IL-10 MUTEINS

20230203117 · 2023-06-29

    Inventors

    Cpc classification

    International classification

    Abstract

    The present disclosure relates to modified forms, or muteins, of IL-10, as well as variants thereof, which display improved features as compared to wild-type IL-10. The present invention further relates to the use of such modified forms, or muteins, of IL-10, as well as variants thereof in methods, including therapeutic methods.

    Claims

    1. An IL-10 mutein, wherein the IL-10 mutein comprises at least one amino acid substitution at positions 18, 92 and 99, as compared to full-length mature wild-type IL-10.

    2. The IL-10 mutein according to claim 1, wherein the IL-10 mutein comprises at least two amino acid substitutions at positions 18, 92 and 99.

    3. The IL-10 mutein according to claim 1, wherein the IL10 mutein comprises amino acid substitutions at all three positions, 18, 92 and 99.

    4. The IL-10 mutein according to claim 1, comprising a substitution at position 18 and the substitution is Y or I (lettering according to recognised one-letter amino acid codes).

    5. The IL-10 mutein according to claim 1, comprising a substitution at position 92 and the substitution is I.

    6. The IL-10 mutein according to claim 1, comprising a substitution at position 99 and the substitution is N.

    7. The IL-10 mutein according to claim 1, comprising one or more further substitutions, but typically less than 10, 9, 8, or 7 substitutions as compared to the wild-type IL-10 sequence.

    8. The IL-10 mutein according to claim 7, wherein said one or more further substitutions is at positions 55, 69, 97, 110, 111 and/or 148.

    9. The IL-10 mutein according to claim 1, wherein the IL-10 mutein is at least 97, 98, 99% or 100% identical to the sequence according to SEQ ID NO:5, 7, 11 or 15, but comprises at least the amino acid substitutions identified in SEQ ID NO:5, 7, 11 or 15, which differ with respect to the corresponding wild-type IL-10 sequence (SEQ ID NO: 1).

    10. A fusion protein comprising an IL-10 mutein according to claim 1, fused to a further different protein molecule or portion of a protein molecule.

    11. The fusion protein according to claim 10, wherein the further molecule is a different cytokine, such as an interleukin (IL) molecule or a wild-type or mutant IL-4 molecule.

    12. (canceled)

    13. The fusion protein according to claim 10, wherein the fusion protein comprises the sequence, which is at least 97, 98, 99%, or 100% identical to the sequence as identified in SEQ ID NO: 17, 19, 21, or 23, but comprises at least the amino acid substitutions identified in SEQ ID NO: 11 which differ with respect to the wild-type IL-10 sequence

    14. The IL-10 mutein according to claim 1, wherein the IL-10 molecule is further modified by PEGylation, phosphorylation, amidation and/or glycosylation.

    15. A pharmaceutical composition comprising an IL-10 mutein according to claim 1, together with a pharmaceutically acceptable excipient.

    16. The pharmaceutical composition according to claim 15 together with a further pharmaceutically active agent, such as an anti-cancer agent, anti-inflammatory agent, or an immune tolerance promoting agent.

    17. The pharmaceutical composition according to claim 16 wherein the further pharmaceutically active agent is an immune cell, such as a CAR T cell, or an anti-cancer or anti-inflammatory antibody.

    18. (canceled)

    19. A method of treating inflammation, autoimmune diseases, graft vs host disease, inflammatory bowel disease/Crohn's disease or cancer; comprising administering the IL-10 mutein, according to claim 1, to a subject in need thereof.

    20. A polynucleotide encoding the IL-10 mutein according to claim 1, such as a DNA or RNA molecule.

    21. A plasmid, virus, cell, lipid nanoparticle, or lipoplex comprising the polynucleotide according to claim 20.

    22. The IL-10 mutein according to claim 1, wherein the IL-10 mutein binds to IL-10Rβ with a Kd which is 100-fold, preferably 1000-fold lower compared to the binding of wild type IL-10 to IL-10Rβ.

    23. The IL-10 mutein according to claim 1, wherein the IL-10 mutein forms a dimer.

    24. The fusion according to claim 10, wherein the IL-10 mutein is fused to at least one polypeptide binding domain, preferably an antibody or fragment thereof, most preferably a single chain antibody, for example a VHH.

    25. The fusion according to claim 24, wherein the polypeptide binding domains binds to at least one checkpoint molecule selected from CD27, CD137, 2B4, TIGIT, CD155, ICOS, HVEM, CD40L, LIGHT, OX40, DNAM-1, PD-L1, PD1, PD-L2, CTLA-4, CD8, CD40, CEACAM1, CD48, CD70, A2AR, CD39, CD73, B7-H3, B7-H4, BTLA, IDO1, ID02, TDO, KIR, LAG-3, TIM-3, and/or VISTA, preferably PD-L1, PD1, wherein the polypeptide binding domains binds to at least one dendritic cell surface marker selected from CD1a, CD1c, CD11c, CD14, CD32b, CD123, CD141, CD206 (MR), CD2007 (Langerin), BDCA-1, BDCA-2, BDCA-3, BDCA-4, CADM1 (Necl2), Clec9A, DEC-205, DC-SIGN, DCIR2 (Clec4A4), LSP-1, SIRP alpha, and/or XCR1, or wherein the polypeptide binding domains binds to at least one inflammatory tissue marker selected from alpha(v) integrins (such as αvβ1, αvβ3, αvβ5 and αvβ8), CHI3L1 (YKL-40), CXCR4, E-Selectin, FAP, EDA and EDB Fibronectin, Galectin-3, ICAM-1, IGF2R (CI-MPR), LFA-1, MadCAM-1 (Adressin), MUC2, MUC4, PDGFR alpha, PDGFR beta, PSGL-1, STRA6 (RBP receptor), and/or VCAM-1.

    26. (canceled)

    27. (canceled)

    28. The fusion protein according to claim 24, wherein the polypeptide binding domains binds to at least one microglia marker selected from CD11b, CD40, CD45, CD68, CX3CR1, EMR1 (F4/80), Iba1, and/or TMEM19.

    29. The fusion protein according to claim 24, wherein the polypeptide binding domains binds to at least one tumor antigen selected from EpCAM, EGFR, HER-2, HER-3, c-Met, FoIR, PSMA, CD38, BCMA, CEA, 5T4, AFP, B7-H3, Cadherin-6, CAIX, CD117, CD123, CD138, CD166, CD19, CD20, CD205, CD22, CD30, CD33, CD40, CD352, CD37, CD44, CD52, CD56, CD70, CD71, CD74, CD79b, CLDN18.2, DLL3, EphA2, ED-B fibronectin, FAP, FGFR2, FGFR3, GPC3, gpA33, FLT-3, gpNMB, HPV-16 E6, HPV-16 E7, ITGA2, ITGA3, SLC39A6, MAGE, mesothelin, Muc1, Muc16, NaPi2b, Nectin-4, P-cadherin, NY-ESO-1, PRLR, PSCA, PTK7, ROR1, SLC44A4, SLTRK5, SLTRK6, STEAP1, TIM1, Trop2, and/or WT1

    30. The fusion according to claim 24, wherein the IL-10 mutein is fused to half-life extending molecule, preferably an immunoglobulin fragment such as an Fc molecule, or a polypeptide binding domain against a blood serum protein, preferably against albumin.

    Description

    [0066] The present invention will now be further described by way of example and with reference to the figures, which show:

    [0067] FIG. 1. Generation of high affinity IL-10 variants by yeast surface display. A. Schematic of IL-10 stepwise receptor assembly for IL-10 dimer (top panel) and IL-10 monomer (bottom panel). B. Schematic of IL-10 dimer and IL-10 monomer secondary structure organisation as described by (Walter, 2014, Josephson et al., 2000). Extended linker region is highlighted in blue. C. Representation of IL-10 displayed on yeast cell surface and screening using fluorescently labelled recombinant IL-10Rβ. D. Yeast displayed wild type IL-10 IL-10Rα binding (panel 2) and IL-10Rβ binding in the absence (panel 3) or presence (panel 4) of IL-10Rα. Unstained control shown in panel 1. E. Outline of ligand conditions used in each yeast display selection round. Selection rounds started at 1 μM IL-10Rβ with 100 nM non-biotinylated IL-10Rα and finishing with 20 nM IL-10Rβ alone. F. Representative histogram of IL-10Rβ binding (AF647) of yeast displayed wild type IL-10, round 3 selection, round 6 selection and round 8 selection. As the library selection proceeds the IL-10RP staining improves. G. The highest IL-10Rβ concentration is 1 μM with a ⅓ serial fold dilution over 7 concentrations. Non-biotinylated IL-10Rα was added at 100 nM to improve cooperative binding. H. Table for amino acid changes found in high affinity mutants. Wild type sequence is show in yellow. Conserved changes between mutants are shown in blue. Individual mutations are shown in white. I. Panel one depicts the wild type IL-10 structure with helices A and D emphasised in red as the area predicted by (Mendoza et al., 2017) to be the IL-10Rβ binding site. Panel 2 shows the structures for the high affinity variant R5A11 with mutations highlighted in purple I Dose response for IL-10Rβ binding for G3 clone from yeast display library.

    [0068] FIG. 2. Increased IL-10Rβ binding affinity enhances IL-10 receptor dimerization. (a). Quantifying receptor dimerization in the plasma membrane by dual-colour single molecule SUBSTITUTE SHEET (RULE 26) colocalization and co-tracking. IL-10Rα and IL-10Rβ with N-terminally fused variants of monomeric ECFP and EGFP, respectively, were labelled with nanobodies EN.sup.AT643 and MI.sup.Rho11, respectively. (b). Trajectories of IL-10Rα (blue), IL-10Rβ (red) and co-localized IL-10Rα:IL-10Rβ (magenta) in the absence of IL-10 (left column) and in the presence of WTD (middle column) and R5A11D (right column), respectively. (c). Heterodimerization of IL-10Rα and IL-10Rβ (left), and homodimerization of IL-10Rα (center) and IL-10Rb (right) induced by dimeric IL-10 variants quantified by co-locomotion analysis. Each data point represents a cell with the number of cells of each experiments indicated in the box plot. (d). Homo- and heterodimerization of IL-10Rα and IL-10Rβ induced by monomeric IL-10 variants quantified by co-locomotion analysis.

    [0069] FIG. 3. High affinity variants improve signalling capabilities of IL-10 in monocytes. A. Monocytes were isolated from human buffy coat samples by CD14 positive MACS selection. Cells were rested in M-CSF containing media for 2 days. Cells were then stimulated with IL-10 for 24 hours before analysis. B. Dose response of pSTAT3 and pSTAT1 in IL-10 treated monocytes. Cells were stimulated with IL-10 wild type and high affinity variants for 15 minutes. Activation of STAT3 and STAT1 was analysed by phospho-flow cytometry. Sigmoidal curves were fitted with GraphPad Prism software. Data shown is the mean of five biological replicates with error bars depicting standard error of the mean. Each biological replicate is normalised by assigning the highest MFI value of the top concentration as 100% and the lowest MFI value of an untreated control as 0%. C. Log.sub.10 EC50 values for pSTAT1 and pSTAT3 from dose response curves in B. Each point represents one biological replicate with line at the mean and error bars show the mix to max of all points. D. Ratio of pSTAT1 to pSTAT3 in IL-10 stimulated monocytes. Ratio was calculated by taking the percentage activation of pSTAT3 and pSTAT1 at 40 nM for five biological replicates and dividing pSTAT1 by pSTAT3 values. Each point represents one biological replicate with line at the mean and error bars show the min to max of all points. E. Kinetics of pSTAT3 and pSTAT1 induced by IL-10. Monocytes were stimulated with IL-10 for the indicated time periods before fixation. Data shown is the mean of four biological replicates with error bars depicting standard error of the mean. Each biological replicate is normalised by assigning the highest MFI value at 15 mins as 100% and the lowest MFI value of an untreated control as 0%. F. Measurement of H LA-DR cell surface expression in monocytes after 24 hours IL-10 treatment. Each point represents one biological replicate (n=4) and error bars indicate the standard deviation. Fold change is calculated for each biological replicate by dividing the MFI of the treated samples by a non-IL-10 treated control (unstimulated). G. Monocytes were stimulated with LPS for 8 hours in the presence of IL-10. Each point represents one biological replicate (n=3) and error bars indicate the standard error of the mean. P value calculated by two-tailed ratio paired t-test.

    [0070] FIG. 4. Characterisation of transcriptional activity induced by IL-10 and high affinity variants in human monocytes. A. Schematic of monocyte stimulation. CD14 positive cells were isolated from three human buffy coats by MACS and rested in M-CSF containing media for two days before twenty-four hours stimulation with IL-10 wild type and high affinity variants. B. Volcano plot of monocyte genes significantly upregulated by IL-10 wild type dimer ≥0.6 log.sub.2 fold change (red) and significantly downregulated ≤−0.6 log.sub.2 fold change compared to non-IL-10 stimulated cells. Fold change was calculated by dividing WTD 50 nM by unstimulated values for each donor. The average fold change was calculated and the log.sub.2 of this value is plotted. P values ≤0.05 were calculated by two-tailed unpaired t-test of the log.sub.2 fold change of WTD 50 nM/unstimulated genes for each donor. Genes which were not significantly changed or were ≤0.6≥−0.6 log.sub.2 fold change were excluded. C. Proportion of monocyte genes significantly regulated by WTD 50 nM ≥0.6 or ≤−0.6 log.sub.2 fold change compared to unstimulated cells. D. Log.sub.2 fold change for the top 20 protein coding genes significantly up (red) and down (blue) regulated by WTD 50 nM in monocytes. E. Percentage activity of low dose WTD compared to high dose WTD. The log.sub.2 fold change of WTD 0.1 nM was divided by WTD 50 nM and multiplied by 100. Genes which showed 75% of high dose activity (183 genes) are highlighted in red. Insert shows the percentage of these genes which up or downregulated activity. F. Gene ontology biological processes analysis for the 183 genes which were sensitive to changes in WTD concentration. G.Log.sub.2 fold change for inflammatory cytokines and chemokine genes for WTD 50 nM and 0.1 nM. H. Heatmap of genes significantly up or down regulated by WTD 50 nM ≥0.6 or ≤−0.6 log.sub.2 fold change and their corresponding log.sub.2 fold change by R5A11D 50 nM, WTD 0.1 nM, R5A11D 0.1 nM, R5A11M 50 nM and WTM 50 nM compared to unstimulated control cells. Values are the mean of three donors. Heat map cluster analysis generated in R studio. I. Volcano plot of genes regulated by WTD (blue) and R5A11D (green) at 0.1 nM concentration each. Only genes which had already been showed to be significantly up or down regulated by WTD 50 nM are plotted. J. Heatmap of the top 10 up and down regulated genes by WTD 0.1 nM compared to R5A11D 0.1 nM. K. Heatmap of inflammatory cytokine and chemokine genes regulated by WTD at 50 nM and 0.1 nM and R5A11D 0.1 nM.

    [0071] FIG. 5. High affinity variants improve signalling capabilities of IL-10 in human CD8 T cells. A. PBMCs were isolated from human buffy coat samples and CD8 cells were purified by CD8 positive MACS selection. PBMCs or purified CD8 cells were activated for three days using soluble anti-CD3 (100 ng/mL) (PBMCs) or anti-CD3/anti-CD28 beads (CD8 cells) with IL-2 (20 ng/mL) in the presence or absence of IL-10. On day 3 activation media was removed and the cell populations were placed in media containing IL-2 plus/minus IL-10 for a further 2-3 days before analysis. B. Dose response of pSTAT3 and pSTAT1 in activated CD8 cells in a PBMC population (activated in the absence of IL-10). Cells were placed in media with no IL-2 overnight before stimulation with IL-10 wild type and mutants for 15 minutes. Data shown is the mean of four biological replicated with error bars depicting standard error of the mean. Each biological replicate is normalised by assigning the highest MFI value of the top concentration as 100% and the lowest MFI value of an untreated control as 0%. C. Log EC50 values for pSTAT3 and pSTAT1 from dose response curves in B. Each point represents one biological replicate with line at the mean and bars represent the mix to max of all points. D. Ratio of pSTAT1 to pSTAT3 in IL-10 stimulated CD8 cells in a PBMC population. Ratio was calculated by taking the percentage activation of pSTAT3 and pSTAT1 at 40 nM for four biological replicates and dividing pSTAT1 by pSTAT3 values. Each point represents one biological replicate with line at the mean and error bars denote mix to max of all points. E. Kinetics of pSTAT3 and pSTAT1 induced by IL-10. Non-activated CD8 cells in a PBMC population were stimulated with IL-10 for the indicated time periods before fixation. Data shown is the mean of three biological replicates with error bars depicting standard error of the mean. Each biological replicate is normalised by assigning the highest MFI value at 15 mins as 100% and the lowest MFI value of an untreated control as 0%. F. Granzyme B protein in activated CD8 T cells in the presence of IL-10. CD8 T cells in a PBMC population were grown and stimulated as shown in A. Cells were then fixed and permeabilised and granzyme B protein was quantified by flow cytometry. Fold change was calculated by normalised to a non-IL-10 treated control for each donor. Each point represents one biological replicate (n=8) and error bars indicate the standard deviation.

    [0072] FIG. 6. Characterisation of transcriptional activity induced by IL-10 and high affinity variants in human CD8 T cells. A. Schematic of CD8 T cell stimulation. CD8 T cells were isolated by MACS and activated with anti-CD3/CD28 beads and IL-2 in the presence or absence of IL-10 wt and variants for three days. On day three the media was changed to IL-2 in the presence or absence of IL-10 wt and variants and cells were expanded for a further three days. B. Volcano plot of CD8 T cell genes significantly upregulated by IL-10 wild type dimer ≥0.6 log.sub.2 fold change (red) and significantly downregulated ≤−0.6 log.sub.2 fold change compared to non-IL-10 stimulated cells. Fold change was calculated by dividing WTD 50 nM by unstimulated values for each donor. The average fold change was calculated and the log.sub.2 of this value is plotted. P values ≤0.05 were calculated by two-tailed unpaired t test of the log.sub.2 fold change of WTD 50 nM/unstimulated genes for each donor. Genes which were not significantly changed or were ≤0.6≥−0.6 log.sub.2 fold change were excluded. C. Proportion of CD8 T cell genes significantly regulated by WTD 50 nM ≤0.6 or ≤−0.6 log.sub.2 fold change compared to unstimulated cells. D. Log.sub.2 fold change for the top 20 protein coding genes significantly up (red) and down (blue) regulated by WTD 50 nM in CD8 T cells. E. Heatmap of genes previously reported to be present in exhausted T cells. A list of exhaustion specific genes from (Bengsch et al., 2018) was used as a comparison for genes significantly up or down regulated by WTD 50 nM. Previously reported genes were given a nominal value of 1 for upregulated genes and −1 for downregulated genes. Log.sub.2 fold change for WTD 50 nM was plotted. Cluster 1 (C1) represents genes upregulated in exhausted cells and upregulated by WTD 50 nM. C2 represents genes upregulated in exhausted cells and downregulated by WTD 50 nM. C3 represents genes downregulated in exhausted cells and upregulated by WTD 50 nM. C4 represents genes downregulated in exhausted cells and downregulated by WTD 50 nM. F. The log.sub.2 fold change induced by WTD 50 nM for a sample of genes from each cluster is shown. G. The RKPM of unstimulated and WTD 50 nM conditions for the IL2RA gene in each donor. H. Heatmap showing the log.sub.2 fold change induced by WTD 50 nM for genes previously reported to be regulated by IL-2 (Rollings et al., 2018). I. Percentage activity of low dose WTD compared to high dose WTD. The log.sub.2 fold change of WTD 0.1 nM was divided by WTD 50 nM and multiplied by 100. Genes which showed ≤75% of high dose activity (781 genes) are highlighted in red. Insert shows the percentage of these genes which up or downregulated activity. J. Log.sub.2 fold change for genes associated with exhaustion or IL-2 stimulation and their regulation of WTD at 50 nM or 0.1 nM concentration. K. Heatmap of genes significantly up or down regulated by WTD 50 nM ≥0.6 or ≤−0.6 log.sub.2 fold change and their corresponding log.sub.2 fold change by R5A11D 50 nM, WTD 0.1 nM, R5A11D 0.1 nM, R5A11M 50 nM and WTM 50 nM compared to unstimulated control cells. Values are the mean of three donors. L. Volcano plot of genes regulated by WTD (blue) and R5A11D (green) at 0.1 nM concentration each in CD8 T cells. Only genes which had already been showed to be significantly up or down regulated by WTD 50 nM are plotted. J. Comparison of regulation of CD8 T cell genes by R5A11D 0.1 nM and WTD 0.1 nM. The log.sub.2 fold change of R5A11D 0.1 nM/unstimulated was divided by the log.sub.2 fold change of WTD 0.1 nM/unstimulated. Proportion of genes which show enhanced regulation by R5A11D are shown in red, proportion of genes which show diminished regulation by R5A11D are shown in blue and genes which do not change between R5A11D and WTD are shown in grey. M. Heatmap of the top 10 up and down regulated CD8 T cell genes by WTD 0.1 nM compared to R5A11D 0.1 nM. N. Heatmap of exhaustion or IL-2 associated genes regulated by WTD at 50 nM and 0.1 nM and R5A11D 0.1 nM.

    [0073] FIG. 7. Comparison of common gene regulation by IL-10 in monocytes and CD8 T cells. A. Venn diagram comparing genes significantly up or down regulated by wild type IL-10 (50 nM) in monocytes and CD8 T cells. Venn diagram generated using “Venny” (Oliveros, 2007-2015). B. Comparison of the 181 genes regulated by IL-10 in both cell subsets. The log.sub.2 fold change for each gene of WTD (50 nM)/unstimulated in both CD8 T cells and monocytes are plotted. Genes which are upregulated by IL-10 in both cell types are denoted as cluster 1 (C1). Genes upregulated by IL-10 in CD8 T cells but downregulated by IL-10 in monocytes are grouped in cluster 2 (C2). Genes which are upregulated by IL-10 in monocytes but downregulated by IL-10 in CD8 T cells are grouped in cluster 3 (C3). Genes downregulated by IL-10 in both monocytes and CD8 T cells are denoted by cluster 4 (C4). C. Examples of genes from each cluster. The log.sub.2 fold change of WTD (50 nM)/unstimulated in both CD8 T cells and monocytes are plotted. Each point represents one biological replicate and error bars represent the standard deviation.

    [0074] FIG. 8. Recombinant expression of wild type and high affinity IL-10 monomeric and dimeric variants. A. FPLC chromatogram for wild type and mutant monomer and dimer. Proteins were run on an S200 gel filtration column and separation by size exclusion. B. Coomassie gel of FPLC purified proteins run on 10% gel.

    [0075] FIG. 9. Biophysical characterisation of high affinity IL-10 variants A. For biacore measurement IL-10Rβ is immobilised on the chip surface via biotin-streptavidin interaction and IL-10 variants are flowed across the chip in solution. B and G. Kinetic charts for IL-10Rβ binding for wild type and high affinity IL-10 with inserts for affinity curves. Concentrations used are shown on curves. C. K.sub.D values for IL-10Rβ binding for wild type and high affinity variants. D. IL-10Rβ is immobilised on the chip surface and IL-10 variants pre-bound to IL-10Rα are flowed across the chip surface in solution. Concentrations used are shown on curves. G. Kinetics for IL-10Rβ binding in the presence of IL-10Rα. F and H K.sub.D values for IL-10Rβ binding when IL-10 proteins are pre-bound to IL-10Rα.

    [0076] FIG. 10. Single molecule imaging of IL-10 receptors by TIRF microscopy: A. Cell surface receptor density of ectopically expressed IL-10Rα (blue) and IL-10Rβ (red). n=20 cells. B. Diffusion coefficients of IL-10Rα (blue), IL-10Rβ (red) and co-locomoting receptors (magenta) in absence or presence of dimeric and monomeric IL-10 variants. WTD: n=20 cells; R5A11D: n=16 cells, WTM: n=19 cells, R5A11M: n=18 cells, unstimulated: n=10 cells.

    [0077] FIG. 11. Extended kinetics of IL-10 and variants in human monocytes. 3-day monocyte pSTAT3/1 kinetics. Monocytes were stimulated with IL-10 for the indicated time periods before fixation. Data shown is the mean of four biological replicates with error bars depicting standard error of the mean. Each biological replicate is normalised by assigning the highest MFI value at 15 mins as 100% and the lowest MFI value of an untreated control as 0%.

    [0078] FIG. 12. Analysis of gene expression profiles induced by IL-10 wild type and high affinity variants in human monocytes. A. KEGG and GO pathway analysis for genes significantly up or down regulated by WTD 50 nM ≥0.6 or ≤−0.6 log.sub.2 fold change in human monocytes. Pathway analysis done using DAVID Bioinformatics Resource functional annotation tool (Huang da et al., 2009a, Huang da et al., 2009b). B. Heatmap showing log.sub.2 fold change expression by WTD (50 nM) stimulation for a selection of metabolic pathways, cytokine & chemokine, CD and interferon related genes. C. Comparison of log.sub.2 fold change in expression for genes by WTD, WTM and R5A11M at 50 nM and WTD and R5A11D at 0.1 nM concentration. D. Comparison of regulation of monocyte genes by R5A11M 50 nM and WTD 50 nM. The log.sub.2 fold change of R5A11M 50 nM/unstimulated was divided by the log.sub.2 fold change of WTD 50 nM/unstimulated. Proportion of genes which show enhanced regulation by R5A11M are shown in red, proportion of genes which show diminished regulation by R5A11M are shown in blue and genes which do not change between R5A11M and WTD are shown in grey. E. Comparison of regulation of genes by R5A11D 0.1 nM and WTD 0.1 nM. The log.sub.2 fold change of R5A11D 0.1 nM/unstimulated was divided by the log.sub.2 fold change of WTD 0.1 nM/unstimulated. Proportion of genes which show enhanced regulation by R5A11D are shown in red, proportion of genes which show diminished regulation by R5A11D are shown in blue and genes which do not change between R5A11D and WTD are shown in grey.

    [0079] FIG. 13. Characterisation of the IL-10 treated CD8 T cell phenotype. A. CD8 cells within a PBMC population and purified CD8 cells were stained for CD69 after 24 hours activation and for CD71 after 6 days activation and expansion. Exhaustion markers PD-1 and LAG3 were analysed after 6 days activation and expansion. Fold change was calculated by dividing IL-10 stimulated MFI values by non-IL-10 stimulated controls for each donor. Each point represents one donor. B. Proliferation of CD4 and CD8 T cells in a PBMC population were analysed after 6 days of activation/expansion. Cell counts for CD4+ and CD8+ cells were taken and fold change was calculated by dividing IL-10 treated cells by a non-IL-10 treated control population from the same donor. Each point represents one biological replicate and p values were calculated using a two tailed paired t test. C. CD8 T cells in a purified population were stained for granzyme B. Fold change of granzyme B was calculated by normalising within each biological replicate to a non-IL-10 treated control (TCR stimulated) for both CD8 cells in a PBMC population and purified CD8 cells. mRNA was isolated from a purified CD8 cell population and gzmb mRNA was quantified by RT qPCR. Fold change was calculated by dividing by a non-IL-10 treated control. Each point represents a biological replicate and p values were calculated using two tailed paired t test.

    [0080] FIG. 14. Analysis of gene expression profiles induced by IL-10 wild type and high affinity variants in human CD8 T cells. A. KEGG and GO pathway analysis for genes significantly up or down regulated by WTD 50 nM ≥0.6 or ≤−0.6 log.sub.2 fold change in human CD8 T cells. Pathway analysis done using DAVID Bioinformatics Resource functional annotation tool (Huang da et al., 2009a, Huang da et al., 2009b). B. Heatmap comparison of regulation of cytokines & chemokines, CD markers, IL-2 related and MAPK signalling genes by WTD, WTM and R5A11M at 50 nM and WTD and R5A11D at 0.1 nM. C. The log.sub.2 fold change of R5A11M 50 nM/unstimulated was divided by the log.sub.2 fold change of WTD 50 nM/unstimulated. Proportion of genes which show enhanced regulation by R5A11M are shown in red, proportion of genes which show diminished regulation by R5A11M are shown in blue and genes which do not change between R5A11M and WTD are shown in grey. D. Comparison of regulation of genes by R5A11D 0.1 nM and WTD 0.1 nM. The log.sub.2 fold change of R5A11D 0.1 nM/unstimulated was divided by the log.sub.2 fold change of WTD 0.1 nM/unstimulated. Proportion of genes which show enhanced regulation by R5A11D are shown in red, proportion of genes which show diminished regulation by R5A11D are shown in blue and genes which do not change between R5A11D and WTD are shown in grey.

    [0081] FIG. 15 Generation of pentameric IL-10 and fusion versions of IL-10 with IL-4 wt and mutant forms. A. A gel showing the generation of the pentameric form of IL-10 mutein. B. A gel showing the generation of various IL-10 mutein/IL-4 fusions.

    [0082] FIG. 16 CAR T experiments using WT and IL-10 muteins. A. A graph showing the effect increasing concentrations of wt IL-10 and IL-10 mutein has on CAR Tin vitro tumour viability, as compared to IL-2. B. A graph showing interferon gamma production by CAR T cells following addition of wt and mutant forms of IL-10.

    [0083] Material and Methods

    [0084] Protein Expression and Purification

    [0085] Monomeric wild type IL-10 (Josephson et al., 2000), monomeric high affinity variants and IL-10Ra ectodomain (amino acids 22-235) were cloned and expressed as described in (Martinez-Fabregas et al., 2019). Briefly, protein sequences were cloned into the pAcGP67-A vector (CD Biosciences) in frame with an N-terminal gp67 signal sequence, driving protein secretion, and a C-terminal hexahistidine tag. The baculovirus expression system was used for protein production as outlined in (LaPorte et al., 2008). Spodoptera frugiperda (SF9) cells, grown in SF90011 media (Invitrogen), were transfected to produce Po baculovirus stocks that were then expanded in SF9 cells to produce Pi virus stock. Protein expression was performed using Trichoplusiani ni (High Five) with cells grown in InsectXpress media (Lonza).

    [0086] Purification was performed using the method described in Sprangler et al (2019). Briefly, the cells were pelleted with centrifugation at 2000 rpm, prior to a precipitation step through addition of Tris pH 8.0, CaCl.sub.2 and NiCl to final concentrations of 200 mM, 50 mM and 1 mM. The precipitate formed was then removed through centrifugation at 6000 rpm. Nickel-NTA agarose beads (Qiagen) were added and the target proteins purified through batch binding followed by column elution in HBS, 200 mM imidazole, pH 7.2. Target proteins were concentrated and further purified by size exclusion chromatography on an ENrich SEC 650 300 column (Biorad), equilibrated in 10 mM HEPES (pH 7.2), 150 mM NaCl. IL-10Rα was biotinylated using EZ=Link NHS biotinylation kit (Thermo) according to the manufacturer's protocols.

    [0087] For expression of biotinylated IL-10Rβ the ectodomain (amino acids 20-220) was cloned into the pAcGP67-A vector carrying a C-terminal biotin acceptor peptide (BAP)-LNDIFEAQKIEWHW followed by a hexahistidine tag. The purified protein was biotinylated with BirA ligase.

    [0088] For expression of dimeric wild type IL-10 and dimeric high affinity variants, synthesised gene blocks (IDT) were cloned into the pET21 vector in frame with an N-terminal hexahistidine tag and a lac promotor, and transformed into E. Coli BL21 cells. Protein production was induced using 1 mM final concentration of IPTG (Formedium) followed by incubation at 37° C. for 3 to 5 hours. Cells were harvested by centrifugation at 6000×g for 15 minutes. The cell pellets were resuspended in 50 mM Tris-HCl (pH 8.0), 25% (w/v) sucrose, 1 mM Na EDTA, 10 mM DTT, 0.2 mM PMSF per litre of original culture and frozen at −80° C. overnight.

    [0089] The recombinant protein was expressed as inclusion bodies, purification of which was performed as follows. Cells were lysed in 100 mM Tris-HCl (pH 8.0), 2% (v/v) TritonX-100, 200 mM NaCl, 2500 units Benzonase, 10 mM DTT, 5 mM MgCl2, 0.2 mM PMSF and incubated for 20 minutes with stirring at room temperature. 10 mM EDTA final concentration was then added to the suspension and the cells were sonicated (8-10 cycles of 15 seconds on/off, 15 microns, Soniprep 150) in an ice bath. The solution was centrifuged at 7000×g for 15 mins (4° C.) and resuspended in 50 mM Tris-HCl pH 8.0, 0.5% Triton X-100, 100 mM NaCl, 1 mM Na EDTA, 1 mM DTT, 0.2 mM PMSF. This step was repeated for a total of at least three washes until the preparation appeared white. The final pellet was then washed once in detergent free buffer (50 mM Tris-HCl pH 8.0, 1 mM Na EDTA, 1 mM DTT, 0.2 mM PMSF).

    [0090] The purified inclusion bodies were solubilised in 10 mls of 6M GuHCl per litre of original culture, for 30 minutes at room temperature. The solution was clarified by a centrifugation at 7000 rcf for 15 minutes and the solubilised protein carefully decanted. Refolding was performed through dropwise addition of the solubilised protein solution into refolding buffer (50 mM Tris-HCl, pH 8.0, 50 mM NaCl, 5 mM EDTA, 2 mM reduced glutathione (GSH) and 0.2 mM oxidized glutathione (GSSG)) at a ratio of 1:20 solution:buffer at 4° C. followed by incubation with gentle stirring overnight at 4° C.

    [0091] The solution was then filtered to remove any precipitant and dialysis performed against 10 mM HEPES (pH 7.2), 150 mM NaCl, using dialysis membrane with a 14 kDa Mwt cut off.

    [0092] After dialysis protein was then further purified using Ni-NTA beads and by size exclusion on a Superdex75 increase 10/300 column (GE Healthcare). Endotoxin removal was then performed. 1 mL of Ni-NTA agarose was added to a polyprep column and equilibrated with 10 mls of HBS before addition of the protein. The column was washed with 50 column volumes of ice-cold HBS, 150 mM NaCl, 20 mM imidazole, 0.1% Triton-X114 (pH X) to remove endotoxin. The column was then washed with a further 20 column volumes of HBS, 20 mM imidazole (pH X). The now endotoxin-free protein was eluted using 4 column volumes of HBS, 200 mM imidazole (pH X). The protein was buffer exchanged into 10 mM HEPES, 150 mM NaCl (pH 7.2), using PD-10 columns (GE Healthcare). Endotoxin levels were measured using Pierce LAL Chromogenic Endotoxin Quantitation Kit (Thermo) following the manufacturer's protocol. For all proteins endotoxin levels were below detection levels of the kit.

    [0093] Surface Plasmon Resonance

    [0094] Surface plasmon resonance was used to determine the binding affinity of the recombinantly produced monomeric IL-10 wild type and variants to IL-10Rβ in the presence or absence of IL-10Rα. Biotinylated IL-10Rβ was immobilised onto the chip surface via streptavidin. Series S Sensor SA (GE Healthcare) chips were primed in 10 mM HEPES, 150 mM NaCl, 0.02% TWEEN-20, prior to immobilisation of the biotinylated receptor. Analysis runs were then performed in 10 mM HEPES, 150 mM NaCl, 0.05% TWEEN-20 and 0.5% BSA. A Biacore T100 (T200 Sensitivity Enhanced) was used for measurement with Biacore T200 Evaluation Software 3.0 used for data analysis.

    [0095] Cell Culture

    [0096] Human buffy coats were obtained from the Scottish Blood Transfusion Service and peripheral blood mononuclear cells (PBMCs) were isolated by density gradient centrifugation (Lymphoprep, StemCell Technologies). PBMCs were grown in RPMI-1640, 10% v/v FBS, 100 U/mL penicillin-streptomycin (Gibco) and cytokines for proliferation and activation. For three days media was supplemented with 100 ng/mL anti-CD3 (human UltraLEAF, Biolegend) and 20 ng/mL IL-2 (Proleukin, Novartis) in the absence or presence of IL-10 variants. After three days activation cells were centrifuged and resuspended in media supplemented with 20 ng/mL of IL-2 plus or minus IL-10 variants. Cell populations were allowed to expand for 2-3 days.

    [0097] Monocytes were isolated from PBMC populations using CD14 positive selection. Anti-CD14.sup.FITc antibody (Biolegend #367116) was used to stain cells and isolation was done by magnetic separation following manufacturer's protocol (MACS Miltenyi). Monocytes were then cultured in complete RPMI (as above) supplemented with M-CSF (20 ng/mL, Biolegend). Cells were then stimulated with IL-10 variants for twenty-four hours before analysis.

    [0098] CD8 T cells were isolated from PBMCs by magnetic separation (MACS Miltenyi) after staining with anti-CD8a.sup.FITC antibody (Biolegend #30906). For activation of purified CD8 T cells ImmunoCult Human CD3/CD28 T cell Activator (Stem Cell) was used following manufacturer's protocol as well as the addition of 20 ng/mL IL-2 and IL-10 variants. Cells were activated for 3 days and then the media was replaced with complete RPMI supplemented with 20 ng/mL IL-2 as well as IL-10 variants for 2-3 days.

    [0099] Flow Cytometry Staining and Antibodies

    [0100] For live cell surface staining of HLA-DR.sup.PE (Biolegend #307605) non-adherent monocytes were removed from culture by centrifugation and resuspension in cold PBS. Adherent monocytes were detached using Acutase (StemCell Technologies) at room temperature for 5 to 10 minutes. Cells were kept at 4° C. or on ice during live cell surface marker staining and staining was done in 96-well v-bottom plates (Griener) unless otherwise stated. Non-adherent and detached cells were combined and resuspended in FcR blocking reagent (Miltenyi) for 10 minutes at 4° C. in a volume of 50 μL per condition. Cells were washed in PBS/0.5% BSA and resuspend in 50 μL of antibody mixture diluted 1/100 in FcR blocking reagent. Antibody incubation was done for 30 to 60 minutes at 4° C. in the dark. Cells were washed twice before resuspension in 100 μL per well for analysis on the CytoFlex flow cytometer (Beckman Coulter). Mean fluorescence intensity (MFI) was quantified for all populations. Data was normalised within each donor by dividing MFI of IL-10 treated cells by a non-IL-10 treated control from the same donor to calculate fold change.

    [0101] For granzyme B intracellular staining either PBMCs or CD8 cells on day 6 of activation were fixed with 2% paraformaldehyde for 10 minutes at room temperature before washing in PBS. Cells were permeabilised in 0.1% Triton-X100/PBS for 10 minutes and washed in PBS/0.5% BSA. Cells were stained with anti-CD8a.sup.AlexaFluor700 (Biolegend #300920), anti-CD4.sup.PE (Biolegend #357404), anti-CD3.sup.BrilliantViolet510 (Biolegend #300448) and anti-granzyme B.sup.FITC (Biolegend #515403) at 1/100 dilution for one hour before washing. MFI was quantified for all populations and normalisation was done as described above.

    [0102] For phospho-flow analysis of STAT1 and STAT3 cells were plated at 50 μL of cell suspension per well at a density of 2×10.sup.4 cells per well in 96-well V bottom plates. For does response studies cells were simulated with 7-fold serially diluted IL-10 variants and an unstimulated control (50 μL per well) for 15 minutes at 37° C. before fixation with 2% paraformaldehyde for 10 minutes at room temperature. For kinetic studies, cells were stimulated with a saturating concentration of IL-10 variants (50 nM) at defined time points before fixation simultaneously with 2% paraformaldehyde. Cells were washed in PBS and permeabilised in ice-cold 100% methanol and incubated on ice for a minimum of 30 minutes. Cells were fluorescently barcoded as described in (Krutzik and Nolan, 2006; Martinez-Fabregas et al., 2019). Briefly, a panel of 16 combinations of two NHS-dyes (Pacific Blue and DyLight800, Thermo) were used to stain individual wells on ice for 35 minutes before stopping the reaction by washing in PBS/0.5% BSA. Once barcoded the 16 populations were be pooled together for antibody staining. PBMCs, CD8 cells and monocytes were stained with the cell surface markers described above as well as anti-pSTAT3.sup.Alexa488 (Biolegend #651006) and anti-pSTAT1.sup.Alexa647 (Cell Signalling Technologies #8009). During acquisition individual populations were identified according to the barcoding pattern and pSTAT3.sup.Alexa488 and pSTAT1.sup.Alexa647 MFI was quantified for all populations. MFI was plotted and sigmoidal dose response curves were fitted using Prism software (Version 7, GraphPad). Data was normalised by assigning the highest MFI of the top concentration of all stimuli as 100% and the lowest MFI as 0% within each donor group.

    [0103] Yeast Display Library

    [0104] Yeast surface display protocol was adapted from previous protocols (Boder and Wittrup, 1997; Martinez-Fabregas et al., 2019). To create an IL-10 yeast display library the monomeric IL-10 gene (Josephson et al., 2000) was subject to error-prone PCR as described in (Mendoza et al., 2017). This product was then amplified and transformed along with a linearized pCT302 vector into the Saccharomyces cerevisiae stain EBY100 and grown in selective dextrose casamino acids (SDCAA) media at 30° C. for two days. Yeast cells were then place in selective galactose casamino acids (SGCAA) at 20° C. for two days to induce cell surface expression of IL-10 variants as described in (Chao et al., 2006). Magnetic activated cell sorting (MACS, Miltenyi) was used to select for IL-10 variants with increased binding affinity for IL-10Rβ as described previously for other systems (Moraga et al., 2015b). Briefly, the first round of selection was performed using high concentrations of streptavidin beads to remove any yeast which displayed variants capable of binding streptavain. The second round of selection selected for yeast which display variants with the c-myc tag at their C-terminus, ensuring that displayed proteins were properly folded. The subsequent rounds of selection were carried out by incubating induced yeast with decreasing concentrations of recombinantly produced biotinylated IL-10Rβ for 2 hours followed by a 15 minute incubation with fluorescently labelled streptavidin (AlexaFluor647). Magnetic activated cell sorting (MACS, Miltenyi) selected for yeast which displayed IL-10 variants capable of binding IL-10Rβ. Once the concentration of IL-10Rβ needed for binding was decreased sufficiently compared to wild type monomeric IL-10, the yeast were plated on SDCAA agar and single colonies were isolated for dose response studies to determine the EC50 values of the mutants.

    [0105] Yeast colonies displaying promising IL-10 variants were subject to Zymoprep (ZymoResearch) to isolate the plasmid which was then heat shocked into competent DH5a E. coli and plasmids were sequenced to observe where mutations had occurred in the monomeric IL-10 gene. These genes were then cloned into the baculovirus expression vector pACgp67BN and recombinantly expressed as described above.

    [0106] Measurement of IL-6 Secretion

    [0107] Monocytes were stimulated with LPS (100 ng/mL) (E. coli 026:B6, Sigma) plus IL-10 variants at various concentration for 8 hours. Supernatant was then removed and used for enzyme linked immunosorbent assay (ELISA) for IL-6 detection (Biolegend, #430501). Manufacturer's protocol was followed. 96-well half-area plates (Sigma) were coated in capture antibody and incubated overnight at 4° C. Plates were washed in PBS/0.05% Tween-20 and blocked for 1 hour in assay diluent and washed. Supernatant was diluted 1 to 10 in assay buffer before addition to the plate. The plates were incubated at room temperature for two hours with shaking. Plates were washed again and incubated for 1 hour with detection antibody. After washing, avidin-HRP was added and incubated for 30 minutes followed by incubation with TMB substrate solution for 15 minutes. The reaction was stopped by addition of H.sub.2SO.sub.4 and absorbance was measured at 450 nm and 570 nm with absorbance at 570 nm being subtracted from 450 nm.

    [0108] RNA Transcriptome Sequencing

    [0109] Human primary monocytes and CD8 T cells from three donors each (StemCell Technologies) were stimulated as described in above. Cells were washed in Hank's balanced salt solution (H BSS, Gibco) and snap frozen for storage. RNA was isolated using the RNeasy Kit (Quiagen) according to manufacturer's protocol. All RNA 260/280 ratios were above 1.9. 1 μg of RNA was used per sample. Transcriptomic analysis was done by Novogene as follows. Sequencing libraries were generated using NEBNext® Ultra™ RNALibrary Prep Kit for Illumina® (NEB, USA) following manufacturer's recommendations and index codes were added to attribute sequences to each sample. Briefly, mRNA was purified from total RNA using poly-T oligo-attached magnetic beads. Fragmentation was carried out using divalent cations under elevated temperature in NEBNext First StrandSynthesis Reaction Buffer (5×). First strand cDNA was synthesized using random hexamer primer and M-MuLV Reverse Transcriptase (RNase H−). Second strand cDNA synthesis was subsequently performed using DNA Polymerase I and RNase H. Remaining overhangs were converted into blunt ends via exonuclease/polymerase activities. After adenylation of 3′ ends of DNA fragments, NEBNext Adaptor with hairpin loop structure were ligated to prepare for hybridization. In order to select cDNA fragments of preferentially 150-200 bp in length, the library fragments were purified with AMPure XP system (Beckman Coulter, Beverly, USA). Then 3 μl USER Enzyme (NEB, USA) was used with size-selected, adaptor-ligated cDNA at 37° C. for 15 min followed by 5 min at 95° C. before PCR. Then PCR was performed with Phusion High-Fidelity DNA polymerase, Universal PCR primers and Index (X) Primer. At last, PCR products were purified (AMPure XP system) and library quality was assessed on the Agilent Bioanalyzer 2100 system.

    [0110] RNA Sequencing Data Analysis

    [0111] Primary data analysis for quality control, mapping to reference genome and quantification was conducted by Novogene as outlined below.

    [0112] Quality control: Raw data (raw reads) of FASTQ format were firstly processed through in-house scripts. In this step, clean data (clean reads) were obtained by removing reads containing adapter and poly-N sequences and reads with low quality from raw data. At the same time, Q20, Q30 and GC content of the clean data were calculated. All the downstream analyses were based on the clean data with high quality.

    [0113] Mapping to reference genome: Reference genome and gene model annotation files were downloaded from genome website browser (NCBI/UCSC/Ensembl) directly. Paired-end clean reads were mapped to the reference genome using HISAT2 software. HISAT2 uses a large set of small GFM indexes that collectively cover the whole genome. These small indexes (called local indexes), combined with several alignment strategies, enable rapid and accurate alignment of sequencing reads.

    [0114] Quantification: HTSeq was used to count the read numbers mapped of each gene, including known and novel genes. And then RPKM of each gene was calculated based on the length of the gene and reads count mapped to this gene. RPKM, (Reads Per Kilobase of exon model per Million mapped reads), considers the effect of sequencing depth and gene length for the reads count at the same time and is currently the most commonly used method for estimating gene expression levels.

    [0115] Statistical analysis was done by the authors in Excel. The fold change was calculated by dividing the IL-10 stimulated expression levels by the unstimulated control within each donor. The average fold change was calculated for each stimulation across the three donors and the log.sub.2 of this average was then calculated. For calculation of significantly changed genes, the log.sub.2 of the fold change between IL-10 stimulated and unstimulated expression levels of each donor was calculated, separately and an unpaired, two tailed t test was used to generate the p value. The logo of this p value was then plotted against the previously calculated log.sub.2 average fold change. Genes which were significantly (p≤0.05) changed greater than 0.6 or less than −0.6 log.sub.2 fold change in the wild type IL-10 dimer (WTD) 50 nM condition were taken as a set list of genes against which all other IL-10 stimulations were compared. Upregulated genes were denoted as genes ≥0.6 log.sub.2 fold change and downregulated genes were denoted as genes ≤−0.6 log.sub.2 fold change. For comparison of WTD to other IL-10 variant stimulations the average log.sub.2 fold changes of the variant was divided by the average log.sub.2 fold change of WTD. Genes with an RPKM of less than 1 in two or more donors were excluded from analysis so as to remove genes with abundance near detection limit.

    [0116] Functional annotation of genes (KEGG pathways, GO terms) was done using DAVID Bioinformatics Resource functional annotation tool (Huang da et al., 2009a, b). Clustered heatmap was generated using R Studio Pheatmap package.

    [0117] Live-Cell Dual Colour Single Molecule Imaging Studies

    [0118] Receptor homo- and heterodimerization was quantified by two-colour single-molecule co-tracking as described previously (Moraga et al., 2015c, Wilmes et al., 2015, Wlmes et al., 2020). Receptor dimerization experiments were performed in HeLa cells transiently expressing IL-10Rα and IL-10Rβ with N-terminally fused variants of monomeric ECFP and EGFP, respectively. Cell surface Labelling was achieved using anti-GFP nanobodies Minimizer (MI) and Enhancer (EN), respectively, site-specifically conjugated with photostable fluorophores via an engineered cysteine residue. For quantification of receptor heterodimerization, IL-10Rα and IL-10Rβ were labelled with MI.sup.Rho11 (ATTO Rho11, ATTO-TEC GmbH) and EN.sup.AT643 (ATTO 643, ATTO-TEC GmbH), respectively. For quantification of homodimerization, either IL-10Rα was labelled with MI.sup.Rho11 and MI.sup.AT643, or IL-10Rβ was labelled with EN.sup.Rho11 and EN.sup.AT643. Over-expression of the corresponding other receptor subunit was ensured by labelling with EN.sup.AT488 or MI.sup.AT488 (ATTO 488, ATTO-TEC GmbH), respectively. Time-lapse dual-color imaging of individual IL-10Rα and IL-10Rβ in the plasma membrane was carried out by total internal reflection fluorescence microscopy with excitation at 561 nm and 640 nm and detection with a single EMCCD camera (Andor iXon Ultra 897, Andor) using an image splitter (QuadView QV2, Photometrics). Molecules were localized using the multiple-target tracing (MTT) algorithm (Serge et al., 2008). Receptor dimers were identified as molecules that co-localized within a distance threshold of 150 nm for at least 10 consecutive frames as described in detail previously (Moraga et al., 2015c, Wilmes et al., 2015, Wilmes et al., 2020).

    [0119] Results:

    [0120] Engineering IL-10 Variants with Enhanced Affinity Towards IL-10Rβ

    [0121] IL-10 engages its tetrameric receptor complex in a two-step binding process. In a first step one molecule of IL-10 binds two copies of IL-10Rα with high affinity and in a second step, two copies of IL-10Rβ are recruited to the tetrameric IL-10/IL-10Rα complex to initiate signalling (FIG. 1A, top panel). A striking feature of IL-10 is its very poor binding affinity for IL-10Rβ (˜mM range), which we hypothesised acts as a rate-limiting step in IL-10's biological activities. Thus, we asked whether an IL-10Rβ affinity-enhanced IL-10 variant would overcome this in vivo rate-limiting-step by inducing robust responses at a wide range of ligand concentrations. To address this question, we have used yeast surface display to increase the binding affinity of IL-10 for IL-10Rβ and study the signalling and activity profiles induced by these new affinity-enhanced IL-10 variants. A caveat to engineering IL-10 is its dimeric nature, which makes the correct display of this cytokine on the yeast surface challenging. We have used the monomeric IL-10 variant previously described by the Walter group (Josephson et al., 2000) as an engineering scaffold to overcome this limitation. The monomeric IL-10 was generated by the Walter group by extending the connecting linker between helices D and E in IL-10 by 6 peptides, consequently allowing helices E and F to fold into its own hydrophobic core to form an IL-10 monomer (FIG. 1B and FIG. 8). Monomeric IL-10 recruits one molecule each of IL-10Rα and IL-10Rβ to form an active signalling trimeric complex (FIG. 1A, bottom panel). Although monomeric IL-10 can trigger IL-10-mediated responses, it does so with a significantly lower potency than its dimeric counterpart (Josephson et al., 2000, Logsdon et al., 2002).

    [0122] First, we transfected yeast with the monomeric IL-10 construct to test whether binding to IL-10Rα and IL-10Rβ receptor subunits was preserved in the context of the yeast surface. We used biotinylated IL-10Rα and IL-10Rβ receptors in combination with Alexa-647 fluorescently labelled streptavidin to measure receptor binding by flow cytometry (FIG. 1C). As shown in FIG. 1D monomeric IL-10 retained binding to IL-10Rα confirming that it was correctly displayed on the surface of the yeast. We could not detect binding of monomeric IL-10 to IL-10Rβ in the presence or absence of IL-10Rα confirming its weak binding to this receptor subunit (FIG. 1D). Without a crystal structure of IL-10 bound to IL-10Rβ to guide us in the design of a site-directed mutant library, we undertook an unbiased error-prone approach to generate IL-10 mutants with enhanced affinity for IL-10Rβ. The monomeric IL-10 variant was subject to error-prone PCR and the amplified PCR product was electroporated into the S. cerevisiae strain EBY100 following previously described protocols (Chao et al., 2006, Mendoza et al., 2017). Eight rounds of selection were performed where the concentration of IL-10Rβ was gradually decreased to isolate variants of IL-10 that bind IL-10Rβ with enhanced affinity (FIG. 1E). Initial rounds of selection were done with high concentrations of biotinylated IL-10Rβ in the presence of non-biotinylated IL-10Rα to stabilize the surface complex and recover low affinity binders. After round 6 the library was comprised of variants that could bind IL-10Rβ in the absence of IL-10Rα and by round 8 the library could bind concentrations of IL-10Rβ in the low nanomolar range (FIGS. 1E and 1F). At this point we picked individual yeast colonies and isolated several clones (A11, B11, R5A11) that bound IL-10Rβ with enhanced affinity when compared to IL-10 wild-type (FIGS. 1F and 1G). When the mutations found in these variants were placed in the context of the IL-10 structure, importantly they localized in a region along helices A and D previously predicted to bind IL-10Rβ (Mendoza et al., 2017) validating our selection process (FIGS. 1H and 1I).

    [0123] Biophysical Characterisation of Isolated IL-10 Variants

    [0124] Next we recombinantly expressed the isolated IL-10 variants and characterized their biophysical properties. Importantly, the IL-10 variants behave as monomers when run in a gel filtration column confirming their monomeric nature (FIGS. 8A and 8B). We carried out surface plasmon resonance (SPR) studies to validate the apparent binding affinities seen in the on-yeast binding titration experiments in FIG. 1G. Biotinylated IL-10Rβ was immobilised onto the chip surface and the IL-10 variants A11, B11 and R5A11 were flowed across (FIG. 9A). We could not detect binding of the wild type monomeric IL-10 (WTM) at the range of doses used in this study (micromolar range), confirming the low binding affinity exhibited by IL-10 wt for IL-10Rβ (FIGS. 9B, panel one and 9C). The affinity matured IL-10 variants were all capable of binding IL-10Rβ with K.sub.D values in the low micromolar range (FIGS. 9B and 9C) confirming their improved binding affinities.

    [0125] IL-10 displays cooperative binding kinetics whereby its affinity for IL-10Rβ is enhanced once pre-bound to IL-10Rα (Walter, 2014). Thus, we investigated whether our mutants preserved this property. For that, we performed new SPR measurements using the high affinity IL-10 variants pre-bound to soluble IL-10Rα (FIG. 9D). We could not detect significant binding of the WTM/IL-10Rα complex to IL-10Rβ, highlighting again its very poor binding affinity towards IL-10Rβ (FIGS. 9E, panel one and 9F). All IL-10 variants exhibited enhanced binding to IL-10Rβ when complexed to IL-10Rα (in the nM range), confirming their cooperative binding and suggesting that the canonical IL-10 receptor complex binding topology has not been perturbed by the mutations introduced in our new variants (FIGS. 9E and 9F). Our SPR data confirms the isolation of new IL-10 variants, which engage IL-10Rβ with 1000-fold better binding affinity than their wt counterpart.

    [0126] Enhanced IL-10Rβ Binding Affinity Improves Receptor Complex Assembly.

    [0127] Thus far we had carried out the biophysical characterisation of our high affinity IL-10 variants in the monomeric conformation of the cytokine as this was necessary for the protein engineering methodologies used. In order to recapitulate the native IL-10/IL-10 receptor complex stoichiometry we recombinantly expressed our high affinity IL-10 mutant, R5A11, in the dimeric form (R5A11D) in addition to the monomeric form (R5A11M) (FIGS. 8A and 8B). Comparisons between this and the wild type IL-10 dimer (WTD) and wild type IL-10 monomer (WTM) allowed us to examine the contributory effects of increased binding affinity as well as stoichiometry on IL-10's molecular and cellular activities.

    [0128] In order to test how increasing the binding affinity to IL-10Rβ altered the dynamics of receptor assembly at the plasma membrane of live cells, we probed diffusion and interaction of both receptor chains by dual colour total internal reflection fluorescence (TIRF) microscopy. To this end, we expressed in HeLa cells IL-10Rα and IL-10Rβ tagged with engineered variants of non-fluorescent (Y67F) mEGFP. The tags were designed to specifically recognise either one of two different anti-GFP nanobodies ((Kirchhofer et al., 2010) pdb: 3K1K and 3G9A). These nanobodies (NBs) were conjugated to photostable organic fluorophores RHO11 and Dy649 suitable for simultaneous dual-colour single molecule tracking of IL-10Rα.sup.DY649 and IL-10Rβ.sup.RHO11 on the surface of live cells as shown previously in other cytokine receptor systems (Martinez-Fabregas et al., 2019, Wilmes et al., 2020, Moraga et al., 2015a) (FIG. 2A and FIG. 10A).

    [0129] After cell surface labelling we found both receptor subunits freely diffusing in the plasma membrane. Receptors were considered as dimerized if two individual particles were persistently found in both spectral channels for ≥10 consecutive steps (˜320 ms) in a proximity of 100 nm. These co-localization/co-tracking thresholds allowed the elimination of density-dependent random encounter co-localizations. In the absence of IL-10, we did not observe heterodimerization of IL-10Rα and IL-10Rβ above background (FIGS. 2B and 2C). Stimulation with saturating concentrations of WTD substantially dimerized IL-10Rα and IL-10Rβ. Strikingly, R5A11D induced a significantly higher level of receptor complex assembly (FIG. 2C). This finding was also confirmed for the monomeric versions of both wild type and high affinity IL-10 variants although at lower levels than seen for the dimeric versions (FIG. 3D). Ligand stimulation led to a significant decrease of diffusion mobility, particularly for IL-10Rα, which is in line with previous reports (FIG. 10B). (Moraga et al., 2015c, Wilmes et al., 2015). We also probed homodimerization of IL-10Rα and IL-10Rβ. To this end, we stochastically labelled either of the receptor chains with both dyes (FIG. 10A), taking into account that only half of the dimers would be labelled with different dyes and thus would be picked up by co-tracking analysis. Stimulation with the dimeric IL-10 induced strong homodimerization of IL-10Rα with no difference between both cytokine variants, as the IL-10Rα binding interface was unaltered in R5A11 (FIG. 2C). Instead, homodimerization of IL-10Rβ was significantly increased for the engineered variant R5A11D. For the monomeric IL-10 variants, all homodimerization experiments failed to induce receptor homodimers, in agreement with the monomeric nature of the ligands (FIG. 2D) (Josephson et al., 2000). Taken together, increased receptor assembly was observed for R5A11 under all conditions in which the affinity-matured interface to IL-10Rβ was involved.

    [0130] IL-10 Variants Exhibit Enhanced Signalling Activities in Human Primary Monocytes

    [0131] IL-10 inhibits inflammatory processes by modulating the activities of different innate cells including monocytes. We next performed a battery of signalling and activity assays in human monocytes to investigate the anti-inflammatory potential of our engineered variants. Monocytes (CD14+ cells) were isolated from human buffy coats and rested for two days before stimulation with IL-10 wt and high affinity monomer and dimers (FIG. 3A). Levels of STAT1 and STAT3 phosphorylation upon ligand stimulation were measured by flow cytometry as these two transcription factors represent the major signalling pathway engaged by IL-10 (Wehinger et al., 1996, Finbloom and Winestock, 1995). At saturating concentrations R5A11D and WTD activated comparable STAT1 and STAT3 levels (FIG. 3B). However, R5A11D showed enhanced phosphorylation of both STAT3 and STAT1 at sub-saturating concentration, which translated into a decrease in EC.sub.50 values compared to WTD (FIGS. 3B and 3C). WTM showed a poor activation of STAT3 and STAT1 with amplitudes of activation less than fifty percentage of those elicited by the WTD (FIG. 3B). Interestingly, WTM triggered a biased signalling response. While WTD, R5A11D and R5A11M showed a 1:1 pSTAT1 to pSTAT3 ratio, WTM showed a clear bias towards pSTAT3 (FIG. 3D), agreeing with previous observations from our laboratory describing biased signalling by short-lived cytokine-receptor complexes (Martinez-Fabregas et al., 2019). R5A11M induced activation of both STAT3 and STAT1 to levels comparable to those induced by the dimeric cytokines at saturating doses, suggesting that the defective signalling elicited by WTM results from its weak receptor binding affinity (FIGS. 3B and 3C). Signalling kinetics studies showed that the signalling profiles obtained in our dose response studies were not confounded by differences in signalling kinetics elicited by the different IL-10 variants. The four IL-10 ligands triggered comparable signalling kinetics in human monocytes (FIG. 3E and FIG. 11), confirming that their different signalling profiles result from their different binding affinities to IL-10Rβ.

    [0132] IL-10 exerts its anti-inflammatory properties by inhibiting antigen presentation in innate cells such as monocytes and dendritic cells (Mittal and Roche, 2015). Thus, we next studied whether IL-10 binding affinity to IL-10Rβ influences its ability to decrease HLA-DR expression in human primary monocytes. WTD and R5A11D reduced the HLA-DR surface levels to similar extent (50%) at saturating doses, in agreement with their comparable signalling profiles (FIG. 3F). At sub-saturating doses however, R5A11D showed an advantage over WTD, inducing a stronger downregulation of HLA-DR expression (FIG. 3F). WTM induced a mild reduction of HLA-DR surface levels (20%) paralleling its poor signalling potency (FIG. 3F). Interestingly, R5A11M induced only a 30% reduction of the surface HLA-DR levels, despite activating STAT1/STAT3 to a very similar extent to the dimeric ligands (FIG. 3F), suggesting an additional mechanism by which IL-10 regulates H LA-DR expression. We next investigated how IL-10Rβ binding affinity correlates with IL-10's ability to inhibit pro-inflammatory cytokine production by monocytes. For this, we measured levels of IL-6 secreted by monocytes upon LPS stimulation in the presence of the indicated doses of WTD and R5A11D (FIG. 3G). At saturating concentrations WTD and R5A11D effectively inhibited IL-6 secretion to a similar extent (FIG. 3G). However, at sub-saturating doses R5A11D again showed a marked improvement over WTD (FIG. 3G). Together our data highlights that IL-10 variants exhibiting enhanced binding towards IL-10Rβ gain a functional advantage at sub-saturating doses, such as those found during therapeutic interventions.

    [0133] Increased Receptor Affinity Enhances Transcriptional Activity of IL-10 in Monocytes

    [0134] Our initial studies in monocytes were focused on two classical markers regulated by IL-10, i.e. HLA-DR levels and IL-6 expression. To gain a broader understanding of how our variants regulate human monocytes activities, we performed detailed transcriptional analysis of human monocytes stimulated with the different IL-10 ligands for 24 hrs. Monocytes were isolated and treated as in FIG. 4A. WTD treatment elicited a strong transcriptional regulation in human monocytes inducing the upregulation of 741 genes and downregulation of 1084 genes (FIGS. 4B and 4C). Highly upregulated and downregulated genes are shown in FIG. 5D. KEGG pathway analysis showed a large number of genes regulated by IL-10 treatment involved in metabolic pathways (FIG. 12A), a selection of which are shown in FIG. 12B. WTD treatment regulated expression of hexokinase-2 and hexokinase-3, key enzymes in glycolysis. Genes associated with acyl-CoA synthesis, ACSS2, ACSL4, ACSL1, were also significantly upregulated highlighting a potential regulation of lipid biosynthesis by IL-10 (FIG. 12B). In addition to metabolic-related genes, WTD treatment regulated expression of cytokines, chemokines and their receptors (FIG. 12B). For instance, cytokines receptors such as IL-12Rβ2, IL-21Rα and IL-4Rα were upregulated while cytokines such as IL-8, IL-18 and IL-24 were downregulated (FIG. 12B). Expression of CXCL1, CCL22, CCL24, CCL18, CXCL10 and CXCL11 chemokines was also modulated by IL-10 treatment contributing to an anti-inflammatory environment. We also observed the regulation of a miscellaneous collection of CD markers by WTD treatment, including CD93—a receptor critical for monocyte phagocytosis and CD44 and CD9—markers involved in cell surface adhesion (FIG. 12B); and an inhibition of type I IFN gene signature, in agreement with previous studies (Ito et al., 1999, Dallagi et al., 2015) (FIG. 12B). Overall, our transcriptional studies revealed a broad regulation of monocyte biology by IL-10, englobing the fine-tuning of their energy homeostasis, migration and trafficking. Remarkably, 90% of genes regulated by WTD at saturating doses were induced to the same extent when sub-saturating doses of WTD were used, highlighting the robustness of the IL-10 responses (FIG. 4E). However, interestingly of the 10% of genes differentially regulated by WTD at the two doses, 96% of those correspond to genes downregulated by IL-10 treatment and include critical pro-inflammatory chemokines and cytokines (FIGS. 4E and 4F). A list of differentially expressed genes is provided in FIG. 5G. Our data shows that low doses of IL-10 treatment specifically disrupt the ability of IL-10 to block expression of key cytokines and chemokines that critically contribute to enhance the inflammatory response.

    [0135] Next we studied how the engineered IL-10 variants regulated gene expression programs in monocytes. WTM induced a very poor transcriptional response, in line with its weak signal activation profile (FIG. 4H and FIG. 12C). Interestingly R5A11M triggered a more potent transcriptional response when compared to WTM but failed to reach the same potency induced by the dimeric ligands (FIG. 4H and FIG. 12C). A direct comparison between WTD and R5A11M showed that the latter monomeric ligand exhibited a diminished effect in 39% of genes regulated by IL-10 (FIG. 12D). This is in contrast to its ability to activate STAT1 and STAT3 to levels comparable to those induced by the dimeric ligands, suggesting that STAT activation does not directly correlate with transcriptional activity in the IL-10 system. In agreement with our signalling studies, R5A11D induced a more robust gene expression profile at sub-saturating doses when compared to WTD (FIG. 4H). R5A11D enhanced the expression of 18% of genes regulated by WTD at 0.1 nM, with only 6% of genes showing favourable activity by WTD over R5A11D (FIGS. 4H and 4I, FIG. 12E). FIG. 4J shows that of the top 10 IL-10 regulated genes, the majority of them displayed enhanced activity by R5A11D. This pattern holds true when genes are group by families, i.e. cytokines & chemokines, CD markers and MAPK signalling (FIG. 12C). Importantly, key pro-inflammatory cytokines, which were not regulated by WTD at low doses, are still regulated by R5A11D (FIG. 4K). Overall, our transcriptional data shows that IL-10 regulates monocyte biology at different levels and that R5A11D, by exhibiting enhanced affinity towards IL-10Rβ, elicits more robust responses at a broader range of ligand concentrations, holding the potential to rescue IL-10 based therapies targeting inflammatory disorders.

    [0136] IL-10 Variants Exhibit Enhanced Signalling Activities in Human Primary CD8 T Cells

    [0137] In addition to its potent anti-inflammatory effects IL-10 stimulates cytotoxic CD8 T cells under certain circumstances, enhancing production of effector molecules and increasing their cytotoxic activity (Oft, 2014). We next investigated whether the enhanced activities exhibited by our affinity-matured variants in monocytes would translate into CD8 T cells. Human primary CD8 T cells were grown and activated as shown in FIG. 5A and STAT1/STAT3 activation levels in response to the indicated concentrations of IL-10 variants were measured by flow cytometry (FIG. 5B). WTD and R5A11D induced very similar STAT phosphorylation levels at saturating doses, but R5A11D showed a decreased EC.sub.50 value and stronger signalling at sub-saturating doses (FIG. 5B-D), agreeing with our results in monocytes. Interestingly R5A11D showed a more potent activation of STAT1 over STAT3 which we did not observed in monocytes, suggesting that long-lived IL-10 receptor complexes gain an advantage activating STAT1 in CD8 T cells. WTM exhibited weak activation of STAT1 and STAT3, inducing less than 25% of the activation amplitudes elicited by the dimeric molecules and exhibited a biased STAT3 activation (FIG. 5B-D). In contrast to what we observed in monocytes, R5A11M also elicited a STAT3 biased response activating STAT3 to 80% of the levels induced by the dimeric molecules and STAT1 to 60% of the levels induced by the dimeric molecules (FIG. 5B-D), suggesting that fundamental differences between monocytes and CD8 T cells impact signalling downstream of the IL-10 receptor complex. As with monocytes, signalling kinetic studies revealed that the observed differences in signalling output by the different IL-10 ligands did not result from altered signalling activation kinetics (FIG. 5E).

    [0138] Granzyme B is a potent cytotoxic effector molecule which has been shown to be increased in CD8 T cells upon IL-10 stimulation (Naing et al., 2018). Next, we studied how granzyme B production by CD8 T cells was regulated by the different IL-10 ligands. For that, PBMCs or isolated CD8 T cells were activated following the workflow illustrated in FIG. 6A and granzyme B levels were measured by flow cytometry or qPCR. As previously reported IL-10 stimulation did not affect classical early and late activation markers, i.e. CD69 and CD71 respectively, nor induced a significantly higher upregulation of inhibitory receptors, i.e. LAG-3 and PD-1 or affect CD8 cell proliferation (FIGS. 13A and 13B). On the other hand, IL-10 stimulation led to a strong upregulation of granzyme B levels in monocytes both at the mRNA and protein levels, independently of whether CD8 T cells were activated in the context of a PBMC population or a purified CD8 T cell population (FIG. 13C). When we compared our IL-10 ligands, at saturating concentrations WTD and R5A11D upregulated granzyme B production to a similar extent, 2.5-fold higher than granzyme B levels induced by TCR stimulation alone (FIG. 5F). WTM showed very poor granzyme B production in agreement with its weak STAT activation. At a sub-saturation concentration, we again observed a stronger upregulation of granzyme B levels induced by R5A11D. Interestingly, R5A11M stimulation resulted in two major populations, with half of the donors upregulating granzyme B to levels similar to those induced by WTM and the other half upregulating granzyme B to levels comparable to those induced by the dimeric molecules. Overall, our results show that enhanced affinity for IL-10Rβ bestows IL-10 with robust activities over a wide range of ligand doses and immune cell subsets.

    [0139] Increased Receptor Affinity Enhances Transcriptional Activity of IL-10 in CD8 T Cells

    [0140] To obtain a more complete understanding of how IL-10 regulates CD8 T cells responses, we next performed transcriptional studies on CD8 T cell treated with the different IL-10 ligands. Human CD8 T cells were purified by positive selection and activated in the presence of IL-10 wt and variants over 6 days as shown in FIG. 6A. The transcriptional changes induced by WTD in CD8 T cells were less dramatic than those induced by this cytokine in monocytes. Only 1000 genes were significantly regulated, with 79% of those genes being down-regulated (FIGS. 6B and 6C). The more highly regulated genes are shown in FIG. 7D. KEGG pathway analysis showed that IL-10 regulated genes are involved in cytokine-cytokine receptor interaction (FIG. 14A). Strikingly, we noticed that IL-10 induced the downregulation of genes classically associated with CD8 T cell exhaustion (FIG. 6E). We compared IL-10-regulated genes to a previously published list of exhaustion-specific CD8 T cell genes (Bengsch et al., 2018). We could identify four clusters of exhaustion genes regulated by IL-10. Cluster 1 comprises genes upregulated in both exhausted T cells and in T cells treated with IL-10. Cluster 2, the largest cluster, shows genes which were upregulated in exhausted T cells but downregulated by IL-10 treatment. Cluster 3 represent genes downregulated in exhausted T cells but upregulated by IL-10 treatment and cluster 4 is comprised of genes downregulated in both exhausted T cells and IL-10 treated T cells. A representative sample of regulated genes in each cluster is shown in FIG. 6F. These results suggest that IL-10 may enhance CD8 T cell activities by preventing their exhaustion. Interestingly, we also observed a significant downregulation of IL-2Ra by IL-10 treatment, which was associated with a reduction on expression of classical IL-2 dependent genes, such as IL-13, LIF, SLC1A4, NFIL3, etc (FIGS. 6G and 6H) (Rollings et al., 2018). Our results suggest that IL-10 regulates CD8 cytotoxic activities by limiting their sensitivity to IL-2, which may delay their exhaustion. As with monocytes, sub-saturating doses of WTD differentially affected a subset of genes regulated by IL-10, with the majority of those genes being downregulated by IL-10 treatment (FIG. 6I). Interestingly, at sub-saturating doses WTD failed to regulate classical IL-2 dependent genes like IL-13 and LIF, suggesting that regulation of IL-2 activities by IL-10 requires high IL-10 doses (FIG. 6J).

    [0141] As seen for monocytes, WTM showed very poor induction of gene expression (FIG. 6K and FIG. 14B), in line with its sub optimal STAT activation. R5A11M again enhance the transcriptional response when compared to WTM but failed to reach expression levels induced by the dimeric ligands despite activating very similar signalling profiles (FIG. 6K and FIG. 14B). Indeed, when directly comparing expression levels induced by WTD and R5A11M, the high affinity monomer showed diminished activity of 56% of IL-10 regulated genes (FIG. 14C). Similar to the results obtained with monocytes, R5A11D at 0.1 nM clustered with WTD 50 nM, supporting its ability to act effectively at low concentrations (FIG. 6K). When the expression levels induced by WTD and R5A11D at the sub-saturation concentration were compared, we identified 38% of IL-10 regulated genes being enhanced by R5A11D, with only 7% showing favourable expression by WTD at low dose (FIG. 6L and FIG. 14D). This was clearly reflected when the expression of the top 10 up and downregulated genes by WTD and R5A11D at 0.1 nM was compared (FIG. 6M). Importantly, classical IL-2 dependent genes, which were not regulated by WTD at low doses, were still regulated by R5A11D (FIG. 6N). Together our data confirms that IL-10 variants which bind the beta receptor more strongly exhibit more robust activity at a wider range of ligand concentrations and open new avenues to boost IL-10 based anti-cancer immune-therapies.

    [0142] Differential Gene Expression Program Regulated by IL-10 in Monocytes and CD8 T Cells

    [0143] Our study provides a high detailed description of transcriptional changes induced by IL-10 in monocytes and CD8 T cells. Despite the obvious discrepancies in the manner that the two cell types were stimulated with IL-10, we decided to investigate similarities of the transcriptional program induced by IL-10 in the two cell subsets, as a proxy to understand STAT3 transcriptional activities. To minimize variability resulting from the different treatments, we focused on genes that were regulated by IL-10 treatment in both monocytes and CD8 T cells. Interestingly, 181 genes were regulated by IL-10 in monocytes and CD8 T cells (FIG. 7A). We could identify four gene clusters based on their regulation by IL-10 treatment (FIG. 7B). Cluster 1 comprises genes that were upregulated by IL-10 treatment in both monocytes and CD8 T cells (FIG. 7B). Cluster 2 correspond to genes that were downregulated by IL-10 in monocytes, but upregulated by IL-10 in CD8 T cells. Cluster 3 show genes that were upregulated by IL-10 treatment in monocytes and downregulated by IL-10 treatment in CD8 T cells. Cluster 4 comprise genes downregulated by IL-10 treatment in monocytes and CD8 T cells. A representative sample of regulated genes in each cluster is shown in FIG. 7C. Overall our comparative study highlights that although IL-10 induces a shared gene expression program between monocytes and CD8 T cells, whether those IL-10 regulated genes are induced or repressed by IL-10 treatment depend on the context where IL-10 stimulation takes place, providing an additional level of gene regulation by cytokines.

    [0144] Production of Pentameric IL-10 Mutein and IL-10 Mutein/IL-4 Fusions

    [0145] Our data have shown that a stabilization of the IL-10/receptor complex results in more potent immuno-modulatory activities by IL-10. Thus, we hypothesize that further stabilizing the IL-10/receptor complex by increasing the binding valency of IL-10 would result in a significant improvement on the activities induced by this ligand. For that, we took advantage of the pentameric BTB domain from KCTD protein to engineer a fusion protein comprised of the pentameric BTB domain and the monomeric R5A11 (Fig. X and Seq. ID. Y). We have recombinantly expressed high levels of this chimeric protein proving the feasibility of the approach (Figure X).

    [0146] There are very few anti-inflammatory ligands described in the literature. One of them is IL-10, which we have engineered in this invention. An additional anti-inflammatory cytokine is IL-4. Here we have hypothesized that a synthetic cytokines comprising these two molecules would have exceptional anti-inflammatory properties. For that we have used our monomeric high affinity IL-10 variant as a scaffold and fuse it to three different IL-4 variants. IL-4 variant 1 correspond to the wild type molecule. IL-4 variant 2 correspond to an IL_4 variant that does not bind Gc or IL-13Ra1 and act as an antagonist. Variant 3 correspond to an IL-4 variant that exhibits reduced affinity for IL-4Ra. We expect that these mutations will affect the biodistribution of the synthetic molecules and target them to interesting immune cell subsets.

    [0147] IL-10 in CART Cancer Therapy

    [0148] Our data support a positive role of IL-10 in boosting CD8 T cell cytotoxic activities. IL-10 treatment induced the upregulation of Granzyme B by CD8 T cells and reduced their exhaustion gene signature, overall increasing the fitness. Based on this findings we next decided to explore the potential use of IL-10 to enhance CAR T cell therapies. CAR T cells are T cells that have been engineered to express an artificial receptor that allow them to specifically target tumor cells of interest. In recent years this therapy have shown a lot of potential and have revolutionized cancer immuno-therapy. However, CAR T cells still suffer from some drawbacks that reduce their efficacy, including the exhaustion of engineered CAR T cells due to over activation. Incubating CAR T cells with IL-10 before the administration to the patient could improve their fitness and therefore enhance their tumor killing potential. Here we provide some preliminary results that support this hypothesis. CAR T cells treated with either IL-10 wt or our engineered IL-10 variant (R5A11) show stronger killing activity in vitro (FIG. 16A) and higher induction of IFNgamma, a classical cytotoxic cytokine (FIG. 16B). Moreover our high affinity variant showed a stronger effect than IL-10 wt, highlighting again that enhance affinity for IL-10Rb boost IL-10 immuno-activities potency.

    [0149] Discussion:

    [0150] IL-10 is an important immuno-modulatory cytokine that regulates inflammatory responses and enhances CD8 T cells cytotoxic activities (Moore et al., 2001; Oft, 2014; Walter, 2014). Despite its central role preserving immune homeostasis, there is still a dearth of knowledge of the exact molecular mechanisms through which IL-10 carries out its functions. We postulate that the weak binding affinity that IL-10 exhibits for IL-10Rβ critically contributes to its functional fitness, by limiting the range of concentrations at which IL-10 elicits its full immuno-modulatory potential. Here we have engineered IL-10 to enhance its affinity for IL-10Rβ to investigate whether the stability of the IL-10 receptor complex determines IL-10 bioactivity potencies. Two main findings arise from our study: (1) Affinity-enhanced IL-10 variants trigger more robust responses at a wide range of ligand concentrations and in different immune cell subsets than wildtype IL-10, and (2) the stoichiometry of the IL-10-receptor complex contributes to IL-10 bioactivity potencies beyond regulation of STAT activation levels. More generally, this work outlines a strategy to improve the potency of low receptor binding affinity cytokines and presents new molecular and cellular data with the potential to revitalise failed IL-10 therapies.

    [0151] IL-10 exerted a profound regulation of the monocytic transcriptional program in our studies, agreeing with previous observations (Moore et al., 2001). IL-10 treatment inhibited antigen presentation by monocytes, limited their ability to recruit inflammatory immune cell subsets through regulation of chemokines and chemokine receptor expression, and boosted their phagocytic activity through the upregulation of scavenger receptors such as CD93, CD47, CD163 and cytokine receptors such as IL-21Ra. In addition, IL-10 treatment modulated the metabolic activity of monocytes by altering their glycolytic and lipid biosynthesis potential, in line with recent studies (Ip et al., 2017). Interestingly, IL-10 effects were slightly biased towards gene repression, with 59% of genes regulated by IL-10 being downregulated. Indeed, several studies have reported the ability of STAT3 to inhibit transcription induced by other STATs (Costa-Pereira et al., 2002; Ray et al., 2014; Yang et al., 2011), suggesting that STAT3 activating cytokines may elicit their functions by disrupting transcriptional programs induced by other cytokines. In agreement with this model, we recently reported that IL-6, another STAT3 activating cytokine, promoted strong STAT3 binding to chromatin, but poor gene expression (Martinez-Fabregas et al., 2019).

    [0152] The vast majority of reports in the literature describing IL-10 activities have focused on myeloid cells and use a single dose of IL-10, often at saturation (de Waal Malefyt et al., 1991a; Ding et al., 1993; Fiorentino et al., 1991a). However, we have a poor understanding regarding the range of IL-10 doses at which this cytokine elicits a full response in myeloid cells, a critical aspect when considering translation of this cytokine to the clinic. Here we provide transcriptional data from monocytes stimulated with two different doses of IL-10, one saturating and the second sub-saturating, with the latter more closely resembling the doses achieved during IL-10 therapies (Naing et al., 2018). Interestingly, 27% of genes regulated by IL-10 were affected when sub-saturating doses of IL-10 were used. The vast majority of affected genes (95%) were genes downregulated by IL-10 and encoded proteins critically contributing to establish an inflammatory environment i.e. key chemokines and cytokines such as IL-24, CXCL10, CXCL11, CCL22. This data suggests that IL-10 anti-inflammatory activities specifically require high and sustained doses to reach their full effect, explaining in part the failing of IL-10 therapies. Our engineered IL-10 variant exhibited a more robust activity at sub-saturating doses and induced potent inhibition of pro-inflammatory chemokines and cytokines, i.e. IL-24, CXCL10, CXCL11, CCL22. It is thus tempting to speculate that our engineered variant could rescue failed IL-10 therapies by promoting anti-inflammatory activities at low ligand doses.

    [0153] The anti-inflammatory activities elicited by IL-10 and its effects on monocytes and macrophages are very well documented. How IL-10 regulates the activity of CD8 T cells on the other hand is less clear and more controversial (Oft, 2014). While some studies have reported that IL-10 enhances the function of CD8 T cells and their ability to kill tumour cells (Emmerich et al., 2012), others report that the presence of IL-10 in the tumour microenvironment predicts poor responses by inhibiting T cell activation (Zhao et al., 2015). Our results agree with a positive effect of IL-10 treatment in CD8 T cells cytotoxic activities. CD8 T cells stimulated in the presence of IL-10 exhibited enhanced levels of effector molecules such as granzyme B, agreeing with recent clinical trials that show an improvement in the tumour response of patients treated with Pegylated-IL-10 (Naing et al., 2019). However, the molecular bases by which IL-10 boosts the anti-tumour CD8 T cell response remains poorly defined. Our transcriptional studies highlighted that CD8 T cells stimulated with IL-10 exhibited a reduced exhaustion gene signature and were more functionally fit. IL-10 treated CD8 T cells also expressed lower levels of IL-2Ra, which correlated with a reduced IL-2 gene signature in these cells. Altogether, our data agree with a model where IL-10, by reducing the sensitivity of CD8 T cells to IL-2, may prevent their over-activation and decrease their transition towards an exhausted phenotype. Remarkably, IL-10 preferentially repressed gene expression in CD8 T cells, with 79% of the genes controlled by IL-10 being downregulated, suggesting that STAT3 activation by IL-10 may compete with other STATs for binding to relevant gene promoters, fine-tuning CD8 T cell responses. Indeed, previous studies have reported a competition between STAT3 and STAT5 proteins for binding to gene promoters that influence cell sensitivity to IL-2 and inflammation (Yang et al., 2011). Our engineered IL-10 variant outperformed IL-10 wildtype in every read out tested when sub-saturating doses were used, reproducing our observations in monocytes and highlighting its potential to boost anti-tumour responses at therapeutical doses.

    [0154] The importance of the dimeric IL-10 architecture for generating its biological responses is not yet well understood. WTD binds IL-10Rα 60-fold more avidly than WTM, which contributes to its more efficient recruitment of IL-10Rβ to the signaling complex and its more potent activities (ref). Paradoxically, R5A11M, which binds IL-10Rβ with higher affinity and elicits more efficient receptor assembly than WTD, triggers weaker transcriptional responses, despite activating STATs to a very similar extent than WTD. In addition, viral IL-10 (also a dimeric ligand) induces the same specific activity than WTD even though binds IL-10Rα with lower affinity than WTM (Tan et al., 1993). Overall these observations suggest that in addition to receptor binding affinity, the stoichiometry of the IL-10-receptor complex contributes to fine-tune IL-10 bioactivity potencies. We recently showed that the number of phospho-tyrosines available in cytokine receptor intracellular domains critically contribute to defining signalling identity by cytokines (Martinez-Fabregas et al., 2019). IL-6 variants that triggered partial phosphorylation of Tyr available in the gp130 intracellular domain exhibited a biased STAT3 versus STAT1 activation (Martinez-Fabregas et al., 2019). A similar model could be invoked to explain functional differences between monomeric and dimeric IL-10 ligands. The dimeric IL-10 variants engage two molecules of IL-10Rα and IL-10Rβ, providing twice as many Tyr available for phosphorylation than the monomeric ligands. This in turn would result in an increase local concentration of phosphorylated Tyr that potentially could engaged additional signaling molecules not recruited by the monomeric ligands, and provide functional specificity. In agreement with this model, WTM and R5A11M elicited biased STAT3 activation in CD8 T cells. Future studies will need to address whether the higher number of Tyr available in the hexameric complex engaged by WTD contribute to define its signaling signature and biological identity.

    [0155] Our study provides a detailed description of how sub-optimal concentrations of IL-10, such as the one achieved during therapeutic interventions, differentially affects IL-10 immuno-modulatory properties. As concentrations of IL-10 decrease critical anti-inflammatory activities induced by this cytokine are lost. IL-10 therapies have been administrated to patients with a wide range of inflammatory disorders, but for the most part only produced disappointing results (Buruiana et al., 2010; Colombel et al., 2001). It is believed that local concentrations of IL-10 reached in the affected tissues during therapies are too low to trigger adequate anti-inflammatory responses (Buruiana et al., 2010; Colombel et al., 2001). In addition, the levels of IL-10 receptor significantly change across different myeloid cell populations, altering their sensitivity to IL-10 and possibly contributing to the poor responses observed in IL-10 therapies (Ding et al., 2001). Importantly, administration of IL-10 is well tolerated by patients, with only some mild side effects when high doses of IL-10 are used (Buruiana et al., 2010; Colombel et al., 2001). Our high affinity IL-10 variant has the potential to overcome these limitations and reinvigorate IL-10 therapies by eliciting strong anti-inflammatory and anti-cancer responses at therapeutically relevant doses, for example 100 μM-10 nM.

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