T Cells

20250270506 · 2025-08-28

Assignee

Inventors

Cpc classification

International classification

Abstract

The invention relates to T cells, and to methods of producing tissue-resident memory T cells (T.sub.RM). The invention concerns tissue-resident memory T cells (T.sub.RM) per se which have been obtained from the methods of the invention, compositions comprising these T.sub.RM cells, and the use of these T.sub.RM cells and the compositions in therapy, such as in immuno-therapy for treating cancer.

Claims

1. A method for producing a tissue-resident memory T cell (T.sub.RM), the method comprising culturing a lymphocyte in the presence of transforming growth factor beta (TGF) and/or co-culturing the lymphocyte with a regulatory T cell.

2. The method according to claim 1, wherein the lymphocyte is cultured in the presence of TGF, preferably wherein the lymphocyte is not co-cultured with a regulatory T cell.

3. The method according to claim 1, wherein the lymphocyte is a nave, effector or memory CD8+ T lymphocyte.

4. The method according to claim 1, wherein the TGF .sub.is present at a concentration of between 0.01 ng/ml and 50 ng/ml.

5. The method according to claim 1, wherein the lymphocyte has been obtained from tissue of a human or non-human animal, optionally wherein the tissue may be selected from the group consisting of: blood, spleen, lymph node, lung, gastrointestinal tract, skin, prostate mammary gland tissue, liver, bone marrow and pancreas.

6. The method according to claim 1, wherein the T.sub.RM is characterised by expression of cluster of differentiation 8 (CD8), cluster of differentiation 69 (CD69), Hobit, aryl hydrocarbon receptor (AhR) and/or cluster of differentiation 103 (CD103).

7. The method according to claim 1, wherein the T.sub.RM is characterised by the absence of expression of killer cell lectin-like receptor subfamily G member (KLRG1) and/or Eomesodermin (Eomes).

8. The method according to claim 1, wherein the method comprises culturing the lymphocyte in the presence of IL-2, IL-4, IL-7, IL-12, IL-15 and/or IL-21, optionally, wherein the method further comprises comprising culturing the lymphocyte in the presence of interleukin 33 (IL-33) and/or at least one interleukin 1 family member, optionally wherein the at least one interleukin 1 family member is IL-1a, IL-1b and/or IL-18.

9-14. (canceled)

15. The method according to claim 1, wherein the lymphocyte is cultured in a culture media comprising at least one aryl hydrocarbon receptor (AhR) ligand.

16. The method according to claim 9, wherein the AhR ligand is selected from a halogenated aromatic hydrocarbon, a polycyclic aromatic hydrocarbon, a dietary derived aryl hydrocarbon, a heme metabolite, an indigoid, StemRegenin 1 and a tryptophan metabolite.

17. The method according to claim 1, wherein the lymphocyte is cultured in a culture media comprising at least one lipid.

18. The method according to claim 1, wherein the lymphocyte is cultured in a culture media comprising an antigen, optionally wherein the antigen is a tumour antigen.

19. The method according to claim 1, wherein the regulatory T cell is characterised by expression of Foxp3, or is absent.

20. The method according to claim 1, wherein the method further comprises culturing the lymphocyte with a dendritic cell.

21. The method according to claim 1, wherein the method further comprises expanding a population of tissue-resident memory T cells (T.sub.RM).

22. The method according to claim 15, wherein the method further comprises culturing the T.sub.RM cells in the presence of IL-2, IL-4, IL-7, IL-12, IL-15 and/or IL-21.

23. A tissue-resident memory T cell (T.sub.RM) derived from a lymphocyte cultured in the presence of transforming growth factor beta (TGF) and/or co-cultured the with a regulatory T cell.

24-25. (canceled)

26. A method of preventing, treating or ameliorating of cancer or an infection in a subject in need thereof, the method comprising administering a tissue-resident memory T cell derived from a lymphocyte cultured in the presence of transforming growth factor beta (TGF) and/or co-cultured the with a regulatory T cell, to the subject.

27. The tissue-resident memory T cell (T.sub.RM) according to claim 23 or an expanded population thereof, wherein the tissue-resident memory T cell (T.sub.RM) or the expanded population thereof is comprised in a pharmaceutical composition, optionally wherein the pharmaceutical composition further comprises a pharmaceutically acceptable excipient.

28. (canceled)

Description

[0162] FIG. 1 shows Foxp3-dependent Tbx21 excision results in reduced number of type 1 Treg cells. (a) Percentage of intestinal T.sub.RM or spleen CD8+ T cells stained for T-bet by flow cytometry analysis (n=4-7). Ex vivo flow cytometry analysis of T cell populations in Foxp3WT and Foxp3Tbx21 mice in indicated organs. (b,f) Proportion of Treg cells (CD4+Foxp3+) in the spleen, mesenteric lymph nodes (mLN) or lamina propria (LPL) expressing either CXCR3, CCR6 or ST2 in (a) Foxp3WT or (f) Foxp3Tbx21 mice (n=4-12). (c,d) Percentage of CXCR3 expressed in CD4+, CD8+ and Treg cells in (c) spleen or (d) thymus (n=5). (e) Representative flow cytometry plot of CXCR3 expression in splenic CD4+ T cells. (g-j) Proportion of Treg cells expressing (g) CD44, (h) Helios, (i) Nrpl1 or (j) KLRG1 in Foxp3WT (open circles) and Foxp3Tbx21 mice (closed triangles) (n=4-9). Bars depict mean, error bars representSEM. For statistical analysis, Mann-Whitney U test, or multiple t test (g-j) was used. *P<0.05; **P<0.01; ***P<0.001; ****P<0.0001.

[0163] FIG. 2 shows Foxp3-dependent Tbx21 excision results in alterations in CD8 T cell 521 populations. (a, b) Flow cytometry analysis of CD8+ T cell populations in the spleen. (a) Percentage of naive (CD62LhiCD44lo), central memory (CD62LhiCD44hi) and effector memory (CD62L-CD44hi) CD8+ T cells in the spleen of Foxp3WT (open bars) n=8, Foxp3Tbx21 (closed bars) n=4, Foxp3Eomes mice (grey bars) (n=4). (b) Representative flow cytometry plot of CD62L and CD44 expression in spleen CD8+ T cells of indicated mouse lines. (c-e) Flow cytometry analysis of T cell populations, CD4+, Foxp3+ and CD8+ T cells in intestinal compartments; (c) intraepithelial lymphocytes (IEL) in Foxp3WT (open symbols) or Foxp3Tbx21 (filled symbols) mice, (d) Numbers of indicated subpopulations of IEL of the same mice described under (c), and (e) the lamina propria (LPL) (n=8-9). (f, g) Ratios of CD4+Foxp3 and CD8+ T cells in indicated organs in Foxp3WT and (f) Foxp3Tbx21 or (g) Foxp3Eomes (n=4-12). (h) Representative dot plots showing CD103 and CD69 expression of IEL (top panels) or LPL (lower panels) CD8+ T cells of indicated mouse lines. (i) Cell numbers of total CD8+ and CD8+CD103+ T cells in the jejunum LPLs of Foxp3WT (open bars), Foxp3Tbx21 (closed bars) and Foxp3Eomes (grey bars) mouse lines (n=5-11). (j) Ratio of total CD8+ T cells over CD8+CD103+ T cells found in the LPL of indicated mouse lines. (n=6-13). Bars depict mean, error bars representSEM. For statistical analysis, multiple t test was used. *P<0.05; **P<0.01; ***P<0.001; ****P<0.0001.

[0164] FIG. 3 shows reduced development of T.sub.RM cells in absence of type 1 Treg cells. (a-d) Lamina propria lymphocytes were isolated from indicated small intestine sections of Foxp3WT (open bars), Foxp3Tbx21 (closed bars) and Foxp3Eomes (grey bars) mice and analysed by flow cytometry. (a,b) Cells were gated on TCR+CD8+ and analysed for KLRG1 expression (n=4-8). (c,d) Representative flow cytometry plots showing (c) CD103 and KLRG1 expression or (d) Eomes and KLRG1 expression in TCR+CD4-CD8+ LPLs of indicated mouse lines. (e-h) Representative plots (e) and cumulative data (f-h) showing proportion of TCR+CD4-CD8+ cells which express KLRG1 in the liver and lungs of indicated mouse lines (f), proportion of T.sub.RM cells in the (g) liver (CD69+Eomes-KLRG1) and (h) lung (CD69+CD103+KLRG1) (n=7-11). Bars depict mean, error bars representSEM. For statistical analysis, Mann-Whitney U test or multiple t test (f-h) was used. *P<0.05; **P<0.01; ***P<0.001; ****P<0.0001.

[0165] FIG. 4 shows reduced T.sub.RM cell development results in increased susceptibility to infection. (a-b) TCR+CD8+ lamina propria lymphocytes, Eomeshi or Eomeslo, from Foxp3Tbx21 mice were analysed by flow cytometry, 48 hrs after stimulation with 25 g of anti-CD3 i.p., for (a) PD-1 and (b) GrzmB expression (n=8-9). (c-h) Foxp3WT (open symbols), (c,e,g) Foxp3Tbx21 (closed symbols) or (d,f,h) Foxp3Eomes (grey symbols) mice were orally infected with 1000 E. vermiformis oocysts. (c,d) Cumulative number of oocysts collected from individual mouse faeces from day 5-18. (e,f) Number of oocysts shed per day per individual mouse. (g,h) Body weight change during the course of E. vermiformis infection (n=3-4 per experiment, 2 biological repeats). Bars depict mean, error bars representSEM. For statistical analysis, multiple t test or Wilcoxon test (a,b) was used. *P<0.05; **P<0.01; ***P<0.001.

[0166] FIG. 5 shows recruitment of type 1 Treg cells determines T.sub.RM cell differentiation. (a-b) Rag2-deficient mice were reconstituted with bone marrow from Ctrl (CD45.1) or Foxp3Tbx21 (CD45.2) mice. Contribution of each donor was assessed for total CD8 T cells in the spleen and the T.sub.RM (CD8+CD103+KLRG1) LPL population; (a) representative dot plots, (b) overview of individual mice assessed (n=8). (c) Description of adoptive transfer model; Foxp3WT or Foxp3Tbx21 mice received C57Bl/6 CD45.1+CD8+ T cells intravenously, one day prior to oral infection with E.vermiformis. After infection resolution and on week 3-4 post-inoculation, lamina propria lymphocytes (LPL) were isolated from the small intestine and analysed by flow cytometry. (d) T.sub.RM cell development as proportion of total CD8 T cell in the LPL of CD45.1 host mice transfer with splenic Foxp3Tbx21-derived CD8 T cells and subsequent E. vermiformis challenge as described under (c) (n=6). (e) Representative dot plot of lymphocytes pre-gated on CD45.1, followed by gating on TCR and CD8 and analysed for expression of CD103 and Eomes in indicated mouse lines. (f-g) Cell numbers of total CD8+ LPLs and CD103+Eomes-CD8+ LPLs obtained from small intestine on week (b) 3 or (c) 9 post infection. Gating performed as described in (a) (n=5-7). (h) Proportion of CD8+CD45.1+ T cells recovered expressing CD103, after transfer of wild type CD45.1+CD8+ T cells with or without wild type Treg cells into Foxp3Tbx21 mice and E. vermiformis challenge. (i) Single-cell RNA-sequencing analysis of Treg cell subtypes, organised by type 1 (85 cells), 2 (35 cells), 3 (28 cells) or other undefined Treg cells. Bars depict mean, error bars representSEM. For statistical analysis, Mann-Whitney U test was used. **P<0.01; ****P<0.0001, n.s.=none significant.

[0167] FIG. 6 shows type 1 Treg cells promote T.sub.RM cell development via TGF availability. (a,b) Foxp3WT or Foxp3Tbx21 mice received C57Bl/6 CD45.1+CD8+ T cells intravenously, one day prior to oral infection with Yersinia pseudotuberculosis. 2-3 weeks later lamina propria lymphocytes (LPL) were isolated from the small intestine and analysed by flow cytometry. (a) Proportion of CD8+CD45.1+ T cells recovered expressing CD103 (n=7-9). (b) Representative dot plot of lymphocytes pre-gated on CD45.1, followed by gating on TCR and CD8 and analysed for expression of CD103 and Eomes in indicated mouse lines. (c-d) Ileum LPL Foxp3WT (open symbols) or Foxp3Tbx21 (closed symbols) mice were analysed at steady state (circle) or 10 days after E. vermiformis (Ev) (squares) infection, for (591 c) numbers of Treg, (d) number of Treg expressing CXCR3 (n=4-9). (e) C57BL/6 mice were infected or not with E.3 vermiformis and at day 10 Cxcl10 mRNA levels over Hprt were assessed in the ileum (2 594 biological repeats n=5-8). (f-k) Foxp3Tbx21 mice received C57Bl/6 CD45.1+CD8+ T cells intravenously, one day prior to oral infection with E. vermiformis. On week 3 post-infection, LPL were isolated from the small intestine and analysed by flow cytometry for the expression of CD103. In addition to CD8CD45.1 cells, wild type Treg cells or Treg cells deficient in (f) CXCR3, (h) IL-10, (i) IL-35, (j) Integrin8 or (k) TGF1 were co-transferred. Mice receiving wild type T.sub.REG cells were cumulated and used in panels (f, h-k). (g) Indicated mouse lines received CD45.1+CD8+ T cells intravenously, one day prior to oral infection with E.vermiformis. On day 10 post-infection, small intestine were stained for CD45.1 (green), Dapi (blue) and Foxp3 (red). Representative immune histochemistry pictures (objective 40, zoom 1.5) shown from areas with oocysts (n=4). White arrows indicate close proximity of CD8 T cell and TREG. Bars depict mean, error bars representSEM. For statistical analysis, Mann-Whitney U test was used . . . *P<0.05; **P<0.01; ***P<0.001; ****P<0.0001.

[0168] FIG. 7 shows Foxp 3 dependent Tbx21 conditional deletion results in reduced number of type 1 Treg cells Ex vivo flow cytometrically analysed cells showing a) Representative plots showing Tbet and Eomes expression by intracellular staining of CD8 cells in C57BL/6 spleen or intestinal T.sub.RM population, b) representative plots of CD4 T cells stained for Foxp3 and Tbet. c-e) Number of Treg, CD4 and CD8 T cells in the thymus and spleen of Foxp 3 WT (open bars) and Foxp3Tbx 21 (closed bars) mice n=9. f-h) Number of Treg, CD4 T cells and CD8 T cells in Foxp3WT (open bars) and Foxp3Eomes (grey bars) mice i-j) Percentage of CXCR3 expression in CD 4 CD 8 and Treg cells in i) spleen or j) thymus. Representative flow cytometry plot of CXCR3 expression in splenic CD4 T cells in Flow cytometric analysis of proportion of Treg cells in spleen, mesenteric lymph nodes mLN and lamina propria expressing CXCR3, CCR6 or ST2 (n4 open symbols Foxp3WT closed Foxp3Tbx21 Error bars representSEM For statistical analysis, Mann Whitney U test or multiple t test h-m) was used P<0 05 P<0 01 P<0 001 P<0 0001.

[0169] FIG. 8 shows Tbet or Eomes deficiency in Tregs is associated with alterations in T cell phenotype in the small intestine. Lamina propria lymphocytes (LPL) were isolated from Foxp3 WT, Foxp3Tbx21 and Foxp3Eomes mice and analysed by flow cytometry. a-d) Cell numbers in the LPL fraction of (a) duodenum (n=8-11), (b) jejunum (n=10-14), (c) ileum (n=9-13) and (d) colon (n=4-7) were determined by gating on TCR+ cells, followed by gating on CD4+CD8YFP(CD4+), CD4+CD8-YFP+ (Treg) and CD4-CD8+ T cells (CD8+). e-f) Ratio between CD4+Foxp3 T cells and CD4+YFP+ T cells in individual animals from Foxp3WT (open circles) and e) Foxp3Tbx21 (closed triangles) or (f) Foxp3Eomes (closed diamonds) (n=8). g) Representative flow cytometry dot plots showing CD103 and CD69 staining of CD4+YFP (top panels) or CD8+ (lower panels) LPL cells of indicated mouse lines. h) Number of total CD4+ T cells and CD103+CD4+ T cells in the lamina propria of Foxp3WT (open bars), Foxp3Tbx21 (closed bars) and Foxp3Eomes (grey bars) mouse lines (n=5-11). i) Ratio of Foxp3CD4+ T cells/CD8+CD103+ T cells found in the LPL of indicated mouse lines. (n=6-13). Error bars representSEM. For statistical analysis, Mann Whitney U test was used. *P<0.05; **P<0.01; ***P<0.001; *** P<0.0001.

[0170] FIG. 9 shows absence of type 1 Tregs results in reduced T.sub.RM cells Lamina propria lymphocytes were isolated from Foxp3WT, Foxp3Eomes and Foxp3Tbx 21 mice and examined by flow cytometry. a) Representative flow cytometry dot plots showing CD103 versus Eomes and KLRG1 versus CD69 in indicated mouse lines. b) Representative flow cytometry dot plots showing KLRG1 versus Bcl2 protein expression. c) Representative flow cytometry dot plots showing CD103 versus TL tetramer (CD 8 staining) (n=4). d) Representative flow cytometry dot plots showing in vivo staining of CD8 in blood and LPL compartment and e overview graph (n=5) * P<0.05, **P<0.01, ***P<0.001, ****P<0.0001.

[0171] FIG. 10 shows reduced T.sub.RM cell development increases infection susceptibility Lamina propria lymphocytes (LPL) or spleen CD8 T cells were isolated from Foxp3WT and Foxp3Tbx 21 mice 48 hrs after i.p. injection with anti CD38 antibodies and examined by flow cytometry. a-c) Representative flow cytometry dot plots showing (a) PD1 or (b) granzyme B versus Eomes protein expression in LPLs (n=4) b) As for a), but showing cumulative data for the spleen (n=6). d-i) C 57BL/6 (control) or (d-f) C57BL/6 Rag2.sup./ of (g-i) IL 15 R mice were orally infected with 1000 E vermiformis oocysts (g) Daily feacal oocyst counts per individual mouse for indicated days, e,h) accumulative oocyst counts (days 6-17 f,i) changes in body weight during E vermiformis infection (n=5-9, 2 biological repeats) Error bars representSEM For statistical analysis, Mann Whitney U test (e,h) multiple t test (d,f,g,f) or Wilcoxon (b) was used *P<0.05, **P<0.01, ***P<0.001, ****P<0.0001.

[0172] FIG. 11 shows Tbet expression and T.sub.RM cell development upon immune activation (a-d) Indicated T cells were assessed by intracellular flow cytometry staining under steady state or 24 hrs after in vivo anti-CD3 stimulation. a) Overview of Tbet expression in Foxp3WT (open symbols) and Foxp3Tbx21 (closed symbols) splenic CD4 and CD 8 T cells. b) Tbet expression analysis by intracellular staining for splenic CD 8 nave and memory T cells as well as LPL sourced T.sub.RM cells (n=11 12). Representative plot of splenic CD 8 T cells from Foxp3WT and Foxp 3Eomes mice stained for (c) Eomes or (d) Tbet 24 hrs after activation (n=3 5). e-h) Foxp3WT (open symbols) and Foxp3Tbx21 (closed symbols) mice were adoptively transferred with CD8 CD45.1 T cells, upon which mice were challenged with E vermiformis a day later At the peak of infection, day 10 LPLs were isolated and CD45.1 were analysed by flow cytometry for (e) proportion of T.sub.RM cells (CD8+CD103+Eomes) and (f) total CD8+CD45.1+ T cells (n=67). (g) As under e), using CD45.2+Foxp3Tbx21 mice as hosts with additional CD45.1+Wt Treg cells transferred, showing representative flow cytometry plots of CD4+ T cells in the LPL, endogenous (CD45.2+) and transferred (CD45.1+) CD4 and Treg cells expressing CXCR3. h) Overview of CXCR3 proportions of transferred Treg cells as under f-g). For statistical analysis, Mann Whitney U test was used.

[0173] FIG. 12 shows T.sub.RM cell development in selected mouse lines a,b) Lamina propria CD4 Foxp3 were isolated and enumerated of the ileum from Foxp3WT and Foxp3Tbx21 mice at steady state (circles) or 10 days after E vermiformis (squares) (n=5-8). c) Indicated mouse lines received CD45.1+CD8+ T cells intravenously, one day prior to oral infection with Ex On day 10 post infection, small intestine were stained for CD45.1 (green) Dapi (blue) and Foxp3 (red). Representative immune histochemistry pictures (objective 20 zoom 15, scale bar 50 m shown, with indicated area enlarged O ocysts are characteristic round unstained areas, such as part indicated with *. An area without oocysts for comparison shown (3rd panel) f) Relative expression levels of splenic CXCR3. or CXCR3+ Treg cells (n=4). LPL were isolated from d,e) C57BL6 (control) or IL 10 deficient mice, g, j) or bone marrow chimeric mice generated with C 57BL6 mice or g, h) IL-35 deficient mice, g,i) Foxp3Itg8 mice, g,j Foxp3tgf1 mice. Representative flow cytometry plots are shown (f) and cumulative proportion of CD103 expressing cells (h-j) (n=7-10). Bars represent mean. For statistical analysis, Mann Whitney test was used ***P<0.001, ****P<0.0001.

[0174] FIG. 13 shows flow cytometry analysis gating strategy. a) Representative flow cytometry plots from spleen of a C57BL/6 Foxp3Tbx21 mouse, showing lymphocyte gating, doublet exclusion and dead cell exclusion, followed by CD4 selection and Treg selection based on eYFP and tdRFP detection. b) Representative flow cytometry plots from LPL of a C57BL/6 Foxp3Tbx21 mouse, showing lymphocyte gating, doublet exclusion and dead cell exclusion, followed by inclusion of TCR+ CD69+ and CD8+. In LPL, T.sub.RM are defined as CD103+.

[0175] FIG. 14 shows RFP detection in Foxp3Tbx21 mice. a-c) Representative flow cytometry plots from spleen of a C57BL/6 Foxp3Tbx21 mouse, as in FIG. 13a, showing a) eYFP and tdRFP detection in the CD4 life gate, b) in the CD4 Foxp3 YFP population and c) the CD8 population Two representative plots are shown of 2 individual mice.

[0176] FIG. 15 shows the experimental layout detailing the production and testing of the T.sub.RM cells, from the initial cell extraction from a mouse to the sorting of the cell population through a FACS machine.

[0177] FIG. 16 shows that bone marrow derived dendritic cells (BMDC) maintain CD69 expression in CD8 T cells. When effector CD8 T cells are cultured with anti-CD3 in the presence of IL-15 and TGF alone (circles) or with BMDC (squares), the CD69 marker, critically expressed on T.sub.RM cells remains expressed in the presence of BMDC, but is lost in the absence of BMDC.

[0178] FIG. 17 shows that IL-7 induces CTLA-4 expression in T.sub.RM. Two independent duplicate experiments show the difference in CTLA-4 expression when effector CD8 T cells are cultured in the absence of IL-7 (black) and with the addition of IL-7 (grey).

[0179] FIG. 18 shows that IL-2 also induces CTLA-4 expression in T.sub.RM. The data show the expression of CTLA4 when effector CD8 T cells are cultured in the absence of IL-7 and IL-2 (black), with the addition of IL-7 (light grey), and with the addition of IL-2 (dark grey). Although a similar proportion of CD8 T cells expresses CTLA-4 if cultured with IL-7 or IL-2, the level of CTLA-4 expression is on average more robust for cultures containing IL-7 than for cultures containing IL-2.

[0180] FIG. 19 shows the experimental layout detailing the production and testing of the T.sub.RM cells, as well as the in vivo challenges and ex vivo analysis performed on the organs of the mice post-challenge. The inventor wanted to confirm whether the characteristics and phenotypes of the T.sub.RM cells produced in vitro correlate with their in vivo seeding into the organs.

[0181] FIG. 20 shows the expression profile of the markers CD69, CD103 and CTLA-4 for the different T cells cultures used in in vivo challenges. The T cells used for the challenges were cultured under the following conditions or groups: [0182] Group 1: CD8+BMDC+aCD3+ TGFb+IL-15=T.sub.RM; [0183] Group 2: CD8+BMDC+aCD3+ TGFb+IL-15+IL-7=T.sub.RM+IL-7; [0184] Group 3: CD8+BMDC+aCD3+IL-15=effector; and [0185] Group 4: CD8+BMDC+aCD3+ TGFb+IL-15+IL-2=T.sub.RM+IL-2.

[0186] FIG. 21 shows the number of CD8+ T cells derived from the spleen of challenged mice over the course of 40 days. Effector CD8 T cells were cultured under the conditions indicated in FIG. 20 and transferred into a full C57BL6/J host. At indicated times, the presence of transferred cells (CD45.1) was assessed in the spleen. Graphs show two experiments pooled. Experiment 1 (black symbols) did not include Group 4 and analysis was performed at time point 11-14 only. Experiment 2 (grey symbols) included Group 4 and analysis was performed at several time points and only shown are 2 out of 6 mice in which cells were recovered at the late time point. The data shows that IL-7 cultured T.sub.RM cells (group 2) were found in substantial numbers in comparison to T.sub.RM cells cultured without IL-7.

[0187] FIG. 22 shows the number of CD8+ T cells derived from the lamina propria of the intestine of challenged mice over the course of 40 days. Effector CD8 T cells were cultured under the conditions indicated in FIG. 20 and transferred into a full C57BL6/J host. At indicated times, the presence of transferred cells (CD45.1) was assessed in the lamina propria of the intestine. Graphs show two experiments pooled. Experiment 1 (black symbols) did not include Group 4 and analysis was performed at time point 11-14 only. Experiment 2 (grey symbols) included Group 4 and analysis was performed at several time points and only shown are 2 out of 6 mice in which cells were recovered at the late time point. The data shows that IL-7 cultured T.sub.RM cells (group 2) were found in substantial numbers in comparison to T.sub.RM cells cultured without IL-7.

[0188] FIG. 23 shows the number of CD8+ T cells derived from the lungs and IEL compartment of the intestine of challenged mice over the course of 32 days. Effector CD8 T cells were cultured under the conditions indicated in FIG. 20 and transferred into a full C57BL6/J host. At indicated times, the presence of transferred cells (CD45.1) was assessed in the lungs and IEL compartment of the intestine. Graphs show experiments (experiment 1-black symbols; experiment 2-grey symbols) in both organs showing the three groups and analysis was performed at several time points. The data shows that IL-7 cultured T.sub.RM cells (group 2) were found in substantial numbers in comparison to T.sub.RM cells cultured without IL-7.

[0189] FIG. 24 shows the comparative number of CD8+ T cells derived from the lamina propria of the intestine and the spleen of challenged mice over the course of 40 days. Effector CD8 T cells were cultured under the conditions indicated in FIG. 20 and transferred into a full C57BL6/J host. At indicated times, the presence of transferred cells (CD45.1) was assessed in the spleen and the lamina propria of the intestine. The data shows that IL-7 cultured T.sub.RM cells (group 2) were found in substantial numbers in comparison to T.sub.RM cells cultured without IL-7.

EXAMPLES

[0190] The inventors hypothesised that T.sub.REG cells are important in the generation of T cells, T.sub.RM cells, that are able to penetrate deeply into tissues and that are highly effective against solid tumours. The inventors aimed to determine the factors required to generate T.sub.RM cells to enable the generation of T.sub.RM cells in vitro with the ultimate aim to adapt current culture protocols to generate anti-tumour T cells to provide these with tissue penetrating properties to target both primary tumours and to provide critical organ-wide immunosurveillance directed against metastasis that have migrated to tissues away from the primary tumour. The inventors also aimed to assess whether the generation of T.sub.RM cells was possible in the absence of T.sub.REG cells in the medium as detailed in FIG. 15. Furthermore, the inventors assessed if the cells produced in vitro maintained their therapeutic properties, in particular, their ability to migrate and survive in vivo inside the tissues as detailed in FIG. 19.

Materials and Methods

Mice:

[0191] C57Bl/6J and C57Bl/6J CD45.1 mice were purchased from Charles River, France. Tbx21.sup.f/f (Tbx21.sup.tm2Srnr) and Eomes.sup.fl/fl (Eomes.sup.tmtSrnr) were kindly provided by Dr Reiner.sup.14, 82, Foxp3eYFP-Cre (Foxp3.sup.tm4(YFP/icre)Ayr) was kindly provided by Dr Rudensky.sup.83, Rosa26-tdRFP was kindly provided by Dr Fehling.sup.84, Rag2.sup./, IL15R.sup./ (Jackson labs). Mice were bred at the Instituto de Medicina Molecular, Lisbon, Portugal. Male and female mice, aged and sex matched, at 8-18 weeks of age were used. Animals were housed in IVC cages with temperature-controlled conditions under a 12-hours light/dark cycle with free access to drinking water and food. All mice were kept in specific-pathogen-free conditions. All mice in the Foxp3eYFP-Cre Rosa26-tdRFP lines were stringently genotyped by PCR and those in which a knock out allele was detected were discarded (20%), appropriate Tbx21 presence was confirmed by blood typing for CD4 T cells expressing CXCR3. In addition, mice were counter screened for inappropriate expression of RFP in relation of eYFP (10% discarded) (FIG. 13-14). Bone marrow chimeras were generated by sublethal irradiation (450 rads) of Rag2-deficient mice and subsequent i.v. injection of bone marrow cells obtained. CXCR3.sup./ (Cxcr3.sup.tm1Dgen).sup.85 were bred at the German Cancer Research Center (DKFZ), Heidelberg, Germany; IL-10.sup./86 were bred at Instituto Gulbenkian de Cincia, Lisbon, Ebi3.sup./ 87 were bred at the institute for Immunology, University Medical Center Mainz, Germany, Itgb8f/f 88 and Tgfbif/f 89, crossed to Foxp3yfp-Cre were bred at the Immunology Virology and Inflammation department, Cancer Research Center of Lyon, France. All animal experimentation complied with regulations of the Direo-Geral de Alimentao e Veterinria Portugal and local ethical review committee and guidelines.

[0192] Cell isolation: Intestinal cells were isolated as previously described 90. Intestine was flushed with PBS to remove contents and opened longitudinally. After cutting into 1 cm pieces, it was incubated in PBS containing 20 mM Hepes, 100 U/ml penicillin, 100 g/ml streptomycin, 1 mM Pyruvate, 10% FCS, 100 g/ml polymyxin B and 10 mM EDTA for 30 min at 37 C. while shaking to release IELs. IEL single-cell suspensions were further purified using 37.5% isotonic Percoll. To isolate LPLs, intestinal tissue was then digested in IMDM medium containing 0.5 mg/ml of Collagenase D (Roche) and 0.2 mg/ml of DNaseI (Roche) for 25 min at 37 C. while shaking. Liver lymphocytes were isolated by mashing the organ through a 70 m filter, followed by cell purification with 37.5% isotonic Percoll. Lungs were shredded in small pieces with scissors and digested in PBS containing 1 mg/ml Collagenase D, 37 C. during 30 minutes. The cell suspension containing the lymphocytes was obtained after passing through a 50 m cell strainer.

[0193] Adoptive cell transfers: CD8+ T cells and/or CD25+ cells (Treg) were purified from a single cell suspension of spleen and lymph nodes. Briefly, cells were labelled with anti-CD8-APC or anti-CD25-APC antibody and selected with anti-APC MACS microbeads, according to the manufacturer's instructions. After counting, purity was determined by flow cytometry and cell numbers adjusted. To ensure a wide TCR diversity in the population transferred a minimum of 210.sup.6 CD8 T cells were used. Some of the recipient mice received in addition 0.4-110.sup.6 Treg cells. Infection was performed one day after cell transfer (day 0).

[0194] Infection challenges: Animals were infected with Eimeria vermiformis (Ev) as previously described in detail.sup.91. Briefly, oocysts were washed 3 times with deionized water, floated in sodium hypochloride and counted using a Fuchs-Rosenthal chamber. Mice received 500 oocysts of E.vermiformis by oral gavage in 100 l of water and were analysed after the infection was cleared (from week 3 p.i). To determine burden of infection, animals were caged individually and faeces collected daily until oocysts were no longer detected. Animals were infected with Yersinia pseudotuberculosis (Yptb), kindly provided by Dr T. Bergsbaken, as previously described.sup.58. Animals were infected with 10.sup.6 Yptb by oral gavage in 100 l of water. Analysis of tissues was performed on days 15-19.

[0195] Flow cytometry: Single cell suspensions from spleen, lymph nodes, intestine, lung and liver were prepared and stained with antibodies (see list), according to the agreed standards.sup.92 and with indicated gating strategy (FIG. 13). In vivo staining were performed by i.v. injection of 3 g of CD8-APC antibody, whereupon mice were sacrificed 5 minutes later. TL-tetramer was kindly provided by NIH Tetramer Core Facility. Samples were run on a Fortessa X20 cytometer (BD Biosciences) and analysed with FlowJo software (TreeStar).

[0196] Quantitative RT-PCR: RNA was isolated using the Qiagen RNeasy Mini kit and cDNA generated using the High Capacity RNA-to-cDNA kit from Applied Biosystems. Amplification was performed using the SYBR Select Master Mix (Applied Biosystems) and the QuantiTect Primer Assays Mm_Cxcl10_1_SG, Mm_Tgfb1_1_SG, Mm_Itgb8_1_SG and Mm_Hprt_1_SG (Qiagen).

[0197] Immunohistochemistry and microscopy: Intestinal tissues were rolled into a Swiss roll, fixed in 10% formalin, rehydrated in 30% glucose and frozen in OCT media. Tissues were cut at 10 m and sections treated with 4% paraformaldehyde. Blocking was performed using 10% BSA and the following antibodies were used for detection: CD45.1 (A20, Biolegend) and FOXP3 (FJK-16s, eBioscience). Slides were mounted in Fluoromount (Invitrogen) and imaged using a Zeiss LSM 880 microscope. Analysis was performed using Fiji software.

[0198] scRNA-Seq analysis Original data was produced and analysed in55. From the initial data-set, T.sub.REG cells were selected based on Foxp3, excluding Tmems, stressed and low-quality cells. In order to analyse this subset, we followed a similar approach as.sup.55, using the R package Seurat.sup.93. Normalization of the data using the LogNormalize method and using a scale factor of 10.sup.5; and scale the data based on Negative Binomial Model and using UMI's. Subtypes of T.sub.REG were defined using the following criteria: Type 1 (Cells with raw counts assigned to the genes Tbx21, Stat1 and Cxcr3); Type 2 (Cells with raw counts assigned to the genes Gata3, Stat6 and Il.sup.1rl1); Type 3 (cells with raw counts assigned to the genes Rorc, Stat3 and Ccr6); other (Cells with no raw counts assigned to the genes Tbx21, Gata3 and Rorc).

In Vitro Cultures:

[0199] Effector CD8 T cells were obtained from C57BL6/J or CD45.1 C57BL6/J mice previously i.p. injected with 25 g anti-CD38. Cells were isolated via AutoMACS bead selection and cultured at 200.000 cells per flat bottom 96-well plates in IMDM medium. 100.000 BMDC, cultured via standard protocol using GM-CSF were added in indicated conditions. Cells were restimulated with 0.25 g/ml anti-CD38, 10 ng/ml IL-15, and 0.5 ng/ml TGF, and where indicated 10-20 ng/ml IL-2 or IL-7. Cells were grown for 3 days before analysis or adoptive transfers into full C57BL6/J mice to test for tissue homing. Cells were assessed for the T.sub.RM markers CD69, CD103, the absence of KLRG-1, and expression of CTLA-4.

[0200] In vitro differentiated cells were transferred into mice through intravenous injection. At the indicated time points, animals were sacrificed and lymphocytes from spleen, lungs and small intestine (both IEL and LPL fractions) were isolated following standard methods. Cell populations were analysed by flow cytometry. Transferred cells were distinguished from endogenous cells by their expression of the congenic marker CD45.1 and cell counts were performed using flow cytometry counting beads.

Example 1

Results

Deletion of Tbx21 in FoxP3.sup.+ Cells Reduces Type 1 T.sub.REG Cells

[0201] T.sub.RM cells express T-bet but not Eomes (FIG. 1a, FIG. 7a) 37. T.sub.REG cells express lineage-associated chemokine receptors in different tissues, with immune type 1, 2 and 3 characteristics (FIG. 1b). To test whether T.sub.REG cells expressing T-bet or Eomes influence T.sub.RM cells, the inventors made use of the Foxp3.sup.eYFP-Cre Tbx21.sup.fl/fl Rosa26.sup.tdRFP/tdRFP and Foxp3.sup.eYFP-Cre Eomes.sup.fl/fl Rosa26tdRFP/tdRFP mouse lines (referred to as Foxp3.sup.Tbx21 and Foxp3.sup.Eomes respectively) and control Foxp3.sup.eYFP-Cre Rosa26.sup.tdRFP/tdRFP line (Foxp3.sup.WT) (methods, FIG. 14). T-bet and Eomes activate the transcription of genes important in type 1 immune responses, such as the chemokine receptor CXCR3, trans-activated by T-bet.sup.38. In line with enhanced type 1 inflammation in the absence of T-bet in T.sub.REG cells.sup.35, 39 (FIG. 7b), spleen, but not thymus, showed proportional increases in CXCR3.sup.+CD4.sup.+ and CXCR3.sup.+CD8.sup.+ T cells in Foxp3.sup.Tbx21 mice (FIG. 1c-d). Numbers of CD4.sup.+Foxp3 or T.sub.REG (CD4.sup.+Foxp3.sup.+) cells in thymus or spleen were similar (FIG. 7c-h), but spleen CD8.sup.+ T cells showed an increased trend in Foxp3.sup.Tbx21 animals (FIG. 7e).sup.29, 35, 39. No signs of autoimmunity in mice up to three months of age were observed.

[0202] The inventors confirmed that Foxp3-specific targeting, CD4.sup.+CXCR3.sup.+Foxp3, but not CD4.sup.+CXCR3.sup.+Foxp3.sup.+, T cells were present in Foxp3.sup.Tbx21 mice (FIG. 1c-e), but observed an increase in the proportion and numbers of CXCR3.sup.+ T.sub.REG cells in peripheral lymphoid organs of Foxp3.sup.Eomes mice (FIG. 7i-k). The excision of T-bet in T.sub.REG cells resulted in altered distribution, but not numbers, of T.sub.REG subsets, with an increase in type 3 T.sub.REG cells (FIG. 1f, FIG. 7l-n). T.sub.REG cell populations in the LPL showed a more activated phenotype compared with those present in the secondary lymphoid organs (SLO), expressing higher levels of CD44 (FIG. 1g). Neuropilin-1 (Nrpl-1) and transcription factor Helios, were present mainly in SLO T.sub.REG cells but reduced in the intestine. T.sub.REG cells show a similar phenotype in Foxp3.sup.Tbx21 compared with Foxp3WT control mice (FIG. 1h-i) 29, the co-inhibitory receptor killer-cell lectin like receptor G1 (KLRG1), expressed on effector T cells and T.sub.EM cells.sup.40, 41, is increased on T.sub.REG cells from Foxp3.sup.Tbx21 compared with Foxp3WT control mice (FIG. 1j). Collectively, these data show that in the absence of T-bet-expressing T.sub.REG cells, the number of T.sub.REG cells and their phenotype remains similar, but with alterations in proportions of T.sub.REG subsets.

Excision of Tbx21 or Eomes in T.SUB.REG .Cells Alters CD8 T Cell Distribution

[0203] The splenic CD8.sup.+ T cell compartment of Foxp3.sup.Tbx21 mice show an increase in effector (T.sub.eff)/T.sub.EM T cells (FIG. 2a-b). However, the intestinal intraepithelial fraction in Foxp3.sup.Tbx21 mice show a reduction in CD4 and CD8 T cells compared with Foxp3.sup.WT controls (FIG. 2c). Within the CD8 IEL population the marked decrease in Foxp3.sup.Tbx21 mice is observed within the induced CD8.sup.+, but not in the natural CD8.sup.+ IEL populations (FIG. 2d). The lamina propria (LP) compartment in Foxp3.sup.Tbx21 mice shows a reduction in CD4.sup.+ T cells, but not CD8.sup.+ T cells compared with Foxp3WT controls (FIG. 2e). This difference is apparent throughout all intestinal sections but the colon (FIG. 8a-d), in which CXCR3 and T-bet expression in T.sub.REG cells is disjointed.sup.42.

[0204] Despite altered numbers of CD4.sup.+Foxp3-T cells and T.sub.REG cells in the LPL compartment, and irrespective of the Foxp3-dependent excision of Tbx21 or Eomes, the proportion of CD4.sup.+ T cells and T.sub.REG cells remains stable (FIG. 8e-f). However, the T cell population of Foxp3.sup.Tbx21 animals shows a marked proportional skewing towards CD8 T cells (FIG. 2f), while the opposite is observed in Foxp3.sup.Eomes animals, particularly in the proximal intestine (FIG. 2g). These data indicate that the absence of T-bet or Eomes in T.sub.REG cells, does not alter the proportional distribution between CD4.sup.+Foxp3.sup.+ and CD4.sup.+Foxp3.sup. T cells, but has a marked impact on the proportion of CD8.sup.+ T cell subsets in the small intestine.

Tbx21.sup.+ and Eomes.sup.+ T.sub.REG Cells Influence the CD8 T Cell Memory Compartment

[0205] The reduction of T.sub.RM cells in the intestine and increased proportion of circulating effector/T.sub.EM cells in the absence of T-bet-sufficient T.sub.REG cells suggested a potential role for these cells in the generation or maintenance of T.sub.RM cells. Although there is a reduction in IEL numbers (FIG. 2c-d), all CD8.sup.+ IELs express the T.sub.RM cell markers CD103 and CD69 (FIG. 2h). The LPL compartment in Foxp3.sup.Tbx21, Foxp3.sup.Eomes and Foxp3.sup.WT mice were similar with respect to CD4.sup.+Foxp3.sup. T cells, which express high levels of CD69 with about half co-expressing CD103 (FIG. 8g). Although the inventors did not observe a difference in the phenotype of CD4 T.sub.RM cells, Foxp3.sup.Tbx21 animals showed an overall trend in reduced numbers of CD4.sup.+Foxp3.sup. T cells and CD4.sup.+CD103.sup.+ cell numbers (FIG. 8h).

[0206] In the LPL compartment of Foxp3WT and Foxp3.sup.Eomes animals, most CD8 T cells express the TRIM markers CD69 and CD103 (FIG. 2h-i). In contrast, in Foxp3.sup.Tbx21 animals, over half of the CD8+ T cells do not express CD103 (FIG. 2h-i). Therefore, despite similar total numbers of CD8+ T cells, in the absence of T-bet-expressing T.sub.REG cells, the numbers of CD8+ T.sub.RM cells are reduced in the intestine of these animals, with high proportional contribution of effector over TRY cells (FIG. 2i-j) resulting in a constant ratio between CD4 T cells and CD8 T.sub.RM cells in all three mouse lines (FIG. 8i). These data indicate that immune networks in the intestine are fine-tuned, with increased CD8+ T cell ratios observed in the Foxp3.sup.Tbx21 animals possibly due to the accumulation of CD8+ effector T cells failing to develop into T.sub.RM cells.

Tbx21.sup.+ T.sub.REG Cells Influence T.sub.RM Cell Development in Multiple Tissues

[0207] Upon skin infections, KLRG1.sup.+CD103.sup.CD8.sup.+ effector T cells have been reported in the dermis early, but not late, nor in the epidermis.sup.19. In agreement with the population of CD103.sup.CD8.sup.+ T cells observed in the small intestine of Foxp3.sup.Tbx21 animals under steady state conditions, a marked population of KLRG1.sup.+CD8.sup.+ T cells, around 20% of the total CD8 T cell population, in all sections of the small intestine was observed (FIG. 3a). In contrast, Foxp3Eomes animals, which harbour increased CXCR3.sup.+ T.sub.REG cells (FIG. 7h), showed a reduction in KLRG1.sup.+CD8.sup.+ T cell numbers in the proximal intestine (FIG. 3b).

[0208] Co-staining with CD103 confirmed the KLRG1 protein to be expressed in a mutually exclusive form with CD103.sup.19, 26, 43, and primarily present in Foxp3.sup.Tbx21 mice (FIG. 3c). The CD103-KLRG1.sup.+CD8 T cells present in Foxp3.sup.Tbx21 animals expressed high levels of Eomes, whereas few were found in Foxp3.sup.WT and even less in Foxp3.sup.Eomes animals (FIG. 3d, FIG. 9a). In agreement with their effector status, KLRG1.sup.+Eomes.sup.+CD8 T cells in Foxp3.sup.Tbx21 animals had reduced expression levels of the pro-survival protein Bcl-2, upregulated during T.sub.RM cell maturation.sup.44, 45 (FIG. 9b). Furthermore, the proportion of cells expressing CD8 homodimers, expressed in conjunction with CD8 heterodimers and characteristic for epithelial memory CD8 T cells.sup.46, was reduced in Foxp3.sup.Tbx21 animals compared with Foxp3.sup.WT controls (FIG. 9c). Lastly, in vivo staining confirmed that the majority of cells isolated from the LPL compartment did not recently circulate (FIG. 9d,e). Taken together, and without wishing to be bound to any particular theory, these data show that in the absence of T-bet expressing T.sub.REG cells, CD8.sup.+ effector T cells accumulate at the intestinal barrier where they do not progress towards T.sub.RM cells.

[0209] The presence of T.sub.RM cells is described in many tissues.sup.4. Consistent with results in the intestine, the liver and lungs of Foxp3.sup.Tbx21 mice contained an increased proportion of effector CD8 T cells, expressing high levels of KLRG1 and Eomes, compared with Foxp3.sup.Eomes and Foxp3.sup.WT animals (FIG. 3e-f). Because CD103 expression is not considered a sufficient marker of T.sub.RM cells in the liver, the inventors assessed the proportions of CD8+CD69+ cells negative for KLRG1 and Eomes. Foxp3.sup.Tbx21 mice contained fewer T.sub.RM cells compared with Foxp3.sup.Eomes and Foxp3.sup.WT mice in the non-lymphoid tissues assessed (FIG. 3g-h). Without wishing to be bound to any particular theory, these data suggest that type 1 T.sub.REG cells are important in the generation of T.sub.RM cells in multiple tissues.

Compromised T.SUB.RM .Cell Compartment Reduces Protection Against Pathogen Invasion

[0210] The inventors hypothesised that reduced T.sub.RM cell numbers in Foxp3.sup.Tbx21 mice could reduce protection against new infections, since bystander-mediated activation of T.sub.RM cells is an important defence mechanism limiting pathogen invasion.sup.47, 48,49. We tested the acute response of intestinal CD8+ T cells by administrating anti-CD3 antibody upon which the LPL T cell response was assessed two days later. Eomes.sup.+CD8 T cells displayed a reduced activity profile compared with Eomes CD8 T cells with increased expression of PD-1 and reduced granzyme B (FIG. 4a,b, FIG. 10a-c).sup.50.

[0211] Next, the inventors challenged mice with the intracellular protozoan parasite Eimeria vermiformis (Ev), which infects murine small intestinal epithelial cells. In this infection model lymphocytes reduce parasite burden (FIG. 10d-f), with CD8+ T cells and IFN playing an important role in the clearance.sup.10, 51, 52. Although type 1 T.sub.REG cells were absent, which could be expected to lead to enhanced T cell-mediated immunity.sup.53, in fact Foxp3.sup.Tbx21 mice showed impaired control of Ev infection compared to Foxp3.sup.WT and Foxp3.sup.Eomes animals (FIG. 4c-f). In contrast to mice devoid of lymphocytes (FIG. 10d-e), but in line with IL-15R-deficient mice required for T.sub.RM cell survival.sup.26, Foxp3.sup.Tbx21 mice, in which more effector cells are present but with an exhausted phenotype, lost body weight compared with Foxp3.sup.WT, Foxp3.sup.Eomes, and Rag2.sup./ animals (FIG. 4g-h, FIG. 10f). These data are in line with T.sub.RM cells offering protection against the apicomplexan parasite Plasmodium in the liver.sup.49 and virus in the skin.sup.26.

Type 1 T.sub.REG Cells Enhance T.sub.RM Development

[0212] T cells from Foxp3.sup.Tbx21 or Foxp3.sup.Eomes mice where indistinguishable from Foxp3WT controls with respect to the expression of Tbet or Eomes, at steady state, upon activation or upon T.sub.RM cell establishment (FIG. 11a-d). To assess if the accumulation of effector T cells and reduction of T.sub.RM cells in tissues of Foxp3.sup.Tbx21 animals (compared to Foxp3WT) was CD8 T cell intrinsic, we generated mixed bone marrow chimeras with CD45.1 controls and Foxp3.sup.Tbx21 mice. The T.sub.RM cells found showed similar contribution from both donors (FIG. 5a-b). Furthermore, we transferred CD8 T cells sourced from Foxp3.sup.Tbx21 mice (CD45.2) into control CD45.1 animals. A day later, mice were challenged with Ev, which is cleared after two weeks.sup.54. The development of CD8.sup.CD45.1CD103.sup.+ T.sub.RM cells was assessed a week after parasite clearance, when T.sub.eff cells have diminished (FIG. 5c). Within the transferred CD45.2.sup.+ population T.sub.RM cells developed with high efficiency (FIG. 5d). Collectively, these results suggest a CD8 T cell extrinsic defect in Foxp3.sup.Tbx21 mice that inhibits the generation of T.sub.RM cells. To confirm this, we transferred CD45.1.sup.+CD8.sup.+ T cells (CD8.sup.CD45.1) into CD45.2.sup.+ Foxp3.sup.Tbx21 or Foxp3.sup.WT animals. At the peak of infection (day 10), T.sub.RM cells and effector T cells are present in the LPLs (FIG. 1l,f). In Foxp3.sup.WT hosts, the majority of transferred CD8.sup.CD45.1 cells showed a characteristic T.sub.RM cell profile of CD103 expression with low Eomes levels (FIG. 5e). In contrast, CD8.sup.CD45.1 T cells transferred into Foxp3.sup.Tbx21 hosts showed partial T.sub.RM cell formation with a majority of these cells showing an effector phenotype, with expression of Eomes and absence of CD103 (FIG. 5e). Accumulated numbers of transferred CD8.sup.CD45.1 T cells were similar in the Foxp3.sup.Tbx21 hosts compared with the Foxp3.sup.WT hosts, with reduced T.sub.RM cells in the former (FIG. 5f). Analysis of mice nine weeks post Ev infection showed reduced numbers of detectable transferred CD8.sup.CD45.1T cells overall in the Foxp3.sup.Tbx21 animals (FIG. 5g). These data confirm that the impaired CD8.sup.+ T.sub.RM cell differentiation observed in the Foxp3.sup.Tbx21 animals is extrinsic to the CD8.sup.+ T cell population. The inventor's transfer system enabled the testing of the hypothesis that T.sub.REG cells facilitate the development of T.sub.RM cells via concomitant transfer of CD8.sup.CD45.1 T cells and T.sub.REG.sup.WT cells into Foxp3.sup.Tbx21 animals (FIG. 11g). In support of the hypothesis, the generation of T.sub.RM cells in Foxp3.sup.Tbx21 animals was restored to levels observed in Foxp3.sup.WT controls in the presence of control T.sub.REG cells (FIG. 5h).

[0213] To understand if T-bet-expressing T.sub.REG cells have specific functional attributes that may explain their role in TRY development, the inventors made use of a recent publically available set of single T.sub.REG cell sequencing data.sup.55. In line with previous reports.sup.42, 56, although small trends may exists, the inventors did not uncover significant differences in T.sub.REG cell effector molecules such as IL-10, IL-35, TGF, CD25, LAG3 or CTLA-4 across T.sub.REG cell subsets defined by the presence of the characteristic lineage transcription factors Tbx21, Gata3 or Rorc (FIG. 5i). Furthermore, T-bet-deficient T.sub.REG cells have been reported to show similar suppressive capacity as control T.sub.REG cells.sup.35, 57.

T.sub.RM Development Relies on T.sub.REG Recruitment to Make TGF Bio-Available Locally

[0214] The inventor's observations relied on the microbial presence under specific pathogen free conditions and the intracellular small intestinal parasite Ev, which provokes a very local response. The inventors made use of our CD8.sup.CD45.1 T cell transfer system (FIG. 5c), challenging the mice with the bacterium Yersinia pseudotuberculosis (Yptb), reported to induce T.sub.RM cells.sup.58,59. In line with results obtained using Ev, Yptb challenge resulted in efficient T.sub.RM cell development in Foxp3.sup.WT animals that was markedly reduced in Foxp3.sup.Tbx21 animals (FIG. 6a,b).

[0215] The transfer model of CD8.sup.CD45.1 T cells into Foxp3.sup.Tbx21 mice enabled the inventors to investigate the contribution T.sub.REG cells make to promote T.sub.RM cell development. In the absence of T-bet, T.sub.REG cells express similar levels of CD103, CCR6 and P-selectin.sup.35, but are unable to express CXCR3, important for localisation of T cells to areas of infection in non-lymphoid tissues.sup.7,35,39,60. The local inflammatory environment controls recruitment of T.sub.RM precursor cells.sup.58, 61, and T.sub.REG cells (FIG. 6c). Importantly, the T.sub.REG cells recruited upon Ev infection predominantly show a type 1 phenotype, expressing CXCR3 (FIG. 6d, FIG. 11g-h). Taking into account the absence of alterations in effector and T.sub.RM cells in the colon of Foxp3.sup.Tbx21 mice, where expression of CXCR3 is not T-bet dependent, the inventors hypothesised that T-bet expression in a subpopulation of T.sub.REG cells facilitates the recruitment of these cells to the site of infection and brings them in close proximity with TRY precursor cells. Conform this, Foxp3-dependent excision of Tbx21 resulted in reduced recruitment of T.sub.REG cells upon Ev infection (FIG. 6c), largely due to those expressing CXCR3 (FIG. 6d). In agreement with recruiting type 1 T.sub.REG cells, the inventors found increased expression of the CXCR3 ligand, CXCL10 in intestinal tissues upon Ev infection (FIG. 6e). CD4 T cell numbers are reduced under steady state conditions in the LPL compartment of Foxp3.sup.Tbx21 mice (FIG. 1e), and could play an additional role in T.sub.RM cell generation. However, Ev infection resulted in robust recruitment of CD4 T cells to the LPL compartment with a predominant T helper 1 phenotype (FIG. 12a,b). Making use of the transfer system (FIG. 5a), upon concomitant transfer with CD8.sup.CD45.1 cells, CXCR3-deficient T.sub.REG cells were unable to support efficient development of T.sub.RM cells compared with CXCR3-sufficient controls (FIG. 6f).

[0216] Aggregates of CD8.sup.+ and CD4.sup.+ T cells together with other immune cells such as macrophages and dendritic cells but without B cells, in areas of microbial invasion are commonly observed.sup.58, 62, 63, 64, 65. Interactions between CD4.sup.+ and CD8.sup.+ T cells, although not required for T cell maintenance.sup.59, likely constitute distinct microenvironments that may support T.sub.RM differentiation. In line, the inventors frequently observed transferred CD8.sup.CD45.1 T cells in close proximity with Foxp3-expressing T.sub.REG cells in Foxp3.sup.WT mice, which were not readily observed in Foxp3.sup.Tbx21 animals despite similar CD8 T cell infiltration (FIG. 6g, FIG. 12c).

[0217] The requirement of CXCR3 to promote T.sub.RM development suggests T.sub.REG provide a short range acting or cell-bound effector molecule. Type 1 cytokines, such as IL-12, can maintain high levels of T-bet and Eomes, thereby preventing the differentiation of T.sub.RM cells and the expression of CD103. IL12RB2-deficient CD8+ T cells have increased proportions of cells expressing CD103 and T cell clusters have higher TGF transcripts.sup.59. IL-10 could reduce IL-12 expression and dendritic cell maturation.sup.66. However, IL-10-deficient T.sub.REG cells are able to assist in the efficient development of T.sub.RM cells (FIG. 6h), and IL-10 deficient animals did not show a reduction in the T.sub.RM cell compartment (FIG. 12d,e). Furthermore, EBI.sub.3-deficient T.sub.REG cells, unable to generate IL-35, similarly facilitated the generation of T.sub.RM cells (FIG. 6i), nor was the T.sub.RM cell compartment reduced in EBI3-deficient bone marrow chimeric animals (FIG. 12g,h).

[0218] Many cells, especially at the mucosal barrier, are able to make TGF.sup.67. Yet, TGF is produced as an inactive precursor, which requires cleavage from its latency-associated peptide. TGF- has potent cell modulation activity, acting on numerous immune and non-immune cell types, hence its availability is strictly regulated in the local microenvironment. It was recently shown that T.sub.REG cells can activate TGF via the integrin v8 and that this protein is upregulated in activated/effector T.sub.REG cells, thereby reducing local bioactive TGF68, and the inventors hypothesised that specific recruitment of CXCR3-expressing T.sub.REG cells, which do not show differential expression for TGF1 or Itgb8 under steady state (FIG. 5f, FIG. 12f).sup.42, to sites with effector CD8 T cells may enable the local release of TGF. Similar to Foxp3.sup.Tbx21 mice, bone marrow chimeras generated from Foxp3.sup.ltg88 mice showed a decrease in T.sub.RM cells and an increase in KLRG1-expressing effector CD8+ T cells (FIG. 12g,i). Importantly, in the absence of Itg8 only in T.sub.REG cells, there was inefficient promotion of T.sub.RM cell generation (FIG. 6j). To understand if T.sub.REG-derived TGF plays a deterministic role, the inventors used Foxp3.sup.Tgf1 mice. In line with Foxp3.sup.ltg88 mice, the absence of TGF.sub.1 from T.sub.REG cells only resulted in increased effector T cells and reduced proportion of T.sub.RM cells (FIG. 12g,j). Upon adoptive transfer, T.sub.REG cells deficient in supplying TGF.sub.1 could not rescue the development of T.sub.RM cells in Foxp3.sup.Tbx21 mice (FIG. 6k). Collectively, and without wishing to be bound to any particular theory, the data shows that T.sub.REG cells are recruited via T-bet-induced expression of CXCR3 produce TGF.sub.1 and make it local bioavailability of via the expression of v8 integrin to promote the development of T.sub.RM cells in inflamed tissues.

Discussion

[0219] The induction of long-lived cellular immunity in non-lymphoid tissues is important to protect against reinfection, as well as a major aim in vaccine design. The inventor's data supports a model in which CD8+ T cells home to tissues as effector cells or memory cell precursors, which subsequently differentiate into T.sub.RM cells upon receiving local cues.sup.69. T cell activation in SLOs induces the expression of a large variety of tissue homing receptors that guide activated T cells to non-lymphoid tissues ensuring that effector T cells inspect most peripheral tissues.sup.69, 70. The unique profile of T.sub.RM cells suggests that factors in the tissue microenvironment instruct the differentiation of effector cells into T.sub.RM cells.

[0220] The inventor's data is based on localised infection models and a polyclonal TCR repertoire. Using localised infection models, it has been shown that optimal T.sub.RM cell development, but not maintenance, requires inflammation-mediated trafficking and cognate antigen in the local microenvironment.sup.61, 71, 72. Although this is in contrast with observations using systemic viral infections where IEL numbers remain stable.sup.69, the inventor's observations are in line with previously reported small intestinal infection.sup.58, and suggest this is a characteristic of local inflammation. Local cues, such as cytokines and secondary antigen encounter may be required for T.sub.RM cell differentiation from recruited effector or memory precursor T cells. The inventor's data supports this model and extends it with the need to recruit T.sub.REG cells to the site of inflammation and their ability to raise bioactive TGF levels that facilitate effector-to-memory development. Upon total T.sub.REG cell depletion, numbers of T.sub.RM cells in the central nervous system were reduced upon viral infection.sup.73, suggesting a role of T.sub.REG cells in the development or maintenance of T.sub.RM cells. The inventors extend this observation by showing that local recruitment of type 1 T.sub.REG cells is critical, whereupon expression of Itg8 promotes T.sub.RM development, which critically relies on locally supplied TGF and its bioavailability.sup.23, 26, 59. Local antigen can retain CD8+ T cells in tissues, which form stable contacts with infected cells and whereupon CD69 is re-expressed, a process that requires CXCR3 expression.sup.74. Although in non-inflamed tissues the inventors report a reduction in CD4 and T.sub.REG cells, CD4 T cells are recruited upon inflammation. Although the supplementation of T.sub.REG cells is sufficient to enhance T.sub.RM cell development, this does not exclude a supportive role of CD4 T cells. The inventors show that CXCR3 expression, also identifying type 1 T.sub.REG cells in humans.sup.75, is required to recruit T.sub.REG cells to the site of inflammation providing a rational for the requirement of the upstream transcription factor T-bet. In the absence of CXCR3, T.sub.REG cell tissue recruitment is limited, resulting in enhanced type 1 immunity and immunopathology.sup.42, 76. Although the absence of T.sub.REG cells is able to enhance immune responses, even resulting in sterile immunity, loss of subsequent immunity was reported.sup.53. The inventors show here that type 1 T.sub.REG cells provide TGF and make it available locally with the expression of v8 integrin, thereby facilitating the development of T.sub.RM cells, supporting life-long immune surveillance and increasing tissue protection against invading microorganisms.

[0221] The inventors observed reduced T.sub.RM differentiation in several tissues assessed in the absence of T-bet-expressing T.sub.REG cells. This highlights that specific tissue microenvironments do not play a critical role in the development of T.sub.RM cells or the recruitment of type 1 T.sub.REG cells. Nevertheless, tissue specific differences may alter the amplitude of T.sub.RM development or their phenotype. T.sub.RM cells in the intestine are known to predominantly produce IFN, while those in the epidermis have been shown to be able to produce IL-17 after microbial challenge. Furthermore, additional tissue insults can alter epidermal T.sub.RM cell function, contributing to wound repair.sup.77,78. The colon was the notable exception in which the inventors did not find alterations in T.sub.RM or effector cells, nor were ratios in T cell subsets altered, in the absence of type 1 T.sub.REG cells. Although T.sub.REG cells require T-bet to express CXCR3 and to be recruited to inflammatory sites, T-bet does not seem to control CXCR3 expression in the colon.sup.42. The disjunction between T-bet and CXCR3 in the colon suggests alternative immune regulation in the organ harbouring the largest content of microbes.

[0222] TGF is a potent driver of CD103 expression on CD8+ T cells in vitro and in vivo.sup.22, and has been shown to reduce KLRG1 expression.sup.43. Furthermore, the importance of reducing inflammation for T.sub.RM cell development is suggested by diminished CD103-expression during chronic infection.sup.23,79. In addition, TGFRII-deficient CD8 T cells fail to become or remain T.sub.RM cells.sup.19, 58. In addition to CD103.sup.+ T.sub.RM cells, a CD103.sup. T.sub.RM cell population has been reported.sup.22, 58, 62. The stability of this population may depend on tissue type and antigen persistence. In the inventor's models in control mice, looking at steady state under specific pathogen-free conditions, as well as after Ev challenge, CD103-T cells were a minor population. Instead, CD103-T cells observed in Foxp3.sup.Tbx21 mice expressed KLRG1 and high levels of Eomes, characteristics of T cells in a transition phase to express CD103 and switch off Eomes.sup.80. Without wishing to be bound to any particular theory, the inventor's data does reveal an important role for type 1 T.sub.REG cells in T.sub.RM cell development, but a smaller T.sub.RM cell population could still be generated, which suggests other cells may make an additional contribution in releasing TGF. Alternative sources of generation of bioactive TGF have been reported, including stromal epithelial cells, important for the maintenance of T.sub.RM cells.sup.81.

[0223] T.sub.REG cells are critical in dampening excessive immune responses, thereby preventing autoimmunity and immunopathology, and may reduce the amplitude of responses upon infection and vaccination as measured in blood. However, the inventor's data highlights their important role in efficiently generating tissue resident memory T cells from effector or memory precursors, which would otherwise become exhausted. T.sub.REG cells thereby ensure that critical numbers of T cells are available for immunosurveillance in tissues to prevent or reduce re-infection as well as reducing pathogen load of new infections.

Example 2

Results

[0224] The inventors assessed whether the generation of T.sub.RM cells was possible in the absence of T.sub.REG cells in the medium, as detailed in FIG. 15.

[0225] Referring to FIG. 16, there is shown that the addition of TGF in cultures with IL-15, antigen presenting cells (BMDC) and previously activated CD8 T cells is sufficient to establish T.sub.RM features such as continued expression of CD69 and CD103 in the absence of additional T.sub.REG cells.

[0226] Referring to FIG. 17, there is shown that the combination of IL-15, TGF, antigen presenting cells and previously activated CD8 T cells with the addition of IL-7 can enhance the migratory capacity of generated T.sub.RM cells based on their CTLA-4 expression profile (Front. Immunol., 27 Nov. 2018; Brunner-Weinzierl and Rudd; Kieke et al., PLOS One, 27/5/09)

[0227] Referring to FIG. 18, there is shown that the combination of IL-15, TGF, antigen presenting cells and previously activated CD8 T cells with the addition of IL-2 can enhance the migratory capacity of generated T.sub.RM cells based on their CTLA-4 expression profile, but this is not as consistent as the addition of IL-7 in amount per cell or over biological repeats.

[0228] Furthermore, the inventors assessed if the cells produced in vitro maintained their therapeutic properties, in particular, their ability to migrate and survive in vivo inside the tissues, the experimental setup detailed in FIG. 19.

[0229] The inventors have recreated the in vivo conditions in an in vitro setup consisting of effector CD8+ T cells and bone marrow derived dendritic cells (BMDC). The T cells are stimulated in vitro and expanded in a similar manner to the produce a large amounts of cells for T cell therapies. The inventors show that the addition of bioactive TGF can replace the role of T.sub.REG cells in the development of T cells resembling T.sub.RM cells, with continued expression of the markers and tissue retention factors CD69 and CD103 (FIG. 20). CD69 is an activation marker normally transiently expressed upon T cell activation. CD69 is a C-type lectin, which are most likely involved in retention of T.sub.RM cells in non-lymphoid tissues, including solid tumours.sup.98. CD69 can form a complex with sphingosine-1-phosphate (S1P) 1, thereby preventing its binding to the S1P receptor that would trigger T cell egress out of tissues. Furthermore, the data show that the addition of IL-7 and IL-2 induces a strong CTLA-4 expression (FIGS. 17 and 18), which is linked with enhanced T cell migration.sup.99,100, 101. Although CTLA-4 expression appears to be stronger with the addition of IL-2, replicate experiments have shown more consistency with the addition of IL-7 than with the addition of IL-2. Moreover, adding IL-7 resulted in individual cells having stronger CTLA-4 expression.

[0230] The data resulting from transferring the in vitro generated and expanded T cells in vivo show that effector cells, those generated in the absence of TGF are not found in substantial numbers in the tissues (FIGS. 21, 22, 23 and 24). T.sub.RM cells on the other hand, especially when stimulated with IL-7 are readily found 40 days post-transfer including in all organs tested such as the lungs, liver and lamina propria and intra-epithelial compartments of the small intestine (FIGS. 21, 22, 23 and 24).

SUMMARY

[0231] In summary, the inventors have developed a highly novel and innovative protocol to generate T cells (known as T.sub.RM cells) that are able to deeply penetrate tumours (and especially solid tumours) to contribute to a step-change in T cell therapies against tumours or infections. The inventor's protocol results in vitro generated and expanded cells with the phenotype of migratory and tissue penetrating cells based on the expression of CTLA-4, CD69 and CD103. Conform their phenotype and in contrast to effector T cells, the generated cells are readily found in a variety of lymphoid and non-lymphoid tissues at least 40 days after adoptive transfer into a full mouse host. The inventors' work will make important inroads for efficacious treatment of organ infections and for those cancer patients suffering from solid tumours, which are much harder to treat. However, the inventors believe that the tissue-penetrating ability of the T.sub.RM cells will go beyond the targeting of infections or primary tumours and may provide critical organ-wide immunosurveillance directed against metastasis that have migrated to, often less accessible, tissues away from the primary tumour.

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