TREATMENT FOR VIRAL RESPIRATORY INFECTIONS
20230192838 · 2023-06-22
Assignee
Inventors
Cpc classification
G01N2800/52
PHYSICS
International classification
Abstract
The present invention relates to pharmaceutical compositions and methods for the treatment of viral respiratory infections. More specifically, the present invention relates to IL-18 antagonists and their use in the treatment of a viral respiratory infection in a subject having: (a) a deficiency of IL-18 binding protein; and/or (b) a deficiency of natural killer cells and/or a deficiency of functional natural killer cells.
Claims
1. An IL-18 antagonist for use in treating a viral respiratory infection in a subject having metabolic syndrome, coronary artery disease, hypertension, atherosclerosis, type II diabetes or a combination thereof.
2. The IL-18 antagonist for use of claim 1, wherein the subject has hypertension.
3. The IL-18 antagonist for use of claim 1, wherein the subject has metabolic syndrome and one or more of coronary artery disease, hypertension, atherosclerosis and type II diabetes.
4. The IL-18 antagonist for use of any one of claims 1 to 3, wherein treating the viral respiratory infection prevents the development of a severe form of a viral respiratory syndrome caused by the viral respiratory infection.
5. The IL-18 antagonist for use of any one of claims 1 to 4, wherein the viral respiratory infection is an infection by a coronavirus, influenza virus, human parainfluenza virus, respiratory syncytial virus, rhinovirus, human metapneumovirus, human bocavirus or adenovirus.
6. The IL-18 antagonist for use of claim 5, wherein the coronavirus is a severe acute respiratory syndrome (SARS) coronavirus or a Middle East respiratory syndrome (MERS) coronavirus, optionally wherein the coronavirus is SARS coronavirus 2 (SARS-CoV2).
7. The IL-18 antagonist for use of any one of claims 1 to 6, wherein the viral respiratory infection is Coronavirus Disease 2019 (COVID-19), SARS, MERS and/or wherein the viral respiratory infection causes viral pneumonia, viral bronchitis or viral bronchiolitis.
8. The IL-18 antagonist for use of any one of claims 1 to 7, wherein the IL-18 antagonist is a protein that binds IL-18, preferably free IL-18.
9. The IL-18 antagonist for use of any one of claims 1 to 8, wherein the IL-18 antagonist is a mammalian or viral IL-18 binding protein, preferably human IL-18 binding protein.
10. The IL-18 antagonist for use of any one of claims 1 to 9, wherein the IL-18 antagonist is an IL-18 binding protein comprising: (i) an amino acid sequence as set forth in any one of SEQ ID NOs: 1-9, preferably any one of SEQ ID NOs: 1-4; (ii) an amino acid sequence with at least 70% sequence identity to an amino acid sequence as set forth in any one of SEQ ID NOs: 1-9, preferably any one of SEQ ID NOs: 1-4; or (iii) a IL-18 binding fragment of (i) or (ii).
11. The IL-18 antagonist for use of any one of claims 1 to 10, wherein the IL-18 antagonist is recombinant human IL-18 binding protein.
12. The IL-18 antagonist for use of any one of claims 1 to 8, wherein the IL-18 antagonist is an antibody that binds specifically to IL-18, preferably free IL-18.
13. The IL-18 antagonist for use of claim 12, wherein said antibody is a human or humanised antibody and/or a monoclonal antibody.
14. The IL-18 antagonist for use of claim 12 or 13, wherein said antibody is an IgG antibody.
15. The IL-18 antagonist for use of any one of claims 12 to 14, wherein said antibody is an IL-18 binding fragment of an antibody.
16. The IL-18 antagonist for use of any one of claims 12 to 15, wherein said antibody is a Fab′, Fab, F(ab′)2, single domain antibody, TandAbs dimer, Fv, scFv, dsFv, ds-scFv, Fd, linear antibody, minibody, diabody, bispecific antibody fragment, bibody, tribody, sc-diabody, kappa(lambda) body, BiTE, DVD-Ig, SIP, SMIP, DART or a small antibody mimetic comprising one or more CDRs.
17. The IL-18 antagonist for use of any one of claims 1 to 16, wherein the IL-18 antagonist is provided in a pharmaceutical composition comprising a pharmaceutically acceptable diluent or excipient, optionally further comprising one or more additional therapeutically active agents.
18. The IL-18 antagonist for use of any one of claims 1 to 17, wherein the IL-18 antagonist is parenterally administered.
19. The IL-18 antagonist for use of any one of claims 1 to 18, wherein the IL-18 antagonist is administered intravenously, subcutaneously or via inhalation.
20. A method for selecting or identifying a subject for treatment according to any one of claims 1 to 19 comprising: (i) assaying the amount of free IL-18 in a blood sample obtained from the subject; and (ii) comparing the amount of free IL-18 in the blood sample to the amount of free IL-18 in blood of a subject with the same viral respiratory infection that has a less severe manifestation thereof, wherein when the amount of free IL-18 in the blood sample of the subject is higher than the amount of free IL-18 in the blood of a subject with the same viral respiratory infection that has a less severe manifestation thereof, the subject is selected for treatment with an IL-18 antagonist, preferably an IL-18 antagonist as defined in any one of claims 8 to 19.
21. A method of treating a viral respiratory infection in a subject in need thereof, wherein the subject has metabolic syndrome, coronary artery disease, hypertension, atherosclerosis, type II diabetes or a combination thereof, said method comprising administering an effective amount of an IL-18 antagonist to the subject, thereby treating the subject.
22. The method of claim 21, wherein the viral respiratory infection is as defined in any one of claims 5 to 7 and/or the IL-18 antagonist is as defined in any one of claims 8 to 19.
23. The method of claim 21 or 22, wherein the subject is as defined in claim 2 or 3.
24. The method of any one of claims 21 to 23, wherein treating the viral respiratory infection prevents the development of a severe form of a viral respiratory syndrome caused by the viral respiratory infection.
Description
[0214] The invention will now be further described with reference to the following non-limiting Examples and Figures in which:
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[0219]
[0220]
[0221]
EXAMPLES
Example 1 - An Immunological Model of COVID-19
[0222] Infection with SARS-CoV2 has been described as having two phases,.sup.1 with the majority of individuals experiencing only the first phase. The first phase consists of a flu-like illness, with sufferers describing intermittent fevers, lethargy and a new onset continuous cough. The second phase, starting at around 5-7 days of symptoms is characterised by sudden onset shortness of breath that becomes progressively worse. It is at this stage that patients usually present in the hospital. Those patients that require invasive ventilation on Intensive Care have been noted as strikingly similar, not only in demographic characteristics, but also in clinical presentation. In our hospital in East Surrey, UK, patients requiring Intensive Care support are typically middle aged to elderly males, with one or more metabolic syndrome conditions. Ethnicity has also been noted as a common feature, with a disproportionate number being Black and Ethnic Minorities (BAME).sup.2. Biochemical presentation includes lymphopenia, hyperferritinemia and unrecordable high CRP levels, with clinical features consisting of spiking fevers, hypothermia and acute respiratory distress syndrome (ARDS). Some patients can develop liver failure, kidney failure or encephalopathy, with many patients showing uncontrolled hypertension.
[0223] The above observations have been widely recognised, but the underlying reasons for them have not. The model of COVID-19 immunopathology described below is based on major streams of COVID-19 specific data, histopathological autopsy analysis, transcriptomic and immune analysis of bronchoalveolar lavage fluid, and peripheral blood flow cytometric analysis. This unique model of COVID-19 immunopathology has resulted in the surprising determination that blockade of IL-18 activity will find utility in the treatment of subjects with viral respiratory infections, such as COVID-19, particularly in subjects with an acquired innate immune deficiency (i.e. presenting as a deficiency in IL-18BP, NK cells and/or functional NK cells) such as in subjects with metabolic syndrome, coronary artery disease, hypertension, atherosclerosis, diabetes or a combination thereof.
Summary of the Major Streams of COVID-19 Specific Data
[0224] Histopathological analysis across a series of studies.sup.3,4,5,6,7,8 has revealed similar and dissimilar features. Similar features include the presence of diffuse alveolar disease, alveolar oedema and proteinaceous exudates, with the formation of hyaline membranes, all indicative of ARDS. Divergence is found on the degree of inflammatory cell tissue infiltrate, with some papers finding none.sup.1,5 as compared to low to moderate amounts.sup.2,3,4 though the finding of mononuclear inflammatory cells in alveolar air spaces with or without multinucleated syncytial cells and desquamated, enlarged type II pneumocytes is reported reliably across all studies. Particularly interesting was the mention in several studies of the predominance of CD4+ T lymphocytic.sup.4,6 infiltrates as compared to a relative paucity of scattered CD8+ cells.sup.4. In addition, autopsy analysis of spleens from 10 patients with COVID-19 have demonstrated lymphocytic depletion with signs of necrosis and degeneration, indicating a potential cytophatic effect of the virus on lymphocytes as a mechanism of viral evasion..sup.9
[0225] Bronchoalveolar lavage fluid (BALF) immune analysis.sup.10 of 6 COVID-19 positive patients (3 with severe disease; 3 with mild disease) demonstrates two major findings. The first relates to a massive clonal expansion of macrophages in severe disease as compared to mild disease and healthy controls, along with a change in the macrophage population towards pro-fibrotic and alveolar macrophage types, away from the monocyte-derived type. The second relates to a preponderance of CD8+ T-cells in mild COVID-19 disease as compared to severe disease, with greater activation of CD4+ T-cells (T-regulatory cells, proliferating cells and CCR7+ cells) in severe disease. Of note, more than 50% of CD8+ T cells in mild COVID-19 disease were expanded clones, likely representing SARS-CoV2 specific cytotoxic T-cells, due to repeated antigenic presentation. The amplification index of these clonal CD8+ T cells was significantly higher in all three mild COVID-19 cases, as compared to the severe cases, from which the authors surmised that early and rapid specific CD8+ T cell expansion was key in limiting viral replication and activity. Transcriptomic analysis.sup.11 of BALF and peripheral blood mononuclear cells (PBMCs) through RNA-seq processing, to identify up-regulated genes specific to COVID-19 infection, revealed a “cytokine storm” type picture in which, contrary to the autopsy analysis of spleens described above, viral readings were high in BALF but absent in PBMCs. Instead, PBMCs showed evidence of significant upregulation in the p53 apoptotic signalling pathway gene. Taken together, these findings may indicate that programmed cell death, may also be a key cause of clinically observed lymphopenia, predictive of disease severity..sup.12
[0226] Flow cytometry analysis.sup.13 of peripheral blood cells in SARS-CoV2 positive patients found that at hospital admission, mild disease was characterised by decreased CD8+ T cell numbers, as compared to healthy controls, with preserved natural killer (NK) cell numbers, while severe disease was characterised by a depletion of both. In addition, functional failure of NK cells was also seen, with IFN-y and Granzyme B release significantly lower in COVID-19 patients as compared to healthy controls. Longitudinal flow-cytometry analysis, correlating cellular analysis with clinical outcomes,.sup.14 found depletion in CD8+ T-cells in severe as opposed to mild cases, at time points before day 3, and between days 7-9 of the disease, reached the significance threshold, while CD4+, CD3+ and NK cell numbers were non-significantly decreased throughout the analysis period. This was confirmed by more extended analysis, .sup.15 which found that day 10 of the disease is a key time-point, separating patients into three groups: mild, moderate and severe, according to both degree of lymphopenia and clinical severity. Patients who died of severe disease showed lymphopenia below 5% persistently, throughout their disease after day 13, while severe cases who recovered never showed a fall in lymphocyte count below 9%. Analysis of the particular lymphocytic subsets beyond early infection has demonstrated a Th1 response.sup.16,17. CD4+ Th1 cells in patients with severe disease express aberrant co-expression of GM-CSF, IL-6 and IFN-y, with CD8+ T-cells also demonstrating higher levels of GM-CSF expression. Peripheral blood monocytes in such patients co-expressed CD14 and CD16, the signature of a high inflammatory state, indicating their activation by the cytokine milieu induced by Th1 activation. Of particular note, these monocytes were capable of secreting both GM-CSF and IL-6 too. Thus, while CD4+ Th1 cells secrete GM-CSF IL-6, attracting peripheral blood mononuclear cells to invade the lung as macrophages, mediating epithelial injury and ARDS, monocytes also secrete GM-CSF and IL-6, to stimulate myelopoiesis and attract more mononuclear cells.
[0227] Bringing these streams of evidence together, a relatively consistent picture emerges: severe disease is characterised by depletion and functional exhaustion of NK cells and CD8+ T cells, alongside a subsequent Th1 response, while mild disease is characterised by a pivot towards CD8+ T-cell activation with preserved NK cell numbers and function. Since NK cells and CD8+ T cells are critical for viral clearance, this makes sense. To put these facts in their correct context however, an understanding of the process of virus-induced inflammation is required.
NK Cell Dysfunction Underpins Poor Viral Control
[0228] NK cells constitute a first line of defence that even precede the peak of the cytotoxic T-cell response. NK cells are able to directly bind and lyse cells, and are activated to do so through integration of inputs from activating natural killer cell receptors (aNKR) and inhibitory natural killer cell receptors (iNKR), with loss of iNKRs often sufficient to stimulate lysis of a target cell.sup.18. iNKRs consist of the subsets of the major histocompatibility class 1 (MHC-I) human leukocyte antigens (HLA) A, B or C, while aNKRs consist of two major groups: NKG2D receptors, such as UL-16 Binding Proteins (ULBP) and the MHC-I related chain (MIC) proteins, and the natural cytotoxicity receptors (NCRs) NKp30, NKp44, NKp46. NK cell activation in response to a virus is vital, and buys time for the cytotoxic T-cell response as well as the later adaptive response to ramp up.
[0229] The importance of NK cells in viral control comes to the fore in Macrophage Activation Syndrome (MAS). MAS is a form of secondary Hemophagocytic lymphohistiocytosis (HLH); primary or “familial” HLH is caused by genetic defects in perforin deployment..sup.19 Perforin insertion into antigen presenting cells (APCs) are the key means by which NK cells and CD8+ T cells eliminate virally infected cells. Some genetic defects relate to pore formation (PRF1) while others relate to vesicle priming (UNC13D), vesicle fusing (RAB27A), vesicle docking (STX11), or other functions relating to perforin delivery and release. Failure of this key pathway means that NK cells and CD8+ T cells are unable to destroy APCs, despite being continuously challenged by antigens. The consequence of super-antigen presentation is activation of the inflammasome, an understanding of which is key to appreciating this model of IL-18 mediated pathogenesis described herein.
[0230] One of the mortality risk factors associated with severe COVID-19 disease has been demonstrated in one retrospective study.sup.20 as increasing age. This study also demonstrated significant differences between those who did not survive COVID-19 as compared to those who died, in features of the metabolic syndrome, notably in incidence of hypertension (48% vs 23%) diabetes (31% vs 14%) and coronary artery disease (24% vs 1%). NK cells are impaired both with increasing age and in metabolic syndrome conditions. With increasing age, both the cytotoxic capacity of NK cells and their capability to secrete cytokines, become impaired.sup.21. In metabolic syndrome conditions, which are characterised by high levels of circulating free fatty acids, NK cells undergo “re-programming”, as a result of peroxisome proliferator-activated receptor (PPAR)-driven lipid accumulation, through disruption of mTOR-mediated glycloysis.sup.22. This is important because successful switching to mTOR-mediated glycloysis from oxidative phophorylation is necessary for NK cellular activation, and associated functions such as trafficking of the cytotoxic machinery to the NK cell-target synapse.sup.23, with inhibition of lipid transport into NK cell mitochondria restoring cytotoxic function. This may explain the demographic observation that individuals from an African and Indo-Pakistani Asian background are disproportionately suffering from the severe manifestation of COVID-19, since these groups in particular deposit adipose tissue abdominally, accounting for their greater propensity to diabetes at lower obesity levels than European counterparts.sup.24. More diabetogenic fat may result in greater free fatty acid levels in the blood, and subsequent greater accumulation of fatty acids in NK cells. The consequence may be what has already been demonstrated and cited above in severe COVID-19 disease: failure of NK cell proliferation and function.
[0231] One particular manner by which NK cell failure may precipitate CD8+ exhaustion and functional depletion, is through the immunomodulatory role NK cells play. In addition to direct antiviral actions, NK cells also play an immunomodulatory role in response to viral infection, by acting to sustain CD8+ T cell populations and functions, by preventing rapid burnout. This was demonstrated elegantly in 2012 as a general principle of viral infections, from lymphocytic choriomeningitis virus (LCMV) Arenavirus, Pichinde virus, and Coronavirus mouse hepatitis virus.sup.25. This team showed that NK cells directly lyse activated CD4+ cells during viral infection. Since CD4+ costimulation is necessary for an effective CD8+ response, the consequence is a weaker CD8+ response. When the viral dose is high, this is important, since it helps to prolong the response to an acute viral infection, helping to ultimately clear it without fatal immunopathology secondary to over-stimulation of CD4+ and CD8+ T-cells, resulting in functional exhaustion and/or a cytokine storm. When the viral dose is moderate, this action of NK cells is detrimental to the host response, but the viral dose is not high enough to cause fatality. Thus, the NK cell acts to immunomodulate the host innate response, balancing antiviral activity against immunopathology.
[0232] Although NK cells are also known to lyse CD8+ T cells directly, especially when the latter become virally infected and downregulate the iNKR interferon I activating receptor (IFNAR),.sup.26 this is unlikely to be the main cause of CD8+ T cell depletion in severe COVID-19, not least because severe COVID-19, as demonstrated, is characterised by early NK cell depletion and failure too. It is more likely therefore that failure of NK cell-CD4+ T cell regulation sits at the heart of CD8+ T cell functional exhaustion and depletion in severe COVID-19.
[0233] Thus, the result of a deficiency in cytotoxic activity of NK cells due to increasing age or metabolic syndrome conditions is poorer viral control. Viral escape results in repeated antigenic stimulation, and unopposed activation of the inflammasome.
Inflammasome-----NK Cell Interactions Regulate Free IL-18
[0234] The inflammasome is a cytosolic multiprotein complex, activated by interferons (IFNs) released from dendritic cells and macrophages upon recognition of bacterial or viral “pathogen-associated molecular patterns” or “danger-associated molecular patterns” released by damaged or dying cells. There are different types of inflammasomes, categorised into pyrin-domain containing sensors (NLRP3, Al M2 and Pyrin) and caspase-activation and recruitment domain (CARD) containing sensors (NLRC4 and NLRP1b).sup.27. Inflammasomes are stimulated by inputs as diverse as ATP, bacterial toxins, viral DNA or RNA, potassium efflux, calcium influx, and even different types of crystals. In addition, osmotic stress in the form of hyperosmolality has also been found to trigger both NLRP3 and NLRC4 inflammasomes.sup.28. The inflammasomes are thus activated by a wide variety of inputs representing a diverse array of cellular stress events. Inflammasomes end with cleavage, by active subunits of caspase 1 (p10 and p20), of IL-18 and IL-1β from their pro to active forms, in addition to the insertion of pore-forming gasdermin D (GSDMD), which induces pyroptotic cell death by causing swelling and bursting of the cell. Among the two most well studied inflammasomes are NLRP3 and NLRC4, with mutations in NLRC4 having been shown to generate widespread inflammation through the uncontrolled production of free IL-18, through unopposed activation of toll-like receptor 9 (TLR9).
[0235] IFN-y release from NK cells under the influence of IL-18 constitutes a negative feedback loop, as IFN-y is likely an essential promoter of IL-18BP transcription in humans, as it is in murine models.sup.29. Given that IFN-y levels are lower or equivalent in severe cases of COVID-19 as compared to moderate or mild cases.sup.30, and that, as compared to healthy controls, intracellular IFN-y levels in NK cells of COVID-19 patients are very significantly collapsed.sup.31, and that the IL-6/IFN-y ratio is emerging as a correlative marker of disease severity.sup.32, we postulate that IFN-gamma is insufficiently stimulated to trigger release of sufficient IL-18BP in severe form of the disease, when IL-18 is released in much larger quantities in severe disease. The consequence of this would be high free IL-18 levels, even when IL-18 is not excessively released, principally because of a collapse in the production of its binding protein.
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Example 2 - Assessment of Free IL-18 Levels in Subjects With COVID-19
[0268] The immunological model of COVID-19 discussed in Example 1 points to Free IL18 as playing an important role in the pathogenesis of the severe form of COVID-19 and forming the basis of a new drug target to prevent or treat the severe form of the disease. To investigate this hypothesis, research into the levels of Free IL18 at all levels of disease severity in patients with COVID-19, at East Surrey Hospital, Surrey, UK, between 9th October 2020 and 9th January 2021, was undertaken.
[0269] As discussed above, IL18 is regulated by an endogenous ligand: IL18-Binding Protein (IL18BP). IL18BP is constitutively produced by mononuclear cells and is found normally in circulation at a concentration of 2.5 ng/ml. IL18BP has a high affinity for IL18 and effectively silences its biological activity. Thus, it is only free-IL18, unbound to its circulation endogenous ligand, that constitutes the biologically active form of this interleukin. This is a critical point for studies that seek to measure IL18; without measuring the binding protein and thus, the free portion of total-lL18, one cannot know the true reality of biologically active IL18 levels.
Methods
Overview
[0270] Excess blood samples (total 947) were collected longitudinally from routine clinical blood tests of 272 individuals over the age of 18, admitted as inpatients with COVID-19 to East Surrey Hospital, between 9th October 2020 and 9th January 2021.
[0271] Comorbidity data (relating to diabetes and hypertension) and Mortality data, as determined by 60-day mortality and worst PF Ratio (Pa02/Fi02) detected during admission, is presented here for all 272 patients. BMI was only obtainable in 146 patients of 272. Free IL18 results are presented from a subset of 211 of the total 947 blood samples, randomly selected from 116 of 272 patients, at every level of disease severity.
Data Collection
[0272] Excess blood of 0.5 ml - 1 ml was aliquoted from EDTA and Serum samples. Whenever EDTA and Serum samples were available for the same blood-taking event, both were sampled and stored. Centrifugation of samples occurred after at least 30 minutes standing. Aliquoting of samples post centrifugation was followed by immediate labelling and storage of samples at -75° C. No thawing periods occurred between aliquoting and analysis of any sample.
[0273] In addition to sample analysis, each patient’s age, sex, BMI and comorbidity profile as relating to diabetes and hypertension, were recorded, with a comorbidity score formulated (0 = no diabetes or hypertension; 1 = diabetes or hypertension; 2 = diabetes and hypertension). Biochemical features of the disease, including lymphocyte count, percentage lymphopaenia, neutrophil:lymphocyte ratio, CRP level and Ferritin level for each individual blood-taking event were recorded. The following oxygenation parameters at each blood taking event were recorded to assess for severity of disease: PF ratio (Pa02/Fi02), as per the Berlin criteria for severity in acute respiratory distress syndrome (ARDS), and method of oxygen delivery (spontaneous; nasal cannula; face-mask; high-flow nasal oxygen {HFNO}; continuous or bi-level positive airway pressure {CPAP/BIPAP}; intubation). When Pa02 was not available, it was calculated through oxygen saturation (Sa02) records, as per equations given in the literature (Sa02/Fi02=29.6+1.09{Pa02/Fi02}). For patients intubated on intensive care, additional note was made of: number of supported organs (of: vasopressor use, respiratory support or renal-replacement therapy), renal-replacement therapy requirement, ventilation parameters (peak inspiratory airway pressure {Pinsp} and positive end-expiratory pressure {PEEP}), number of ventilated days and number of days in intensive care.
Sample Analysis
[0274] Samples were thawed at room temperature before enzyme-linked immunosorbent assay (ELISA) analysis. Total IL18 was analysed from EDTA samples (Human total IL-18/IL-1F4 Quantikine ELISA kit, R&D Systems, Minneapolis, MN, USA); IL18BP from EDTA samples (Human IL-18 BPa Quantikine ELISA kit, R&D Systems, Minneapolis, MN, USA) and IL18-BP-Complex from Serum samples (Human IL-18/IL-18 BPa Complex DuoSet ELISA, R&D Systems, Minneapolis, MN, USA; DuoSet ELISA Ancillary Reagent Kit 2, R&D Systems, Minneapolis, MN, USA). EDTA and Serum samples analysed were always from the same blood-taking event. ELISA procedures were undertaken in accordance with the ELISA protocols set out in the product datasheets of each kit.
Statistical Analysis
[0275] Levels of Total IL18, IL18BP and IL18-BP-Complex were measured using the above stated methods, and Free IL18 levels were calculated as per the law of Mass Action, detailed in Novick et al. (Cytokine. 2001 Jun 1; 14(6):334-42), using a Kd of 0.05. Statistical analysis was undertaken using R.
Results
Demographics and Comorbidity
[0276] Analysis of the demography of all 272 patients revealed interesting findings.
[0277] Firstly, age was relatively evenly distributed between all categories of disease severity (
[0278] Secondly, as shown by
[0279] The relationship between disease severity (worst PFR) and mortality (
[0280] Finally, BMI showed an important and significant difference between those in the severest disease category and those in the mild (p=2.161x10.sup.-06) and moderate (p=0.023) categories of disease severity (
Free IL 18 and Disease Severity
[0281] Free IL18 assessed against oxygen delivery method, as a marker of severity, revealed a striking and highly statistically significant difference across the major groups (
Discussion
[0282] The data presented here shows a highly statistically significant increase in Free IL18 levels for those requiring high levels of oxygen support (“HFNO” or “I”) as compared to those requiring minimal support (“S” or “NC”). This provides good evidence supporting Free IL18 blockade as a treatment modality in viral respiratory pneumonia.
Comorbidity and Mortality
[0283] Our data shows, in consonance with existing studies.sup.1, that comorbidities relating to the metabolic syndrome, hypertension and diabetes, are associated with worse outcomes in COVID-19 disease. In particular,
[0284] The drive in increased mortality seen with more severe disease also shows a striking association with hypertensive disease, as revealed by
[0285] BMI showed an interesting picture, with BMI increasing steadily between mild to moderate to severe groups in a significant manner, between mild to severe and moderate to severe groups (
Free IL 18 Analysis
[0286] Our data shows a clear relationship between severity of COVID-19 disease, as represented by oxygen delivery methods, and Free IL18 levels. This pattern is consistent across multiple different oxygen delivery method groups, with significant differences between NC or S, and I or HFNO.
[0287] It may be asked why severity of disease for the Free IL18 data was not assessed with concurrent PFR rather than method of oxygen delivery, as was done with the mortality and comorbidity data (
[0288] A major reason is that the demographic and comorbidity data involved assessing comorbidity and mortality for all 272 patients against “worst PF ratio” across the entire range of 947 blood-taking events, thus providing a comprehensive assessment of disease severity.
[0289] The Free IL18 data, however, was taken from a random selection of blood samples; 211 out of a total selection of 947, from 116 patients out of a total of 247, and so “worst” PFR would not reflect disease severity. Indeed, if the “worst PFR” recorded occurred before the Free IL18 blood sampling occurred, the PFR would be actively misleading.
[0290] Another option could be PFR concurrent with the blood sampling event. Yet, PFR concurrent with Free IL18 would not provide an accurate assessment of disease severity either, on account of the fact that the blood samples were taken as a random selection from a larger pool, so as to avoid selection bias. Use of concurrent PFR in an incomplete longitudinal data set would thus be misleading; a high Free IL18 may be noted in a patient with a high PFR, with the deleterious effects of the high Free IL18 resulting in low PFR only in the subsequent days. Without that full longitudinal data set, the effect of the high Free IL18 in driving a later low PFR would go unnoticed. Similarly, a patient may have a high PFR in the recovery phase from severe COVID-19 disease, while still intubated, due to critical care weakness, secondary to an extended period on the ventilator. A high PFR in this case also would obfuscate rather than reveal the severity of the illness the patient had experienced. For these reasons, it was felt that oxygen delivery method would provide a more holistic view of disease severity, given that it represents a holistic trajectory of the patient’s clinical course, rather than a snapshot value.
[0291] Another important effect of the random sampling is that each different Free IL18 result represents a patient at a different time point in their disease. This explains perhaps, why Free IL18 extends so widely in intubated patients, from a high of 300+ pg/ml down to 40 pg/ml. Different patients at different points in their disease course may have different Free IL18 levels, with those in the early, worsening phase, showing higher levels of Free IL18, and those in the recovery phase from severe disease, showing lower levels. This perspective of the effect of the time course helps also explain why those in the “S” and “NC” groupings also showed a range, though with a lower mean Free IL18 level. Without doing further analysis, we cannot tease out whether such individual with higher Free IL18 level in the “S” group, would go on in the subsequent days from that blood sampling event, to develop significant acute respiratory distress syndrome (ARDS), shifting them into the “HFNO” or “I” groups.
[0292] Notwithstanding the attenuating effect of the different time courses on Free IL18 levels, the difference between those on the greatest degree of oxygen support and those on least, is still marked and highly statistically significant. Once contextualised into the patient’s individual disease time-course, through completion of all 947 longitudinally-taken blood samples, we hypothesise that the case for blockade of Free IL18 as a novel drug target in modifying the severity of viral respiratory illness, will become even stronger than it already is.
[0293] Finally, that patient comorbidity increases with more severe disease, as indicated by
REFERENCES
[0294] 1. Fathi M, Vakili K, Sayehmiri F, Mohamadkhani A, Hajiesmaeili M, Rezaei-Tavirani M, Eilami O. The prognostic value of comorbidity for the severity of COVID-19: A systematic review and meta-analysis study. PIoS one. 2021 Feb 16; 16(2):e0246190.