Clinical severity classes in COVID-19 pneumonia have distinct immunological profiles, facilitating risk stratification by machine learning.

Objective: Clinical triage in coronavirus disease 2019 (COVID-19) places a heavy burden on senior clinicians during a pandemic situation. However, risk stratification based on serum biomarker bioprofiling could be implemented by a larger, nonspecialist workforce. Method: Measures of Complement Activation and inflammation in patientS with CoronAvirus DisEase 2019 (CASCADE) patients (n = 72), (clinicaltrials.gov: NCT04453527), classified as mild, moderate, or severe (by support needed to maintain SpO2 > 93%), and healthy controls (HC, n = 20), were bioprofiled using 76 immunological biomarkers and compared using ANOVA. Spearman correlation analysis on biomarker pairs was visualised via heatmaps. Linear Discriminant Analysis (LDA) models were generated to identify patients likely to deteriorate. An X-Gradient-boost (XGB) model trained on CASCADE data to triage patients as mild, moderate, and severe was retrospectively employed to classify COROnavirus Nomacopan Emergency Treatment for covid 19 infected patients with early signs of respiratory distress (CORONET) patients (n = 7) treated with nomacopan. Results: The LDA models distinctly discriminated between deteriorators, nondeteriorators, and HC, with IL-27, IP-10, MDC, ferritin, C5, and sC5b-9 among the key predictor variables during deterioration. C3a and C5 were elevated in all severity classes vs. HC (p < 0.05). sC5b-9 was elevated in the "moderate" and "severe" categories vs. HC (p < 0.001). Heatmap analysis shows a pairwise increase of negatively correlated pairs with IL-27. The XGB model indicated sC5b-9, IL-8, MCP1, and prothrombin F1 and F2 were key discriminators in nomacopan-treated patients (CORONET study). Conclusion: Distinct immunological fingerprints from serum biomarkers exist within different severity classes of COVID-19, and harnessing them using machine learning enabled the development of clinically useful triage and prognostic tools. Complement-mediated lung injury plays a key role in COVID-19 pneumonia, and preliminary results hint at the usefulness of a C5 inhibitor in COVID-19 recovery.

Dual inhibition of complement component 5 and leukotriene B4 by topical rVA576 in atopic keratoconjunctivis: TRACKER phase 1 clinical trial results.

PURPOSE: To evaluate the safety and preliminary efficacy of topical rVA576, a dual inhibitor of complement component 5 (C5) and leukotriene B4 (LTB4), in patients with recalcitrant atopic keratoconjunctivitis (AKC) in the open label phase 1 TRACKER clinical trial. METHODS: Three patients diagnosed with moderate or severe AKC who had been on maximal topical treatment (antihistamines and ciclosporin) for at least three months prior to entry, and showed persistent symptoms and signs of inflammation, were recruited into the trial. Patients received rVA576 eye drops twice a day for 8 weeks. Patients were seen at baseline and weeks 1, 2, 4, 6 and 8. Safety data was recorded and a composite sum score of symptoms and signs was obtained. This score comprised symptoms such as itching, mucous discharge and photophobia, and conjunctival and corneal signs such as hyperemia, tarsal papillae, punctate keratitis and corneal neovascularization, all rated individually from 0 to 3 for a maximum score of 33. RESULTS: Two of the three patients completed the initial open label phase of the trial. The third patient was unable to attend appointments and terminated the study early at day 14. Topical rVA576 was well tolerated with no serious adverse events reported. There was an average improvement in overall clinical score of 53%, composed of an improvement in symptoms of 65% [63.64-66.67%] and signs of 40% [40-40.12%] by day 56. CONCLUSIONS: In this open label phase 1 TRACKER trial, rVA576 eye drops were well tolerated and showed a response across signs and symptoms of active inflammation. This study is exploratory but supports topical rVA576 safety and shows promising efficacy for recalcitrant AKC. A phase 2 randomised control trial is currently underway.

Immune-Mediated Retinal Vasculitis in Posterior Uveitis and Experimental Models: The Leukotriene (LT)B4-VEGF Axis.

Retinal vascular diseases have distinct, complex and multifactorial pathogeneses yet share several key pathophysiological aspects including inflammation, vascular permeability and neovascularisation. In non-infectious posterior uveitis (NIU), retinal vasculitis involves vessel leakage leading to retinal enlargement, exudation, and macular oedema. Neovascularisation is not a common feature in NIU, however, detection of the major angiogenic factor-vascular endothelial growth factor A (VEGF-A)-in intraocular fluids in animal models of uveitis may be an indication for a role for this cytokine in a highly inflammatory condition. Suppression of VEGF-A by directly targeting the leukotriene B4 (LTB4) receptor (BLT1) pathway indicates a connection between leukotrienes (LTs), which have prominent roles in initiating and propagating inflammatory responses, and VEGF-A in retinal inflammatory diseases. Further research is needed to understand how LTs interact with intraocular cytokines in retinal inflammatory diseases to guide the development of novel therapeutic approaches targeting both inflammatory mediator pathways.

Leukotriene B4 and Its Receptor in Experimental Autoimmune Uveitis and in Human Retinal Tissues: Clinical Severity and LTB4 Dependence of Retinal Th17 Cells.

Nomacopan, a drug originally derived from tick saliva, has dual functions of sequestering leukotriene B4 (LTB4) and inhibiting complement component 5 (C5) activation. Nomacopan has been shown to provide therapeutic benefit in experimental autoimmune uveitis (EAU). Longer acting forms of nomacopan were more efficacious in mouse EAU models, and the long-acting variant that inhibited only LTB4 was at least as effective as the long-acting variant that inhibited both C5 and LTB4, preventing structural damage to the retina and a significantly reducing effector T helper 17 cells and inflammatory macrophages. Increased levels of LTB4 and C5a (produced upon C5 activation) were detected during disease progression. Activated retinal lymphocytes were shown to express LTB4 receptors (R) in vitro and in inflamed draining lymph nodes. Levels of LTB4R-expressing active/inflammatory retinal macrophages were also increased. Within the draining lymph node CD4+ T-cell population, 30% expressed LTB4R+ following activation in vitro, whereas retinal infiltrating cells expressed LTB4R and C5aR. Validation of expression of those receptors in human uveitis and healthy tissues suggests that infiltrating cells could be targeted by inhibitors of the LTB4-LTB4 receptor 1 (BLT1) pathway as a novel therapeutic approach. This study provides novel data on intraocular LTB4 and C5a in EAU, their associated receptor expression by retinal infiltrating cells in mouse and human tissues, and in attenuating EAU via the dual inhibitor nomacopan.

Complement C5 activation during influenza A infection in mice contributes to neutrophil recruitment and lung injury.

Influenza virus A (IAV) causes annual epidemics and intermittent pandemics that affect millions of people worldwide. Potent inflammatory responses are commonly associated with severe cases of IAV infection. The complement system, an important mechanism of innate and humoral immune responses to infections, is activated during primary IAV infection and mediates, in association with natural IgM, viral neutralization by virion aggregation and coating of viral hemmagglutinin. Increased levels of the anaphylatoxin C5a were found in patients fatally infected with the most recent H1N1 pandemic virus. In this study, our aim was to evaluate whether targeting C5 activation alters inflammatory lung injury and viral load in a murine model of IAV infection. To address this question C57Bl/6j mice were infected intranasally with 10(4) PFU of the mouse adapted Influenza A virus A/WSN/33 (H1N1) or inoculated with PBS (Mock). We demonstrated that C5a is increased in bronchoalveolar lavage fluid (BALF) upon experimental IAV infection. To evaluate the role of C5, we used OmCI, a potent arthropod-derived inhibitor of C5 activation that binds to C5 and prevents release of C5a by complement. OmCI was given daily by intraperitoneal injection from the day of IAV infection until day 5. Treatment with OmCI only partially reduced C5a levels in BALF. However, there was significant inhibition of neutrophil and macrophage infiltration in the airways, Neutrophil Extracellular Traps (NETs) formation, death of leukocytes, lung epithelial injury and overall lung damage induced by the infection. There was no effect on viral load. Taken together, these data suggest that targeting C5 activation with OmCI during IAV infection could be a promising approach to reduce excessive inflammatory reactions associated with the severe forms of IAV infections.

Arthropod-derived protein EV131 inhibits histamine action and allergic asthma.

Histamine is an important mediator of allergic responses. Arthropods express several biologically active proteins in their saliva, which may allow a prolonged blood meal on the host. Proteins identified and expressed include histamine, serotonin, tryptase, and complement binding proteins. We review here data that scavenging of endogenous histamine by the histamine-binding protein EV131 has a profound inhibitory effect on allergic asthma. Aerosol administration of EV131 prevented airway hyperreactivity and abrogated peribronchial inflammation, eosinophil recruitment, mucus hypersecretion, and IL-4 and IL-5 secretion. Saturation with histamine abrogated the inhibitory effect of EV131 on bronchial hyperreactivity. The data suggest that histamine plays a role in allergies and that scavenging of histamine by EV131 may represent a novel therapeutic strategy in the treatment of allergic diseases.

Histamine scavenging attenuates endotoxin-induced acute lung injury.

Histamine is an important mediator of early and late inflammatory responses. Here we asked whether scavenging of endogenous histamine by the arthropod-derived histamine binding protein EV131 diminishes acute respiratory distress syndrome (ARDS) induced by inhaled endotoxin. We demonstrate that EV131 (360 microg given intranasally) reduced endotoxin-induced bronchoconstriction and recruitment of neutrophils. Furthermore, EV131 administration diminished TNF-alpha and protein leak in the bronchoalveolar lavage fluid. The data suggest that histamine attenuates endotoxin-induced bronchoconstriction and neutrophil recruitment. Therefore, scavenging of histamine by EV131 may represent a novel therapeutic strategy in ARDS.

Arthropod-derived histamine-binding protein prevents murine allergic asthma.

Because histamine receptor type I blockade attenuates allergic asthma, we asked whether complete neutralization of histamine by an arthropod-derived, high affinity histamine-binding protein (EV131) would prevent allergic asthma. Intranasal administration of EV131 given before Ag challenge in immunized mice prevented airway hyperreactivity by 70%, and abrogated peribronchial inflammation, pulmonary eosinophilia, mucus hypersecretion, and IL-4 and IL-5 secretion. Saturation with histamine abrogated the inhibitory effect of EV131 on bronchial hyperreactivity. The inhibitory effect of EV131 on bronchial hyperreactivity was comparable to that of glucocorticosteroids. These results demonstrate that histamine is a critical mediator of allergic asthma. Therefore, complete neutralization of histamine, rather than specific histamine receptor blockade, may have a profound effect on allergic asthma.