AMP5A modulates Toll-like receptors 7 and 8 single-stranded RNA immune responses in PMA-differentiated THP-1 and PBMC.

Background: Dysregulation of antiviral immunity has been implicated in the progression of acute respiratory syndrome coronavirus 2 infection into severe cases of coronavirus disease of 2019 (COVID-19). Imbalances in the inflammatory response drive the overabundant production of pro-inflammatory cytokines and chemokines. The low molecular weight fraction of 5% human serum albumin commercial preparation (AMP5A) is a novel biologic drug currently under clinical investigation for the treatment of osteoarthritis and the hyperinflammatory response associated with COVID-19. This study aims to elucidate AMP5A effects following the activation of immune cells with agonists of Toll-like receptor (TLR) 7 and/or 8, which detect ssRNA viral sequences. Methods: CXCL10 ELISAs were used to evaluate the dynamics of myeloid cells activated with CL075 and CL307, agonists of TLR7/8 and TLR7, respectively. In addition, enrichment analysis of gene sets generated by ELISA arrays was utilized to gain insight into the biologic processes underlying the identified differentially expressed cytokine profiles. Finally, relative potency (REP) was employed to confirm the involvement of mechanisms of action paramount to AMP5A activity. Results: AMP5A inhibits the release of CXCL10 from both CL075- and CL307-activated PMA-differentiated THP-1 and peripheral blood mononuclear cells. Furthermore, AMP5A suppresses a distinct set of pro-inflammatory cytokines (including IL-1ß, IL-6, IL-12, and CXCL10) associated with COVID-19 and pro-inflammatory NF-κB activation. REP experiments using antagonists specific for the immunomodulatory transcription factors, peroxisome proliferator-activated receptor γ, and aryl hydrocarbon receptor, also indicate that these pathways are involved in the ability of AMP5A to inhibit CXCL10 release. Conclusion: Due to the biphasic course of COVID-19, therapeutic approaches that augment antiviral immunity may be more beneficial early in infection, whereas later interventions should focus on inflammation suppression. In this study, we show that AMP5A inhibits TLR 7/8 signaling in myeloid cells, resulting in a decrease in inflammatory mediators associated with hyperinflammation and autoimmunity. Furthermore, data demonstrating that AMP5A activates immunomodulatory transcription factors found to be protective in lung disease is provided. These findings suggest that the modes and mechanisms of action of AMP5A are well suited to treat conditions involving dysregulated TLR 7/8 activation.

C1 esterase inhibitor-mediated immunosuppression in COVID-19: friend or foe?

From asymptomatic to severe, SARS-CoV-2, causative agent of COVID-19, elicits varying disease severities. Moreover, understanding innate and adaptive immune responses to SARS-CoV-2 is imperative since variants such as Omicron negatively impact adaptive antibody neutralization. Severe COVID-19 is, in part, associated with aberrant activation of complement and Factor XII (FXIIa), initiator of contact system activation. Paradoxically, a protein that inhibits the three known pathways of complement activation and FXIIa, C1 esterase inhibitor (C1-INH), is increased in COVID-19 patient plasma and is associated with disease severity. Here we review the role of C1-INH in the regulation of innate and adaptive immune responses. Additionally, we contextualize regulation of C1-INH and SERPING1, the gene encoding C1-INH, by other pathogens and SARS viruses and propose that viral proteins bind to C1-INH to inhibit its function in severe COVID-19. Finally, we review the current clinical trials and published results of exogenous C1-INH treatment in COVID-19 patients.

A Randomized Controlled Trial to Evaluate the Safety and Efficacy of a Novel Inhaled Biologic Therapeutic in Adults with Respiratory Distress Secondary to COVID-19 Infection.

INTRODUCTION: Inhaled therapeutics may act to directly target and attenuate lung inflammation due to COVID-19. An inhalation form of a novel biologic drug, AMP5A, is being developed as an immunomodulatory agent to treat dysregulated immune responses and is being studied in hospitalized patients to treat respiratory complications due to COVID-19. METHODS: A randomized, controlled, phase I trial was conducted to evaluate hospitalized adults with respiratory distress secondary to COVID-19. Patients received the standard care (SOC) for COVID-19, including respiratory therapy, corticosteroids, and antiviral therapies such as remdesivir. Patients were randomized 1:1 to inhalation treatment with AMP5A as an adjunct to SOC or to SOC alone (control). AMP5A was administered via inhalation daily for 5 days via hand-held nebulizer, non-invasive ventilator, or mechanical ventilation. Safety and clinical efficacy endpoints were evaluated. RESULTS: Forty subjects were enrolled and randomized (n = 19 AMP5A, n = 21 control). Remdesivir was used in fewer AMP5A subjects (26%) than control (52%), and dexamethasone was administered for most subjects (84% AMP5A, 71% control). The study met its primary endpoint with no AMP5A treatment-related adverse events (AEs), and the incidence and severity of AEs were comparable between groups: 18 AEs for control (8 mild, 1 moderate, 9 severe) and 19 AEs for AMP5A (7 mild, 7 moderate, 5 severe). Notably, subjects treated with AMP5A had fewer deaths (5% vs. 24%), shorter hospital stay (8 days vs. 12 days), fewer ICU admissions (21% vs. 33%), and a greater proportion with improved clinical outcomes than control. CONCLUSION: The phase I clinical results indicate inhaled AMP5A is safe, is well tolerated, and could lead to fewer patients experiencing deterioration or death. Based on the treatment effect (i.e., reduced mortality), a phase II trial has been initiated. TRIAL REGISTRATION: Clinicaltrials.gov identifier: NCT04606784.

Clinically distinct COVID-19 cases share notably similar immune response progression: A follow-up analysis.

Inflammatory responses to the novel coronavirus SARS-CoV-2, which causes COVID-19, range from asymptomatic to severe. Here we present a follow-up analysis of a longitudinal study characterizing COVID-19 immune responses from a father and son with distinctly different clinical courses. The father required a lengthy hospital stay for severe symptoms, whereas his son had mild symptoms and no fever yet tested positive for SARS-CoV-2 for 29 days. Father and son, as well as another unrelated COVID-19 patient, displayed a robust increase of SERPING1, the transcript encoding C1 esterase inhibitor (C1-INH). We further bolstered this finding by incorporating a serum proteomics dataset and found that serum C1-INH was consistently increased in COVID-19 patients. C1-INH is a central regulator of the contact and complement systems, potentially linking COVID-19 to complement hyperactivation, fibrin clot formation, and immune depression. Furthermore, despite distinct clinical cases, significant parallels were observed in transcripts involved in interferon and B cell signaling. As symptoms were resolving, widespread decreases were seen in immune-related transcripts to levels below those of healthy controls. Our study provides insight into the immune responses of likely millions of people with extremely mild symptoms who may not be aware of their infection with SARS-CoV-2 and implies a potential for long-lasting consequences that could contribute to reinfection risk.

LMWF5A suppresses cytokine release by modulating select inflammatory transcription factor activity in stimulated PBMC.

BACKGROUND: Dysregulation of transcription and cytokine expression has been implicated in the pathogenesis of a variety inflammatory diseases. The resulting imbalance between inflammatory and resolving transcriptional programs can cause an overabundance of pro-inflammatory, classically activated macrophage type 1 (M1) and/or helper T cell type 1 (Th1) products, such as IFNγ, TNFα, IL1-ß, and IL12, that prevent immune switching to resolution and healing. The low molecular weight fraction of human serum albumin (LMWF5A) is a novel biologic drug that is currently under clinical investigation for the treatment of osteoarthritis and the hyper-inflammatory response associated with COVID-19. This study aims to elucidate transcriptional mechanisms of action involved with the ability of LMWF5A to reduce pro-inflammatory cytokine release. METHODS: ELISA arrays were used to identify cytokines and chemokines influenced by LMWF5A treatment of LPS-stimulated peripheral blood mononuclear cells (PBMC). The resulting profiles were analyzed by gene enrichment to gain mechanistic insight into the biologic processes and transcription factors (TFs) underlying the identified differentially expressed cytokines. DNA-binding ELISAs, luciferase reporter assays, and TNFα or IL-1ß relative potency were then employed to confirm the involvement of enriched pathways and TFs. RESULTS: LMWF5A was found to significantly inhibit a distinct set of pro-inflammatory cytokines (TNFα, IL-1ß, IL-12, CXCL9, CXCL10, and CXCL11) associated with pro-inflammatory M1/Th1 immune profiles. Gene enrichment analysis also suggests these cytokines are, in part, regulated by NF-κB and STAT transcription factors. Data from DNA-binding and reporter assays support this with LMWF5A inhibition of STAT1α DNA-binding activity as well as a reduction in overall NF-κB-driven luciferase expression. Experiments using antagonists specific for the immunomodulatory and NF-κB/STAT-repressing transcription factors, peroxisome proliferator-activated receptor (PPAR)γ and aryl hydrocarbon receptor (AhR), indicate these pathways are involved in the LMWF5A mechanisms of action by reducing LMWF5A drug potency as measured by TNFα and IL-1ß release. CONCLUSION: In this report, we provide evidence that LMWF5A reduces pro-inflammatory cytokine release by activating the immunoregulatory transcription factors PPARγ and AhR. In addition, our data indicate that LMWF5A suppresses NF-κB and STAT1α pro-inflammatory pathways. This suggests that LMWF5A acts through these mechanisms to decrease pro-inflammatory transcription factor activity and subsequent inflammatory cytokine production.

Inhibition of Bruton tyrosine kinase in patients with severe COVID-19.

Patients with severe COVID-19 have a hyperinflammatory immune response suggestive of macrophage activation. Bruton tyrosine kinase (BTK) regulates macrophage signaling and activation. Acalabrutinib, a selective BTK inhibitor, was administered off-label to 19 patients hospitalized with severe COVID-19 (11 on supplemental oxygen; 8 on mechanical ventilation), 18 of whom had increasing oxygen requirements at baseline. Over a 10-14 day treatment course, acalabrutinib improved oxygenation in a majority of patients, often within 1-3 days, and had no discernable toxicity. Measures of inflammation - C-reactive protein and IL-6 - normalized quickly in most patients, as did lymphopenia, in correlation with improved oxygenation. At the end of acalabrutinib treatment, 8/11 (72.7%) patients in the supplemental oxygen cohort had been discharged on room air, and 4/8 (50%) patients in the mechanical ventilation cohort had been successfully extubated, with 2/8 (25%) discharged on room air. Ex vivo analysis revealed significantly elevated BTK activity, as evidenced by autophosphorylation, and increased IL-6 production in blood monocytes from patients with severe COVID-19 compared with blood monocytes from healthy volunteers. These results suggest that targeting excessive host inflammation with a BTK inhibitor is a therapeutic strategy in severe COVID-19 and has led to a confirmatory international prospective randomized controlled clinical trial.