Activation of the AIM2 Receptor in Circulating Cells of Post-COVID-19 Patients With Signs of Lung Fibrosis Is Associated With the Release of IL-1α, IFN-α and TGF-ß.

Severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2), responsible for COVID-19, has caused a global pandemic. Observational studies revealed a condition, herein called as Long-COVID syndrome (PC), that affects both moderately and severely infected patients, reducing quality-of-life. The mechanism/s underlying the onset of fibrotic-like changes in PC are still not well defined. The goal of this study was to understand the involvement of the Absent in melanoma-2 (AIM2) inflammasome in PC-associated lung fibrosis-like changes revealed by chest CT scans. Peripheral blood mononuclear cells (PBMCs) obtained from PC patients who did not develop signs of lung fibrosis were not responsive to AIM2 activation by Poly dA:dT. In sharp contrast, PBMCs from PC patients with signs of lung fibrosis were highly responsive to AIM2 activation, which induced the release of IL-1α, IFN-α and TGF-ß. The recognition of Poly dA:dT was not due to the activation of cyclic GMP-AMP (cGAMP) synthase, a stimulator of interferon response (cGAS-STING) pathways, implying a role for AIM2 in PC conditions. The release of IFN-α was caspase-1- and caspase-4-dependent when AIM2 was triggered. Instead, the release of pro-inflammatory IL-1α and pro-fibrogenic TGF-ß were inflammasome independent because the inhibition of caspase-1 and caspase-4 did not alter the levels of the two cytokines. Moreover, the responsiveness of AIM2 correlated with higher expression of the receptor in circulating CD14+ cells in PBMCs from patients with signs of lung fibrosis.

Post-COVID-19 Patients Who Develop Lung Fibrotic-like Changes Have Lower Circulating Levels of IFN-ß but Higher Levels of IL-1α and TGF-ß.

PURPOSE: SARS-CoV-2 infection induces in some patients a condition called long-COVID-19, herein post-COVID-19 (PC), which persists for longer than the negative oral-pharyngeal swab. One of the complications of PC is pulmonary fibrosis. The purpose of this study was to identify blood biomarkers to predict PC patients undergoing pulmonary fibrosis. PATIENTS AND METHODS: We analyzed blood samples of healthy, anti-SARS-CoV-2 vaccinated (VAX) subjects and PC patients who were stratified according to the severity of the disease and chest computed tomography (CT) scan data. RESULTS: The inflammatory C reactive protein (CRP), complement complex C5b-9, LDH, but not IL-6, were higher in PC patients, independent of the severity of the disease and lung fibrotic areas. Interestingly, PC patients with ground-glass opacities (as revealed by chest CT scan) were characterized by higher plasma levels of IL-1α, CXCL-10, TGF-ß, but not of IFN-ß, compared to healthy and VAX subjects. In particular, 19 out of 23 (82.6%) severe PC and 8 out of 29 (27.6%) moderate PC patients presented signs of lung fibrosis, associated to lower levels of IFN-ß, but higher IL-1α and TGF-ß. CONCLUSIONS: We found that higher IL-1α and TGF-ß and lower plasma levels of IFN-ß could predict an increased relative risk (RR = 2.8) of lung fibrosis-like changes in PC patients.

A lesson from a saboteur: High-MW kininogen impact in coronavirus-induced disease 2019.

The newly identified coronavirus SARS-CoV-2 that spread from China is causing the pandemic COVID-19 with a fatality rate from 5-15%. It causes fever, cough, myalgia, fatigue up to dyspnoea, responsible for hospitalization and artificial oxygenation. SARS-CoV-2 infects human cells using ACE2, the transmembrane protease serine 2 (TMPRSS2) and the SARS-CoV-2 main protease (Mpro ). Once bound to ACE2 and the other two proteases in concert they allow the virus replication and spread throughout the body. Our attention has been focused on the role of ACE2 as its binding to by the virus increases bradykinin and its metabolites, which facilitate inflammation in the lung (causing cough and fever), coagulation and the complement system. These three systems are involved in angioedema, cardiovascular dysfunction and sepsis, pathologies which occur in COVID-19 patients. Thus, we propose that blocking the kallikrein-kinin system with lanadelumab, approved for hereditary angioedema, will prevent facilitation of these 3 systems. LINKED ARTICLES: This article is part of a themed issue on The Pharmacology of COVID-19. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v177.21/issuetoc.