Clonal chromosomal mosaicism and loss of chromosome Y in elderly men increase vulnerability for SARS-CoV-2

The pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2, COVID-19) had an estimated overall case fatality ratio of 1.38% (pre-vaccination), being 53% higher in males and increasing exponentially with age. Among 9578 individuals diagnosed with COVID-19 in the SCOURGE study, we found 133 cases (1.42%) with detectable clonal mosaicism for chromosome alterations (mCA) and 226 males (5.08%) with acquired loss of chromosome Y (LOY). Individuals with clonal mosaic events (mCA and/or LOY) showed a 54% increase in the risk of COVID-19 lethality. LOY is associated with transcriptomic biomarkers of immune dysfunction, pro-coagulation activity and cardiovascular risk. Interferon-induced genes involved in the initial immune response to SARS-CoV-2 are also down-regulated in LOY. Thus, mCA and LOY underlie at least part of the sex-biased severity and mortality of COVID-19 in aging patients. Given its potential therapeutic and prognostic relevance, evaluation of clonal mosaicism should be implemented as biomarker of COVID-19 severity in elderly people. Among 9578 individuals diagnosed with COVID-19 in the SCOURGE study, individuals with clonal mosaic events (clonal mosaicism for chromosome alterations and/or loss of chromosome Y) showed an increased risk of COVID-19 lethality

Heparan sulfate potentiates leukocyte adhesion on cardiac fibroblast by enhancing Vcam-1 and Icam-1 expression

Cardiac fibroblasts (CF) act as sentinel cells responding to chemokines, cytokines and growth factors released in cardiac tissue in cardiac injury events, such as myocardial infarction (MI). Cardiac injury involves the release of various damage-associated molecular patterns (DAMPs) including heparan sulfate (HS), a constituent of the extracellular matrix (ECM), through the TLR4 receptor activation triggering a strong inflammatory response, inducing leukocytes recruitment. This latter cells are responsible of clearing cell debris and releasing cytokines that promote CF differentiation to myofibroblast (CMF), thus initiating scar formation. CF were isolated from adult male rats and subsequently stimulated with HS or LPS, in the presence or absence of chemical inhibitors, to evaluate signaling pathways involved in ICAM-1 and VCAM-1 expression. siRNA against ICAM-1 and VCAM-1 were used to evaluate participation of these adhesion molecules on leukocytes recruitment. HS through TLR4, PI3K/Ala and NF-KB increased ICAM-1 and VCAM-1 expression, which favored the adhesion of spleen mononuclear cells (SMC) and bone marrow granulocytes (PMN) to CF. These effects were prevented by siRNA against ICAM-1 and VCAM-1. Co-culture of CF with SMC increased alpha-SMA expression, skewing CF towards a pro-fibrotic phenotype, while CF pretreatment with HS partially reverted this effect. Conclusion: These data show the dual role of HS during the initial stages of wound healing. Initially, HS enhance the pro-inflammatory role of CF increasing cytokines secretion; and later, by increasing protein adhesion molecules allows the adhesion of SMC on CF, which trigger CF-to-CMF differentiation.FONDECYT 1170425 FONDAP ACCDiS 15130011 CEAL-AL/2017-02