Probes for INS

Most COVID-19 victims are old and die from unrelated causes. Here we present twelve complete autopsies, including two rapid autopsies of young patients where the cause of death was COVID-19 ARDS. The main virus induced pathology was in the lung parenchyma and not in the airways. Most coagulation events occurred in the intra-alveolar and not in the intra-vascular space and the few thrombi were mainly composed of aggregated thrombocytes. The dominant inflammatory response was the massive accumulation of CD163 + macrophages and the disappearance of T killer, NK and B-cells. The virus was replicating in the pneumocytes and macrophages but not in bronchial epithelium, endothelium, pericytes or stromal cells. The lung consolidations were produced by a massive regenerative response, stromal and epithelial proliferation and neovascularization. We suggest that thrombocyte aggregation inhibition, angiogenesis inhibition and general proliferation inhibition may have a roll in the treatment of advanced COVID-19 ARDS.

(1) Background: Little is known about the effects of SARS-CoV-2 on the placenta, and whether the maternal inflammatory response is transmitted vertically. This research aims to provide information about the effects of SARS-CoV-2 infection on maternal and fetal immunity. (2) Methods: We have studied placental changes and humoral and cellular immunity in maternal and umbilical cord blood (UCB) samples from a group of pregnant women delivering after the diagnosis of SARS-CoV-2 infection during pregnancy. IgG and IgM SARS-CoV-2 antibodies, Interleukin 1b (IL1b), Interleukin 6 (IL6), and gamma-Interferon (IFN-γ), have been studied in the UCB samples. Lymphocyte subsets were studied according to CD3, CD8, CD4, CD34, and invariant natural Killer T cells (iNKT) markers. We used in situ hybridization techniques for the detection of viral RNA in placentas. (3) Results: During the study period, 79 pregnant women and their corresponding newborns were recruited. The main gestational age at the time of delivery was 39.1 weeks (SD 1.3). We did not find traces of the SARS-CoV-2 virus RNA in any of the analyzed placental samples. Detectable concentrations of IgG anti-SARS-CoV-2 antibodies, IL1b, IL6, and IFN-γ, in UCB were found in all cases, but IgM antibodies anti-ARS-CoV-2 were systematically undetectable. We found significant correlations between fetal CD3+ mononuclear cells and UCB IgG concentrations. We also found significant correlations between UCB IgG concentrations and fetal CD3+/CD4+, as well as CD3+/CD8+ T cells subsets. We also discovered that fetal CD3+/CD8+ cell counts were significantly higher in those cases with placental infarctions. (4) Conclusion: we have not verified the placental transfer of SARS-CoV-2. However, we have discovered that a significant immune response is being transmitted to the fetus in cases of SARS-CoV-2 maternal infection.

COVID-19 has been associated with cardiac injury and dysfunction. While both myocardial inflammatory cell infiltration and myocarditis with myocyte injury have been reported in patients with fatal COVID-19, clinical-pathologic correlations remain limited. The objective was to determine the relationships between cardiac pathological changes in patients dying from COVID-19 and cardiac infection by SARS-CoV-2, laboratory measurements, clinical features, and treatments. In a retrospective study, 41 consecutive autopsies of patients with fatal COVID-19 were analyzed for the associations between cardiac inflammation, myocarditis, cardiac infection by SARS-CoV-2, clinical features, laboratory measurements, and treatments. Cardiac infection was assessed by in situ hybridization and NanoString transcriptomic profiling. Cardiac infection by SARS-CoV-2 was present in 30/41 cases: virus+ with myocarditis (n = 4), virus+ without myocarditis (n = 26), and virus- without myocarditis (n = 11). In the cases with cardiac infection, SARS-CoV-2+ cells in the myocardium were rare, with a median density of 1 cell/cm2. Virus+ cases showed higher densities of myocardial CD68+ macrophages and CD3+ lymphocytes, as well as more electrocardiographic changes (23/27 vs 4/10; P = 0.01). Myocarditis was more prevalent with IL-6 blockade than with nonbiologic immunosuppression, primarily glucocorticoids (2/3 vs 0/14; P = 0.02). Overall, SARS-CoV-2 cardiac infection was less prevalent in patients treated with nonbiologic immunosuppression (7/14 vs 21/24; P = 0.02). Myocardial macrophage and lymphocyte densities overall were positively correlated with the duration of symptoms but not with underlying comorbidities. In summary, cardiac infection with SARS-CoV-2 is common among patients dying from COVID-19 but often with only rare infected cells. Cardiac infection by SARS-CoV-2 is associated with more cardiac inflammation and electrocardiographic changes. Nonbiologic immunosuppression is associated with lower incidences of myocarditis and cardiac infection by SARS-CoV-2.

Since the vast majority of species solely rely on innate immunity for host defense, it stands to reason that a critical evolutionary trait like immunological memory evolved in this primitive branch of our immune system. There is ample evidence that vaccines such as bacillus Calmette-Guérin (BCG) induce protective innate immune memory responses (trained immunity) against heterologous pathogens. Here we show that while BCG vaccination significantly reduces morbidity and mortality against influenza A virus (IAV), it fails to provide protection against severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). In contrast to IAV, SARS-CoV-2 infection leads to unique pulmonary vasculature damage facilitating viral dissemination to other organs, including the bone marrow (BM), a central site for BCG-mediated trained immunity. Finally, monocytes from BCG-vaccinated individuals mount an efficient cytokine response to IAV infection, while this response is minimal following SARS-CoV-2. Collectively, our data suggest that the protective capacity of BCG vaccination is contingent on viral pathogenesis and tissue tropism.

Recent Case reports suggest COVID-19 is associated with collapsing glomerulopathy in African Americans with APOL1 risk alleles, however, it is unclear if disease pathogenesis is similar to HIVAN. Here RNA sequencing analysis of a kidney biopsy specimen from a patient with COVID-19-associated collapsing glomerulopathy and APOL1 risk alleles (G1/G1) revealed similar levels of APOL1 and ACE2 mRNA transcripts as compared to 12 control kidney samples downloaded from the GTEx Portal. Whole genome sequencing of the COVID-19-associated collapsing glomerulopathy kidney sample identified four indel gene variants, three of which are of unknown significance with respect to chronic kidney disease and/or FSGS. Molecular profiling of the kidney demonstrated activation of COVID-19-associated cell injury pathways such as inflammation and coagulation. Evidence for direct SARS-CoV-2 infection of kidney cells was lacking, which is consistent with the findings of several recent studies. Interestingly, immunostaining of kidney biopsy sections revealed increased expression of phospho-STAT3 in both COVID-19-associated collapsing glomerulopathy and HIVAN as compared to control kidney tissue. Importantly, IL-6-induced activation of STAT3 may be a targetable mechanism driving COVID-19-associated acute kidney injury.

As the world continues to experience the COVID-19 pandemic, seasonal influenza remain a cause of severe morbidity and mortality globally. Worse yet, coinfection with SARS-CoV-2 and influenza A virus (IAV) leads to more severe clinical outcomes. The development of a combined vaccine against both COVID-19 and influenza is thus of high priority. Based on our established lipid nanoparticle (LNP)-encapsulated mRNA vaccine platform, we developed and characterized a novel mRNA vaccine encoding the HA antigen of influenza A (H1N1) virus, termed ARIAV. Then, ARIAV was combined with our COVID-19 mRNA vaccine ARCoV, which encodes the receptor-binding domain (RBD) of the SARS-CoV-2 S protein, to formulate the final combined vaccine, AR-CoV/IAV. Further characterization demonstrated that immunization with two doses of AR-CoV/IAV elicited robust protective antibodies as well as antigen-specific cellular immune responses against SARS-CoV-2 and IAV. More importantly, AR-CoV/IAV immunization protected mice from coinfection with IAV and the SARS-CoV-2 Alpha and Delta variants. Our results highlight the potential of the LNP-mRNA vaccine platform in preventing COVID-19 and influenza, as well as other respiratory diseases.