Cytokine storm-based mechanisms for extrapulmonary manifestations of SARS-CoV-2 infection

A histopathological analysis of extrapulmonary lesions in fatal coronavirus disease (COVID-19)

INTRODUCTION

The coronavirus disease 2019 (COVID-19) pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), presents diverse clinical manifestations and multi-organ involvement. This study aimed to evaluate the extra-pulmonary histopathological patterns underpinning COVID-19-induced lesions in cardiac, hepatic, renal, brainstem, and splenic tissues.

MATERIALS AND METHODS

The research involved conventional forensic autopsies conducted between April 2020 and April 2021 on individuals with confirmed SARS-CoV-2 infection in Cluj-Napoca, Romania. Tissues were processed and stained for histological examination. Differences in patients with and without diffuse alveolar damage (DAD) were evaluated.

RESULTS

In our study of 79 COVID-19 autopsies conducted on unvaccinated patients besides lung involvement, the patients had histological changes in at least two out of five (brain, heart, liver, kidney, and spleen) organs. Notable findings include hepatitis observed in 46.8 % of cases, 21.5 % with lobular hepatitis, and 41.8 % with liver steatosis. Additionally, 69.6 % exhibited acute tubular necrosis, and 55.7 % had varying degrees of splenic lymphocyte depletion. Almost 41 % of cases had pericardial effusion, 36.7 % myocarditis, 24.1 % myocardial infarction, and 12.7 % of cases had encephalitis. Acute tubular necrosis (78.6 %) was the most frequent histopathological finding observed in patients with DAD. Myocarditis was described in 45.9 % of the patients without DAD.

DISCUSSION

The autopsy findings in our cohort of COVID-19 victims align with international scientific literature. Distinguishing viral-induced myocarditis, encephalitis, hepatitis, or systemic inflammatory syndrome remains challenging.

CONCLUSION

Post-mortem analysis identified lesions associated with SARS-CoV-2 in multiple organs, highlighting the systemic nature of the virus and emphasizing the need for continued research into organ-specific damage and long-term sequelae of COVID-19.

"Idiopathic" minimal change nephrotic syndrome: a podocyte mystery nears the end

The discovery of zinc fingers and homeoboxes (ZHX) transcriptional factors and the upregulation of hyposialylated angiopoietin-like 4 (ANGPTL4) in podocytes have been crucial in explaining the cardinal manifestations of human minimal change nephrotic syndrome (MCNS). Recently, uncovered genomic defects upstream of ZHX2 induce a ZHX2 hypomorph state that makes podocytes inherently susceptible to mild cytokine storms resulting from a common cold. In ZHX2 hypomorph podocytes, ZHX proteins are redistributed away from normal transmembrane partners like aminopeptidase A (APA) toward alternative binding partners like IL-4Rα. During disease relapse, high plasma soluble IL-4Rα (sIL-4Rα) associated with chronic atopy complements the cytokine milieu of a common cold to displace ZHX1 from podocyte transmembrane IL-4Rα toward the podocyte nucleus. Nuclear ZHX1 induces severe upregulation of ANGPTL4, resulting in incomplete sialylation of part of the ANGPTL4 protein, secretion of hyposialylated ANGPTL4, and hyposialylation-related injury in the glomerulus. This pattern of injury induces many of the classic manifestations of human minimal change disease (MCD), including massive and selective proteinuria, podocyte foot process effacement, and loss of glomerular basement membrane charge. Administration of glucocorticoids reduces ANGPTL4 upregulation, which reduces hyposialylation injury to improve the clinical phenotype. Improving sialylation of podocyte-secreted ANGPTL4 also reduces proteinuria and improves experimental MCD. Neutralizing circulating TNF-α, IL-6, or sIL-4Rα after the induction of the cytokine storm in Zhx2 hypomorph mice reduces albuminuria, suggesting potential new therapeutic targets for clinical trials to prevent MCD relapse. These studies collectively lay to rest prior suggestions of a role of single cytokines or soluble proteins in triggering MCD relapse.

Bioinformatics and system biology analysis revealed the crosstalk between COVID-19 and osteoarthritis

BACKGROUND

The global coronavirus disease 2019 (COVID-19) outbreak has significantly impacted public health. Moreover, there has been an association between the incidence and severity of osteoarthritis (OA) and the onset of COVID-19. However, the optimal diagnosis and treatment strategies for patients with both diseases remain uncertain. Bioinformatics is a novel approach that may help find the common pathology between COVID-19 and OA.

METHODS

Differentially expressed genes (DEGs) were screened by R package "limma." Functional enrichment analyses were performed to find key biological functions. Protein-protein interaction (PPI) network was constructed by STRING database and then Cytoscape was used to select hub genes. External data sets and OA mouse model validated and identified the hub genes in both mRNA and protein levels. Related transcriptional factors (TF) and microRNAs (miRNAs) were predicted with miRTarBase and JASPR database. Candidate drugs were obtained from Drug Signatures database. The immune infiltration levels of COVID-19 and OA were evaluated by CIBERSORT and scRNA-seq.

RESULTS

A total of 74 common DEGs were identified between COVID-19 and OA. Receiver operating characteristic curves validated the effective diagnostic values (area under curve > 0.7) of four hub genes (matrix metalloproteinases 9, ATF3, CCL4, and RELA) in both the training and validation data sets of COVID-19 and OA. Quantitative polymerase chain reaction and Western Blot showed significantly higher hub gene expression in OA mice than in healthy controls. A total of 84 miRNAs and 28 TFs were identified to regulate the process of hub gene expression. The top 10 potential drugs were screened including "Simvastatin," "Hydrocortisone," and "Troglitazone" which have been proven by Food and Drug Administration. Correlated with hub gene expression, Macrophage M0 was highly expressed while Natural killer cells and Mast cells were low in both COVID-19 and OA.

CONCLUSION

Four hub genes, disease-related miRNAs, TFs, drugs, and immune infiltration help to understand the pathogenesis and perform further studies, providing a potential therapy target for COVID-19 and OA.