Evidence of SARS-CoV-2 infection in postmortem lung, kidney, and liver samples, revealing cellular targets involved in COVID-19 pathogenesis

Abstract

There is an urgent need to understand severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-host interactions involved in virus spread and pathogenesis, which might contribute to the identification of new therapeutic targets. In this study, we investigated the presence of SARS-CoV-2 in postmortem lung, kidney, and liver samples of patients who died with coronavirus disease (COVID-19) and its relationship with host factors involved in virus spread and pathogenesis, using microscopy-based methods. The cases analyzed showed advanced stages of diffuse acute alveolar damage and fibrosis. We identified the SARS-CoV-2 nucleocapsid (NC) in a variety of cells, colocalizing with mitochondrial proteins, lipid droplets (LDs), and key host proteins that have been implicated in inflammation, tissue repair, and the SARS-CoV-2 life cycle (vimentin, NLRP3, fibronectin, LC3B, DDX3X, and PPARγ), pointing to vimentin and LDs as platforms involved not only in the viral life cycle but also in inflammation and pathogenesis. SARS-CoV-2 isolated from a patient´s nasal swab was grown in cell culture and used to infect hamsters. Target cells identified in human tissue samples included lung epithelial and endothelial cells; lipogenic fibroblast-like cells (FLCs) showing features of lipofibroblasts such as activated PPARγ signaling and LDs; lung FLCs expressing fibronectin and vimentin and macrophages, both with evidence of NLRP3- and IL1β-induced responses; regulatory cells expressing immune-checkpoint proteins involved in lung repair responses and contributing to inflammatory responses in the lung; CD34+ liver endothelial cells and hepatocytes expressing vimentin; renal interstitial cells; and the juxtaglomerular apparatus. This suggests that SARS-CoV-2 may directly interfere with critical lung, renal, and liver functions involved in COVID-19-pathogenesis.

SARS-CoV-2 mechanisms of cell tropism in various organs considering host factors

“…Notably, viral RNA is not detected in these cell types. Reports suggest the presence of infected nonmuscle cells in COVID-19 cardiac tissue, while another report indicates SARS-CoV-2 antigen in cardiomyocytes, suggesting potential direct myocardial damage [ 125 ]. Human induced pluripotent stem cell (hiPSC)-derived heart cells show susceptibility to SARS-CoV-2 infection, resulting in myofibrillar fragmentation and nuclear disruption, potentially linked to dysregulation of genes associated with the nucleoskeleton-cytoskeleton complex.…”

NLRP3 Inflammasome Activation by Oxidative Stress and Its Implications for Vaccination-Related Adverse Events

“…Inflammation and formation of cytokine-generating inflammasome complexes are crucial components of the defense mechanism against pathogens and a key event in the innate immune response to vaccination 2,3 . Activation of the NLRP3 inflammasome has been identified as an early component of the immune response to vaccination [4][5][6] and has also been implicated as an important contributor to SARS-CoV-2 morbidity and mortality [7][8][9][10][11] . As illustrated in Figure 1, initial priming of the NLRP3 response upon antigen exposure involves Toll-like receptor (TLR) recognition and NF-κB-mediated transcription of genes coding for inflammasome components, including NLRP3, ASC (apoptosis-associated speck-like protein containing a caspase recruitment domain), procaspase-1, pro-IL-1β and pro-IL-18.…”

“…As noted above, NLRP3 activation plays a central role in the cytokine storm initiated by SARS-CoV-2 infection, leading in some cases to severe life-threatening cardiopulmonary dysfunction. In fact, multiple postmortem studies of these individuals have provided direct evidence of NLRP3 inflammasome activation in the lung and other tissues [7][8][9][10][11] . Factors that increase the likelihood of severe COVID-19, include old age, type 2 diabetes, obesity, asthma, and cardiovascular disease, all of which are associated with oxidative stress and increased NLRP3 activation [122][123][124][125][126][127][128][129][130][131] .…”

Nucleocapsid protein accumulates in renal tubular epithelium of a post-COVID-19 patient

“…Still, it is heavily debated whether SARS-CoV-2 enters or actively replicates in kidney tissue. The presence of SARS-CoV-2 in kidney during COVID-19 has previously been investigated by multiple studies employing RNA in situ hybridization, immunohistochemistry (IHC), transmission electron microscopy (TEM), confocal microscopy, quantitative reverse transcription PCR, or RNA assays ( 11 – 18 ). In these studies, SARS-CoV-2 proteins or RNA were detected in multiple extra-pulmonary tissues; including liver, spleen, heart, prostate, uterus, colon, kidney, lymph node, and thyroid.…”