ABSTRACT
Background: Chronic Kidney disease (CKD) is the risk factor that most increases the risk of lethal COVID-19. However, the underlying molecular mechanisms are unclear. CKD patients have an increased risk of multiple infections due to CKD-associated nonspecific immunodeficiency. Whether specific defects are related to the defense against SARS-CoV-2 is unknown. SARS-CoV-2 and coronavirus-associated receptors and factors (SCARFs) regulate coronavirus cell entry and/or replication. We hypothesized that CKD may alter the expression of SCARF genes. Method(s): A literature search identified 32 SARF genes of which 21 were directly related to SARS-CoV-2 or SARS-CoV infection and assessed their expression in target tissues of COVID-19 (kidneys, lungs, aorta and heart) in experimental CKD in mice fed adenine and compared them with controls. Result(s): Out of 21 SCARF genes, 19 (90%) were differentially expressed in at least one organ in CKD. 15 genes had a differential expression that would be expected to favor SARS-CoV-2 infection and/or severity in at least one organ. Of these, 13 were differentially expressed in the kidney. Only 2 genes reported to protect from SARS-CoV-2, Ifitm3 encoding interferon induced transmembrane protein 3 (IFITM3) and Ly6e encoding lymphocyte antigen 6 family member 6 (LY6E), were downregulated in at least two non-kidney target organs (lung and heart), potentially predisposing to more severe lung/ cardiovascular involvement in COVID-19 (Fig). The largest change was observed for Ifitm3. Conclusion(s): CKD is associated with the differential expression of multiple SCARF genes in target organs of COVID-19. The decreased expression of Ifitm3 and Ly6e in heart and/or lung may contribute to increase the severity of COVID-19 in CKD. These data may allow the development of interventions that decrease the risk of severe COVID-19 in CKD patients.
ABSTRACT
BACKGROUND AND AIMS: Chronic kidney disease (CKD) is the most common risk factor for lethal COVID19 and the risk factor that most increases the risk of death of COVID19 patients. Additionally, acute kidney injury (AKI) is frequent in COVID19 and AKI increases the risk of death. However, the underlying cellular and molecular mechanisms of such increased risk are unclear. SARS-CoV-2 and coronavirusassociated receptors and factors (SCARFs) are required for and/or regulate (in a positive or negative manner) coronary cell entry and/or viral replication. We have now studied changes in the expression of genes encoding for SCARF in the context of acute and chronic kidney disease. METHOD: Data mining of in-house (experimental models of AKI -folic acid nephropathy- and CKD -Unilateral ureteral obstruction- in mice) and publicly available databases (Nephroseq, published single cell transcriptomics studies) of kidney tissue transcriptomics as well as the Protein Atlas database. RESULTS: Out of 28 SCARF genes identified by Singh et al (Cell Reports 2020), 26 were represented in the experimental AKI database. Of them 7 (27%) were differentially expressed during AKI (FDR <0.05), 4 of them upregulated and 3 downregulated (Figure 1.A). Additionally, 27 were represented in the experimental CKD database. Of them 17 (63%) were differentially expressed during experimental CKD, 6 of them upregulated and 11 downregulated (Figure 1.B). Two genes were consistently upregulated (Ctsl and Ifitm3) and two consistently downregulated (Tmprss2 and Top3b) in both experimental AKI and CKD (Figure 1.A and B). They encode cathepsin L, interferon induced transmembrane protein 3, transmembrane serine protease 2, DNA topoisomerase III beta, respectively. Single cell transcriptomics databases localized Ctsl expression mainly to podocytes and tubular cells while protein atlas showed clear tubular staining. The main site of Ifitm3 was endothelium in both datasets and it was also localized to leukocytes by single cell transcriptomics. Tmprss2 was mainly localized to tubular cells in both datasets while Top3b was widely expressed in parenchymal renal cells, endothelium and leucocytes in single cell transcriptomics. Increased kidney expression of Ifitm3 and decreased expression of Tmprss2 and Top3b were confirmed in diverse CKD datasets in Nephroseq. CONCLUSION: Both AKI and CKD are associated with differential expression of SCARF genes in kidney tissue, the impact of CKD appearing to be larger. Characterization of these changes and their functional impact in kidney tissue and beyond the kidneys may provide clues to the increased risk of severe or lethal COVID19 in kidney disease patients. (Figure Presented).
ABSTRACT
BACKGROUND AND AIMS: COVID-19 is a pandemic with no end in sight. There is only one approved antiviral agent but global stocks are deemed insufficient. Despite in vitro antiviral activity, clinical trials of chloroquine and hydroxychloroquine were disappointing, and they may even impair outcomes. Chloroquine causes zebroid deposits reminiscent of Fabry disease (a-galactosidase A deficiency) and endothelial cells are key targets of COVID-19. The study aims to investigate in vitro the effect of enzyme replacement therapy (ERT) in chloroquine-induced endothelial dysfunction. METHOD: We have explored the effect of chloroquine on cultured endothelial cells and its modulation by recombinant α-galactosidase A (agalsidase-β). Following doseresponse studies, 0.5 μg/mL chloroquine was added to cultured human endothelial cells. Neutral red and Lysotracker were used to assess lysosomes. Cytotoxicity was evaluated by the 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide) - MTT assay and cell stress by assessing reactive oxygen species (ROS) and nitric oxide (NO). In endothelial cells, chloroquine induced dose-dependent cytotoxicity at in vitro test concentrations for COVID-19 therapy. RESULTS: Chloroquine significantly induced the accumulation of acid organelles (P<0.05), increased ROS levels, and decreased NO production (P<0.05), in vitro. These adverse effects of chloroquine on endothelial cell biology were decreased by agalsidase-β (P<0.05). CONCLUSION: Chloroquine-induced endothelial cell cytotoxicity and stress is attenuated by agalsidase-β treatment. This suggests that endothelial cell injury may contribute to the failure of chloroquine as therapy for COVID-19 and may be at least in part related to causing dysfunction of the lysosomal enzyme α-galactosidase A. (Figure Presented).