Epithelial Cell Biology/Function in InflammationINCREASED CATHEPSIN EXPRESSION CORRELATES WITH SARS-COV-2 INFECTION IN HUMAN IBD ENTEROIDS
Introduction
Coronavirus Disease 2019 (COVID-19) is an ongoing public health crisis that has sickened or precipitated death in millions. The etiologic agent of COVID-19, Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), infects the intestinal epithelium, with viral RNA shed in the stool, and can induce GI symptoms similar to the human inflammatory bowel diseases (IBD). An international surveillance epidemiology study, SECURE-IBD, reported that the standardized mortality ratio trends higher in IBD patients (1.5–1.8) and that 5-aminosalicylic acid (5-ASA) therapy correlates with poor outcome. Together these data indicate patients with IBD may represent a particularly vulnerable population during this COVID-19 pandemic.
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Methods
Published datasets GSE75214 and GSE16879 were downloaded and expression levels of select genes were querried using RStudio. Primary human ileal spheroids (enteroids), derived from healthy donors and patients with Crohn’s disease (CD), were grown on 2D transwells until confluent. Cells were then differentiated for 3d before infection with a modified vesicular stomatitis virus expressing the SARS-CoV-2 spike protein (VSV-SARS-CoV-2) and green fluorescent protein (GFP) for 1 h at a multiplicity of
Results
VSV-SARS-CoV-2 was able to infect both healthy and CD enteroids as determined by co-staining of GFP, indicative of virus infection, and the viral receptor ACE2. However, levels of GFP fluorescence did not correlate with ACE2 expression in CD enteroids. A subset of CD enteroids exhibited enhanced protease expression (TMPRSS2, TMPRSS4, CTSL), each of which correlated with higher viral RNA levels (P=0.04, P=0.002, P=0.006, respectively). In Vero E6 cells, 5-ASA inhibited the replication of a
Conclusions
Host proteases, particularly the lysosomal protease CTSL, contribute to the infection of CD enteroids and may represent novel therapeutic targets in patients with IBD and COVID-19. 5-ASA modulates the expression of several epithelial genes relevant to SARS-CoV-2 infection, yet does not alter viral replication in healthy enteroids.