ENTERIC NEURONAL VASOACTIVE INTESTINAL PEPTIDE MEDIATES SARS-COV-2 ASSOCIATED DIARRHEA
Gastroenterology
; 162(7):S-364, 2022.
Article
in English
| EMBASE | ID: covidwho-1967299
ABSTRACT
Background:
Diarrhea is present in up to 36.6% of patients with COVID-19. The mechanism of SARS-CoV-2-induced diarrhea remains unclear. We hypothesized that enterocyte-enteric neuron interactions were important in SARS-CoV-2-induced diarrhea. SARS-CoV-2 induces endoplasmic reticulum (ER) stress in enterocytes causing the release of Damage Associated Molecular Patterns (DAMPs). The DAMPs then stimulate the release of enteric neurotransmitters that disrupt gut electrolyte homeostasis. The influence of ER stress and enteric neuronderived vasoactive intestinal peptide (VIP) on the expression of Na+/H+ exchanger 3 (NHE3), an important transporter that mediates intestinal Na+/fluid absorption, was further examined.Methods:
SARS-CoV-2 propagated in Vero-E6 cells was used to infect Caco-2, a human colon epithelial cell line that expresses SARS-CoV-2 entry receptor ACE2. The expression of ER stress markers, phospho-PERK, Xbp1s, and DAMP proteins, was examined by Western blotting. Primary mouse enteric neurons were treated with a conditioned medium of Caco- 2 cells that were infected with SARS-CoV-2 or treated with tunicamycin. VIP expression by cultured enteric neurons was assessed by RT-qPCR, Western blotting, and ELISA. Membrane expression of NHE3 was determined by surface biotinylation.Results:
SARS-CoV-2 infection of Caco-2 cells led to increased expression of phospho-PERK and Xbp1s indicating increased ER stress. Infected Caco-2 cells secreted DAMP proteins, including HSP70 and calreticulin, as revealed by proteomic and Western analyses. The expression of VIP mRNA in enteric neurons was up-regulated after treatment with a conditioned medium of SARS-CoV-2- infected Caco-2 cells (Mock, 1 ± 0.0885;and SARS-CoV-2, 1.351 ± 0.020, P=.005). CD91, a receptor for HSP70 and calreticulin, is abundantly expressed in cultured mouse and human enteric neurons and was up-regulated by a conditioned medium of SARS-CoV-2-infected Caco-2 cells. Tunicamycin, an inducer of ER stress, also induced the secretion of HSP70 and calreticulin, mimicking SARS-CoV-2 infection. Moreover, co-culture of enteric neurons with tunicamycin-treated Caco-2 cells stimulated VIP production as determined by ELISA. Co-treatment of Caco-2 cells with tunicamycin (apical) and VIP (basolateral) induced a synergistic decrease in the membrane expression of NHE3.Conclusions:
Our findings demonstrate that SARS-CoV-2 infection of enterocytes leads to ER stress and the release of DAMPs that up-regulate the expression and release of VIP by enteric neurons. The presence of ER stress together with the secreted VIP, in turn, inhibits fluid absorption through the downregulation of brush-border membrane expression of NHE3 in the enterocytes. These data highlight epithelial-neuronal crosstalk in COVID-19 related diarrhea. (Figure Presented)
angiotensin converting enzyme 2; calreticulin; electrolyte; endogenous compound; heat shock protein 70; low density lipoprotein receptor related protein; messenger RNA; neurotransmitter; sodium ion; sodium proton exchange protein 3; tunicamycin; vasoactive intestinal polypeptide; X box binding protein 1; animal cell; animal experiment; biotinylation; brush border; Caco-2 cell line; coculture; conditioned medium; conference abstract; controlled study; coronavirus disease 2019; diarrhea; down regulation; endoplasmic reticulum stress; enzyme linked immunosorbent assay; gastrointestinal tract; gene expression; HCE cell line (colon epithelium); homeostasis; human; intestine cell; male; mouse; nerve cell; nonhuman; protein expression; Severe acute respiratory syndrome coronavirus 2; Vero C1008 cell line; Western blotting
Full text:
Available
Collection:
Databases of international organizations
Database:
EMBASE
Language:
English
Journal:
Gastroenterology
Year:
2022
Document Type:
Article
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