SARS-CoV-2 Induces Epithelial-Enteric Neuronal Crosstalk Stimulating VIP Release

Arun Balasubramaniam; Philip R. Tedbury; Simon M. Mwangi; Yunshan Liu; Ge Li; Didier Merlin; Adam D. Gracz; Peijian He; Stefan G. Sarafianos; Shanthi Srinivasan

doi:10.3390/biom13020207

Biomolecules (Jan 2023)

SARS-CoV-2 Induces Epithelial-Enteric Neuronal Crosstalk Stimulating VIP Release

Arun Balasubramaniam,
Philip R. Tedbury,
Simon M. Mwangi,
Yunshan Liu,
Ge Li,
Didier Merlin,
Adam D. Gracz,
Peijian He,
Stefan G. Sarafianos,
Shanthi Srinivasan

Affiliations

Arun Balasubramaniam: Division of Digestive Diseases, Department of Medicine, Emory University, Atlanta, GA 30322, USA
Philip R. Tedbury: Department of Pediatrics, Emory University, Atlanta, GA 30322, USA
Simon M. Mwangi: Division of Digestive Diseases, Department of Medicine, Emory University, Atlanta, GA 30322, USA
Yunshan Liu: Division of Digestive Diseases, Department of Medicine, Emory University, Atlanta, GA 30322, USA
Ge Li: Division of Digestive Diseases, Department of Medicine, Emory University, Atlanta, GA 30322, USA
Didier Merlin: VA Medical Center Atlanta, Decatur, GA 30033, USA
Adam D. Gracz: Division of Digestive Diseases, Department of Medicine, Emory University, Atlanta, GA 30322, USA
Peijian He: Division of Digestive Diseases, Department of Medicine, Emory University, Atlanta, GA 30322, USA
Stefan G. Sarafianos: Department of Pediatrics, Emory University, Atlanta, GA 30322, USA
Shanthi Srinivasan: Division of Digestive Diseases, Department of Medicine, Emory University, Atlanta, GA 30322, USA

DOI: https://doi.org/10.3390/biom13020207
Journal volume & issue: Vol. 13, no. 2
p. 207

Abstract

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Background: Diarrhea is present in up to 30–50% 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. Methods: Primary mouse enteric neurons (EN) were exposed to a conditioned medium from ACE2-expressing Caco-2 colonic epithelial cells infected with SARS-CoV-2 or treated with tunicamycin (ER stress inducer). Vasoactive intestinal peptides (VIP) expression and secretion by EN were assessed by RT-PCR and ELISA, respectively. Membrane expression of NHE3 was determined by surface biotinylation. Results: SARS-CoV-2 infection led to increased expression of BiP/GRP78, a marker and key regulator for ER stress in Caco-2 cells. Infected cells secreted the DAMP protein, heat shock protein 70 (HSP70), into the culture media, as revealed by proteomic and Western analyses. The expression of VIP mRNA in EN was up-regulated after treatment with a conditioned medium of SARS-CoV-2-infected Caco-2 cells. CD91, a receptor for HSP70, is abundantly expressed in the cultured mouse EN. Tunicamycin, an inducer of ER stress, also induced the release of HSP70 and Xbp1s, mimicking SARS-CoV-2 infection. Co-treatment of Caco-2 with tunicamycin (apical) and VIP (basolateral) induced a synergistic decrease in membrane expression of Na+/H+ exchanger (NHE3), an important transporter that mediates intestinal Na+/fluid absorption. Conclusions: Our findings demonstrate that SARS-CoV-2 enterocyte infection leads to ER stress and the release of DAMPs that up-regulates the expression and release of VIP by EN. VIP in turn inhibits fluid absorption through the downregulation of brush-border membrane expression of NHE3 in enterocytes. These data highlight the role of epithelial-enteric neuronal crosstalk in COVID-19-related diarrhea.

Published in Biomolecules

ISSN: 2218-273X (Online)
Publisher: MDPI AG
Country of publisher: Switzerland
LCC subjects: Science: Microbiology
Website: https://www.mdpi.com/journal/biomolecules

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