ACE2 dysregulation COVID-19 Medicine SARS-CoV-2 SARS-CoV-2 infection abdominal pain acute mesenteric ischemia anxiety clinical course clinical manifestations cytokines delivery of healthcare depression dyspnea endoscopy endothelitis enteric infection gastroenterology gastrointestinal disorders gastrointestinal manifestations gut dysbiosis gut microbiota hepatology hospitalized patients hypercoagulability inflammatory bowel disease intestinal inflammation liver liver disease medication adherence