Alimentary System is Directly Attacked by SARS-COV-2 and Further Prevents Immune Dysregulation Caused by COVID-19.

BACKGROUND: SARS-COV-2 causes digestive system symptom, the effect of which remains equivocal. METHODS: Patients with COVID-19 were classified into 4 groups according to symptom. The study traced the onset and duration of symptoms, compared laboratory examinations and conducted bioinformatic analysis. Immune indices were further analyzed. RESULTS: By March 16, 25 patients with COVID-19 and 13 with suspect COVID-19 were admitted to West China Hospital, Sichuan University. Digestive system symptom group had the highest level of ESR (mm/h, Pi¼œ0.0001), serum ferritin (ng/ml, Pi¼œ0.0001), hepatic enzymes (Pi¼œ0.05), and retentive lymphocyte count/percentage (Pi¼œ0.05) and its subsets (Pi¼œ0.05). Combined group (respiratory combined with subsequent digestive system symptom) had the highest level of IL-6 (pg/ml, P=0.0046), CRP (mg/L, P=0.0004) and moderate lymphocyte depletion. Respiratory system symptom and asymptomatic groups suffered the most from lymphocyte depletion (Pi¼œ0.05). Bioinformatic analysis indicated co-expression of binding related proteins of SARS-COV-2 (ACE2, TMPRSS2 and Furin) in small intestine. CD147 was extensively expressed in alimentary tract. CTSL, PIKfyve, TPC2 and CTSB could be detected with ≥moderate expressions in a variety of organs including alimentary system. CONCLUSIONS: Alimentary system is possibly attacked by SARS-COV-2 other than hyperinflammation or immune dysregulation caused by it. Involvement of alimentary system might further protect mild and moderate cases from lymphocyte depletion caused by COVID-19.