Relevance of enriched expression of SARS-CoV-2 binding receptor ACE2 in gastrointestinal tissue with pathogenesis of digestive symptoms, diabetes-associated mortality, and disease recurrence in COVID-19 patients

Ashutosh Kumar; Muneeb A. Faiq; Vikas Pareek; Khursheed Raza; Ravi K. Narayan; Pranav Prasoon; Pavan Kumar; Maheswari Kulandhasamy; Chiman Kumari; Kamla Kant; Himanshu N. Singh; Rizwana Qadri; Sada N. Pandey; Santosh Kumar

The world is currently reeling in an alarming outbreak of novel coronavirus disease 2019 referred to as COVID-19. COVID-19 is caused by a new coronavirus strain severe acute respiratory syndrome coronavirus 2 (SARS CoV-2)-a positive sense single strand RNA virus. Recent studies which decoded structure of the virus showed binding of its Sspike protein to a human protein-angiotensin converting enzyme 2 (ACE2). [1] [2] [3] Clinical presentation in COVID-19 patients is highly diverse and majority of them primarily presents with pulmonary symptoms (cough, fever, shortness of breath). 4 In addition, some of the patients present with digestive symptoms like diarrhea, nausea, vomiting and abdominal pain (3.8%). 4 Digestive symptoms have been the only presentations in some of the patients. 5, 6 Digestive symptoms are not unique to the COVID-19 and usually present in the gastroenteritis caused by many other respiratory syndrome viruses like SARS-CoV-1 and influenza A and B. 7,8 However, how SARS-CoV-2 makes entry into the gastrointestinal (GI) tissue leading to gastroenteritis-like features, does not imbibe sufficient and coherent explanation in the light of the existing literature. Some investigators have speculated a fecal-oral route of transmission but any conclusive evidence is lacking in this regard. 6 Knowing the expression pattern of ACE2 in gastrointestinal tract (GIT) may explicate the pathogenesis of digestive symptoms in COVID-19. Digestive juices and enzymes secreted from the liver, gallbladder (GB) and pancreas play an important role in maintenance of the secretions and absorption of nutrients across intestinal epithelium. Hence their possible dysfunction in COVID-19 patients needs to be examined in order to understand pathogenesis of the digestive symptoms which, in turn, prevent some COVID-19 associated mortality.