Gastrointestinal mucosal immunity and COVID-19

Abstract

As the gastrointestinal tract may also be a crucial entry or interaction site of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the role of the gut mucosal immune system as a first-line physical and immunological defense is critical. Furthermore, gastrointestinal involvement and symptoms in coronavirus disease 2019 (COVID-19) patients have been linked to worse clinical outcomes. This review discusses recent data on the interactions between the virus and the immune cells and molecules in the mucosa during the infection. By carrying out appropriate investigations, the mucosal immune system role in SARS-CoV-2 infection in therapy and prevention can be established. In line with this, COVID-19 vaccines that stimulate mucosal immunity against the virus may have more advantages than the others.

Keywords: Mucosa; Gut mucosa; Mucosa-associated lymphoid tissue; SARS-CoV-2; COVID-19; Secretory immunoglobulin A; Gut microbiota

Core Tip: The gastrointestinal tract is a frequent route of infection with severe acute respiratory syndrome coronavirus 2. Given the complex interactions between the virus and the mucosal immune system after exposure, additional research is needed to elucidate the immune mechanisms and processes in the gut mucosa. The hallmark of all immune responses is the recruitment of various immune cells, such as neutrophils, dendritic cells, macrophages, and T cells in the gut mucosa. However, the mucosal inflammatory response could change intercellular space between enterocytes, leading to an increase in intestinal permeability that allows various bacterial antigens and toxins to enter the bloodstream, further complicating the disease state of coronavirus disease 2019 patients.