Intestinal Dysbiosis and Probiotics in COVID-19

The COVID-19 pandemic has been an emerging threat to global public health. Several lines of evidence suggest that the causative virus SARS-CoV-2 infects the human intestinal epithelial cells as well as airway epithelial cells, suggesting that the enteric infection of SARS-CoV-2 has destructive effects on the intestinal microbiota and subsequently airway physiology and immunity through the gut-lung axis. Despite the important roles of the gut-lung axis in the antiviral immunity, only limited information is currently available concerning COVID-19-specific changes in the gut microbiome. This review summarizes recent knowledge of intestinal dysbiosis associated with COVID-19 patients and its potential contribution to the respiratory symptoms through the gut-lung axis. We also discuss the possibility of prophylactic and therapeutic use of probiotics in COVID-19, including our ongoing trial using Lactobacillus plantarum, which is known to have a wide variety of immunomodulatory activity against respiratory viral infections.