FIGURE 4.

Interactions between gut dysbiosis and organs in coronavirus disease 2019. Gut dysbiosis affects multiple organs to form bidirectional gut–organs axes. Bile acids produced in the liver are secreted into gut, which are metabolized by gut bacteria and reabsorbed into the liver to form enterohepatic circulation. Other bacterial metabolites such as butyrate can also be absorbed into the liver. In gut dysbiosis, lipopolysaccharides and microbes are able to cross gut barrier to enter the liver. After processing in the liver, they enter to circulation system. In case of liver disease, there are also activated immune cells and cytokines. All these can be secret into the intestines and other organs. Chronic diseases in cardiovascular system, lung, brain and other organs could also produce and secrete immune cells and cytokine into circulation system