Coronavirus disease-19 and the gut-lung axis

Zhou, Dan; Wang, Qiu; Liu, Hanmin

Gastrointestinal and respiratory tract diseases often occur together. There are many overlapping pathologies, leading to the concept of the “gut-lung axis,” in which stimulation on one side triggers a response on the other side. This axis appears to be implicated in infections involving severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which has triggered the global pandemic of coronavirus disease 2019 (COVID-19), in which respiratory symptoms of fever, cough, and dyspnea often occur together with gastrointestinal symptoms such as nausea, vomiting, abdominal pain, and diarrhea. Besides the gut-lung axis, it should be noted that the gut participates in numerous axes, which may affect lung function and consequently COVID-19 severity through several pathways. However, in this article, we mainly pay attention to the latest evidence and the mechanisms that drive the operation of the gut-lung axis, as well as discuss the interaction between the gut-lung axis and its possible involvement in COVID-19 from the perspective of microbiota, microbiota metabolites, microbial dysbiosis, common mucosal immunity and angiotensin-converting enzyme II (ACE2). Raising hypotheses and providing methods to guide future research on this new disease and its treatments.