Emerging pathogenic links between microbiota and the gut–lung axis

The gastrointestinal tract (GIT) and respiratory tract, although separate organs, are part of a shared mucosal immune system termed the gut–lung axis.The microbiota of the GIT and the respiratory tract are involved in the gut–lung axis, influencing immune responses both locally and at distant sites.Current research has identified specific bacterial taxa, their components and metabolites that can influence host immunity.With greater knowledge of the gut–lung axis and microbial influences of immunity, advances have been made in understanding the role of the microbiota in respiratory diseases, such as asthma, chronic obstructive pulmonary disease (COPD) and respiratory infection.This newfound understanding has created several possible therapeutic strategies for the treatment or prevention of acute and chronic respiratory diseases. However, several technical challenges and unanswered questions remain.