Emerging pathogenic links between microbiota and the gut–lung axis

The microbiota is central for host homeostasis and affects not only the gut but also other organs, including the lungs. In this Opinion article, Hansbro and colleagues explore the role of the microbiota in the gut–lung axis and lung disease. The microbiota is vital for the development of the immune system and homeostasis. Changes in microbial composition and function, termed dysbiosis, in the respiratory tract and the gut have recently been linked to alterations in immune responses and to disease development in the lungs. In this Opinion article, we review the microbial species that are usually found in healthy gastrointestinal and respiratory tracts, their dysbiosis in disease and interactions with the gut–lung axis. Although the gut–lung axis is only beginning to be understood, emerging evidence indicates that there is potential for manipulation of the gut microbiota in the treatment of lung diseases.