The Gut-Lung Axis

There is a communication between the microbiotas of the gut and lungs
All the microorganisms that are naturally found in and on the human body are called the microbiota. These include mostly  bacteria, viruses and fungi. The microbiota has been shown to have a vital role in health, including immunity

Airway and lung microbiota

There is a diverse population of microbes found throughout the upper respiratory tract and lower respiratory tract. These have been shown to interact with immune functions.

References

Gut-lung axis 

Recent evidence describes the cross-talk between the microbiotas of the gut and lungs. Changes in lung microbial community influence the composition of gut microbiota and viceversa, influencing respiratory health.

Disruptions in gut and lung microbiota have been linked to respiratory diseases including viral respiratory tract infections, asthma, chronic obstructive pulmonary disease (COPD) and lung cancer.

Gut microbiota

Gut microbiota regulates the immune system and protects against harmful pathogens. As we grow, microbiota and immune system shape the development of each other.

References
AB21® probiotic modulates the gut-lung axis
Some probiotics have been clinically tested to influence gut or lung microbiota, with effects on respiratory health