The gut microbiome is a risk factor for respiratory diseases

Published: December 29, 2022

Asthma and chronic obstructive pulmonary disease (COPD) represent the vast majority of chronic respiratory diseases (CRD) worldwide, both having significant impact on the patients’ health and quality of life. Currently, the diagnosis of CODP and asthma remains a challenge, resulting in substantial under-diagnosis where patients have not been recognized as having the condition. While lung function assessment via a spirometer is the main test for confirming diagnoses of COPD and asthma, people with mild CODP and asthma can still have normal spirometry. Identification of risk factors for CRD in the general population is crucial for developing strategies for disease prevention and early intervention. In recent years, increasing evidence has suggested that the human microbiome, particularly the airway microbiome, is linked to respiratory functions and diseases, but little is known about the relationship between the gut microbiome and adult-onset CRD.

In a recent issue of The Journal of Allergy and Clinical Immunology (JACI), Liu et al. reported a new study investigating whether and to what extent the gut microbiome, the microorganisms residing in the intestine, affects prospective risk of developing COPD and asthma in adults. Stool samples were collected from more than 7000 participants of a population-based cohort study in Finland in 2002. The gut microbiomes of the participants were profiled by analysing the stool samples with shotgun metagenomic sequencing. The participants were followed up for disease occurrence through electronic health record systems until the end of 2016. The researchers evaluated the relationship between the gut microbiomes of the participants at the time of inclusion in the study and later occurrence of asthma and COPD during a follow-up period of up to 15 years. They also developed machine learning models to investigate the predictive ability of the gut microbiome for asthma and COPD.

The study demonstrated that the gut microbiome is associated with incident asthma and COPD in the general population. Interestingly, some bacteria that were previously linked to impaired lung function in the airway microbiome, Streptococcus as an instance, were also found to be associated with higher risk of asthma and COPD in the gut microbiome. They showed that the gut microbiome had moderate predictive capacities in distinguishing people who developed incident respiratory diseases from those who did not. In addition, they showed that the gut microbiome-based prediction of asthma and COPD was largely independent of age, sex, BMI and smoking, all of which can influence susceptibility to respiratory diseases. Importantly, the study affirmed the large body of evidence that cigarette smoking is a strong risk factor for respiratory illness, especially COPD, while the predictive power of the gut microbiome for future respiratory disease is partially explained by smoking behavior.

While the airway microbiome is known as a contributing factor for the development of respiratory diseases, whether the gut microbiome contributes to respiratory diseases remains unclear. The findings of this study support the role of the gut microbiome in adult respiratory disease and as a potential risk factor that might aid in risk profiling of asthma and COPD. Future exploration of the influence of the gut microbiome in severity and progression of respiratory diseases is warranted, and may lead to further clinically-significant findings.

The Journal of Allergy and Clinical Immunology (JACI) is an official scientific journal of the AAAAI, and is the most-cited journal in the field of allergy and clinical immunology.

Full Article