Dysbiosis and leaky gut in hyper-inflated COPD patients: Have smoking and exercise training any role?

To characterize the leaky gut syndrome in a cohort of COPD patients with lung hyperinflation according to their clinical history (i.e. hyperinflation severity, chronic respiratory failure [CRF] presence, GOLD stage, prescribed therapy, smoking history) and with or without recent exercise training activity.

At the ambulatory visit, we evaluated selected COPD patients with lung hyperinflation [residual volume (RV)≥110% pred, TLC≤120% pred)] in clinical stability, identifying them as those who have attended a recent program of exercise training and those who were waiting for it. Clinical and respiratory characteristics (forced expiratory volume at the first second, forced vital capacity, and arterial blood gasses) were collected. Microbiota composition (CFU/ml), and intestinal permeability (i.e., Zonulin ng/ml) were measured in the stool and normalized to the normality cutoff value.

All patients [n = 32, median age: 67 years, median RV: 185.0% pred (IQR: 162.0-206.0) and TLC 125.0% pred (IQR: 113.0-138.0)] showed depletion of Lactobacilli, Bacteroides and a great increase in E. Coli, KES (2 and 6.4 times) and Saccharomyces concentrations (2.5 times) other than normality. All evaluations on gut microbiota composition in the whole population were independent of BMI, CRF, GOLD stage or hyperinflation severity, and inhaled steroid therapy. Smoking habits (smokers vs ex-smokers) influenced only Bacteroides species (p<0.05) and no systemic inflammation was present in these patients. On the contrary, Zonulin concentration, a marker of intestinal permeability, was significantly higher than normal (2.8 times) and was correlated with Saccharomyces (p = 0.013). Zonulin (p = 0.001) and Saccharomyces (p<0.0001) were also significantly different in patients undergoing exercise training with respect to those on the waiting list for training. These findings were not influenced by smoking habits.

A marked dysbiosis and leaky gut alteration characterize all COPD hyper-inflated patients, being worse in patients waiting for exercise training. A pre-to-post study is necessary to confirm these preliminary findings.