Impact of 12-week exercise program on biomarkers of gut barrier integrity in patients with coronary artery disease

INTRODUCTION: Breakdown of gut barrier integrity has been associated with inflammatory activation and is implicated in the etiology of several chronic medical conditions. Acute exercise is known to increase gut barrier permeability but the impact of chronic exercise is not clear. Most studies to date have examined how acute exercise impacts gut barrier integrity in healthy adults, while few studies have examined the impact of chronic exercise in older adults with comorbidities. We aim to investigate the impact of a 12-week program of aerobic and resistance training on biomarkers of gut barrier integrity in a sample of older adults with coronary artery disease. METHODS: Participants were adults with coronary artery disease undergoing a moderate-intensity 12-week cardiac rehabilitation exercise program. Fasting blood samples were taken at baseline and study termination. Serum levels of biomarkers of gut barrier integrity (zonulin and fatty acid-binding protein 2 (FABP2)) were measured by ELISA. Cardiorespiratory fitness was assessed by peak oxygen uptake (VO(2peak)) at study start & completion. Data analyses were performed using SPSS software version 24.0. RESULTS: Among study participants (n = 41, 70% male, age = 62.7± 9.35) we found a significant negative association between baseline FABP2 levels and baseline VO(2peak) in a multiple linear regression model adjusting for covariates (B = -0.3, p = 0.009). Over the course of the exercise program an increase in VO(2peak) (≥ 5 mL/kg/min) was independently associated with a relative decrease in FABP2 (B = -0.45, p = 0.018) after controlling for medical covariates. CONCLUSION: Our findings indicate that an increase in cardiorespiratory fitness during a 12-week exercise program resulted in a relative improvement in a biomarker of gut barrier integrity. This indicates a potential mechanism by which longer term exercise may improve gut barrier integrity.