Gastrointestinal Dysmotility, Autonomic Function and Small Intestinal Bacterial Overgrowth among People with Well-Controlled HIV

Introduction Gastrointestinal dysfunction, including microbiome changes and increased bacterial translocation across a compromised gastrointestinal barrier plays a role in the chronic systemic inflammation experienced by people with HIV (PWH). It is unknown whether autonomic neuropathy (AN) may contribute to these mechanisms by altering gastrointestinal motility. Methods This is a cross-sectional study of 100 PWH and 89 controls. All participants underwent assessment of gastrointestinal transit times using a wireless motility capsule (WMC). All PWH and a subset of controls also underwent: a standardized battery of autonomic function tests summarized as the Modified Composite Autonomic Severity Score (MCASS) and its adrenergic, cardiovagal and sudomotor sub-scores, breath testing for small intestinal bacterial overgrowth (SIBO), and the Patient Assessment of Upper Gastrointestinal Disorders Symptoms (PAGI-SYM) and Composite Autonomic Symptom Score 31 (COMPASS-31) questionnaires. Results Compared to controls, PWH displayed shorter gastric emptying times (GET) and longer small bowel and colonic transit times (SBTT, CTT). Among PWH, GET was associated with PAGI-SYM score. The MCASS and its sudomotor sub-score (reflecting peripheral sympathetic function) were associated with SBTT but not GET or CTT. PWH with prolonged SBTT (>6h) were more likely to have SIBO. Conclusion Gastrointestinal motility is altered in PWH. This study provides preliminary evidence that changes in autonomic function may influence SBTT in PWH and that prolonged SBTT may contribute to the development of SIBO. Future studies are needed to more fully elucidate the pathophysiologic links between HIV-associated AN, altered gastrointestinal motility, the gastrointestinal microbiome, chronic inflammation, and resulting morbidity and mortality among PWH.