Serum Trimethylamine-N-oxide Concentrations in People Living with HIV and the Effect of Probiotic Supplementation

Background The incidence of cardiovascular disorders in people living with HIV (PLWH) is higher than that in non-infected individuals. Traditional and specific risk factors have been described but the role of the gut microbiota-dependent choline metabolite, trimethylamine-N-oxide (TMAO) is still unclear. Methods A cross-sectional analysis and a longitudinal analysis (with high-dose probiotic supplementation) were performed to measure serum TMAO concentrations through UHPLC-MS/MS. Stable outpatients living with HIV on highly active antiretroviral treatment with no major cardiovascular disease were enrolled. Non-parametric tests (bivariate and paired tests) and a multivariate linear regression analysis were used. Results A total of 175 participants were enrolled in the study. Median serum TMAO concentrations were 165 (103-273) ng/mL. An association with age, serum creatinine, number of antiretrovirals, multimorbidity and polypharmacy was observed; at linear logistic regression analysis, multimorbidity was the only independent predictor of TMAO concentrations. Carotid intima media thickness (IMT) was 0.85 (0.71-1.21) mm, with a trend towards higher TMAO concentrations observed in patients with IMT >0.9 mm (P=0.087). In the 25 participants who received probiotic supplementation, TMAO levels did not significantly change after 24 weeks (Wilcoxon paired P=0.220). Conclusion Serum TMAO levels in PLWH were associated with multimorbidity, higher cardiovascular risk and subclinical atherosclerosis and were not affected by 6 months of high-dose probiotic supplementation.