Effect of bariatric surgery on HDL-mediated cholesterol efflux capacity

Background: Bariatric surgery (BS) is the most effective intervention for severe obesity, leading to sustained weight loss, reduced obesity-related comorbidities, and cardiovascular mortality. Aim: To assess changes in high-density lipoprotein (HDL) functions [cholesterol efflux capacity (CEC) and anti-inflammatory capacity] at different follow-up times in patients with severe obesity undergoing BS. Methods: A prospective observational study within a cohort of consecutively enrolled patients with severe obesity scheduled to undergo BS. In total, 62 participants (77% women), with a mean age of 42.1 years (SD 9.33 years) underwent BS. Regarding the surgical procedure, 27 (43.5%) underwent sleeve gastrectomy and 35 (56.5%) Roux-en-Y gastric bypass. All patients were evaluated preoperatively and at 1, 3, 6, and 12 months after surgery. Results: A decrease in body mass index and an improvement in the systemic lipid profile, indicated by reductions in total cholesterol, low-density lipoprotein cholesterol (LDLc), and remnant cholesterol, and an increase in HDL cholesterol (HDLc) was observed (all p trend < 0.001). Time-series comparisons vs. baseline showed that, in general, anthropometric measures, glycemia, total cholesterol, LDLc, and remnant cholesterol decreased at all follow-ups, whereas HDLc and triglyceride concentrations significantly improved vs. baseline from 6 months, reaching at 12 months the highest HDLc levels (29.6%, p < 0.001) and the lowest circulating triglycerides (−30%, p < 0.001). Although HDL's anti-inflammatory ability worsens after surgery, the HDL-mediated CEC linearly increased after surgery (for both p trend < 0.013). Conclusion: BS improves the lipid profile both quantitatively and qualitatively after 1 year, specifically enhancing HDL-mediated cholesterol efflux capacity, which may contribute to a reduced cardiovascular risk in individuals with severe obesity.