Effects of bariatric surgery on hepatic and intestinal lipoprotein particle metabolism in obese, nondiabetic humans

Abstract

Objective: The dyslipidemia of obesity and other insulin-resistant states is characterized by the elevation of plasma triglyceride-rich lipoproteins (TRL) of both hepatic (apoB-100-containing very low-density lipoprotein) and intestinal (apoB-48-containing chylomicrons) origin. Bariatric surgery is a well-established and effective modality for the treatment of obesity and is associated with improvements in several metabolic abnormalities associated with obesity, including a reduction in plasma triglycerides. Here, we have investigated the effect of bariatric surgery on TRL metabolism.

Approach and results: Twenty-two nondiabetic, obese subjects undergoing bariatric surgery: sleeve gastrectomy (n=12) or gastric bypass (n=10) were studied. Each subject underwent 1 lipoprotein turnover study 1 month before surgery followed by a second study, 6 months after surgery, using established stable isotope enrichment methodology, in constant fed state. TRL-apoB-100 concentration was significantly reduced after sleeve gastrectomy, explained by a decrease (P<0.05) in TRL-apoB-100 production rate and an increase (P<0.05) in TRL-apoB-100 fractional catabolic rate. TRL-apoB-48 concentration was also significantly reduced after sleeve gastrectomy, explained by reduction in TRL-apoB-48 production rate (P<0.05). For gastric bypass, although TRL-apoB-100 concentration declined after surgery (P<0.01), without a significant decline in TRL-apoB-48, there was no significant change in either TRL-apoB-100 or TRL-apoB-48 production rate or fractional catabolic rate. The reduction in TRL-apoB-100 concentration was significantly associated with a reduction in plasma apoC-III in the pooled group of patients undergoing bariatric surgery.

Conclusions: This is the first human lipoprotein kinetic study to explore the mechanism of improvement of TRL metabolism after bariatric surgery. These effects may contribute to the decrease of cardiovascular mortality after surgery.

Clinical trial registration url: http://www.ClinicalTrials.gov. Unique identifier: NCT01277068.

Keywords: atherosclerosis; chylomicrons; general surgery; lipoproteins; obesity; triglycerides.