Roux-en-Y gastric bypass (RYGB) surgery is one of the most effective treatment options for severe obesity and related comorbidities, including hyperlipidemia, a well-established risk factor of cardiovascular diseases. Elucidating the molecular mechanisms underlying the beneficial effects of RYGB may facilitate development of equally effective, but less invasive, treatments. Recent studies have revealed that RYGB increases low-density lipoprotein receptor (LDLR) expression in the intestine of rodents. Therefore, in this study we first examined the effects of RYGB on intestinal cholesterol metabolism in human patients, and we show that they also exhibit profound changes and increased LDLR expression. We then hypothesized that the upregulation of intestinal LDLR may be sufficient to decrease circulating cholesterol levels. To this end, we generated and studied mice that overexpress human LDLR specifically in the intestine. This perturbation significantly affected intestinal metabolism, augmented fecal cholesterol excretion, and induced a reciprocal suppression of the machinery related to luminal cholesterol absorption and bile acid synthesis. Circulating cholesterol levels were significantly decreased and, remarkably, several other metabolic effects were similar to those observed in RYGB-treated rodents and patients, including improved glucose metabolism. These data highlight the importance of intestinal cholesterol metabolism for the beneficial metabolic effects of RYGB and for the treatment of hyperlipidemia.
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Financial Support: This work was supported by National Institute of Diabetes and Digestive and Kidney Diseases Grant R01-DK108642 (to N.S.), as well as funding from the Edward Mallinckrodt Jr. Foundation (to N.S.), the Diabetes Action Research and Education Foundation (to N.S.), a Rothschild fellowship (to D.B.-Z.), a Human Frontiers in Science postdoctoral fellowship (to D.B.-Z.), and National Fund for Scientific and Technological Development of the Government of Chile (FONDECYT) Grant 11160688 (to R.M.).
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