Bariatric surgery, known for its often striking metabolic effects including mitigation of nonalcoholic fatty liver disease (NAFLD), alters the expression of genes in the liver, researchers found.

In a small study that looked at liver biopsies from NAFLD patients before and after bariatric surgery, methylation changes associated with the disease phenotype were partially reversible, Jochen Hampe, PhD, of University Hospital Dresden in Germany, and colleagues reported online in Cell Metabolism.

"Our findings provide an example of treatment-induced epigenetic organ remodeling in humans," they wrote.

Earlier work has shown that in addition to shedding pounds, bariatric surgery has metabolic benefits, such as remission of type 2 diabetes and reversal of symptoms of fatty liver disease.

Yet the mechanisms by which these improvement happen are unclear.

To look specifically at liver changes associated with weight loss surgery, Hampe and colleagues assessed liver biopsies from both normal and obese patients with and without NAFLD. They included 27 obese patients with different stages of NAFLD, 18 healthy obese patients without liver disease, and 18 normal-weight patients without liver disease.

Samples were assessed via array-based DNA methylation and mRNA expression profiling.

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