Effects of weight loss induced by bariatric surgery on hepatic adipocytokine expression

BACKGROUND/AIMS: Adipocytokines play a key role in the pathophysiology of non-alcoholic fatty liver diseases (NAFLD). Whereas adiponectin has mainly anti-inflammatory functions, leptin, resistin and pre-B cell enhancing factor (PBEF)/Nampt/visfatin are considered as mainly pro-inflammatory mediators regulating metabolic and immune processes. METHODS: We prospectively examined the effect of weight loss on systemic levels and/or hepatic expression of adiponectin/adiponectin receptors, leptin/leptin receptors, resistin and PBEF/Nampt/visfatin. Severely obese patients underwent laparoscopic adjustable gastric banding (LABG) and serum samples (n=30) were collected before, and after 6 and 12 months. Paired liver biopsies (before and 6 months after LABG) were obtained from 18 patients. RESULTS: Bariatric surgery improved insulin resistance, abnormal liver function tests and liver histology. Pronounced weight loss after 6 and 12 months was accompanied by a significant increase in serum adiponectin levels whereas both leptin and PBEF/Nampt/visfatin levels decreased. Resistin serum levels increased after 6 months but fell below baseline values after 12 months. Liver mRNA expression of adiponectin increased slightly after 6 months whereas leptin mRNA expression did not change. Interestingly, weight loss resulted in a significant decrease of hepatic mRNA expression of resistin, PBEF/Nampt/visfatin and both leptin receptor isoforms while expression of type 1 and 2 adiponectin receptor was not affected. Liver immunohistochemistry performed on index and follow-up liver biopsies revealed an increase in adiponectin staining, showed no effect on resistin/leptin positivity, and demonstrated a decrease in PBEF/Nampt/visfatin immunoreactivity. CONCLUSIONS: Weight loss after LABG surgery drives the adipocytokine milieu towards a more anti-inflammatory direction both systemically and in the liver.