Expression data from liver of obese patients

Non-alcoholic fatty liver disease (NAFLD) encompasses a spectrum of histological findings, from simple steatosis to steatohepatitis (NASH), the latter presenting a higher risk of cardiovascular and kidney diseases, type 2 diabetes and end-stage liver disease. NAFLD is seen as the hepatic manifestation of the metabolic syndrome and affects up to 70-80% of obese patients. There are currently no approved pharmacological therapies for NASH, thus the only option is lifestyle intervention or bariatric surgery in order to lose weight and to improve insulin resistance. Although surgical intervention has allowed collections of liver biopsies, transcriptomic data from livers are still scarce and especially follow-up data to evaluate the impact of weight loss intervention on the liver. Therefore we studied hepatic transcriptomic data in a large cohort of obese patients assessed for presence of NASH at baseline and 1 year follow-up. Patients visiting the obesity clinic of the Antwerp University Hospital for a problem of being overweight (BMI above 25 to 29.9 kg/m²) or obese (BMI above 30 kg/m²) were prospectively recruited and underwent a hepatic work-up. Patients were excluded from further analysis in case of significant alcohol consumption (>20 g/day), history of bariatric surgery, diagnosis of another liver disease, pre-existing diabetes. Patients who were, however, diagnosed with de novo diabetes at baseline or at follow-up were not excluded. If NAFLD was suspected, liver biopsy was proposed. For patients undergoing bariatric surgery (BS), a liver biopsy was proposed regardless of the criteria. Patients were reassessed after 1 year. Liver biopsy was performed percutaneously (16G Menghini) or peri-operatively (14G Tru-Cut). The different histological features of NAFLD were assessed using the NASH Clinical Research Network (NASH CRN) Scoring System. The presence of NASH was defined according to Chalasani et al. necessitating the combined presence of steatosis, ballooning and lobular inflammation. Microarray data were obtained for 152 patients at baseline (44 no NASH, 104 NASH, 4 undefined) and 79 patients (54 no NASH, 22 NASH, 3 undefined) at 1 year follow-up (38 diet restriction [Diet], 41 bariatric surgery [BS]). When paired (baseline - follow-up) samples were available, the number in brackets in Sample name indicates the baseline number of the same patient.