Effect of Bariatric Surgery on Non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) risk should be screened in patients with metabolic risk factors, the most important being obesity. The effects of laparoscopic sleeve gastrectomy (LSG) in patients with NAFLD are not well established. Liver biopsy is essential for the diagnosis of nonalcoholic steatohepatitis (NASH) and is the only procedure that differentiates NAFLD from NASH. Non invasive assessment is needed to identify the risk of NAFLD among patients with increased metabolic risk and patients with worse prognosis. SCCA-IgM is a known biomarker of progression to hepatocellular carcinoma from viral hepatitis but its role in diagnosis of fatty liver disease is under investigation. The aim of this prospective study was to evaluate if bariatric surgery can affect the biochemical features of NAFLD and to assess the prognostic value of squamous cell carcinoma antigen-IgM (SCCA-IgM) among non-invasive markers of liver injure.Fifty six (40 females and 16 males) treated with LSG were studied before (time 0) and twelve months after surgery. Anthropometric measurements, resting energy expenditure (REE) (by indirect calorimetry) and body composition data (fat-free mass or FFM, fat mass or FM, extrapolated by the means of bioelectrical impedance analysis), biochemical data (full blood count, glucometabolic profile, lipid profile, kidney and liver function tests, inflammatory markers) and clinical data (patient history, smoking and drinking habits, medication history, diet and lifestyle, anthopometric measures) were collected at baseline and one year later. An ultrasound scan was obtained for each patient at time 0 in order to ascertain the presence of hepatic steatosis, which was graded using a semiquantitative scale ranging from 0 (no steatosis) to 2 (severe steatosis). SCCA-IgM was measured by commercial ELISA kit (Xeptagen S.p.A., Venice, Italy). The data were analyzed by the software Statistical Package for the Social Sciences (SPSS v.20.0). Weight loss was 20,4±9,5%. We observed that the grading of steatosis was associated with glycemic profile (euglycemic vs prediadiabetic vs diabetic, squared-chi test p = 0,03) at baseline. ALT/AST ratio decreased after surgery (ALT/AST before LSG: median 1,06 IQR 0,92-1,39; ALT/AST after LSG: median 0,90 IQR 0,72-1,16 p <0,001) and its change was correlated with weight loss (r = 0,273; p= 0,046), BMI reduction (r = 0,388; p = 0,004) and decrease of HOMA index (r = 0,303; p = 0,037). No statistical difference was noted between the distributions of SCCA-IgM before and after surgery, nor there was any association between the decrease of SCCA-IgM titer and variations of body weight, HOMA index, platelets, ALT, AST, GGT, glucose titers. Only three patients had a value of SCCA-IgM above upper normal limit (cut-off value 200 AU/ml) and the decrease in their SCCA-IgM was not significant after a year. A correlation between SCCA-IgM titer and basal insulin levels was present titer before LSG (r = 0,335 p = 0,009) but not after bariatric surgery. Post LSG SCCA-IgM titer was found to be correlated to the titers of highsensitivity C-reactive protein (r = 0,288, p = 0,032) and IL6 (r = 0,355; p = 0,007), but no correlation was found between the variation of SCCA-IgM titer and the variations of the aforesaid inflammatory markers. Bariatric surgery resulted in a significant reduction of ALT, AST, GGT and ALT/AST ratio related to the degree of weight loss. NAFLD determined by the association of ultrasound scan and steatosis biomarkers confirm the tight link with insulin resistance. The role of SCCA-IgM in the development of fatty liver disease is still unclear. We can hypothesise the absence of a difference in SCCA IgM levels before and after LSG was related to the shortness of our follow-up, assuming that the healing processes in liver may require a longer period of time.