Altered amino acids concentrations in polycystic ovary syndrome women with non-alcoholic fatty liver disease

Abstract

Prevalence of Non-alcoholic fatty liver disease (NAFLD) increased in females with polycystic ovary syndrome (PCOS). Dysfunction of amino acids metabolism has been found in NAFLD. We aim to explore the association between plasma concentrations of amino acids and NAFLD in PCOS women. Cross-sectional study Diagnosis of PCOS was based on the Rotterdam criteria. A subgroup of 157 PCOS women from a metabolomics study was included. Plasma samples from subjects were tested using the gas chromatography/time-of-flight mass spectrometry (GC/TOF-MS). NAFLD status was evaluated by a fatty liver index (FLI). FLI was calculated using body mass index (BMI), waist circumference, triglycerides, and gamma-glutamyl transferase, using a cut-off <30 for excluding, 30≤FIL<60 for suspecting, and ≥60 for confirming hepatic steatosis. Accordingly, subjects were divided into three groups based FLI values. Endocrine hormones, metabolic parameters, anthropometric measurements, and oral glucose tolerance tests were performed. Our results showed that altered metabolism of glucose, lipid, amino acids and androgen in PCOS with hepatic steatosis. Levels of alanine and branched-chain amino acid (BCAA) increased in subjects with FLI≥60, while threonine decreased. Correlation analysis showed that alanine and BCAA were positively associated with FLI, and glycine and serine were negatively correlated with FLI. After adjusting age, BMI, free androgen index (FAI) and homeostasis model assessment of insulin resistance (HOMA-IR), we found alanine and BCAA were positively associated with FLI. In addition, valine and isoleucine were positively associated with C-reation protein. Altered plasma amino acids levels were found in PCOS with NAFLD. BCAA was strongly associated with NAFLD in PCOS independent of age, BMI, FAI and IR. Chronic inflammation may be an underlying mechanism for BCAA inducing NAFLD in PCOS.