Non-invasive diagnosis of non-alcoholic fatty liver disease.

Abstract

Non-alcoholic fatty liver disease (NAFLD) has become one of the top concerns for the practising hepato-gastroenterologist due to the obesity epidemic and its potential to progress to an advanced liver disease that significantly impacts on overall and liver-related mortality. Due to the rapidly advancing epidemics of obesity and diabetes, a large segment of the population is at risk for NAFLD. Particularly worrisome is the emergence of NAFLD or non-alcoholic steatohepatitis (NASH) with a significant fibrotic disease in developing countries, even in patients of normal or underweight. A critical issue in patients with NAFLD is the differentiation of NASH from simple steatosis (SS). It is then of particular importance to identify NASH patients as they are at greatest risk of developing cardiovascular diseases and complications such as cirrhosis, liver failure or hepatocellular carcinoma. There is a need, in NAFLD management, to develop non-invasive methods to detect NASH and to predict advanced fibrosis stages. Therefore, we evaluated the following items: (i) A tool-based on optical analysis of liver magnetic resonance images as biomarkers for NASH and fibrosis detection by investigating patients with biopsy-proven NAFLD who underwent magnetic resonance protocols using 1.5T General Electric or Philips devices. Two imaging biomarkers (NASHMRI and FibroMRI) were developed, standardized and validated using the area under the receiver operating characteristic curve (AUROC) analysis. The results indicated NASHMRI diagnostic accuracy for steatohepatitis detection was 0.83 (95%CI: 0.73-0.93), and FibroMRI diagnostic accuracy for significant fibrosis determination was 0.85 (95%CI: 0.77-0.94). These findings were independent of the magnetic resonance system used. We conclude that the optical analysis of magnetic resonance images has high potential to define non-invasive imaging biomarkers for the detection of steatohepatitis (NASHMRI) and the prediction of significant fibrosis (FibroMRI). (ii) Genetic and epigenetic biomarkers, such as human patatin-like phospholipase domain containing 3 (PNPLA3), transmembrane 6 superfamily 2 (TM6SF2) and fibroblast growth factor 21 (FGF21) variants as well as a panel of most abundant liver microRNAs. After univariate and multivariate analysis, we confirmed that GG genotype of PNPLA3 exerted a clear role in NASH development, and we identified the impact of a novel risk variant located in FGF21 gene in significant fibrosis stages. Besides, we found overexpression of FGF21 levels in both liver and serum, directly related to NASH condition. Finally, two microRNAs (miR-200b-3p and miR-224-5p) were screened and validated in human liver tissue and plasma of biopsy proven NAFLD patients, and were found raised in NASH, conferring them potential as non-invasive biomarkers.