China Is Catching and Passing U.S. with NAFLD Plus Updates

F Zhou et al. Hepatology 2019; 70: 1119-33. The authors performed a systematic review (n=392 studies, more than 2 million subjects) and found that NAFLD in China increased from 25.4% in 2008-2010 to 32.3% in 2015-2018. The pooled prevalence across all studies was 29.2%. The associated editorial speculates that some of this increase is related to diet changes as well as PNPLA3 gene.  This allele “is more common among East Asians than Caucasians”  It is lower in African Americans in the U.S. which helps explain why this population is at reduced risk.

JB Schwimmer, JS Johnson et al Gastroenterol 2019; 157: 1109-22.  In this prospective study with 87 children (89% Hispanic), the authors associated fecal microbiomes with NAFLD and NASH.  Both NAFLD and NASH were associated with intestinal dysbiosis with lower diversity and high abundance of Prevotella copri. Full text link: Microbiome Signatures Associated With Steatohepatitis and Moderate to Severe Fibrosis in Children With Nonalcoholic Fatty Liver Disease

S Pelusi et al. Clin Gastroenterol Hepatol 2019; 17: 2310-9.  This study analyzed data from 1738 subjects (45% with severe obesity) who had undergone liver biopsy.  132 of 389 (33.9%) with significant fibrosis did NOT have nonalcoholic steatohepatitis (NASH) and 39 patients (10%) had no inflammation. NASH diagnosis required steatosis (≥5% of hepatocytes), hepatocellular ballooning, and lobular inflammation. Factors associated with significant fibrosis in the absence of NASH, included fasting hyperglycemia, severe steatosis, mild inflammation or ballooning, and PNPLA3 1148M variant.  My take: this study shows that the finding of NASH on liver biopsy is NOT required for the development of severe liver disease related to NAFLD.

D Linden et al. Molecular Metabolism 2019; 22: 49-61. This study, summarized in Gastroenterol 2019; 157: 1156-9) showed that PNPLA3 silencing with antisense oligonucleotides ameliorates NASH in PNPLA3 1148M knock-in mice.  The summary notes that the mutated 1148 M PNPLA3 protein variant accumulates on lipid droplets altering clearance and affecting triglycerides and phospholipid turnover.