PNPLA3 rs139051 is associated with phospholipid metabolite profile and hepatic inflammation in nonalcoholic fatty liver disease

AIM To investigate the effect of PNPLA3 polymorphisms on serum lipidomics and pathological characteristics in nonalcoholic fatty liver disease(NAFLD).METHODS Thirty-four biopsy-proven NAFLD patients from Northern, Central, and Southern China were subjected to stratification by genotyping their single nucleotide polymorphisms(SNPs) in PNPLA3. Ultra performance liquid chromatography-tandem mass spectrometry was then employed to characterize the effects of PNPLA3 SNPs on serum lipidomics. In succession, correlation analysis revealed the association of PNPLA3-related lipid profile and hepatic pathological characteristics on a basis of steatosis, activity, and fibrosis assessment. The variant-based scoring of hepatocyte steatosis, ballooning, lobular inflammation, and liver fibrosis was finally performed so as to uncover the actions of lipidomics-affecting PNPLA3 SNPs in NAFLD-specific pathological alterations. RESULTS PNPLA3 SNPs(rs139051, rs738408, rs738409, rs 2072906, rs2294918, rs2294919, and rs4823173) demonstrated extensive association with the serum lipidomics, especially phospholipid metabolites [lysophosphatidylcholine(LPC), lysophosphatidylcholine plasmalogen(LPCO), lysophosphatdylethanolamine(LPE), phosphatidylcholine(PC), choline plasmalogen(PCO), phosphatidylethanolamine(PE), ethanolamine plasmalogen(PEO)], of NAFLD patients. PNPLA3 rs139051(A/A genotype) and rs2294918(G/G genotype) dominated the up-regulatory effect on phospholipids of LPCs(LPC 17:0, LPC 18:0, LPC 20:0, LPC 20:1, LPC 20:2) and LPCOs(LPC O-16:1, LPC O-18:1). Moreover, subjects with high-level LPCs/LPCOs were predisposed to low-grade lobular inflammation of NAFLD(rho:-0.407 to-0.585, P < 0.05-0.001). The significant correlation of PNPLA3 rs139051 and inflammation grading [A/A vs A/G + G/G: 0.50(0.00, 1.75) vs 1.50(1.00, 2.00), P < 0.05] further demonstrated its pathological role based on the modulation of phospholipid metabolite profile.CONCLUSION The A/A genotype at PNPLA3 rs139051 exerts an upregulatory effect on serum phospholipids of LPCs and LPCOs, which are associated with low-grade lobular inflammation of NAFLD.

Genetics of non-alcoholic fatty liver disease: From susceptibility and nutrient interactions to management

Genetics plays an important role in determining the susceptibility of an individual to develop a disease. Complex, multi factorial diseases of modern day(diabetes, cardiovascular disease, hypertension and obesity) are a result of disparity between the type of food consumed and genes, suggesting that food which does not match the host genes is probably one of the major reasons for developing life style diseases. Non-alcoholic fatty liver is becoming a global epidemic leading to substantial morbidity. While various genotyping approaches such as whole exome sequencing using next generation sequencers and genome wide association studies have identified susceptibility loci for non-alcoholic fatty liver disease(NAFLD) including variants in patatin-like phospholipase domain containing 3 and transmembrane 6 superfamily member 2 genes apart from others; nutrient based studies emphasized on a combination of vitamin D, E and omega-3 fatty acids to manage fatty liver disease. However majority of the studies were conducted independent of each other and very few studies explored the interactions between the genetic susceptibility and nutrient interactions. Identifying such interactions will aid in optimizing the nutrition tailor made to an individual's genetic makeup, thereby aiding in delaying the onset of the disease and its progression. The present topic focuses on studies that identified the genetic susceptibility for NAFLD, nutritional recommendations, and their interactions for better management of NAFLD.