Background Single-nucleotide polymorphisms (SNPs) in the IL28B and PNPLA3 gene regions have been associated with hepatic steatosis in genotype 1 (G1) chronic HCV infection but their clinical impacts remain to be determined. Aim We sought to validate these associations and to explore their impact on treatment response to peginterferon and ribavirin therapy. Methods A total of 972 G1 HCV-infected Caucasian patients were genotyped for the SNPs rs12979860 (IL28B) and rs2896019 (PNPLA3). Multivariable analysis tested IL28B and PNPLA3 for association with the presence of any steatosis (>0 %); clinically significant steatosis (>5 %); steatosis severity (grade 0-3/4); and the interacting associations of the SNPs and hepatic steatosis to sustained viral response (SVR). Results IL28B and PNPLA3 polymorphisms were associated with the presence of any steatosis (rs12979860, p = 1.87 × 10 -7; rs2896019, p = 7.56 × 10 -4); clinically significant steatosis (rs12979860, p = 1.82 × 10 -3; rs2896019, p = 1.27 × 10 -4); and steatosis severity (rs12979860, p = 2.05 × 10 -8; rs2896019, p = 2.62 × 10 -6). Obesity, hypertriglyceridemia, hyperglycemia, liver fibrosis, and liver inflammation were all independently associated with worse steatosis. Hepatic steatosis was associated with lower SVR, and this effect was attenuated by IL28B. PNPLA3 had no independent association with SVR. Conclusions IL28B and PNPLA3 are associated with hepatic steatosis prevalence and severity in Caucasians with G1 HCV, suggesting differing potential genetic risk pathways to steatosis. IL28B attenuates the association between steatosis and SVR. Remediable metabolic risk factors remain important, independently of these polymorphisms, and remain key therapeutic goals to achieve better outcomes for patients with HCV-associated hepatic steatosis.
Bibliographical noteFunding Information:
Conflict of interest The authors disclose the following: Drs. Thompson, Harrison, Sulkowski, Afdhal, McHutchison and Muir report having received research and grant support from Schering-Plough (now Merck); Drs Afdhal, Harrison, McHutchison, Goldstein and Muir have received consulting fees or acted in an advisory capacity for Schering-Plough or Merck. Dr Harrison has received grant and research support from Genentech, Merck, and Rottapharm, worked in an advisory capacity for Three Rivers Pharmaceuticals and Amylin and for speaker’s bureau for Bristol Myers Squibb and Merck. Drs Albrecht and Pedicone are employees of Schering-Plough (now Merck & Co.) and are stockholders in this entity. Dr McHutchison is now employed by Gilead Sciences. Dr Noviello is a former employee of Schering-Plough and is now a consultant to Merck & Co. Drs. Thompson, Ge, Urban, McHutchison and Goldstein are co-inventors of a patent application based on the IL28B finding.
Acknowledgments The authors would like to thank the patients in the IDEAL trial as well as the principal investigators, study coordinators, and nurses involved. The authors thank Megan Koehler, DCRI for her statistical review. The study was funded by Schering-Plough Research Institute, Kenilworth, NJ (now Merck and Co.). Drs. Clark and Thompson received funding support from the Duke Clinical Research Institute, the Richard Boebel Family Fund, the National Health and Medical Research Council of Australia (PJC: APP1017139), the Gastroenterological Society of Australia. Dr Thompson received funding from the Royal Australian College of Physicians. Dr. Clark received funding from the National Centre in HIV Epidemiology and Clinical Research (now The Kirby Institute for Infection and Immunity in Society), University of New South Wales, Australia, and the AASLD/LIFER Clinical and Translational Research Fellowship in Liver Diseases Award.
- Abdominal obesity metabolic syndrome
- Adiponutrin, human
- Fatty liver
- IL28B protein, human
- PNPLA3 protein, human
- Polymorphism, single-nucleotide, SNP