title: Hepatitis B virus-induced hepatocellular carcinoma: functional roles of MICA variants.
abstract: Hepatitis B virus infection is a high-risk factor for hepatocellular carcinoma. The human major histocompatibility complex class I chain-related gene A (MICA) is a ligand of the NKG2D receptor that modulates the NK and T-cell-mediated immune responses and is associated with several diseases. This study determined the effects of MICA polymorphisms during HBV infection and HBV-induced HCC. We conducted a case-controlled study in a Vietnamese cohort and genotyped ten functional MICA polymorphisms including the microsatellite motif in 552 clinically classified hepatitis B virus patients and 418 healthy controls. The serum soluble MICA levels (sMICA) were correlated with MICA variants and liver enzyme levels. We demonstrated a significant contribution of MICA rs2596542G/A promoter variant and nonsynonymous substitutions MICA-129Met/Val, MICA-251Gln/Arg, MICA-175Gly/Ser, triplet repeat polymorphism and respective haplotypes with HBV-induced HCC and HBV persistence. The circulating sMICA levels in HBV patient groups were elevated significantly compared with healthy controls. A significant contribution of studied MICA variants to sMICA levels was also observed. The liver enzymes alanine amino transferase (ALT), aspartate transaminase (AST), total bilirubin and direct bilirubin were positively correlated with sMICA levels suggesting sMICA as a biomarker for liver injury. We conclude that MICA polymorphisms play a crucial role in modulating innate immune responses, tumour surveillance and regulate disease susceptibility during HBV infection.
authors.affiliation: Institute of Tropical Medicine, University of Tübingen, Tübingen, Germany.
authors.forename: H V
authors.initials: HV
authors.lastname: Tong
authors.forename: N L
authors.initials: NL
authors.lastname: Toan
authors.forename: L H
authors.initials: LH
authors.lastname: Song
authors.forename: C-T
authors.initials: CT
authors.lastname: Bock
authors.forename: P G
authors.initials: PG
authors.lastname: Kremsner
authors.forename: T P
authors.initials: TP
authors.lastname: Velavan
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D006528:Carcinoma, Hepatocellular / Q000235:genetics*; D016022:Case-Control Studies; D015331:Cohort Studies; D005260:Female; D020022:Genetic Predisposition to Disease; D006509:Hepatitis B / Q000150:complications* / Q000235:genetics*; D006515:Hepatitis B virus / Q000276:immunology*; D015395:Histocompatibility Antigens Class I / Q000235:genetics* / Q000276:immunology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011110:Polymorphism, Genetic; D014744:Vietnam; D055815:Young Adult
chemical_list: D015395:Histocompatibility Antigens Class I; C099187:MHC class I-related chain A
keywords: MICA; hepatitis B virus; hepatocellular carcinoma; single nucleotide polymorphism; triplet repeat microsatellite