title: Cytochrome P4502D6(193-212): a new immunodominant epitope and target of virus/self cross-reactivity in liver kidney microsomal autoantibody type 1-positive liver disease.
abstract: Cytochrome P4502D6 (CYP2D6), target of liver kidney microsomal autoantibody type 1 (LKM1), characterizes autoimmune hepatitis type 2 (AIH2) but is also found in patients with chronic hepatitis C virus (HCV) infection. To provide a complete linear epitope B cell map of CYP2D6, we tested peptides spanning the entire sequence of CYP2D6. In addition to confirming previously described antigenic sites, we identified four new epitopes (193-212, 238-257, 268-287, and 478-497). CYP2D6(193-212) is immunodominant and was the target of 12 of 13 (93%) patients with AIH2 and 5 of 10 (50%) HCV/LKM1-positive patients. Because LKM1 is present in both AIH2 and a viral infection, we tested whether Abs to CYP2D6(193-212) arise through cross-reactive immunity between virus and self. We identified a hexameric sequence "RLLDLA" sharing 5 of 6 aa with "RLLDLS" of HCV(2985-2990) and all 6 aa with CMV(130-135). Of 17 CYP2D6(193-212)-reactive sera, 11 (7 AIH and 4 HCV) reacted by ELISA with the HCV homologue, 8 (5 AIH and 3 HCV) with the CMV homologue, and 8 (5 AIH and 3 HCV) showed double reactivity. Autoantibody binding to CYP2D6(193-212) was inhibited by preincubation with HCV(2977-2996) or CMV(121-140). Recombinant HCV-nonstructural protein 5 and CMV-UL98 proteins also inhibited Ab binding to CYP2D6(193-212). Affinity-purified CYP2D6(193-212)-specific Ab inhibited the metabolic activity of CYP2D6. The demonstrated similarity and cross-reactivity between CYP2D6(193-212) and two unrelated viruses suggests that multiple exposure to viruses mimicking self may represent an important pathway to the development of autoimmunity.
authors.affiliation: Institute of Hepatology, University College, London, United Kingdom.
authors.forename: Nanda
authors.initials: N
authors.lastname: Kerkar
authors.forename: Kaushik
authors.initials: K
authors.lastname: Choudhuri
authors.forename: Yun
authors.initials: Y
authors.lastname: Ma
authors.forename: Ayman
authors.initials: A
authors.lastname: Mahmoud
authors.forename: Dimitrios P
authors.initials: DP
authors.lastname: Bogdanos
authors.forename: Luigi
authors.initials: L
authors.lastname: Muratori
authors.forename: Francesco
authors.initials: F
authors.lastname: Bianchi
authors.forename: Roger
authors.initials: R
authors.lastname: Williams
authors.forename: Giorgina
authors.initials: G
authors.lastname: Mieli-Vergani
authors.forename: Diego
authors.initials: D
authors.lastname: Vergani
mesh_terms: D000293:Adolescent; D000328:Adult; D000595:Amino Acid Sequence; D001323:Autoantibodies / Q000096:biosynthesis / Q000097:blood / Q000378:metabolism*; D001324:Autoantigens / Q000276:immunology / Q000378:metabolism; D001402:B-Lymphocytes / Q000201:enzymology / Q000276:immunology; D002648:Child; D002675:Child, Preschool; D003429:Cross Reactions; D019389:Cytochrome P-450 CYP2D6 / Q000276:immunology* / Q000378:metabolism; D018604:Epitope Mapping / Q000379:methods; D005260:Female; D016174:Hepacivirus / Q000276:immunology*; D019698:Hepatitis C, Chronic / Q000276:immunology*; D019693:Hepatitis, Autoimmune / Q000276:immunology*; D006801:Humans; D016056:Immunodominant Epitopes / Q000276:immunology* / Q000378:metabolism; D007668:Kidney / Q000276:immunology; D008297:Male; D008862:Microsomes, Liver / Q000276:immunology; D008875:Middle Aged; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000276:immunology* / Q000378:metabolism
chemical_list: D001323:Autoantibodies; D001324:Autoantigens; D016056:Immunodominant Epitopes; D010446:Peptide Fragments; C060729:anti-liver kidney microsome antibody; D019389:Cytochrome P-450 CYP2D6