Programmed cell death-1 rs11568821 and interleukin-28B rs12979860 polymorphisms in autoimmune hepatitis

Abstract

Background: Autoimmune hepatitis (AIH) is a relatively rare chronic liver disease of unknown etiology. The genetic background affects susceptibility, clinical phenotype, and prognosis. The programmed cell death-1 rs11568821 polymorphism (PD1.3) has been associated with susceptibility to autoimmune diseases. The interleukin-28B (IL28B) rs12979860 polymorphism has been associated with steatosis, inflammation, and fibrosis in liver diseases.

Aim: Our aim was to investigate for the first time the incidence and clinical significance of PD1.3 and IL28B rs12979860 in AIH.

Methods: Two hundred patients with AIH were evaluated, while 100 healthy subjects were used as controls. Genotyping was performed with in-house allelic discrimination End-Point PCR.

Results: The SNP PD1.3/A was present in 36/200 (18%) AIH patients compared to 28/100 (28%) healthy controls (p = 0.065). The AA/GA genotypes were not associated with the mode of presentation of AIH, the histological grade or stage, the presence of cirrhosis, risk of disease progression, response to treatment and survival. The IL28B rs12979860 genotype distribution was CC 79/200 (39.5%), TT 36/200 (18%) and CT 85/200 (42.5%), in similar rates with healthy controls (p = 0.878). Inflammatory activity and fibrosis stage did not differ between CC homozygotes and CT/TT carriers. LDL cholesterol was significantly higher in CC than CT/TT patients (P = 0.027), though no differences was found regarding the presence of steatosis or steatohepatitis. On-treatment response to immunosuppressive treatment was not affected by the IL28B rs12979860 polymorphism. However, CC homozygotes AIH patients achieved treatment withdrawal in significantly higher rates (OR 2.3, 95%CI: 1.1-4.7, P = 0.02) irrespective of the presence of steatosis or steatohepatitis.

Conclusions: The PD1.3 and IL28B rs12979860 variants are unlikely to contribute to AIH susceptibility, disease presentation and prognosis. The IL28B rs12979860 is not associated with the presence of concurrent steatosis or steatohepatitis. However, although on-treatment response rates to immunosuppression were not affected by the IL28B rs12979860 polymorphism, AIH patients with CC homozygosity were more likely to achieve complete treatment withdrawal. This novel finding needs validation and further clarification from larger multicenter studies.

Keywords: AIH, Autoimmune hepatitis.; ANA, Antinuclear antibodies.; Anti-LC1, Liver cytosol type-1 antibodies.; Anti-LKM1, Liver kidney microsomal type-1 antibodies; Anti-SLA/LP, Soluble liver antigen/liver pancreas antibodies.; Autoimmune hepatitis; CR, Complete response.; HCC, Hepatocellular carcinoma.; HCV, Hepatis C virus.; HDL, High density lipoprotein.; HLA, Human leukocyte antigen.; HWE, Hardy-weinberg equilibrium.; IL28B, Interleukin 28B.; INR, International normalized ratio.; IQR, Interquartile range.; IgG, Immunoglobulin class G.; Interleukin-28B; LDL, Low density lipoprotein; MetS, Metabolic syndrome.; NAFLD, Non-alcoholic fatty liver disease.; PCR, Polymerase chain reaction.; PD1, Programmed cell death-1.; Polymorphisms; Programmed cell death-1; SD, Standard deviation.; SLE, Systemic lupus erythematosus.; SMA, Smooth muscle antibodies.; SNP, Single nucleotide polymorphism.; ULN, Upper limit of normal..