| Background Hepatitis C virus (HCV) infection is the leading cause of cirrhosis, hepatic decompensation, hepatocellular carcinoma (HCC). This is not only relevant to the infection with HCV genotype, but also with the host immune status, the cytokine genotype and the level of cytokine expression. Approximately 20% individuals can spontaneously clear HCV infection. The mechanism of spontaneous eradication depends on factors of the host and the pathogen. The host immune response plays an important role in the spontaneous clearance. When HCV is not completely eradicated by immune system, chronic infection will happen. The persistence of chronic inflammation would induce the proliferation of hepatic fibrous connective tissues, even lead to cirrhosis, liver cancer. Therefore, the clinical outcome of HCV infection is correlated with viral factors and host genetic factors. It is suggested that host genetic factors have important impact on the incidence and prognosis of HCV infection.The Human Genome Project research suggests:homologous human gene is 99.9%, only 0.1% of the difference determines the genetic traits of different people, different susceptibility to certain diseases and the different therapy effect of certain medications, and these differences are manifested in the variant nucleotide sites, called single nucleotide polymorphisms (single nucleotide polymorphisms, SNPs). At home and abroad there are many researches show that interleukin 28B (IL-28B) gene on chromosome 19 encoding interferon-A,-3 have SNP, and the variability of three single nucleotide polymorphisms(rs12980275, rs8099917, rs12979860) is associated with spontaneous HCV clearance and response to interferon treatment,and exists the racial differences. But the study about the relationship between IL-28B, HCV viral load and liver function is relatively small reported, especially there is seldom reported in Guangdong, and the research about the distribution of SNPs rs12980275, rs8099917, rs12979860 in gene IL-28B and the association of the distribution with response to treatment with pegylated interferon (PEG-IFN) is rare.Objective:To explore the distribution of the genotypes of host interleukin 28B polymorphism and the association of IL-28B variation with HCV viral load, genotype and liver function, and the association with response to treatment with pegylated interferon (peg-IFN). To analyze the role of IL-28B polymorphism in the diseases of HCV infection, and assess whether IL-28B genotypes may become the predictor of clinical outcome and therapeutic effect.Methods:94 patients of our hospital were conformed according to the Diagnosis of Hepatitis C Prevention Guideline made by Infectious Diseases and Parasitic Disease Society and Hepatology branch of Chinese Medical Association in 2004. A total of 74 individuals were subjected to treatment with pegylated interferon-alpha and ribavirin (peg-IFN/RBV). Specimen collection methods:for the 74 CHC patients receiving peg-IFN/RBV, the peripheral intravenous blood (EDTA anticoagulant,10ml once one person) was collected at the time of pre-treatment, week 4,12,24,48 of treatment and 24 weeks after the end of treatment. After the whole blood was collected, plasma and peripheral blood mononuclear cells (peripheral blood mononuclear cells, PBMC) were separated and extracted. For the 20 patients without treatment, peripheral intravenous blood was collected for one time, then was separated and extracted the plasma and PBMC.To extract the PBMC genomic DNA from these patients, primers were designed to amplify IL-28B gene polymorphisms such as rs8099917, rs 12979860 and rs12980275, and sequence analysis of each SNP locus genotypes.The determination of plasma HCV load (Da An Gene Co., Ltd. of Zhongshan kit) is used fluorescence quantitative polymerase chain reaction.Hepatitis C virus sub-type-specific primers and fluorescent probes, one-step polymerase chain reaction combined with Taqman technology were used to determine type 1 and non-type 1 fluorescent PCR genotyping of hepatitis C virus (in Shanghai Jiang biotechnology Co., Ltd.).Liver function tests:using automatic biochemical analyzer (equipment manufacturers: Japan OLYMPUS AU 2700).All data were statistically analyzed using SPSS16.0 science, Comparisons of quantitative variables were performed using t-test, Categorical variables were analyzed with chi-square test and the Fisher’s exact test; P value< 0.05 was considered as significant.Results:Host IL-28B gene sequencing was detected in 94 patients with chronic hepatitis C. The proportions of IL-28B genotypes were 82 (87.2%),12 (12.8%),0 (0%) for TT, TG, GG at rs8099917; 78 (83.0%),16 (17.0%),0 (0%) for CC, CT, TT at rs12979860; and 75 (79.8%),19 (20.2%),0 (0%) for AA, AG, GG at rs12980275, respectively.HCV genotyping assay was detected in a total of 89 cases of 94 patients, in which HCV genotype-1 was accounted for 74.2% and non-type 1 was accounted for 25.8%. There is a statistical significant difference between the two groups (F> 0.005).A total of 94 patients were underwent liver function and HCV-RNA load testing, the variability of three single nucleotide polymorphisms of IL-28B (rs8099917, rs12979860, rs12980275) had no relationship with serum total bilirubin (TB), aspartate aminotransferase (AST), albumin (ALB), cholinesterase (CHE), prothrombin time (PT) and HCV-RNA levels (P> 0.05); the variation of rs8099917 and rs12980275 were not related to propylene aminotransferase (ALT) levels (P> 0.05), but at rs12980275 the CC genotype was shown to have a higher ALT levels the CT genotype (P= 0.008).The rate of rapid viral response (RVR) in the 74 patients treated with peg-IFN/RBV was 66.2%, and 77.0% of sustained viral response (SVR); There was no significant difference between HCV genotype-1 and HCV non genotype-1 patients treated with peg-IFN (P>0.05). In HCV genotpe-1-infected patients, only rs 12979860 was associated with SVR, the proportion of rs12979860 CC in SVR group was significantly higher than that in non SVR group (88.4% vs.58.3%, P< 0.05). In non-genotype 1-infected patients, none of the three SNPs was associated with RVR or SVR (P>0.05).Conclusions:1. Most patients with chronic hepatitis C in Guangdong province have rs12980275 AA genotype, rs 12979860 CC genotype, and rs8099917 TT genotype in IL-28B gene.2. All genotypes of three SNPs in IL28B gene are not associated with HCV-RNA viral load. Patients who have CC genotype at rs 12979860 might have higher level of serum ALT than the other.3. In Guangdong province region, patients with chronic hepatitis C virus infection might have a better immune response to the standard strategy of combination treatment with pegylated interferon alpha 2a plus ribavirin.4. In individuals with HCV genotype-1, the variations of rs12979860 may be a important predictor of pre-treatment SVR, and genotype CC at rs12979860 polymorphism might have the advantage for the SVR. |
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