No role of the -2518 promoter polymorphism of monocyte chemotactic protein-1 in chronic hepatitis C

Genes and hepatitis C: susceptibility, fibrosis progression and response to treatment

Hepatitis C virus contact and infection show three different phenotypes: spontaneous viral clearance (SVC), chronic hepatitis C (CHC) and sustained virological response (SVR) following antiviral treatment. Many factors, including genetics, influence the evolution of these three phenotypes. We performed a literature search (PubMed) up to 31 January 2010 without language restriction to identify relevant studies on genes and hepatitis C. Additional studies were sought by reviewing the reference lists of the identified articles. Meta-analysis (using Meta-disk 1.4) was conducted to evaluate the association of single nucleotide polymorphism (SNP) in the IL28B region and SVR. The candidate gene approach showed strong relationships between human leucocyte antigen class II (DQB1(*) 0301 and DRB1(*) 1101) and SVC. A cirrhosis risk score involving 7 SNPs has been validated recently. The set of odds ratios of studies demonstrated an association between SNP (rs12987960/rs8099917) in the IL28B and SVR in CHC treated with peginterferon plus ribavirin (OR: 4.6; 95% CI: 2.9-7.3). The overall distribution of protective allele correlated with ethnic differences in SVR (Asians, Europeans, Hispanic and Afro-Americans) together with SVC, but not with fibrosis stage or viral load. These polymorphisms did not influence SVR in very-easy-to-treat patients such as genotype 2/3, rapid virological responders or patients with acute hepatitis C. While the genetic fingerprint for fibrosis progression remains elusive, IL28b polymorphism predicts SVC and SVR. However, nearly half of patients achieving SVR did not show favourable genotype. Further genetic signals are warranted to complete the puzzle of factors influencing hepatitis C.

Multiple variants in toll-like receptor 4 gene modulate risk of liver fibrosis in Caucasians with chronic hepatitis C infection

BACKGROUND/AIMS

Seven genomic loci, implicated by single nucleotide polymorphisms (SNPs), have recently been associated with progression to advanced fibrosis (fibrosis risk) in patients with chronic hepatitis C virus. Other variants in these loci have not been examined but may be associated with fibrosis risk independently of or due to linkage disequilibrium with the original polymorphisms.

METHODS

We carried out dense genotyping and association testing of additional SNPs in each of the 7 regions in Caucasian case control samples.

RESULTS

We identified several SNPs in the toll-like receptor 4 (TLR4) and syntaxin binding protein 5-like (STXBP5L) loci that were associated with fibrosis risk independently of the original significant SNPs. Haplotypes consisting of these SNPs in TLR4 and STXBP5L were strongly associated with fibrosis risk (global P=3.04 x 10(-5) and 4.49 x 10(-6), respectively).

CONCLUSIONS

Multiple variants in TLR4 and STXBP5L genes modulate risk of liver fibrosis. These findings are of relevance for understanding the pathogenesis of HCV-induced liver disease in Caucasians and may be extended to other ethnicities as well.

Recognition of genetic factors influencing the progression of hepatitis C : potential for personalized therapy

Infection with hepatitis C virus (HCV) is a major cause of chronic liver disease. Hepatic fibrosis may develop in subjects with chronic HCV infection, culminating in cirrhosis and an increased risk of hepatocellular carcinoma. The rate of development of fibrosis varies substantially between individuals; while it is influenced by a number of demographic and environmental factors, these account for only a small proportion of the variability. There are no clinical markers or tests that predict the rate of fibrosis progression in an individual subject. Thus, there has been increasing interest in the influence of host genetic factors on the rate of disease progression, and whether a genetic signature can be developed to reliably identify individuals at risk of severe disease. Numerous case-control, candidate gene, allele-association studies have examined the relationship between host single nucleotide polymorphisms or other genetic mutations and fibrosis in patients with chronic HCV infection. However, these studies have generally been irreproducible and disappointing. As seen with genetic studies for other diseases, small study cohorts and poor study design have contributed to limited meaningful findings. The successful determination of genetic signatures for fibrosis progression in chronic HCV will require multicenter collaborations using genome-wide association studies, with large, phenotypically well-defined sample sets. While these studies will require a significant financial commitment, a successful outcome offers the potential for personalized therapy and better patient management.

DNA polymorphisms and response to treatment in patients with chronic hepatitis C: results from the HALT-C trial

BACKGROUND/AIMS

Certain host genetic polymorphisms reportedly affect the likelihood of a sustained virological response (SVR) to interferon treatment in subjects infected with hepatitis C virus (HCV). As part of the HALT-C trial we evaluated genetic associations among patients infected with HCV genotype 1 who had failed previous interferon treatment.

METHODS

SVR was determined 24 weeks after completing treatment with pegylated interferon alfa-2a and ribavirin. Eight single nucleotide polymorphisms (SNPs) were selected on the basis of previously reported associations with treatment response. Genotypes were assessed by polymerase chain reaction-based assays. The percentage of patients who achieved SVR was determined for each genotype and for an IL10 promoter diplotype.

RESULTS

Among 637 non-Hispanic Caucasian patients there were no significant associations between genotype for any individual SNP (IL10-1082, IL10-592, TNF-308, TNF-238, TGFB1 codon 25, CCL2-2518, EPHX1 codon 113 and AGT-6) and SVR, but SVR was more common among the patients who were homozygous for the ACC IL10 promoter diplotype (adjusted odds ratio, 3.24; 95% confidence interval, 1.33-7.78; p=0.001).

CONCLUSIONS

Among non-Hispanic Caucasian patients treated with peginterferon and ribavirin after failing previous treatment with interferon, homozygosity for the ACC IL10 promoter diplotype was associated with SVR.

Evaluation of complement factor 5 variants as genetic risk factors for the development of advanced fibrosis in chronic hepatitis C infection

BACKGROUND/AIMS

Intercross studies in inbred mice susceptible or resistant to liver fibrosis revealed complement factor 5 as a quantitative trait gene associated with the development of fibrosis. In 277 patients with hepatitis C, two C5 SNPs, rs17611 and rs2300929, have been associated with advanced fibrosis.

METHODS

We investigated the association of these C5 SNPs with advanced fibrosis in 1435 HCV infected patients and in 1003 patients with other liver diseases. We performed genotyping with melting curve analysis using fluorescence resonance energy transfer probes in the LightCycler.

RESULTS

The defined high-risk genotypes (AA and TT) and alleles (A and T) were not associated with advanced fibrosis in HCV patients when Chi square testing and logistic regression analysis were applied (rs17611A 0.45 in F0-1 vs. 0.43 in F2-4, P=0.31; rs2300929T 0.91 F0-1 and 0.91 in F2-4, P=0.82). In the group of patients with liver diseases other than HCV we neither found an association of the C5 SNPs with advanced fibrosis nor an overrepresentation of the SNPs in patients with cirrhosis.

CONCLUSIONS

We found no evidence that these C5 SNPs are genetic risk factors for the development of advanced fibrosis in chronic HCV infection or other chronic liver diseases.

Hepatitis C -- identifying patients with progressive liver injury

Hepatitis C follows a variable course with some patients developing progressive liver fibrosis, cirrhosis and hepatocellular carcinoma, while others have minimal or no significant liver disease after decades of infection. Studies have identified both host and viral factors associated with disease progression. The importance of general factors such as age at infection, gender, immune status and alcohol consumption has long been recognized; however recently, polymorphisms in a wide array of genes have also been shown to be associated with progressive fibrosis. How specific viral proteins may contribute to disease progression has also been studied. This review highlights what is currently known about the factors associated with progressive liver injury in patients with hepatitis C. A greater understanding of the determinants of disease progression will hopefully lead to improved utilization of existing treatments and ultimately may aid in identification of new therapeutic targets.