STAT4 gene polymorphisms are associated with susceptibility and ANA status in primary biliary cirrhosis. Dis Markers. 2014;2014:727393. [PMID: 24648611 PMCID: PMC3932279 DOI: 10.1155/2014/727393]

Regional heritability mapping identifies several novel loci (STAT4, ULK4, and KCNH5) for primary biliary cholangitis in the Japanese population

While the advent of GWAS more than a decade ago has ushered in remarkable advances in our understanding of complex traits, the limitations of single-SNP analysis have also led to the development of several other approaches. Simulation studies have shown that the regional heritability mapping (RHM) method, which makes use of multiple adjacent SNPs jointly to estimate the genetic effect of a given region of the genome, generally has higher detection power than single-SNP GWAS. However, thus far its use has been mostly limited to agricultural settings, and its potential for the discovery of new genes in human diseases is yet to be fully exploited. In this study, by applying the RHM method to primary biliary cholangitis (PBC) in the Japanese population, we identified three novel loci (STAT4, ULK4, and KCNH5) at the genome-wide significance level, two of which (ULK4 and KCNH5) have not been found associated with PBC in any population previously. Notably, these genes could not be detected by using conventional single-SNP GWAS, highlighting the potential of the RHM method for the detection of new susceptibility loci in human diseases. These findings thereby provide strong empirical evidence that RHM is an effective and practical complementary approach to GWAS in this context. Also, liver tissue mRNA microarray analysis revealed higher gene expression levels in ULK4 in PBC patients (P < 0.01). Lastly, we estimated the common SNP heritability of PBC in the Japanese population (0.210 ± 0.026).

Polymorphism at rs9264942 is associated with HLA-C expression and inflammatory bowel disease in the Japanese

An expression quantitative trait locus (eQTL) single-nucleotide polymorphism (SNP) at rs9264942 was earlier associated with human leukocyte antigen (HLA)-C expression in Europeans. HLA-C has also been related to inflammatory bowel disease (IBD) risk in the Japanese. This study examined whether an eQTL SNP at rs9264942 could regulate HLA-C expression and whether four SNP haplotypes, including the eQTL SNP at rs9264942 and three SNPs at rs2270191, rs3132550, and rs6915986 of IBD risk carried in the HLA-C*12:02~B*52:01~DRB1*15:02 allele, were associated with IBD in the Japanese. HLA-C expression on CD3e⁺CD8a⁺ lymphocytes was significantly higher for the CC or CT genotype than for the TT genotype of rs9264942. The TACC haplotype of the four SNPs was associated with a strong susceptibility to ulcerative colitis (UC) but protection against Crohn’s disease (CD) as well as with disease clinical outcome. While UC protectivity was significant but CD susceptibility was not for the CGTT haplotype, the significance of UC protectivity disappeared but CD susceptibility reached significance for the CGCT haplotype. In conclusion, our findings support that the eQTL SNP at rs9264942 regulates HLA-C expression in the Japanese and suggest that the four SNPs, which are in strong linkage disequilibrium, may be surrogate marker candidates of a particular HLA haplotype, HLA-C*12:02~B*52:01~DRB1*15:02, related to IBD susceptibility and disease outcome.

STAT4: an immunoregulator contributing to diverse human diseases

Signal transducer and activator of transcription 4 (STAT4) is a member of the STAT family and localizes to the cytoplasm. STAT4 is phosphorylated after a variety of cytokines bind to the membrane, and then dimerized STAT4 translocates to the nucleus to regulate gene expression. We reviewed the essential role played by STAT4 in a wide variety of cells and the pathogenesis of diverse human diseases, especially many kinds of autoimmune and inflammatory diseases, via activation by different cytokines through the Janus kinase (JAK)-STAT signaling pathway.

Genetic association of E26 transformation specific sequence 1 polymorphisms with the susceptibility of primary biliary cholangitis in China

Primary biliary cholangitis (PBC) is a chronic and cholestatic liver disease characterized by an autoimmune-mediated destruction of intrahepatic bile ducts. E26 transformation specific sequence 1 (ETS-1) is a transcription factor regulating the expression of various immune-related genes. The aim of our study was to identify the associations between the gene polymorphisms of ETS-1 with the susceptibility and clinical characteristics of PBC in Chinese Han population. Three single nucleotide polymorphisms (rs4937333, rs11221332 and rs73013527) of ETS-1 were selected based on relevant studies. Genotyping was executed with polymerase chain reaction-high resolution melting (PCR-HRM) assay. SNP rs4937333 of ETS-1 was prominent correlation with the susceptibility of PBC (P = 0.007, OR = 1.44, 95%CI = 1.10–1.88). For rs4937333, PBC patients carrying the allele T assumed high-level TP (P = 0.020), and homozygous genotype TT assumed low-level RDW (P = 0.033). For rs11221332, PBC patients carrying the allele T assumed high-level TP and HDLC (P = 0.004, P = 0.015, respectively). For rs73013527, PBC patients carrying the allele T assumed low-level PLT (P = 0.002), and homozygous genotype TT assumed high-level RDW (P = 0.021). In conclusion, Gene polymorphisms of ETS-1 present relevant with the susceptibility of PBC, and affect the expression of TP, HDLC, PLT and RDW concentrations in patients with PBC.

The influence of polymorphic GSTM1 gene on the increased susceptibility of non-viral hepatic cirrhosis: evidence from observational studies

It is reported that glutathione S-transferase mu (GSTM1) polymorphism is associated with non-viral hepatic cirrhosis (HC). However, some studies showed different views. Therefore, in this paper, a meta-analysis was conducted to get a more comprehensive understanding of GSTM1 polymorphisms in non-viral HC susceptibility. The results showed that GSTM1 null was associated with the increased risk of non-viral HC (OR = 1.337, 95% CI 1.112–1.804, p = 0.005). Subgroup analysis of cirrhosis type revealed that GSTM1 null was a prominent risk factor for alcoholic HC (OR = 1.416, 95% CI 1.112–1.804, p = 0.005). Meanwhile, subgroup analysis of population indicated that the significant differences only existed in Asian population (OR = 1.719, 95% CI 1.212–2.438, p = 0.002). In hospital-based studies, patients with GSTM1 null were more likely in risk of HC (OR = 1.426, 95% CI 1.092–1.863, p = 0.009). Subgroup analysis using genotyping method showed a significant association between GSTM1 null genotype and HC occurrence in the studies employing the multiple PCR genotyping method (OR = 1.559, 95% CI 1.171–2.076, p = 0.002). Based on the results of this analysis, it was concluded that GSTM1 null genotype could increase the susceptibility of non-viral hepatic cirrhosis. In addition, alcohol intake, Asian ethnicity, sample source from hospital and multiple PCR genotyping method may also influence the susceptibility of hepatic cirrhosis.

Genetic and epigenetic influences on the loss of tolerance in autoimmunity

Immunological tolerance loss is fundamental to the development of autoimmunity; however, the underlying mechanisms remain elusive. Immune tolerance consists of central and peripheral tolerance. Central tolerance, which occurs in the thymus for T cells and bone marrow for B cells, is the primary way that the immune system discriminates self from non-self. Peripheral tolerance, which occurs in tissues and lymph nodes after lymphocyte maturation, controls self-reactive immune cells and prevents over-reactive immune responses to various environment factors. Loss of tolerance results in autoimmune disorders, such as systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), type 1 diabetes (T1D) and primary biliary cirrhosis (PBC). The etiology and pathogenesis of autoimmune diseases are highly complicated. Both genetic predisposition and epigenetic modifications are implicated in the loss of tolerance and autoimmunity. In this review, we will discuss the genetic and epigenetic influences on tolerance breakdown in autoimmunity. Genetic and epigenetic influences on autoimmune diseases, such as SLE, RA, T1D and PBC, will also be briefly discussed.

Genetics and epigenetics in the pathogenesis of primary biliary cholangitis

Primary biliary cholangitis (PBC) is a chronic, slowly progressive cholestatic autoimmune liver disease predominantly afflicting women. PBC is characterized by the presence of disease-specific antimitochondrial antibodies and the histological destruction of intrahepatic bile ducts, which eventually lead to cirrhosis and hepatic failure. Fortunately, ursodeoxycholic acid therapy has improved the outcome of the vast majority of PBC cases. Although the etiology of PBC has not yet been elucidated, human leukocyte antigen (HLA) class II alleles have been consistently associated with disease onset for decades. PBC patients may also have genetically determined risk factors in non-HLA regions. Meanwhile, exposure to environmental factors, such as infectious diseases and harmful chemicals, can produce epigenetic alterations in some individuals and subsequent PBC onset. In this review, we describe the influence of HLA alleles and other gene polymorphisms on PBC along with the results of genome-wide association studies on this disease and its future prospects in terms of epigenetics.

Polymorphisms of IL12RB2 May Affect the Natural History of Primary Biliary Cholangitis: A Single Centre Study

Background. Recent GWAS in primary biliary cholangitis (PBC) showed strong associations with SNPs located within interleukin-12 receptor (IL12R) beta-2 (IL12RB2) gene. Aims. We assessed whether genetic variation of IL12RB2 is associated with laboratory and clinical features of PBC. Methods. Genomic DNA was isolated from 306 patients with PBC and 258 age/gender-matched controls. PBC-specific anti-mitochondrial antibodies (AMA) were tested in all subjects by ELISA. Two SNPs, rs3790567 and rs6679356, of IL12RB2 were genotyped using the MGB-TaqMan SNP assay. Results. Despite comparable age at diagnosis of cirrhotic and noncirrhotic PBC patients, allele A of rs3790567 and allele C of rs6679356 were overrepresented in the former rather than the latter group (p = 0.0009 and p = 0.002, resp.). The risk of cirrhosis at presentation increased when allele A and allele C coexisted. AMA-M2 titres were significantly higher in AA homozygotes of rs3790567 compared to GG homozygotes (132 ± 54 versus 103 ± 62, p = 0.02) and in rs6679356 when C allele was present (p = 0.038). There were no other significant associations between IL12RB2 polymorphisms and laboratory or clinical features. Conclusion. In this first study analyzing phenotypic features of PBC carriers of the IL12RB2 polymorphisms, we found that carriers are more frequently cirrhotic at diagnosis and have significantly higher titres of AMA.

Genetic Contribution to the Pathogenesis of Primary Biliary Cholangitis

Formerly termed primary biliary cirrhosis, primary biliary cholangitis (PBC) is a chronic and progressive cholestatic liver disease characterized by the presence of antimitochondrial antibodies. Ursodeoxycholic acid (UDCA) therapy is the most effective and approved treatment for PBC and leads to a favorable outcome in the vast majority of cases. Although the etiology of PBC has not yet been elucidated, human leukocyte antigen (HLA) class II alleles have been consistently associated with disease onset for decades. Individuals in different geographic regions of the world may have varying susceptibility alleles that reflect indigenous triggering antigens. In this review, we describe the influence of HLA alleles and other gene polymorphisms on PBC along with the results of genome-wide association studies (GWAS) on this disease.

Recent advances in the diagnosis and treatment of primary biliary cholangitis

Primary biliary cholangitis (PBC), formerly referred to as primary biliary cirrhosis, is an infrequent progressive intrahepatic cholestatic autoimmune illness that can evolve into hepatic fibrosis, hepatic cirrhosis, hepatic failure, and, in some cases, hepatocellular carcinoma. The disease itself is characterized by T-lymphocyte-mediated chronic non-suppurative destructive cholangitis and elevated serum levels of extremely specific anti-mitochondrial autoantibodies (AMAs). In this article, we will not only review epidemiology, risk factors, natural history, predictive scores, radiologic approaches (e.g., acoustic radiation force impulse imaging, vibration controlled transient elastography, and magnetic resonance elastography), clinical features, serological characteristics covering biochemical markers, immunoglobulins, infections markers, biomarkers, predictive fibrosis marker, specific antibodies (including AMAs such as AMA-M2), anti-nuclear autoantibodies [such as anti-multiple nuclear dot autoantibodies (anti-sp100, PML, NDP52, anti-sp140), anti-rim-like/membranous anti-nuclear autoantibodies (anti-gp210, anti-p62), anti-centromere autoantibodies, and some of the novel autoantibodies], histopathological characteristics of PBC, diagnostic advances, and anti-diastole of PBC. Furthermore, this review emphasizes the recent advances in research of PBC in terms of therapies, including ursodeoxycholic acid, budesonide, methotrexate, obeticholic acid, cyclosporine A, fibrates such as bezafibrate and fenofibrate, rituximab, mesenchymal stem cells transplant, and hepatic transplant. Currently, hepatic transplant remains the only optimal choice with acknowledged treatment efficiency for end-stage PBC patients.

Association of STAT4 polymorphisms with hepatitis B virus infection and clearance in Chinese Han population

Genome-wide association study indicates that STAT4 is a plausible candidate for an association study with HBV-related liver diseases. We aimed to examine the roles of STAT4 polymorphisms on HBV-related liver diseases in a Chinese Han population. We selected 13 SNPs in STAT4 based on the HapMap database to investigate their associations in 3,033 participants. SNP rs7574865 was significantly associated with HBV infection [odds ratio (OR) 1.15; 95 % confidence interval (CI) 1.00, 1.31; P = 0.046] and clearance (OR 1.17; 95 % CI 1.02, 1.33; P = 0.028). Further, haplotype-based association analysis indicated that the haplotype CTCTT, formed by SNPs rs8179673, rs7574865, rs4274624, rs11889341, and rs10168266, was significantly associated with HBV infection (OR 0.87; 95 % CI 0.76, 0.99; P = 0.022) and clearance (OR 0.86; 95 % CI 0.75, 0.99; P = 0.018). Bioinformatics analysis of these SNPs predicted that they participate in transcriptional regulation. Taken together, our findings demonstrate that variants in STAT4 play a critical role in HBV infection and clearance in the Chinese Han population.

Association of IL12A Expression Quantitative Trait Loci (eQTL) With Primary Biliary Cirrhosis in a Chinese Han Population

Genome-wide association studies in European individuals have revealed that IL12A is strongly associated with primary biliary cirrhosis (PBC). However, this association was not detected in replicative studies conducted in Chinese Han and Japanese populations.To verify contributions of genetic variants of IL12A to the pathogenesis of PBC in Chinese populations, a replicative study of 22 single nucleotide polymorphisms (SNPs) around the IL12A gene locus was performed in a cohort of 586 PBC cases and 726 healthy controls. Three out of the 22 SNPs were significantly associated with PBC. The 2 SNPs with the most significant association signal were rs4679868 (P = 6.59E-05, odds ratio [OR] = 1.554 [1.253-1.927]) and rs6441286 (P = 8.00E-05, OR = 1.551 [1.250-1.924]). These 2 SNPs were strongly linked to each other (r = 0.981), and both were found to be significantly associated with PBC in European populations.An expression quantitative trait loci (eQTL) analysis was performed based on the observation that these 2 SNPs were located in proximity to 2 enhancers verified by luciferase reporter systems in the HEK293 cell line. The results of eQTL analysis, conducted using the publically accessible data, showed that the risk alleles of rs4679868 and rs6441286 were significantly associated with decreased expression of IL12A in lymphoblastoid cell lines derived from individuals of Chinese Han ancestry (P = 0.0031 for rs4679868 and P = 0.0073 for rs6441286). In addition, the risk alleles of the 2 SNPs were significantly associated with down-regulation of SCHIP1, a celiac disease susceptible gene, 91.5 kb upstream of IL12A.These results not only demonstrated that IL12A is associated with PBC in the Chinese Han population but also identified a potential mechanism for its involvement in the pathogenesis of PBC.