No evidence for genetic association of interferon regulatory factor 3 in systemic lupus erythematosus

Genetic Polymorphism in Toll-Like Receptor 3 and Interferon Regulatory Factor 3 in Hepatitis C Virus-Infected Patients: Correlation with Liver Cirrhosis

Host genetic factors could play a primary role in determining the risk for cirrhosis development in chronic hepatitis C virus (HCV)-infected patients. We designed this work to study the effect of single-nucleotide polymorphism (SNP) in Toll-like receptor 3 (TLR3) and interferon regulatory factor (IRF) on the risk of HCV-related cirrhosis. This study enrolled 139 Egyptian HCV-infected patients. They were divided into patients with cirrhotic (56) and noncirrhotic (83) liver. Genotyping of rs3775291 F459F (+1234C/T) and rs3775290 L412F (+1377C/T) in TLR3 and IRF3 rs2304204 (-925A/G) was performed by restriction fragment length polymorphism-polymerase chain reaction. Although there is no significant difference in genotype and allele distribution of +1377C/T of TLR3 gene between cirrhotic and noncirrhotic subjects, CC (odds ratio [OR] = 1.572, 95% confidence interval [CI]: 0.781-3.164); TT (OR = 1.463, 95% CI: 0.351-6.104) genotypes might be considered as risk factors for liver cirrhosis. On the contrary, the analysis revealed that only one genotype (CC) and one allele (C) were detected in +1234C/T SNP, with the total disappearance of CT/TT genotypes and T allele in all subjects. On the contrary, lower frequency has been found for the AG genotype of the IRF3 (-925A/G) gene in cirrhotic patients compared with noncirrhotic ones, indicating that AG is a protective genotype (OR = 0.509, 95% CI: 0.256-1.012). Our data stressed the association of AG genotype SNP in IRF3 (-925A/G) in protection against the worth outcome of HCV infection.

Abnormalities of the type I interferon signaling pathway in lupus autoimmunity

Type I interferons (IFNs), mostly IFNα and IFNβ, and the type I IFN Signature are important in the pathogenesis of Systemic Lupus Erythematosus (SLE), an autoimmune chronic condition linked to inflammation. Both IFNα and IFNβ trigger a signaling cascade that, through the activation of JAK1, TYK2, STAT1 and STAT2, initiates gene transcription of IFN stimulated genes (ISGs). Noteworthy, other STAT family members and IFN Responsive Factors (IRFs) can also contribute to the activation of the IFN response. Aberrant type I IFN signaling, therefore, can exacerbate SLE by deregulated homeostasis leading to unnecessary persistence of the biological effects of type I IFNs. The etiopathogenesis of SLE is partially known and considered multifactorial. Family-based and genome wide association studies (GWAS) have identified genetic and transcriptional abnormalities in key molecules directly involved in the type I IFN signaling pathway, namely TYK2, STAT1 and STAT4, and IRF5. Gain-of-function mutations that heighten IFNα/β production, which in turn maintains type I IFN signaling, are found in other pathologies like the interferonopathies. However, the distinctive characteristics have yet to be determined. Signaling molecules activated in response to type I IFNs are upregulated in immune cell subsets and affected tissues of SLE patients. Moreover, Type I IFNs induce chromatin remodeling leading to a state permissive to transcription, and SLE patients have increased global and gene-specific epigenetic modifications, such as hypomethylation of DNA and histone acetylation. Epigenome wide association studies (EWAS) highlight important differences between SLE patients and healthy controls in Interferon Stimulated Genes (ISGs). The combination of environmental and genetic factors may stimulate type I IFN signaling transiently and produce long-lasting detrimental effects through epigenetic alterations. Substantial evidence for the pathogenic role of type I IFNs in SLE advocates the clinical use of neutralizing anti-type I IFN receptor antibodies as a therapeutic strategy, with clinical studies already showing promising results. Current and future clinical trials will determine whether drugs targeting molecules of the type I IFN signaling pathway, like non-selective JAK inhibitors or specific TYK2 inhibitors, may benefit people living with lupus.

The Genetic Variants of Interferon Regulatory Factor-3 in Children with Asthma

Interferon Regulatory Factor-3 (IRF-3) is one of the key players in the inflammatory response mediated by the innate immune system. Although many studies have implicated a role for IRF-3 in the pathogenesis of inflammatory airway diseases, information about the possible association of IRF-3 genetic variants with asthma is scarce. We aimed to investigate the potential effects of IRF-3 polymorphisms in childhood asthma and asthma-related phenotypes. IRF-3 polymorphisms were first determined by sequencing 25 asthmatic and 25 healthy children. For further analysis, 609 asthmatic children and 191 healthy controls were screened for the genetic variants, such as rs2304204, rs2304205, rs320440, rs34739574, and rs7251. In addition, the relationship between these polymorphisms and asthma-related phenotypic features, including forced expiratory volume in one second values, eosinophil counts, and IgE levels was determined. rs7251 was associated with asthma in the codominant (P = 0.049) and G dominant (P = 0.025) model, however this significance was lost after False Discovery Rate analysis. Other investigated single nucleotide polymorphisms (SNPs) showed no significant association with asthma or asthma-related phenotypes. In conclusion, the seven SNPs of IRF-3 gene are not associated with asthma or asthma-related phenotypes in Turkish asthmatic children.

Independent Replication on Genome-Wide Association Study Signals Identifies IRF3 as a Novel Locus for Systemic Lupus Erythematosus

Systemic lupus erythematosus (SLE) is a genetically complex autoimmune disease. Despite the significant progress made in identifying susceptibility genes for SLE, the genetic architecture of the disease is far from being understood. In this study, we set to replicate a number of suggestive association signals found in genome-wide association studies (GWASs) in additional independent cohorts. Replication studies were performed on Han Chinese cohorts from Hong Kong and Anhui, involving a total of 2,269 cases and 5,073 controls. We identified a missense variant in IRF3 (rs7251) reaching genome-wide significance through a joint analysis of GWAS and replication data (OR = 0.876, P = 4.40E-08). A significant correlation was observed between rs7251 and lupus nephritis (LN) by subphenotype stratification (OR = 0.785, P = 0.0128). IRF3 is a key molecule in type I interferon production upon nucleic acid antigen stimulations and may inhibit regulatory T cell differentiation. Further elucidation of the mechanism of this association could help us better understand the pathogenesis of SLE.

Interferon regulatory factor 3 as key element of the interferon signature in plasmacytoid dendritic cells from systemic lupus erythematosus patients: novel genetic associations in the Mexican mestizo population

Many genetic studies have found an association between interferon regulatory factors (IRF) single nucleotide polymorphisms (SNPs) and systemic lupus erythematosus (SLE); however, specific dendritic cell (DC) alterations have not been assessed. The aim of the present study was to address the expression of IRF3 and IRF5 on different DC subsets from SLE patients, as well as their association with interferon (IFN)-α production and novel SNPs. For the genetic association analyses, 156 SLE patients and 272 healthy controls from the Mexican mestizo population were included. From these, 36 patients and 36 controls were included for functional analysis. Two IRF3 SNPs - rs2304206 and rs2304204 - were determined. We found an increased percentage of circulating pDC in SLE patients in comparison to controls (8.04 ± 1.48 versus 3.35 ± 0.8, P = 0.032). We also observed enhanced expression of IRF3 (64 ± 6.36 versus 36.1 ± 5.57, P = 0.004) and IRF5 (40 ± 5.25 versus 22.5 ± 2.6%, P = 0.010) restricted to this circulating pDC subset from SLE patients versus healthy controls. This finding was associated with higher IFN-α serum levels in SLE (160.2 ± 21 versus 106.1 ± 14 pg/ml, P = 0.036). Moreover, the IRF3 rs2304206 polymorphism was associated with increased susceptibility to SLE [odds ratio (OR), 95% confidence interval (CI) = 2.401 (1.187-4.858), P = 0.021] as well as enhanced levels of serum type I IFN in SLE patients who were positive for dsDNA autoantibodies. The IRF3 rs2304204 GG and AG genotypes conferred decreased risk for SLE. Our findings suggest that the predominant IRF3 expression on circulating pDC is a key element for the increased IFN-α activation based on the interplay between the rs2304206 gene variant and the presence of dsDNA autoantibodies in Mexican mestizo SLE patients.

No association between IRF3 polymorphism and susceptibility to hepatitis B virus infection in Chinese patients

AIM: To investigate the association between three tag single nucleotide polymorphisms (tagSNPs) in interferon regulatory factors (IRF3) and the genetic susceptibility to chronic hepatitis B virus (HBV) infection.

METHODS: We performed a case-control study of 985 Chinese cases of chronic HBV infection and 294 self-limiting HBV-infected individuals as controls. Three tagSNPs in IRF3 (rs10415576, rs2304204, rs2304206) were genotyped with the Multiplex SNaPshot technique. The genotype and allele frequencies were calculated and analyzed.

RESULTS: The three SNPs showed no significant genotype/allele associations with chronic HBV infection. Overall allele P values were: rs10415576, P = 0.0908, odds ratio (OR) [95% confidence interval (CI)] = 1.1798 (0.9740-1.4291); rs2304204, P = 0.5959, OR (95% CI) = 1.0597 (0.8552-1.3133); rs2304206, P = 0.8372, OR (95% CI) = 1.0250 (0.8097-1.2976). Overall genotype P values were: rs10415576, P = 0.2106; rs2304204, P = 0.8458; rs2304206, P = 0.8315. There were no statistically significant differences between patients with chronic HBV infection and controls. Haplotypes generated by these three SNPs were also not significantly different between the two groups.

CONCLUSION: The three tagSNPs of IRF3 are not associated with HBV infection in the Han Chinese population.

Interferon regulatory factors: beyond the antiviral response and their link to the development of autoimmune pathology

Abnormal production of interferon type I has been widely related to multiple autoimmune diseases, particularly systemic lupus erythematosus (SLE). It has been considered the molecular signature characterized by the overexpression of type I Interferon related genes in SLE patients. Among these, are the interferon regulatory factors (IRF). These transcription factors have been involved in the innate immune response, mainly the one related to the defense against viral infections; the development of immune cells and carcinogenesis. The role of IRF in autoimmune pathology has been addressed in diverse murine models. However, evidence in humans is quite scant. This review will focus on the evidence that supports the role of IRF in the development or susceptibility to autoimmune diseases. Specific emphasis will be made over the role of IRF-5 and IRF-7, since evidence of its association to the development of pathology, particularly systemic lupus erythematosus is the strongest.

Interferon induced with helicase C domain 1 (IFIH1) and virus-induced autoimmunity: a review

In addition to genetic factors, environmental triggers, including viruses and other pathogens, are thought to play a major role in the development of autoimmune disease. Recent findings have shown that viral-induced autoimmunity is likely to be genetically determined. In large-scale genetic analyses, an association of interferon induced with helicase C domain 1 (IFIH1) gene variants encoding a viral RNA-sensing helicase with susceptibility to several autoimmune diseases was found. To date, the precise role of IFIH1 in pathogenic mechanisms of viral-induced autoimmunity has yet to be fully elucidated. However, recent reports suggest that IFIH1 may play a role in the etiology of type 1 diabetes. Rare IFIH1 alleles have been shown to be protective against diabetes, and their carriage correlates with lower production of this helicase and its functional disruption. In contrast, upregulation of IFIH1 expression by viruses is associated with more severe disease, and could exacerbate the autoimmune process in susceptible individuals.

Genetic associations in type I interferon related pathways with autoimmunity

Type I interferons play an outstanding role in innate and adaptive immunity by enhancing functions of dendritic cells, inducing differentiation of monocytes, promoting immunoglobulin class switching in B cells and stimulating effector functions of T cells. The increased production of IFNα/β by plasmacytoid dendritic cells could be responsible for not only efficient antiviral defence, but it also may be a pathological factor in the development of various autoimmune disorders. The first evidence of a genetic link between type I interferons and autoimmune diseases was the observation that elevated IFNα activity is frequently detected in the sera of patients with systemic lupus erythematosus, and that this trait shows high heritability and familial aggregation in their first-degree healthy relatives. To date, a number of genes involved in interferon signalling have been associated with various autoimmune diseases. Patients with systemic lupus erythematosus, Sjögren's syndrome, dermatomyositis, psoriasis, and a fraction of patients with rheumatoid arthritis display a specific expression pattern of interferon-dependent genes in their leukocytes, termed the interferon signature. Here, in an attempt to understand the role of type I interferons in the pathogenesis of autoimmunity, we review the recent advances in the genetics of autoimmune diseases focusing on the association of genes involved in type I interferon pathways.