Asia-Inclusive Global Development of Enpatoran: Results of an Ethno-Bridging Study, Intrinsic/Extrinsic Factor Assessments and Disease Trajectory Modeling to Inform Design of a Phase II Multiregional Clinical Trial

Enpatoran is a novel, highly selective, and potent dual toll-like receptor (TLR)7 and TLR8 inhibitor currently under development for the treatment of autoimmune disorders including systemic lupus erythematosus (SLE), cutaneous lupus erythematosus (CLE), and myositis. The ongoing phase II study (WILLOW; NCT05162586) is evaluating enpatoran for 24 weeks in patients with active SLE or CLE and is currently recruiting. To support development of WILLOW as an Asia-inclusive multiregional clinical trial (MRCT) according to International Conference on Harmonisation E5 and E17 principles, we have evaluated ethnic sensitivity to enpatoran based on clinical pharmacokinetic (PK), pharmacodynamic (PD), and safety data from an ethno-bridging study (NCT04880213), supplemented by relevant quantitative PK, PD, and disease trajectory modeling (DTM) results, and drug metabolism/disease knowledge. A single-center, open-label, sequential dose group study in White and Japanese subjects matched by body weight, height, and sex demonstrated comparable PK and PD properties for enpatoran in Asian vs. non-Asian (White and other) subjects across single 100, 200, and 300 mg orally administered doses. DTM suggested no significant differences in SLE disease trajectory for Asian vs. non-Asian individuals. Aldehyde oxidase (AOX) is considered to be a key contributor to enpatoran metabolism, and a literature review indicated no relevant ethnic differences in AOX function based on in vitro and clinical PK data from marketed drugs metabolized by AOX, supporting the conclusion of low ethnic sensitivity for enpatoran. Taken together, the inclusion of Asian patients in MRCTs including WILLOW was informed based on a Totality of Evidence approach.

Associations of toll-like receptor polymorphisms with systemic lupus erythematosus: A meta-analysis

Objective

The objective of this study was to examine whether polymorphisms in toll-like receptors 7 and 4 (TLR7 and 4) contribute to vulnerability to systemic lupus erythematosus (SLE).

Methods

We searched MEDLINE, Embase, and Web of Science for relevant articles and performed a meta-analysis to investigate the relationship between TLR7 rs179008, rs3853839, rs1790010, TLR4 rs4986791, and rs798690 polymorphisms and SLE.

Results

Eighteen studies and 16 papers including 8022 patients with SLE and 9822 healthy controls were retrieved. Meta-analysis revealed that the TLR7 rs179008 T variant was not associated with SLE (OR = 1.008, 95% CI = 0.849-1.394, P = 0.504). Ethnic classification revealed no association between the TLR7 rs179008 T gene and SLE in either European or Latin American groups. Additionally, homozygous comparison, recessive, and dominant models revealed no association between the TLR7 rs179008 variant and SLE. In contrast, a significant association between SLE and the TLR7 rsrs3853839 GG + GA allele (OR = 2.135, 95% CI = 1.502-3.035, <0.001; OR = 23.20, 95% CI = 14.13-38.08, <0.001) was observed in the Arab and Asian groups. The T variant of TLR7 rsrs179010 was also associated with SLE in Asians (OR = 1.177, 95% CI = 1.048-1.321, P = 0.006). In contrast, the TLR4 rs4986791 variant was not associated with SLE in Europeans when allele, homozygous comparison, recessive, and dominant models were used. Furthermore, no association between the TLR4 rs4986790 variant and SLE risk in Europeans was found using any genomic model.

Conclusions

Meta-analysis revealed that the TLR7 rs3853839 variant is associated with SLE risk in Asians and Arabs and that TLR7 rs179010 is associated with SLE in Asians. However, TLR7 rs179008, TLR4 rs4986791, and TLR rs798690 polymorphisms were not associated with SLE risk.

Association of the polymorphisms rs179008 (TLR7), rs2004640 (IRF5), rs1800795 (IL-6) and rs2280788 (CCL5) with systemic lupus erythematosus in women of Mayan ethnicity from Yucatan

Introduction: IFN-α is the main cytokine in SLE, and single nucleotide polymorphisms (SNP) in different genes could induce it. Aim: To determine the association of rs2004640 (IRF5), rs179008 (TLR7), rs1800795 (IL-6) and rs2280788 (CCL5) with SLE in Mexican women with Mayan ethnicity. Methods: DNA and RNA were isolated from the peripheral blood of 110 patients and 200 healthy control subjects. SNP genotyping and gene expression analysis of IRF5, TLR7, IL-6 and IFN-α were determined by real-time PCR and analyzed with SNP Stat, Stata 10.1 and Graph Pad Prism v5. Results: rs2004640, rs179008, and rs1800795 in both groups were according to Hardy-Weinberg equilibrium. Risk alleles rs179008T and rs2004640T frequencies were higher in controls (p = 0.015 and p = 0.028, respectively), whereas rs179008A frequency was higher in patients (p = 0.015). Allelic combination AGT frequency was higher in patients (p = 0.001). IL-6 rs1800795C > G and CCL5 rs2280788G > C frequencies did not show significant differences (p > 0.05), being rs2280788G (CCL5) monomorphic in controls. SLE patients showed higher TLR7, IRF5, IL6, and IFN-α mRNA levels. IRF5 expression was higher in SLE patients homozygous for rs2004640T (IRF5). Conclusion: This work showed the contribution of TLR7 and IRF5 in SLE pathogenesis in Mayan females from Yucatan.

CCR5 promoter region polymorphisms in systemic lupus erythematosus

This study investigated the impacts of CCR5 promoter region polymorphisms on the development of systemic lupus erythematosus (SLE) by comparing CCR5 genotypes and haplotypes from SLE patients with ethnically matched controls. A total of 382 SLE patients (289 European-derived and 93 African-derived) and 375 controls (243 European-derived and 132 African-derived) were genotyped for the CCR2-64I G > A (rs1799864), CCR5-59353 C > T (rs1799988), CCR5-59356 C > T (rs41469351), CCR5-59402 A > G (rs1800023) and CCR5-59653 C > T (rs1800024) polymorphisms through polymerase chain reaction-restriction fragment length polymorphism and direct sequencing. Previous data from CCR5Δ32 analysis was included in the study to infer the CCR5 haplotypes and as a possible confounding factor in the binary logistic regression. European-derived patients showed a higher frequency of CCR5 wild-type genotype (conversely, a reduced frequency of Δ32 allele) and a reduced frequency of the HHG*2 haplotype compared to controls; both factors significantly affecting disease risk [p = .003 (OR 3.5, 95%CI 1.6-7.5) and 2.0% vs. 7.2% (residual p = 2.9E - 5), respectively]. Additionally, the HHA/HHB, HHC and HHG*2 haplotype frequencies differed between African-derived patients and controls [10% vs. 20.5% (residual p = .003), 29.4% vs. 17.4% (residual p = .003) and 3.9% vs. 0.8% (residual p = .023), respectively]. Considering the clinical manifestations of the disease, the CCR5Δ32 presence was confirmed as a susceptibility factor to class IV nephritis in the African-derived group and when all patients were grouped for comparison [pcorrected  = .012 (OR 3.0; 95%CI 3.0-333.3) and pcorrected  = .0006 (OR 6.8; 95%CI 1.9-24.8), respectively]. In conclusion, this study indicates that CCR5 promoter polymorphisms are important disease modifiers in SLE. Present data reinforces the CCR5Δ32 polymorphism as a protective factor for the development of the disease in European-derived patients and as a susceptibility factor for class IV nephritis in African-derived patients. Furthermore, we also described a reduced frequency of HHA/HHB and an increased frequency of HHC and HHG*2 haplotypes in African-derived patients, which could modify the CCR5 protein expression in specific cell subsets.

Association of Toll-Like Receptor 7 (TLR7) Polymorphisms with Predisposition to Systemic Lupus Erythematosus (SLE): A Meta and Trial Sequential Analysis

Systemic Lupus Erythematosus (SLE) is an autoimmune disorder characterized by autoantibody production and organ involvement. The role of toll-like receptor-7 in SLE is well established. Although genetic variations in the TLR-7 gene have been associated with an increased risk of developing SLE, the findings are not consistent. We performed a meta-analysis of previously published articles on four important single nucleotide polymorphisms in the TLR-7 gene (rs3853839, rs179008, rs179019, and rs179010) to reach a valid conclusion. Various literature databases, including PubMed, Science Direct, and Scopus, were scoured for eligible reports until May 10, 2023. GPower software v.3 was used to assess the power of individual reports included in the meta-analysis. Comprehensive Meta-analysis v3 software was used to perform all statistics. The publication biases in each genetic comparison model were investigated using funnel plots and Egger's regression test. To test heterogeneity, Cochrane Q statistics, probability value and I2 were used. Considering the predefined inclusion and exclusion criteria, the current study included a total of 10 eligible studies that included 15,472 SLE cases and 16,721 healthy controls. The meta-analysis revealed a significant association between TLR7 polymorphisms (rs179019 and rs179010) and susceptibility to SLE development. Other TLR7 polymorphisms (rs3853839 and rs179008), on the other hand, showed no significant association. Furthermore, the trial sequential analysis identified the need for additional case control studies for TLR-7 polymorphisms (rs3853839, rs179008, and rs179019) other than the rs179010 polymorphism. TLR7 variants for rs179010 and rs179019 are risk factor for the development of SLE. Further investigations are required to reach a valid conclusion.

Type I Interferons in Autoimmunity: Implications in Clinical Phenotypes and Treatment Response

Type I interferon (IFN-I) is thought to play a role in many systemic autoimmune diseases. IFN-I pathway activation is associated with pathogenic features, including the presence of autoantibodies and clinical phenotypes such as more severe disease with increased disease activity and damage. We will review the role and potential drivers of IFN-I dysregulation in 5 prototypic autoimmune diseases: systemic lupus erythematosus, dermatomyositis, rheumatoid arthritis, primary Sjögren syndrome, and systemic sclerosis. We will also discuss current therapeutic strategies that directly or indirectly target the IFN-I system.

B cell-intrinsic TLR7 expression drives severe lupus in TLR9-deficient mice

The endosomal Toll-like receptor 7 (TLR7) is a major driver of murine and human systemic lupus erythematosus (SLE). The role of TLR7 in lupus pathogenesis is enhanced when the regulatory role of TLR9 is absent. TLR7 signaling in plasmacytoid DCs (pDC) is generally thought to be a major driver of the IFN response and disease pathology; however, the cell types in which TLR7 acts to mediate disease have not been distinguished. To address this, we selectively deleted TLR7 in either CD11c+ cells or CD19+ cells; using a TLR7-floxed allele, we created on the lupus-prone MRL/lpr background, along with a BM chimera strategy. Unexpectedly, TLR7 deficiency in CD11c+ cells had no impact on disease, while TLR7 deficiency in CD19+ B cells yielded mild suppression of proteinuria and a trend toward reduced glomerular disease. However, in TLR9-deficient MRL/lpr mice with accelerated SLE, B cell-specific TLR7 deficiency greatly improved disease. These results support revision of the mechanism by which TLR7 drives lupus and highlight a cis regulatory interaction between the protective TLR9 and the pathogenic TLR7 within the B cell compartment. They suggest B cell-directed, dual TLR7 antagonism/TLR9 agonism or dual TLR7/9 antagonism as a potential future therapeutic strategy to treat SLE.

Aberrant B Cell Signaling in Autoimmune Diseases

Aberrant B cell signaling plays a critical in role in various systemic and organ-specific autoimmune diseases. This is supported by genetic evidence by many functional studies in B cells from patients or specific animal models and by the observed efficacy of small-molecule inhibitors. In this review, we first discuss key signal transduction pathways downstream of the B cell receptor (BCR) that ensure that autoreactive B cells are removed from the repertoire or functionally silenced. We provide an overview of aberrant BCR signaling that is associated with inappropriate B cell repertoire selection and activation or survival of peripheral B cell populations and plasma cells, finally leading to autoantibody formation. Next to BCR signaling, abnormalities in other signal transduction pathways have been implicated in autoimmune disease. These include reduced activity of several phosphates that are downstream of co-inhibitory receptors on B cells and increased levels of BAFF and APRIL, which support survival of B cells and plasma cells. Importantly, pathogenic synergy of the BCR and Toll-like receptors (TLR), which can be activated by endogenous ligands, such as self-nucleic acids, has been shown to enhance autoimmunity. Finally, we will briefly discuss therapeutic strategies for autoimmune disease based on interfering with signal transduction in B cells.

Development of High Fat Diet-Induced Hyperinsulinemia in Mice Is Enhanced by Co-treatment With a TLR7 Agonist

Metabolic syndrome (MetS) is common in Systemic Lupus Erythematosus (SLE) patients and is associated with increased cardio-renal risk. Toll-like receptor 7 (TLR7) stimulation promotes the development of SLE through mechanisms including activating type I Interferon (IFN) and autoreactive B cells. The current study tested whether combined TLR7 agonist treatment and exposure to a high fat, high sucrose “Western diet” intervention affects the early-stage development of SLE or MetS features. Female C57BL/6 mice were untreated or treated with the TLR7 agonist imiquimod (IMQ) and fed a high-fat diet (HFD; fat 42% kcal, sucrose 34% kcal) or control diet (fat 12.6% kcal, sucrose 34% kcal) for 6 weeks. Supporting early-stage induction of autoimmunity, spleen weights were significantly increased and anti-nuclear antibody (ANA) positivity was detected in IMQ-treated mice. Increased body weight, gonadal fat pad mass, and plasma leptin levels were observed between HFD and control animals for both IMQ and untreated mice. However, the increase in these parameters with HFD was slightly but significantly diminished in IMQ-treated mice. Both the HFD and IMQ treatments significantly increased fasting blood glucose levels. Notably, IMQ treatment affected fasting insulin concentrations in a diet-dependent manner, with hyperinsulinemia observed in IMQ-HFD treated mice. Together, this indicates that the IMQ model of SLE is associated with metabolic alterations, impaired glycemic control, and hyperinsulinemia under HFD conditions. This model may be helpful in further investigating the relationship between MetS and SLE, and supports a role of TLR7 signaling in promoting or accelerating the development of dysglycemia and hyperinsulinemia.

Association of X-linked TLR-7 gene polymorphism with the risk of knee osteoarthritis: a case-control study

Knee osteoarthritis (OA) is the most prevalent type of OA, and Toll-like receptor 7 (TLR7) may lead to the pathogenesis of OA. Recently, X-linked TLR7 polymorphism has been confirmed to be associated with arthritis. However, there is a lack of studies on TLR7 gene polymorphism associated with knee OA susceptibility. The current study aimed to determine whether TLR7 gene polymorphism is associated with the risk of knee OA. Genotyping of two polymorphic sites (rs3853839 and rs179010) in the TLR7 gene was performed in 252 OA patients, and 265 healthy controls using the SNaPshot sequencing technique. Data were analyzed statistically by Chi-square tests and logistic regression. Rs3853839-C allele showed frequencies of 28% and 27% in the healthy control and female knee OA groups, respectively. The differences were not statistically significant (P > 0.05). The rs3853839-CG genotype frequency was significantly lower in the female knee OA group as compared to the healthy control group (OR 0.60; 95%CI 0.36–0.99; P = 0.044). In the male hemizygote population, the rs3853839-CC showed significantly lower frequencies in the male knee OA group as compared to the healthy control group (OR 0.35; 95%CI 0.17–0.71; P = 0.0025). Regarding rs179010, there were no differences in the genotype distribution and allele frequencies between OA patients and healthy subjects under any models (P > 0.05). Stratified analysis showed that the frequency of the rs3853839-CG genotypes was lower in high Kellgren-Lawrence grades (KLG) (OR 0.48; 95%CI 0.21–1.08; P = 0.066), and significantly lower in OA patients with effusion synovitis (OR 0.38; 95%CI 0.17–0.88; P = 0.013). TLR7 rs3853839 polymorphism may play a role in the susceptibility of knee OA in the Chinese Han Population and may be associated with OA severity and the risk of effusion synovitis in Knee OA.

TLR7 gain-of-function genetic variation causes human lupus

Although circumstantial evidence supports enhanced Toll-like receptor 7 (TLR7) signalling as a mechanism of human systemic autoimmune disease1-7, evidence of lupus-causing TLR7 gene variants is lacking. Here we describe human systemic lupus erythematosus caused by a TLR7 gain-of-function variant. TLR7 is a sensor of viral RNA8,9 and binds to guanosine10-12. We identified a de novo, previously undescribed missense TLR7Y264H variant in a child with severe lupus and additional variants in other patients with lupus. The TLR7Y264H variant selectively increased sensing of guanosine and 2',3'-cGMP10-12, and was sufficient to cause lupus when introduced into mice. We show that enhanced TLR7 signalling drives aberrant survival of B cell receptor (BCR)-activated B cells, and in a cell-intrinsic manner, accumulation of CD11c+ age-associated B cells and germinal centre B cells. Follicular and extrafollicular helper T cells were also increased but these phenotypes were cell-extrinsic. Deficiency of MyD88 (an adaptor protein downstream of TLR7) rescued autoimmunity, aberrant B cell survival, and all cellular and serological phenotypes. Despite prominent spontaneous germinal-centre formation in Tlr7Y264H mice, autoimmunity was not ameliorated by germinal-centre deficiency, suggesting an extrafollicular origin of pathogenic B cells. We establish the importance of TLR7 and guanosine-containing self-ligands for human lupus pathogenesis, which paves the way for therapeutic TLR7 or MyD88 inhibition.

X marks the spot in autoimmunity

INTRODUCTION

Autoimmune diseases mostly affect females. Besides hormones, several factors related to chromosome X have been called in action to explain this sex predominance.

AREAS COVERED

This paper provides an overview on the role of chromosome X (chrX) in explaining why females have higher susceptibility to autoimmunity. The work outlines some essential concepts regarding chrX inactivation, escape from chrX inactivation and the evolutionary history of chrX. In addition, we will discuss the concept of gene escape in immune cells, with examples related to specific X-linked genes and autoimmune diseases.

EXPERT OPINION

There is growing evidence that many genes present on chrX escape inactivation, and some of them have significant immune-mediated functions. In immune cells of female individuals the escape of these genes is not constant, but the knowledge of the mechanisms controlling this plasticity are not completely understood. Future studies aimed at the characterization of these modifications at single-cell resolution, together with conformational 3D studies of the inactive X chromosome, will hopefully help to fill this gap of knowledge.

Copy Number Variation and Frequency of rs179008 in TLR7 Gene Associated with Systemic Lupus Erythematosus in Two Mexican Populations

Systemic Lupus Erythematosus (SLE) is an autoimmune disease in which genetic factors play a role in the susceptibility to develop it. Genes related to the synthesis of interferons such as TLR7 and genetics factors such as single nucleotide polymorphisms (SNPs) or copies number variation (CNV) in the gene have been involved with the development of the disease. The genetic differences between the populations contribute to the complexity of LES. Mexico has a mestizo population with a genetic load of at least three origins: Amerindian, Caucasian, and African. The mestizo of Yucatán is the only group whose contribution Amerindian is mainly Mayan, geographically distant from other Mexican Amerindians. We analyzed the CNV and the frequency of SNP rs179008 of the TLR7 as genetic risk factors in developing the disease in patients from Yucatán and Central Mexico. Results show that 14% of the cases of the Yucatecan population showed significantly >2 CNV and a higher risk of developing the disease (OR: 34.364), concerning 4% of those coming from Central Mexico (OR: 10.855). T allele and the A/T and T/T risk genotypes of rs179008 were more frequent in patients of Central Mexico than in those of Yucatán (50% vs. 30%, 93% vs. 30%, 4% vs. 1%), and association with susceptibility to develop SLE was observed (OR: 1.5 vs. 0.58, 9.54 vs. 0.66, 12 vs. 0.14). Data support the genetic differences between and within Mexican mestizo populations and the role of the TLR7 in the pathogenesis of SLE.

Targeting Toll-like Receptor (TLR) Pathways in Inflammatory Arthritis: Two Better Than One?

Inflammatory arthritis is a cluster of diseases caused by unregulated activity of the immune system. The lost homeostasis is followed by the immune attack of one’s self, what damages healthy cells and tissues and leads to chronic inflammation of various tissues and organs (e.g., joints, lungs, heart, eyes). Different medications to control the excessive immune response are in use, however, drug resistances, flare-reactions and adverse effects to the current therapies are common in the affected patients. Thus, it is essential to broaden the spectrum of alternative treatments and to develop disease-modifying drugs. In the last 20 years, the involvement of the innate immune receptors TLRs in inflammatory arthritis has been widely investigated and targeting either the receptor itself or the proteins in the downstream signalling cascades has emerged as a promising therapeutic strategy. Yet, concerns about the use of pharmacological agents that inhibit TLR activity and may leave the host unprotected against invading pathogens and toxicity issues amid inhibition of downstream kinases crucial in various cellular functions have arisen. This review summarizes the existing knowledge on the role of TLRs in inflammatory arthritis; in addition, the likely druggable related targets and the developed inhibitors, and discusses the pros and cons of their potential clinical use.

Impact of TLR7 and TLR9 polymorphisms on susceptibility to placental infections and pregnancy complications

This study evaluated the impact of the TLR7 Gln11Leu (rs179008) and TLR9 -1237 T/C (rs5743836) single nucleotide polymorphisms (SNPs) on susceptibility to placental infections and pregnancy complications in 455 Brazilian women. Demographic, socioeconomic, gynecological, and clinical characteristics of the women were collected. Placental tissues were sampled from pregnant women and human and viral DNA was extracted. Human alphaherpesvirus 1 (Herpes simplex virus type 1, HSV-1), Human alphaherpesvirus 2 (Herpes simplex virus type 2, HSV-2) and Human betaherpesvirus 5 (Human cytomegalovirus, HCMV) were detected by nested PCR. TLR9 and TLR7 SNPs were genotyped by PCR amplification of bi-directional specific alleles (Bi-PASA) and restriction fragment length polymorphism (RFLP), respectively. Infections at the time of birth were detected in 45.71 % of women. The presence of the TT genotype (recessive model) of the TLR7 SNP was associated with increased susceptibility to HSV-1 infection (O.R. = 2.23, p = 0.05). The presence of the C allele of the TLR9 SNP, in heterozygosis or homozygosis (dominant model), decreased the infection risk by HCMV (O.R. = 0.31, p-mod<0.05). The TT genotype (recessive model) of the TLR7 SNP was significantly associated (p < 0.05) with increased occurrence of pre-treated hypertension. The codominant model of the TLR9 SNP was significantly associated (p < 0.05) with reduced risk of hospitalization during pregnancy. In combination, the AA/CT (TLR7-TLR9) genotypes significantly decreased the risk of placental infection by HSV-1 and/or HSV-2 (O.R. = 0.47, p = 0.02), the susceptibility to all infectious agents considered in combination (O.R. = 0.4, p = 0.00), and the need of hospitalization (O.R. = 0.48, p = 0.02). In conclusion, TLR7 and TLR9 SNPs are potential modulating factors for the risk of placental infections and pregnancy complications.

TLR4 and TLR9 polymorphisms are not associated with either rheumatoid arthritis or systemic lupus erythematosus in Mexican patients

Toll-like receptor (TLR)-mediated signaling pathways induce a proinflammatory microenvironment to eradicate pathogens. However, in rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE), TLRs can promote chronic inflammation. It has been shown that some TLR4 and TLR9 single nucleotide polymorphisms (SNPs) are risk factors for RA and SLE, but these findings have not been replicated in all populations; thus, results are inconclusive. We evaluated the TLR4 Asp299Gly, Thr399Ile, - 1892G/A SNPs, and the TLR9 Pro545Pro SNP to assess potential associations with RA and SLE in Mexican patients. This study included 474 patients with RA, 283 patients with SLE, and 424 healthy controls. We used a 5' nuclease allelic discrimination assay to genotype individuals for the four TLR4 and TLR9 polymorphisms. We found that the genotype or allelic frequencies of the TLR4 Asp299Gly, Thr399Ile, - 1892G/A, and TLR9 Pro545Pro polymorphisms were similar between patients and controls. We found no association under different genetic models. A haplotype analysis of TLR4 showed no association with either RA or SLE. We found no significant differences in the allelic or genotypic frequencies of TLR4 Asp299Gly, Thr399IIe, - 1892G/A, or TLR9 Pro545Pro between patients and controls. These findings suggested that these variants are not risk factors for RA or SLE in Mexican patients.

Germline Genetic Variants of Viral Entry and Innate Immunity May Influence Susceptibility to SARS-CoV-2 Infection: Toward a Polygenic Risk Score for Risk Stratification

The ongoing COVID-19 pandemic caused by the novel coronavirus, SARS-CoV-2 has affected all aspects of human society with a special focus on healthcare. Although older patients with preexisting chronic illnesses are more prone to develop severe complications, younger, healthy individuals might also exhibit serious manifestations. Previous studies directed to detect genetic susceptibility factors for earlier epidemics have provided evidence of certain protective variations. Following SARS-CoV-2 exposure, viral entry into cells followed by recognition and response by the innate immunity are key determinants of COVID-19 development. In the present review our aim was to conduct a thorough review of the literature on the role of single nucleotide polymorphisms (SNPs) as key agents affecting the viral entry of SARS-CoV-2 and innate immunity. Several SNPs within the scope of our approach were found to alter susceptibility to various bacterial and viral infections. Additionally, a multitude of studies confirmed genetic associations between the analyzed genes and autoimmune diseases, underlining the versatile immune consequences of these variants. Based on confirmed associations it is highly plausible that the SNPs affecting viral entry and innate immunity might confer altered susceptibility to SARS-CoV-2 infection and its complex clinical consequences. Anticipating several COVID-19 genomic susceptibility loci based on the ongoing genome wide association studies, our review also proposes that a well-established polygenic risk score would be able to clinically leverage the acquired knowledge.

Escape from X Chromosome Inactivation and the Female Predominance in Autoimmune Diseases

Women represent 80% of people affected by autoimmune diseases. Although, many studies have demonstrated a role for sex hormone receptor signaling, particularly estrogens, in the direct regulation of innate and adaptive components of the immune system, recent data suggest that female sex hormones are not the only cause of the female predisposition to autoimmunity. Besides sex steroid hormones, growing evidence points towards the role of X-linked genetic factors. In female mammals, one of the two X chromosomes is randomly inactivated during embryonic development, resulting in a cellular mosaicism, where about one-half of the cells in a given tissue express either the maternal X chromosome or the paternal one. X chromosome inactivation (XCI) is however not complete and 15 to 23% of genes from the inactive X chromosome (Xi) escape XCI, thereby contributing to the emergence of a female-specific heterogeneous population of cells with bi-allelic expression of some X-linked genes. Although the direct contribution of this genetic mechanism in the female susceptibility to autoimmunity still remains to be established, the cellular mosaicism resulting from XCI escape is likely to create a unique functional plasticity within female immune cells. Here, we review recent findings identifying key immune related genes that escape XCI and the relationship between gene dosage imbalance and functional responsiveness in female cells.

Inflammasomes in Common Immune-Related Skin Diseases

The inflammasome is an important protein complex that cleaves the proinflammatory cytokines pro-IL-1β and pro-IL-18 into their active forms. Owing to its critical role in eliciting innate immune responses, IL-1β has been suggested to contribute to various skin diseases, including psoriasis, vitiligo, systemic lupus erythematosus (SLE), and atopic dermatitis (AD). Recently, several types of activators and inhibitors of different inflammasomes, as well as inflammasome-related genes and genetic susceptibility loci, have been identified in these immune-related common skin diseases. In particular, inflammasome activators and inhibitors presented highly cell-type-specific activity, suggesting that the inflammasome might perform different functions in different cell types. Moreover, most of these findings were based on experimental disease models, and the clinical features of the models partly resemble the typical symptoms of the diseases. In this review, from the perspective of activators and inhibitors, we collected evidence from the widely-studied inflammasomes, NLRP3, AIM2, and NLRP1, in psoriasis, vitiligo, SLE, and AD. Importantly, some small-molecule inhibitors hold therapeutic promise for the treatment of these diseases.

Glycoprotein 96 polymorphisms are associated with the risk of systemic lupus erythematosus: A case-control study

AIM

To investigate the clinical implications of a genetic polymorphism in glycoprotein 96 (GP96), by analyzing the association between the genotype and haplotype of GP96 with systemic lupus erythematosus (SLE).

METHOD

We analyzed cell-surface expression of GP96 in peripheral blood mononuclear cells (PBMCs) and serum titer of anti-GP96 antibody of SLE patients. Single nucleotide polymorphisms and deletion mutants of GP96 were detected by two-dimensional gene scanning (TDGS). Odds ratios with 95% confidence intervals (CI) were determined for each genotype and haplotype through the chi-square test.

RESULTS

In total, 216 Korean SLE patients and 215 age- and sex-matched healthy controls were enrolled. In SLE patients, as opposed to healthy controls, cell-surface expression of GP96 among human leukocyte antigen-DR+ PBMCs (76.4% vs 45.5%, respectively, P < 0.001) and serum anti-GP96 antibody titers (0.98 vs 0.50, respectively, P = 0.012) increased. TDGS revealed six polymorphic sites in GP96, two of which were significantly associated with SLE (exon 1, g.-7C>G, odds ratio [OR] 1.78, 95% CI 1.16-2.75, P = 0.009; exon 17, g.17009_17011del, OR 1.76, 95% CI 1.18-2.64, P = 0.006). Two haplotypes (121111, 211212) were strongly associated with SLE (OR 8.92, 95% CI 1.10-72.6, P = 0.041; OR 3.03, 95% CI 1.22-7.50, P = 0.017, respectively) and specific clinical manifestations (discoid rash, arthritis, renal disorder, neurologic disorder, and hematologic disorder). Haplotype-based analysis revealed a stronger association between GP96 and SLE than did genotype-based analysis.

CONCLUSION

The two polymorphisms, each in exons 1 and 17 of GP96 are potential genetic risk factors of SLE. Two haplotypes 121111 and 211212 are related to not only SLE but also specific clinical manifestations.

From autoinflammation to autoimmunity: old and recent findings

Autoimmune diseases and autoinflammatory diseases have a number of similar etiopathogenetic and clinical characteristics, including genetic predisposition and recurrent systemic inflammatory flares. The first phase of ADs involves innate immunity: by means of TLRs, autoantigen presentation, B and T cell recruitment and autoantibody synthesis. The second phase involves adaptive immunity, a self-sustaining process in which immune complexes containing nucleic acids and autoantibodies activate self-directed inflammation. The link between autoimmunity and autoinflammation is IL-1ß, which is crucial in connecting the innate immune response due to NLR activation and the adaptive immune responses of T and B cells. In conclusion, although ADs are still considered adaptive immunity-mediated disorders, there is increasing evidence that innate immunity and inflammasomes are also involved. The aim of this review is to highlight the link between the innate and adaptive immune mechanisms involved in autoimmune diseases.

Association between TLR9 rs5743836 polymorphism and risk of recurrent venous thromboembolism

Recent gene knockout studies on mice have shown the role of toll-like receptor 9 (TLR9) in resolution of venous thromboembolism (VTE) through sterile inflammation. However, the role of a putative functional TLR9 polymorphism (rs5743836) in risk assessment of VTE recurrence remains unknown. The aim of our study was to investigate the TLR9 rs5743836 polymorphism in VTE patients and its association with the risk of VTE recurrence. We analyzed TLR9 rs5743836 polymorphism in Malmö thrombophilia study patients; a prospective follow-up study of 1465 VTE patients by Taqman PCR. From a total of 1465 VTE patients, those who had VTE before inclusion and those who died or had VTE recurrence during anticoagulant treatment were excluded (n = 415). Cox regression analyses were performed on the remaining 1050 VTE patients, including 126 (12.5%) patients that had recurrent VTE during follow-up period. TLR9 polymorphism was significantly associated with higher risk of VTE recurrence in female patients (HR 3.46, 95% CI 1.06–11.33) independent of acquired risk factors for VTE, family history, risk of thrombophilia and deep vein thrombosis (DVT) location. Similarly, in unprovoked VTE patients, TLR9 polymorphism was significantly associated with higher risk of VTE recurrence in female patients (HR 5.94, 95% CI 1.25–28.13) after adjusting for family history, risk of thrombophilia and DVT location. No association between TLR9 polymorphism and risk of VTE recurrence was found in male patients. Our results suggest that TLR9 rs5743836 polymorphism is an independent risk factor for VTE recurrence in female patients but not in males.

Associations between PTPN22 and TLR9 polymorphisms and systemic lupus erythematosus: a comprehensive meta-analysis

Previous studies have explored the relationship of PTPN22 and TLR9 polymorphisms with systemic lupus erythematosus (SLE). In consideration of the population stratification, conflicting results and updating data, we conducted a comprehensive meta-analysis, which consists of a total of 17 research articles (9120 cases and 11,724 controls) for PTPN22 and 20 articles (including up to 2808 cases and 3386 controls) for TLR9. Significant association was verified between PTPN22 rs2476601 and SLE in the overall population (OR = 1.511 per T allele, 95% CI 1.338-1.706, P = 2.931 × 10^-11) and under dominant model of T allele (TT+CT vs. CC: OR = 1.531, 95% CI 1.346-1.742, P = 9.17 × 10^-11). Analysis after stratification by ethnicity indicated that PTPN22 rs2476601 was related to SLE in Americans (OR = 2.566, 95% CI 1.796-3.665, P = 2.219 × 10^-7), Europeans (OR = 1.399, 95% CI 1.261-1.552, P = 2.153 × 10^-10), and Africans (OR = 4.14, 95% CI 1.753-9.775, P = 1.0 × 10^-3). We did not observe any association between TLR9 polymorphisms (rs187084, rs352140, rs5743836 and rs352139) and SLE under any model, after excluding the data that were inconsistent with Hardy-Weinberg equilibrium (HWE). In summary, PTPN22 rs2476601 was significantly interrelated with SLE and contributed to susceptibility and development of SLE in Americans, Europeans and Africans in this analysis, while their relationship needs to be validated in Africans by future research.

Cellular and Molecular Mechanisms of Autoimmunity and Lupus Nephritis

Autoimmunity involves immune responses directed against self, which are a result of defective self/foreign distinction of the immune system, leading to proliferation of self-reactive lymphocytes, and is characterized by systemic, as well as tissue-specific, inflammation. Numerous mechanisms operate to ensure the immune tolerance to self-antigens. However, monogenetic defects or genetic variants that weaken immune tolerance render susceptibility to the loss of immune tolerance, which is further triggered by environmental factors. In this review, we discuss the phenomenon of immune tolerance, genetic and environmental factors that influence the immune tolerance, factors that induce autoimmunity such as epigenetic and transcription factors, neutrophil extracellular trap formation, extracellular vesicles, ion channels, and lipid mediators, as well as costimulatory or coinhibitory molecules that contribute to an autoimmune response. Further, we discuss the cellular and molecular mechanisms of autoimmune tissue injury and inflammation during systemic lupus erythematosus and lupus nephritis.

Kruppel-like factor4 regulates PRDM1 expression through binding to an autoimmune risk allele

A SNP identified as rs548234, which is found in PRDM1, the gene that encodes BLIMP1, is a risk allele associated with systemic lupus erythematosus (SLE). BLIMP1 expression was reported to be decreased in women with the PRDM1 rs548234 risk allele compared with women with the nonrisk allele in monocyte-derived DCs (MO-DCs). In this study, we demonstrate that BLIMP1 expression is regulated by the binding of Kruppel-like factor 4 (KLF4) to the risk SNP. KLF4 is highly expressed in MO-DCs but undetectable in B cells, consistent with the lack of altered expression of BLIMP1 in B cells from risk SNP carriers. Female rs548234 risk allele carriers, but not nonrisk allele carriers, exhibited decreased levels of BLIMP1 in MO-DCs, showing that the regulatory function of KLF4 is influenced by the risk allele. In addition, KLF4 directly recruits histone deacetylases (HDAC4, HDAC6, and HDAC7), established negative regulators of gene expression. Finally, the knock down of KLF4 expression reversed the inhibitory effects of the risk SNP on promoter activity and BLIMP1 expression. Therefore, the binding of KLF4 and the subsequent recruitment of HDACs represent a mechanism for reduced BLIMP1 expression in MO-DCs bearing the SLE risk allele rs548234.

Endosomal toll-like receptor gene polymorphisms and susceptibility to HIV and HCV co-infection - Differential influence in individuals with distinct ethnic background

The genetic background of human populations can influence the susceptibility and outcome of infection diseases. Toll-like receptors (TLRs) have been previously associated with susceptibility to human immunodeficiency virus (HIV) infection, disease progression and hepatitis C, virus (HCV) co-infection in different populations, although mostly in Europeans. In this study, we investigated the genetic role of endosomal TLRs on susceptibility to HIV infection and HCV co-infection through the analysis of TLR7 rs179008, TLR8 rs3764880, TLR9 rs5743836 and TLR9 rs352140 polymorphisms in 789 Brazilian individuals (374 HIV+ and 415 HIV-), taking into account their ethnic background. Amongst the 357 HIV+ individuals with available data concerning HCV infection, 98 were positive. In European descendants, the TLR9 rs5743836 C carriers displayed a higher susceptibility to HIV infection [dominant, Odds Ratio (OR)=1.53; 95% CI: 1.05-2.23; P=0.027]. In African descendants, TLR9 rs5743836 CT genotype was associated with protection to HIV infection (codominant, OR=0.51; 95% CI: 0.30-0.87; P=0.013). Also, the TLR9 rs352140 AA variant genotype was associated with susceptibility to HIV+/HCV+ co-infection in African descendants (recessive, OR=2.92; 95% CI: 1.22-6.98, P=0.016). These results are discussed in the context of the different ethnic background of the studied individuals highlighting the influence of this genetic/ethnic background on the susceptibility to HIV infection and HIV/HCV co-infection in Brazilian individuals.

Previously Unidentified Single Nucleotide Polymorphisms in HIV/AIDS Cases Associate with Clinical Parameters and Disease Progression

The genetic background of an individual plays an important role in the progression of HIV infection to AIDS. Identifying previously unknown or uncharacterized single nucleotide polymorphisms (SNPs) that associate with disease progression may reveal important therapeutic targets and provide a greater understanding of disease pathogenesis. In the present study, we employed ultra-high multiplex PCR on an Ion Torrent next-generation sequencing platform to sequence 23 innate immune genes from 94 individuals with HIV/AIDS. This data was used to identify potential associations of SNPs with clinical parameters and disease progression. SNPs that associated with an increased viral load were identified in the genes for the interleukin 15 receptor (IL15RA), toll-like receptor 7 (TLR7), tripartite motif-containing protein 5 (TRIM5), and two killer-cell immunoglobulin-like receptors (KIR2DL1 and KIR2DL3). Additionally, SNPs that associated with progression from HIV infection to AIDS were identified in two 2'-5'-oligoadenylate synthetase genes (OAS2 and OAS3). In contrast, other SNPs identified in OAS2 and OAS3 genes, as well as in the TRIM5 and KIR2DS4 genes, were associated with a slower progression of disease. Taken together, our data demonstrates the utility of ultra-high multiplex PCR in identifying polymorphisms of potential clinical significance and further,identifies SNPs that may play a role in HIV pathogenesis.

A meta-analysis of public microarray data identifies gene regulatory pathways deregulated in peripheral blood mononuclear cells from individuals with Systemic Lupus Erythematosus compared to those without

BACKGROUND

Systemic Lupus Erythematosus (SLE) is a complex, multi-systemic, autoimmune disease for which the underlying aetiological mechanisms are poorly understood. The genetic and molecular processes underlying lupus have been extensively investigated using a variety of -omics approaches, including genome-wide association studies, candidate gene studies and microarray experiments of differential gene expression in lupus samples compared to controls.

METHODS

This study analyses a combination of existing microarray data sets to identify differentially regulated genetic pathways that are dysregulated in human peripheral blood mononuclear cells from SLE patients compared to unaffected controls. Two statistical approaches, quantile discretisation and scaling, are used to combine publicly available expression microarray datasets and perform a meta-analysis of differentially expressed genes.

RESULTS

Differentially expressed genes implicated in interferon signaling were identified by the meta-analysis, in agreement with the findings of the individual studies that generated the datasets used. In contrast to the individual studies, however, the meta-analysis and subsequent pathway analysis additionally highlighted TLR signaling, oxidative phosphorylation and diapedesis and adhesion regulatory networks as being differentially regulated in peripheral blood mononuclear cells (PBMCs) from SLE patients compared to controls.

CONCLUSION

Our analysis demonstrates that it is possible to derive additional information from publicly available expression data using meta-analysis techniques, which is particularly relevant to research into rare diseases where sample numbers can be limiting.

Shaping the spectrum - From autoinflammation to autoimmunity

Historically, autoimmune-inflammatory disorders were subdivided into autoinflammatory vs. autoimmune diseases. About a decade ago, an immunological continuum was proposed, placing "classical" autoinflammatory disorders, characterized by systemic inflammation in the absence of high-titer autoantibodies or autoreactive T lymphocytes, at the one end, and autoimmune disorders at the other end. We provide an overview of recent developments and observations, filling in some of the gaps and showing strong interconnections between innate and adaptive immune mechanisms, indicating that disorders from both ends of the immunological spectrum indeed share key pathomechanisms. We focus on three exemplary disorders: i) systemic juvenile idiopathic arthritis representing "classical" autoinflammatory disorders; ii) psoriasis, a mixed pattern disease; and iii) systemic lupus erythematosus, a prototypical autoimmune disease. We summarize scientific observations suggesting that, depending on disease stages and/or duration, individualized treatment targeting innate or adaptive immune mechanisms in disorders from either end of the immunological spectrum may control disease activity.

Genotypic distribution of common variants of endosomal toll like receptors in healthy Spanish women. A comparative study with other populations

Genetic variants of endosomal toll like receptors (TLR) have been associated with many infectious, autoimmune and inflammatory diseases, but few studies have been reported in the Spanish population. The aim of this study was to describe the allelic and genotypic distributions of some common nucleotide substitutions of endosomal TLRs in healthy Spanish women and to compare them with those already published in other population groups. Nine substitutions were analysed in 150 DNA samples from 150 Spanish, non-related healthy females: TLR3 rs3775291 and rs5743305; TLR7 rs179008 and rs5743781; TLR8 rs3764880 and TLR9 rs187084, rs5743836, rs352139 and rs352140. Genotyping was carried out by real time PCR and melting curve analysis in a LightCycler 480. A systematic review was performed in order to compare the genotypic distributions in our cohort with those previously published in other population groups. The comparative study was performed with the two tailed Fisher's test or the Yates continuity correction for the Chi-square test when appropriate. No homozygotes for rs5743781 in TLR7 were found, and rs352139 and rs352140 of TLR9 were in strong linkage disequilibrium. Genotype distributions in endosomal TLR are similar to other Spanish series previously reported. As expected, most differences were found when comparing our distributions with Asiatics, but differences were also found with other Caucasian populations. Since there are significant variations in genotypic distributions of TLRs in both interracial groups and within the same ethnic group, to carry out studies of disease susceptibility in more restricted groups is mandatory.

Breakdown of Immune Tolerance in Systemic Lupus Erythematosus by Dendritic Cells

Dendritic cells (DC) play an important role in the pathogenesis of systemic lupus erythematosus (SLE), an autoimmune disease with multiple tissue manifestations. In this review, we summarize recent studies on the roles of conventional DC and plasmacytoid DC in the development of both murine lupus and human SLE. In the past decade, studies using selective DC depletions have demonstrated critical roles of DC in lupus progression. Comprehensive in vitro and in vivo studies suggest activation of DC by self-antigens in lupus pathogenesis, followed by breakdown of immune tolerance to self. Potential treatment strategies targeting DC have been developed. However, many questions remain regarding the mechanisms by which DC modulate lupus pathogenesis that require further investigations.

Association between toll-like receptor polymorphisms and systemic lupus erythematosus: a meta-analysis update

OBJECTIVE

The aim of this study was to determine whether polymorphisms of the Toll-like receptor (TLR) genes are associated with susceptibility to systemic lupus erythematosus (SLE).

METHODS

The authors conducted a meta-analysis of the relationship between 12 TLR polymorphisms and SLE susceptibility.

RESULTS

In total, 26 studies that involved 11,984 patients and 14,572 controls were included in the meta-analysis. The meta-analysis showed no association between the two alleles of the rs352140, rs5743836, and rs352139 polymorphisms of TLR9 and SLE, but indicated an association between the two alleles of the rs187084 polymorphism (TLR9) and SLE in the overall population (OR = 0.869, 95% CI = 0.762-0.992, P = 0.038). No association was detected between rs3764880 (TLR8) and SLE; however, our meta-analysis indicated an association between rs3764879 (TLR8) and SLE in Caucasians (OR = 1.414, 95% CI = 1.139-1.756, P = 0.002). An association between rs179008 (TLR7) and SLE was found in the African (OR = 0.430, 95% CI = 0.238-0.775, P = 0.005), but not in the Caucasian population (OR = 1.206, 95% CI = 0.932-1.614, P = 0.145). Furthermore, our meta-analysis indicated a significant association between rs3853839 (TLR7) and SLE in the Asian population (OR = 0.773, 95% CI = 0.735, 0.823, P < 1.0 × 10(-9)). No associations were found between rs5744168 (TLR5), rs4986791 (TLR4), rs4986790 (TLR4), and rs3775291 (TLR3) polymorphisms and SLE susceptibility.

CONCLUSIONS

Our meta-analysis suggests that TLR7, TLR8, and TLR9 polymorphisms are associated with the development of SLE in Caucasian, Asian, and African populations.

TLR9 polymorphisms and systemic lupus erythematosus risk: an update meta-analysis study

It has been reported that the Toll-like receptor 9 (TLR9) gene polymorphisms may be associated with systemic lupus erythematosus (SLE) risk. However, some studies yielded conflicting results. Therefore, a comprehensive meta-analysis was performed to assess the precise association between TLR9 polymorphisms and SLE susceptibility. We performed a systematic search in PubMed, Embase (Ovid), China National Knowledge Internet, and Wanfang databases up to July 15, 2015. Odds ratio (OR) and 95 % confidence interval (CI) were used to pool the effect size. Statistical analyses were performed with STATA 11.0 software. In total, 21 studies from nineteen articles with 10,273 subjects were included in this meta-analysis. The overall results suggested that there was a statistically significant association between TLR9 rs187084 polymorphism and SLE risk observed in recessive model (TT vs. TC + CC: OR 1.17, 95 % CI 1.05-1.30, P = 0.005), codominant model (TT vs. CC: OR 1.22, 95 % CI 1.03-1.43, P = 0.019), and allele model (T vs. C: OR 1.15, 95 % CI 1.02-1.30, P = 0.020) in Asians. However, we found that there may be no significant association between the other three TLR9 polymorphisms and SLE risk in either Asians or non-Asians. In conclusion, the meta-analysis results suggested that TLR9 rs187084 polymorphism may increase the risk of SLE in Asians. However, no significant association between TLR9 SNPs (rs352139, rs352140, and rs5743836) and SLE risk was identified.

Single nucleotide polymorphisms of toll-like receptor 7 in hepatitis C virus infection patients from a high-risk chinese population

Hepatitis C virus (HCV) infection varies in the outcomes depending on both viral and host factors. This study aims to investigate the associations of three single nucleotide polymorphisms (SNPs) of Toll-like receptor 7 (TLR7), rs179016, rs5743733, and rs1634323, with susceptibility to HCV infection and clearance. The three SNPs were genotyped in a high-risk Chinese population, including 444 HCV spontaneous clearance cases, 732 persistent infection cases, and 1107 healthy controls. The G allele of rs1634323 was related to the protection from persistent infection among females (dominant model: odds ratio (OR) = 0.558, 95 % confidence interval (CI) = 0.348-0.894, P = 0.015). This protective effect was more evident in blood donation and HCV non-1 genotype-infected subgroups (all P < 0.05). The carriage of rs179016 C allele was more prone to develop persistent infection (OR = 1.444, 95 % CI = 1.096-1.903, P = 0.009) in males, and the risk effect remained significant among older (>50 years), hemodialysis (HD), and HCV-1 and HCV non-1 genotypes-infected subjects (all P < 0.05). Haplotype analyses showed that CCA haplotype among females was correlated with the elevated risk of HCV susceptibility while the carriage of GGA was more prone to be infected with HCV and CCA was more likely to develop persistent infection (all P < 0.05) among males. Our results first demonstrated that the carriage of rs179016 C allele had a negative effect on spontaneous clearance of HCV among males while rs1634323 G allele conferred a protective effect against persistent infection among female subjects.

Polymorphisms in Toll-like receptor genes are associated with vitiligo

Background: The members of Toll-like receptor (TLR) family are responsible for recognizing various molecular patterns associated with pathogens. Their expression is not confined to immune cells and have been detected in skin cells such as keratinocytes and melanocytes. As part of a generated response to pathogens, TLRs are involved in inducing inflammatory mediators to combat these threats. It is therefore not surprising that TLRs have been implicated in inflammatory skin diseases, including atopic dermatitis and psoriasis. Likewise, as key players in autoimmunity, they have been associated with a number of autoimmune diseases. Based on this, the role of TLRs in vitiligo could be suspected, but is yet to be clearly established.

Methods: In order to conduct a genetic association analysis, 30 SNPs were selected from TLR1-TLR8 and TLR10 regions to be genotyped in Estonian case-control cohort consisting of 139 vitiligo patients and 307 healthy control individuals. The patients were further analyzed in subgroups based on sex, age of onset, occurrence of vitiligo among relatives, extent of depigmented areas, vitiligo progression activity, appearance of Köbner's phenomenon, existence of halo naevi, and incidence of spontaneous repigmentation.

Results: The most notable finding came with SNP rs179020 situated in TLR7 gene, that was associated in entire vitiligo (Padj = 0.0065) and also several subgroup analyses. Other single marker and haplotype analyses pointed to TLR3, TLR4, and TLR10 genes.

Conclusions: This study investigated the genetic regions of nine TLR genes in relation to vitiligo susceptibility. The main results were the associations of TLR7 SNPs with vitiligo, while several other associations were obtained from the remaining TLR gene regions. This suggests that in addition to other inflammatory skin diseases, TLRs affect the development of vitiligo, thus making them interesting targets for future research.

Roles of B Cell-Intrinsic TLR Signals in Systemic Lupus Erythematosus

Toll-like receptors (TLRs) are a large family of pattern recognition receptors. TLR signals are involved in the pathogenesis of systemic lupus erythematosus. Mouse and human B cells constitutively express most TLRs. Many B cell subpopulations are highly responsive to certain TLR ligation, including B-1 B cells, transitional B cells, marginal zone B cells, germinal center B cell and memory B cells. The B cell-intrinsic TLR signals play critical roles during lupus process. In this review, roles of B cell-intrinsic TLR2, 4, 7, 8 and 9 signals are discussed during lupus pathogenesis in both mouse model and patients. Moreover, mechanisms underlying TLR ligation-triggered B cell activation and signaling pathways are highlighted.

Inflammasomes and human autoimmunity: A comprehensive review

Inflammasomes are multi-protein complexes composed of a NOD-like receptor (NLR)/an AIM-like receptor (ALR), the adapter molecule apoptosis-associated speck-like protein that contains a CARD (ASC), and caspase-1. Active caspase-1 cleaves pro-IL-1β and pro-IL-18 to IL-1β and IL-18, resulting in inflammation. Genetic mutations in inflammasomes were first recognized to result in autoinflammatory diseases, which are characterized by the absence of both autoantibodies and autoreactive-T/B cells. However, there is increasing attention being placed on genetic polymorphisms that are involved in the components of inflammasomes, and these have implications for innate immunity and the natural history of autoimmune diseases. For example, while the NOD-like receptor family, pyrin domain containing 1 (NLRP1) haplotypes contributes to susceptibility to developing vitiligo; there are other single nucleotide polymorphisms (SNPs) that alters the susceptibility and severity of rheumatoid arthritis (RA) and juvenile idiopathic arthritis. Indeed, there are multiple factors that contribute to lowering the threshold of immunity and inflammasomes play a key role in this threshold. For example, IL-1β and IL-18 further perpetuate Th17 responses and endothelial cell damage, which potentiate a number of autoimmune diseases, including synovitis in RA, cardiovascular disease, and systemic lupus erythematosus (SLE). There is also increasing data on the role of innate immunity in experimental autoimmune encephalomyelitis (EAE), in lupus nephritis, and in a variety of autoimmune pathologies in which activation of the innate immune system is the driver for the adaptive system. Indeed, it is likely that the chronic pathology of autoimmunity is mediated in part by otherwise innocent bystander cells, augmented by inflammasomes.

Is there association between TLR9 polymorphism and SLE susceptibility?

After reading the article "Susceptibility to SLE in South Indian Tamils may be influenced by genetic selection pressure on TLR2 and TLR9 genes", we have some doubt. As the differences existed in genetic risk factors, SLE symptoms, and disease severity between the childhood-onset and adult-onset SLE patients, the association analyses in study population including both childhood-onset and adult-onset SLE patients might be inappropriate. Besides, in order to explore whether TLR9 (-1237C/T) polymorphism impact SLE occurrence, we reviewed current studies and conducted a meta-analysis. The results of meta-analysis showed no significant correlation between TLR9 (-1237C/T) and SLE susceptibility in total population (allele model OR=0.97, 95%CI (0.81-1.14)), or in Caucasians (allele model OR=1.05, 95%CI (0.72-1.39)) and in Asians (allele model OR=0.94, 95%CI (0.54-1.35)). Therefore, confirmative evidence reveals that TLR9 (-1237C/T) polymorphism does not correlate with SLE susceptibility.

Toll-like receptors in systemic lupus erythematosus: potential for personalized treatment

Systemic lupus erythematosus (SLE) is a complex autoimmune disease characterized by the loss of tolerance to self-nuclear antigens. The symptoms of SLE, progression of pathology and the array of autoantibodies present in the serum differ significantly from patient to patient, which calls for a personalized approach to treatment. SLE is polygenic and strongly influenced by gender, ethnicity, and environmental factors. Data from genome-wide association studies suggests that polymorphisms in as many as 100 genes contribute to SLE susceptibility. Recent research has focused on genes associated with Toll-like receptors (TLRs), type I interferons, immune regulation pathways, and immune-complex clearance. TLR7 and TLR9 have been extensively studied using lupus-prone mouse models. In multiple systems overexpression of TLR7 drives disease progression but interestingly, a loss of TLR9 results in an almost identical phenotype. While TLR7 overexpression has been linked to human SLE, the possible role of TLR9 in human disease remains elusive. In the present review, we focus on TLR polymorphisms and TLR expression in SLE patients and discuss their potential as biomarkers for individualized treatment.

Susceptibility to SLE in South Indian Tamils may be influenced by genetic selection pressure on TLR2 and TLR9 genes

INTRODUCTION

Systemic lupus erythematosus (SLE) is a multisystem autoimmune disorder with complex etiology. Genetics plays an important role in lupus pathogenesis through its influence on clinical and autoantibody phenotype of the disease. Toll like receptors (TLR) recognize molecular patterns of pathogens and activate the innate immune system. Their ability to identify nucleic acids makes them suitable candidates for investigation of their role in lupus pathogenesis. Hence, this study was carried out to analyze the G to A and C to T transitions in TLR2 and TLR9 genes respectively and to test their association with lupus susceptibility, clinical and autoantibody phenotypes in South Indian Tamils.

METHOD

Three hundred SLE patients fulfilling ACR 2012 criteria for SLE and 460 age, sex similar, ethnicity matched controls were recruited as cases and controls. TLR2 (R753Q) and TLR9 (-1237C/T) polymorphisms were analyzed by real time PCR.

RESULTS

The TLR2 gene remained monomorphic in patients and controls, the frequency of the homozygous wild type allele being 100% and 99.6% respectively. Hence, it did not confer susceptibility to SLE. The more frequent T allele of TLR9 gene conferred a significant risk to develop SLE (p=0.011, OR 1.69, 95% CI 1.1-2.6). Both the polymorphisms did not influence clinical or autoantibody phenotype of the disease.

CONCLUSION

Prevailing endemic infections in the Indian subcontinent may have exerted a selection pressure resulting in TLR2 gene remaining monomorphic and the TLR9 adapting to a mutation for its increased expression. These may have an additive effect in the presence of other genetic and environmental risk factors to confer susceptibility to SLE in South Indian Tamils.

Immune sensing of nucleic acids in inflammatory skin diseases

Endosomal and cytosolic nucleic acid receptors are important immune sensors required for the detection of infecting or replicating viruses. The intracellular location of these receptors allows viral recognition and, at the same time, avoids unnecessary immune activation to self-nucleic acids that are continuously released by dying host cells. Recent evidence, however, indicates that endogenous factors such as anti-microbial peptides have the ability to break this protective mechanism. Here, we discuss these factors and illustrate how they drive inflammatory responses by promoting immune recognition of self-nucleic acids in skin wounds and inflammatory skin diseases such as psoriasis and lupus.

A polymorphism in TLR2 is associated with arterial thrombosis in a multiethnic population of patients with systemic lupus erythematosus

OBJECTIVE

Thrombosis is a serious complication of systemic lupus erythematosus (SLE). Studies that have investigated the genetics of thrombosis in SLE are limited. We undertook this study to assess the association of previously implicated candidate genes, particularly Toll-like receptor (TLR) genes, with pathogenesis of thrombosis.

METHODS

We genotyped 3,587 SLE patients from 3 multiethnic populations for 77 single-nucleotide polymorphisms (SNPs) in 10 genes, primarily in TLRs 2, 4, 7, and 9, and we also genotyped 64 ancestry-informative markers (AIMs). We first analyzed association with arterial and venous thrombosis in the combined population via logistic regression, adjusting for top principal components of the AIMs and other covariates. We also subjected an associated SNP, rs893629, to meta-analysis (after stratification by ethnicity and study population) to confirm the association and to test for study population or ethnicity effects.

RESULTS

In the combined analysis, the SNP rs893629 in the KIAA0922/TLR2 region was significantly associated with arterial thrombosis (logistic P = 6.4 × 10(-5) , false discovery rate P = 0.0044). Two additional SNPs in TLR2 were also suggestive: rs1816702 (logistic P = 0.002) and rs4235232 (logistic P = 0.009). In the meta-analysis by study population, the odds ratio (OR) for arterial thrombosis with rs893629 was 2.44 (95% confidence interval 1.58-3.76), without evidence for heterogeneity (P = 0.78). By ethnicity, the effect was most significant among African Americans (OR 2.42, P = 3.5 × 10(-4) ) and European Americans (OR 3.47, P = 0.024).

CONCLUSION

TLR2 gene variation is associated with thrombosis in SLE, particularly among African Americans and European Americans. There was no evidence of association among Hispanics, and results in Asian Americans were limited due to insufficient sample size. These results may help elucidate the pathogenesis of this important clinical manifestation.

Single nucleotide polymorphisms in genes encoding toll-like receptors 7, 8 and 9 in Danish patients with systemic lupus erythematosus

Several studies indicate a role for toll-like receptors (TLRs) in the pathogenesis of systemic lupus erythematosus (SLE). We aimed to investigate the risk of SLE and typical clinical and serological manifestations of SLE potentially conferred by selected single nucleotide polymorphisms (SNPs) of genes encoding TLR7, TLR8, and TLR9. Using a multiplexed bead-based assay, we analyzed eight SNPs in a cohort of 142 Danish SLE patients and a gender-matched control cohort comprising 443 individuals. Our results showed an association between the rs3853839 polymorphism of TLR7 and SLE (G vs. C, P = 0.008, OR 1.60, 95 % CI 1.12-2.27 in females; P = 0.02, OR 4.50, 95 % CI 1.18-16.7 in males) confirming recent findings in other populations. Additionally, an association between the rs3764879 polymorphism of TLR8 and SLE (G vs. C, P < 0.05, OR 1.36, 95 % CI 0.99-1.86 in females; P = 0.06, OR 4.00, 95 % CI 0.90-17.3 in males) was found. None of the other investigated SNPs were associated with SLE but several SNPs were associated with clinical and serological manifestations. In summary, a previously shown association between the rs3853839 SNP of TLR7 and SLE in Asian patients was also found in Danish patients. Together with the association of several other SNPs of TLR8 and TLR9 with various clinical and serological manifestations of SLE these findings corroborate the pathogenic significance of TLRs in SLE.

Systemic Lupus Erythematosus: Old and New Susceptibility Genes versus Clinical Manifestations

Systemic Lupus Erythematosus (SLE) is one of the most relevant world-wide autoimmune disorders. The formation of autoantibodies and the deposition of antibody-containing immune complexes in blood vessels throughout the body is the main pathogenic mechanism of SLE leading to heterogeneous clinical manifestations and target tissue damage. The complexity of etiology and pathogenesis in SLE, enclosing genetic and environmental factors, apparently is one of the greatest challenges for both researchers and clinicians. Strong indications for a genetic background in SLE come from studies in families as well as in monozygotic and dizygotic twins, discovering several SLE-associated loci and genes (e.g. IRF5, PTPN22, CTLA4, STAT4 and BANK1). As SLE has a complex genetic background, none of these genes is likely to be entirely responsible for triggering autoimmune response in SLE even if they disclosure a potentially novel molecular mechanisms in the pathogenesis' disease. The clinical manifestations and disease severity varies greatly among patients, thus several studies try to associate clinical heterogeneity and prognosis with specific genetic polymorphisms in SLE associated genes. The continue effort to describe new predisposing or modulating genes in SLE is justified by the limited knowledge about the pathogenesis, assorted clinical manifestation and the possible prevention strategies. In this review we describe newly discovered, as well as the most studied genes associated to SLE susceptibility, and relate them to clinical manifestations of the disease.

Genetic variations in Toll-like receptors (TLRs 3/7/8) are associated with systemic lupus erythematosus in a Taiwanese population

Toll-like receptors (TLRs), as innate immunity sensors, play critical roles in immune responses. Six SNPs of TLR3, TLR7, and TLR8 were genotyped to determine their associations with systemic lupus erythematosus (SLE) and clinical manifestations of SLE. TLR7 SNP rs3853839 was independently associated with SLE susceptibility in females (G vs. C: p = 0.0051). TLR7 rs3853839-G (G vs. C: p = 0.0100) and TLR8 rs3764880-G (recessive model: p = 0.0173; additive model: p = 0.0161) were associated with pericardial effusion in females relative to healthy females. Anti-SSA positive cases were more likely to have the dominant TLR7 rs179010-T allele than normal controls (p = 0.0435). TLR3 rs3775296-T was associated with photosensitivity (p = 0.0020) and anemia (p = 0.0082). The “G-G” haplotype of TLR7 rs3853839 and TLR8 rs3764880 increased risk of SLE in females (age adjusted p = 0.0032). These findings suggest that TLR variations that modify gene expression affect risk for SLE susceptibility, clinical phenotype development, and production of autoantibodies.

Toll-like receptor 7 mediates early innate immune responses to malaria

Innate immune recognition of malaria parasites is the critical first step in the development of the host response. At present, Toll-like receptor 9 (TLR9) is thought to play a central role in sensing malaria infection. However, we and others have observed that Tlr9(-/-) mice, in contrast to mice deficient in the downstream adaptor, Myeloid differentiation primary response gene 88 (MYD88), exhibit few deficiencies in immune function during early infection with the malaria parasite Plasmodium chabaudi, implying that another MYD88-dependent receptor also contributes to the antimalarial response. Here we use candidate-based screening to identify TLR7 as a key sensor of early P. chabaudi infection. We show that TLR7 mediates a rapid systemic response to infection through induction of cytokines such as type I interferons (IFN-I), interleukin 12, and gamma interferon. TLR7 is also required for induction of IFN-I by other species and strains of Plasmodium, including an etiological agent of human disease, P. falciparum, suggesting that malaria parasites harbor a common pathogen-associated molecular pattern (PAMP) recognized by TLR7. In contrast to the nonredundant requirement for TLR7 in early immune activation, sensing through both TLR7 and TLR9 was required for proinflammatory cytokine production and immune cell activation during the peak of parasitemia. Our findings indicate that TLR7 plays a central role in early immune activation during malaria infection, whereas TLR7 and TLR9 contribute combinatorially to immune responses as infection progresses.

Association study of TLR-9 polymorphisms and systemic lupus erythematosus in northern Chinese Han population

BACKGROUND

Systemic lupus erythematosus (SLE) is an autoimmune disease, with multiple genetic and environmental factors involving in its etiology. The toll-like receptor 9 (TLR9) gene has been reported to have important roles in the development and progression of SLE. We performed a case-control study to investigate the effects of 4 SNPs in the TLR9 gene in the development of SLE in Northern Chinese population.

METHODS

Four SNPs including rs187084, rs5743836, rs352139 and rs352140 were genotyped using the SNaPshot® method. A group of 430 SLE patients were compared to 424 normal controls. Data were analyzed by SPSS 17.0 and HaploView v 4.1 software.

RESULTS

The frequency distributions of SNP rs351240 and haplotype H2 (TGCT) and H3 (CATT) were found to differ significantly between patient and control groups (p<0.05), while other SNPs and haplotypes showed no significant difference between the two cohorts (p>0.05).

CONCLUSION

The results revealed that variations in the TLR9 gene are associated with SLE, indicating that TLR9 may play an important role in the pathogenesis of SLE in the northern Chinese Han population.

TLR-9 promoter polymorphisms (T-1237C and T-1486C) are not associated with systemic lupus erythematosus: a case control study and meta-analysis

Toll like receptors (TLRs) are essential molecules implicated in both innate and adaptive immune response. Polymorphisms in TLR gene have been associated with various infectious diseases and autoimmune disorders. Role of TLR9 has been elegantly demonstrated in both human systemic lupus erythematosus (SLE) and mice model of lupus. In the present study we investigated association of TLR-9 promoter polymorphisms (T-1237C and T-1486C) with susceptibility/resistance to SLE in an Eastern Indian state which is endemic to parasitic diseases. 210 Female SLE patients who fulfilled the American College of Rheumatology criteria were enrolled along with matched healthy controls from Odisha, India. TLR-9 polymorphisms (T-1237C and T-1486C) were typed by polymerase chain reaction followed by restriction fragment length polymorphism. For meta-analysis, relevant literatures were searched from PubMed database and comprehensive meta-analysis V2 software was employed for analysis. Allele and genotype frequency of TLR-9 promoter polymorphisms (T-1237C and T-1486C) were comparable among SLE patients and controls. Further, meta-analysis of earlier reports and present study did not reveal a significant association of TLR-9 (T-1237C and T-1486C) polymorphisms with SLE. Data from the present study suggest that TLR-9 promoter polymorphisms are not associated with susceptibility to SLE in an area endemic to parasitic diseases.