Variation at interleukin-6 receptor gene is associated to joint damage in rheumatoid arthritis

Towards Personalized Medicine in Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a chronic, incurable, multisystem, inflammatory disease characterized by synovitis and extra-articular features. Although several advanced therapies targeting inflammatory mechanisms underlying the disease are available, no advanced therapy is universally effective. Therefore, a ceiling of treatment response is currently accepted where no advanced therapy is superior to another. The current challenge for medical research is the discovery and integration of predictive markers of drug response that can be used to personalize medicine so that the patient is started on "the right drug at the right time". This review article summarizes our current understanding of predicting response to anti-rheumatic drugs in RA, obstacles impeding the development of personalized medicine approaches and future research priorities to overcome these barriers.

Polymorphic markers of several immune regulatory genes modulate the susceptibility for eczema and related phenotypes in children

Background

Eczema is associated with multiple genes regulating epidermal barrier functions and immunological pathways. However, their epistatic interactions are not well studied. This cross-sectional study investigated the relationship between childhood eczema phenotypes and single-nucleotide polymorphisms (SNPs) of immune regulatory genes.

Methods

One thousand three hundred and twenty-nine Chinese eczematous children and 1,179 non-allergic controls were recruited. Nine SNPs of immune regulatory genes signal transducer and activator of transcription 3 (STAT3), interleukin-10 (IL10), transforming growth factor-beta 1 (TGFB1), and IL-6 receptor (IL6R) were genotyped by TaqMan genotyping assays. Logistic regression was used to analyze the associations between SNPs and eczema phenotypes. Generalized multifactor dimensionality reduction (GMDR) was used to examine epistatic interactions among these SNPs as well as those reported by our group [filaggrin (FLG) and 11q13] for eczema phenotypes.

Results

TGFB1_rs1800469 was found to be associated with eczema [odds ratio (OR), 0.82; 95% confidence interval (CI): 0.73-0.92; P=0.001], atopic eczema (OR, 0.83; 95% CI: 0.72-0.95; P=0.009) and allergic rhinitis (OR, 0.84; 95% CI: 0.74-0.95; P=0.005). We also found a trend between IL10_rs1800872 and increased total immunoglobulin E (IgE) levels (P=0.009). Epistatic interaction among IL10_rs3021094, TGFB1_rs1800469, IL6R_rs2228145, and STAT3_rs4796793 were found for total IgE [testing accuracy (TA), 0.551; cross-validation consistency (CVC), 10; P=0.014]. Mean log-transformed total IgE (logIgE) levels in high-risk cases, low-risk cases, high-risk controls, and low-risk controls were 2.75, 2.60, 1.90, and 1.81 respectively (P=0.019 for trend).

Conclusions

Functional TGFB1 polymorphism is associated with both eczema and allergic rhinitis, suggesting the role of TGF-β1 in allergy susceptibility. IL10 may be associated with increased total IgE levels. Interaction among immune regulatory genes modulates total IgE levels.

Genetic and expression deregulation of immunoregulatory genes in rheumatoid arthritis

Rheumatoid arthritis (RA) is one of the most common autoimmune diseases globally, and is an important public health concern, associating with early death and systemic complications. Although key development in RA treatment has already been made still RA affected individuals face comorbidity and disability. Therefore, there is a need to discover new risk factors in helping early diagnosis and treatment of RA. The present study is designed to assess the variations of Vitamin D receptor (VDR) and interleukin -6 (IL-6) in RA patients. Polymorphisms of said genes were calculated in 300 RA patients and 300 controls, using Tetra-ARMS polymerase chain reaction. Secondly, expression levels of selected genes were checked using the quantitative PCR (qPCR) and obtained results were evaluated using a different statistical test. Logistic regression analysis showed that frequency of mutant allele of VDR gene polymorphisms (rs11168268, OR = 4.84; 95% CI = 2.94-7.97; p = 0.0001; rs2248098, OR = 1.65; 95% CI = 1.07-2.54; p = 0.02) and IL-6 gene polymorphisms (rs184229712, OR = 2.47; 95% CI = 1.56-3.92, p = 0.0001; rs36215814, OR = 2.14; 95% CI = 1.30-3.53; p = 0.002) was observed significantly higher in RA patients vs controls. Expression analysis showed the significant upregulation of IL-6 (p < 0.0001) and downregulation of VDR gene (p < 0.0001) in RA cases vs controls. ROC curve analysis showed that downregulation of IL-6 (AUC = 0.86, p < 0.001) and upregulation of VDR (AUC = 0.77, p < 0.001) was act as the good diagnostic marker for detection/diagnosis of arthritis. In conclusions, data from the present study showed the significant involvement of VDR and IL-6 gene variations in RA pathogenesis.

Genetic Polymorphisms Associated with Rheumatoid Arthritis Development and Antirheumatic Therapy Response

Rheumatoid arthritis (RA) is the most common inflammatory arthropathy worldwide. Possible manifestations of RA can be represented by a wide variability of symptoms, clinical forms, and course options. This multifactorial disease is triggered by a genetic predisposition and environmental factors. Both clinical and genealogical studies have demonstrated disease case accumulation in families. Revealing the impact of candidate gene missense variants on the disease course elucidates understanding of RA molecular pathogenesis. A multivariate genomewide association study (GWAS) based analysis identified the genes and signalling pathways involved in the pathogenesis of the disease. However, these identified RA candidate gene variants only explain 30% of familial disease cases. The genetic causes for a significant proportion of familial RA have not been determined until now. Therefore, it is important to identify RA risk groups in different populations, as well as the possible prognostic value of some genetic variants for disease development, progression, and treatment. Our review has two purposes. First, to summarise the data on RA candidate genes and the increased disease risk associated with these alleles in various populations. Second, to describe how the genetic variants can be used in the selection of drugs for the treatment of RA.

Methylation Pattern of the SOCS3 and IL6R Promoters in Rheumatoid Arthritis

Interleukin-6 (IL-6) plays an essential function in the development of rheumatoid arthritis (RA), mainly through its proinflammatory effect, which may lead to joint destruction. The genes encoding IL-6 receptor (IL6R) and suppressor of cytokine signaling 3 (SOCS3) play a key role in the IL-6 signaling pathway, but their epigenetic regulation remains unclear. The aim of the study was to investigate how the presence of methylation in the SOCS3 and IL6R promoters is associated with the morbidity and severity of RA. A total of 146 unrelated individuals, 122 with RA and 24 healthy controls, were enrolled in the study. All subjects were genotyped with regard to the rs4969168 and rs4969170 polymorphisms in the SOCS3 gene and the rs2228145 and rs4129267 polymorphisms in IL6R. The methylation study included 52 patients with RA and 24 healthy controls. Qualitative real-time methylation-specific PCR was used to evaluate methylation status. We found no differences between patients and healthy controls in the methylation pattern in the IL6R and SOCS3 promoter regions and in variants frequency. The methylation profiles of the SOCS3 and IL6R promoters do not support the hypothesis that the genes SOCS3 and IL6R involved in the JAK-STAT signaling pathway are epigenetically deregulated in whole blood.

KDR (VEGFR2) Genetic Variants and Serum Levels in Patients with Rheumatoid Arthritis

We investigated kinase insert domain-containing receptor (KDR) polymorphisms and protein levels in relation to susceptibility to and severity of Rheumatoid Arthritis (RA). 641 RA patients and 340 controls (HC) were examined for the rs1870377 KDR variant by the polymerase chain reaction (PCR)-restriction fragment length polymorphism (RFLP) method and for rs2305948 and rs2071559 KDR single nucleotide polymorphisms (SNPs) by TaqMan SNP genotyping assay. KDR serum levels were determined by enzyme-linked immunosorbent assay (ELISA). The rs1870377 KDR variant has shown association with RA under the codominant (p = 0.02, OR = 1.76, 95% CI = 1.09–2.85) and recessive models (p = 0.019, OR = 1.53, 95% CI = 1.07–2.20). KDR rs2305948 was associated with RA under the dominant model (p = 0.005, OR = 1.38, 95% CI = 1.10–1.73). Under the codominant model, the frequency of the rs2071559 TC and GG genotypes were lower in RA patients than in controls (p < 0.001, OR = 0.51, 95% CI = 0.37–0.69, and p = 0.002, OR = 0.57, 95% CI = 0.39–0.81). KDR rs2071559 T and rs2305948 A alleles were associated with RA (p = 0.001, OR = 0.60, 95% CI = 0.45–0.81 and p = 0.008, OR = 1.71, CI = 1.15–2.54). KDR rs2305948SNP was associated with Disease Activity Score (DAS)-28 score (p < 0.001), Visual Analog Scale (VAS) score (p < 0.001), number of swollen joints (p < 0.001), mean value of CRP (p < 0.001). A higher KDR serum level was found in RA patients than in HC (8018 pg/mL versus 7381 pg/mL, p = 0.002). Present results shed light on the role of KDR genetic variants in the severity of RA.

DNA methylation rather than single nucleotide polymorphisms regulates the production of an aberrant splice variant of IL6R in mastitic cows

Interleukin-6 receptor-alpha (IL6R) interacts with IL6 and forms a ligand-receptor complex, which can stimulate various cellular responses, such as cell proliferation, cell differentiation, and activation of inflammatory processes. Both genetic mutation and epigenetic modification regulate gene transcription. We identified a novel splice variant of bovine IL6R, designated as IL6R-TV, which is characterized by the skipping of exon 2 of the NCBI-referenced IL6R gene (IL6R-reference). The expression levels of IL6R-TV and IL6R-reference transcripts were lower in normal mammary gland tissues. These transcripts play a potential role during inflammatory infection. We also detected two putative functional SNPs (g.19711 T > C and g.19731 G > C) located within the upstream 100 bp of exon 2. These SNPs formed two haplotypes (T-G and C-C). Two mutant pSPL3 exon-trapping plasmids (pSPL3-T-G and pSPL3-C-C) were transferred into the bovine mammary epithelial cells (MAC-T) and human embryonic kidney 293 T cells (HEK293T) to investigate the relationship between the two SNPs and the aberrant splicing of IL6R. DNA methylation levels of the alternatively spliced exon in normal and mastitis-infected mammary gland tissues were quantified through nested bisulfate sequencing PCR (BSP) and cloning sequencing. We found that DNA methylation regulated IL6R transcription. The DNA methylation level was high in mastitis-infected mammary gland tissues and stimulated IL6R expression, thereby promoting the inclusion of the alternatively spliced exon. The upregulated expression of the two transcripts was due to DNA methylation modification rather than genetic mutations.

Age and Age-Related Diseases: Role of Inflammation Triggers and Cytokines

Cytokine dysregulation is believed to play a key role in the remodeling of the immune system at older age, with evidence pointing to an inability to fine-control systemic inflammation, which seems to be a marker of unsuccessful aging. This reshaping of cytokine expression pattern, with a progressive tendency toward a pro-inflammatory phenotype has been called "inflamm-aging." Despite research there is no clear understanding about the causes of "inflamm-aging" that underpin most major age-related diseases, including atherosclerosis, diabetes, Alzheimer's disease, rheumatoid arthritis, cancer, and aging itself. While inflammation is part of the normal repair response for healing, and essential in keeping us safe from bacterial and viral infections and noxious environmental agents, not all inflammation is good. When inflammation becomes prolonged and persists, it can become damaging and destructive. Several common molecular pathways have been identified that are associated with both aging and low-grade inflammation. The age-related change in redox balance, the increase in age-related senescent cells, the senescence-associated secretory phenotype (SASP) and the decline in effective autophagy that can trigger the inflammasome, suggest that it may be possible to delay age-related diseases and aging itself by suppressing pro-inflammatory molecular mechanisms or improving the timely resolution of inflammation. Conversely there may be learning from molecular or genetic pathways from long-lived cohorts who exemplify good quality aging. Here, we will discuss some of the current ideas and highlight molecular pathways that appear to contribute to the immune imbalance and the cytokine dysregulation, which is associated with "inflammageing" or parainflammation. Evidence of these findings will be drawn from research in cardiovascular disease, cancer, neurological inflammation and rheumatoid arthritis.

A pilot study of single nucleotide polymorphisms in the interleukin-6 receptor and their effects on pre- and post-transplant serum mediator level and outcome after allogeneic stem cell transplantation

Interleukin (IL)-6 is an important regulator of immunity and inflammation in many diseases. Single nucleotide polymorphisms (SNPs) in the IL-6 gene influence outcome after allogeneic stem cell transplantation (ASCT), but the possible importance of SNPs in the IL-6 receptor has not been examined. We therefore investigated whether SNPs in the IL-6R gene influenced biochemical characteristics and clinical outcomes after ASCT. We examined the IL-6 promoter variant rs1800975 and the IL-6R SNPs rs4453032, rs2228145, rs4129267, rs4845374, rs4329505, rs4845617, rs12083537, rs4845618, rs6698040 and rs4379670 in a 101 population-based cohort of allotransplant recipients and their family donors. Patients being homozygous for the major alleles of the IL-6R SNPs rs2228145 and rs4845618 showed high pretransplant CRP serum levels together with decreased sIL-6R levels; the decreased IL-6R levels persisted 6 months post-transplant. In contrast, patients being homozygous for the minor allele of the IL-6R SNP rs4379670 showed decreased pretransplant CRP levels. Furthermore, the IL-6R rs4845618 donor genotype showed an association with severe acute graft-versus-host disease (GVHD), whereas the donor genotype of the IL-6 SNP rs1800795 was associated with decreased survival 100 days post-transplant. Finally, the recipient genotype of the IL-6R SNP rs4329505 showed a strong association with 2-years non-relapse mortality, and this effect was also highly significant in multivariate analysis. IL-6 and IL-6R SNPs influence the clinical outcome after allogeneic stem cell transplantation.

Influence of IL6R gene polymorphisms in the effectiveness to treatment with tocilizumab in rheumatoid arthritis

In the present study, we aimed to investigate the influence of clinical parameters and single-nucleotide polymorphisms of interleukin-6 receptor (rs12083537, rs2228145, rs4329505 and rs11265618) on response to tocilizumab, TCZ (European League Against Rheumatism (EULAR) response, remission, low disease activity (LDA) and improvement of DAS28). We performed a retrospective cohort study in patients with Rheumatoid Arthritis (RA) treated with TCZ for 12 months. Multivariable analysis showed that the only variable independently associated to satisfactory EULAR response (odds ratio (OR): 0.61; 95% of confidence interval (CI)_95%: 0.42, 0.88; P=0.008), remission (OR: 0.51; CI_95%: 0.35, 0.75; P=0.001), LDA (OR: 0.41; CI_95%: 0.24, 0.72; P=0.002) and improvement in DAS28 (B=-0.32; CI_95%): -0.47, -0.17; P=7.5 × 10^-5) at 12 months was lower number of previous biological therapy (BT). High baseline DAS28 was also associated with a greater decrease in DAS28 at 12 months of treatment (B=0.99; CI_95%: 0.79, 1.20; P=1.5 × 10^-14). Those patients who were carriers of AA genotypes for rs12083537 (OR: 13.0; CI_95%: 2.31, 72.91; P=0.004) and CC for rs11265618 (OR: 12.15; CI_95%: 2.18, 67.81; P=0.004) had better LDA response at 12 months of treatment with TCZ. In conclusion, RA patients treated with TCZ showed better EULAR response, remission, LDA and DAS28 improvement rates when a lower number of BT were previously administered. The AA genotype for rs12083537 and CC for rs11265618 polymorphisms for may act as predictors of good response LDA.

A functional variant of TLR10 modifies the activity of NFkB and may help predict a worse prognosis in patients with rheumatoid arthritis

Background

Toll-like receptor (TLR) family members are key players in inflammation. TLR10 has been poorly studied in chronic inflammatory disorders, and its clinical relevance in rheumatoid arthritis (RA) is as yet unknown. We aimed at identifying TLR10 variants within all coding regions of the gene in patients with RA as well as studying their functional and clinical significance.

Methods

TLR10 gene variants were studied by performing sequencing of 66 patients with RA and 30 control subjects. A selected variant, I473T, was then analyzed in 1654 patients and 1702 healthy control subjects. The capacity of this TLR10 variant to modify the transcriptional activity of nuclear factor kappa-light-chain-enhancer of activated B cells (NFkB) was determined by using a luciferase reporter assay and analyzing the expression of NFkB target genes by quantitative polymerase chain reaction. Differences between groups were analyzed by using the Mann-Whitney U test and the unpaired two-tailed Student’s t test.

Results

We detected ten missense variants in the TLR10 gene and focused on the I473T substitution based on allele frequencies and the predicted functional impact. I473T variant is not associated with susceptibility to RA, but it significantly correlates with erosive disease in patients seropositive for antibodies to citrullinated protein antigens (p = 0.017 in the total cohort and p = 0.0049 in female patients) and with a lower response to infliximab treatment as measured by the change in Disease Activity Score in 28 joints (p = 0.012) and by the European League Against Rheumatism criteria (p = 0.049). Functional studies showed that TLR10 reduced activation of the NFkB inflammatory pathway in hematopoietic cells, whereas the I473T variant lacked this inhibitory capacity. Consistently, after exposure to infliximab, cells expressing the I437T variant showed higher NFkB activity than cells carrying wild-type TLR10.

Conclusions

A TLR10 allelic variant, I473T, has impaired NFkB inhibitory activity and is highly associated with disease severity and low response to infliximab in patients with RA.