The IL - 6 promoter polymorphism is associated with disease activity and disability in systemic sclerosis

The Microbiome in Systemic Sclerosis: Pathophysiology and Therapeutic Potential

Systemic sclerosis (SSc), also known as scleroderma, is an autoimmune disease with unknown etiology characterized by multi-organ fibrosis. Despite substantial investigation on SSc-related cellular and molecular mechanisms, effective therapies are still lacking. The skin, lungs, and gut are the most affected organs in SSc, which act as physical barriers and constantly communicate with colonized microbiota. Recent reports have documented a unique microbiome signature, which may be the pathogenic trigger or driver of SSc. Since gut microbiota influences the efficacy and toxicity of oral drugs, evaluating drug-microbiota interactions has become an area of interest in disease treatment. The existing evidence highlights the potential of the microbial challenge as a novel therapeutic option in SSc. In this review, we have summarized the current knowledge about molecular mechanisms of SSc and highlighted the underlying role of the microbiome in SSc pathogenesis. We have also discussed the latest therapeutic interventions using microbiomes in SSc, including drug-microbiota interactions and animal disease models. This review aims to elucidate the pathophysiological connection and therapeutic potential of the microbiome in SSc. Insights into the microbiome will significantly improve our understanding of etiopathogenesis and developing therapeutics for SSc.

Relationship Between Interleukin-6 -174G/C Genetic Variant and Efficacy of Methotrexate Treatment in Psoriatic Arthritis Patients

Introduction

The purpose of the study was to investigate whether single-nucleotide polymorphisms (SNPs) IL-6 −174 G/C and IL-6R Asp358Ala are associated with susceptibility to psoriatic arthritis (PsA) or affect response to treatment with methotrexate (MTX).

Patients and Methods

Seventy-four patients diagnosed with PsA and qualified for MTX treatment were enrolled to the study. The control group consisted of 120 healthy individuals. Polymorphisms IL-6 −174 G/C and IL-6R Asp358Ala were genotyped using a polymerase chain reaction (PCR) amplification employing LightSNiP assays.

Results

A significant association between the IL-6 −174 CC genotype and an improved clinical outcome of MTX therapy was observed. A good response was more frequently observed among PsA patients bearing the IL-6 −174 CC genotype than patients with the GC or GG genotypes (P = 0.007). On the other hand, patients carrying the IL-6 −174 GC genotype less frequently responded to MTX treatment as compared to patients with other genotypes (P = 0.006). With respect to the IL-6R Asp358Ala SNP, there were no significant differences in genotype and allelic frequencies in relation to clinical outcome of MTX treatment. No association was found between the IL-6 −174 G/C or IL-6R Asp358Ala SNPs and PsA susceptibility.

Conclusion

Results from this study provide evidence that the IL-6 −174 G/C polymorphism might influence efficacy of MTX treatment.

Imbalance between T helper 17 and regulatory T cell subsets plays a significant role in the pathogenesis of systemic sclerosis

Systemic sclerosis (SSc) is a rare autoimmune disease that is characterized by fibrosis, inflammation, and vasculopathy of the skin and internal organs. The etiopathogenesis of SSc remains unclear. However, the pivotal role of T lymphocytes with an aberrant immune response in SSc is well established. Among T cells, IL-17-producing helper T (Th17) cell and regulatory T (Treg) cell subsets have recently been found to play crucial roles in SSc pathogenesis. Generally speaking, Th17 cell subsets up-regulate inflammation, fibrosis, and autoimmunity, which are present in SSc, while Treg cell subsets have an immunosuppressive function and resist the immunological performance of Th17 cells. Up-to-date evidence has pointed out that the imbalance and abnormal functions of Th17/Treg cells may contribute to SSc. Therefore, this review aims to summarize the current understanding of the vital cytokines and signaling pathways that are involved in Th17/Treg differentiation and functions, and their roles in the pathogenesis of SSc, thus providing novel insights about targeting the Th17/Treg balance as a potential therapy for SSc treatment in the near future.

Lack of association between rs1800795 (-174 G/C) polymorphism in the promoter region of interleukin-6 gene and susceptibility to type 2 diabetes in Isfahan population

BACKGROUND

Type 2 diabetes mellitus (T2DM) is an inflammatory autoimmune disease that mostly affects older adults. The etiology of T2DM includes both genetic and environmental factors. rs1800795 (-174 G/C) single nucleotide polymorphism (SNP) linked with autoimmune disorders predispositions, identified by Genome-Wide Association Study among genes, which immunologically related is considerably over signified. The goal of this study was to evaluate the association between rs1800795 (-174 G/C) polymorphisms in the promoter of interleukin-6 (IL-6) gene with susceptibility to T2DM in a subset of the Iranian population.

MATERIALS AND METHODS

In this case-control study, 120 healthy subjects and 120 patients with T2DM were included. Genomic DNA obtained from whole blood samples and the polymerase chain reaction was used to amplify the fragment of interest contain rs1800795 SNP, restriction fragment length polymorphism method was applied for genotyping of the DNA samples with NlaIII as a restriction enzyme. SPSS for Windows software (version 18.0, SPSS, Chicago, IL, USA) was performed for statistical analysis.

RESULTS

No significant differences were found between healthy controls and T2DM patients with respect to the frequency distribution of the cytokine gene polymorphism investigated. Odds ratio, adjusted for sex, age, and smoking status has displayed similar outcomes.

CONCLUSION

These results indicated that the rs1800795 SNP is not a susceptibility gene variant for the development of T2DM in the Isfahan population. Further studies using new data on complex transcriptional interactions between IL-6 polymorphic sites are necessary to determine IL-6 haplotype influence on susceptibility to T2DM.

Update on biomarkers in systemic sclerosis: tools for diagnosis and treatment

Systemic sclerosis (SSc) is a complex autoimmune disease in which immune activation, vasculopathy, and extensive fibrosis of the skin and internal organs are among the principal features. SSc is a heterogeneous disease with varying manifestations and clinical outcomes. Currently, patients’ clinical evaluation often relies on subjective measures, non-quantitative methods, or requires invasive procedures as markers able to predict disease trajectory or response to therapy are lacking. Therefore, current research is focusing on the discovery of useful biomarkers reflecting ongoing inflammatory or fibrotic activity in the skin and internal organs, as well as being predictive of future disease course. Recently, remarkable progress has been made towards a better understanding of numerous mechanisms involved in the pathogenesis of SSc. This has opened new possibilities for the development of novel biomarkers and therapy. However, current proposed biomarkers that could reliably describe various aspects of SSc still require further investigation. This review will summarize studies describing the commonly used and validated biomarkers, the newly emerging and promising SSc biomarkers identified to date, and consideration of future directions in this field.

Role of the promoter polymorphism IL-6 -174G/C in dermatomyositis and systemic lupus erythematosus

The promoter polymorphism -174G/C within the interleukin-6 gene (IL-6) has been reported to have a functional importance through the modulation of IL-6 gene expression in vitro and in vivo. IL-6 is thought to play an important role in autoimmune diseases and the effect of its receptor inhibitor-tocilizumab-has been recently studied. The aim of this case-control study was to investigate the association between the interleukin-6 -174G/C single nucleotide polymorphism and the susceptibility to dermatomyositis (DM) and systemic lupus erythematosus (SLE) in Bulgarian patients. Altogether, 87 patients-52 with SLE and 35 with DM-as well as 80 unrelated healthy controls were included in this study. All of them were analyzed by restriction fragment length polymorphism analysis (RFLP). The GG genotype and the G allele appeared to be associated with SLE, especially in women. None of the genotypes showed an association with DM. However, the G allele appeared to be associated with muscle weakness and it is a risk factor for elevated muscle enzymes. Our results indicate that IL-6 -174G/C polymorphism might be associated with the susceptibility to SLE especially in women. Although it is not associated with DM, it seems that IL-6 -174G/C polymorphism could modulate some clinical features in the autoimmune myopathies.

The role of type 1 interferon in systemic sclerosis

Systemic Sclerosis (Scleroderma, SSc) is an autoimmune disease characterized by vasculopathy, inflammation, and fibrosis that can lead to loss of organ function. Type I interferons (IFNs) are family of cytokines that mitigate the deleterious effects of viral and bacterial infections in the innate immunity system. Past several years, research efforts have been focused on the role of type I IFN and IFN-inducible genes in the pathogenesis of SSc. Polymorphisms in the Interferon regulatory factor (IRF)-5, IRF7, and IRF8 are associated with SSc, Similarly, polymorphism of Signal Transducer and Activator of Transcription (STAT)-4, has been established as a genetic risk factor of SSc. IRFs and STAT4 proteins are key activators of type I IFN signaling pathways. An IFN signature (increased expression and activation of IFN-regulated genes) has been observed in the peripheral blood and skin biopsy samples of patients with SSc. Furthermore, a plasma IFN-inducible chemokine score correlated with markers of disease severity and autoantibody subtypes in SSc. In this review, we summarize our current knowledge of the role of type I IFNs and IFN-inducible genes in the pathogenesis of SSc and their potential role as biomarkers and therapeutic targets.

Insights into the pathogenesis of systemic sclerosis based on the gene expression profile of progenitor-derived endothelial cells

OBJECTIVE

To determine the gene expression profile of endothelial cells derived from the endothelial progenitor cells (EPCs) of patients with systemic sclerosis (SSc).

METHODS

Microarray experiments were performed on Affymetrix GeneChip Human Exon 1.0 ST Arrays in unstimulated and hypoxia-stimulated EPC-derived cells from patients with SSc and control subjects. Followup of the raised hypotheses was performed ex vivo by immunohistochemical analysis of skin tissue.

RESULTS

Signals from 92 probe sets and 188 probe sets were different in unstimulated and hypoxia-stimulated cells, respectively, from patients with SSc compared with controls. Within the largest groups of genes related to cell-cell interaction and vascular remodeling, down-regulation of tumor necrosis factor ligand superfamily member 10 (TNFSF10) and homeobox A9 (HOX-A9) was confirmed by real-time polymerase chain reaction and Western blots in EPC-derived cells and by immunohistochemistry in SSc skin tissue. Signals from 221 and 307 probe sets were different in unstimulated and hypoxia-stimulated cells, respectively, from patients with diffuse cutaneous SSc compared with patients with limited cutaneous SSc. Within the largest group of genes related to the inflammatory response, differential expression of TNFα-induced protein 3 and prostaglandin-endoperoxide synthase 2 was observed in EPC-derived cells and skin tissue from patients with SSc.

CONCLUSION

Our data revealed important gene expression changes in EPC-derived endothelial cells from patients with SSc, characterized by a proadhesive, proinflammatory, and activated phenotype. Differential expression in lesional SSc skin tissue of new targets, such as TNF family members and HOX-A9, may contribute to the pathogenesis of SSc and deserves more in-depth exploration.

Influence of the IL6 gene in susceptibility to systemic sclerosis

OBJECTIVE

Systemic sclerosis (SSc) is a genetically complex autoimmune disease; the genetic component has not been fully defined. Interleukin 6 (IL-6) plays a crucial role in immunity and fibrosis, both key aspects of SSc. We investigated the influence of IL6 gene in the susceptibility and phenotype expression of SSc.

METHODS

We performed a large metaanalysis including a total of 2749 cases and 3189 controls from 6 white populations (Germany, The Netherlands, Norway, Spain, Sweden, and United Kingdom). Three IL6 single-nucleotide polymorphisms (SNP; rs2069827, rs1800795, and rs2069840) were selected by SNP tagging and genotyped using TaqMan(®) allele discrimination technology.

RESULTS

Individual SNP metaanalysis showed no evidence of association of the 3 IL6 genetic variants with the global disease. Phenotype analyses revealed a significant association between the minor allele of rs2069840 and the limited cutaneous SSc clinical form (Bonferroni p = 0.036, OR 1.14, 95% CI 1.04-1.25). A trend of association between the minor allele of the rs1800795 and the diffuse cutaneous SSc clinical form was also evident (Bonferroni p = 0.072, OR 0.86, 95% CI 0.77-0.96). In the IL6 allelic combination analyses, the GGC allelic combination rs2069827-rs1800795-rs2069840 showed an association with overall SSc (Bonferroni p = 0.016, OR 1.13, 95% CI 1.04-1.23).

CONCLUSION

Our results suggest that the IL6 gene may influence the development of SSc and its progression.

Serum leptin, resistin and TNF-α levels in patients with systemic sclerosis: the role of adipokines in scleroderma

AIM

Systemic sclerosis (SSc) is a chronic fibrotic collagen tissue disease. Leptin's role in regulating immune and inflammatory response has become increasingly evident. Resistin has pro-inflammatory properties and also is associated with inflammatory markers in some rheumatologic diseases. The purpose of this study was to determine serum leptin, resistin and tumor necrosis factor alpha (TNF-α) in SSc patients and evaluate their association with other frequently used laboratory and clinic findings.

METHOD

Sixteen patients were compared with 30 healthy women of similar age and body mass index. Serum leptin, resistin and TNF-α levels were measured by enzyme-linked immunosorbent assay and results were assessed by Mann-Whitney U -test and Spearman's correlation test.

RESULTS

Leptin levels were significantly increased in the SSc group compared to controls (7789.43 ± 1180.72 pg/mL, 1790.55 ± 333.68 pg/mL, P < 0.0001). TNF-α was significantly elevated in patients and it was also positively correlated with leptin (25.30 ± 2.16 pg/mL, 20.95 ± 0.30 pg/mL, P = 0.001), (P = 0.002, r = 0.523). There was no association between leptin, resistin, TNF-α levels and skin score, activity score and disease duration in the SSc patients (P > 0.05).

CONCLUSION

Leptin, resistin and TNF-α levels were found to be higher in SSc in contrast to the control group. These adipokines may have differentiating roles in the pathogenesis of SSc. In order to verify these findings, further clinical studies are needed with larger patient groups.

Interleukin 6 in Systemic Sclerosis and Potential Implications for Targeted Therapy

Objective.

The purpose of this study was to review the potential importance of interleukin 6 (IL-6) in systemic sclerosis (SSc).

Methods.

PubMed and Scopus databases and American College of Rheumatology (from 2009–10) and European League Against Rheumatism abstracts (2009–11) were searched using keywords “scleroderma; SSc; cytokines; interleukins; interleukin 6” and publications were excluded if not pertaining to IL-6 in SSc. Data were extracted from selected articles to construct a cell interaction model of the effects of IL-6 in SSc.

Results.

A total of 416 reports were found (PubMed, n = 82; Scopus, n = 331; 3 abstracts); 372 were excluded (irrelevant) leaving 41 publications and 3 abstracts (39 from PubMed, 18 from Scopus; but 16 were repeated from PubMed search), where 40 suggested IL-6 was important in SSc and 4 did not. Effects of IL-6 in SSc were summarized schematically.

Conclusion.

Of the 44 publications, 40 suggested that IL-6 may be important in SSc, allowing for a conceptual framework within SSc including effects on macrophages, fibroblasts, plasma cells, monocytes, and extracellular matrix.

Gingival overgrowth in cyclosporine, tacrolimus, or sirolimus-based immunosuppressive regimens and the single nucleotide IL-6 (-174 G/C) gene polymorphism

OBJECTIVE

Interleukin-6 (IL-6) may be involved in drug-induced gingival overgrowth (GO). The present study was conducted to assess the association between IL-6 (-174 G/C) gene polymorphism and GO in renal transplant recipients under cyclosporine (CsA), tacrolimus (Tcr), or sirolimus (Sir)-based regimens.

METHODS

Within an eligible population, 45 unrelated subjects were selected for each CsA, Tcr, and Sir group, totaling a sample of 135 subjects. GO was visually assessed and subjects were assigned as controls (non-responders) or cases (responders) in a post hoc definition. IL-6 gene polymorphism was assessed using the polymerase chain reaction amplification and digestion. The distribution of genotypes and allele frequencies in responders and non-responders were compared using the Chi-squared test.

RESULTS

The number of responders was 27 (60.0%), 13 (28.9%), and 7 (15.6%) in the CsA, Tcr, and Sir groups, respectively. No differences could be observed at frequencies of -174GG, -174CG, and -174CC genotypes when comparing responders to non-responders in the CsA, Tcr, and Sir groups. Similar to genotypes, allele frequencies showed no differences between responders and non-responders in all groups.

CONCLUSIONS

No association between IL-6 (-174 G/C) gene polymorphism and gingival overgrowth was observed in renal transplant recipients under CsA, Tcr, or Sir-based immunosuppressive maintenance regimens.

Cannabinoids inhibit fibrogenesis in diffuse systemic sclerosis fibroblasts

OBJECTIVE

It has been demonstrated that the endocannabinoid system is up-regulated in pathologic fibrosis and that modulation of the cannabinoid receptors might limit the progression of uncontrolled fibrogenesis. The aim of this study was to investigate whether the synthetic cannabinoid receptor agonist WIN55,212-2 could modulate fibrogenesis in an in vitro model of dcSSc.

METHODS

The expression of cannabinoid receptors CB1 and CB2 was assessed in dcSSc fibroblasts and healthy control fibroblasts. To investigate the effect of WIN55,212-2 on dcSSc fibrogenesis, we studied type I collagen, profibrotic cytokines, fibroblast transdifferentiation into myofibroblasts, apoptotic processes and activation of the extracellular signal-related kinase 1/2 pathway prior to and after the treatment with the synthetic cannabinoid at increasing concentrations.

RESULTS

Both CB1 and CB2 receptors were over-expressed in dcSSc fibroblasts compared with healthy controls. WIN55,212-2 caused a reduction in extracellular matrix deposition and counteracted several behavioural abnormalities of scleroderma fibroblasts including transdifferentiation into myofibroblasts and resistance to apoptosis. The anti-fibrogenic effect of WIN55,212-2 was not reverted by selective cannabinoid antagonists.

CONCLUSIONS

Our preliminary findings suggest that cannabinoids are provided with an anti-fibrotic activity, thereby possibly representing a new class of agents targeting fibrosis diseases.

Predictors of the scleroderma phenotype in fibroblasts from systemic sclerosis patients

BACKGROUND

Fibroblasts from skin lesions generally exhibit the scleroderma phenotype in the early stage of in vitro culture, and act as one of the most important samples to investigate systemic sclerosis. However, not all cell lines from patients show the scleroderma phenotype, and little prospective evidence can be relied on to predict the phenotype of fibroblasts from systemic sclerosis patients.

OBJECTIVE

This study aims to find the predictive factors related to fibroblast phenotypes.

METHODS

Fibroblast lines from 15 patients with systemic sclerosis were established through explant culture, with their scleroderma phenotypes being determined by real-time reverse transcription-polymerase chain reaction (RT-PCR) of procollagen transcription. Logistic regression analysis was used to analyse the clinical data of these patients. Haematoxylin-eosin staining was performed to observe histopathological differences. Expression of methylation-related factors was detected by real-time reverse transcription-polymerase chain reaction.

RESULTS

Eight of the 15 fibroblast cell lines from patients with systemic sclerosis exhibited the scleroderma phenotype. Logistic regression analysis yielded an equation (Y = -9.718 + 2.525X1) in which X1 significantly represents the Valentini Disease Activity Index. Histopathology results demonstrated that the scleroderma phenotype was positively correlated with leucocyte infiltration. Further laboratory observations showed increased expression of Dnmt1 in the positive phenotype fibroblasts and a positive correlation between elevations of Dnmt1 and the maintenance period of the scleroderma phenotype.

CONCLUSIONS

The results of this study suggest that the Valentini Disease Activity Index and expression of Dnmt1 may act as indicators of the scleroderma phenotype in fibroblasts. Additionally, these data also imply that epigenetic factors, such as Dnmt1, may be involved in the maintenance of the scleroderma phenotype. Our analyses may be beneficial to the research in systemic sclerosis.

Update on Indices of Disease Activity in Systemic Sclerosis

OBJECTIVE

An important barrier in the study of systemic sclerosis (SSc) is the difficulty in measuring disease activity. We reviewed the literature on currently available global measures of disease activity in SSc.

METHODS

The PubMed database (1950-2006) was searched for the key words "scleroderma" in conjunction with "disease activity" and then "disease severity." All relevant original and review articles in English and French were reviewed. Textbooks in rheumatology and pertinent secondary references were also reviewed.

RESULTS

There are currently 3 tools that are used to measure disease activity globally in SSc. Physician global assessments have been commonly used but have not been formally evaluated. The Valentini Disease Activity Index is a new measure that consists of 10 variables and a resulting score ranging from 0 to 10. It appears easy to use but lacks some face and content validity and responsiveness to change has yet to be demonstrated. The Medsger Disease Severity Scale measures disease severity in 9 organ systems. However, it assesses mostly damage and is difficult to score.

CONCLUSIONS

There is currently no gold standard measure of disease activity in SSc. Given the need to measure disease activity in SSc and the limitations of the currently available instruments, efforts are ongoing to develop new ones. This represents a major challenge but one that remains particularly important to undertake.