Association of interleukin 23 receptor polymorphisms with anti-topoisomerase-I positivity and pulmonary hypertension in systemic sclerosis

Cellular and Molecular Diversity in Scleroderma

With the increasing armamentarium of high-throughput tools available at manageable cost, it is attractive and informative to determine the molecular underpinnings of patient heterogeneity in systemic sclerosis (SSc). Given the highly variable clinical outcomes of patients labelled with the same diagnosis, unravelling the cellular and molecular basis of disease heterogeneity will be crucial to predicting disease risk, stratifying management and ultimately informing a patient-centered precision medicine approach. Herein, we summarise the findings of the past several years in the fields of genomics, transcriptomics, and proteomics that contribute to unraveling the cellular and molecular heterogeneity of SSc. Expansion of these findings and their routine integration with quantitative analysis of histopathology and imaging studies into clinical care promise to inform a scientifically driven patient-centred personalized medicine approach to SSc in the near future.

Classical Disease-Specific Autoantibodies in Systemic Sclerosis: Clinical Features, Gene Susceptibility, and Disease Stratification

Systemic sclerosis (SSc) is an autoimmune disease characterized by abnormalities in microcirculation, extracellular matrix accumulation, and immune activation. Autoantibodies are markers of immune abnormalities and provide diagnostic and predictive value in SSc. Anti-topoisomerase antibodies (ATAs), anticentromere antibodies (ACAs), and anti-RNA polymerase antibodies (ARAs) are the three classical specific antibodies with the highest availability and stability. In this review, we provide an overview of the recent progress in SSc research with respect to ATAs, ACAs, and ARAs, focusing on their application in distinguishing clinical phenotypes, such as malignancy and organ involvement, identifying genetic background in human leukocyte antigen (HLA) or non-HLA alleles, and their potential roles in disease pathogenesis based on the effects of antigen-antibody binding. We finally summarized the novel analysis using ATAs, ACAs, and ARAs on more detailed disease clusters. Considering these advantages, this review emphasizes that classical SSc-specific autoantibodies are still practical and have the potential for patient and risk stratification with applications in precise medicine for SSc.

Molecular "omic" signatures in systemic sclerosis

Systemic sclerosis (SSc) is a connective tissue disorder characterized by immunologic, vascular, and extracellular matrix abnormalities. Variation in the proportion and/or timing of activation in the deregulated molecular pathways that underlie SSc may explain the observed clinical heterogeneity in terms of disease phenotype and treatment response. In recent years, SSc research has generated massive amounts of "omics" level data. In this review, we discuss the body of "omics" level work in SSc and how each layer provides unique insight to our understanding of SSc. We posit that effective integration of genomic, transcriptomic, metagenomic, and epigenomic data is an important step toward precision medicine and is vital to the identification of effective therapeutic options for patients with SSc.

The profiles of miRNAs and lncRNAs in peripheral blood neutrophils exosomes of diffuse cutaneous systemic sclerosis

BACKGROUND

Diffuse cutaneous systemic sclerosis (dSSc) is a systemic autoimmune disease with skin fibrosis. Neutrophils display important roles in autoimmunity, inflammation, vasculopathy and fibrosis. Exosomes (EXOs) are cell-derived vesicles contained various noncoding RNAs, mRNA and proteins with biological roles.

OBJECTIVE

To investigate the roles of miRNAs and lncRNAs from dSSc neutrophils EXOs.

METHODS

EXOs were isolated from cultured neutrophils supernatants and identified by transmission electron microscopy. Global expression of miRNAs and lncRNAs in neutrophils EXOs were sequenced by Illumina HiSeq 3000 and bioinformatic analyses were performed by R/Bioconductor. Genes were validated by real-time quantitative PCR.

RESULTS

In profiles of neutrophils EXOs, we identified 22 dysregulated miRNAs and 281 dysregulated lncRNAs. Predicted target genes of them were enriched in GO, KEGG and Reactome pathways, Wnt, AMPK, IL-23 and NOTCH signaling pathways were selected for further analysis. Widely interactions among them were also found. Human dermal microvascular endothelial cells and human primary skin fibroblasts were stimulated with dSSc neutrophils EXOs, these fibrosis related genes were detected and some changes were found, such as ENST00000533886.1-hsa-miR-1268a-CAMK2G in Wnt and IL-23 signaling pathways, ENST00000610091.1-hsa-miR-299-3p, 512-3p-CPT1A in IL-23 and AMPK signaling pathways, NR_001564.2, ENST00000520562.1, ENST00000596567.1-hsa-miR-299-3p, 512-3p -TFDP2 in IL-23, AMPK and NOTCH signaling pathways.

CONCLUSIONS

The profiles of miRNAs and lncRNAs of neutrophils EXOs provided novel clues for dSSc pathogenesis. We identified several gene pairs in the Wnt, AMPK, IL-23 and NOTCH signaling pathways, which could be potential biomarkers and therapeutic targets in dSSc.

Genetic Interactions Affect Lung Function in Patients with Systemic Sclerosis

Scleroderma, or systemic sclerosis (SSc), is an autoimmune disease characterized by progressive fibrosis of the skin and internal organs. The most common cause of death in people with SSc is lung disease, but the pathogenesis of lung disease in SSc is insufficiently understood to devise specific treatment strategies. Developing targeted treatments requires not only the identification of molecular processes involved in SSc-associated lung disease, but also understanding of how these processes interact to drive pathology. One potentially powerful approach is to identify alleles that interact genetically to influence lung outcomes in patients with SSc. Analysis of interactions, rather than individual allele effects, has the potential to delineate molecular interactions that are important in SSc-related lung pathology. However, detecting genetic interactions, or epistasis, in human cohorts is challenging. Large numbers of variants with low minor allele frequencies, paired with heterogeneous disease presentation, reduce power to detect epistasis. Here we present an analysis that increases power to detect epistasis in human genome-wide association studies (GWAS). We tested for genetic interactions influencing lung function and autoantibody status in a cohort of 416 SSc patients. Using Matrix Epistasis to filter SNPs followed by the Combined Analysis of Pleiotropy and Epistasis (CAPE), we identified a network of interacting alleles influencing lung function in patients with SSc. In particular, we identified a three-gene network comprising WNT5A, RBMS3, and MSI2, which in combination influenced multiple pulmonary pathology measures. The associations of these genes with lung outcomes in SSc are novel and high-confidence. Furthermore, gene coexpression analysis suggested that the interactions we identified are tissue-specific, thus differentiating SSc-related pathogenic processes in lung from those in skin.

HLA and autoantibodies define scleroderma subtypes and risk in African and European Americans and suggest a role for molecular mimicry

Systemic sclerosis (SSc) is a clinically heterogeneous autoimmune disease characterized by mutually exclusive autoantibodies directed against distinct nuclear antigens. We examined HLA associations in SSc and its autoantibody subsets in a large, newly recruited African American (AA) cohort and among European Americans (EA). In the AA population, the African ancestry-predominant HLA-DRB1*08:04 and HLA-DRB1*11:02 alleles were associated with overall SSc risk, and the HLA-DRB1*08:04 allele was strongly associated with the severe antifibrillarin (AFA) antibody subset of SSc (odds ratio = 7.4). These African ancestry-predominant alleles may help explain the increased frequency and severity of SSc among the AA population. In the EA population, the HLA-DPB1*13:01 and HLA-DRB1*07:01 alleles were more strongly associated with antitopoisomerase (ATA) and anticentromere antibody-positive subsets of SSc, respectively, than with overall SSc risk, emphasizing the importance of HLA in defining autoantibody subtypes. The association of the HLA-DPB1*13:01 allele with the ATA⁺ subset of SSc in both AA and EA patients demonstrated a transancestry effect. A direct correlation between SSc prevalence and HLA-DPB1*13:01 allele frequency in multiple populations was observed (r = 0.98, P = 3 × 10^-6). Conditional analysis in the autoantibody subsets of SSc revealed several associated amino acid residues, mostly in the peptide-binding groove of the class II HLA molecules. Using HLA α/β allelic heterodimers, we bioinformatically predicted immunodominant peptides of topoisomerase 1, fibrillarin, and centromere protein A and discovered that they are homologous to viral protein sequences from the Mimiviridae and Phycodnaviridae families. Taken together, these data suggest a possible link between HLA alleles, autoantibodies, and environmental triggers in the pathogenesis of SSc.

Functional and phenotypic heterogeneity of Th17 cells in health and disease

BACKGROUND

Th17 cells have nonredundant roles in maintaining immunity, particularly at mucosal surfaces. These roles are achieved principally through the production of cytokines and the recruitment of other immune cells to maintain the integrity of mucosal barriers and prevent the dissemination of microorganisms. Th17 cells are heterogeneous and exhibit a considerable degree of plasticity. This allows these cells to respond to changing environmental challenges. However, Th17 cells also play pro-inflammatory roles in chronic autoimmune diseases. The trigger(s) that initiate these Th17 responses in chronic autoimmune diseases remain unclear.

DESIGN

In this report, we provide an overview of studies involving animal models, patient data, genome wide association studies and clinical trials targeting IL-17 for treatment of patients to gain a better understanding of the pathogenic roles of Th17 cells play in a range of autoimmune diseases.

RESULTS

The report sheds light on likely triggers that initiate or perpetuate Th17 responses that promote chronic inflammation and autoimmunity. The divergent effects of tumour necrosis factor alpha blockade on Th17 cells in patients, is explored. Furthermore, we highlight the role of Th17 cells in inducing autoreactive B cells, leading to autoantibody production. Pathogenic bacterial species can change Th17 cell phenotype and responses. These findings provide insights into how Th17 cells could be induced to promoting autoimmune disease pathogenesis.

CONCLUSION

This article provides an overview of the distinct roles Th17 cells play in maintaining immunity at mucosal surfaces and in skin mucosa and how their functional flexibility could be linked with chronic inflammation in autoimmune rheumatic diseases.

Evaluation of interleukin 23 (IL-23) as a non-invasive test of disease severity in patients with ulcerative colitis

BACKGROUND AND STUDY AIMS

Studies have found increased expression of IL-23 in inflamed and non-inflamed mucosa of patients with ulcerative colitis (UC). We hypothesized that serum interleukin-23 as a non-invasive test has a role in pathogenesis of ulcerative colitis disease and correlates with the disease severity.

PATIENTS AND METHODS

Forty patients with biopsy proven ulcerative colitis, recruited from Ain Shams University hospitals were included. Forty healthy subjects matched in age and gender were also included in the study as a control group. Serum IL-23 level was quantified using quantitative ELISA technique (Enzyme linked Immunosorbent Assay).

RESULTS

Patients with UC had higher level of interleukin 23 (234.5 ± 161 pg/mL) compared to control subjects (54.2 ± 15 pg/mL) and the level of IL-23 correlated with the disease severity. Cut off value of IL-23 at 68 pg/mL was the best to differentiate between cases and control subjects. Receiver operating characteristic curve (ROC) revealed that the best cut off for IL-23 to detect mild cases of ulcerative colitis was at105 pg/mL, to detect moderate cases at 200 pg/mL and to detect severe cases was at 270 pg/mL with sensitivity 80% to mild cases, 60% to moderate cases and 81% to severe cases.

CONCLUSION

Our findings confirm the suggestion that IL-23 level measurement may be of value as a non-invasive test in the diagnosis and disease severity assessment in patients with UC.

Lung Involvements in Rheumatic Diseases: Update on the Epidemiology, Pathogenesis, Clinical Features, and Treatment

Lung illness encountered in patients with rheumatic diseases bears clinical significance in terms of increased morbidity and mortality as well as potential challenges placed on patient care. Although our understanding of natural history of this important illness is still limited, epidemiologic knowledge has been accumulated during the past decade to provide useful information on the risk factors and prognosis of lung involvements in rheumatic diseases. Moreover, the pathogenesis particularly in the context of genetics has been greatly updated for both the underlying rheumatic disease and associated lung involvement. This review will focus on the current update on the epidemiologic and genetics features and treatment options of the lung involvements associated with four major rheumatic diseases (rheumatoid arthritis, systemic sclerosis, myositis, and systemic lupus erythematosus), with more attention to a specific form of involvement or interstitial lung disease.

Is there a role for IL-17 in the pathogenesis of systemic sclerosis?

In systemic sclerosis (SSc) immuno-inflammatory events are central to disease development. Amongst other mediators of inflammation, interleukin 17 (IL-17) and Th17 cells have been reported to be increased in the peripheral blood and target organs including involved skin in SSc. They participate and amplify inflammatory responses by inducing the production of cytokines such as IL-6, chemokines such as CCL2 and CXCL8 (IL-8), matrix metalloproteinases-1, -2, -9 and the expression of adhesion molecules in stromal cells including fibroblasts and endothelial cells. In this respect, IL-17 and Th17 cells behave paradigmatically as documented in other autoimmune pathological conditions or infectious diseases. In experimental animal models of skin and lung fibrosis, IL-17 indirectly enhances the fibrotic process by favoring further inflammation by recruiting inflammatory cells, by activating and/or stimulating the production of TGF-β and other pro-fibrotic mediators, by inhibiting autophagy. Whether the findings generated in animal models of fibrosis can be translated to human SSc is unproven. Furthermore, it is controversial whether IL-17 directly promotes the transdifferentiation of human fibroblasts into myofibroblasts and enhances collagen production, with most of the available evidence against this possibility. The reductionist approach in which fibroblast in monolayers are cultured in plastic dishes under the influence of IL-17 limits the relevance of these findings. Further in vitro/ex vivo models with human tissues are being developed to investigate the real effect of IL-17 on extracellular matrix deposition, since agents blocking IL-17 are available for the clinic and it will be important to know whether their use in SSc would be beneficial or detrimental.

IL-17 and related cytokines involved in systemic sclerosis: Perspectives

Systemic sclerosis (SSc) is a multisystemic, complex, and rare disease of connective tissue, with high morbidity and mortality, and without specific treatment. The disease is characterized by three main principles: vascular disease, autoantibody production and inflammation, and fibrosis. Since it is well defined that SSc is characterized by elevated production of TGF-β, IL-6, and IL-1, all of them cytokines related to Th17 differentiation, the hypothesis is that this disease may be strongly related to a polarization of the immune response towards the Th17 pathway. Considering the importance of a better understanding of the pathophysiology of Th17 pathway in SSc, this article aims to propose an update for a better understanding of current knowledge on main cytokines secreted by the Th17 cells (IL-17 A, IL-21, and IL-22) and the future prospects in the current disease.

Dendritic cells in systemic sclerosis: Advances from human and mice studies

Systemic sclerosis (SSc) is a complex heterogeneous fibrotic autoimmune disease with an unknown exact etiology, and characterized by three hallmarks: fibrosis, vasculopathy, and immune dysfunction. Dendritic cells (DCs) are specialized cells in pathogen sensing with high potency of antigen presentation and capable of releasing mediators to shape the immune response. Altered DCs distributions and their impaired functions may account for their role in breaking the immune tolerance and driving inflammation in SSc, and the direct contribution of DCs in promoting endothelial dysfunction and fibrotic process has only begun to be understood. Plasmacytoid dendritic cells in particular have been implicated due to their high production of type I interferon as well as other cytokines and chemokines, including the pro-inflammatory and anti-angiogenic CXCL4. Furthermore, a deeper understanding of human and mouse DC biology has clarified their identification and function in different tissues, and novel DC subsets have only recently been discovered. In this review, we highlight key findings and recent advances exploring DC role in the pathogenesis of SSc and other related autoimmune diseases, and consideration of their potential use as targeted therapy in SSc.

T Helper Cells in the Immunopathogenesis of Systemic Sclerosis – Current Trends

Systemic sclerosis (SSc) is a chronic progressive autoimmune disease characterized by skin and multiorgan involvement with alterations in both the innate and adaptive immunities. The hallmark of the disease is widespread fibrosis engaging the skin and multiple internal organs, as well as the musculoskeletal system. There is mounting evidence that T cells are key players in the pathogenesis of scleroderma. The current review discusses the role of the different T helper (Th) lymphocyte subsets in the processes of inflammation and fibrosis, characteristics for the pathogenesis of the disease. Cytokines produced by Th cell populations have a major effect on endothelial cells and fibroblasts in the context of favoring/inhibiting the vasculopathy and the fibrosis spread. The Th2 pro-fibrotic cytokines IL-4 and IL-13 have been shown to induce collagen synthesis by fibroblasts, whereas IFN-γ demonstrates an inhibitory effect. Increased Th17 cells are present in the scleroderma skin infiltrates. The combination of IL-17, IFN-γ and TGF-β levels in CD45RO and CD45RA cells from patients with SSc is useful to distinguish between the limited and the diffuse phenotype of the disease. There are accumulating data for functional and numerical alterations in the Tregs in SSc. High levels of TNF-α which might reduce the suppressive ability of Tregs have been described. According to some studies, the number of Tregs in scleroderma skin biopsies has been decreased against the normal absolute number of Tregs in peripheral blood of the same patients, which suggests suppressed immunomodulatory response. Other studies reported increased frequency of Tregs in peripheral blood of patients with systemic sclerosis and established a correlation with disease activity. The main immunological challenge remains the identification of the trigger of the autoimmune response in SSc, the causes for preferential Th2-type cell responses and the immunological differences between the diffuse and the limited cutaneous form of the disease.

Analysis of killer cell immunoglobulin-like receptors (KIRs) and their HLA ligand genes polymorphisms in Iranian patients with systemic sclerosis

Genetic factors have a great role in the pathogenesis of autoimmune diseases by cooperating with environmental stimuli. Killer immunoglobulin-like receptors (KIRs) are cell surface proteins on NK cells whose association with major histocompatibility complex-I regulates their killing function. The aim of this study was to provide information on the possible association between KIR and human leukocyte antigen (HLA) genes with systemic sclerosis disease in Iranian population. A total of 279 systemic sclerosis patients and 451 healthy controls were enrolled in this case-control study in order to determine the presence or absence of 19 KIR genes and 6 specific HLA class I ligands. DNA was analyzed by polymerase chain reaction using the specific sequence primer method (PCR-SSP). Among 11 discovered KIR genotypes, 6 genotypes showed a considerable role and 4 genotypes could preclude the risk of systemic sclerosis (SSc) disease. The gene-gene interactions were also analyzed, and significant confounding effects were seen between involved genes in these two combinations: "KIR3DL1; HLA-BW4-Thr80" and "KIR3DL1 -HLA-BW4-A1." None of single KIR genes showed significant effect on the risk of SSc. We conclude that there is an important relationship between KIR genes and their HLA ligands with incidence rate of systemic sclerosis in Iranian population. The powerful role of a number of discovered KIR/HLA compounds such as activating KIR genotype 3 and HLA-BW4-A1 confirmed the provocative hypothesis of the interplay between activating or inhibitory KIR genes with HLA ligands as a critical index of systemic sclerosis predisposition.

Genomic and genetic studies of systemic sclerosis: A systematic review

Systemic sclerosis is an autoimmune rheumatic disease characterised by fibrosis, vasculopathy and inflammation. The exact aetiology of SSc remains unknown but evidences show that various genetic factors may be involved. This review aimed to assess HLA alleles/non-HLA polymorphisms, microsatellites and chromosomal abnormalities that have thus far been associated with SSc. PubMed, Embase and Scopus databases were searched up to July 29, 2015 using a combination of search-terms. Articles retrieved were evaluated based on set exclusion and inclusion criteria. A total of 150 publications passed the filters. HLA and non-HLA studies showed that particular alleles in the HLA-DRB1, HLA-DQB1, HLA-DQA1, HLA-DPB1 genes and variants in STAT4, IRF5 and CD247 are frequently associated with SSc. Non-HLA genes analysis was performed using the PANTHER and STRING₁₀ databases. PANTHER classification revealed that inflammation mediated by chemokine and cytokine, interleukin and integrin signalling pathways are among the common extracted pathways associated with SSc. STRING₁₀ analysis showed that NFKB1, CSF3R, STAT4, IFNG, PRL and ILs are the main "hubs" of interaction network of the non-HLA genes associated with SSc. This study gathers data of valid genetic factors associated with SSc and discusses the possible interactions of implicated molecules.

Genetics of systemic sclerosis: recent advances

Purpose of review

Large-scale and follow-up genetic association studies in systemic sclerosis (SSc) have implicated over 40 regions in disease risk, 15 of which with robust associations. Nevertheless, the causal variants and the functional mechanisms underlying the genetic associations remain elusive, and the reasons for the higher disease burden in African Americans unknown. Incorporating tools from diverse fields is beginning to unveil the role of genetic diversity and regulatory variation in SSc susceptibility. This review will summarize recent advances in SSc genetics, including autoimmune disease overlap, evidence of natural selection, and current progress towards the dissection of the functional role of associated risk variants.

Recent findings

In the past year, multiple large-scale studies reported novel strong and suggestive SSc associations. These results, coupled with the regions shared with other autoimmune diseases, emphasize the role of dysregulation of immune pathways as a key causative factor in SSc pathogenesis. Strong evidence implicates natural selection as a mechanism contributing to the maintenance of some of these SSc alleles in the population. Studies integrating genomic, transcriptomic, and epigenomic datasets in specific cell types to identify causal autoimmune disease variants are emerging.

Summary

The identification and comprehensive understanding of the factors and mechanisms contributing to SSc will contribute to improved diagnosis and disease management.

Rediscovering Pertussis

Pertussis, caused by Bordetella (B.) pertussis, a Gram-negative bacterium, is a highly contagious airway infection. Especially in infants, pertussis remains a major health concern. Acute infection with B. pertussis can cause severe illness characterized by severe respiratory failure, pulmonary hypertension, leucocytosis, and death. Over the past years, rising incidence rates of intensive care treatment in young infants were described. Due to several virulence factors (pertussis toxin, tracheal cytotoxin, adenylate cyclase toxin, filamentous hemagglutinin, and lipooligosaccharide) that promote bacterial adhesion and invasion, B. pertussis creates a unique niche for colonization within the human respiratory tract. The resulting long-term infection is mainly caused by the ability of B. pertussis to interfere with the host's innate and adaptive immune system. Although pertussis is a vaccine-preventable disease, it has persisted in vaccinated populations. Epidemiological data reported a worldwide increase in pertussis incidence among children during the past years. Either acellular pertussis (aP) vaccines or whole-cell vaccines are worldwide used. Recent studies did not detect any differences according to pertussis incidence when comparing the different vaccines used. Most of the currently used aP vaccines protect against acute infections for a period of 6-8 years. The resurgence of pertussis may be due to the lack of herd immunity caused by missing booster immunizations among adolescents and adults, low vaccine coverages in some geographic areas, and genetic changes of different B. pertussis strains. Due to the rising incidence of pertussis, probable solution strategies are discussed. Cocooning strategies (vaccination of close contact persons) and immunizations during pregnancy appear to be an approach to reduce neonatal contagiousness. During the past years, studies focused on the pathway of the immune modulation done by B. pertussis to provide a basis for the identification of new therapeutic targets to enhance the host's immune response and to probably modulate certain virulence factors.

Frequency of circulating topoisomerase-I-specific CD4 T cells predicts presence and progression of interstitial lung disease in scleroderma

Background

Scleroderma is an antigen-driven T cell-mediated autoimmune disease. Presence of anti-topoisomerase-I antibodies is associated with pulmonary fibrosis and predicts increased mortality. Characterization of autoreactive T lymphocytes may shed light on disease pathogenesis and serve as a biomarker for disease activity. Here, we aimed to quantify and functionally characterize circulating topoisomerase I (topo-I)-specific CD4+ T cells and to define their association with presence and progression of interstitial lung disease (ILD) in patients with scleroderma.

Methods

Using flow cytometry, circulating topo-I-reactive CD4+ T cells were identified by the expression of specific activation markers (CD154 and CD69) upon stimulation with purified topo-I and quantified in 27 SSc patients and 4 healthy donors (HD). Polarization of autoreactive T cells (Th1, Th2, Th17, Th1–17) was defined using surface expression of specific chemokine receptors. Presence and progression of ILD were determined using high-resolution chest CT and pulmonary function tests.

Results

Topo-I-reactive CD4+ T cells were found in all topo-I-positive patients compared to one topo-I-negative subject and no HD. Topo-I-specific CD4+ T cells exhibited a distinct Th17 polarized phenotype. Autoreactive T cells were significantly increased in subjects with evidence of ILD and were quantitatively associated with the decline of lung volumes.

Conclusions

Topo-I-specific T cells can be reliably quantified in the peripheral blood of patients with scleroderma, exhibit a pro-inflammatory Th17 phenotype, and predict progression of ILD.

Electronic supplementary material

The online version of this article (doi:10.1186/s13075-016-0993-2) contains supplementary material, which is available to authorized users.

Genetic Susceptibility to Interstitial Lung Disease Associated with Systemic Sclerosis

Systemic sclerosis (SSc) is a connective tissue disease that is characterized by tissue fibrosis, microvasculopathy, and autoimmunity. Interstitial lung disease (ILD) is a common complication of SSc and is one of the frequent causes of mortality in SSc. Although the exact etiology of SSc remains unknown, clinical and experimental investigations have suggested that genetic and environmental factors are relevant to the pathogenesis of SSc and SSc-ILD. More than 30 genes have been identified as susceptibility loci for SSc, most of which are involved in immune regulation and inflammation. It is thought that the key pathogenesis of SSc-ILD is caused by the release of profibrotic mediators such as transforming growth factor β1 and connective tissue growth factor from lung cells induced by a persistent damage. This review presents the genetic susceptibility to SSc-ILD, including human leukocyte antigen and non-human leukocyte antigen genes, especially focusing on connective tissue growth factor.

Association of IL23R polymorphism (rs7530511) with intracerebral hemorrhage in Korean population

Cytokines and their receptors are involved in the development of intracerebral hemorrhage (ICH). Interleukin 23 receptor (IL23R) has been implicated in numerous inflammatory and immune diseases. In this study, we investigated whether single nucleotide polymorphisms (SNPs) of IL23R were associated with the susceptibility of ICH in Korean population. Two coding region SNPs (cSNPs) [rs1884444 (Gln3His), and rs7530511 (Leu310Pro)] were selected, and genotyped in 167 ICH patients and 377 control subjects using direct sequencing. Of two cSNPs, only rs7530511 showed a significant association with ICH in codominant model (C/T vs. C/C, P = 0.017, odds ratio (OR) 4.15, 95 % confidential interval (CI) 1.27-13.58). Allele frequency analysis also revealed that rs7530511 was associated with ICH (P = 0.023, OR 3.68, 95 % CI 1.19-11.32). The frequency of the T allele was increased in the ICH patients, compared to the control subjects. These results suggest that IL23R may contribute to the development of ICH.

The role of the acquired immune response in systemic sclerosis

Profound alterations characterize the adaptive immune response in systemic sclerosis, and several layers of evidence support a prominent role exerted by immune cellular effectors and humoral mediators in the pathogenesis of this disease. These include (i) the presence of oligoclonal T cells in tissues undergoing fibrosis consistent with (auto)antigen-specific recruitment, (ii) the preferential expansion of polarized CD4+ and CD8+ T cells producing pro-fibrotic cytokines such as IL-4 and IL-13, (iii) the presence of increased number of cells producing mediators belonging to the IL-17 family, including IL-22, which may drive and participate in inflammatory pathways involving epithelial cells as well as fibroblasts, (iv) the deficient or redirected function of T regulatory cells favoring fibrosis, and (v) the enhanced expression of CD19 and CD21 on naïve B cells, and the upregulation of co-stimulatory molecules in mature B cells, which together with the increased levels of B cell activating factor (BAFF) underlie the propensity to an exaggerated humoral response possibly favoring fibrogenesis. Despite all the progress made in understanding the features of the aberrant immune response in scleroderma, it remains unclear whether the activation of immune effector pathways ultimately drives the disease pathogenesis or rather represents a defective attempt to limit or even reverse excessive extracellular matrix deposition and progressive vasculopathy, the main hallmarks of this disease.

Pathogenesis of Systemic Sclerosis

Systemic scleroderma (SSc) is one of the most complex systemic autoimmune diseases. It targets the vasculature, connective tissue-producing cells (namely fibroblasts/myofibroblasts), and components of the innate and adaptive immune systems. Clinical and pathologic manifestations of SSc are the result of: (1) innate/adaptive immune system abnormalities leading to production of autoantibodies and cell-mediated autoimmunity, (2) microvascular endothelial cell/small vessel fibroproliferative vasculopathy, and (3) fibroblast dysfunction generating excessive accumulation of collagen and other matrix components in skin and internal organs. All three of these processes interact and affect each other. The disease is heterogeneous in its clinical presentation that likely reflects different genetic or triggering factor (i.e., infection or environmental toxin) influences on the immune system, vasculature, and connective tissue cells. The roles played by other ubiquitous molecular entities (such as lysophospholipids, endocannabinoids, and their diverse receptors and vitamin D) in influencing the immune system, vasculature, and connective tissue cells are just beginning to be realized and studied and may provide insights into new therapeutic approaches to treat SSc.

Genetics, Epigenetics, and Genomics of Systemic Sclerosis

Systemic sclerosis (SSc) is a complex autoimmune disease that occurs in a genetically susceptible host. Genetic studies performed so far reveal that multiple genetic loci contribute to disease susceptibility in SSc. The purpose of this review is to discuss the current knowledge of genetics in SSc by exploring the observational evidence, the different genetic studies, and their modalities as well as the most relevant genes discovered by these. The importance of gene expression variation and the different mechanisms that govern it, including the recently discovered field of epigenetics, are also explored, with an emphasis on microRNA.

Update on etiopathogenesis of systemic sclerosis

Systemic Sclerosis (SSc) is an autoimmune disease of multifactorial etiology, triggered by a combination of genetic and environmental factors. Its varied clinical expression results from the complex physiopathogenic interaction of three main elements: proliferative vasculopathy, immune dysregulation and abnormal deposition and remodeling of the extracellular matrix (ECM), of which the characteristic disease fibrosis is the result. Early physiopathogenic events appear to be endothelial injury and imbalance in vascular repair with the activation of endothelial cells, the immune system and platelets, with the release of multiple mediators such as TH2 proinflammatory cytokines and growth factors, triggering a sequence of simultaneous or cascading events that involve several intracellular signaling pathways. The most important result of these events is the hyperactivation of fibroblasts, the main effector cells of fibrosis, which will then produce large amounts of ECM constituents and secrete multiple growth factors and cytokines that perpetuate the process. In this article we review the main factors potentially involved in the etiology of SSc and reexamine the current knowledge about the most important mechanisms involved in the development of lesions that are characteristic of the disease. A better understanding of these physiopathogenic mechanisms will help identify potential therapeutic targets, which may result in advances in the management of this complex and debilitating disease.

Systemic Sclerosis is a Complex Disease Associated Mainly with Immune Regulatory and Inflammatory Genes

Systemic sclerosis (SSc) is a fibrotic and autoimmune disease characterized clinically by skin and internal organ fibrosis and vascular damage, and serologically by the presence of circulating autoantibodies. Although etiopathogenesis is not yet well understood, the results of numerous genetic association studies support genetic contributions as an important factor to SSc. In this paper, the major genes of SSc are reviewed. The most recent genome-wide association studies (GWAS) are taken into account along with robust candidate gene studies. The literature search was performed on genetic association studies of SSc in PubMed between January 2000 and March 2014 while eligible studies generally had over 600 total participants with replication. A few genetic association studies with related functional changes in SSc patients were also included. A total of forty seven genes or specific genetic regions were reported to be associated with SSc, although some are controversial. These genes include HLA genes, STAT4, CD247, TBX21, PTPN22, TNFSF4, IL23R, IL2RA, IL-21, SCHIP1/IL12A, CD226, BANK1, C8orf13-BLK, PLD4, TLR-2, NLRP1, ATG5, IRF5, IRF8, TNFAIP3, IRAK1, NFKB1, TNIP1, FAS, MIF, HGF, OPN, IL-6, CXCL8, CCR6, CTGF, ITGAM, CAV1, MECP2, SOX5, JAZF1, DNASEIL3, XRCC1, XRCC4, PXK, CSK, GRB10, NOTCH4, RHOB, KIAA0319, PSD3 and PSOR1C1. These genes encode proteins mainly involved in immune regulation and inflammation, and some of them function in transcription, kinase activity, DNA cleavage and repair. The discovery of various SSc-associated genes is important in understanding the genetics of SSc and potential pathogenesis that contribute to the development of this disease.

Prevalence of anti-RNA polymerase III antibodies in systemic sclerosis: New data from a French cohort and a systematic review and meta-analysis

OBJECTIVE

Studies assessing the prevalence of anti-RNA polymerase III (anti-RNAP III) antibodies in systemic sclerosis (SSc) have yielded a wide range of results. The aim of the present study was to describe a new SSc cohort tested for presence of anti-RNAP III and perform a systematic review and meta-analysis to assess the prevalence of anti-RNAP III in patients worldwide and the potential factors of variability.

METHODS

Seropositivity for anti-RNAP III was evaluated in a French cohort of SSc patients. A systematic review of the literature was carried out in PubMed and EMBase. Meta-analysis was performed using available data on prevalence, clinical characteristics of SSc patients, and the types of assays used for anti-RNAP III testing.

RESULTS

One hundred thirty-three French SSc patients were tested for anti-RNAP III, and a prevalence of 6-9% was found in these patients. Thirty studies representing a total population of 8,437 SSc patients were included in the meta-analysis. Prevalence of anti-RNAP III in this population was highly variable (range 0-41%). The overall pooled prevalence of anti-RNAP III was 11% (95% confidence interval 8-14), but heterogeneity was high among studies (I(2) = 93%, P < 0.0001). Geographic factors such as continent or country of study origin partially explained this heterogeneity and correlated with the prevalence. No other baseline SSc characteristics were significantly correlated with the prevalence of anti-RNAP III.

CONCLUSION

Data on our new cohort and our meta-analysis of the literature confirmed that anti-RNAP III prevalence in SSc varies among centers. Geographic factors were significantly associated with prevalence, which underscores the probable implication that genetic background and environmental factors play a role. Heterogeneity among studies remained largely unexplained.

IL-17: a new actor in IFN-driven systemic autoimmune diseases

Systemic autoimmune diseases such as systemic lupus erythematosus are type I IFN-driven diseases with exaggerated B-cell responses and autoantibody production. Th17 cells, a T-helper-cell subset with high inflammatory capacity, was initially discovered and characterized in the context of experimental autoimmune encephalomyelitis - an animal model of multiple sclerosis. There is now emerging evidence that Th17 cells, and more generally IL-17 and IL-17-producing cells, may play a role in the pathogenesis of type I IFN-driven systemic autoimmune diseases such as lupus. Here, we review the different studies suggesting a role for IL-17 and IL-17-producing cells in systemic autoimmune diseases, both in humans and in animal models, and we consider the possible mechanisms by which these cells may contribute to disease. We also discuss the hypothesis that type I IFN and IL-17 act in concert to sustain and amplify autoimmune and inflammatory responses, making them a dangerous combination involved in the pathogenesis of systemic autoimmune diseases.

Genetics of scleroderma: implications for personalized medicine?

Significant advances have been made in understanding the genetic basis of systemic sclerosis (scleroderma) in recent years. Can these discoveries lead to individualized monitoring and treatment? Besides robustly replicated genetic susceptibility loci, several genes have been recently linked to various systemic sclerosis disease manifestations. Furthermore, inclusion of genetic studies in design and analysis of drug trials could lead to development of genetic biomarkers that predict treatment response. Future genetic studies in well-characterized systemic sclerosis cohorts paired with advanced analytic approaches can lead to development of genetic biomarkers for targeted diagnostic and therapeutic interventions in systemic sclerosis.

Immunity to the respiratory pathogen Bordetella pertussis

Bordetella pertussis causes whooping cough, a severe respiratory tract infection in infants and children, and also infects adults. Studies in murine models have shown that innate immune mechanisms involving dendritic cells, macrophages, neutrophils, natural killer cells, and antimicrobial peptides help to control the infection, while complete bacterial clearance requires cellular immunity mediated by T-helper type 1 (Th1) and Th17 cells. Whole cell pertussis vaccines (wP) are effective, but reactogenic, and have been replaced in most developed countries by acellular pertussis vaccines (aP). However, the incidence of pertussis is still high in many vaccinated populations; this may reflect sub-optimal, waning, or escape from immunity induced by current aP. Protective immunity generated by wP appears to be mediated largely by Th1 cells, whereas less efficacious alum-adjuvanted aP induce strong antibody Th2 and Th17 responses. New generation aP that induce Th1 rather than Th2 responses are required to improve vaccine efficacy and prevent further spread of B. pertussis.

Primary biliary cirrhosis associated with systemic sclerosis: diagnostic and clinical challenges

Patients with primary biliary cirrhosis (PBC) often have concurrent limited systemic sclerosis (SSc). Conversely, up to one-fourth of SSc patients are positive for PBC-specific antimitochondrial antibodies (AMA). The mechanisms responsible for the co-occurrence of these diseases are largely unknown. Genetic, epigenetic, environmental, and infectious factors appear to be important for the pathogenesis of the disease, but the hierarchy of events are not well defined. Patients with SSc and PBC have an increased morbidity and mortality compared with the general population, but whether the presence of both diseases in an affected individual worsens the prognosis and/or outcome of either disease is not clear. Some case reports suggested that the presence of SSc in PBC patents is associated with a more favorable prognosis of the liver disease, whereas others report an increased mortality in patients with PBC and SSc compared to patients with PBC alone. This paper discusses the features of patients with PBC-associated SSc. Our aims are to clarify some of the pathogenetic, diagnostic, and clinical challenges that are currently faced in the routine management of these patients. We also intend to provide some practical hints for practitioners that will assist in the early identification of patients with PBC-associated SSc.

Deciphering the genetic background of systemic sclerosis

Systemic sclerosis (SSc) is a severe autoimmune connective tissue disease. Over the years, evidence for a genetic background of SSc susceptibility has clearly accumulated. This article aims to provide an extensive overview of genetics in SSc research. We discuss indicators for a genetic component present in SSc, family studies, chromosomal aberrances, the involvement of the HLA region and multiple candidate genes and, finally, genome-wide association studies.

A GWAS follow-up study reveals the association of the IL12RB2 gene with systemic sclerosis in Caucasian populations

A single-nucleotide polymorphism (SNP) at the IL12RB2 locus showed a suggestive association signal in a previously published genome-wide association study (GWAS) in systemic sclerosis (SSc). Aiming to reveal the possible implication of the IL12RB2 gene in SSc, we conducted a follow-up study of this locus in different Caucasian cohorts. We analyzed 10 GWAS-genotyped SNPs in the IL12RB2 region (2309 SSc patients and 5161 controls). We then selected three SNPs (rs3790567, rs3790566 and rs924080) based on their significance level in the GWAS, for follow-up in an independent European cohort comprising 3344 SSc and 3848 controls. The most-associated SNP (rs3790567) was further tested in an independent cohort comprising 597 SSc patients and 1139 controls from the USA. After conditional logistic regression analysis of the GWAS data, we selected rs3790567 [P(MH)= 1.92 × 10(-5) odds ratio (OR) = 1.19] as the genetic variant with the firmest independent association observed in the analyzed GWAS peak of association. After the first follow-up phase, only the association of rs3790567 was consistent (P(MH)= 4.84 × 10(-3) OR = 1.12). The second follow-up phase confirmed this finding (P(χ2) = 2.82 × 10(-4) OR = 1.34). After performing overall pooled-analysis of all the cohorts included in the present study, the association found for the rs3790567 SNP in the IL12RB2 gene region reached GWAS-level significant association (P(MH)= 2.82 × 10(-9) OR = 1.17). Our data clearly support the IL12RB2 genetic association with SSc, and suggest a relevant role of the interleukin 12 signaling pathway in SSc pathogenesis.

IL-23 in infections, inflammation, autoimmunity and cancer: possible role in HIV-1 and AIDS

The growing family of interleukin (IL)-12-like cytokines produced by activated macrophages and dendritic cells became the important players in the control of infections, development of inflammation, autoimmunity and cancer. However, the role of one of them-heterodimer IL-23, which consists of IL12p40 and the unique p19 subunit in HIV-1 infection pathogenesis and progression to AIDS, represent special interest. We overviewed findings of IL-23 involvement in control of peripheral bacterial pathogens and opportunistic infection, central nervous system (CNS) viral infections and autoimmune disorders, and tumorogenesis, which potentially could be applicable to HIV-1 and AIDS.

Impact of a functional KIR2DS4 allele on heterosexual HIV-1 transmission among discordant Zambian couples

Killer cell immunoglobulin-like receptors (KIRs) and their HLA ligands interact to regulate natural killer (NK) cell function. KIR gene content and allelic variations are reported to influence human immunodeficiency virus (HIV)-1 infection and pathogenesis. We investigated the impact of KIR genes on heterosexual HIV-1 transmission among 566 discordant couples from Lusaka, Zambia. KIR2DS4*001, the only allele of KIR2DS4 known to encode a functional activating receptor, was associated with relatively high viral load for HIV-1 in index (HIV-1 seroprevalent) partners (β [standard error (SE)], .17 [.8] log₁₀; P = .04) and with accelerated transmission of HIV-1 to cohabiting seronegative partners (relative hazard [RH], 2.00; P = .004). The latter association was independent of the direction of transmission (male-to-female or female-to-male), genital ulcers, and carriage of the putative ligand (HLA-Cw*04). No KIR-gene variant in the initially seronegative partners was associated with HIV-1 acquisition or early viral load following seroconversion. Further analysis of NK cell function should clarify the role of KIR2DS4*001 in HIV-1 transmission.

[Cytokines and T cell differentiation in systemic sclerosis]

The physiopathology of systemic sclerosis remains unclear within a complex interaction between vasculopathy, perivascular inflammatory infiltrate, extensive tissue fibrosis and auto-immune manifestations. Chronology between vascular disease and adjacent inflammatory cell infiltration is still not yet clarified. There is growing evidence that T cell activation and its cytokine expression play a key role in vascular impairment occurrence and collagen dysregulation. Nevertheless, cytokine descriptions are mainly limited to blood and tissue measurement and the T cells differentiation analysis restricted to the Th1/Th2 balance. The purpose of this review is to establish an exhaustive cartography of cytokines involved in T cell differentiation, regarding the recent advance in T lymphocyte differentiation, including Th9, Th17, Th22 and regulatory T cells (Treg) pathways. This review will focus on Th17, Th22 and Treg differentiation, corresponding to the equilibrium between inflammation and tolerance. Finally, regarding published results in systemic sclerosis, T cells participation appears to be more a Th1/Th2 co-expression than an exclusive Th1 or Th2 polarization. Also, a possible Th22/Treg imbalance is suggested, leading to a Th22 overexpression and likely to tissue inflammation genesis.

The genetics of systemic sclerosis

Systemic sclerosis (SSc, scleroderma) is an autoimmune disease clinically characterized by progressive fibrosis in the skin and internal organs. While the pathogenesis of SSc is not completely understood, familial studies and genetic studies suggest that SSc is a complex polygenic disease. In the current review, we will discuss recent studies investigating genetic susceptibility to SSc. Candidate gene studies have identified critical immunoregulatory genes and gene regions including BANK1, FAM167A-BLK, IL23R, IRF5, STAT4, TBX21, and TNFSF4 as susceptibility genes for the development of SSc. More recently a genome-wide association study has been performed and identified CD247 (CD3-zeta) as a novel genetic risk factor for the susceptibility to SSc. Together these genetic association studies have substantially advanced our understanding of SSc pathogenesis and form the foundation for future studies seeking to understand the complexities of SSc.