Association study of a polymorphism of the CTGF gene and susceptibility to systemic sclerosis in the Japanese population

Insights into the genetic landscape of systemic sclerosis

Systemic sclerosis (SSc) is a complex autoimmune disease that clinically manifests as progressive fibrosis of the skin and internal organs. Autoimmunity and endothelial dysfunction play important roles in the development of SSc but the causes of SSc remain unknown. Accumulating evidence, first from familial aggregation studies and subsequently from candidate gene association studies and genome wide association studies underscore the crucial contributions of genetics to the development of SSc. The identification of polymorphisms in the HLA region as well as non-HLA loci is important for understanding the risks of developing SSc but can also provide important pathogenic insight in SSc. While not translating into clinic practice yet, understanding the genetic landscape of SSc will hopefully assist in the diagnosis and management of patients with and/or at risk of developing SSc in the future. Herein we review the studies that investigate genetic risks of SSc susceptibility.

Pathogenesis of interstitial lung disease in systemic sclerosis

Interstitial lung disease (ILD) is a frequent important complication of systemic sclerosis (SSc). Factors relevant to aetiopathogenesis of SSc are also central to SSc-ILD. Severity of SSc-ILD is variable but it has a major impact on morbidity and mortality. Factors determining SSc-ILD susceptibility reflect the genetic architecture of SSc and are increasingly being defined. There are aspects linked to immunogenomics and non-immunological genetic factors that may be less conserved and underlie some of the geographical and racial diversity of SSc. These associations may also underlie important links between autoantibody subgroups and patient level risk of SSc-ILD. Examination of blood and tissue samples and observational clinical research together with integrated analysis of in vitro and in vivo preclinical models have elucidated pathogenic mechanisms of SSc-ILD. These have confirmed the potential importance of immune mechanisms in the innate and adaptive immune systemic as well as a significant role for profibrotic pathways especially transforming growth factor beta (TGFbeta) and its regulators and downstream mediators. Recent analysis of clinical trial cohorts as well as integrated and multilevel high dimensional analysis of bio-samples has shed further light on SSc-ILD. This is likely to underpin future advances in stratified and precision medicine for treatment of SSc.

The rs9402373 polymorphism of CTGF gene may not be related to inflammatory bowel disease susceptibility in Chinese population based on ARMS-PCR genotyping

Background

It has been confirmed that the connective tissue growth factor (CTGF) gene rs9402373 polymorphism is associated with fibrotic and inflammatory diseases. However, studies on the relationship between polymorphisms in CTGF rs9402373 and inflammatory bowel disease (IBD) remain rare. Therefore, the aim of this study was to assess the association between the CTGF rs9402373 polymorphism and IBD susceptibility in a Chinese population.

Materials and methods

To establish an amplification refractory mutation system (ARMS) PCR technology for genotyping CTGF gene rs9402373 polymorphism, we designed two specific forward primers for the wild and mutant types by placing the allele-specific nucleotide at the penultimate position of the '3' end of the primer. Then, 10 samples were randomly selected and rechecked by DNA sequencing to verify the accuracy of this method. We further used the established method to detect specimens collected from 191 patients with inflammatory bowel disease, including 120 Crohn's disease (CD) and 71 ulcerative colitis (UC), and 110 healthy Han Chinese individuals.

Results

We successfully established the ARMS-PCR method for genotyping, and the results of 10 randomly selected samples were completely consistent with DNA sequencing. The rs9402373 G allele frequencies in UC and CD cases were 38.03% and 43.75%, respectively, and in controls, they were 41.82%. No significant difference was found in minor allele frequencies between the UC or CD and control groups (P = 0.473, P = 0.676). Genotype analysis demonstrated that there was no relationship between CTGF rs9402373 polymorphism and the risk of IBD regardless of the inheritance mode (P > 0.05).

Conclusions

In this preliminary study, we successfully developed a simple, efficient and cost-effective method for genotyping CTGF rs9402373 polymorphism. The polymorphism may not be related to IBD susceptibility in the Chinese Han population.

Multifunctional regulatory protein connective tissue growth factor (CTGF): A potential therapeutic target for diverse diseases

Connective tissue growth factor (CTGF), a multifunctional protein of the CCN family, regulates cell proliferation, differentiation, adhesion, and a variety of other biological processes. It is involved in the disease-related pathways such as the Hippo pathway, p53 and nuclear factor kappa-B (NF-κB) pathways and thus contributes to the developments of inflammation, fibrosis, cancer and other diseases as a downstream effector. Therefore, CTGF might be a potential therapeutic target for treating various diseases. In recent years, the research on the potential of CTGF in the treatment of diseases has also been paid more attention. Several drugs targeting CTGF (monoclonal antibodies FG3149 and FG3019) are being assessed by clinical or preclinical trials and have shown promising outcomes. In this review, the cellular events regulated by CTGF, and the relationships between CTGF and pathogenesis of diseases are systematically summarized. In addition, we highlight the current researches, focusing on the preclinical and clinical trials concerned with CTGF as the therapeutic target.

Connective Tissue Growth Factor Single Nucleotide Polymorphisms in (Familial) Pulmonary Fibrosis and Connective Tissue Disease Associated Interstitial Lung Disease

PURPOSE

Connective tissue growth factor (CTGF) is an important mediator in fibrotic disease. Single nucleotide polymorphisms (SNPs) in CTGF have been found to be associated with different fibrotic diseases and CTGF protein was found to be upregulated in lung tissue, bronchoalveolar lavage cells, and plasma of idiopathic pulmonary fibrosis (IPF) patients. We investigated whether genetic variants predispose to sporadic IPF (spIPF), familial pulmonary fibrosis (FPF), and connective tissue disease associated ILD (CTD-ILD).

METHODS

In total, 294 patients with spIPF and 294 healthy individuals were genotyped for CTGF rs12526196, rs9402373, rs6918698, and rs9399005. For replication of CTGF rs6918698 findings in pulmonary fibrosis, 128 patients with FPF, 125 with CTD-ILD, and an independent control cohort of 130 individuals were included. Lung tissue of 6 IPF patients was stained for CTGF to assess pulmonary localization.

RESULTS

Of the four SNPs, only the minor allele frequency (MAF) of CTGF rs6918698 deviated between spIPF (MAF 0.41) and controls (MAF 0.47; OR 0.774 (0.615-0.975); p = 0.030). Further comparison of CTGF rs6918698G showed a difference between FPF (MAF 0.33) and controls (MAF 0.48; OR 0.545 (0.382-0.778); p = 0.001), but not with CTD-ILD. CTGF was localized in alveolar and bronchiolar epithelium, alveolar macrophages, myofibroblasts and endothelium and highly expressed in the basal cell layer of sandwich foci.

CONCLUSION

CTGF rs6918698G associates with spIPF and with FPF, but not with CTD-ILD in a Dutch cohort. CTGF is localized in lung tissue involved in IPF pathogenesis. Further research into the role of this SNP on CTGF expression and fibrogenesis is warranted.

Genetic Susceptibility to Systemic Sclerosis in the Greek-Cypriot Population: A Pilot Study

Background: Systemic Sclerosis (SSc), also known as scleroderma, is an autoimmune rheumatic disease, which is clinically subdivided into two major subgroups; limited (lcSSc) and diffuse cutaneous scleroderma (dcSSc). Even though the SSc etiologies remains unclear, some HLA and non-HLA genetic variants have been associated with the disease. Aim: This study was designed to evaluate the associations between several HLA-related genetic variants and SSc in the Greek-Cypriot population. Methods: Forty-one SSc patients and 164 controls were genotyped at 18 selected single nucleotide polymorphisms (SNPs) using restriction fragment length polymorphism analyses, Sanger sequencing, and a multiplex SNaPshot minisequencing assay. Logistic regression analysis under the log-additive model was used to evaluate all possible associations between these SNPs and SSc; nominal statistical significance was assumed at p < 0.05. Results: Associations of SSc with SNPs rs3117230, rs3128930, and rs3128965 within the HLA-DPB1 and HLA-DPB2 regions were observed in the Greek-Cypriot population at the level of p < 0.05. However, none of these associations survived a Bonferroni correction. The direction of the effect is consistent with the direction reported in previous studies. In addition, allele frequencies of the majority of the selected SNPs in the Greek-Cypriot population are similar to those reported in the European population. Conclusion: This study initiates the genetic investigation of SSc in the Greek-Cypriot population, a relatively small newly investigated population. Further investigation with a larger sample size and/or additional SSc susceptibility loci may confirm the association of some of these variants with SSc in the Greek-Cypriot population that could potentially be used for predictive testing.

Evaluation of tear and aqueous humor level, and genetic variants of connective tissue growth factor as biomarkers for early detection of pseudoexfoliation syndrome/glaucoma

Pseudoexfoliation syndrome (PEX) may lead to the development of pseudoexfoliative glaucoma (PEG), a potential cause of irreversible blindness, if left untreated. This type of glaucoma often presents with much higher intraocular pressure (IOP) values than observed in primary open angle glaucoma, and patients are often unaware of their condition. Therefore, early diagnosis is of utmost importance in PEX and PEG. Unfortunately, no valid objective biomarkers are available that can be used for this purpose. The excessive synthesis and deposition of elastic microfibrillar pseudoexfoliation material is observed in the pathophysiology of PEX, therefore, growth factors may play roles in this pathology. Thus, in this study, we sought to determine the roles of phenotypes and genotypes of connective tissue growth factor (CTGF) as objective biomarkers for early diagnosis of PEX and PEG. Thus, we investigated possible associations involving tear and aqueous humor CTGF concentrations and four single nucleotide polymorphisms (SNPs) of the CTGF gene in PEX and PEG. The study was designed as a 2-year case-control study in the Turkish population. Study population was composed of 214 patients with PEG, 214 patients with PEX, and 214 age-matched controls for CTGF SNP analysis. Tear fluid study group consisted of 78 patients with PEG, 77 patients with PEX, and 78 controls. Aqueous humor analysis included 8 patients with PEG, 17 patients with PEX, and 23 controls. Tear fluid was collected using Schirmer strips, and aqueous humor samples were taken during cataract surgery. CTGF concentration was determined by ELISA, and total protein concentration was determined by Bradford assay in tear and aqueous humor samples. PCR followed by restriction fragment length polymorphism analysis was used for genotyping of rs6918698 G/C and rs9399005 C/T, while real-time PCR was used for rs9402373 C/G and rs12526196 T/C. Intraocular pressure, visual field score, mean deviation, and pattern standard deviation parameters were also evaluated. CTGF concentration in tear fluid was significantly higher in PEG patients compared with controls (P = 0.001), while it was lower in PEX patients. Similarly, total protein concentration in tear fluid was significantly increased in PEG patients relative to PEX patients (P = 0.026) and controls (P = 0.004). CTGF concentration in aqueous humor did not differ markedly between the groups, whereas total protein was significantly higher in the PEG group compared with the PEX group (P = 0.012) and controls (P = 0.003). Receiver operating characteristic analysis revealed that total protein in aqueous humor was a robust classifier for evaluating the presence of PEG against controls (Area under the curve = 0.897, P = 0.001). The genotypes of the studied SNPs were not significantly correlated with CTGF concentration in aqueous humor or tear fluid, and did not exhibit significant association with PEG or PEX. In conclusion, this was the first study to investigate tear fluid CTGF concentration in PEX and PEG, which came out not to be a good classifier for PEG or PEX. Total protein level in tear fluid and CTGF SNPs also did not predict PEG or PEX status successfully.

Translational research in pulmonary fibrosis

Pulmonary fibrosis refers to the development of diffuse parenchymal abnormalities in the lung that cause dyspnea, cough, hypoxemia, and impair gas exchange, ultimately leading to respiratory failure. Though pulmonary fibrosis can be caused by a variety of underlying etiologies, ranging from genetic defects to autoimmune diseases to environmental exposures, once fibrosis develops it is irreversible and most often progressive, such that fibrosis of the lung is one of the leading indications for lung transplantation. This review aims to provide a concise summary of the recent advances in our understanding of the genetics and genomics of pulmonary fibrosis, idiopathic pulmonary fibrosis in particular, and how these recent discoveries may be changing the clinical approach to diagnosing and treating patients with fibrotic interstitial lung disease.

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.

Genetic predictors of systemic sclerosis-associated interstitial lung disease: a review of recent literature

The interplay between genetic and environmental factors is likely involved in the pathogenesis of systemic sclerosis (SSc). Interstitial lung disease associated in the context of SSc (SSc-ILD) is associated with significant morbidity, and is the leading cause of death in SSc. The spectrum of SSc-ILD severity is wide, ranging from patients with only limited and inherently stable pulmonary involvement, to those with extensive and progressive pulmonary fibrosis. In order to provide accurate prognostic information for patients, and to initiate appropriate monitoring and treatment regimens, the ability to identify patients at risk of developing severe ILD early in the disease course is crucial. Identification of genetic variants involved in disease pathogenesis can not only potentially provide diagnostic/prognostic markers, but can also highlight dysregulated molecular pathways for therapeutic targeting. A number of genetic associations have been established for susceptibility to SSc, but far fewer studies have investigated genetic susceptibility to SSc-ILD specifically. In this review we present a summary of the studies assessing genetic associations with SSc-ILD.

Association of Polymorphisms in Connective Tissue Growth Factor and Epidermal Growth Factor Receptor Genes With Human Longevity

Growth pathways play key roles in longevity. The present study tested single-nucleotide polymorphisms (SNPs) in the connective tissue growth factor gene (CTGF) and the epidermal growth factor receptor gene (EGFR) for association with longevity. Comparison of allele and genotype frequencies of 12 CTGF SNPs and 41 EGFR SNPs between 440 American men of Japanese ancestry aged ≥95 years and 374 men of average life span revealed association with longevity at the p < .05 level for 2 SNPs in CTGF and 7 in EGFR. Two in CTGF and two in EGFR remained significant after Bonferroni correction. The SNPs of both CTGF and EGFR were in a haplotype block in each respective gene. Haplotype analysis confirmed the suggestive association found by χ2 analysis. We noted an excess of heterozygotes among the longevity cases, consistent with heterozygote advantage in living to extreme old age. No associations of the most significant SNPs were observed in whites or Koreans. In conclusion, the present findings indicate that genetic variation in CTGF and EGFR may contribute to the attainment of extreme old age in Japanese. More research is needed to confirm that genetic variation in CTGF and EGFR contributes to the attainment of extreme old age across human populations.

The status of pulmonary fibrosis in systemic sclerosis is associated with IRF5, STAT4, IRAK1, and CTGF polymorphisms

Pulmonary fibrosis (PF) is one of the leading causes of death in systemic sclerosis (SSc) patients. Although all SSc patients are characterized by autoimmunity, only part of them suffer from PF, suggesting that beside autoimmunity, some additional factors are involved in the initiation of PF in SSc. In this study, we aimed to identify genetic polymorphisms associated with the status of PF in SSc. We performed that an exhaustive search of the PubMed database was performed to identify eligible studies. Then, a comprehensive meta-analysis was performed by comparing PF⁺-SSc and PF^--SSc patients to identify genetic polymorphisms associated with the status of PF in SSc. Among eight SSc-associated susceptibility polymorphisms which were applied for meta-analysis, IRF5 rs2004640 polymorphism (OR 1.12; 95% CI 1.02-1.22, P = 1.39 × 10^-2), STAT4 rs7574865 polymorphism (OR 1.25; 95% CI 1.07-1.47, P = 5.3 × 10^-3), IRAK1 rs1059702 polymorphism (OR 1.20; 95% CI 1.05-1.37, P = 0.007), and CTGF G-945C polymorphism (OR 1.42; 95% CI 1.18-1.71, P = 0.002) are associated with PF status in SSc, while TNFAIP3 rs5029939, CD226 rs763361, CD247 rs2056626, and IRF5 rs10488631 polymorphisms are not. Since IRF5, STAT4, and IRAK1 are important regulatory factors in the control of innate immune responses and CTGF is involved in the synthesis of extracellular matrix, these results suggest a role of the innate immunity and matrix compounds in the pathogenesis of PF in SSc.

Connective Tissue Growth Factor Domain 4 Amplifies Fibrotic Kidney Disease through Activation of LDL Receptor-Related Protein 6

Connective tissue growth factor (CTGF), a matrix-associated protein with four distinct cytokine binding domains, has roles in vasculogenesis, wound healing responses, and fibrogenesis and is upregulated in fibroblasts and myofibroblasts in disease. Here, we investigated the role of CTGF in fibrogenic cells. In mice, tissue-specific inducible overexpression of CTGF by kidney pericytes and fibroblasts had no bearing on nephrogenesis or kidney homeostasis but exacerbated inflammation and fibrosis after ureteral obstruction. These effects required the WNT receptor LDL receptor-related protein 6 (LRP6). Additionally, pericytes isolated from these mice became hypermigratory and hyperproliferative on overexpression of CTGF. CTGF is cleaved in vivo into distinct domains. Treatment with recombinant domain 1, 1+2 (N terminus), or 4 (C terminus) independently activated myofibroblast differentiation and wound healing responses in cultured pericytes, but domain 4 showed the broadest profibrotic activity. Domain 4 exhibited low-affinity binding to LRP6 in in vitro binding assays, and inhibition of LRP6 or critical signaling cascades downstream of LRP6, including JNK and WNT/β-catenin, inhibited the biologic activity of domain 4. Administration of blocking antibodies specifically against CTGF domain 4 or recombinant Dickkopf-related protein-1, an endogenous inhibitor of LRP6, effectively inhibited inflammation and fibrosis associated with ureteral obstruction in vivo Therefore, domain 4 of CTGF and the WNT signaling pathway are important new targets in fibrosis.

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.

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.

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.

An insight into rheumatology in Thailand

Despite the fact that rheumatic diseases constitute a common health care problem in Thailand, improvements in rheumatology education, research and health care are still required. Low numbers of rheumatologists, their uneven distribution, lack of time to perform both clinical and basic research, lack of patient compliance and restricted access to effective medication comprise some of the barriers that need to be overcome to establish rheumatology education, research and care with a Western-country benchmark. The annual academic activities provided by the Thai Rheumatism Association for rheumatologists, general practitioners, allied health professionals and patients can advance only some forms of education and health care. Better cooperation between the Thai Rheumatism Association, the Royal College of Physicians of Thailand, the Ministry of Public Health and the Thai government is needed to improve rheumatology training, care and research in the country.

Immunogenicity and other problems associated with the use of biopharmaceuticals

Biopharmaceuticals are used widely for the treatment of cancer, chronic viral hepatitis, inflammatory, and autoimmune diseases. Biopharmaceuticals such as interferons are well tolerated for the most part with the most common adverse events observed being 'flu-like' symptoms that resolve rapidly after initial treatment. Prolonged treatment is associated, however, with more serious adverse events including leucopenia, thrombocytopenia, and neuropsychiatric effects, which may necessitate dose reduction or even cessation of treatment in some patients. Recombinant growth factors, such as erythropoietin (EPO), granulocyte colony-stimulating factor, or granulocyte macrophage colony-stimulating factor, are for the most part well tolerated, although severe complications have been reported in patients with cancer or chronic kidney disease treated with EPO. Similarly, treatment of patients with cancer with high doses of interleukin-2 is associated with significant toxicity. Treatment of chronic inflammatory diseases, such as rheumatoid arthritis, psoriasis, and Crohn's disease, with antitumor necrosis factor-alpha monoclonal antibodies is associated with an increased risk of granulomatous infections and, in particular, tuberculosis. The monoclonal antibody, natalizumab, that targets alpha4 integrins is effective in the treatment of multiple sclerosis but is associated with the activation of JC virus and development of progressive multifocal leukoencephalopathy. Repeated administration of recombinant proteins can cause a break in immune tolerance in some patients resulting in the production of a polyclonal antibody response that can adversely affect pharmacokinetics and clinical response. In addition, neutralizing antibodies that cross react with nonredundant essential proteins such as EPO can cause severe autoimmune reactions.

Connective tissue growth factor (CTGF) expression modulates response to high glucose

Connective tissue growth factor (CTGF) is an important mediator of fibrosis; emerging evidence link changes in plasma and urinary CTGF levels to diabetic kidney disease. To further ascertain the role of CTGF in responses to high glucose, we assessed the consequence of 4 months of streptozotocin-induced diabetes in wild type (+/+) and CTGF heterozygous (+/−) mice. Subsequently, we studied the influence of glucose on gene expression and protein in mice embryonic fibroblasts (MEF) cells derived from wildtype and heterozygous mice. At study initiation, plasma glucose, creatinine, triglyceride and cholesterol levels were similar between non-diabetic CTGF+/+ and CTGF+/− mice. In the diabetic state, plasma glucose levels were increased in CTGF+/+ and CTGF+/− mice (28.2 3.3 mmol/L vs 27.0 3.1 mmol/L), plasma triglyceride levels were lower in CTGF+/− mice than in CTGF+/+ (0.7 0.2 mmol/L vs 0.5 0.1 mmol/L, p<0.05), but cholesterol was essentially unchanged in both groups. Plasma creatinine was higher in diabetic CTGF+/+ group (11.7±1.2 vs 7.9±0.6 µmol/L p<0.01), while urinary albumin excretion and mesangial expansion were reduced in diabetic CTGF+/− animals. Cortices from diabetic mice (both CTGF +/+ and CTGF +/−) manifested higher expression of CTGF and thrombospondin 1 (TSP1). Expression of nephrin was reduced in CTGF +/+ animals; this reduction was attenuated in CTGF+/− group. In cultured MEF from CTGF+/+ mice, glucose (25 mM) increased expression of pro-collagens 1, IV and XVIII as well as fibronectin and thrombospondin 1 (TSP1). In contrast, activation of these genes by high glucose was attenuated in CTGF+/− MEF. We conclude that induction of Ctgf mediates expression of extracellular matrix proteins in diabetic kidney. Thus, genetic variability in CTGF expression directly modulates the severity of diabetic nephropathy.

Positive association between STAT4 polymorphisms and polymyositis/dermatomyositis in a Japanese population

OBJECTIVES

To investigate associations between signal transducer and activator of transcription 4 (STAT4), one of the most commonly acknowledged genes for the risk of multiple autoimmune diseases, with susceptibility to adult-onset polymyositis/dermatomyositis among Japanese individuals.

METHODS

A single nucleotide polymorphism of STAT4, rs7574865, was genotyped using TaqMan assay in 1143 Japanese individuals. The first set comprised 138 polymyositis/dermatomyositis patients and 289 controls and the second set comprised 322 patients and 394 controls. 460 patients (273 polymyositis and 187 dermatomyositis patients) and 683 controls were genotyped.

RESULTS

rs7574865T conferred a risk of polymyositis/dermatomyositis with an OR of 1.37 (95% CI 1.16 to 1.64; p=4x10(-4); p(corr)=0.0012). Both polymyositis and dermatomyositis exhibited high associations with the rs7574865T allele (polymyositis: OR=1.36, 95% CI 1.11 to 1.67; p=0.0039; p(corr)=0.012; dermatomyositis: OR=1.40, 95% CI 1.10 to 1.78; p=0.0054; p(corr)=0.016). The association between this STAT4 polymorphism and interstitial lung disease (ILD) was also investigated in the first set of polymyositis/dermatomyositis patients (n=138); those with ILD (n=79) bore rs7574865T more frequently compared with controls (OR 1.59, 95% CI 1.10 to 2.28; p=0.013; p(corr)=0.039).

CONCLUSION

This is the first study to show a positive association between a STAT4 polymorphism and polymyositis/dermatomyositis, suggesting that polymyositis/dermatomyositis shares a gene commonly associated with the risk of other autoimmune diseases.

Taking aim at the extracellular matrix: CCN proteins as emerging therapeutic targets

Members of the CCN family of matricellular proteins are crucial for embryonic development and have important roles in inflammation, wound healing and injury repair in adulthood. Deregulation of CCN protein expression or activities contributes to the pathobiology of various diseases - many of which may arise when inflammation or tissue injury becomes chronic - including fibrosis, atherosclerosis, arthritis and cancer, as well as diabetic nephropathy and retinopathy. Emerging studies indicate that targeting CCN protein expression or signalling pathways holds promise in the development of diagnostics and therapeutics for such diseases. This Review summarizes the biology of CCN proteins, their roles in various pathologies and their potential as therapeutic targets.

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.

Lack of CTGF*-945C/G Dimorphism in Thai Patients with Systemic Sclerosis

An association between connective tissue growth factor (CTGF) gene dimorphism at –945 (CTGF*-945C/G) and systemic sclerosis (SSc) has been reported with inconclusive results. We performed this study to determine whether such an association exists among Thai patients with SSc. DNA samples were taken from 50 Thai SSc patients (diffuse SSc in 39 and limited SSc in 11) and 99 healthy controls for determination of CTGF*-945C/G dimorphism by polymerase chain reaction (PCR) using specific oligonucleotide primers. The associations between the genotype frequencies, clinical manifestations and auto-antibodies were determined as well. When compared with the controls, SSc patients had no significantly higher frequencies of the GG genotype (44.0% vs 39.4%, p = 0.60), G allele (63.0% vs 65.2%, p = 0.80) or G phenotype (82.0% vs 90.9%, p = 1.0). There was no association between the presence of the GG genotype and clinical manifestations (pulmonary fibrosis, sclerodactyly, digital pitting scars, telangiectasia and pulmonary arterial hypertension), or the presence of auto-antibodies (anti-Scl-70, anti-SSA/Ro, and anti-RNP). In conclusion, we found no association between CTGF*-945C/G dimorphism and Thai SSc patients.

Connective tissue growth factor (CTGF/CCN2) ELISA: a novel tool for monitoring fibrosis

BACKGROUND

Connective tissue growth factor (CTGF) has been identified as a key factor in the pathogenesis of diseases with significant fibrosis-related complications such as hepatitis, diabetes and renal transplantation. Increasing evidence shows that CTGF levels in plasma, serum and urine have promising biomarker applicability in these disorders.

OBJECTIVE

To present an overview of current knowledge on CTGF in various patient populations and the technical aspects of CTGF measurement by enzyme-linked immunosorbent assay (ELISA).

METHOD

We performed a comprehensive literature search by using electronic bibliographic databases.

CONCLUSION

CTGF is associated with disease severity parameters and outcome in fibrotic disease and may have diagnostic and prognostic values. However, CTGF ELISA needs standardization.

Updating the genetics of systemic sclerosis

PURPOSE OF REVIEW

Systemic sclerosis (SSc) is a connective tissue disease characterized by early generalized microangiopathy, immune system disturbances and massive deposits of collagen and other matrix substances in the connective tissue. Although rare, SSc presents a major medical challenge, being recognized as the most severe connective tissue disorder in terms of its prognosis. Molecular biology has provided unparalleled insight into the susceptibility genes conferring a predisposition to this disease and has improved our understanding of its complex immune pathogenesis. In this review, we focus on recent large candidate gene studies that have included replication and very recent genome-wide approaches.

RECENT FINDINGS

Attention has recently focused on both known and new susceptibility genes. Large studies have revealed various striking associations within the immune system, but associations with vascular or fibrotic factors were found to be weaker or were not replicated. The major histocompatibility complex genes are the predominant genetic region of importance for many autoimmune disorders, including SSc. Candidate gene studies and genome-wide studies have also provided evidence that various autoimmune genes implicated in innate immunity, T-cell differentiation and immune signaling play a critical role in this disease.

SUMMARY

The use of powerful molecular tools has shed light on the nature of the susceptibility genes for SSc and the pathophysiology of this disease. Postgenomic studies are now required to clarify the role of these genes. Improvements in diagnostic and prognostic tools are anticipated in the near future, together with the development of more specific immune therapy.

The CTGF -945GC polymorphism is not associated with plasma CTGF and does not predict nephropathy or outcome in type 1 diabetes

The -945GC polymorphism (rs6918698) in the connective tissue growth factor gene promoter (CTGF/CCN-2) has been associated with end organ damage in systemic sclerosis. Because CTGF is important in progression of diabetic kidney disease, we investigated whether the -945GC polymorphism is associated with plasma CTGF level and outcome in type 1 diabetes.

The study cohort consisted of 448 diabetic nephropathy patients and 419 normoalbuminuric diabetic patients with complete data concerning renal function and cardiovascular characteristics. Genomic DNA was genotyped by a QPCR-based SNP assay. We observed no relation between the -945GC polymorphism and plasma CTGF level, and the genotype frequencies were not different in nephropathy patients vs. normoalbuminuric controls. General and cardiovascular mortality, and renal function decline was similar in patients with CC, CG or GG genotypes.

In conclusion, the -945GC SNP does not affect plasma CTGF levels, incidence and prognosis of diabetic nephropathy, and cardiovascular outcome.

Recent findings on genetics of systemic autoimmune diseases

Association studies of over 1 million SNPs capturing most of the human genome common variation became possible thanks to the information provided by the HapMap International project and the development of high-throughput genotyping technologies at accessible prices. Genome-wide scans analyzing thousands of individuals have now identified most if not all of the major genes involved in susceptibility for several systemic autoimmune diseases. In particular, results for rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), and systemic sclerosis (SSc) are reviewed here. While most genes are shared between diseases, few seem to be unique reflecting that we still are long before knowing all genes, their interactions with other genes and the environment and their impact on biological functions.

Safety, Tolerability, and Immunogenicity of Interferons

Interferons (IFNs) are class II cytokines that are key components of the innate immune response to virus infection. Three IFN sub-families, type I, II, and III IFNs have been identified in man, Recombinant analogues of type I IFNs, in particular IFNα2 and IFNβ1, have found wide application for the treatment of chronic viral hepatitis and remitting relapsing multiple sclerosis respectively. Type II IFN, or IFN gamma, is used principally for the treatment of chronic granulomatous disease, while the recently discovered type III IFNs, also known as IFN lambda or IL-28/29, are currently being evaluated for the treatment of chronic viral hepatitis. IFNs are in general well tolerated and the most common adverse events observed with IFNα or IFNβ therapy are “flu-like” symptoms such as fever, headache, chills, and myalgia. Prolonged treatment is associated with more serious adverse events including leucopenia, thrombocytopenia, increased hepatic transaminases, and neuropsychiatric effects. Type I IFNs bind to high-affinity cell surface receptors, composed of two transmembrane polypeptides IFNAR1 and IFNAR2, resulting in activation of the Janus kinases Jak1 and Tyk2, phosphorylation and activation of the latent cytoplasmic signal transducers and activators of transcription (STAT1) and STAT2, formation of a transcription complex together with IRF9, and activation of a specific set of genes that encode the effector molecules responsible for mediating the biological activities of type I IFNs. Systemic administration of type I IFN results in activation of IFN receptors present on essentially all types of nucleated cells, including neurons and hematopoietic stem cells, in addition to target cells. This may well explain the wide spectrum of IFN associated toxicities. Recent reports suggest that certain polymorphisms in type I IFN signaling molecules are associated with IFN-induced neutropenia and thrombocytopenia in patients with chronic hepatitis C. IFNγ binds to a cell-surface receptor composed of two transmembrane polypeptides IFGR1 and IFGR2 resulting in activation of the Janus kinases Jak1 and Jak2, phosphorylation of STAT1, formation of STAT1 homodimers, and activation of a specific set of genes that encode the effector molecules responsible for mediating its biological activity. In common with type I IFNs, IFNγ receptors are ubiquitous and a number of the genes activated by IFNγ are also activated by type I IFNs that may well account for a spectrum of toxicities similar to that associated with type I IFNs including “flu-like” symptoms, neutropenia, thrombocytopenia, and increased hepatic transaminases. Although type III IFNs share the major components of the signal transduction pathway and activate a similar set of IFN-stimulated genes (ISGs) as type I IFNs, distribution of the IFNλ receptor is restricted to certain cell types suggesting that IFNλ therapy may be associated with a reduced spectrum of toxicities relative to type I or type II IFNs. Repeated administration of recombinant IFNs can cause in a break in immune tolerance to self-antigens in some patients resulting in the production of neutralizing antibodies (NABs) to the recombinant protein homologue. Appearance of NABs is associated with reduced pharmacokinetics, pharmacodynamics, and a reduced clinical response. The lack of cross-neutralization of IFNβ by anti-IFNα NABs and vice versa, undoubtedly accounts for the apparent lack of toxicity associated with the presence of anti-IFN NABs with the exception of relatively mild infusion/injection reactions.

Association between a CTGF gene polymorphism and systemic sclerosis in a French population

OBJECTIVE

Systemic sclerosis (SSc) is a life-threatening autoimmune disease characterized by chronic fibrosis of the skin and internal organs. Connective tissue growth factor (CTGF) is believed to be a primary mediator of chronic fibrosis. We assessed the possible association between 7 single-nucleotide polymorphisms (SNP) in the CTGF gene and scleroderma in a French population (registration number 2006/0182).

METHODS

We conducted a case-control study with 241 scleroderma patients and 269 controls. Seven SNP were genotyped using the TaqMan system. Univariate and multivariate analyses were performed. In silico electrophoretic mobility shift assay (EMSA), and reverse transcriptase polymerase chain reaction analyses were done to assess the effect of the SNP on CTGF gene expression.

RESULTS

The frequency of the rs9399005TT genotype was significantly lower in SSc patients than in controls. This association remained significant after adjustment for gender. An association was detected between the rs9399005 and the diffuse and limited cutaneous forms. Multivariate analysis between SSc patients and controls taking into account all 7 SNP and sex revealed that only sex and the rs9399005 SNP were associated with disease. DNA analysis by EMSA indicated that the T allele bound nuclear factors that were also bound by the C allele. The binding affinity was higher for the T allele. Analysis of the human database and experiments with human hepatocyte cell line indicated the existence of an alternative transcript containing the rs9399005 polymorphism in its 3'UTR region. In silico analysis indicated that this polymorphism may alter the structure of CTGF messenger RNA.

CONCLUSION

These findings suggest that CTGF gene polymorphisms may contribute to susceptibility to scleroderma.