TGF-β-mediated downregulation of microRNA-196a contributes to the constitutive upregulated type I collagen expression in scleroderma dermal fibroblasts

A functional variant of pre-miRNA-196a2 confers risk for Behcet's disease but not for Vogt-Koyanagi-Harada syndrome or AAU in ankylosing spondylitis

This study aimed to investigate the predisposition of common pre-miRNA SNPs with Behcet's disease (BD), Vogt-Koyanagi-Harada (VKH) syndrome and acute anterior uveitis (AAU) associated with ankylosing spondylitis (AS). A two-stage association study was carried out in 859 BD, 400 VKH syndrome, 209 AAU(+)AS(+) patients and 1,685 controls all belonging to a Chinese Han population. Genotyping, the expression of miR-196a and Bach1 (the target gene of miR-196a), cell proliferation, cytokine production were examined by PCR-RFLP, real-time PCR, CCK8 and ELISA. In the first stage study, the results showed significantly increased frequencies of the miR-196a2/rs11614913 TT genotype and T allele in BD patients (adjusted P(c) = 0.024, OR = 1.63; adjusted P(c) = 5.4 × 10(-3), OR = 1.45, respectively). However, no significant association of the tested SNPs with VKH and AAU(+)AS(+) patients was observed. The second stage and combined studies confirmed the association of rs11614913 with BD (TT genotype: adjusted P(c) = 6×10(-5), OR = 1.53; T allele: adjusted P(c) = 8×10(-6), OR = 1.35; CC genotype: adjusted P(c) = 0.024, OR = 0.68). A stratified analysis showed an association of the rs11614913 TT genotype and T allele with the arthritis subgroup of BD (P(c) = 5.3 × 10(-3), OR = 1.89; P(c) = 0.015, OR = 1.56, respectively). Functional experiments showed a decreased miR-196a expression, an increased Bach1 expression and an increased production of IL-1β and MCP-1 in TT cases compared to CC cases (P = 0.023, P = 0.0073, P = 0.012, P = 0.002, respectively). This study shows that a functional variant of miR-196a2 confers risk for BD but not for VKH syndrome or AAU(+)AS(+) by modulating the miR-196a gene expression and by regulating pro-inflammatory IL-1β and MCP-1 production.

Alteration of circulating miRNAs in SSc: miR-30b regulates the expression of PDGF receptor β

OBJECTIVE

Although several miRNAs have been shown to regulate autoimmune pathogenesis by affecting lymphocyte function, the roles of miRNAs in the pathogenesis of SSc remain unclear. Therefore the purpose of this study was to identify miRNAs that play a role in the pathogenesis of SSc by quantitative PCR screening of serum miRNAs.

METHODS

Ninety-five miRNAs that were predicted to target SSc-related genes [IL-4, TGF-β, CTGF, PDGF-B, PDGF receptor (PDGFR) α/β and COL1A2) by in silico analyses were selected. The expression of these miRNAs in sera of SSc patients and healthy controls was measured by quantitative PCR. Involvement of miR-30b, which was most strongly down-regulated in SSc patients, in the regulation of PDGFR-β expression was examined by transfection experiments and 3'-untranslated region (3'-UTR) target luciferase assays. The expression of miR-30b in skin was evaluated in a bleomycin-induced dermal fibrosis model in mice and in SSc patients.

RESULTS

Nineteen of 95 miRNAs were significantly decreased in the sera of SSc patients. Among them, miR-30b was most strongly down-regulated in SSc patients (P = 0.00006) and the levels of miR-30b were inversely correlated with modified Rodnan skin scores. Transfection of a miR-30b mimic repressed PDGFR-β expression in dermal fibroblasts and the activity of a luciferase reporter containing 3'-UTR of PDGFR-β. Moreover, the expression of miR-30b was down-regulated in bleomycin-treated sclerotic skin and in affected skin in SSc patients.

CONCLUSION

Down-regulation of miR-30b might be involved in the pathogenesis of SSc.

Detection of hair-microRNAs as the novel potent biomarker: evaluation of the usefulness for the diagnosis of scleroderma

BACKGROUND

Serum microRNA levels are known as useful biomarkers for various diseases. Recent publication has indicated the existence of microRNAs in hair roots and hair shafts.

OBJECTIVE

In this study, we evaluated several methods for the extraction of hair microRNAs, and their usefulness for the diagnosis of scleroderma.

METHODS

A single hair root and 5 pieces of hair shafts were obtained from the occiput of each individual of 11 scleroderma patients and 13 normal subjects at the time of serum sampling. microRNA extraction from sera or hair roots was performed with commercially available kits. microRNAs were extracted from hair shafts using four different methods. microRNA expression was evaluated by PCR array and real-time PCR.

RESULTS

We demonstrated microRNAs in hair roots and hair shafts were detectable and quantitative using our method. We found the difference of microRNA levels in hair roots and hair shafts obtained from different places of head in each individual were within 2-fold, indicating the reproducibility of hair microRNA levels by our method. PCR array revealed microRNAs from sera, hair roots and hair shafts have different expression pattern, and can be independent biomarkers. Serum and hair root miR-196a levels were not significantly changed in scleroderma patients, while we found miR-196a levels in hair shafts were significantly decreased in scleroderma patients compared to those in normal subjects (p<0.05).

CONCLUSION

Hairs are more accessible than sera among human samples. microRNAs levels in hair roots or hair shafts may become effective and independent biomarkers.

microRNA-mediated regulation of innate immune response in rheumatic diseases

miRNAs have been shown to play essential regulatory roles in the innate immune system. They function at multiple levels to shape the innate immune response and maintain homeostasis by direct suppression of the expression of their target proteins, preferentially crucial signaling components and transcription factors. Studies in humans and in disease models have revealed that dysregulation of several miRNAs such as miR-146a and miR-155 in rheumatic diseases leads to aberrant production of and/or signaling by inflammatory cytokines and, thus, critically contributes to disease pathogenesis. In addition, the recent description of the role of certain extracellular miRNAs as innate immune agonist to induce inflammatory response would have direct relevance to rheumatic diseases.

Targeted therapies for systemic sclerosis

Pathogenic processes that underlie the development and progression of systemic sclerosis (SSc) are being defined in preclinical, clinical and genetic studies. Important evidence of interplay between the vasculature, connective tissue and specialized epithelial structures is emerging, and abnormalities of both the innate and adaptive immune systems have been identified. In this context, information regarding pivotal mediators, pathways or cell types that could be targets for therapeutic intervention, and that might offer potential for true disease modification, is accruing. Precedent for the regression of some aspects of the pathology has been set in clinical studies showing that potential exists to improve tissue structure and function as well as to prevent disease progression. This article reviews the concept of targeted therapies and considers potential pathways and processes that might be attenuated by therapeutic intervention in SSc. As well as improving outcomes, such approaches will undoubtedly provide information about pathogenesis. The concept of translational medicine is especially relevant in SSc, and we anticipate that the elusive goal of an effective antifibrotic treatment will emerge from one of the several clinical trials currently underway or planned in this disease. Therapeutic advances in SSc would have implications and potential beyond autoimmune rheumatic diseases.

Fibrosing connective tissue disorders of the skin: molecular similarities and distinctions

A variety of fibrosing connective tissue disorders of the skin have been described. They all share a characteristic activation of fibroblasts resulting in excessive production and deposition of extracellular matrix whereas their etiologies, incidence rates and clinical appearances differ dramatically in part. As effective treatment options are still not on hand, the understanding of cutaneous fibrogenesis needs to be improved. This review focuses on the molecular differences and similarities of the major fibrosing skin disorders namely systemic sclerosis, localized scleroderma, keloid and hypertrophic scars, Eosinophilic fasciitis, Lichen sclerosus and graft-versus-host-disease. Abnormalities in ECM turnover and the impact of matrix-metalloproteases were closely examined. It could be concluded, that besides increased collagen synthesis, modified ECM degradation is an as important factor in cutaneous fibrogenesis. The influence of immune components such as HLA haplotypes and the production of auto-antibodies is crucial for some of the diseases, but not decisive for skin fibrosis in general. A great number of cytokines was reported to be differentially regulated in the respective disorders among whom the components of the gp130/STAT3 signaling pathway seem to be of pivotal importance. Furthermore, the role of miRNAs in the pathogenesis of fibrosing connective tissue diseases of the skin was analyzed according to the current state of knowledge. In summary, this review gives an explicit overview of the various molecular mechanisms leading to fibrosis in the skin and the underlying connective tissue and reveals the most promising targets for future therapeutic approaches.

Systemic sclerosis: genetics and epigenetics

Systemic sclerosis (SSc) is an autoimmune disease characterized by immune abnormalities, vascular obliteration, excessive extracellular matrix deposition, and fibrosis of the skin and/or internal organs. To date, the exact etiology of this complicated disease remains unknown. Over the past few years, however, the role of genetic susceptibility and epigenetic modifications caused by environmental factors have been intensively studied in relation to the pathogenesis of this disease, and important advances have been made. This review focuses on the recent progress in the field of SSc research, including HLA and non-HLA susceptibility genes identified in genome-wide association studies (GWAS), and aberrant epigenetic modifications of gene loci associated with SSc. HLA genes most closely linked with SSc susceptibility include HLA-A, -B, -C, -DR, -DP and -DQ. A large number of non-HLA genes were also reported. It has also been noted that different genetic variants can be linked to specific clinical patterns. Finally, DNA demethylation of regulatory genes (eNOS, CD40L and CD70), therapeutic effects associated with Trichostatin A (TSA) treatment, and abnormal expression of a large spectrum of microRNAs (miR-21, -31, -146, -503, -145, -29b, etc.) are all observed in SSc. Overall, the findings presented in this review illustrate how both genetic and epigenetic aberrations play important roles in the development of SSc; however, several unanswered questions continue to impede our understanding of this complex disease. Future research should focus on the identification of new biomarkers for early diagnosis and prognosis, which will help improve the clinical outcome of patients with SSc.

Laminin peptide YIGSR induces collagen synthesis in Hs27 human dermal fibroblasts

The dermal ECM is synthesized from fibroblasts and is primarily compromised of fibrillar collagen and elastic fibers, which support the mechanical strength and resiliency of skin, respectively. Laminin, a major glycoprotein located in the basement membrane, promotes cell adhesion, cell growth, differentiation, and migration. The laminin tyrosine-isoleucine-glycine-serine-arginine (YIGSR) peptide, corresponding to the 929-933 sequence of the β1 chain, is known to be a functional motif with effects on the inhibition of tumor metastasis, the regulation of sensory axonal response and the inhibition of angiogenesis through high affinity to the 67kDa laminin receptor. In this study, we identified a novel function of the YIGSR peptide to enhance collagen synthesis in human dermal fibroblasts. To elucidate this novel function regarding collagen synthesis, we treated human dermal fibroblasts with YIGSR peptide in both a time- and dose-dependent manner. According to subsequent experiments, we found that the YIGSR peptide strongly enhanced collagen type 1 synthesis without changing cell proliferation or cellular MMP-1 level. This YIGSR peptide-mediated collagen type 1 synthesis was modulated by FAK inhibitor and MEK inhibitor. This study clearly reveals that YIGSR peptide plays a novel function on the collagen type 1 synthesis of dermal fibroblasts and also suggests that YIGSR is a strong candidate peptide for the treatment of skin aging and wrinkles.