Katsunari Makino

TGF-β–Mediated Downregulation of MicroRNA-196a Contributes to the Constitutive Upregulated Type I Collagen Expression in Scleroderma Dermal Fibroblasts

Previous reports indicated the significance of the TGF-β signaling in the pathogenesis of systemic sclerosis. We tried to evaluate the possibility that microRNAs (miRNAs) play a part in the type I collagen upregulation seen in normal fibroblasts stimulated with exogenous TGF-β and systemic sclerosis (SSc) fibroblasts. miRNA expression profile was evaluated by miRNA PCR array and real-time PCR. The protein expression of type I collagen was determined by immunoblotting. In vivo detection of miRNA in paraffin section was performed by in situ hybridization. Several miRNAs were found to be downregulated in both TGF-β–stimulated normal fibroblasts and SSc fibroblasts compared with normal fibroblasts by PCR array. Among them, miR-196a expression was decreased in SSc both in vivo and in vitro by real-time PCR or in situ hybridization. In SSc fibroblasts, miR-196a expression was normalized by TGF-β small interfering RNA. miR-196a inhibitor leads to the overexpression of type I collagen in normal fibroblasts, whereas overexpression of the miRNA resulted in the downregulation of type I collagen in SSc fibroblasts. In addition, miR-196a was detectable and quantitative in the serum of SSc patients. Patients with lower serum miR-196a levels had significantly higher ratio of diffuse cutaneous SSc:limited cutaneous SSc, higher modified Rodnan total skin thickness score, and higher prevalence of pitting scars than those without. miR-196a may play some roles in the pathogenesis of SSc. Investigation of the regulatory mechanisms of type I collagen expression by miR-196a may lead to new treatments using miRNA.

The Downregulation of microRNA let-7a Contributes to the Excessive Expression of Type I Collagen in Systemic and Localized Scleroderma

Systemic and localized scleroderma (SSc and LSc) is characterized by excessive deposition of collagen and tissue fibrosis in the skin. Although they have fundamental common characteristics including autoimmunity, little is known about the exact mechanism that mediates the excessive collagen expression in these disorders. In the current study, we tried to evaluate the possibility that microRNAs (miRNAs) play some roles in the pathogenesis of fibrosis seen in these diseases. miRNA expression patterns were evaluated by miRNA array analysis, real-time PCR, and in situ hybridization. The function of miRNAs in dermal fibroblasts was assessed using miRNA inhibitors, precursors, or protectors. In the mouse model of bleomycin-induced dermal sclerosis, the overexpression of miRNAs was performed by i.p. miRNA injection. We demonstrated let-7a expression was downregulated in SSc and LSc skin both in vivo and in vitro, compared with normal or keloid skin. The inhibition or overexpression of let-7a in human or mouse skin fibroblasts affected the protein expression of type I collagen or luciferase activity of collagen 3′-untranslated region. Also, we found let-7a was detectable and quantitative in the serum and investigated serum let-7a levels in patients with SSc or LSc. let-7a concentration was significantly decreased in these patients, especially in LSc patients. Moreover, we revealed that the intermittent overexpression of let-7a in the skin by i.p. miRNA injection improved the skin fibrosis induced by bleomycin in mice. Investigation of more detailed mechanisms of miRNA-mediated regulation of collagen expression may lead to new therapeutic approaches against SSc and LSc.

Circulating miR-142-3p levels in patients with systemic sclerosis

Background.  Recently, increased evidence has shown that serum micro (mi)RNA levels are a useful biomarker for the diagnosis, prognosis and therapeutic value of various diseases. However, serum miRNA has not been investigated in patients with systemic sclerosis (SSc), to our knowledge.

microRNA-7 down-regulation mediates excessive collagen expression in localized scleroderma.

Localized scleroderma (LSc), a connective tissue disorder restricted to the skin and subcutaneous tissue, is characterized by skin fibrosis due to an excessive deposition of types I collagen. The mechanism of such fibrosis is still unknown, but epigenetics may play some roles in the excessive collagen expression. In the present study, we investigated the mechanism of fibrosis seen in LSc, focusing on microRNA (miRNA). miRNA expression was determined by PCR array, real-time PCR, and in situ hybridization. The function of miRNA was evaluated using specific inhibitor. Immunoblotting was performed to detect α2(I) collagen protein. PCR array analysis using tissue miRNA demonstrated miR-7 level was significantly decreased in LSc skin as well as keloid tissue compared to normal skin in vivo. In situ hybridization also showed miR-7 expression in dermal fibroblasts was decreased in LSc dermis. The transfection of specific inhibitor for miR-7 into cultured normal dermal fibroblasts resulted in the up-regulation of α2(I) collagen protein in vitro. Also, the serum levels of miR-7 were significantly decreased in LSc patients compared with healthy controls, but serum miR-29a levels not. Systemic or local down-regulation of miR-7 may contribute to the pathogenesis of LSc via the overexpression of α2(I) collagen, and serum miR-7 may be useful as a disease marker. Investigation of the regulatory mechanisms of LSc by miRNA may lead to new treatments by the transfection into the lesional skin of this disease.

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.

Adiponectin expression is decreased in the involved skin and sera of diffuse cutaneous scleroderma patients

Abstract:  In this study, we determined the adiponectin expression in the serum and lesional skin of patients with scleroderma (SSc). Serum adiponectin concentrations were measured in 32 patients with SSc, 10 patients with SLE, 12 patients with dermatomyositis patients and 13 healthy subjects with specific enzyme‐linked immunosorbent assays. Adiponectin mRNA was determined in skin tissues of five patients with diffuse cutaneous SSc (dcSSc), seven patients with limited cutaneous SSc (lcSSc) and seven healthy subjects with real‐time polymerase chain reaction. There was a significant reduction in serum adiponectin levels in patients with dcSSc. SSc patients with decreased serum adiponectin levels had higher total skin thickness score and higher incidence of pulmonary fibrosis. Adiponectin mRNA levels in skin tissues from patients with dcSSc were also reduced. Serum adiponectin levels may be a useful biomarker for fibrotic condition in patients with SSc. Clarifying the role of adiponectin in collagen diseases may lead to further understanding of the pathogenesis and new therapeutic approach.

Discoidin Domain Receptor 2–microRNA 196a–Mediated Negative Feedback against Excess Type I Collagen Expression Is Impaired in Scleroderma Dermal Fibroblasts

Systemic sclerosis (SSc) is characterized by excess collagen deposition in the skin, due to intrinsic transforming growth factor-β (TGF-β) activation. We tried to determine the expression and the role of discoidin domain receptor 2 (DDR2) in SSc. The expression of DDR2 mRNA and protein was significantly decreased in SSc dermal fibroblasts, which was recovered by knocking down TGF-β. The knockdown of DDR2 in normal fibroblasts induced microRNA-196a expression, which led to type I collagen downregulation, indicating that DDR2 itself has a negative effect on microRNA-196a expression and inducible effect on collagen expression. In SSc fibroblasts, however, the DDR2 knockdown did not affect TGF-β signaling and microRNA-196a expression. The microRNA-196a levels were significantly decreased in normal fibroblasts treated with TGF-β and in SSc fibroblasts. Taken together our data indicate that, in SSc fibroblasts, intrinsic TGF-β stimulation induces type I collagen expression, and also downregulates DDR2 expression. This probably acts as a negative feedback mechanism against excess collagen expression, as a decreased DDR2 expression is supposed to stimulate the microRNA-196a expression and further change the collagen expression. However, in SSc fibroblasts the microRNA-196a expression was downregulated by TGF-β signaling. DDR2-microRNA-196a pathway may be a previously unreported negative feedback system, and its impairment may be involved in the pathogenesis of SSc.

Serum levels of soluble CD163 in patients with systemic sclerosis

Macrophages may play a role in the pathogenesis of systemic sclerosis (SSc), and CD163-positive M2 macrophages are potentially important source for fibrosis-inducing cytokines. However, no link between M2 macrophages and SSc has been established. The aim is to evaluate the possibility that serum levels of soluble CD163 (sCD163) can be a useful marker for SSc, reflecting M2 activation of macrophages in this disease. Serum sCD163 levels of 43 patients with SSc, 10 patients with scleroderma spectrum disorder (SSD), and 12 healthy controls were measured with specific enzyme-linked immunosorbent assays. SSc patients had significantly higher serum sCD163 levels than healthy controls. The sCD163 levels in SSD patients were higher than healthy controls and lower than SSc patients. Significantly higher right ventricular systolic pressure and lower % DLco levels, and shorter duration of disease were seen in SSc patients with elevated serum sCD163 levels than those with normal levels. These results suggest that sCD163 levels may be increased in proportion to the progression of this disease, indicating the involvement of CD163 in the pathogenesis of SSc. Furthermore, serum sCD163 levels may be a marker of pulmonary hypertension at the early stage in patients with SSc.

Decreased miR-7 Expression in the Skin and Sera of Patients with Dermatomyositis

Expression of microRNA (miRNA) in the skin in dermatomyositis has not previously been studied in detail. In this study, we performed miRNA array analysis using miRNAs purified from dermatomyositis-involved skin and normal skin, and found that several miRNAs were up- or down-regulated in dermatomyositis skin. Among them, we focused on miR-7, one of the most down-regulated miRNAs in dermatomyositis skin. Total miRNAs were purified from serum, and hsa-miR-7 levels were measured with quantitative real-time PCR using the specific primer. Serum levels of miR-7 were significantly decreased in patients with dermatomyositis compared with normal subjects or patients with other autoimmune diseases. Thus, serum miR-7 levels might be a possible diagnostic marker for dermatomyositis. Clarifying the up- or down-stream events of down-regulated miR-7 in patients with dermatomyositis may lead to further understanding of the disease and a new therapeutic approach.

Serum levels of soluble vascular endothelial growth factor receptor-2 in patients with systemic sclerosis

Background  Although vascular endothelial growth factor (VEGF)‐A/VEGF receptor 2 (KDR) signalling may play a major role in the microangiopathy of systemic sclerosis (SSc), serum levels of soluble KDR (sKDR) in this disease have not yet been determined.