Flow cytometry of fibroblasts cultured from skin of patients with localized scleroderma

Fibroblast cultures were initiated from affected and unaffected skin sites of 6 patients with localized scleroderma. Two of the affected cell lines exhibited more than threefold increases in procollagen production and mRNA levels. All the cell lines were analyzed by flow cytometry to detect a possible heterogeneity of scleroderma fibroblast cultures which could explain the production of excessive amounts of collagen. No evidence of a subpopulation responsible for elevated collagen production was detected using cytoplasmic dot hybridization of cells fractionated by flow cytometry. When compared with the nonaffected controls, all the cell lines from affected skin areas of scleroderma patients were found to exhibit a lower level of cellular autofluorescence, suggesting an alteration in metabolic activity. The results show that the heterogeneity of scleroderma fibroblasts that was found in vivo is lost when the cells are cultured.     

Constitutive activation of c‐Abl/protein kinase C‐δ/Fli1 pathway in dermal fibroblasts derived from patients with localized scleroderma

Background A noncanonical pathway of transforming growth factor‐β signalling, the c‐Abl/protein kinase C‐δ (PKC‐δ)/Friend leukemia virus integration 1 (Fli1) axis, is a powerful regulator of collagen synthesis in dermal fibroblasts. Objectives To investigate the significance of the c‐Abl/PKC‐δ/Fli1 pathway for the establishment of the profibrotic phenotype in lesional dermal fibroblasts from patients with localized scleroderma (LSc). Methods The activation status of the c‐Abl/PKC‐δ/Fli1 pathway was evaluated by immunoblotting and chromatin immunoprecipitation using cultured dermal fibroblasts from patients with LSc and closely matched healthy controls and by immunostaining on skin sections. The effects of a platelet‐derived growth factor receptor inhibitor AG1296 and gene silencing of c‐Abl on the expression levels of type I collagen were evaluated by immunoblotting. Results The phosphorylation levels of Fli1 at threonine 312 were increased, while the total Fli1 levels and the binding of Fli1 to the COL1A2 promoter were decreased, in cultured LSc fibroblasts compared with cultured normal fibroblasts. Furthermore, in cultured LSc fibroblasts, the expression levels of c‐Abl were elevated compared with cultured normal fibroblasts and PKC‐δ was preferentially localized in the nucleus. These findings were also confirmed in vivo by immunohistochemistry using skin sections. Moreover, gene silencing of c‐Abl, but not AG1296, significantly suppressed the expression of type I collagen in cultured LSc fibroblasts. Conclusions Constitutive activation of the c‐Abl/PKC‐δ/Fli1 pathway at least partially contributes to the establishment of the profibrotic phenotype in LSc dermal fibroblasts, which provides a novel molecular basis to explain the efficacy of imatinib against skin sclerosis in a certain subset of LSc.     

Stimulated expression of decorin and the decorin gene in fibroblasts cultured from patients with localized scleroderma

Decorin mRNA levels, the content of decorin and the synthesis of dermatan sulphate in skin fibroblasts from patients with systemic and localized scleroderma were investigated. Approximately a 2.2-fold increase in decorin mRNA levels, was found by Northern blot analysis in localized scleroderma, but no significant changes were found in systemic scleroderma. Decorin, as measured by an immunoblot assay, was increased 2.6-fold in fibroblast cultures from localized scleroderma but not in those from systemic scleroderma. In contrast, the synthesis of dermatan sulphate was similar in both conditions. These results indicate that altered decorin gene expression causes abnormal proteoglycan metabolism in localized scleroderma.     

A TGF-beta1-dependent autocrine loop regulates the structure of focal adhesions in hypertrophic scar fibroblasts

Following injury, fibroblasts migrate into wounds and differentiate into alpha smooth muscle cell actin (SMCA)-positive cells, termed myofibroblasts, that assemble and remodel the scar. Cultured myofibroblasts assemble larger focal adhesions than do normal dermal fibroblasts and these focal adhesions attach to alpha SMCA-rich stress fibers. Following severe traumatic or thermal injury to the dermis, hypertrophic scars (HTSs) often develop and these scar fibroblasts (HTSFs) express alpha SMCA persistently. We now report that HTSFs stably display large focal adhesions as a consequence of both the autocrine production and activation of transforming growth factor beta1 (TGF-beta1). We also observe that myofibroblasts elaborating larger focal adhesions adhere more tightly to fibronectin. Conditioned medium from HTSFs induces focal adhesion growth in normal fibroblasts and this is blocked by pre-incubation with a soluble TGF-beta1 receptor mimetic. Human foreskin fibroblasts transduced with a retrovirus encoding active TGF-beta1 elaborate large focal adhesions, whereas fibroblasts overexpressing normal, latent TGF-beta1 do not. We conclude that the large focal adhesions found in pathogenic myofibroblasts arise through an autocrine loop involving the production and activation of TGF-beta1; these adhesions likely mediate both tighter adhesion to wound matrix and the exuberant wound contraction observed in pathogenic scars.     

激活素受体样激酶1在系统性硬化病患者皮肤成纤维细胞中的表达及作用

目的 探讨激活素受体样激酶1（ALK1）在系统性硬化病患者皮肤成纤维细胞中的表达及其在纤连蛋白和Ⅰ型纤溶酶原激活物抑制因子（PAI-1）产生中的作用。方法 Western 印迹和免疫荧光法观察比较ALK1在14例健康人和12例系统性硬化病患者皮肤成纤维细胞中的表达,并设计针对ALK1的特异性小干扰RNA（siRNA）,利用转染试剂将ALK1 siRNA瞬时转染至原代培养的健康人皮肤成纤维细胞中。转染后的细胞分两组,一组用无血清培养基OPTI-MEM培养,另一组在OPTI-MEM中加入转化生长因子?茁1（TGF?茁1）。培养72 h后,Western 印迹检测纤连蛋白和PAI-1蛋白量的变化。结果 Western 印迹和免疫荧光法结果显示,ALK1在健康人和系统性硬化病患者皮肤成纤维细胞中均有表达,且在系统性硬化病患者中的表达量明显高于健康人;免疫荧光结果显示,在成纤维细胞中ALK1位于胞膜和胞质中。转染了ALK1 siRNA的成纤维细胞其ALK1、纤连蛋白和PAI-1蛋白表达水平分别下降90%、58%和31%。TGF?茁1可显著促进对照siRNA组成纤维细胞表达ALK1、纤连蛋白和PAI-1,而ALK1 siRNA则显著抑制TGF?茁1诱导的ALK1、纤连蛋白和PAI-1的增加。 结论 TGF?茁1可通过ALK1诱导成纤维细胞纤连蛋白和PAI-1的表达,ALK1可能参与了系统性硬化病中纤维化的形成。     

Glycosaminoglycan content in the media of cultured dermal fibroblasts derived from burn scar and normal skin

The glycosaminoglycan (GAG) content of the extracellular matrix of burn scar in humans has been reported to differ from that of normal skin. In order to investigate whether the GAG content altered as a result of functional changes in fibroblasts, the GAG content was determined in culture media of fibroblasts derived from growing burn scar, mature scar, and normal skin tissue. No statistical differences were observed in the population doubling-times of scar and normal skin. Mature scar showed significantly higher values for all the concentrations of uronic acid, hexosamine, and sulfate measured in the glycosaminoglycan, as compared with normal skin values, and the concentrations from growing scar were slightly higher than those for normal skin. The above results may suggest an increase in glycosaminoglycan sulfate synthesis following the hyperplasia of the matrix in burn scar tissue.     

5 alpha-reductase activity in cultured human dermal papilla cells from beard compared with reticular dermal fibroblasts

The activity of 5 alpha-reductase was assessed in cultured human beard dermal papilla cells and reticular dermal fibroblasts to elucidate the mechanism of androgen action in promoting the growth of beards in men. The monolayer was incubated with 50 nM of [1,2-3H]-testosterone. Steroids were extracted from the medium and analyzed by thin layer chromatography. The major metabolite in the beard dermal papilla cells was dihydrotestosterone (DHT), the most potent androgen in the androgen target tissue. By contrast, the amount of DHT formed was similar to that of androstenedione in reticular dermal fibroblasts. The 5 alpha-reductase activity in beard dermal papilla cells was three to five times as high as that in the reticular dermal fibroblasts from the same skin sample. The apparant Michaelis constant of 5 alpha-reductase in the beard dermal papilla cells was 1.0 X 10(-6) M, which was virtually equivalent to that of genital skin fibroblasts, typical androgen target cells. It was 4.0 X 10(-5) M in reticular dermal fibroblasts. By contrast, the activities of 5 alpha-reductase in dermal papilla cells from occipital scalp hair follicles were similar to those of reticular dermal fibroblasts of the same skin samples. These results strongly suggest that the beard dermal papilla cell is an androgen target cell, and that DHT plays a role in the growth of beards in men.     

Identification of androgen-inducible TGF-beta1 derived from dermal papilla cells as a key mediator in androgenetic alopecia

We attempted to establish a coculture model of human dermal papilla cells (DPCs) from androgenetic alopecia (AGA) and keratinocytes (KCs) to study the pathomechanism of AGA. Since expression of mRNA for the androgen receptor (AR) decreased during subcultivation of DPCs in vitro, we transiently transfected the AR expression vector into the DPCs and cocultured them with KCs. In this coculture, androgen inhibited the growth of KCs by 50%, indicating that the DPCs produce diffusible growth suppressive factors into the medium in an androgen-dependent manner. Since recently increasing evidence has shown the importance of transforming growth factor-beta1 (TGF-beta1) in hair growth, we further examined the concentration of TGF-beta1 in this coculture medium after androgen treatment by ELISA assays. The results showed that androgen treatment increased the secretion of TGF-beta1 into the conditioned medium. Moreover, neutralizing anti-TGF-beta1 antibody reversed the inhibition of KC proliferation. Thus, we suggest that androgen-inducible TGF-beta1 derived from DPCs mediates hair growth suppression in AGA.     

Expression of TGF-beta 1, -beta 2 and -beta 3 in localized and systemic scleroderma.

Scleroderma is a generalized or localized disorder which leads to fibrosis of the affected organs. TGF-beta has been implicated as a causal agent in its pathogenesis. In mammals, TGF-beta comprises a family of three members, beta 1, beta 2 and beta 3. Since cutaneous wound healing is thought to result either in formation of a scar or in scar-free tissue regeneration, depending on the relative amounts of the beta 3 isoform, the expression of all three isoforms was studied in skin biopsies of patients with either localized or systemic scleroderma. mRNA for all three isoforms was detected in inflammatory skin areas of both disease forms, but never in sclerotic or healthy skin. Immunohistochemical analysis confirmed expression of beta1 and beta 2 proteins in inflammatory skin of patients, whereas beta 3 protein appeared to be present in the subepidermal area and also found throughout the dermis of patients and healthy dermis as well.     

D-penicillamine in the treatment of localized scleroderma

Localized scleroderma has no recognized internal organ involvement but may be disfiguring and disabling when the cutaneous lesions are extensive or affect children. There is no accepted or proven treatment for localized scleroderma. Case reports of 11 patients with severe, extensive localized scleroderma who were treated with D-penicillamine are summarized in this article. This drug was judged to have a favorable effect on the disease course in 7 (64%) of 11 patients. Improvement began within 3 to 6 months and consisted of cessation of active cutaneous lesions in all 7 patients, skin softening in 5, and more normal growth of the affected limb in 2 of 3 children. Joint stiffness and contractures also improved. The dose of D-penicillamine associated with a favorable response was as low as 2 to 5 mg/kg per day given over a period ranging from 15 to 53 months. D-Penicillamine caused nephrotic syndrome in 1 patient and milder reversible proteinuria in 3 other patients; none developed renal insufficiency. These data suggest that D-penicillamine may be effective in severe cases of localized scleroderma.     

Identification of fibroblasts responsible for increased collagen production in localized scleroderma by in situ hybridization

Skin biopsies from seven patients with localized scleroderma (morphea) and from two healthy individuals were studied by in situ hybridization to localize the cells responsible for increased procollagen production. In scleroderma lesions, high levels of pro alpha 1 (I) and pro alpha 1 (III) collagen mRNAs were detected in some but not all fibroblasts, suggesting the presence of a subpopulation responsible for the increased collagen production. The levels of pro alpha 1 (I) and pro alpha 1 (III) collagen mRNAs in these fibroblasts were clearly elevated compared to control skin specimens hybridized at the same time under identical conditions. Most of the scleroderma samples represented intermediate stages where the fibroblasts containing elevated levels of type I and type III procollagen mRNAs were located in the papillary and upper reticular layer of the dermis. One of the scleroderma samples from an early inflammatory stage of the disease was found to contain activated fibroblasts in all dermal layers and also in aggregates adjacent to inflammatory cell infiltrates. In situ analyses were also performed on cell cultures from affected and unaffected skin of one scleroderma patient. These experiments revealed a homogeneous population of activated fibroblasts in cultures producing high levels of collagen. The results suggest that development of fibrosis in scleroderma could evolve through activation of a certain fibroblast subpopulation. During cell culturing, however, cell selection or uncharacterized regulatory mechanisms appear to modulate the behavior of these cells with respect to collagen production.     

Topical tacrolimus in the treatment of localized scleroderma

Although the cause of localized scleroderma is unknown, an autoimmune mechanism is suspected. We describe two patients with localized scleroderma treated with topical tacrolimus, an immunosuppressive macrolide antibiotic. Topical tacrolimus 0.1% ointment applied twice daily under occlusion led to a significant clinical improvement of late sclerotic lesions and complete clearance of early inflammatory skin lesions in 3 months. These were the first cases of successful topical tacrolimus therapy in localized scleroderma and should be regarded as a promising treatment option for LS, especially on account of its high tolerability that permits prolonged use without side-effects.     

Immunohistochemical characterization of the cellular infiltrate in localized scleroderma

Background Localized scleroderma is a connective tissue disorder with hardening of the skin and fibrosis of the affected tissue as the most prominent features. The etiology of localized scleroderma is still unknown, but immunologic factors may play an important role in the pathogenesis. This study was performed to determine the immunohistochemical features of the cellular infiltrate in localized scleroderma. Methods Skin samples were obtained from six patients by 6‐mm punch biopsy. The samples were stained with monoclonal antibodies against CD1a, CD3, CD4, CD8, CD20, CD25, CD30, and CD57. The number of cells stained with each monoclonal antibody was calculated. Results There were more CD1a+, CD3+, CD4+, CD8+, CD20+, CD25+, and CD57+ cells in the dermal infiltrate in localized scleroderma relative to those in normal controls. The numbers of CD1a+, CD3+, CD4+, CD8+, and CD57+ cells in localized scleroderma were significantly greater than those in normal skin (P < 0.05). The number of CD30+ cells in localized scleroderma was almost the same as that in normal skin. Conclusions This study reveals that T lymphocytes, Langerhans cells, and natural killer cells may play important roles in the pathogenesis of localized scleroderma.     

Increased adhesion of fibroblasts from patients with scleroderma to extracellular matrix components: in vitro modulation by IFN-gamma but not by TGF-beta.

A characteristic feature of systemic scleroderma is fibrosis of the skin and eventually of internal organs resulting from an overproduction of collagen and other connective tissue components by the resident fibroblasts. The balance between the cells and the amount of the surrounding extracellular matrix is then altered. Because cellular metabolism depends to a large extent on cellular contacts and communications with connective tissue molecules, we have therefore investigated the interactions with extracellular matrix components of fibroblasts obtained from skin of patients affected with scleroderma. In comparison to fibroblasts from healthy skin, all fibroblasts from scleroderma patients had an increased adhesion capacity to collagens I, IV, VI, fibronectin, and laminin. In addition, whereas adhesion of control fibroblasts was stimulated by a pre-treatment with transforming growth factor-beta, adhesion patterns of scleroderma fibroblasts remained unchanged. However, pre-incubation of the cells with interferon-gamma decreased the adhesion of both scleroderma and control fibroblasts.     

Differential modulation of bFGF receptors by TGF-beta in adult skin, scleroderma skin, and newborn foreskin fibroblasts.

Effects of transforming growth factor beta (TGF-beta) on proliferative responses to basic fibroblast growth factor (bFGF) were studied in human diploid fibroblasts cell strains derived from three different sources: adult skin, scleroderma, and newborn foreskin. All three types of cell strains were similarly responsive to TGF-beta, whereas adult skin fibroblasts were significantly more responsive to bFGF. Incubation of cells with TGF-beta prior to bFGF addition substantially increased responsiveness of adult skin fibroblasts to this latter cytokine, slightly increased that of scleroderma fibroblasts, and decreased that of foreskin fibroblasts. Modulation of bFGF receptors by TGF-beta correlated positively with these mitogenic effects. Adult skin fibroblasts showed increases of both high- and low-affinity receptors and scleroderma fibroblasts showed small increases of high-affinity receptors only, whereas foreskin fibroblasts showed no changes. Heparitinase treatment of adult skin fibroblasts during TGF-beta pre-incubation resulted in reduced bFGF binding to low-affinity receptors and reduced mitogenic response to bFGF, suggesting that the TGF-beta-stimulated increase of low-affinity receptors in these cells contributes to the observed enhanced mitogenic effects of bFGF. Abnormal responses of scleroderma fibroblasts to TGF-beta/bFGF stimulation, particularly failure to synthesize low-affinity receptors in response to TGF-beta, adds a new characteristic to the fibrotic phenotype of scleroderma fibroblasts.