Pathogenesis of scleroderma. Collagen

Localized morphea treated with imiquimod 5% and dermoscopic assessment of effectiveness

The cases are reported of two women patients presenting asymptomatic solitary lesions: one in the anterior tibial region of the right leg, the other on the right arm. The first patient's lesion was 3 cm in diameter and had appeared 2 years earlier as a translucent oval atrophic patch with a definite border. The second patient presented a whitish area with a lilac ring, 2.5 cm in diameter, which had appeared nearly a year earlier. Both patients had no other similar cutaneous lesions, and their family histories for cutaneous disease were negative. The lesions underwent punch biopsy, and the histopathological findings confirmed the diagnosis of morphea. Laboratory investigations showed no abnormalities. Imiquimod 5% cream was prescribed for 5 consecutive days a week for 16 weeks. Clinical and dermoscopic assessment of the lesions was performed before treatment, during follow-up and at treatment end point. No local or systemic side effects were observed during treatment. Following treatment, both patients achieved complete clinical remission of the lesions, with a definitive improvement in the lesions' initial disfiguring features.

Effect of erythromycin A and its new derivative EM201 on type I collagen production by cultured dermal fibroblasts

Thinning of the dermis is the principal histological change in atrophic skin disorders and aged skin. It is caused due to a decreased amount of collagen in the dermis. Macrolides have been reported to exert various pharmacological activities, including anti-inflammatory activity, tumor angiogenesis inhibition and growth inhibition of fibroblasts, in addition to antimicrobial activity. In this study, we investigated the effects of erythromycin A (EMA) and its new derivative EM201 on type I collagen production by cultured dermal fibroblasts. Dermal fibroblasts were cultured with 10(-9) M-10(-5) M EMA or EM201, and collagen production was measured by incubation with radioactive proline, SDS-polyacrylamide gel electrophoresis and fluorography. mRNA levels were measured by Northern blots analysis, and to investigate transcriptional levels luciferase assays were also performed. The results showed that both EMA and EM201 increased collagen production and type I collagen mRNA level (to a maximum of 200% with EMA and 250% with EM201) in a dose-dependent manner in cultured dermal fibroblasts. Transcription of the type I collagen gene was also increased by both macrolides. These results suggest that EMA and EM201 have the potential to improve the thinning of the dermis in atrophic skin disorders and aged skin.

Role of connective tissue growth factor and its interaction with basic fibroblast growth factor and macrophage chemoattractant protein-1 in skin fibrosis

Activation of the immune system and abnormal growth of skin fibroblasts cause systemic sclerosis. Growth factors have various biological activities, including mediation of immune reactions. The growth factor family includes basic fibroblast growth factor (bFGF), transforming growth factor-beta (TGF-beta), and connective tissue growth factor (CTGF). CTGF, an important downstream mediator of TGF-beta in fibrosis, has been suggested to play a specific role in fibrotic disorders. We have directed our attention to the role of CTGF in sustaining skin fibrosis. To better understand its effects in vivo, we established an animal model of skin fibrosis induced by exogenous application of growth factors. In this model, bFGF transiently induced subcutaneous fibrosis. Simultaneous injection of bFGF and CTGF increased skin fibrosis compared with a single injection of bFGF. Serial injections of bFGF for 3 days followed by CTGF for 4 days, or of CTGF followed by bFGF, did not cause skin fibrosis but simultaneous injections increased macrophage chemoattractant protein-1 (MCP-1) mRNA expression levels. To further define the mechanisms of skin fibrosis in vivo, bFGF and CTGF were injected simultaneously into MCP-1 knockout mice, resulting in decreased collagen levels in granulation tissues on day 8. The number of inflammatory cells, such as mast cells, macrophages and lymphocytes, was significantly decreased in MCP-1 knockout mice compared with wild-type mice. These results suggest that bFGF induces collagen production by stimulating skin fibroblasts and CTGF cooperates with bFGF. Our results indicate that the induction of MCP-1 is necessary for infiltration of inflammatory cells.

Elevated expression of isopeptide bond cross-links contributes to fibrosis in scleroderma and the healing wounds of tight skin mice

Scleroderma is a chronic disease characterized by excessive tissue fibrosis. Recent studies indicate that cultured dermal fibroblasts isolated from patients produce excessive amounts of collagen and other extracellular matrix components. In this study, we investigated the mechanism(s) of abnormal extracellular matrix accumulation in the scleroderma biopsies and the healing wounds of Tsk1/+ mice. Full-thickness excisional wounds were made in Tsk1/+ and wild-type mice and were subsequently harvested at days 7, 10, and 14 postinjury. The levels of pro-fibrotic cytokine, transforming growth factor were elevated in the wounds of Tsk1/+ mice. Interestingly, the levels of matrix metalloproteinase were significantly reduced in the granulation tissue of Tsk1/+ mice in comparison with wild-type. Furthermore, immunohistochemical analysis of the wounds indicated that the levels of gamma-glutamyl-epsilon-lysine cross-links were elevated in the granulation tissue of Tsk1/+ mice as well as the fibrotic lesions of scleroderma specimens. Collectively, these findings indicate that elevated collagen synthesis and decreased matrix metalloproteinase levels, in combination with increased isopeptide bond cross-links, contribute to abnormal collagen synthesis and assembly in granulation tissue of Tsk1/+ mice and the fibrotic lesions of scleroderma patients.

Esclerodermia localizada na criança: aspectos clínicos, diagnósticos e terapêuticos

A esclerodermia localizada, ou morféia, acomete crianças em idade escolar e, em geral, é autolimitada, apesar de localmente desfiguradora. A literatura descreve inúmeros fatores etiopatogênicos, bem como modalidades de investigação e tratamento. Este artigo reúne os estudos mais recentes e discute sua aplicação clínica.

Elevated serum concentrations of polymorphonuclear neutrophilic leukocyte elastase in systemic sclerosis: association with pulmonary fibrosis

OBJECTIVE

To determine the serum concentrations and clinical association of polymorphonuclear neutrophilic leukocyte (PMN) elastase in patients with systemic sclerosis (SSc).

METHODS

Serum PMN elastase levels from 21 patients with limited cutaneous SSc (lSSc) and 32 with diffuse cutaneous SSc (dSSc) were examined by ELISA.

RESULTS

Serum PMN elastase levels were elevated in patients with SSc, especially dSSc, compared to healthy controls. SSc patients with elevated serum PMN elastase levels had more frequent presence of pulmonary fibrosis, arthritis, contracture of phalanges, and diffuse pigmentation. Anticentromere antibody was detected less frequently in SSc patients with elevated serum PMN elastase levels than in controls. Consistently, serum PMN elastase levels also correlated positively with serum levels of KL-6 and surfactant protein-D, serological markers for pulmonary fibrosis. Serum PMN elastase levels were also associated with levels of serum 8-isoprostane, an oxidative stress marker in SSc.

CONCLUSION

Serum PMN elastase levels were elevated in patients with SSc, and it was more prominent in patients with pulmonary fibrosis, suggesting that serum PMN elastase is a novel serological marker for SSc-related pulmonary fibrosis.

TGFbeta affects collagen cross-linking independent of chondrocyte phenotype but strongly depending on physical environment

Transforming growth factor beta (TGFbeta) is often used in cartilage tissue engineering to increase matrix formation by cells with various phenotypes. However, adverse effects of TGFbeta, such as extensive crosslinking in cultured fibroblasts, have also been reported. Our goal was to study effects of TGFbeta on collagen cross-linking and evaluating the role of cellular phenotype and physical environment. We therefore used four different cell populations in two very different physical environments: primary and expanded chondrocytes and fibroblasts embedded in alginate gel and attached to tissue culture plastic. Matrix production, collagen cross-linking, and alpha-smooth muscle actin (alphaSMA) were analyzed during 4 weeks with or without 2.5 ng/ mL TGFbeta2. TGFbeta2 did not affect collagen deposition by primary cells. In expanded cells, TGFbeta2 increased collagen deposition. Chondrocytes and fibroblasts in monolayer produced more collagen cross-links with TGFbeta2. In alginate, primary and expanded cells displayed an unexpected decrease in collagen cross-linking with TGFbeta2. alphaSMA was not present in alginate cultures and barely upregulated by TGFbeta2. Organized alphaSMA fibers were present in all monolayer cultures and became more pronounced with TGFbeta2. This study demonstrates that the physical environment determined by the substrate used co-determines the response of cells to TGFbeta. The presence of mechanical stress, determined with alphaSMA-staining, is probably responsible for the increase in collagen cross-linking upon addition of TGFbeta.

Proteomic analysis of scleroderma lesional skin reveals activated wound healing phenotype of epidermal cell layer

OBJECTIVE

To identify using proteomic analysis, proteins of altered abundance in the skin of patients with SSc.

METHODS

4 mm excision biopsies were obtained from the forearm involved skin of 12 diffuse SSc patients and 12 healthy controls. Two-dimensional gel electrophoresis was used to separate and define proteins in normal and SSc skin biopsy material. Proteins of altered abundance in the disease were formally identified by mass spectroscopy. Abnormalities of the epidermis were confirmed by immunohistochemistry.

RESULTS

Proteomic analysis revealed altered abundance of proteins involved in extracellular matrix production, myofibroblast contractility, energy metabolism and response to oxidative stress. In addition, proteins specific to the epidermis and involved in epidermal cell differentiation were altered in abundance in the disease. SSc epidermis is thickened, has an expanded nucleated cell layer, and exhibits abnormal persistence of basal marker keratin 14, delayed expression of maturation markers keratin 1/10 and the induction of keratins 6 and 16, normally absent from interfollicular skin and induced following epidermal injury. These changes closely resemble the activated phenotype seen during wound healing.

CONCLUSIONS

Consistent with previous models of SSc pathogenesis these data are showing increased contractility, increased extracellular matrix and response to oxidative stress in the involved skin of recent onset SSc patients. In addition, we show that SSc epidermis has an activated, wound healing phenotype. These findings are important because epidermal cells activated by injury induce and regulate local fibroblasts during wound repair.

Neutralizing monoclonal antibody to human connective tissue growth factor ameliorates transforming growth factor-beta-induced mouse fibrosis

Skin fibrotic disorders such as systemic sclerosis (SSc) are characterized by an excessive accumulation of extracellular matrix (ECM) and are understood to develop under the influence of fibrogenic growth factors. To better understand the detailed mechanisms of persistent fibrosis in SSc, we have previously established an animal model of skin fibrosis induced by exogenous application of growth factors. In this model, transforming growth factor-beta (TGF-beta) transiently induced subcutaneous fibrosis and serial injections of connective tissue growth factor (CTGF) after TGF-beta caused persistent fibrosis. These results suggest that CTGF plays an important role in the development of persistent skin fibrosis and that CTGF may be a potential and specific therapeutic target in skin fibrosis. Therefore, the aim of the current study is to develop a neutralizing monoclonal antibody against human CTGF. We also investigated the neutralizing effect of the antibodies in our animal model. Firstly, by using the DNA immunization method, we developed a panel of anti-CTGF antibodies recognizing the native conformation of human CTGF. Next, to examine the anti-fibrosing effects of these antibodies, newborn B6 mice received subcutaneous injections of TGF-beta for 3 days with either anti-CTGF neutralizing antibodies or control purified immunoglobulin. Anti-CTGF antibodies significantly reduced skin fibrosis and collagen contents compared with the control group. These results suggest that our anti-CTGF antibodies are capable of blocking the development of skin fibrosis at least partially and these anti-CTGF neutralizing antibodies may be useful as the feasible strategy to treat skin fibrotic diseases as SSc.

Heparan sulfate-dependent ERK activation contributes to the overexpression of fibrotic proteins and enhanced contraction by scleroderma fibroblasts

OBJECTIVE

To investigate the contribution of heparan sulfate proteoglycan and Ras/MEK/ERK to the overexpression of profibrotic proteins and the enhanced contractile ability of dermal fibroblasts from patients with systemic sclerosis (SSc; scleroderma).

METHODS

The effects of the MEK/ERK inhibitor U0126, the heparan sulfate side chain formation inhibitor beta-xyloside, and soluble heparin on the overexpression of profibrotic genes were compared in fibroblasts from lesional skin of patients with diffuse SSc and fibroblasts from healthy control subjects. Identified protein expressions were compared with the contractile abilities of fibroblasts while they resided within a collagen lattice. Forces generated were measured using a culture force monitor.

RESULTS

Inhibiting MEK/ERK with U0126 significantly reduced expression of a cohort of proadhesive and procontractile proteins that normally are overexpressed by scleroderma fibroblasts, including integrin alpha4 and integrin beta1. Antagonizing heparan sulfate side chain formation with beta-xyloside or the addition of soluble heparin prevented ERK activation, in addition to reducing the expression of these proadhesive/contractile proteins. Treatment with either U0126, beta-xyloside, or heparin resulted in a reduction in the overall peak contractile force generated by dermal fibroblasts. Blocking platelet-derived growth factor receptor with Gleevec (imatinib mesylate) reduced overall contractile ability and the elevated syndecan 4 expression and ERK activation in SSc fibroblasts.

CONCLUSION

The results of this study suggest that heparan sulfate-dependent ERK activation contributes to the enhanced contractile ability demonstrated by dermal fibroblasts from lesional skin of patients with scleroderma. These results are consistent with the notion that the MEK/ERK procontractile pathway is dysregulated in scleroderma dermal fibroblasts. Additionally, the results suggest that antagonizing the MEK/ERK pathway is likely to modulate heparan sulfate proteoglycan activity, which in turn may have a profound effect on the fibrotic response in SSc.

Treatment with antisense oligonucleotide reduces the expression of type I collagen in a human-skin organ-wound model: implications for antifibrotic gene therapy

Increased collagen expression during wound healing causes scar formation, abnormal contracture, low tensile strength, functional impairment, and disfigurement. A novel ex vivo wound-injury model demonstrated that AS60, an antisense oligonucleotide (ASO) to type I collagen, reduced the mRNA and protein expression of type 1 collagen. Following a cutaneous wound injury in a human-skin organ culture, AS60 injection resulted in a 36% (P < 0.001) and 30% decrease (P < 0.001) in type 1 collagen mRNA and protein expression after 7 days. Similarly, transfection of cultured human fibroblasts with ASO resulted in a 36% decrease (P < 0.001) and a 31% decrease (P < 0.001) in type 1 collagen mRNA and protein expression. Immunofluorescence of human skin organ culture treated with ASO showed a specific reduction in collagen expression. Using AS60 to reduce collagen expression in human skin may have implications for its use as a gene therapy agent to reduce the formation of fibrotic scarring.

Understanding systemic sclerosis through gene expression profiling

PURPOSE OF REVIEW

Genomic analysis has rapidly become commonplace in the study and treatment of complex disease. Several recent studies of gene expression profiling in systemic sclerosis have demonstrated its value in diagnosis and illustrate the potential for this technique in prognostication, as well as the elucidation of the underlying pathogenesis.

RECENT FINDINGS

Skin biopsies from patients with systemic sclerosis show robust changes in gene profile that precede clinically detectable involvement. Current results suggest that clinically indistinguishable subgroups may be identified with different pathogenesis and outcome. Expression profiling studies of animal models of systemic sclerosis and explanted fibroblasts have helped to reveal the utility and deficiencies of these surrogates in the study of systemic sclerosis.

SUMMARY

Gene profiling is likely to provide valuable prognostic information in systemic sclerosis patients. Recent advances in sample collection and standardization of analysis mean that longitudinal collection of samples for gene profiling, even in small numbers of patients from different clinical centers, will contribute enormously to our understanding of the disease.

Capillary regeneration in scleroderma: stem cell therapy reverses phenotype?

BACKGROUND

Scleroderma is an autoimmune disease with a characteristic vascular pathology. The vasculopathy associated with scleroderma is one of the major contributors to the clinical manifestations of the disease.

METHODOLOGY/PRINCIPAL FINDINGS

We used immunohistochemical and mRNA in situ hybridization techniques to characterize this vasculopathy and showed with morphometry that scleroderma has true capillary rarefaction. We compared skin biopsies from 23 scleroderma patients and 24 normal controls and 7 scleroderma patients who had undergone high dose immunosuppressive therapy followed by autologous hematopoietic cell transplant. Along with the loss of capillaries there was a dramatic change in endothelial phenotype in the residual vessels. The molecules defining this phenotype are: vascular endothelial cadherin, a supposedly universal endothelial marker required for tube formation (lost in the scleroderma tissue), antiangiogenic interferon alpha (overexpressed in the scleroderma dermis) and RGS5, a signaling molecule whose expression coincides with the end of branching morphogenesis during development and tumor angiogenesis (also overexpressed in scleroderma skin. Following high dose immunosuppressive therapy, patients experienced clinical improvement and 5 of the 7 patients with scleroderma had increased capillary counts. It was also observed in the same 5 patients, that the interferon alpha and vascular endothelial cadherin had returned to normal as other clinical signs in the skin regressed, and in all 7 patients, RGS5 had returned to normal.

CONCLUSION/SIGNIFICANCE

These data provide the first objective evidence for loss of vessels in scleroderma and show that this phenomenon is reversible. Coordinate changes in expression of three molecules already implicated in angiogenesis or anti-angiogenesis suggest that control of expression of these three molecules may be the underlying mechanism for at least the vascular component of this disease. Since rarefaction has been little studied, these data may have implications for other diseases characterized by loss of capillaries including hypertension, congestive heart failure and scar formation.

T cells expressing allograft inflammatory factor 1 display increased chemotaxis and induce a profibrotic phenotype in normal fibroblasts in vitro

OBJECTIVE

Allograft inflammatory factor 1 (AIF-1) was first identified in rat cardiac allografts undergoing chronic rejection. The vasculopathy of chronic allograft rejection is strikingly similar to that seen in patients with systemic sclerosis (SSc). We previously demonstrated AIF-1 expression in inflammatory cells infiltrating skin and lungs from SSc patients, but its role in SSc pathogenesis is unknown. The present study was undertaken to investigate the effects of AIF-1 on T cell migration and production of cytokines capable of modulating normal dermal fibroblast functions.

METHODS

Stably transfected Jurkat T cells expressing 2 AIF-1 splicing variants were prepared, and their migration toward fibroblast monolayers assayed in Transwell cultures. Cytokine production was assessed by real-time polymerase chain reaction (PCR) and multiplex enzyme-linked immunosorbent assay. Fibroblast gene expression was quantified by real-time PCR, and collagen production by Western blot analysis of culture media.

RESULTS

AIF-1 significantly increased Jurkat T cell migration toward fibroblast monolayers. Expression of AIF-1 isoform 2 in Jurkat T cells up-regulated their production of interleukin-4 (IL-4) and IL-17. Conditioned media from AIF-1-expressing clones stimulated synthesis of types I and III collagen and expression of IL-6, transforming growth factor beta, endothelin receptor, and alpha-smooth muscle actin by normal dermal fibroblasts.

CONCLUSION

These results suggest that AIF-1 may participate in the early pathogenesis of SSc by promoting tissue T cell infiltration and production of cytokines capable of inducing the expression of a fibrotic phenotype in normal fibroblasts.

EM703, the new derivative of erythromycin, inhibits transcription of type I collagen in normal and scleroderma fibroblasts

BACKGROUND

Excessive accumulation of collagen in the skin and internal organs in systemic sclerosis (SSc) is considered to result from enhanced transcription of collagen in fibroblasts. Macrolides have been reported to show various pharmacological activities. Recently, it was reported that EM703, a new derivative of erythromycin, improved bleomycin-induced pulmonary fibrosis in mice.

OBJECTIVE

Therefore, we attempted to examine the effects of EM703 on the type I collagen synthetic activity in normal and SSc dermal fibroblasts.

METHODS

Normal and SSc dermal fibroblasts were cultured with various concentrations of Erythromycin A or EM703 for 48h. Amount of type I collagen in the culture medium was measured with ELISA with anti-type I collagen antibody. Type I collagen mRNA levels were measured by northern blots analysis and type I collagen transcription and regulation of the human COL1A1 promoter activity were examined by transient transfection and luciferase assay. Electrophoretic gel mobility shift assay was also performed for measurement of binding activities of DNA binding factors to the COL1A1 promoter.

RESULTS

We found that EM703 reduced collagen production and the mRNA levels of alpha1(I) collagen in a dose-dependent manner in the normal fibroblasts. The transcription of COL1A1 was downregulated as detected by the luciferase assay. The downregulation was also detected using DNA containing various short lengths of the COL1A1 promoter region. EM703 did not inhibit COL1A1 transcription when the luciferase assay was performed using DNA containing the COL1A1 promoter with a short substitution mutation of the CCAAT box. Decreased production of type I collagen at the transcriptional level was also found in SSc fibroblasts treated with EM703.

CONCLUSION

These results suggest that EM703 inhibits the transcription of type I collagen in both normal and SSc fibroblasts, and that the transcription is inhibited through the CCAAT box of the COL1A1 promoter.

Hypoxia induces expression of connective tissue growth factor in scleroderma skin fibroblasts

Connective tissue growth factor (CTGF) plays a role in the fibrotic process of systemic sclerosis (SSc). Because hypoxia is associated with fibrosis in several profibrogenic conditions, we investigated whether CTGF expression in SSc fibroblasts is regulated by hypoxia. Dermal fibroblasts from patients with SSc and healthy controls were cultured in the presence of hypoxia or cobalt chloride (CoCl(2)), a chemical inducer of hypoxia-inducible factor (HIF)-1alpha. Expression of CTGF was evaluated by Northern and Western blot analyses. Dermal fibroblasts exposed to hypoxia (1% O(2)) or CoCl(2) (1-100 microM) enhanced expression of CTGF mRNA. Skin fibroblasts transfected with HIF-1alpha showed the increased levels of CTGF protein and mRNA, as well as nuclear staining of HIF-1alpha, which was enhanced further by treatment of CoCl(2). Simultaneous treatment of CoCl(2) and transforming growth factor (TGF)-beta additively increased CTGF mRNA in dermal fibroblasts. Interferon-gamma inhibited the TGF-beta-induced CTGF mRNA expression dose-dependently in dermal fibroblasts, but they failed to hamper the CoCl(2)-induced CTGF mRNA expression. In addition, CoCl(2) treatment increased nuclear factor (NF)-kappaB binding activity for CTGF mRNA, while decreasing IkappaBalpha expression in dermal fibroblasts. Our data suggest that hypoxia, caused possibly by microvascular alterations, up-regulates CTGF expression through the activation of HIF-1alpha in dermal fibroblasts of SSc patients, and thereby contributes to the progression of skin fibrosis.

Adenosine A2A receptors in diffuse dermal fibrosis: pathogenic role in human dermal fibroblasts and in a murine model of scleroderma

OBJECTIVE

Adenosine regulates inflammation and tissue repair, and adenosine A2A receptors promote wound healing by stimulating collagen matrix production. We therefore examined whether adenosine A2A receptors contribute to the pathogenesis of dermal fibrosis.

METHODS

Collagen production by primary human dermal fibroblasts was analyzed by real-time polymerase chain reaction, 14C-proline incorporation, and Sircol assay. Intracellular signaling for dermal collagen production was investigated using inhibitors of MEK-1 and by demonstration of ERK phosphorylation. In vivo effects were studied in a bleomycin-induced dermal fibrosis model using adenosine A2A receptor-deficient wild-type littermate mice, C57BL/6 mice, and mice treated with adenosine A2A receptor antagonist. Morphometric features and levels of hydroxyproline were determined as measures of dermal fibrosis.

RESULTS

Adenosine A2A receptor occupancy promoted collagen production by primary human dermal fibroblasts, which was blocked by adenosine A2A, but not A1 or A2B, receptor antagonism. Adenosine A2A receptor ligation stimulated ERK phosphorylation, and A2A receptor-mediated collagen production by dermal fibroblasts was blocked by MEK-1 inhibitors. Adenosine A2A receptor-deficient and A2A receptor antagonist-treated mice were protected from developing bleomycin-induced dermal fibrosis.

CONCLUSION

These results demonstrate that adenosine A2A receptors play an active role in the pathogenesis of dermal fibrosis and suggest a novel therapeutic target in the treatment and prevention of dermal fibrosis in diseases such as scleroderma.

Androgen and prolactin (Prl) levels in systemic sclerosis (SSc): relationship to disease severity

Testosterone (T), sex hormone-binding globulin, (SHBG), dehydroepiandrosterone sulfate (DHEAS), and prolactin (Prl) serum levels were measured by electrochemiluminescense immunoassay (ECLIA) in 39 patients with systemic sclerosis (SSc) and compared with serum hormonal levels in control subjects matched for sex and reproductive status. A possible relationship with disease duration and disease severity was examined. Our data show an altered androgen and prolactin (Prl) status in SSc patients, in most cases related to disease duration and disease severity score. We can hypothesize that hormonal dysregulation is a consequence of the chronicity of the disease. The altered hormonal status could result in relative immunological hyperactivity contributing to enhance tissue damage and disease severity.

Constitutive ALK5-independent c-Jun N-terminal kinase activation contributes to endothelin-1 overexpression in pulmonary fibrosis: evidence of an autocrine endothelin loop operating through the endothelin A and B receptors

The signal transduction mechanisms generating pathological fibrosis are almost wholly unknown. Endothelin-1 (ET-1), which is up-regulated during tissue repair and fibrosis, induces lung fibroblasts to produce and contract extracellular matrix. Lung fibroblasts isolated from scleroderma patients with chronic pulmonary fibrosis produce elevated levels of ET-1, which contribute to the persistent fibrotic phenotype of these cells. Transforming growth factor beta (TGF-beta) induces fibroblasts to produce and contract matrix. In this report, we show that TGF-beta induces ET-1 in normal and fibrotic lung fibroblasts in a Smad-independent ALK5/c-Jun N-terminal kinase (JNK)/Ap-1-dependent fashion. ET-1 induces JNK through TAK1. Fibrotic lung fibroblasts display constitutive JNK activation, which was reduced by the dual ETA/ETB receptor inhibitor, bosentan, providing evidence of an autocrine endothelin loop. Thus, ET-1 and TGF-beta are likely to cooperate in the pathogenesis of pulmonary fibrosis. As elevated JNK activation in fibrotic lung fibroblasts contributes to the persistence of the myofibroblast phenotype in pulmonary fibrosis by promoting an autocrine ET-1 loop, targeting the ETA and ETB receptors or constitutive JNK activation by fibrotic lung fibroblasts is likely to be of benefit in combating chronic pulmonary fibrosis.

Effect of small interfering RNA on the expression of connective tissue growth factor and type I and III collagen in skin fibroblasts of patients with systemic sclerosis

BACKGROUND

Systemic sclerosis (SSc) is characterized by an excessive production of extracellular matrix. It is widely accepted that fibrosis is induced by transforming growth factor (TGF)-beta in the early stage and is subsequently maintained by connective tissue growth factor (CTGF). CTGF is a cysteine-rich mitogenic peptide that has been involved in various fibrotic disorders and can be induced in fibroblasts by activation with TGF-beta.

OBJECTIVES

To evaluate the effect of small interfering RNA (siRNA) targeting CTGF on the expression of CTGF and type I and type III collagen in SSc.

METHODS

Skin fibroblasts from patients with SSc were cultured in vitro and later transfected using four CTGF-specific siRNAs and one nonspecific siRNA. The effect of CTGF-specific siRNAs on the expression of CTGF and type I and type III collagen was examined and quantified by real-time reverse transcription-polymerase chain reaction (RT-PCR), Western blot analysis and immunocytochemistry.

RESULTS

Semiquantitative RT-PCR analysis showed that the four CTGF-specific siRNAs significantly reduced CTGF mRNA expression (P < 0.001), of which siRNA742 showed the strongest inhibitory effect with an inhibitory rate of 73%. Three of the four siRNAs could also depress the transcriptional levels of type I and type III collagen mRNA (P < 0.001), of which siRNA742 showed the strongest inhibitory effect with an inhibitory rate of 37% and 29% for type I and type III collagen, respectively. Western blot analysis further demonstrated that three CTGF-specific siRNAs could significantly decrease CTGF protein level (P < 0.001). In addition, immunocytochemical analysis showed that the expression of type I collagen was significantly decreased in fibroblasts after transfection with siRNA742, whereas inhibition of expression of type III collagen was modest.

CONCLUSIONS

Our data for the first time showed that CTGF RNA interference could inhibit expression of CTGF and type I and III collagen in SSc fibroblasts and indicated that CTGF might be an upstream factor regulating type I and type III collagen synthesis, particularly type I collagen. Our findings suggest that silencing CTGF expression might facilitate a potential therapeutic approach for SSc.

Relevance of the stroma and epithelial-mesenchymal transition (EMT) for the rheumatic diseases

Epithelial-mesenchymal transition (EMT) is a term applied to the process whereby cells undergo a switch from an epithelial phenotype with tight junctions, lateral, apical, and basal membranes, and lack of mobility into mesenchymal cells that have loose interactions with other cells, are non-polarized, motile and produce an extracellular matrix. The importance of this process was initially recognized from a very early step in embryology, but more recently as a potential mechanism for the progression and spread of epithelial cancers. As the sequence of morphological changes has become understood in molecular terms, diseases characterized by alterations in stromal elements and fibrosis are being considered as examples of EMT. This review will focus on the pathogenetic features of immune-mediated renal disease, systemic sclerosis and rheumatoid arthritis that could be explained by EMT.

Monocyte chemoattractant protein 1 released from glycosaminoglycans mediates its profibrotic effects in systemic sclerosis via the release of interleukin-4 from T cells

OBJECTIVE

Monocyte chemoattractant protein 1 (MCP-1; CCL2) has been implicated in the pathogenesis of fibrotic diseases and is up-regulated in patients with systemic sclerosis (SSc). The aim of the present study was to examine the mechanisms by which MCP-1 mediates its profibrotic effects in the setting of SSc.

METHODS

The expression of receptors for MCP-1 on dermal fibroblasts was analyzed by real-time polymerase chain reaction and fluorescence-activated cell sorting. The ability of extracellular matrix proteins to bind and release MCP-1 was quantified by enzyme-linked immunosorbent assay. Th0 cells were isolated using a magnetic-activated cell sorting system and were stimulated twice in the presence of MCP-1. The synthesis of collagen was measured using the Sircol collagen assay kit.

RESULTS

The glycosaminoglycan chondroitin sulfate, but not fibronectin or collagens, bound and released MCP-1 in a time-dependent manner. MCP-1 that was released from chondroitin sulfate induced the differentiation of interleukin-4 (IL-4)-producing T cells in a dose-dependent manner. In turn, dermal fibroblasts from patients with SSc expressed IL-4 receptor, and stimulation with IL-4 significantly increased the production of collagen in dermal fibroblasts. In contrast, CCR2a and CCR2b, as well as D6 and US28 (other potential receptors of MCP-1), were not detectable in SSc and normal fibroblasts, and their expression was not induced by platelet-derived growth factor, IL-1beta, or IL-4. In addition, MCP-1 had no direct effects on collagen production by fibroblasts.

CONCLUSION

MCP-1 has no direct effects on dermal fibroblasts but contributes to fibrosis in patients with SSc by inducing the differentiation of IL-4-producing T cells. Because MCP-1 has both proinflammatory and profibrotic effects, pharmacologic targeting of MCP-1 could be a promising therapeutic approach in SSc.

Matrix contraction by dermal fibroblasts requires transforming growth factor-beta/activin-linked kinase 5, heparan sulfate-containing proteoglycans, and MEK/ERK: insights into pathological scarring in chronic fibrotic disease

Scarring is characterized by excessive synthesis and contraction of extracellular matrix. Here, we show that fibroblasts from scarred (lesional) areas of patients with the chronic fibrotic disorder diffuse scleroderma [diffuse systemic sclerosis (dSSc)] show an enhanced ability to adhere to and contract extracellular matrix, relative to fibroblasts from unscarred (nonlesional) areas of dSSc patients and dermal fibroblasts from normal, healthy individuals. The contractile abilities of normal and dSSc dermal fibroblasts were suppressed by blocking heparin sulfate-containing proteoglycan biosynthesis or antagonizing transforming growth factor-beta receptor type I [activin-linked kinase (ALK5)] or ras/mitogen-activated protein kinase (MEK)/extracellular signal-regulated kinase (ERK). Compared with both normal and nonlesional fibroblasts, lesional dSSc fibroblasts overexpressed the heparin sulfate-containing proteoglycan syndecan 4. We also found that the procontractile signals from transforming growth factor (TGF)-beta were integrated through syndecan 4 and MEK/ERK because the ability of TGFbeta to induce contraction of dermal fibroblasts was prevented by MEK antagonism. TGFbeta could not induce a contractile phenotype or phosphorylate ERK in syndecan 4(-/-) dermal fibroblasts. These results suggest that integrating TGFbeta and ERK signals via syndecan 4 is essential for the contractile ability of dermal fibroblasts. We conclude that antagonizing MEK/ERK, TGFbeta1/ALK5, or syndecan 4 may alleviate scarring in chronic fibrotic disease.

Chronic progressive sensory ataxic neuropathy associated with limited systemic sclerosis

We report the case of a 33-year-old woman with limited systemic sclerosis and chronic progressive sensory ataxic neuropathy. Sural nerve biopsy showed loss of myelinated fibers mostly those of large diameter, axonal degeneration and infiltration of macrophages, but no signs of vasculitis. Physical examination, laboratory testing, neurophysiological and neuroradiological examinations suggested that the dorsal root was primarily affected in this patient. Cytokine analysis by multiplex bead array assay revealed that IL-1beta and GM-CSF were increased both in serum and CSF. Although her symptoms did not respond to corticosteroid therapy, intravenous immunoglobulin (IVIg) therapy resulted in marked improvement. IVIg could be effective in case of immune-mediated reversible neuronal dysfunction associated with collagen disease without vasculitis.

Inhibition of systemic sclerosis dermal fibroblast type I collagen production and gene expression by simvastatin

OBJECTIVE

To examine whether statins are capable of modulating collagen gene expression in cultured systemic sclerosis dermal fibroblasts.

METHODS

Cultured dermal fibroblasts from 3 patients with diffuse systemic sclerosis of recent onset were treated with 5 microM and 10 microM of simvastatin for 3 or 4 days. Morphologic features, cytotoxicity, and type I collagen production and messenger RNA (mRNA) levels in the fibroblasts were examined. The effects of mevalonate, geranylgeranyl pyrophosphate (GGPP), and farnesyl pyrophosphate (FPP), which are lipids downstream from the hydroxymethylglutaryl-coenzyme A block, were also examined. Transient transfections with COL1A1 promoter-reporter constructs and electrophoretic gel mobility shift assays were utilized to examine COL1A1 transcription and Sp1 and CCAAT-box binding factor (CBF) binding.

RESULTS

Simvastatin did not cause morphologic changes or cytotoxicity in the fibroblasts, even after 4 days of treatment. Type I collagen production and mRNA levels showed a potent and dose-related inhibition following 3 and 4 days of treatment. The inhibition of collagen gene expression by simvastatin was completely reversed by mevalonate and GGPP, but not by FPP. The statin effects occurred at the transcriptional level and involved the proximal COL1A1 promoter region encompassing -174 bp. A significant reduction in Sp1 and CBF binding activity was also found in simvastatin-treated cells.

CONCLUSION

Simvastatin is a powerful inhibitor of type I collagen gene expression in normal and systemic sclerosis fibroblasts. The pleiotropic protective effects of statins on various endothelial and immune cell functions in conjunction with their potent inhibitory effects on type I collagen gene expression suggest that statins may be effective therapeutic agents in systemic sclerosis.

Contribution of activin receptor–like kinase 5 (transforming growth factor β receptor type I) signaling to the fibrotic phenotype of scleroderma fibroblasts

OBJECTIVE

To use a specific transforming growth factor beta receptor type I (TGFbetaRI; activin receptor-like kinase 5 [ALK-5]) kinase inhibitor (SD208) to determine the role of activation of the TGFbetaRI kinase (ALK-5) in maintaining the profibrotic phenotype of dermal fibroblasts in systemic sclerosis (SSc).

METHODS

The effect of SD208 on the expression of key biochemical markers of the fibrotic phenotype was compared in fibroblasts cultured from clinically involved (lesional) and clinically uninvolved skin of patients with diffuse cutaneous SSc (dcSSc) and in fibroblasts from healthy controls matched for age, sex, and anatomic site. Protein expression was compared together with the ability of fibroblasts to adhere to the extracellular matrix and to remodel and contract a free-floating fibroblast-populated type I collagen lattice.

RESULTS

Inhibiting TGFbetaRI kinase reduced the expression of a cohort of fibrotic markers by dermal fibroblasts from patients with dcSSc, including type I collagen and beta1 integrin. Moreover, inhibition also attenuated the elevated adhesive and contractile abilities of dcSSc fibroblasts.

CONCLUSION

Our data suggest that some of the key profibrotic features of lesional SSc fibroblasts are dependent upon ALK-5 activity. Thus, TGFbetaRI kinase-mediated signaling may contribute to dermal fibrosis in dcSSc.

Constitutively phosphorylated Smad3 interacts with Sp1 and p300 in scleroderma fibroblasts

OBJECTIVE

To elucidate the role of transforming growth factor-beta (TGF-beta)/Smad signalling in the increased expression of the collagen gene in systemic sclerosis (SSc) fibroblasts.

METHODS

Dermal fibroblasts from seven patients with diffuse SSc of recent onset and from seven healthy individuals were studied. The expression levels of Smad2, Smad3 and Smad4 proteins were determined by immunoblotting. Smad3 phosphorylation and the interaction of Smad3 with Sp1 or p300 were analysed using immunoprecipitation. The effects of overexpression of Smad proteins or Sp1 on the human alpha2(I) collagen gene transcription were investigated with chloramphenicol acetyltransferase (CAT) assays using the -772 COL1A2/CAT construct.

RESULTS

Constitutive increased Smad3 phosphorylation was detected in SSc fibroblasts compared with normal fibroblasts. Increased interaction of Smad3 with Sp1 as well as p300 was also detected in SSc fibroblasts. The overexpression of Smad3 caused an increase of up to 5-fold in COL1A2 promoter activity in normal fibroblasts, while Smad3 caused a small increase in COL1A2 promoter activity in SSc fibroblasts. However, neither Smad2 nor Smad4 caused significant effects in COL1A2 promoter activity in normal fibroblasts or SSc fibroblasts. The overexpression of Sp1 caused further increase in COL1A2 promoter activity stimulated by TGF-beta in normal fibroblasts, but did not change COL1A2 promoter activity in the presence of TGF-beta in SSc fibroblasts. The combined overexpression of Smad3 and Sp1 significantly enhanced TGF-beta response in normal fibroblasts, but less markedly in SSc fibroblasts.

CONCLUSIONS

These results suggested that SSc fibroblasts are less sensitive to exogenous TGF-beta stimulation because they are already activated by the autocrine TGF-beta loop.

Lipid peroxidation and trace elements in systemic sclerosis

Oxidative stress appears to be important in the causation and perpetuation of tissue injury and fibrosis in systemic sclerosis or scleroderma (SSc). We conducted a case-control study to assess lipid peroxidation levels as determined by measuring fasting plasma malondialdehyde (MDA) and serum levels of the trace elements selenium, iron, zinc and copper in SSc. Plasma MDA levels were almost tenfold higher in patients than in controls (p=0.00007), and an inverse relationship between MDA levels and disease duration (r=-0.52, p=0.044) was observed. Selenium levels were lower in patients than in controls (p=0.012). Within the patient cohort, copper correlated inversely with the total skin score (r=-0.52, p=0.03). Our findings provide further evidence that lipid peroxidation is increased and antioxidant capacity is reduced in SSc. The gradual decline in MDA levels with time suggests that antioxidant therapy, if to be useful in SSc, is most likely to be effective early in the course of the disease.

Topical application of a peptide inhibitor of transforming growth factor-beta1 ameliorates bleomycin-induced skin fibrosis

Transforming growth factor-beta (TGF-beta) plays a crucial role in the pathogenesis of skin fibrotic diseases. Systemic TGF-beta inhibitors effectively inhibit fibrosis in different animal models; however, systemic inhibition of TGF-beta raises important safety issues because of the pleiotropic physiological effects of this factor. In this study, we have investigated whether topical application of P144 (a peptide inhibitor of TGF-beta1) ameliorates skin fibrosis in a well-characterized model of human scleroderma. C3H mice received daily subcutaneous injections of bleomycin for 4 wk, and were treated daily with either a lipogel containing P144 or control vehicle. Topical application of P144 significantly reduced skin fibrosis and soluble collagen content. Most importantly, in mice with established fibrosis, topical treatment with P144 lipogel for 2 wk significantly decreased skin fibrosis and soluble collagen content. Immunohistochemical studies in P144-treated mice revealed a remarkable suppression of connective tissue growth factor expression, fibroblast SMAD2/3 phosphorylation, and alpha-smooth muscle actin positive myofibroblast development, whereas mast cell and mononuclear cell infiltration was not modified. These data suggest that topical application of P144, a peptide inhibitor of TGF-beta1, is a feasible strategy to treat pathological skin scarring and skin fibrotic diseases for which there is no specific therapy.

Connective tissue growth factor causes persistent proalpha2(I) collagen gene expression induced by transforming growth factor-beta in a mouse fibrosis model

Skin fibrotic disorders such as systemic sclerosis (SSc) are characterized by an excessive production of extracellular matrix (ECM) and understood to develop under the influence of certain growth factors. Connective tissue growth factor (CTGF) is a cysteine-rich mitogenic peptide that is implicated in various fibrotic disorders and induced in fibroblasts after activation with transforming growth factor-beta (TGF-beta). To better understand the mechanisms of persistent fibrosis seen in SSc, we previously established an animal model of skin fibrosis induced by exogenous application of growth factors. In this model, TGF-beta transiently induced subcutaneous fibrosis and serial injections of CTGF after TGF-beta caused persistent fibrosis. To further define the mechanisms of skin fibrosis induced by TGF-beta and CTGF in vivo, we investigated in this study, the effects of growth factors on the promoter activity of the proalpha2 (I) collagen (COL1A2) gene in skin fibrosis. For this purpose, we utilized transgenic reporter mice harboring the -17 kb promoter sequence of the mouse COL1A2 linked to either a firefly luciferase gene or a bacterial beta-galactosidase gene. Serial injections of CTGF after TGF-beta resulted in a sustained elevation of COL1A2 mRNA expression and promoter activity compared with consecutive injection of TGF-beta alone on day 8. We also demonstrated that the number of fibroblasts with activated COL1A2 transcription was increased by serial injections of CTGF after TGF-beta in comparison with the injection of TGF-beta alone. Furthermore, the serial injections recruited mast cells and macrophages. The number of mast cells reached a maximum on day 4 and remained relatively high up to day 8. In contrast to the kinetics of mast cells, the number of macrophages was increased on day 4 and continued to rise during the subsequent consecutive CTGF injections until day 8. These results suggested that CTGF maintains TGF-beta-induced skin fibrosis by sustaining COL1A2 promoter activation and increasing the number of activated fibroblasts. The infiltrated mast cells and macrophages may also contribute to the maintenance of fibrosis.

Autoantibodies to a collagen-specific molecular chaperone, heat-shock protein 47, in systemic sclerosis

Heat-shock proteins are highly conserved and immunogenic proteins, which may be involved in the initiation and perpetuation of autoimmune diseases. Heat-shock protein 47 (HSP47) is expressed by collagen-secreting cells such as fibroblasts and serves as a collagen-specific molecular chaperone that plays a crucial role in collagen metabolism. Abnormal collagen accumulation and autoimmunity are characteristics of systemic sclerosis (SSc). We determined the presence and prevalence of autoantibodies to HSP47 in patients with SSc and also in tight-skin (TSK/+) mice, an animal model for SSc. Anti-HSP47 autoantibodies were present in SSc patients with a frequency of 26%, while patients with systemic lupus erythematosus, those with dermatomyositis, those with keloid and healthy subjects did not have anti-HSP47 antibodies. IgG1 and IgG2 were the major Ig isotypes of the autoantibodies. Patients positive for anti-HSP47 had a significantly shorter duration of disease than those who were negative. Anti-HSP47 autoantibodies were also positive in 79% of TSK/+ mice. Thus, autoantibodies to HSP47 were present in the sera from SSc patients as well as those from TSK mice, and may be associated with the pathogenesis of SSc.

Haematopoietic stem cell transplantation for the treatment of systemic sclerosis and other autoimmune disorders

Systemic sclerosis (SSc) with involvement of vital organs has up to 50% 5-year mortality and no treatment is known which changes the natural history. Although components of vascular, immunological and fibrotic processes are involved, drugs such as cyclophosphamide (CY), an alkylating agent and a potent immunosuppressive, have been partially effective in uncontrolled studies. The dose of such agents is limited by the inevitable toxicity on the bone marrow, but this threshold may be superseded by first removing the patient's own haematopoietic stem cells, followed by reconstitution of the marrow after high-dose myeloablative CY or other therapy. This autologous haematopoietic stem cell transplantation (HSCT) technique has been applied to approximately 650 patients with severe autoimmune diseases worldwide, > 100 of whom had SSc. Of these, 75 are included in the Basle registry. Around 70% of patients responded with a significant (> 25%) improvement of the thickened skin and stabilisation of vital organ involvement. Approximately a third achieved a durable remission. The treatment-related mortality was 8.5%. Based on these encouraging Phase I/II study results, several multi-centre, international, prospective randomised Phase III trials are running or being planned. The preliminary data suggest that through such a jolt of heavy immunosuppression, the dysregulated autoaggressive immune system may be re-regulated. It is hypothesised that this results in fewer autoinflammatory and unwanted stimulatory signals to other systems such as vascular endothelium and fibroblasts, and these mechanisms are currently under study.

Autoantibody against matrix metalloproteinase-3 in patients with systemic sclerosis

Systemic sclerosis (SSc) is characterized by multi-organ fibrosis with an autoimmune background. Although autoantibodies are detected frequently in SSc patients, the role of autoantibody in the development of fibrosis remains unknown. Connective tissue homeostasis is a balance between the synthesis and degradation of the extracellular matrix (ECM); ECM degradation is regulated mainly by matrix metalloproteinases (MMPs). Anti-MMP-1 antibody is suggested to inhibit MMP-1 and be involved in the development of the fibrosis in SSc. However, the accumulation of various ECM components in the tissue of SSc cannot be explained by the anti-MMP-1 antibody alone. In this study, we examined the presence or levels of antibody to MMP-3, a protein which degrades various ECM components relevant to SSc fibrosis. Enzyme-linked immunosorbent assay (ELISA) using human recombinant MMP-3 revealed that IgG anti-MMP-3 autoantibody levels were elevated significantly in the sera from SSc patients, but not in patients with active systemic lupus erythematosus or dermatomyositis. IgG and IgM anti-MMP-3 antibody levels were significantly higher in diffuse cutaneous SSc, a severe form, than those in limited cutaneous SSc. Consistently, IgG anti-MMP-3 antibody levels correlated significantly with fibrosis of the skin, lung and renal blood vessels. The presence of IgG anti-MMP-3 autoantibody in sera from SSc patients was confirmed by immunoblotting analysis. Remarkably, MMP-3 activity was inhibited by IgG anti-MMP-3 antibody. These results suggest that anti-MMP-3 antibody is a serological marker that reflects the severity of SSc and also suggest that it may contribute to the development of fibrosis by inhibiting MMP-3 activity and reducing the ECM turnover.

A Role for the Androgen Receptor in Collagen Content of the Skin

Collagen, the major macromolecular component of skin, is responsible for maintaining the structural integrity of the tissue as well as for providing important functional characteristics, such as pliability and thickness. We have been studying the structure and regulation of collagen in mouse mutations affecting the skin. In the course of these studies, we found that there are significant differences in collagen content between the skin of wild-type male and female mice, which become evident at puberty. Furthermore, male mice with an X-linked mutation in the androgen receptor gene (formerly called testicular feminization and abbreviated as Ar(Tfm)) showed decreased levels of collagen, indicating that the androgen receptor pathway contributes to the observed differences. These findings demonstrate that there are striking differences in the collagen content of skin between male and female mice, and provide a biochemical explanation for these differences.

Vaskul�re Ver�nderungen in der Pathogenese der systemischen Sklerose

Systemic sclerosis (SSc, scleroderma) is a connective tissue disease of unknown etiology. Perivascular inflammatory infiltrates and endothelial apoptosis with an impaired angiogenesis are observed in early stages of the disease, whereas later stages are characterized by an excessive accumulation of extracellular matrix proteins in the skin and various internal organs. Consistent with the ongoing endothelial cell damage, various markers of endothelial cells such as endothelin-1, sICAM-1, s-VCAM-1 and thrombomodulin are found in high levels in the serum of SSc patients. Surprisingly, the vascular endothelial growth factor (VEGF), a potent angiogenic molecule, is overexpressed in the skin of patients with SSc despite insufficient angiogenesis. Interestingly, patients suffering from diffuse SSc and patients without finger tip ulcers show higher VEGF levels compared to age- and sex-matched controls. These results indicate that a controlled overexpression of VEGF might help to protect against the manifestation of ischemic conditions. On the other hand, data from animal models indicate that a long-term, uncontrolled overexpression of VEGF might have paradox effects on the formation of new vessels leading to capillary changes similar to those observed in SSc. In addition to the impaired angiogenesis, defective vasculogenesis might contribute to the vascular symptoms of SSc.

Altered B lymphocyte function induces systemic autoimmunity in systemic sclerosis

Systemic sclerosis (SSc) is a connective tissue disease characterized by excessive extracellular matrix deposition in the skin and visceral organs. SSc is associated with immune activation characterized by autoantibody production, lymphocyte activation, and release of various cytokines. The presence of autoantibodies is a central feature of immune activation in SSc. Although autoantibodies are thought to be closely linked to the pathogenesis of SSc, the pathogenic relationship between systemic autoimmunity and the clinical manifestations of SSc, including skin fibrosis, remains unknown. Recent studies have revealed that B cells play a critical role in systemic autoimmunity and disease expression through various functions, including cytokine production in addition to autoantibody production. The B cell signaling thresholds are regulated by response regulators that augment or diminish B cell signals during responses to self and foreign antigens. Abnormal regulation of the response regulator function and expression may result in autoantibody production. Among these response regulators, CD19, which is a critical cell-surface signal transduction molecule of B cells, is the most potent positive regulator. Transgenic mice that overexpress CD19 by approximately 3-fold lose tolerance and generate autoantibodies spontaneously. B cells from SSc patients exhibit a 20%-increase in CD19 expression that induces SSc-specific autoantibody production in transgenic mice. Furthermore, SSc patients have intrinsic B cell abnormalities characterized by expanded naive B cells, activated but diminished memory B cells, and chronic hyper-reactivity of memory B cells, possibly due to CD19 overexpression. Similarly, B cells from a tight-skin mouse, a model of SSc, show augmented CD19 signaling and chronic hyper-reactivity. Remarkably, CD19 loss results in inhibition of chronic B cell hyper-reactivity and elimination of autoantibody production, which is associated with improvement in skin fibrosis and a parallel decrease in IL-6 production by B cells. Thus, chronic B cell activation resulting from augmented CD19 signaling leads to skin fibrosis possibly through IL-6 overproduction, as well as autoantibody production, in tight-skin mice and SSc patients.

Histopathological changes of cervical tissue in women with systemic sclerosis

Systemic sclerosis is a connective tissue disease that can affect almost any organ of the body. The clinical aspects of systemic sclerosis on the reproductive system have been studied in large series, and an increased rate of cesarean section has been reported. For this reason, in the present study the histopathological features of cervical specimens of hysterectomyzed women with systemic sclerosis were evaluated. An increased frequency of vascular and stromal abnormalities in cervical specimens of women with systemic sclerosis were observed. Vascular medial hypertrophy, intimal thickening, and fibrosis were more often encountered in the cervical specimens of the patients with systemic sclerosis. Some of the histopathological features also showed correlation with the clinical profile of the disease. The patients with vascular medial hypertrophy in their cervical specimens were older, had a higher Rodnan score, and had longer duration of the disease. In contrast to vascular medial hypertrophy, periadventitial edema was found in the cervical specimens of the patients who were younger, had a lower Rodnan score, and had shorter duration of the disease. It was concluded that the problems that are seen in common obstetric and gynecological practices in patients with systemic sclerosis may be explained by these tissue abnormalities.

B-Myb acts as a repressor of human COL1A1 collagen gene expression by interacting with Sp1 and CBF factors in scleroderma fibroblasts

We investigated the role of B-Myb, a cell-cycle-regulated transcription factor, in the expression of the alpha1 (I) pro-collagen gene (COL1A1) in scleroderma fibroblasts. Scleroderma or SSc (systemic sclerosis) is a fibrotic disease characterized by excessive production of extracellular matrix components, especially type I collagen. Northern-blot analysis showed an inverse relationship between COL1A1 mRNA expression and that of B-Myb during exponential cell growth and during quiescence in human SSc fibroblasts. Overexpression of B-Myb in SSc fibroblasts was correlated with decreased COL1A1 mRNA expression. Transient transfections localized the down-regulatory effect of B-Myb to a region containing the proximal 174 bp of the COL1A1 promoter that does not contain B-Myb consensus binding sites. Gel-shift analysis, using nuclear extracts from normal and SSc fibroblasts transfected with B-Myb, showed no differences in DNA-protein complex formation when compared with the nuclear extracts from mock-transfected cells. However, we found that B-Myb decreases Sp1 (specificity protein 1) and CBF (CCAAT-binding factor) binding for their specific sites localized in the 174 bp COL1A1 proximal promoter. These results were also confirmed using B-Myb-immunodepleted nuclear extracts. Furthermore, immunoprecipitation assays using SSc nuclear extracts demonstrated a physical interaction of B-Myb with Sp1 and CBF transcription factors, and also an interaction between Sp1 and CBF. In addition, by employing full-length or deleted B-Myb cDNA construct, we found that B-Myb down-regulates the COL1A1 proximal promoter through its C-terminal domain. Thus these results suggest that B-Myb may be an important factor in the pathway(s) regulating collagen production in SSc fibroblasts.

Endothelin-1 promotes myofibroblast induction through the ETA receptor via a rac/phosphoinositide 3-kinase/Akt-dependent pathway and is essential for the enhanced contractile phenotype of fibrotic fibroblasts

The endothelins are a family of endothelium-derived peptides that possess a variety of functions, including vasoconstriction. Endothelin-1 (ET-1) is up-regulated during tissue repair and promotes myofibroblast contraction and migration, hence contributing to matrix remodeling during tissue repair. Here, we show that addition of ET-1 to normal lung fibroblasts induces expression of proteins that contribute to a contractile phenotype, including alpha-smooth muscle actin (alpha-SMA), ezrin, moesin, and paxillin. We confirm that ET-1 enhances the ability of lung fibroblasts to contract extracellular matrix, a function essential for tissue repair, through induction of de novo protein synthesis. Blockade of the Akt/phosphoinositide 3-kinase (PI3-kinase) pathway with LY294002 and wortmannin prevents the ability of ET-1 to induce alpha-SMA, ezrin, paxillin, and moesin and to promote matrix contraction. Dominant negative rac and Akt blocked the ability of ET-1 to promote formation of alpha-SMA stress fibers. Using specific ET-1 receptor inhibitors, we show that ET-1 induces collagen matrix contraction through the ETA, but not the ETB, receptor. Relative to normal pulmonary fibroblasts, fibroblasts cultured from scars of patients with the fibrotic disease systemic sclerosis (scleroderma) show enhanced ET-1 expression and binding. Systemic sclerosis lung fibroblasts show increased ability to contract a collagen matrix and elevated expression of the procontractile proteins alpha-SMA, ezrin, paxillin, and moesin, which are greatly reduced by antagonizing endogenous ET-1 signaling. Thus, blocking ET-1 or the PI3-kinase/Akt cascades might be beneficial in reducing scar formation in pulmonary fibrosis.

Selective cleavage of nucleolar autoantigen B23 by granzyme B in differentiated vascular smooth muscle cells: insights into the association of specific autoantibodies with distinct disease phenotypes

OBJECTIVE

To investigate the association of specific autoantibodies with distinct disease phenotypes. The association of autoantibodies to nucleophosmin/B23 with pulmonary hypertension in scleroderma, and the susceptibility of autoantigens to cleavage by granzyme B (GB), provided a focus for these studies.

METHODS

Intact cells were subjected to cytotoxic lymphocyte granule-induced death, and the susceptibility of autoantigens to cleavage by GB was addressed by immunoblotting and/or by a novel immunofluorescence assay.

RESULTS

B23 was cleaved efficiently by GB in vitro, but was highly resistant to cleavage by GB during cytotoxic lymphocyte granule-mediated death of many intact cell types. In contrast, this molecule was highly susceptible to GB-mediated proteolysis exclusively in differentiated vascular smooth muscle cells. Topoisomerase I and several other GB substrates did not show this striking change in cleavage susceptibility in different cell types.

CONCLUSION

These data demonstrate that the cleavage of B23 by GB in intact cells is dependent upon both cell type and phenotype. The susceptibility of this autoantigen (which is associated with a distinct pulmonary vascular phenotype in scleroderma) to GB-mediated proteolysis selectively in vascular smooth muscle cells suggests that the GB-cleavable conformation of autoantigens may occur selectively in the target tissue, and may play a role in shaping the phenotype-specific autoimmune response.

Die Extrakorporale Photopherese bei Progressiver Systemischer Sklerodermie: Unterscheidung von Respondern und Non-Respondern. Extracorporeal photopheresis in progressive systemic sclerosis: discrimination of responders and non-responders

BACKGROUND

The benefit of extracorporeal photopheresis (ExP) in progressive systemic sclerosis (PSS) is controversial. There is limited experience with the long-term use of ExP in PSS. The purpose of the present study was to distinguish between responders and non-responders by using ExP in PSS and to evaluate activation markers for PSS.

PATIENTS AND METHODS

20 subjects with PSS were treated for 12 months with ExP (interval: 1x/month) as an immunomodulating monotherapy (11/20) or combination therapy (9/20). The course of PSS was assessed by both specially designed clinical score and serological parameters (CRP, ANA, beta-galactosidase, P-III-P, CD4/CD8-ratio, TNF-alpha, 11-2-R, 11-6).

RESULTS

After 12 cycles of ExP, 30% of the subjects showed a partial remission and 25%, stable disease (55% responders) while 45% had a progression (non-responders). Although there was no correlation between the clinical course and the serological parameters, an increase of beta-galactosidase during therapy marked a progression of PSS in non-responders. Responders with a short PSS-course before ExP, moderate ANA titres, normal TNF-alpha levels and lack of Scl-70 had a good prognosis.

CONCLUSIONS

About the half of the subjects with PSS profited by the long-term use of ExP. Thereby the mild immunomodulating effect of ExP seems to be insufficient to control markedly progressive courses of PSS.

Transcriptional inhibition of type I collagen gene expression in scleroderma fibroblasts by the antineoplastic drug ecteinascidin 743

We previously showed that COL1A1 expression is up-regulated at the transcriptional level in systemic sclerosis (SSc) fibroblasts and that the CCAAT-binding factor (CBF) is involved in this increased expression. Ecteinascidin 743 (ET-743) is a chemotherapeutic agent that binds with sequence specificity to the minor groove of DNA and inhibits CBF-mediated transcriptional activation of numerous genes. Therefore, we examined the effects of ET-743 on the increased COL1A1 expression in SSc fibroblasts. The drug caused a potent and dose-dependent inhibition of type I collagen biosynthesis, which reached 70-90% at 700 pM without affecting cell viability. The same drug concentration caused 60-80% reduction in COL1A1 mRNA levels. The stability of the corresponding transcripts was not affected. In vitro nuclear transcription assays demonstrated a 54% down-regulation of COL1A1 transcription. Transient transfections with COL1A1 promoter constructs containing the specific CBF binding sequence into SSc cells previously treated with 700 pM ET-743 failed to show an effect on COL1A1 promoter activity. Furthermore, ET-743 did not affect the binding of CBF or Sp1 transcription factors to their cognate COL1A1 elements. However, treatment with 700 pM ET-743 of stably transfected NIH 3T3 cells expressing a human type II procollagen gene under the control of the human COL1A1 promoter caused a greater than 50% reduction in the production of type II procollagen and a similar decrease in the corresponding type II procollagen transcripts. These results indicate that ET-743 is a potent inhibitor of COL1A1 transcription. However, this effect cannot be explained by a direct effect on CBF binding to the COL1A1 promoter. Although the exact mechanisms responsible for the transcriptional inhibition of COL1A1 by ET-743 are not apparent, our observations suggest that the drug may be an effective agent to decrease collagen overproduction in SSc and other fibrotic diseases.