Expression of class II-MHC antigens in the dermis of patients with progressive systemic sclerosis

Engineered extracellular vesicles from human skin cells induce pro-β-cell conversions in pancreatic ductal cells

Direct nuclear reprogramming has the potential to enable the development of β cell replacement therapies for diabetes that do not require the use of progenitor/stem cell populations. However, despite their promise, current approaches to β cell-directed reprogramming rely heavily on the use of viral vectors. Here we explored the use of extracellular vesicles (EVs) derived from human dermal fibroblasts (HDFs) as novel non-viral carriers of endocrine cell-patterning transcription factors, to transfect and transdifferentiate pancreatic ductal epithelial cells (PDCs) into hormone-expressing cells. Electrotransfection of HDFs with expression plasmids for Pdx1, Ngn3, and MafA (PNM) led to the release of EVs loaded with PNM at the gene, mRNA, and protein level. Exposing PDC cultures to PNM-loaded EVs led to successful transfection and increased PNM expression in PDCs, which ultimately resulted in endocrine cell-directed conversions based on the expression of insulin/c-peptide, glucagon, and glucose transporter 2 (Glut2). These findings were further corroborated in vivo in a mouse model following intraductal injection of PNM- vs sham-loaded EVs. Collectively these findings suggest that dermal fibroblast-derived EVs could potentially serve as a powerful platform technology for the development and deployment of non-viral reprogramming-based cell therapies for insulin-dependent diabetes.

Potential Biomarkers in Systemic Sclerosis: A Literature Review and Update

Systemic sclerosis (SSc) is a chronic autoimmune disease characterized by dysregulation of the immune system, vascular damage, and fibrosis of the skin and internal organs. Patients with SSc show a heterogeneous phenotype and a range of clinical courses. Therefore, biomarkers that are helpful for precise diagnosis, prediction of clinical course, and evaluation of the therapeutic responsiveness of disease are required in clinical practice. SSc-specific autoantibodies are currently used for diagnosis and prediction of clinical features, as other biomarkers have not yet been fully vetted. Krebs von den Lungen-6 (KL-6), surfactant protein-D (SP-D), and CCL18 have been considered as serum biomarkers of SSc-related interstitial lung disease. Moreover, levels of circulating brain natriuretic peptide (BNP) and N-terminal pro-brain natriuretic peptide (NT-proBNP) can provide diagnostic information and indicate the severity of pulmonary arterial hypertension. Assessment of several serum/plasma cytokines, chemokines, growth factors, adhesion molecules, and other molecules may also reflect the activity or progression of fibrosis and vascular involvement in affected organs. Recently, microRNAs have also been implicated as possible circulating indicators of SSc. In this review, we focus on several potential SSc biomarkers and discuss their clinical utility.

FOXP3, ICOS and ICOSL gene polymorphisms in systemic sclerosis: FOXP3 rs2294020 is associated with disease progression in a female Italian population

Systemic sclerosis (SSc), an autoimmune disorder, is characterized by vasculopathy, inflammation, progressive perivascular and interstitial fibrosis. Its pathogenesis is largely unknown, however strong evidences suggest that genetic predisposition may contribute to SSc development. Several gene polymorphisms involved in regulatory T cell function have been identified in many autoimmune diseases, including SSc. Moreover, dysregulation of co-stimulatory and/or co-inhibitory signals, including ICOS signalling, can lead to autoimmunity. The aim of the present study was to investigate the association of the FOXP3 rs2294020, ICOS rs6726035 and ICOSL rs378299 SNPs with both the susceptibility and the progression to SSc in an Italian case-series of patients. SNP genotyping results were successfully obtained from a total of 350 subjects including 166 individuals with SSc and 184 healthy controls. Although analysis tests did not show any significant associations between the SNPs under study and susceptibility to SSc, the occurrence of FOXP3 rs2294020 in female patients was associated with decreased time to progression from early to definite SSc (allelic model: HR=1.43; CI=1.03-1.99; p=0.03; dominant model: HR=1.54; CI=1.04-2.28; p=0.03). The inclusion of presence of ACA autoantibodies in the model did not significantly change the estimates. No conclusions can be drawn for the susceptibility to the disease or the time to progression in men due to the low statistical power. This study provides evidence of the association of rs2294020 with SSc evolution in female patients, modulating the time of progression from the diagnosis of early SSc to the diagnosis of definite SSc, while no effect on SSc susceptibility per se was found. rs2294020 may be considered a disease-modifying gene-variant rather than a disease-susceptibility SNP in SSc.

Human Lung Fibroblasts Present Bacterial Antigens to Autologous Lung Th Cells

Lung fibroblasts are key structural cells that reside in the submucosa where they are in contact with large numbers of CD4⁺ Th cells. During severe viral infection and chronic inflammation, the submucosa is susceptible to bacterial invasion by lung microbiota such as nontypeable Haemophilus influenzae (NTHi). Given their proximity in tissue, we hypothesized that human lung fibroblasts play an important role in modulating Th cell responses to NTHi. We demonstrate that fibroblasts express the critical CD4⁺ T cell Ag-presentation molecule HLA-DR within the human lung, and that this expression can be recapitulated in vitro in response to IFN-γ. Furthermore, we observed that cultured lung fibroblasts could internalize live NTHi. Although unable to express CD80 and CD86 in response to stimulation, fibroblasts expressed the costimulatory molecules 4-1BBL, OX-40L, and CD70, all of which are related to memory T cell activation and maintenance. CD4⁺ T cells isolated from the lung were predominantly (mean 97.5%) CD45RO⁺ memory cells. Finally, cultured fibroblasts activated IFN-γ and IL-17A cytokine production by autologous, NTHi-specific lung CD4⁺ T cells, and cytokine production was inhibited by a HLA-DR blocking Ab. These results indicate a novel role for human lung fibroblasts in contributing to responses against bacterial infection through activation of bacteria-specific CD4⁺ T cells.

Serum adhesion molecule levels as prognostic markers in patients with early systemic sclerosis: a multicentre, prospective, observational study

Objective

To assess the utility of circulating adhesion molecule levels as a prognostic indicator of disease progression in systemic sclerosis (SSc) patients with early onset disease.

Methods

Ninety-two Japanese patients with early onset SSc presenting with diffuse skin sclerosis and/or interstitial lung disease were registered in a multicentre, observational study. Concentrations of intercellular adhesion molecule (ICAM) −1, E-selectin, L-selectin, and P-selectin in serum samples from all patients were measured by enzyme-linked immunosorbent asssay (ELISA). In 39 patients, adhesion molecule levels were measured each year for four years. The ability of baseline adhesion molecule levels to predict subsequent progression and severity in clinical and laboratory features were evaluated statistically.

Results

At their first visit, serum levels of ICAM-1, E-selection, P-selectin were significantly elevated and serum L-selectin levels were significantly reduced in patients with SSc compared with healthy controls. Overall, serum ICAM-1 levels at each time point were significantly inversely associated with the %vital capacity (VC) of the same time and subsequent years by univariate analysis. The initial serum ICAM-1 levels were significantly inversely associated with the %VC at the fourth year by multiple regression analysis. The initial serum P-selectin levels were significantly associated with the health assessment questionnaire disability index (HAQ-DI) at the fourth year by multiple regression analysis. Initial adhesion molecule levels were not significantly associated with other clinical features including skin thickness score. Baseline adhesion molecule levels were not significantly associated with subsequent rate of change of clinical parameters.

Conclusion

In patients with SSc, serum levels of ICAM-1 and P-selectin may serve as prognostic indicators of respiratory dysfunction and physical disability, respectively. Further longitudinal studies of larger populations are needed to confirm these findings.

Serum chemokine levels as prognostic markers in patients with early systemic sclerosis: a multicenter, prospective, observational study

OBJECTIVE

To assess the utility of serum chemokine levels as a prognostic indicator of disease progression in systemic sclerosis (SSc) patients with early onset disease.

METHODS

Seventy Japanese patients with early onset SSc presenting with diffuse skin sclerosis and/or interstitial lung disease were registered in a multicenter, observational study. Concentrations of CCL2, CCL5, CXCL8, CXCL9, and CXCL10 in serum samples from all patients were measured using cytometric beads array. In 33 patients, chemokine levels were measured each year for 4 years. The ability of baseline chemokine levels to predict changes in clinical features were evaluated statistically by multiple regression analysis.

RESULTS

At their first visit, serum levels of CCL2, CCL5, CXCL8, CXCL9, and CXCL10 were significantly elevated in patients with SSc compared with healthy controls. There were significant associations between CCL2 and CXCL8 levels and between CXCL9 and CXCL10 levels in patients. The initial serum CXCL8 levels were significantly associated with the HAQ-DI at the fourth year while the %VC of baseline tended to be negatively associated with HAQ-DI at the fourth year. Initial chemokine levels were not associated with other clinical features including skin thickness score and the respiratory function.

CONCLUSION

Serum CXCL8 level may serve as a prognostic indicator of the physical dysfunction in SSc. Further longitudinal studies of larger populations are needed to confirm these findings.

Serum chemokine and cytokine levels as indicators of disease activity in patients with systemic sclerosis

To determine the clinical utility of serum levels of chemokines and cytokines for the evaluation of disease activity in patients with systemic sclerosis (SSc), concentrations of four chemokines (interferon γ-inducible protein-10 [IP-10, CXCL10], monokine induced by interferon γ [MIG/CXCL9], monocyte chemoattractant protein-1 [MCP-1/CCL2], interleukin 8 [IL-8/CXCL8]) and six cytokines (IL-2, IL-4, IL-6, IL-10, tumor necrosis factor [TNF]-α, interferon [IFN]- γ) were measured using cytometric beads array kits in serum samples from 31 Japanese patients with SSc and 20 normal controls. Clinical and laboratory data and serum chemokine and cytokine levels were assessed for each patient at their first visit and each subsequent year for 3 years. Among these chemokines and cytokines, serum levels of IP-10, MIG and MCP-1 were significantly elevated in SSc patients compared with normal controls at their first visit. Serum MCP-1 levels declined year and year, along with improvement for skin sclerosis. The variations of MCP-1, but not IP-10 and MIG, were significantly associated with the variations of skin thickness score and vital capacity during 3 years. These results suggest that MCP-1 is a serological indicator of the activity of skin and lung involvement in patients with SSc. However, a longer-term prospective study in a larger population will be needed to confirm its clinical utility as predictors of outcomes.

Chemokines and Chemokine Receptors in Scleroderma

Scleroderma is a connective tissue disease with unknown etiology characterized by excessive deposition of extracellular matrix in the skin. Cellular infiltrates of certain immune cells and proinflammatory mediators are suggested to play a crucial role in cutaneous fibrosis, forming complicated networks between fibroblasts and immune cells via cell-cell communications. Tissue-selective trafficking of leukocytes is mediated by combinations of adhesion molecules and chemokines. Recent studies have shown that an increase in proinflammatory chemokines has been associated with the initiation and/or development of skin fibrosis/sclerosis, suggesting that chemokines and their receptors may be important mediators of inflammation and fibrosis in scleroderma. This review will focus on the roles of chemokines and their receptors during the process of cutaneous sclerosis and will also provide a current insight into the potential mechanisms of scleroderma.

Up regulated expression of fractalkine/CX3CL1 and CX3CR1 in patients with systemic sclerosis

BACKGROUND

Fractalkine expressed on endothelial cells mediates activation and adhesion of leucocytes expressing its receptor, CX(3)CR1. Soluble fractalkine exhibits chemotactic activity for leucocytes expressing CX(3)CR1.

OBJECTIVE

To determine the role of fractalkine and its receptor in systemic sclerosis (SSc) by assessing their expression levels in patients with this disease.

METHODS

The expression of fractalkine and CX(3)CR1 in the skin and lung tissues was immunohistochemically examined. Circulating soluble fractalkine levels were examined by enzyme linked immunosorbent assay (ELISA). Blood samples from patients with SSc were stained for CX(3)CR1 with flow cytometric analysis.

RESULTS

CX(3)CR1 levels on peripheral monocytes/macrophages and T cells were found to be raised in patients with diffuse cutaneous SSc. The numbers of cells expressing CX(3)CR1, including monocytes/macrophages, were increased in the lesional skin and lung tissues from patients with diffuse cutaneous SSc. Fractalkine was strongly expressed on endothelial cells in the affected skin and lung tissues. Soluble fractalkine levels were significantly raised in sera and were associated with raised erythrocyte sedimentation rates, digital ischaemia, and severity of pulmonary fibrosis.

CONCLUSIONS

Up regulated expression of fractalkine and CX(3)CR1 cooperatively augments the recruitment of mononuclear cells expressing CX(3)CR1 into the affected tissue of SSc, leading to inflammation and vascular injury.

Differential effects of the immunosuppressant FK-506 on human ?2(I) collagen gene expression and transforming growth factor ? signaling in normal and scleroderma fibroblasts

OBJECTIVE

To investigate the effects of FK-506 on the expression of the human alpha2(I) collagen gene and transforming growth factor beta (TGFbeta) signaling in normal and scleroderma fibroblasts.

METHODS

The expression levels of type I procollagen protein and alpha2(I) collagen messenger RNA (mRNA) were analyzed by immunoblotting and Northern blotting, respectively. The promoter activities of alpha2(I) collagen gene and 3TP-Lux were determined by transient transfection assay. Interaction between TGFbeta receptor type I and FK-506 binding protein 12 (FKBP12) was evaluated by immunoprecipitation.

RESULTS

FK-506 did not affect the basal expression of type I procollagen protein or alpha2(I) collagen mRNA, but it significantly reduced the TGFbeta1-induced expression of type I procollagen protein and alpha2(I) collagen mRNA in normal fibroblasts. The effect of FK-506 was regulated posttranscriptionally, but not transcriptionally. In scleroderma fibroblasts, FK-506 significantly reduced the expression of type I procollagen protein and alpha2(I) collagen mRNA through posttranscriptional regulation, but not transcriptional regulation. FK-506 increased the basal activity of the 3TP-Lux promoter, but it did not affect the TGFbeta1-induced promoter activity in normal fibroblasts. In contrast, FK-506 did not affect the basal or the TGFbeta1-induced 3TP-Lux promoter activity in scleroderma fibroblasts. Furthermore, FKBP12, which protects TGFbeta receptor type I from ligand-independent activation by TGFbeta receptor type II, constitutively dissociated from TGFbeta receptor type I in scleroderma fibroblasts.

CONCLUSION

FK-506 inhibits alpha2(I) collagen gene expression by reducing the stability of mRNA without exhibiting its activation effect on TGFbeta signaling in scleroderma fibroblasts.

Abnormal expression of intracellular cytokines and chemokine receptors in peripheral blood T lymphocytes from patients with systemic sclerosis

In patients with systemic sclerosis (SSc), there are conflicting findings regarding which is predominant between type 1 and type 2 immune responses. To determine the balance between type 1 and type 2 T lymphocytes in peripheral blood from SSc patients, we investigated the expression of intracellular cytokines, such as interferon-gamma (IFN-gamma), interleukin-2 (IL-2), IL-4, and IL-13, and chemokine receptors such as CXCR3 and CCR4 by flow cytometry. The frequency of IFN-gamma-producing cells among CD8+ cells was significantly increased in patients with diffuse cutaneous SSc (n = 11, P < 0.0001) and limited cutaneous SSc (lSSc; n= 16, P < 0.0001) compared with normal controls (n = 17) while there was no significant difference in the frequency of IL-4- or IL-13-producing cells. In contrast, the frequency of IFN-gamma- or IL-4-producing cells among CD4+ cells was similar between the three groups. Similar results were obtained when absolute numbers were assessed. The frequency of IFN-gamma-producing cells among CD8+ cells inversely correlated with percentage DLco in SSc patients (r = - 0.650, P < 0.005). CXCR3+ CD8+ cells selectively produced IFN-gamma, and the frequency of CXCR3+ CD45RO+ cells among CD8+ cells was higher in lSSc patients (n = 14, P < 0.01) than in normal controls (n = 22). In contrast, there was no significant difference in the frequencies of CXCR3- or CCR4-expressing CD45RO+ cells among CD4+ cells. These results demonstrate the predominance of type 1 cytokine-producing cells (Tc1 cells) in peripheral blood CD8+ T cells from SSc patients, but no definite Th1/Th2 imbalance in CD4+ T cells. Tc1 cells may be associated with pulmonary vascular damage in SSc.

Peripheral blood T lymphocytes from systemic sclerosis patients show both Th1 and Th2 activation

Our objective was to investigate the phenotype of helper T cells in the peripheral blood of patients with systemic sclerosis (SSc). PBMC from 15 patients with SSc and 15 sex- and age-matched controls were investigated for lymphocyte subpopulations (CD3, CD4, CD8, CD19, CD16/CD56, CD3-DR); IL-2, IL-4, and IFN-gamma mRNAs; and the relative cytokines in their cytoplasm. The last assay was carried out both in unstimulated and in PMA-activated PBMC. SSc patients presented a higher percentage of activated T cells, CD3+ DR+ (19.7 +/- 9.9 vs 5.1 +/- 2.5%; P < 0.0001); 12 of them presented IFN-gamma mRNA-positive cells; and none IL-2 or IL-4 mRNAs. Under basal conditions, PBMC from six SSc patients contained IL-2, IL-4, and IFN-gamma (i.e., they showed both Th1 and Th2 activation), and 1 IFN-gamma only. PMA-stimulated PBMC of patients differed from those of controls only in the increased percentage of IFN-gamma positive cells (52 +/- 12 vs 37 +/- 11%; P < 0.01). Our study demonstrates that Thl activation occurs in the peripheral blood of SSc patients. This evidence must be faced with from both a pathogenetic and a therapeutical point of view.

Up-regulation of class II major histocompatibility complex and intercellular adhesion molecule 1 expression on scleroderma fibroblasts and endothelial cells by interferon-gamma and tumor necrosis factor alpha in the early disease stage

OBJECTIVE

To investigate the expression patterns of interferon-gamma (IFN gamma) and tumor necrosis factor alpha (TNF alpha), both of which are potent inducers of class II major histocompatibility complex (MHC) and intercellular adhesion molecule 1 (ICAM-1) expression, and their codistribution with HLA-DR and ICAM-1 in skin lesions, cultured fibroblasts, and peripheral blood mononuclear cells (PBMC) of systemic sclerosis (SSc) patients in different stages of disease.

METHODS

Investigations were carried out using immunohistochemistry studies, reverse transcriptase-polymerase chain reaction, dot-blot hybridization, and cytometric analysis. Serum levels of TNF alpha were determined by enzyme-linked immunosorbent assay.

RESULTS

In the early inflammatory stage of SSc, class II MHC and ICAM-1 expression could be detected on most endothelial cells and on fibroblasts located especially in perivascular areas surrounded by infiltrating lymphocytes, which belong to the T helper 1 phenotype expressing IFN gamma and TNF alpha. In this early disease stage, an enhanced expression of TNF alpha on cultured dermal fibroblasts and PBMC, as well as elevated serum titers of soluble TNF alpha, could be found.

CONCLUSION

These data suggest that class II MHC antigens and ICAM-1 on fibroblasts and endothelial cells are induced by IFN gamma and TNF alpha in an early stage of SSc after the influx of mononuclear-cells, and may be important in the putative autoimmune response and in the perpetuation of fibrotic processes in SSc.

Pathogenesis of scleroderma. Collagen

It is now evident that persistent overproduction of collagen and other connective tissue macromolecules results in excessive tissue deposition, and is responsible for the progressive nature of fibrosis in SSc. Up-regulation of collagen gene expression in SSc fibroblasts appears to be a critical event in the development of tissue fibrosis. The coordinate transcriptional activation of a number of extracellular matrix genes suggests a fundamental alteration in the regulatory control of gene expression in SSc fibroblasts. Trans-acting nuclear factors that bind to cis-acting elements in enhancer and promoter regions of the genes modulate the basal and inducible transcriptional activity of the collagen genes. The identity of the nuclear transcriptional factors that regulate normal collagen gene expression remains to be firmly established, and to date, no alterations in the level or in the activity of such DNA binding factors has been demonstrated in SSc fibroblasts. In addition to important interactions between fibroblasts and the extracellular matrix, cytokines and other cellular mediators can positively and negatively influence fibroblast collagen synthesis. Some of these signaling molecules may have physiologic roles, and their aberrant expression, or altered responsiveness of SSc fibroblasts to them, may result in the acquisition of the activated phenotype. The rapid expansion of knowledge regarding the effects of cytokines on extracellular matrix synthesis has led to an appreciation of the enormous complexity of regulatory networks that operate in the physiologic maintenance of connective tissue and which may be responsible for the occurrence of pathologic fibrosis. The ubiquitous growth factor TGF beta is the most potent inducer of collagen gene expression and connective tissue accumulation yet discovered. The expression of TGF beta in activated infiltrating mononuclear cells suggests a role for this cytokine as a mediator of fibroblast activation in SSc. Furthermore, the recognition that TGF beta is capable of inducing its own expression in a variety of cell types, coupled with the demonstration that a subpopulation of SSc dermal fibroblasts produces TGF beta, indicates the existence of a possible autocrine loop whereby lymphocyte-derived TGF beta in early SSc not only signals biosynthetic activation of fibroblasts in a paracrine manner, but autoinduces endogenous TGF beta production by the target fibroblasts themselves. Such an autocrine loop involving TGF beta may explain the persistent activation of collagen gene expression in SSc fibroblasts, and could be responsible for the progressive nature of fibrosis in SSc. Numerous other cytokines, as well as cell-matrix interactions, also modify collagen gene expression and can significantly influence the effects of TGF beta. Although their physiologic function in tissue remodeling or their involvement in abnormal fibrogenesis has not yet been conclusively demonstrated, the study of the biologic effects of these cytokines may provide important clues to understanding the pathogenesis of SSc, and to the development of rational drug therapy aimed at interrupting the abnormal fibrogenic process in this disease.

Expression of HLA-DR antigen and smooth muscle cell differentiation markers by valvular fibroblasts in degenerative aortic stenosis

OBJECTIVES

This study was designed to analyze the functional characteristics of fibroblasts present in aortic valves with degenerative stenosis.

BACKGROUND

Morphologic analysis of degenerative stenosis of tricuspid aortic valves has revealed an extensive interstitial fibrosis.

METHODS

Stenotic aortic valves collected during aortic valve replacement and control valves collected at autopsy were fixed in formaldehyde, cryosectioned and stained with antibodies against leukocyte markers, HLA-DR and intracellular filaments. Fibroblasts isolated from stenotic valve and skin explants were grown in cell culture, and their proliferative activity was analyzed by cell counting and uptake of tritiated thymidine.

RESULTS

In the stenotic valves nearly all interstitial cells expressed vimentin, and approximately 60% of the cells also expressed alpha-actin and desmin. HLA-DR was present on inflammatory cells as well as on one-third of the fibroblast-like cells in the interstitium. Macrophages were found in the interstitium and T lymphocytes close to calcium deposits and in subendothelial areas. In control valves, fibroblasts expressed vimentin but not alpha-actin or desmin. Few inflammatory cells were present in these valves, and HLA-DR expression was restricted to the endothelial surface. In culture, stenotic valve fibroblasts had a reduced ability to proliferate in serum and to activate DNA synthesis in response to growth factors compared with skin fibroblasts from the same patient.

CONCLUSIONS

The observation that fibroblasts present in aortic valves with degenerative stenosis express smooth muscle cell characteristics and HLA-DR antigen and show signs of cellular senescence in vitro suggests that they are in a state of chronic activation similar to that observed in fibromatosis and scleroderma lesions.

Immune-mediated mechanisms and immune activation of fibroblasts in the pathogenesis of eosinophilia-myalgia syndrome induced by L-tryptophan

To determine the immunopathogenesis of the persistent symptoms of patients with eosinophilia-myalgia syndrome (EMS) induced by L-tryptophan, we performed immunocytochemical studies on 10 muscle and fascia biopsy specimens obtained during the acute disease and the chronic persistent connective tissue sclerosis. A series of monoclonal antibodies was used in a single- or double-immunostaining technique to detect and quantify T-cell subsets, macrophages, major histocompatibility complex antigens, eosinophilic basic protein-positive cells, and resting fibroblasts expressing Thy-I antigen or activated fibroblasts expressing the activation marker F-19. We found inflammatory cells consisting of CD8+ cells (45% +/- 8.9%), T4 cells (36% +/- 10.1%), and macrophages (19% +/- 12%), scattered or perivascularly in the fascia, the perimysium, and the endomysial septae. Only rare granulated or degranulating eosinophils were noted. Many muscle fibers around fascicles or near blood vessels expressed major histocompatibility complex-I antigens. The mean number of fibroblasts in the fascia, the perimysial connective tissue, and the spindle capsule was increased in the EMS patients' specimens compared with the endomysial cells seen in six disease-control muscle biopsy specimens from patients with chronic inflammatory myopathies or dystrophies (P < .01). Up to 70% of the fibroblasts in EMS were activated and up to 30% of them expressed HLA-DR antigen. In the disease controls up to 29% of the fibroblasts were activated but none expressed DR. Repeat muscle biopsy a year later in a patient whose symptoms persisted showed reduced inflammation but an increased number of activated fibroblasts and enhanced DR expression. We conclude that in EMS there is a T-cell-mediated process against components of the extracellular matrix, including fibroblasts, in the fascia and the perimysium that persists even years after the drug is discontinued. Because the fibroblasts are activated and aberrantly express DR antigen, they may be the target cells playing a role in the continuing clinical and histologic signs of tissue sclerosis.

Expression of adhesion proteins involved in cell-cell and cell-matrix interactions in the skin of patients with progressive systemic sclerosis

BACKGROUND

Lymphocytic infiltration and activation of connective tissue metabolism in the early phase of progressive systemic sclerosis (PSS, scleroderma) may be critically influenced by cellular adhesion molecules (CAMs), which mediate cell-cell and cell-extracellular matrix interactions.

OBJECTIVE

The tissue distribution might demonstrate a pathogenetic role of these adhesion molecules in early edematous and chronic fibrotic scleroderma.

METHODS

We investigated by immunohistochemical techniques the in situ expression and distribution of beta 1 and beta 2 integrins, selectins, and CAMs of the immunoglobulin superfamily in patients with scleroderma.

RESULTS

In the early disease stage a moderate percentage of perivascular CD3+/CD4+/TCR alpha/beta + lymphocytes showed expression of the alpha 3, alpha 5, and beta 1 chains and, to a lesser degree, of the alpha 1, alpha 2, alpha 4 and alpha 6 subunits. In contrast to chronic PSS, LFA-1 alpha, LFA-1 beta and ICAM-1 expression on mononuclear infiltrating cells was seen more frequently in acute scleroderma. Different percentages of fibroblasts expressed alpha 1-, alpha 3-, alpha 5- and beta 1-integrin chains. In acute PSS ICAM-1 was expressed especially by fibroblasts located around perivascular inflammatory infiltrates as well as by endothelial cells (ECs). A few ECs expressed alpha 2 beta 1 integrins.

CONCLUSION

Our observations suggest that CAMs are intimately involved in early pathogenetic events in scleroderma, mediating cellular interactions between lymphocytes, ECs, and fibroblasts, as well as homing and tissue targeting of mononuclear infiltrating cells.