Lymphocytes in the skin of patients with progressive systemic sclerosis. Quantification, subtyping, and clinical correlations

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.

Immunopathogenesis of systemic sclerosis

The information outlined above can be used to generate a model of the immunopathogenesis of SSc (Fig. 3). This model includes a susceptible host, with age greater than 25 and female gender being risk factors. The model also includes exposure to exogenous agents, which could be different in different individuals and may include inhaled or ingested chemicals or infectious agents. An early event is T-cell activation, with infiltration in the skin and internal organs. Activation of the T cells is a selective process that appears to be influenced by antigen in SSc patients. The importance of a particular T-cell subpopulation may depend upon the organ involved and the stage of the disease. CD4+ T cells predominate in the skin. In contrast, CD8+ T cells are increased in the lungs of patients with alveolitis, where they are oligoclonal, showing evidence of antigen-driven selection. V delta 1+ gamma/delta T cells are increased in both the blood and lungs of SSc patients and also show evidence of selection by antigen. B cells are activated early, with polyclonal activation leading to hypergammaglobulinemia. SSc-specific autoantibodies target DNA topoisomerase I, centromeric proteins, and RNA polymerases I and III. Characteristics of autoantibodies in SSc suggest that the target antigens are presented to the immune system as native molecules or even part of a multiunit complex. There is some homology between viruses and autoantibody targets in SSc, which suggests that molecular mimicry may play a role in initiating the antibody response. Many nonspecific inflammatory cells infiltrate the tissues and show evidence of activation. These include macrophages and monocytes, mast cells, eosinophils, basophils, and natural killer cells. Soluble mediators made by these T cells, B cells, and nonspecific inflammatory cells can activate and damage fibroblasts, endothelial cells, and other vascular cells. The relative importance of the various candidate cytokines, the temporal sequence of their production, and their cellular sources remain largely to be defined. There may be some contribution of direct T-cell cytotoxicity or antibody-dependent cellular cytoxicity to the tissue damage that occurs.

Safety and efficacy of recombinant gamma interferon in the treatment of systemic sclerosis

OBJECTIVE

To evaluate the safety and efficacy of recombinant gamma interferon (rIFN gamma) in the treatment of patients with systemic sclerosis.

METHODS

Sixteen patients with systemic sclerosis were treated with r-IFN gamma, 60 micrograms m-2 (low dose, n = 10) and 150 micrograms m-2 (high dose, n = 6), three times weekly in an open phase I/II trial of eight months duration. The patients were stratified in low and high dose according to the severity and the extent of scleroderma; the two groups were comparable.

RESULTS

The treatment was well tolerated. The most common side effects, almost certainly related to r-IFN gamma, were fever, chills, dizziness, headache, and severe flu-like syndrome with decreasing intensity with the time of treatment. Severe aphthous stomatitis (n = 1), ventricular tachycardia (n = 1), severe oesophageal ulcers due to gastro-oesophageal reflux (n = 1), disease exacerbation alone with frank arthritis and slight pericardial effusion (n = 1), and inability to conform to the requirements of the study (n = 1) were the reasons for discontinuing treatment. Side effects and degree of response were evident during the first five months of treatment. A significant decrease in mean skin thickness score was observed and was higher in the high dose group. Reactive oxygen species of peripheral neutrophils and soluble interleukin-2 receptor serum concentrations were higher than those of normal individuals at study entry and decreased in parallel with clinical improvement.

CONCLUSIONS

Treatment of systemic sclerosis patients with r-IFN gamma was relatively safe and well tolerated for doses as high as 150 micrograms m-2 three times weekly. Side effects and the degree of response can be seen during the first months of therapy and can be used as predictors of ultimate toxicity or response. The drug seems to be effective in treating cutaneous scleroderma.

Skewing of the CD8+ T-cell repertoire in the lungs of patients with systemic sclerosis

Pulmonary parenchymal involvement in SSc is characterized by alveolitis and interstitial fibrosis, with an increased number of CD8+ T cells in BAL fluids. This study analyzed the diversity of the alphabeta T-cell repertoire in peripheral blood and BAL fluids from seven SSc patients, looking for evidence of antigen-driven selection of T cells in the lungs. A reverse transcriptase-polymerase chain reaction technique was used to amplify rearranged TCR transcripts from unfractionated, CD4+, and CD8+ T cells. Nearly all AV and BV gene families were expressed in SSc patients and most had similar levels of expression in blood and BAL samples. Next, the diversity of TCR junctional region lengths was assessed, using sequencing gel electrophoresis. Many V gene families had a Gaussian distribution of their junctional region lengths. However, some V gene families had an abnormal pattern of junctional lengths, with skewing away from a Gaussian distribution, including predominance of one or two lengths. This suggests selected expansion of T cells expressing those V genes. Alterations in TCR junctional region lengths were most prominent in bronchoalveolar CD8+ T cells, with similar patterns of skewing in several patients and in one patient over time. Sequence analysis of AV14 and BV17 junctional regions confirmed the oligoclonal character of expansion of bronchoalveolar CD8+ T cells.

IgG antiendothelial cell autoantibodies from scleroderma patients induce leukocyte adhesion to human vascular endothelial cells in vitro. Induction of adhesion molecule expression and involvement of endothelium-derived cytokines

IgG autoantibodies that bind human endothelial cells (AECA) were detected by ELISA in 30 of 42 samples of sera from patients with scleroderma. Pretreatment of human umbilical vein endothelial cells with AECA-positive scleroderma sera, or IgG purified from these sera, led to a dose- and time-dependent increase in the ability of the cells to bind human U937 monocytic cells. Threshold-active IgG concentrations were 1-10 micrograms/ml; effects were significant after 3 h and maximal after 6-12 h. IgG from AECA-negative sera or normal sera were without effect. Increased adhesion of U937 cells was accompanied by increased expression of endothelial intercellular adhesion molecule-1, vascular cell adhesion molecule-1, and E-selectin. Transfer of endothelial cell-conditioned media after pretreatment with AECA and immunodepletion of IgG demonstrated the presence of transferable activity that mimicked the effects of AECA. Treatment with neutralizing anticytokine antibodies indicated that IL-1, generated by the endothelial cells in response to AECA, was involved in the upregulation of adhesion molecules and U937 cell adhesion. We conclude that AECA can play a pathogenic role in scleroderma by activating endothelial cells, in part due to autocrine or paracrine actions of IL-1.

Oligoclonal expansion of V delta 1+ gamma/delta T-cells in systemic sclerosis patients

Systemic sclerosis (SSc) is a multisystem disease characterized by T-cell infiltration of involved tissues, fibrosis, and small vessel vasculopathy. Using flow cytometric analyses, we found an increased percentage of gamma/delta T-cells expressing the T-cell antigen receptor variable (V) delta 1 gene segment in the peripheral blood and bronchoalveolar lavage fluid of patients with SSc. To estimate clonality of these V delta 1+ T-cells, the diversity of V delta 1 junctional regions (V-Diversity-Joining gene segments) was examined using a reverse transcriptase-polymerase chain reaction to amplify T-cell antigen receptor delta chain transcripts isolated from peripheral blood mononuclear cells, lung, esophagus, stomach, or skin of patients and controls. Limited diversity of V delta 1-J delta junctional regions in SSc patients was demonstrated by the finding of greater restriction in the nucleotide lengths of junctional region cDNAs in individual SSc patients than in controls. Sequence analyses confirmed that V delta 1-J delta junctional regions from the blood of SSc patients had less diversity than those from controls, in that a significantly higher proportion of sequences were repeated in patients (54.4% vs. 19.4% in controls). Evidence for selection of the V delta 1+ T-cells in tissues of individual SSc patients came from the findings that the same V delta 1-J delta junctional sequences could be isolated from the same tissue over time and that identical V delta 1-J delta junctional sequences could be isolated from multiple tissues. These data suggest that expansion of V delta 1+ gamma/delta T cells may be antigen driven in SSc patients.

Enhanced production of transforming growth factor-beta (TGF-beta) during autologous mixed lymphocyte reaction of systemic sclerosis patients

Systemic sclerosis (SSc) is characterized by systemic fibrosis and microvascular lesions. As TGF-beta is suggested to be related to skin fibrosis, we examined the production of TGF-beta from peripheral mononuclear cells (MNC) of SSc patients. Since anti-TGF-beta neutralizing antibody improved the defective proliferative response in autologous mixed lymphocyte reaction (AMLR) of SSc patients, TGF-beta was thought to participate in the decreased AMLR of SSc patients. Greater amounts of TGF-beta in the active as well as in the latent forms were produced during AMLR of SSc patients than that of normal subjects. It was suggested that TGF-beta excessively produced from the MNC of SSc patients might play a major role in the fibrosis of the patients during AMLR-like in vivo responses.

Specific suppression of lupus-like graft-versus-host disease using extracorporeal photochemical attenuation of effector lymphocytes

(C57BL/6 x DBA/2)F1 (B6D2F1) mice inoculated with parental DBA/2 (D2) splenocytes develop chronic stimulatory graft-versus-host reaction with many of the clinical manifestations of systemic lupus erythematosus. This investigation tested the ability of 8-methoxypsoralen (8-MOP) and ultraviolet A (UVA) light-treated D2 cells, primed to contain an expanded population of T cells specific for B6D2F1 major histocompatability complex antigens, to treat and/or prevent such systemic lupus erythematosus-like disease. 8-MOP/UVA-treated cells from B6D2F1-primed D2 donors were inoculated into B6D2F1 recipients weekly six to ten times, either before or after initiating graft-versus-host disease with normal D2 cells. A third group of B6D2F1 recipients were vaccinated weekly six times before disease initiation using 8-MOP/UVA-attenuated, B6D2F1-primed D2 cells that had been secondarily stimulated and expanded in vitro in the presence of irradiated B6D2F1 targets and interleukin-2. Control B6D2F1 mice were vaccinated with 8-MOP/UVA-treated D2 cells stimulated in vitro and/or in vivo with (C3H/HeJ x DBA/2)F1 cells. Only mice vaccinated with 8-MOP/UVA-attenuated D2-anti-B6D2F1 cells that were secondarily stimulated and expanded in vitro exhibited differences from controls when measured by the clinical parameters of ascites formation, and mean survival (p < 0.025). These groups also differed significantly in mean antinuclear antibody titer measured 14 weeks after disease initiation (p < 0.05). At 28 weeks, histologic evidence of systemic lupus erythematosus-like kidney disease was found only in the control group. These results indicate that photochemically attenuated D2-anti-B6D2F1 cells primed in vivo and secondarily stimulated and expanded in vitro are capable of vaccinating recipients against progression of graft-versus-host reaction-initiated systemic lupus erythematosus-like disease.

Cytokine gene and CD25 antigen expression by peripheral blood T cells from patients with primary Sjögren's syndrome

We studied mononuclear cell subsets in 17 patients with primary Sjögren's syndrome (PSS) and in 11 normal controls by flow cytometry. We found a decreased percentage of CD4+ cells (p = 0.027) and a higher percentage of CD8+ cells in patients as compared to controls. In both, CD4+ cells and CD8+ cells, CD25 antigen was overexpressed (p = 0.005 and p = 0.025, respectively as compared to controls). We then measured spontaneous mRNA cytokine expression by T cells from 7 PSS patients and 5 normal controls by coupled reverse transcription-polymerase chain reaction. We found spontaneous mRNA expression for IFN-gamma, IL-10, IL-13 as well as for CD25. Our results suggest an overall T cell activation in PSS patients and provides evidence of a T cell cytokine regulatory imbalance which may play a role in the pathogenesis of this disease.

Role of T cells and cytokines in effecting fibrosis

A number of humoral and cellular immune abnormalities are present in patients with early scleroderma (systemic sclerosis). Most of these abnormalities reflect ongoing autoimmune reactions of the cellular and humoral types, resulting in a variety of autoantibodies to cellular and tissue constituents. Evidence exists for a defect(s) in immunoregulation favoring excessive helper T cell activity. The presence of circulating cytokines and shed interleukin-2 receptors suggest ongoing cellular immune reactions are occurring, generating cytokines and lymphokines that are capable of effecting the vascular and fibrotic lesions that are hallmarks of the disease. Future directions for research are suggested that would focus on determining if, and at what point, fibroblasts might function autonomously to generate excessive matrix components and on determining the nature of the original antigenic stimulus that starts the scleroderma process.

The role of the trimolecular complex (alpha beta TCR-MHC+peptide) in the pathogenesis of systemic sclerosis

Systemic sclerosis is an intricate disease process whose most unique and specific parameter indicative of autoimmunity is the presence of autoantibodies directed against certain nuclear antigens. The relationship between this particular humoral immune response and the genesis of a fibrotic tissue response in the skin as well as internal organs is not yet well understood. The prominence of CD4 T-cell infiltration during early phases of disease suggest that activation pathways may be initiated which subsequently result in phenotypic changes of a variety of mesenchymal cells, especially endothelial cells and fibroblasts. Taken in concert with the association of susceptibility with certain MHC class II molecules, the conventional presenters of exogenous peptide to T cells of the CD4 lineage, the notion of a central critical immune recognition event underlying the development of systemic sclerosis gains increasing likelihood. In addition to the still incompletely understood paracrine pathways between immune response and fibrosis, there is a nearly complete void of knowledge concerning what peptide is recognized by the T-cell and the structure of the alpha beta TCR involved in this recognition. Determining the role of the alpha beta TCR in the activation of the T-cell population in terms of identifying structural features which are critical participants in this process and the functional derangement leading to the characteristic pattern of self recognition will certainly enhance our understanding of the pathogenesis of systemic sclerosis.

Oncostatin M stimulates collagen and glycosaminoglycan production by cultured normal dermal fibroblasts: insensitivity of sclerodermal and keloidal fibroblasts

It is thought that normal fibrotic repair progresses to dermal fibrosis when fibroblasts are activated persistently by chronic exposure to cytokines such as transforming growth factor-beta. However, additional cytokines and mechanisms may play a role in the development of fibrosis. Thus, we examined a recently described T-lymphocyte/macrophage-derived cytokine, oncostatin M, for its effect on the production of collagen and glycosaminoglycan by microcultures of normal dermal, sclerodermal, and keloidal fibroblasts. Treatment with oncostatin M for 48 h induced dose-dependent (1-100 ng/ml) increases in the collagen and glycosaminoglycan production of nine normal fibroblast strains, which in the absence of fetal bovine serum at 100 ng/ml averaged 196% and 244%, respectively. Oncostatin M treatment increased both types I and III procollagens and their mRNA transcripts, as well as levels of hyaluronic acid, chondroitin-4/6 sulfates, and dermatan sulfate, but not fibronectin or general noncollagenous protein synthesis. In contrast, the collagen production of six of eight sclerodermal and keloidal fibroblast strains was essentially unresponsive to oncostatin M treatment, with 100 ng/ml inducing an average increase of only 34% for the eight fibrotic strains. Oncostatin M stimulation of fibrotic fibroblast glycosaminoglycan production was also hyporesponsive, as 100 ng/ml of oncostatin M induced an average increase of only 101%. These results indicate that oncostatin M could function as a stimulator of normal fibrotic repair via activation of fibroblast collagen and glycosaminoglycan synthesis and that the persistent activation of sclerodermal and keloidal fibroblasts is accompanied by a loss of sensitivity to oncostatin M stimulation.

Anti-topoisomerase I antibodies in silica-associated systemic sclerosis. A model for autoimmunity

OBJECTIVE

To determine the frequency and type of autoantibodies present in patients with systemic sclerosis (SSc) associated with an established environmental toxin.

METHODS

Clinical data and sera were available from 14 men with silica-associated SSc who had developed SSc after at least 2 years of exposure to silica at work. Controls included 27 men with silicosis without SSc. Autoantibodies were measured by immunodiffusion, immunoblotting, and functional inhibition of topoisomerase I (topo I).

RESULTS

Nine of the 14 patients with silica-associated SSc had anti-topo I antibodies. All anti-topo I antibodies in the patients with silica-associated SSc and in 14 anti-topo I-positive patients with idiopathic SSc were directed at an active site of topo I, or at least sterically inhibited its function. One patient with silica-associated SSc had anticentromere antibodies. Unexpectedly, 2 patients with silicosis who had no symptoms of a connective tissue disease had autoantibodies to Ro/SS-A and La/SS-B autoantigens.

CONCLUSION

Anti-topo I antibodies are the predominant autoantibodies present in silica-associated SSc. The generation of anti-topo I antibodies in genetically susceptible individuals may depend partly on the patient's sex and on the site of organ involvement, and may be triggered by silica particles acting as an immune adjuvant.

Increased endothelin-1 production in fibroblasts derived from patients with systemic sclerosis

OBJECTIVES

To determine whether fibroblasts from patients with systemic sclerosis (SSc) produce excessive amounts of endothelin-1 (ET-1), which is recognised as having vasoconstrictive properties and as having a potent mitogenic effect on fibroblasts.

METHODS

Dermal fibroblasts were removed from 11 patients with SSc and from five normal controls (NC). The assay of ET-1 protein was measured by an ELISA that used two anti-ET-1 antibodies. The gene expression of prepro ET-1 mRNA was evaluated by a reverse-transcriptase polymerase chain reaction (RT-PCR) method.

RESULTS

Levels of ET-1 protein were significantly higher in SSc fibroblast cultures than in those of normal fibroblasts (p < 0.01). The expression of prepro ET-1 mRNA was also higher in SSc fibroblasts than in normal fibroblasts. The addition of interleukin-1 beta (IL-1 beta) increased the production of ET-1 by fibroblasts.

CONCLUSION

The findings indicate that the overproduction of ET-1 is a novel abnormal function in SSc fibroblasts, and that ET-1 induced by fibroblasts may play a role in the fibrosis and Raynaud's phenomenon of SSc.

A role for CD4+ T cells in the pathogenesis of skin fibrosis in tight skin mice

The tight skin (Tsk/+) mouse represents a murine model of heritable fibrosis with some similarities to the skin fibrosis seen in human scleroderma. Tsk/+ animals display alterations in connective tissue in some internal organs. Skin fibrosis can be adoptively transferred to normal recipients with Tsk/+ bone marrow or spleen cells and older Tsk/+ animals develop autoantibodies against topoisomerase suggesting that some of the pathogenesis in the Tsk/+ mouse may be mediated by autoimmunity. To determine the role of T cell subsets in the pathogenesis of fibrotic disease, Tsk/+ mice were bred with CD4- and CD8-deficient (CD4-/- and CD8-/-) mice. Tsk/+ CD4-/- mice showed a marked reduction in skin fibrosis as well as decreased cellularity and only mild collagen disorganization as compared to Tsk/+ CD4+ CD8+ control mice yet did not differ from Tsk controls in the level of serum anti-topoisomerase activity. In contrast, Tsk/+ CD8-/- mice exhibited the same histology in the skin as Tsk/+ controls yet had significantly reduced levels of serum anti-topoisomerase activity. Lung pathology, i.e. emphysema, was unaffected by both the CD4 or CD8 mutations. These data show that only some of the pathological effects of the Tsk mutation are T cell dependent and that different T cell subsets affect different parameters in this multi-organ model of fibrotic disease.

Severe systemic sclerosis with anti-topoisomerase I antibodies is associated with an HLA-DRw11 allele

SSc is an autoimmune connective tissue disease in which strong HLA associations have not been described. Anti-topo I antibodies are recognized, in general, in SSc patients with diffuse cutaneous involvement, whereas anti-ACAs are found in individuals with limited cutaneous involvement. We studied 95 Caucasian SSc patients, 44 with anti-topo I antibodies and 51 with neither anti-topo I nor ACA, for HLA-DR associations by using DNA typing techniques. We analyzed 181 normal Caucasian individuals in the same fashion. A significant association was observed in the anti-topo-I-positive patients with DRw11 (p = 1.7 x 10(-6), RR 4.2). The distribution of DRw11 alleles in these patients was significantly different from that observed in controls and could be accounted for by an increase in the frequency of the DRB1*1104 allele (p = 1.2 x 10(-9), RR 9.5). The DRw11 alleles were also associated with SSc with more tendon friction rubs (p = 0.006), which is a marker of more severe disease. In addition, a strong association was observed with anti-topo I antibodies and a particular sequence (aa 71-77) of the DQB1 chain (p = 0.02, RR 2.2). HLA associations in the case of SSc patients with anti-topo I antibodies are complex and involve at least two genes: HLA-DRw11, which appears to play a major role in determining the severity of the disease, and a DQ sequence, which associates with the development of the anti-topo I antibodies.

Improved pulmonary function in systemic sclerosis after treatment with cyclophosphamide

OBJECTIVE

Pulmonary fibrosis is a common feature of systemic sclerosis (SSc) and a major cause of morbidity and mortality. Since alveolitis may be an essential step in the development of pulmonary fibrosis, we investigated the use of immunosuppressive drug therapy to improve pulmonary function in patients with SSc.

METHODS

Eighteen patients with progressive pulmonary dysfunction, diminished vital capacity (VC), and/or decreased static lung compliance (Cst) were treated with cyclophosphamide and corticosteroids for 1 year. Eight patients had diffuse cutaneous SSc and 10 had limited cutaneous SSc. The median disease duration was 2.5 years (range 0.5-17 years).

RESULTS

VC increased in 14 of 18 patients and the median VC rose from 74% to 80% of predicted. Cst improved in 8 of 12 patients and the median Cst increased from 59% to 66% of predicted. Pulmonary nonfibrotic opacities disappeared in 9 of 12 patients. The erythrocyte sedimentation rate (ESR) and serum concentrations of orosomucoid, C-reactive protein, and aminopropeptide type III collagen all improved. The patients were divided into 2 groups based on the presence or absence of elevations in acute-phase protein levels and ESR before therapy. Among the 12 patients with biochemical signs of inflammation, VC increased in 11, and Cst improved or was unchanged in 7 of the 8 who were tested. The median VC in this subgroup increased from 73% to 80% of predicted and the median Cst increased from 57% to 60% of predicted. In the group of 18 patients overall, the skin score decreased, while esophageal and renal function remained stable.

CONCLUSION

Cyclophosphamide may have a beneficial effect on pulmonary fibrosis in patients with SSc and elevated levels of acute-phase proteins. Controlled trials of cyclophosphamide in pulmonary SSc should be performed and should focus on such patients.

Anti-centromere antibodies (ACA) in systemic sclerosis patients and their relatives: a serological and HLA study

Autoantibody reactivity to centromere proteins CENP-A, CENP-B and CENP-C was examined in 58 patients with systemic sclerosis (SSc), 218 first degree relatives and 22 spouses. HLA class II typing for HLA-DRB1 and HLA-DQA1 was performed by restriction fragment length polymorphism (RFLP) analysis in 50 families, and HLA-DRB1, HLA-DQA1 and HLA-DQB1 typing was performed by olignucleotide typing in 44 families. Eleven probands and two relatives had ACA. The two relatives with ACA also had SSc. One relative was an identical twin sister of a proband with ACA and the other relative was a sister of a proband with ACA. All ACA-positive probands and relatives were female, and all recognized CENP-A, CENP-B and CENP-C. The presence of at least one HLA-DQB1 allele not coding for leucine at position 26 of the first domain appeared necessary, although not sufficient for the generation of ACA. Therefore within SSc families ACA is strongly associated with female gender and disease phenotype, and is at least in part genetically determined.

CD4+ and CD8+ subsets: naive and memory cells in the peripheral blood of patients with systemic sclerosis

Systemic Sclerosis (SSc; scleroderma) is associated with several immunological abnormalities, including altered proportion between lymphocyte subsets. Peripheral blood lymphocyte subsets from 25 patients with SSc were studied by two-colour flow cytometry using monoclonal antibodies against CD45RA and CD29 markers, which allow a dissection of CD4+ and CD8+ populations into 'naive' and 'memory' subsets. A decrease of the percentage of CD8+ (p < 0.05) and of CD8+CD29+ (p < 0.001) cells was observed compared to that in 20 age and sex-matched controls. These abnormalities were not significantly associated with the extension of cutaneous disease or other clinical features of SSc nor with treatment, pattern of autoantibodies or HLA phenotype.

Increased frequency of in vivo hprt gene-mutated T cells in the peripheral blood of patients with systemic sclerosis

OBJECTIVE

Activated T lymphocytes are involved in the pathogenesis of scleroderma (systemic sclerosis, SSc); such cells rapidly divide in vivo and are thus theoretically subject to random mutation more frequently than resting cells. To study whether SSc is associated with rapidly expanding T cell clones the frequency was determined of in vivo mutated T cells (MF) at the hypoxanthine guanine phosphoribosyl transferase (hprt) gene in the peripheral blood from patients with SSc. Specific clinical or serological associations were also investigated.

METHODS

Peripheral blood lymphocytes from 16 healthy individuals and 20 patients with SSc were cultured using an hprt clonal assay; mutated and wild T cell clones were established to assess individual values of T cell MF. T cell clones were further expanded in vitro and their phenotype was determined by standard immunofluorescence technique. Enzyme-linked immunosorbent assays were used for simultaneous measurements of plasma levels of soluble Interleukin-2 receptors (s-IL-2R) and Intercellular adhesion molecule-1 (s-ICAM-1).

RESULT

Mean (SD) value of T cell MF in patients with SSc was 2.5-fold higher than the normal mean (SD) value [10.6 (6.6) x 10(-6) v [4.4 (2.8) x 10(-6), p = 0.0007]. Eleven of 20 patients with SSc (55%) had T cell MF values greater than two SD above the normal mean value. The majority (84%) of mutated T cells had a helper/inducer, memory phenotype while 12% were cytotoxic/suppressor T cells. There was no association between T cell MF and the extent of skin involvement or the duration of Raynaud's phenomenon. High individual T cell MF values were not related to a possible concurrent immune overactivity as assessed by plasma levels of s-IL-2R and s-ICAM-1. Patients with long standing skin disease, however, had almost double T cell MF values than patients with early skin disease [(13.6 (7.4)) x 10(-6) v (7.5 (4.3)) x 10(-6), p = 0.03], suggesting that increased T cell MF in SSc may reflect an ongoing process of chronic in vivo T cell proliferation and/or prolonged survival.

CONCLUSION

Increased in vivo T cell mutation in patients with SSc suggests that excessive division and/or survival of T cell clones contribute to the pathology in SSc; this approach can be used in further investigations to identify the stimulus that is triggering T cell activation in this disease.

Immunocytochemical localization and serologic detection of transforming growth factor beta 1. Association with type I procollagen and inflammatory cell markers in diffuse and limited systemic sclerosis, morphea, and Raynaud's phenomenon

OBJECTIVE

To determine the presence of transforming growth factor beta 1 (TGF beta 1) and inflammatory cell markers (HLA-DR and Factor XIIIa) and to compare these with the presence of type I procollagen, in clinically uninvolved and involved skin from patients with different subsets of systemic sclerosis (SSc), and to analyze circulating levels of TGF beta 1 in SSc patients.

METHODS

TGF beta 1, HLA-DR, Factor XIIIa, and type I procollagen were detected in skin biopsy sections using a biotin-streptavidin-peroxidase system. Levels of circulating TGF beta 1 were measured using a capture enzyme-linked immunosorbent assay technique.

RESULTS

Patients with active diffuse cutaneous SSc (dcSSc) showed minimal TGF beta 1 but significant type I procollagen staining in involved skin, while the clinically uninvolved skin of these patients showed moderate extracellular and intra-epidermal TGF beta 1 immunoreactivity. Patients with limited cutaneous SSc (lcSSc) showed elevated TGF beta 1 staining in both involved and uninvolved skin, as well as procollagen staining. Significant TGF beta 1 reactivity, HLA-DR and Factor XIIIa immunoreactivity, numerous inflammatory cells, and procollagen staining were seen in specimens from patients with morphea. Sequential biopsies suggested the presence of cytokine activity at the earliest stages of disease, which was not maintained with progression of sclerosis. Among the disease groups studied, elevated levels of circulating TGF beta 1 were seen only in patients with morphea.

CONCLUSION

The pattern of TGF beta 1 staining in dermal sections from patients with dcSSc, lcSSc, and morphea suggests that this cytokine is important in the pathogenesis of scleroderma. Furthermore, the presence of TGF beta 1 prior to the onset of fibrosis indicates an early involvement of this growth factor, possibly in the inflammatory stage of the disease.

Early phenotypic activation of circulating helper memory T cells in scleroderma: correlation with disease activity

OBJECTIVES

The differential expression of several accessory/activation molecules (CD26, CD29, CD45RA, CD25, MLR4, HLA-DR) on peripheral blood CD4+ and CD8+ T lymphocytes in patients with scleroderma was compared with that in controls and patients with other connective systemic diseases to look for evidence of the involvement of T cells in the disease process of scleroderma.

METHODS

The two colour expression of surface molecules by circulating T cells was analysed with a panel of monoclonal antibodies and flow cytometry in 17 patients with scleroderma, 10 patients with systemic lupus erythematosus, and five patients with rheumatoid arthritis, and the results compared with those for 10 normal controls. The two colour T CD4+ phenotype was further compared between patients with active and quiescent disease in these patients with scleroderma. The coexpression of surface molecules by CD4+ T cells was also analysed by three colour flow cytometry in eight patients with scleroderma.

RESULTS

Patients with scleroderma showed increased CD4+CD26+ and CD4+CD25+ percentages and absolute numbers and decreased CD8+CD29+ percentages compared with controls. Moreover, a significant correlation between the higher CD4+CD26+ T cell percentage and absolute cell numbers with disease activity was observed. Most of the CD4+ peripheral blood T cells from patients with scleroderma showed the CD26+CD45RA- phenotype by three colour flow cytometry analysis.

CONCLUSIONS

The distinctive pattern of early helper memory T cell activation in these patients with rapidly evolving scleroderma supports the role of a T cell mediated mechanism in the progression of scleroderma.

A radical proposal for the pathogenesis of scleroderma

Because the etiology and pathogenesis of scleroderma are largely speculative, effective therapy is not available for this debilitating condition and its variants. This article reviews current concepts in the etiology and pathogenesis of scleroderma and suggests a unifying hypothesis involving the generation of free radicals. The role of specific free radical scavengers should be tested both in vitro and in clinical trials of patients with scleroderma.

Use of anti-thymocyte globulin in the management of refractory systemic autoimmune diseases

The purpose of our pilot study was to evaluate the short-and long-term efficacy of T-lymphocyte depletion in the management of patients with refractory, systemic autoimmune diseases. Nine patients with severe, therapy-resistant autoimmune diseases were subjected to T-cell depletion procedure using polyclonal anti-T-cell antibodies combined with peroral administration of azathioprine and/or cyclosporine. The proband group consisted of 4 patients with systemic lupus erythematosus, 3 with progressive systemic sclerosis, and 2 with rheumatoid arthritis. Administration of polyclonal anti-T-cell antibodies was performed at a single occasion via a central venous catheter during 9-10 days. Immunological analyses of T-cell phenotypes and function and assessment of organ function (kidneys, lungs, bone-marrow) has been performed prospectively in all the patients studied. This treatment resulted in prompt and long-lasting (mean follow-up time: 25.6 months) improvement of autoimmune hemolytic anemia, glomerulonephritis, lung fibrosis, skin and joint involvements in the majority of cases. Adverse effects of this treatment included two episodes of infection (E. coli and Cytomegalovirus) and three cases of serum sickness, and were all easily managed. We suggest that this treatment modality adopted from transplant rejection therapy could be employed in cases of severe autoimmune diseases unresponsive to regular immunosuppressive treatment.

Cultured fibroblasts in avian scleroderma, an autoimmune fibrotic disease, display an activated phenotype

University of California, Davis, line 200 and 206 chickens spontaneously develop an autoimmune syndrome that has many features analogous to human scleroderma, including dermal fibrosis, antinuclear antibodies and antibodies to type II collagen. These birds also have thymic subcapsular epithelial defects and an abnormality in T cell calcium influx and proliferation in response to both T cell receptor-dependent and -independent activators. To determine whether fibroblast activation is a contributing factor to development of skin fibrosis in line 200/206 chickens, as it is in human scleroderma, we studied the collagen, non-collagenous protein and glycosaminoglycan (GAG) production of 34 separate fibroblast lines derived from the normal and fibrotic skin of line 200 and 206 chickens and from the skin of control chicken lines 058 and 254. The mean +/- SEM 24-h incorporation of 3H-proline or 3H-glucosamine into extracellular collagen, non-collagenous protein or GAG by first passage fibroblast lines derived from the fibrotic skin of diseased birds was 1,526 +/- 136, 859 +/- 82 and 25.7 +/- 1.3 dpm/10(3) cells, respectively, while fibroblast lines derived from the skin of control birds produced only 341 +/- 36, 343 +/- 42 and 15.2 +/- 1.4 dpm/10(3) cells. Similar differences in results were recorded for cell-associated production, and when collagen and non-collagenous protein production were assessed using non-radioactive electrophoretic methods. The activated phenotype of the fibroblast lines derived from the fibrotic skin of diseased birds persisted through 10 cell doublings in tissue culture. However, the ratio of type I:III collagen and the profile of GAG types produced were similar in all fibroblast lines studied. These results suggest that fibroblast activation is responsible for the skin fibrosis observed in this avian model of scleroderma.

Human fibroblasts synthesize elevated levels of extracellular matrix proteins in response to interleukin 4

Interleukin 4 (also known as "B cell stimulatory factor-1"), a cytokine product of T lymphocytes and mast cells, stimulates synthesis of the extracellular matrix proteins, types I and III collagen and fibronectin, by human dermal fibroblasts in vitro. Stimulation of collagen by human recombinant (hr)IL-4 was also demonstrated in several fibroblastic synovial cell lines obtained from patients with rheumatoid arthritis and osteoarthritis. The stimulatory effect of hrIL-4 on fibroblast collagen synthesis was specifically neutralized by rabbit anti-hrIL-4 Ig. IL-4 specifically increased the steady-state levels of types I and III procollagen and fibronectin mRNAs, with no effect on cytoplasmic beta-actin mRNA. Quantitative analysis of the levels of Pro alpha 1(I) collagen transcripts in IL-4-treated fibroblast cultures was also corroborated by antisense RNA-mRNA hybridization and RNAse resistant hybrids which showed that IL-4-treated fibroblasts expressed higher levels of Pro alpha 1(I) collagen transcripts. Nuclear run-off transcription experiments indicated that IL-4 stimulated the rates of mRNA biogenesis. Based on these observations we conclude that IL-4 exerts its effect on collagen and fibronectin synthesis at the pretranslational level, resulting in synthesis of these extracellular matrix proteins. These and other data suggest that IL-4 may be a "fibrogenic cytokine" that could be important in promoting biogenesis of extracellular matrix proteins in normal wound healing and in pathological fibrosis in which mast cells and T lymphocytes play a central role.

Treatment of systemic sclerosis with recombinant interferon-gamma. A phase I/II clinical trial

OBJECTIVE

A phase I/II trial to examine the safety and efficacy of interferon-gamma (IFN gamma) therapy for patients with systemic sclerosis (SSc).

METHODS

An 18-week open-label study was performed. Eighteen patients with rapidly progressive SSc were enrolled, 14 of whom completed at least 16 weeks of the study. These 14 patients had a mean age of 40 years and had been diagnosed as having SSc an average of 10.1 months prior to study entry. Recombinant IFN gamma was injected intramuscularly 3 times weekly for 18 weeks. Six patients received a 0.1 mg/m2 dose, while 8 patients received a 0.5 mg/m2 dose. Patients who completed the 18-week trial were offered maintenance therapy at a dose of up to 0.5 mg/m2. The effects of IFN gamma on skin involvement were assessed by 2 methods: 1) evaluation of skin thickness, by scoring 15 zones according to a 0 (normal skin) to 3 (hidebound skin) scale; and 2) determination of the total body surface area involved, by using 2-dimensional body diagrams to indicate areas affected, and then having a second, "blinded," assessor calculate the area score with a planimeter.

RESULTS

The mean skin thickness score decreased from a baseline of 25.9 to 19.1 (P < 0.03), and the mean area scores declined from 33.1 to 19.6 (P < 0.02) after 18 weeks of IFN gamma treatment. Ten patients had a > 25% decrease in area score. Five patients had a > or = 70% decrease in area score, and 3 of them have not experienced disease recurrence for 6 to 17 months after discontinuation of IFN gamma. Five patients withdrew before the study ended. Three of these patients developed renal crisis, which may reflect the severity of the SSc in the study group, although an adverse effect of IFN gamma in SSc cannot be excluded.

CONCLUSION

IFN gamma was associated with a beneficial effect on the skin involvement in most of this series of patients with rapidly progressive SSc. A placebo-controlled study will be necessary to confirm these results.

Increased expression of tenascin in the dermis in scleroderma

The expression of tenascin, a recently discovered extracellular matrix protein, was studied by immunohistochemical techniques in scleroderma skin and compared with its distribution in normal skin. In progressive systemic sclerosis, a marked increase in tenascin content was observed in the superficial reticular dermis. In localized scleroderma, the deposition of tenascin was increased both in the superficial and deep dermis of involved skin, whereas in clinically uninvolved skin the distribution of tenascin was the same as in normal control skin, i.e. the papillary dermis and peri-appendiceal zone. The distribution of tenascin did not strictly parallel that of fibronectin. These findings and the current knowledge of tenascin biology suggest that the overproduction of tenascin in scleroderma dermis could be secondary to stimulation of fibroblasts by immune cell-derived cytokines, or could be due to abnormal fibroblasts, or a subpopulation of fibroblasts, producing high levels of this extracellular matrix protein.

Serum adenosine deaminase activity in systemic sclerosis (scleroderma) and related disorders

BACKGROUND

Adenosine deaminase (ADA) activity in serum is mainly derived from T lymphocytes.

OBJECTIVE

Our purpose was to clarify the significance of ADA activity in systemic sclerosis (PSS) and related disorders.

METHODS

ADA activity was determined with an enzymatic method in 34 patients with PSS, 4 with mixed connective tissue disease (MCTD), 6 with dermatomyositis (DM), 11 with localized scleroderma (LS), and 13 with other collagen diseases.

RESULTS

Serum ADA activity was elevated over the mean (+2 standard deviations) of the control in 85% of the patients with PSS, all with MCTD, 83% of those with DM, and 82% of those with LS. The mean values in 10 PSS patients with anti-topoisomerase I antibodies, 14 patients with anti-RNP antibodies, 12 patients with anticentromere antibodies (ACAs), and 5 patients without antinuclear antibodies (ANAs) were 26.1, 24.9, 22.6, and 16.8 IU/L, respectively. In most cases, except for ACA-positive patients, serum ADA activity changed almost in parallel with ANA titers.

CONCLUSION

These results support the notion that T cells are involved in the pathogenesis of PSS and related disorders.

Adhesion of peripheral blood mononuclear cells to vascular endothelium in patients with systemic sclerosis (scleroderma)

OBJECTIVE

Perivascular infiltrates in skin, subcutaneous tissue, and internal organs are a characteristic feature of early systemic sclerosis (SSc). We studied the first step of migration of peripheral blood mononuclear cells (PBMC) through the vessel wall to the extravascular space, i.e., adhesion of PBMC to endothelial cells (EC), in patients with various forms of SSc (limited scleroderma, diffuse scleroderma, and the transitional form).

METHODS

Radioisotope-labeled patient PBMC were coincubated with umbilical cord EC in vitro, and the percentage adhesion was measured.

RESULTS

Adhesion of PBMC to EC was markedly decreased, while adhesion of isolated active rosette-forming cells (ARFC) was significantly increased, in SSc patients compared with healthy controls. Decreased adhesion of PBMC to EC was found to correlate with a diminished percentage of ARFC in the peripheral blood. Preincubation of PBMC from healthy donors with interleukin-2 (IL-2) enhanced their adhesion to EC, while preincubation of PBMC from SSc patients with this cytokine resulted in a decrease in adhesion in 10 of 14 individuals. IL-1, interferon-gamma, and transforming growth factor beta had no significant effect on adhesion of SSc patient PBMC to EC. Differences in adhesion of PBMC to EC among the SSc subgroups were not significant.

CONCLUSION

Our findings suggest that in SSc, activation of subpopulations of PBMC leads to their enhanced adhesion to vascular endothelium in vivo and to migration of these cells to the extravascular space, resulting in the elimination from the peripheral blood of those PBMC with high ability to adhere to EC.

Imbalance of CD4+ lymphocyte subsets in patients with mixed connective tissue disease

CD4+ (helper/inducer) T lymphocyte subsets were studied in the peripheral blood from patients with mixed connective tissue disease (MCTD) by double-labelling immunofluorescence. The proportion of CD4+CD45RA+ cells was higher (P less than 0.01) when compared with controls, whereas CD4+CD29+ cells were markedly diminished (P less than 0.001). CD4+CD29+ cells were lower than in patients with progressive systemic sclerosis who were studied in parallel. Upon stimulation with phytohaemagglutinin, CD4+ cells from MCTD patients showed a strong reactivity to acquire the CD29+ phenotype. Expression of high levels of CD29 and other adhesion molecules might lead to facilitated localization of CD4+ cells to inflamed tissue. It is suggested that an increased responsiveness of CD4+ cells to activation signals in vivo and accumulation of CD4+CD29+ cells at tissue sites could result in depletion of this cell subset in the peripheral blood of patients with MCTD.

Increased interleukin 1 receptor, type I, at messenger RNA and protein level in skin fibroblasts from patients with systemic sclerosis

Summary. To elucidate the mechanisms of the fibrosis in systemic sclerosis (SSc) through the action of a cytokine, interleukin 1 (IL-1), we studied the specific biologic and biochemical features of interleukin 1 receptor (IL-1R) as expressed on the surfaces of fibroblast cells in cultures from 3 SSc patients and 3 normal donors. 125I-IL-1 beta binding assays revealed a high density of IL-1R on the cell surfaces of SSc fibroblasts as compared to those of normal subjects. We also found an enhanced expression of IL-1R messenger RNA (mRNA) in SSc fibroblasts, using Northern blot or slot blot analysis. These findings indicate that the expression of IL-1R on SSc fibroblasts were spontaneously induced at the transcriptional level. It is suggested that SSc fibroblasts are more sensitive to IL-1, and that the signal transduction of IL-1 through IL-1R may be eventually involved in the fibrosis of SSc.

Selective upregulation of platelet-derived growth factor alpha receptors by transforming growth factor beta in scleroderma fibroblasts

Transforming growth factor beta (TGF-beta), a multifunctional cytokine, is an indirect mitogen for human fibroblasts through platelet-derived growth factor (PDGF), particularly the A ligand-alpha receptor arm of that system. TGF-beta effects on PDGF alpha receptor expression were studied in vitro using ligand binding techniques in three human dermal fibroblast strains: newborn foreskin, adult skin, and scleroderma (systemic sclerosis, SSc). Each cell strain responded differently to TGF-beta. In newborn foreskin fibroblasts, PDGF alpha receptor number decreased in a dose-dependent manner after exposure to low concentrations of TGF-beta (0.1-1 ng/ml). Responses of normal skin fibroblasts were varied, and mean net receptor number was unchanged. Increases in PDGF alpha receptor number by TGF-beta occurred consistently with SSc fibroblasts and low concentrations of TGF-beta (0.1-1 ng/ml) were particularly stimulatory. Increased surface expression of alpha receptor subunit by TGF-beta in SSc fibroblasts correlated with increased new PDGF alpha receptor synthesis as demonstrated by radioimmunoprecipitation analysis of metabolically labeled cells and with increased steady-state levels of corresponding mRNAs. In normal adult skin fibroblasts, TGF-beta had no effect on either synthesis or mRNA expression of alpha receptor subunits. Proliferative responses to PDGF-AA after pretreatment with TGF-beta correlated positively with effects of TGF-beta on expression of alpha receptor subunit. Decreased mitogenic responses to PDGF-AA were observed in foreskin fibroblasts, small changes in responses in adult fibroblasts, and significant increases in SSc fibroblasts. Thus, costimulation with PDGF-AA and TGF-beta selectively enhanced proliferation of fibroblasts with the SSc phenotype. Immunohistochemical examination of SSc and control skin biopsies revealed the presence of PDGF-AA in SSc skin. Data obtained by ligand binding, immunoprecipitation, mRNA, and mitogenic techniques are consistent with the hypothesis that activation of the PDGF-AA ligand/alpha receptor pathway is a characteristic of the SSc fibroblast and may contribute to the expansion of fibroblasts in SSc.

Elevated expression of beta 1 and beta 2 integrins, intercellular adhesion molecule 1, and endothelial leukocyte adhesion molecule 1 in the skin of patients with systemic sclerosis of recent onset

OBJECTIVE

To investigate the possible role of integrins and cell adhesion molecules in the pathogenesis of the mononuclear cell infiltration and fibrosis of skin that occurs in systemic sclerosis (SSc).

METHODS

The presence and topographic distribution of beta 1, beta 2, and beta 4 integrins, as well as of endothelial leukocyte adhesion molecule 1 (ELAM-1) and intercellular adhesion molecule 1 (ICAM-1), was examined immunohistochemically in affected skin from 8 patients with rapidly progressive SSc of recent onset. The expression of the beta 1 integrin gene was also investigated by in situ hybridization with a human sequence-specific complementary DNA.

RESULTS

The presence of beta 1 integrin epitopes and the corresponding messenger RNA within inflammatory cells surrounding small vessels was demonstrated in SSc skin but not in normal skin. Lymphocytes positive for beta 2 integrin were also found only in SSc skin, and they appeared in close proximity to small blood vessels and collagen bundles. Immunostaining for beta 4 integrin epitopes revealed no differences between normal and SSc skin. ELAM-1 and ICAM-1 monoclonal antibodies, which identify epitopes indicative of endothelial cell activation, stained endothelial cells in SSc skin but not normal skin.

CONCLUSION

These observations suggest that the complex interactions of beta 1 and beta 2 integrins, as well as ELAM-1 and ICAM-1, may be intimately involved in the pathogenesis of SSc, perhaps by mediating the homing and targeting of pathogenetic lymphocytes to the affected tissues.

Sequential dermal microvascular and perivascular changes in the development of scleroderma

It has been previously proposed that there is a primary microvascular abnormality in patients with systemic sclerosis. In this study using conventional light and electron microscopy, immunohistochemistry, and labelled adenosine uptake techniques, changes in the dermal microvasculature have been related to the various clinical stages of skin disease in systemic sclerosis. The earliest pathological changes are seen in clinically normal skin. They constitute changes in endothelial cell function and their consequences. Perivascular oedema is an early feature. With progression in the clinical disease, there is, at first, an inflammatory cell infiltrate into the dermis, particularly the papillary and mid-dermis, and platelet aggregation within vessels. Further clinical progression is associated with increasing dermal fibrosis, loss of adnexae, and vascular effacement. It is postulated that the recruitment of different types of mononuclear cells into the dermis is causally linked with the preceding endothelial cell dysfunction and the subsequent induction of fibroblast proliferation and collagen synthesis.

Enhanced expression of high-affinity interleukin-2 receptors in scleroderma: possible role for IL-6

Scleroderma (systemic sclerosis) is characterized by tissue fibrosis, a distinctive vascular and microvascular disorder, and a perivascular mononuclear cell infiltration of involved organs. The pathogenesis of scleroderma is not known; however, there is evidence for a cell-mediated immune mechanism in the disease. Enhanced IL-2 production has been documented both in vivo and in vitro. In this study, the effect of IL-2 on lymphocyte proliferation in vitro was examined. An enhanced proliferative response to IL-2 was seen in scleroderma lymphocytes over that in matched control lymphocytes. Since high-affinity IL-2 receptors (HIL-2-R) mediate the growth-promoting activity of IL-2, we examined HIL-2-R expression on lymphocytes from 13 scleroderma and 11 matched control subjects by a radioiodinated IL-2 binding assay. Significantly higher numbers of HIL-2-R were noted in scleroderma cells (3054 +/- 618 in scleroderma vs 1721 +/- 181 in control cells, mean +/- SD; P less than 0.001). The addition of IL-6 to control cell cultures 24 hr prior to binding determination led to changes in IL-2 binding that were identical to scleroderma cell binding characteristics, while the addition of neutralizing IL-6 antibody to scleroderma cells led to a reduction in HIL-2-R expression. Other cytokines (IL-1, IL-3, IL-4, IL-5, TNF, LT, IFN-gamma, and TGF-beta) had no effect on IL-2 binding, suggesting that IL-6 may mediate the enhanced expression of HIL-2-R. This conclusion was further supported by the finding that scleroderma lymphocytes released in vitro 10- to 20-fold higher concentrations of IL-6 than control cells. The data demonstrate an amplification of IL-2 binding in scleroderma and suggest IL-6 as the mediator of this phenomenon.

Expression of intercellular adhesion molecule-1 (ICAM-1) in the skin of patients with systemic scleroderma

The expression and tissue distribution of intercellular adhesion molecule-1 (ICAM-1) in skin biopsies from 12 patients with systemic (SSc) and localized (LS) scleroderma was studied and compared to the biopsies from patients with lupus erythematosus (LE) and normal individuals. In normal human skin ICAM-1 expression was restricted to the vascular endothelium, infiltrating mononuclear cells (MNC), and to few individual keratinocytes. In the inflammatory stage of SSc, however, the expression of ICAM-1 was dramatically increased at the site of MNC infiltrates and could also be detected on fibroblast-like cells lying well apart from these infiltrates in the deep dermis. In contrast, in LS ICAM-1 was expressed mainly at the sites of MNC infiltrates. In LE ICAM-1 expression was confined to the keratinocytes, endothelial cells, and mononuclear cells in the upper parts of the dermis. Analysis of serial tissue sections from patients with SSc demonstrated also colocalization of staining of ICAM-1 around blood vessels with LFA-1-positive lymphocytes. Increased expression of ICAM-1 in the dermis of patients with SSc may represent an important mechanism by which MNC become localized and retained at a site of connective tissue inflammation, leading to the activation of fibroblasts.

Phenotypic analysis of skin infiltrates in comparison with peripheral blood lymphocytes, spleen cells and thymocytes in early avian scleroderma

University of California at Davis line 200 (UCD-200) chickens develop a hereditary connective tissue disease characterized by severe lymphocytic infiltration, vascular occlusion and fibrosis of skin and internal organs. To identify cellular immunological abnormalities in the acute inflammatory disease stage of this animal model for progressive systemic sclerosis (PSS) we investigated the phenotypic characteristics and function of peripheral blood lymphocytes (PBL), spleen cells and thymocytes in comparison with skin infiltrating cells. Immunofluorescence and immunohistochemical analysis using monoclonal antibodies revealed the overwhelming majority of skin infiltrating mononuclear cells in the deeper dermis and subcutaneous tissue to be T cell receptor alpha/beta (TcR2)+/CD3+/CD4+/class II+ cells, a small portion (5-10%) of which were interleukin 2 (IL-2) receptor positive. In contrast, the inflammatory infiltrate in perivascular areas of the papillary dermis was constituted of mainly TcR gamma/delta (TcR1)+/class II- lymphocytes. Only few B cells (T/B cell ratio greater than 5) were detected. These diseased chickens showed significantly reduced percentages and numbers of circulating peripheral T cells exhibiting TcR1, TcR2, CD3, CD4 or IL-2-receptor, probably owing to an increased influx into lymphoid organs and affected tissues. In contrast to healthy chickens, the thymi of UCD-200 animals revealed fewer cells expressing TcR1, TcR2 and class II antigen, suggesting an altered intrathymic maturation of the T cell lineage. Functional in vitro studies showed a significantly decreased T cell mitogen-induced proliferation rate associated with a decreased capacity to produce IL-2 and to express IL-2 receptors. In contrast to the deficient in vitro IL-2 production the sera of UCD-200 chickens contained significant levels of IL-2 bioactivity. The alteration of T lymphocyte physiology in UCD-200 chickens adds, at least in part, to the parallels between this animal model and its human counterpart. These data confirm our hypothesis that the PSS-like disease of UCD-200 chickens includes a numeric and/or functional alteration of peripheral T cell subsets, especially of TcR1 positive cells, in contrast to the pronounced accumulation in the afflicted tissues.

Abnormalities of T lymphocyte subsets in systemic sclerosis demonstrated with anti-CD45RA and anti-CD29 monoclonal antibodies

T cell subpopulations were assessed by two colour flow cytometry with phycoerythrin conjugated anti-CD45RA and anti-CD29 and fluorescein conjugated anti-CD4 and anti-CD8 monoclonal antibodies, on peripheral blood lymphocytes from 12 patients with systemic sclerosis and from nine control subjects. The percentage of CD4+CD29+ cells was significantly higher in patients with systemic sclerosis than in controls (mean (SEM) 68.8 (3.1) v 47.9 (4.1) respectively). CD4+CD45RA+ cells were not significantly different in patients and controls. CD8+CD29+ and CD8+CD45RA+ subpopulations were significantly higher in patients with systemic sclerosis than in controls (83.0 (3.2) v 58.7 (6.8) and 80.2 (3.0) v 66.9 (3.2) respectively). The increase in the percentage of CD29+ cells suggests an activation of memory cells in patients with systemic sclerosis, which may play an important part in the pathogenesis of the disease.

Increased interleukin-2 production in response to human type I collagen stimulation in patients with systemic sclerosis

Peripheral blood mononuclear cells (PBMC) from patients with systemic sclerosis (SSc) produced increased amounts of interleukin-2 (IL-2), in a dose-dependent manner, in response to stimulation with human type I collagen, whereas PBMC from normal subjects did not. At a dose of 50 micrograms human type I collagen/10(6) PBMC, PBMC from SSc patients (n = 17) produced 8 times as much IL-2 as did PBMC from 16 normal subjects (P less than 0.005) and 3 times as much as did PBMC from a group of 13 rheumatoid arthritis patients (P less than 0.05). In contrast, IL-2 production by PBMC after nonspecific stimulation with the mitogen, phytohemagglutinin, did not differ among the SSc, rheumatoid arthritis, and normal control groups. Cell depletion experiments indicated that the IL-2-producing cells in SSc patients are CD4+. Thus, SSc patients have CD4 cells that are specifically sensitized to human type I collagen and can produce increased levels of IL-2. Measurement of IL-2 production stimulated by human type I collagen may be useful in evaluating disease activity, and further investigation of this process may contribute to the delineation of the pathogenesis of SSc.

Eosinophil activation in systemic sclerosis

Circulating levels of eosinophil cationic protein (ECP) were increased 4-fold in patients with systemic sclerosis (SSc) compared with those in healthy control subjects. There was no correlation between the ECP concentrations and laboratory indices of inflammatory activity or visceral involvement. Mean ECP levels were higher in patients with a history of occupational exposure to silica, even though patients who had no such history also had ECP levels higher than normal. The patients had increased bronchoalveolar levels of ECP, which correlated with impaired lung functioning. Skin infiltration with activated eosinophils and extracellular deposits of ECP were present in skin biopsy samples from the SSc patients. We conclude that eosinophil activation is part of the inflammatory process in SSc.