Derangement of apoptosis-related lymphocyte homeostasis in systemic sclerosis

Association Between DNA Damage Response, Fibrosis and Type I Interferon Signature in Systemic Sclerosis

Increased endogenous DNA damage and type I interferon pathway activation have been implicated in systemic sclerosis (SSc) pathogenesis. Because experimental evidence suggests an interplay between DNA damage response/repair (DDR/R) and immune response, we hypothesized that deregulated DDR/R is associated with a type I interferon signature and/or fibrosis extent in SSc. DNA damage levels, oxidative stress, induction of abasic sites and the efficiency of DNA double-strand break repair (DSB/R) and nucleotide excision repair (NER) were assessed in peripheral blood mononuclear cells (PBMCs) derived from 37 SSc patients and 55 healthy controls; expression of DDR/R-associated genes and type I interferon-induced genes was also quantified. Endogenous DNA damage was significantly higher in untreated diffuse or limited SSc (Olive tail moment; 14.7 ± 7.0 and 9.5 ± 4.1, respectively) as well as in patients under cytotoxic treatment (15.0 ± 5.4) but not in very early onset SSc (5.6 ± 1.2) compared with controls (4.9 ± 2.6). Moreover, patients with pulmonary fibrosis had significantly higher DNA damage levels than those without (12.6 ± 5.8 vs. 8.8 ± 4.8, respectively). SSc patients displayed increased oxidative stress and abasic sites, defective DSB/R but not NER capacity, downregulation of genes involved in DSB/R (MRE11A, PRKDC) and base excision repair (PARP1, XRCC1), and upregulation of apoptosis-related genes (BAX, BBC3). Individual levels of DNA damage in SSc PBMCs correlated significantly with the corresponding mRNA expression of type I interferon-induced genes (IFIT1, IFI44 and MX1, r=0.419-0.490) as well as with corresponding skin involvement extent by modified Rodnan skin score (r=0.481). In conclusion, defective DDR/R may exert a fuel-on-fire effect on type I interferon pathway activation and contribute to tissue fibrosis in SSc.

Regulatory T Cells in Systemic Sclerosis: a Comprehensive Review

Systemic sclerosis (SSc) is a chronic inflammatory disease with complex pathogenesis, based on the sophisticated interplay of injury to the vascular endothelium, exaggerated tissue regeneration and fibrosis, and extensive immune abnormalities. The role of regulatory T cells (Tregs) in the development of SSc has started being studied during the last decade with new aspects being disclosed continuously, in parallel with the better understanding of Tregs physiology. There is a general agreement in the medical literature regarding the decreased functional capacity of circulating Tregs in SSc. Some patients, particularly those with active disease, may have increased numbers of circulating Tregs, representing the inhibitory response of the immune system to its inappropriate activation or occurring as a compensatory move for Tregs' decreased suppressive ability. Decreased pool of circulating Tregs can be seen in other SSc patients, with even lower Treg percentages seen in patients with long-standing disease. Skin-resident Tregs are depleted in advanced SSc but can be active and have a role in earlier disease stages. In addition to diminished suppressive ability, Tregs can contribute to SSc evolution by their microenvironment-dependent transformation to pathogenic effector T cells of Th17 or Th2 lineages with respective pro-inflammatory or pro-fibrotic activity. The current data on the effects of existing treatment modalities, including autologous stem cell transplantation, on Tregs function in SSc, is controversial, not being sufficiently elaborated.

T and NK Cell Phenotypic Abnormalities in Systemic Sclerosis: a Cohort Study and a Comprehensive Literature Review

Scleroderma (SSc) is a rare and heterogeneous immune-mediated disease involving the connective tissue and microvasculature whose pathogenesis remains unclear. Data concerning T and natural killer (NK) cell abnormalities and cytokine levels in the peripheral blood (PB) from patients with SSc are scarce, and the results are contradictory. The present study aimed to analyze the changes of T lymphocytes, NK cells, and T helper (Th)-related cytokines in the PB of patients with SSc in comparison to healthy individuals and its relation to disease subtype and stage, organ involvement, and nailfold capillaroscopic changes. A non-random convenience sample of 57 scleroderma patients was utilized. Fifty-five out of the 57 patients studied were women (97 %); 10 patients presented pre-scleroderma (pre-SSc) and 47 SSc: 34 limited cutaneous SSc (lcSSc) and 13 diffuse cutaneous SSc (dcSSc). Patients with SSc were classified in early (n = 7), intermediate (n = 10), and late (n = 30) disease. Blood samples were analyzed by flow cytometry for total T cells, CD4+ and CD8+ T cell subsets, total NK cells, and CD56+low and CD56+high NK cell subsets. T cells were further analyzed for the expression of the CD56 adhesion molecule and activation-related markers (HLA-DR, CD45RO). In addition, the serum levels of Th1-, Th2-, and Th17-related cytokines were measured by flow cytometry. Twenty-five healthy individuals recruited from the blood bank were used as controls. Patients had lower numbers of total lymphocytes and T cells comparing to healthy controls. Both CD4+ and CD8+ T cells were decreased, but differences were statistically significant only for CD8+ and CD8+ CD45RO+ T cells. These alterations were seen in patients with SSc but not in patients with pre-SSc, and, in general, they were more pronounced in patients with dcSSc than in patients with lcSSc, in patients with vascular involvement than in those without, as well as in patients having active and late nailfold capillaroscopic patterns. CD56+ T cells were also decreased in SSc patients, especially in those with active/late capillaroscopic patterns or with severe lung disease. Diminished numbers of circulating NK cells were also observed in patients with lcSSc and in those with early disease. No statistically significant changes were found in serum cytokine levels, as compared with controls. Patients with SSc had major alterations in circulating CD8+ and CD56+ T cells, as well as in NK cells, suggesting that these cells may play a relevant role in SSc pathogenesis, probably operating at different phases and/or at different organs. In addition, the serum levels of Th1, Th2, and Th17 cytokines did not provide useful information for evaluating T cell polarization in SSc.

Relationship between redox status and cell fate in immunity and autoimmunity

SIGNIFICANCE

The signaling function of redox molecules is essential for an efficient and proper execution of a large number of cellular processes, contributing to the maintenance of cell homeostasis. Excessive oxidative stress is considered as playing an important role in the pathogenesis of autoimmune diseases by enhancing inflammation and breaking down the immunological tolerance through protein structural modifications that induce the appearance of neo/cryptic epitopes.

RECENT ADVANCES

There is a complex reciprocal relationship between oxidative stress and both apoptosis and autophagy, which is essential to determine cell fate. This is especially relevant in the context of autoimmune disorders in which apoptosis and autophagy play a crucial pathogenic role.

CRITICAL ISSUES

In this review, we describe the latest developments with regard to the involvement of redox molecules in the initiation and progression of autoimmune disorders, focusing on their role in cell fate regulation. We also discuss new therapeutic approaches that target oxidative stress in the treatment of these disorders. The administration of antioxidants is scarcely studied in autoimmunity, and future analyses are needed to assess its beneficial effects in preventing or ameliorating these diseases.

FUTURE DIRECTIONS

Deciphering the intricate relationships between oxidative stress and both apoptosis and autophagy in the context of autoimmunity could be critical in elucidating key pathogenic mechanisms and could lead to novel interventions for the clinical management of autoimmune diseases.

Association of immunological cell profiles with specific clinical phenotypes of scleroderma disease

This study aimed to search the correlation among immunological profiles and clinical phenotypes of scleroderma in well-characterized groups of scleroderma patients, comparing forty-nine scleroderma patients stratified according to specific clinical phenotypes with forty-nine healthy controls. Five immunological cell subpopulations (B, CD4(+) and CD8(+) T-cells, NK, and monocytes) and their respective stages of apoptosis and activation were analyzed by flow cytometry, in samples of peripheral blood mononuclear cells (PBMCs). Analyses of results were stratified according to disease stage, time since the diagnosis, and visceral damage (pulmonary fibrosis, pulmonary hypertension, and cardiac affliction) and by time of treatment with corticosteroids. An increase in the percentages of monocytes and a decrease in the B cells were mainly related to the disease progression. A general apoptosis decrease was found in all phenotypes studied, except in localized scleroderma. An increase of B and NK cells activation was found in patients diagnosed more than 10 years ago. Specific cell populations like monocytes, NK, and B cells were associated with the type of affected organ. This study shows how, in a heterogeneous disease, proper patient's stratification according to clinical phenotypes allows finding specific cellular profiles. Our data may lead to improvements in the knowledge of prognosis factors and to aid in the analysis of future specific therapies.

Initiation but no execution - modulation of peripheral blood lymphocyte apoptosis in rheumatoid arthritis - a potential role for heat shock protein 70

Background

Rheumatoid arthritis (RA) is a chronic autoimmune disease, which causes synovial damage. Persistence of lymphocyte infiltrates in the rheumatoid synovium has been attributed to abnormal apoptosis. While not comprehensively investigated, perturbations in peripheral blood lymphocyte (PBL) apoptosis may also be involved in perpetuation of autoimmune processes in RA.

Methods

We investigated total, CD4+ and CD19+ PBL apoptosis in our study cohort by monitoring the translocation of phosphatidylserine using the Annexin-V assay. To examine the role of death receptor mediated apoptosis as well as activation-induced-cell-death (AICD), PBLs were labeled with CD95/Fas and CD69 markers and enumerated by flow cytometry. Proteolytic activity of initiator and executioner caspases was determined by luminometry. DNA fragmentation assays were used to examine whether apoptotic signals were transduced to the nucleus. Quantitative PCR arrays were used to investigate apoptotic pathways associated with RA-PBLs. Since heat-shock-protein-70 (HSP70) is an inducible protein which modulates apoptotic signals, we determined HSP70 levels by intra-cellular flow cytometry and western blots.

Results

The RA-PBLs showed signs of elevated apoptosis whilst in circulation. These include increases in the loss of plasma membrane asymmetry, indicated by increased externalization of phosphatidylserine (especially in B-lymphocytes). RA-PBLs showed a bias to CD95/Fas mediated apoptotic pathways, but low levels of the CD69 marker suggested that this was not associated with immune activation. Although downstream markers of apoptosis such as caspase-3/7 activity, were increased, no DNA fragmentation was observed in RA-PBLs. Interestingly, elevated levels of apoptosis did not correlate with absolute lymphocyte counts in RA patients. Levels of HSP70 were highly elevated in RA-PBLs compared to controls.

Conclusion

The results suggest that while apoptosis may be initiated in RA-PBLs, they may lack commitment to fully executing the apoptotic program. This may be related to inhibition on apoptotic transduction by HSP70. This study provides evidence that abnormalities in RA-PBLs apoptosis may occur whilst still in circulation and may contribute to pathogenesis of the disease.

Autoimmune mechanisms of scleroderma and a role of oxidative stress

Scleroderma is a fibrotic condition characterized by immunological abnormalities, vascular injury and increased accumulation of extracellular matrix proteins in the skin. Although the etiology of scleroderma has not yet been fully elucidated, a growing body of evidence suggests that extracellular matrix overproduction by activated fibroblasts results from complex interactions among endothelial cells, lymphocytes, macrophages and fibroblasts via a number of mediators, such as cytokines, chemokines and growth factors. Recent investigations have further suggested that reactive oxygen species (ROS) are involved and play a role of autoimmunology in scleroderma. In this review, current findings on the autoimmune mechanisms in the pathophysiology of scleroderma are described.

Analyses of T cell phenotype and function reveal an altered T cell homeostasis in systemic sclerosis. Correlations with disease severity and phenotypes

We investigated in systemic sclerosis (SSc) patients the T cell homeostasis and its relationship with the clinical course of the disease. Distribution of peripheral T cell subsets, thymic output, lymphocyte proliferation and apoptosis were analyzed by flow cytometry or ELISA. Age inappropriate levels of naive CD4(+) T cells and thymic output were observed. Proliferation of CD4(+) T cells, lymphocyte apoptosis and CD4(+) regulatory T (Treg) cell frequency were significantly higher than those observed in controls and significantly correlated with clinical phenotypes and clinical progression parameters i.e., diffusing capacity of the lung for carbon monoxide (DLCO) and disease activity. These data indicate that the evaluation of the T cell homeostasis can represent a valuable prognostic tool for SSc patients and it is useful to distinguish between limited and diffuse phenotypes. A therapeutic intervention targeted at reversing T cell homeostasis abnormalities would therefore potentially be helpful in counteracting disease progression.

Regulatory T cells (CD4(+)CD25(bright)FoxP3(+)) expansion in systemic sclerosis correlates with disease activity and severity

BACKGROUND

The role and function of T regulatory (Treg) cells have not been fully investigated in patients with systemic sclerosis (SSc).

METHODS

Ten patients with SSc donated 20ml of peripheral blood. Activity (Valentini) and severity (Medsger) scores for SSc were calculated for all patients. Healthy volunteers (controls) were matched to each patient by gender and age. CD4(+) cells were separated using the MACS system. The numbers of Treg cells were estimated by flow cytometry after staining for CD4, CD25, and FoxP3 and calculated as patient-to-control ratio separately for each experiment. Correlations with activity and severity indices of the disease were performed. Twenty-four-hour production of TGF-beta and IL-10 by activated CD4(+) cells was measured by ELISA in culture supernatants.

RESULTS

The numbers of Treg cells, expressed as patient-to-control ratio, correlated significantly with both activity and severity indices (r=0.71, p=0.034 and r=0.67, p=0.044, respectively). ELISA-measured production of TGF-beta and IL-10 by CD4(+) cells was similar in patients and controls.

CONCLUSIONS

Increased numbers of Treg cells are present in patients with SSc, correlating with activity and severity of the disease. This expansion of Treg cells was not accompanied, however, by heightened TGF-beta or IL-10 production. Further studies to elaborate the causes and functional significance of Treg cell expansion in SSc are needed.

Increased apoptosis in circulating lymphocyte cultures of anti-RNA polymerase III positive patients with systemic sclerosis

The sera of 39 patients (38 women and 1 man), 16 with limited and 23 with diffuse clinical form of systemic sclerosis (SSc), were tested for anti-centromere (ACA), anti-topoisomerase I (ATA) and anti-RNA polymerase III (ARA) antibodies. The presence of apoptotic cells in cultures of circulating lymphocytes was investigated using the TUNEL (terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end labeling) technique. ACAs were present in 16 (41%), ATA in 15 (38%) and ARA in 8 (21%) cases. The mean frequency of apoptotic lymphocytes was statistically higher in the ARA positive patients with respect to that in the control population (P < 0.001), in ACA (P < 0.001) and in the ATA (P < 0.001) groups. Moreover, apoptosis was distributed homogenously in ACA and ATA positive subjects, but not in the ARA patients. Our results show that there is an increase in apoptosis in the lymphocytes of ARA positive SSc patients.

The immunobiology of systemic sclerosis

OBJECTIVES

Systemic sclerosis (SSc) is a chronic connective tissue disease characterized by vascular damage, autoimmunity, and excessive collagen deposition. Despite advances in disease-specific treatment of other rheumatologic diseases, disease-targeted treatment in SSc continues to be elusive. In this review, our goal was to place the contemporary immunobiology of SSc in the perspective of clinical medicine.

METHODS

We performed a PubMed search for the period from 1989 to 2007, using the keyword, "systemic sclerosis," resulting in a total of 9099 publications, including 1252 reviews. Articles were then selected based on their discussion of recent advances in the elusive pathogenesis of SSc. A final total of 259 articles were chosen for the review.

RESULTS

The SSc hallmarks of vascular damage, immunologic activation, and collagen deposition can be traced to 4 major factors: T-cells, fibroblasts, B-cells, and cytokines/chemokines. T-cells are a major component of the infiltrate in skin and lung, exhibiting increased expression of activation markers and showing signs of antigen-driven expansion. Preliminary data indicate that induction of oral tolerance with collagen, a target of SSc T-cell responses, is associated with clinical benefits. Although this suggests that T-cells participate in the pathogenesis of SSc, their precise role and antigen specificity largely remain to be elucidated. Defective numbers and functions of certain T-cell subsets, such as natural killer and gammadelta T-cells, may be involved in the failure to maintain tolerance. Other data suggest that gammadelta T-cells may themselves be effector cells in endothelial cell cytotoxicity. There are several lines of evidence for a pathogenic role of B-cells in SSc, in particular, through the production of autoantibodies. Antibody-dependent cell-mediated cytotoxicity is a primary pathogenic event in an animal model of SSc and is likely to be involved in human SSc. Nonetheless, there is as yet no convincing evidence for the pathogenicity of SSc-specific antibodies. SSc fibroblasts exhibit a specific phenotype characterized not only by excessive collagen production but also by increased responsiveness to and production of cytokines and chemokines. This phenotype is induced by a complex network of cytokines and chemokines but appears to be maintained in the absence of exogenous stimuli via the autocrine production of some of these factors by SSc fibroblasts themselves, particularly transforming growth factor, platelet-derived growth factor, monocyte chemoattractant protein 1, and interleukin-1.

CONCLUSIONS

Significant variations in laboratory data among patients suggest that the pathology reflects a heterogeneous disease. Nonetheless, the possibility of achieving clinical benefits by inducing oral tolerance highlights the importance of characterizing SSc T-cell antigens. It is hoped that the identification of some of the key players in the induction and maintenance of the SSc fibroblast phenotype may yield new disease-targeted treatment regimens for patients with SSc.

Engulfed cell remnants, and not cells undergoing apoptosis, constitute the LE-cell phenomenon

The LE cell has been one of the first immunological signs of active systemic lupus erythematosus, included into the ACR criteria. LE cells consist of a phagocyte engulfing material of disputed origin, which was interpreted as either cellular remnants from necrotic cells or as early apoptotic cells. It is well established that LE cell formation is dependent on autoantibodies against the linker histone H1. In view of this fact, we investigated whether anti-histone H1 antibodies and LE cell positive sera bound to cells where apoptosis had been induced by gliotoxin or actinomycin D or which were necrotic after heating. Necrotic cell remnants, but not (early) apoptotic cells were bound by anti-histone H1 antibodies and LE cell positive sera, establishing that the process of LE cell formation, which is dependent on anti-H1 binding, leads to engulfment of necrotic (or late apoptotic) material, but not of early apoptotic cells.

Serum soluble Fas levels in patients with autoimmune rheumatic diseases

OBJECTIVE

The role of the serum soluble Fas (sFAS) system is unclear in diagnosis of several autoimmune rheumatic diseases although there are present contradictory reports on the levels of serum sFas. We therefore assessed levels of sFAS in serum of patients with autoimmune rheumatic diseases.

PATIENTS AND METHODS

We analyzed sFas levels and their relationship to clinical and laboratory data in patients with systemic lupus erythematosus (SLE, n=32), rheumatoid arthritis (RA, n=28), Sjögren's syndrome (SS, n=20) systemic sclerosis (SSc, n=21), polymyositis/dermatomyositis (PM/DM, n=15). Patients with osteoarthritis (OA, n=20) and healthy volunteers (n=20) were used as controls. Serum levels of sFAS were determined by ELISA. sFas levels greater than mean (normals)+2 SD were considered as elevated.

RESULTS

The mean sFas values were found higher in RA, PM/DM and OA than in control although no differences were found in SSc and SS patients. The mean sFas levels in SLE patients were lower than healthy controls. Elevated sFas rates in RA, PM/DM and SS were found to be 21.4%, 60%, 10% higher than in healthy controls, respectively. sFas levels in SLE and SSc did not differ from control values. Mean sFas levels did not show significant difference between active and inactive patients in all disease groups except PM/DM, RA and OA. No correlations of sFas with relevant disease subsets, laboratory findings and treatment modalities were found.

CONCLUSIONS

The findings indicate that the serum sFas molecule may provide a useful additional marker for presence and assessment of disease in patients with RA and PM/DM.

Effects of short-term infliximab therapy on autoantibodies in systemic lupus erythematosus

OBJECTIVE

To analyze changes in autoantibodies occurring in patients with systemic lupus erythematosus (SLE) treated with 4 infusions of the chimeric anti-tumor necrosis factor alpha (TNFalpha) antibody infliximab.

METHODS

In an open-label safety study, 7 patients with SLE were treated with infliximab at weeks 0, 2, 6, and 10 in combination with azathioprine or methotrexate. Antibodies to double-stranded DNA (dsDNA) were determined by radioimmunoassay and the Crithidia luciliae indirect immunofluorescence assay; anticardiolipin antibodies (aCL) and antibodies to histone and chromatin were measured by enzyme-linked immunosorbent assay. Antihistone antibodies were also analyzed by immunoblotting. Peripheral blood mononuclear cells from healthy individuals and SLE patients were incubated for 2 weeks with or without TNFalpha. TNFalpha was removed by washing and by the addition of infliximab. Apoptotic cells were stained with annexin V and analyzed by flow cytometry.

RESULTS

Autoantibodies to dsDNA increased in 5 of 7 patients. Histone, chromatin, and IgM aCL levels were increased in 4 of 7, 6 of 7, and 4 of 7 patients, respectively, peaking 4-10 weeks after the last infliximab infusion, but falling to baseline levels or lower thereafter. In the in vitro experiments, TNF withdrawal after long-term incubation with recombinant human TNF led to increased percentages of apoptotic cells.

CONCLUSION

While TNF blockade was clinically effective, the majority of SLE patients treated with infliximab showed an increase in autoantibodies to nuclear antigens and phospholipids. These increases were transient and were not associated with disease flares. Increased availability of apoptotic antigens after TNF blockade may play a role in the autoantibody formation induced by TNF blockade.

Methods to characterize lymphoid apoptosis in a murine model of autoreactivity

The immune system is shaped by the random generation of lymphocytes followed by apoptosis of self-reactive cells, a process termed negative selection. The survival of these pathogenic cells in the periphery can elicit autoreactivity. We describe the development of a biomarker assay for the detection of pathogenic subpopulations of lymphoid cells in adult non-obese diabetic (NOD) mice based on disease-specific alterations in spontaneous or triggered cell death. Utilizing improved methods of cell separations, two distinct lymphoid cell subpopulations with increased susceptibility to apoptosis were identified and quantified. A subpopulation of CD8+ T cells that constitutes approximately 3-7% of the total CD8+ T cell population underwent apoptosis on exposure to low concentrations of TNF-alpha. Such cells were exclusively detected only in NOD mice with histologic signs of active autoreactivity. The non-T cell compartment of NOD immune system, although resistant to TNF-alpha-induced apoptosis, contained a subpopulation of B cells with spontaneous death by culture alone. The refined detection of small numbers of lymphoid cell subsets with quantifiable differences in apoptosis provides a possible immune biomarker for monitoring disease activity or treatment interventions.

Scleroderma: from cell and molecular mechanisms to disease models

Scleroderma [also known as systemic sclerosis (SSc)] is a complex autoimmune disease characterised by pathological remodelling of connective tissues. Although the earliest and most frequent manifestations include blood vessel and immunological abnormalities, the systemic and progressive pathology suggests that fundamental interactions between microvascular damage and inflammation are mechanistically linked to obliterative tissue fibrosis. This review will focus on how model systems have provided clues to these relationships and will discuss new data from the study of novel animal disease models. These reveal how vascular damage and leukocyte accumulation generate the molecular cues that control the profiles of soluble mediators, which regulate the aberrant behaviour of mesenchymal cells within connective tissues, and how the dysregulated expression of these components and their differentiation contribute to the persistent fibrogenic response.

Inverse relationship between the ratio of ICAM-1 expressing lymphocytes and serum TGF-β1 concentrations in acute rheumatic fever

Autoimmunity in acute rheumatic fever (ARF) is triggered by group-A beta hemolytic streptococci (GAS). Although most of the recent work has focused on the major impact of lymphocytes, the exact immunopathogenesis is still unresolved. Regulation of self-tolerance in response to GAS has been investigated in various animal experiments. This study aimed to associate the ratio of lymphocytes bearing adhesion/costimulatory molecules, Bcl-2/CD95 and serum TGF-beta1 concentrations with clinical stages of ARF. Thirty-five patients were assigned according to the clinical stages. Bcl-2 expression on CD19+ and CD3+ lymphocytes was similar within patient groups and controls. CD62p expression was higher in patients with carditis. The ratio of ICAM-1 bearing lymphocytes was significantly different between patient groups and controls and was increased through acute to remission stages longitudinally. In contrast, a gradual and significant decrease in TGF-beta1 concentrations was observed longitudinally from acute to chronic stages. A positive correlation has been documented between ICAM-1+ lymphocyte ratios and Fas+ cytotoxic T cell ratios supported by a prominent increase in CD95+ T cells. These data draw our attention to the role of ICAM-1, Fas and TGF-beta1 in ARF pathogenesis through the perspective of self-tolerance in a clinical setting.

Increased CD8+ T cell apoptosis in scleroderma is associated with low levels of NF-kappa B

Our objectives were (1) to compare lymphocyte subpopulation apoptosis rates in SSc patients versus healthy controls and (2) to compare Bcl-2 and NF-kappa B expression in cultured CD8 lymphocytes of SSc patients versus controls. Peripheral blood samples were obtained from 27 SSc patients meeting the American College of Rheumatology criteria for SSc and 28 healthy individuals. Mononuclear cells were isolated by Ficoll-Hypaque density gradient separation and cultured for 48 hr. For determination of apoptosis within specific cell populations, samples were labeled with PE-conjugated monoclonal antibody to CD8, CD4, and a FITC-conjugated monoclonal antibody to Annexin V. Flow cytometry was carried out with a FACS operating with Cellquest software. CD8+ lymphocytes were positively selected with magnetic microbeads conjugated to antihuman CD8. CD8 T cells were separated, then incubated with activation for 48 hr, and NF-kappa B and Bcl-2 analysis was carried out using Western immunoblotting. The CD4:CD8 ratio was increased in SSc compared to controls (2.6 +/- 1.13 vs.1.87 +/- 0.76; P = 0.018). The spontaneous apoptosis rate of SSc CD8 lymphocytes was increased compared to that of controls of (21.9 +/- 13.7 vs. 13.3 +/- 9.9; P = 0.019). No difference was found in the rate of CD4 apoptosis of SSc patients versus controls (9.8 +/- 5.2 vs. 7.18 +/- 4.89%; P = ns). The expression of NF-kappa B in SSc CD8 lymphocytes was decreased compared with that of CD8 lymphocytes from healthy controls (144 +/- 13 vs. 188 +/- 11; P = 0.018). Whereas expression of Bcl-2 was similar in activated CD8+ T cells of SSc patients and healthy controls, CD8+ T cell apoptosis rate was found to be in reverse correlation with expression of NF-kappa B in these cells ( r = - 0.53, P = 0.029). The increased CD4:CD8 ratio in SSC may result from increased CD8+ T cell apoptosis. Increased SSc CD8 T cell apoptosis is associated with low levels of NF-kappa B.

Increased transendothelial migration of scleroderma lymphocytes

BACKGROUND

CD4+ T lymphocytes play an important part in the pathogenesis of scleroderma (systemic sclerosis, SSc) and predominate in perivascular SSc skin lesions. Both soluble and membrane bound adhesion molecules are overexpressed in SSc, possibly influencing lymphocyte/endothelial cell (EC) contact.

OBJECTIVE

To assess the transendothelial migration capacity of peripheral lymphocytes in vitro.

PATIENTS AND METHODS

Collagen was covered with human umbilical vein endothelial cells (HUVEC), and peripheral blood mononuclear cells (PBMC) of patients and matched healthy controls (HC) were added in parallel experiments. Before and after fractionated harvest of non-adherent, bound, and migrated lymphocytes, the CD4/CD8 ratio and the lymphocytic expression of activation markers and adhesion molecules were analysed by fluorocytometry.

RESULTS

13 (SD 12)% of the SSc PBMC migrated compared with only 5 (5)% HC PBMC (p<0.0002); this increase was primarily due to the migration of CD3+ T lymphocytes and mainly to a larger proportion of CD4+ cells within this CD3+ fraction (71 (SD 14)% for SSc v 56 (14)% for HC, p<0.03), leading to an increased CD4/CD8 ratio among migrated SSc lymphocytes in comparison with controls (3.3 (1.5) v 1.62 (0.93), p<0.006). Among migrated SSc CD4+ T lymphocytes, the frequency of HLA-DR+ cells was increased; migrated lymphocytes highly expressed the adhesion molecules CD11a, CD49d, CD29, and CD44.

CONCLUSION

Transendothelial migration of CD4+ T lymphocytes is enhanced in SSc, and migrating cells exhibit an activated phenotype. The data suggest that activated CD3+CD4+ lymphocytes as found in SSc peripheral blood are prone to transvascular migration, thus contributing to the formation of typical perivascular lymphocytic infiltrates.

The levels of serum-soluble Fas in patients with rheumatoid arthritis and systemic sclerosis

Different defects in Fas/APO-1 interaction with its ligand or in signaling of apoptosis may contribute to autoimmune disease. The aim of this study was to examine whether elevated serum-soluble Fas (sFas) levels are associated with rheumatoid arthritis (RA) or systemic sclerosis (SSc). sFas level was assayed using a sandwich ELISA in serum from 37 patients with RA, 30 patients with SSc and 20 healthy controls. The RA patients were classified according to disease activity, anatomical joint damage, and the presence of pulmonary involvement. Presence of pulmonary fibrosis, CO diffusion capacity (DLCO) and skin score were determined in patients with SSc. Serum sFas levels were not significantly different between study groups. Serum sFas level in the active RA patients was significantly higher than in the patients with inactive disease (p < 0.05). The untreated active RA patients had significantly higher sFas level than healthy controls (p < 0.05). In RA patients, sFas level was significantly correlated with rheumatoid factor titer (p = 0.01), C-reactive protein (p < 0.05), and erythrocyte sedimentation rate (p < 0.05). The RA patients with severe joint damage had significantly higher sFas level than those with mild joint damage (p < 0.05). The untreated SSc patients had significantly higher sFas levels than the treated SSc patients and healthy controls (p < 0.01). Serum sFas level was not correlated with presence of pulmonary fibrosis, DLCO or skin score. The soluble Fas molecule may provide a useful additional marker for assessment of disease activity and severity in patients with RA.

Programmed cell death in rheumatoid arthritis peripheral blood T-cell subpopulations determined by laser scanning cytometry

Because peripheral blood mononuclear cells play an important role in the perpetuation of the autoimmune process in rheumatoid arthritis (RA) and because the maintenance of these cells might be caused by the dysregulation of apoptosis, we investigated the apoptosis susceptibility of peripheral blood mononuclear cells from patients with RA. Freshly separated peripheral blood lymphocytes were stained for apoptosis markers (CD95, Bax, Bcl-2, TNF receptor) and for an activation marker (CD45-RO), and the apoptosis frequency of cells bearing these markers were assessed by the terminal-deoxynucleotidyl transferase-mediated dUTP digoxigenin nick end labeling method and nuclear condensation analysis with laser scanning cytometry. Also, the ability of CD4(+) and CD8(+) T-cell populations to undergo apoptosis was investigated with 24-hour culture in medium alone or with different apoptosis inducers (anti-CD3, anti-CD95, anti-TNF receptor). Laser scanning cytometry analysis was used to enumerate the phenotype and apoptosis ratios of both freshly isolated and cultured lymphocytes. Quantitative ELISA was performed to detect plasma levels of TNF-alpha and soluble Fas ligand. Furthermore, we studied the relationship between marked apoptotic defects in patients with RA and the severity of clinical disease. CD4(+) T-cell counts in patients with RA were elevated compared with controls. A decreased rate of anti-CD95-mediated apoptosis was found within the CD4(+) and CD8(+) lymphocytic subpopulations. In patients with RA, decreased Bax expression and decreased apoptosis rate within the Bax-positive cells were found, whereas Bcl-2 expression was elevated. The CD45-RO expression was higher, whereas the apoptosis within CD45-RO(+) cells were decreased in RA. Evaluation of plasma soluble Fas ligand revealed significantly decreased levels in patients compared with controls. The reduced susceptibility to CD95-mediated apoptosis may contribute to the expansion of an activated CD4(+) lymphocyte subpopulation and thus to the maintenance of peripheral autoreactive T-cell clones in RA. We also revealed a relationship between in vitro demonstrated lymphocyte apoptosis defects and clinical disease activity.

Distinct immune profiles characterize patients with diffuse or limited systemic sclerosis

Mitogen-stimulated IL-2, IFN-gamma, TNF-alpha (type 1 cytokines), and IL-10 (type 2 cytokine) production by peripheral blood mononuclear cells, as well as expression of surface markers on immune cells, was evaluated in systemic sclerosis (SSc) patients. Fifty-four SSc patients with either diffuse (dSSc) or limited (lSSc) disease and 20 age- and sex-matched healthy controls (HCs) were examined. Fourteen patients were treated with prednisone and 9 patients with prednisone and cyclophosphamide pulses. Results showed that (1) IL-2 production is significantly decreased, whereas IL-10 is higher in untreated patients compared to HCs; IL-10, IFN-gamma, and TNF-alpha production is higher in lSSc compared to dSSc patients; (2) CD4+25+ (IL-2R), CD8+, and CD8+45RA-28+57- (memory) lymphocytes are reduced in patients compared to HCs; (3) CD95-expressing CD4+ and CD8+ cells are significantly higher in dSSc patients; and (4) steroids are more effective alone than in combination with cyclophosphamide in reducing IL-10 and IFN-gamma production in these patients. These results confirm that a complex imbalance in cytokine production is present in SSc patients and suggest that peculiar phenotypic populations are underrepresented in these patients. Overexpression of Fas in dSSc could results from the attempt of the immune system to induce apoptosis of autoreactive T-cell clones.

Increased bioactive TNF in human systemic lupus erythematosus: associations with cell death

In systemic lupus erythematosus (SLE) serum TNF is increased and correlates with its soluble receptors and with disease activity. We therefore investigated (i) whether the TNF in SLE serum is bioactive, (ii) whether SLE cells react to TNF and (iii) whether there are associations with cell death, which is regarded as pathogenic in SLE. Sera from active SLE patients induced an increase in fibroblast CD54, which was abolished by blocking antibodies against TNF, suggesting TNF bioactivity. SLE lymphocytes had a similar surface expression of TNF-RI as healthy lymphocytes, their expression of TNF-RII was slightly increased. Recombinant TNF induced cell death in PBMC of SLE patients, suggesting functional receptors. Serum levels of sTNF-RII (as a surrogate marker for TNF activity) correlated with sTNF-RI and disease activity, as expected, and also correlated with the percentage of dying lymphocytes and with lymphocytic CD95. SLE sera contain increased amounts of biologically active TNF. Peripheral blood lymphocytes of SLE patients express functional TNF receptors. Finally, associations with cell death and CD95 receptors suggest that TNF may be pathogenic in SLE.

Current treatment options in systemic Sclerosis (Scleroderma)

Systemic Sclerosis (SSc) or Scleroderma is a generalized autoimmune disease with variable involvement of the skin and major organs. Etiology and pathogenesis are still largely unknown, but a variety of humoral and cellular autoimmune phenomena can be observed, and a pivotal role of T lymphocytes in SSc pathogenesis is postulated. The rarity of the disease, the wide spectrum of clinical manifestations and severity as well as a variable course render therapy in SSc a major challenge. In view of the immunopathogenesis of SSc, many (presumed) immunomodulatory agents have been used, but no single agent has been proven to be convincingly effective. Trials with extracorporeal therapies (such as photopheresis, plasmapheresis) or even stem cell transplantation are in progress. In contrast to the hitherto unsuccessful therapeutic approaches for the overall disease course, some life-threatening organ manifestations can often be treated successfully, e.g. interstitial pneumonitis with i.v. cyclophosphamide and scleroderma renal crisis with ACE inhibitors and haemodialysis, respectively. Furthermore, pharmacological and supportive treatment of Raynaud's phenomenon and gastrointestinal involvement can alleviate the burden of the disease. Current therapeutic options as well as hitherto investigated immunomodulators are reviewed in this article.