Antihistone antibodies in systemic sclerosis. Association with pulmonary fibrosis

Neutrophil extracellular trap formation in anti-neutrophil cytoplasmic antibody-associated and large-vessel vasculitis

Levels of neutrophil extracellular traps (NETs) were measured in plasma of healthy controls (HC, n = 30) and patients with granulomatosis with polyangiitis (GPA, n = 123), microscopic polyangiitis (MPA, n = 61), Takayasu's arteritis (TAK, n = 58), and giant cell arteritis (GCA, n = 68), at times of remission or activity and correlated with levels of the platelet-derived thrombospondin-1 (TSP-1). Levels of NETs were elevated during active disease in patients with GPA (p < 0.0001), MPA (p = 0.0038), TAK (p < 0.0001), and GCA (p < 0.0001), and in remission for GPA, p < 0.0001, MPA, p = 0.005, TAK, p = 0.03, and GCA, p = 0.0009. All cohorts demonstrated impaired NET degradation. Patients with GPA (p = 0.0045) and MPA (p = 0.005) had anti-NET IgG antibodies. Patients with TAK had anti-histone antibodies (p < 0.01), correlating with presence of NETs. Levels of TSP-1 were increased in all patients with vasculitis, and associated with NET formation. NET formation is a common process in vasculitides. Targeting NET formation or degradation could be potential therapeutic approaches for vasculitides.

Cytokine-producing B-cell balance associates with skin fibrosis in patients with systemic sclerosis

Systemic sclerosis (SSc) is an autoimmune disease characterized by skin and lung fibrosis. Over 90% of patients with SSc are positive for autoantibodies. In addition, the serum levels of B-cell activating factor, a potent B-cell stimulator, are correlated with SSc severity and activity. Thus, B cells play an important role in SSc pathogenesis. However, two opposing B-cell subsets exist: effector B cells (Beff) and regulatory B cells (Breg). Interleukin (IL)-6-producing Beff have been shown to promote scleroderma in a mouse model, whereas IL-10-producing Breg inhibit scleroderma development. In the present study, we investigated the clinical association of effector and regulatory B cells in patients with SSc. The blood levels of IL-6-producing Beff and IL-10-producing Breg were measured in 30 patients with SSc and 21 healthy subjects by flow cytometry. The frequency of IL-6-producing Beff in the blood was significantly (p < 0.0001) elevated in patients with SSc (median, 56.2%; range, 35.3-81.3%) compared with that in healthy controls (median, 41.3%; range, 21.0-61.3%). In contrast, the frequency of IL-10-producing Breg in the blood was significantly (p < 0.05) decreased in patients with SSc (median, 1.4%; range, 0.5-2.8%) compared with that in healthy controls (median, 2.0%; range, 1.1-3.8%). The Beff/Breg ratio was significantly increased in patients with SSc. In addition, the Beff/Breg ratio was positively correlated with the skin score and extent of interstitial lung disease. These results suggest that dysregulation of effector and regulatory B-cell balance contributes to SSc pathogenesis.

Clinical use of anti-histone antibodies in idiopathic and drug-induced lupus

Anti-histone antibodies (AHAs) make their appearance in a number of systemic autoimmune diseases including systemic lupus erythematosus (SLE) and drug-induced lupus erythematosus (DILE). Although being known for over 50 years, they are poorly studied and understood. There is emerging evidence for their use in predicting clinical features of SLE, diversifying their clinical use. AHAs, however, are probably less prevalent in DILE than once thought owing to a move away from older DILE drugs to modern biological agents which do not appear to elicit AHAs. This review examines the historical studies that have defined AHAs and looks at some of the recent work with these autoantibodies.

Single-cell-level protein analysis revealing the roles of autoantigen-reactive B lymphocytes in autoimmune disease and the murine model

Despite antigen affinity of B cells varying from cell to cell, functional analyses of antigen-reactive B cells on individual B cells are missing due to technical difficulties. Especially in the field of autoimmune diseases, promising pathogenic B cells have not been adequately studied to date because of its rarity. In this study, functions of autoantigen-reactive B cells in autoimmune disease were analyzed at the single-cell level. Since topoisomerase I is a distinct autoantigen, we targeted systemic sclerosis as autoimmune disease. Decreased and increased affinities for topoisomerase I of topoisomerase I-reactive B cells led to anti-inflammatory and pro-inflammatory cytokine production associated with the inhibition and development of fibrosis, which is the major symptom of systemic sclerosis. Furthermore, inhibition of pro-inflammatory cytokine production and increased affinity of topoisomerase I-reactive B cells suppressed fibrosis. These results indicate that autoantigen-reactive B cells contribute to the disease manifestations in autoimmune disease through their antigen affinity.

Interleukin-31 promotes fibrosis and T helper 2 polarization in systemic sclerosis

Systemic sclerosis (SSc) is a chronic multisystem disorder characterized by fibrosis and autoimmunity. Interleukin (IL)-31 has been implicated in fibrosis and T helper (Th) 2 immune responses, both of which are characteristics of SSc. The exact role of IL-31 in SSc pathogenesis is unclear. Here we show the overexpression of IL-31 and IL-31 receptor A (IL-31RA) in dermal fibroblasts (DFs) from SSc patients. We elucidate the dual role of IL-31 in SSc, where IL-31 directly promotes collagen production in DFs and indirectly enhances Th2 immune responses by increasing pro-Th2 cytokine expression in DFs. Furthermore, blockade of IL-31 with anti-IL-31RA antibody significantly ameliorates fibrosis and Th2 polarization in a mouse model of SSc. Therefore, in addition to defining IL-31 as a mediator of fibrosis and Th2 immune responses in SSc, our study provides a rationale for targeting the IL-31/IL-31RA axis in the treatment of SSc.

Systemic sclerosis (SSc) disease involves multisystem fibrosis and autoimmunity with limited treatment options. Here the authors demonstrate that IL-31 and IL-31RA are overexpressed in dermal fibroblasts from SSc patients and show that fibrosis and cytokine release can be reduced upon blocking of IL-31/IL-31RA.

Increased expression of GAB1 promotes inflammation and fibrosis in systemic sclerosis

Systemic sclerosis (SSc) is an autoimmune disease mainly characterized by persistent inflammation and fibrosis. The receptor tyrosine kinase (RTK) signal pathway plays an important role in the process of SSc, and Grb2-associated binding protein (GAB) is crucial in activating RTK signalling. A previous study found elevated levels of GAB1 in bleomycin (BLM)-induced fibrotic lungs, but the effects of GAB1 in SSc remain unclear. Our aim was to investigate whether GAB1 was dysregulated and its potential role in SSc. Compared with healthy donors, we found GAB1 expression was 1.6-fold higher in peripheral blood mononuclear cells (PBMC), 2.5-fold higher in CD4 + T cells, and 2-fold higher in skin from of SSc patients (P < .01). At the same time, the levels of type one collagen (COLI) were also significantly increased (1.8-fold higher) in SSc skin. Additionally, BLM-induced SSc mice showed mRNA levels of Gab1 2-fold higher than saline-treated controls, and Gab1 expression correlated positively with collagen content. A further in vitro study showed silencing of GAB1 suppressed inflammatory gene expression in TNF-α induced fibroblasts. Additionally, GAB1 deficiency prominently inhibited cell proliferation and reduced COLI protein levels in TGF-β induced fibroblasts. Taken together, these data suggest that GAB1 has a relatively high expression rate in SSc, and knockdown of GAB1 may attenuate SSc by stimulating inflammatory and fibrotic processes.

Immunopathogenesis of Pediatric Localized Scleroderma

Localized scleroderma (LS) is a complex disease characterized by a mixture of inflammation and fibrosis of the skin that, especially in the pediatric population, also affects extracutaneous tissues ranging from muscle to the central nervous system. Although developmental origins have been hypothesized, evidence points to LS as a systemic autoimmune disorder, as there is a strong correlation to family history of autoimmune disease, the presence of shared HLA types with rheumatoid arthritis, high frequency of auto-antibodies, and elevated circulating chemokines and cytokines associated with T-helper cell, IFNγ, and other inflammatory pathways. This inflammatory phenotype of the peripheral blood is reflected in the skin via microarray, RNA Sequencing and tissue staining. Research is underway to identify the key players in the pathogenesis of LS, but close approximation of inflammatory lymphocytic and macrophage infiltrate with collagen and fibroblasts deposition supports the notion that LS is a disease of inflammatory driven fibrosis. The immune system is dynamic and undergoes changes during childhood, and we speculate on how the unique features of the immune system in childhood could potentially contribute to some of the differences in LS between children and adults. Interestingly, the immune phenotype in pediatric LS resembles to some extent the healthy adult cellular phenotype, possibly supporting accelerated maturation of the immune system in LS. We discuss future directions in better understanding the pathophysiology of and how to better treat pediatric LS.

Clinical Significance of Serum Galectin-9 and Soluble CD155 Levels in Patients with Systemic Sclerosis

Signaling through coinhibitory receptors downregulates the immune response to prevent excessive immune activation and maintain optimal immunity and tolerance. The aim of this study was to examine the levels of the soluble forms of coinhibitory receptors and their ligands, namely, galectin-9 (the ligand of T-cell immunoglobulin and mucin domain 3) and CD155 (the ligand of T cell immunoglobulin and immunoreceptor tyrosine-based inhibitory motif domain), and their association with clinical features in patients with systemic sclerosis (SSc). The serum levels of galectin-9 and soluble sCD155 were examined by enzyme-linked immunosorbent assays in patients with SSc, and the results were evaluated with respect to clinical features. Patients with SSc exhibited raised serum levels of galectin-9, but not sCD155. Serum galectin-9 levels were raised not only in patients with diffuse cutaneous SSc but also in patients with limited cutaneous SSc. Furthermore, serum galectin-9 levels correlated positively with the erythrocyte sedimentation rate. In addition, increased serum galectin-9 levels tended to be associated with higher mortality and serious organ involvement. These results suggest that galectin-9, but not CD155, may be involved in the pathogenesis of SSc. In addition, the measurement of serum galectin-9 levels could be used to predict serious organ involvement and high mortality in patients with SSc.

Risk factors for primary Sjögren syndrome-associated interstitial lung disease

Background

Primary Sjögren syndrome (pSS) is a chronic inflammatory autoimmune disease that is characterized by lymphocytic infiltration of the exocrine glands and extraglandular organ systems. Interstitial lung disease (ILD) is common in pSS patients and is one of the independent risk factors for a poor prognosis. The previously reported characteristics and potential risks contributing to pSS-associated ILD have been controversial.

Methods

A cohort of 201 newly diagnosed pSS patients were studied over a period of 3 years. Data were from clinical charts. The pSS patients were classified into two groups, namely pSS-ILD or pSS without ILD, according to the lung evaluation.

Results

In total, the prevalence of pSS-associated ILD was 78.6%. The pSS patients associated ILD were more likely to be male, older and smokers in comparison to the pSS patients without ILD. There were no significant differences in multiorgan involvement between the two groups. Nonspecific interstitial pneumonia (NSIP) was the most common radiological pattern (45.5%). pSS with ILD was associated with increasing age [odds ratio (OR) =1.073], smoking (OR =8.544) and antinuclear antibody (ANA) positive (OR =3.286). Over a median follow-up period of 24 months (range, 18-30 months), no patients died, experienced acute exacerbation of ILD, or had newly diagnosed pSS-ILD.

Conclusions

pSS associated ILD were more commonly in males, older patients and smokers. Aging, cigarette smoking, and ANA positivity may be potential risk factors contributing to ILD in pSS patients.

Role of Autoantibodies in the Diagnosis of Connective-Tissue Disease ILD (CTD-ILD) and Interstitial Pneumonia with Autoimmune Features (IPAF)

The diagnosis of interstitial lung disease (ILD) requires meticulous evaluation for an underlying connective tissue disease (CTD), with major implications for prognosis and management. CTD associated ILD (CTD-ILD) occurs most commonly in the context of an established CTD, but can be the first and/or only manifestation of an occult CTD or occur in patients who have features suggestive of an autoimmune process, but not meeting diagnostic criteria for a defined CTD-recently defined as "interstitial pneumonia with autoimmune features" (IPAF). The detection of specific autoantibodies serves a critical role in the diagnosis of CTD-ILD, but there remains a lack of data to guide clinical practice including which autoantibodies should be tested on initial assessment and when or in whom serial testing should be performed. The implications of detecting autoantibodies in patients with IPAF on disease behaviour and management remain unknown. The evaluation of CTD-ILD is challenging due to the heterogeneity of presentations and types of CTD and ILD that may be encountered, and thus it is imperative that immunologic tests are interpreted in conjunction with a detailed rheumatologic history and examination and multidisciplinary collaboration between respiratory physicians, rheumatologists, immunologists, radiologists and pathologists.

Increased expression of latent TGF-β-binding protein 4 affects the fibrotic process in scleroderma by TGF-β/SMAD signaling

Scleroderma is a fibrosis-related disorder characterized by cutaneous and internal organ fibrosis, and excessive collagen deposition in extracellular matrix (ECM) is a major cause of fibrosis. Transforming growth factor-β (TGF-β)/SMAD signaling has a central role in the pathogenesis of fibrosis by inducing abnormal collagen accumulation in ECM, and latent TGF-β-binding protein 4 (LTBP-4) affects the secretion of latent TGF-β to ECM. A previous study indicated that bleomycin (BLM) treatment increased LTBP-4 expression in lung fibroblasts of Thy-1 knockout mice with lung fibrosis, and LTBP-4 further promoted TGF-β bioavailability as well as SMAD3 phosphorylation. However, the expression and function of LTBP-4 in human scleroderma remain unclear. We aimed to investigate the potential role of LTBP-4 in scleroderma through clinical, in vivo and in vitro studies. LTBP-4 and TGF-β expressions were significantly upregulated in systemic scleroderma (SSc) patients' plasma compared with normal controls (LTBP-4, 1,215±100.2 vs 542.8±41.7 ng/ml, P<0.0001; TGF-β, 1.5±0.2 vs 0.7±0.1 ng/ml, P=0.0031), while no significant difference was found between localized scleroderma (LSc) and normal controls. The plasma concentrations of LTBP-4 and TGF-β were even higher in SSc patients with lung fibrosis (LTBP-4, 1462± 137.3 vs 892.8±113.4 ng/ml, P=0.0037; TGF-β, 2.0±0.4 vs 0.9±0.2 ng/ml, P=0.0212) and esophagus involvement (1390±134.4 vs 940.7±127.0 ng/ml, P=0.0269; TGF-β, 1.9±0.3 vs 0.9±0.2 ng/ml, P=0.0426). The area under receiver operating characteristics (ROC) curve of LTBP-4 was 0.86. Immunohistochemistry measurement also demonstrated a higher LTBP-4 expression in sclerotic skin tissue of LSc and SSc compared with normal controls. More positive fibroblasts were also found in BLM-induced scleroderma mouse model than the saline-treated group. In in vitro studies, knockdown of LTBP-4 in SSc skin fibroblasts prominently reduced downstream COL1A1, COL1A2, and COL3A1 mRNA level by 84%, 82%, and 43%, respectively, and other fibrosis-related genes' expression were also decreased. Furthermore, extracellular TGF-β level and the SMAD2/3 phosphorylation were inhibited through LTBP-4 knockdown treatment, suggesting that the knockdown of LTBP-4 reduced the collagen expression through TGF-β/SMAD signaling pathway. Taken together, these data suggest that LTBP-4 affects fibrotic process in scleroderma, and the high expression of LTBP-4 in SSc plasma may serve as a clinical biomarker in diagnosing this disease. In addition, this study also lays the theoretical foundation for targeting LTBP-4 as treatment of scleroderma.

Increased expression of S100A8 and S100A9 in patients with diffuse cutaneous systemic sclerosis. A correlation with organ involvement and immunological abnormalities

S100A8 and S100A9 play important roles in immune and inflammatory disorders. The role of the two proteins in systemic sclerosis (SSc) remains unknown. Fifty-seven diffuse cutaneous SSc (dcSSc) patients, 31 limited cutaneous SSc (lcSSc) patients were recruited in the present study. The expression of S100A8 and S100A9 in plasma was measured using an enzyme-linked immunosorbent assay and the mRNA levels in peripheral blood were assessed using reverse transcriptase quantitative PCR. The expression and distribution of S100A8, S100A9, and receptor for advanced glycation end products (RAGE), in skin tissues was analyzed by immunohistochemistry. The plasma concentrations of S100A8 and S100A9 were significantly higher in dcSSc patients than in normal controls and lcSSc patients. Both S100A8 and S100A9 levels were significantly increased in dcSSc patients with lung or kidney involvement. Increased plasma levels of S100A8 and S100A9 in dcSSc patients were associated with several autoantibodies. Transcription levels of S100A8 and S100A9 in peripheral blood were found elevated in both dcSSc and lcSSc patients than normal controls. Immunohistochemistry demonstrated higher S100A8 and S100A9 expression in sclerotic skin than in normal skin. The number of S100A8, S100A9, or RAGE positive fibroblasts was also significantly increased. Highly elevated expression of both S100A8 and S100A9 was found in dcSSc patients. There was close correlation with disease severity and serological abnormalities, suggesting that the two proteins may play important roles in the development of systemic sclerosis.

Increased circulating soluble vascular adhesion protein-1 levels in systemic sclerosis: association with lower frequency and severity of interstitial lung disease

AIM

To determine circulating soluble vascular adhesion protein-1 (sVAP-1) levels and their clinical associations in patients with systemic sclerosis (SSc).

METHOD

Serum VAP-1 levels were examined by enzyme-linked immunosorbent assay in 71 SSc patients, 13 systemic lupus erythematosus patients and 50 healthy individuals.

RESULTS

Serum sVAP-1 levels were significantly elevated in SSc patients (617.2 ± 338.7 ng/mL) compared with healthy individuals (320.2 ± 144.2 ng/mL; P < 0.001) and patients with systemic lupus erythematosus (329.0 ± 176.1 ng/mL; P < 0.001). Among SSc patients, there were no differences in serum sVAP-1 levels between those with limited cutaneous SSc and those with diffuse cutaneous SSc. SSc patients with raised sVAP-1 levels had interstitial lung disease and decreased percent vital capacity less often than those with normal sVAP-1 levels. sVAP-1 levels were positively correlated with percent vital capacity in patients with SSc.

CONCLUSION

Serum sVAP-1 levels were increased in patients with SSc, and associated with a lower frequency and severity of interstitial lung disease in SSc, suggesting that sVAP-1 plays a role in the pathogenesis of interstitial lung disease in SSc.

Serum B-cell activating factor assessment in a population of Egyptian patients with systemic sclerosis

BACKGROUND

Systemic sclerosis (SSc) is a rare systemic connective tissue disease characterized by abnormal fibroblast proliferation and micro-vascular inflammatory changes.

AIM

To assess serum B-cell activating factor (BAFF) levels in patients with systemic sclerosis and to correlate this with disease features and disease severity.

METHODS

This is a case-control study in which patients with the established diagnosis of SSc were recruited. The diagnosis of SSc was established according to the American Rheumatology Association 1980 criteria for the classification of scleroderma. Patients' assessment included evaluation of skin involvement using the Modified Rodnan score and disease severity using the Medsger score. Twenty-five healthy matching controls were included. The sandwich enzyme-linked immunosorbent assay technique was used for direct assessment of serum BAFF in patients and controls.

RESULTS

The study included 60 patients (54 female and 6 male), with a mean age of 38.18 ± 12.06 years, with mean disease duration of 7.85 ± 4.075 years. Serum BAFF in patients ranged 98.2-5015 pg/mL with mean BAFF 1100 ± 835.4 pg/mL. In controls serum BAFF levels ranged 188.5-2314 pg/mL with mean BAFF 546.1 ± 471.1 pg/mL, showing a statistically significant elevation of serum BAFF levels in SSc patients (P = 0.0001) with insignificant correlation to skin disease or total Medsgar Score of the study population (P > 0.05). Serum BAFF levels showed significant correlation with episodes of pseudo-obstruction and methotrexate (MTX) use in the patients studied (P < 0.05).

CONCLUSION

Serum BAFF levels were significantly elevated in patients with SSc irrespective of disease subtype, disease duration or age of patients. This elevation in serum BAFF significantly related to gastrointestinal track involvement and MTX therapy.

Increased circulating fibrinogen-like protein 2 in patients with systemic sclerosis

Fibrinogen-like protein 2 (FGL2), a member of the fibrinogen-related superfamily of proteins, is expressed on the surface of macrophages, T cells, and endothelial cells and directly cleaves prothrombin to thrombin. The aim of this study is to determine the serum FGL2 level and its association with clinical parameters in patients with systemic sclerosis (SSc). Serum FGL2 level was examined by enzyme-linked immunosorbent assay in 61 patients with SSc, 24 patients with systemic lupus erythematosus, and 24 healthy individuals. In a retrospective longitudinal study, sera from 13 patients with SSc were analyzed. The serum FGL2 level was increased in patients with SSc compared with healthy individuals (P < 0.001) and patients with systemic lupus erythematosus (P < 0.01). Among patients with SSc, there were no differences in serum FGL2 level between limited cutaneous SSc and diffuse cutaneous SSc. In the longitudinal study, the FGL2 level was generally unchanged at follow-up. The results show that the serum FGL2 level was increased in patients with SSc but not in patients with systemic lupus erythematosus or healthy individuals. Therefore, FGL2 possibly contribute to the development of SSc.

Augmented production of soluble CD93 in patients with systemic sclerosis and clinical association with severity of skin sclerosis

BACKGROUND

The cell surface protein CD93, expressed on endothelial and myeloid cells, mediates phagocytosis, inflammation and cell adhesion. A soluble form of CD93 (sCD93) is released during inflammation.

OBJECTIVES

To determine the serum sCD93 level and its association with clinical parameters in patients with systemic sclerosis (SSc).

METHODS

Serum sCD93 levels were examined by enzyme-linked immunosorbent assay in 59 patients with SSc, 24 patients with systemic lupus erythematosus and 47 healthy individuals. The expression of CD93 in skin tissues was examined immunohistochemically. In a retrospective longitudinal study, sera from 11 patients with SSc were analysed.

RESULTS

Serum sCD93 levels were increased in patients with SSc compared with healthy individuals (P<0·001). Patients with diffuse cutaneous SSc showed greater levels of sCD93 than those with limited cutaneous SSc (P<0·01) or systemic lupus erythematosus (P<0·01). Serum sCD93 levels correlated positively with the severity of skin sclerosis. Strong CD93 immunostaining was observed on endothelial cells in lesional skin tissues. In the longitudinal study, sCD93 levels decreased in parallel with improvement in skin sclerosis.

CONCLUSIONS

Serum sCD93 levels are increased in patients with SSc and correlate with the severity and activity of skin sclerosis. CD93 may contribute to the development of skin fibrosis in SSc.

Increased serum levels of soluble CD163 in patients with scleroderma

CD163 is a 130-kDa, type I transmembrane protein belonging to group B of the cysteine-rich scavenger receptor family. Expression of CD163 is constitutive and/or induced by some stimuli on circulating monocytes and most tissue macrophages. An approximately 130-kDa soluble form of human CD163 is released from the cell surface by proteolysis after oxidative stress or inflammatory stimuli. Thus, an elevated level of circulating soluble CD163 (sCD163) has been reported in diabetes mellitus, which is one of the oxidative conditions. We have already acknowledged that scleroderma (SSc) is one of the oxidative conditions. Therefore, we conducted the measurement of serum sCD163 in SSc patients. After receiving the informed consents, 56 SSc patients were examined; 20 dermatomyositis patients were used as disease controls and 40 persons were used as healthy controls. Blood samples were collected, and the concentration of serum sCD163 was measured by ELISA (human CD163, R&D Systems). Other parameters in the blood of SSc patients were also examined. Statistical analyses were performed using Mann-Whitney U test, and the relationship between parameters was statistically examined by Spearman's rank test. Serum sCD163 levels were elevated in SSc patients compared with normal controls (p < 0.01), with similar levels between limited SSc and diffuse SSc patients. SSc patients with pulmonary fibrosis had increased serum levels of sCD163 than those without pulmonary fibrosis (p < 0.05). SSc patients with elevated sCD163 levels had increased serum levels of IgG than those with normal sCD163 levels (p < 0.05). Serum sCD163 levels correlated positively with pulsatility index in SSc patients (p = 0.0009, r = 0.534). These results suggest that oxidative stress may play an important role in immunological abnormalities, renal circulation, and pulmonary fibrosis of SSc.

A possible contribution of altered cathepsin B expression to the development of skin sclerosis and vasculopathy in systemic sclerosis

Cathepsin B (CTSB) is a proteolytic enzyme potentially modulating angiogenic processes and extracellular matrix remodeling. While matrix metalloproteinases are shown to be implicated in tissue fibrosis and vasculopathy associated with systemic sclerosis (SSc), the role of cathepsins in this disease has not been well studied. The aim of this study is to evaluate the roles of CTSB in SSc. Serum pro-CTSB levels were determined by enzyme-linked immunosorbent assay in 55 SSc patients and 19 normal controls. Since the deficiency of transcription factor Fli1 in endothelial cells is potentially associated with the development of SSc vasculopathy, cutaneous CTSB expression was evaluated by immunostaining in Fli1^+/− and wild type mice as well as in SSc and control subjects. The effects of Fli1 gene silencing and transforming growth factor-β (TGF-β) on CTSB expression were determined by real-time PCR in human dermal microvascular endothelial cells (HDMECs) and dermal fibroblasts, respectively. Serum pro-CTSB levels were significantly higher in limited cutaneous SSc (lcSSc) and late-stage diffuse cutaneous SSc (dcSSc) patients than in healthy controls. In dcSSc, patients with increased serum pro-CTSB levels showed a significantly higher frequency of digital ulcers than those with normal levels. CTSB expression in dermal blood vessels was increased in Fli1^+/− mice compared with wild type mice and in SSc patients compared with healthy controls. Consistently, Fli1 gene silencing increased CTSB expression in HDMECs. In cultured dermal fibroblasts from early dcSSc, CTSB expression was decreased compared with normal fibroblasts and significantly reversed by TGF-β1 antisense oligonucleotide. In conclusion, up-regulation of endothelial CTSB due to Fli1 deficiency may contribute to the development of SSc vasculopathy, especially digital ulcers, while reduced expression of CTSB in lesional dermal fibroblasts is likely to be associated with skin sclerosis in early dcSSc.

Serum Levels of Galectin-3: Possible Association with Fibrosis, Aberrant Angiogenesis, and Immune Activation in Patients with Systemic Sclerosis

Objective.

Galectin-3 is a multifunctional protein implicated in a variety of biological processes including fibrosis, angiogenesis, and immune activation, all of which are associated with the development of systemic sclerosis (SSc). We investigated the clinical significance of serum galectin-3 levels in SSc.

Methods.

Serum galectin-3 levels were determined by a specific ELISA in 58 patients with SSc and 19 healthy controls.

Results.

Serum galectin-3 levels were significantly lower in patients with diffuse cutaneous SSc (dcSSc) than in controls (3.29 ± 3.27 ng/ml vs 4.91 ± 2.67 ng/ml, respectively; p < 0.05), while being comparable between limited cutaneous SSc (3.70 ± 2.39 ng/ml) and healthy controls. In dcSSc, serum galectin-3 levels significantly correlated with total skin score (r = 0.45, p < 0.05). Serum galectin-3 levels were significantly decreased in early dcSSc (disease duration < 1 year; 1.64 ± 1.74 ng/ml; p < 0.05), but not in mid-stage dcSSc (1 to 6 years; 3.22 ± 3.16 ng/ml) or late-stage dcSSc (> 6 years; 4.86 ± 4.10 ng/ml), compared with controls. Serum galectin-3 levels were higher in SSc patients with both digital ulcers (DU) and elevated right ventricular systolic pressure (RVSP) than in those without each symptom (DU: 5.44 ± 3.74 ng/ml vs 2.99 ± 2.36 ng/ml, p < 0.05; elevated RVSP: 4.44 ± 3.14 ng/ml vs 2.82 ± 2.64 ng/ml, p < 0.05).

Conclusion.

Galectin-3 may be related to the developmental process of skin sclerosis in dcSSc and of DU and pulmonary vascular involvements in total SSc.

Clinical significance of serum growth differentiation factor-15 levels in systemic sclerosis: association with disease severity

OBJECTIVE

To determine serum growth differentiation factor-15 (GDF-15) levels and their clinical associations in patients with systemic sclerosis (SSc).

METHODS

Serum GDF-15 levels were examined by enzyme-linked immunosorbent assay in 61 patients with SSc and 24 healthy individuals. In a retrospective longitudinal study, sera from 14 patients with SSc were analyzed (duration of follow-up 1.2-7.2 years).

RESULTS

Serum GDF-15 levels were significantly elevated in SSc patients (1340 ± 910 pg/ml) compared with healthy individuals (213 ± 79 pg/ml; P < 0.001). Among SSc patients, patients with diffuse cutaneous SSc (n = 31) had higher levels of serum GDF-15 (1609 ± 1069 pg/ml) than those with limited cutaneous SSc (n = 30; 1142 ± 646 pg/ml; P < 0.05). SSc patients with high GDF-15 levels (≥1000 pg/ml) had pulmonary fibrosis, decreased vital capacity, and decreased diffusion capacity for carbon monoxide more often than those with low GDF-15 levels (<1000 pg/ml). GDF-15 levels correlated positively with the extent of skin sclerosis and inversely with percentage vital capacity and diffusion capacity for carbon monoxide in patients with SSc. In a longitudinal study, serum GDF-15 levels were generally decreased during the follow-up.

CONCLUSION

Serum GDF-15 levels were increased in patients with SSc and associated with the extent of skin sclerosis and the severity of pulmonary fibrosis. These results suggest that GDF-15 may play a role in the development of cutaneous and pulmonary fibrosis in SSc. Measurement of serum GDF-15 may be useful for risk stratification in early disease stage.

Clinical significance of circulating platelet-activating factor acetylhydrolase levels in systemic sclerosis

Platelet-activating factor acetylhydrolase (PAF-AH) has been demonstrated to be one of anti-inflammatory and anti-apoptotic factors, suggesting the potential to be involved in the development of systemic sclerosis (SSc). The aim of this study is to determine serum PAF-AH levels and their clinical associations in patients with SSc. Serum PAF-AH levels were examined by enzyme-linked immunosorbent assay in 57 patients with SSc and 24 healthy individuals. Serum PAF-AH levels were significantly elevated in SSc patients (130.4 ± 69.5 ng/ml) compared with healthy individuals (81.6 ± 34.8 ng/ml; P < 0.001). Among SSc patients, there were no differences in serum PAF-AH levels between those with diffuse cutaneous SSc (135.5 ± 79.3 ng/ml; n = 29) and those with limited cutaneous SSc (125.1 ± 58.6 ng/ml; n = 28). Patients with SSc who had raised PAF-AH levels less often had digital ulcers and arthritis/arthralgias than those with normal PAF-AH levels. The results show that serum PAF-AH levels were increased in patients with SSc and associated with a lower frequency of pitting scars/digital ulcers and arthritis/arthralgias. PAF-AH could be a protective factor against the development of digital ulcers and arthritis/arthralgia in this disease and as such would be a useful serological marker for disease severity.

Serum interleukin 9 levels are increased in patients with systemic sclerosis: association with lower frequency and severity of pulmonary fibrosis

OBJECTIVE

To determine serum interleukin 9 (IL-9) levels and their clinical associations in patients with systemic sclerosis (SSc).

METHODS

Serum IL-9 levels were examined by ELISA in 71 patients with SSc, 15 with systemic lupus erythematosus (SLE), 15 with dermatomyositis (DM), 39 with atopic dermatitis, and 28 healthy individuals.

RESULTS

Serum IL-9 levels were significantly elevated in SSc patients (84.6 ± 76.0 pg/ml) compared with healthy individuals (40.4 ± 41.7 pg/ml; p < 0.001), and patients with SLE (50.7 ± 52.0 pg/ml; p < 0.05) or DM (50.6 ± 55.8 pg/ml; p < 0.05) or atopic dermatitis (41.8 ± 38.8 pg/ml; p < 0.001). Among SSc patients, there were no differences in serum IL-9 levels between those with limited cutaneous SSc and those with diffuse cutaneous SSc. Patients with SSc and raised IL-9 levels less often had pulmonary fibrosis and decreased percentage vital capacity than those with normal IL-9 levels. IL-9 levels were positively correlated with percentage vital capacity in patients with SSc.

CONCLUSION

Serum IL-9 level was increased in patients with SSc, and was associated with lower frequency and severity of pulmonary fibrosis in SSc. IL-9 could be a protective factor against the development of pulmonary fibrosis in this disease, and as such would be a possible therapeutic target.

Prevalence of anti-histone antibodies, their clinical significance and correlation with other autoantibodies in a cohort of Italian scleroderma patients

Purpose

The aim of our study was to determine the prevalence, clinical significance of antibodies to individual histone components and to evaluate their correlation with other autoantibody specificities in a cohort of Italian SSc patients. Some authors, demonstrated high prevalence of anti-histone antibodies in Italian SSc patients, associated with cardiac and renal involvement, suggesting a prognostic value of these autoantibodies; however, these data need to be confirmed.

Methods

Serum from 112 adult SSc patients, classified as diffuse (dc) and limited cutaneous (lc) SSc subsets were analyzed for autoantibodies by indirect immunofluorescence, fluoroenzyme immunoassay and enzyme immunoassay.

Results

AHA were found in 13 patients (11.6%), nine with lcSSc and four with dcSSc. Among them, five patients were anti-Scl70+ and four were anti-CENP B+. The presence of AHA was not associated with multi-organ involvement or with diffuse subset, as already described. Anti-Scl70 was detected in 43% of patients, anti-CENP B in 32% and anti-RNA polymerase III in 7.1%. We confirmed the association between anti-Scl70 antibodies and pulmonary fibrosis (OR 15.75, p < 0.0001).

Conclusion

In our experience, the very low prevalence of AHA in Italian SSc patients and the lack of association with clinical manifestations suggest that this test is of little clinical use; however, it would be worthwhile extending the study to a larger population of patients.

Increasing levels of serum antioxidant status, total antioxidant power, in systemic sclerosis

Oxidative stress is one of the important factors that contribute to tissue damage in systemic sclerosis (SSc). Since the physiological response to oxidative stress is regulated by multiple antioxidant systems, it is important to measure quantitatively the total antioxidant capacity in the biological specimens. To determine the clinical significance of total antioxidant power (TAP) in SSc, we investigated the prevalence and clinical correlation of serum TAP levels in SSc patients. Serum TAP levels were examined in 49 patients with SSc by colorimetric microplate assay. The assay measures the total abilities for reducing Cu++ into Cu+. Clinical evaluation including medical history, physical examination, and laboratory tests were conducted for all SSc patients. Serum TAP levels were significantly elevated in SSc patients compared to normal controls (p < 0.01). When values higher than the mean + 2SD of the control serum samples were considered to be elevated, TAP levels were elevated in 24% of total SSc patients, with 26% of diffuse cutaneous SSc patients and 23% of limited cutaneous SSc patients. Serum TAP levels were correlated positively with C-reacting protein (r = 0.35, p ≤ 0.05). However, no other significant correlation was observed between serum TAP levels and clinical features in SSc patients. These results suggested that oxidative stress is enhanced in SSc patients, and serum TAP levels increase as an indicator of the global response to oxidative stress.

Serum IL-33 levels are raised in patients with systemic sclerosis: association with extent of skin sclerosis and severity of pulmonary fibrosis

To determine serum interleukin-33 (IL-33) levels and their associations with clinical parameters in patients with systemic sclerosis (SSc). Serum IL-33 levels were examined by enzyme-linked immunosorbent assay in 69 patients with SSc and 30 healthy individuals. In a retrospective longitudinal study, sera from 14 patients with SSc were analyzed (follow-up, 1-7 years). Serum IL-33 levels were elevated in SSc patients (261.7 ± 141.9 pg/ml) compared with healthy individuals (174.9 ± 72.4 pg/ml; P < 0.001). Patients with diffuse cutaneous SSc had higher levels of IL-33 (287.5 ± 146.6 pg/ml) than those with limited cutaneous SSc (221.5 ± 126.5 pg/ml; P < 0.05). Pulmonary fibrosis and decreased forced vital capacity were more commonly found in patients with elevated IL-33 levels than in those with normal IL-33 levels. IL-33 levels correlated positively with the extent of skin sclerosis, and inversely with percent predicted forced vital capacity. IL-33 levels were increased in SSc patients and correlated with the extent of skin sclerosis and the severity of pulmonary fibrosis. Therefore, IL-33 possibly plays a role in cutaneous and pulmonary fibrosis in SSc patients.

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

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

Serum CCL23 levels are increased in patients with systemic sclerosis

The aim of this study is to determine serum CCL23 levels and their clinical associations in patients with systemic sclerosis (SSc). Serum CCL23 levels were examined by ELISA in 66 patients with SSc, 20 patients with systemic lupus erythematosus, 20 patients with dermatomyositis, and 33 healthy individuals. Serum CCL23 levels were elevated in SSc patients (389.1 ± 199.2 pg/mL) compared with healthy individuals (94.1 ± 85.6 pg/mL; P < 0.001) and patients with systemic lupus erythematosus (43.4 ± 39.3 pg/mL; P < 0.001) or dermatomyositis (132.1 ± 104.5 pg/mL; P < 0.001). Among SSc patients, there were no differences in serum CCL23 levels between those with limited cutaneous SSc and those with diffuse cutaneous SSc. SSc patients with elevated CCL23 levels were found to have shorter disease duration than those with normal CCL23 levels (P < 0.001). Furthermore, raised CCL23 levels were associated with a higher frequency of pulmonary arterial hypertension (P < 0.05). The results show that serum CCL23 level was increased in the early phase of SSc. CCL23 could be associated with induction of SSc and as such would be a serologically useful marker for disease activity.

Autoantibody Against Survivin in Patients with Systemic Sclerosis

Objective.

In patients with systemic sclerosis (SSc), to determine concentrations of antibodies against survivin and their clinical association with SSc, and to evaluate serum survivin concentrations.

Methods.

Anti-survivin antibody was examined by ELISA and immunoblotting using human recombinant survivin. Serum survivin levels were assessed by ELISA.

Results.

IgG but not IgM anti-survivin antibody levels in patients with SSc were significantly higher than those in healthy controls and patients with systemic lupus erythematosus (SLE). When cutoff values were set as mean + 2 SD of control, IgG anti-survivin antibodies were positive in 41% (25/61) of patients with SSc, while they were detected in only 1 healthy individual (3%, 1/29) and 1 patient with SLE (5%, 1/20). Regarding the clinical correlation, patients with SSc who were positive for IgG anti-survivin antibody exhibited significantly longer disease duration than those who were negative. Immunoblotting analysis confirmed the presence of anti-survivin antibody in sera from patients with SSc. Serum survivin levels in patients with SSc were also significantly higher than in controls and patients with SLE.

Conclusion.

Our results suggest that autoantibody against survivin is generated in patients with SSc, especially those with long disease duration.

Autoantibody against one of the antioxidant repair enzymes, methionine sulfoxide reductase A, in systemic sclerosis: association with pulmonary fibrosis and vascular damage

Systemic sclerosis (SSc) is a connective tissue disease characterized by fibrosis and vascular changes in the skin and internal organs with autoimmune background. It has been suggested that oxidative stress plays an important role in the development of SSc. To determine the prevalence and clinical correlation of autoantibody to methionine sulfoxide reductase A (MSRA), one of the antioxidant repair enzymes, in SSc, serum anti-MSRA autoantibody levels were examined in patients with SSc by enzyme-linked immunosorbent assay using recombinant MSRA. The presence of anti-MSRA antibody was evaluated by immunoblotting. To determine the functional relevance of anti-MSRA antibody in vivo, we assessed whether anti-MSRA antibody was able to inhibit MSRA enzymatic activity. Serum anti-MSRA antibody levels in SSc patients were significantly higher compared to controls and this autoantibody was detected in 33% of SSc patients. Serum anti-MSRA levels were significantly elevated in SSc patients with pulmonary fibrosis, cardiac involvement, or decreased total antioxidant power compared with those without them. Anti-MSRA antibodies also correlated positively with renal vascular damage determined as pulsatility index by color-flow Doppler ultrasonography of the renal interlobar arteries and negatively with pulmonary function tests. Furthermore, anti-MSRA antibody levels correlated positively with serum levels of 8-isoprostane and heat shock protein 70 that are markers of oxidative and cellular stresses. Remarkably, MSRA activity was inhibited by IgG isolated from SSc sera containing IgG anti-MSRA antibody. These results suggest that elevated anti-MSRA autoantibody is associated with the disease severity of SSc and may enhance the oxidative stress by inhibiting MSRA enzymatic activity.

Serum CXCL16 Concentrations Correlate with the Extent of Skin Sclerosis in Patients with Systemic Sclerosis

Objective.

To determine serum concentrations of soluble CXCL16 and its clinical associations in patients with systemic sclerosis (SSc).

Methods.

Serum CXCL16 levels from 89 patients with SSc were examined by ELISA. In a retrospective longitudinal study, 68 sera from 28 patients with SSc were analyzed (followup 1.3 to 7.3 yrs).

Results.

Serum CXCL16 levels were elevated in patients with SSc compared with healthy controls (n = 42). Patients with diffuse cutaneous SSc (n = 52) had higher levels of CXCL16 than those with limited cutaneous SSc (n = 37). Serum CXCL16 levels correlated positively with the extent of skin sclerosis. In the longitudinal study, CXCL16 levels generally decreased on a parallel with the improvement in skin sclerosis.

Conclusion.

CXCL16 levels were increased in patients with SSc, and correlated with the extent of skin sclerosis, suggesting that CXCL16 may have a role in the development of skin fibrosis in SSc. Blockade of CXCL16 interaction might be a potential therapeutic target in patients with SSc.

Elevated Circulating TWEAK Levels in Systemic Sclerosis: Association with Lower Frequency of Pulmonary Fibrosis

Objective.

To determine serum levels of tumor necrosis factor-related weak inducer of apoptosis (TWEAK) and its clinical associations in patients with systemic sclerosis (SSc).

Methods.

Serum TWEAK levels from 70 patients with SSc were examined by ELISA. In a retrospective longitudinal study, sera from 23 patients with SSc were analyzed (followup 0.8–7.2 yrs).

Results.

Serum TWEAK levels were elevated in patients with SSc (n = 70) compared with healthy controls (n = 31) and patients with systemic lupus erythematosus (n = 22). Among patients with SSc, there were no differences in serum TWEAK levels between limited cutaneous SSc and diffuse cutaneous SSc. Patients with SSc who had elevated TWEAK levels less often had pulmonary fibrosis and decreased vital capacity than those with normal TWEAK levels. In the longitudinal study, SSc patients with inactive pulmonary fibrosis or without pulmonary fibrosis consistently exhibited increased TWEAK levels, while those with active pulmonary fibrosis showed decreased TWEAK levels during the followup period.

Conclusion.

TWEAK levels were increased in patients with SSc, and associated with a lower frequency of pulmonary fibrosis in patients with SSc. TWEAK could be a protective factor against the development of pulmonary fibrosis in this disease and as such would be a possible therapeutic target.

Anti-chromatin and anti-histone antibodies in Egyptian patients with systemic lupus erythematosus

There has been a renewed interest in anti-chromatin and anti-histone antibodies in the last few years. To assess the prevalence of anti-chromatin and anti-histone antibodies in patients with systematic lupus erythematosus (SLE) and to correlate serum levels of these antibodies with clinical features of the disease, the presence of anti-chromatin and anti-histone antibodies in 38 patients with SLE was investigated by an enzyme-linked immunosorbent assay (ELISA). To determine the specificity of these antibodies, 15 patients with rheumatoid arthritis, 15 patients with systemic sclerosis, and 15 normal controls were also tested. Sensitivity of anti-chromatin antibodies in SLE patients was 89.5% and specificity was 80.0%, while sensitivity of anti-histone antibodies was 92.1% and specificity was 82.2%. Significant associations were found between the levels of anti-chromatin antibodies and arthritis, malar rash, oral ulcer, pulmonary affection (P < 0.05) also, lupus nephritis (P < 0.01), and disease activity score as measured by SLE disease activity index (SLEDAI; P < 0.001). Significant association was found between anti-histone antibodies and fatigue (P < 0.05). The incidence of positive anti-chromatin and anti-histone antibodies was significantly higher than that of anti-dsDNA antibodies in early stage of the disease. We conclude that anti-chromatin and anti-histone antibodies are both sensitive and specific for SLE and could be a useful addition to the laboratory tests that can help in the diagnosis of SLE. Anti-chromatin antibodies seem to be a promising marker useful in early diagnosis and assessment of disease activity in SLE patients especially in patients who are negative for anti-dsDNA antibodies.

Increased Serum Pentraxin 3 in Patients with Systemic Sclerosis

Objective.

To determine serum concentrations of pentraxin 3 (PTX3) and its clinical associations in patients with systemic sclerosis (SSc).

Methods.

Serum PTX3 levels from 45 patients with diffuse cutaneous SSc (dSSc), 46 with limited cutaneous SSc (lSSc), and 20 healthy controls were examined by ELISA. PTX3 expression in the sclerotic skin from SSc patients was evaluated immunohistochemically. Normal and SSc fibroblasts were cultured and PTX3 levels in the culture medium were also examined by ELISA.

Results.

Serum PTX3 levels were elevated in patients with SSc relative to controls. PTX3 levels in dSSc patients were significantly higher than in controls and lSSc patients. PTX3 expression in the sclerotic skin from SSc patients was more intense relative to normal skin. Elevation of serum PTX3 levels was associated with more frequent presence of pulmonary fibrosis, cardiac disease, and pitting scar/ulcer and increased serum immunoglobulin levels and erythrocyte sedimentation rates. PTX3 levels correlated positively with modified Rodnan total skin thickness score, and negatively with percentage vital capacity and percentage DLCO in patients with SSc. PTX3 levels also correlated positively with serum levels of 8-isoprostane, a marker of oxidative stress, and hyaluronan, recently identified as an endogenous ligand for Toll-like receptors. PTX3 production from cultured SSc fibroblasts was increased by stimulation with hyaluronan.

Conclusion

These results suggest that elevated serum PTX3 levels are associated with the disease severity of SSc.

Clinical significance of serum HMGB-1 and sRAGE levels in systemic sclerosis: association with disease severity

INTRODUCTION

The high mobility group box 1 protein (HMGB-1)/advanced glycation end products (RAGE) system is recently shown to play an important part in immune/inflammatory disorders. However, the association of this system in systemic sclerosis (SSc) remains unknown.

MATERIALS AND METHODS

To determine clinical association of serum levels of HMGB-1 and soluble RAGE (sRAGE) in patients with SSc, sera from 70 patients with SSc and 25 healthy controls were examined by enzyme-linked immunosorbent assay. Sera from tight-skin mice and bleomycin-induced scleroderma mice, animal models for SSc, were also examined. Skin HMGB-1 and RAGE expression was assessed by immunohistochemistry.

RESULTS AND DISCUSSION

Serum HMGB-1 and sRAGE levels in SSc were higher than those in controls. Similarly, HMGB-1 and sRAGE levels in animal SSc models were higher than those in control mice. SSc patients with elevated HMGB-1 and sRAGE levels had more frequent involvement of several organs and immunological abnormalities compared to those with normal levels. Furthermore, HMGB-1 and sRAGE levels correlated positively with modified Rodnan total skin thickness score and negatively with pulmonary function test.

CONCLUSIONS

HMGB-1 and sRAGE expression in the sclerotic skin was more intense than normal skin. These results suggest that elevated serum HMGB-1 and sRAGE levels are associated with the disease severity and immunological abnormalities in SSc.

The clinical relevance of serum antinuclear antibodies in Japanese patients with systemic sclerosis

Background

Systemic sclerosis (SSc) is a connective tissue disorder with excessive fibrosis of the skin and various internal organs. Although SSc is a heterogeneous disease, it has been reported that the particular antinuclear antibodies (ANA) are often indicative of clinical features, disease course and overall severity.

Objective

To clarify the association of clinical and prognostic features with serum ANA in Japanese patients with SSc.

Methods

We studied 203 Japanese patients diagnosed with SSc, who visited our hospital during the period 1983–2005. Six SSc-related ANA were identified using indirect immunofluorescence, double immunodiffusion and immunoprecipitation assays.

Results

Patients with SSc were classified into six ANA-based subgroups and a group without ANA. As expected, antitopoisomerase I antibody (Ab, n = 64), anti-RNA polymerases (RNAP) Ab (n = 12) and anti-U3 RNP Ab (n = 5) were associated with diffuse cutaneous SSc, whereas anticentromere Ab (ACA, n = 75), anti-Th/To Ab (n = 7) and anti-U1 RNP Ab (n = 10) were frequently detected in patients with limited cutaneous SSc. Clinical features of the ANA-negative group (n = 10) were heterogeneous. Consistent with previous findings in Caucasian and/or black African patients, antitopoisomerase I Ab was associated with the involvement of vascular and pulmonary fibrosis, leading to decreased survival rate. However, no patients with anti-RNAP Ab developed renal crisis and the frequency of isolated pulmonary hypertension in patients with ACA, anti-Th/To Ab or anti-U3 RNP Ab was similar to that in other ANA-based subgroups.

Conclusion

These results indicate that the clinical relevance of SSc-related ANA in Japanese patients differs in some aspects from that in Caucasian and/or black African patients.