Background Plasmacytoid dendritic cells have been implicated in the pathogenesis of systemic sclerosis through mechanisms beyond the previously suggested production of type I interferon. Methods We isolated plasmacytoid dendritic cells from healthy persons and from patients with systemic sclerosis who had distinct clinical phenotypes. We then performed proteome-wide analysis and validated these observations in five large cohorts of patients with systemic sclerosis. Next, we compared the results with those in patients with systemic lupus erythematosus, ankylosing spondylitis, and hepatic fibrosis. We correlated plasma levels of CXCL4 protein with features of systemic sclerosis and studied the direct effects of CXCL4 in vitro and in vivo. Results Proteome-wide analysis and validation showed that CXCL4 is the predominant protein secreted by plasmacytoid dendritic cells in systemic sclerosis, both in circulation and in skin. The mean (±SD) level of CXCL4 in patients with systemic sclerosis was 25,624±2652 pg per milliliter, which was significantly higher than the level in controls (92.5±77.9 pg per milliliter) and than the level in patients with systemic lupus erythematosus (1346±1011 pg per milliliter), ankylosing spondylitis (1368±1162 pg per milliliter), or liver fibrosis (1668±1263 pg per milliliter). CXCL4 levels correlated with skin and lung fibrosis and with pulmonary arterial hypertension. Among chemokines, only CXCL4 predicted the risk and progression of systemic sclerosis. In vitro, CXCL4 downregulated expression of transcription factor FLI1, induced markers of endothelial-cell activation, and potentiated responses of toll-like receptors. In vivo, CXCL4 induced the influx of inflammatory cells and skin transcriptome changes, as in systemic sclerosis. Conclusions Levels of CXCL4 were elevated in patients with systemic sclerosis and correlated with the presence and progression of complications, such as lung fibrosis and pulmonary arterial hypertension. (Funded by the Dutch Arthritis Association and others.)

Systemic sclerosis (SSc) is an autoimmune disease characterized by fibrosis of the skin and internal organs that leads to profound disability and premature death. To identify novel SSc susceptibility loci we conducted the first genome wide association study (GWAS) in a population of Caucasian ancestry including a total of 2296 SSc patients and 5171 controls. Analysis of 279,621 autosomal single nucleotide polymorphisms (SNPs) followed by replication testing in an independent case-control set of European ancestry (2,753 SSc patients / 4,569 controls) identified a new susceptibility locus for systemic sclerosis at CD247 (1q22-23; rs2056626, P = 2.09 × 10−7 in the discovery samples, P = 3.39 × 10−9 in the combined analysis). Additionally, we confirm and firmly establish the role of MHC (2.31 × 10−18), IRF5 (P =1.86 × 10−13) and STAT4 (P =3.37 × 10−9) gene regions as SSc genetic risk factors.

The Sm proteins B/B, D1, D2, D3, E, F, and G are components of the small nuclear ribonucleoproteins U1, U2, U4/U6, and U5 that are essential for the splicing of pre-mRNAs in eukaryotes. D1 and D3 are among the most common antigens recognized by anti-Sm autoantibodies, an autoantibody population found exclusively in patients afflicted with systemic lupus erythematosus. Here we demonstrate by protein sequencing and mass spectrometry that all arginines in the C-terminal arginine-glycine (RG) dipeptide repeats of the human Sm proteins D1 and D3, isolated from HeLa small nuclear ribonucleoproteins, contain symmetrical dimethylarginines (sDMAs), a posttranslational modification thus far only identified in the myelin basic protein. The further finding that human D1 individually overexpressed in baculovirus-infected insect cells contains asymmetrical dimethylarginines suggests that the symmetrical dimethylation of the RG repeats in D1 and D3 is dependent on the assembly status of D1 and D3. In antibody binding studies, 10 of 11 anti-Sm patient sera tested, as well as the monoclonal antibody Y12, reacted with a chemically synthesized C-terminal peptide of D1 containing sDMA, but not with peptides containing asymmetrically modified or nonmodified arginines. These results thus demonstrate that the sDMA-modified C terminus of D1 forms a major linear epitope for anti-Sm autoantibodies and Y12 and further suggest that posttranslational modifications of Sm proteins play a role in the etiology of systemic lupus erythematosus.

Objective. To confirm in a placebo-controlled trial the safety and efficacy profile of infliximab in shortterm treatment of patients with active spondylarthropathy (SpA).Methods. Forty patients with active SpA were randomly assigned to receive an intravenous loading dose (weeks 0, 2, and 6) of 5 mg/kg infliximab or placebo. Evaluations for efficacy and safety were performed at weeks 1, 2, 6, 8, and 12. The primary end points of this study were the improvements in patient and physician global assessments of disease activity on a 100-mm visual analog scale.Results. Both primary end points improved significantly in the infliximab group compared with the baseline value, with no improvement in the placebo group. As early as week 2 and sustained up to week 12, there was a highly statistically significant difference between the values for these 2 end points in the infliximab versus the placebo group. In most of the other assessments of disease activity (laboratory measures, assessments of specific peripheral and/or axial disease), significant improvements were observed in the infliximab group compared with the baseline value and compared with placebo. Minor adverse events not causing discontinuation were equally observed in both treatment groups. There was one severe drug-related adverse event, in which a patient developed disseminated tuberculosis.Conclusion. Tumor necrosis factor ␣ blockade with infliximab in patients with active SpA was well tolerated and resulted in significant clinical and laboratory improvements in this short-term, placebocontrolled study. However, the occurrence of tuberculosis in one patient necessitates strict inclusion criteria and long-term followup.

Objectives-To compare the macroscopic and microscopic characteristics of synovial tissue in rheumatoid arthritis (RA), spondyloarthropathy (SpA), and osteoarthritis (OA) after exclusion of possible biases induced by disease duration or activity, or both. Methods-Synovial biopsy specimens were obtained by needle arthroscopy in patients with early RA (n=16), late RA (n=14), early SpA (n=23), and OA (n=12). Macroscopic and microscopic features were scored on a four point scale and analysed as a function of disease duration (early versus late RA), local and systemic disease activity, and diagnosis. Results-Except for the maximal synovial lining thickness, no significant diVerences were seen between early and late RA. For disease activity, synovial histology was only weakly correlated with C reactive protein in RA, but seemed to be strongly dependent on eVusion of the biopsied joint in all disease groups. After stratification for local disease activity, no disease related diVerences were found in patients without joint eVusion. In contrast, important diVerences were found between patients with RA and SpA with active joint eVusion. Synovial vascularity was macroscopically increased in SpA versus RA (p=0.017). A straight vessel pattern was only seen in RA, while tortuous vessels were preferentially seen in SpA. Vascularity was also microscopically increased in SpA compared with RA (p=0.031), and correlated with the macroscopic vascularity (r s =0.36, p=0.036). CD3+ (p=0.008), CD4+ (p=0.008), and CD20+ (p=0.024) lymphocytes were overrepresented in RA compared with SpA. The integrin expression in RA was characterised by a decrease of V 3 in the synovial lining (p=0.006) and an increase of V 5 in the sublining (p<0.001). Conclusions-The immune architecture of the synovial membrane is more dependent on local disease activity than on disease duration. Synovium obtained from clinically aVected joints shows important histological diVerences between RA and SpA.(Ann Rheum Dis 2000;59:945-953)