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Abstract Introduction Primary Sjögren's syndrome (pSS) is a chronic autoimmune disease with complex etiopathogenesis. Despite extensive studies to understand the disease process utilizing human and mouse models, the intersection between these species remains elusive. To address this gap, we utilized a novel systems biology approach to identify disease-related gene modules and signaling pathways that overlap between humans and mice. Methods Parotid gland tissues were harvested from 24 pSS and 16 non-pSS sicca patients and 25 controls. For mouse studies, salivary glands were harvested from C57BL/6.NOD-Aec1Aec2 mice at various times during development of pSS-like disease. RNA was analyzed with Affymetrix HG U133+2.0 arrays for human samples and with MOE430+2.0 arrays for mouse samples. The images were processed with Affymetrix software. Weighted-gene co-expression network analysis was used to identify disease-related and functional pathways. Results Nineteen co-expression modules were identified in human parotid tissue, of which four were significantly upregulated and three were downregulated in pSS patients compared with non-pSS sicca patients and controls. Notably, one of the human disease-related modules was highly preserved in the mouse model, and was enriched with genes involved in immune and inflammatory responses. Further comparison between these two species led to the identification of genes associated with leukocyte recruitment and germinal center formation. Conclusion Our systems biology analysis of genome-wide expression data from salivary gland tissue of pSS patients and from a pSS mouse model identified common dysregulated biological pathways and molecular targets underlying critical molecular alterations in pSS pathogenesis.

Abstract Background Macrophages expressing the pro-angiogenic transcription factor hypoxia-inducible factor (HIF)-1alpha have been demonstrated in rheumatoid arthritis (RA) in the synovial tissue. Aim of the present study was to investigate intracellular signal transduction regulation of pro-inflammatory HIF-1 alpha expression in macrophages to identify possible new intervention strategies. We investigated the effects of CaMKII-inhibitors amongst other kinase inhibitors, on HIF-1 alpha expression and downstream production of pro-angiogenic factors in macrophages. Methods Differentiated THP-1 cells and synovial fluid (SF) macrophages were stimulated with 1 μg/ml LPS with or without pretreatment with specific inhibitors of the ERK pathway (PD98059), the PI3K pathway (LY294002), and the CaMKII pathway (KN93 and SMP-114). mRNA and protein expression of HIF-1 alpha, VEGF, MMP-9, and IL-8 was measured in cell lysates and cell supernatants. Results HIF-1 alpha protein expression in LPS-stimulated THP-1 macrophages could be blocked by ERK- and PI3K-inhibitors, but also by the CaMKII inhibitor KN93. THP-1 and SF macrophages produced high levels of VEGF, IL-8, and MMP-9, and VEGF protein production was significantly inhibited by PI3K-inhibitor, and by both CaMKII inhibitors. LPS stimulation in an hypoxic environment did not change VEGF levels, suggesting that LPS induced VEGF production in macrophages is more important than the hypoxic induction. Conclusions Expression of HIF-1 alpha and downstream effects in macrophages are regulated by ERK-, PI3K, but also by CaMKII pathways. Inhibition of HIF-1α protein expression and significant inhibition of VEGF production in macrophages was found using CaMKII inhibitors. This is an unknown but very interesting effect of the CaMKII inhibitor SMP-114, which has been in clinical trial as DMARD for the treatment of RA. This effect may contribute to the anti-arthritic effects of SMP-114.

When measured serially by Farr assay at a frequency of approximately once a month, changes in levels of anti-dsDNA appear to be a good predictor of clinical disease activity. Although the role of antibodies to the RNA component of snRNP awaits further studies, measurement of anti-UsnRNP antibody levels seems to be of limited value in monitoring lupus patients in clinical practice. The same holds for antibodies to SSA (Ro) and anti-histone antibodies. More recently described antibodies to C1q are probably useful in the follow-up of SLE patients suspected of proliferative renal involvement. The best alternative to measuring levels of the antibodies mentioned before is probably serial analysis of activation of the complement cascade. Levels of complement factors like C3, C4 and, functionally, CH50 remain a useful parameter for monitoring disease activity in SLE, although fluctuations in anti-dsDNA as measured by Farr assay seem superior with respect to sensitivity and specificity for an ensuing relapse. Despite the problems in sampling, measuring levels of activated split products of complement factors like C3a, C3d or C5a may prove to be a valuable tool in the follow-up of lupus patients. The involvement of the endothelial surface is illustrated by rising sVCAM-1 levels prior to relapses in SLE. Although one could expect that subsequent inflammation should be reflected by increased levels of inflammatory molecules like CRP and IL-6, the use of these molecules as predictors of lupus activity seems limited. Interferon-α as a direct reflector of the effector phase seems, however, rather promising in this respect and awaits longitudinal studies to analyse the possible relation with clinical disease activity and other serological parameters. [ABSTRACT FROM PUBLISHER]

The article reports on results of a study of the mechanism behind pauci-immune small-vessel vasculitides. The study showed that infection with a Gram-negative bacterium such as Escherichia coli may trigger disease in susceptible individuals by inducing the production of antibodies to a human protein expressed on neutrophils, lysosomal membrane protein-2.

BACKGROUNDLittle is known about the autoreactive B cells in antineutrophil cytoplasmic antibody-associated (ANCA-associated) vasculitis (AAV). We aimed to investigate tolerance checkpoints of circulating antigen-specific proteinase 3-reactive (PR3+) B cells.METHODSMulticolor flow cytometry in combination with bioinformatics and functional in vitro studies were performed on baseline samples of PBMCs from 154 well-characterized participants of the RAVE trial (NCT00104299) with severely active PR3-AAV and myeloperoxidase-AAV (MPO-AAV) and 27 healthy controls (HCs). Clinical data and outcomes from the trial were correlated with PR3+ B cells (total and subsets).RESULTSThe frequency of PR3+ B cells among circulating B cells was higher in participants with PR3-AAV (4.77% median [IQR, 3.98%-6.01%]) than in participants with MPO-AAV (3.16% median [IQR, 2.51%-5.22%]) and participants with AAV compared with HCs (1.67% median [IQR, 1.27%-2.16%], P < 0.001 for all comparisons), implying a defective central tolerance checkpoint in patients with AAV. Only PBMCs from participants with PR3-AAV contained PR3+ B cells capable of secreting PR3-ANCA IgG in vitro, proving they were functionally distinct from those of participants with MPO-AAV and HCs. Unsupervised clustering identified subtle subsets of atypical autoreactive PR3+ memory B cells accumulating through the maturation process in patients with PR3-AAV. PR3+ B cells were enriched in the memory B cell compartment of participants with PR3-AAV and were associated with higher serum CXCL13 levels, suggesting an increased germinal center activity. PR3+ B cells correlated with systemic inflammation (C-reactive protein and erythrocyte sedimentation rate, P < 0.05) and complete remission (P < 0.001).CONCLUSIONThis study suggests the presence of defective central antigen-independent and peripheral antigen-dependent checkpoints in patients with PR3-AAV, elucidating the selection process of autoreactive B cells.Trial registrationClinicalTrials.gov NCT00104299.FundingThe Vasculitis Foundation, the National Institute of Allergy and Infectious Diseases of the NIH, and the Mayo Foundation for Education and Research.

BACKGROUNDBaseline expression of FCRL5, a marker of naive and memory B cells, was shown to predict response to rituximab (RTX) in rheumatoid arthritis. This study investigated baseline expression of FCRL5 as a potential biomarker of clinical response to RTX in granulomatosis with polyangiitis (GPA) and microscopic polyangiitis (MPA).METHODSA previously validated quantitative PCR-based (qPCR-based) platform was used to assess FCRL5 expression in patients with GPA/MPA (RAVE trial, NCT00104299).RESULTSBaseline FCRL5 expression was significantly higher in patients achieving complete remission (CR) at 6, 12, and 18 months, independent of other clinical and serological variables, among those randomized to RTX but not cyclophosphamide-azathioprine (CYC/AZA). Patients with baseline FCRL5 expression ≥ 0.01 expression units (termed FCRL5hi) exhibited significantly higher CR rates at 6, 12, and 18 months as compared with FCRL5lo subjects (84% versus 57% [P = 0.016], 68% versus 40% [P = 0.02], and 68% versus 29% [P = 0.0009], respectively).CONCLUSIONOur data taken together suggest that FCRL5 is a biomarker of B cell lineage associated with increased achievement and maintenance of complete remission among patients treated with RTX and warrant further investigation in a prospective manner.FUNDINGThe analysis for this study was funded by Genentech Inc.

Introduction: The aim of this study was to investigate the effect of three years of tumor necrosis factor-alpha (TNF-α) blocking therapy on bone turnover as well as to analyze the predictive value of early changes in bone turnover markers (BTM) for treatment discontinuation in patients with ankylosing spondylitis (AS)., Methods: This is a prospective cohort study of 111 consecutive AS outpatients who started TNF-α blocking therapy. Clinical assessments and BTM were assessed at baseline, three and six months, as well as at one, two, and three years. Z-scores of BTM were calculated to correct for age and gender. Bone mineral density (BMD) was assessed yearly., Results: After three years, 72 patients (65%) were still using their first TNF-α blocking agent. In these patients, TNF-α blocking therapy resulted in significantly increased bone-specific alkaline phosphatase, a marker of bone formation; decreased serum collagen-telopeptide (sCTX), a marker of bone resorption; and increased lumbar spine and hip BMD compared to baseline. Baseline to three months decrease in sCTX Z-score (HR: 0.394, 95% CI: 0.263 to 0.591), AS disease activity score (ASDAS; HR: 0.488, 95% CI: 0.317 to 0.752), and physician's global disease activity (HR: 0.739, 95% CI: 0.600 to 0.909) were independent inversely related predictors of time to treatment discontinuation because of inefficacy or intolerance. Early decrease in sCTX Z-score correlated significantly with good long-term response regarding disease activity, physical function and quality of life., Conclusions: Three years of TNF-α blocking therapy results in a bone turnover balance that favors bone formation, especially mineralization, in combination with continuous improvement of lumbar spine BMD. Early change in sCTX can serve as an objective measure in the evaluation of TNF-α blocking therapy in AS, in addition to the currently used more subjective measures.

Purpose of Review: This review focuses on recent advances in the diagnosis, pathogenesis and treatment of antineutrophil cytoplasmic autoantibody-associated small-vessel vasculitis., Recent Findings: Antineutrophil cytoplasmic autoantibodies are closely associated with Wegener's granulomatosis and microscopic polyangiitis. Within the Churg-Strauss syndrome, antineutrophil cytoplasmic autoantibodies, mostly directed towards myeloperoxidase, characterize patients with glomerulonephritis and small-vessel vasculitis. There is increasing evidence that myeloperoxidase-antineutrophil cytoplasmic autoantibodies are directly involved in the pathogenesis of necrotizing vasculitis. This is less clear for proteinase 3-antineutrophil cytoplasmic autoantibodies, markers for Wegener's granulomatosis. With respect to proteinase 3-antineutrophil cytoplasmic autoantibodies, complementary proteinase 3, a peptide translated from the antisense DNA strand of proteinase 3 and homologous to several microbial peptides, may be involved in induction of proteinase 3-antineutrophil cytoplasmic autoantibodies. Currently, various controlled trials have been initiated. Methotrexate has been shown to be effective for induction of remission in locoregional Wegener's granulomatosis. Other trials are underway., Summary: Apart from its diagnostic potential, antineutrophil cytoplasmic autoantibodies, particularly myeloperoxidase-antineutrophil cytoplasmic autoantibodies, are directly involved in the pathogenesis of the associated vasculitides. New treatment modalities, supposedly more efficacious and less toxic than daily oral cyclophosphamide, are being tested in randomized controlled trials.