Epigenetic alterations in Sjögren's syndrome patient saliva.

Epigenetic mechanisms have been implicated in the pathogenesis of Sjögren's syndrome (SS). Extensive alterations in DNA methylation have been described in minor salivary gland (MSG) epithelial cells and lymphocytes derived from SS patients compared to sicca controls. In an effort to identify novel potential epigenetic markers that could prove useful in diagnosis and disease monitoring, we explored whether DNA methylation differences can also be detected in saliva from SS patients compared to sicca controls. We performed DNA methylation analysis by methylation-sensitive restriction digestion followed by quantitative real-time polymerase chain reaction of selected genomic loci in saliva samples of 16 SS patients and 10 sicca controls with negative MSG biopsy. We identified reduced DNA methylation of the imprinting control region (ICR) of the H19 locus in SS patient saliva compared to sicca controls. Levels of saliva H19 ICR methylation were negatively correlated with C4 serum complement levels. Consistent with the reduced methylation of the ICR, H19 RNA levels were increased in SS patient peripheral blood mononuclear cells (PBMCs), while no significant change was observed in MSG H19 RNA levels compared to sicca controls. Our findings support that H19 ICR methylation could be a useful molecular epigenetic marker in monitoring patients with SS, highlighting saliva as a valuable biological sample in SS research and clinical practice. The role of H19 in SS pathogenesis remains to be addressed.

Fine specificity of anti-citrullinated peptide antibodies discloses a heterogeneous antibody population in rheumatoid arthritis.

Anti-citrullinated peptide antibodies (ACPA) are highly specific for rheumatoid arthritis (RA). However, the predominant B cell epitopes have not yet been defined. The aim of this study was to examine the reactivity of ACPA against different peptides derived from citrullinated proteins and to investigate whether or not these antibodies constitute a homogeneous population. For this purpose, sera from patients with RA (n = 141), systemic lupus erythematosus (SLE) (n = 60), Sjögren's syndrome (SS) (n = 54) and healthy controls (n = 100) were tested for their reactivity against six citrullinated peptides derived from peptidyl arginine deiminase (PAD), vimentin (vim), alpha-enolase (enol), fibrin, type II collagen (col-II) and filaggrin, respectively. A non-citrullinated control peptide derived from PAD was used as control (ctrlPAD(621-40)). Antibody reactivity against each individual peptide was evaluated by enzyme-linked immunosorbent assay (ELISA). Specificity and cross-reactivity of ACPA were tested by using two prototype sera with homologous and cross-inhibition assays. Specificity of ACPA from two prototype sera was confirmed by purification of anti-peptide antibodies and homologous-inhibition experiments. We found that sera from patients with RA reacted diversely with the six citrullinated peptides. More specifically, PAD(211-30) displayed 29·08% sensitivity, vim(60-75) 29·08%, enol(5-21) 37·59%, fibrin(617-31) 31·21%, col-II(358-75) 29·97% and filaggrin(306-24) 28·37%, while control ctrlPAD(621-40) showed no reactivity. All reactive peptides were found to be highly specific for RA. A notable cross-reaction (>70%) was found mainly between filaggrin and the majority of anti-citrullinated peptide antibodies. We concluded that ACPA in RA constitute a heterogeneous population with limited cross-reactivity and without a predominant epitope.

Cryoglobulinemic vasculitis in primary Sjögren's Syndrome: Clinical presentation, association with lymphoma and comparison with Hepatitis C-related disease.

OBJECTIVE: To describe the clinical spectrum of cryoglobulinemic vasculitis (CV) in primary Sjögren's syndrome (pSS), investigate its relation to lymphoma and identify the differences with hepatitis C virus (HCV) related CV. METHODS: From a multicentre study population of consecutive pSS patients, those who had been evaluated for cryoglobulins and fulfilled the 2011 classification criteria for CV were identified retrospectively. pSS-CV patients were matched with pSS patients without cryoglobulins (1:2) and HCV-CV patients (1:1). Clinical, laboratory and outcome features were analyzed. A data driven logistic regression model was applied for pSS-CV patients and their pSS cryoglobulin negative controls to identify independent features associated with lymphoma. RESULTS: 1083 pSS patients were tested for cryoglobulins. 115 (10.6%) had cryoglobulinemia and 71 (6.5%) fulfilled the classification criteria for CV. pSS-CV patients had higher frequency of extraglandular manifestations and lymphoma (OR=9.87, 95% CI: 4.7-20.9) compared to pSS patients without cryoglobulins. Purpura was the commonest vasculitic manifestation (90%), presenting at disease onset in 39% of patients. One third of pSS-CV patients developed B-cell lymphoma within the first 5 years of CV course, with cryoglobulinemia being the strongest independent lymphoma associated feature. Compared to HCV-CV patients, pSS-CV individuals displayed more frequently lymphadenopathy, type II IgMk cryoglobulins and lymphoma (OR = 6.12, 95% CI: 2.7-14.4) and less frequently C4 hypocomplementemia and peripheral neuropathy. CONCLUSION: pSS-CV has a severe clinical course, overshadowing the typical clinical manifestations of pSS and higher risk for early lymphoma development compared to HCV related CV. Though infrequent, pSS-CV constitutes a distinct severe clinical phenotype of pSS.

Pathogenesis of subacute cutaneous lupus erythematosus.

Subacute cutaneous lupus erythematosus (SCLE) is a photosensitive form of lupus-specific skin lesion that is strongly associated with the presence of anti-Ro/SSA autoantibody. The pathogenesis of SCLE includes genetic, environmental and immunologic factors. Recent studies provide strong evidence for the involvement of innate and cell-mediated immunity, underlying the important role of plasmacytoid dendritic cells, interferon-alpha and antibody-dependent cell cytotoxicity. In addition, a variety of cytokines, chemokines and adhesion molecules have been found to participate in the expansion phase of the autoimmune effector mechanisms. This article summarizes the recent immunological findings and reviews the current mechanisms which are implied in the development of the disease.