[Autoantibodies as biomarkers]. / Les auto-anticorps comme biomarqueurs.

Activation and differentiation of autoreactive B-lymphocytes lead to the production of autoantibodies, which are thus the direct consequence of the autoimmune process. They often constitute biomarkers of autoimmune diseases and are measured by tests displaying various diagnosis sensitivity and specificity. Autoantibody titers can be correlated to the disease activity and certain autoantibody populations associated with particular clinical manifestations or tissue lesions. The demonstration that autoantibodies appear years before the onset of autoimmune diseases indicates that their presence in healthy individuals may be a predictive marker of the occurrence of disease. Certain autoantibodies could also be predictive markers of a therapeutic response to biologics and of the occurrence of side effects as well. Thus, autoantibodies are useful tools in the diagnosis and the management of patients with organ specific or non-organ specific autoimmune diseases at different steps of the autoimmune process.

Autosomal dominant STAT3 deficiency and hyper-IgE syndrome: molecular, cellular, and clinical features from a French national survey.

Autosomal dominant deficiency of signal transducer and activator of transcription 3 (STAT3) is the main genetic etiology of hyper-immunoglobulin (Ig) E syndrome. We documented the molecular, cellular, and clinical features of 60 patients with heterozygous STAT3 mutations from 47 kindreds followed in France. We identified 11 known and 13 new mutations of STAT3. Low levels of interleukin (IL)-6-dependent phosphorylation and nuclear translocation (or accumulation) of STAT3 were observed in Epstein-Barr virus-transformed B lymphocytes (EBV-B cells) from all STAT3-deficient patients tested. The immunologic phenotype was characterized by high serum IgE levels (96% of the patients), memory B-cell lymphopenia (94.5%), and hypereosinophilia (80%). A low proportion of IL-17A-producing circulating T cells was found in 14 of the 15 patients tested. Mucocutaneous infections were the most frequent, typically caused by Staphylococcus aureus (all patients) and Candida albicans (85%). Up to 90% of the patients had pneumonia, mostly caused by Staph. aureus (31%) or Streptococcus pneumoniae (30%). Recurrent pneumonia was associated with secondary bronchiectasis and pneumatocele (67%), as well as secondary aspergillosis (22%). Up to 92% of the patients had dermatitis and connective tissue abnormalities, with facial dysmorphism (95%), retention of decidual teeth (65%), osteopenia (50%), and hyperextensibility (50%). Four patients developed non-Hodgkin lymphoma. The clinical outcome was favorable, with 56 patients, including 43 adults, still alive at the end of study (mean age, 21 yr; range, 1 mo to 46 yr). Only 4 patients died, 3 from severe bacterial infection (aged 1, 15, and 29 yr, respectively). Antibiotic prophylaxis (90% of patients), antifungal prophylaxis (50%), and IgG infusions (53%) improved patient health, as demonstrated by the large decrease in pneumonia recurrence. Overall, the prognosis of STAT3 deficiency may be considered good, provided that multiple prophylactic measures, including IgG infusions, are implemented.

Synovium CD20 expression is a potential new predictor of bone erosion progression in very-early arthritis treated by sequential DMARDs monotherapy -- a pilot study from the VErA cohort.

OBJECTIVE: Because available biomarkers (rheumatoid factors [RF], anti-cyclic citrullinated autoantibodies [anti-CCP2], erythrocyte sedimentation rate at 1st hour [ESR]/C-reactive peptide [CRP] and bone erosions) are insufficient to predict rheumatoid arthritis (RA) structural damage, to determine whether synovium expression of greater or equal to 1 markers could constitute new prognostic factor(s). METHOD: The study was conducted on 18 prospectively enrolled disease-modifying anti-rheumatic drug (DMARD)- and glucocorticoid-naïve, VErA cohort patients with very-early arthritis (median duration: 4months). Recorded at baseline were: clinical and biological (serum ESR, CRP, RF-isotypes, anti-CCP2, osteoprotegerin, receptor activator of nuclear κB-ligand [RANK-L] and cartilage oligomeric matrix protein [COMP] levels) data; synovium expression (HLA-DR, CD163, CD3, CD20, VEGF, osteoprotegerin, RANK-L, Bcl2 and global inflammation index) for a metacarpophalangeal joint-synovium biopsy. Baseline and 3-year hand-and-foot X-rays were graded with the van der Heijde-modified-Sharp score; the judgment criterion was its progression during follow-up. Pearson's product moment correlation statistics were used to test for association between paired samples. RESULTS: A baseline, a significant relationship was found between erosive damage and markers of B-cell activation, notably the synovium CD20 expression (r=0.68; P=0.0001). Quantified by the modified-Sharp erosion score variation, the 3-year structural damage progression was significantly correlated with: serum levels of RF-IgG (r=0.75; P=0.0003), -IgM (r=0.69; P=0.001), anti-CCP2 (r=0.53; P=0.02) and RANK-L (r=0.61; P=0.007); synovium CD20 expression (r=0.70; P=0.001). CONCLUSION: This analysis of the prognostic value of a large panel of synovium markers in a limited sample of prospectively followed, well-documented patients suggested that both synovial CD20 and serum RANK-L levels might be new predictors of structural damage progression in very-early RA.

Parental consanguinity is associated with a severe phenotype in common variable immunodeficiency.

The DEFI study has collected clinical data and biological specimens from kindreds with CVID. Patients with demonstrated parental consanguinity (cCVID group) were compared to patients without parental consanguinity (ncCVID). A total of 24 of the 436 patients with CVID had consanguineous parents. Age at first symptoms and age at diagnosis were comparable in the two groups. Some complications were more frequent in cCVID patients: splenomegaly (62.5% vs. 29%; p = 0.001), granulomatous disease (29% vs. 12%; p = 0.02), and bronchiectasis (58% vs. 29%; p = 0.003). A high incidence of opportunistic infections was also observed in this population (29% vs. 5%; p < 0.001). Distribution of B-cell subsets were similar in the two groups. Naïve CD4+ T cells were decreased in cCVID patients (15% vs. 28%; p < 0.001), while activated CD4 + CD95+ (88% vs. 74%; p = 0.002) and CD8 + HLA-DR + T cells (47% vs. 31%; p < 0.001) were increased in these patients when compared to ncCVID patients. Parental consanguinity is associated with an increased risk of developing severe clinical complications in patients with CVID. Most of these patients presented with severe T-cell abnormalities and should be considered with a diagnosis of late-onset combined immune deficiency (LOCID). Systematic investigation for parental consanguinity in patients with CVID provides useful information for specific clinical care and genetic screening.

Frequent and widespread vascular abnormalities in human signal transducer and activator of transcription 3 deficiency.

BACKGROUND: Signal transducer and activator of transcription 3 (STAT3) deficiency is responsible for autosomal dominant hyperimmunoglobulin E syndrome, characterized by recurrent bacterial and fungal infections, connective tissue abnormalities, hyperimmunoglobulin E, and Th17 lymphopenia. Although vascular abnormalities have been reported in some patients, the prevalence, characteristics, and etiology of these features have yet to be described. METHODS AND RESULTS: We prospectively screened 21 adult STAT3-deficient patients [corrected] (median age, 26 years; range, 17-44 years) [corrected] for vascular abnormalities. We explored the entire arterial vasculature with whole-body magnetic resonance imaging angiography, coronary multislice computed tomography, and echo-tracking-based imaging specifically for the [corrected] carotid arteries. We also assayed for serum biomarkers of inflammation and endothelial dysfunction. Finally, we studied murine models of aortic aneurysm in the presence and absence of inhibitors of STAT3-dependent signaling. Ninety-five percent of patients showed brain abnormalities (white matter hyperintensities, lacunar lesions suggestive of ischemic infarcts, and atrophy). We reported peripheral and brain artery abnormalities in 84% of the patients and detected coronary artery abnormalities in 50% of the patients. The most frequent vascular abnormalities were ectasia and aneurysm. The carotid intima-media thickness was markedly decreased, with a substantial increase in circumferential wall stress, indicating the occurrence of hypotrophic arterial remodeling in this STAT3-deficient population. Systemic inflammatory biomarker levels correlated poorly with the vascular phenotype. In vivo inhibition of STAT3 signaling or blockade of IL-17A resulted in a marked increase in aneurysm severity and fatal rupture in mouse models. CONCLUSIONS: Vascular abnormalities are highly prevalent in patients with STAT3 deficiency. This feature is consistent with the greater susceptibility to vascular aneurysm observed after inhibition of STAT3-dependent signaling in mouse models.

Correlation of anti-signal recognition particle autoantibody levels with creatine kinase activity in patients with necrotizing myopathy.

OBJECTIVE: Anti-signal recognition particle (anti-SRP) autoantibodies are associated with severe acquired necrotizing myopathies. The role of these autoantibodies remains elusive, and the evolution of anti-SRP levels over time is unknown. In this study, we developed an addressable laser bead immunoassay (ALBIA) technique to investigate a correlation between anti-SRP levels, serum creatine kinase (CK) levels, and muscle strength in patients with necrotizing myopathy. METHODS: The diagnostic value of the ALBIA assay was determined by comparing serum levels of anti-SRP autoantibodies in 31 anti-SRP immunodot-positive patients to those in 190 healthy blood donors and 199 control patients with different inflammatory/autoimmune conditions or polyclonal hypergammaglobulinemia. Among the 31 anti-SRP-positive patients, serum samples from 8 patients were monitored over time for levels of anti-SRP autoantibodies and levels of CK (determined at least 3 times, consecutively, over a mean followup period of 783 days). The relationship between levels of anti-SRP autoantibodies and levels of CK was tested using a linear mixed model. RESULTS: The assay yielded positive results for anti-SRP in all anti-SRP immunodot-positive serum samples tested, while all control sera tested negative. The 8 anti-SRP-positive patients who were followed up longitudinally were found to have normalized CK levels and improved muscle strength. There was a striking correlation between the degree of myolysis, as measured by CK levels, in patients receiving therapy and the anti-SRP54 autoantibody levels in these same patients (P = 0.002). CONCLUSION: Anti-SRP-positive myositis appears to be one of the few autoimmune diseases in which specific autoantibody levels are correlated with surrogate disease activity markers. These results reveal the usefulness of monitoring anti-SRP autoantibody levels in patients receiving therapy, and may also suggest a possible pathogenic role for anti-SRP autoantibodies in the necrotizing myopathies.

Enzyme-linked immunosorbent assay for the combination of bullous pemphigoid antigens 1 and 2 in the diagnosis of bullous pemphigoid.

OBJECTIVE: To assess the usefulness of enzyme-linked immunosorbent assay (ELISA) assessment of the combination of bullous pemphigoid antigen 1 (BPAG1) and BPAG2 in the diagnosis of bullous pemphigoid (BP). DESIGN: Retrospective study of serum samples from patients with BP. SETTING: Tertiary care center. PATIENTS: A total of 190 patients with newly diagnosed BP and 78 controls with other autoimmune bullous diseases. INTERVENTION: Serum samples were tested using commercialized BPAG1 and BPAG2 ELISA and indirect immunofluorescence (IIF). MAIN OUTCOME MEASURES: The sensitivity and specificity of ELISA for the combination of BPAG1 and BPAG2 in the diagnosis of BP were contrasted with ELISA for each of the antigens alone and with IIF. RESULTS: The sensitivity and specificity of ELISA for the combination of BPAG1 and BPAG2 were 87% and 88%, respectively, compared with 79% and 90% for BPAG2 ELISA, 61% and 96% for BPAG1 ELISA, and 81% and 63% for IIF. The combination of BPAG1 ELISA and BPAG2 ELISA permitted 8% and 16% gains in sensitivity compared with each of BPAG2 ELISA and BPAG1 ELISA alone, respectively. Anti-BPAG1 antibodies were detected in 15 of 40 BP serum samples with no anti-BPAG2 antibodies (38%) and in 8 of 13 serum samples from patients with BP and mucosal involvement (62%) compared with 2 of 22 samples of cicatricial pemphigoid (P = .002) and 0 of 16 epidermolysis bullosa acquisita serum samples (P < .001). The BPAG2 ELISA values were more closely correlated with initial extent of BP lesions (r = 0.44, P < .001) than BPAG1 ELISA values (r = 0.16, P = .03). CONCLUSION: Since the combination of BPAG1 and BPAG2 ELISA only slightly increases the sensitivity of BP diagnosis over BPAG2 ELISA alone, BPAG1 ELISA could be adequately proposed in a minority of BP cases with mucosal involvement and in those with no circulating anti-BPAG2 antibodies.

Role of toll-like receptor 4 in the inflammation reaction surrounding silicone prosthesis.

The inflammation which occurs around the silicone prosthesis is a complex process that can provoke the failure of the device and compromise the health of the implanted patient. Toll-like receptors (TLRs), which are transmembrane proteins, are now known to act in the innate immune response and in endogenous inflammation. The aim of our study was to assess the role of TLR4 in the foreign body reaction to a silicone shell prosthesis. Disks of shell silicone prosthesis were implanted in the subcutaneous tissue of C57BL6-TLR4-/- and C57BL6-WT mice. At day 14, inflammatory cell infiltrate and vessel sections around the prosthesis were less numerous in TLR4-/- than in WT mice. A histomorphometric analysis showed that the capsule around the implant was 1.96-fold less thick in depleted TLR4 than in wild-type mice. In addition, vascular endothelial growth factor and transforming growth factor 1 were underexpressed in the surrounding tissue of the prosthesis in TLR4-/- mice. Our study suggests, from this foreign body response model against silicone in mice, that TLR4 plays a key role in the reaction process around silicone implants.

Gene profiling predicts rheumatoid arthritis responsiveness to IL-1Ra (anakinra).

OBJECTIVES: The overall non-response rate to biologics remains 30-40% for patients with RA resistant to MTX. The objective of this study was to predict responsiveness to the anakinra-MTX combination by peripheral blood mononuclear cell gene profiling in order to optimize treatment choice. METHODS: Thirty-two patients treated with anakinra (100 mg/day s.c.) and MTX were categorized as responders when their 28-joint DAS (DAS-28) had decreased by ≥1.2 at 3 months. Pre-treatment blood samples had been drawn. RESULTS: For seven responders and seven non-responders, 52 microarray-identified mRNAs were expressed as a function of the response to treatment, and unsupervised hierarchical clustering correctly separated responders from non-responders. The levels of seven of these 52 transcripts, as assessed by real-time, quantitative RT-PCR, were able to accurately classify 15 of 18 other patients (8 responders and 10 non-responders), with 87.5% specificity and 77.8% negative-predictive value for responders. Among the 52 genes, 56% were associated with IL-1ß. CONCLUSION: This predictive gene expression profile was obtained with a non-invasive procedure. After further validation in other cohorts of patients, it could be proposed and used on a large scale to select likely RA responders to combined anakinra-MTX. Trial registration. Clinical Trials; NCT00213538 (http://www.clinicaltrials.gov).

Human duodenal proteome modulations by glutamine and antioxidants.

PURPOSE: Glutamine (Gln) has protective, anti-inflammatory effects in animal models and humans. Antioxidant nutrients may exert synergistic effects on intestinal functions. Therefore, these combined nutrients may have a therapeutic potential during intestinal inflammation. This study was designed to investigate in humans the effects of a supplement composed of Gln and high-dosed antioxidant micronutrients compared to isomolar Gln only, on duodenal proteome. EXPERIMENTAL DESIGN: Enteral perfusion of Gln (0.8 mmol x kg(-1) x h(-1)) or supplement was performed in two groups of six healthy volunteers during 5 h before taking endoscopic duodenal biopsies. Protein expression was analyzed by 2-DE and the relevant proteins identified by MS/MS. RESULTS: About 1500 protein spots were revealed in both supplement and Gln conditions. Comparative proteomics analysis indicated that 11 proteins were differentially and significantly (p≤0.05) expressed in response to the supplement. These proteins were essentially implicated in metabolism pathways, e.g. fatty acid binding protein-1 and 40S ribosomal protein SA expressions were downregulated while manganese superoxide dismutase and retinal dehydrogenase-1 expressions were upregulated. CONCLUSIONS AND CLINICAL RELEVANCE: This study provides new information on human duodenal proteome and its nutritional modulation, and supports further clinical investigations designed to evaluate the effects of Gln plus antioxidants during intestinal inflammation and cancer.

Serum IgA rheumatoid factor and pyridinoline in very early arthritis as predictors of erosion(s) at two years: a simple model of prediction from a conservatively treated community-based inception cohort.

OBJECTIVE: To identify, in conservatively treated, very early arthritis patients, predictors of ≥1 erosion(s) at 2 years, and to construct a prediction model. METHODS: Community-based adults (n=310) who had never taken disease-modifying antirheumatic drugs (DMARDs) or steroids with swelling of ≥2 joints persisting for >4 weeks and lasting <6 months were recruited. Erosion status was assessed at 0, 6, 12, and 24 months; evaluations were comprised of clinical criteria (Disease Activity Score, Health Assessment Questionnaire), C-reactive protein level, erythrocyte sedimentation rate, autoantibodies, bone and cartilage markers, hand densitometry, and HLA class II shared epitopes. Patients meeting American College of Rheumatology rheumatoid arthritis (RA) criteria or with undifferentiated arthritis (UA) were followed and treated conservatively: one-third of RA patients and three-fourths of UA patients received no DMARDs during 2 years; a biologic agent was given to 1.8% of the patients during the first year. The main judgment criterion was ≥1 erosion(s) at 2 years. RESULTS: At 2 years, 219 patients were assessed; 31.3% with RA and 10.6% with UA had ≥1 erosion(s). Logistic regression analysis at that time showed erosion(s) strongly associated with serum IgA rheumatoid factor (IgA-RF) and pyridinoline levels for the 190 patients with no baseline erosions, with the corresponding receiver operating characteristic curve having an area under the curve of 0.77 (95% confidence interval 0.64-0.86). A prediction model was constructed with IgA-RF thresholds of 5 and 25 IU/ml and a pyridinoline threshold of 10 nM/liter; odds ratios ranged from 1 for IgA-RF<5 IU/ml and pyridinoline <10 nM/liter to 50.75 for the association of IgA-RF≥5 IU/ml and pyridinoline≥10 nM/liter. CONCLUSION: This model, using serum IgA-RF and pyridinoline concentrations, was able to predict≥1 erosion(s) at 2 years in very early arthritis patients.

Critical role of TLR2 and TLR4 in autoantibody production and glomerulonephritis in lpr mutation-induced mouse lupus.

Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by pathogenic autoantibodies directed against nuclear Ags and immune complex deposits in damaged organs. Environmental factors have been thought to play a role in the onset of the disease. The recognition of these factors is mediated by TLRs, in particular TLR2 and TLR4 which bind pathogen-associated molecular patterns of Gram(+) and Gram(-) bacteria, respectively. We attempted to determine the role of these TLRs in SLE by creating TLR2- or TLR4-deficient C57BL/6(lpr/lpr) mice. These mice developed a less severe disease and fewer immunological alterations. Indeed, in C57BL/6(lpr/lpr)-TLR2 or -TLR4-deficient mice, glomerular IgG deposits and mesangial cell proliferation were dramatically decreased and antinuclear, anti-dsDNA, and anti-cardiolipin autoantibody titers were significantly reduced. However, the response against nucleosome remained unaffected, indicating a role of TLR2 and TLR4 in the production of Abs directed against only certain categories of SLE-related autoantigens. Analysis of B cell phenotype showed a significant reduction of marginal zone B cells, particularly in C57BL/6(lpr/lpr)-TLR4-deficient mice, suggesting an important role of TLR4 in the sustained activation of these cells likely involved in autoantibody production. Interestingly, the lack of TLR4 also affected the production of cytokines involved in the development of lupus disease.

Early and long-standing rheumatoid arthritis: distinct molecular signatures identified by gene-expression profiling in synovia.

INTRODUCTION: Rheumatoid arthritis (RA) is a heterogeneous disease and its underlying molecular mechanisms are still poorly understood. Because previous microarray studies have only focused on long-standing (LS) RA compared to osteoarthritis, we aimed to compare the molecular profiles of early and LS RA versus control synovia. METHODS: Synovial biopsies were obtained by arthroscopy from 15 patients (4 early untreated RA, 4 treated LS RA and 7 controls, who had traumatic or mechanical lesions). Extracted mRNAs were used for large-scale gene-expression profiling. The different gene-expression combinations identified by comparison of profiles of early, LS RA and healthy synovia were linked to the biological processes involved in each situation. RESULTS: Three combinations of 719, 116 and 52 transcripts discriminated, respectively, early from LS RA, and early or LS RA from healthy synovia. We identified several gene clusters and distinct molecular signatures specifically expressed during early or LS RA, thereby suggesting the involvement of different pathophysiological mechanisms during the course of RA. CONCLUSIONS: Early and LS RA have distinct molecular signatures with different biological processes participating at different times during the course of the disease. These results suggest that better knowledge of the main biological processes involved at a given RA stage might help to choose the most appropriate treatment.

Diagnostic and prognostic usefulness of antibodies to citrullinated peptides.

The diagnosis of rheumatoid arthritis (RA) must be made early, because prompt initiation of treatments tailored to disease activity is crucial to improve structural and functional outcomes. Anti-citrullinated peptide antibodies (ACPAs) are well-established diagnostic markers for RA and should be included in the classification criteria. Here, we describe the main tests for detecting ACPAs and we underline the diagnostic and prognostic usefulness of ACPAs in patients with RA. The presence of ACPAs predicts poorer functional and structural outcomes, and ACPA titers respond to some of the medications used in RA. Therefore, ACPA titers should be determined at regular intervals throughout follow-up.

Can rheumatoid arthritis responsiveness to methotrexate and biologics be predicted?

This review briefly recapitulates the existing markers predictive of RA responsiveness to treatment, focusing on MTX alone or combined with a biologic. In addition to the demographic and clinical factors, an update is provided of the predictive biomarkers identified by large-scale gene and protein analyses that generated new insights into the ability of high-throughput analysis of biological systems to select new potential indicators. Among the large-scale analysis tools now available, pharmacogenetics and pharmacogenomics (including transcriptomic and proteomic approaches) have been shown to provide such new putative biomarkers of therapeutic responses.

ELISA testing of anti-desmoglein 1 and 3 antibodies in the management of pemphigus.

OBJECTIVE: To assess the predictive value of anti-desmoglein (Dsg) 1 and anti-Dsg3 antibody (Ab) enzyme-linked immunosorbent assay (ELISA) values for the occurrence of relapses in pemphigus. DESIGN: Retrospective study. SETTING: Dermatology departments from 13 university hospitals in France. Patients The study population comprised 26 patients with typical clinical, histologic, and immunofluorescence findings of pemphigus, who were followed up over a 17-month period. MAIN OUTCOME MEASURES: Serial anti-Dsg1 and anti-Dsg3 Ab ELISA values were recorded during the patients' follow-up examinations and correlated with the occurrence of skin and/or mucosal relapses. RESULTS: A significant reduction of anti-Dsg1 (P < .001) and anti-Dsg3 (P < .001) Ab ELISA values was observed in serum samples from patients with pemphigus foliaceus or pemphigus vulgaris after the initial treatment. During the long-term follow-up, anti-Dsg1 Ab ELISA values correlated with the course of skin lesions (P = .03); the 20 U/mL cutoff for the anti-Dsg1 Ab ELISA value provided a 79% positive and an 84% negative predictive value for the occurrence of cutaneous relapses. No correlation was observed between anti-Dsg3 Ab ELISA values and the course of mucosal lesions (P = .13). Anti-Dsg3 Ab ELISA values higher than the 14-U/mL cutoff were observed in 5 of the 5 patients with relapse and in 10 of the 13 patients with ongoing mucosal remission, providing a 100% sensitivity but a poor specificity of 23%. A cutoff value of 130 U/mL for anti-Dsg3 Abs was calculated based on the receiver operating characteristics curve and provided an 84% positive and an 81% negative predictive value. CONCLUSIONS: Anti-Dsg1 Ab ELISA values are more closely correlated than anti-Dsg3 Ab ELISA values with the course of the disease in patients with pemphigus vulgaris or pemphigus foliaceus. This should be taken into account for the management of patients with pemphigus.

Candidate autoantigens identified by mass spectrometry in early rheumatoid arthritis are chaperones and citrullinated glycolytic enzymes.

INTRODUCTION: The aim of our study was to identify new early rheumatoid arthritis (RA) autoantibodies. METHODS: Sera obtained from 110 early untreated RA patients (<6 months) were analyzed by western blot using HL-60 cell extract, separated on one-dimensional and two-dimensional gel electrophoresis (1-DE, 2-DE). Sera from 50 healthy blood donors and 20 patients with non-RA rheumatisms were used as controls for 1-DE and 2-DE, respectively. The immunoreactive proteins were identified by MALDI-TOF mass spectrometric analysis and the presence of potential sites of citrullination in each of these proteins was evaluated. FT-ICR mass spectrometry was used to verify experimentally the effect of citrullination upon the mass profile observed by MALDI-TOF analysis. RESULTS: The 110 1-DE patterns allowed detection of 10 recurrent immunoreactive bands of 33, 39, 43, 46, 51, 54, 58, 62, 67 and 70 kDa, which were further characterized by 2-DE and proteomic analysis. Six proteins were already described RA antigens: heterogeneous nuclear ribonucleoprotein A2/B1, aldolase, alpha-enolase, calreticulin, 60 kDa heat shock protein (HSP60) and BiP. Phosphoglycerate kinase 1 (PGK1), stress-induced phosphoprotein 1 and the far upstream element-binding proteins (FUSE-BP) 1 and 2 were identified as new antigens. Post-translational protein modifications were analyzed and potentially deiminated peptides were found on aldolase, alpha-enolase, PGK1, calreticulin, HSP60 and the FUSE-BPs. We compared the reactivity of RA sera with citrullinated and noncitrullinated alpha-enolase and FUSE-BP linear peptides, and showed that antigenicity of the FUSE-BP peptide was highly dependent on citrullination. Interestingly, the anti-cyclic citrullinated peptide antibody (anti-CCP2) status in RA serum at inclusion was not correlated to the reactivity directed against FUSE-BP citrullinated peptide. CONCLUSIONS: Two categories of antigens, enzymes of the glycolytic family and molecular chaperones are also targeted by the early untreated RA autoantibody response. For some of them, and notably the FUSE-BPs, citrullination is involved in the immunological tolerance breakdown observed earlier in RA patients. Autoantibodies recognizing a citrullinated peptide from FUSE-BP may enhance the sensibility for RA of the currently available anti-CCP2 test.

Regulation of feeding and anxiety by alpha-MSH reactive autoantibodies.

alpha-Melanocyte-stimulating hormone (alpha-MSH) is a stress-related neuropeptide involved in the regulation of motivated behavior, appetite and emotion including stimulation of satiety and anxiety. Although autoantibodies (autoAbs) reactive with alpha-MSH have been identified in human subjects and in rats, it remained unknown if these autoAbs are involved in the regulation of feeding and anxiety and if their production is related to stress. Here we show that repeated exposure of rats to anxiolytic mild stress by handling increases the levels and affinity of alpha-MSH reactive IgG autoAbs and that these changes are associated with adaptive feeding and anxiety responses during exposure of rats to a strong stress by food restriction. Importantly, an increase in affinity of alpha-MSH reactive autoAbs was associated with changes of their functional roles from stimulation to inhibition of alpha-MSH-mediated behavioural responses, suggesting that these autoAbs can be a carrier or a neutralizing molecule of alpha-MSH peptide, respectively. Using a model of passive transfer into the brain, we show that alpha-MSH autoAbs affinity purified from blood of rats exposed to repeated mild stress, but not from control rats, are able to increase acutely food intake, suppress anxiety and modify gene expression of hypothalamic neuropeptides in naïve rats. These data provide the first evidence that autoAbs reactive with alpha-MSH are involved in the physiological regulation of feeding and mood, supporting a further role of the immune system in the control of motivated behavior and adaptation to stress.

Detection and characterization of anti-envoplakin linker autoantibodies in paraneoplastic pemphigus using specific bead-based assay.

Paraneoplastic pemphigus (PNP) is characterized by an autoantibody response directed against desmosomal antigens, desmogleins and plakin's proteins, i.e., periplakin and envoplakin. Notably, PNP antibodies were shown to recognize major epitopes located in the linker subdomain of human envoplakin and thus, may constitute a diagnostic marker of PNP. In this study, a recombinant envoplakin-linker subdomain (rENV-L) was produced and used to develop a specific bead-based assay to determine the prevalence and titers of anti-rENV-L antibodies in patients with different types of autoimmune bullous skin diseases. Sera from 33 PNP, 41 pemphigus vulgaris, 46 pemphigus foliaceus, 24 bullous pemphigoid and 74 normal subjects were analyzed by rENV-L bead-based assay: 23/33 (69.7%) PNP, 2/24 (8.3%) bullous pemphigoid and 4/74 (5.4%) healthy control sera showed IgG reactivity against rENV-L. For PNP, the sensitivity and specificity of the assay were 69.7% and 94.6%, respectively. Among the PNP sera reacting with envoplakin and periplakin by immunoblot analysis, 80.8% contained anti-rENV-L antibodies. Finally, we showed that an anti-rENV-L mAb that recognizes both envoplakin and periplakin gave the same fluorescence pattern on rat bladder sections than PNP sera. Thus, anti-rENV-L antibodies constitute a useful diagnostic marker of PNP and our bead-based assay, notably combined with other epidermal autoantigens, a useful tool to diagnose PNP.