Sabine Grootenboer-Mignot

Identification of Periplakin as a New Target for Autoreactivity in Idiopathic Pulmonary Fibrosis

RATIONALE Injury to alveolar epithelial cells is central to the pathophysiology of idiopathic pulmonary fibrosis (IPF). An abnormal autoimmune response directed against antigens of the alveolar epithelium may contribute to the disease. OBJECTIVES To detect circulating autoantibodies (autoAbs) directed against epithelial structures. METHODS We performed immunoblot by separating human placental amnion extract or alveolar epithelial cell (A549 cell line) proteins on polyacrylamide gels, blotting on nitrocellulose membranes, and incubating with serum from patients with IPF (n = 40) or healthy subjects (n = 40). Proteomic analysis and mass spectrometry characterized the target protein. Inhibition experiments performed with the correspondent recombinant protein confirmed our results. MEASUREMENTS AND MAIN RESULTS We identified IgG autoAbs recognizing a 200-kD protein in the serum of patients with IPF. Proteomic analysis identified this protein as human periplakin (PPL), a component of desmosomes. Anti-PPL Abs were found by immunoblot in both serum and bronchoalveolar lavage in patients with IPF: 16/40 (40%) of them were positive versus none of the control subjects. Immunohistochemistry revealed that PPL was strongly expressed in bronchial and alveolar epithelium, but that PPL exhibited changes in intracellular localization among normal and fibrotic alveolar epithelium. In an alveolar epithelial wound repair assay, an anti-PPL IgG decreased cell migration. Recombinant PPL induced bronchoalveolar lavage T lymphocyte proliferation. Patients with IPF with anti-PPL Abs had a more severe respiratory disease, despite no difference in survival. CONCLUSIONS We found a new circulating autoAb directed against PPL in patients with IPF, associated with a more severe disease.

Prospective cohort study of effects of infliximab on rheumatoid factor, anti-cyclic citrullinated peptide antibodies and antinuclear antibodies in patients with long-standing rheumatoid arthritis.

BACKGROUND Antibodies to cyclic citrullinated peptide (anti-CCP) and IgM rheumatoid factor (IgM-RF) are well-established serological markers for rheumatoid arthritis (RA). Lupus-like disease with antinuclear antibodies (ANA) has been reported during TNFalpha antagonist therapy. Our objectives were to investigate the effect of infliximab therapy on these three autoantibodies in patients with established RA and to look for correlations linking IgM-RF and anti-CCP titres to a treatment response (defined as a good or moderate EULAR response) after 48 weeks of infliximab therapy. METHODS Thirty-six patients with long-standing RA not responding to disease-modifying anti-rheumatic drugs (DMARDs) received intravenous infliximab (starting dose: 3mg/kg) at 0, 2, and 6 weeks then at 8-week intervals, in combination with a DMARD. At baseline, week 24, and week 48, C-reactive protein (CRP) and the erythrocyte sedimentation rate (ESR) were determined and the disease activity score (DAS28) was calculated. Serum samples collected at the same time points were used to measure anti-CCP (commercial second-generation ELISA), IgM-RF (quantitative nephelometric assay), and ANA (indirect immunofluorescence in HEp2 cells). Correlations linking baseline autoantibody titres to changes in autoantibody levels were examined. RESULTS At baseline, tests were positive for anti-CCP in 31/36 (94.6%) patients, IgM-RF in 29/36 (80.5%) patients, and ANA in 16/36 (44%) patients. IgM-RF titres decreased significantly (p<0.001), whereas anti-CCP showed little change (p=0.053). ANA titres increased significantly (p<0.001). The treatment response was not associated with changes in anti-CCP or IgM-RF titres during infliximab therapy (OR for a response in patients with a 50% anti-CCP decrease, 0.77 [95%CI, 0.16-3.58]; OR for a response in patients with a 50% IgM-RF decrease, 0.82 [95%CI, 0.16-4.13]). CONCLUSIONS During infliximab therapy used to treat established RA, IgM-RF titres showed larger decreases than anti-CCP titres. Changes in IgM-RF and anti-CCP failed to correlate with the 48-week treatment response.

Autoantibodies to citrullinated fibrinogen compared with anti-MCV and anti-CCP2 antibodies in diagnosing rheumatoid arthritis at an early stage: data from the French ESPOIR cohort

Objectives To compare the performance of anticitrullinated peptides/protein antibodies (ACPA) detected by three immunoassays in the French ESPOIR cohort of patients with early rheumatoid arthritis (RA) and undifferentiated arthritis (UA) and to study the relationship between ACPA and disease activity. Methods A diagnosis of RA (1987 American College of Rheumatology (ACR) criteria) was established at baseline in 497 patients and after a 2-year follow-up in 592 patients. At baseline, antibodies to citrullinated fibrinogen (AhFibA), antimutated citrullinated vimentin (anti-MCV) and anticyclic citrullinated peptide (anti-CCP2) were assayed and the individual and combined diagnostic sensitivities and predictive values of the tests were determined. Relationships between ACPA positivity and the 28-joint disease activity score and Health Assessment Questionnaire scores were analysed. Results At a diagnostic specificity of at least 98%, the three tests exhibited similar diagnostic sensitivities (47–48.5%). When considering as positive patients with at least one positive test, the sensitivity increased to 53.5% with a probable loss of specificity. Among the patients classified as having UA at baseline, 30% were positive for one ACPA, the positive predictive values for RA of the three tests ranging from 73% to 80% but increasing when two tests were associated. Whatever the test used, the addition of ACPA positivity to the 1987 criteria enhanced their sensitivity by 6%, close to that of the 2010 ACR/European League Against Rheumatism (EULAR) criteria. Conclusions In early arthritis, AhFibA, anti-MCV and anti-CCP2 showed similar diagnostic sensitivity with a high diagnostic specificity and a similar high positive predictive value for RA. Adding ACPA to the 1987 ACR criteria significantly increased the number of patients classified as having RA, confirming the validity of the recent inclusion of the serological criterion in the ACR/EULAR criteria.

Levels of anticardiolipin and anti-β2-glycoprotein I antibodies in healthy newborn cord sera

Levels of anticardiolipin and anti-β2-glycoprotein I antibodies in healthy newborn cord sera -

Diagnostic performance of three assays for anticitrullinated protein antibodies in the very early arthritis ‘ESPOIR’ cohort

Background and objectives Anticitrullinated protein antibodies (ACPA) are recognised as the most specific markers for rheumatoid arthritis (RA). Their detection can be performed with various ELISAs using either the autoantigenic targets (human mutated vimentin: MCV and human fibrinogen: AhFibA) or cyclic peptides (CCP2). We investigated the diagnostic value of these ELISAs in a French cohort of undifferentiated arthritis of less than 6-month duration (ESPOIR cohort). Material and methods 685 patients were followed until 2 years after inclusion. Antibodies were determined at baseline. The cut-off of each assay was previously determined in order to obtain a similar 98% diagnostic specificity. Diagnostic sensitivity was determined for patients classified as RA at 2 years, according to the 1987 American College of Rheumatology (ACR) criteria. Results 592 (86.4 %) patients were classified as RA at 2 years. 47–48.5 % of RA patients were positive for one single test at baseline without any significant differences between the 3 assays, and 317 (53.5 %) were positive for at least one. Discrepant results were observed for eight patients positive only for anti-CCP2, 17 for anti-MCV antibodies, and 16 for AhFibA. 95 patients classified as RA at 2 years were not classified as RA at baseline: 30 of them (31.5%) were positive for at least one assay at baseline. If the positivity of at least one assay is included in the diagnostic criteria, 543 patients are classified as RA (79.3%) at inclusion, instead of 497 (72.5%) without it. Diagnostic sensitivities of ACPA assays Sensitivity (%) Anti-CCP 47 Anti-MCV 47.3 AhFibA 48.5 Anti-CCP or anti-MCV 50.8 Anti-CCP or AhFibA 50.7 Anti-MCV or AhFibA 52.2 At least 1 ACPA assay 53.5 Conclusions The performance of the three ACPA assays is similar but the tests do not totally overlap. In very early undifferentiated arthritis, the detection of the three ACPA subfamilies increased the sensitivity of 6% as compared with the assays of only 1 marker with the risk of a slight decrease in specificity. Moreover, the positivity of one ACPA assay 2 years before the diagnosis was predictive for RA in 30% of the 95 patients without a diagnosis at inclusion. When ACPA were included among the diagnostic criteria, 7% more patients were classified as RA at inclusion. These results are in perfect agreement with the new ACR/EULAR classification criteria for RA which now include ACPA.