Tocilizumab in the treatment of mixed connective tissue disease and overlap syndrome in children

International audienceArthritis is one of the main manifestations of mixed connective tissue disease (MCTD) and overlap syndrome in children and can be responsible for functional disability. We report on 2 children with arthritis that were dramatically improved by a treatment with interleukin-6 (IL-6) blockers in the context of connective tissue disease. However, in both cases, other systemic autoimmune symptoms were not modified by the treatment and autoantibodies tend to increase, suggesting a differential effect of IL-6 inhibition on articular inflammation and systemic autoimmunity

MISS questionnaire in French version: a good tool for children and parents to assess methotrexate intolerance

International audienceThe aim of this study was to assess the relevance for children and parents to use the French-validated version of the methotrexate intolerance severity score (MISS), a measure of methotrexate intolerance for children suffering from juvenile idiopathic arthritis. The French-version MISS was developed following the "Guidelines for the process of cross-cultural adaptation of self-report measures." The new version was tested in families of children with juvenile idiopathic arthritis who completed the questionnaire twice at a 2-week interval. Item correlations, Cronbach's alpha, and kappa coefficients were computed to evaluate acceptability, internal consistency, and reproducibility. A culturally acceptable version to French was obtained. A total of 71 individuals were included from May 2015 to November 2015. The results show very good acceptability: good response rate (80%), few missing data (\textless1%) and good understanding of parents and children. The inter-item, dimension-item, and inter-dimension correlations were satisfactory (except for "vomiting" items-other items correlation). Cronbach's alpha coefficient was well higher than the usually recommended value of 0.6. The results of validity of internal and external consistencies were satisfactory. We also found good agreement between the test-retest for every family. The empirical discriminative cut-off point of 3 showed a sensitivity of 86% and a specificity of 83%. The MISS questionnaire is quick to complete, easy to use. It can be completed by children or their parents with no significant difference. This validated French-version MISS can help study prevalence and risk factors of methotrexate intolerance, better detect this intolerance, and provide better support for patients on long-term treatment

Familial Mediterranean fever mutations are hypermorphic mutations that specifically decrease the activation threshold of the Pyrin inflammasome

Objectives. FMF is the most frequent autoinflammatory disease and is associated in most patients with bi-allelic MEFV mutations. MEFV encodes Pyrin, an inflammasome sensor activated following RhoGTPase inhibition. The functional consequences of MEFV mutations on the ability of Pyrin variants to act as inflammasome sensors are largely unknown. The aim of this study was to assess whether MEFV mutations affect the ability of Pyrin to detect RhoGTPase inhibition and other inflammasome stimuli. Methods. IL-1β and IL-18 released by monocytes from healthy donors (HDs) and FMF patients were measured upon specific engagement of the Pyrin, NLRP3 and NLRC4 inflammasomes. Cell death kinetics following Pyrin activation was monitored in real time. Results. Monocytes from FMF patients secreted significantly more IL-1β and IL-18 and died significantly faster than HD monocytes in response to low concentrations of Clostridium difficile toxin B (TcdB), a Pyrin-activating stimulus. Monocytes from patients bearing two MEFV exon 10 pathogenic variants displayed an increased Pyrin inflammasome response compared with monocytes from patients with a single exon 10 pathogenic variant indicating a gene-dosage effect. Using a short priming step, the response of monocytes from FMF patients to NLRP3-and NLRC4-activating stimuli was normal indicating that MEFV mutations trigger a specific hypersensitivity of monocytes to low doses of a Pyrin-engaging stimulus. Conclusion. Contrary to the NLRP3 mutations described in cryopyrin-associated periodic syndrome, FMF-associated MEFV mutations do not lead to a constitutive activation of Pyrin. Rather, FMF-associated mutations are hypermorphic mutations that specifically decrease the activation threshold of the Pyrin inflammasome without affecting other canonical inflammasomes