Integrating the pathogenesis of spondyloarthritis: gut and joint united?

Purpose of review : The association between spondyloarthritis (SpA) and inflammatory bowel disease (IBD) is well known. Additionally, about half of SpA patients show microscopic gut inflammation. Substantial progress has been made in understanding the pathogenesis of SpA and IBD, with new therapeutic targets for either of them in clinical development. Recent findings : Microscopic gut inflammation was found in early forms of SpA in about 50% of cases and is associated with age, sex, disease activity and degree of MRI inflammation on sacroiliac joints. Although prospective follow-up data in men and murine animal studies show a parallelism between gut and joint evolution in SpA, therapeutic outcomes are not always the same in SpA and IBD. These differences can be ascribed to differences in not only the cytokine pathways and cells involved in disease, tissue localization and environmental factors but also in pharmacokinetics and biodistribution. Summary : A significant amount of data all point in the direction of arthritis and gut inflammation being pathogenetically closely linked in the SpA concept. However, when it comes to therapeutic effectiveness, the gut and the joints do not always react in the same way. These differences in therapeutic effect could be attributed to the different ways in which cytokine pathways are involved in SpA and IBD

The thymic microenvironment differentially regulates development and trafficking of invariant NKT cell sublineages

The regulatory role of the thymic microenvironment during trafficking and differentiation of the invariant NKT (iNKT) cell lineage remains poorly understood. In this study, we show that fractalkine receptor expression marks emigrating subpopulations of the NKT1, NKT2, and NKT17 sublineages in the thymus and peripheral organs of naive mice. Moreover, NKT1 sublineage cells can be subdivided into two subsets, namely NKT1(a) and NKT1(b), which exhibit distinct developmental and tissue-specific distribution profiles. More specifically, development and trafficking of the NKT1(a) subset are selectively dependent upon lymphotoxin (LT)α1β2-LTβ receptor-dependent differentiation of thymic stroma, whereas the NKT1(b), NKT2, and NKT17 sublineages are not. Furthermore, we identify a potential cellular source for LTα1β2 during thymic organogenesis, marked by expression of IL-7Rα, which promotes differentiation of the NKT1(a) subset in a noncell-autonomous manner. Collectively, we propose a mechanism by which thymic differentiation and retention of the NKT1 sublineage are developmentally coupled to LTα1β2-LTβ receptor-dependent thymic organogenesis.status: publishe

The thymic microenvironment differentially regulates development and trafficking of invariant NKT cell sublineages

The regulatory role of the thymic microenvironment during trafficking and differentiation of the invariant NKT (iNKT) cell lineage remains poorly understood. In this study, we show that fractalkine receptor expression marks emigrating subpopulations of the NKT1, NKT2, and NKT17 sublineages in the thymus and peripheral organs of naive mice. Moreover, NKT1 sublineage cells can be subdivided into two subsets, namely NKT1(a) and NKT1(b), which exhibit distinct developmental and tissue-specific distribution profiles. More specifically, development and trafficking of the NKT1(a) subset are selectively dependent upon lymphotoxin (LT)alpha 1 beta 2-LT beta receptor-dependent differentiation of thymic stroma, whereas the NKT1(b), NKT2, and NKT17 sublineages are not. Furthermore, we identify a potential cellular source for LT alpha 1 beta 2 during thymic organogenesis, marked by expression of IL-7R alpha, which promotes differentiation of the NKT1(a) subset in a noncell-autonomousmanner. Collectively, we propose a mechanism by which thymic differentiation and retention of the NKT1 sublineage are developmentally coupled to LT alpha 1 beta 2-LT beta receptor-dependent thymic organogenesis

Assessment of sensitivity to change of the European Scleroderma Study Group activity index

OBJECTIVES: The European Scleroderma Study Group (EScSG) activity index meets nearly all the OMERACT-standards of truth, discrimination and feasibility. The sensitivity to change remains to be attested. This study assesses sensitivity to change of the EScSG activity index in patients with early and severe diffuse cutaneous Systemic Sclerosis (dcSSc) treated with rituximab. METHODS: 12-month follow-up (open-label study) of 14 consecutive patients with early dcSSc. Patients received an infusion of two times 1000 mg rituximab at month 0 and 6, together with 100 mg methylprednisolone. Clinical read outs (modified Rodnan skin score [mRSS], lung function and echocardiography) and EScSG activity index were performed at month 0, 3, 6 and 12. Mixed models analyses (MMA) were used to evaluate changes in parameters over time. RESULTS: There was a clinically significant change in skin score with a mean (SD) mRSS of 24.8 (4.44) at baseline and 10.4 (3.12) at month 12 (MMA p<0.001). Also the EScSG activity index decreased significantly, with a mean (SD) of 4.3 (1.79) at baseline and 0.7 (0.83) at month 12 (MMA p<0.001). The estimated mean change of the EScSG activity index was -3.6 (95%CI -4.9; -2.4) over 12 months. Indices of internal organ involvement remained stable throughout the study. CONCLUSIONS: A significant improvement of the EScSG activity index was observed, in line with the significant improvement of the mRSS and the stabilisation of internal organ involvement. To our knowledge, this is the first study to attest sensitivity to change of the EScSG activity index in the subset of 'early' dcSSc