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.

TRIAL REGISTRATION

ClinicalTrials.gov Registration, http://clinicaltrials.gov, number NCT00379431.

A20 inhibition of STAT1 expression in myeloid cells: a novel endogenous regulatory mechanism preventing development of enthesitis

Objectives

A20 is an important endogenous regulator of inflammation. Single nucleotide polymorphisms in A20 have been associated with various immune-mediated inflammatory diseases, and cell-specific deletion of A20 results in diverse inflammatory phenotypes. Our goal was to delineate the underlying mechanisms of joint inflammation in myeloid-specific A20-deficient mice (A20myelKO mice).

Methods

Inflammation in A20myelKO mice was assessed in a time-dependent manner. Western blot analysis and quantitative PCR analysis were performed on bone marrow-derived macrophages from A20myelKO and littermate control mice to study the effect of A20 on STAT1/STAT3 expression and STAT1/STAT3-dependent gene transcription in myeloid cells. The in vivo role of Janus kinase-Signal Transducer and Activator of Transcription (JAK-STAT) signalling in the development of enthesitis in A20myelKO mice was assessed following administration of a JAK inhibitor versus placebo control.

Results

Enthesitis was found to be an early inflammatory lesion in A20myelKO mice. A20 negatively modulated STAT1-dependent, but generally not STAT3-dependent gene transcription in myeloid cells by suppressing STAT1 but not STAT3 expression, both in unstimulated conditions and after interferon-γ or interleukin-6 stimulation. The increase in STAT1 gene transcription in the absence of A20 was shown to be JAK-STAT-dependent. Moreover, JAK inhibition in vivo resulted in significant reduction of enthesitis, both clinically and histopathologically.

Conclusions

Our data reveal an important and novel interplay between myeloid cells and tissue resident cells at entheseal sites that is regulated by A20. In the absence of A20, STAT1 but not STAT3 expression is enhanced leading to STAT1-dependent inflammation. Therefore, A20 acts as a novel endogenous regulator of STAT1 that prevents onset of enthesitis.

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.