Arthritis & Rheumatism, Volume 63,
November 2011 Abstract Supplement

Abstracts of the American College of
Rheumatology/Association of Rheumatology Health Professionals
Annual Scientific Meeting
Chicago, Illinois November 4-9, 2011.


Enhanced IL-6 Trans-Signalling in Early dcSSc May Drive Fibrotic Response Via JAK2/STAT3 Signalling Pathways.

Khan1,  Korsa, Shiwen2,  Xu, Abraham3,  David J., Denton4,  Christopher P., Ong5,  Voon

UCL medical School, London, United Kingdom
Royal Free Hospital, London, United Kingdom
Centre for Rheumatology and Connective Tissue Diseases, UCL Medical School, London, United Kingdom
UCL Medical School, London, United Kingdom
UCL Medical School, London, England

Background/Purpose:

We have reported that a subgroup of diffuse cutaneous systemic sclerosis (dcSSc) with elevated serum IL-6 levels is associated with high modified Rodnan skin score (mRSS). In this study, we examine its potential profibrotic effects and downstream signalling pathways in patients with early dcSSc.

Methods:

Using skin biopsies obtained from patients with early dcSSc (n=10, mean disease duration, Mean±SEM: 35±9.5 months) and healthy controls (n=5), colocalisation of IL-6 with aSMA and phospho-STAT3 were determined with immunohistochemical techniques. The effect of IL-6 trans-signalling on extracellular matrix(ECM) production was assessed on fibroblasts grown by explant culture from skin of SSc patients and healthy controls. Downstream signalling pathways regulated by IL-6 and soluble IL-6 receptor was examined using pharmacological inhibitors. These were stimulated overnight with IL-6 (0–50ng/ml) and sIL-6R (20ng/ml).

Results:

There was greater dermal IL-6 expression in patients with early dcSSc compared to healthy controls. IL-6 accumulation was strongly associated with vascular structures and perivascular inflammatory infiltrate in 8/10 patients. Compared to controls, immunostaining for downstream IL-6 signaling molecules showed an increased expression of pSTAT3 in all cases with early dSSc particularly in the perivascular inflammatory foci and vascular structures. Similar co localisation of IL-6 and aSMA was observed in all skin sections with early dcSSc.

To explore the effect of IL-6 trans-signalling on ECM synthesis, incubation of dermal fibroblasts from healthy controls with either IL-6 alone (25–50 ng/ml) or sIL-6R (20ng/ml) alone had no effect on collagen, aSMA and CTGF production. However, there was upregulation of collagen synthesis in normal fibroblasts(34.3±2.45 vs 9.88±1.54 Densitometry Image Unit (DIU) controls, p < 0.05) in response to IL-6 (25ng/ml) and sIL-6R (20ng/ml). Similar induction of aSMA and CTGF by 12-fold and 15-fold (p<0.01) respectively were observed in normal fibroblasts incubated with a combination of IL-6 and sIL-6R. The IL-6 trans-signalling activation of collagen synthesis in normal fibroblasts was abrogated by AG490 (3.6-fold) and S3I-201 (3.5-fold, p<0.02), that targets JAK2 and STAT3 signalling pathways respectively.

Time-course analysis indicates that IL-6 trans-signalling induces maximal activation of pJAK2 and pSTAT3 at 45 min and this was diminished by 2 hours in normal fibroblasts. Constitutive activation of both JAK2 and STAT3 pathways was observed in SSc fibroblasts and further activation by the addition of IL-6 and sIL-6R occurred at 15 minutes and this was sustained at 1 hour.

Conclusion:

Our results confirm overexpression of IL-6 in dcSSc and demonstrate a potent profibrotic effect of IL-6 trans-signalling via the JAK2/STAT3 pathways. The data also provide rationale that targeting the IL-6 trans-signalling as a potential fibrotic therapy in SSc.

To cite this abstract, please use the following information:
Khan, Korsa, Shiwen, Xu, Abraham, David J., Denton, Christopher P., Ong, Voon; Enhanced IL-6 Trans-Signalling in Early dcSSc May Drive Fibrotic Response Via JAK2/STAT3 Signalling Pathways. [abstract]. Arthritis Rheum 2011;63 Suppl 10 :2324
DOI:

Abstract Supplement

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