Arthritis & Rheumatism, Volume 62,
November 2010 Abstract Supplement

Abstracts of the American College of
Rheumatology/Association of Rheumatology Health Professionals
Annual Scientific Meeting
Atlanta, Georgia November 6-11, 2010.


The Notch Pathway Controls Fibroblast Activation and Tissue Fibrosis in Systemic Sclerosis.

Dees2,  Clara, Zerr2,  Pawel, Tomcik2,  Michal, Beyer2,  Christian, Horn2,  Angelika, Akhmetshina2,  Alfiya, Palumbo2,  Katrin

Center of Experimental Rheumatology and Zurich Center of Integrative Human Physiology, University Hospital Zurich, Switzerland
Department of Internal Medicine 3, University Erlangen-Nuremberg, Germany
Laboratory of Neurosciences, National Institute on Aging Intramural Research Program, Baltimore, MD

Purpose:

Tissue fibrosis caused by pathological activation of fibroblasts with increased synthesis of extracellular matrix components is a major hallmark of systemic sclerosis (SSc) and other fibrotic diseases. Pathologic activation of Notch signaling has been implicated in the pathogenesis of human malignancies. The aims of the present study were to investigate whether Notch contributes to the uncontrolled activation of fibroblasts and tissue fibrosis in SSc and to evaluate the therapeutic potential of Notch inhibition for the treatment of fibrosis.

Methods:

Activation of the Notch pathway was analyzed by immunohistochemistry in skin sections of SSc patients and healthy volunteers. Dermal fibroblasts were stimulated with recombinant human Jagged-1 (Jag-1) Fc Chimera and incubated with the g-secretase inhibitor DAPT. Fibroblast activation was determined by staining for a-smooth muscle actin (aSMA) and stress fibers. Inhibition of Notch signaling for the treatment of fibrosis was evaluated in the mouse model of bleomycin-induced dermal fibrosis and in tight-skin-1 (tsk-1) mice.

Results:

Notch signaling is activated in skin of SSc patients as analyzed by immunohistochemistry. Moreover, this activation persisted in cultured fibroblasts in vitro with significantly elevated levels of activated Notch-1, its ligand Jag-1 and its target gene hes-1. Activation of the Notch pathway by stimulation with recombinant Jag-1 potently induced differentiation of resting fibroblasts into myofibroblasts with increased levels of aSMA and formation of stress fibers. In addition, Jag-1 increased collagen synthesis to 294 ± 37 % (p < 0.05) which was prevented upon pre-incubation with DAPT. Consistent with the selective activation of Notch signaling in SSc fibroblasts, incubation of dermal fibroblasts with DAPT decreased the basal collagen synthesis only in SSc but not in healthy dermal fibroblasts. In the mouse model of bleomycin-induced dermal fibrosis, treatment with DAPT completely prevented dermal thickening upon bleomycin-challenge (p < 0.05). Inhibition of g-secretase prevented also hypodermal thickening in tsk-1 mice with a mean reduction of hypodermal thickness by 75 ± 4 % (p < 0.05). Overexpression of a Notch-1 antisense construct confirmed the results obtained with the chemical inhibitor. Bleomycin-induced dermal thickening was reduced by 85 ± 19 % (p < 0.05) and hypodermal thickness in tsk-1 mice decreased by 51 ± 11 % (p < 0.05). Of note, treatment with DAPT not only prevented fibrosis but induced significant regression of dermal thickening below pre-treatment levels in a modified model of established bleomycin-induced skin fibrosis.

Conclusion:

We demonstrate that the Notch pathway is activated in fibrotic skin, induces myofibroblast differentiation and stimulates the release of collagen. Inhibition of Notch signaling exerts potent anti-fibrotic effects in preclinical models suggesting that targeting Notch signaling might be a promising molecular approach for anti-fibrotic therapy.

To cite this abstract, please use the following information:
Dees, Clara, Zerr, Pawel, Tomcik, Michal, Beyer, Christian, Horn, Angelika, Akhmetshina, Alfiya, et al; The Notch Pathway Controls Fibroblast Activation and Tissue Fibrosis in Systemic Sclerosis. [abstract]. Arthritis Rheum 2010;62 Suppl 10 :672
DOI: 10.1002/art.28440

Abstract Supplement

Meeting Menu

2010 ACR/ARHP