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.


Enhanced Expression of Ephrins and Thrombospondins in the Dermis of Patients with Early Diffuse Systemic Sclerosis: Potential Contribution to Perturbed Angiogenesis and Fibrosis.

Avouac6,  Jerome, Clemessy2,  Maud, Distler8,  Jorg H. W., Gasc2,  Jean Marie, Ruiz1,  Barbara, Vacher-Lavenu3,  Marie Cecile, Wipff6,  Julien

INSERM U781, Necker Hospital, Paris, France
INSERM U833 and Collège de France, Paris, France
Paris Descartes University, Pathophysiology Department, Cochin Hospital, Paris, France
Paris Descartes University, Rheumatology A Department, Cochin Hospital, APHP, Paris, France
Paris Descartes University, Rheumatology A Department, Cochin Hospital, APHP, Paris and INSERM U781, Necker Hospital, Paris, France
Paris Descartes University, Rheumatology A Department, Cochin Hospital, APHP, Paris and INSERM U781, Necker Hospital, Paris, France
U.V.S.Q University, Biochemistry, Hormonology and Molecular Genetics Department, Ambroise Paré Hospital, AP-HP, Boulogne, France
University of Erlangen, Erlangen, Germany

Objective:

Ephrins have emerged as essential regulators of angiogenesis and thrombospondins are inhibitors of angiogenesis and strong promoters of fibrosis that are both involved in systemic sclerosis (SSc). Our aim was to investigate whether ephrins and thrombospondins contribute to the dysregulation of angiogenic homeostasis related to systemic sclerosis (SSc) and to the pathologic activation of SSc dermal fibroblasts.

Methods:

Skin biopsies were obtained from 8 patients with early diffuse cutaneous subset and from 4 healthy volunteers, matched for age and sex with SSc patients. SSc Skin biopsies were taken from both clinically involved and non-involved skin. Dermal fibroblasts were cultured from control and clinically involved and non-involved SSc skin. Ephrin (EphB4 and EphrinB2) and thrombospondin (TSP-1 and 2) mRNA and protein levels were analyzed in skin tissue respectively by in situ hybridization and immunohistochemistry. EphB4/EphrinB2 and TSP-1/2 mRNA and protein levels were assessed in SSc and control dermal fibroblasts in basal conditions and after stimulation by TGFb or 6 hours of hypoxic exposure. Ephrin and thrombospondin expression was also determined in SSc and control dermal fibroblasts cultured with a pan-specific TGFb blocking antibody.

Results:

Increased mRNA and protein levels of EphrinB2 and EphB4 were detected in clinically involved skin of SSc patients. EphrinB2, but not EphB4, was also upregulated in clinically non-involved skin. The expression of Ephrins was restricted to the vessels. Low levels of EphrinB2 and EPhB4 were detected in control and SSc cultured dermal fibroblasts, in basal conditions or after stimulation by TGFb or hypoxia, suggesting that fibroblasts do not produce ephrins. TSP-1 and 2 were upregulated in SSc skin biopsies taken from both involved and non-involved skin. Their expression was mainly detected in the extracellular matrix located at the periphery of vessels. The overactivation of TSP-1 and TSP-2 persisted in cultured SSc dermal fibroblasts issued from involved and non-involved skin, and might contribute to the activated phenotype of SSc fibroblasts. Culture with TGFb blocking antibody markedly reduced the upregulated expression of TSP-1 and TSP-2 in SSc dermal fibroblasts, but had little effect on healthy fibroblasts. Moreover, stimulation of healthy dermal fibroblasts with TGFb, but not with hypoxic exposure, led to TSP-1 and TSP-2 activation.

Conclusion:

We investigated for the first time the expression of EphB4/EphrinB2 and TSP-1/TSP-2 expression in the skin and in dermal fibroblasts of patients affected by SSc. EphB4 and EphrinB2 are upregulated in clinically involved skin of SSc patients, suggesting their participation in SSc perturbed angiogenesis. TSP-1 and 2 are upregulated in both clinically involved and non-involved SSc skin and are constitutively activated in a TGFb dependent/hypoxia independent manner in SSc dermal fibroblasts. Further studies are now warranted to assess the role of TSP-1 and TSP-2 respectively in the early activation of TGFb and in the assembly of extracellular matrix proteins accumulated under the overproduction of TGFb.

To cite this abstract, please use the following information:
Avouac, Jerome, Clemessy, Maud, Distler, Jorg H. W., Gasc, Jean Marie, Ruiz, Barbara, Vacher-Lavenu, Marie Cecile, et al; Enhanced Expression of Ephrins and Thrombospondins in the Dermis of Patients with Early Diffuse Systemic Sclerosis: Potential Contribution to Perturbed Angiogenesis and Fibrosis. [abstract]. Arthritis Rheum 2010;62 Suppl 10 :1991
DOI: 10.1002/art.29756

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