Arthritis & Rheumatism, Volume 60,
October 2009 Abstract Supplement

The 2009 ACR/ARHP Annual Scientific Meeting
Philadelphia October 16-21, 2009.


Augmentation of IL-21 Receptor by Endothelin-1 Via Endothelin Receptor B in Skin Fibroblasts From Systemic Sclerosis

Kawaguchi,  Yasushi, Takagi,  Kae, Tochimoto,  Akiko, Ota,  Yuko, Katsumata,  Yasuhiro, Gono,  Takahisa, Hara,  Masako

Purpose:

Endothelin (ET)-1 is a vasoconstrictive agent which is involved in endothelial dysfunction in patients with systemic sclerosis (SSc). Recently, it is reported that ET receptor antagonist is a useful treatment for Raynaud's phenomenon and pulmonary arterial hypertension in patients with SSc, and currently we are able to select a selective antagonist for ET receptor A (ETRA) or a dual antagonist for ETRA and ETRB. However, the effects of ET-1 on skin fibroblasts derived from patients with SSc (SSc fibroblasts) remain to be elucidated. In this study, we sought to determine key mediators induced by ET-1 through ETRA and/or ETRB in SSc fibroblasts.

Method:

The expression of ETRA and ETRB in skin fibroblasts was estimated by immunohistochemistry using antibodies against a specific for ETRA or ETRB. We comprehensively analyzed ET-1-induced genes by skin fibroblasts from SSc patients and healthy donors using DNA microarray using Affymetrix GeneChip Human U133 Plus 2.0 Array. Recombinant ET-1, BQ123 as selective ETRA antagonist, BQ788 as selective ETRB antagonist, and PD145065 as dual ETRA and ETRB antagonist were purchased in Sigma. A quantitative analysis of mRNA was performed by a real-time RT-PCR method using a specific TaqMan probe. IL-6, TGF-beta and procollagen type I were measured by commercial ELISA kits.

Results:

Both ETRA and ETRB were expressed in skin fibroblasts constitutively. In addition of optimal ET-1 and BQ-123 in culture media, IL-21 receptor (IL-21R) mRNA was over-expressed in SSc fibroblasts using DNA microarray. This phenomenon was confirmed by real-time RT-PCR. On the other hand, the stimulation of ET-1 with BQ788 or PD145065 failed to induce IL-21R gene expression in SSc fibroblasts. Those findings strongly suggest that IL-21R expression is dependent upon ET-1 signal transduction through ETRB alone. It was reported that IL-21 induced collagen production in intestinal fibroblasts from inflammatory bowel disease. In the next experiments, we investigated whether exogenous IL-21 could induce the fibrogenic mediators and procollagen production in skin fibroblasts. The addition of recombinant IL-21 increased the production of IL-6, TGF-beta, and procollagen type I in culture media of SSc fibroblasts. These phenomena were augmented by pre-stimulation with optimal ET-1.

Conclusion:

ET-1 induced IL-21R through ETRB in SSc skin fibroblasts, and the addition of IL-21 increased the production of IL-6, TGF-beta and procollagen type I, suggesting that blocking ETRB as well as ETRA may play an important role in treatment for systemic sclerosis.

To cite this abstract, please use the following information:
Kawaguchi, Yasushi, Takagi, Kae, Tochimoto, Akiko, Ota, Yuko, Katsumata, Yasuhiro, Gono, Takahisa, et al; Augmentation of IL-21 Receptor by Endothelin-1 Via Endothelin Receptor B in Skin Fibroblasts From Systemic Sclerosis [abstract]. Arthritis Rheum 2009;60 Suppl 10 :1808
DOI: 10.1002/art.26882

Abstract Supplement

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