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.
Adenosine A2A Receptor Occupancy Promotes Dermal Fibrosis by Modulating FLI1 and CTGF Expression.
Liu3, Hailing, Chan2, Edwin, Fernandez2, Patricia, Cronstein1, Bruce N.
Increased production of extracellular matrix in the skin is the hallmark of Scleroderma. We have previously reported that adenosine, a purine nucleoside produced in ischemic tissue, acting at A2A receptors, enhances dermal collagen production both in vitro and in a murine model of dermal fibrosis, although the mechanism by which adenosine receptor stimulation promotes collagen production is not clear. Fli1 is a known transcriptional repressor of fibrillar collagen genes and connective tissue growth factor (CTGF/CCN2) in dermal fibroblasts. To further clarify the mechanism by which A2A receptor stimulation induces dermal collagen accumulation, we explored the effects of A2A receptor occupancy on Fli1 and downstream mediators of fibroblast matrix production.
Primary human dermal fibroblasts were stimulated with the selective adenosine A2AR agonist CGS21680 (1mM) for varying time periods and message levels (real time-RTPCR) for fli1 and CTGF were quantitated. In addition we measured cell associated and supernatant levels of collagen I and nuclear levels of fli1 by Western Blot.
Adenosine A2A receptor stimulation for 4 hours reduced Fli1 mRNA expression by 47±18% (4 hrs, p<0.05 vs. control, n=4) and reduced nuclear protein levels of Fli1 by 32±13% (24hrs, p<0.05, n=4). Because diminished nuclear fli1 should increase CTGF levels we next examined the effect of A2A receptor stimulation on CTGF mRNA and protein secretion. CTGF mRNA level was increased following A2A receptor stimulation for 8 hours by 3.7 fold. Consistent with the change in CTGF mRNA, CGS21680 stimulated a 4.7 fold increase in CTGF protein secretion at (24 hours) as well (p<0.03, n=4). As expected A2A receptor stimulation increased collagen I secretion (1.8-fold vs. control, p<0.05, n=3) and the increase in collagen production was completely abrogated by an antibody to CTGF (1.1+0.04 fold of control, p<0.05 vs.CGS, n=3) but not by control antiserum (1.6 +0.03fold of control, n=3).
A2AR occupancy promotes dermal matrix production by suppressing expression of the transcriptional repressor fli1 leading to an increase in CTGF expression which acts in an autocrine fashion to stimulate collagen production. These findings further suggest that modulation of A2AR function may be a novel therapeutic target for limiting fibrosis in such conditions as scleroderma.
To cite this abstract, please use the following information:
Liu, Hailing, Chan, Edwin, Fernandez, Patricia, Cronstein, Bruce N.; Adenosine A2A Receptor Occupancy Promotes Dermal Fibrosis by Modulating FLI1 and CTGF Expression. [abstract]. Arthritis Rheum 2010;62 Suppl 10 :600