THURSDAY, April 12 (HealthDay News) -- Patients with rheumatoid arthritis that is resistant to corticosteroids have cells that produce more corticosteroid receptor-β than patients who are steroid sensitive, according to study findings published in the April issue of Rheumatology. The β form of the receptor increases after stimulation and is not inhibited by hydrocortisone.
Ian C. Chikanza, M.D., and colleagues from the University of London in the United Kingdom, examined the expression of the corticosteroid receptors α and β in peripheral blood mononuclear cells from steroid-sensitive and steroid-resistant patients with rheumatoid arthritis.
The researchers found that the expression of corticosteroid receptor-β and the ratio of the β/α receptor was higher in cells from steroid-resistant patients. Both parameters increased when the cells were stimulated with concanavalin-A, which was not inhibited by hydrocortisone. A significantly smaller percentage of cells from steroid-sensitive patients stained positively for the β receptor, while cells from steroid-resistant patients stained more intensely for the β receptor.
"We show for the first time that corticosteroid receptor-β is overexpressed in steroid-resistant rheumatoid arthritis patients and that hydrocortisone fails to inhibit concanavalin-A stimulated increase in corticosteroid receptor-β mRNA in steroid-resistant rheumatoid arthritis patients," Chikanza and colleagues conclude. "This mechanism may contribute in part to the corticosteroid hyporesponsiveness seen in some rheumatoid arthritis patients."
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