A defective hypothalamo-pituitary-adrenal axis response to inflammatory cytokines may contribute to the pathophysiology of rheumatoid arthritis (RA). The purpose of this study was to define further the mechanisms responsible for this dysregulation. Six normal individuals and seven patients with active RA were recruited and given an oral dose of dexamethasone at 2300 h the evening before the study. The next day, an i.v. catheter was fitted at 1300 h. Blood samples were collected between 1400 h and 1700 h before and after infusion (at 1500 h) of corticotrophin releasing factor (CRF). Plasma was separated and stored at-20 degrees C before radioimmunoassay for ACTH, cortisol and dihydroepiandrosterone (DHEA). Before the CRF challenge, ACTH and cortisol were significantly increased and DHEA significantly decreased in the patients with RA compared with the controls. Neither ACTH nor DHEA was significantly altered after CRF infusion. Control individuals did not mount a cortisol response to infusion of CRF. Similarly, four of the patients with RA did not respond to CRF. However, in contrast to the controls, three of the patients mounted an immediate and sustained cortisol response after receiving CRF. These data reveal that three of the seven patients with RA were able to escape from dexamethasone suppression and mount a cortisol response to CRF challenge. This suggests that there may be a subpopulation of patients with RA who have impaired glucocorticoid feedback. The implications of this alteration for disease progression remain to be determined.
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- Author: Kirwan JR x
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