Endocrine Abstracts

Joint stiffness in rheumatoid arthritis (RA) is worse in the morning and has been associated with increased secretion of the pro-inflammatory cytokine IL-6 and in decreased secretion of cortisol, suggesting that clinical symptoms may be related to hormonal and immune circadian variations. We measured 24 h plasma profiles of IL-6 and cortisol in RA patients to determine any changes in IL-6 and cortisol following a two week course of prednisone administered orally in a specially designed timed-release tablet (TRT).

Nine patients with active RA were clinically assessed and had 24 h blood sampling before and after a 2 wk course of TRT prednisone (5 mg per day). Patients took the TRT orally at 2200 h and the prednisone was released at 0200 h. Changes in circadian variation in cortisol and IL-6 and clinical measures were compared using random coefficient regression modeling and Wilcoxon matched-pairs signed-rank test.

Significant alterations in circadian profiles and concentrations of IL-6 and cortisol were observed following TRT prednisone. The peak value of IL-6 fell from 42.5 to 21.3 pg/ml, and occurred earlier (0134 h compared to 0827 h) (P<0.005). Following TRT prednisone, the peak value of cortisol increased from 14.1 μg/dl to 19.3 μg/dl and the trough fell from 2.9 μg/dl to 2.1 μg/dl (P<0.001). There was a close correlation between reduction of IL-6 and improvement in morning joint stiffness following TRT. We propose that these changes in IL-6 and cortisol, prior to the onset of morning joint stiffness, are functionally important in mediating the improvement in joint stiffness following prednisone in RA patients.

Declaration of interest: The authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project.

Funding: This work was supported, however funding details unavailable.