To study the systemic effects of intra-articular (IA) glucocorticoid (GC) injections in juvenile idiopathic arthritis (JIA).
The study group comprised 21 JIA patients being treated with IA methylprednisolone [MP (n = 15) or MP plus triamcinolone hexacetonide (THA) (n = 6)] prescribed on clinical indications. The systemic effect of MP was assessed by measuring circulating glucocorticoid bioactivity (GBA) with a recombinant cell transactivation assay 7 and 24 h after the IA injections, and after 2 months. The systemic immunological responses were studied with a novel assay for testing patient serum-induced changes in the secretion of interferon (IFN)-γ and interleukin (IL)-5 from target cells.
Administration of IA GC induced serum GBA (p = 0.001) and suppressed circulating cortisol levels (p = 0.002) 7 h after the injection. Serum withdrawn 24 h after the IA injection induced less IL-5 secretion from mitogen-activated target cells when compared with pre-treatment sera (p = 0.036). This decrease in target cell T helper (Th)2 response (IL-5) was MP dose related (r = -0.550, p = 0.018). High IL-5 secretion from target cells prior to the IA injections was associated with good clinical outcome at 2 months, seen as a low number of active (p = 0.044) and restricted joints (p = 0.049).
IA GC injections have systemic effects that are reflected in the serum as an immediate elevation of GBA, a decrease of endogenous cortisol as well as a suppressive effect of patient serum on target cell IL-5 secretion. These systemic effects may play a role in the attenuation of disease activity.