To study the effects of low-dose prednisolone on the osteoclast-regulating proteins osteoprotegerin (OPG) and RANK ligand (RANKL) and on markers of bone resorption, 1CTP generated by MMPs and CTX-1 generated by cathepsin K, in patients with early RA in relation to inflammation and joint destruction.
In 225 patients, who at the start of the first DMARD had been randomized to 7.5 mg prednisolone daily for 2 years, the P-group, or no prednisolone, the NoP-group, OPG and RANKL were analysed at 0-24 months and 1CTP and CTX-1 at 0-12 months. Radiographs of hands and feet were assessed at 0, 1 and 2 years using the modified Sharp-van der Heijde score and radiological progression defined as increase in total Sharp score above 5.8. Data were analysed with a mixed linear model and by the GENMOD procedure.
In the P-group, RANKL and the ratio OPG/RANKL were stable between baseline and 24 months, whereas in the NoP-group, RANKL increased and the ratio OPG/RANKL decreased. CTX-1 decreased significantly more in the P-group. 1CTP decreased over time in both groups, but more in the P-group, P < 0.001, a difference also present in the subgroups of patients in remission. The decrease in 1CTP was associated with less radiological progression after 2 years and displayed a significant interaction with treatment.
Low-dose prednisolone may inhibit progression of joint destruction by interfering with MMP activity, seen as a marked decrease in 1CTP, as well as by impairing osteoclast activation, shown by a stable OPG/RANKL ratio.