Background The increasing role of B-cells in the pathogenesis and management of RA, the common occurrence of postmenopausal osteoporosis with RA and the suggested responsibility of BAFF in autoantibodies production with affection of bone density were main motives to research in this area
Objectives The aim of the present work was to study the serum concentration of BAFF in relation to postmenopausal low bone mass (LBM) associated with RA compared to those without RA and to study its relation to the bone turnover markers and bone mineral density. Comparing the results with an RA group with normal BMD was considered with the healthy control subjects. Relation of the findings to intake of hydroxychloroquine (HCQ) was considered.
Methods The study included 68 postmenopausal LBM patients 34 with RA and another 34 without. Thirty age-matched postmenopausal healthy subjects were included as control. The laboratory investigations performed for the patients and control, included markers of bone formation; Osteocalcin (OC) and bone-specific alkaline phosphatase (b-ALP) and a marker of bone resorption; N- terminal cross linked telopeptides of type I collagen. Serum BAFF level was assessed in patients and control. Bone mineral density was quantified by dual energy x-ray absorptiometry (DXA).
Results The bone turnover markers and DXA t scores were significantly different in the patients compared to control. The level of BAFF was significantly higher in RA patient with LBM (1.58±1.17 ng/ml) compared to patients with LBM only (1.03±1.04 ng/ml) (p=0.045) but was insignificantly different from the level in RA patients with normal BMD (1.29±0.87 ng/ml). BAFF significantly correlated with the DXA t score over distal radius and negatively correlated with the b-ALP. In the present study, the t score of the hip was significantly improved and the BAFF level significantly lower in those RA patients receiving hydroxychloroquine (HCQ).
Conclusions the responsibility of B-cells and BAFF in the pathogenesis of postmenopausal LBM (osteopenia/osteoporosis) is shown in addition to their established role in RA. Hydroxychloroquine has a potential effect in reducing bone loss and should be considered among the first line armamentarium regimens in the management of RA cases. Introduction of new therapeutic options that selectively inhibit B-cells and target BAFF in osteoporosis should be considered especially when associated with RA.
Disclosure of Interest None declared