Session Title: Imaging of Rheumatic Diseases Poster III: Other Modalities
Session Type: ACR Poster Session C
Session Time: 9:00AM-11:00AM
Rheumatoid arthritis (RA) induces systemic osteoporosis as well as osteoporotic change in the bones having arthritis by RA. Recently immune complex and anti-citrullinated peptide antibody (ACPA) in the blood of patients with RA have been reported to promote bone absorption through activating osteoclast directly (Negishi-Koga T. Nat Commun 2015, Harre U. J Clin Invest 2012). Bone absorption by ACPA is mainly observed in the trabecular bone of the cancellous bone (Lundberg K. Ann Rheum Dis 2016). In the present study, we investigated the effects of ACPA on bone microstructure of the distal radius in the patients with RA using high-resolution peripheral quantitative computed tomography (HR-pQCT).
Subjects were 95 female patients with DMARDs naïve rheumatoid arthritis without bone erosion (N-group) and 14 female patients with primary osteoporosis (OP-group). The N-group was classified into 52 APCA-negative patients (NN-group, 59±2 y.o.) and 43 APCA-positive patients (PN-group, 58±2 y.o.). For subgroup analyses, 29 subjects in NN-group and 14 subjects in PN-group were selected with excluding active synovitis based on the ultrasonographic findings of the wrist and finger joints. All the patients underwent HR-pQCT in Nagoya Rheumatology Clinic. The bone microstructural parameters to be studied were Tt.vBMD(Total volumetric Bone Mineral Density), Ct(Cortical).vBMD, Tb(Trabecular).vBMD, Tb.Meta.vBMD, Tb.Inn(Inner).vBMD, Tb.N(the number of trabecula), Tb.Th(Thickness), Tb.Sp(Separation), Ct.Th(Thickness), Ct.Po(Porosity), and Ct.PoDm(Pore Diameter).
Significant difference (p<0.05) was observed in averaged left and right Ct.Po (cortical porosity) between NN-group (0.006±0.001) and PN-group (0.010±0.001). In NN-group, the parameters negatively correlated with age were Tt.vBMD, Ct.vBMD, Tb.vBMD, Tb.Meta.vBMD, Tb.Inn.vBMD, Tb.N, and Ct.Th, whereas positively correlated parameters were Ct.Po and Ct.PoDm. PN-group differed from NN-group only in that no significant negative correlation was observed in Tb.Inn.vBMD and Tb.N. These results suggested that ACPA affects the number of trabecula beyond the age-related change. The subgroup analyses excluding the effect of active synovitis represented that the difference between left and right Tb.N was significantly larger in PN-group (0.154±0.057/mm) than in NN-group (0.070±0.014/mm) and OP-group (0.056±0.037/mm) (p<0.05). The results mean ACPA have an left-right asymmetrical effect on the trabecular structure in the distal radius without relation to synovitis, while the pathophysiological mechanisms are not clear.
The results suggested that APCA affects trabecular structure in patients with rheumatoid arthritis independent from the activity of synovitis.
To cite this abstract in AMA style:Tanaka I, Kato T, Kai M, Ogawa K, Mizuno H, Ushikubo M, Izumi K, Oshima H, Tamaki S. Effects of Anti-Citrullinated Peptide Antibody (ACPA) on Bone Microstructure in Rheumatoid Arthritis: A HR-pQCT Study [abstract]. Arthritis Rheumatol. 2018; 70 (suppl 10). https://acrabstracts.org/abstract/effects-of-anti-citrullinated-peptide-antibody-acpa-on-bone-microstructure-in-rheumatoid-arthritis-a-hr-pqct-study/. Accessed December 14, 2019.
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