Full Papers
Comprehensive evaluation of bone structural and microarchitectural changes in rheumatoid arthritis treated with baricitinib using HR-pQCT, imaging, and biomarker analyses
T. Michitsuji1, N. Iwamoto2, K. Chiba3, K. Shiraishi4, K. Watanabe5, N. Oki6, A. Okada7, T. Koga8, S. Kawashiri9, M. Tamai10, M. Osaki11, A. Kawakami12
- Department of Immunology and Rheumatology, Division of Advanced Preventive Medical Sciences, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan.
- Department of Immunology and Rheumatology, Division of Advanced Preventive Medical Sciences, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan. naoki-iwa@nagasaki-u.ac.jp
- Department of Orthopaedic Surgery, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan.
- Department of Orthopaedic Surgery, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan.
- Department of Orthopaedic Surgery, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan.
- Department of Radiological Sciences, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan.
- Department of Rheumatology, National Hospital Organization Nagasaki Medical Center, Omura, Nagasaki, Japan.
- Department of Immunology and Rheumatology, Division of Advanced Preventive Medical Sciences, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan.
- Department of Immunology and Rheumatology, Division of Advanced Preventive Medical Sciences, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki; and Center for Collaborative Medical Education and Development, Nagasaki University Institute of Biomedical Sciences, Nagasaki, Japan.
- Department of Immunology and Rheumatology, Division of Advanced Preventive Medical Sciences, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan.
- Department of Orthopaedic Surgery, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan.
- Department of Immunology and Rheumatology, Division of Advanced Preventive Medical Sciences, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan.
CER19797
Full Papers
Received: 12/02/2026
Accepted : 19/05/2026
In Press: 18/06/2026
Abstract
OBJECTIVES:
To comprehensively evaluate the effects of baricitinib on bone structure and bone-related biomarkers in patients with rheumatoid arthritis (RA) using high-resolution peripheral quantitative computed tomography (HR-pQCT).
METHODS:
RA patients initiating baricitinib were enrolled in this prospective study. Bone structure in the second and third metacarpal heads was assessed using HR-pQCT at baseline and after 6 and 12 months. Synovitis, tenosynovitis, and osteitis were evaluated using ultrasound and MRI. Serum cytokines, chemokines, and bone-related biomarkers were analysed through a multiplex bead assay.
RESULTS:
Fourteen patients with RA who initiated baricitinib were included in the analysis. No new bone erosions were detected during the 12-month period, and several pre-existing erosions showed partial repair. HR-pQCT revealed favourable trends in trabecular bone parameters, including increases in volumetric bone mineral density and trabecular thickness. Serum osteoprotegerin (OPG) significantly increased, while osteopontin (OPN) and interleukin-23 (IL-23) decreased, indicating suppression of the IL-23/Th17/RANKL axis and enhancement of bone preservation pathways. In addition, baricitinib modulated inflammatory mediators, including increased Eotaxin and decreased MCP-3. These changes were accompanied by improvements in synovitis, osteitis, and tenosynovitis assessed by multiple imaging modalities.
CONCLUSIONS:
Baricitinib treatment inhibited the progression of bone erosions and also induced partial repair in some lesions, accompanied by improvements in periarticular bone microarchitecture. These favourable effects on bone structure were paralleled by beneficial modulation of bone-related and inflammatory biomarkers. Collectively, these findings indicate that baricitinib contributes to the prevention of joint destruction primarily through structural preservation, supported by parallel molecular mechanisms.
