The Influence of a 2-year Anti-TNF-α Therapy on Bone and Cartilage Metabolism in Rheumatoid Arthritis and Ankylosing Spondylitis

Introduction: The understanding of the complex pathogenesis of rheumatoid arthritis (RA) and ankylosing spondylitis (AS) has been improved by intensive research in recent years, but a causal therapy is still not available. Newer therapeutic strategies target cytokine-dependent mechanisms of these inflammatory-rheumatic diseases to facilitate disease remission. The aim of this study was to evaluate the influence of an anti-TNF-alpha therapy with infliximab on bone and cartilage metabolism in patients with RA and AS over a period of 2 years. Patients and Methods: 18 RA patients (mean age 62 years) and 16 AS patients (mean age 48 years) with inadequate response to therapy were examined and treated with 3-5 mg/kg body weight infliximab i.v. The effects of infliximab on bone and cartilage metabolism were determined by biochemical markers such as bone-specific alkaline phosphatase (BAP), tartrate-resistant acid phosphatase (TRAP5b), type II collagen carboxy-propeptide (CP-II), type II collagen neoepitope (C2C), and parameters of bone mineral density. Furthermore parameters of activity and function (Disease Activity Score 28 - DAS28, Bath Ankylosing Spondylitis Disease Activity Index - BASDAI, Health Assessment Questionnaire - HAQ) and pain (visual analogue scale - VAS) were evaluated. These results were compared between baseline and after 24 months. Furthermore radiological follow-up of the hands and feet were performed in patients with RA and X-rays of the axial skeleton in AS patients. Results: The patients with RA and AS showed a significant decrease of BAP, TRAP5b and C2C as well as a significant increase of CP-II, and the axial bone mineral density. The DAS28 in RA patients, the BASDAI-Index in AS patients and in both groups the HAQ score and pain (VAS) decreased significantly. In addition, the X-rays of hands, feet and the axial skeleton showed no radiomorphological progression. Conclusion: The treatment with infliximab in patients with RA and AS results in a sufficient suppression of inflammation and protects bone and cartilage with substantial disease-modifying effects.