ABSTRACT
OBJECTIVES: Inflammatory mediators such as interleukin 6 (IL-6) are known to activate catabolic responses in chondrocytes during osteoarthritis (OA). This study aimed to investigate the role of a downstream target gene of IL-6, the serine protease inhibitor SerpinA3N, in the development of cartilage damage in OA. METHODS: RNA sequencing was performed in murine primary chondrocytes treated with IL-6, and identified target genes were confirmed in human and murine OA cartilage samples. Male cartilage-specific Serpina3n-deficient mice and control mice underwent meniscectomy (MNX) or sham surgery at 10 weeks of age. Intra-articular injections of SerpinA3N or sivelestat (an inhibitor of leucocyte elastase (LE), a substrate for SerpinA3N) were performed in wild-type mice after MNX. Joint damage was assessed 3-9 weeks after surgery by histology and micro-CT. The effect of sivelestat was assessed in cartilage explants exposed to macrophage-derived conditioned media. RESULTS: RNA sequencing revealed that SerpinA3N is a major target gene of IL-6 in chondrocytes. The expression of SerpinA3N is increased in OA cartilage. Conditional loss of SerpinA3N in chondrocytes aggravated OA in mice, while intra-articular injection of SerpinA3N limited joint damage. Chondrocytes did not produce serine proteases targeted by SerpinA3N. By contrast, macrophages produced LE on IL-6 stimulation. Sivelestat limited the cartilage catabolism induced by conditioned media derived from IL-6-stimulated macrophages. Additionally, an intra-articular injection of sivelestat is protected against OA in the MNX model. CONCLUSIONS: SerpinA3N protects cartilage against catabolic factors produced by macrophages, including LE. SerpinA3N and LE represent new therapeutic targets to dampen cartilage damage in OA.
ABSTRACT
OBJECTIVE: Study the therapeutic maintenance, efficacy and reasons for tocilizumab stop in daily practice. PATIENTS AND METHODS: A monocentric, retrospective study of patients treated for rheumatoid arthritis who received at least one TCZ infusion between January 2009 and December 2015. Therapeutic maintenance was evaluated using the Kaplan-Meier method. The efficacy of TCZ was measured by DAS28 and the EULAR response. Reasons for stopping and new treatment lines were also collected. RESULTS: Of the 88 patients (83% women and 17% men) who were included, the mean age was 54±12.5 years. There were 75% positive rheumatoid factors and 76% positive anti-CCP. The mean duration of the follow-up was 31 months. TCZ was used as monotherapy in 24 patients (27%). Before the introduction of TCZ, the mean DAS28 was 5.07±1.32. The EULAR response at 1 year in patients still under treatment (n=63) was obtained in 59 (93.7%) patients, 46 good responders and 13 moderate responders. Therapeutic maintenance was 82.9%, 72.5%, 68.7% and 57.2%, respectively, at 12, 24, 36 and 54 months. Twenty-eight patients (32%) followed TCZ, 10 for adverse events and 14 for ineffectiveness. Abatacept was the main new therapeutic line. CONCLUSION: The therapeutic maintenance of TCZ in common practice over a long period of follow-up is similar to pivotal studies. Efficacy data are reassuring in the long-term.