Dynamic expression and significance of Bcl6 in fibroblast-like synoviocytes induced osteoclast differentiation and activation in rheumatoid arthritis / 中华风湿病学杂志

ABSTRACT

Objective To investigate the dynamic expression and significance of B cell lymphoma (Bcl) 6 in fibroblast-like synoviocytes (FLS) induced osteoclast differentiation and activation in rheumatoid arthritis (RA) patients.Methods RA-FLS were co-cultured with peripheral blood monocytes (PBMCs) from healthy volunteers in the medium containing M-CSF.Bcl6 protein and mRNA in osteoclasts and their precursors were determined by immunofluorescence and Real-time PCR at day 0,7,14 and 21,respectively.Osteoclasts were identified by tartrate-resistant acid phosphatase (TRAP) staining.Bone resorption activity of osteoclasts was determined by bone slices stained with toluidine blue.Kruskal-Wallis H and Bonferroni were used for statistical analysis.Results ① Immunofluorescence staining and TRAP staining showed that Bcl6 protein was mainly expressed in the nuclei of PBMCs.After co-cultured with RA-FLS for 7 days,some PBMCs differentiated into macrophages and a few differentiated to TRAP-positive multinucleated osteoclasts,and the total Bcl6 protein expression in osteoclasts and their precursors were increased.At day 14,the total Bcl6 protein expression was increased further.At day 21,the Bcl6 protein expression in nuclei of osteoclasts was decreased while PBMCs were differentiated into osteoclasts,and total Bcl6 protein expression was decreased.②Real-time PCR showed that Bcl6 mRNA expression in osteoclasts and their precursors at day 7 tended to increase than that at day 0 (x2=3.429,P＞0.05).At day 14 after co-cultured with RA-FLS,Bcl6 mRNA expression in osteoclasts and their precursors was significantly higher than that at day 0 (x2=5.333,P=0.045).At day 21,the expression of Bcl6 mRNA was significantly lower than that at day 14 (x2=6.023,P=0.038).Conclusion Bcl6 may be involved in osteoclast differentiation and activation,and may play a role in the inflammatory status in the process of differentiation from PBMCs to macrophages.Further studies are needed to establish the mechanisms.