The Effect And Mechanism Of Inhibited Osteocytic TGF-β/Smads Of Subchondral Bone On Knee Osteoarthritis In Mice

Objectives to detect the effect of osteocytic TGF-βin subchondral bone on knee osteoarthritis in mouse,and if it was modulated by the coupled bone sorption and formation.Methods mice with down-regulated osteocytic TGF-β are obtained by cre/loxp technology and induced osteoarthritis(OA)models were generated by using destabilization of the medial meniscus(DMM)on right knee and sham operation on left knee in 10-wk-old mice.8 week and 16 week after operation,saferin o/ green staining was performed to test the damage of cartilage;BMD and micro-CT were used to examine the bone volume and micro-architecture of subchondral bone;ALP and TRAP staining were performed to test bone sorption and formation in subchondral bone;additionally,real-time PCR and western blot were used to detect the specific osteogenic and osteoclastic markers;Moreover,ALP,alizarin red and TRAP staining were used to test osteoblastic and osteoclastic differentiation when BMSCs were co-cultured with osteocytes in vitro.Results compared with sham group,the OARSI score in mice with DMM markedly higher increased,while it got modified when TGF-βin osteoctyes was downregulated.BMD on subcondral bone was no significant differentiation,however,the micro-architecture features were changed after DMM treatment.ALP and TRAP staining shown that the turnover rate of bone sorption and formation on subcondral bone were accelerated after DMM treatment,but down-regulation of osteocytic TGF-β might alleviate it.Additionally,the specific osteoblastic and osteoclastic markers demonstrated that down-regulated osteocytic TGF-beta could decrease bone sorption and formation.Moreover,ALP,alizarin red and TRAP staining in vitro found that conditional knockdown TGF-beta in osteocytes could inhibit BMSCs osteoclastic and osteoblastic differentiation when co-cultured.Conclusions down-regulated osteocytic TGF-β in mice could inhibit the turnover rate of bone sorption and formation,maintain the micro-architecture of subchondral bone,preserve the degeneration of knee cartilage,and finally alleviate progression of osteoarthritis.