骨骼肌Osteonectin介导肌源性因子调控促进青少年特发性脊柱侧凸成骨分化OA

Objective:To investigate the expression characteristics of paraspinal muscle-derived osteonectin in adolescent idio-pathic scoliosis(AIS)and its effect on osteogenic differentiation,providing evidence for elucidating aberrant myokine regulation of paraspinal muscles in AIS.Methods:Multiplex immunoassays were used to measure multiple myokines levels in peripheral blood and the concave and convex sides of apical vertebra paraspinal muscle of the control and AIS patients.Immunohistochemistry and qPCR were used to assess protein and mRNA expressions of osteonectin in bilateral paraspinal muscles.An in vitro muscle-bone co-culture model was established using human skeletal muscle myoblasts(HSMM)infected with lentivirus to overexpress osteo-nectin and induce myotube differentiation.After collecting the culture medium supernatant,conditioned medium from osteonectin-overexpressing cells(OE-CM group)and regular HSMM-conditioned medium(CM group)were prepared to culture primary AIS osteoblasts.The effects of osteonectin on osteogenic differentiation were evaluated by alkaline phosphatase(ALP)staining and qPCR.Results:The results of multiplex immunoassays indicated that the levels of osteonectin,fatty acid-binding pro-tein 3,and erythropoietin in the peripheral blood of the AIS patients were significantly decreased compared to the controls(P<0.05).Immunohistochemistry revealed a reduced expression of osteonectin protein in AIS paraspinal muscles,with lower expres-sion on the concave side than the convex side(P<0.01).qPCR and multiplex immunoassays confirmed that the osteonectin mRNA and protein expressions were lower on the concave side than the convex side(P<0.05).The ALP positive staining of pri-mary AIS osteoblasts was significantly enhanced in the OE-CM group compared to the CM group,and qPCR showed that the mRNA levels of ALP,RUNX2,and COL1A1 in osteoblasts of the OE-CM group were significantly upregulated(P<0.001).Conclusion:AIS patients exhibit abnormal expression of multiple myokines in peripheral blood and imbalanced secretory function of the concave and convex sides of paraspinal muscle.Osteonectin promotes osteogenic differentiation of primary AIS osteoblasts by enhancing ALP activity and upregulating osteogenic gene expressions,suggesting that osteonectin-mediated myokine regulation may contribute to the pathogenesis and progression of AIS through modulating bone metabolism.