15-Lipoxygenase-1 in osteoblasts promotes TGF-β1 expression via inhibiting autophagy in human osteoarthritis.

Background: 15-Lipoxygenase-1 (15-LOX-1) belongs to the lipoxygenase family involved in the inflammatory response and pathological process of various diseases, including osteoarthritis (OA). The overexpression of TGF-β1 in osteoblasts leads to abnormal changes in subchondral bone structure, eventually causing OA. However, the pathogenesis of the disease is poorly defined, and the interaction between 15-LOX-1 and TGF-β1 in osteoblasts has not been evaluated in OA. In this study, the role of 15-LOX-1 in subchondral bone osteoblasts in OA was evaluated.

Method: 15-LOX-1 expression in osteoblasts of the subchondral bone of patients with OA was measured by immunohistochemistry, qRT-PCR, and western blotting. Osteoblasts extracted from the subchondral bone of OA were transfected with 15-LOX-1 siRNA and an overexpression vector. The eff ;ect of 15-LOX-1 on the expression of TGF-β1 in OA osteoblasts was assessed by qRT-PCR and western blotting. The effect of 15-LOX-1 on autophagy via AMPK pathway in OA osteoblasts was evaluated by qRT-PCR, western blotting, and transmission electron microscopy.

Results: The expression levels of 15-LOX-1 and TGF-β1 were higher in OA subchondral bone osteoblast than that in non-OA subchondral bone. 15-LOX-1, which downregulated autophagy by inhibiting AMPK following the activation of mTORC1, upregulated the osteoblast expression of TGF-β1. Treatment with autophagy inhibitors significantly increased the expression levels of TGF-β1 in osteoblasts.

Conclusion: In the present study, our findings suggested that 15-Lipoxygenase-1 in Osteoblasts Promotes TGF-β1 expression via inhibiting autophagy in human Osteoarthritis. These novel results suggested that 15-Lipoxygenase-1 expressed by subchondral bone osteoblasts might be a promising therapeutic target in human OA.