Journal Article

Combined use of leptin and mechanical stress has osteogenic effects on ossification of the posterior longitudinal ligament

Zhu, Haifeng, Xie, Ziang, Chen, Jian, Wang, Gangliang, Chen, Shuai, Wang, Jiying

2018

Overview

PurposeTo evaluate the effects of leptin/leptin receptor (LepR) combined with mechanical stress on the development of ossification of the posterior longitudinal ligament (OPLL), which is a disease characterized by ectopic bone formation of the posterior longitudinal ligament (PLL) and can lead to radiculopathy and myelopathy.MethodsSix human samples of the PLL were analyzed for the expression of leptin and LepR by RT-PCR and western blotting. PLL cells were stimulated with leptin and mechanical stress delivered via a Flexcell tension system, and osteogenic differentiation was evaluated by RT-PCR and western blotting analysis of osteogenic marker expression as well as by alkaline phosphatase (ALP) staining and alizarin red S staining. Activation of mitogen-activated protein kinase (MAPK), Janus kinase (JAK) 2-signal transducer, activator of transcription (STAT) 3 and phosphatidylinositol 3-kinase (PI3K)–Akt was evaluated by western blotting.ResultsSamples from the OPLL group had higher LepR mRNA and protein levels and lower leptin levels than those from healthy controls. Exposure to leptin and Flexcell increased the number of ALP-positive cells and calcium nodules in a dose-dependent manner; this effect was accompanied by upregulation of the osteogenic markers osteocalcin, runt-related transcription factor 2 (RUNX2) and osteopontin. Extracellular signal-regulated kinase, P38 MAPK, JAK2, STAT3, PI3K and Akt signaling, was also activated by the combined effects of leptin and mechanical stress.ConclusionsLeptin and LepR are differentially expressed in OPLL tissues, and the combined use of leptin/LepR and mechanical stress promotes osteogenic differentiation of PLL cells via MAPK, JAK2-STAT3 and PI3K/Akt signaling.Graphical abstractThese slides can be retrieved under Electronic Supplementary Material.

• Publisher: Springer Nature B.V
• Subject: 1-Phosphatidylinositol 3-kinase / AKT protein / Alkaline phosphatase / Bone growth / Calcium / Cbfa-1 protein / Central nervous system diseases / Extracellular signal-regulated kinase / Janus kinase / Janus kinase 2 / Kinases / Ligaments / MAP kinase / Nodules / Ossification / Ossification (ectopic) / Osteocalcin / Osteogenesis / Osteopontin / Polymerase chain reaction / Protein kinase / Spinal cord / Stat3 protein / Western blotting