Abstract:

BACKGROUND: Doxycycline has a certain effect on disc degeneration progression, but the mechanism by which doxycycline inhibits the expression of matrix metalloproteinases (MMPs) in intervertebral disc remains unclear.
OBJECTIVE: To clarify the mechanism by which doxycycline inhibits MMPs expression in intervertebral disc by cytologic experiment in views of intramolecular signal transduction.
METHODS: The human nucleus pulposus cells were cultured in vitro, and 45 000 fibronectin fragments were added into the culture medium to make the degeneration model. The degenerative models were divided according to different action time and different concentrations. The expression levels of type II collagen and MMP13 in each group were detected by western blot assay. After treatment with 10 mg/L doxycycline for 24 hours, the expression levels of ERK1/2, p-ERK1/2, P38, p-P38, JNK, and p-JNK proteins in each group were determined by western blot assay. Based on the above experimental results, the inhibition of ERK and JNK pathways was selected, and the effect of doxycycline on the expression of MAPK pathway protein was detected by western blot assay.
RESULTS AND CONCLUSION: Fibronectin could induce the degeneration of nucleus pulposus cells, showing an increase in expression level of MMP13 and a decrease in expression of type II collagen. Doxycycline could inhibit the expression of MMP13 in degenerative nucleus pulposus cells induced by fibronectin, but not in a time- or dose-dependent manner. After degenerative nucleus pulposus cells induced by fibronectin were treated with doxycycline, the phosphorylation of ERK1/2 and JNK was inhibited, and dual inhibition effectively blocked the activation of ERK1/2 and JNK compared with MAPK inhibitors or doxycycline alone. So doxycycline may block ERK1/2 and JNK activation in the nucleus pulposus cells to inhibit MMP expression, and thus reduce the extracellular matrix degradation. Thereafter, doxycycline exerts a potential role in preventing and treating disc degeneration.

中国组织工程研究杂志出版内容重点：组织构建；骨细胞；软骨细胞；细胞培养；成纤维细胞；血管内皮细胞；骨质疏松；组织工程

Key words: Fibronectins, Doxycycline, Tissue Engineering