脂多糖诱导成骨细胞中CHI3L1表达的分子机制研究

The Molecular Mechanism of LPS-induced CHI3L1 Expression

慢性骨髓炎因其病程漫长、易出现并发症以及复发率高成为临床上棘手的难题,其主要致病原因是金黄色葡萄球菌等革兰氏阴性菌感染.脂多糖(LPS)是革兰氏阴性细菌细胞壁的重要成分,用LPS在体外刺激骨组织相关细胞在一定程度上可以模拟骨髓炎患者的病理特征.实时荧光定量PCR和Western blot等试验结果表明,在骨髓炎患者的骨组织和LPS刺激的成骨细胞中,几丁质酶家族成员CHI3L1的表达均有明显升高.核因子κB(NF-κB)萤光素酶报告载体检测结果显示,LPS能诱导细胞的NF-κB活化,NF-κB活化抑制剂Bay11-7082能抑制LPS诱导的CHI3L1表达升高.用抗肿瘤坏死因子α(TNF-α)的抗体预处理细胞,或采用siRNA干扰的方法抑制TNF-α受体的表达,都能明显抑制LPS诱导的CHI3L1表达上调.同时,NF-κB活化抑制剂Bay11-7082预处理细胞能抑制LPS对TNF-α表达的诱导作用.结果提示,LPS通过激活NF-κB诱导TNF-α分泌上调,刺激CHI3L1表达.提出骨髓炎及脂多糖刺激条件下CHI3L1表达上调,并在细胞水平上初步探讨了脂多糖诱导CHI3L1表达的分子机制.

Treatment of chronic osteomyelitis has become a difficult problem in clinical medicine due to its extended pathological process, high occurrence of complication and recurrence of disease. The major pathogenesis mechanism is Gram-negative bacteria infection, such as staphylococci. LPS is an important substance found in the cell wall of Gram-negative bacteria and administration of LPS to skeleton relevant cells in vitro could simulate the pathological characteristics of osteomyelitis patients. The results of quantitative real-time PCR and Western blot showed that CHI3L1 was up-regulated obviously in the infected bone tissues of osteomyelitis patients and LPS-stimulated osteoblasts. Analysis of the luciferase activity of NF-κB reporter gene vector revealed that LPS could activate NF-κB. Bay11-7082, an inhibitor of NF-κB activation, suppressed the elevation of CHI3L1 expression induced by LPS. Pre-incubation of osteoblasts with anti-TNF-α antibody or silencing TNF-α receptor expression by siRNA inhibited the induction effect of LPS on CHI3L1. Inhibition of NF-κB activation also prevented up-regulation of TNF-α induced by LPS. In conclusion, LPS stimulated TNF-α expression through activating NF-κB, then TNF-α induced CHI3L1 expression. It was demonstrated for the first time that CHI3L1 expression is promoted in osteomyelitis and LPS-treated osteoblasts and investigates the molecular mechanism of LPS-induced CHI3L1 expression in osteoblasts.