The expression of nuclear factor κB signal molecule in Kashin-Beck disease and its role in chondrocyte apoptosis

Abstract

Objective To clarify the role of nuclear factor κB (NF-κB) signaling pathway in pathogenesis of Kashin-Beck disease (KBD) by observing the expression of NF-κB p65 in the whole blood samples of patients with KBD and controls, and the expression of NF-κB p65 in C28/I2 chondrocyte, and to analyze the role of NF-κB p65 molecule in chondrocyte apoptosis. Methods Through a case-control study, 161 patients with KBD (KBD group) were selected from Xunyi, Yongshou, Changwu, Linyou, Qianyang and Long counties in KBD endemic areas and 312 healthy people (control group) were matched by age and sex in Shaanxi Province. Venous blood samples were collected from patients and healthy controls, which were anticoagulated and used for determination of NF-κB p65 protein. According to the group design, the model of C28/I2 chondrocyte oxidative damage was established. The experiments were divided into 4 groups including control group (C), tBHP injury group (O, tBHP 300.00 μmol/L), low selenium pre-protection group (OS1, 0.05 mg/L Na2SeO3 + 300.00 μmol/L tBHP), and middle selenium pre- protection group (OS2, 0.10 mg/L Na2SeO3 + 300.00 μmol/L tBHP). Then, cell apoptosis was detected by Hoechst 33342 and reactive oxygen species (ROS) was detected by dichlorfluorescein (DCF) method. The protein was extracted by Trizol method, then protein expression level of NF-κB p65 molecule was detected by Western blotting in whole blood samples and C28/I2 chondrocyte. Results The differences in age and sex were not statistically significant between KBD group and control group (t = 0.336, P > 0.05; χ2 = 0.407, P > 0.05). The protein expression level of NF-κB p65 in KBD group was 1.835 times as high as that of control group (KBD: 0.167 ± 0.026, control: 0.091 ± 0.014, t = 5.147, P < 0.01). Under the fluorescence microscope, chondrocyte showed strong blue fluorescence in tBHP group and the level of ROS (1.219 ± 0.104) was higher than those of low and middle selenium pre-protection groups (0.832 ± 0.077, 0.635 ± 0.070, P < 0.05). The protein expression level of NF-κB p65 in tBHP group (1.563 ± 0.351) was higher than that of control group (0.451 ± 0.069, P < 0.05), and protein levels of NF-κB p65 had a decreasing tendency in low and middle selenium pre-protection groups compared to tBHP group. Conclusion The NF-κB signaling pathway is up-regulated in KBD patients, moreover, chondrocyte experiments show that cell apoptosis is mediated via upregulation of NF-κB p65, which suggests NF-κB signaling pathway may play an important role in pathogenesis of KBD. Key words: Kashin-Beck disease; Chondrocytes; NF-kappaB; Oxidative damage; Protein expression