Relationship between insulin-like growth factor-1 receptor down-regulation and Kaschin-Beck disease / 中华地方病学杂志

ABSTRACT

Objective To observe the expression level of insulin-like growth factor-1 receptor (IGF-1R) in the cartilage tissue of children with Kaschin-Beck disease (KBD) and T-2 toxin-poisoned rats under low selenium condition,and the effect of IGF-1R inhibitor on apoptosis of human normal chondrocytes (C28/I2 cells),and to investigate the role of IGF-1R in the pathogenesis of KBD.Methods The knuckles of dead children (5 cases) in the KBD areas,car accident death and congenital 6 finger deformity operation children (5 cases) in non-KBD areas in Shaanxi were collected,the expression of IGF-1R in the articular cartilage was detected by immunohistochemistry.Thirty-two male Sprague-Dawley rats with a body mass of 60-80 g were selected,according to the body mass,they were divided into the routine feed group (selenium content101.5 μg/kg) and the low-selenium feed group (selenium content1.1 μg/kg) by random number table method,16 rats in each group.After 30 days of feeding,the routine feed group was divided into control group and T-2 toxin group (100 ng·kg-1·d-1),the low-selenium feed group was divided into low selenium group and low selenium + T-2 toxin group,8 rats in each group,the expression of IGF-1R in the articular cartilage of the left knee joint was detected by immunohistochemistry after 30 days of feeding.C28/I2 cells were cultured in vitro and treated with T-2 toxin 0 (control),6,12,and 24 μg/L,and each concentration of T-2 toxin was accompanied with sodium selenite (+ 0.1 mg/L) for 72 h.Meanwhile,IGF-1R inhibitor with 0 (control),250,500,and 1 000 μg/L was treated on C28/I2 cells for 48 h.The expression levels of IGF-1R mRNA and protein in chondrocytes were detected by Real-time PCR and Western blotting,and the apoptosis of chondrocytes was detected by flow cytometry.Results Compared with the control group [(100.00 ± 0.00)％,(100.00 ± 0.00)％],the expression rates of IGF-1R positive cells in articular cartilage surface and middle layers [(72.71 ± 4.75)％,(36.33 ± 4.32)％] of children in KBD group were significantly reduced (t =12.852,32.650,P ＜ 0.01).Compared with control group [(100.00 ± 0.00)％,(100.00 ± 0.00)％,(100.00 ± 0.00)％],the expression rates of IGF-1R positive cells in articular cartilage middle layer [(20.83 ± 2.69)％,(26.45 ± 2.84)％,(20.34 ± 1.82)％],deep layer [(33.55 ± 5.66)％,(48.89 ± 8.39)％,(25.51 ± 7.50)％],and the expression rates of IGF-1R positive cells [(47.50 ± 1.47)％,(28.66 ± 3.58)％,(40.52 ± 6.78)％] in the hypertrophic layer of the metaphyseal plate of rats in low selenium,T-2 toxin,and low selenium + T-2 toxin groups were significantly reduced (P ＜ 0.01).C28/I2 cells were cultured in vitro,compared with the control group,IGF-1R mRNA and protein expression levels in each T-2 toxin groups were significantly reduced (P ＜ 0.05).The expression levels of IGF-1R mRNA (1.95 ± 0.35,2.44 ± 0.17,2.40 ± 0.15) in 6,12,24 μg/L T-2 toxin + 0.1 mg/L selenium groups were significantly higher than those in T-2 toxin groups (0.80 ± 0.08,0.63 ± 0.08,0.61 ± 0.11,t =-12.259,-11.279,-13.371,P＜ 0.05).The expression levels of IGF-1R protein (1.67 ± 0.70,1.07 ± 0.26) in 6,12 μg/L T-2 toxin + 0.1 mg/L selenium groups were significantly higher than those in T-2 toxin groups (0.52 ± 0.05,0.72 ± 0.05,t =-25.977,-10.776,P ＜ 0.05).Compared with the control group [(5.33 ± 0.85)％,(4.03 ± 1.15)％],C28/I2 cells early apoptosis rates [(8.26 ± 1.51)％,(13.00 ± 0.72)％,(13.19 ± 1.05)％] in each of IGF-1R inhibitor groups,and late apoptosis rates [(8.50 ± 0.71)％,(14.21 ± 1.10)％] in 500,1 000 μg/L IGF-1R inhibitor groups were increased significantly (P ＜ 0.05).Conclusions The expressions of IGF-1R in the cartilage tissue of KBD children and T-2 toxin-poisoned rats under low selenium condition are decreased.T-2 toxin decreases the expression of IGF-1R in chondrocytes,and selenium can partly inhibit the effect of T-2 toxin on IGF-1R.Down-regulation of IGF-1R causes chondrocyte apoptosis,and it may play an important role in KBD chondrocyte apoptosis.