程序性死亡受体1及其配体在大鼠牙周炎发展中的时序性表达及意义

目的 研究程序性死亡受体1（programmed death-1,PD-1）及其配体（programmed death ligand 1,PD-L1）在大鼠牙周炎发展中的时序性表达及意义。方法 SD大鼠随机分为对照组和模型组,按照测定时间不同随机分为4个亚组,分别为A组（造模1周）、B组（造模2周）、C组（造模3周）和D组（造模4周）,每个亚组各8只大鼠。对各模型组大鼠采用“丝线结扎+接种牙龈卟啉单胞菌脂多糖”的方法建立大鼠上颌实验性牙周炎模型,对各组大鼠牙周进行组织病理检查和骨吸收面积测定,采用RT-PCR法对各组大鼠牙周组织中肿瘤坏死因子α（tumor necrosis factor alpha, TNF-α）、白细胞介素1β（interleukin-1, IL-1β）、白细胞介素6（interleukin 6, IL-6）及转化生长因子β（transforming growth factor beta, TGF-β）mRNA进行测定,采用Western免疫印迹法对各组大鼠牙周组织PD-1和PD-L1蛋白表达水平进行测定。采用SPSS 22.0 软件包对数据进行统计学分析。结果 建模期间,模型组大鼠第一磨牙釉-牙骨质界到牙槽嵴顶(amelocemental junction-alveolar crest, ACJ-AC)距离和根分叉区骨吸收面积逐渐增加（P<0.05）,与相应时间点对照组相比,差异有统计学意义（P<0.01）。建模期间,模型组大鼠牙周组织中TNF-α、IL-1β和IL-6 mRNA表达水平持续升高（P<0.05）,TGF-β mRNA表达水平持续降低（P<0.05）,并且与相应时间点对照组相比,差异有统计学意义（P<0.01）。建模期间,模型组大鼠牙周组织中PD-1和PD-L1蛋白表达水平持续升高（P<0.05）,与相应时间点对照组相比,差异显著（P<0.01）。疾病发展过程中,大鼠牙周组织中PD-1和PD-L1蛋白表达水平与牙周组织炎症介质TNF-α和IL-6 mRNA表达水平持续正相关（P<0.05）。结论 PD-1作为免疫抑制分子与其受体PD-L1可促进牙周炎症进展,其作用可能通过调节TNF-α和IL-6的表达来实现。调节PD-1和PD-L1的表达,可作为治疗牙周炎症相关性疾病的新靶点。

Temporal expression of PD-1 and PD-L1 during the development of experimental periodontitis in rats and its implications

PURPOSE: To study the temporal expression of programmed death receptor 1 (PD-1) and its ligand (PD-L1) in the development of periodontitis in rats. METHODS: SD rats were randomly divided into control group and model group, and 4 subgroups were divided in each model group according to the time of measurement: group A (1 week), group B (2 weeks), group C (3 weeks) and group D (4 weeks). There were 8 rats in each subgroup. Maxillary periodontitis models were made by using "thread ligation + vaccination LPS-PG" in rats. Periodontal tissue specimens were examined and bone resorption areas were determined in each group. Tumor necrosis factor alpha (TNF-α), interleukin-1 (IL-1β), interleukin 6 (IL-6) and transforming growth factor beta (TGF-β) mRNA in periodontal tissue in each group were determined by RT-PCR method. PD-1 and PD-L1 protein expression in periodontal tissues in each group were determined by Western blotting. The data were analyzed by SPSS 22.0 software package. RESULTS: During modeling period, amelocemental junction-alveolar crest(ACJ-AC) distance and bone resorption area of the first molar in model group gradually increased (P<0.05), which were significantly different from the control group at the corresponding time point (P<0.01). During modeling period, TNF-α, IL-1β and IL-6 mRNA level in periodontal tissues in the model group was continuously increased(P<0.05), and TGF-β mRNA was continuously decreased(P<0.05), which was significantly different from the control group at the corresponding time point(P<0.01). During disease progress, PD-1 and PD-L1 protein level in periodontal tissues in each model group was continuously increased(P<0.05), which was significantly different from the control group at the corresponding time point (P<0.01); and PD-1 and PD-L1 protein levels in periodontal tissues in each model group was positively correlated to TNF-α and IL-6 mRNA levels(P<0.01). CONCLUSIONS: PD-1, as an immunosuppressive molecule and its receptor PD-L1, can promote the progression of periodontal inflammation, and its effect may be achieved by regulating the expression of TNF-α and IL-6.Regulating the expression of PD-1 and PD-L1 may be a new target for the treatment of periodontitis.