核因子-κB在分泌性中耳炎早期活性的变化及PDTC对其表达的影响

The Activation of Nuclear Factor κB in the Early Stage of Secretory Otitis Media and the Effect of Pyrrolidine Dithiocarbamate on Its Expression

目的探讨核因子-κB(NF-κB)在分泌性中耳炎(secretory otitis media,SOM)发病机制中的作用,为临床探寻以NF-κB为靶点治疗SOM提供实验依据。方法将76只豚鼠随机分三组:对照组(10只),SOM组(22只)和吡咯醛二硫氨基甲酸(pyrrolidine dithiocarbamate,PDTC)组(44只,其中PDTC1组和PDTC2组各22只)。对照组:右鼓室内注入0.9%生理盐水0.1ml,分别于注射后0h、6h、1d、3d、5d各处死2只。SOM组:经豚鼠右鼓室内注入灭活肺炎链球菌完成SOM造模。PDTC组:右鼓室注入细菌后6h分别给予PDTC50mg/kg(PDTC1组)和200mg/kg(PDTC2组)腹腔注射。SOM组、PDTC组按注入细菌后不同时点0h、6h、1d、3d、5d分别处死5只。通过免疫组织化学的方法检测鼓室黏膜NF-κB、TNF-α和IL-1β的表达,并行组织学观察。结果SOM组:NF-κBp65、TNF-α、IL-1β在注射后6h就有表达,三者均于24h表达最强;3～5d鼓室黏膜明显增厚,大量炎性细胞浸润。PDTC1组:各时间段与OME组表达相似,仅于注射后1d时NF-κBp65表达较低,两者差异有统计学意义(P<0.05)。PDTC2组NF-κBp65、TNF-α、IL-1β在注射后6h表达与SOM组表达相似,1、3、5d有表达,但均低于SOM组(P<0.01),3～5d时鼓室黏膜厚度明显低于SOM组(P<0.01),两组之间的差异具有显著统计学意义。结论①NF-κB信号通路激活可能为SOM发病机制之一,SOM早期NF-κB活化可能与TNF-α和IL-1β上调密切相关。②抗氧化剂PDTC可抑制豚鼠SOM动物模型鼓室黏膜上皮NF-κB的活化,两者存在量效依赖关系,早期足量PDTC干预可明显抑制NF-κB的活化。③抑制NF-κB的活化可下调SOM重要致炎因子TNF-α和IL-1β的表达,从而减轻SOM的病理改变。

Objective To study the role of nuclear factor- κB（NF- κB） in the pathogenesis of secretory otitis media （SOM）, and to provide reliable experiment foundation for chnical treatment. Methods 76 guinea pigs were randomly divided into 3 groups： control group（10）, SOM group（22） and pyrrolidine dithiocarbamate（PDTC） group（44）. The control guinea pigs were sacrificed after the right ears were injected with 0.9% sodium chloride. SOM models were produced by injecting deactivated streptococcus pneumonia into the right tympanic cavities of guinea pigs. In PDTC group, guinea pigs were injected intraperitoneally with PDTC of 50 mg/kg （PDTC1 group） or 200 mg/kg（PDTC2 group）, respectively, 6 hours after the injection of deactivated streptococcus pneumonia. In SOM and PDTC groups, guinea pigs were sacrificed at the interval of 0 h, 6 h, 1 d, 3 d, and 5 d after bacteria injection. The expressions of NF-κB, TNF- u, and IL- 1β in the tympanic membrane were examined by means of immunohistochemistry. Via,sulks In SOM group, NF -κB p65, TNF - α, IL - 1β were detected in the middle ear mucosa as early as 6 h after bacteria injection , and peaked at 24 h. Mucosa was clearly thickened from 3 d to 5 d. In PDTC1 group, the expression of NF - κB p65,TNF- α,IL- 1β was similar to that in SOM group at different times except 24 h after bacteria injection. At 24 hour after injection , the level of NF - κB p65 was lower than that in SOM group（ P 〈 0.01 ）. In PDTC2 group, NF - κB p65, TNF - α,IL- 1β were similar to that in SOM group at 6 h, but the expression was lower than that in SOM group at other times. （P 〈 0.01 ）. The thickness of mucosa of the middle ear was less than that in SOM group. Conclusion The results indicate that NF -κB may play an important role in the pathogenesis of SOM. NF - κB is activated in the early stage of SOM and can facilitate the expression of TNF - α and IL- 1β. PDTC ,a NF - κB inhibitor, can inhibit the expression of inflammatory mediators and the development of SOM. NF - κB inhibitors may have a potential benefit in the treatment of SOM.