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目的:研究哮喘大鼠Toll样受体4(TLR4)表达变化及其对嗜酸性粒细胞(EOS)凋亡的作用机制。方法:清洁级SD大鼠27只,随机分为对照组(A)、哮喘组(B)、地塞米松(D)组,每组9只。用OVA致敏与激发复制哮喘模型。光镜观察肺组织病理变化;BALF中炎症细胞计数;ELISA测定血清IL-10含量;原位杂交测定肺组织TLR4mRNA表达;TUNEL法检测EOS凋亡。结果:(1)光镜观察:B组见肺组织大量炎症细胞侵润,支气管黏液腺增生;D组上述现象明显减轻。(2)BALF中细胞总数、EOS绝对计数和EOS占细胞总数的百分比:B组均明显高于A组(均P<0.01);D组均明显低于B组(均P<0.01)。(3)血清IL-10含量:B组与A组有显著差异(P<0.01);D组显著低于B组(P<0.01)。(4)TLR4mRNA的检测:TLR4在肺组织表达B组与A组差异无统计学意义(P>0.05);D组显著高于B组(P<0.01)。(5)EOS凋亡率检测结果,B组与A组比差异显著(P<0.05);D组显著高于B组(P<0.01)。相关分析显示,TLR4mRNA表达与EOS凋亡率呈显著正相关(r=0.612,P<0.01)。结论:DXM上调血清中IL-10水平,诱导肺组织EOS凋亡,可能与TLR4信号通路有关。
Objective: To investigate the expression of Toll-like receptor 4 (TLR4) and its mechanism of apoptosis in eosinophils (EOS) in asthmatic rats. Methods: Twenty-seven SD rats were randomly divided into control group (A), asthma group (B) and dexamethasone group (D), with 9 rats in each group. Sensitized and challenged with OVA to replicate asthma model. The pathological changes of lung tissue were observed with light microscope. The number of inflammatory cells in BALF was counted. The content of IL-10 in serum was measured by ELISA. The expression of TLR4 mRNA in lung tissue was detected by in situ hybridization. Results: (1) Light microscopy: In group B, a large number of infiltration of inflammatory cells and bronchial mucosal gland hyperplasia were observed in lung tissue. The above phenomenon in group D was significantly reduced. (2) The percentage of total cells, absolute EOS and EOS in BALF were significantly higher in group B than in group A (all P <0.01); group D were significantly lower than those in group B (all P <0.01). (3) Serum IL-10 content: There was a significant difference between group B and group A (P <0.01); Group D was significantly lower than group B (P <0.01). (4) The detection of TLR4 mRNA: there was no significant difference between group B and group A (P> 0.05); group D was significantly higher than group B (P <0.01). (5) The apoptosis rate of EOS was significantly different between group B and group A (P <0.05), and group D was significantly higher than group B (P <0.01). Correlation analysis showed that the expression of TLR4 mRNA was positively correlated with the apoptosis rate of EOS (r = 0.612, P <0.01). Conclusion: DXM may up-regulate the level of IL-10 in serum and induce the apoptosis of EOS in lung tissue, which may be related to the TLR4 signaling pathway.