TOLL样受体4对肺炎衣原体感染小鼠肺组织炎性递质的影响

Influence of Toll-like receptor 4 on inflammatory media in the lungs of mice infected with chlamydia pneumoniae

目的:通过应用肺炎衣原体(Cpn)分别感染Toll样受体4(TLR4)基因突变型(C3H/HeJ品系,TLR4-/-)小鼠和野生型(C3H/HeN品系,TLR4+/+)小鼠,探讨TLR4在Cpn感染后炎性反应中的作用。方法:TLR4突变型和野生型小鼠各60只分为4组(突变型对照组、突变型感染组、野生型对照组和野生型感染组),每组30只,随机分为5个时间点(即第1 d、第4 d、第7 d、第14 d和第21 d)。两感染组经鼻腔接种Cpn,两对照组则经鼻腔吸入二磷酸蔗糖(2SP)缓冲液,在上述预定时间点处死动物,采用ELISA检测肺组织肿瘤坏死因子α(TNF-α)和白细胞介素(IL)-10的含量,并行病理观察,测定肺湿质量/干质量比值(W/D)。结果:小鼠接种Cpn后,肺组织病理早期以中性粒细胞浸润、后期则以淋巴细胞浸润为主,且有肺泡间隔增宽、肺泡水肿和出血等炎性改变,炎症第21 d趋于吸收。突变型感染组TNF-α的含量自第1 d开始升高,第4 d达峰值,随后呈下降趋势,至第21 d仍高于正常,第7d、14 d和21 d含量分别为(1.10±0.12)、(0.72±0.12)和(0.52±0.10)pg/mg,低于野生型感染组的(1.30±0.16)、(1.01±0.19)和(0.71±0.08)pg/mg。突变型感染组IL-10的含量第4 d开始升高,第7 d达峰值,随后呈下降趋势,至第21 d仍高于正常。第14 d和第21 d的含量分别为(1.08±0.08)和(0.64±0.10)pg/mg,低于野生型感染组的(1.34±0.10)和(0.79±0.05)pg/mg。突变型感染组的W/D值(3.00±0.28)在第21 d高于野生型感染组(2.72±0.16)。结论:TLR4在感染后期至少部分参与Cpn感染小鼠的肺组织炎性递质生成。

Objective： To investigate the role of Toll-like receptor 4 （TLR4） in the inflammatory reaction in the mouse model of Chlamydia pneumoniae （Cpn） infection. Methods： We divided 60 TLR4 mutant C3H/HeJ and 60 wild type C3H/HeN male mice into 4 groups： a mutant control （M）, a mutant infection （ M ＋ I）, a wild type control （W） and a wild type infection （ W ＋ I） group, each randomly as- signed to 5 scheduled time points （1 d, 4 d, 7 d, 14 d and 21 d）. The animals in the M and W groups were intranasally inoculated with 2-sucrose phosphate （2SP） buffer, while those in the M ＋ I and W ＋ I groups with Cpn. All the mice were killed and their lung tissues were sampled on the above time points. The levels of TNF-α and IL-10 in the lung tissues were detected by enzyme-linked immunosobent assay （ELISA）, histopathological examinations were performed, and the wet / dry weight （W / D） ratio was determined. Results： After Cpn inoculation, the lung tissues were characterized by patchy interstitial pneumonitis, predominantly infiltrated with neutrophil leukocytes in the earlier （7 d） stage and with lymphocytes in the later （ 14 d ） stage. In the M ＋ I group, the levels of TNF-α were elevated at 1 d （ [0.78 ±0.06] pg/mg）, peaked at 4 d （ [ 1.22 ± 0.12] pg/mg） and then began to decrease, but was still higher than normal at 21 d; they were （1.10 ±0. 12, 0.72 ＋ O. 12 and 0.52 ± O. 10） pg/mg at 7, 14 and 21 d, significantly lower than in the W＋I group （[1.30 ± 0.16], [1.01 ± 0.19]and [0.71 ± 0.08] pg/mg, P 〈 0.05）. The levels of IL-10 in the M ＋I group were increased at4 d, peaked at 7 d （[1.32 ± 0.17 ] pg/mg） and began to decrease at 14 d; they were （1.08 ± 0.08 and 0.64 ＋ 0.10） pg/mg at ld and 21 d, significantly reduced as compared with the W ＋ I group （ [ 1.34 ± 0.10] and [0.79± 0.05] pg/mg, P 〈 0.05）. The W/D ratio of the M ＋I group was （3.00 ±0.28） at 21 d, significantly higher than that of the M ＋ I group （2.72 ± 0.16）. Conclusion ： TLR4 is in- volved, at least partially, in the formation of inflammatory media in the lung tissues of Cpninfected mice.