鸭疫里默氏菌对鸭盲肠组织形态结构和TLR4信号通路相关基因表达的影响

为探讨鸭疫里默氏菌的可能致病机制，本试验采用显微镜观察鸭疫里默氏菌感染后鸭盲肠组织的形态结构变化，并对肠黏膜厚度、肠绒毛高度及隐窝深度进行测量和统计，采用实时荧光定量PCR法检测鸭疫里默氏菌感染后盲肠组织中TLR4信号通路相关基因的表达变化。病理学观察结果显示，鸭疫里默氏菌感染后肠道结构有明显的损伤，表现为肠绒毛脱落、淤血、出血、淋巴细胞浸润和淋巴细胞增生；统计结果表明，2 d时，鸭疫里默氏菌感染组的肠黏膜厚度（383.58 μm）显著低于对照组（643.39 μm）（P<0.05）；2和5 d时，感染组的肠绒毛高度（173.04和168.68 μm）均显著低于对照组（355.79和276.54 μm）（P<0.05）；9 d时，鸭疫里默氏菌感染组的绒毛高度/隐窝深度的比值（3.42）显著低于对照组（5.34）（P<0.05）。实时荧光定量PCR结果显示，鸭疫里默氏菌感染后2和5 d，TLR4信号通路相关基因TLR4、MD2、MyD88、TRAF6、NF-κB、IL-4和IL-8 mRNA的表达量上调。说明鸭疫里默氏菌感染可导致盲肠的肠黏膜组织物理损伤和炎性病变，且TLR4信号通路参与了该炎性反应过程。

Effect of Riemerella anatipestifer on the Morphological Structure and TLR4 Signal Pathway Related Gene Expression of Cecum in Ducks

In order to investigate the possible pathogenic mechanism of Riemerella anatipestifer,the morphological structure was observed using microscope,the thickness of intestinal mucosa,the height of intestinal villi and the depth of crypt were measured and counted,and the expression of TLR4 signal pathway related genes in the cecum of ducks after infected with Riemerella anatipestifer was detected by Real-time quantitative PCR.Pathological observation results showed that the intestinal structure was damaged after Riemerella anatipestifer infection,which was manifested as intestinal villus shedding,congestion,bleeding and lymphocyte infiltration and lymphocyte proliferation.The statistical results showed that the thickness of intestinal mucosa in infection group (383.58 μm) was significantly lower than that in control group (643.39 μm) at 2 d (P<0.05).The height of intestinal villi in infection group (173.04 and 168.68 μm) were significantly lower than that in control group (355.79 and 276.54 μm) at 2 and 5 day (P<0.05),respectively.The ratio of height of intestinal villi to crypt depth in infection group (3.42) was significantly lower than that of control group (5.34) at 9 d (P<0.05).Real-time quantitative PCR results showed that the expression of TLR4 signal pathway related genes of TLR4,MD2,MyD88,TRAF6,NF-κB,IL-4 and IL-8 mRNA was up-regulated at 2 and 5 d after infection.These results suggested that the infection of Riemerella anatipestifer could lead to the physical damage and inflammatory lesions of the cecum,and TLR4 signal pathway was involved in the inflammatory response process.