Ye Xin-min, Zhong Nan-shan, Liu Chun-Li, Zhao Jin, Qin Sheng, Chen Ru-chong
Affiliated Nanjing Children's Hospital, Nanjing Medical Univercity, Nanjing 210008, China.
Zhonghua Yi Xue Za Zhi. 2011 Jun 28;91(24):1708-12.
To establish a guinea pig model of acute and postinfectious cough caused by respiratory syncytial virus (RSV) infection and investigate the role of neurogenic inflammation in its pathogenesis.
Fifty guinea pigs were randomly divided into control group and four groups of Days 6, 12, 28 and 42 after RSV inoculation (n = 10 each). The RSV suspension was inoculated by intranasal instillation. Buxco system was used to assess the cough reflex sensitivity (CRS) to inhaled capsaicin. Airway inflammation was determined by bronchoalveolar lavage fluid (BALF) cytology and lung histopathology. RSV antigen and nucleic acid were detected by immunofluorescence and real-time fluorescence quantitative PCR (polymerase chain reaction). After modeling, the content of substance P in homogenate of lung tissue was detected by ELISA (enzyme-linked immunosorbent assay) kit. The level of neurokinins receptor 1 (NK1) mRNA in lung tissue was detected by real-time PCR. The expression of substance P protein in lung tissue was detected by immunohistochemistry. The correlation analyses between CRS and the levels of substance P and NK1 mRNA were performed respectively.
The viral antigen expression could be found in lung tissue of RSV infected guinea pigs. The concentration of RSV RNA content showed a gradually decreasing trend with infection time until 42 days at very low titers. The CRS values were (8.0 ± 1.2), (8.7 ± 2.0), (7.6 ± 1.4) and (6.7 ± 1.2) cough counts at Days 6, 12, 28 and 42 respectively. Compared with (2.5 ± 0.5) cough counts of control group, the CRS to capsaicin increased significantly in all animals with PIV3 inoculation (all P < 0.05) and peaked at Day 12 (P < 0.01). BALF cytology and lung tissue pathology showed airway inflammation during the acute stage of infection without pneumonia. All the contents of substance P in lung tissue homogenates increased markedly in infected groups. The immunohistochemical results of substance P in lung tissue of infected groups showed a distinct brown-yellow positive expression. In addition to Group Day 6, the NK1 mRNA contents of lung tissue in all other infection groups became elevated significantly. The correlation analysis showed a positive correlation between CRS and the levels of substance P and NK1 mRNA (all P < 0.05).
A guinea pig model for cough of RSV infection has been successfully established. The elevated releases of substance P and its receptor may cause neurogenic inflammation. And airway neurogenic inflammation may play a decisive role in the heightened CRS and postinfectious cough induced by RSV.
建立呼吸道合胞病毒（RSV）感染所致豚鼠急性和感染后咳嗽模型，探讨神经源性炎症在其发病机制中的作用。
将50只豚鼠随机分为对照组及RSV接种后第6、12、28和42天4组（每组10只）。通过滴鼻法接种RSV悬液。采用Buxco系统评估吸入辣椒素后的咳嗽反射敏感性（CRS）。通过支气管肺泡灌洗液（BALF）细胞学检查和肺组织病理学检查确定气道炎症。采用免疫荧光法和实时荧光定量PCR（聚合酶链反应）检测RSV抗原和核酸。造模后，采用酶联免疫吸附测定（ELISA）试剂盒检测肺组织匀浆中P物质含量。采用实时PCR检测肺组织中神经激肽受体1（NK1）mRNA水平。采用免疫组织化学法检测肺组织中P物质蛋白表达。分别进行CRS与P物质及NK1 mRNA水平的相关性分析。
在RSV感染的豚鼠肺组织中可发现病毒抗原表达。RSV RNA含量浓度随感染时间呈逐渐下降趋势，至42天时滴度极低。CRS值在第6、12、28和42天分别为（8.0±1.2）、（8.7±2.0）、（7.6±1.4）和（6.7±1.2）次咳嗽计数。与对照组的（2.5±0.5）次咳嗽计数相比，所有接种PIV3的动物对辣椒素的CRS均显著增加（均P<0.05），并在第12天达到峰值（P<0.01）。BALF细胞学检查和肺组织病理学检查显示感染急性期存在气道炎症但无肺炎。感染组肺组织匀浆中P物质含量均显著增加。感染组肺组织中P物质的免疫组织化学结果显示有明显的棕黄色阳性表达。除第6天组外，其他所有感染组肺组织中NK1 mRNA含量均显著升高。相关性分析显示CRS与P物质及NK1 mRNA水平呈正相关（均P<0.05）。
成功建立了RSV感染咳嗽的豚鼠模型。P物质及其受体释放增加可能导致神经源性炎症。气道神经源性炎症可能在RSV诱导的CRS升高和感染后咳嗽中起决定性作用。
