促肾上腺皮质激素释放激素基因敲除对烧伤后早期小鼠巨噬细胞趋化和组织细菌移位的影响

目的观察促肾上腺皮质素释放激素(CRH)基因敲除的烧伤小鼠腹腔巨噬细胞趋化功能变化及其与组织细菌移位的关系。方法选用3种CRH基因型:野生型(+/+),杂合子(+/-),纯合子(-/-)小鼠,以凝固汽油复制20%的Ⅲ度烧伤模型,伤后6小时和24小时分别以腹腔灌洗法提取腹腔巨噬细胞,观察其趋化功能变化;并以血琼脂平板培养法,观察肝、肺和肠系膜淋巴结细菌移位情况。结果 CRH-/-小鼠烧伤后,腹腔巨噬细胞趋化功能较CRH+/+烧伤小鼠显著减弱,伤后6小时趋化指数(14.05±5.54)低于伤后野生型(27.1±8.61)(P0.05),CRH-/-小鼠肝、肺和肠系膜淋巴结细菌菌落数显著高于CRH+/+和CRH+/-烧伤小鼠,以肠系膜淋巴结最为显著(P0.01);伤后24小时CRH-/-小鼠肠系膜淋巴结菌落数(974±356.75)和细菌移位率(100%)分别显著高于野生组小鼠肠道菌落数(574±191.4)和细菌移位率(40%)(P0.01),伴肠道炎性损伤加重。结论创伤应激早期,CRH基因敲除显著削弱机体天然免疫功能。

Effects of burn injury on chemotaxis in peritoneal macrophages and bacteria translocation in tissues in corticotropin releasing hormone deficient mice

Objective To observe the changes in the chemotaxis in peritoneal macrophages（PMφ） and its relation to the bacteria translocation in corticotrophin-releasing hormone（CRH） knockout mice after burn injury.Methods Three genotypes of CRH mice（＋/＋,＋/-,-/-） were used to prepare the model of a full-thickness dorsal scald burn injury with gelatinized gasoline,which was confirmed as 20%TBSA burn by the pathological determination.At 6 hours and 24 hours after injury,the PMφ were collected for the chemotaxis assay.Also,samples of lung,liver and mesenteric lymph nodes（MLN） were taken under sterile conditions for examining bacteria translocation（BT）.Results The PMφ chemotaxis was significantly inhibited in CRH deficiency mice compared with CRH＋/＋ mice after burn injury.Six hours after burn injury,the chemotactic index in CRH-/-group（14.05±5.54） was less than that in CRH＋/＋ group（27.1±8.61）（P0.05）.Consequently,the number of bacteria colonies due to gut-derived BT in lung,liver and MLN tissues was elevated in CRH-/-group as compared to CRH＋/＋ and CRH＋/-group（P0.05,P0.01）,with the highest in MLN（P0.01）.Twenty-four hours after burn injury,the number of bacteria colonies（974±356.75） and bacteria translocation rate（100%） significantly increased in CRH-/-group compared with CRH＋/＋ group（574±191.4,40%） respectively（P0.01）.CRH knockout mice showed enhancement of inflammatory responses and severe tissue injuries after burn injury.Conclusion CRH knockout could significantly destroy the innate immune functions particularly at the early stage of trauma.