肠道屏障在肠源性侵袭性真菌病中的作用

The preventive effects of intestinal barrier on enterogenic breakthrough invasive candida infection

目的 证实菌群紊乱及急性应激状态下肠道屏障在侵袭性真菌病发病过程中的作用.方法 Wistar大鼠60只,随机分为3组,雌雄不计,第一组为空白对照组;第二组为抗生素组,每日静脉给予头孢曲松100 mg/kg一次;第三组为抗生素＋胰腺炎组,腹腔注射20％ L-精氨酸1.25 mg/kg两次,中间间隔lh,造成急性出血性胰腺炎模型,同样给予头孢曲松,剂量及方法同第二组.分别于实验开始第7天、第14天,各取每组10只大鼠,取心内血、门静脉血、肠内容物、肠壁及肠系膜淋巴结做真菌培养,取肠壁组织及胰腺做病理镜检.若同一实验动物有两个或两个以上样本培养结果阳性,应用18S rDNA内转录间隔区（internal transcribed spacer,ITS）序列分析技术,进行菌株层面的鉴定,确定是否有真菌突破感染.结果 抗生素组及抗生素＋胰腺炎组大鼠的肠内容物真菌培养阳性分别为11例及13例,与对照组比较差异有统计学意义,表明存在菌群紊乱、真菌增殖.在实验第7天及实验第14天两个时间节点,仅有3例发生真菌定植/突破感染,与对照组比较差异无统计学意义.结论 在真菌成为肠道优势菌群的情况下,肠道固有屏障的保护作用,仍可保证急性应激情况下真菌不能突破肠道屏障,造成侵袭性真菌病,肠道屏障的免疫功能在其中可能起重要作用.

Objective To confirm that whether the intestinal barrier can provide protection during invasive fungal disease （IFD） in the stress state and flora disturbance.Methods Sixty Wistar rats （regardless of male and female） were divided into three groups.The first group was blank control group; the second group was antibiotics group,and the rats were intravenous injected with ceftriaxone （100 mg/kg） once a day; the third group was antibiotics and acute pancreatitis （AP） group,and the rats were given 20％ L-ARG by intraperitoneal injection （1.25 mg/kg） twice with the interval of one hour to cause acute hemorrhagic pancreatitis model,meanwhile this group was also given same dose of ceftriaxone.All the three groups were provided the same food,water and living condition.On the 7th day and the 14th of the experiment,ten rats from each group were taken and the samples were rapidly removed under aseptic condition.The samples included intracardiac blood,portal venous blood,intestinal content,intestinal wall and mesenteric lymph nodes.Blood,tissue homogenate and intestinal contents were sent for fungal culture,and microscopic examination for the bowel wall tissue and pancreatic pathological section.If more than one sample from one rat culture was positive,the fungi were separated and identified by the 18S rDNA-ITS sequence analysis technology to determine whether the fungi were breakthrough.Results Positive fungi culture numbers of the intestinal content culture in the antibiotics group and antibiotics ＋ AP group were 11 and 13,respectively,which was significantly different from those in the blank control group.It implies that there exists intestinal flora disturbance,and the fungi have already multiplied.On the 7th and the 14th day of experiment,there were only 3 rats suffered from fungal colonization or breakthrough infection,which showed no statistical differences compared with the blank group.Conclusion When the fungi become the dominant bacterial community,intestinal barrier can still provide protection even acute stress exists,so the fungi cant break through the intestinal barrier to cause IFD.It implies that the immunologic function of intestinal barrier may play an important role in this pathophysiological process.