Effect of Zinc in Attaching and Effacing E. coli Infection

描述(由申请人提供)：在对几个大洲贫困儿童的研究中，锌已被证明可以缩短腹泻疾病的持续时间和严重程度。尽管锌的这些有益作用最初归因于纠正营养不良儿童的锌缺乏，但研究表明，即使在研究前血清锌水平正常的儿童中，锌的有益作用也是有益的。对健康实验动物和培养细胞的肠道病原体的研究也表明，在非缺锌动物或条件下，锌具有保护作用。在我们的实验室中，我们发现锌在体外对几种重要的人肠道致病性大肠杆菌菌株的毒力因子的产生具有强烈的抑制作用。然后，我们将这些观察扩展到兔EPEC菌株，并发现了类似的结果。兔是EPEC感染的天然宿主，是检测体内锌效应的良好动物模型。现在我们也有体外数据表明，锌也抑制志贺氏菌毒素大肠杆菌(STEC，也称为肠出血性大肠杆菌，或EHEC)的毒力。在人类来源的EPEC、兔EPEC和STEC中，锌减少细菌产生的毒力因子，包括粘附素、分泌的效应蛋白和志贺毒素(STX)。我们建议进一步研究锌在体外和体内对A/E大肠杆菌感染的影响。具体目标有3个：具体目标1：在不同的生长条件下(以及在抗生素存在的情况下)，测定锌在体外对大肠杆菌(包括EPEC、RePEc和STEC)的附着和清除的直接作用。具体目的2.确认并进一步明确锌对兔回肠结扎肠段A/E大肠杆菌体内感染的影响，并检测锌对这些肠段STEC感染的影响。具体目标3：确定体内补锌是否能保护兔免受RePEc和STEC的胃部感染。除了研究锌对临床病程和肠道病理的影响外，我们还将研究锌是否对STEC引起的肠道外病变(特别是肾脏损害)具有保护作用。在这些研究中，我们将使用一种新的出血性结肠炎(HC)和溶血性尿毒症综合征(HUS)模型，该模型在荷兰带兔身上发展，挑战表达STX1或STX2的RePEc菌株。 与公共卫生相关：“附着和去除大肠杆菌”包括两组引起腹泻的大肠杆菌，肠致病性大肠杆菌(EPEC)和肠出血性大肠杆菌(EHEC，也称为志贺产毒大肠杆菌，简称STEC)。由于食源性暴发，EHEC，如O157：H7菌株，已得到广泛宣传。锌抑制了这两组大肠杆菌的毒力，我们希望进一步研究锌是否可以用于治疗这些感染。

DESCRIPTION (provided by applicant): Zinc has been shown to reduce the duration and severity of diarrheal diseases in studies of poor children on several continents. Although these beneficial effects of zinc were first attributed to correction of a zinc deficiency in malnourished children, studies have shown beneficial zinc effects even in children with normal serum zinc levels before study. Studies of enteric pathogens in healthy experimental animals and cultured cell assays have also shown protective effects of zinc in non-zinc deficient animals or conditions. In our laboratories we discovered that zinc strongly inhibits the production of several important virulence factors human enteropathogenic E. coli strains in vitro. We then extended those observations to rabbit EPEC strains and found similar results. Rabbits are natural hosts for EPEC infection, so they constitute a good animal model for us to test zinc efficacy in vivo. Now we also have in vitro data showing that zinc also inhibits virulence in Shiga-toxigenic E. coli (STEC, also known as enterohemorrhagic E. coli, or EHEC). In human-derived EPEC, rabbit EPEC, and STEC, zinc decreases the bacterial production of virulence factors, including adhesins, secreted effector proteins and Shiga toxin (Stx). We propose to further examine the effect of zinc on A/E E.coli infections both in vitro and in vivo. There are 3 specific aims: Specific Aim 1: Determine the direct effects of zinc on attaching and effacing E. coli (including EPEC, REPEC and STEC) in vitro under different growth conditions (and in the presence of antibiotics). Specific Aim 2.: To confirm and further define the effects of zinc on A/E E.coli infection in vivo in ligated rabbit ileal loops, and to examine its effect on STEC infections in these loops. Specific Aim 3: Determine if zinc administration in vivo can protect rabbits against orogastric infections with REPEC and STEC. In addition to examining the effects of zinc on clinical disease course and intestinal pathology, we will also examine if zinc can protect against extra-intestinal pathology induced by STEC (especially kidney damage). For these studies we will use a new model of hemorrhagic colitis (HC) and hemolytic uremic syndrome (HUS) which develops in Dutch Belted rabbits challenged with REPEC strains expressing Stx1 or Stx2. PUBLIC HEALTH RELEVANCE: "Attaching and Effacing E. coli" includes 2 groups of diarrhea-producing E. coli, enteropathogenic E. coli (EPEC) and enterohemorrhagic E. coli (EHEC, also called Shiga toxigenic E. coli, or STEC). EHEC, such as strain O157:H7, has received wide publicity due to foodborne outbreaks. Zinc inhibits the virulence of both of these groups of E. coli, and we wish to study zinc further to see if it could be used as a treatment for these infections.