PREGNANCY INDUCED REACTIVATION OF ARRESTED HOOKWORMS

怀孕导致捕获的钩虫重新激活

基本信息

批准号：
6626343
负责人：
PREMA ARASU
金额：
$ 16.26万
依托单位：
NORTH CAROLINA STATE UNIVERSITY RALEIGH
依托单位国家：
美国
项目类别：
财政年份：
1999
资助国家：
美国
起止时间：
1999-01-01 至 2004-12-31
项目状态：
已结题

项目摘要

Developmental arrest within a host allows many parasitic nematodes to evade adverse external conditions and action of chemotherapeutic agents, but to reactivate at opportune periods. Our long range goal is to elucidate the molecular mechanisms that trigger reactivation of arrested parasites and to identify strategies of preventing neonatally- transmitted infections as well as self-reinfections (e.g. Strongyloides in immunodeficient individuals). This study is focused on pregnancy- induced reactivation and transmammary transmission of arrested Ancylostoma larvae because hookworms infect about 1.2 billion people, and in young children, the protein loss and anemia can contribute to physical and cognitive deficiencies. We have previously shown that larval reactivation cannot be attributed to a state of generalized immunosuppression as is associated with pregnancy; rather, hormonally- induced cytokine changes appear to be critical. Using an in vitro reactivation assay, we find that TGF-beta stimulates larval feeding at levels comparable to that of serum stimulation. Further, the stimulatory effect of serum can be significantly neutralized with antibodies to TGF-beta. Earlier studies have shown that exogenous estrogen and prolactin stimulate a resurgence of larvae in the milk of latently-infected, lactating dogs, and more recent work indicates that these hormones specifically upregulate the levels of TGF-beta2 during late pregnancy and lactation. In addition, TGF-beta. signaling is clearly crucial to reactivation of arrested larvae of the soil nematode, Caenorhabditis elegans. The objective of this proposal is to use the mouse/A. caninum model to test the hypothesis that host-derived TGF-beta particularly the beta2 isoform which is upregulated by estrogen and prolactin, triggers the reactivation and transmammary transmission of developmentally-arrested larvae during late pregnancy and lactation. We propose to test our hypothesis with 3 specific aims: 1. Characterize the A. caninum homologues of the TGF-beta receptor and ligand to evaluate binding of mammalian TGF-beta to the parasite receptor. 2. Use the in vivo model of infection to determine TGF-beta levels, and larval status and burden in skeletal muscle versus mammary tissue during different phases of pregnancy and lactation, and determine whether larval reactivation is stimulated by estrogen and prolactin. 3. Use in vitro co-cultures of tissue larvae with muscle versus mammary cells to distinguish the differential effects of estrogen, prolactin and staged pregnancy sera on larval reactivation, and determine if neutralizing antibodies to TGF-beta inhibit reactivation. These studies will provide important results for the development of therapeutic strategies to eradicate latent parasitic infections.

宿主内的发育停滞使得许多寄生线虫能够逃避不利的外部条件和化疗药物的作用，但要在适当的时候重新激活。我们的长期目标是阐明触发停滞再激活的分子机制寄生虫并确定预防新生儿感染的策略传播感染以及自身再感染（例如类圆线虫）免疫缺陷个体）。这项研究的重点是怀孕—— 诱导再激活和经乳房传播钩虫幼虫，因为钩虫感染了大约 12 亿人，对于幼儿来说，蛋白质流失和贫血可能会导致身体和认知缺陷。我们之前已经证明了幼虫的重新激活不能归因于普遍状态与怀孕相关的免疫抑制；相反，荷尔蒙—— 诱导的细胞因子变化似乎至关重要。使用体外再激活测定中，我们发现 TGF-β 刺激幼虫摄食水平与血清刺激水平相当。此外，血清的刺激作用可以被显着中和 TGF-β 抗体。早期研究表明，外源性雌激素和催乳素刺激幼虫在乳汁中复活潜伏感染的、哺乳期的狗以及最近的工作表明这些激素在生长过程中特异性上调 TGF-β2 的水平妊娠晚期和哺乳期。此外，TGF-β。信号传递是显然对于重新激活被捕获的土壤线虫幼虫至关重要，秀丽隐杆线虫。该提案的目标是利用鼠标/A.犬模型来检验宿主衍生的 TGF-β 的假设特别是β2亚型，它被雌激素上调催乳素，触发催乳素的重新激活和跨乳房传播妊娠晚期和哺乳期发育停滞的幼虫。我们建议通过 3 个具体目标来检验我们的假设： 1. 表征犬 A. TGF-β 受体和配体的同源物评估哺乳动物 TGF-β 与寄生虫受体的结合。 2. 使用体内感染模型以确定 TGF-β 水平和幼虫骨骼肌与乳腺组织的状态和负担怀孕和哺乳的不同阶段，并确定是否雌激素和催乳素刺激幼虫重新激活。 3. 使用于组织幼虫与肌肉细胞和乳腺细胞的体外共培养区分雌激素、催乳素和分阶段的不同作用妊娠血清对幼虫重新激活的影响，并确定是否具有中和作用 TGF-β 抗体抑制再激活。这些研究将提供对于制定治疗策略具有重要意义根除潜伏的寄生虫感染。