Innate immune response to microbial PAMPs in the schistosome-transmitting snail,

描述（由申请人提供）：寄生虫体与其蜗牛中间宿主之间的相容性部分取决于幼虫寄生虫与宿主先天性内部防御系统（IDS）相互作用的结果。与其他先天免疫系统一样，媒介蜗牛光滑双脐螺的IDS被认为依赖于模式识别受体（PRR）对病原体相关分子模式（PAMP）的识别。然而，PAMPs和PRRs的重要性，在寄生虫蜗牛的相互作用还没有得到很好的理解。所提出的研究的具体目的是鉴定B的IDS针对的一种或多种特定PAMP。glabrata响应，然后在转录组水平上表征这种响应。最近，在抗β-内酰胺酶（但不敏感β-内酰胺酶）的B的造血阿米巴细胞产生器官（APO）中观察到对注射的大肠杆菌粗脂多糖（LPS）的有丝分裂反应。glabrata，并且有丝分裂活性的模式与先前针对注射的溶酶体提取物描述的非常相似。这一观察结果提供了一个机会，以确定第一次特定的PAMP，触发免疫反应，在一个寄生虫传播蜗牛。如果这种有丝分裂活性实际上是针对LPS的，它代表了无脊椎动物对最具特征的微生物PAMP之一的独特反应，并且鉴定负责的PAMP可以提供关于蜗牛IDS识别不相容的寄生虫幼虫的见解，这可能是在最近获得寄生虫之前很久对微生物病原体的反应中进化而来的。拟议的研究将测试在粗LPS中发现的最可能的候选PAMP的促有丝分裂活性（即，LPS、肽聚糖、未甲基化的富含CpG的DNA），并且如果活性与LPS本身相关，则LPS的活性组分（即，脂质A或O多糖）。这些研究将利用注射蜗牛的载脂蛋白O细胞分裂的组织学分析。最后，与使用微阵列分析，在APO中的基因表达的模式，以响应注射与活性细菌PAMP将比较先前报告的其他形式的非自我。 公共卫生相关性：蜗牛作为医学上重要的复殖吸虫的中间宿主的能力部分取决于寄生虫与宿主先天免疫系统的相互作用。这项拟议的研究旨在首次确定一种特定的细菌分子，该分子可以在介体传播蜗牛Biomphalaria glabrata中引发先天免疫反应（造血），然后表征响应该分子的基因表达模式。这项研究的结果可能会提供新的信息，免疫识别的细菌分子模式，以及洞察的蜗牛，寄生虫兼容性的潜在机制。

DESCRIPTION (provided by applicant): Compatibility between schistosomes and their snail intermediate hosts is determined in part by the outcome of the interaction of the larval parasite with the host's innate internal defense system (IDS). As in other innate immune systems, the IDS of the vector snail Biomphalaria glabrata is thought to rely on recognition of pathogen-associated molecular patterns (PAMPs) by pattern recognition receptors (PRRs). However, both the PAMPs and PRRs important in schistosome-snail interactions are not well understood. The specific aims of the proposed research are to identify one or more specific PAMPs to which the IDS of B. glabrata responds, and then to characterize this response at the transcriptomic level. Recently, a mitotic response to injected crude lipopolysaccharide (LPS) from Escherichia coli has been observed in the hematopoietic amebocyte-producing organ (APO) of schistosome-resistant (but not schistosome- susceptible) B. glabrata, and the pattern of mitotic activity is quite similar to that previously described against injected schistosome extracts. This observation provides an opportunity to identify for the first time a specific PAMP that triggers an immune response in a schistosome-transmitting snail. Should this mitotic activity in fact be directed against LPS, it represents a unique invertebrate response against one of the best characterized microbial PAMPs, and identification of the responsible PAMP(s) may provide insights on recognition of incompatible schistosome larvae by the snail IDS, which presumably evolved largely in response to microbial pathogens long before the recent acquisition of schistosome parasites. The proposed research will test the mitogenic activity of the most likely candidate PAMPs found in crude LPS (i.e., LPS, peptidoglycan, unmethylated CpG-rich DNA), and if activity is associated with LPS itself, then the active component of LPS (i.e., lipid A or the O polysaccharide) will be identified. These studies will utilize histological analysis of cell division in APOs of injected snails. Finally, with the use of microarray analysis, the pattern of gene expression in the APO in response to injection with the active bacterial PAMP will be compared to that previously reported in response to other forms of nonself. PUBLIC HEALTH RELEVANCE: The capacity for a snail to serve as an intermediate host for medically important digenetic trematodes hinges in part on the interaction of the parasite with the host's innate immune system. The proposed research seeks to identify for the first time a specific bacterial molecule that triggers an innate immune response (hematopoiesis) in the schistosome-transmitting snail, Biomphalaria glabrata, and then to characterize the pattern of gene expression in response to this molecule. Results of this study may provide new information on immune recognition of bacterial molecular patterns, as well as insights on the underlying mechanisms of snail-schistosome compatibility.