Immune Responses to Giardia lamblia

描述：(申请人提供)：蓝氏贾第鞭毛虫是一种原生动物 在许多哺乳动物的小肠中复制的寄生虫， 兰布里亚革兰氏菌感染是中国最常见的人类感染之一 这个词。大多数感染是自限性的，获得性免疫反应是 对控制人类和其他宿主中的革兰氏菌感染至关重要 物种。因此，了解蓝氏菌的免疫反应是非常重要的。 为了更好地控制这种疾病。我们最近展示了B细胞， γ-增量T细胞、IL-4和干扰素-γ缺陷小鼠可控制急性 感染蓝氏革兰氏菌。相比之下，需要CD4+、α-βT细胞 来控制感染。因此，T细胞依赖，但抗体不依赖。 存在控制兰布里亚革兰氏菌的机制。我们还展示了桅杆 细胞缺陷小鼠和IL-6缺陷小鼠不能控制蓝氏菌 感染。此外，体外研究表明，一氧化氮和 被称为防御素的抗菌肽可以抑制革兰氏杆菌。基于 这些发现，提出了如下假设：CD4+T细胞 在革兰氏杆菌感染过程中激活肥大细胞产生IL-6。IL-6 然后产生导致上皮细胞产生一氧化氮和 控制急性蓝氏菌感染的防御素。我们将对此进行测试 假设有以下具体目的： 1.确定IL-6在蓝氏菌感染过程中的作用。 我们将通过治疗免疫缺陷小鼠来确认IL-6的重要性 感染过程中的重组IL-6。IL-6的产量也将在 用RT-PCR检测野生型和免疫缺陷小鼠体内感染过程。 2.确定肥大细胞IL-6在革兰氏阴性杆菌发病过程中的重要性 感染。我们将通过以下方式确认肥大细胞在感染过程中的作用 通过免疫耗竭肥大细胞来测量感染期间的肥大细胞反应 细胞，以及肥大细胞缺陷小鼠的重建。我们要检查一下桅杆 免疫组织化学和过继转移法细胞产生IL-6。 3.探讨蓝氏贾第鞭毛虫中肥大细胞活化的机制 感染。我们将检测T细胞在体内和体内产生的细胞因子 体外培养。我们还将检查细胞因子缺陷小鼠的感染情况。我们会 检测肠上皮细胞(IEC)中干细胞因子的产生 体外和体内。 4.确定IL-6的产生导致控制糖尿病的机制 急性革兰氏阴性杆菌感染。我们将检查防御素和硝酸盐的生产 IEC体内氧化作用的RT-PCR和体外Northern blotting及 生物化学。防御素表达和一氧化氮产生不足的小鼠 然后被感染，以确定它们在控制感染方面的重要性。 这些实验的成功完成将使我们对免疫力有更深入的了解 以及发展这种生物作为模型系统来研究 了解粘膜免疫反应。

DESCRIPTION: (provided by the applicant):Giardia lamblia is a protozoan parasite which replicates in the small intestine of many species of mammals, and infections with G. lamblia are one of the most common human infections in the word. Most infections are self-limiting and acquired immune responses are essential for controlling G. lamblia infections in humans and other host species. Understanding the immune response to G. lamblia is therefore essential for better control of this disease. We have recently shown that B cell, gamma-delta T cell, IL-4 and IFN-gamma deficient mice can control acute infections with G. lamblia. In contrast, CD4+, alpha-beta T cells are required to control infections. Thus, a T cell-dependent, but antibody-independent. mechanism exists which can control G. lamblia. We have also shown that mast cell-deficient mice and IL-6 deficient mice cannot control G. lamblia infections. Also, in vitro studies have shown that nitric oxide and anti-microbial peptides known as defensins can inhibit G. lamblia. Based on these findings, the following hypothesis has been formulated: CD4+ T cells activate mast cells to produce IL-6 during G. lamblia infections. IL-6 production then leads to epithelial cell production of nitric oxide and defensins that control acute G. lamblia infections. We will test this hypothesis with the following specific aims: 1.To determine the importance of IL-6 production during G. lamblia infections. We will confirm the importance of IL-6 by treating immnunodeficjent mice with recombinant IL-6 during infections. IL-6 production will also be measured in vivo during infections in wild type and immunodeficient mice using RT-PCR. 2. To determine the importance of mast cell IL-6 production during G. lamblia infections. We will confirm the role of mast cells during infections by measuring mast cell responses during infections, by immuno-depletion of mast cells, and by reconstitution of mast cell deficient mice. We will examine mast cell production of IL-6 using immunohistochemistry and adoptive transfers. 3. To determine the mechanism of mast cell activation during G. lamblia infections. We will examine cytokine production by T cells in vivo and in vitro. We will also examine infections in cytokine deficient mice. We will examine intestinal epithelial cell (IEC) production of stem cell factor in vitro and in vivo. 4. To determine the mechanisms by which IL-6 production leads to control of acute G. lamblia infections. We will examine production of defensins and nitric oxide by IEC in vivo using RT-PCR and in vitro by Northern blots and biochemistry. Mice deficient in defensin expression and nitric oxide production will then be infected to determine their importance in controlling infections. Successful completion of these experiments will give us insights into immunity to G. lamblia, as well as developing this organism as a model system for understanding mucosal immune responses.