MT VET COBRE PROJECT 3: NEUTROPHIL FUNCTION IN ASPERGILLOSIS IMMUNITY

这个子项目是利用由NIH/NCRR资助的中心拨款提供的资源的许多研究子项目之一。子项目和调查员(PI)可能从另一个NIH来源获得了主要资金，因此可能会出现在其他CRISE条目中。列出的机构是针对中心的，而不一定是针对调查员的机构。烟曲霉是一种会导致人类致命感染的真菌。近几十年来，在免疫抑制疾病患者中，致命性烟曲霉菌感染的数量不断增加，烟曲霉菌现在被公认为是受损个体中主要的空气传播真菌病原体。免疫功能正常的人即使暴露在高浓度的烟曲霉菌分生孢子中也很少发生曲霉病，中性粒细胞(PMN)的几个缺陷被认为是这种疾病的重要危险因素。为了研究PMN在肺中的防御作用，特别是其抗微生物氧化活性，比较了正常小鼠和gp91Phox基因缺陷和CXCR2基因缺陷小鼠对烟曲霉菌分生孢子的反应。在gp91Phox基因缺陷的小鼠中，NADPH氧化酶是不活跃的，而在CXCR2基因缺陷的小鼠中，中性粒细胞对某些炎症刺激的反应延迟。在正常Balb/c小鼠中，招募的PMN通过将分生孢子包裹在PMN聚集体中抑制萌发，其中用Formazan染色检测氧化酶活性。分生孢子萌发发生在gp91Phox缺陷小鼠和CXCR2缺陷小鼠中，其中PMN聚集体形成但缺乏氧化酶活性，而CXCR2缺陷小鼠的PMN聚集体形成延迟。我们的研究提供了体内证据表明，当一些到达免疫活性小鼠肺的分生孢子被肺泡噬菌体(AM)占据时，分生孢子周围具有氧化酶活性的PMN聚集体的招募、激活和形成抑制了额外的萌发。使用CXCR2基因缺陷和gp91Phox基因缺陷小鼠的实验表明，这些事件发生在分生孢子暴露后6小时内，对于防止菌丝出现是必不可少的。这一信息可能有助于解释为什么免疫能力强的人缺乏疾病，即使暴露在大量分生孢子中也是如此。未来的研究将更好地描述PMN和AM中分生孢子杀伤的分子机制

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Aspergillus fumigatus is a fungus that causes fatal infection in humans. Recent decades have seen increasing numbers fatal A. fumigatus infections in patients with immune suppressive disorders, and A. fumigatus is now recognized as the leading airborne fungal pathogen in compromised individuals. Humans with normal immunity rarely develop aspergillosis even when exposed to high concentrations of A. fumigatus conidia, and several deficiencies of polymorphonuclear neutrophils (PMN) are recognized to be a significant risk factor in this disease. In order to study the defensive role of PMN in the lungs, with particular reference to their antimicrobial oxidant activity, responses of PMN to A. fumigatus conidia in normal mice were compared to those in gp91phox-deficient and CXCR2-deficient mice, which are susceptible to aspergillosis. In gp91phox-deficient mice NADPH oxidase is inactive while in CXCR2-deficient mice there is delayed PMN recruitment in response to certain inflammatory stimuli. In normal balb/c mice, recruited PMN inhibited germination by enclosure of conidia within PMN aggregates where oxidase activity was detected with formazan staining. Conidial germination occurred in gp91phox-deficient mice, where PMN aggregates formed but lacked oxidase activity and in CXCR2-deficient mice, where there was a delay in formation of oxidase-active PMN aggregates. Our studies provide in vivo evidence to indicate that while some conidia reaching the lungs of immune competent mice are engaged by alveolar macarophages (AM), recruitment, activation and formation of oxidase-active PMN aggregates around conidia inhibited additional germination. Experiments using CXCR2-deficient and gp91phox-deficient mice indicate that it is essential for these events to occur within 6 h following conidial exposure to prevent hyphal emergence. This information may help explain a lack of disease in immunocompetent humans, even when exposed to large numbers of conidia. Future studies will better describe the molecular mechanisms of conidial killing in both PMN and AM.