Enhancing neutrophil function in neutropenia-related pneumonia

描述（申请人提供）：化疗和放疗广泛用于治疗各种血液恶性肿瘤和实体瘤。中性粒细胞减少和相关感染是这些抗癌治疗中最重要的剂量限制性毒性，影响生活质量和临床结果，并有可能导致死亡。中性粒细胞减少相关性肺炎涉及40%的非血液部位感染，通常采用广谱抗生素治疗和粒细胞集落刺激因子（G-CSF）治疗。然而，并非所有患者对抗生素治疗都有反应，G-CSF治疗通常与骨痛、头痛、疲劳、恶心和患白血病的高风险等副作用有关。该项目的长期目标是探索另一种治疗/预防中性粒细胞减少相关肺炎的策略-通过增强中性粒细胞功能（如招募，存活和细菌杀死）。我们将尝试通过提高细胞内PtdIns(3,4,5)P3信号通路来实现这一目标，该信号通路与多种中性粒细胞功能有关。最近，我们发现PTEN敲除小鼠的中性粒细胞对化学吸引物刺激的反应性大大增强，其中PtdIns(3,4,5)P3信号被过度激活。在这些小鼠中，中性粒细胞向炎症腹膜腔的募集明显增强。此外，通过消耗PTEN增强PtdIns(3,4,5)P3信号可防止中性粒细胞自发死亡。我们的初步数据还表明，PTEN零中性粒细胞具有增强的细菌杀灭能力，并且它们在炎症肺部的招募也增强了。基于这些有趣的结果，我们假设增加PtdIns(3,4,5)P3信号通路应该是治疗中性粒细胞减少相关性肺炎的合法治疗策略。在这项拟议的研究中，我们将直接研究PTEN的破坏是否可以增加中性粒细胞募集和中性粒细胞相关性肺炎（Aim I）的存活，增强中性粒细胞杀伤能力，并减轻中性粒细胞相关性肺炎（Aim II）的严重程度。此外，由于肺泡巨噬细胞在宿主防御呼吸道感染中也起着关键作用，PTEN的破坏是否也能增强肺泡巨噬细胞的功能将被研究（Aim III）。最后，PtdIns(3,4,5)P3信号也可以通过破坏InsP3KB而增强；因此，我们将探讨InsP3KB的破坏是否也可以降低中性粒细胞减少相关肺炎的严重程度（Aim IV）。公共卫生相关性：本研究提出的实验将深入研究PtdIns(3,4,5)P3通路在肺部感染和炎症中提高中性粒细胞和巨噬细胞功能的作用机制，最终目的是巩固PtdIns(3,4,5)P3相关通路作为治疗中性粒细胞减少相关性肺炎的新靶点。这将是对目前抗生素和G- CSF治疗的重要和必要的补充。此外，虽然我们在本应用中关注的是中性粒细胞减少相关的肺炎，但同样的策略也可以很容易地应用于其他中性粒细胞减少相关的传染病。

DESCRIPTION (provided by applicant): Chemo- and radiotherapy are extensively used to treat various hematological malignancies and solid tumors. Neutropenia and related infection are the most important dose limiting toxicities of these anti-cancer treatments, impacting on quality of life and clinical outcomes, with the potential to cause death. Neutropenia- related pneumonias are involved in 40% infection at a site other than blood alone, and usually treated with broad-spectrum antibiotic therapy and granulocyte colony-stimulating factor (G-CSF) therapy. However, not all patients respond to antibiotic treatment and G-CSF therapy is often associated with side-effects such as bone pain, headache, fatigue, nausea, and higher risk of getting leukemia. The long-term goal of this project is to explore another strategy for treating/preventing neutropenia-related pneumonia - via enhancing neutrophil functions (e.g. recruitment, survival, and bacteria killing) in neutropenic patients. We will try to achieve this by elevating intracellular PtdIns(3,4,5)P3 signaling pathway which has been implicated in a variety of neutrophil functions. Recently, we have shown that the responsiveness of neutrophil to chemoattractant stimulation is much enhanced in PTEN knockout mice in which the PtdIns(3,4,5)P3 signaling is hyperactivated. The recruitment of neutrophils to the inflamed peritoneal cavity was significantly enhanced in these mice. In addition, augmenting PtdIns(3,4,5)P3 signal via depleting PTEN prevents neutrophil spontaneous death. Our preliminary data also demonstrated that the PTEN null neutrophils possess an enhanced bacteria killing capability and their recruitment to the inflamed lungs was also augmented. Based on these intriguing results, we hypothesize that augmentation of PtdIns(3,4,5)P3 signaling pathway should be a legitimate therapeutic strategy for the treatment of neutropenia-related pneumonia. In this proposed research, we will directly examine whether disruption of PTEN can augment neutrophil recruitment and survival in neutropenia-related pneumonia (Aim I), enhance neutrophil bacterial killing capability, and alleviate the severity of neutropenia- related pneumonia (Aim II). In addition, since alveolar macrophages also play a critical role in host defense against respiratory tract infections, whether disruption of PTEN can also enhance the function of alveolar macrophages will be investigated (Aim III). Lastly, PtdIns(3,4,5)P3 signaling can also be augmented by disrupting InsP3KB; and thus we will explore whether disruption of InsP3KB can also reduce the severity of neutropenia-related pneumonia (Aim IV). PUBLIC HEALTH RELEVANCE: Experiments proposed in this study will provide insight into the mechanism of action of PtdIns(3,4,5)P3 pathway in elevating neutrophil and macrophage function in lung infection and inflammation, with the ultimate goal of solidifying PtdIns(3,4,5)P3-related pathways as novel therapeutic targets for treatment of neutropenia- related pneumonia. This will be an important and necessary complementation to the current antibiotic and G- CSF therapies. In addition, although we focus on neutropenia-related pneumonia in this application, the same strategy can be readily applied to other neutropenia-related infectious diseases.