P13Kdelta Modulation of Neutrophil Trafficking

描述（由申请人提供）：中性粒细胞在炎症条件中发挥重要作用，如果不加以控制，可能导致组织损伤。因此，选择性抑制对其进入组织至关重要的途径将具有治疗价值。在这方面，I类PI3激酶（PBKs），由a， P， γ和δ亚型组成，成为有吸引力的靶标，因为它们在这些细胞的趋化因子定向迁移中起着关键作用。许多研究都集中在它们的功能上，但由于缺乏抑制剂，进展受到阻碍：1)无毒，因此可以在动物模型中进行研究；2)选择性地靶向主要在白细胞中表达的pdk，如δ异构体。利用最近开发的PI3Kdelta小分子抑制剂IC87114和p110delta缺陷小鼠，我们提供了证据，证明该信号通路是药物开发的有效靶点。小鼠口服该化合物可减少趋化因子介导的迁移，有趣的是，中性粒细胞与血管壁的粘附相互作用类似于在p110delta缺失动物中观察到的情况。因此，本应用的目的是确定PI3Kdelta在炎症部位中性粒细胞定位中的生物学作用及其调节细胞因子刺激的内皮细胞的促炎状态的能力。我们的研究将针对三个具体目标。在Aim 1中，我们将使用复制人类疾病状态的小鼠模型来评估PI3Kdelta在促进炎症肺和关节中性粒细胞积累中的作用。在Aim 2中，我们将确定该异构体相对于PI3K/ γ和p38MAPK信号通路在体外和体内促进中性粒细胞激活和迁移以响应内源性和细菌来源的化学引诱剂的重要性。后者将通过使用活体显微镜直接可视化表达gfp的细胞的行为来完成。在Aim 3中，我们将确定la类和Ib类PBKs是否存在于内皮细胞的功能复合物中，并探讨它们参与内皮细胞募集中性粒细胞能力的机制。总之，这些研究将确定PI3Kdelta在炎症中性粒细胞募集中的重要性，并为限制它们向组织迁移的治疗策略提供见解。此外，我们的研究结果将定义I类PBKs的新作用，即调节炎症内皮的粘附特性。

DESCRIPTION (provided by applicant): Neutrophils play a prominent role in inflammatory conditions, which if uncontrolled, can result in tissue injury. Thus, selective inhibition of a pathway critical for their movement into tissues would be of therapeutic value. In this regard, class I PI3 kinases (PBKs), consisting of a, P, gamma, and delta isoforms, make attractive targets as they play a pivotal role in chemokine-directional migration of these cells. Much research has concentrated on their functions, but progress has been hampered by the lack of inhibitors that 1) are nontoxic so that they may be studied in animal models, and 2) selectively target PDKs that are primarily expressed in leukocytes such as the delta isoform. Utilizing the recently developed small molecule inhibitor of PI3Kdelta, IC87114, and mice deficient in p110delta we provide evidence that this signaling pathway is a valid target for drug development. Oral administration of this compound to mice reduced chemokine-mediated migration and interestingly, adhesive interactions of neutrophils with the vessel wall in a manner analogous to that observed in p110delta null animals. Thus, the purpose of this application is to define the biological role of PI3Kdelta in neutrophil localization at sites of inflammation and its ability to modulate the proinflammatory state of cytokine-stimulated endothelium. Our studies will be directed at three specific aims. In Aim 1, we will evaluate the role of PI3Kdelta in promoting neutrophil accumulation in inflamed lung and joints using murine models that replicate disease states in man. In Aim 2, we will determine the importance of this isoform relative to PI3K/gamma and the p38MAPK signaling pathways in promoting neutrophil activation and migration in response to endogenous vs. bacteria-derived chemoattractants in vitro and in vivo. The latter will be accomplished by direct visualization of the behavior of GFP-expressing cells using intravital microscopy. In Aim 3, we will determine whether class la and Ib PBKs exist in functional complexes in endothelium and explore the mechanism(s) by which they participate in the ability of this cell type to recruit neutrophils. Together, these studies will determine the importance of PI3Kdelta in neutrophil recruitment in inflammation as well as provide insight into therapeutic strategies designed to limit their migration into tissues. Moreover, our results will define a new role for class I PBKs, regulation of the adhesive properties of inflamed endothelium.