PGE2 Regulation of Host Defense post-BMT

描述（由申请人提供）：骨髓（BM）移植（BMT）是许多恶性肿瘤和特定遗传性疾病的治疗选择。不幸的是，感染，如铜绿假单胞菌（铜绿假单胞菌）经常发生，甚至在移植后。对BMT患者肺部感染风险增加的机制知之甚少。我们已经证明，尽管供体白细胞完全重建，接受同基因BMT的小鼠比未移植的小鼠更容易受到铜绿假单胞菌的肺部感染。我们发现BMT小鼠的肺泡巨噬细胞（AM）和多形核白细胞（PMN）吞噬和/或杀死细菌并释放肿瘤坏死因子-α（TNF α）的能力存在缺陷。此外，来自BMT小鼠的AM和PMNs产生的前列腺素E2（PGE 2）是来自对照小鼠的细胞的125倍。PGE 2能够通过与E前列腺素2（EP 2）受体的相互作用限制AM吞噬作用并限制AM和PMN细菌杀伤。因此，PGE 2是一个有吸引力的候选人，在BMT小鼠AM和PMN的功能失调活动中发挥核心作用。体内证实来自我们的研究，其中PGE 2产生的药理学阻断（使用吲哚美辛）恢复了BMT后肺宿主对铜绿假单胞菌的防御。这些数据导致我们的假设，即BMT后肺中PGE 2的过度产生，通过EP 2受体信号传导起作用，抑制肺吞噬细胞功能，导致肺宿主对铜绿假单胞菌的防御受损。我们目前的研究将确定骨髓移植后粒细胞-巨噬细胞集落刺激因子（GM-CSF）的产生是否增加导致PGE 2的产生增加，以及供体与宿主来源的肺吞噬细胞或骨髓移植条件肺环境是否有助于受损的宿主防御。最后，我们将探讨第十号染色体上的磷酸酶和张力蛋白同源物（PTEN）和IL-1受体相关激酶（IRAK）-M作为PGE 2诱导的抑制的介质所发挥的作用。本研究采用分子、细胞和动物模型方法，旨在：目的1）确定GM-CSF增加在决定BMT后PGE 2升高和宿主防御受损中的作用;目的2）确定AM的起源是否与BMT后PGE 2升高和宿主防御受损有关。目的3确定BMT肺微环境是否抑制AM功能;目的4）探讨PTEN激活和/或IRAK-M升高在骨髓移植后PGE 2诱导的免疫抑制中的作用。这项工作提供了对BMT后观察到的持续免疫抑制的机理性见解，并为开发新的治疗策略（GM-CSF的中和、PGE 2合成/信号传导的抑制和PTEN活化的药理学抑制）提供了概念证明，这可能导致有效的新治疗以预防干细胞移植后患者的肺部感染。

DESCRIPTION (provided by applicant): Bone marrow (BM) transplantation (BMT) is the treatment of choice for many malignancies and specific inherited disorders. Unfortunately, infections such as Pseudomonas aeruginosa (P. aeruginosa) occur frequently even post-engraftment. Little is known about the mechanisms responsible for the increased risk of lung infections in BMT patients. We have shown that mice undergoing syngeneic BMT are more susceptible to pulmonary infection with P. aeruginosa than are non-transplanted mice despite complete donor leukocyte reconstitution. We found defects in the ability of alveolar macrophages (AMs) and polymorphonuclear leukocytes (PMNs) from BMT mice to phagocytose and/or kill bacteria and release tumor necrosis factor-a (TNFa). In addition, AMs and PMNs from BMT mice produce up to 125-times more prostaglandin E2 (PGE2) than cells from control mice. PGE2 is able to limit AM phagocytosis and to limit AM and PMN bacterial killing via interactions with the E prostanoid 2 (EP2) receptor. Thus, PGE2 is an attractive candidate to play a central role in the dysfunctional activity of AMs and PMNs from BMT mice. In vivo confirmation comes from our studies where pharmacologic blockade of PGE2 production (using indomethacin) restores lung host defense against P. aeruginosa post-BMT. These data have led to our hypothesis that over-production of PGE2 in the lung post-BMT, acting via EP2 receptor signaling, suppresses lung phagocyte function leading to impaired pulmonary host defense against P. aeruginosa. Our current studies will determine whether increased production of granulocyte-macrophage colony-stimulating factor (GM-CSF) post-BMT leads to increased production of PGE2 and whether the donor vs. host origin of the lung phagocytes or the BMT-conditioned lung environment contributes to impaired host defense. Finally, we will explore the role that the phosphatase and tensin homolog on chromosome ten (PTEN) and IL-1 receptor-associated kinase (IRAK)-M play as mediators of the PGE2-induced suppression. Using molecular, cellular and animal modeling strategies, we will address the following aims: Aim 1) To determine the role of increased GM-CSF in determining PGE2 elevation and impaired host-defense post- BMT; Aim 2) To determine whether the origin of the AMs (donor vs. host) dictates function post-BM; Aim 3 To determine whether the BMT lung microenvironment is inhibitory to AM function; Aim 4) To determine the roles that PTEN activation and/or IRAK-M elevation play in mediating the PGE2-induced immunosuppression post-BMT. This work provides mechanistic insight into the persistent immunosuppression seen post-BMT and provides a proof of concept for the development of new therapeutic strategies (neutralization of GM- CSF, inhibition of PGE2 synthesis/signaling and pharmacologic inhibition of PTEN activation) which may result in effective new treatments to prevent pulmonary infections in patients post-stem cell transplant.