Alternative macrophage activation in acute Pseudomonas pneumonia

描述(由申请人提供)：替代的巨噬细胞激活调节对病原体的炎症反应。到目前为止，大多数工作都描述了它们在Th2型免疫反应中的作用。另一种激活的巨噬细胞通过产生转化生长因子�和精氨酸酶-1抑制经典激活的巨噬细胞的增殖和功能，以及抑制T细胞介导的免疫反应。精氨酸酶-1和转化生长因子�在控制肺内稳态和抑制炎症方面也具有重要作用。AAM在调节肺部细胞外革兰氏阴性细菌感染时的炎症反应中的作用尚不清楚。了解AAM在这一环境中的作用对于促进我们对影响囊性纤维化(CF)和其他慢性肺部炎症患者的免疫机制的理解至关重要。Cf由于铜绿假单胞菌感染引起反复的、失调的炎症反应，导致进行性的、危及生命的肺损伤。因此，这项工作将解决这样一种假设，即交替激活 巨噬细胞减少铜绿假单胞菌感染时的肺部炎症，这依赖于转化生长因子�和精氨酸酶-1的产生。我们将利用正常和基因工程小鼠的铜绿假单胞菌肺炎模型来解决三个不同的目标。目的1确定铜绿假单胞菌肺部感染引起的炎症调节是否依赖于巨噬细胞的交替激活。目的2将探讨AM对T细胞处置的调节是否可以通过产生转化生长因子�来控制炎症和肺损伤。目的3将确定是否需要巨噬细胞表达精氨酸酶-1来预防铜绿假单胞菌肺炎引起的炎症。将使用具有遗传改变的aAM、转化生长因子�信号和巨噬细胞特异性精氨酸酶-1产生的小鼠模型，以及采用的转移方法和补充的体外实验。这些改变的影响将从炎症、经典巨噬细胞功能和T细胞亚群的激活和功能方面进行评估，以确定巨噬细胞在调节这些反应中所采用的重要机制。突出这项工作的临床相关性是使用抗菌剂阿奇霉素作为CF患者的免疫调节剂。该药已被证明可以减缓感染假单胞菌的CF患者的肺功能下降和减少发病率，但其有益的机制尚不清楚。最近，体外和动物研究表明，阿奇霉素使巨噬细胞极化为另一种表型，显著增加精氨酸酶-1的表达。这些数据，加上阿奇霉素在CF患者中的成功长期使用，使研究替代巨噬细胞激活在应对假单胞菌肺炎方面的作用具有吸引力，并可能为干预提供新的治疗靶点，以改变这一炎症和呼吸道损伤的破坏性循环。

DESCRIPTION (provided by applicant): Alternative macrophage activation regulates inflammatory responses to pathogenic organisms. Most work to date has characterized their role in Th2-type immune responses. Alternatively activated macrophages (AAM) have been shown to inhibit classically activated macrophage proliferation and function, as well as to suppress T cell mediated immune responses through the production of the type II cytokine transforming growth factor (TGF)-� and arginase-1. While primarily functioning to orchestrate remodeling and repair mechanisms, arginase-1 and TGF� are also important in controlling lung homeostasis and suppressing inflammation. The function of AAM in regulating the inflammatory response to extracellular Gram-negative bacterial infection in the lungs has not been characterized. Understanding the role of AAM in this setting is critical for advancing our understanding of immune mechanisms affecting patients with cystic fibrosis (CF) and other chronic pulmonary inflammatory conditions. CF causes progressive, life-threatening lung damage due in large part to repeated, dysregulated inflammatory responses to Pseudomonas aeruginosa infection. Therefore, this work will address the hypothesis that alternatively activated macrophages decrease pulmonary inflammation in P. aeruginosa infection, and that this is dependent upon production of TGF� and arginase-1. We will utilize a model of P. aeruginosa pneumonia in normal and genetically engineered mice to address 3 distinct aims. Aim 1 will determine whether regulation of inflammation caused by P. aeruginosa lung infection is dependent upon alternative macrophage activation. Aim 2 will address whether AAM regulation of T cell disposition can control inflammation and lung damage through the production of TGF�. Aim 3 will determine whether arginase-1 expression by macrophages is required to prevent inflammation induced by P. aeruginosa pneumonia. Mouse models with genetically altered AAM, TGF� signaling, and macrophage-specific arginase-1 production will be used, along with adoptive transfer methodologies and complementary in vitro experiments. The impact of these alterations will be evaluated in terms of inflammation, classical macrophage function, and T cell subset activation and function to determine the important mechanisms employed by macrophages in regulating these responses. Highlighting the clinical relevance of this work is the use of the antimicrobial agent azithromycin as an immunomodulator in patients with CF. This drug has been shown to slow pulmonary function decline and decrease morbidity in CF patients infected with Pseudomonas, but the beneficial mechanistic effect is unknown. Recently it has been shown, in both in vitro and animal studies, that azithromycin polarizes macrophages to an alternative-like phenotype, dramatically increasing the expression of arginase-1. This data, along with the successful long-term use of azithromycin in patients with CF, make studying the role of alternative macrophage activation in response to Pseudomonas pneumonia attractive and likely to yield novel therapeutic targets for intervention to alter this destructive cycle of inflammation and airway damage.