PMN integrins, apoptosis and inflammation

描述（由申请人提供）： 多形核中性粒细胞（PMN）参与炎症反应是抵御入侵生物的第一道防线。 然而，炎症被称为“双刃剑”，因为PMN可引起周围组织的损伤，并且延长的炎症反应可导致多种病理状况。 循环中的中性粒细胞募集到炎症部位需要中性粒细胞与内皮细胞的刺激粘附，然后是它们的外渗和趋化性。 β 2整联蛋白、α-L β-2和α-M β-2介导PMN与内皮细胞的紧密粘附，这是随后外渗所需的。 虽然β 2整合素已被广泛研究，重点是确定粘附所需的构象变化，而负责调节β 2介导的PMN粘附的细胞信号转导途径仍然知之甚少。我们已经确定了一个与PMN凋亡相关的信号通路，该通路减弱了β 2介导的PMN与肺微血管内皮细胞的粘附。 刺激PMN Fas“死亡”受体导致PMN与肺微血管内皮细胞的粘附减少。 初步数据表明，粘附的损失是Fas/神经酰胺/蛋白激酶C δ（PKC δ）通路中的一个非常早期的事件，该通路有助于PMN凋亡。 具体而言，Fas激活增加PMN神经酰胺浓度，并导致PKC δ的胞质定位。 我们认为PKC δ的胞浆定位可以减少粘附，因为它反对PKC δ的膜定位，而膜定位是β 2介导的粘附所必需的。 目的1检测PMN上介导内皮细胞粘附的两种β 2整合素受体α-L β 2和α M β 2，以确定哪些β 2受体受Fas激活的影响。 目的2确定Fas激活对PKC δ的影响，并操纵PKC δ的细胞定位以确定其对β 2整合素和粘附的影响。 目的3检测Fas对神经酰胺的影响，以证实神经酰胺增加介导Fas对PKC δ、β 2整合素和粘附的影响。 目的4确定通过操纵Fas/神经酰胺/PKC δ途径减少粘附是否也可以减少离体大鼠肺中缺血/再灌注诱导的损伤。 对这一途径的理解将为控制炎症提供新的靶点。

DESCRIPTION (provided by applicant): The participation of Polymorphonuclear neutrophils (PMN) in the inflammatory response provides a first line of defense against invading organisms. However, inflammation has been called "double edged sword" as PMN can cause damage to surrounding tissues and a prolonged inflammatory response can contribute to a variety of pathological conditions. The recruitment of circulating PMN to inflammatory sites requires the stimulated adhesion of PMN to the endothelium followed by their extravasation and chemotaxis. The beta2 integrins, alpha-L beta-2 and alpha-M beta-2 mediate the tight adhesion of PMN to the endothelial cells required for subsequent extravasation. Although the beta2 integrins have been widely studied, the focus has been on identifying conformational changes necessary for adhesion while the cellular signaling pathways responsible for regulating beta2 mediated adhesion of PMN remain poorly understood. We have identified a signaling pathway associated with PMN apoptosis that attenuates the beta2 mediated adhesion of PMN to pulmonary microvascular endothelial cells. Stimulation of the PMN Fas "death" receptor results in a reduction of PMN adhesion to pulmonary microvascular endothelial cells. Preliminary data indicates that the loss of adhesion is a very early event in the Fas/Ceramide/Protein Kinase Cdelta (PKCdelta) pathway that contributes to PMN apoptosis. Specifically, Fas activation increases PMN ceramide concentration and causes the cytosolic localization of PKCdelta. We propose that the cytosolic localization of PKCdelta could reduce adhesion because it opposes the membrane localization of PKCdelta that is necessary for beta2 mediated adhesion. Aim 1 examines the two beta2 integrin receptors on PMN, alpha-L beta-2 and alphaM beta2, that mediate endothelial cell adhesion to determine which of the beta2 receptors are affected by Fas activation. Aim 2 determines the effect of Fas activation on PKCdelta and manipulates the cellular localization of PKCdelta to determine its effects on the beta2 integrins and adhesion. Aim 3 examines the effects of Fas on ceramide to confirm that ceramide increases mediate Fas effects on PKCdelta, beta2 integrins, and adhesion. Aim 4 determines if reducing adhesion by manipulating the Fas/ceramide/PKCdelta pathway can also reduce ischemia/reperfusion-induced injury in an ex-vivo rat lung. An understanding of this pathway would provide novel targets for the control of inflammation.