P CARINII-EPITHELIAL INTERACTIONS MEDIATE INFLAMMATION

卡氏肺孢子虫在免疫功能低下的患者中产生危及生命的肺炎（PCP）。 重要的是，PCP的临床严重程度通常与患者对卡氏肺孢子虫产生炎症反应的能力比与微生物负荷更密切相关。 肺泡上皮细胞（AECs）与卡氏肺孢子虫（P. carinii）相互作用密切，并且这些细胞在启动炎症反应中的重要作用越来越被认识到。 该提议的假设是，AEC在肺泡隔室中卡氏肺孢子虫的初始检测和识别中起关键作用，并且卡氏肺孢子虫与肺泡上皮的相互作用刺激趋化因子分泌，并发出特异性地将炎性细胞募集到感染部位的信号。 当卡氏肺孢子虫感染的SCID小鼠的免疫功能恢复时，T淋巴细胞和巨噬细胞仅被募集到感染部位。 除了清除感染外，这种炎症反应还导致对肺的“旁观者”损伤。 我们的初步数据扩展了这些观察结果表明，β-趋化因子和β-趋化因子受体CCR 1和CCR 2在体内高度表达后重建的感染的SCID小鼠，免疫活性小鼠接种后。 此外，我们表明卡氏肺孢子虫与体外AEC的特异性连接模拟了TNF-α和β-趋化因子基因表达的分泌。 本发明的具体目的在于：1）表征卡氏肺孢子虫刺激的AEC分泌趋化因子并诱导CD 4 + T细胞的趋化性的能力。2)确定体内暴露于卡氏肺孢子虫后肺泡表面的早期趋化因子信号是否需要CD 4 + T细胞。 3)通过利用CCR 1和2敲除小鼠确定β-趋化因子在细胞募集和对卡氏肺孢子虫的抗性中的作用。 4)确定CCR 1和CCR 2在卡氏肺孢子虫诱导的肺部炎症的良好表征模型中在T细胞募集、生物体清除和肺损伤中的作用。 本提案的目的是了解对卡氏肺孢子虫的炎症反应，以便制定策略来规避由宿主对卡氏肺孢子虫的反应引起的肺损伤。

Pneumocystis carinii produces life-threatening pneumonia (PCP) in immunocompromised patients. Importantly, the clinical severity of PCP often correlates more closely with a patient's ability to mount an inflammatory response against P. carinii than with organism burdens. Alveolar epithelial cells (AECs) interact closely with P. carinii, and the important role of these cells in initiating inflammatory responses is becoming increasingly recognized. The hypothesis of this proposal is that AECs play a critical role in the initial detection and recognition of P. carinii in the alveolar compartment, and that the interaction of P. carinii with the alveolar epithelium stimulates chemokine secretion, and signals the recruitment of inflammatory cells specifically to sites of infection. When immune function is restored to P. carinii-infected SCID mice, T lymphocytes and macrophages are recruited only to sites of infection. In addition to clearing infection, this inflammatory response also results in "bystander" injury to the lung. Our preliminary data extends these observations by demonstrating that beta-chemokines and the beta-chemokine receptors CCR1 and CCR2 are highly expressed in vivo after reconstitution of infected SCID mice, and after inoculation of immunocompetent mice. In addition, we show that the specific attachment of P. carinii to AECs, in vitro, simulates the secretion of TNF-alpha and beta-chemokine gene expression. The specific aims of this proposal are designed to: 1) characterize the ability of P. carinii stimulated AECs to secrete chemokines, and induce the chemotaxis of CD4+ T cells. 2) determine whether CD4+ T cells are required for the early chemokine signals at the alveolar surface following in vivo exposure to P. carinii. 3) determine the role of beta-chemokines in cell recruitment and in resistance to P. carinii by utilizing CCR1 and 2 knockout mice. 4) determine the role of CCR1 and CCR2 in T cell recruitment, organism clearance, and lung injury in a well-characterized model of P. carinii-induced pulmonary inflammation. The goal of this proposal is to understand the inflammatory response to P. carinii so that strategies may be developed to circumvent the lung injury that results from the host response to P. carinii.