TNF Processing in Pulmonary Immunopathology

描述（由申请人提供）：感染呼吸道病毒，如流感病毒，特别是高致病性菌株，会导致相当大的肺部免疫病理，其中很大一部分是由宿主T细胞反应引起的。这种肺损伤是这种感染的临床结果的重要决定因素。我们已经建立了一个模型来区分肺损伤是特异性地由于CD8+ T细胞识别肺上皮上的病毒抗原和由此触发的T细胞效应活动，而不是由于病毒本身的细胞病变效应。在这个提议中，我们的目标是扩展CD8+ T细胞介导的损伤的特征，以解剖与流感肺炎存在的T细胞反应相关的复杂免疫病理过程。我们发现高度损伤和最小损伤的T细胞群在处理跨膜TNF到其可溶性形式的阈值方面存在显著差异。作为原理的证明，我们已经开发出CD8+ T细胞，专门表达不可切割的跨膜形式的TNF，并观察到损伤潜力的显着降低。这些T细胞引发的病理表现是明显的间质/间隔细胞浸润，但没有明显的肺泡间隙浸润，也没有水肿或出血的迹象。此外，虽然WT T细胞介导的损伤的特征是在T细胞接触后的最初12-24小时内短暂积累PMN，然后是巨噬细胞的大量积累，但在转移突变T细胞后，这种PMN内流并不明显。在突变T细胞的受体中，气体交换仅轻微受损。我们假设，处理跨膜TNF的阈值决定了CD8+ T细胞识别后损伤的严重程度。我们进一步假设，以抗原特异性方式产生的可溶性TNF介导的增强损伤的机制是，在T细胞识别的响应下，肺泡上皮细胞诱导中性粒细胞趋化剂表达，从而导致早期和短暂的中性粒细胞募集到肺泡空间。这似乎是由TNF-R2 （p75）介导的，导致旺盛的ERK激活和Egr-1表达。我们将研究WT和突变型CD8+ T细胞群，以及多种表达突变型TNF受体的转基因小鼠，以了解CD8+ TNF加工到可溶性物种如何引发严重的肺损伤及其调控机制。

DESCRIPTION (provided by applicant): Infection with respiratory viruses such as with influenza, particularly the highly pathogenic strains, results in considerable pulmonary immunopathology, a large component of which results from the host T cell responses. This lung injury is an important determinant of clinical outcome in such infections. We have developed a model to distinguish the lung injury that is specifically due to CD8+ T cell recognition of viral antigen on lung epithelium and T cell effector activities triggered thereby, from that which results from the cyopathic effects of the virus itself. In this proposal we aim to extend the characterization of CD8+ T cell mediated injury to dissect the complex immunopathologic processes associated with T cell responses in the presence of influenza pneumonia. We have found a significant difference between highly injurious and minimally injurious T cell populations in their threshold for processing transmembrane TNF to its soluble form. As a proof of principle, we have developed CD8+ T cells which exclusively express a non-cleavable transmembrane form of TNF, and have observed a marked reduction in injury potential. The pathology triggered by these T cells is remarkable for significant interstitial/septal cellular infiltration without significant infiltration of the alveolar space and without evidence of edema or hemorrhage. Furthermore, while WT T cell-mediated injury is characterized by transient accumulation of PMNs in the first 12-24 hours after T cell engagement, followed by dramatic accumulation of macrophages, this PMN influx was not evident after transfer of the mutant T cells. Gas exchange was only mildly impaired in recipients of the mutant T cells. We hypothesize that the threshold for processing of transmembrane TNF determines the severity of the injury after CD8+ T cell recognition. We further hypothesize that the mechanism of enhanced injury mediated by soluble TNF produced in an antigen-specific fashion is the induction of neutrophil chemoattractant expression by alveolar epithelial cells, in response to T cell recognition, which leads to early and transient neutrophil recruitment to the alveolar space. This appears to mediated by TNF-R2 (p75) leading to exuberant ERK activation and Egr-1 expression. We will study WT and mutant CD8+ T cell populations, and a variety of transgenic mice expressing mutant TNF receptors in order to understand how CD8+ TNF processing to the soluble species triggers severe lung injury, and the mechanisms of regulation.