T cells & IL-17
Role of T Cells in Lung Ischemia-Reperfusion Injury
Despite refinements in lung preservation and improvements in surgical technique and perioperative care, IR injury remains a significant cause of early morbidity and mortality after lung transplant. Clearly, prevention of IR injury is sorely needed.
We are utilizing both in vivo and in vitro models as complementary approaches to study mechanisms of lung IR injury. We have demonstrated a vital role for alveolar macrophages and TNF-alpha production in lung IR injury and have described crosstalk between macrophages and alveolar epithelial cells during IR injury. Current studies are focused on evaluating the role of CD4+ T cells, T cell-derived cytokines, and the innate immune system in lung IR injury. Preliminary studies indicate that NKT cells are pivotal for the initiation of IR injury and that NKT cell-produced IL-17 is a key chemokine for the activation and infiltration of neutrophils which lead to tissue damage. Dendritic cell-derived IL-23 also seems to be an upstream mediator of NKT cell activation. In addition, oxidative stress mechanisms of IR injury are being studied. Here, NADPH oxidase-generated reactive oxygen species is a key component of immune cell activation upon reperfusion, and we are studying the role of NADPH oxidase in various cell types in mediating IR-induced inflammatory pathways. Our laboratory uses various knockout and chimeric mice, immune cell ablation studies with diphtheria toxin in susceptible transgenic mice, adoptive transfer studies, and cultured immune cells to address mechanistic questions both in vivo and in vitro to study mechanisms of lung IR injury. In testing our hypotheses we hope to gain further knowledge of the pathways that mediate lung IR injury that will enable the development of specific small molecules that can be used in future clinical studies.
Representative flow cytometric analysis of IL-17-expressing leukocytes. Wild-type mice underwent either sham or IR surgery, and cell suspensions were prepared from left lungs. CD45+ 7-AAD- B220- TCRb+ cells were gated and further assessed by flow cytometry as shown. The numbers within each box indicate the percentage of cells gated. (A) The number of IL-17-expressing iNKT cells (IL-17+ CD1d tetramer+) was increased after IR compared to sham. (B) A substantial increase in the number of IL-17-expressing neutrophils (IL-17+ Gr-1+) occurred after IR. (C) The number of IL-17-expressing gd T cells (IL-17+ gdTCR+) was not increased after IR compared to sham.