Polarizing T Cell Responses in vivo With Dendritic Cells

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Emerging evidence suggests a central role for dendritic cells (DCs) in inducing immune tolerance. Our recent research has provided critical new insights into the molecular mechanisms that “program” DCs to induce tolerogenic responses. In particular, we have observed an unappreciated intersection between the ancient nutrient-sensing pathway, involving the amino acid sensing molecule GCN2, and control of inflammation in the gut. Given the central role of GCN2 as a sensor of amino acid starvation, we explored its’ potential role in the intestine, and observed its remarkable effects on modulating the functions of intestinal DCs and epithelial cells to control inflammation in the gut. In this context the goal of the research proposed here is to determine the mechanisms by which GCN2 and this stress response pathway regulate gut inflammation. Aim 1: To determine the mechanism by which the GCN2-eIF2α pathway regulates intestinal immunity and inflammation. Our preliminary data demonstrates that GCN2-/- mice display enhanced susceptibility to intestinal inflammation and strikingly enhanced Th17 responses. Here we will explore the effects of conditional ablation of GCN2 expression in DCs versus intestinal epithelial cells, and whether these effects are dependent on down the downstream kinase eIF2α. Aim 2: To determine the cause and consequence of excess reactive oxygen species (ROS) production in GCN2 deficient mice. Our preliminary data show that GCN2-/- mice have enhanced intestinal inflammation and elevated levels of ROS in gut DCs and epithelial cells. In this aim we propose to determine the cause and consequence of excess ROS production in the GCN2-/- mice. Aim 3: To determine the mechanism by which GCN2 suppresses inflammasome activation. Finally, our preliminary data demonstrates increased inflammasome activation in gut DCs and epithelial cells in GCN2-/- mice. In this aim, we will determine whether this inflammasome activation is essential for enhanced intestinal inflammation and Th17 responses. The successful completion of these aims will provide new mechanistic insights into how this stress response pathway controls intestinal inflammation, and provide new therapeutic strategies against autoimmunity.