My overall aim is to understand the physiologic and medical importance of lung dendritic cells (DC) and to define the suitability of inhibitors of their function for the treatment of inflammatory lung diseases like asthma and COPD.Lung dendritic cells (DC) play crucial roles in the regulation of lung immunity. We still do not fully understand how they get activated in response to different types of environmental triggers like allergens, cigarette smoke and pathogens. Although recognition of conserved motifs by pattern recognition receptors on DCs could be a key event, these stimuli are also accompanied by accumulation of unfolded proteins in the endoplasmic reticulum (ER). Cells respond by mounting the unfolded protein response (UPR) that acts to ameliorate protein folding, but intersects with metabolism, induction of alarm signals and cellular suicide mechanisms. I hypothesize that the presence of unfolded proteins and ER stress in DCs is a crucial endogenous danger signal that is vital to understanding their biology and their involvement in inflammatory lung diseases.My specific aims are to :1.define the fine tuning of ER stress pathways in various lung DC subsets in health and disease2. define the specific role of ER stress proteins XBP1, JIK and ORMDL3 in DCs3. test if interfering with ER stress pathways alters the course of inflammatory lung diseaseTo approach these aims, I have developed mouse models of lung disease that are centered around lung DCs and where ER stress pathways can be genetically deleted. Using a combination of cell biological and immunological techniques I hope to achieve definitive answers as to how ER stress pathways regulate the function of DCs. Manipulation of ER stress pathways by drugs will have a major impact on very common diseases like diabetes, cardiovascular and neurodegenerative disease. Through the current proposal, I hope to extend this exciting field to lung biology.