Asthma is an extremely common disease, affecting 6.4% of American adults over the course of their lives1. Determining the molecular mechanisms behind the development and progression of asthma will lead to new treatment targets, more specific treatment options, and better control of the disease. Asthma is an inflammatory disease characterized by hypertrophy of smooth muscle, airway obstruction, and increased mucous production3. Dendritic cells, eosinophils, and mast cells are known to play a role in the development and progression of asthma, however the molecular mechanisms behind the disease have not been elucidated. Hypoxia inducible factor-11 (HIF-11) is a transcription factor recently identified as a master regulator of the inflammatory capacity of myeloid cells4; 5. HIF-11 mediates many critical functions of macrophages and neutrophils in inflammation4; 6. Because it is found in all mammalian cells, regulates over 100 functional genes, and modulates NF-:B pathways that are known to be up regulated during allergic inflammation7; 8, I hypothesize that HIF-11 regulates allergic inflammation in asthma. The pathogenesis underlying the development of asthma can be broken down into two components. First, an allergic response to a specific allergen is initiated. Second, airway inflammation develops in response to allergen re-exposure. The goal of the work proposed here is to explore how the transcription factor Hypoxia Inducible Factor-11 (HIF-11) modulates the pathogenesis of asthma, and to probe mechanistically the molecular pathways through which HIF-11 acts in this capacity. I hypothesize that (a) Hypoxia Inducible Factor-11 is a critical regulator of molecular pathways involved in allergic inflammation; (b) HIF-11 in dendritic cells plays a significant role in the initiation of the allergic airway response; and (c) HIF-11 in eosinophils plays a role in the perpetuation and progression of airway inflammation. I will explore how genetic manipulation of HIF-11 levels in leukocytes influences asthma susceptibility, and examine whether a therapeutic strategy to pharmacologically inhibit HIF-11 can be effective in reducing airway inflammation and reactivity. We will utilize an ovalbumin (OVA) model of allergic inflammatory airways disease in mice. Mice will be evaluated for the magnitude of allergic response via IgE, histamine, IL-4, and IL-13 levels, airway resistance, inflammatory pulmonary infiltrates, and airway remodeling. Detailed, mechanistic studies of eosinophils and dendritic cells will be done in vitro, with cells derived from mouse bone marrow. These studies will utilize migration assays, FACS analysis, ELISAs, Western blots, and real-time quantitative PCR. In this proposal, I will determine whether HIF-11 initiates or sustains allergic inflammatory airway disease development in mice. Specifically, these studies will rigorously test whether HIF-11 regulates dendritic cells and eosinophil function in allergic inflammation leading to asthma. Unique mouse genetic reagents, in which HIF-11 levels have been markedly reduced or constitutively increased in leukocyte lineages, are available for me to definitively test these hypotheses in a detailed, mechanistic fashion in vivo and ex vivo. Beyond these powerful genetic approaches, I propose a parallel series of pharmacologic experiments utilizing small molecule inhibitors to globally suppress HIF-11. I hypothesize that because HIF-11 is regulated at the protein level with a half-life of seconds9, anti-HIF-11 immunosuppressant agents will lead to a rapid decrease in inflammation in a manner that is rapidly reversible upon discontinuation of the agent. Therefore, if severe asthmatic patients were treated chronically with a HIF-11 inhibitor and developed an infection, the HIF-11 antagonist could be temporarily stopped to provide a rapid return of normal leukocyte function. As well as other chronic inflammatory diseases (rheumatoid arthritis, lupus, etc.), I hypothesize that HIF-11 inhibition may offer an exciting strategy for the management of asthma.
Asthma affects 6.4% of American adults, including Veterans, causing a major burden on the VA healthcare system1. The incidence of asthma has been studied in military personnel in particular, and has been found to not only be highly prevalent, but also increasing over time. Between 1980-In 1999, 3,900 Navy personnel were first hospitalized for asthma, and during this time the incidence of hospitalization doubled for some asthmatic populations10. There have been no major improvements in asthmatic treatments over the past several years, therefore research into the specific mechanisms underlying asthma is needed, to find better ways of treating and preventing it. The research proposed here is relevant to a disease commonly found in the Veteran population, and will greatly enhance our understanding of the molecular mechanisms underlying the development and progression of asthma, and lead towards the development of more effective targeted therapies to increase the quality of healthcare for our U.S. Veterans.
