The overall goal of this laboratory over the past 20 years has been the elucidation of mechanisms regulating allergic inflammation and thereby identification of novel targets for treating allergic diseases. This proposal will focus on mechanisms regulating human basophil activation and effector function in allergic diseases. Basophils are the least abundant granulocytes in the circulation, and only recently has evidence demonstrated that basophils have potent effector functions that bridge innate and adaptive immunity and contribute to the pathogenesis of both allergic and autoimmune diseases. Preliminary studies demonstrate that IL-3 is a key cytokine for polarizing basophils for effector functions that include degranulation in response to Fc?R1 crosslinking, regulation of cell surface molecule expression, cytokine expression, and immune modulation. Key preliminary findings include: 1) detailed analysis of IL-3 activation of human basophils that demonstrates IL-3-inducible phenotypic subsets of basophils with distinct functional characteristics;2) the first direct evidence for human basophil expression of the thymic stromal lymphopoietin receptor (TSLPR) and signaling in response to TSLP, which is regulated by IL-3 and IL-33;and 3) evidence for basophil "functional tolerance'regulated by IL-3. This proposal will investigate the central hypothesis that targeting IL-3 activation of basophils is an effective strategy for treatin basophil-mediated allergic diseases. Studies will use human basophils from healthy controls and patients with allergic diseases, as well as murine basophils from IL-3 deficient and control mice, and state-of-the-art cellular and molecular techniques. The central hypothesis will be investigated by testing the following four corollary hypotheses:
Aim 1 : Investigate the hypothesis that in the absence of IL-3, basophils are in a state of "functional tolerance", and that IL-3 activation of basophils breaks "functional tolerance" and results in heterogeneous subpopulations which may be either in sequential states of activation or stochastically distinct subpopulations;
Aim 2 : Investigate the hypothesis that IL-3 activated basophils respond to TSLP and acquire a functional phenotype that is polarized for inducing Th2 immune responses;
Aim 3 : Investigate the hypothesis that the IL-3 activation state of basophils determines the sensitivity o basophil activation testing for assessment of clinical atopy versus "functional tolerance";
and Aim 4 : Investigate the hypothesis that antagonism, or lack, of IL-3 will result in basophil "functional tolerance" in [a murine model of atopy and a novel in vitro human model of atopy.] These studies have the potential to delineate the mechanisms by which basophils are activated for distinct effector functions, lead to novel assays for clinical evaluation of basophil activatio, and provide proof-of- concept for potentially targeting IL-3 as a novel treatment of allergic disorders.

Public Health Relevance

Basophils are a minor population of human hematopoietic cells, comprising less than 1% of circulating leukocytes, and have been the focus of only limited investigation. Recent studies are beginning to implicate basophils as important for generating and regulating Th2 immune responses, bridging innate and adaptive immune responses, and the pathogenesis of allergic disorders and potentially autoimmune disorders. The goal of this proposal is to elucidate novel regulatory mechanisms by which human basophils are activated and regulate allergic immune responses, and thereby identify potential targets for modulating basophil-mediated allergic inflammation. Findings from this study could bring profound insight into the development of strategies for diagnosing and treating allergic diseases.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
1R01AI097372-01A1
Application #
8631752
Study Section
Hypersensitivity, Autoimmune, and Immune-mediated Diseases Study Section (HAI)
Program Officer
Dong, Gang
Project Start
2013-12-01
Project End
2018-11-30
Budget Start
2013-12-01
Budget End
2014-11-30
Support Year
1
Fiscal Year
2014
Total Cost
$730,925
Indirect Cost
$216,125
Name
Texas A&M University
Department
Other Clinical Sciences
Type
Schools of Medicine
DUNS #
835607441
City
College Station
State
TX
Country
United States
Zip Code
77845
Cromheecke, Jessica L; Nguyen, Kathleen T; Huston, David P (2014) Emerging role of human basophil biology in health and disease. Curr Allergy Asthma Rep 14:408