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2007 Progress Report: Mechanisms of Particulate-Induced Allergic Asthma
EPA Grant Number: R832139C003Subproject: this is subproject number 003 , established and managed by the Center Director under grant R832139
(EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
Center: Johns Hopkins Center for Childhood Asthma in the Urban Environment
Center Director: Breysse, Patrick
Title: Mechanisms of Particulate-Induced Allergic Asthma
Investigators: Wills-Karp, Marsha
Institution: Johns Hopkins University
EPA Project Officer: Fields, Nigel
Project Period: November 1, 2003 through October 31, 2008 (Extended to October 31, 2010)
Project Period Covered by this Report: November 1, 2006 through October 31, 2007
RFA: Centers for Children's Environmental Health and Disease Prevention Research (2003)
Research Category: Children's Health , Health Effects
Description:
Objective:The overall goal of the proposal was to establish a causal relationship between particulate matter (PM) exposure and asthma morbidity and to determine the mechanisms by which PM elicits these effects.
The primary objective of this project is to establish a causal relationship between PM exposure and asthma morbidity and to determine the mechanisms by which exposure enhances asthma morbidity. We have determined that a single (0.5 mg/mouse) intratracheal dose of particulate matter collected in urban Baltimore induces significant increases in airway hyperresponsiveness. The increase in AHR was preceded by dramatic increases in BAL granulocytes particularly, eosinophils. These physiological changes were associated with an early Th2 cytokine pattern (IL-5, IL-13, eotaxin), which shifted toward a Th1 pattern as AHR and granulocytes returned to normal levels. We concluded from these studies that ambient PM induces asthma-like parameters in naive mice suggesting that PM exposure may contribute to increases in asthma prevalence.
As we have recently identified complement as a susceptibility gene for asthma in a murine model, we evaluated its role in PM-induced AHR. The responses to PM exposure were compared in complement factor 3 (C3) deficient mice and their wild type controls. Interestingly, C3 deficient mice did not develop AHR, while the wild type mice developed significant AHR in response to particulate exposure. Immunostaining of lung sections with a fluorescently labeled anti-C3 antibody revealed that C3 was deposited along the epithelial surface and in the smooth muscle layer. Thus, complement deposition may be a common mechanism by which airborne particles elicit allergic airway responses.
The specific aims of the proposal were the following:
- To determine the relationship between exposure to airborne indoor PM and asthma morbidity, we will compare the biological effects or PM collected in homes of children with mild and severe asthma stratified for the presence of smokers in the home using the development of asthma symptoms in mice as a readout system.
- To determine the interaction with genetic factors, environmental exposure to allergens, and environmental PM exposures which contribute to asthma morbidity, we will examine the biological effects of exposure to indoor urban Baltimore PM in non-allergic strains of mice.
- To determine the role of complement factor 3 in mediating urban indoor PM-induced inflammation and/or exacerbations of allergic asthmatic symptoms, we will compare the biological effects of PM exposure in C3 deficient and wildtype mice.
- As we have previously shown that PM induces the development of Th2-mediated allergic airway responses, we sought to determine whether AUB exposure activated the major antigen-presenting cell in the lung, the dendritic cell. Interestingly, we have found that PM induces significant elevations in the numbers of lung derived myeloid DC as compared to the plasmacytoid subset. As we and others have previously shown that myeloid DC are immunogenic and induce allergic responses, whereas, plasmactyoid DCs confer tolerance to the development of allergic responses, these studies suggest that PM exposure may enhance allergic responses by altering the balance of immunogenic to tolerogenic DCs present in the lung. In order to begin determining the mechanisms by which AUB may activate mDCs, we hypothesized that AUB may induce changes in the airway epithelium which lead to the recruitment and activation of mDCs. To test this hypothesis, we asked whether AUB-conditioned supernatants influence the activation or cytokine production of DCs.
- Specifically, we cultured mDCs isolated from the bone marrow (BMDDC) of A/J mice and measured the production of the Th1-directing cytokine, IL-12 and the Th2-directing cytokines, IL-6. Interestingly, we find that AUB-conditioned epithelial supernatants preferentially induce the production of the Th2-directing cytokine, IL-6. These results suggest that AUB may induce the production of factors by the airway epithelium that activate DCs to provide Th2 promoting signals to T cells. To determine whether this effect differs from direct effects of AUB on DCs, we cultured BMDDC with AUB, and assessed IL-6 and IL-12 production. We found that direct exposure of BMDDC to AUB induces significant elevations in both cytokines suggesting that direct AUB exposure of DC would lead to a mixed Th1/Th2 response. Thus, our studies suggest that AUB induces changes in the airway epithelial that skew the immune response towards a Th2 response. The nature of these factors and the mechanisms by which AUB induces these factors remain unknown.
- As we have previously shown that different mouse strains manifest differential susceptibility to allergen-induced AHR concomitant with alterations in DC cell recruitment and activation, we compared the responses of mouse strains that are either susceptible (A/J) or resistant (C3H) to the development of allergen-induced AHR to AUB exposure in vivo. We show that similar to their responses to allergen, A/J mice develop AHR in response to AUB exposure, while C3H mice do not develop AHR in response to AUB.
- To begin to determine the potential mechanism(s) underlying the differential susceptibility of A/J and C3H to AUB-induced AHR, we conducted an Affymetrix GeneChip experiment comparing the effects of AUB exposure on gene expression of primary epithelial cells from A/J and C3H mice. The results show that there are significant differences in gene expression patterns at baseline between the two murine strains. Moreover, there are significant differences in AUB-induced gene expression patterns between A/J and C3H mice. The primary differences are in genes in the complement activation pathway (C3, Factor B), oxidative stress pathways (vanin 1, vanin 3, nox), and prostaglandin family genes (PGER3, PGE2), chemokine genes (GM-CSF, CCL20). The finding that complement factor 3 and Factor b are activated in susceptible A/J mice is consistent with our previous finding that AUB-induced AHR is C3 dependent.
- These findings extend our understanding of the mechanisms by which complement is activated in that we show for the first time that it is the alternative not the classical pathway that is upregulated following AUB exposure. These findings are also consistent with our previous finding that complement family components regulate dendritic cell function recruitment and activation in the airways. Secondly, we identified a novel set of genes that are induced by AUB, the vanin family genes. Vanin-1 is an epithelial ectoenzyme with pantetheinase activity which generates the amino-thiol cysteamine through the metabolism of pantothenic acid (vitamin B(5). Vanin deficient mice are protected from oxidative damage induced by UV irradiation and paraquat exposure suggesting that vanin plays a role in oxidative stress. Intriguing it has been shown that A/J mice carry a unique nonsense mutation in vanin-3 which results in the generation of a truncated protein. This defect in the vanin protein in A/J mice has been shown to be associated with susceptibility of A/J mice to malaria.
- Thus it is possible that the differential expression of vanin genes in A/J and C3H may contribute to differences in oxidative stress responses and the subsequent release of chemokines and cytokines from the epithelium. Lastly, we found that genes in the PGE2 family (PGE2, PGRE3) are more highly induced in AUB-exposed epithelial cells from resistant C3H mice. Enhanced PGE2 series prostaglandin production in C3H mice is consistent with their ability to both suppress dendritic cell function and to induce relaxation in airway smooth muscle. Studies are currently underway to determine whether differences in complement family genes, oxidative stress genes or prostaglandin genes play a role in the differential susceptibility of the two murine strains to AUB-induced dendritic cell activation and AHR.
Our plans over the next year include further study of the ability of both outdoor and indoor particulates to induce allergic airway responses. Specifically, we will:
- Explore further the role of the novel candidate genes (vanin, Nox) we identified in AUB-induced dendritic cell activation and development of allergic inflammation.
- Examine the effects of PM collected from homes in inner city Baltimore on allergic airway responses in mice. Specifically, we plan to collect PM by similar means as the AUB from indoor sources in inner city homes. A comparison of different sources of the PM may provide further information regarding the biologically active components of the PM.
Journal Articles on this Report : 5 Displayed | Download in RIS Format
| Other subproject views: | All 19 publications | 19 publications in selected types | All 19 journal articles |
| Other center views: | All 103 publications | 103 publications in selected types | All 100 journal articles |
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Kohl J, Baelder R, Lewkowich IP, Pandey MK, Hawlisch H, Wang L, Best J, Herman NS, Sproles AA, Zwirner J, Whitsett JA, Gerard C, Sfyroera G, Lambris JD, Wills-Karp M. A regulatory role for the C5a anaphylatoxin in type 2 immunity in asthma. Journal of Clinical Investigation 2006;116(3):783-796. |
R832139C003 (2006) R832139C003 (2007) |
not available |
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Kohl J, Wills-Karp M. A dual role for complement in allergic asthma. Current Opinion in Pharmacology 2007;7:283-289. |
R832139C003 (2007) |
not available |
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Kohl J, Wills-Karp M. Complement regulates inhalation tolerance at the dendritic cell/T cell interface. Molecular Immunology 2007;44:44-56. |
R832139C003 (2007) |
not available |
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Perkins C, Wills-Karp M, Finkelman FD. IL-4 induces IL-13-independent allergic airway inflammation. Journal of Allergy and Clinical Immunology 2006;118:410-419. |
R832139C003 (2007) |
not available |
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Wills-Karp M. Complement activation pathways: a bridge between innate and adaptive immune responses in asthma. Proceedings of the American Thoracic Society 2007;4:247-251. |
R832139C003 (2007) |
not available |
, HUMAN HEALTH, Air, Geographic Area, Scientific Discipline, Health, RFA, PHYSICAL ASPECTS, Health Effects, Health Risk Assessment, Physical Processes, particulate matter, Allergens/Asthma, State, Maryland (MD), allergens, children's health, air toxics, respiratory, air pollution, airborne pollutants, children, exposure, asthma triggers, asthma, human exposure, PM
Progress and Final Reports:
2004 Progress Report
2005 Progress Report
2006 Progress Report
Original Abstract
Main Center Abstract and Reports:
R832139 Johns Hopkins Center for Childhood Asthma in the Urban Environment
Subprojects under this Center: (EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
R832139C001 The Epidemiology of Susceptibility to Airborne Particulates and Allergens to Asthma in African Americans
R832139C002 A Randomized Controlled Trial of Behavior Changes in Home Exposure Control
R832139C003 Mechanisms of Particulate-Induced Allergic Asthma
R832139C004 Dendritic Cell Activation by Particulate Matter and Allergen