Stromal Archives - World Asthma Foundation

IL-33 and Thymic Stromal Lymphopoietin Mediate Immune Pathology in Response to Chronic Airborne Allergen Exposure.

J Immunol. 2014 Jul 11;

Authors: Iijima K, Kobayashi T, Hara K, Kephart GM, Ziegler SF, McKenzie AN, Kita H

Abstract
Humans are frequently exposed to various airborne allergens in the atmospheric environment. These allergens may trigger a complex network of immune responses in the airways, resulting in asthma and other chronic airway diseases. In this study, we investigated the immunological mechanisms involved in the pathological changes induced by chronic exposure to multiple airborne allergens. Naive mice were exposed intranasally to a combination of common airborne allergens, including the house dust mite, Alternaria, and Aspergillus, for up to 8 wk. These allergens acted synergistically and induced robust eosinophilic airway inflammation, specific IgE Ab production, type 2 cytokine response, and airway hyperresponsiveness in 4 wk, followed by airway remodeling in 8 wk. Increased lung infiltration of T cells, B cells, and type 2 innate lymphoid cells was observed. CD4(+) T cells and type 2 innate lymphoid cells contributed to the sources of IL-5 and IL-13, suggesting involvement of both innate and adaptive immunity in this model. The lung levels of IL-33 increased quickly within several hours after allergen exposure and continued to rise throughout the chronic phase of inflammation. Mice deficient in IL-33R (Il1rl1(-/-)) and thymic stromal lymphopoietin receptor (Tslpr(-/-)) showed significant reduction in airway inflammation, IgE Ab levels, and airway hyperresponsiveness. In contrast, mice deficient in IL-25R or IL-1R showed minimal differences as compared with wild-type animals. Thus, chronic exposure to natural airborne allergens triggers a network of innate and adaptive type 2 immune responses and airway pathology, and IL-33 and thymic stromal lymphopoietin most likely play key roles in this process.

PMID: 25015831 [PubMed – as supplied by publisher]

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Flagellin Induces the Expression of Thymic Stromal Lymphopoietin in Human Keratinocytes via Toll-Like Receptor 5.

Int Arch Allergy Immunol. 2010 Nov 25;155(1):31-37

Authors: Le TA, Takai T, Vu AT, Kinoshita H, Chen X, Ikeda S, Ogawa H, Okumura K

Background: Thymic stromal lymphopoietin (TSLP), highly expressed by keratinocytes in skin lesions of atopic dermatitis patients and bronchial epithelial cells in asthma, plays a key role in allergic diseases. Information on triggers for the release of TSLP in keratinocytes is still limited. Keratinocytes express Toll-like receptor (TLR) 5, the ligand for which is flagellin, the major structural protein of the flagella of Gram-negative bacteria. IL-4, IL-13 and TNF-? (Th2/TNF) are associated with allergic diseases. TGF-?, one of the ligands for the epidermal growth factor receptor, is overexpressed in keratinocytes in atopic dermatitis. We investigated the induction of TSLP expression in keratinocytes stimulated with flagellin and its modulation by the Th2/TNF cytokines and TGF-?. Methods: Primary human keratinocytes were stimulated with flagellin with or without cytokines. The TSLP released was measured by ELISA. Gene expression was analyzed by quantitative real-time PCR. Results: Stimulation of keratinocytes with flagellin induced the release of TSLP protein and upregulation of the gene expression of TSLP and other pro-inflammatory molecules. The flagellin-induced release of TSLP was enhanced by the Th2/TNF cytokines or TGF-?. Small interfering RNA-mediated knockdown of TLR5 expression suppressed the flagellin-induced TSLP gene expression. Conclusions: Flagellin induces TSLP expression in keratinocytes via TLR5 and the expression can be upregulated by a cytokine milieu with Th2/TNF or TGF-?, suggesting that exposure of barrier-defective skin to Gram-negative bacteria or environmental flagellin contributes to the initiation and/or amplification of Th2-type skin inflammation including atopic dermatitis through the induction of TSLP expression in keratinocytes.

PMID: 21109746 [PubMed – as supplied by publisher]

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