Chitin Activates Parallel Immune Modules that Direct Distinct Inflammatory Responses via Innate Lymphoid Type 2 and γδ T Cells

Immunity (Impact Factor: 21.56). 03/2014; 40(3). DOI: 10.1016/j.immuni.2014.02.003
Source: PubMed


Chitin, a polysaccharide constituent of many allergens and parasites, initiates innate type 2 lung inflammation through incompletely defined pathways. We show that inhaled chitin induced expression of three epithelial cytokines, interleukin-25 (IL-25), IL-33, and thymic stromal lymphopoietin (TSLP), which nonredundantly activated resident innate lymphoid type 2 cells (ILC2s) to express IL-5 and IL-13 necessary for accumulation of eosinophils and alternatively activated macrophages (AAMs). In the absence of all three epithelial cytokines, ILC2s normally populated the lung but failed to increase IL-5 and IL-13. Although eosinophils and AAMs were attenuated, neutrophil influx remained normal without these epithelial cytokines. Genetic ablation of ILC2s, however, enhanced IL-1β, TNFα, and IL-23 expression, increased activation of IL-17A-producing γδ T cells, and prolonged neutrophil influx. Thus, chitin elicited patterns of innate cytokines that targeted distinct populations of resident lymphoid cells, revealing divergent but interacting pathways underlying the tissue accumulation of specific types of inflammatory myeloid cells.

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    • "IL-33 induction occurred in both hematopoietic and non-hematopoietic cells, particularly in alveolar type 2 cells (Kouzaki et al., 2011; McSorley et al., 2014; R.M.L., unpublished data). Activation of lung ILC2s (Bartemes et al., 2012; Beamer et al., 2013; Doherty et al., 2012; Halim et al., 2012; Van Dyken et al., 2014), Th2 cells (Endo et al., 2015; Kurowska-Stolarska et al., 2008), or both (Iijima et al., 2014), were required to mediate the allergic phenotype , depending on the model system. ILC2s might indirectly support the generation of Th2 cells via IL-13 induction of dendritic cell migration or through direct ILC2/Th2 interactions (Halim et al., 2014; Martinez-Gonzalez et al., 2015; Oliphant et al., 2014). "
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    ABSTRACT: Interleukin-33 (IL-33) is a nuclear-associated cytokine of the IL-1 family originally described as a potent inducer of allergic type 2 immunity. IL-33 signals via the receptor ST2, which is highly expressed on group 2 innate lymphoid cells (ILC2s) and T helper 2 (Th2) cells, thus underpinning its association with helminth infection and allergic pathology. Recent studies have revealed ST2 expression on subsets of regulatory T cells, and for a role for IL-33 in tissue homeostasis and repair that suggests previously unrecognized interactions within these cellular networks. IL-33 can participate in pathologic fibrotic reactions, or, in the setting of microbial invasion, can cooperate with inflammatory cytokines to promote responses by cytotoxic NK cells, Th1 cells, and CD8(+) T cells. Here, we highlight the regulation and function of IL-33 and ST2 and review their roles in homeostasis, damage, and inflammation, suggesting a conceptual framework for future studies. Copyright © 2015 Elsevier Inc. All rights reserved.
    Immunity 06/2015; 42(6):1005-1019. DOI:10.1016/j.immuni.2015.06.006 · 21.56 Impact Factor
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    • "Membrane receptor expression and cytokine secretion is elevated when exposed to carbohydrates, glycosides, or glycolipids (Lucas et al. 2010, Sullivan et al. 2010). These molecules interact as ligands with receptors of macrophages (Satoh et al. 2010), eosinophils and basophils (Reese et al. 2007), epithelial cells (Roy et al. 2012) and other cells (Koller et al. 2011, Van Dyken et al. 2014). After recognition of foreign determinants, cascade signaling is induced which determines the outcome of the immune response. "
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    ABSTRACT: The probability of infection with fungi, as well as parasitic nematodes or arthropods may increase in overcrowded population of animals and human. The widespread overuse of drugs and immunosuppressants for veterinary or medical treatment create an opportunity for many pathogenic species. The aim of the review is to present the common molecular characteristics of such pathogens as fungi and nematodes and other chitin bearing animals, which may both activate and downregulate the immune response of the host. Although these pathogens are evolutionary distinct and distant, they may provoke similar immune mechanisms. The role of chitin in these phenomena will be reviewed, highlighting the immune reactions that may be induced in mammals by this natural polymer.
    Acta Parasitologica 06/2015; 60(2). DOI:10.1515/ap-2015-0047 · 0.91 Impact Factor
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    • "A distinct chitin-binding receptor has yet to be identified, although TLR9, NOD2, and the mannose receptor were shown to interact with and be necessary for chitin-mediated macrophage IL-10 secretion [42]. Furthermore, chitin particles and chitin in fungal extracts mediated lung eosinophil recruitment in mice [43]–[45]. Eosinophils are effector cells associated with allergy and infection with helminths [46], intestinal parasites that, like fungi, express chitin [23]. In response to aspiration of Af5517 conidia, we have observed increased chitin-mediated airway eosinophil recruitment (O’Dea, E.M., Amarsaikhan, N., Li, H., Downey, J., Steele, E., Van Dyken, S.J., Locksley, R.M., Templeton, S.P. "
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    ABSTRACT: The ubiquitous fungal pathogen Aspergillus fumigatus is a mediator of allergic sensitization and invasive disease in susceptible individuals. The significant genetic and phenotypic variability between and among clinical and environmental isolates are important considerations in host-pathogen studies of A. fumigatus-mediated disease. We observed decreased radial growth, rate of germination, and ability to establish colony growth in a single environmental isolate of A. fumigatus, Af5517, when compared to other clinical and environmental isolates. Af5517 also exhibited increased hyphal diameter and cell wall β-glucan and chitin content, with chitin most significantly increased. Morbidity, mortality, lung fungal burden, and tissue pathology were decreased in neutropenic Af5517-infected mice when compared to the clinical isolate Af293. Our results support previous findings that suggest a correlation between in vitro growth rates and in vivo virulence, and we propose that changes in cell wall composition may contribute to this phenotype.
    PLoS ONE 06/2014; 9(6):e100430. DOI:10.1371/journal.pone.0100430 · 3.23 Impact Factor
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