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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Available from: Ari Molofsky, Oct 28, 2015
    • "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non-hematopoietic cells, particularly in alveolar type 2 cells (Kouzaki et al., 2011; McSorley et al., 2014; R.M.L., unpublished data).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
    • "It is tempting to speculate that CHIA, along with its well-documented IL-13- mediating functions (Zhu et al. 2004), might be responsible for the release of CCL2 described by Roy et al. (2012), possibly by binding to chitin directly. Likewise, the epithelial-associated cytokine TSLP, recently reported to contribute to TH2 inflammatory signaling mediated by ILC2s in response to chitin challenge in the murine lung (Van Dyken et al. 2014), is induced in a Chi3L1-dependent manner in the immune responses to S. pneumoniae in murine lungs (Dela Cruz et al. 2012). Again it is tempting to speculate that Chi3L1, which is known to bind chitin (Houston et al. 2003), could be involved in the perception of chitin and the induction of TSLP. "
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    ABSTRACT: Chitin is a vital polysaccharide component of protective structures in many eukaryotic organisms, but seems absent in vertebrates. Chitin or chitin oligomers are therefore prime candidates for non-self molecules, which are recognized and degraded by the vertebrate immune system. Despite the absence of polymeric chitin in vertebrates chitinases and chitinase like proteins are well conserved in vertebrate species. In many studies these proteins have been found to be involved in immune regulation and in mediating the degradation of chitinous external protective structures of invading pathogens. Several important aspects of chitin immunostimulation have recently been uncovered, advancing our understanding of the complex regulatory mechanisms that chitin mediates. Likewise, the last few years have seen large advances in our understanding of the mechanisms and molecular interactions of chitinases and chitinase like proteins in relation to immune response regulation. It is becoming increasingly clear that their function in this context is not exclusive to chitin producing pathogens, but includes bacterial infections and cancer signaling as well. Here we provide an overview of the immune signaling properties of chitin and other closely related biomolecules. We also review the latest literature on chitinases and chitinase like proteins of the GH18 family. Finally, we examine the existing literature on zebrafish chitinases, and propose the use of zebrafish as a versatile model to complement the existing murine models. This could especially be of benefit to the exploration of the function of chitinases in infectious diseases using high throughput approaches and pharmaceutical interventions. © The Author 2015. Published by Oxford University Press.
    Glycobiology 01/2015; 25(5):469-482. DOI:10.1093/glycob/cwv005 · 3.15 Impact Factor
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