Bo Liu

Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, United States

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Publications (4)50.47 Total impact

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    ABSTRACT: Background: Food-mediated allergic reactions have emerged as a major health problem. The underlying mechanisms that promote uncontrolled type 2 immune responses to dietary allergens in the gastrointestinal tract remain elusive. Objective: We investigated whether altering IL-25 signaling enhances or attenuates allergic responses to food allergens. Methods: Mice of an IL-25 transgenic mouse line (iIL-25Tg mice), which constitutively overexpress intestinal IL-25, and Il17rb(-/-) mice, in which Il17rb gene expression is disrupted, were sensitized and gavage fed with ovalbumin (OVA). We assessed symptomatic characteristics of experimental food allergy, including incidence of diarrhea, incidence of hypothermia, intestinal TH2 immune response, and serum OVA-specific IgE and mast cell protease 1 production. Results: Rapid induction of Il25 expression in the intestinal epithelium preceded onset of the anaphylactic response to ingested OVA antigen. iIL-25Tg mice were more prone and Il17rb(-/-) mice were more resistant to experimental food allergy. Resident intestinal type 2 innate lymphoid cells (ILC2s) were identified as the major producers of IL-5 and IL-13 in response to IL-25. Reconstituting irradiated wild-type mice with Rora(-/-) or Il17rb(-/-) bone marrow resulted in a deficiency or dysfunction of the ILC2 compartment, respectively, and resistance to experimental food allergy. Repeated intragastric antigen challenge induced a significant increase in numbers of CD4(+) TH2 cells, which enhance IL-25-stimulated IL-13 production by ILC2s ex vivo and in vivo. Finally, reconstituted IL-13-deficient ILC2s had reduced capability to promote allergic inflammation, resulting in increased resistance to experimental food allergy. Conclusion: IL-25 and CD4(+) TH2 cells induced by ingested antigens enhance ILC2-derived IL-13 production, thereby promoting IgE-mediated experimental food allergy.
    No preview · Article · Nov 2015 · The Journal of allergy and clinical immunology
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    ABSTRACT: Experimental IgE-mediated food allergy depends on intestinal anaphylaxis driven by interleukin-9 (IL-9). However, the primary cellular source of IL-9 and the mechanisms underlying the susceptibility to food-induced intestinal anaphylaxis remain unclear. Herein, we have reported the identification of multifunctional IL-9-producing mucosal mast cells (MMC9s) that can secrete prodigious amounts of IL-9 and IL-13 in response to IL-33, and mast cell protease-1 (MCPt-1) in response to antigen and IgE complex crosslinking, respectively. Repeated intragastric antigen challenge induced MMC9 development that required T cells, IL-4, and STAT6 transcription factor, but not IL-9 signals. Mice ablated of MMC9 induction failed to develop intestinal mastocytosis, which resulted in decreased food allergy symptoms that could be restored by adoptively transferred MMC9s. Finally, atopic patients that developed food allergy displayed increased intestinal expression of Il9- and MC-specific transcripts. Thus, the induction of MMC9s is a pivotal step to acquire the susceptibility to IgE-mediated food allergy.
    Full-text · Article · Sep 2015 · Immunity
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    ABSTRACT: Type-2 innate lymphoid cells (ILC2s) and the acquired CD4(+) Th2 and Th17 cells contribute to the pathogenesis of experimental asthma; however, their roles in Ag-driven exacerbation of chronic murine allergic airway diseases remain elusive. In this study, we report that repeated intranasal rechallenges with only OVA Ag were sufficient to trigger airway hyperresponsiveness, prominent eosinophilic inflammation, and significantly increased serum OVA-specific IgG1 and IgE in rested mice that previously developed murine allergic airway diseases. The recall response to repeated OVA inoculation preferentially triggered a further increase of lung OVA-specific CD4(+) Th2 cells, whereas CD4(+) Th17 and ILC2 cell numbers remained constant. Furthermore, the acquired CD4(+) Th17 cells in Stat6(-/-)/IL-17-GFP mice, or innate ILC2s in CD4(+) T cell-ablated mice, failed to mount an allergic recall response to OVA Ag. After repeated OVA rechallenge or CD4(+) T cell ablation, the increase or loss of CD4(+) Th2 cells resulted in an enhanced or reduced IL-13 production by lung ILC2s in response to IL-25 and IL-33 stimulation, respectively. In return, ILC2s enhanced Ag-mediated proliferation of cocultured CD4(+) Th2 cells and their cytokine production, and promoted eosinophilic airway inflammation and goblet cell hyperplasia driven by adoptively transferred Ag-specific CD4(+) Th2 cells. Thus, these results suggest that an allergic recall response to recurring Ag exposures preferentially triggers an increase of Ag-specific CD4(+) Th2 cells, which facilitates the collaborative interactions between acquired CD4(+) Th2 cells and innate ILC2s to drive the exacerbation of a murine allergic airway diseases with an eosinophilic phenotype. Copyright © 2015 by The American Association of Immunologists, Inc.
    No preview · Article · Mar 2015 · The Journal of Immunology
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    ABSTRACT: The inflammatory cytokine interleukin (IL)-17 is involved in the pathogenesis of allergic diseases. However, the identity and functions of IL-17-producing T cells during the pathogenesis of allergic diseases remain unclear. Here, we report a novel subset of T(H)2 memory/effector cells that coexpress the transcription factors GATA3 and RORγt and coproduce T(H)17 and T(H)2 cytokines. Classical T(H)2 memory/effector cells had the potential to produce IL-17 after stimulation with proinflammatory cytokines IL-1β, IL-6, and IL-21. The number of IL-17-T(H)2 cells was significantly increased in blood of patients with atopic asthma. In a mouse model of allergic lung diseases, IL-17-producing CD4(+) T(H)2 cells were induced in the inflamed lung and persisted as the dominant IL-17-producing T cell population during the chronic stage of asthma. Treating cultured bronchial epithelial cells with IL-17 plus T(H)2 cytokines induced strong up-regulation of chemokine eotaxin-3, Il8, Mip1b, and Groa gene expression. Compared with classical T(H)17 and T(H)2 cells, antigen-specific IL-17-producing T(H)2 cells induced a profound influx of heterogeneous inflammatory leukocytes and exacerbated asthma. Our findings highlight the plasticity of T(H)2 memory cells and suggest that IL-17-producing T(H)2 cells may represent the key pathogenic T(H)2 cells promoting the exacerbation of allergic asthma.
    Full-text · Article · Oct 2010 · Journal of Experimental Medicine

Publication Stats

158 Citations
50.47 Total Impact Points

Institutions

  • 2015
    • Cincinnati Children's Hospital Medical Center
      • Division of Allergy and Immunology
      Cincinnati, Ohio, United States
  • 2010
    • University of Cincinnati
      • Division of Immunology, Allergy & Rheumatology
      Cincinnati, OH, United States