Background: Asthma is estimated to effect more than 300 million persons worldwide, leading to nearly 250,000 deaths annually. The majority of patients with mild-to-severe asthma have what is deemed ''type-2 high'' asthma, which is driven by the prototypical type 2 cytokines IL-4, IL-5, and IL-13. Studies have indicated that the receptor for advanced glycation end products (RAGE) is a critical molecule in the pathogenesis of experimental asthma/allergic airway inflammation. More specifically, RAGE expressed on stromal cells, rather than hematopoietic cells, is critical to induction of asthma/allergic airway inflammation by driving type 2 inflammatory responses. However, the role of RAGE in directly mediating type 2 cytokine signaling has never been investigated. Objective: The goal of this study was to test the hypothesis that RAGE mediates type 2 cytokine-induced signal transduction, airway inflammation, and mucus metaplasia in the lungs. Methods: Wild-type (WT) and RAGE knockout (RAGE 2/2) mice, were intranasally administered rIL-5/rIL-13 or rIL-4 alone, and signal transducer and activator of transcription 6 (STAT6) signaling, airway inflammation, and mucus metaplasia were assessed. A RAGE small-molecule antagonist was used to determine the effects of pharmacologically inhibiting RAGE on type 2 cytokine-induced effects. Results: Administration of type 2 cytokines induced pronounced airway inflammation and mucus metaplasia in WT mice, which was nearly completely abrogated in RAGE 2/2 mice. In addition, treatment with a RAGE-specific antagonist diminished the effects of type 2 cytokines in WT mice and in primary human bronchial epithelial cell cultures. Genetic ablation or pharmacologic inhibition of RAGE blocks the effects of IL-13 and IL-4 by inhibiting sustained STAT6 activation and downstream target gene expression in mice and in human bronchial epithelial cells. Conclusions: This study is the first to indicate that RAGE is a critical component of type 2 cytokine signal transduction mechanisms, which is a driving force behind type 2-high asthma.
Enhanced VCAM-1 expression in the lungs by HDM, AA, or rIL-33 exposure was found to be RAGE dependent. In addition, stimulation of primary mouse lung endothelial cells with IL-33 induced VCAM-1 expression in WT, but not RAGE-KO cells. Administration of VCAM-1 and β7 integrin blocking antibodies reduced IL-33 induced eosinophilic inflammation, mucus metaplasia, and type 2 inflammatory responses CONCLUSION: This study demonstrates that allergen and cytokine-induced VCAM-1 expression is RAGE dependent, and contributes to lung ILC2 accumulation and downstream eosinophilic inflammation, mucus metaplasia, and type 2 inflammatory responses. This article is protected by copyright. All rights reserved.
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