A murine model of eosinophilic chronic rhinosinusitis using the topical application of a vitamin D3 analog.

Background: Eosinophilic chronic rhinosinusitis (ECRS) is a chronic inflammatory disease, characterized by eosinophilic infiltration, T‐helper type 2 (Th2‐type) response, and olfactory dysfunction. A master regulator of Th2‐type inflammation, thymic stromal lymphopoietin (TSLP), is important for basophil activation. TSLP‐elicited basophils are a key factor in the pathogenesis of ECRS. Methods: In order to elucidate the mechanisms of ECRS in humans, we aimed to establish a murine model of ECRS based on TSLP production in response to the topical application of MC903 (a vitamin D3 analog) and the subsequent TSLP‐induced basophil activation. Histological analyses were performed to assess immune cell infiltration into the nasal mucosa and to explore the impact of eosinophilic inflammation on the olfactory epithelium. The status of Th2‐type inflammation was evaluated by quantitative real‐time PCR and enzyme‐linked immunosorbent assay (ELISA). Results: Eosinophils, basophils, and M2 macrophages increased significantly in the nasal mucosa of the mice treated with MC903 and ovalbumin (OVA), compared to those treated with OVA alone or the controls. Quantitative real‐time PCR and ELISA revealed elevated expression of interleukin (IL)‐4, IL‐5, IL‐13, TSLP, the chemokine CCL11, and CCL24 in the nasal mucosa of the ECRS mice. In parallel, thinned olfactory epithelium and decreased mature olfactory sensory neurons were observed in the ECRS mice. Conclusions: Our model of ECRS displayed Th2‐type inflammation in the sinonasal region, including both eosinophil infiltration and basophil infiltration. Additionally, olfactory epithelium turned out to be affected by eosinophilic inflammation. These features are consistent with the characteristics of the human ECRS. [ABSTRACT FROM AUTHOR]