The G protein-coupled estrogen receptor (GPER) specific agonist G-1 has therapeutic effects in patients with allergic diseases, but any role for G-1 as a therapy for inflammation associated with allergic rhinitis (AR) remains unclear. The structure of the environmental hormone nonylphenol (NP) is very similar to that of estrogen; it binds to the estrogen receptor to produce estrogen-like effects and thus may also bind to the membrane GPER. We explored whether NP administration would reduce the effects of G-1 on AR, the interactions between the two materials, and their mechanisms of action using a murine model of AR. Mice were randomly assigned into control, AR, G-1, and G-1 + NP groups (n = 10/group). AR nasal symptoms were scored. Eosinophils in nasal mucosa were counted after staining with hematoxylin and eosin. Serum ovalbumin (OVA)-specific IgE was determined by ELISA. The proportions of splenic Th1, Th2, and Treg cells were determined by flow cytometry. The expression of transcription factors unique to Th1, Th2, Treg cells and cytokine levels in nasal mucosa were evaluated by real-time PCR and cytometric bead arrays. AR nasal symptoms, including sneezing, nasal scratching, eosinophil infiltration of nasal mucosa, and serum IgE, were reduced in G-1 group. After injection, Th2 cells proportions, Th2-immune response-related cytokines (IL-4, IL-5, and IL-13), and a Th2 cell-specific transcription factor (GATA-3) were significantly decreased in G-1 group. Treg immune response was enhanced (as reflected by Treg cell, IL-10, and Foxp3 levels). The levels of all of these were significantly increased after adding NP, and the Treg immune response was significantly decreased. These results indicate that G-1 attenuated the nasal symptoms, serum OVA-specific IgE, and Th2 cell immune response, whereas it enhanced Treg immune response, in mice with AR. Adding NP weakened these therapeutic effects.
Keywords: Allergic rhinitis; G protein-coupled estrogen receptor; G-1; Nonylphenol; Treg.
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