Effects of 4-DAMP on allergic rhinitis in guinea pigs and its potential mechanism

Allergic rhinitis (AR) is a non-infectious chronic inflammatory disease of the nasal mucosa mainly mediated by immunoglobulin E (IgE), which seriously affects the life quality of affected patients. This study aimed to observe the effects of 1,1-dimethyl-4-diphenylacetoxypiperidinium iodide (4-DAMP; a selective M3 receptor antagonist) on ovalbumin (OVA)-induced AR guinea pigs, and to explore its potential mechanism of involvement.

An AR model was established by inducing male guinea pigs (4-6 weeks of age) with OVA. AR guinea pigs were randomly divided into a model group, 0.6 mg/kg ipratropium bromide (IB) group, 0.12 and 0.6 mg/kg 4-DAMP group (n=18). The 0.6 mg/kg IB group, 0.12 and 0.6 mg/kg 4-DAMP group animals were treated with IB (0.6 mg/kg) and 4-DAMP (0.12 or 0.6 mg/kg) by intranasal instillation per nostril daily. Animals in the model group and normal group were treated with saline as control. The AR symptom scores were counted and nasal secretion weights were measured. Histopathological methods were used to observe nasal mucosa. Enzyme-linked immunosorbent assay (ELISA) was used to detect the levels of histamine and cytokines. Western blot and quantitative real-time polymerase chain reaction (qRT-PCR) were used to detect the expressions of mucin 5AC (MUC5AC), matrix metalloproteinase 9 (MMP9), and epidermal growth factor receptor (EGFR).

Compared with model group animals, the AR symptom scores and nasal secretion weights of animals treated with 4-DAMP were reduced significantly, goblet cell metaplasia was reversed, and eosinophil infiltration was visibly alleviated. The levels of histamine and cytokines in nasal lavage fluid (NLF) were decreased, and the protein and messenger RNA (mRNA) expressions of MUC5AC, MMP9, and EGFR were inhibited.

Treatment with 4-DAMP has a certain effect on AR, especially for mucus hypersecretion, which provides a new idea for clinical treatment of AR.