Objective: To investigate the effects and mechanism of intranasal interferon gamma (IFN-gamma) in the treatment of allergic rhinitis.
Methods: Ovalbumin (OVA) absorbed to aluminum hydroxide was used to construct the allergic rhinitis model (group C), and the normal control group (group A), the allergic rhinitis model group (group B) and beclomethasone dipropionate group (group D) consisted of 8 rats for each. PBS 50 microl was absorbed to group B, IFN-gamma 1 microg was absorbed to group C and beclomethasone dipropionate 3.5 microg was absorbed to group D on day 31 to day 38 once daily once nasal cavity. The nasal lavage fluid was collected on day 39, and the cellular constituents, levels of interleukin-4 (IL-4), interleukin-5 (IL-5) and IgE were determined, together with the pathologic changes and expression of GATA-3 were observed.
Results: Decrease of eosinophils [(0.005 +/- 0.003) x 10(4)/ml, x +/- s] was seen in nasal lavage fluid of group C as comparing with group B [(0.225 +/- 0.060) x 10(4)/ml, (P < 0.01)], and the levels of IL-4 (7.8 +/- 3.5) pg/ml and IL-5 (12.5 +/- 4.3) pg/ml decreased significantly in comparing with group B (P < 0.01). The serum levels of total IgE (38.5 +/- 9.6) microg/ml and ovalbumin-specific IgE (19.8 +/- 5.4) IU/ml decreased significantly in comparing with those of group B (P < 0.01). In group B, mucosal congestion and edema thickening with inflammatory cells infiltration mainly of eosinophils; in group C, the above mentioned changes were much more ameliorated. Immunohistochemistry showed significant increase of GATA-3 expression in the nasal tissue of group B but much lesser than that in group C.
Conclusions: IFN-gamma can inhibit the composition of IL-4 and IL-5, and inhibit the airway inflammation with eosinophilic infiltration and the serum levels of total IgE and ovalbumin specific IgE, probably through the mechanism of restraining the Th2 reaction by blockade of GATA-3 expression in the nasal tissue.