ABSTRACT: BACKGROUND:Asthma is a chronic inflammatory disease characterized by airway inflammation with mucus hypersecretion and hyperresponsiveness to various nonspecific stimuli. Corticosteroids are usually used to prevent ?2 adrenoceptor (?2AR) desensitization in clinical and experimental practice. But the exact mechanism of corticosteroid effectiveness on ?2AR desensitization is unclear. OBJECTIVES:To find the potential mechanisms related to the protective effects of corticosteroid on salbutamol induced ?2AR desensitization by a proteomics approach. METHODS:Thirty-two BALB/c (6-8 weeks old) mice were divided into four groups: group A, control group, phosphate buffered saline (PBS)-treated group; group B, asthmatic group, treated by ovalbumin (OVA); group C, ?2AR desensitized asthmatic group, treated by OVA and salbutamol (SBT) and group D, corticosteroid-treated ?2AR desensitized asthmatic group, treated with OVA, SBT and Dexamethasone (DEX). After administrated with those drugs, their serum total IgE, bronchoalveolar lavage fluid (BALF) cytokine concentration, airway resistance and membrane receptor number of ?2AR were evaluated. After then, the mice of group C and D were sacrificed, their protein from lung tissue were extracted and then seperated by two-dimensional gel electrophoresis (2DE). Then, the isolated protein spots were analyzed by ImageMaster software and mass spectrometry. Bioinformatic tools were used to search these protein spots and find interesting protein spots associated with corticosteroid protective effect on ?2AR desensitization. Finally, these protein spots were confirmed by Western blotting. RESULTS:With inflammatory cell count, cytokine concentration of BALF, pathological sections, total serum IgE, airway resistance, membrane receptor number and ?2AR total amount changes, asthmatic mouse model and ?2AR desensitization asthmatic mouse model were successfully established. Seventeen protein spots were found different expression between group C and group D, 4 protein spots were down-regulated and 13 protein spots were up-regulated compared to group C. Proteasome subunit beta type 3 was down-regulated. CONCLUSIONS:Increased proteasome subunit beta type 3 expression may be responsible for salbutamol-induced ?2AR desensitization in asthmatic disease, and DEX possibly render the ?2AR resensitization partially by decreasing the content of proteasome.