Background β2-adrenoceptor （β2AR） desensitization is a common problem in clinical practice, β2AR desensitization proceeds by at least such three mechanisms as heterologous desensitization, homologous desensitization and a kind of agonist-induced rapid phosphorylation by a variety of serine/threonine kinases. It is not clear whether there are other mechanisms, This study aimed to investigate potential mechanisms of β2AR desensitization.Methods Twenty-four BALB/c （6-8 weeks old） mice were divided into three groups, which is, group A, phosphate buffered saline （PBS）-treated; group B, ovalbumin （OVA）-induced; and group C, salbutamol-treated. Inflammatory cell counts, cytokine concentrations of bronchoalveolar lavage fluid （BALF）, pathological sections, total serum IgE, airway responsiveness, membrane receptor numbers and total amount of β2AR were observed. Asthmatic mouse model and β2AR desensitization asthmatic mouse model were established. Groups B and C were selected for two-dimensional gel electrophoresis （2DE） analysis so as to find key protein spots related to β2AR desensitization.Results Asthmatic mouse model and β2AR desensitization asthmatic mouse model were verified by inflammatory cell count, cytokine concentration of BALF, serum IgE level, airway hyperreactivity measurement, radioligand receptor binding assay, Western blot analysis, and pathologic examination. Then the two groups （groups B and C） were subjected to 2DE. Two key protein spots associated with β2AR desensitization, Rho GDP-dissociation inhibitor 2 （RhoGDl2） and peroxiredoxin 5, were found by comparative proteomics （2DE and mass spectrum analysis）.Conclusion Oxidative stress and small G protein regulators may play an important role in the process of β2AR desensitization.v
LIU Hua ZHOU Lin-fu ZHANG Qian QIAN Fen-hong YIN Kai-sheng HUANG Mao ZHANG Xi-long
Background Tyrosine kinase signaling cascades play a critical role in the pathogenesis of allergic airway inflammation. Sunitinib, a multitargeted receptor tyrosine kinase inhibitor, has been reported to exert potent immunoregulatory, anti-inflammatory and anti-fibrosis effects. We investigated whether sunitinib could suppress the progression of airway inflammation, airway hyperresponsiveness （AHR）, and airway remodeling in a murine model of chronic asthma. Methods Ovalbumin （OVA）-sensitized mice were chronically challenged with aerosolized OVA for 8 weeks. Some mice were intragastrically administered with sunitinib （40 mg/kg） daily during the period of OVA challenge. Twelve hours after the last OVA challenge, mice were evaluated for the development of airway inflammation, AHR and airway remodeling. The levels of total serum immunoglobulin E （IgE） and Th2 cytokines （interleukin （IL）-4 and IL-13） in bronchoalveolar lavage fluid （BALF） were measured by ELISA. The expression of phosphorylated c-kit protein in the lungs was detected by immunoprecipitation/Western blotting （IP/WB） analysis. Results Sunitinib significantly inhibited eosinophilic airway inflammation, persistent AHR and airway remodeling in chronic experimental asthma. It reduced levels of total serum IgE and BALF Th2 cytokines and also lowered the expression of phosphorylated c-kit protein in remodelled airways. Conclusions Sunitinib may inhibit the development of airway inflammation, AHR and airway remodeling. It is potentially beneficial to the prevention or treatment of asthma.
