Effects of 1,25-(OH) 2 D3 on Ca2+concentration and PI3K/AKT/mTOR pathway in type Ⅱalveolar epi-thelial cells of rat with pulmonary fibrosis / 医学研究生学报

ABSTRACT

Objective Idiopathic pulmonary fibrosis ( IPF) is a chronic inflammatory disease with unknown etiology and is lack of effective therapy. The aim of this study is to explore the function of Ca2+ and PI3K/AKT/mTOR pathway in the pathogenesis of IPF, and the impact of 1,25?( OH) 2 D3 on Ca2+ and PI3K/AKT/mTOR pathway in type Ⅱalveolar epithelial cells of rat with IPF. Methods 150 male SD rats were randomly divided into 2 groups prevention group ( control groupⅠ, model groupⅠ, medication groupⅠ) and treatment group ( control groupⅡ, model groupⅡ, medication groupⅡ) . The tracheal exposure surgery was operated in control groupⅠ/Ⅱ, and then 200μL sterile physiological saline was administered by intraperitoneal injection of each rats 2 days and 14 days after surgery, separately. Bleomycin(BLM)(5 mg/kg) was in?jected into the trachea of model groupⅠ/Ⅱ, and then vitamin D3 solvent(0.1%ethanol and 99.9%glycol propylene, 1μL/g) was ad?ministered by intraperitoneal injection 2 days and 14 days after surger?y, separately. Bleomycin( BLM) ( 5 mg/kg) was injected into the tra?chea of medication groupⅠ/Ⅱ, and then 1,25?( OH) 2 D3( 2μg/kg) was administered by intraperitoneal injection 2 days and 14 days after surgery, separately. IPF model was built by injecting Bleomycin into the trachea of rats, 1,25?(OH)2D3(2μg/kg) was used to prevent and treat IPF by intraperitoneal injection in medication group. The hydroxyproline content of lung tissue in each group was measured, type Ⅱalveolar epithelial cells were separated from lung tissue and labeled with Fluo?3AM, then concentration of Ca2+ was detected by Laser scanning confocal microscope. The mRNA levels of PI3K, AKT and mTOR in the typeⅡalveolar epithelial cells were tested by RT?PCR. Results Compared with control groupⅠ/Ⅱ at each time point, hydroxyproline content of lung tissue, Ca2+ concentration and expression of PI3K, AKT and mTOR in typeⅡalveolar epithelial cells in model groupⅠ/Ⅱand medication groupⅠ/Ⅱwere sig?nificantly raised( P<0.05 or P<0.01) , but these were significantly reduced in medication groupⅠ/Ⅱcompared with model groupⅠ/Ⅱ( P<0.05 or P<0.01) . Correlation analysis showed that there is significant positive correlation between Ca2+ concentration and mRNA expression levels of PI3K, AKT and mTOR in model groupⅠ/Ⅱ(r=0.5988, r=0.6230, r=0.6603,P<0.01)and medication groupⅠ/Ⅱ( r=0.701 2, r=0.632 3,r=0.740 3,P<0.01) . Conclusion The PI3K/AKT/mTOR pathway plays an important role in devel?opment of IPF. 1,25?( OH) 2 D3 is able to reduce Ca2+concentration in typeⅡalveolar epithelial cells and inhibit the PI3K/AKT/mTOR pathway, and then inhibit the development of IPF.