瘦素通过PI3K／Akt通路对大鼠气道平滑肌细胞凋亡的影响

The effects of leptin on apoptosis of airway smooth muscle cells via the PI3K/Akt signaling pathway

目的观察瘦素对大鼠气道平滑肌细胞（ASMC）蛋白激酶-B（Akt）、磷酸化蛋白激酶-B（Pho-Akt）、B细胞淋巴瘤／白血病-2（Bcl-2）、Bcl-2相关X蛋白（Bax）、半胱氨酸天冬氨酰蛋白酶．3（caspase-3）的表达及细胞凋亡的影响，探讨瘦素影响ASMC凋亡的可能机制。方法体外培养大鼠ASMC，按随机数字表法分为空白对照组、瘦素50μg/L组（Lep50组）、瘦素100μg/L组（Lep100组）、瘦素200μg/L组（Lep200组）及瘦素200μg/L＋LY294002组[1-磷脂酰肌醇3．激酶（P13K）抑制剂组]。各组均孵育24h后用Annexin-V／PI双标记流式细胞仪分析法检测细胞凋亡率，WesternblotOn,0定Akt、Pho-Akt、Bcl-2、Bax和caspase-3的蛋白表达情况。结果Lep50组、Lep100组、Lep200组的细胞凋亡率分别为（3．97±0．39）％、（1．88±0．72）％和（0．77±0．11）％，均低于空白对照组的（7．38±0．49）％（F=89．57，P〈0．05），且各组细胞凋亡率与瘦素浓度呈负相关（r=-0．711，P〈0．05）；P13K抑制剂组凋亡率为（3．29±0．36）％，高于Lep200组（F=89．57，P〈0．01）。Westernblot结果显示随着瘦素浓度的升高Bel-2表达增加，且与浓度呈正相关（r=0．939，P〈0．05），Bax和easpase-3表达下降，与瘦素浓度成负相关（r值分别为-0．908和-0．961，均P〈0．05），Bcl-2／Bax比值增加（F=20．56，P〈0．05），Pho-Akt表达上调，且与瘦素浓度呈正相关（r=0．958，P〈0．05）；P13K抑制剂组较Lep200组Pho-Akt、Bcl-2表达下降（F值分别为32．93和19．48，均P〈0．05），Bax和caspase-3表达升高（F值分别为10．10和29．86，均P〈0．05），Bcl-2／Bax比值下降（F=20．56，P〈0．05）。结论瘦素可以抑制ASMC的凋亡，其机制可能与激活P13K／Akt通路有关。

Objective To observe the effects of leptin on the expression of Akt, Pho-Akt, Bcl-2, Bax, caspase-3 and the apoptosis of airway smooth muscle cells （ASMCs） , and to explore the possible mechanisms. Methods ASMCs were derived fi＇om rat airway tissue and cultured in vitro. The cells were randomly divided into 5 groups including a control group, leptin at concentrations of 50, 100, 200 μg/L groups （group Lep50, Lep100, Lep200）, and PI3K specific antagonist with Lep200 group. Then the cells of different groups were incubated for 24 h. An apoptosis detection kit was used for annexin V and PI staining. The expression of Akt, phosphorylation Akt, Bcl-2, Bax, caspase-3 were measured by Western blot. Results The apoptosis rates of ASMCs in group Lep50, Lep100 and Lep200 were （3.97 ± 0. 39）% , （ 1.88 ± 0. 72 ） % and （0. 77 ± 0. 11 ） % , respectively, all significantly lower than that in the control group （7. 38 ± 0. 49） % （ F = 89. 57, P 〈 0. 05 ）. Furthermore, the concentration of leptin was negatively related to the apoptosis rate （r = -0. 711, P 〈 0. 05 ）. The apoptosis rates of PI3K specific antagonist with Lep200 group （3.29 ± 0. 36） % was higher than that of group Lep200 （ 0. 77 ± 0. 11 ） % （ F = 89. 57, P 〈 0. 01 ）. After the intervention of leptin, the expression of Bel-2 was upregulated and positively correlated with leptin concentration （ r = 0. 939, P 〈 0. 05 ） ; Bax was downregulated and negatively related to the leptin concentration （ r = - 0. 908, P 〈 0. 05 ） ; while the Bcl-2/Bax ratio was raised after leptin treatment （ F = 20. 56, P 〈0. 05）. Leptin inhibited the activation of caspase-3 in the negative way. （r = -0. 961, P 〈 0.05）. The results also showed that leptin significantly increased phosphorylation of Akt that positively related to leptin concentration （ r = 0. 958, P 〈 0. 05 ）. Compared with group Lep200, the expression of Pho-Akl and Bel-2 in PI3K speeifie antagonist with Lep200 group were downregulaled （ F = 32.93, 19.48, vespeclively, P 〈 0. 05 ） , while the expression of Bax and easpase-3 was increased （ F = 10. 10, 29. 86, respectively, P 〈0. 05） ; the Bcl-2/Bax ratio was lower in group Lep200 as compared to the PI3K specific antagonist with Lep200 group （ F = 20. 56, P 〈0. 05）. Conclusion l,eptin can significantly inhibit ASMC apoptosis partially via the PI3K/Akt signaling pathway.