维生素D3对博来霉素诱发小鼠肺纤维化的影响

Effects of vitamin D3 on bleomycin-induced pulmonary fibrosis in mice

目的探讨维生素D3(VitD3)对博来霉素(BLM)诱发小鼠肺纤维化的保护作用及其机制。方法 96只成年C57BL/6J雄性小鼠(8周,24~26 g)随机分为如下8组:生理盐水对照组(对照组),单纯维生素D3组(VitD3组),博来霉素组(BLM 1 d、7 d和21 d组),维生素D3+博来霉素组(VitD3+BLM 1 d、7 d和21 d组)。BLM组经气管单次给予BLM,剂量为3 mg/kg,VitD3+BLM组:在BLM(3 mg/kg)处理前30 min及处理后每24 h经腹腔给予一次1,25(OH)_2D_3,剂量为1μg/kg,对照组和VitD3组给予等量的生理盐水或1,25(OH)_2D_3,小鼠分别于BLM或生理盐水处理后1 d、7 d和21 d剖杀并取肺组织。用HE染色法检测肺病理改变,用免疫组化检测肺3-硝基酪氨酸水平,RT-PCR检测肺氧化及抗氧化酶mRNA水平。结果 HE染色提示BLM处理引起肺组织破坏及间质纤维化,1,25(OH)_2D_3显著减轻BLM诱导的肺组织破坏及间质纤维化。RT-PCR提示BLM引起肺组织氧化酶基因表达上调(P<0.05),抗氧化酶基因表达下调(P<0.05)。1,25(OH)_2D_3处理显著抑制BLM引起的肺脏氧化酶基因表达上调及抗氧化酶基因下调(P<0.05)。免疫组化结果提示,1,25(OH)_2D_3明显减少BLM所致肺3-硝基酪氨酸残留。结论维生素D3可能通过抗肺氧化应激作用减轻BLM诱发的肺组织破坏及间质纤维化。

Objective To investigate the effects of vitamin D3 on bleomycin（ BLM）-induced pulmonary fibrosis in mice. Methods 96 adult male C57 BL/6 J mice（ 8 weeks,24 26 g） were randomly divided into eight groups：Control group,vitamin D3（ VitD3） group,BLM 1 d,7 d and 21 d groups,and VitD3 ＋ BLM 1 d,7 d and 21 d groups. In bleomycin group,mice were intratracheally injected with bleomycin（ 3 mg/kg）. In VitD3 ＋ BLM group,mice were intraperitoneally injected with 1,25（ OH）2D3（ 1 μg/kg） daily,beginning at 30 min before BLM injection. VitD3 mice were injected with 1,25（ OH）2D3（ 1 μg/kg） daily. Control mice were injected with saline daily. Mice were euthanized at 1 d,7 d,and 21 d after BLM,respectively. Some lungs were collected for realtime RT-PCR. Some lungs were excised for histopathologic examination and immunohistochemistry. Results As expected,BLM-induced damage of alveolar structure and pulmonary fibrosis in mice. Interestingly,1,25（ OH）2D3 attenuated BLM-induced damage of alveolar structure and pulmonary fibrosis in mice. Further study found that BLM up-regulated oxidant enzyme gene expression and down-regulated antioxidant enzyme gene expression. 1,25（ OH）2D3 inhibited BLM-induced up-regulation of oxidant enzyme gene and down-regulation of antioxidant enzyme gene. Moreover,strong 3-nitrotyrosine immunoreactivity was observed in the lungs 1 d,7 d and 21 d after BLM injection,and 1,25（ OH）2D3 significantly attenuated BLM-induced protein nitration in the lungs. Conclusion Vitamin D3 may reduce BLM-induced pulmonary tissue destruction and interstitial fibrosis through anti-pulmonary oxidative stress.