Purpose: Staphylococcus aureus (S. aureus) is an important bacterial pathogen, which creates infective inflammation to human being and animals. Mangiferin (MG) is one of the natural flavonoids with anti-inflammatory, anti-bacterial, and anti-oxidative properties. However, the anti-apoptosis and anti-autophagy of MG are unknown. Hence, this study was aimed to research the inhibition of MG on S. aureus-induced apoptosis and autophagy in RAW264.7 cells.
Methods: The RAW264.7 cells were pretreated with MG, or pretreated with SP600125 or anisomycin synchronously, and then infected with S. aureus (MOI=100:1). The viability and proliferation status of RAW264.7 cells were detected by MTT and EdU assay. The relative expression of TNF-α, IL-6 and IL-10 protein was tested with ELISA. The levels of Bax, Bcl-2, caspase-3, c-Jun N-terminal kinase (JNK), extracellular-regulated protein kinase (ERK), p38, LC3, Beclin-1, p62, phosphorylated JNK, phosphorylated p38 and phosphorylated ERK in cells were detected by Western blotting. The apoptosis rate of RAW264.7 cells was analyzed by flow cytometric assay.
Results: The study showed that MG significantly attenuated RAW264.7 cells apoptosis and autophagy caused by S. aureus. MG alleviated S. aureus-induced apoptosis by down-regulating the protein level of active caspase-3 and Bax and up-regulating the level of Bcl-2. MG also inhibited S. aureus-induced autophagy via decreasing the protein level of LC3-II/LC3-I and Beclin-1 or increasing the protein expression of p62. This protective role was dependent on the up-regulation of JNK signal pathway, which was confirmed by using JNK agonist and inhibitor.
Conclusion: Our results demonstrated that MG might protect RAW264.7 cells from S. aureus-induced apoptosis and autophagy via inhibiting JNK/Bax-dependent signal pathway. Therefore, MG may be a potential agent against pathological cell damage induced by S. aureus infection.

Keywords: mangiferin, Staphylococcus aureus, apoptosis, autophagy


中文翻译：

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芒果苷抑制金黄色葡萄球菌诱导的RAW264.7细胞凋亡和自噬

目的：金黄色葡萄球菌（S. aureus）是一种重要的细菌病原体，对人和动物造成感染性炎症。芒果苷 (MG) 是一种具有抗炎、抗菌和抗氧化特性的天然类黄酮。然而，MG的抗细胞凋亡和抗自噬作用尚不清楚。因此，本研究旨在研究MG对金黄色葡萄球菌诱导的RAW264.7细胞凋亡和自噬的抑制作用。
方法： RAW264.7细胞用MG预处理，或用SP600125或茴香霉素同步预处理，然后感染金黄色葡萄球菌。(MOI=100:1)。MTT法和EdU法检测RAW264.7细胞的活力和增殖状态。ELISA检测TNF-α、IL-6和IL-10蛋白的相对表达。Bax、Bcl-2、caspase-3、c-Jun N-末端激酶 (JNK)、细胞外调节蛋白激酶 (ERK)、p38、LC3、Beclin-1、p62、磷酸化 JNK、磷酸化 p38 和磷酸化的水平通过蛋白质印迹检测细胞中的ERK。流式细胞仪检测RAW264.7细胞凋亡率。
结果：研究表明，MG显着减弱金黄色葡萄球菌引起的RAW264.7细胞凋亡和自噬。MG缓解金黄色葡萄球菌- 通过下调活性 caspase-3 和 Bax 的蛋白水平和上调 Bcl-2 的水平诱导细胞凋亡。MG 还通过降低 LC3-II/LC3-I 和 Beclin-1 的蛋白质水平或增加 p62 的蛋白质表达来抑制金黄色葡萄球菌诱导的自噬。这种保护作用依赖于 JNK 信号通路的上调，这通过使用 JNK 激动剂和抑制剂得到证实。
结论：我们的研究结果表明，MG可能通过抑制JNK/Bax依赖的信号通路保护RAW264.7细胞免受金黄色葡萄球菌诱导的细胞凋亡和自噬。因此，MG可能是对抗金黄色葡萄球菌感染引起的病理细胞损伤的潜在药物。

关键词：芒果苷,金黄色葡萄球菌, 细胞凋亡, 自噬