目的：探讨M2型巨噬细胞来源的小细胞外囊泡（M2 macrophages-derived small extracellular vesicle, M2-sEV）对慢性间歇性缺氧（chronic intermittent hypoxia，CIH）诱导的H9C2心肌细胞损伤的影响及机制。方法：白介素-4（interleukin 4，IL-4）诱导巨噬细胞向M2型极化，实时荧光定量PCR（real time fluorogenic quantitative polymerase chain reaction, qRT-PCR）检测M2型标志物CD206、精氨酸酶-1（arginase-1,Arg-1）表达水平。提取并鉴定M2-sEV。将H9C2细胞分为对照组（CON组）、CIH组、CIH+M2-sEV组。CCK8法检测细胞活力，qRT-PCR和蛋白质印迹法检测缺氧诱导因子1α（hypoxia inducible factor 1 α, HIF-1α）、IL-6、肿瘤坏死因子-α（tumor necrosis factor-α，TNF-α）和转化生长因子-β（transforming growth factor-β，TGF-β）等炎症因子，活化的胱天蛋白酶3（cleaved caspase-3）、活化的胱天蛋白酶9、B细胞淋巴瘤2（B cell lymphoma-2, Bcl-2）和凋亡蛋白Bcl-2相关X蛋白（Bcl-2 associated X protein, Bax）等凋亡因子，内质网跨膜蛋白肌醇酶1α（inositol-requiring enzyme 1α，IRE1α）、转录因子剪接型X-盒结合蛋白1（spliced X-box binding protein 1，XBP1）、转录激活因子6（activating transcription factor 6, ATF6）和葡萄糖调节蛋白78（glucose-regulated protein 78，GRP78）等内质网应激因子。结果：成功极化M2型巨噬细胞，并获取M2-sEV。CCK8检测显示，M2-sEV可提高CIH下H9C2心肌细胞增殖活性。qRT-PCR和蛋白质印迹法显示，与CON组比，CIH组HIF-1α、IL-6、TNF-α、TGF-β、活化的胱天蛋白酶3、活化的胱天蛋白酶9、Bax、IRE1α、XBP1、ATF6、GRP78表达水平明显增高（均P<0.05），Bcl-2表达水平降低、Bax/Bcl-2比值增高（均P<0.05）；加入M2-sEV共孵育后，上述缺氧诱导因子、炎症因子、促凋亡蛋白、内质网应激因子等表达均显著降低（均P<0.05），抗凋亡蛋白Bcl-2表达增高、Bax/Bcl-2比值降低（均P<0.05）。结论：M2-sEV减轻CIH诱导的H9C2细胞损伤，其机制可能与下调内质网应激水平，抑制炎症反应和心肌细胞凋亡有关。

Objective To investigate the effect and mechanism of M2 macrophages-derived small extracellular vesicle (M2-sEV) on injury of H9C2 cardiomyocytes induced by chronic intermittent hypoxia (CIH). Methods Interleukin-4(IL-4) was used to induce the polarization of RMa-bm macrophages to M2-type. The mRNA expression levels of M2-type markers CD206 and arginase-1（Arg-1） were detected by quantitative reverse transcription PCR (qRT-PCR). M2-sEV were extracted and identified. The signature proteins CD9, CD63 and CD81 of M2-sEV were detected by Western blotting(WB). H9C2 cells were randomly divided into control（CON） group, CIH group and CIH+M2-sEV group. CCK8 was used to detect cell viability, and qRT-PCR and WB were respectively used to detect mRNA and protein expression of hypoxia-inducible factor-1α (HIF-1α）, IL-6、tumor necrosis factor-α（TNF-α）、transforming growth factor-β（TGF-β） and apoptotic factors(cleaved caspase-3、cleaved caspase-9、Bcl-2、Bax) as well as endoplasmic reticulum stress factors (IRE1α、XBP1、ATF6、GRP78). Results M2-type macrophages were polarized successfully and M2-sEV were extracted successfully. CCK8 showed that M2-sEV increased the proliferation activity of H9C2 cardiomyocytes under CIH. Compared with the CON group, the expression level of HIF-1α, inflammatory factors (IL-6,TNF-α,TGF-β), pro-apoptotic proteins(cleaved caspase-3, cleaved caspase-9, Bax) and endoplasmic reticulum stress factors (IRE1α, XBP1, ATF6, GRP78) were significantly increased in the CIH group(P<0.05) in both mRNA and protein level. The protein level of Bcl-2 in the CIH group was decreased, and the ratio of Bax/Bcl-2 was increased in the CIH group (P<0.05). However, after co-incubating with M2-sEV, the expressions of HIF-1α, inflammatory factors, pro-apoptotic proteins and endoplasmic reticulum stress factors in CIH group were significantly decreased (P<0.05), and the expression of Bcl-2 and the ratio of Bax/Bcl-2 were also decreased (P<0.05). Conclusions M2-sEV can alleviate the injury of H9C2 cell induced by CIH, which is related to the downregulation of endoplasmic reticulum stress, inhibition of inflammation and reduction of apoptosis.