趋化因子配体16参与心肌梗死过程及其在体外对巨噬细胞吞噬功能的影响

Involvement of chemokine CXCL16 in myocardial infarction and its influence on phagocytic activity of macrophage in vitro

目的探讨趋化因子配体16（CXCL16）在心肌梗死早期是否升高及其在体外对巨噬细胞吞噬功能的影响。方法野生雄性C57BL／6J小鼠40只按随机数字表随机分为心肌梗死组和假手术组，每组各20只；心肌梗死组开胸结扎小鼠冠脉前降支，假手术组只给予开胸处理；术后立即行心电图检查；于3d时每组各处死10只小鼠，ELISA检测外周血清中CXCL16的表达；心脏组织病理切片，HE染色观察心脏组织的结构改变和炎症浸润情况；免疫组化检测CXCL16的表达；其余每组各10只小鼠于28d时显微超声检NsJ,鼠心脏结构及功能；心脏组织病理切片，Masson三原色法检测心脏胶原沉积；HE染色观察心脏组织的结构改变和炎症浸润情况；免疫组化检测CXCL16的表达；体外实验分离小鼠骨髓单核细胞，刺激分化为巨噬细胞后转染CXCL16腺病毒及绿色荧光蛋白（GFP）对照，并与小鼠心脏细胞碎片共培养，流式细胞仪检测巨噬细胞吞噬功能。结果与假手术组相比，心肌梗死手术后小鼠即刻出现心律加快及ST段抬高；3d时外周血CXCL16水平上调[（1079±176）pg／ml比（611±37）pg／ml，P=0．032]，梗死区心肌细胞坏死，大量炎症细胞浸润；免疫组化染色可见CXCL16表达上调；28d时心肌梗死组左室射血分数降低（13．29％±2．83％比48．92％±5．46％，P〈0．01），梗死区胶原沉积，炎症消退，免疫组化见CXCLl6表达下降；流式细胞术检测可见巨噬细胞转染CXCL16腺病毒后吞噬功能增强（17．11％±0．87％比7．91％±0．71％，P〈0．01）。结论小鼠心肌梗死早期CXCL16表达上调，炎症细胞浸润，体外CXCL16在巨噬细胞过表达能促进其对细胞碎片的吞噬作用。

Objective To explore whether chemokine CXCL16 is up-regulated after myocardial infarction and promotes the phagocytic activity of macrophage in vitro. Methods Forty wild-type mice were randomly separated into 2 groups （ n = 20 each ）. Group A had the ligation of left anterior descending coronary artery while group B underwent a sham operation. Electrocardiogram was used to assess whether the operation was successful or not. Three days after surgery, 10 animals of each group were sacrificed and the serum level of CXCL16 was detected by enzyme-linked immunosorbent assay （ELISA）. Twenty-eight days after surgery, cardiac function of the remaining mice was measured by small animal ultrasound. Then the animals were sacrificed. Hematoxylin and eosin （HE） staining and immunohistoehemical staining of cardiac paraffin section were used to observe the inflammation and detect the expression of CXCL16 in cardiac tissue after myocardial infarction. To explore the function of CXCL16 in vitro, primary murine monocytes were separated from bone marrow, cultured to differentiate into macrophages and transfected with adenovirus vectors over-expressing CXCL16 or control adenovirus vectors. After stimulation by debris of cardiac cells, the phagocytic uptake by maerophages was evaluated by flow eytometry. Results The model of myocardialinfarction was successfully established. ELISA showed that the serum level of CXCL16 was elevated 3 days after myocardial infarction [（1 079 ± 176） vs （611 ± 37） pg/ml, P = 0. 0321. HE and immunohistochemical staining demonstrated that the infiltration of macrophages increased during an early stage of myocardial infarction and decreased at the late stage. The CXCL16 level was up-regulated 3 days after myocardial infarction and returned to normal level at Day 28. Furthermore, macrophages transfected with adenovirus over-expressing CXCL16 showed stronger phagocytic activity compared with control （17. 11% ± 0. 87% vs 7.91%± 0. 71%, P 〈 0. 01 ）. Conclusion CXCL16 is up-regulated after myocardial infarction in mice. And an in vitro over-expression of CXCL16 promotes the macrophage phagocytosis of cardiac debris.