[Electroacupuncture ameliorates inflammatory response of mice with acute myocardial ischemia by regulating vascular endothelial growth factor C/vascular endothelial growth factor receptor 3 pathway]

Abstract

Objective: To observe the effect of electroacupuncture (EA) on the cardiac function, lymphatic markers, macrophage and inflammatory cytokines in acute myocardial ischemia (AMI) mice, so as to explore its mechanism in improving AMI.

Methods: Male C57BL/6 mice were randomly divided into sham operation, model, EA, inhibitor and inhibitor+EA groups, with 10 mice in each group. AMI model was established by occlusion of left anterior descending coronary artery. For mice in the EA group and inhibitor+EA group, EA (1 mA, 2 Hz/15 Hz) was applied to bilateral "Shenmen"(HT7) and "Tongli"(HT5) for 30 min, once daily for consecutive 3 days. Mice in the inhibitor+EA group were given intraperitoneal injection of vascular endothelial growth factor receptor-3 (VEGFR-3) inhibitor SAR131675 30 min before the EA, while mice in the inhibitor group were given intraperitoneal injection of SAR131675 only. The electrocardiogram (ECG) of the neck-thoracic lead was recorded and analyzed by BL-420F biological function experiment system. Histopathologic changes of myocardial tissue were observed after H.E. staining. The contents of lactate dehydrogenase (LDH), cardiac troponin I (cTnI) in serum and interleukin-18 (IL-18) and interleukin-6 (IL-6) in ischemic myocardium were determined by ELISA. The expressions of hyaluronic acid receptor-1 (LYVE-1) and macrophage mar-ker CD68 (CD68) in the myocardial tissue were detected by immunofluorescence assay. The protein expression levels of vascular endothelial growth factor C (VEGF-C) and VEGFR-3 were detected by Western blot.

Results: Compared with the sham operation group, the ECG-ST level, the contents of serum LDH and cTnI, and the contents of IL-18 and IL-6 in the myocardial tissue were significantly increased (P<0.01), the expression of LYVE-1 and the protein expression levels of VEGF-C and VEGFR-3 in the myocardial tissue were significantly decreased (P<0.01), while the number of CD68 positive cells was significantly increased (P<0.01) in the model group. Compared with the model, inhibitor and inhibitor+EA groups, the ECG-ST level, the contents of serum LDH and cTnI, and the contents of IL-18 and IL-6 in the myocardial tissue were decreased (P<0.01), the expression of LYVE-1 and the expression level of VEGFR-3 protein were increased (P<0.01), while the number of CD68 positive cells was significantly decreased (P<0.01) in the EA group. Compared with the model and inhibitor groups, the expression level of VEGF-C was increased (P<0.01) in the EA group. Outcomes of H.E. staining showed that the myocardial fibers were disordered with a large number of inflammatory cell infiltration in the model group, which was milder in the EA group.

Conclusion: Acupuncture can improve the inflammatory injury of AMI mice, which may be related to activate VEGF-C/VEGFR-3 pathway to promote lymphangiogenesis, reduce macrophage infiltration and inflammatory factors.

Keywords: Acute myocardial ischemia; Electroacupuncture; Heart meridian; Inflammatory response; Lymphangiogenesis; Vascular endothelial growth factor C/vascular endothelial growth factor receptor 3 pathway.