Electroacupuncture improves myocardial ischemia inflammatory injury by regulating the homeostasis of myocardial Th17/Treg cells through JAK1/STAT3 signaling in rats

To observe the effect of electroacupuncture (EA) on the homeostasis of Th17/Treg cells and the expressions of key proteins of the janus kinase 1/signal transducer and activator of transcription 3 signaling pathway in myocardial tissue of rats with myocardial ischemia(MI), so as to explore its mechanisms underlying amelioration of inflammatory injury following MI.

SD rats were randomly divided into control, model, and EA groups, with 6 rats in each group. The MI model was established by subcutaneous injection of isoproterenol hydrochloride (5 mg∙kg^-1∙d^-1), once daily for 7 consecutive days. After successful modeling, the rats of EA group received EA stimulation (2 Hz/10 Hz, 2 to 3 mA) of unilateral “Neiguan” (PC6) and “Zusanli” (ST36) for 20 min, once daily for 21 d. The standard limb lead Ⅱ electrocardiogram (ECG) was recorded to analyze the height of ST and amplitude of T wave for assessing the degree of ischemic myocardial injury. The hematoxylin-eosin (H.E.) staining was used to observe histopathological changes in the myocardial tissue, and the Masson staining performed to examine the collagen deposition of the myocardial cells. The concentrations of tumor necrosis factor-alpha (TNF-α), interleukin (IL)-17, and IL-10 in the serum and myocardial tissue were detected using enzyme-linked immunosorbent assays (ELISA), and the proportions of Th17 cells and Treg cells in the myocardial tissue analyzed using flow cytometry. The expression levels of signal transducers and activators of transcription 3 (STAT3), phosphorylated (p)- STAT3, forkhead box protein 3 (Foxp3), Janus kinase 1 (JAK1), retinoic acid-related orphan nuclear receptor-α(RORα), suppressor of cytokine signaling 3 (SOCS3) proteins in the myocardial tissue were detected using Western blot.

Compared with the control group, the model group had a significant increase in the ST height and T-wave amplitude, myocardial collagen volume fraction (CVF), TNF-α and IL-17 contents in the serum and myocardial tissue, myocardial Th17/Treg ratio, and expression levels of myocardial JAK1, STAT3, p-STAT3, and RORα proteins (P<0.01, P<0.05), and a striking decrease in the proportion of Treg cells, contents of myocardial and serum IL-10, and expression levels of myocardial FOXP3 and SOCS3 (P<0.01, P<0.05). In contrast to the model group, both the increase and the decrease of the indexes mentioned above were reversed in the EA group (P<0.05, P<0.01). H.E. staining showed necrosis and dissolution of a large number of myocardial cells, with increased cell spacing and blurred boundaries, inflammatory infiltration and fibrous tissue hyperplasia in the model group, which was relatively and significantly milder in the degree of myocardial injury in the EA group.

EA at PC6 and ST36 can improve myocardial inflammation injury in rats with MI, which may be related to its function in regulating the homeostasis of Th17/Treg cells in myocardial tissue through JAK1/STAT3 signaling, balancing the secretion of pro-inflammatory factors TNF-α, IL-17 and anti-inflammatory factor IL-10.