Microglia are tissue-resident macrophages of the central nervous system (CNS). In the CNS, microglia play an important role in the monitoring and intervention of synaptic and neuron-level activities. Interventions targeting microglia have been shown to improve the prognosis of various neurological diseases. Recently, studies have observed the activation of microglia in different cardiovascular diseases. In addition, different approaches that regulate the activity of microglia have been shown to modulate the incidence and progression of cardiovascular diseases. The change in autonomic nervous system activity after neuroinflammation may be a potential intermediate link between microglia and cardiovascular diseases. Here, in this review, we will discuss recent updates on the regulatory role of microglia in hypertension, myocardial infarction and ischemia/reperfusion injury. We propose that microglia serve as neuroimmune modulators and potential targets for cardiovascular diseases.

Background—: Vagus nerve stimulation attenuates left ventricular (LV) remodeling after myocardial infarction (MI). Our previous study found a noninvasive approach to deliver vagus nerve stimulation by transcutaneous electric stimulation of auricular branch of vagus nerve. So we hypothesize that chronic intermittent low-level tragus stimulation (LL-TS) could attenuate LV remodeling in conscious dogs with healed MI. Methods and Results—: Thirty beagle dogs were randomly divided into 3 groups, MI group (left anterior descending artery and major diagonal branches ligation to introduce MI, n=10), LL-TS group (MI plus chronic intermittent LL-TS, n=10), and control group (sham surgery without stimulation, n=10). Tragus stimulation was delivered to bilateral tragus with ear-clips connected to a custom-made stimulator. The voltage slowing sinus rate was used as the threshold for setting LL-TS at 80% below that. LL-TS group was given 4 hours stimulation at 7–9 am and 4–6 pm on conscious dogs. At the end of 90-day follow-up, LL-TS group significantly reduced LA and LV dilatation, improved LV contractile and diastolic function, reduced infarct size by ≈50% compared with MI group. LL-TS treatment alleviated cardiac fibrosis and significantly decreased protein expression level of collagen I, collagen III, transforming growth factor β1, and matrix metallopeptidase 9 in LV tissues. The plasma level of high-specific C-reactive protein, norepinephrine, N-terminal pro-B-type-natriuretic peptide in LL-TS group was significantly lower than those in MI group from the 7th day to the end of follow-up. Conclusions—: Chronic intermittent low-level transcutaneous electric stimulation of auricular branch of vagus nerve can attenuate LV remodeling in conscious dogs with healed MI.