Ischemic postconditioning attenuates the inflammatory response in ischemia/reperfusion myocardium by upregulating miR‑499 and inhibiting TLR2 activation

Abstract

Toll-like receptor 2 (Tlr2)-mediated myocardial inflammation serves an important role in promoting myocardial ischemic/reperfusion (I/R) injury. Previous studies have shown that miR-499 is critical for cardioprotection after ischemic postconditioning (IPostC). Therefore, the present study evaluated the protective effect of IPostC on the myocardium by inhibiting TLR2, and also assessed the involvement of microRNA (miR)-499. Rat hearts were subjected to 30 min of ischemia and 2 h of reperfusion. The IPostC was 3 cycles of 30 sec of reperfusion and 30 sec of re-occlusion prior to reperfusion. In total, 90 rats were randomly divided into six groups (n=15 per group): Sham; I/R; IPostC; miR-499 negative control adeno-associated virus (AAV) vectors + IPostC; miR-499 inhibitor AAV vectors + IPostC; and miR-499 mimic AAV vectors + IPostC. It was identified that IPostC significantly decreased the I/R-induced cardiomyocyte apoptotic index (29.4±2.03% in IPostC vs. 42.64±2.27% in I/R; P<0.05) and myocardial infarct size (48.53±2.49% in IPostC vs. 66.52±3.1% in I/R; P<0.05). Moreover, these beneficial effects were accompanied by increased miR-499 expression levels (as demonstrated by reverse transcription-quantitative PCR) in the myocardial tissue and decreased TLR2, protein kinase C (PKC), interleukin (IL)-1β and IL-6 expression levels (as demonstrated by western blotting and ELISA) in the myocardium and serum. The results indicated that IPostC + miR-499 mimics significantly inhibited inflammation and the PKC signaling pathway and enhanced the anti-inflammatory and anti-apoptotic effects of IPostC. However, IPostC + miR-499 inhibitors had the opposite effect. Therefore, it was speculated that IPostC may have a miR-499-dependent cardioprotective effect. The present results suggested that miR-499 may be involved in IPostC-mediated ischemic cardioprotection, which may occur via local and systemic TLR2 inhibition, subsequent inhibition of the PKC signaling pathway and a decrease in inflammatory cytokine release, including IL-1β and IL-6. Moreover, these effects will ultimately lead to a decrease in the myocardial apoptotic index and myocardial infarct size via the induction of the anti-apoptotic protein Bcl-2, and inhibition of the pro-apoptotic protein Bax in myocardium.

PPARβ/δ Is Required for Mesenchymal Stem Cell Cardioprotective Effects Independently of Their Anti-inflammatory Properties in Myocardial Ischemia-Reperfusion Injury

“…Considering the results presented in Figure 3C , we observed decreased amounts of cytokines (CXCL1 and IL-6) in the PostC condition vs. IR, whereas Maruyama et al have reported similar values of coronary flow values at 60 min of reperfusion in both IR and PostC conditions ( 55 ). On the basis of these results, we can therefore suggest that the decrease in cytokine levels at IR60 observed after a PostC (see Figure 3C ) may result mainly from a decrease in the release of cytokines vs. IR, in accordance with the anti-inflammatory effect of PostC described in vivo ( 10 , 56 ). However, we cannot exclude an improvement in the coronary flow upon PostC, as described for many other cardioprotective strategies evaluated in our laboratory ( 53 , 54 ) or others ( 57 ), which could also contribute to the reduction in measured amounts of cytokines.…”

H3K14 hyperacetylation‑mediated c‑Myc binding to the miR‑30a‑5p gene promoter under hypoxia postconditioning protects senescent cardiomyocytes from hypoxia/reoxygenation injury

“…Among which, autophagy has also been found to be involved in i/r (4). Studies have reported that ischemic postconditioning (iPostc) can protect the heart from i/r injury by transient intermittent i/r episodes prior to long-term ischemia or hypoxia reperfusion (5). Wei et al (6) found that iPostc could improve autonomic function in acute ischemic stroke patients through the enhancement of the total autonomic nerve activity and vagus nerve activity.…”

“…Wei et al (6) found that iPostc could improve autonomic function in acute ischemic stroke patients through the enhancement of the total autonomic nerve activity and vagus nerve activity. another study also found that iPostc attenuates the injury in i/r myocardium by upregulating microrna (mirna/mir)-499 and inhibiting Toll-like receptor 2 activation (5). mir-30a-5p, a member of the mir-30 family, is regarded as a key mirna in cardiovascular pathophysiology (7).…”

Exploring the mechanism of Yixinyin for myocardial infarction by weighted co-expression network and molecular docking

“…This protection may be achieved by the inhibition of TLR2 and the reduction of inflammatory cytokine release (including IL-1β and IL-6). These effects eventually lead to a dropping in the area of MI 26 . Therefore, regulating TLR2 signal may provide a new treatment strategy for heart failure.…”