CpG oligodeoxynucleotide preconditioning improves cardiac function after myocardial infarction via modulation of energy metabolism and angiogenesis

Abstract

Unmethylated CpG oligodeoxynucleotide (CpG-ODN), a Toll-like receptor 9 (TLR9) ligand, has been shown to protect against myocardial ischemia/reperfusion injury. However, the potential effects of CpG-ODN on myocardial infarction (MI) induced by persistent ischemia remains unclear. Here, we investigated whether and how CpG-ODN preconditioning protects against MI in mice. C57BL/6 mice were treated with CpG-ODN by i.p. injection 2 hr prior to MI induction, and cardiac function, and histology were analyzed 2 weeks after MI. Both 1826-CpG and KSK-CpG preconditioning significantly improved the left ventricular (LV) ejection fraction (LVEF) and LV fractional shortening (LVFS) when compared with non-CpG controls. Histological analysis further confirmed the cardioprotection of CpG-ODN preconditioning. In vitro studies further demonstrated that CpG-ODN preconditioning increases cardiomyocyte survival under hypoxic/ischemic conditions by enhancing stress tolerance through TLR9-mediated inhibition of the SERCA2/ATP and activation of AMPK pathways. Moreover, CpG-ODN preconditioning significantly increased angiogenesis in the infarcted myocardium compared with non-CpG. However, persistent TLR9 activation mediated by lentiviral infection failed to improve cardiac function after MI. Although CpG-ODN preconditioning increased angiogenesis in vitro, both the persistent stimulation of CpG-ODN and stable overexpression of TLR9 suppressed the tube formation of cardiac microvascular endothelial cells. CpG-ODN preconditioning significantly protects cardiac function against MI by suppressing the energy metabolism of cardiomyocytes and promoting angiogenesis. Our data also indicate that CpG-ODN preconditioning may be useful in MI therapy.

Synthetic CpG oligonucleotides induce a genetic profile ameliorating murine myocardial I/R injury

“…The activation of angiogenesis represents another requisite aspect of restoration initiated after myocardial ischaemic injury. Increasing angiogenesis in infracted tissue was demonstrated to occur after pre‐conditioning using CpG ODNs, restoring myocardial function after I/R in a very recent study by Zhou et al . In line with this, our study identified a set of genes with specific implications for the fostering of angiogenesis to be significantly up‐regulated in TLR9‐pretreated mice.…”

“…Increasing angiogenesis in infracted tissue was demonstrated to occur after pre-conditioning using CpG ODNs, restoring myocardial function after I/R in a very recent study by Zhou et al 47 In line with this, our study identified a set of genes with specific implications for the fostering of angiogenesis to be significantly up-regulated in TLR9-pretreated mice. Among the leading up-regulated genes we discovered were S100A9, S100A8, ARG1, CFB and CCL2, all of which have been demonstrated to exert specific positive influences on cardiovascular angiogenesis.…”

TLR9 is essential for HMGB1-mediated post-myocardial infarction tissue repair through affecting apoptosis, cardiac healing, and angiogenesis

“…The deficiency of TLR9 led to a decreased survival rate and increased mortality due to acute cardiac rupture, which was expressed as fewer myofibroblast formation and reductions of collagen I in the peri-infarct area, moreover, the thinner wall thickness and less fibrotic area. Prior studies and our results have documented the cardiovascular-protection of TLR9 ligand ODN 1826 in experimental MI 14 , we illustrated that the positive role of TLR9 ligand in wound healing. Therefore, the early activation of smad3 by TLR9 leads to the reparative fibrotic response in vivo, which resulted in normal accumulation of myofibroblast in the infarct area and synthesis and maturation of the extracellular matrix.…”

“…Also, the presence of immune cells, like macrophages and neutrophils leads to the release of cytokines that are capable of stimulating fibroblast growth factor and VEGF expression and is sufficient to produce angiogenesis 34,35 . Interestingly, TLRs activation not only initiates innate and adaptive immune responses but also regulates angiogenesis after binding to exogenous and endogenous ligands 8,14,36 . Our study showed that hypoxia induced the expression of VEGFA, and overexpression of VEGFA in WT mice promoted angiogenesis as demonstrated by an increase in capillary and arteriole densities.…”

“…TLR9 as an essential part of the innate immune system is expressed not only by multiple immune cells including monocytes, lymphocytes, etc., but by cardiomyocytes and cardiac fibroblast 13 . Although numerous studies have examined the effects of TLR9 ligands on MI 14,15 , the role of TLR9 deletion in ischemic cardiovascular disease has not been explored. Here, we performed an experimental MI on TLR9 knockout (TLR9KO) mice.…”