Ghrelin Promotes Functional Angiogenesis in a Mouse Model of Critical Limb Ischemia Through Activation of Proangiogenic MicroRNAs

Abstract

Current therapeutic strategies for the treatment of critical limb ischemia (CLI) have only limited success. Recent in vitro evidence in the literature, using cell lines, proposes that the peptide hormone ghrelin may have angiogenic properties. In this study, we aim to investigate if ghrelin could promote postischemic angiogenesis in a mouse model of CLI and, further, identify the mechanistic pathway(s) that underpin ghrelin's proangiogenic properties. CLI was induced in male CD1 mice by femoral artery ligation. Animals were then randomized to receive either vehicle or acylated ghrelin (150 μg/kg sc) for 14 consecutive days. Subsequently, synchrotron radiation microangiography was used to assess hindlimb perfusion. Subsequent tissue samples were collected for molecular and histological analysis. Ghrelin treatment markedly improved limb perfusion by promoting the generation of new capillaries and arterioles (internal diameter less than 50 μm) within the ischemic hindlimb that were both structurally and functionally normal; evident by robust endothelium-dependent vasodilatory responses to acetylcholine. Molecular analysis revealed that ghrelin's angiogenic properties were linked to activation of prosurvival Akt/vascular endothelial growth factor/Bcl-2 signaling cascade, thus reducing the apoptotic cell death and subsequent fibrosis. Further, ghrelin treatment activated proangiogenic (miR-126 and miR-132) and antifibrotic (miR-30a) microRNAs (miRs) while inhibiting antiangiogenic (miR-92a and miR-206) miRs. Importantly, in vitro knockdown of key proangiogenic miRs (miR-126 and miR-132) inhibited the angiogenic potential of ghrelin. These results therefore suggest that clinical use of ghrelin for the early treatment of CLI may be a promising and potent inducer of reparative vascularization through modulation of key molecular factors.

Ghrelin Preserves Ischemia-Induced Vasodilation of Male Rat Coronary Vessels Following β-Adrenergic Receptor Blockade

“…Ever since its discovery in 1999 (17), ghrelin has emerged as an important therapeutic modulator of cardiac function in health and disease (18). Whereas the exact mechanisms that underpin the cardioprotective properties of ghrelin remain to be fully elucidated, various groups have shown that ghrelin prevents MI-induced sympathetic activation (6,7,19,20), inhibits myocardial apoptosis (21), promotes angiogenesis (22,23), reduces cardiac cachexia and dysfunction (24), preserves cardiac contractility (25), and attenuates cardiac remodeling (26). Although ghrelin is known to modulate coronary vasculature tone directly, at least in animal models, the few reports, to date, do not agree as to whether ghrelin dilates or constricts coronary vessels (10)(11)(12)(13).…”

An Emerging Role for isomiRs and the microRNA Epitranscriptome in Neovascularization

“…Both miR-126-3p and -5p are also highly expressed in ECs where they promote angiogenesis by stimulating EC proliferation and VEGF signaling and regulating leukocyte adhesion [46][47][48][49]. Inhibition of miR-126-3p was shown to decrease recovery after myocardial infarction and hindlimb ischemia in mice [47,50,51]. Furthermore, miR-126 levels are decreased in patients with ischemic coronary artery disease [52].…”

IMPORTANCE OF THE LEPTIN/GRELIN RATIO AS A BIOMARKER IN DIETARY INDUCED HYPERLIPIDEMIA IN FEMALE C57Black/6 MICE

“…Взаимосвязь между изменениями L/Gh и массой органов и тканей может быть обусловлена участием лептина и грелина в регуляции ангиогенеза и формировании фиброзных изменений, которые наблюдаются при ожирении и метаболическом синдроме. Причем была показана как проангиогенная, так и антифибротическая роль грелина in vivo и in vitro за счет активации Bcl-2 (белок семейства регуляторов апоптоза) сигнального пути и редукции апоптоза [17]. На этом фоне системное введение грелина мышам, получающим обогащенный жирами рацион, способствовало увеличению сывороточного VEGF (фактор роста эндотелия) и снижению сывороточных концентраций лептина и NO (окись азота II) [19].…”