[Show abstract][Hide abstract] ABSTRACT: Humanin (HN) is an endogenous mitochondrial-derived cytoprotective peptide that has shown protective effects against atherosclerosis and is expressed in human vessels. However, its effects on the progression of kidney disease are unknown. We hypothesized that HN would protect the kidney in the early phase of atherogenesis.
Forty-eight mice were studied in four groups (n=12 each). Twenty-four ApoE deficient mice were fed a 16-week high-cholesterol diet supplemented with saline or HN (4mg/kg/day, intraperitoneal). C57BL/6 mice were fed a normal diet supplemented with saline or HN. Microvascular architecture was assessed with micro-CT and vascular wall remodeling by alpha-SMA staining. The effects of HN on angiogenesis, inflammation, apoptosis and fibrosis were evaluated in the kidney tissue by Western blotting and histology.
Cortical microvascular spatial density and media/lumen area ratio were significantly increased in high-cholesterol diet fed ApoE deficient mice, but restored by HN. HN up-regulated the renal expressions of anti-angiogenic proteins angiostatin and TSP-1, and inhibited angiopoietin-1. HN attenuated inflammation by down-regulating MCP-1, TNF-alpha and osteopontin. HN also tended to restore pSTAT3 and attenuated Bax expression, suggesting blunted apoptosis. Kidney collagen IV expression was alleviated by HN treatment.
HN attenuates renal microvascular remodeling, inflammation and apoptosis in the early stage of kidney disease in hypercholesterolemic ApoE(-/-) mice. HN may serve as a novel therapeutic target to mitigate kidney damage in early atherosclerosis.
[Show abstract][Hide abstract] ABSTRACT: The mechanism of atherosclerotic plaque progression leading to instability, rupture, and ischemic manifestation involves oxidative stress and apoptosis. Humanin (HN) is a newly emerging endogenously expressed cytoprotective peptide. Our goal was to determine the presence and localization of HN in carotid atherosclerotic plaques.
Plaque specimens from 34 patients undergoing carotid endarterectomy were classified according to symptomatic history. Immunostaining combined with digital microscopy revealed greater expression of HN in the unstable plaques of symptomatic compared to asymptomatic patients (29.42±2.05 vs. 14.14±2.13% of plaque area, p<0.0001). These data were further confirmed by immunoblot (density of HN/β-actin standard symptomatic vs. asymptomatic 1.32±0.14 vs. 0.79±0.11, p<0.01). TUNEL staining revealed a higher proportion of apoptotic nuclei in the plaques of symptomatic patients compared to asymptomatic (68.25±3.61 vs. 33.46±4.46% of nuclei, p<0.01). Double immunofluorescence labeling revealed co-localization of HN with macrophages (both M1 and M2 polarization), smooth muscle cells, fibroblasts, and dendritic cells as well as with inflammatory markers MMP2 and MMP9.
The study demonstrates a higher expression of HN in unstable carotid plaques that is localized to multiple cell types within the plaque. These data support the involvement of HN in atherosclerosis, possibly as an endogenous response to the inflammatory and apoptotic processes within the atheromatous plaque.
[Show abstract][Hide abstract] ABSTRACT: Humanin (HN) is a cytoprotective peptide derived from endogenous mitochondria, expressed in the endothelial layer of human vessels, but its role in atherogenesis in vivo is not known. In vitro study, however, HN reduced oxidized low-density lipoprotein induced formation of reactive oxygen species and apoptosis. The present study tested the hypothesis that long term treatment with HN will have a protective role against endothelial dysfunction and progression of atherosclerosis in vivo.
Daily intraperitonial injection of the HN analogue HNGF6A for 16 weeks prevented endothelial dysfunction and decreased atherosclerotic plaque size in the proximal aorta of ApoE-deficient mice fed on a high cholesterol diet, without showing direct vasoactive effects or cholesterol-reducing effects. HN was expressed in the endothelial layer on the aortic plaques. HNGF6A treatment reduced apoptosis and nitrotyrosine immunoreactivity in the aortic plaques without affecting the systemic cytokine profile. HNGF6A also preserved expression of endothelial nitric oxide synthase in aorta.
HN may have a protective effect on endothelial function and progression of atherosclerosis by modulating oxidative stress and apoptosis in the developing plaque.
[Show abstract][Hide abstract] ABSTRACT: Humanin (HN) is a 24-amino acid peptide that has been shown to have an anti-apoptotic function against neuronal cell death caused by Alzheimer's disease. Increased oxidative stress, one of the major factors contributing to this cell death, also plays an important role in the inflammatory process of atherosclerosis. The current study was designed to test the hypothesis that HN is expressed in the human vascular wall and may protect against oxidative stress.
HN expression in the vascular wall was detected by immunostaining in the endothelial cell layer of human internal mammary arteries (n = 5), atherosclerotic coronary arteries (n = 17), and sections of the greater saphenous vein (n = 3). HN mRNA was expressed in the human aortic endothelial cells (HAECs). Cytoprotective effects of HN against oxidative stress were tested in vitro in HAECs. Pre-treatment with 0.1 µM HN reduced oxidized LDL (Ox-LDL)-induced (i) formation of reactive oxygen species by 50%, (ii) apoptosis by ∼50% as determined by TUNEL staining, and (iii) formation of ceramide, a lipid second messenger involved in the apoptosis signalling cascade, by ∼20%.
The current study demonstrates for the first time the expression of HN in the endothelial cell layer of human blood vessels. Exogenous addition of HN to endothelial cell cultures was shown to be effective against Ox-LDL-induced apoptosis. These findings suggest that HN may play a role and may have a protective effect in early atherosclerosis in humans.
Full-text · Article · Nov 2010 · Cardiovascular Research