Type-2 diabetes-induced changes in vascular extracellular matrix gene expression: Relation to vessel size

BACKGROUND: Hyperglycemia-induced changes in vascular wall structure contribute to the pathogenesis of diabetic microvascular and macrovascular complications. Matrix metalloproteinases (MMP), a family of proteolytic enzymes that degrade extracellular matrix (ECM) proteins, are essential for vascular remodeling. We have shown that endothelin-1 (ET-1) mediates increased MMP activity and associated vascular remodeling in Type 2 diabetes. However, the effect of Type 2 diabetes and/or ET-1 on the regulation of ECM and MMP gene expression in different vascular beds remains unknown. METHODS: Aorta and mesenteric artery samples were isolated from control, Type 2 diabetic Goto-Kakizaki (GK) rats and GK rats treated with ET(A )antagonist ABT-627. Gene expression profile of MMP-2, MMP-9, MT1-MMP, fibronectin, procollagen type 1, c-fos and c-jun, were determined by quantitative real-time (qRT) PCR. In addition, aortic gene expression profile was evaluated by an ECM & Adhesion Molecules pathway specific microarray approach. RESULTS: Analysis of the qRT-PCR data demonstrated a significant increase in mRNA levels of MMPs and ECM proteins as compared to control animals after 6 weeks of mild diabetes. Futhermore, these changes were comparable in aorta and mesentery samples. In contrast, treatment with ET(A )antagonist prevented diabetes-induced changes in expression of MMPs and procollagen type 1 in mesenteric arteries but not in aorta. Microaarray analysis provided evidence that 27 extracellular matrix genes were differentially regulated in diabetes. Further qRT-PCR with selected 7 genes confirmed the microarray data. CONCLUSION: These results suggest that the expression of both matrix scaffold protein and matrix degrading MMP genes are altered in macro and microvascular beds in Type 2 diabetes. ET(A )antagonism restores the changes in gene expression in the mesenteric bed but not in aorta suggesting that ET-1 differentially regulates microvascular gene expression in Type 2 diabetes

Oxidative stress and the use of antioxidants in diabetes: Linking basic science to clinical practice

Cardiovascular complications, characterized by endothelial dysfunction and accelerated atherosclerosis, are the leading cause of morbidity and mortality associated with diabetes. There is growing evidence that excess generation of highly reactive free radicals, largely due to hyperglycemia, causes oxidative stress, which further exacerbates the development and progression of diabetes and its complications. Overproduction and/or insufficient removal of these free radicals result in vascular dysfunction, damage to cellular proteins, membrane lipids and nucleic acids. Despite overwhelming evidence on the damaging consequences of oxidative stress and its role in experimental diabetes, large scale clinical trials with classic antioxidants failed to demonstrate any benefit for diabetic patients. As our understanding of the mechanisms of free radical generation evolves, it is becoming clear that rather than merely scavenging reactive radicals, a more comprehensive approach aimed at preventing the generation of these reactive species as well as scavenging may prove more beneficial. Therefore, new strategies with classic as well as new antioxidants should be implemented in the treatment of diabetes

Delayed minocycline inhibits ischemia-activated matrix metalloproteinases 2 and 9 after experimental stroke

BACKGROUND: Matrix metalloproteinases 2 and 9 (MMP-2 and MMP-9) are increased in the brain after experimental ischemic stroke in rats. These two proteases are involved with the degradation of the basal lamina and loss of stability of the blood brain barrier that occurs after ischemia and that is associated with thrombolytic therapy in ischemic stroke. Minocycline is a lipophilic tetracycline and is neuroprotective in several models of brain injury. Minocycline inhibits inflammation, apoptosis and extracellular matrix degradation. In this study we investigated whether delayed minocycline inhibits brain MMPs activated by ischemia in a model of temporary occlusion in Wistar rats. RESULTS: Both MMP-2 and MMP-9 were elevated in the ischemic tissue as compared to the contra-lateral hemisphere after 3 hours occlusion and 21 hours survival (p < 0.0001 for MMP-9). Intraperitoneal minocycline at 45 mg/kg concentration twice a day (first dose immediately after the onset of reperfusion) significantly reduced gelatinolytic activity of ischemia-elevated MMP-2 and MMP-9 (p < 0.0003). Treatment also reduced protein concentration of both enzymes (p < 0.038 for MMP-9 and p < 0.018 for MMP-2). In vitro incubation of minocycline in concentrations as low as 0.1 μg/ml with recombinant MMP-2 and MMP-9 impaired enzymatic activity and MMP-9 was more sensitive at lower minocycline concentrations (p < 0.05). CONCLUSION: Minocycline inhibits enzymatic activity of gelatin proteases activated by ischemia after experimental stroke and is likely to be selective for MMP-9 at low doses. Minocycline is a potential new therapeutic agent to acute treatment of ischemic stroke

Effect of neutrophil depletion on gelatinase expression, edema formation and hemorrhagic transformation after focal ischemic stroke

BACKGROUND: While gelatinase (MMP-2 and -9) activity is increased after focal ischemia/reperfusion injury in the brain, the relative contribution of neutrophils to the MMP activity and to the development of hemorrhagic transformation remains unknown. RESULTS: Anti-PMN treatment caused successful depletion of neutrophils in treated animals. There was no difference in either infarct volume or hemorrhage between control and PMN depleted animals. While there were significant increases in gelatinase (MMP-2 and MMP-9) expression and activity and edema formation associated with ischemia, neutrophil depletion failed to cause any change. CONCLUSION: The main finding of this study is that, in the absence of circulating neutrophils, MMP-2 and MMP-9 expression and activity are still up-regulated following focal cerebral ischemia. Additionally, neutrophil depletion had no influence on indicators of ischemic brain damage including edema, hemorrhage, and infarct size. These findings indicate that, at least acutely, neutrophils are not a significant contributor of gelatinase activity associated with acute neurovascular damage after stroke

25 years of endothelin research: the next generation

In the past three decades, endothelin and endothelin receptor antagonists have received great scientific and clinical interest, leading to the publication of more than 27,000 scientific articles since its discovery. The Thirteenth International Conference on Endothelin (ET-13) was held on September 8–11, 2013, at Tokyo Campus of the University of Tsukuba in Japan. Close to 300 scientists from 25 countries from around the world came to Tokyo to celebrate the anniversary of the discovery of the endothelin peptide discovered 25 years ago at the University of Tsukuba. This article summarizes some of the highlights of the conference, the anniversary celebration ceremony, and particularly the participation of next generation of endothelin researchers in endothelin science and the anniversary celebration. As a particular highlight, next generation endothelin researchers wrote a haiku (a traditional form of Japanese poetry originating from consisting of no more than three short verses and 27 on, or Japanese phonetic units) to describe the magic of endothelin science which they presented to the conference audience at the anniversary ceremony. The text of each haiku – both in its original language together with the English translation – is part of this article providing in an exemplary fashion how poetry can be bridged with science. Finally, we give an outlook towards the next 25 years of endothelin research

Reduced endothelium-dependent relaxation to anandamide in mesenteric arteries from young obese Zucker rats

Impaired vascular function, manifested by an altered ability of the endothelium to release endothelium-derived relaxing factors and endothelium-derived contracting factors, is consistently reported in obesity. Considering that the endothelium plays a major role in the relaxant response to the cannabinoid agonist anandamide, the present study tested the hypothesis that vascular relaxation to anandamide is decreased in obese rats. Mechanisms contributing to decreased anandamide-induced vasodilation were determined. Resistance mesenteric arteries from young obese Zucker rats (OZRs) and their lean counterparts (LZRs) were used. Vascular reactivity was evaluated in a myograph for isometric tension recording. Protein expression and localization were analyzed by Western blotting and immunofluorescence, respectively. Vasorelaxation to anandamide, acetylcholine, and sodium nitroprusside, as well as to CB1, CB2, and TRPV1 agonists was decreased in endothelium-intact mesenteric arteries from OZRs. Incubation with an AMP-dependent protein kinase (AMPK) activator or a fatty acid amide hydrolase inhibitor restored anandamide-induced vascular relaxation in OZRs. CB1 and CB2 receptors protein expression was decreased in arteries from OZRs. Incubation of mesenteric arteries with anandamide evoked endothelial nitric oxide synthase (eNOS), AMPK and acetyl CoA carboxylase phosphorylation in LZRs, whereas it decreased phosphorylation of these proteins in OZRs. In conclusion, obesity decreases anandamide-induced relaxation in resistance arteries. Decreased cannabinoid receptors expression, increased anandamide degradation, decreased AMPK/eNOS activity as well as impairment of the response mediated by TRPV1 activation seem to contribute to reduce responses to cannabinoid agonists in obesity.National Institutes of Health (HL71138, HL74167)Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP)INCT Obesity and DiabetesConselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq

Increased hemorrhagic transformation and altered infarct size and localization after experimental stroke in a rat model type 2 diabetes

<p>Abstract</p> <p>Background</p> <p>Interruption of flow through of cerebral blood vessels results in acute ischemic stroke. Subsequent breakdown of the blood brain barrier increases cerebral injury by the development of vasogenic edema and secondary hemorrhage known as hemorrhagic transformation (HT). Diabetes is a risk factor for stroke as well as poor outcome of stroke. The current study tested the hypothesis that diabetes-induced changes in the cerebral vasculature increase the risk of HT and augment ischemic injury.</p> <p>Methods</p> <p>Diabetic Goto-Kakizaki (GK) or control rats underwent 3 hours of middle cerebral artery occlusion and 21 h reperfusion followed by evaluation of infarct size, hemorrhage and neurological outcome.</p> <p>Results</p> <p>Infarct size was significantly smaller in GK rats (10 ± 2 vs 30 ± 4%, p < 0.001). There was significantly more frequent hematoma formation in the ischemic hemisphere in GK rats as opposed to controls. Cerebrovascular tortuosity index was increased in the GK model (1.13 ± 0.01 vs 1.34 ± 0.06, P < 0.001) indicative of changes in vessel architecture.</p> <p>Conclusion</p> <p>These findings provide evidence that there is cerebrovascular remodeling in diabetes. While diabetes-induced remodeling appears to prevent infarct expansion, these changes in blood vessels increase the risk for HT possibly exacerbating neurovascular damage due to cerebral ischemia/reperfusion in diabetes.</p

Molecular aspects of endothelin-1

Endothelin-1 (ET-1) is a 21-amino acid residue peptide with potent vasoconstricting and mitogenic properties. Three members of the ET family, ET-1, ET-2, and ET-3, have been cloned, and these peptides were found to have sequence homology and similar bioactivity to a peptide toxin family, sarafotoxins (STX). A comparison of the amino acid sequences of the ETs and STXs revealed that certain residues are highly conserved, suggesting that they might be important in post-translational modification, cellular transport, receptor binding, or receptor activation.To test these possibilities, the codons for Lys-9, Ile-20, and Trp-21 in the PPET-1 cDNA were replaced by ones that encode for Ala. Lys-9 was also replaced by Glu, and the mutant and wild-type PPET-1 cDNAs were transiently expressed in COS-7 cells. Levels of the expression of recombinant mutant ET-1s were measured by radioimmunoassay. Interestingly, immunoreactive ET-1 levels in the transfection medium obtained from cells transfected with (Ala-21-ET-1)PPET-1 cDNA were 10-fold lower that those of cells transfected with wild-type and other mutant cDNAs along with a corresponding increase in the big ET-1 levels in the extracts of (Ala-21-ET-1)PPET-1 cDNA-transfected cells.The receptor binding properties of the mutant peptides were studied on two cell lines, rat vascular smooth muscle cells A-10 and human Girardi heart cells that possess ET\sb{\rm A}- and ET\sb{\rm B}-class receptors, respectively. The contractile effects of these peptides were tested on canine coronary artery rings that are enriched in the ET\sb{\rm A} receptor subtype. The results of the binding and contractility experiments demonstrated that Lys-9, Ile-20, and Trp-21 are important for binding and activation of ET\sb{\rm A} receptors, whereas replacement of Lys-9 by either Ala or Glu does not have any appreciable effect on binding to the ET\sb{\rm B} receptor subtype. In addition, the (Glu-9)ET-1 mutant peptide blocked the contractile response mediated by 50 nM ET-1, indicating that it has inhibitory properties as well