Gene Deletion of the Kinin Receptor B1 Attenuates Cardiac Inflammation and Fibrosis During the Development of Experimental Diabetic Cardiomyopathy

Objective: Diabetic cardiomyopathy is associated with increased mortality in patients with diabetes mellitus. The underlying pathology of this disease is still under discussion. We studied the role of the kinin B1 receptor on the development of experimental diabetic cardiomyopathy. Research Design and Methods: We utilized B1 receptor knockout mice and investiged cardiac inflammation, fibrosis and oxidative stress after induction of streptozotocin (STZ)-induced diabetes mellitus. Furthermore, the left ventricular function was measured by pressure-volume loops after 8 weeks of diabetes mellitus. Results: B1 receptor knockout mice showed an attenuation of diabetic cardiomyopathy with improved systolic and diastolic function in comparison with diabetic control mice. This was associated with a decreased activation state of the MAP kinase p38, less oxidative stress as well as normalized cardiac inflammation, shown by fewer invading cells and, no increase in matrix metalloproteinase-9 as well as the chemokine CXCL-5. Furthermore, the pro-fibrotic connective tissue growth factor was normalized, leading to a reduction in cardiac fibrosis despite severe hyperglycemia in mice lacking the B1 receptor. Conclusion: These findings suggest that the B1 receptor is detrimental in diabetic cardiomyopathy in that it mediates inflammatory and fibrotic processes. These insights might have useful implications on future studies utilizing B1 receptor antagonists for treatment of human diabetic cardiomyopathy

Kinin B1 Receptor Enhances the Oxidative Stress in a Rat Model of Insulin Resistance: Outcome in Hypertension, Allodynia and Metabolic Complications

BACKGROUND: Kinin B(1) receptor (B(1)R) is induced by the oxidative stress in models of diabetes mellitus. This study aims at determining whether B(1)R activation could perpetuate the oxidative stress which leads to diabetic complications. METHODS AND FINDINGS: Young Sprague-Dawley rats were fed with 10% D-Glucose or tap water (controls) for 8-12 weeks. A selective B(1)R antagonist (SSR240612) was administered acutely (3-30 mg/kg) or daily for a period of 7 days (10 mg/kg) and the impact was measured on systolic blood pressure, allodynia, protein and/or mRNA B(1)R expression, aortic superoxide anion (O(2)(*-)) production and expression of superoxide dismutase (MnSOD) and catalase. SSR240612 reduced dose-dependently (3-30 mg/kg) high blood pressure in 12-week glucose-fed rats, but had no effect in controls. Eight-week glucose-fed rats exhibited insulin resistance (HOMA index), hypertension, tactile and cold allodynia and significant increases of plasma levels of glucose and insulin. This was associated with higher aortic levels of O(2)(*-), NADPH oxidase activity, MnSOD and catalase expression. All these abnormalities including B(1)R overexpression (spinal cord, aorta, liver and gastrocnemius muscle) were normalized by the prolonged treatment with SSR240612. The production of O(2)(*-) in the aorta of glucose-fed rats was also measured in the presence and absence of inhibitors (10-100 microM) of NADPH oxidase (apocynin), xanthine oxidase (allopurinol) or nitric oxide synthase (L-NAME) with and without Sar[D-Phe(8)]des-Arg(9)-BK (20 microM; B(1)R agonist). Data show that the greater aortic O(2)(*-) production induced by the B(1)R agonist was blocked only by apocynin. CONCLUSIONS: Activation of kinin B(1)R increased O(2)(*-) through the activation of NADPH oxidase in the vasculature. Prolonged blockade of B(1)R restored cardiovascular, sensory and metabolic abnormalities by reducing oxidative stress and B(1)R gene expression in this model

Detrimental implication of B-1 receptors in myocardial ischemia: evidence from pharmacological blockade and gene knockout mice

Objective: the aim of this study was to evaluate the contribution of kinin B-1 receptors in myocardial ischemia using both pharmacological blockade and gene knockout mice. Material and methods: Hearts (n=6-8 per group) from wild type or homozygous B-1 receptor gene knockout mice were isolated and perfused using the Langendorff technique. After a 30-min stabilisation period, the left coronary artery was occluded for 30 min followed by 60 min of reperfusion. in two separate groups of wild type hearts, B-1 and B-2 receptors were blocked with 3 nM of (des-Arg(9), Leu(8))-bradykinin and 10 nM of Hoe 140, respectively, (started 15 min before ischemia and stopped before the reperfusion). Results: Infarct size to risk zone (I/R) ratio was significantly reduced in hearts of knockout mice (11.3 +/- 2.1%) compared to those of wild type mice (25.7 +/- 1.7%). Furthermore, in wild type mice, I/R was significantly reduced in hearts perfused with the B-1 receptor antagonist (12.8 +/- 2.4%) but not in hearts perfused with the B-2 receptor antagonist (36.3 4.4%) compared to untreated hearts. Finally, a RTPCR technique showed an activation of kinin B-1 receptor gene transcription, in wild type hearts, subjected to the ischemia-reperfusion sequence. Conclusion: This study demonstrates that B-1 receptors are induced during myocardial ischemia where they could play a detrimental role in mice. (C) 2002 Published by Elsevier Science B.V.Univ Grenoble 1, Lab Stress Cardiovasc & Pathol Associees, F-38706 La Tronche, FranceMax Delbruck Ctr Mol Med, D-13092 Berlin, GermanyEscola Paulista Med, Dept Biophys, BR-04023062 São Paulo, BrazilEscola Paulista Med, Dept Biophys, BR-04023062 São Paulo, BrazilWeb of Scienc

Endocannabinoids as mediators in the heart: a potential target for therapy of remodelling after myocardial infarction?

Endocannabinoid production by platelets and macrophages is increased in circulatory shock. This may be protective of the cardiovascular system as blockade of CB(1) cannabinoid receptors exacerbates endothelial dysfunction in haemorrhagic and endotoxin shock and reduces survival. Now evidence suggests that blockade of CB(1) receptors starting 24 h after myocardial infarction in rats has a deleterious effect on cardiac performance, while use of a nonselective cannabinoid receptor agonist prevents hypotension and reduces endothelial dysfunction, although left ventricular end diastolic pressure is elevated. Cannabinoids and endocannabinoid systems may therefore present useful targets for therapy following myocardial infarction

Lack of both bradykinin B1 and B2 receptors enhances nephropathy, neuropathy, and bone mineral loss in Akita diabetic mice

An insertion polymorphism of the angiotensin-I converting enzyme gene (ACE) is common in humans and the higher expressing allele is associated with an increased risk of diabetic complications. The ACE polymorphism does not significantly affect blood pressure or angiotensin II levels, suggesting that the kallikrein-kinin system partly mediates the effects of the polymorphism. We have therefore explored the influence of lack of both bradykinin receptors (B1R and B2R) on diabetic nephropathy, neuropathy, and osteopathy in male mice heterozygous for the Akita diabetogenic mutation in the insulin 2 gene (Ins2). We find that all of the detrimental phenotypes observed in Akita diabetes are enhanced by lack of both B1R and B2R, including urinary albumin excretion, glomerulosclerosis, glomerular basement membrane thickening, mitochondrial DNA deletions, reduction of nerve conduction velocities and of heat sensation, and bone mineral loss. Absence of the bradykinin receptors also enhances the diabetes-associated increases in plasma thiobarbituric acid-reactive substances, mitochondrial DNA deletions, and renal expression of fibrogenic genes, including transforming growth factor beta1, connective tissue growth factor, and endothelin-1. Thus, lack of B1R and B2R exacerbates diabetic complications. The enhanced renal injury in diabetic mice caused by lack of B1R and B2R may be mediated by a combination of increases in oxidative stress, mitochondrial DNA damage and over expression of fibrogenic genes

Loss of Bradykinin Signaling Does Not Accelerate the Development of Cardiac Dysfunction in Type 1 Diabetic Akita Mice

Bradykinin signaling has been proposed to play either protective or deleterious roles in the development of cardiac dysfunction in response to various pathological stimuli. To further define the role of bradykinin signaling in the diabetic heart, we examined cardiac function in mice with genetic ablation of both bradykinin B1 and B2 receptors (B1RB2R−/−) in the context of the Akita model of insulin-deficient type 1 diabetes (Ins2Akita/+). In 5-month-old diabetic and nondiabetic, wild-type and B1RB2R−/− mice, in vivo cardiac contractile function was determined by left-ventricular (LV) catheterization and echocardiography. Reactive oxygen species levels were measured by 2′-7′-dichlorofluorescein diacetate fluorescence. Mitochondrial function and ATP synthesis were determined in saponin-permeabilized cardiac fibers. LV systolic pressure and the peak rate of LV pressure rise and decline were decreased with diabetes but did not deteriorate further with loss of bradykinin signaling. Wall thinning and reduced ejection fractions in Akita mouse hearts were partially attenuated by B1RB2R deficiency, although other parameters of LV function were unaffected. Loss of bradykinin signaling did not increase fibrosis in Ins2Akita/+ diabetic mouse hearts. Mitochondrial dysfunction was not exacerbated by B1RB2R deficiency, nor was there any additional increase in tissue levels of reactive oxygen species. Thus, loss of bradykinin B2 receptor signaling does not abrogate the previously reported beneficial effect of inhibition of B1 receptor signaling. In conclusion, complete loss of bradykinin expression does not worsen cardiac function or increase myocardial fibrosis in diabetes

Bradykinin receptor 1 activation exacerbates experimental focal and segmental glomerulosclerosis

Focal and segmental glomerulosclerosis (FSGS) is one of the most important causes of end-stage renal failure. the bradykinin B1 receptor has been associated with tissue inflammation and renal fibrosis. To test for a role of the bradykinin B1 receptor in podocyte injury, we pharmacologically modulated its activity at different time points in an adriamycin-induced mouse model of FSGS. Estimated albuminuria and urinary protein to creatinine ratios correlated with podocytopathy. Adriamycin injection led to loss of body weight, proteinuria, and upregulation of B1 receptor mRNA. Early treatment with a B1 antagonist reduced albuminuria and glomerulosclerosis, and inhibited the adriamycin-induced downregulation of podocin, nephrin, and alpha-actinin-4 expression. Moreover, delayed treatment with antagonist also induced podocyte protection. Conversely, a B1 agonist aggravated renal dysfunction and even further suppressed the levels of podocyte-related molecules. Thus, we propose that kinin has a crucial role in the pathogenesis of FSGS operating through bradykinin B1 receptor signaling. Kidney International (2011) 79, 1217-1227; doi:10.1038/ki.2011.14; published online 16 March 2011Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)INCT Complex FluidsUniv São Paulo, Inst Biomed Sci 4, Dept Immunol, Lab Imunobiol Transplante, BR-05508900 São Paulo, BrazilUniversidade Federal de São Paulo, Disciplina Nefrol, Dept Med, Lab Imunol Clin & Expt, BR-04023900 São Paulo, BrazilUniversidade Federal de São Paulo, Disciplina Nefrol, Dept Med, Mol Biol Lab, BR-04023900 São Paulo, BrazilUniversidade Federal de São Paulo, Dept Biofis, BR-04023900 São Paulo, BrazilUniversidade Federal de São Paulo, Dept Patol, BR-04023900 São Paulo, BrazilUniv Paris 07, INSERM, U699, Paris, FranceUniv São Paulo, Dept Patol, BR-05508900 São Paulo, BrazilHosp Israelita Albert Einstein, São Paulo, BrazilUniversidade Federal de São Paulo, Dept Microbiol Imunol & Parasitol, BR-04023900 São Paulo, BrazilUniversidade Federal de São Paulo, Disciplina Nefrol, Dept Med, Lab Imunol Clin & Expt, BR-04023900 São Paulo, BrazilUniversidade Federal de São Paulo, Disciplina Nefrol, Dept Med, Mol Biol Lab, BR-04023900 São Paulo, BrazilUniversidade Federal de São Paulo, Dept Biofis, BR-04023900 São Paulo, BrazilUniversidade Federal de São Paulo, Dept Patol, BR-04023900 São Paulo, BrazilUniversidade Federal de São Paulo, Dept Microbiol Imunol & Parasitol, BR-04023900 São Paulo, BrazilFAPESP: 04/08226-9FAPESP: 07/07139-3FAPESP: 2007/07120FAPESP: 08/55125-4CNPq: 501848/2009-6Web of Scienc