Emerging role of G protein-coupled receptors in microvascular myogenic tone

Blood flow autoregulation results from the ability of resistance arteries to reduce or increase their diameters in response to changes in intravascular pressure. The mechanism by which arteries maintain a constant blood flow to organs over a range of pressures relies on this myogenic response, which defines the intrinsic property of the smooth muscle to contract in response to stretch. The resistance to flow created by myogenic tone (MT) prevents tissue damage and allows the maintenance of a constant perfusion, despite fluctuations in arterial pressure. Interventions targeting MT may provide a more rational therapeutic approach in vascular disorders, such as hypertension, vasospasm, chronic heart failure, or diabetes. Despite its early description by Bayliss in 1902, the cellular and molecular mechanisms underlying MT remain poorly understood. We now appreciate that MT requires a complex mechanotransduction converting a physical stimulus (pressure) into a biological response (change in vessel diameter). Although smooth muscle cell depolarization and a rise in intracellular calcium concentration are recognized as cornerstones of the myogenic response, the role of wall strain-induced formation of vasoactive mediators is less well established. The vascular system expresses a large variety of Class 1 G protein-coupled receptors (GPCR) activated by an eclectic range of chemical entities, including peptides, lipids, nucleotides, and amines. These messengers can function in blood vessels as vasoconstrictors. This review focuses on locally generated GPCR agonists and their proposed contributions to MT. Their interplay with pivotal G(q-11) and G(12-13) protein signalling is also discussed

Chronic inhibition of endoplasmic reticulum stress and inflammation prevents ischaemia-induced vascular pathology in type II diabetic mice

Endoplasmic reticulum (ER) stress and inflammation are important mechanisms that underlie many of the serious consequences of type II diabetes. However, the role of ER stress and inflammation in impaired ischaemia-induced neovascularization in type II diabetes is unknown. We studied ischaemia-induced neovascularization in the hind-limb of 4-week-old db - /db- mice and their controls treated with or without the ER stress inhibitor (tauroursodeoxycholic acid, TUDCA, 150 mg/kg per day) and interleukin-1 receptor antagonist (anakinra, 0.5 microg/mouse per day) for 4 weeks. Blood pressure was similar in all groups of mice. Blood glucose, insulin levels, and body weight were reduced in db - /db- mice treated with TUDCA. Increased cholesterol and reduced adiponectin in db - /db- mice were restored by TUDCA and anakinra treatment. ER stress and inflammation in the ischaemic hind-limb in db - /db- mice were attenuated by TUDCA and anakinra treatment. Ischaemia-induced neovascularization and blood flow recovery were significantly reduced in db - /db- mice compared to control. Interestingly, neovascularization and blood flow recovery were restored in db - /db- mice treated with TUDCA or anakinra compared to non-treated db - /db- mice. TUDCA and anakinra enhanced eNOS-cGMP, VEGFR2, and reduced ERK1/2 MAP-kinase signalling, while endothelial progenitor cell number was similar in all groups of mice. Our findings demonstrate that the inhibition of ER stress and inflammation prevents impaired ischaemia-induced neovascularization in type II diabetic mice. Thus, ER stress and inflammation could be potential targets for a novel therapeutic approach to prevent impaired ischaemia-induced vascular pathology in type II diabetes

Plasmacytoid dendritic cells contribute to vascular endothelial dysfunction in type 2 diabetes

ObjectiveType 2 diabetes (T2D) is associated with an increased risk of cardiovascular disease due to macro- and microvascular dysfunction. This study aimed to investigate the potential involvement of plasmacytoid dendritic cells (pDCs) in T2D-related vascular dysfunction.Approach and resultspDCs were isolated from db/db and control mice. It was found that pDCs from db/db mice impaired endothelial cell eNOS phosphorylation in response to ATP and decreased vascular endothelium-dependent relaxation compared to pDCs from control mice. Moreover, isolated CD4+ cells from control mice, when stimulated overnight with high glucose and lipids, and isolated pDCs from db/db mice, display elevated levels of ER stress, inflammation, and apoptosis markers. Flow cytometry revealed that pDC frequency was higher in db/db mice than in controls. In vivo, the reduction of pDCs using anti-PDCA-1 antibodies in male and female db/db mice for 4 weeks significantly improved vascular endothelial function and eNOS phosphorylation.ConclusionpDCs may contribute to vascular dysfunction in T2D by impairing endothelial cell function. Targeting pDCs with anti-PDCA-1 antibodies may represent a promising therapeutic strategy for improving vascular endothelial function in T2D patients. This study provides new insights into the pathogenesis of T2D-related vascular dysfunction and highlights the potential of immunomodulatory therapies for treating this complication. Further studies are warranted to explore the clinical potential of this approach

Interleukin-1β Disruption Protects Male Mice From Heart Failure With Preserved Ejection Fraction Pathogenesis

Background: Heart failure with preserved ejection fraction (HFpEF) is a significant unmet need in cardiovascular medicine and remains an untreatable cardiovascular disease. The role and mechanism of interleukin-1β in HFpEF pathogenesis are poorly understood. Methods and Results: C57/Bl6J and interleukin-1β(-/-) male mice were randomly divided into 4 groups. Groups 1 and 2: C57/Bl6J and interleukin-1β(-/-) mice were fed a regular diet for 4 months and considered controls. Groups 3 and 4: C57/Bl6 and interleukin-1β(-/-) mice were fed a high-fat diet with N[w]-nitro-l-arginine methyl ester (endothelial nitric oxide synthase inhibitor, 0.5 g/L) in the drinking water for 4 months. We measured body weight, blood pressure, diabetes status, cardiac function/hypertrophy/inflammation, fibrosis, vascular endothelial function, and signaling. C57/Bl6 fed a high-fat diet and N[w]-nitro-l-arginine methyl ester in the drinking water for 4 months developed HFpEF pathogenesis characterized by obesity, diabetes, hypertension, cardiac hypertrophy, lung edema, low running performance, macrovascular and microvascular endothelial dysfunction, and diastolic cardiac dysfunction but no change in cardiac ejection fraction compared with control mice. Interestingly, the genetic disruption of interleukin-1β protected mice from HFpEF pathogenesis through the modulation of the inflammation and endoplasmic reticulum stress mechanisms. Conclusions: Our data suggest that interleukin-1β is a critical driver in the development of HFpEF pathogenesis, likely through regulating inflammation and endoplasmic reticulum stress pathways. Our findings provide a potential therapeutic target for HFpEF treatment

Endothelial CHOP as a central mechanism in renovascular hypertension-induced vascular endothelial dysfunction and cardiac fibrosis

Abstract Objective In this study, we sought to determine the significant impact of the vascular endothelial endoplasmic reticulum (ER) stress C/EBP homologous protein (CHOP) in renovascular hypertension-induced vascular endothelial dysfunction and cardiac fibrosis. Approach and results Eight-week-old male and female CHOP flox/flox and EC CHOP−/− mice were randomly divided into eight groups with and without 2-Kidney-1-Clip (2K1C) surgery for four weeks. Body weight, systolic blood pressure, running performance, cardiac hypertrophy and fibrosis, lung edema, inflammation, vascular endothelial function, and signaling were assessed. For the mechanism, we utilized human coronary endothelial cells, both with and without CHOP down-regulation, and then stimulated them with and without angiotensin II ± ATP to determine eNOS phosphorylation level and the presence of inflammatory factors. Male and female CHOP flox/flox mice subjected to 2K1C for four weeks exhibited hypertension, cardiac hypertrophy and fibrosis, lung edema, impaired running performance, endothelium-dependent vascular relaxation dysfunction, reduction in eNOS phosphorylation, and inflammation induction. In contrast, male and female EC CHOP−/− mice subjected to 2K1C for four weeks were protected against the pathogenesis of renovascular hypertension. In vitro, data showed that deletion of CHOP in endothelial cells protected eNOS phosphorylation level and blunted the induction of inflammation in response to angiotensin II ± ATP. Conclusion Our research findings determined that CHOP is a central mechanism driving vascular endothelial dysfunction and cardiac fibrosis in renovascular hypertension. Therefore, targeting CHOP in endothelial cells could be a potential therapeutic approach to protect against the pathogenesis of renovascular hypertension

Unveiling the vulnerability of C57BL/6J female mice to HFpEF and its related complications

Introduction: The impact of female biological sex on the development of heart failure with preserved ejection fraction (HFpEF) and its associated kidney disease and vascular endothelial dysfunction is still controversial. Whether females are protected from HFpEF and associated complications is not well established. Previous studies report conflicting prevalence between genders. We hypothesize that female mice are unprotected from HFpEF and its associated kidney disease and vascular endothelial dysfunction. Methods: Eight-week-old female mice were divided into four groups: control groups receiving a standard diet and water for either 5 or 16 weeks, and HFpEF groups fed a high-fat diet (HFD, Rodent Diet With 60 kcal% Fat) and N[w]-nitro-l-arginine methyl ester (L-NAME - 0.5 g/L) in the drinking water for 5 or 16 weeks. Various measurements and assessments were performed, including echocardiography, metabolic and hypertensive evaluations, markers of heart and kidney injury, and assessment of vascular endothelial function. Results: Female mice with HFD and L-NAME developed HFpEF at 5 weeks, evidenced by increased E/E' ratio, reduced cardiac index, left ventricular mass, and unchanged ejection fraction. After 16 weeks, HFpEF worsened. Metabolic disorders, hypertension, lung wet/kidney weight increase, exercise intolerance, and cardiac/renal injury markers were observed. Vascular endothelial dysfunction was associated with ER stress and fibrosis induction. Conclusions: We found that female mice are susceptible to the development of HFpEF and its associated kidney disease and vascular endothelial dysfunction. Our data support the concept that the female sex does not protect from HFpEF and its associated kidney disease and vascular endothelial dysfunction when disease risk factors are present

Endothelial CHOP as a central mechanism in renovascular hypertension-induced vascular endothelial dysfunction and cardiac fibrosis

OBJECTIVE: In this study, we sought to determine the significant impact of the vascular endothelial endoplasmic reticulum (ER) stress C/EBP homologous protein (CHOP) in renovascular hypertension-induced vascular endothelial dysfunction and cardiac fibrosis. APPROACH AND RESULTS: Eight-week-old male and female CHOP(flox/flox) and EC(CHOP-/-) mice were randomly divided into eight groups with and without 2-Kidney-1-Clip (2K1C) surgery for four weeks. Body weight, systolic blood pressure, running performance, cardiac hypertrophy and fibrosis, lung edema, inflammation, vascular endothelial function, and signaling were assessed. For the mechanism, we utilized human coronary endothelial cells, both with and without CHOP down-regulation, and then stimulated them with and without angiotensin II ± ATP to determine eNOS phosphorylation level and the presence of inflammatory factors. Male and female CHOP(flox/flox) mice subjected to 2K1C for four weeks exhibited hypertension, cardiac hypertrophy and fibrosis, lung edema, impaired running performance, endothelium-dependent vascular relaxation dysfunction, reduction in eNOS phosphorylation, and inflammation induction. In contrast, male and female EC(CHOP-/-) mice subjected to 2K1C for four weeks were protected against the pathogenesis of renovascular hypertension. In vitro, data showed that deletion of CHOP in endothelial cells protected eNOS phosphorylation level and blunted the induction of inflammation in response to angiotensin II ± ATP. CONCLUSION: Our research findings determined that CHOP is a central mechanism driving vascular endothelial dysfunction and cardiac fibrosis in renovascular hypertension. Therefore, targeting CHOP in endothelial cells could be a potential therapeutic approach to protect against the pathogenesis of renovascular hypertension

A novel role for epidermal growth factor receptor tyrosine kinase and its downstream endoplasmic reticulum stress in cardiac damage and microvascular dysfunction in type 1 diabetes mellitus

International audienceEpidermal growth factor receptor tyrosine kinase (EGFRtk) and endoplasmic reticulum (ER) stress are important factors in cardiovascular complications. Understanding whether enhanced EGFRtk activity and ER stress induction are involved in cardiac damage, and microvascular dysfunction in type 1 diabetes mellitus is an important question that has remained unanswered. Cardiac fibrosis and microvascular function were determined in C57BL/6J mice injected with streptozotocin only or in combination with EGFRtk inhibitor (AG1478), ER stress inhibitor (Tudca), or insulin for 2 weeks. In diabetic mice, we observed an increase in EGFRtk phosphorylation and ER stress marker expression (CHOP, ATF4, ATF6, and phosphorylated-eIF2alpha) in heart and mesenteric resistance arteries, which were reduced with AG1478, Tudca, and insulin. Cardiac fibrosis, enhanced collagen type I, and plasminogen activator inhibitor 1 were decreased with AG1478, Tudca, and insulin treatments. The impaired endothelium-dependent relaxation and -independent relaxation responses were also restored after treatments. The inhibition of NO synthesis reduced endothelium-dependent relaxation in control and treated streptozotocin mice, whereas the inhibition of NADPH oxidase improved endothelium-dependent relaxation only in streptozotocin mice. Moreover, in mesenteric resistance arteries, the mRNA levels of Nox2 and Nox4 and the NADPH oxidase activity were augmented in streptozotocin mice and reduced with treatments. This study unveiled novel roles for enhanced EGFRtk phosphorylation and its downstream ER stress in cardiac fibrosis and microvascular endothelial dysfunction in type 1 diabetes mellitus.</p