Communication Is Key: Mechanisms of Intercellular Signaling in Vasodilation

Endothelial histone deacetylase 1 activity impairs kidney microvascular NO signaling in rats fed a high-salt diet

AIM

We aimed to test the hypothesis that a high-salt diet (HS) impairs NO signaling in kidney microvascular endothelial cells through a histone deacetylase 1 (HDAC1)-dependent mechanism.

METHODS

Male Sprague Dawley rats were fed normal salt diet (NS; 0.49% NaCl) or HS (4% NaCl) for 2 weeks. NO signaling was assessed by measuring L-NAME induced vasoconstriction of the afferent arteriole using the blood perfused juxtamedullary nephron (JMN) preparation. In this preparation, kidneys were perfused with blood from a donor rat on a matching or different diet to that of the kidney donor. Kidney endothelial cells were isolated with magnetic activated cell sorting and HDAC1 activity was measured.

RESULTS

We found HS-induced impaired NO signaling in the afferent arteriole. This was restored by inhibition of HDAC1 with MS-275. Consistent with these findings, HDAC1 activity was increased in kidney endothelial cells. We further found the loss of NO to be dependent upon the diet of the blood donor rather than the diet of the kidney donor and the plasma from HS-fed rats to be sufficient to induce impaired NO signaling. This indicates the presence of a humoral factor we termed plasma-derived endothelial dysfunction mediator (PDEM). Pretreatment with the antioxidants, PEG-SOD and PEG-catalase, as well as the NOS cofactor, tetrahydrobiopterin, restored NO signaling.

CONCLUSION

We conclude that HS activates endothelial HDAC1 through PDEM leading to decreased NO signaling. This study provides novel insights into the molecular mechanisms by which a HS decreases renal microvascular endothelial NO signaling.

Molecular mechanisms of endothelial dysfunction in coronary microcirculation dysfunction

Coronary microvascular endothelial cells (CMECs) react to changes in coronary blood flow and myocardial metabolites and regulate coronary blood flow by balancing vasoconstrictors-such as endothelin-1-and the vessel dilators prostaglandin, nitric oxide, and endothelium-dependent hyperpolarizing factor. Coronary microvascular endothelial cell dysfunction is caused by several cardiovascular risk factors and chronic rheumatic diseases that impact CMEC blood flow regulation, resulting in coronary microcirculation dysfunction (CMD). The mechanisms of CMEC dysfunction are not fully understood. However, the following could be important mechanisms: the overexpression and activation of nicotinamide adenine dinucleotide phosphate oxidase (Nox), and mineralocorticoid receptors; the involvement of reactive oxygen species (ROS) caused by a decreased expression of sirtuins (SIRT3/SIRT1); forkhead box O3; and a decreased SKCA/IKCA expression in the endothelium-dependent hyperpolarizing factor electrical signal pathway. In addition, p66Shc is an adapter protein that promotes oxidative stress; although there are no studies on its involvement with cardiac microvessels, it is possible it plays an important role in CMD.

Butyrate inhibits LPC-induced endothelial dysfunction by regulating nNOS-produced NO and ROS production

Lipids oxidation is a key risk factor for cardiovascular diseases. Lysophosphatidylcholine (LPC), the major component of oxidized LDL, is an important triggering agent for endothelial dysfunction and atherogenesis. Sodium butyrate, a short-chain fatty acid, has demonstrated atheroprotective properties. So, we evaluate the role of butyrate in LPC-induced endothelial dysfunction. Vascular response to phenylephrine (Phe) and acetylcholine (Ach) was performed in aortic rings from male mice (C57BL/6J). The aortic rings were incubated with LPC (10 μM) and butyrate (0.01 or 0.1 Mm), with or without TRIM (an nNOS inhibitor). Endothelial cells (EA.hy296) were incubated with LPC and butyrate to evaluate nitric oxide (NO) and reactive oxygen species (ROS) production, calcium influx, and the expression of total and phosphorylated nNOS and ERK½. We found that butyrate inhibited LPC-induced endothelial dysfunction by improving nNOS activity in aortic rings. In endothelial cells, butyrate reduced ROS production and increased nNOS-related NO release, by improving nNOS activation (phosphorylation at Ser1412). Additionally, butyrate prevented the increase in cytosolic calcium and inhibited ERk½ activation by LPC. In conclusion, butyrate inhibited LPC-induced vascular dysfunction by increasing nNOS-derived NO and reducing ROS production. Butyrate restored nNOS activation, which was associated with calcium handling normalization and reduction of ERK½ activation.

Understanding human aging and the fundamental cell signaling link in age-related diseases: the middle-aging hypovascularity hypoxia hypothesis

Aging-related hypoxia, oxidative stress, and inflammation pathophysiology are closely associated with human age-related carcinogenesis and chronic diseases. However, the connection between hypoxia and hormonal cell signaling pathways is unclear, but such human age-related comorbid diseases do coincide with the middle-aging period of declining sex hormonal signaling. This scoping review evaluates the relevant interdisciplinary evidence to assess the systems biology of function, regulation, and homeostasis in order to discern and decipher the etiology of the connection between hypoxia and hormonal signaling in human age-related comorbid diseases. The hypothesis charts the accumulating evidence to support the development of a hypoxic milieu and oxidative stress-inflammation pathophysiology in middle-aged individuals, as well as the induction of amyloidosis, autophagy, and epithelial-to-mesenchymal transition in aging-related degeneration. Taken together, this new approach and strategy can provide the clarity of concepts and patterns to determine the causes of declining vascularity hemodynamics (blood flow) and physiological oxygenation perfusion (oxygen bioavailability) in relation to oxygen homeostasis and vascularity that cause hypoxia (hypovascularity hypoxia). The middle-aging hypovascularity hypoxia hypothesis could provide the mechanistic interface connecting the endocrine, nitric oxide, and oxygen homeostasis signaling that is closely linked to the progressive conditions of degenerative hypertrophy, atrophy, fibrosis, and neoplasm. An in-depth understanding of these intrinsic biological processes of the developing middle-aged hypoxia could provide potential new strategies for time-dependent therapies in maintaining healthspan for healthy lifestyle aging, medical cost savings, and health system sustainability.

Endothelial Histone Deacetylase 1 Activity Impairs Kidney Microvascular NO Signaling in Rats fed a High Salt Diet

Aim

We aimed to identify new mechanisms by which a high salt diet (HS) decreases NO production in kidney microvascular endothelial cells. Specifically, we hypothesized HS impairs NO signaling through a histone deacetylase 1 (HDAC1)-dependent mechanism.

Methods

Male Sprague Dawley rats were fed normal salt diet (NS; 0.49% NaCl) or high salt diet (4% NaCl) for two weeks. NO signaling was assessed by measuring L-NAME induced vasoconstriction of the afferent arteriole using the blood perfused juxtamedullary nephron (JMN) preparation. In this preparation, kidneys were perfused with blood from a donor rat on a matching or different diet to that of the kidney donor. Kidney endothelial cells were isolated with magnetic activated cell sorting and HDAC1 activity was measured.

Results

We found that HS impaired NO signaling in the afferent arteriole. This was restored by inhibition of HDAC1 with MS-275. Consistent with these findings, HDAC1 activity was increased in kidney endothelial cells. We further found the loss of NO to be dependent upon the diet of the blood donor rather than the diet of the kidney donor and the plasma from HS fed rats to be sufficient to induce dysfunction suggesting a humoral factor, we termed Plasma Derived Endothelial-dysfunction Mediator (PDEM), mediates the endothelial dysfunction. The antioxidants, PEG-SOD and PEG-catalase, as well as the NOS cofactor, tetrahydrobiopterin, restored NO signaling.

Conclusion

We conclude that HS activates endothelial HDAC1 through PDEM leading to decreased NO signaling. This study provides novel insights into the molecular mechanisms by which a HS decreases renal microvascular endothelial NO signaling.

The Importance of Integrated Regulation Mechanism of Coronary Microvascular Function for Maintaining the Stability of Coronary Microcirculation: An Easily Overlooked Perspective

Coronary microvascular dysfunction (CMD) refers to a group of disorders affecting the structure and function of coronary microcirculation and is associated with an increased risk of major adverse cardiovascular events. At present, great progress has been made in the diagnosis of CMD, but there is no specific treatment for it because of the complexity of CMD pathogenesis. Vascular dysfunction is one of the important causes of CMD, but previous reviews mostly considered microvascular dysfunction as a whole abnormality so the obtained conclusions are skewed. The coronary microvascular function is co-regulated by multiple mechanisms, and the mechanisms by which microvessels of different luminal diameters are regulated vary. The main purpose of this review is to revisit the mechanisms by which coronary microvessels at different diameters regulate coronary microcirculation through integrated sequential activation and briefly discuss the pathogenesis, diagnosis, and treatment progress of CMD from this perspective.

Evaluation of vasodilatory effect and antihypertensive effect of chrysin through in vitro and sub-chronic in vivo study

Chrysin, a bioflavonoid belonging to the flavone, occurs naturally in plants such as the passionflower, honey and propolis. Few studies have demonstrated that chrysin can promote vasorelaxant activities in rats' aorta and mesenteric arteries. To date, no research has explored the signalling system routes that chrysin may utilise to produce its vasorelaxant action. Therefore, this study aimed to investigate the underlying mechanisms involved in chrysin-induced vasorelaxant in rats' aortic rings and assess the antihypertensive effect of chrysin in spontaneously hypertensive rats (SHRs). The findings revealed that chrysin utilised both endothelium-dependent and endothelium-independent mechanisms. The presence of L-NAME (endothelial NO synthase inhibitor), ODQ (sGC inhibitor), methylene blue (cGMP lowering agent), 4-AP (voltage-gated potassium channel inhibitor), atropine (muscarinic receptors inhibitor) and propranolol (β-adrenergic receptors inhibitor) significantly reduced the chrysin's vasorelaxant action. Furthermore, chrysin can reduce intracellular Ca²⁺ levels by limiting the extracellular intake of Ca²⁺ through voltage-operated calcium channels and blocking the intracellular release of Ca²⁺ from the sarcoplasmic reticulum via the IP₃ receptor. These indicate that chrysin-induced vasorelaxants involved NO/sGC/cGMP signalling cascade, muscarinic and β-adrenergic receptors, also the potassium and calcium channels. Although chrysin had vasorelaxant effects in in vitro studies, the in vivo antihypertensive experiment discovered chrysin does not significantly reduce the blood pressure of SHRs following 21 days of oral treatment. This study proved that chrysin utilised multiple signalling pathways to produce its vasorelaxant effect in the thoracic aorta of rats; however, it had no antihypertensive effect on SHRs.

Intracellular communication and immunothrombosis in sepsis

Inflammation and coagulation are the critical responses to infection that include leukocytes, platelets, and vascular endothelial cells responding in concert to eradicate the invading pathogen. In sepsis, a variety of cell surface receptors, including toll-like receptors, Fcγ-receptors, G-protein-coupled receptors, and adhesion receptors, detect the pathogens and elicit thromboinflammatory responses. Concurrently, the molecular patterns released from host damaged cells accelerate the immune responses through binding to the same pattern recognition receptors. Cytokines, chemokines, and extracellular vesicles are important mediators for amplifying the responses to distant cells as part of the systemic response to infections. At the same time, cells communicate with each other via direct contact, adhesion molecules, paracrine mediators, and tunneling nanotubes, which are important for regulating inflammation and thrombus formation. Despite increasing attention to immunothrombosis in sepsis, these close communication systems are less understood but play a critical role in host defense mechanisms. In this review, cellular activation and direct intercellular communication systems in sepsis with a focus on the coagulation response will be considered.

Loss of Jagged1 in mature endothelial cells causes vascular dysfunction with alterations in smooth muscle phenotypes

BACKGROUND

Notch signaling is an evolutionarily conserved pathway that functions via direct cell-cell contact. The Notch ligand Jagged1 (Jag1) has been extensively studied in vascular development, particularly for its role in smooth muscle cell maturation. Endothelial cell-expressed Jag1 is essential for blood vessel formation by signaling to nascent vascular smooth muscle cells and promoting their differentiation. Given the established importance of Jag1 in endothelial cell/smooth muscle crosstalk during development, we sought to determine the extent of this communication in the adult vasculature for blood vessel function and homeostasis.

METHODS

We conditionally deleted Jag1 in endothelial cells of adult mice and examined the phenotypic consequences on smooth muscle cells of the vasculature.

RESULTS

Our results show that genetic loss of Jag1 in endothelial cells has a significant impact on Notch signaling and vascular smooth muscle function in mature blood vessels. Endothelial cell-specific deletion of Jag1 causes a concomitant loss of JAG1 and NOTCH3 expression in vascular smooth muscle cells, resulting in a transition to a less differentiated state. Aortic vascular smooth muscle cells isolated from the endothelial cell-specific Jag1 deficient mice retain an altered phenotype in culture with fixed changes in gene expression and reduced Notch signaling. Utilizing comparative RNA-sequence analysis, we found that Jag1 deficiency preferentially affects extracellular matrix and adhesion protein gene expression. Vasoreactivity studies revealed a reduced contractile response and impaired agonist-induced relaxation in endothelial cell Jag1-deficient aortas compared to controls.

CONCLUSIONS

These data are the first to demonstrate that Jag1 in adult endothelial cells is required for the regulation and homeostasis of smooth muscle cell function in arterial vessels partially through the autoregulation of Notch signaling and cell matrix/adhesion components in smooth muscle cells.

The predominance of endothelium-derived relaxing factors and beta-adrenergic receptor pathways in strong vasorelaxation induced by 4-hydroxybenzaldehyde in the rat aorta

4-hydroxybenzaldehyde (4HB), known as ρ-hydroxybenzaldehyde, is commonly present in traditional Chinese medicine herb, most frequently used for hypertension treatment. This research aims to determine the potency of 4HB's vasorelaxant action. In the study, the vasodilation effect of 4HB was evaluated using in vitro isolated rat aortic rings assay. The aortic rings were pre-incubated with respective antagonists before being pre-contracted with phenylephrine (PE) and challenged with various concentrations of 4HB for mechanistic action studies. R_max (maximal vasodilation) and pEC₅₀ (negative logarithm of half-maximal effective concentration) values of each experiment were determined for comparison purposes. 4HB caused vasodilation on endothelium-intact aortic rings which pre-contracted with PE (pEC₅₀ = 3.53 ± 0.05, R_max = 100.95 ± 4.25%) or potassium chloride (pEC₅₀ = 2.96 ± 0.13, R_max = 72.13 ± 4.93%). The vasodilation effect of 4HB was significantly decreased in the absence of an endothelium (pEC₅₀ = 2.21 ± 0.25, R_max = 47.96 ± 4.16%). The atropine, 4-aminopyridine, Nω-nitro-L-arginine methyl ester, glibenclamide, and propranolol significantly reduced the vasorelaxation effect of 4HB. Besides that, 4HB blocked the voltage-operated calcium channel (VOCC) and regulated the intracellular Ca²⁺ release from the sarcoplasmic reticulum (SR) in the aortic ring. Thus, the results indicated that 4HB exerted its vasodilatory effect via cGMP and β₂ pathways, M₃-dependent PLC/IP₃ pathways, and potassium and calcium channels.

Connexin 43 Expression in Cutaneous Biopsies of Lupus Erythematosus

INTRODUCTION

Gap junctions are channels between adjacent cells formed by connexins (Cxs). Cxs also form hemichannels that connect the cell with its extracellular milieu. These channels allow the transport of ions, metabolites, and small molecules; therefore, Cxs, and more specifically, connexin (Cx) 43 has been demonstrated to be in control of several crucial events such as inflammation and cell death.

MATERIAL AND METHODS

We examined the immunostaining of Cx43 in the endothelia of the cutaneous blood vessels of biopsies from 28 patients with several variants of lupus erythematosus.

RESULTS

In 19 cases (67.86%), staining of more than half of the dermal vessels including both vessels of the papillary and of the reticular dermis was identified. Only in 4 cases (14.28%), less than 25% of the vessels in the biopsy showed expression of the marker.

CONCLUSIONS

Our results suggest a role of Cx43 in regulating the endothelial activity in lupus erythematosus, which also opens a door for targeted therapeutic options.

Cyclooxygenase-dependent mechanisms mediate in part the anti-dilatory effects of perivascular adipose tissue in uterine arteries from pregnant rats

Uterine perivascular adipose tissue (PVAT) contributes to uterine blood flow regulation in pregnancy, at least in part, due to its effects on uterine artery reactivity. We tested the hypothesis that uterine PVAT modulates the balance between the contribution of nitric oxide synthase (NOS)- and cyclooxygenase (COX)-dependent pathways to acetylcholine (ACh)-induced relaxation in isolated uterine arteries. Concentration-response curves to ACh (1 nM - 30 µM) were performed on uterine arteries from pregnant and non-pregnant rats. Arteries were exposed to Krebs-Henseleit solution (control) or PVAT-conditioned media (PVATmedia) in the presence of the following inhibitors: L-NAME (NOS inhibitor), indomethacin (COX inhibitor), SC560 (COX-1 inhibitor), NS398 (COX-2 inhibitor), SQ 29,548 (thromboxane receptor (TP) inhibitor). In arteries incubated with PVATmedia, the presence of indomethacin increased ACh-induced relaxation, reversing the anti-dilatory effect of PVATmedia. NOS inhibition reduced ACh-induced relaxation in uterine arteries from pregnant rats, and exposure to PVATmedia did not change this effect. Selective inhibition of COX-1 but not COX-2 suppressed relaxation responses to ACh in control arteries. The presence of PVATmedia abolished the effect of COX-1 inhibition. Incubation of uterine arteries from pregnant rats with PVATmedia increased production of thromboxane B2 (TxB2, p = 0.01) but thromboxane receptor (TP) inhibition did not affect the anti-dilatory properties of PVATmedia. In conclusion, inhibition of COX signaling suppressed the anti-dilatory effects of PVATmedia, while PVATmedia had no effect on the contribution of the NOS/NO pathway to ACh-induced relaxation in uterine arteries from pregnant rats, indicating that the anti-dilatory effects of uterine PVAT are mediated in part by COX-dependent mechanisms.

Negative Influence by the Force: Mechanically Induced Hyperpolarization via K2P Background Potassium Channels

The two-pore domain K_2P subunits form background (leak) potassium channels, which are characterized by constitutive, although not necessarily constant activity, at all membrane potential values. Among the fifteen pore-forming K_2P subunits encoded by the KCNK genes, the three members of the TREK subfamily, TREK-1, TREK-2, and TRAAK are mechanosensitive ion channels. Mechanically induced opening of these channels generally results in outward K⁺ current under physiological conditions, with consequent hyperpolarization and inhibition of membrane potential-dependent cellular functions. In the past decade, great advances have been made in the investigation of the molecular determinants of mechanosensation, and members of the TREK subfamily have emerged among the best-understood examples of mammalian ion channels directly influenced by the tension of the phospholipid bilayer. In parallel, the crucial contribution of mechano-gated TREK channels to the regulation of membrane potential in several cell types has been reported. In this review, we summarize the general principles underlying the mechanical activation of K_2P channels, and focus on the physiological roles of mechanically induced hyperpolarization.

The Mechanisms of L-Arginine Metabolism Disorder in Endothelial Cells

L-arginine is a key metabolite for nitric oxide production by endothelial cells, as well as signaling molecule of the mTOR signaling pathway. mTOR supports endothelial cells homeostasis and regulates activity of L-arginine-metabolizing enzymes, endothelial nitric oxide synthase, and arginase II. Disruption of the L-arginine metabolism in endothelial cells leads to the development of endothelial dysfunction. Conflicting results of the use of L-arginine supplement to improve endothelial function reveals a controversial role of the amino acid in the endothelial cell biology. The review is aimed at analysis of the current data on the role of L-arginine metabolism in the development of endothelial dysfunction.

Endothelium-dependent remote signaling in ischemia and reperfusion: Alterations in the cardiometabolic continuum

Intact endothelial function plays a fundamental role for the maintenance of cardiovascular (CV) health. The endothelium is also involved in remote signaling pathway-mediated protection against ischemia/reperfusion (I/R) injury. However, the transfer of these protective signals into clinical practice has been hampered by the complex metabolic alterations frequently observed in the cardiometabolic continuum, which affect redox balance and inflammatory pathways. Despite recent advances in determining the distinct roles of hyperglycemia, insulin resistance (InR), hyperinsulinemia, and ultimately diabetes mellitus (DM), which define the cardiometabolic continuum, our understanding of how these conditions modulate endothelial signaling remains challenging. It is widely accepted that endothelial cells (ECs) undergo functional changes within the cardiometabolic continuum. Beyond vascular tone and platelet-endothelium interaction, endothelial dysfunction may have profound negative effects on outcome during I/R. In this review, we summarize the current knowledge of the influence of hyperglycemia, InR, hyperinsulinemia, and DM on endothelial function and redox balance, their influence on remote protective signaling pathways, and their impact on potential therapeutic strategies to optimize protective heterocellular signaling.

Pathophysiological adaptations of resistance arteries in rat offspring exposed in utero to maternal obesity is associated with sex-specific epigenetic alterations

BACKGROUND/OBJECTIVES

Maternal obesity impacts vascular functions linked to metabolic disorders in offspring, leading to cardiovascular diseases during adulthood. Even if the relation between prenatal conditioning of cardiovascular diseases by maternal obesity and vascular function begins to be documented, little is known about resistance arteries. They are of particular interest because of their specific role in the regulation of local blood flow. Then our study aims to determine if maternal obesity can directly program fetal vascular dysfunction of resistance arteries, independently of metabolic disorders.

METHODS

With a model of rats exposed in utero to mild maternal diet-induced obesity (OMO), we investigated third-order mesenteric arteries of 4-month old rats in absence of metabolic disorders. The methylation profile of these vessels was determined by reduced representation bisulfite sequencing (RRBS). Vascular structure and reactivity were investigated using histomorphometry analysis and wire-myography. The metabolic function was evaluated by insulin and glucose tolerance tests, plasma lipid profile, and adipose tissue analysis.

RESULTS

At 4 months of age, small mesenteric arteries of OMO presented specific epigenetic modulations of matrix metalloproteinases (MMPs), collagens, and potassium channels genes in association with an outward remodeling and perturbations in the endothelium-dependent vasodilation pathways (greater contribution of EDHFs pathway in OMO males compared to control rats, and greater implication of PGI₂ in OMO females compared to control rats). These vascular modifications were detected in absence of metabolic disorders.

CONCLUSIONS

Our study reports a specific methylation profile of resistance arteries associated with vascular remodeling and vasodilation balance perturbations in offspring exposed in utero to maternal obesity, in absence of metabolic dysfunctions.

Endothelium-Derived Hyperpolarizing Factor and Myoendothelial Coupling: The in vivo Perspective

The endothelium controls vascular tone adopting blood flow to tissue needs. It releases chemical mediators [e.g., nitric oxide (NO), prostaglandins (PG)] and exerts appreciable dilation through smooth muscle hyperpolarization, thus termed endothelium-dependent hyperpolarization (EDH). Initially, EDH was attributed to release of a factor, but later it was suggested that smooth muscle hyperpolarization might be derived from radial spread of an initial endothelial hyperpolarization through heterocellular channels coupling these vascular cells. The channels are indeed present and formed by connexins that enrich in gap junctions (GJ). In vitro data suggest that myoendothelial coupling underlies EDH-type dilations as evidenced by blocking experiments as well as simultaneous, merely identical membrane potential changes in endothelial and smooth muscle cells (SMCs), which is indicative of coupling through ohmic resistors. However, connexin-deficient animals do not display any attenuation of EDH-type dilations in vivo, and endothelial and SMCs exhibit distinct and barely superimposable membrane potential changes exerted by different means in vivo. Even if studied in the exact same artery EDH-type dilation exhibits distinct features in vitro and in vivo: in isometrically mounted vessels, it is rather weak and depends on myoendothelial coupling through connexin40 (Cx40), whereas in vivo as well as in vitro under isobaric conditions it is powerful and independent of myoendothelial coupling through Cx40. It is concluded that EDH-type dilations are distinct and a significant dependence on myoendothelial coupling in vitro does not reflect the situation under physiologic conditions in vivo. Myoendothelial coupling may act as a backup mechanism that is uncovered in the absence of the powerful EDH-type response and possibly reflects a situation in a pathophysiologic environment.

Endothelial cells control vascular smooth muscle cell cholesterol levels by regulating 24-dehydrocholesterol reductase expression

Communication of vascular cells is essential for the control of organotypic functions of blood vessels. In this context, vascular endothelial cells (EC) act as potent regulators of vascular smooth muscle cell (VSMC) functions such as contraction and relaxation. However, the impact of ECs on the gene expression pattern of VSMCs is largely unknown. Here, we investigated changes of the VSMC transcriptome by utilizing 3D human vascular organoids organized as a core of VSMCs enclosed by a monolayer of ECs. Microarray-based analyses indicated that interaction with ECs for 48 h down-regulates expression of genes in VSMCs controlling rate-limiting steps of the cholesterol biosynthesis such as HMGCR, HMGCS1, DHCR24 and DHCR7. Protein analyses revealed a decrease in the abundance of DHCR24 (24-dehydrocholesterol reductase) and lower cholesterol levels in VSMCs co-cultured with ECs. On the functional level, the blockade of the DHCR24 activity impaired adhesion, migration and proliferation of VSMCs. Collectively, these findings indicate that ECs have the capacity to instruct VSMCs to shut down the expression of DHCR24 thereby limiting their cholesterol biosynthesis, which may support their functional steady state.

Oxidative Stress: A Unifying Paradigm in Hypertension

The etiology of hypertension involves complex interactions among genetic, environmental, and pathophysiologic factors that influence many regulatory systems. Hypertension is characteristically associated with vascular dysfunction, cardiovascular remodelling, renal dysfunction, and stimulation of the sympathetic nervous system. Emerging evidence indicates that the immune system is also important and that activated immune cells migrate and accumulate in tissues promoting inflammation, fibrosis, and target-organ damage. Common to these processes is oxidative stress, defined as an imbalance between oxidants and antioxidants in favour of the oxidants that leads to a disruption of oxidation-reduction (redox) signalling and control and molecular damage. Physiologically, reactive oxygen species (ROS) act as signalling molecules and influence cell function through highly regulated redox-sensitive signal transduction. In hypertension, oxidative stress promotes posttranslational modification (oxidation and phosphorylation) of proteins and aberrant signalling with consequent cell and tissue damage. Many enzymatic systems generate ROS, but NADPH oxidases (Nox) are the major sources in cells of the heart, vessels, kidneys, and immune system. Expression and activity of Nox are increased in hypertension and are the major systems responsible for oxidative stress in cardiovascular disease. Here we provide a unifying concept where oxidative stress is a common mediator underlying pathophysiologic processes in hypertension. We focus on some novel concepts whereby ROS influence vascular function, aldosterone/mineralocorticoid actions, and immunoinflammation, all important processes contributing to the development of hypertension.

The effect of quercetin on endothelial cells is modified by heterocellular interactions

Single cell-type models are useful for determining mechanisms, but in vivo, cell-cell interactions are important, and neighbouring cells can impact endothelial cell function. Quercetin can attenuate endothelial dysfunction by modulating vascular tone and reducing inflammation. We determined the effect of quercetin on a co-culture between Human Umbilical Vein Endothelial Cells (HUVEC) and human HepG2 hepatic cells or human LHCN-M2 muscle cells. Heme oxygenase-1 (HO-1) mRNA and protein were decreased, pyruvate dehydrogenase kinase (PDK) 4 and glucose transporter (GLUT) 3 mRNA increased, and GLUT1 protein decreased in HUVEC when cultured with HepG2. GLUT transporters, but not the other targets, were similarly regulated in co-culture with muscle cells. Some but not all of the effects were mediated by lactate and transforming growth factor β1. Quercetin added apically to the endothelial cells upregulated HO-1 and downregulated PDK4 both in monoculture and in co-culture, but the total PDK4 levels were higher in the presence of HepG2 cells. In the absence of general permeability changes, glucose transport across the endothelial monolayer was elevated in the presence of HepG2 cells, however this effect was moderated by quercetin applied on the apical side of the endothelial cells. At lower glucose concentration, apical quercetin also promoted glucose uptake in HepG2 cells. Co-culturing HUVEC with the HepG2 cells showed capacity to modulate quercetin-elicited changes in endothelial gene transcription and glucose transport.

Echinacoside‑induced nitric oxide production in endothelial cells: Roles of androgen receptor and the PI3K‑Akt pathway

Echinacoside (ECH) is a natural compound with an endothelium‑dependent vasodilatory effect. Nitric oxide (NO) is an important vasorelaxant released from endothelial cells. In order to examine the molecular mechanism of ECH‑induced NO production in endothelial cells, the present study investigated the involvement of androgen receptor (AR) and the phosphatidylinositol 3‑kinase (PI3K)/protein kinase B (Akt) pathway in the phosphorylation of endothelial nitric oxide synthase (eNOS) in human umbilical vein endothelial cells (HUVECs). Using the fluorescent probe DAF‑FM, the production of NO was found to be significantly increased, and eNOS was phosphorylated at Ser1177 in a concentration‑​dependent manner under 0.01‑10 µM ECH treatment in HUVECs. In addition, NO production and eNOS phosphorylation induced by ECH were diminished when pretreated with the AR antagonist nilutamide, or when transfected with AR small interfering RNAs. Furthermore, the ECH‑induced phosphorylation of the Akt at Ser473 was abrogated by 5 µM wortmannin (a PI3K inhibitor). These data indicated that ECH stimulated NO production via the AR‑dependent activation of eNOS in HUVECs, and that the PI3K/Akt pathway may be involved in eNOS phosphorylation induced by ECH.

You Are Only as Frail as Your Arteries: Prehabilitation of Elderly Surgical Patients

Purpose of Review

To discuss the concept of prehabilitation for the elderly frail surgical patient as well as strategies to improve preoperative functional capacity and vascular function to decrease postoperative complications.

Recent Findings

Frailty is associated with poor surgical outcomes yet there is no consensus on how frailty should be measured or mitigated in the preoperative period. Prehabilitation, or improving functional capacity prior to surgery typically through exercise, has been shown to be an effective strategy to decrease preoperative frailty and improves surgical outcomes. Use of remote ischemic preconditioning (RIPC) may serve as an alternative to exercise in this fragile patient population.

Summary

Prehabilitation programs using strategies targeted at improving vascular function may decrease frailty in the preoperative period and improve surgical outcomes in the elderly population.

Paternal diet impairs F1 and F2 offspring vascular function through sperm and seminal plasma specific mechanisms in mice

KEY POINTS

A low protein diet had minimal effects on paternal cardiovascular function or renin-angiotensin system activity. Paternal low protein diet modified F1 neonatal and adult offspring renin-angiotensin system activity and cardiovascular function in a sperm and/or seminal plasma specific manner. Paternal low protein diet modified F1 male offspring testicular expression of central epigenetic regulators. Significant changes in F2 neonatal offspring growth and tissue angiotensin-converting enzyme activity were programmed by paternal low protein diet in a sperm and/or seminal plasma specific manner.

ABSTRACT

Although the impact of maternal diet on adult offspring health is well characterized, the role that a father's diet has on his offspring's health remains poorly defined. We establish the significance of a sup-optimal paternal low protein diet for offspring vascular homeostasis and define the sperm and seminal plasma specific programming effects on cardiovascular health. Male C57BL6 mice were fed either a control normal protein diet (NPD; 18% protein) or an isocaloric low protein diet (LPD; 9% protein) for a minimum of 7 weeks. Using artificial insemination, in combination with vasectomized male mating, we generated offspring derived from either NPD or LPD sperm (devoid of seminal plasma) but in the presence of NPD or LPD seminal plasma (devoid of sperm). We observed that either LPD sperm or seminal fluid at conception impaired adult offspring vascular function in response to both vasoconstrictors and dilators. Underlying these changes in vascular function were significant changes in serum, lung and kidney angiotensin-converting enzyme (ACE) activity, established in F1 offspring from 3 weeks of age, maintained into adulthood and present also within juvenile F2 offspring. Furthermore, we observed differential expression of multiple central renin-angiotensin system regulators in adult offspring kidneys. Finally, paternal diet modified the expression profiles of central epigenetic regulators of DNA methylation, histone modifications and RNA methylation in adult F1 male testes. These novel data reveal the impact of sub-optimal paternal nutrition on offspring cardiovascular well-being, programming offspring cardiovascular function through both sperm and seminal plasma specific mechanisms over successive generations.

Controlled Feeding of an 8-d, High-Dairy Cheese Diet Prevents Sodium-Induced Endothelial Dysfunction in the Cutaneous Microcirculation of Healthy, Older Adults through Reductions in Superoxide

BACKGROUND

While excess dietary sodium impairs vascular function by increasing oxidative stress, the dietary incorporation of dairy foods improves vascular health. We demonstrated that single-meal cheese consumption ameliorates acute, sodium-induced endothelial dysfunction. However, controlled feeding studies examining the inclusion of cheese, a dairy product that contains both bioactive constituents and sodium, are lacking.

OBJECTIVES

We tested the hypothesis that microcirculatory endothelium-dependent dilation (EDD) would be impaired by a high-sodium diet, but a sodium-matched diet high in dairy cheese would preserve EDD through oxidant stress mechanisms.

METHODS

We gave 11 adults without salt-sensitive blood pressure (<10 mmHg Δ mean arterial pressure; 64 ± 2 y) 4 separate 8-d controlled dietary interventions in a randomized, crossover design: a low-sodium, no-dairy intervention (LNa; 1500 mg/d sodium); a low-sodium, high-cheese intervention (LNaC; 1500 mg/d sodium, 170 g/d cheese); a high-sodium, no-dairy intervention (HNa; 5500 mg/d sodium); and a high-sodium, high-cheese intervention (HNaC; 5500 mg/d sodium, 170 g/d cheese). On Day 8 of each diet, EDD was assessed through a localized infusion (intradermal microdialysis) of acetylcholine (ACh), both alone and during coinfusion of NG-nitro-L-arginine methyl ester (NO synthase inhibitor), L-ascorbate (nonspecific antioxidant), apocynin [NAD(P)H oxidase inhibitor], or tempol (superoxide scavenger).

RESULTS

Compared with LNa, microvascular responsiveness to ACh was attenuated during HNa (LNa: -4.82 ± 0.20 versus HNa: -3.21 ± 0.55 M logEC50; P = 0.03) but not LNaC (-5.44 ± 0.20 M logEC50) or HNaC (-4.46 ± 0.50 M logEC50). Further, ascorbate, apocynin, and tempol administration each increased ACh-induced vasodilation during HNa only (Ringer's: 38.9 ± 2.4; ascorbate: 48.0 ± 2.5; tempol: 45.3 ± 2.7; apocynin: 48.5 ± 2.6% maximum cutaneous vascular conductance; all P values < 0.01).

CONCLUSIONS

These results demonstrate that incorporating dairy cheese into a high-sodium diet preserves EDD by decreasing the concentration of superoxide radicals. Consuming sodium in cheese, rather than in nondairy sources of sodium, may be an effective strategy to reduce cardiovascular disease risk in salt-insensitive, older adults. This trial was registered at clinicaltrials.gov as NCT03376555.

Mechanotransduction, immunoregulation, and metabolic functions of CD31 in cardiovascular pathophysiology

Biomechanical changes in the heart and vessels drive rapid and dynamic regulation of blood flow, a vital process for meeting the changing metabolic needs of the peripheral tissues at any given point in time. The fluid movement of the blood exerts haemodynamic stress upon the solid elements of the cardiovascular system: the heart, vessels, and cellular components of the blood. Cardiovascular diseases can lead to prolonged mechanical stress, such as cardiac remodelling during heart failure or vascular stiffening in atherosclerosis. This can lead to a significantly reduced or increasingly turbulent blood supply, inducing a shift in cellular metabolism that, amongst other effects, can trigger the release of reactive oxygen species and initiate a self-perpetuating cycle of inflammation and oxidative stress. CD31 is the most abundant constitutive co-signalling receptor glycoprotein on endothelial cells, which line the cardiovascular system and form the first-line of cellular contact with the blood. By associating with most endothelial receptors involved in mechanosensing, CD31 regulates the response to biomechanical stimuli. In addition, by relocating in the lipid rafts of endothelial cells as well as of cells stably interacting with the endothelium, including leucocytes and platelets, CD31–CD31 trans-homophilic engagement guides and restrains platelet and immune cell accumulation and activation and at sites of damage. In this way, CD31 is at the centre of mediating mechanical, metabolic, and immunological changes within the circulation and provides a single target that may have pleiotropic beneficial effects.

Reactive species-induced microvascular dysfunction in ischemia/reperfusion

Vascular endothelial cells line the inner surface of the entire cardiovascular system as a single layer and are involved in an impressive array of functions, ranging from the regulation of vascular tone in resistance arteries and arterioles, modulation of microvascular barrier function in capillaries and postcapillary venules, and control of proinflammatory and prothrombotic processes, which occur in all segments of the vascular tree but can be especially prominent in postcapillary venules. When tissues are subjected to ischemia/reperfusion (I/R), the endothelium of resistance arteries and arterioles, capillaries, and postcapillary venules become dysfunctional, resulting in impaired endothelium-dependent vasodilator and enhanced endothelium-dependent vasoconstrictor responses along with increased vulnerability to thrombus formation, enhanced fluid filtration and protein extravasation, and increased blood-to-interstitium trafficking of leukocytes in these functionally distinct segments of the microcirculation. The number of capillaries open to flow upon reperfusion also declines as a result of I/R, which impairs nutritive perfusion. All of these pathologic microvascular events involve the formation of reactive species (RS) derived from molecular oxygen and/or nitric oxide. In addition to these effects, I/R-induced RS activate NLRP3 inflammasomes, alter connexin/pannexin signaling, provoke mitochondrial fission, and cause release of microvesicles in endothelial cells, resulting in deranged function in arterioles, capillaries, and venules. It is now apparent that this microvascular dysfunction is an important determinant of the severity of injury sustained by parenchymal cells in ischemic tissues, as well as being predictive of clinical outcome after reperfusion therapy. On the other hand, RS production at signaling levels promotes ischemic angiogenesis, mediates flow-induced dilation in patients with coronary artery disease, and instigates the activation of cell survival programs by conditioning stimuli that render tissues resistant to the deleterious effects of prolonged I/R. These topics will be reviewed in this article.

Agonism for the bile acid receptor GPBAR1 reverses liver and vascular damage in a mouse model of steatohepatitis

Nonalcoholic steatohepatitis (NASH) is associated with an increased risk of developing cardiovascular complications and mortality, suggesting that treatment of NASH might benefit from combined approaches that target the liver and the cardiovascular components of NASH. Using genetic and pharmacologic approaches, we show that G protein-coupled bile acid-activated receptor 1 (GPBAR1) agonism reverses liver and vascular damage in mouse models of NASH. NASH is associated with accelerated vascular inflammation representing an independent risk factor for development of cardiovascular diseases and cardiovascular-related mortality. GPBAR1, also known as TGR5, is a G protein-coupled receptor for secondary bile acids that reduces inflammation and promotes energy expenditure. Using genetic and pharmacologic approaches, we investigated whether GPBAR1 agonism by 6β-ethyl-3α,7β-dihydroxy-5β-cholan-24-ol (BAR501) reverses liver and vascular damage induced by exposure to a diet enriched in fat and fructose (HFD-F). Treating HFD-F mice with BAR501 reversed liver injury and promoted the browning of white adipose tissue in a Gpbar1-dependent manner. Feeding HFD-F resulted in vascular damage, as shown by the increased aorta intima-media thickness and increased expression of inflammatory genes (IL-6,TNF-α, iNOS, and F4/80) and adhesion molecules (VCAM, intercellular adhesion molecule-1, and endothelial selectin) in the aorta, while reducing the expression of genes involved in NO and hydrogen sulfide generation, severely altering vasomotor activities of aortic rings in an ex vivo assay. BAR501 reversed this pattern in a Gpbar1-dependent manner, highlighting a potential role for GPBAR1 agonism in treating the liver and vascular component of NASH.-Carino, A., Marchianò, S., Biagioli, M., Bucci, M., Vellecco, V., Brancaleone, V., Fiorucci, C., Zampella, A., Monti, M. C., Distrutti, E., Fiorucci, S. Agonism for the bile acid receptor GPBAR1 reverses liver and vascular damage in a mouse model of steatohepatitis.