Salt Sensitivity of Angiogenesis Inhibition-Induced Blood Pressure Rise: Role of Interstitial Sodium Accumulation?

Sodium, Interstitium, Lymphatics and Hypertension-A Tale of Hydraulics

Blood pressure is regulated by vascular resistance and intravascular volume. However, exchanges of electrolytes and water between intra and extracellular spaces and filtration of fluid and solutes in the capillary beds blur the separation between intravascular, interstitial and intracellular compartments. Contemporary paradigms of microvascular exchange posit filtration of fluids and solutes along the whole capillary bed and a prominent role of lymphatic vessels, rather than its venous end, for their reabsorption. In the last decade, these concepts have stimulated greater interest in and better understanding of the lymphatic system as one of the master regulators of interstitial volume homeostasis. Here, we describe the anatomy and function of the lymphatic system and focus on its plasticity in relation to the accumulation of interstitial sodium in hypertension. The pathophysiological relevance of the lymphatic system is exemplified in the kidneys, which are crucially involved in the control of blood pressure, but also hypertension-mediated cardiac damage. Preclinical modulation of the lymphatic reserve for tissue drainage has demonstrated promise, but has also generated conflicting results. A better understanding of the hydraulic element of hypertension and the role of lymphatics in maintaining fluid balance can open new approaches to prevent and treat hypertension and its consequences, such as heart failure.

Management of hypertension in patients with cancer: challenges and considerations

The survival rates of many cancers have significantly improved due to recent advancements in cancer screening and therapeutics. Although better cancer outcomes are encouraging, additional health challenges have surfaced, the utmost of which is the burden imposed by various cardiovascular and renal toxicities of anticancer therapies. To improve the overall outcome of patients with cancer, it is essential to understand and manage these treatment-related adverse effects. The cardiovascular side effects of antineoplastic therapies are well-known and include left ventricular dysfunction, heart failure, myocardial ischaemia, QT prolongation, arrhythmia and hypertension. Among these, hypertension is the most common complication, prevalent in about 40% of all cancer patients, yet frequently overlooked and undertreated. This review explores the intricate connection between cancer and hypertension and provides distinct approaches to diagnosing, monitoring and managing hypertension in patients with cancer. We also outline the challenges and considerations that are relevant to the care of patients receiving anticancer drugs with prohypertensive potential.

Role of Lymphangiogenesis in Cardiac Repair and Regeneration

This article highlights the importance of the structure and function of cardiac lymphatics in cardiovascular diseases and the therapeutic potential of cardiac lymphangiogenesis. Specifically, we explore the innate lymphangiogenic response to damaged cardiac tissue or cardiac injury, derive key findings from regenerative models demonstrating how robust lymphangiogenic responses can be supported to improve cardiac function, and introduce an approach to imaging the structure and function of cardiac lymphatics.

Hypertensive heart disease: risk factors, complications and mechanisms

Hypertensive heart disease constitutes functional and structural dysfunction and pathogenesis occurring primarily in the left ventricle, the left atrium and the coronary arteries due to chronic uncontrolled hypertension. Hypertensive heart disease is underreported and the mechanisms underlying its correlates and complications are not well elaborated. In this review, we summarize the current understanding of hypertensive heart disease, we discuss in detail the mechanisms associated with development and complications of hypertensive heart disease especially left ventricular hypertrophy, atrial fibrillation, heart failure and coronary artery disease. We also briefly highlight the role of dietary salt, immunity and genetic predisposition in hypertensive heart disease pathogenesis.

The Role of Nitric Oxide in the Micro- and Macrovascular Response to a 7-Day High-Salt Diet in Healthy Individuals

This study aimed to investigate the specific role of nitric oxide (NO) in micro- and macrovascular response to a 7-day high-salt (HS) diet, specifically by measuring skin microvascular local thermal hyperemia and the flow-mediated dilation of the brachial artery, as well as serum NO and three NO synthase enzyme (NOS) isoform concentrations in healthy individuals. It also aimed to examine the concept of non-osmotic sodium storage in the skin following the HS diet by measuring body fluid status and systemic hemodynamic responses, as well as serum vascular endothelial growth factor C (VEGF-C) concentration. Forty-six young, healthy individuals completed a 7-day low-salt diet, followed by a 7-day HS diet protocol. The 7-day HS diet resulted in impaired NO-mediated endothelial vasodilation in peripheral microcirculation and conduit arteries, in increased eNOS, decreased nNOS, and unchanged iNOS concentration and NO serum level. The HS diet did not change the volume of interstitial fluid, the systemic vascular resistance or the VEGF-C serum level. These results indicate that the 7-day HS-diet induces systemic impairment of NO-mediated endothelial vasodilation, while dissociation in the eNOS and nNOS response indicates complex adaptation of main NO-generating enzyme isoforms to HS intake in healthy individuals. Our results failed to support the concept of non-osmotic sodium storage.

Skin regulation of salt and blood pressure and potential clinical implications

Sodium chloride, as salt, gives rise to hypertension. Nevertheless, individual susceptibility to the ramifications of sodium chloride is heterogeneous. The conventional nephron-centric regulation of sodium with neurohormonal inputs and responses is now expanded to include an intricate extrarenal pathway including the endothelium, skin, lymphatics, and immune cells. An overabundance of sodium is buffered and regulated by the skin interstitium. Excess sodium passes through (and damages) the vascular endothelium and can be dynamically stored in the skin, modulated by skin immune cells and lymphatics. This excess interstitially stored sodium is implicated in hypertension, cardiovascular dysfunction, metabolic disruption, and inflammatory dysregulation. This extrarenal pathway of regulating sodium represents a novel target for better blood pressure management, rebalancing disturbed inflammation, and hence addressing cardiovascular and metabolic disease.

Dietary sodium restriction prevents vascular endothelial growth factor inhibitor-induced hypertension

BACKGROUND

Vascular endothelial growth factor inhibitors (VEGFIs) are effective anticancer agents which often induce hypertension. VEGFI-induced hypertension is sodium-sensitive in animal studies. Therefore, the efficacy of dietary sodium restriction (DSR) to prevent VEGFI-induced hypertension in cancer patients was studied.

METHODS

Cancer patients with VEGFI-induced hypertension (day mean >135/85 mmHg or a rise in systolic and/or diastolic BP ≥ 20 mmHg) were treated with DSR (aiming at <4 g salt/day). The primary endpoint was the difference in daytime mean arterial blood pressure (MAP) increase between the treatment cycle with and without DSR.

RESULTS

During the first VEGFI treatment cycle without DSR, mean daytime MAP increased from 95 to 110 mmHg. During the subsequent treatment cycle with DSR, mean daytime MAP increased from 94 to 102 mmHg. Therefore, DSR attenuated the increase in mean daytime MAP by 7 mmHg (95% CI 1.3-12.0, P = 0.009). DSR prevented the rise in the endothelin-1/renin ratio that normally accompanies VEGFI-induced hypertension (P = 0.020) and prevented the onset of proteinuria: 0.15 (0.10-0.25) g/24 h with DSR versus 0.19 (0.11-0.32) g/24 h without DSR; P = 0.005.

DISCUSSION

DSR significantly attenuated VEGFI induced BP rise and proteinuria and thus is an effective non-pharmacological intervention.

Mechanisms of sodium-mediated injury in cardiovascular disease: old play, new scripts

There is a strong association between salt intake and cardiovascular diseases, particularly hypertension, on the population level. The mechanisms that explain this association remain incompletely understood and appear to extend beyond blood pressure. In this review, we describe some of the 'novel' roles of Na⁺ in cardiovascular health and disease: energetic implications of sodium handling in the kidneys; local accumulation in tissue; fluid dynamics; and the role of the microvasculature, with particular focus on the lymphatic system. We describe the interplay between these factors that involves body composition, metabolic signatures, inflammation and composition of the extracellular and intracellular milieus.

Apatinib Through Activating the RhoA/ROCK Signaling Pathway to Cause Dysfunction of Vascular Smooth Muscle Cells

Vascular smooth muscle cells (VSMCs) are associated with differentiated, organized, and contractile phenotype under the effect of various types of physiological conditions those are associated with migratory, proliferative, and synthetic phenotype under the effect of various types of stimuli, which dysfunction drives many cardiovascular diseases. Abnormal cell proliferation and invasion of VSMCs are among the primary causes of hypertension. Apatinib is a small-molecule tyrosine kinase inhibitor (TKI) that highly selectively binds to and strongly inhibits VEGFR-2. Previous studies have confirmed that the TKIs can raise blood pressure through RhoA/ROCK pathway. LARG is a key gene in the RhoA/ROCK pathway and plays a critical role in the continuous vasoconstriction function because it regulates part of signal transduction in VSMCs. In this study, an in vitro experiment was conducted to observe that apatinib caused dysfunction of MOVAS cells through the RhoA/ROCK signalling pathway and Y27632, a nonspecific ROCK inhibitor, and knockout of LARG gene can improve the proliferation, antiapoptosis, oxidative stress, and mitochondrial autophagy of apatinib-induced MOVAS cells. These findings suggest that activation of the RhoA/ROCK signalling pathway could be the underlying mechanism of apatinib-induced dysfunction of MOVAS cells, while ROCK inhibitor and knockout of LARG gene have potential therapeutic value.

Research on the Mechanism and Prevention of Hypertension Caused by Apatinib Through the RhoA/ROCK Signaling Pathway in a Mouse Model of Gastric Cancer

Hypertension is one of the main adverse effects of antiangiogenic tumor drugs and thus limits their application. The mechanism of hypertension caused by tyrosine kinase inhibitors (TKIs) targeting vascular endothelial growth factors is mainly related to inhibition of the nitric oxide (NO) pathway and activation of the endothelin pathway, as well as vascular rarefaction and increased salt sensitivity; consequently, prevention and treatment differ for this type of hypertension compared with primary hypertension. Apatinib is a highly selective TKI approved in China for the treatment of advanced or metastatic gastric cancer. The RhoA/ROCK pathway is involved in the pathogenesis of hypertension and mediates smooth muscle contraction, eNOS inhibition, endothelial dysfunction and vascular remodeling. In this study, in vivo experiments were performed to explore whether the RhoA/ROCK signaling pathway is part of a possible mechanism of apatinib in the treatment of gastric cancer-induced hypertension and the impairment of vascular remodeling and left ventricular function. Y27632, a selective small inhibitor of both ROCK1 and ROCK2, was combined with apatinib, and its efficacy was evaluated, wherein it can reduce hypertension induced by apatinib treatment in gastric cancer mice and weaken the activation of the RhoA/ROCK pathway by apatinib and a high-salt diet (HSD). Furthermore, Y-27632 improved aortic remodeling, fibrosis, endothelial dysfunction, superior mesenteric artery endothelial injury, left ventricular dysfunction and cardiac fibrosis in mice by weakening the activation of the RhoA/ROCK pathway. The expression of RhoA/ROCK pathway-related proteins and relative mRNA levels in mice after apatinib intervention were analyzed by various methods, and blood pressure and cardiac function indexes were compared. Endothelial and cardiac function and collagen levels in the aorta were also measured to assess vascular and cardiac fibrosis and to provide a basis for the prevention and treatment of this type of hypertension.

Tissue Sodium in Patients With Early Stage Hypertension: A Randomized Controlled Trial

Background

Sodium (Na⁺) stored in skin and muscle tissue is associated with essential hypertension. Sodium magnetic resonance imaging is a validated method of quantifying tissue stores of Na⁺. In this study, we evaluated tissue Na⁺ in patients with elevated blood pressure or stage I hypertension in response to diuretic therapy or low Na⁺ diet.

Methods and Results

In a double‐blinded, placebo‐controlled trial, patients with systolic blood pressure 120 to 139 mm Hg were randomized to low sodium diet (<2 g of sodium), chlorthalidone, spironolactone, or placebo for 8 weeks. Muscle and skin Na⁺ using sodium magnetic resonance imaging and pulse wave velocity were assessed at the beginning and end of the study. Ninety‐eight patients were enrolled to undergo baseline measurements and 54 completed randomization. Median baseline muscle and skin Na⁺ in 98 patients were 16.4 mmol/L (14.9, 18.9) and 13.1 mmol/L (11.1, 16.1), respectively. After 8 weeks, muscle Na⁺ increased in the diet and chlorthalidone arms compared with placebo. Skin sodium was decreased only in the diet arm compared with placebo. These associations remained significant after adjustment for age, sex, body mass index, systolic blood pressure, and urinary sodium. No changes were observed in pulse wave velocity among the different groups when compared with placebo.

Conclusions

Diuretic therapy for 8 weeks did not decrease muscle or skin sodium or improve pulse wave velocity in patients with elevated blood pressure or stage I hypertension.

Registration

URL: https://www.clinicaltrials.gov; Unique identifier: NCT02236520.

Tissue Sodium Accumulation: Pathophysiology and Clinical Implications

Excessive sodium intake has been well established as a risk factor for the development and progression of cardiovascular and renal diseases. Its adverse effects are achieved by renal sodium retention and related volume expansion and by inducing low-grade inflammation and oxidative stress (OS) in the target tissues. This review presents the recent concept of nonosmotic sodium storage in the skin interstitium, the subsequent dissociation of sodium and volume homeostasis, and the cellular response to the increased tissue sodium concentration. Furthermore, data are shown on the sodium barrier and buffering potential of the endothelial glycocalyx that may protect the functional integrity of the endothelium when it is challenged by an increased sodium load. Finally, examples will be given of the involvement of oxygen free radicals (OFR) in sodium-induced tissue damage, and some clinical entities will be mentioned that are causally associated with sodium/volume retention and OS.

Rho kinase inhibition ameliorates vascular remodeling and blood pressure elevations in a rat model of apatinib-induced hypertension

OBJECTIVES

Hypertension is one of the major adverse effects of tyrosine kinase inhibitors (TKIs) targeting vascular endothelial growth factors. However, the mechanism underlying TKIs-induced hypertension remains unclear. Here, we explored the role of the RhoA/Rho kinase (ROCK) signaling pathway in elevation of blood pressure (BP) induced by apatinib, a selective TKI approved in China for treatment of advanced or metastatic gastric cancer. A nonspecific ROCK inhibitor, Y27632, was then combined with apatinib and its efficacy in alleviating apatinib-induced hypertension was evaluated.

METHODS

Normotensive female Wistar-Kyoto rats were exposed to two different doses of apatinib, or apatinib combined with Y27632, or vehicle for 2 weeks. BP was monitored by a tail-cuff plethysmography system. The mRNA levels and protein expression in the RhoA/ROCK pathway were determined, and vascular remodeling assessed.

RESULTS

Administration of either a high or low dose of apatinib was associated with a rapid rise in BP, reaching a plateau after 12 days. Apatinib treatment mediated upregulation of RhoA and ROCK II in the mid-aorta, more significant in the high-dose group. However, ROCK I expression showed no statistically significant differences. Furthermore, the mRNA level of GRAF3 decreased dose-dependently. Apatinib administration was also associated with decreased levels of MLCP, and elevated endothelin-1 (ET-1) and collagen I, which were accompanied with increased mid-aortic media. However, treatment with Y27632 attenuated the above changes.

CONCLUSION

These findings suggest that activation of the RhoA/ROCK signaling pathway could be the underlying mechanism of apatinib-induced hypertension, while ROCK inhibitor have potential therapeutic value.

Hypertension Induced by Combination Therapy of Cancer: A Systematic Review and Meta-Analysis of Global Clinical Trials

Background: Nowadays, due to the limitation of single therapy, combination therapy for cancer treatments has become important strategy. With the advancement of research on cardiotoxicities induced by anti-cancer treatment, among which cancer treatment-induced hypertension is the most frequent case. However, due to the small sample size and the absence of comparison (single-arm study alone), these studies have limitations to produce a feasible conclusion. Therefore, it is necessary to carry out a meta-analysis focusing on hypertension caused by cancer combination therapy.

Methods: We systematically searched PubMed, Embase, Cochrane Library, Web of Science, and CNKI, from database inception to November 31, 2020, with randomized controlled trials (RCTs) associated with hypertension induced by cancer combination drugs. The main endpoint of which was to assess the difference in the incidence of hypertension in cancer patients with monotherapy or combination therapy. We calculated the corresponding 95% confidence interval (95% CIs) according to the random effect model and evaluated the heterogeneity between different groups.

Results: According to the preset specific inclusion and exclusion criteria, a total of 23 eligible RCTs have been included in the present meta-analysis, including 6,241 patients (Among them, 2872 patients were the control group and 3369 patients were the experimental group). The results showed that cancer patients with combination therapy led to a higher risk of hypertension (All-grade: RR 2.85, 95% CI 2.52∼3.22; 1∼2 grade: RR 2.43, 95% CI 2.10∼2.81; 3∼4 grade: RR 4.37, 95% CI 3.33∼5.72). Furthermore, compared with the control group who received or did not receive a placebo, there was a higher risk of grade 3-4 hypertension caused by cancer combination treatment.

Conclusion: The present meta-analysis carries out a comprehensive analysis on the risk of patients suffering from hypertension in the process of multiple cancer combination therapies. Findings in our study support that the risk of hypertension may increase significantly in cancer patients with multiple cancer combination therapies. The outcomes of this meta-analysis may provide a reference value for clinical practice and may supply insights in reducing the incidence of hypertension caused by cancer combined treatment.

Cardiovascular toxicity of angiogenesis inhibitors and immune checkpoint inhibitors: synergistic anti-tumour effects at the cost of increased cardiovascular risk?

In the past two decades, treatment outcomes for a wide range of malignancies have improved remarkably due to the development of novel anti-cancer therapies, including vascular endothelial growth factor inhibitors (VEGFIs) and immune checkpoint inhibitors (ICIs). Despite their unprecedented anti-tumour effects, it is becoming increasingly clear that both types of agents are associated with specific cardiovascular toxicity, including hypertension, congestive heart failure, myocarditis and acceleration of atherosclerosis. Currently, VEGFI and ICI combination therapy is recommended for the treatment of advanced renal cell carcinoma (RCC) and has shown promising treatment efficacy in other tumour types as well. Consequently, VEGFI and ICI combination therapy will most likely become an important therapeutic strategy for various malignancies. However, this combinatory approach is expected to be accompanied by a substantial increase in cardiovascular risk, as both types of agents could act synergistically to induce cardiovascular sequelae. Therefore, a comprehensive baseline assessment and adequate monitoring by specialised cardio-oncology teams is essential in case these agents are used in combination, particularly in high-risk patients. This review summarises the mechanisms of action and treatment indications for currently registered VEGFIs and ICIs, and discusses their main vascular and cardiac toxicity. Subsequently, we provide the biological rationales for the observed promising synergistic anti-tumour effects of combined VEGFI/ICI administration. Lastly, we speculate on the increased risk for cardiovascular toxicity in case these agents are used in combination and its implications and future directions for the clinical situation.

Hypertension and Prohypertensive Antineoplastic Therapies in Cancer Patients

The development of a wide range of novel antineoplastic therapies has improved the prognosis for patients with a wide range of malignancies, which has increased the number of cancer survivors substantially. Despite the oncological benefit, cancer survivors are exposed to short- and long-term adverse cardiovascular toxicities associated with anticancer therapies. Systemic hypertension, the most common comorbidity among cancer patients, is a major contributor to the increased risk for developing these adverse cardiovascular events. Cancer and hypertension have common risk factors, have overlapping pathophysiological mechanisms and hypertension may also be a risk factor for some tumor types. Many cancer therapies have prohypertensive effects. Although some of the mechanisms by which these antineoplastic agents lead to hypertension have been characterized, further preclinical and clinical studies are required to investigate the exact pathophysiology and the optimal management of hypertension associated with anticancer therapy. In this way, monitoring and management of hypertension before, during, and after cancer treatment can be improved to minimize cardiovascular risks. This is vital to optimize cardiovascular health in patients with cancer and survivors, and to ensure that advances in terms of cancer survivorship do not come at the expense of increased cardiovascular toxicities.

New Concept of Onco-Hypertension and Future Perspectives

Owing to aging populations, the prevalence of hypertension and associated cardiovascular events has been increasing worldwide. The morbidity and mortality due to cancer have also been increasing with aging populations. Several small-molecule inhibitors have been used in cancer therapy, which have a positive impact on the prognosis and survival of patients with cancer. Consequently, the number of cancer survivors with hypertension has been rapidly increasing. Anticancer therapy, including vascular endothelial growth factor inhibitors, increases blood pressure. However, both clinical and laboratory evidence are lacking regarding optimal blood pressure control in patients with hypertension with cancer. Here, we propose the concept of onco-hypertension, which is an evolving subspecialty focused on the complex pathophysiology of hypertension and cancer. In this review, we highlight blood pressure changes in cancer, hypertension induced by anticancer therapy, and optimal blood pressure management in patients with hypertension with cancer. In addition, we discuss needed studies to further establish this new onco-hypertension concept.

A Modern View of the Interstitial Space in Health and Disease

Increases in the volume of the interstitial space are readily recognized clinically as interstitial edema formation in the loose connective tissue of skin, mucosa, and lung. However, the contents and the hydrostatic pressure of this interstitial fluid can be very difficult to determine even in experimental settings. These difficulties have long obscured what we are beginning to appreciate is a dynamic milieu that is subject to both intrinsic and extrinsic regulation. This review examines current concepts regarding regulation of interstitial volume, pressure, and flow and utilizes that background to address three major topics of interest that impact IV fluid administration. The first of these started with the discovery that excess dietary salt can be stored non-osmotically in the interstitial space with minimal impact on vascular volume and pressures. This led to the hypothesis that, along with the kidney, the interstitial space plays an active role in the long-term regulation of blood pressure. Second, it now appears that hypovolemic shock leads to systemic inflammatory response syndrome principally through the entry of digestive enzymes into the intestinal interstitial space and the subsequent progression of enzymes and inflammatory agents through the mesenteric lymphatic system to the general circulation. Lastly, current evidence strongly supports the non-intuitive view that the primary factor leading to inflammatory edema formation is a decrease in interstitial hydrostatic pressure that dramatically increases microvascular filtration.

Molecular Mechanisms of SGLT2 Inhibitor on Cardiorenal Protection

The development of sodium-glucose transporter 2 inhibitor (SGLT2i) broadens the therapeutic strategies in treating diabetes mellitus. By inhibiting sodium and glucose reabsorption from the proximal tubules, the improvement in insulin resistance and natriuresis improved the cardiovascular mortality in diabetes mellitus (DM) patients. It has been known that SGLT2i also provided renoprotection by lowering the intraglomerular hypertension by modulating the pre- and post- glomerular vascular tone. The application of SGLT2i also provided metabolic and hemodynamic benefits in molecular aspects. The recent DAPA-CKD trial and EMPEROR-Reduced trial provided clinical evidence of renal and cardiac protection, even in non-DM patients. Therefore, the aim of the review is to clarify the hemodynamic and metabolic modulation of SGLT2i from the molecular mechanism.

Vascular Cardio-Oncology: Vascular Endothelial Growth Factor inhibitors and hypertension

Since the formation of new blood vessels is essential for tumour growth and metastatic spread, inhibition of angiogenesis by targeting the vascular endothelial growth factor (VEGF) pathway is an effective strategy for various types of cancer, most importantly renal cell carcinoma, thyroid cancer, and hepatocellular carcinoma. However, VEGF inhibitors have serious side effects, most importantly hypertension and nephropathy. In case of fulminant hypertension, this may only be handled by lowering the dosage since the blood pressure rise is proportional to the amount of VEGF inhibition. These effects pathophysiologically and clinically resemble the most severe complication of pregnancy, preeclampsia, in which case an insufficient placenta leads to a rise in sFlt-1 levels causing a decrease in VEGF availability. Due to this overlap, studies in preeclampsia may provide important information for VEGF inhibitor-induced toxicity and vice versa. In both VEGF inhibitor-induced toxicity and preeclampsia, endothelin (ET)-1 appears to be a pivotal player. In this review, after briefly summarizing the anticancer effects, we discuss the mechanisms that potentially underlie the unwanted effects of VEGF inhibitors, focusing on ET-1, nitric oxide and oxidative stress, the renin-angiotensin-aldosterone system, and rarefaction. Given the salt sensitivity of this phenomenon, as well as the beneficial effects of aspirin in preeclampsia and cancer, we next provide novel treatment options for VEGF inhibitor-induced toxicity, including salt restriction, ET receptor blockade, and cyclo-oxygenase inhibition, in addition to classical antihypertensive and renoprotective drugs. We conclude with the recommendation of therapeutic drug monitoring to improve patient outcome.

DMOG, a Prolyl Hydroxylase Inhibitor, Increases Hemoglobin Levels without Exacerbating Hypertension and Renal Injury in Salt-Sensitive Hypertensive Rats

Prolyl hydroxylase (PHD) inhibitors are being developed as alternatives to recombinant human erythropoietin (rHuEPO) for the treatment of anemia in patients with chronic kidney disease (CKD). However, the effects of PHD inhibitors and rHuEPO on blood pressure and CKD in animal models susceptible to hypertension and nephropathy have not been studied. The present study compared the effects of dimethyloxaloylglycine (DMOG), a PHD inhibitor, and rHuEPO on the development of hypertension and renal injury in Dahl salt-sensitive rats fed an 8% salt diet for 3 weeks. DMOG and rHuEPO were equally effective at raising hemoglobin levels. Systolic blood pressure rose to a greater extent in rHuEPO-treated rats (267 ± 10 vs. 226 ± 4 mm Hg) than in rats given DMOG (189 ± 8 mm Hg). Urinary protein excretion increased to 568 ± 54 versus 353 ± 25 mg/day in rats treated with rHuEPO and vehicle; however, it only rose to 207 ± 21 mg/day in rats receiving DMOG. DMOG significantly attenuated the degree of glomerulosclerosis and renal interstitial fibrosis as compared with that in vehicle and rHuEPO-treated rats. This was associated with lower renal levels of monocyte chemoattractant protein-1 and interleukin-1β and increased vascular endothelial growth factor expression in cortex and medulla. These results indicate that DMOG and rHuEPO are equally effective in increasing hemoglobin levels in Dahl S rats; however, rHuEPO aggravates hypertension and renal injury, whereas DMOG has marked renoprotective effects. These results suggest that PHD inhibitors may have a therapeutic advantage for the treatment of anemia in CKD. SIGNIFICANCE STATEMENT: Prolyl hydroxylase (PHD) inhibitors are in phase 3 clinical trials as alternatives to recombinant human erythropoietin (rHuEPO) for the treatment of anemia in chronic kidney disease (CKD). The present study reveals that dimethyloxaloylglycine (DMOG), a PHD inhibitor, and rHuEPO are equally effective in increasing hemoglobin levels in Dahl S rats; however, rHuEPO aggravated hypertension and renal injury, whereas DMOG attenuated the development of hypertension and prevented renal injury. PHD inhibitors may provide a safer therapeutic option for the treatment of anemia in CKD.

The role of sodium in modulating immune cell function

Sodium intake is undoubtedly indispensable for normal body functions but can be detrimental when taken in excess of dietary requirements. The consequences of excessive salt intake are becoming increasingly clear as high salt consumption persists across the globe. Salt has long been suspected to promote the development of hypertension and cardiovascular diseases and is now also recognized as a potential modulator of inflammatory and autoimmune diseases through its direct and indirect effects on immune cells. The finding that, in addition to the kidneys, other organs such as the skin regulate sodium levels in the body prompted new hypotheses, including the concept that skin-resident macrophages might participate in tissue sodium regulation through their interactions with lymphatic vessels. Moreover, immune cells such as macrophages and different T cell subsets are found in sodium-rich interstitial microenvironments, where sodium levels modulate their function. Alterations to the intestinal bacterial community induced by excess dietary salt represent another relevant axis whereby salt indirectly modulates immune cell function. Depending on the inflammatory context, sodium might either contribute to protective immunity (for example, by enhancing host responses against cutaneous pathogens) or it might contribute to immune dysregulation and promote the development of cardiovascular and autoimmune diseases.

An update on the conquests and perspectives of cardio-oncology in the field of tumor angiogenesis-targeting TKI-based therapy

INTRODUCTION

The angiogenesis mechanism is considered a crucial point in neoplastic development. A growing number of multi-targeted tyrosine kinase inhibitors (TKI) has been developed and approved for cancer treatment during the last few years. Cardiac side effects still remain an issue to manage nowadays. These drugs mechanisms and toxicities have already been discussed, hence the authors will report updates on these already available drugs.

AREAS COVERED

This manuscript provides an updated review on the new mechanisms involved in angiogenesis and cardiotoxicity that are TKI-related. Here is reported an overview of the already available and the most recent TKIs under investigation in the oncology field. A literature review has been performed, focusing on the most relevant phase II and phase III trial results.

EXPERT OPINION

TKIs represent a new and important resource in the oncology field. Since the use and the number of VEGFR-TKI is constantly increasing, a specific focus on cardiotoxicity development and management appears as justified. Oncologists must record cardiovascular risk factors at baseline in order to stratify patients' risk before undergoing TKI-VEGFRs. A collaboration between oncologists and cardio-oncologists is strongly recommended to earlier manage cardiovascular events (i.e. arterial hypertension) that could interfere with oncological results.

Acute blood pressure elevation associated with biological therapies for cancer: a focus on VEGF signaling pathway inhibitors

INTRODUCTION

Treatment with biological agents interfering with mechanisms of angiogenesis, such as vascular endothelial growth factor (VEGF) signaling pathway (VSP) inhibitors, was associated with an enhanced risk of acute and severe blood pressure (BP) increase and development of hypertensive emergencies. Areas covered: The present article will review the scientific literature reporting hypertensive emergencies as a complication of biological treatment with VSP inhibitors. Hypertensive emergency is a life-threatening condition characterized by very high BP values (>180/110 mmHg) associated with acute organ damage. The exact mechanism of action is still incompletely clarified. Endothelial dysfunction following reduced bioavailability of nitric oxide has been hypothesized to play an important role in promoting hypertension and the occurrence of acute organ damage. Expert opinion: Prevention, prompt recognition and treatment of hypertensive emergencies associated with treatment with VSP-inhibitors are essential to reduce the risk of adverse events. Not infrequently, the occurrence of hypertensive emergency led to VSP treatment discontinuation, with potential negative consequences on patient overall survival. The present review aims at providing detailed knowledge for the clinician regarding this specific issue, which could be of high impact in usual clinical practice, given the increasing burden of indications to treatment with biological agents targeted to the VEGF pathway.

Renal Soluble Guanylate Cyclase Is Downregulated in Sunitinib-Induced Hypertension

Background

The tyrosine kinase inhibitor sunitinib causes hypertension associated with reduced nitric oxide (NO) availability, elevated renal vascular resistance, and decreased fractional sodium excretion. We tested whether (1) nitrate supplementation mitigates sunitinib‐induced hypertension and NO contributes less to renal vascular resistance as well as fractional sodium excretion regulation in sunitinib‐treated rats than in controls; and (2) renal soluble guanylate cyclase (sGC) is downregulated and sGC activation lowers arterial pressure in rats with sunitinib‐induced hypertension.

Methods and Results

Arterial pressure responses to nitrate supplementation and the effects of systemic and intrarenal NO synthase (NOS) inhibition on renal hemodynamics and fractional sodium excretion were assessed in sunitinib‐treated rats and controls. Renal NOS and sGC mRNA as well as protein abundances were determined by quantitative polymerase chain reaction and Western blot. The effect of the sGC activator cinaciguat on arterial pressure was investigated in sunitinib‐treated rats. Nitrate supplementation did not mitigate sunitinib‐induced hypertension. Endothelium‐dependent reductions in renal vascular resistance were similar in control and sunitinib‐treated animals without and with systemic NOS inhibition. Selective intrarenal NOS inhibition lowered renal medullary blood flow in control but not in sunitinib‐treated rats without significant effects on fractional sodium excretion. Renal cortical sGC mRNA and sGC α₁‐subunit protein abundance were less in sunitinib‐treated rats than in controls, and cinaciguat effectively lowered arterial pressure by 15‐20 mm Hg in sunitinib‐treated rats.

Conclusions

Renal cortical sGC is downregulated in the presence of intact endothelium‐dependent renal vascular resistance regulation in developing sunitinib‐induced hypertension. This suggests that sGC downregulation occurs outside the renal vasculature, increases renal sodium retention, and contributes to nitrate resistance of sunitinib‐induced hypertension.

High-Salt Diet Causes Expansion of the Lymphatic Network and Increased Lymph Flow in Skin and Muscle of Rats

Objective—

A commonly accepted pivotal mechanism in fluid volume and blood pressure regulation is the parallel relationship between body Na + and extracellular fluid content. Several recent studies have, however, shown that a considerable amount of Na + can be retained in skin without commensurate water retention. Here, we asked whether a salt accumulation shown to result in VEGF (vascular endothelial growth factor)-C secretion and lymphangiogenesis had any influence on lymphatic function.

Approach and Results—

By optical imaging of macromolecular tracer washout in skin, we found that salt accumulation resulted in an increase in lymph flow of 26% that was noticeable only after including an overnight recording period. Surprisingly, lymph flow in skeletal muscle recorded with a new positron emission tomography/computed tomography method was also increased after salt exposure. The transcapillary filtration was unaffected by the high-salt diet and deoxycorticosterone-salt treatment, suggesting that the capillary barrier was not influenced by the salt accumulation. A significant reduction in lymph flow after depletion of macrophages/monocytes by clodronate suggests these cells are involved in the observed lymph flow response, together with collecting vessels shown here to enhance their contraction frequency as a response to extracellular Na + .

Conclusions—

The observed changes in lymph flow suggest that the lymphatics may influence long-term regulation of tissue fluid balance during salt accumulation by contributing to fluid homeostasis in skin and muscle. Our studies identify lymph clearance as a potential disease-modifying factor that might be targeted in conditions characterized by salt accumulation like chronic kidney disease and salt-sensitive hypertension.

Inflammasome-Independent NALP3 Contributes to High-Salt Induced Endothelial Dysfunction

Backgrounds and Aims: Na⁺ is an important nutrient and its intake, mainly from salt (NaCl), is essential for normal physiological function. However, high salt intake may lead to vascular injury, independent of a rise in blood pressure (BP). Canonical NALP3 inflammasome activation is a caspase-1 medicated process, resulting in the secretion of IL-18 and IL-1β which lead to endothelial dysfunction. However, some researches uncovered a direct and inflammasome-independent role of NALP3 in renal injury. Thus, this study was designed to investigate the possible mechanisms of NALP3 in high salt induced endothelial dysfunction.

Methods and Results: Changes in endothelial function were measured by investigating mice (C57BL/6J, NALP3^-/- and wild-type, WT) fed with normal salt diet (NSD) or high salt diet (HSD) for 12W, and thoracic aortic rings from C57BL/6J mice cultured in high-salt medium. Changes of tube formation ability, intracellular reactive oxygen species (ROS), and NALP3 inflammasome expression were detected using mouse aortic endothelial cells (MAECs) cultured in high-salt medium. Consumption of HSD for 12W did not affect BP or body weight in C57BL/6J mice. Endothelium-dependent relaxation (EDR) decreased significantly in C57BL/6J mice fed with HSD for 12W, and in isolated thoracic aortic rings cultured in high-salt medium for 24 h. Results from the aortic ring assay also revealed that the angiogenic function of thoracic aortas was impaired by either consumption of HSD or exposure to high-salt medium. NALP3^-/- mice fed with HSD showed a relatively mild decrease in EDR function when compared with WT mice. Tube length of thoracic aortic rings from NALP3^-/- mice was longer than those from WT mice after receiving high-salt treatment. Inhibiting NALP3 with a NALP3 antagonist, small interfering (si) RNA experiments using si-NALP3, and decomposing ROS significantly improved tube formation ability in MAECs under high salt medium. NALP3 expression was increased in MAECs cultured with high salt treatment and inhibiting NALP3 reversed the down-regulation of p-eNOS induced by high salt in MAECs.

Conclusion: High salt intake impairs endothelial function, which is at least in part mediated by increasing NALP3 expression.

Management of VEGF-Targeted Therapy-Induced Hypertension

PURPOSE OF REVIEW

From a physiological point of view, VEGFs (vascular endothelial growth factors) and their receptors (VEGFR) play a critical role in vascular development angiogenesis, endothelial function, and vascular tone. On the pathological side, VEGF-VEGFR signaling may induce dysregulated angiogenesis, which contributes to the growth and to the spread of tumors, being essential for neoplastic proliferation and invasion.

RECENT FINDINGS

Pharmacological inhibition of VEGF-VEGFR is now a cornerstone in the treatment of many malignancies; however, treatment with VEGF inhibitors is commonly associated with an increase in blood pressure values. This side effect is strictly connected with the mechanism of action of these medications and might represent an index of therapy efficacy. The optimal management of this form of hypertension is, at present, not clear. Calcium channel blockers and renin-angiotensin system inhibitors probably represent the most appropriate classes of hypertensive dugs for the treatment of this condition; however, no conclusive data are presently available.

Novel SNPs of WNK1 and AKR1C3 are associated with preeclampsia

Preeclampsia is a hypertensive disorder of pregnancy and is one of the most common causes of poor perinatal outcomes. Preeclampsia increases the risk of hypertension in the future. Variants of WNK1 (lysine deficient protein kinase 1), ADRB2 (β2 adrenergic receptor), NEDD4L (ubiquitin-protein ligase NEDD4-like), KLK1 (kallikrein 1) contribute to hypertension, and AKR1C3 (aldo-keto reductase family1 member C3), is associated with preeclampsia. The association of single nucleotide polymorphisms (SNPs) in these five candidate preeclampsia susceptibility genes and the related traits in Chinese individuals were investigated. In this study, 13 SNPs of the five genes were genotyped in 276 preeclampsia patients and 229 age- and area-matched normal pregnancies in women of Chinese Northern Han origin. The 95% confidence interval (CI) and odds ratio (OR) were estimated by binary logistic regression. No obvious linkage disequilibrium or haplotypes were observed among these SNPs. Those with GG genotype and allele G of AKR1C3 (rs10508293) had a decreased risk of preeclampsia (adjusted OR = 3.011, 95% CI = 1.758-5.159, and adjusted OR = 1.745, 95% CI = 1.349-2.257, respectively). The AA genotype and allele A of WNK1 (rs1468326) were significantly associated with an increased risk in preeclampsia (adjusted OR = 2.307, 95% CI = 1.206-3.443, and adjusted OR = 1.663, 95% CI = 1.283-2.157, respectively). The findings indicate that the GG genotype of AKR1C3 rs10508293 is associated with decreased risk for preeclampsia and the AA genotype of WNK1 rs1468326 are related with an increased risk for preeclampsia.

The interstitium conducts extrarenal storage of sodium and represents a third compartment essential for extracellular volume and blood pressure homeostasis

The role of salt in the pathogenesis of arterial hypertension is not well understood. According to the current understanding, the central mechanism for blood pressure (BP) regulation relies on classical studies linking BP and Na⁺ balance, placing the kidney at the very centre of long-term BP regulation. To maintain BP homeostasis, the effective circulating fluid volume and thereby body Na⁺ content has to be maintained within very narrow limits. From recent work in humans and rats, the notion has emerged that Na⁺ could be stored somewhere in the body without commensurate water retention to buffer free extracellular Na⁺ and that previously unidentified extrarenal, tissue-specific regulatory mechanisms are operative regulating the release and storage of Na⁺ from a kidney-independent reservoir. Moreover, immune cells from the mononuclear phagocyte system not only function as local on-site sensors of interstitial electrolyte concentration, but also, together with lymphatics, act as systemic regulators of body fluid volume and BP. These studies have established new and unexpected targets in studies of BP control and thus the pathophysiology of hypertension: the interstitium/extracellular matrix of the skin, its inherent interstitial fluid and the lymphatic vasculature forming a vessel network in the interstitium. Aspects of the interstitium in relation to Na⁺ balance and hypertension are the focus of this review. Taken together, observations of salt storage in the skin to buffer free extracellular Na⁺ and macrophage modulation of the extracellular matrix and lymphatics suggest that electrolyte homeostasis in the body cannot be achieved by renal excretion alone, but also relies on extrarenal regulatory mechanisms.

Salt, Hypertension, and Immunity

The link between inappropriate salt retention in the kidney and hypertension is well recognized. However, growing evidence suggests that the immune system can play surprising roles in sodium homeostasis, such that the study of inflammatory cells and their secreted effectors has provided important insights into salt sensitivity. As part of the innate immune system, myeloid cells have diverse roles in blood pressure regulation, ranging from prohypertensive actions in the kidney, vasculature, and brain, to effects in the skin that attenuate blood pressure elevation. In parallel, T lymphocyte subsets, as key constituents of the adaptive immune compartment, have variable effects on renal sodium handling and the hypertensive response, accruing from the functions of the cytokines that they produce. Conversely, salt can directly modulate the phenotypes of myeloid and T cells, illustrating bidirectional regulatory mechanisms through which sodium and the immune system coordinately impact blood pressure. This review details the complex interplay between myeloid cells, T cells, and salt in the pathogenesis of essential hypertension.

Hemodynamics and Salt-and-Water Balance Link Sodium Storage and Vascular Dysfunction in Salt-Sensitive Subjects

We investigated 24-hour hemodynamic changes produced by salt loading and depletion in 8 salt-sensitive (SS) and 13 salt-resistant (SR) normotensive volunteers. After salt loading, mean arterial pressure was higher in SS (96.5±2.8) than in SR (84.2±2.7 mm Hg), P<0.01, owing to higher total peripheral resistance in SS (1791±148) than in SR (1549±66 dyn*cm(-5)*s), P=0.05, whereas cardiac output was not different between groups (SS 4.5±0.3 versus SR 4.4±0.2 L/min, not significant). Following salt depletion, cardiac output was equally reduced in both groups. Total peripheral resistance increased 24±6% (P<0.001) in SR, whose mean arterial pressure remained unchanged. In contrast, total peripheral resistance did not change in SS (1±6%, not significant). Thus, their mean arterial pressure was reduced, abolishing the mean arterial pressure difference between groups. SS had higher E/e' ratios than SR in both phases of the protocol. In these 21 subjects and in 32 hypertensive patients, Na(+) balance was similar in SR and SS during salt loading or depletion. However, SR did not gain weight during salt retention (-158±250 g), whereas SS did (819±204), commensurate to iso-osmolar water retention. During salt depletion, SR lost the expected amount of weight for iso-osmolar Na(+) excretion, whereas SS lost a greater amount that failed to fully correct the fluid retention from the previous day. We conclude that SS are unable to modulate total peripheral resistance in response to salt depletion, mirroring their inability to vasodilate in response to salt loading. We suggest that differences in water balance between SS and SR indicate differences in salt-and-water storage in the interstitial compartment that may relate to vascular dysfunction in SS.