Vaccines in the management of hypertension

Vaccines against components of the renin-angiotensin system

Even though effective drugs for treating hypertension are available, a great percentage of patients have inadequate control of their blood pressure. Unwanted side effects and inappropriate oral drug adherence are important factors that contribute to the global problem of uncontrolled hypertension. Vaccination could provide a revolutionary therapy with long-lasting effects, increasing patient compliance and therefore better control of high blood pressure. Nowadays, current immunization approaches against hypertension target renin, angiotensin I, angiotensin II, and angiotensin II type 1 receptor, key elements of the renin–angiotensin system. This article reviews the different vaccination attempts with proteins and peptides against the different molecules of the renin–angiotensin system in the last two decades, safety issues, and other novel prospects biomarkers in hypertension, and summarizes the potential of this immunomodulatory approach in clinical practice.

Antifibrotic Roles of RAAS Blockers: Update

The rennin-angiotensin-aldosterone system (RAAS) has been well documented in regulating blood pressure, fluid volume, and sodium balance. Overactivity of RAAS promotes both systemic and regional glomerular capillary hypertension, which could induce hemodynamic injury to the glomerulus, leading to kidney damage and renal fibrosis via profibrotic and proinflammatory pathway. Therefore, the use of RAAS inhibitors (i.e., ACEIs, ARBs, and MRAs) as the optional therapy has been demonstrated to prevent proteinuria, and kidney fibrosis and slow the decline of renal function effectively in the process of kidney disease during the last few decades. Recently, several new components of the RAAS have been discovered, including ACE2 and the corresponding ACE2/Ang (1-7)/Mas axis, which are also present in the kidney. Besides the classic RAAS inhibitors target the angiotensin-AT1-aldosterone axis, with the expanding knowledge about RAAS, a number of potential therapeutic targets in this system is emerging. Newer agents that are more specific are being developed. The present chapter outlines the insights of the RAAS agents (classic RAAS antagonists/the new RAAS drugs), and discusses its clinical application in the combat of renal fibrosis.

Therapeutic Vaccines for Hypertension: a New Option for Clinical Practice

PURPOSE OF REVIEW

Vaccines are commonly used as preventive methods, primarily against infectious diseases. The goal of our study is to develop the therapeutic vaccine for hypertension.

RECENT FINDINGS

We and others recently reported that an angiotensin II (AngII) vaccine for hypertension successfully attenuated elevated blood pressures in an animal model without any immunogenic side effects. In this system, an immunogenic molecule (i.e., KLH) with adjuvants provides an antigen that supports the activation of helper T cells. In addition, pretreatment with the AngII vaccine exerts neuroprotective effects in a cerebral ischemia model and cardioprotective effects in a myocardial infarction model. In the early phase of clinical trial, the administration of an AngII vaccine (AngQb-Cyt006) successfully decreased blood pressure in hypertensive patients with the increase of anti-AngII antibody titer. Increasing the effectiveness of drug adherence interventions in the clinical setting may have a large impact on the health of the population, which can be improved by using successful therapeutic vaccines. In this review, we describe the concept of therapeutic vaccines for hypertension and future directions for therapeutic vaccines.

Advances in understanding the renin-angiotensin-aldosterone system (RAAS) in blood pressure control and recent pivotal trials of RAAS blockade in heart failure and diabetic nephropathy

The renin-angiotensin-aldosterone system (RAAS) plays a fundamental role in the physiology of blood pressure control and the pathophysiology of hypertension (HTN) with effects on vascular tone, sodium retention, oxidative stress, fibrosis, sympathetic tone, and inflammation. Fortunately, RAAS blocking agents have been available to treat HTN since the 1970s and newer medications are being developed. In this review, we will (1) examine new anti-hypertensive medications affecting the RAAS, (2) evaluate recent studies that help provide a better understanding of which patients may be more likely to benefit from RAAS blockade, and (3) review three recent pivotal randomized trials that involve newer RAAS blocking agents and inform clinical practice.

Long-Term Reduction of High Blood Pressure by Angiotensin II DNA Vaccine in Spontaneously Hypertensive Rats

Recent research on vaccination has extended its scope from infectious diseases to chronic diseases, including Alzheimer disease, dyslipidemia, and hypertension. The aim of this study was to design DNA vaccines for high blood pressure and eventually develop human vaccine therapy to treat hypertension. Plasmid vector encoding hepatitis B core-angiotensin II (Ang II) fusion protein was injected into spontaneously hypertensive rats using needleless injection system. Anti-Ang II antibody was successfully produced in hepatitis B core-Ang II group, and antibody response against Ang II was sustained for at least 6 months. Systolic blood pressure was consistently lower in hepatitis B core-Ang II group after immunization, whereas blood pressure reduction was continued for at least 6 months. Perivascular fibrosis in heart tissue was also significantly decreased in hepatitis B core-Ang II group. Survival rate was significantly improved in hepatitis B core-Ang II group. This study demonstrated that Ang II DNA vaccine to spontaneously hypertensive rats significantly lowered high blood pressure for at least 6 months. In addition, Ang II DNA vaccines induced an adequate humoral immune response while avoiding the activation of self-reactive T cells, assessed by ELISPOT assay. Future development of DNA vaccine to treat hypertension may provide a new therapeutic option to treat hypertension.

Using viruses as nanomedicines

The field of nanomedicine involves the design and fabrication of novel nanocarriers for the intracellular delivery of therapeutic cargo or for use in molecular diagnostics. Although traditionally recognized for their ability to invade and infect host cells, viruses and bacteriophages have been engineered over the past decade as highly promising molecular platforms for the targeted delivery and treatment of many human diseases. Inherently biodegradable, the outer capsids of viruses are composed entirely of protein building blocks, which can be genetically or chemically engineered with molecular imaging reagents, targeting ligands and therapeutic molecules. While there are several examples of viruses as in vitro molecular cargo carriers, their potential for applications in nanomedicine has only recently emerged. Here we highlight recent developments towards the design and engineering of viruses for the treatment of cancer, bacterial infections and immune system-related diseases.

Antibodies in the pathogenesis of hypertension

It has long been known that circulating levels of IgG and IgM antibodies are elevated in patients with essential and pregnancy-related hypertension. Recent studies indicate these antibodies target, and in many cases activate, G-protein coupled receptors and ion channels. Prominent among these protein targets are AT₁ receptors, α₁-adrenoceptors, β₁-adrenoceptors, and L-type voltage operated Ca²⁺ channels, all of which are known to play key roles in the regulation of blood pressure through modulation of vascular tone, cardiac output, and/or Na⁺/water reabsorption in the kidneys. This suggests that elevated antibody production may be a causal mechanism in at least some cases of hypertension. In this brief review, we will further describe the protein targets of the antibodies that are elevated in individuals with essential and pregnancy-related hypertension and the likely pathophysiological consequences of antibody binding to these targets. We will speculate on the potential mechanisms that underlie elevated antibody levels in hypertensive individuals and, finally, we will outline the therapeutic opportunities that could arise with a better understanding of how and why antibodies are produced in hypertension.

Effects of angiotensin-converting enzyme inhibitory peptide LAP on vascular remodeling

The aim of this article is to study the efficiency of an angiotensin-converting enzyme (ACE)-inhibitory peptide LAP on the blood pressure (BP) and the vascular remodeling in spontaneously hypertensive rats (SHRs). Ten-week-old male SHRs were divided into four groups with 10 animals in each group and treated for 2 months: blank, pseudo-experimental (NS), enalapril (ENA), and LAP. The alterations of BP, plasma angiotensin II (AngII) levels, and morphological changes of left common carotid artery and the third level of superior mesenteric artery were investigated. After 2 weeks of treatment, LAP and ENA significantly decreased BP and the antihypertensive effects lasted till the end of experiment. After 2 months, LAP and ENA also significantly lowered plasma AngII levels. LAP and enalapril significantly lowered vascular medial thickness, media thickness/lumen diameter, medial cross-sectional area, and mean nuclear area of smooth muscle cells in left common carotid artery. When compared to the blank group, LAP and ENA significantly lowered the percentages of collagen fibers in the vascular area of left common carotid artery with 24.84 ± 0.53, 23.36 ± 0.99 versus 31.82 ± 0.57 (blank), respectively, and those of the third level of superior mesenteric artery with 15.82 ± 0.60, 15.15 ± 0.71 versus 23.42 ± 0.72, respectively. LAP had a beneficial effect on BP and vascular remodeling in SHRs. These findings suggest the potential therapeutic value of LAP in the treatment of hypertension.

The design of semi-synthetic and synthetic glycoconjugate vaccines

INTRODUCTION

Glycoconjugate vaccines are among the safest and most efficacious vaccines developed during the last 30 years. They are a potent tool for prevention of life-threatening bacterial infectious diseases like meningitis and pneumonia. The concept of hapten-carrier conjugation is now being extended to other disease areas.

AREAS COVERED

This is an overview of the history and current status of glycoconjugate vaccines. The authors discuss the approaches for their preparation and quality control as well as those variables which might affect their product profile. The authors also look at the potential to develop fully synthetic conjugate vaccines based on the progress of organic chemistry. Additionally, new applications of conjugate vaccines technology in the field of non-infectious diseases are discussed. Through this review, the reader will have an insight regarding the issues and complexities involved in the preparation and characterization of conjugate vaccines, the variables that might affect their immunogenicity and the potential for future applications.

EXPERT OPINION

The immunogenicity of weak T-independent antigens can be increased in quantity and quality by conjugation to protein carriers, which provide T-cell help. Glycoconjugate vaccines are among the safest and most efficacious vaccines developed so far. Various conjugation procedures and carrier proteins can be used. Many variables impact on the immunogenicity of conjugate vaccines and a tight control through physicochemical tests is important to ensure manufacturing and clinical consistency. New and challenging targets for conjugate vaccines are represented by cancer and other non-infectious diseases.

Local renin-angiotensin system and the brain--a continuous quest for knowledge

The ancient renin-angiotensin system (RAS) was discovered more than a hundred years ago by identifying the rate-limiting enzyme of the system and its relevance to blood pressure regulation. Forty years ago, Detlev Ganten et al. postulated the existence of a tissue RAS. In these forty years, he kept developing the knowledge of these systems either directly or by training or attracting the interest of many researchers. Through the present review, we try to highlight recent advancements that originated from the postulation of local brain RAS. Although a large amount of knowledge accumulated, this system continues to intrigue and stimulate the interest and imagination of many researchers.