Decrease in blood pressure and regression of cardiovascular complications by angiotensin II vaccine in mice

Unveiling novel molecules and therapeutic targets in hypertension - A narrative review

Hypertension is a prevalent non-communicable disease with serious cardiovascular complications, including heart failure, myocardial infarction, and stroke, often resulting from uncontrolled hypertension. While current treatments primarily target the renin-angiotensin-aldosterone pathway, the therapeutic response remains modest in many patients, with some developing resistant hypertension. Newer therapeutic approaches aim to address hypertension from various aspects beyond conventional drugs, including targeting central nervous system pathways, inflammatory pathways, vascular smooth muscle function, and baroreceptors. Despite these advancements, each therapy faces unique clinical and mechanistic challenges that influence its clinical translatability and long-term viability. This review explores the mechanisms of novel molecules in preclinical and clinical development, highlights potential therapeutic targets, and discusses the challenges and ethical considerations related to hypertension therapeutics and their development.

PCPE-1, a brown adipose tissue-derived cytokine, promotes obesity-induced liver fibrosis

Metabolic dysfunction-associated steatohepatitis (MASH, previously termed non-alcoholic steatohepatitis (NASH)), is a major complication of obesity that promotes fatty liver disease. MASH is characterized by progressive tissue fibrosis and sterile liver inflammation that can lead to liver cirrhosis, cancer, and death. The molecular mechanisms of fibrosis in MASH and its systemic control remain poorly understood. Here, we identified the secreted-type pro-fibrotic protein, procollagen C-endopeptidase enhancer-1 (PCPE-1), as a brown adipose tissue (BAT)-derived adipokine that promotes liver fibrosis in a murine obesity-induced MASH model. BAT-specific or systemic PCPE-1 depletion in mice ameliorated liver fibrosis, whereas, PCPE-1 gain of function in BAT enhanced hepatic fibrosis. High-calorie diet-induced ER stress increased PCPE-1 production in BAT through the activation of IRE-1/JNK/c-Fos/c-Jun signaling. Circulating PCPE-1 levels are increased in the plasma of MASH patients, suggesting a therapeutic possibility. In sum, our results uncover PCPE-1 as a novel systemic control factor of liver fibrosis.

Therapeutic Vaccines and Nucleic Acid Drugs for Cardiovascular Disease

To combat the spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), novel vaccine modalities, such as messenger RNA vaccines, were rapidly developed and have shown high efficacy. This new vaccine technology, underpinned by intensive immunological analysis, is now being applied to the production of other vaccines. For over 10 years, we have been developing therapeutic vaccines for non-infectious diseases. The epitope vaccine approach, which combines a B-cell epitope with exogenous T-cell epitopes presented through major histocompatibility complex molecules, has been proposed to induce antibody production. This vaccine type is designed to efficiently induce a blocking antibody response against the self-antigen without activating cytotoxic T cells. If therapeutic vaccines become established as treatment options for conditions such as hypertension or dyslipidemia, their administration-potentially only a few times per year-could replace the need for daily medication. Nucleic acid drugs, including small interfering RNA and antisense oligonucleotides, have recently received attention as long-term agonists, similar to vaccines. Therefore, therapeutic vaccines or nucleic acid drugs could represent a novel strategy for controlling the progression of cardiovascular diseases. It is hoped that the accumulation of immunological findings and advances in vaccine technology will provide valuable insights into the development of vaccines for treating cardiovascular diseases.

Preventive effects of vasohibin-2-targeting peptide vaccine for diabetic nephropathy

Diabetic nephropathy remains the leading cause of end-stage kidney disease in many countries, and additional therapeutic targets are needed to prevent its development and progression. Some angiogenic factors are involved in the pathogenesis of diabetic nephropathy. Vasohibin-2 (VASH2) is a novel proangiogenic factor, and our previous study showed that glomerular damage is inhibited in diabetic Vash2 homozygous knockout mice. Therefore, we established a VASH2-targeting peptide vaccine as a tool for anti-VASH2 therapy in diabetic nephropathy. In this study, the preventive effects of the VASH2-targeting peptide vaccine against glomerular injury were examined in a streptozotocin (STZ)-induced diabetic mouse model. The mice were subcutaneously injected with the vaccine at two doses 2 wk apart and then intraperitoneally injected with 50 mg/kg STZ for 5 consecutive days. Glomerular injury was evaluated 20 wk after the first vaccination. Treatment with the VASH2-targeting peptide vaccine successfully induced circulating anti-VASH2 antibody without inflammation in major organs. Although the vaccination did not affect blood glucose levels, it significantly prevented hyperglycemia-induced increases in urinary albumin excretion and glomerular volume. The vaccination did not affect increased VASH2 expression but significantly inhibited renal angiopoietin-2 (Angpt2) expression in the diabetic mice. Furthermore, it significantly prevented glomerular macrophage infiltration. The preventive effects of vaccination on glomerular injury were also confirmed in db/db mice. Taken together, the results of this study suggest that the VASH2-targeting peptide vaccine may prevent diabetic glomerular injury in mice by inhibiting Angpt2-mediated microinflammation.NEW & NOTEWORTHY This study demonstrated preventive effects of VASH2-targeting peptide vaccine therapy on albuminuria and glomerular microinflammation in STZ-induced diabetic mouse model by inhibiting renal Angpt2 expression. The vaccination was also effective in db/db mice. The results highlight the importance of VASH2 in the pathogenesis of early-stage diabetic nephropathy and the practicability of anti-VASH2 strategy as a vaccine therapy.

Two decades of vaccine development against atherosclerosis

Atherosclerosis is an immune-mediated chronic inflammatory disease that leads to the development of fatty plaques in the arterial walls, ultimately increasing the risk of thrombosis, stroke, and myocardial infarction. The immune response in this complex disease is both atheroprotective and pro-atherogenic, involving both innate and adaptive immunity. Current treatments include the adjustment of lifestyle factors, cholesterol-lowering drugs such as statins, and immunotherapy, whereas vaccine development has received comparatively little attention. In this review, we discuss the potential of antigen-specific vaccination as a preventative approach based on more than 20 years of research and innovation. Vaccination targets include proteins that are more abundant in atherosclerotic patients, such as oxidized low-density lipoprotein (LDL), apolipoprotein B-100, proprotein convertase subtilisin/kexin type-9 serine protease (PCSK9), cholesteryl ester transfer protein (CETP), and heat shock proteins HSP60 and HSP65. Immunization with such proteins or their peptide epitopes has been shown to induce T-cell activation, produce antigen-specific antibodies, reduce the size of atherosclerotic lesions, and/or reduce serum cholesterol levels. Vaccination against atherosclerosis therefore offers a new strategy to address the burden on healthcare systems caused by cardiovascular disease, the leading cause of death worldwide.

Peptide-based vaccine targeting IL17A attenuates experimental spondyloarthritis in HLA-B27 transgenic rats

OBJECTIVES

Spondyloarthritis (SpA) is known as series of immune-mediated inflammatory disease of the axial and peripheral joints. Human leucocyte antigen (HLA)-B27 is a genetic risk factor for SpA. Recent evidence suggests that the interleukin -17 (IL17) axis strongly contributes to SpA. This study aimed to assess the efficacy of an IL17A peptide-based vaccine on SpA manifestations in model rats.

METHODS

HLA-B27/human β₂-microglobulin (hβ₂M) transgenic rats were immunised with heat-inactivated Mycobacterium tuberculosis (MT) to develop spondylitis and arthritis as an experimental SpA model after immunisation with a keyhole limpet hemocyanin-conjugated IL17A peptide-based vaccine with an alum adjuvant three times. The IL17A antibody titre was assessed using ELISA, and arthritis score and joint thickness were monitored two times a week. Enzyme-linked immunospot (ELISpot) assays for IL4- and interferon-γ-secreting splenocytes were conducted to evaluate IL17A-specific T cell activation. We also evaluated the effect of IL17A vaccine in SpA therapeutic model.

RESULTS

The IL17A peptide-based vaccine with alum adjuvant successfully induced antibody production and suppressed the arthritis score and joint thickness. X-ray and histological analyses showed that enthesitis, bone destruction and new bone formation were inhibited by the IL17A vaccine. The ELISpot assay showed that the IL17A peptide-based vaccine did not elicit any IL17A-reactive T cell responses. IL17A vaccine tends to mitigate, but not significant, in SpA treatment model. These data showed that the peptide-based vaccine targeting IL17A alleviated the SpA phenotype in a heat-inactivated MT-induced SpA model in HLA-B27/hβ₂M transgenic rats.

CONCLUSIONS

IL17A peptide-based vaccine may be a therapeutic option for SpA treatment.

A novel soluble epoxide hydrolase vaccine protects murine cardiac muscle against myocardial infarction

Myocardial infarction is still a life-threatening disease, even though its prognosis has been improved through the development of percutaneous coronary intervention and pharmacotherapy. In addition, heart failure due to remodeling after myocardial infarction requires lifelong management. The aim of this study was to develop a novel treatment suppressing the myocardial damage done by myocardial infarction. We focused on inhibition of soluble epoxide hydrolase to prolong the activation of epoxyeicosatrienoic acids, which have vasodilatory and anti-inflammatory properties. We successfully made a new vaccine to inactivate soluble epoxide hydrolase, and we have evaluated the effect of the vaccine in a rat myocardial infarction model. In the vaccinated group, the ischemic area was significantly reduced, and cardiac function was significantly preserved. Vaccine treatment clearly increased microvessels in the border area and suppressed fibrosis secondary to myocardial infarction. This soluble epoxide hydrolase vaccine is a novel treatment for improving cardiac function following myocardial infarction.

Effect of prorenin peptide vaccine on the early phase of diabetic retinopathy in a murine model of type 2 diabetes

Prorenin is viewed as an ideal target molecule in the prevention of diabetic retinopathy. However, no drugs are available for inhibiting activation of prorenin. Here, we tested the effect of a prorenin peptide vaccine (VP) in the retina of a murine model of type 2 diabetes (T2D). To choose the optimal vaccine, we selected three different epitopes of the prorenin prosegment (E1, E2, and E3) and conjugated them to keyhole limpet hemocyanin (KLH). We injected C57BL/6J mice twice with KLH only (as a control vaccine), E1 conjugated with KLH (E1-KLH), E2-KLH, or E3-KLH and compared antibody titers. E2-KLH showed the highest antibody titer and specific immunoreactivity of anti-sera against prorenin, so we used E2-KLH as VP. Then, we administered injections to the non-diabetic db/m and diabetic db/db mice, as follows: db/m + KLH, db/db + KLH, and db/db + VP. Retinal blood flow measurement with laser speckle flowgraphy showed that the impaired retinal circulation response to both flicker light and systemic hyperoxia in db/db mice improved with VP. Furthermore, the prolonged implicit time of b-wave and oscillatory potentials in electroretinography was prevented, and immunohistochemical analysis showed reduced microglial activation, gliosis, and vascular leakage. The enzyme-linked immunosorbent spot assay confirmed vaccinated mice had no auto-immune response against prorenin itself. The present data suggest that vaccination against prorenin is an effective and safe measure against the early pathological changes of diabetic retinopathy in T2D.

Brief report on a phase I/IIa study to assess the safety, tolerability, and immune response of AGMG0201 in patients with essential hypertension

We have been developing an angiotensin II vaccine for hypertension. We conducted a placebo-controlled dose escalation study to investigate the safety, tolerability, and immunological responses of this angiotensin II vaccine (AGMG0201). AGMG0201 was administered to participants with mild to moderate hypertension between 18 and 79 years of age. Twelve patients each were enrolled in the low-dose and high-dose groups. Within each group, subjects were randomly assigned to receive either the active study drug or a placebo at a ratio of 3:1. Each participant received a single intramuscular injection, followed by a second injection 30 days later, and was monitored for 360 days after the second dose. The results showed that most treatment-related adverse events were classified as mild or moderate in severity, including pain and erythema at the injection site. Anti-angiotensin II antibodies were observed in the AGMG0201 patients, especially in the high-dose group. Overall, AGMG0201 was well tolerated.

Prevention of vascular dementia via immunotherapeutic blockade of renin-angiotensin system in a rat model

INTRODUCTION

As several clinical trials have revealed that angiotensin-converting enzyme inhibitors and angiotensin II (Ang II) receptor blockers may be efficient in treating vascular dementia (VaD), the long-acting blockade of the renin-angiotensin system (RAS) would be useful considering the poor adherence of antihypertensive drugs. Accordingly, we continuously blocked RAS via vaccination and examined the effectiveness of the VaD model in rats.

METHODS

Male Wistar rats were exposed to two-vessel occlusions (2VO) after three injections of Ang II peptide vaccine. The effects of the vaccine were evaluated in the novel object recognition test, brain RAS components, and markers for oligodendrocytes.

RESULTS

In the vaccinated rats, anti-Ang II antibody titer level was increased in serum until Day 168, but not in cerebral parenchyma. Vaccinated rats showed better object recognition memory with inhibited demyelination in the corpus callosum and activation of astrocytes and microglia. Also, levels of BrdU/GSTπ-positive cells and the phosphorylation of cAMP response element binding protein was increased in vaccinated rats, indicating that the differentiation of oligodendrocyte progenitor cells to mature oligodendrocytes was accelerated. Vaccinated rats showed increased expression of fibroblast growth factor-2 (FGF2), which was observed in endothelial cells. Angiotensinogen mRNA was decreased at 7 days after 2VO but increased at 14 and 28 days.

CONCLUSION

Ang II vaccine might have promoted oligodendrocyte differentiation and inhibited astrocytic and microglial activation by stimulating FGF2 signaling in the endothelial cells-oligodendrocyte/astrocyte/microglia coupling. These data indicate the feasibility of Ang II vaccine for preventing progression of vascular dementia.

Therapeutic vaccine for chronic diseases after the COVID-19 Era

There is currently a respiratory disease outbreak caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). After rapid development, RNA vaccines and adenoviral vector vaccines were approved within a year, which has demonstrated the strong impact of preventing infectious diseases using gene therapy technology. Furthermore, intensive immunological analysis has been performed to evaluate the efficiency and safety of these vaccines, potentially allowing for rapid progress in vaccine technology. After the coronavirus disease 2019 (COVID-19) era, the novel vaccine technology developed will expand to other vaccines. We have been developing vaccines for chronic diseases, such as hypertension, for >10 years. Regarding the development of vaccines against self-antigens (i.e., angiotensin II), the vaccine should efficiently induce a blocking antibody response against the self-antigen without activating cytotoxic T cells. Therefore, the epitope vaccine approach has been proposed to induce antibody production in response to a combination of a B cell epitope and exogenous T cell epitopes through major histocompatibility complex molecules. When these vaccines are established as therapeutic options for hypertension, their administration regimen, which might be a few times per year, will replace daily medication use. Thus, therapeutic vaccines for hypertension may be a novel option to control the progression of cerebrovascular diseases. Hopefully, the accumulation of immunological findings and vaccine technology advances due to COVID-19 will provide a novel concept for vaccines for chronic diseases.

A novel angiotensin II peptide vaccine without an adjuvant in mice

OBJECTIVES

We recently developed a novel peptide, AJP001, that possesses both a mouse T-cell epitope and adjuvant action. Direct conjugation to the antigen is useful for peptide vaccines without the addition of adjuvants. In this study, the efficacy of an angiotensin (Ang) II and AJP001-conjugated peptide vaccine (AJ-Ang II) was evaluated in mice.

METHODS

The anti-Ang II antibody titer was measured in Balb/C mice following three injections of AJ-Ang II at 2-week intervals. SBP was measured during vaccination of Balb/C mice treated with Ang II infusion (1 μg/kg per min).

RESULTS

AJ-Ang II treatment resulted in an increase in the anti-Ang II antibody titer in a dose-dependent manner without the addition of adjuvants. In the analysis of the humoral immune response, AJ-Ang II mainly elicited IgG1 antibodies and IL-4 and IL-10 production, as measured by an enzyme-linked immune absorbent spot assay, which suggests the induction of a Th2 response. Importantly, cotreatment with purified antibodies attenuated Ang II-induced extracellular signal-regulated kinase phosphorylation and nuclear factor (NF)-κB activation in cultured vascular smooth muscle cells. The SBP in immunized mice was significantly lower than that in nonimmunized mice (135.9 ± 8.5 vs. 154.9 ± 16.8 mmHg, P = 0.02). Furthermore, Ang II-induced perivascular fibrosis in the heart was significantly attenuated in immunized mice, which also exhibited decreased mRNA expression of collagen I/III and transforming growth factor-β.

CONCLUSION

AJ-Ang II may be a simple and useful therapeutic peptide vaccine without the addition of any adjuvants.

Prevention of Progression of Aortic Aneurysm by Peptide Vaccine Against Ang II (Angiotensin II) in a Rat Model

There is no proven medical therapy to inhibit the progression of abdominal aortic aneurysm (AAA) in the clinical setting. To develop a novel therapeutic approach for the treatment of AAA, we focused on vaccination targeting Ang II (angiotensin II) and assessed the effect of an Ang II peptide vaccine on the progression of AAA using a rat model. Ang II peptide was conjugated with KLH (keyhole limpet hemocyanin) carrier protein to induce a sufficient immune response. Male rats were subcutaneously immunized with Ang II-KLH with an adjuvant on days 0, 14, and 28. Aortic dilatation was induced by intraluminal incubation with elastase on day 35. Treatment with Ang II vaccine successfully induced the production of a high titer of anti-Ang II antibodies. Immunization with Ang II vaccine resulted in a significant reduction in expansion of the aortic diameter compared with control rats, without a blood pressure-lowering effect. Four weeks after operation, the increase in Ang II in the aneurysm wall was significantly inhibited by treatment with Ang II vaccine. Inhibition of Ang II action led to suppression of the inflammatory response in the AAA wall through attenuation of the NFκB (nuclear factor kappa B) and c-jun N-terminal kinase signaling cascades. Treatment with Ang II vaccine inhibited accumulation of macrophages in the AAA wall. In addition, expression of TNF-α (tumor necrosis factor alpha) and activation of MMP (matrix metalloproteinase)-2 and MMP-9 were also inhibited by treatment with Ang II vaccine, resulting in protection against the destruction of elastic fibers. This vaccine therapy could become a potent therapeutic option to treat patients with AAA.

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.

Future Directions of Therapeutic Vaccines for Chronic Diseases

Vaccines are well-known therapies for infectious disease and cancer; however, recently, we and others have developed vaccines for other chronic diseases, such as hypertension, diabetes and dyslipidemia. Although we have many treatment options for hypertension, including angiotensin II type 1 receptor blockers, calcium-channel blockers, and diuretics, a substantial portion of the hypertensive population has uncontrolled blood pressure due to poor medication adherence. When these vaccines are established in the future as therapeutic options for chronic diseases, their administration regimen, such as several times per year, will replace daily medication use. Thus, therapeutic vaccines might be a novel option to control the progression of cardiovascular diseases. Importantly, regarding the development of vaccines against self-antigens (i.e., angiotensin II), the vaccine should efficiently induce a blocking antibody response against the self-antigen without provoking cytotoxic T cells. Therefore, to address the safety and efficiency of therapeutic vaccines, we have developed an original B-cell vaccine to induce antibody production and used carrier proteins, which include exogenous T-cell epitopes through the major histocompatibility complex. In this review, we will introduce the challenges in developing therapeutic vaccines for chronic diseases and describe the therapeutic potential for cardiovascular diseases.

AJP001, a novel helper T-cell epitope, induces a humoral immune response with activation of innate immunity when included in a peptide vaccine

Vaccine design requires well-tailored formulations including a T-cell epitope and adjuvants. We identified a novel cationic peptide, AJP001, which possesses a strong affinity for murine MHC class II alleles (H2-IEd and H2-IAd) and low affinity for H2-IAb. We designed an AJP001 and epitope peptide-conjugated vaccine, AJP001-angiotensin (Ang) II, which was intracutaneously administered to mice three times at 2-week intervals. Indeed, the AJP001-Ang II vaccine induced antibody production against Ang II in BALB/cA mice but not in C57BL/6 mice. To estimate the T-cell-dependent immunogenicity of the AJP001 conjugate vaccine in human cells, naïve human peripheral blood mononuclear cells (PBMCs) were exposed to AJP001-Ang II, and T-cell proliferation was evaluated by analyzing cell division using flow cytometric measurement of carboxyfluorescein succinimidyl ester (CFSE) dye dilution. To activate the immune response, the innate immune system must be activated by adjuvant treatment. Interestingly, treatment with AJP001 induced IL-1β and IL-18 secretion via NLRP3 inflammasome activation and induced TNF-α and IL-6 production through an NF-κB-dependent pathway in human and mouse macrophages. These results suggest that AJP001 behaves as a T-cell epitope in mice and humans and is a useful tool for the formulation of peptide vaccines without the addition of adjuvants.

[Development of therapeutic vaccine for life style-related diseases]

In the 18^th century, Edward Jenner proposed the vaccine for smallpox as a first vaccine therapy based on the legend that a vaccinia prevents the infection with smallpox. Recently, the therapeutic target of vaccine will expand from infectious diseases to various diseases, such as amyloid β or tau vaccine for Alzheimer's disease. We are now going to develop a therapeutic vaccine to lifestyle-related diseases (i.e. high blood pressure), and aim to realize a novel therapy which will be injected once or twice per year from a daily medication. For this purpose, the appropriate choice of an antigen, carrier and adjuvants should be required to activate hormonal immunity by the vaccine, leading to efficient antibody production without toxicity, because the therapeutic target of our vaccine is an endogenous protein (i.e. hormone). The clinical advantage of this therapeutic vaccine is to improve the medical adherence and drug management because the multiple drug users are increased in particular old patients, so called polypharmacy. If the vaccine will take place of a part of medicine in future, it may give us a novel therapeutic option with several social benefits.

Therapeutic Vaccine Against S100A9 (S100 Calcium-Binding Protein A9) Inhibits Thrombosis Without Increasing the Risk of Bleeding in Ischemic Stroke in Mice

Decreased adherence to daily ingestion of antiplatelet drugs is a critical issue, increasing mortality and morbidity in poststroke patients. As vaccination could be a promising approach to solving this, we designed an antiplatelet vaccine that inhibited S100A9 (S100 calcium-binding protein A9)/CD36 (cluster of differentiation 36) signaling in platelets, which was reported to be a key signal in arterial thrombosis, but not hemostasis. Immunization with this vaccine induced a sustainable increase in the anti-S100A9 antibody titer for >2 months and an additional booster immunization enhanced the antibody production further. The middle cerebral artery occlusion time was successfully prolonged in the vaccinated mice, which was comparable to that in mice treated with clopidogrel. The antithrombotic effect lasted for 84 days after the last vaccination, as well as after the booster immunization. Importantly, the bleeding time was not affected in the immunized mice. The antithrombotic effect was also observed in the common carotid artery, which was similar to that found in CD36^-/- mice. Vascular injury increased the expression of S100A9 in the serum and phosphorylation of JNK (c-Jun N-terminal kinase) and VAV1 in the platelets, but these increases were inhibited in the immunized mice. Moreover, the S100A9 vaccine did not induce cell-mediated autoimmunity, as demonstrated by the enzyme-linked immunosorbent spot assay. Thus, immunization with the S100A9 vaccine resulted in long-term inhibition of thrombus formation through inhibition of increased S100A9/CD36 signaling without risk of bleeding or adverse autoimmune responses. Vaccination against S100A9 might be a novel therapy to prevent recurrent ischemic stroke.

Peptide vaccine for semaphorin3E ameliorates systemic glucose intolerance in mice with dietary obesity

We previously demonstrated that cellular aging signals upregulated a secreted class 3 semaphorin E (Sema3E) and its receptor plexinD1 in the adipose tissue of a murine model of dietary obesity and that Sema3E was a chemoattractant, mediating its biological effects by inducing infiltration of plexinD1-positive inflammatory macrophages into the visceral white adipose tissue. This study was performed to develop a peptide vaccine for Sema3E and test its therapeutic potential in a murine model of dietary obesity. Two antigenic peptides were selected to generate neutralizing antibodies for a vaccine. These peptides were conjugated to keyhole limpet hemocyanin (KLH), and were administered with Freund’s adjuvant to obese wild-type male mice. The Sema3E antibody titer was analyzed by ELISA, and the biological effects of the peptides were tested in mice with dietary obesity. Among the two candidate peptides, the Sema3E antibody titer was significantly increased by injection of KLH-conjugated HKEGPEYHWS (Sema3E vaccine). Administration of Sema3E vaccine suppressed the infiltration of plexinD1-positive cells, ameliorated chronic inflammation in visceral white adipose tissue, and improved systemic glucose intolerance in mice with dietary obesity, suggesting that Sema3E vaccine has the potential to become a next generation therapy for obesity and diabetes.

Recombinant neuraminidase pseudotyped baculovirus: a dual vector for delivery of Angiotensin II peptides and DNA vaccine

Baculovirus is a promising vaccine deliver vector due to its biosafety profiles, gene transfer efficiency, ability to display small foreign antigens on its surface, strong adjuvant activities, etc. A dual vector for peptide antigens and a DNA vaccine delivery was constructed. In this vector, a tetrameric glycoprotein neuraminidase (NA) from influenza A virus (H5N1) serves as a baculovirus surface protein to improve baculovirus transduction efficiency and a partner for displaying the target peptide antigen. Nucleotides encoding target peptides could be fused to a full length NA gene, at the lower part of its head structure, integrated into Autographa californica multinucleopolyhedrovirus genome and expressed under the control of a White Spot Syndrome Virus IE-1 shuttle promoter. Angiotensin II (AngII) peptides, a potent vasoconstrictor that causes high blood pressure, was our target antigen. The recombinant NA-AngII pseudotyped baculovirus had the AngII peptides fused to the NA and displayed on its surface. In vitro studies revealed that this recombinant baculovirus successfully delivered AngII peptides, as DNA vaccine, into human HEK293A cells. A single subcutaneous injection of the recombinant NA-AngII pseudotyped baculovirus into moderately high blood pressure rats at 4 × 10⁹ pfu/rat, stimulated anti-AngII antibody production and their systolic blood pressure (SBP) levels were found to have decreased. In addition, a single intranasal immunization at 8 × 10⁸ pfu/rat, raised anti-AngII antibodies in a rat and its SBP was also reduced. The recombinant neuraminidase pseudotyped baculovirus is a potential vector for AngII peptide antigen and DNA vaccine for subcutaneous or intranasal immunization for treatment of hypertension.

Recent Advances in the Development of Vaccines for Diabetes, Hypertension, and Atherosclerosis

Vaccines are commonly used in the prevention of infectious diseases. The basic principle of vaccination is to use specific antigens, endogenous or exogenous to stimulate immunity against the specific antigens or cells producing them. Autoantigen or oligo vaccination has been used for disease animal models. More recently humanized monoclonal antibodies have been successfully used for the treatment of neoplastic disorders or familial hypercholesterolemia. Humanized monoclonal antibody therapy needs repeated injection, and the therapy is expensive. Therapeutic vaccination can lead to persistent immunized or immune tolerant against the therapeutic molecule(s) or site. However, immunization against those endogenous substances may also elicit persistent autoimmune reaction or destruction that do harm to health. Therefore, rigorous studies are needed before any clinical application. In this review, we briefly reviewed vaccines used in protection against common metabolic diseases including atherosclerosis, hypertension, and diabetes mellitus.

Novel Medical Treatments for Hypertension and Related Comorbidities

Purpose of Review

The purpose of this review is to summarize the most recent data available on advances in development of novel medical treatments for hypertension and related comorbidities.

Recent Findings

Approximately half of all hypertensive patients have not achieved goal blood pressure with current available antihypertensive medications. Recent landmark studies and new hypertension guidelines have called for stricter blood pressure control, creating a need for better strategies for lowering blood pressure. This has led to a shift in focus, in recent years, to the development of combination pills as a means of achieving improved blood pressure control by increasing adherence to prescribed medications along with further research and development of promising novel drugs based on discovery of new molecular targets such as the counter-regulatory renin-angiotensin system.

Summary

Fixed-dose combination pills and novel treatments based on recently discovered pathogenic mechanisms of hypertension that have demonstrated promising results as treatments for hypertension and related comorbidities will be discussed in this review.

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.

Future drug discovery in renin-angiotensin-aldosterone system intervention

INTRODUCTION

Renin-angiotensin-aldosterone system inhibitors (RAASIs), including angiotensin-converting enzyme inhibitors, angiotensin AT1 receptor blockers and mineralocorticoid receptor antagonists (MRAs), are the cornerstone for the treatment of cardiovascular and renal diseases. Areas covered: The authors searched MEDLINE, PubMed and ClinicalTrials.gov to identify eligible full-text English language papers. Herein, the authors discuss AT2-receptor agonists and ACE2/angiotensin-(1-7)/Mas-receptor axis modulators, direct renin inhibitors, brain aminopeptidase A inhibitors, biased AT1R blockers, chymase inhibitors, multitargeted drugs, vaccines and aldosterone receptor antagonists as well as aldosterone synthase inhibitors. Expert opinion: Preclinical studies have demonstrated that activation of the protective axis of the RAAS represents a novel therapeutic strategy for treating cardiovascular and renal diseases, but there are no clinical trials supporting our expectations. Non-steroidal MRAs might become the third-generation of MRAs for the treatment of heart failure, diabetes mellitus and chronic kidney disease. The main challenge for these new drugs is that conventional RAASIs are safe, effective and cheap generics. Thus, the future of new RAASIs will be directed by economical/strategic reasons.

Angiotensin II Peptide Vaccine Protects Ischemic Brain Through Reducing Oxidative Stress

Background and Purpose—

Medication nonadherence is one of major risk factors for the poor outcome in ischemic stroke. Vaccination is expected to solve such a problem because of its long-lasting effects, but its effect on ischemic brain damage is still unknown. Here, we focused on vaccination for renin–angiotensin system and examined the effects of angiotensin II (Ang II) peptide vaccine in permanent middle cerebral artery occlusion model in rats.

Methods—

Male Wistar rats were exposed to permanent middle cerebral artery occlusion after 3× injections of Ang II peptide vaccine, and the serum or brain level of anti–Ang II antibody was examined. The effects of the vaccine were evaluated by differences in infarction volume, brain renin–angiotensin system components, and markers for neurodegeneration and oxidative stress.

Results—

Ang II vaccination successfully produced anti–Ang II antibodies in serum without concomitant change in blood pressure. Sufficient production of serum anti–Ang II antibody led to reduction of infarct volume and induced the penetration of anti–Ang II antibody in ischemic hemisphere, with suppressed expression of Ang II type 1 receptor mRNA. Vaccinated rats with sufficient antibody production showed the reduction of Fluoro-Jade B–positive cells, spectrin fragmentation, 4-hydroxynonenal-positive cells, and Nox 2 mRNA expression.

Conclusions—

Our findings indicate that Ang II vaccination exerts neuroprotective and antioxidative effects in cerebral ischemia, with renin–angiotensin system blockade by penetration of anti–Ang II antibodies into ischemic brain lesion. Ang II peptide vaccination could be a promising approach to treat ischemic stroke.

Design of therapeutic vaccines as a novel antibody therapy for cardiovascular diseases

Vaccines are primarily used worldwide as a preventive medicine for infectious diseases and have recently been applied to cancer. We and others have developed therapeutic vaccines designed for cardiovascular diseases that are notably different from previous vaccines. In the case of cancer vaccines, a specific protein in cancer cells is a target antigen, and the activation of cytotoxic T cells (CTL) is required to kill and remove the antigen-presenting cancer cells. Our therapeutic vaccines work against hypertension by targeting angiotensin II (Ang II) as the antigen, which is an endogenous hormone. Therapeutic vaccines must avoid CTL activation and induce the blocking antibodies for Ang II. The goal of our therapeutic vaccine for cardiovascular diseases is to induce the specific antibody response toward the target protein without inducing T-cell or antibody-mediated inflammation through the careful selection of the target antigen, carrier protein and adjuvants. The goal of our therapeutic vaccine is similar to that of antibody therapy. Recently, multiple antibody-based drugs have been developed for cancer, immune-related diseases, and dyslipidemia, which are efficient but expensive. If the effect of a therapeutic vaccine is nearly equivalent to antibody therapy as an alternative approach, the lower medical cost and improvement in drug adherence can be advantages of therapeutic vaccines. In this review, we will describe our concept of therapeutic vaccines for cardiovascular diseases and the future directions of therapeutic vaccines as novel antibody therapies.

A peptide vaccine targeting angiotensin II attenuates the cardiac dysfunction induced by myocardial infarction

A peptide vaccine targeting angiotensin II (Ang II) was recently developed as a novel treatment for hypertension to resolve the problem of noncompliance with pharmacotherapy. Ang II plays a crucial role in the pathogenesis of cardiac remodeling after myocardial infarction (MI), which causes heart failure. In the present study, we examined whether the Ang II vaccine is effective in preventing heart failure. The injection of the Ang II vaccine in a rat model of MI attenuated cardiac dysfunction in association with an elevation in the serum anti-Ang II antibody titer. Furthermore, any detrimental effects of the Ang II vaccine were not observed in the rats that underwent sham operations. Treatment with immunized serum from Ang II vaccine-injected rats significantly suppressed post-MI cardiac dysfunction in MI rats and Ang II-induced remodeling-associated signaling in cardiac fibroblasts. Thus, our present study demonstrates that the Ang II vaccine may provide a promising novel therapeutic strategy for preventing heart failure.

Evaluating the potential of the GFAP-KLH immune-tolerizing vaccine for type 1 diabetes in mice

Glial fibrillary acidic protein (GFAP), expressed in peri-islet Schwann cells, is a novel target for the treatment of type 1 diabetes mellitus (T1DM). We designed a GFAP immune-tolerizing vaccine that successfully suppresses hyperglycemia and enhances C peptide secretion. The GFAP vaccine significantly prevented T cell infiltration into pancreatic islets. Moreover, after GFAP vaccination, naïve T-cell differentiation shifted from a cytotoxic Th1- to a Th2-biased humoral response. These results indicate that as a novel target, GFAP reliably predicts the development of T1DM, and that the GFAP vaccine successfully delays the progression of T1DM by regulating T-cell differentiation.

New Approaches in the Treatment of Hypertension

Hypertension is the most common modifiable risk factor for cardiovascular disease and death, and lowering blood pressure with antihypertensive drugs reduces target organ damage and prevents cardiovascular disease outcomes. Despite a plethora of available treatment options, a substantial portion of the hypertensive population has uncontrolled blood pressure. The unmet need of controlling blood pressure in this population may be addressed, in part, by developing new drugs and devices/procedures to treat hypertension and its comorbidities. In this Compendium Review, we discuss new drugs and interventional treatments that are undergoing preclinical or clinical testing for hypertension treatment. New drug classes, eg, inhibitors of vasopeptidases, aldosterone synthase and soluble epoxide hydrolase, agonists of natriuretic peptide A and vasoactive intestinal peptide receptor 2, and a novel mineralocorticoid receptor antagonist are in phase II/III of development, while inhibitors of aminopeptidase A, dopamine β-hydroxylase, and the intestinal Na + /H + exchanger 3, agonists of components of the angiotensin-converting enzyme 2/angiotensin(1–7)/Mas receptor axis and vaccines directed toward angiotensin II and its type 1 receptor are in phase I or preclinical development. The two main interventional approaches, transcatheter renal denervation and baroreflex activation therapy, are used in clinical practice for severe treatment resistant hypertension in some countries. Renal denervation is also being evaluated for treatment of various comorbidities, eg, chronic heart failure, cardiac arrhythmias and chronic renal failure. Novel interventional approaches in early development include carotid body ablation and arteriovenous fistula placement. Importantly, none of these novel drug or device treatments has been shown to prevent cardiovascular disease outcomes or death in hypertensive patients.

Development of DNA vaccines as an anti-hypertensive therapy or for anti-angiogenesis

INTRODUCTION

Vaccines are used as preventive medicine for infectious diseases worldwide; however, several recent studies have indicated the potential of therapeutic vaccines for managing Alzheimer's disease or hypertension.

AREAS COVERED

The concept and history of therapeutic vaccines for hypertension are introduced. The improvement of drug compliance associated with vaccines in hypertensive patients may assist in better control of blood pressure, leading to reduced complications. Recently, groups have attempted to develop a therapeutic vaccine against hypertension. The vaccine-induced anti-angiotensin II antibodies can efficiently ameliorate high blood pressure. DNA vaccines have also been designed via a similar strategy using a plasmid vector encoding a hepatitis B core (HBc)-angiotensin II fusion protein. The immunogenic molecule (i.e., HBc) is used to provide an antigen that supports the activation of T cells in this DNA vaccine system. The platform technology can also be applied to generate a VEGF vaccine for cancer.

EXPERT OPINION

To date, several clinical studies of DNA vaccines have been conducted, but their effectiveness has not been determined. We hope that the novel concept of DNA vaccines will contribute to promoting health and medicine in the future.

Peptide Vaccines for Hypertension and Diabetes Mellitus

Vaccines are commonly used as a preventive medicine for infectious diseases worldwide; however, the trial for an amyloid beta vaccine against Alzheimer’s disease will open a new concept in vaccination. In case of therapeutic vaccines for cancer, their targets are usually specific antigens in cancer cells, allowing activated cytotoxic T cells (CTLs) to attach and remove the antigen-presenting cancer cells. In our therapeutic vaccines against hypertension, the target is angiotensin II (Ang II) and induced anti-Ang II antibodies could efficiently ameliorate high blood pressure. Similarly, we developed the therapeutic vaccine against DPP4 for diabetes mellitus. However, because Ang II or DPP4 is an endogenous hormone, we must avoid autoimmune disease induced by these vaccines. Therefore, our system was used to design a therapeutic vaccine that elicits anti-Ang II or DPP4 antibodies without CTL activation against Ang II or DPP4. In this review, we will describe our concept of therapeutic vaccines for hypertension and diabetes mellitus.

Therapeutic vaccine against DPP4 improves glucose metabolism in mice

The increasing prevalence of type 2 diabetes mellitus is associated with a significant economic burden. We developed a dipeptidyl peptidase 4 (DPP4)-targeted immune therapy to increase glucagon-like peptide 1 hormone levels and improve insulin sensitivity for the prevention and treatment of type 2 diabetes mellitus. Immunization with the DPP4 vaccine in C57BL/6J mice successfully increased DPP4 titer, inhibited plasma DPP4 activity, and induced an increase in the plasma glucagon-like peptide 1 level. Moreover, this elevated titer was sustained for 3 mo. In mice fed a high-fat diet, DPP4 vaccination resulted in improved postprandial glucose excursions and insulin sensitivity and, in the diabetic KK-A(y) and db/db mice strains, DPP4 vaccination significantly reduced glucose excursions and increased both plasma insulin and pancreatic insulin content. Importantly, T cells were not activated following challenge with DPP4 itself, which suggests that this vaccine does not induce cell-mediated autoimmunity. Additionally, no significant immune-mediated damage was detected in cells and tissues where DPP4 is expressed. Thus, this DPP4 vaccine may provide a therapeutic alternative for patients with diabetes.