Inhibition of atherogenesis in LDLR knockout mice by systemic delivery of adeno-associated virus type 2-hIL-10

Zhuyu Pill Alleviates Nonalcoholic Fatty Liver Disease by Regulating Bile Acid Metabolism through the Gut-Liver Axis

AIM

The prevalence of nonalcoholic fatty liver disease (NAFLD) is increasing worldwide, but there are currently limited treatment options available. Therefore, it is necessary to research new treatment strategies. Zhuyu Pill (ZYP) is a well-known herbal recipe consisting of Huanglian (Coptidis rhizoma) and Wuzhuyu (Evodiae Fructus) that has been clinically used to treat NAFLD. This study aimed to investigate the impact of ZYP on NAFLD induced by a high-fat diet (HFD) and to identify its potential mechanism.

METHODS

In this investigation, we used ZYP to treat a mouse model of NAFLD induced by an HFD. We conducted various analyses including assessment of serum biochemical indices, histological evaluation, fecal metabonomics analysis, western blot, and quantitative real-time polymerase chain reaction.

RESULTS

ZYP effectively improved blood lipid levels and reduced inflammatory response in HFD mice, while also alleviating liver cell damage and lipid accumulation. Additionally, ZYP influenced the fecal bile acid (BA) metabolism profiles of HFD mice by inhibiting the signal transduction of ileal farnesoid X receptor (FXR) fibroblast growth factor 15 (FGF15), enhancing the expression of cytochrome P450 family 7 subfamily A member 1(CYP7A1), promoting BA synthesis and increasing the metabolic elimination of cholesterol.

CONCLUSION

ZYP shows promise as a potential treatment for alleviating NAFLD by modulating BA metabolism through the FXR-FGF15-CYP7A1 pathway.

Research progress on Th17 and T regulatory cells and their cytokines in regulating atherosclerosis

Background

Coronary heart disease due to atherosclerosis is the leading cause of death worldwide. Atherosclerosis is considered a chronic inflammatory state in the arterial wall that promotes disease progression and outcome, and immune cells play an important role in the inflammatory process.

Purpose

We review the mechanisms of CD4+ T subsets, i.e., helper T17 (Th17) cells and regulatory T cells (Tregs), in regulating atherosclerosis, focusing on the role of interleukin (IL)-17, IL-10, and other cytokines in this disease and the factors influencing the effects of these cytokines.

Results

IL-17 secreted by Th17 cells can promote atherosclerosis, but few studies have reported that IL-17 can also stabilize atherosclerotic plaques. Tregs play a protective role in atherosclerosis, and Th17/Treg imbalance also plays an important role in atherosclerosis.

Conclusion

The immune response is important in regulating atherosclerosis, and studying the mechanism of action of each immune cell on atherosclerosis presents directions for the treatment of atherosclerosis. Nevertheless, the current studies are insufficient for elucidating the mechanism of action, and further in-depth studies are needed to provide a theoretical basis for clinical drug development.

CRISPR/Cas9 based blockade of IL-10 signaling impairs lipid and tissue homeostasis to accelerate atherosclerosis

Interleukin-10 (IL-10) is a widely recognized immunosuppressive factor. Although the concept that IL-10 executes an anti-inflammatory role is accepted, the relationship between IL-10 and atherosclerosis is still unclear, thus limiting the application of IL-10-based therapies for this disease. Emerging evidence suggests that IL-10 also plays a key role in energy metabolism and regulation of gut microbiota; however, whether IL-10 can affect atherosclerotic lesion development by integrating lipid and tissue homeostasis has not been investigated. In the present study, we developed a human-like hamster model deficient in IL-10 using CRISPR/Cas9 technology. Our results showed that loss of IL-10 changed the gut microbiota in hamsters on chow diet, leading to an increase in lipopolysaccharide (LPS) production and elevated concentration of LPS in plasma. These changes were associated with systemic inflammation, lipodystrophy, and dyslipidemia. Upon high cholesterol/high fat diet feeding, IL-10-deficient hamsters exhibited abnormal distribution of triglyceride and cholesterol in lipoprotein particles, impaired lipid transport in macrophages and aggravated atherosclerosis. These findings show that silencing IL-10 signaling in hamsters promotes atherosclerosis by affecting lipid and tissue homeostasis through a gut microbiota/adipose tissue/liver axis.

A Guide to Different Intensities of Exercise, Vaccination, and Sports Nutrition in the Course of Preparing Elite Athletes for the Management of Upper Respiratory Infections during the COVID-19 Pandemic: A Narrative Review

Elite athletes use high-intensity training to maintain their fitness level. However, intense training can harm the immune system, making athletes suspectable to COVID-19 and negatively affecting their performance. In addition, the diet of athletes should be appreciated more as it is another influencer of the immune system, especially during the COVID 19 pandemic. The other important issue elite athletes face currently is vaccination and its possible intervention with their training. The present study attempts to discuss the impact of different training intensities, nutritional strategies, and vaccination on the immune system function in elite athletes. To this end, Scopus, ISC, PubMed, Web of Science, and Google Scholar databases were searched from 1988 to 2021 using the related keywords. The results of our review showed that although high-intensity exercise can suppress the immune system, elite athletes should not stop training in the time of infection but use low- and moderate-intensity training. Moderate-intensity exercise can improve immune function and maintain physical fitness. In addition, it is also better for athletes not to undertake high-intensity training at the time of vaccination, but instead perform moderate to low-intensity training. Furthermore, nutritional strategies can be employed to improve immune function during high-intensity training periods.

Studying the effect of garlic consumption and endurance training on serum levels of some pro-and anti-inflammatory cytokines in female mice with breast cancer - A randomized trial

Background:

This study aimed to determine the effect of garlic consumption and endurance training on the serum levels of some pro-inflammatory and anti-inflammatory cytokines in female mice with breast cancer.

Methods:

This study is an experimental research randomly conducted on 32 female BALB/c mice divided into 4 equal groups (N = 8), including: Cancer Control (CC), Garlic Supplementation (GS), Endurance Training (ET), Endurance Training + Garlic Supplementation (ET + GS). One million cancerous cells were injected to all mice's upper right thigh using the subcutaneous injection method. Exercise groups performed endurance training for 8 weeks (5 days a week.(Garlic supplement groups received 1 ml of the garlic extract orally per kilogram of body weight. The control groups -were not given any task, activity or exercise during the research. At the end of the research, all the mice were anesthetized, and their blood samples were collected.

Results:

The period of 8-week simultaneous endurance exercise and consumption of garlic supplement significantly decreased the serum level of interleukin-6 (F = 75 P = 0.00), interleukin-8 (F = 97.9 P = 0.00), and interleukin-17 (F = 95.7 P = 0.00), and increased the serum level of interleukin-10 (F = 50.4 P = 0.00).

Conclusions:

Along with other existing methods, reduction of inflammatory factors, endurance exercises and consumption of garlic supplement have been proved to be an extremely effective treatment for breast cancer patients.

Exosome-mediated delivery of inflammation-responsive Il-10 mRNA for controlled atherosclerosis treatment

Rationale: Tailored inflammation control is badly needed for the treatment of kinds of inflammatory diseases, such as atherosclerosis. IL-10 is a potent anti-inflammatory cytokine, while systemic and repeated delivery could cause detrimental side-effects due to immune repression. In this study, we have developed a nano-system to deliver inflammation-responsive Il-10 mRNA preferentially into macrophages for tailored inflammation control. Methods: Il-10 was engineered to harbor a modified HCV-IRES (hepatitis C virus internal ribosome entry site), in which the two miR-122 recognition sites were replaced by two miR-155 recognition sites. The translational responsiveness of the engineered mRNA to miR-155 was tested by Western blot or ELISA. Moreover, the engineered Il-10 mRNA was passively encapsulated into exosomes by forced expression in donor cells. Therapeutic effects on atherosclerosis and the systemic leaky expression effects in vivo of the functionalized exosomes were analyzed in ApoE^-/- (Apolipoprotein E-deficient) mice. Results: The engineered IRES-Il-10 mRNA could be translationally activated in cells when miR-155 was forced expressed or in M1 polarized macrophages with endogenous miR-155 induced. In addition, the engineered IRES-Il-10 mRNA, when encapsulated into the exosomes, could be efficiently delivered into macrophages and some other cell types in the plaque in ApoE^-/- mice. In the recipient cells of the plaque, the encapsulated Il-10 mRNA was functionally translated into protein, with relatively low leaky in other tissues/organs without obvious inflammation. Consistent with the robust Il-10 induction in the plaque, exosome-based delivery of the engineered Il-10 could alleviate the atherosclerosis in ApoE^-/- mice. Conclusion: Our study established a potent platform for controlled inflammation control via exosome-based systemic and repeated delivery of engineered Il-10 mRNA, which could be a promising strategy for atherosclerosis treatment.

Exercise for slowing the progression of atherosclerotic process: effects on inflammatory markers

Atherosclerosis is a dynamic process driven by all cardiovascular risk factors that can be briefly divided into an early and a late phase. Inflammation is one of the fundamental substrates that initiates the atherosclerotic process in the early stages and promotes and maintains it in the final stages. In the last decades, clinical and experimental data have shown that inflammation is supported by mediators that respond to physical activity. The present review aimed at investigating the effect of physical exercise on inflammatory mediators, both the positive ones that have a proinflammatory effect (interleukin 6, c-reactive protein and tumor necrosis factor α, interferon γ, high-mobility group box-1), and the negative ones which have an anti-inflammatory effect (interleukin 10). Pooled data support the evidence that physical exercise can directly modulate the activity of inflammatory cytokines slowing down or preventing the formation of the atherosclerotic stage.

Resuscitation After Hemorrhagic Shock in the Microcirculation: Targeting Optimal Oxygen Delivery in the Design of Artificial Blood Substitutes

Microcirculatory preservation is essential for patient recovery from hemorrhagic shock. In hemorrhagic shock, microcirculatory flow and pressure are greatly reduced, creating an oxygen debt that may eventually become irreversible. During shock, tissues become hypoxic, cellular respiration turns to anaerobic metabolism, and the microcirculation rapidly begins to fail. This condition requires immediate fluid resuscitation to promote tissue reperfusion. The choice of fluid for resuscitation is whole blood; however, this may not be readily available and, on a larger scale, may be globally insufficient. Thus, extensive research on viable alternatives to blood has been undertaken in an effort to develop a clinically deployable blood substitute. This has not, as of yet, achieved fruition, in part due to an incomplete understanding of the complexities of the function of blood in the microcirculation. Hemodynamic resuscitation is acknowledged to be contingent on a number of factors other than volume expansion. The circulation of whole blood is carefully regulated to optimize oxygen delivery to the tissues via shear stress modulation through blood viscosity, inherent oxygen-carrying capacity, cell-free layer variation, and myogenic response, among other variables. Although plasma expanders can address a number of these issues, hemoglobin-based oxygen carriers (HBOCs) introduce a method of replenishing the intrinsic oxygen-carrying capacity of blood. There continue to be a number of issues related to HBOCs, but recent advances in the next-generation HBOCs show promise in the preservation of microcirculatory function and limiting toxicities. The development of HBOCs is now focused on viscosity and the degree of microvascular shear stress achieved in order to optimize vasoactive and oxygen delivery responses by leveraging the restoration and maintenance of physiological responses to blood flow in the microcirculation. Blood substitutes with higher viscous properties tend to improve oxygen delivery compared to those with lower viscosities. This review details current concepts in blood substitutes, particularly as they relate to trauma/hemorrhagic shock, with a specific focus on their complex interactions in the microcirculation.

The effects of six-week resistance, aerobic and combined exercises on the pro-inflammatory and anti-inflammatory markers in overweight patients with moderate haemophilia A: A randomized controlled trial

INTRODUCTION

Overweight increases the secretion of pro-inflammatory cytokines and serves as a major risk factor for arthropathy and cardiovascular diseases (CVD). This condition is becoming increasingly prevalent among patients with haemophilia (PWH). Different forms of exercise training could favourably modify weight-related complications, cardiovascular risk factors and the inflammation.

AIM

To investigate the effects of resistance, aerobic and combined exercises on the pro-inflammatory and anti-inflammatory markers in overweight patients with moderate haemophilia A.

METHODS

Forty-eight patients with moderate haemophilia A, aged 35-55 years, and body mass index (BMI) of 25-30 kg/m² were randomly assigned to resistance training (RT, n = 12), aerobic (AT, n = 12), combined training (CT, n = 12) and control (n = 12) groups. The patients participated in 45-minutes exercise sessions three times a week for 6 weeks. Waist circumference (WC), waist-to-hip ratio (WHR), fat mass, fat-free mass, interleukin-10 (IL-10), adiponectin, tumour necrosis factor-α (TNF-α), interleukin-6 (IL-6) and high sensitive C-reactive protein (hs-CRP) were measured before and after the 6 weeks of training.

RESULTS

There was significant decrease in WC, WHR, BMI and weight in the AT, RT and CT groups as compared to the control group. Total HJHS scores decreased in the AT, RT, CT groups compared to the control groups (P ≤ 0.001). The decrease in hs-CRP, IL-6 and TNF-α in the CT group was significant compared to the control group (P ≤ 0.02). The increase in IL-10 and adiponectin was not significant in the RT, AT and CT groups compared to the control group.

CONCLUSION

CT was the most effective training mode for decreasing the pro-inflammatory cytokines and increasing anti-inflammatory markers in overweight patients with haemophilia A.

Effect of soluble cleavage products of important receptors/ligands on efferocytosis: Their role in inflammatory, autoimmune and cardiovascular disease

Efferocytosis, the clearance of apoptotic cells (ACs), is a physiologic, multifaceted and dynamic process and a fundamental mechanism for the preservation of tissue homeostasis by avoiding unwanted inflammation and autoimmune responses through special phagocytic receptors. Defective efferocytosis is associated with several disease states, including cardiovascular disease and impaired immune surveillance, as occurs in cancer and autoimmune disease. A major cause of defective efferocytosis is non-functionality of surface receptors on either the phagocytic cells or the ACs, such as TAM family tyrosine kinase, which turns to a soluble form by cleavage/shedding or alternative splicing. Recently, soluble forms have featured prominently as potential biomarkers, indicative of prognosis and enabling targeted therapy using several commonly employed drugs and inhibitors, such as bleomycin, dexamethasone, statins and some matrix metalloproteinase inhibitors such as TAPI-1 and BB3103. Importantly, to design drug carriers with enhanced circulatory durability, the adaptation of soluble forms of physiological receptors/ligands has been purported. Research has shown that soluble forms are more effective than antibody forms in enabling targeted treatment of certain conditions, such as autoimmune diseases. In this review, we sought to summarize the current knowledge of these soluble products, how they are generated, their interactions, roles, and their potential use as biomarkers in prognosis and treatment related to inflammatory, cardiovascular, and autoimmune diseases.

Regulatory T Cells Promote Macrophage Efferocytosis during Inflammation Resolution

Regulatory T (Treg) cell responses and apoptotic cell clearance (efferocytosis) represent critical arms of the inflammation resolution response. We sought to determine whether these processes might be linked through Treg-cell-mediated enhancement of efferocytosis. In zymosan-induced peritonitis and lipopolysaccharide-induced lung injury, Treg cells increased early in resolution, and Treg cell depletion decreased efferocytosis. In advanced atherosclerosis, where defective efferocytosis drives disease progression, Treg cell expansion improved efferocytosis. Mechanistic studies revealed the following sequence: (1) Treg cells secreted interleukin-13 (IL-13), which stimulated IL-10 production in macrophages; (2) autocrine-paracrine signaling by IL-10 induced Vav1 in macrophages; and (3) Vav1 activated Rac1 to promote apoptotic cell engulfment. In summary, Treg cells promote macrophage efferocytosis during inflammation resolution via a transcellular signaling pathway that enhances apoptotic cell internalization. These findings suggest an expanded role of Treg cells in inflammation resolution and provide a mechanistic basis for Treg-cell-enhancement strategies for non-resolving inflammatory diseases.

The Multifaceted Uses and Therapeutic Advantages of Nanoparticles for Atherosclerosis Research

Nanoparticles are uniquely suited for the study and development of potential therapies against atherosclerosis by virtue of their size, fine-tunable properties, and ability to incorporate therapies and/or imaging modalities. Furthermore, nanoparticles can be specifically targeted to the atherosclerotic plaque, evading off-target effects and/or associated cytotoxicity. There has been a wealth of knowledge available concerning the use of nanotechnologies in cardiovascular disease and atherosclerosis, in particular in animal models, but with a major focus on imaging agents. In fact, roughly 60% of articles from an initial search for this review included examples of imaging applications of nanoparticles. Thus, this review focuses on experimental therapy interventions applied to and observed in animal models. Particular emphasis is placed on how nanoparticle materials and properties allow researchers to learn a great deal about atherosclerosis. The objective of this review was to provide an update for nanoparticle use in imaging and drug delivery studies and to illustrate how nanoparticles can be used for sensing and modelling, for studying fundamental biological mechanisms, and for the delivery of biotherapeutics such as proteins, peptides, nucleic acids, and even cells all with the goal of attenuating atherosclerosis. Furthermore, the various atherosclerosis processes targeted mainly for imaging studies have been summarized in the hopes of inspiring new and exciting targeted therapeutic and/or imaging strategies.

Regulation of pro- and anti-atherogenic cytokines

Despite advances in prevention and treatment, vascular diseases continue to account for significant morbidity and mortality in the developed world. Incidence is expected to worsen as the number of patients with common co-morbidities linked with atherosclerotic vascular disease, such as obesity and diabetes, continues to increase, reaching epidemic proportions. Atherosclerosis is a lipid-driven vascular inflammatory disease involving multiple cell types in various stages of inflammation, activation, apoptosis, and necrosis. One commonality among these cell types is that they are activated and communicate with each other in a paracrine fashion via a complex network of cytokines. Cytokines mediate atherogenesis by stimulating expression of numerous proteins necessary for induction of a host of cellular responses, including inflammation, extravasation, proliferation, apoptosis, and matrix production. Cytokine expression is regulated by a number of transcriptional and post-transcriptional mechanisms. In this context, proteins that control and fine-tune cytokine expression can be considered key players in development of atherosclerosis and also represent targets for rational drug therapy to combat this disease. This review will describe the cellular and molecular mechanisms that drive atherosclerotic plaque progression and present key cytokines that participate in this process. We will also describe RNA binding proteins that mediate cytokine mRNA stability and regulate cytokine abundance. Identification and characterization of the cytokines and proteins that regulate their abundance are essential to our ability to identify therapeutic approaches to ameliorate atherosclerotic vascular disease.

Non-coding RNA regulation of T cell biology: Implications for age-associated cardiovascular diseases

Prevalence of age-associated cardiovascular diseases (CVD) has dramatically increased as a result of improvements in life expectancy. Chronic inflammation is a shared pathophysiological feature of age-associated CVDs, indicating a role for the immune system in the onset and development of CVDs. Indeed, ageing elicits profound changes in both the cardiovascular and immune system, especially in the T cell compartment. Although such changes have been well described at the cellular level, the molecular mechanisms underlying immune-mediated cardiovascular ageing remain largely unexplored. Non-coding RNAs (ncRNAs) comprise a heterogeneous family of RNA transcripts that regulate gene expression at the epigenetic, transcriptional, post-transcriptional, and post-translational levels. Non-coding RNAs have recently emerged as master modulators of T cell immunity. In this review, the state-of-the-art knowledge on ncRNA regulatory effects over T cell differentiation, function, and ageing in the context of age-associated CVDs, such as atherosclerosis, acute coronary syndromes, and heart failure, is discussed.

Loss of Macrophage Low-Density Lipoprotein Receptor-Related Protein 1 Confers Resistance to the Antiatherogenic Effects of Tumor Necrosis Factor-α Inhibition

OBJECTIVE

Antiatherosclerotic effects of tumor necrosis factor-α (TNF-α) blockade in patients with systemic inflammatory states are not conclusively demonstrated, which suggests that effects depend on the cause of inflammation. Macrophage LRP1 (low-density lipoprotein receptor-related protein 1) and apoE contribute to inflammation through different pathways. We studied the antiatherosclerosis effects of TNF-α blockade in hyperlipidemic mice lacking either LRP1 (MΦLRP1(-/-)) or apoE from macrophages.

APPROACH AND RESULTS

Lethally irradiated low-density lipoprotein receptor (LDLR)(-/-) mice were reconstituted with bone marrow from either wild-type, MΦLRP1(-/-), apoE(-/-) or apoE(-/-)/MΦLRP1(-/-)(DKO) mice, and then treated with the TNF-α inhibitor adalimumab while fed a Western-type diet. Adalimumab reduced plasma TNF-α concentration, suppressed blood ly6C(hi) monocyte levels and their migration into the lesion, and reduced lesion cellularity and inflammation in both wild-type→LDLR(-/-) and apoE(-/-)→LDLR(-/-) mice. Overall, adalimumab reduced lesion burden by 52% to 57% in these mice. Adalimumab reduced TNF-α and blood ly6C(hi) monocyte levels in MΦLRP1(-/-)→LDLR(-/-) and DKO→LDLR(-/-) mice, but it did not suppress ly6C(hi) monocyte migration into the lesion or atherosclerosis progression.

CONCLUSIONS

Our results show that TNF-α blockade exerts antiatherosclerotic effects that are dependent on the presence of macrophage LRP1.

Heat-killed Staphylococcus aureus reduces atherosclerosis by inducing anti-inflammatory macrophages

BACKGROUND

Staphylococcus aureus cell wall components can induce IL-10 responses by immune cells, which may be atheroprotective. Therefore, in this study, we investigated whether heat-killed S. aureus (HK-SA) could inhibit the development of atherosclerosis.

METHODS

Atherosclerosis-susceptible LDL receptor-deficient mice were administered intraperitoneal HK-SA twice weekly and fed a Western-type diet for 6 weeks.

RESULTS

HK-SA administration resulted in a 1.6-fold increase in IL-10 production by peritoneal macrophages and splenocytes, and a 12-fold increase in serum IL-10 levels. Moreover, aortic plaque ICAM-1, VCAM-1 and CCL2 expression levels were significantly downregulated by on average 40%. HK-SA-treated mice had reduced numbers of inflammatory Ly-6C(hi) monocytes as well as Th1 and Th17 cells in the circulation and spleen, respectively. Attenuated leucocyte recruitment resulted in a significant inhibition of macrophage and T cell infiltration in atherosclerotic plaques, culminating in a significant 34% reduction in the development of atherosclerosis. To determine the effects of intraperitoneal HK-SA treatment, we stimulated macrophages with HK-SA in vitro. This resulted in a significant toll-like receptor 2 (TLR2)-dependent increase in IL-10, arginase-1, iNOS, TNF-α, PD-L1, CCL22 and indoleamine 2,3-dioxygenase expression. It was found that phosphoinositide 3-kinase crucially determined the balance of pro- and anti-inflammatory gene expression. The HK-SA-induced macrophage phenotype resembled M2b-like immunoregulatory macrophages.

CONCLUSIONS

We have shown that HK-SA treatment induces strong anti-inflammatory IL-10 responses by macrophages, which are largely dependent on TLR2 and PI3K, and protects against the development of atherosclerosis. Commensalism with S. aureus could thus reduce cardiovascular events.

Targeted Interleukin-10 Nanotherapeutics Developed with a Microfluidic Chip Enhance Resolution of Inflammation in Advanced Atherosclerosis

Inflammation is an essential protective biological response involving a coordinated cascade of signals between cytokines and immune signaling molecules that facilitate return to tissue homeostasis after acute injury or infection. However, inflammation is not effectively resolved in chronic inflammatory diseases such as atherosclerosis and can lead to tissue damage and exacerbation of the underlying condition. Therapeutics that dampen inflammation and enhance resolution are currently of considerable interest, in particular those that temper inflammation with minimal host collateral damage. Here we present the development and efficacy investigations of controlled-release polymeric nanoparticles incorporating the anti-inflammatory cytokine interleukin 10 (IL-10) for targeted delivery to atherosclerotic plaques. Nanoparticles were nanoengineered via self-assembly of biodegradable polyester polymers by nanoprecipitation using a rapid micromixer chip capable of producing nanoparticles with retained IL-10 bioactivity post-exposure to organic solvent. A systematic combinatorial approach was taken to screen nanoparticles, resulting in an optimal bioactive formulation from in vitro and ex vivo studies. The most potent nanoparticle termed Col-IV IL-10 NP22 significantly tempered acute inflammation in a self-limited peritonitis model and was shown to be more potent than native IL-10. Furthermore, the Col-IV IL-10 nanoparticles prevented vulnerable plaque formation by increasing fibrous cap thickness and decreasing necrotic cores in advanced lesions of high fat-fed LDLr(-/-) mice. These results demonstrate the efficacy and pro-resolving potential of this engineered nanoparticle for controlled delivery of the potent IL-10 cytokine for the treatment of atherosclerosis.

Regulatory T cells in cardiovascular diseases

Inflammation is essential in the initial development and progression of many cardiovascular diseases involving innate and adaptive immune responses. The role of CD4(+)CD25(+)FOXP3(+) regulatory T (TREG) cells in the modulation of inflammation and immunity has received increasing attention. Given the important role of TREG cells in the induction and maintenance of immune homeostasis and tolerance, dysregulation in the generation or function of TREG cells can trigger abnormal immune responses and lead to pathology. A wealth of evidence from experimental and clinical studies has indicated that TREG cells might have an important role in protecting against cardiovascular disease, in particular atherosclerosis and abdominal aortic aneurysm. In this Review, we provide an overview of the roles of TREG cells in the pathogenesis of a number of cardiovascular diseases, including atherosclerosis, hypertension, ischaemic stroke, abdominal aortic aneurysm, Kawasaki disease, pulmonary arterial hypertension, myocardial infarction and remodelling, postischaemic neovascularization, myocarditis and dilated cardiomyopathy, and heart failure. Although the exact molecular mechanisms underlying the cardioprotective effects of TREG cells are still to be elucidated, targeted therapies with TREG cells might provide a promising and novel future approach to the prevention and treatment of cardiovascular diseases.

Anti-inflammatory immune skewing is atheroprotective: Apoe−/−FcγRIIb−/− mice develop fibrous carotid plaques

Background

Stroke, caused by carotid plaque rupture, is a major cause of death in the United States. Whereas vulnerable human plaques have higher Fc receptor (FcγR) expression than their stable counterparts, how FcγR expression impacts plaque histology is unknown. We investigated the role of FcγRIIb in carotid plaque development and stability in apolipoprotein (Apo)e^−/− and Apoe^−/−FcγRIIb^−/− double knockout (DKO) animals.

Methods and Results

Plaques were induced by implantation of a shear stress‐modifying cast around the carotid artery. Plaque length and stenosis were followed longitudinally using ultrasound biomicroscopy. Immune status was determined by flow cytometry, cytokine release, immunoglobulin G concentration and analysis of macrophage polarization both in plaques and in vitro. Surprisingly, DKO animals had lower plaque burden in both carotid artery and descending aorta. Plaques from Apoe^−/− mice were foam‐cell rich and resembled vulnerable human specimens, whereas those from DKO mice were fibrous and histologically stable. Plaques from DKO animals expressed higher arginase 1 (Arg‐1) and lower inducible nitric oxide synthase (iNOS), indicating the presence of M2 macrophages. Analysis of blood and cervical lymph nodes revealed higher interleukin (IL)‐10, immune complexes, and regulatory T cells (T_regs) and lower IL‐12, IL‐1β, and tumor necrosis factor alpha (TNF‐α) in DKO mice. Similarly, in vitro stimulation produced higher IL‐10 and Arg‐1 and lower iNOS, IL‐1β, and TNF‐α in DKO versus Apoe^−/− macrophages. These results define a systemic anti‐inflammatory phenotype.

Conclusions

We hypothesized that removal of FcγRIIb would exacerbate atherosclerosis and generate unstable plaques. However, we found that deletion of FcγRIIb on a congenic C57BL/6 background induces an anti‐inflammatory T_reg/M2 polarization that is atheroprotective.

AAV2/8-humanFOXP3 gene therapy shows robust anti-atherosclerosis efficacy in LDLR-KO mice on high cholesterol diet

Inflammation is a key etiologic component in atherogenesis. Previously we demonstrated that adeno-associated virus (AAV) 2/8 gene delivery of Netrin1 inhibited atherosclerosis in the low density lipoprotein receptor knockout mice on high-cholesterol diet (LDLR-KO/HCD). One important finding from this study was that FOXP3 was strongly up-regulated in these Netrin1-treated animals, as FOXP3 is an anti-inflammatory gene, being the master transcription factor of regulatory T cells. These results suggested that the FOXP3 gene might potentially be used, itself, as an agent to limit atherosclerosis. To test this hypothesis AAV2/8 (AAV)/hFOXP3 or AAV/Neo (control) gene therapy virus were tail vein injected into the LDLR-KO/HCD animal model. It was found that hFOXP3 gene delivery was associated with significantly lower HCD-induced atherogenesis, as measured by larger aortic lumen cross sectional area, thinner aortic wall thickness, and lower aortic systolic blood velocity compared with Neo gene-HCD-treated controls. Moreover these measurements taken from the hFOXP3/HCD-treated animals very closely matched those measurements taken from the normal diet (ND) control animals. These data strongly suggest that AAV/hFOXP3 delivery gave a robust anti-atherosclerosis therapeutic effect and further suggest that FOXP3 be examined more stringently as a therapeutic gene for clinical use.

AAV-mediated gene therapy for atherosclerosis

The prognosis of patients with coronary artery disease and stroke has improved substantially over the last decade as a result of advances in primary and secondary preventive care as well as novel interventional approaches, including the development of drug-eluting stents and balloons. Despite this progress, however, cardiovascular disease remains the leading cause of death in industrialized nations. Sustained efforts to elucidate the underlying mechanisms of atherogenesis, reperfusion-induced cardiac injury, and ischemic heart failure have led to the identification of several target genes as key players in the development and progression of atherosclerotic vascular disease. This knowledge has now enabled genetic therapeutic modulation not only for inherited diseases with a single gene defect, such as familial hypercholesterolemia, but also for multifactorial disorders. This review will focus on approaches in adeno-associated viral (AAV)-mediated gene therapy for atherosclerosis and its long-term sequelae.

Cytokines in atherosclerosis: Key players in all stages of disease and promising therapeutic targets

Atherosclerosis, a chronic inflammatory disorder of the arteries, is responsible for most deaths in westernized societies with numbers increasing at a marked rate in developing countries. The disease is initiated by the activation of the endothelium by various risk factors leading to chemokine-mediated recruitment of immune cells. The uptake of modified lipoproteins by macrophages along with defective cholesterol efflux gives rise to foam cells associated with the fatty streak in the early phase of the disease. As the disease progresses, complex fibrotic plaques are produced as a result of lysis of foam cells, migration and proliferation of vascular smooth muscle cells and continued inflammatory response. Such plaques are stabilized by the extracellular matrix produced by smooth muscle cells and destabilized by matrix metalloproteinase from macrophages. Rupture of unstable plaques and subsequent thrombosis leads to clinical complications such as myocardial infarction. Cytokines are involved in all stages of atherosclerosis and have a profound influence on the pathogenesis of this disease. This review will describe our current understanding of the roles of different cytokines in atherosclerosis together with therapeutic approaches aimed at manipulating their actions.

The influence of dysfunctional signaling and lipid homeostasis in mediating the inflammatory responses during atherosclerosis

Atherosclerosis, the underlying cause of myocardial infarction and thrombotic cerebrovascular events, is responsible for the majority of deaths in westernized societies. Mortality from this disease is also increasing at a marked rate in developing countries due to the acquisition of a westernized lifestyle accompanied with elevated rates of obesity and diabetes. Atherosclerosis is recognized as a chronic inflammatory disorder associated with lipid accumulation and the development of fibrotic plaques within the walls of medium and large arteries. A range of immune cells, such as macrophages and T-lymphocytes, through the action of various cytokines, such as interleukins-1 and -33, transforming growth factor-β and interferon-γ, orchestrates the inflammatory response in this disease. The disease is also characterized by marked dysfunction in lipid homeostasis and signaling pathways that control the inflammatory response. This review will discuss the molecular basis of atherosclerosis with particular emphasis on the roles of the immune cells and cytokines along with the dysfunctional lipid homeostasis and cell signaling associated with this disease.

Targeted nanoparticles containing the proresolving peptide Ac2-26 protect against advanced atherosclerosis in hypercholesterolemic mice

Chronic, nonresolving inflammation is a critical factor in the clinical progression of advanced atherosclerotic lesions. In the normal inflammatory response, resolution is mediated by several agonists, among which is the glucocorticoid-regulated protein called annexin A1. The proresolving actions of annexin A1, which are mediated through its receptor N-formyl peptide receptor 2 (FPR2/ALX), can be mimicked by an amino-terminal peptide encompassing amino acids 2-26 (Ac2-26). Collagen IV (Col IV)-targeted nanoparticles (NPs) containing Ac2-26 were evaluated for their therapeutic effect on chronic, advanced atherosclerosis in fat-fed Ldlr(-/-) mice. When administered to mice with preexisting lesions, Col IV-Ac2-26 NPs were targeted to lesions and led to a marked improvement in key advanced plaque properties, including an increase in the protective collagen layer overlying lesions (which was associated with a decrease in lesional collagenase activity), suppression of oxidative stress, and a decrease in plaque necrosis. In mice lacking FPR2/ALX in myeloid cells, these improvements were not seen. Thus, administration of a resolution-mediating peptide in a targeted NP activates its receptor on myeloid cells to stabilize advanced atherosclerotic lesions. These findings support the concept that defective inflammation resolution plays a role in advanced atherosclerosis, and suggest a new form of therapy.

Cytokines and Immune Responses in Murine Atherosclerosis

Atherosclerosis is an inflammatory disease of the vessel wall characterized by activation of the innate immune system, with macrophages as the main players, as well as the adaptive immune system, characterized by a Th1-dominant immune response. Cytokines play a major role in the initiation and regulation of inflammation. In recent years, many studies have investigated the role of these molecules in experimental models of atherosclerosis. While some cytokines such as TNF or IFNγ clearly had atherogenic effects, others such as IL-10 were found to be atheroprotective. However, studies investigating the different cytokines in experimental atherosclerosis revealed that the cytokine system is complex with both disease stage-dependent and site-specific effects. In this review, we strive to provide an overview of the main cytokines involved in atherosclerosis and to shed light on their individual role during atherogenesis.

Interleukin-10 protects against atherosclerosis by modulating multiple atherogenic macrophage function

Atherosclerosis is primarily a disorder of lipid metabolism, but there is also a prominent chronic inflammatory component that drives the atherosclerotic lesion progression in the artery wall. During hyperlipidaemic conditions, there is a rapid influx of circulating monocytes into the atherosclerosis-prone areas of the arterial intima. These infiltrated monocytes differentiate into macrophages and take up the atherogenic lipoproteins in the intima of the vessel wall that have been modified within the lesion environment. Interleukin (IL)-10 is a prototypic anti-inflammatory cytokine made primarily by the macrophages and Th2 subtype T lymphocytes. In terms of atherosclerosis its major roles include inhibition of macrophage activation as well as inhibition of matrix metalloproteinase, pro-inflammatory cytokines and cyclooxygenase-2 expression in lipid-loaded and activated macrophage foam cells. Recent discoveries suggest another important role of IL-10 in atherosclerosis: its ability to alter lipid metabolism in macrophages. The current review will highlight the present knowledge on multiple ways in which IL-10 mediates atherosclerosis. As macrophages play a critical role in all stages of atherosclerosis, the review will concentrate on how IL-10 regulates the activities of macrophages that are especially important in the development of atherosclerosis.

AAV2/8-hSMAD3 gene delivery attenuates aortic atherogenesis, enhances Th2 response without fibrosis, in LDLR-KO mice on high cholesterol diet

Background

Inflammation is a key etiologic component in atherogenesis and transforming growth factor beta 1 (TGFβ1) is a well known anti-inflammatory cytokine which potentially might be used to limit it. Yet TGFβ1 is pleiomorphic, causing fibrosis, cell taxis, and under certain circumstances, can even worsen inflammation. SMAD3 is an important member of TGFβ1′s signal transduction pathway, but is a fully intracellular protein.

Objectives

With the hope of attenuating TGFβ1′s adverse systemic effects (eg. fibrosis) and accentuating its anti-inflammatory activity, we proposed the use of human (h)SMAD3 as an intracellular substitute for TGFβ1.

Study design

To test this hypothesis adeno-associated virus type 2/8 (AAV)/hSMAD3 or AAV/Neo (control) was tail vein injected into the low density lipoprotein receptor knockout (LDLR-KO) mice, then placed on a high-cholesterol diet (HCD).

Results

The hSMAD3 delivery was associated with significantly lower atherogenesis as measured by larger aortic cross sectional area, thinner aortic wall thickness, and lower aortic systolic blood velocity compared with Neo gene-treated controls. HSMAD3 delivery also resulted in fewer aortic macrophages by immunohistochemistry for CD68 and ITGAM, and quantitative reverse transcriptase polymerase chain reaction analysis of EMR and ITGAM. Overall, aortic cytokine expression showed an enhancement of Th2 response (higher IL-4 and IL-10); while Th1 response (IL-12) was lower with hSMAD3 delivery. While TGFβ1 is often associated with increased fibrosis, AAV/hSMAD3 delivery exhibited no increase of collagen 1A2 or significantly lower 2A1 expression in the aorta compared with Neo-delivery. Connective tissue growth factor (CTGF), a mediator of TGFβ1/SMAD3-induced fibrosis, was unchanged in hSMAD3-delivered aortas. In the liver, all three of these genes were down-regulated by hSMAD3 gene delivery.

Conclusion

These data strongly suggest that AAV/hSMAD3 delivery gave anti-atherosclerosis therapeutic effect without the expected undesirable effect of TGFβ1-associated fibrosis.

Comparison of efficacy of the disease-specific LOX1- and constitutive cytomegalovirus-promoters in expressing interleukin 10 through adeno-associated virus 2/8 delivery in atherosclerotic mice

The development of gene therapy vectors for treating diseases of the cardiovascular system continues at a steady pace. Moreover, in the field of gene therapy the utility of "disease-specific promoters" has strong appeal. Many therapeutic genes, including transforming growth factor beta 1 or interleukin 10, are associated to adverse effects. The use of a disease-specific promoter might minimize toxicity. The lectin-like oxidized low density lipoprotein receptor 1 is a marker of cardiovascular disease and a potential therapeutic target. The lectin-like oxidized low density lipoprotein receptor 1 is known to be up-regulated early during disease onset in a number of cell types at the sites where the disease will be clinically evident. In this study an adeno-associated virus-2 DNA vector (AAV2) using the AAV8 capsid, and containing the full length The lectin-like oxidized low density lipoprotein receptor 1 promoter, was generated and assayed for its ability to express human interleukin 10 in low density lipoprotein receptor knockout mice on high cholesterol diet. The cytomegalovirus early promoter was used for comparison in a similarly structured vector. The two promoters were found to have equal efficacy in reducing atherogenesis as measured by aortic systolic blood velocity, aortic cross sectional area, and aortic wall thickness. This is the first head-to-head comparison of a constitutive with a disease-specific promoter in a therapeutic context. These data strongly suggest that the use of a disease-specific promoter is appropriate for therapeutic gene delivery.

Role of peroxisome proliferator-activated receptor α in atherosclerosis

Atherosclerosis is an inflammatory disease involving the immune response. In addition to lowering the cholesterol level, the peroxisome proliferator-activated receptor α (PPAR-α) can prevent atherosclerosis via its pleiotropic anti-inflammatory effects. However, the role of PPAR-α in modulating inflammatory progression of atherosclerosis has rarely been studied. Thus, we aimed to investigate the role of PPAR-α in atherosclerosis by evaluating the expression of inflammatory cytokines induced by PPAR-α in an in vivo rabbit model. New Zealand White rabbits were randomly divided into 5 groups: control, high-fat diet + balloon injury, high-fat diet + balloon injury + placebo, high-fat diet + balloon injury + fenofibrate, and high-fat diet + balloon injury + WY-14643. The femoral arteries of rabbits were balloon-injured after initiation of the high-fat diet and before administration of fenofibrate, WY-14643 or placebo solution. Atherosclerosis was induced by high-fat diet and balloon angioplasty, and the vessel wall lumen occlusion was determined by measuring the stenosis rate. PPAR-α gene expression was examined by quantitative polymerase chain reaction analysis. The cellular localization and distribution of PPAR-α was observed by immunohistochemistry, and its protein level was assessed by western blot analysis. The production of interleukin-10 (IL-10), tumor necrosis factor-α (TNF-α) and P-selectin, which are major inflammatory factors involved in atherosclerosis, was monitored by an enzyme-linked immunosorbent assay (ELISA). Treatment with PPAR-α agonists (fenofibrate or WY-14643) reduced the vascular occlusion rate, as compared to the high-fat diet + balloon injury and the placebo groups. Furthermore, the expression of PPAR-α at both the protein and the mRNA level was increased in the fenofibrate and WY-14643 groups. According to the results, the TNF-α and P-selectin levels were reduced in the fenofibrate and WY-14643 groups. These results suggest that PPAR-α activation can attenuate the effects of atherosclerosis by inhibiting the expression of major inflammatory factors in a rabbit atherosclerosis model.

Atmospheric ultrafine particles promote vascular calcification via the NF-κB signaling pathway

Exposure to atmospheric fine particulate matter (PM(2.5)) is a modifiable risk factor of cardiovascular disease. Ultrafine particles (UFP, diameter <0.1 μm), a subfraction of PM(2.5), promote vascular oxidative stress and inflammatory responses. Epidemiologic studies suggest that PM exposure promotes vascular calcification. Here, we assessed whether UFP exposure promotes vascular calcification via NF-κB signaling. UFP exposure at 50 μg/ml increased alkaline phosphatase (ALP) activity by 4.4 ± 0.2-fold on day 3 (n = 3, P < 0.001) and matrix calcification by 3.5 ± 1.7-fold on day 10 (n = 4, P < 0.05) in calcifying vascular cells (CVC), a subpopulation of vascular smooth muscle cells with osteoblastic potential. Treatment of CVC with conditioned media derived from UFP-treated macrophages (UFP-CM) also led to an increase in ALP activities and matrix calcification. Furthermore, both UFP and UFP-CM significantly increased NF-κB activity, and cotreatment with an NF-κB inhibitor, JSH23, attenuated both UFP- and UFP-CM-induced ALP activity and calcification. When low-density lipoprotein receptor-null mice were exposed to UFP at 359.5 μg/m(3) for 10 wk, NF-κB activation and vascular calcification were detected in the regions of aortic roots compared with control filtered air-exposed mice. These findings suggest that UFP promotes vascular calcification via activating NF-κB signaling.

Dual AAV/IL-10 Plus STAT3 Anti-Inflammatory Gene Delivery Lowers Atherosclerosis in LDLR KO Mice, but without Increased Benefit

Both IL-10 and STAT3 are in the same signal transduction pathway, with IL-10-bound IL10 receptor (R) acting through STAT3 for anti-inflammatory effect. To investigate possible therapeutic synergism, we delivered both full-length wild-type human (h) STAT3 and hIL-10 genes by separate adenoassociated virus type 8 (AAV8) tail vein injection into LDLR KO on HCD. Compared to control Neo gene-treated animals, individual hSTAT3 and hIL-10 delivery resulted in significant reduction in atherogenesis, as determined by larger aortic lumen size, thinner aortic wall thickness, and lower blood velocity (all statistically significant). However, dual hSTAT3/hIL-10 delivery offered no improvement in therapeutic effect. Plasma cholesterol levels in dual hSTAT3/hIL-10-treated animals were statistically higher compared to hIL-10 alone. While no advantage was seen in this case, we consider that the dual gene approach has intrinsic merit, but properly chosen partnered genes must be used.

Effects of macrophage-specific adiponectin expression on lipid metabolism in vivo

Epidemiological studies have associated low circulating levels of the adipokine adiponectin with multiple metabolic disorders, including metabolic syndrome, obesity, insulin resistance, type II diabetes, and cardiovascular disease. Recently, we reported that adiponectin selectively overexpressed in mouse macrophages can improve insulin sensitivity and protect against inflammation and atherosclerosis. To further investigate the role of adiponectin and macrophages on lipid and lipometabolism in vivo, we engineered the expression of adiponectin in mouse macrophages (Ad-TG mice) and examined effects on plasma lipoproteins and on the expression levels of genes involved in lipoprotein metabolism in tissues. Compared with the wild-type (WT) mice, Ad-TG mice exhibited significantly lower levels of plasma total cholesterol (-21%, P < 0.05) due to significantly decreased LDL (-34%, P < 0.05) and VLDL (-32%, P < 0.05) cholesterol concentrations together with a significant increase in HDL cholesterol (+41%, P < 0.05). Further studies investigating potential mechanisms responsible for the change in lipoprotein cholesterol profile revealed that adiponectin-producing macrophages altered expression of key genes in liver tissue, including apoA1, apoB, apoE, the LDL receptor, (P < 0.05), and ATP-binding cassette G1 (P < 0.01). In addition, Ad-TG mice also exhibited higher total and high-molecular-weight adipnection levels in plasma and increased expression of the anti-inflammatory cytokine IL-10 as well as a decrease in the proinflammatory cytokine IL-6 in adipose tissue. These results indicate that macrophages engineered to produce adiponectin can influence in vivo gene expression in adipose tissue in a manner that reduces inflammation and macrophage infiltration and in liver tissue in a manner that alters the circulating lipoprotein profile, resulting in a decrease in VLDL and LDL and an increase in HDL cholesterol. The data support further study addressing the use of genetically manipulated macrophages as a novel therapeutic approach for treatment of cardiometabolic disease.

Intranasal delivery of E-selectin reduces atherosclerosis in ApoE-/- mice

Mucosal tolerance to E-selectin prevents stroke and protects against ischemic brain damage in experimental models of stroke studying healthy animals or spontaneously hypertensive stroke-prone rats. A reduction in inflammation and neural damage was associated with immunomodulatory or “tolerogenic” responses to E-selectin. The purpose of the current study on ApoE deficient mice is to assess the capacity of this stroke prevention innovation to influence atherosclerosis, a major underlying cause for ischemic strokes; human E-selectin is being translated as a potential clinical prevention strategy for secondary stroke. Female ApoE−/− mice received intranasal delivery of E-selectin prior to (pre-tolerization) or simultaneously with initiation of a high-fat diet. After 7 weeks on the high-fat diet, lipid lesions in the aorta, serum triglycerides, and total cholesterol were assessed as markers of atherosclerosis development. We also assessed E-selectin-specific antibodies and cytokine responses, in addition to inflammatory responses that included macrophage infiltration of the aorta and altered gene expression profiles of aortic mRNA. Intranasal delivery of E-selectin prior to initiation of high-fat chow decreased atherosclerosis, serum total cholesterol, and expression of the leucocyte chemoattractant CCL21 that is typically upregulated in atherosclerotic lesions of ApoE−/− mice. This response was associated with the induction of E-selectin specific cells producing the immunomodulatory cytokine IL-10 and immunosuppressive antibody isotypes. Intranasal administration of E-selectin generates E-selectin specific immune responses that are immunosuppressive in nature and can ameliorate atherosclerosis, a major risk factor for ischemic stroke. These results provide additional preclinical support for the potential of induction of mucosal tolerance to E-selectin to prevent stroke.

Helper-dependent adenoviral vector achieves prolonged, stable expression of interleukin-10 in rabbit carotid arteries but does not limit early atherogenesis

Vascular gene therapy could potentially complement or replace current therapies for human atherosclerosis, while avoiding their side effects. However, development of vascular gene therapy is limited by lack of a useful vector. Helper-dependent adenovirus (HDAd) shows promise to overcome this barrier because, unlike first-generation adenovirus, HDAd achieves durable transgene expression in the artery wall with minimal inflammation. To begin to test whether HDAd, delivered to the artery wall, can limit atherosclerosis we constructed HDAd that expresses rabbit interleukin (IL)-10, a potent atheroprotective cytokine, and tested its activity in a rabbit model of early carotid atherogenesis. HDAd expressed immunoreactive, active IL-10 in vitro. In contrast to other HDAd-expressed transgenes, IL-10 expression from HDAd increased significantly between 3 days and 2 weeks after infusion and remained stable for at least 8 weeks. Rising, persistent IL-10 expression was associated with relative persistence of HDAdIL-10 genomes 4 weeks after infusion, compared with HDAdNull genomes. Surprisingly, IL-10 expression had no significant effects on atherosclerotic lesion size, macrophage content, or expression of either adhesion molecules or atherogenic cytokines. These results might be due to inadequate protein expression in vivo or lack of suitability of this rabbit model to reveal IL-10 therapeutic effects. IL-10 remains a promising agent for vascular gene therapy and HDAd remains a promising vector; however, proof of efficacy of HDAdIL-10 is elusive. Future preclinical studies will be aimed at increasing IL-10 expression levels and improving the sensitivity of this animal model to detect atheroprotective effects.

Influenza vaccination promotes stable atherosclerotic plaques in apoE knockout mice

OBJECTIVE

Current evidence suggests a relationship between seasonal Influenza viral infection and cardiovascular disease (CVD). Experimental animals inoculated with Influenza A virus have shown to develop thrombotic complications similar to those seen in humans. Conversely, several epidemiological studies and clinical trials have suggested that Influenza vaccination may have a protective effect on CVD. However, the potential mechanisms behind this protective effect remain unstudied. We aimed to study the effect of Influenza vaccination on atherosclerotic plaque development in apoE(-/-) mice.

METHODS AND RESULTS

The effect of immunization with increasing doses of Influenza vaccine (0.38, 1.8, 9 and 45 μg/0.5 mL Vaxigrip®, Sanofi-Aventis) on atherogenesis was compared with that of animals immunized with Pneumo23® (pneumococcus vaccine, Sanofi-Aventis) and control group inoculated with phosphate buffered saline (PBS). Animals vaccinated with 45 μg/0.5 mL Vaxigrip®, (the same dose used to immunize humans adults against Influenza) developed smaller atherosclerotic lesions with lower lipid content but richer in smooth muscle cells and collagen when compared with control animals. Concomitantly, they showed lower levels of interferon gamma (IFNγ), interleukin (IL)-2 and tumor necrosis factor alpha (TNFα) but higher levels of IL-4. Furthermore, we found increased levels of anti-Influenza immunoglobulin (Ig) G1 or anti-Pneumo23® IgM specific antibodies in a time and dose dependent fashion in animals immunized with these vaccines.

CONCLUSIONS

These results indicate that vaccination against Influenza may protect against the development of CVD by promoting smaller and stable atherosclerotic plaques and by inducing atheroprotective immune responses.

The effect of interleukin-10 on apoptosis in macrophages stimulated by oxLDL

Marked anti-atheromatous effects of the anti-inflammatory cytokine interleukin-10 (IL-10) were observed in several lipid-driven animal models of arteriosclerosis. We have previously demonstrated that IL-10 significantly inhibited lipid uptake in macrophages induced by oxLDL (Wang et al., 2008; Yang et al., 2008b). In this study, we investigated whether IL-10 affects the apoptosis related gene BCL2L11 and BMF expression in macrophages treated with oxLDL from THP-1 cells, which served as macrophage models. Cell apoptosis assays were performed by flow cytometry. Expression of the apoptosis related genes BCL2L11 and BMF mRNA was quantified by real-time RT-PCR (mRNA expression) and Western blotting (protein expression). IL-10 markedly blocked oxLDL induced cells undergoing early stage apoptosis. In the foam cell group, as compared with the macrophage group, the percentage of apoptosis increased by 100%. Here the expression of BCL2L11 was 45% (mRNA) and 41% (protein) elevated, while the expression of BMF was 54% (mRNA) and 44% (protein) elevated. When macrophages were co-stimulated by 100mg/l oxLDL and 20 μg/l IL-10 for 24h, compared with the foam cell group, the percentage of the apoptosis decreased by 21%, the expression of apoptosis related gene BMF was inhibited, the expression of mRNA and protein was both depressed by 23% and 20%, respectively, but the BCL2L11 expression was unchanged. These results may explain why decrement of early stage apoptosis cells was observed during co-stimulation and raise the possibility that IL-10 reduces foam cell undergoing apoptosis partly through down-regulating the expression of BMF, which demonstrates a critical role of IL-10 in anti-atherogenesis.

Systemic human Netrin-1 gene delivery by adeno-associated virus type 8 alters leukocyte accumulation and atherogenesis in vivo

Atherosclerosis is an inflammatory disorder of arteries. Atherosclerotic plaque, in its early to intermediate stages, is composed largely of lipid-engorged foam cells. These foam cells are derived from the trafficking of monocytes (Mo) into the arterial intima, attracted to the site by chemoattractants. Given that foam cells are derived from the trafficking of Mo, the use of Netrin-1, an Mo chemorepellent, may be useful in limiting Mo accumulation and subsequent plaque formation. To investigate the potential of Netrin-1 for limiting atherosclerosis, we systemically delivered its human (h) cDNA by adeno-associated virus type 8 (AAV8, single-stranded structure) delivery into low-density lipoprotein receptor knockout (LDLR-/-) mice and placed the animals on a high cholesterol diet (HCD). Compared with control neomycin resistance (Neo) gene delivery/HCD, hNetrin-1 delivery resulted in a significant reduction in plaque formation, as determined by larger aortic lumen size, thinner intima-media thickness and lower blood velocity than the Neo/HCD control (all statistically significant). Indices of monocyte/macrophage (Mo/MΦ) accumulation, CD68, integrin, alpha M (ITGAM) and egf-like module containing, mucin-like, hormone receptor-like 1 (EMR-1), were reduced in hNetrin-1/HCD-treated animal's aortas and spleens compared with Neo/HCD-treated animals. Unexpectedly, CD25 and foxp3 (regulatory T cells (Tregs)) in the aorta were strongly upregulated. This is the first time the Mo/MΦ chemorepellent approach, and specific Netrin-1 gene delivery, has been performed for the reduction of Mo/MΦ burden and atherosclerosis. In addition, Netrin-1 has never before been linked to altered Treg levels. These data strongly suggest that hNetrin-1 gene delivery can reduce Mo/MΦ accumulation, inflammation and subsequent plaque formation.

LDLR-Gene therapy for familial hypercholesterolaemia: problems, progress, and perspectives

Coronary artery diseases (CAD) inflict a heavy economical and social burden on most populations and contribute significantly to their morbidity and mortality rates. Low-density lipoprotein receptor (LDLR) associated familial hypercholesterolemia (FH) is the most frequent Mendelian disorder and is a major risk factor for the development of CAD. To date there is no cure for FH. The primary goal of clinical management is to control hypercholesterolaemia in order to decrease the risk of atherosclerosis and to prevent CAD. Permanent phenotypic correction with single administration of a gene therapeutic vector is a goal still needing to be achieved. The first ex vivo clinical trial of gene therapy in FH was conducted nearly 18 years ago. Patients who had inherited LDLR gene mutations were subjected to an aggressive surgical intervention involving partial hepatectomy to obtain the patient's own hepatocytes for ex vivo gene transfer with a replication deficient LDLR-retroviral vector. After successful re-infusion of transduced cells through a catheter placed in the inferior mesenteric vein at the time of liver resection, only low-level expression of the transferred LDLR gene was observed in the five patients enrolled in the trial. In contrast, full reversal of hypercholesterolaemia was later demonstrated in in vivo preclinical studies using LDLR-adenovirus mediated gene transfer. However, the high efficiency of cell division independent gene transfer by adenovirus vectors is limited by their short-term persistence due to episomal maintenance and the cytotoxicity of these highly immunogenic viruses. Novel long-term persisting vectors derived from adeno-associated viruses and lentiviruses, are now available and investigations are underway to determine their safety and efficiency in preparation for clinical application for a variety of diseases. Several novel non-viral based therapies have also been developed recently to lower LDL-C serum levels in FH patients. This article reviews the progress made in the 18 years since the first clinical trial for gene therapy of FH, with emphasis on the development, design, performance and limitations of viral based gene transfer vectors used in studies to ameliorate the effects of LDLR deficiency.

Immunization with cationized BSA inhibits progression of disease in ApoBec-1/LDL receptor deficient mice with manifest atherosclerosis

Immune responses against modified self-antigens generated by hypercholesterolemia play an important role in atherosclerosis identifying the immune system as a possible novel target for prevention and treatment of cardiovascular disease. It has recently been shown that these immune responses can be modulated by subcutaneous injection of adjuvant. In the present study we immunized 25-week old ApoBec-1/LDL receptor deficient mice with manifest atherosclerosis with adjuvant and two different concentrations of the carrier molecule cationized BSA (cBSA). Plasma levels of Th2-induced apolipoprotein B (apoB)/IgG1 immune complexes were increased in the cBSA immunized groups verifying induction of immunity against a self-antigen. Mice were sacrificed at 36 weeks of age and atherosclerosis was monitored by en face Oil red O staining of the aorta. Immunization with 100 μg cBSA inhibited plaque progression, whereas the lower dose (50 μg) did not. In addition, the higher dose induced a more stable plaque phenotype, indicated by a higher content of collagen and less macrophages and T cells in the plaques. Moreover, there was an increased ratio of Foxp3+/Foxp3⁻ T cells in the circulation suggesting activation of a regulatory T cell response. In conclusion, we show that immunization with cBSA induces an immune response against apoB as well as an activation of Treg cells. This was associated with development of a more stable plaque phenotype and reduced atherosclerosis progression.

Erythropoietin suppresses the formation of macrophage foam cells: role of liver X receptor alpha

BACKGROUND

In addition to the hematopoietic effect of erythropoietin, increasing evidence suggests that erythropoietin also exerts protective effects for cardiovascular diseases. However, the role of erythropoietin and its underlying mechanism in macrophage foam cell formation are poorly understood.

METHODS AND RESULTS

Compared with wild-type specimens, erythropoietin was increased in atherosclerotic aortas of apolipoprotein E-deficient (apoE(-/-)) mice, mainly in the macrophage foam cells of the lesions. Erythropoietin levels in culture medium and macrophages were significantly elevated in response to oxidized low-density lipoprotein in a dose-dependent manner. Furthermore, erythropoietin markedly attenuated lipid accumulation in oxidized low-density lipoprotein-treated macrophages, a result that was due to an increase in cholesterol efflux. Erythropoietin treatment significantly increased ATP-binding cassette transporters (ABC) A1 and ABCG1 mRNA and protein levels without affecting protein expression of scavenger receptors, including scavenger receptor-A, CD36, and scavenger receptor-BI. The upregulation of ABCA1 and ABCG1 by erythropoietin resulted from liver X receptor alpha activation, which was confirmed by its prevention on expression of ABCA1 and ABCG1 after pharmacological or small interfering RNA inhibition of liver X receptor alpha. Moreover, the erythropoietin-mediated attenuation on lipid accumulation was abolished by such inhibition. Finally, reduced lipid accumulation and marked increase in ABCA1 and ABCG1 were demonstrated in erythropoietin-overexpressed macrophages.

CONCLUSIONS

Our data suggest that erythropoietin suppresses foam cell formation via the liver X receptor alpha-dependent upregulation of ABCA1 and ABCG1.

Interleukin-10 overexpression in macrophages suppresses atherosclerosis in hyperlipidemic mice

In atherogenesis, macrophage foam cell formation is modulated by pathways involving both the uptake and efflux of cholesterol. We recently showed that interleukin-10 (IL-10) modulates lipid metabolism by enhancing both uptake and efflux of cholesterol in macrophages. However, the mechanistic details of these properties in vivo have been unclear. Thus, the purpose of this study was to determine whether expression of IL-10 in macrophages would alter susceptibility to atherosclerosis and whether IL-10 exerts its antiatherosclerotic properties by modulating lipid metabolism in macrophages. We utilized a macrophage-specific retroviral vector that allows long-term in vivo expression of IL-10 in macrophages through transplantation of retrovirally transduced bone marrow cells (BMCs). IL-10 expressed by macrophages derived from transduced BMCs inhibited atherosclerosis in LDLR(-/-) mice by reducing cholesteryl ester accumulation in atherosclerotic sites. Experiments with primary macrophages indicated that macrophage source of IL-10 stimulated both the uptake (by up-regulating scavenger receptors) and efflux of cholesterol (by activating the PPARgamma-LXR-ABCA1/ABCG1 pathway), thereby reducing inflammation and apoptosis in atherosclerosis. These findings indicate that BMC-transduced macrophage IL-10 production can act as a strong antiatherogenic agent, and they highlight a novel antiatherosclerotic therapy using a simple, yet effective, stem cell transduction system that facilitates long-term expression of IL-10 in macrophages.

Inhibition of arterial lesion progression in CD16-deficient mice: evidence for altered immunity and the role of IL-10

AIMS

Given the importance of IgG Fc receptors in immune regulation, we hypothesized that Fcg receptor type III (FcgRIII, CD16) plays an important role in atherogenesis. We therefore analysed the formation of arterial lesions in LDL receptor-deficient (LDLR(-/-)) and FcgRIII(-/-)xLDLR(-/-) double knockout mice at three different points up to 24 weeks of exposure to a high-fat diet.

METHODS AND RESULTS

Analysis of Oil Red-O-stained sections revealed no difference in lesion formation between strains after 6 weeks of a high-fat diet, and a modest decrease after 14 weeks in double knockouts relative to LDLR(-/-) controls. After 24 weeks, lesion formation was decreased in the aortic root (30%) and innominate artery (50%) in FcgRIII double knockouts relative to LDLR(-/-) controls. Analysis of peripheral CD4+ T-cells by intracellular flow cytometry from double knockouts after 24 weeks of a high-fat diet revealed statistically significant increases in the percentages of cells producing interferon-gamma, interleukin (IL)-10, and IL-4 relative to controls, differences that were also observed by analyses of whole aortas for cytokine mRNA levels. As determined by flow cytometry, FcgRIII deficiency resulted in an expansion of CD4+ cells and an increase in the CD4 to CD8 ratio. Analysis of plasma anti-oxidized LDL (OxLDL) antibodies by chemiluminescent assay revealed that IgG1 and IgG2c titers to OxLDL were increased in FcgRIII (-/-)xLDLR(-/-) double knockouts relative to LDLR(-/-) controls, while total IgG levels were similar.

CONCLUSION

These results reveal altered immunity in FcgRIII(-/-)xLDLR(-/-) mice and a reduction in lesion formation associated with increased production of IL-10 by an expansion of CD4+ T-cells. The reduction in lesion formation was manifest well after evidence of an immune response to OxLDL, suggesting that FcgRIII contributes to lesion progression in murine atherosclerosis.