Phosphatidylserine liposomes mimic apoptotic cells to attenuate atherosclerosis by expanding polyreactive IgM producing B1a lymphocytes

Inflammation: A Novel Therapeutic Target/Direction in Atherosclerosis

Over the past two decades, the viewpoint of atherosclerosis has been replaced gradually by a lipid-driven, chronic, low-grade inflammatory disease of the arterial wall. Current treatment of atherosclerosis is focused on limiting its risk factors, such as hyperlipidemia or hypertension. However, treatment targeting the inflammatory nature of atherosclerosis is still very limited and deserves further attention to fight atherosclerosis successfully. Here, we review the current development of inflammation and atherosclerosis to discuss novel insights and potential targets in atherosclerosis, and to address drug discovery based on anti-inflammatory strategy in atherosclerotic disease.

CD6 expression has no effect on atherosclerosis in apolipoprotein E-deficient mice

OBJECTIVE

To determine if deficiency of CD6, a cell surface protein on lymphocytes that alters natural antibody production, increases atherosclerosis in ApoE-deficient mice fed a chow or a western-type diet.

RESULTS

We compared cholesterol levels, IgM, B1a cells, and aortic root lesion areas in ApoE-deficient vs. CD6/ApoE double deficient mice. Feeding the high-fat western type diet increased all parameters, except for B1a cell numbers decreased. Sex also had an effect on many parameters with males having increased body weights, higher high density lipoprotein cholesterol, higher B1a cells, but smaller atherosclerotic lesions if chow fed mice; however, this sex effect on atherosclerosis was absent in mice fed the western-type diet. CD6 deficiency had no effect on atherosclerosis in both male and female mice on either diet. Thus, loss of CD6 on lymphocytes did not lead to expected reductions in B1a cells and protective IgM levels, and in turn did not alter atherosclerosis in mice.

Combating atherosclerosis with targeted nanomedicines: recent advances and future prospective

Introduction: Cardiovascular diseases (CVDs) is recognized as the leading cause of mortality worldwide. The increasing prevalence of such disease demands novel therapeutic and diagnostic approaches to overcome associated clinical/social issues. Recent advances in nanotechnology and biological sciences have provided intriguing insights to employ targeted Nanomachines to the desired location as imaging, diagnosis, and therapeutic modalities. Nanomedicines as novel tools for enhanced drug delivery, imaging, and diagnosis strategies have shown great promise to combat cardiovascular diseases.

Methods: In the current study, we intend to review the most recent studies on the nano-based strategies for improved management of CVDs.

Results: A cascade of events results in the formation of atheromatous plaque and arterial stenosis. Furthermore, recent studies have shown that nanomedicines have displayed unique functionalities and provided de novo applications in the diagnosis and treatment of atherosclerosis.

Conclusion: Despite some limitations, nanomedicines hold considerable potential in the prevention, diagnosis, and treatment of various ailments including atherosclerosis. Fewer side effects, amenable physicochemical properties and multi-potential application of such nano-systems are recognized through various investigations. Therefore, it is strongly believed that with targeted drug delivery to atherosclerotic lesions and plaque, management of onset and progression of disease would be more efficient than classical treatment modalities.

Linking autoimmunity to the origin of the adaptive immune system

In jawed vertebrates, the adaptive immune system (AIS) cooperates with the innate immune system (IIS) to protect hosts from infections. Although targeting non-self-components, the AIS also generates self-reactive antibodies which, when inadequately counter-selected, can give rise to autoimmune diseases (ADs). ADs are on the rise in western countries. Why haven’t ADs been eliminated during the evolution of a ∼500 million-year old system? And why have they become more frequent in recent decades? Self-recognition is an attribute of the phylogenetically more ancient IIS and empirical data compellingly show that some self-reactive antibodies, which are classifiable as elements of the IIS rather then the AIS, may protect from (rather than cause) ADs. Here, we propose that the IIS’s self-recognition system originally fathered the AIS and, as a consequence of this relationship, its activity is dampened in hygienic environments. Rather than a mere breakdown or failure of the mechanisms of self-tolerance, ADs might thus arise from architectural constraints.

Opposing roles of B lymphocyte subsets in atherosclerosis

Atherosclerosis is initiated by cholesterol entry into arteries that triggers chronic immune-inflammatory lesions in the vessels. Early lesions are clinically insignificant but advanced complex lesions and vulnerable rupture prone lesions impact on quality of life and can be life threatening. Rupture of vulnerable atherosclerotic lesions initiates thrombotic occlusion of vital arteries precipitating heart attacks and strokes that remain major killers globally despite therapeutic use of statins to lower blood cholesterol levels. Conventional B2 cells are proatherogenic whereas peritoneal Bla cells are atheroprotective. Depletion of B2 cells by administration of mAb to CD20 or to BAFF receptor or in BAFF receptor-deficient mice ameliorates atherosclerosis. B2 cells may promote atherosclerosis by production of IgG, secretion of proinflammatory cytokine TNFα and activation of CD4 T cells. Together these B2 cell mechanisms contribute to generation of rupture-prone vulnerable atherosclerotic plaques characterised by large necrotic cores. In contrast, peritoneal Bla cells protect against atherosclerosis by secretion of natural IgM that scavenges apoptotic cells and oxidised LDL and reduces necrotic cores in atherosclerotic lesions. These atheroprotective effects can be further increased by stimulating Bla cells by administration of apoptotic cells, liposomes of phosphatidylserine abundant on surfaces of apoptotic cell, by mAb to TIM1, a phosphatidylserine receptor expressed by B1a cells and by TLR4-MyD88 activation. Experimental studies of atherosclerosis in mouse models indicate that reductions in atherogenic B2 cells and/or activation of atheroprotective B1a cells protects against atherosclerosis development, findings which have potential for clinical translation to reduce risks of deaths from heart attacks and strokes.

Resolvins suppress tumor growth and enhance cancer therapy

Cancer therapy reduces tumor burden by killing tumor cells, yet it simultaneously creates tumor cell debris that may stimulate inflammation and tumor growth. Sulciner et al. demonstrate that specific resolvins (RvD1, RvD2, and RvE1) inhibit tumor growth and enhance cancer therapy through the clearance of tumor cell debris.

Cancer therapy reduces tumor burden by killing tumor cells, yet it simultaneously creates tumor cell debris that may stimulate inflammation and tumor growth. Thus, conventional cancer therapy is inherently a double-edged sword. In this study, we show that tumor cells killed by chemotherapy or targeted therapy (“tumor cell debris”) stimulate primary tumor growth when coinjected with a subthreshold (nontumorigenic) inoculum of tumor cells by triggering macrophage proinflammatory cytokine release after phosphatidylserine exposure. Debris-stimulated tumors were inhibited by antiinflammatory and proresolving lipid autacoids, namely resolvin D1 (RvD1), RvD2, or RvE1. These mediators specifically inhibit debris-stimulated cancer progression by enhancing clearance of debris via macrophage phagocytosis in multiple tumor types. Resolvins counterregulate the release of cytokines/chemokines, including TNFα, IL-6, IL-8, CCL4, and CCL5, by human macrophages stimulated with cell debris. These results demonstrate that enhancing endogenous clearance of tumor cell debris is a new therapeutic target that may complement cytotoxic cancer therapies.

Heterogeneity of atherosclerotic plaque macrophage origin, phenotype and functions: Implications for treatment

Macrophages are key players in atherosclerotic lesions, regulating the local inflammatory milieu and plaque stability by the secretion of many inflammatory molecules, growth factors and cytokines. Monocytes have long been considered to be the main source of plaque macrophages. However, recent findings provide evidence for proliferation of local macrophages or transdifferentiation from other vascular cells as alternative sources. Recent years of research focused on the further identification and characterisation of macrophage phenotypes and functions. In this review we describe the advances in our understanding of monocyte and macrophage heterogeneity and its implications for specific therapeutic interventions, aiming to reduce the ever growing significant risk of cardiovascular events without any detrimental side effects on the patient's immune response.

Liposomes as colloidal nanovehicles: on the road to success in intravenous drug delivery

The advancement of research in colloidal systems has led to the increased application of this technology in more effective and targeted drug delivery. Nanotechnology enables control over functionality parameters and allows innovations in biodegradable, biocompatible, and stimuli-responsive delivery systems. The first closed bilayer phospholipid system, the liposome system, has been making steady progress over five decades of extensive research and has been efficient in achieving many desirable parameters such as remote drug loading, size-controlling measures, longer circulation half-lives, and triggered release. Liposome-mediated drug delivery has been successful in overcoming obstacles to cellular and tissue uptake of drugs with improved biodistribution in vitro and in vivo. These colloidal nanovehicles have moved on from a mere concept to clinical applications in various drug delivery systems for antifungal, antibiotic, and anticancer drugs.

Nanomedicines for dysfunctional macrophage-associated diseases

Macrophages play vital functions in host inflammatory reaction, tissue repair, homeostasis and immunity. Dysfunctional macrophages have significant pathophysiological impacts on diseases such as cancer, inflammatory diseases (rheumatoid arthritis and inflammatory bowel disease), metabolic diseases (atherosclerosis, diabetes and obesity) and major infections like human immunodeficiency virus infection. In view of this common etiology in these diseases, targeting the recruitment, activation and regulation of dysfunctional macrophages represents a promising therapeutic strategy. With the advancement of nanotechnology, development of nanomedicines to efficiently target dysfunctional macrophages can strengthen the effectiveness of therapeutics and improve clinical outcomes. This review discusses the specific roles of dysfunctional macrophages in various diseases and summarizes the latest advances in nanomedicine-based therapeutics and theranostics for treating diseases associated with dysfunctional macrophages.

Readapting the adaptive immune response - therapeutic strategies for atherosclerosis

Cardiovascular diseases remain a major global health issue, with the development of atherosclerosis as a major underlying cause. Our treatment of cardiovascular disease has improved greatly over the past three decades, but much remains to be done reduce disease burden. Current priorities include reducing atherosclerosis advancement to clinically significant stages and preventing plaque rupture or erosion. Inflammation and involvement of the adaptive immune system influences all these aspects and therefore is one focus for future therapeutic development. The atherosclerotic vascular wall is now recognized to be invaded from both sides (arterial lumen and adventitia), for better or worse, by the adaptive immune system. Atherosclerosis is also affected at several stages by adaptive immune responses, overall providing many opportunities to target these responses and to reduce disease progression. Protective influences that may be defective in diseased individuals include humoral responses to modified LDL and regulatory T cell responses. There are many strategies in development to boost these pathways in humans, including vaccine-based therapies. The effects of various existing adaptive immune targeting therapies, such as blocking critical co-stimulatory pathways or B cell depletion, on cardiovascular disease are beginning to emerge with important consequences for both autoimmune disease patients and the potential for wider use of such therapies. Entering the translation phase for adaptive immune targeting therapies is an exciting and promising prospect.

LINKED ARTICLES

This article is part of a themed section on Targeting Inflammation to Reduce Cardiovascular Disease Risk. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.22/issuetoc and http://onlinelibrary.wiley.com/doi/10.1111/bcp.v82.4/issuetoc.

Toll-Like Receptor (TLR)4 and MyD88 are Essential for Atheroprotection by Peritoneal B1a B Cells

BACKGROUND

We previously identified peritoneal B1a cells that secrete natural IgM as a key atheroprotective B cell subset. However, the molecules that activate atheroprotective B1a cells are unknown. Here, we investigated whether Toll-like receptors (TLRs) TLR2, TLR4, and TLR9 expressed by B1a cells are required for IgM-mediated atheroprotection.

METHODS AND RESULTS

We adoptively transferred B1a cells from wild-type mice or from mice deficient in TLR2, TLR4, TLR9, or myeloid differentiation primary response 88 (MyD88) into ApoE-/- mice depleted of peritoneal B1a cells by splenectomy and fed a high-fat diet for 8 weeks. Elevations in plasma total, anti-oxLDL (oxidized low-density lipoprotein), anti-leukocyte, anti-CD3, anti-CD8, and anti-CD4 IgMs in atherosclerotic mice required B1a cells expressing TLR4 and MyD88, indicating a critical role for TLR4-MyD88 signaling for IgM secretion. Suppression of atherosclerosis was also critically dependent on B1a cells expressing TLR4-MyD88. Atherosclerosis suppression was associated not only with reductions in lesion apoptotic cells, necrotic cores, and oxLDL, but also with reduced lesion CD4+ and CD8+ T cells. Transforming growth factor beta 1 (TGF-β1) expression, including macrophages expressing TGF-β1, was increased, consistent with increased IgM-mediated phagocytosis of apoptotic cells by macrophages. Reductions in lesion inflammatory cytokines tumor necrosis factor alpha (TNF-α), interleukin (IL) 1β, and IL-18 were consistent with augmented TGF-β1 expression.

CONCLUSIONS

TLR4-MyD88 expression on B1a cells is critical for their IgM-dependent atheroprotection that not only reduced lesion apoptotic cells and necrotic cores, but also decreased CD4 and CD8 T-cell infiltrates and augmented TGF-β1 expression accompanied by reduced lesion inflammatory cytokines TNF-α, IL-1β, and IL-18.

The association between oxidized low-density lipoprotein antibodies and hematological diseases

Background

The aim of the study is to compare the profiles of antibodies (IgM and IgG) against oxidized low-density lipoprotein (oxLDL) of hematological diseases.

Methods

The serum antibodies of oxLDL-IgM and oxLDL-IgG for 446 cases with hematological diseases and 90 patients with primary hypertension and 90 healthy controls were measured by enzyme-linked immunosorbent assay (ELISA) in a cross-section survey. The association of serum oxLDL-LgM and oxLDL-IgG with hematological diseases was analyzed by multiple linear regression model.

Results

Comparing with the hypertension or normal groups, the levels of TCH, TG, LDL-c, HDL-c, oxLDL, and oxLDL-IgG were lower and the levels of ADP and oxLDL-IgM were higher in the hematological diseases group. The levels of oxLDL-IgG antibodies titer were different among hematological diseases group. The results of correlation and multiple regression analysis showed that the seven hematological disease subgroups were positively related to the oxLDL-IgM antibody titer but negatively related to the oxLDL-IgG antibody titer, having been adjusted for potential confounding factors such as age, SBP, DBP, BMI, TCH, TG, ADP, oxLDL, HDL-c, LDL-C.

Conclusions

Here we show that oxLDL-IgG antibodies titer were lower and of oxLDL-IgM titer were higher than hypertension and healthy individuals. Also oxLDL-IgG titer were different among hematological diseases group.

Developing connections amongst B lymphocytes and deregulated pathways in autoimmunity

Immunologists have long investigated B lymphocytes as solely antibody producing cells. With further studies, it became clear that B cells are able to exert a variety of functions within the immune system, and beyond. As a result, B cells are considered promising targets for immunotherapy in a variety of disorders. Recently, experts in B cell biology and autoimmunity convened to discuss important stepping stones to decipher the complexity of B lymphocyte-mediated pathways in autoimmune diseases.

Novel B-cell subsets in atherosclerosis

PURPOSE OF REVIEW

The number of deaths associated with cardiovascular disease remains high, despite great advances in treating the associated high levels of cholesterol. The main underlying pathology of cardiovascular disease is atherosclerosis, which is recognized as a chronic autoimmune-like inflammatory disease. Hence, there is a pressing need to shed light on the immune pathways associated with atherosclerosis. B cells have long been thought to have a general protective effect in atherosclerosis. However, findings in the last decade have challenged this paradigm, showing that it is crucial to differentiate between the various B-cell subsets when assessing their role/effect on atherosclerosis.

RECENT FINDINGS

It has become increasingly recognized lately that B cells can have significant effects on the immune system independent of antibody production. The understanding that B cells form a major source of cytokines and can directly influence T-cell responses via surface markers, have led to the identification of novel B-cell subsets. These subsets are important modulators of autoimmune disorders but have not yet been fully investigated in atherosclerosis.

SUMMARY

Here we review the current known roles of B-cell subsets and the putative effects of recently identified B cells on atherosclerosis.

Phosphatidylserine in atherosclerosis

PURPOSE OF REVIEW

It is now widely acknowledged that phosphatidylserine is a multifunctional bioactive lipid. In this review, we focus on the function of phosphatidylserine in modulating cholesterol metabolism, influencing inflammatory response and regulating coagulation system, and discuss promising phosphatidylserine-based therapeutic approaches and detection techniques in atherosclerosis.

RECENT FINDINGS

Phosphatidylserine has been suggested to play important roles in physiological processes, such as apoptosis, inflammation, and coagulation. Recent data demonstrate atheroprotective potential of phosphatidylserine, reflecting its capacity to inhibit inflammation, modulate coagulation, and enhance HDL functionality. Furthermore, modern lipidomic approaches have enabled the investigation of phosphatidylserine properties relevant to the lipid-based drug delivery and development of reconstituted HDL.

SUMMARY

Studies of phosphatidylserine in relation to atherosclerosis represent an area of opportunity. Additional research elucidating mechanisms underlying experimentally observed atheroprotective effects of phosphatidylserine is required to fully explore therapeutic potential of this naturally occurring phospholipid in cardiovascular disease.

Therapeutic applications of reconstituted HDL: When structure meets function

Reconstituted forms of HDL (rHDL) are under development for infusion as a therapeutic approach to attenuate atherosclerotic vascular disease and to reduce cardiovascular risk following acute coronary syndrome and ischemic stroke. Currently available rHDL formulations developed for clinical use contain apolipoprotein A-I (apoA-I) and one of the major lipid components of HDL, either phosphatidylcholine or sphingomyelin. Recent data have established that quantitatively minor molecular constituents of HDL particles can strongly influence their anti-atherogenic functionality. Novel rHDL formulations displaying enhanced biological activities, including cellular cholesterol efflux, may therefore offer promising prospects for the development of HDL-based, anti-atherosclerotic therapies. Indeed, recent structural and functional data identify phosphatidylserine as a bioactive component of HDL; the content of phosphatidylserine in HDL particles displays positive correlations with all metrics of their functionality. This review summarizes current knowledge of structure-function relationships in rHDL formulations, with a focus on phosphatidylserine and other negatively-charged phospholipids. Mechanisms potentially underlying the atheroprotective role of these lipids are discussed and their potential for the development of HDL-based therapies highlighted.

Drug Carriers: Not an Innocent Delivery Man

Biomaterials used as drug carriers are often considered inactive and assumed to have no other roles than modifying pharmacokinetics and biodistribution of a drug. On the other hand, there are several examples in which the carrier materials show bioactivities in the body, which may have been underestimated or inadvertently ignored. This review highlights several examples where biomaterials used as drug carriers bring biological effects, known or newly discovered, and discusses their implications in development of new drug delivery systems.