Marginal zone B cells control the response of follicular helper T cells to a high-cholesterol diet

Tipping the Scale: Atheroprotective IgM-Producing B Cells in Atherosclerosis

Atherosclerosis is a chronic inflammatory disease whose progression is fueled by proinflammatory moieties and limited by anti-inflammatory mediators. Whereas oxidative damage and the generation of oxidation-specific epitopes that act as damage-associated molecular patterns are highly inflammatory, IgM antibodies produced by B-1 and marginal zone B cells counteract unrestricted inflammation by neutralizing and encouraging clearance of these proinflammatory signals. In this review, we focus on describing the identities of IgM-producing B cells in both mice and humans, elaborating the mechanisms underlying IgM production, and discussing the potential strategies to augment the production of atheroprotective IgM. In addition, we will discuss promising therapeutic interventions in humans to help tip the scale toward augmentation of IgM production and to provide atheroprotection.

Causal relationship between immune cells and risk of myocardial infarction: evidence from a Mendelian randomization study

Background

Atherosclerotic plaque rupture is a major cause of heart attack. Previous studies have shown that immune cells are involved in the development of atherosclerosis, but different immune cells play different roles. The aim of this study was to investigate the causal relationship between immunological traits and myocardial infarction (MI).

Methods

To assess the causal association of immunological profiles with myocardial infarction based on publicly available genome-wide studies, we used a two-sample mendelian randomization (MR) approach with inverse variance weighted (IVW) as the main analytical method. Sensitivity analyses were used to assess heterogeneity and horizontal pleiotropy.

Results

A two-sample MR analysis was conducted using IVW as the primary method. At a significance level of 0.001, we identified 47 immunophenotypes that have a significant causal relationship with MI. Seven of these were present in B cells, five in cDC, four in T cells at the maturation stage, six in monocytes, five in myeloid cells, 12 in TBNK cells, and eight in Treg cells. Sensitivity analyses were performed to confirm the robustness of the MR results.

Conclusions

Our results provide strong evidence that multiple immune cells have a causal effect on the risk of myocardial infarction. This discovery provides a new avenue for the development of therapeutic treatments for myocardial infarction and a new target for drug development.

Moving from lipids to leukocytes: inflammation and immune cells in atherosclerosis

Atherosclerotic cardiovascular disease (ASCVD) is the most important cause of morbidity and mortality worldwide. While it is traditionally attributed to lipid accumulation in the vascular endothelium, recent research has shown that plaque inflammation is an important additional driver of atherogenesis. Though clinical outcome trials utilizing anti-inflammatory agents have proven promising in terms of reducing ASCVD risk, it is imperative to identify novel actionable targets that are more specific to atherosclerosis to mitigate adverse effects associated with systemic immune suppression. To that end, this review explores the contributions of various immune cells from the innate and adaptive immune system in promoting and mitigating atherosclerosis by integrating findings from experimental studies, high-throughput multi-omics technologies, and epidemiological research.

Therapeutic Avenues to Modulate B-Cell Function in Patients With Cardiovascular Disease

The adaptive immune system plays an important role in the development and progression of atherosclerotic cardiovascular disease. B cells can have both proatherogenic and atheroprotective roles, making treatments aimed at modulating B cells important therapeutic targets. The innate-like B-cell response is generally considered atheroprotective, while the adaptive response is associated with mixed consequences for atherosclerosis. Additionally, interactions of B cells with components of the adaptive and innate immune system, including T cells and complement, also represent key points for therapeutic regulation. In this review, we discuss therapeutic approaches based on B-cell depletion, modulation of B-cell survival, manipulation of both the antibody-dependent and antibody-independent B-cell response, and emerging immunization techniques.

T-Cell/B-Cell Interactions in Atherosclerosis

Atherosclerosis is a complex inflammatory disease in which the adaptive immune response plays an important role. While the overall impact of T and B cells in atherosclerosis is relatively well established, we are only beginning to understand how bidirectional T-cell/B-cell interactions can exert prominent atheroprotective and proatherogenic functions. In this review, we will focus on these T-cell/B-cell interactions and how we could use them to therapeutically target the adaptive immune response in atherosclerosis.

Autoimmune diseases and atherosclerotic cardiovascular disease

Autoimmune diseases are associated with a dramatically increased risk of atherosclerotic cardiovascular disease and its clinical manifestations. The increased risk is consistent with the notion that atherogenesis is modulated by both protective and disease-promoting immune mechanisms. Notably, traditional cardiovascular risk factors such as dyslipidaemia and hypertension alone do not explain the increased risk of cardiovascular disease associated with autoimmune diseases. Several mechanisms have been implicated in mediating the autoimmunity-associated cardiovascular risk, either directly or by modulating the effect of other risk factors in a complex interplay. Aberrant leukocyte function and pro-inflammatory cytokines are central to both disease entities, resulting in vascular dysfunction, impaired resolution of inflammation and promotion of chronic inflammation. Similarly, loss of tolerance to self-antigens and the generation of autoantibodies are key features of autoimmunity but are also implicated in the maladaptive inflammatory response during atherosclerotic cardiovascular disease. Therefore, immunomodulatory therapies are potential efficacious interventions to directly reduce the risk of cardiovascular disease, and biomarkers of autoimmune disease activity could be relevant tools to stratify patients with autoimmunity according to their cardiovascular risk. In this Review, we discuss the pathophysiological aspects of the increased cardiovascular risk associated with autoimmunity and highlight the many open questions that need to be answered to develop novel therapies that specifically address this unmet clinical need.

Inflammation in HIV and Its Impact on Atherosclerotic Cardiovascular Disease

People living with HIV have a 1.5- to 2-fold increased risk of developing cardiovascular disease. Despite treatment with highly effective antiretroviral therapy, people living with HIV have chronic inflammation that makes them susceptible to multiple comorbidities. Several factors, including the HIV reservoir, coinfections, clonal hematopoiesis of indeterminate potential (CHIP), microbial translocation, and antiretroviral therapy, may contribute to the chronic state of inflammation. Within the innate immune system, macrophages harbor latent HIV and are among the prominent immune cells present in atheroma during the progression of atherosclerosis. They secrete inflammatory cytokines such as IL (interleukin)-6 and tumor necrosis-α that stimulate the expression of adhesion molecules on the endothelium. This leads to the recruitment of other immune cells, including cluster of differentiation (CD)8+ and CD4+ T cells, also present in early and late atheroma. As such, cells of the innate and adaptive immune systems contribute to both systemic inflammation and vascular inflammation. On a molecular level, HIV-1 primes the NLRP3 (NLR family pyrin domain containing 3) inflammasome, leading to an increased expression of IL-1β, which is important for cardiovascular outcomes. Moreover, activation of TLRs (toll-like receptors) by HIV, gut microbes, and substance abuse further activates the NLRP3 inflammasome pathway. Finally, HIV proteins such as Nef (negative regulatory factor) can inhibit cholesterol efflux in monocytes and macrophages through direct action on the cholesterol transporter ABCA1 (ATP-binding cassette transporter A1), which promotes the formation of foam cells and the progression of atherosclerotic plaque. Here, we summarize the stages of atherosclerosis in the context of HIV, highlighting the effects of HIV, coinfections, and antiretroviral therapy on cells of the innate and adaptive immune system and describe current and future interventions to reduce residual inflammation and improve cardiovascular outcomes among people living with HIV.

Adaptive immunity and atherosclerosis: aging at its crossroads

Adaptive immunity plays a profound role in atherosclerosis pathogenesis by regulating antigen-specific responses, inflammatory signaling and antibody production. However, as we age, our immune system undergoes a gradual functional decline, a phenomenon termed "immunosenescence". This decline is characterized by a reduction in proliferative naïve B- and T cells, decreased B- and T cell receptor repertoire and a pro-inflammatory senescence associated secretory profile. Furthermore, aging affects germinal center responses and deteriorates secondary lymphoid organ function and structure, leading to impaired T-B cell dynamics and increased autoantibody production. In this review, we will dissect the impact of aging on adaptive immunity and the role played by age-associated B- and T cells in atherosclerosis pathogenesis, emphasizing the need for interventions that target age-related immune dysfunction to reduce cardiovascular disease risk.

Atherosclerosis and the Bidirectional Relationship between Cancer and Cardiovascular Disease: From Bench to Bedside-Part 1

Atherosclerosis, a complex metabolic-immune disease characterized by chronic inflammation driven by the buildup of lipid-rich plaques within arterial walls, has emerged as a pivotal factor in the intricate interplay between cancer and cardiovascular disease. This bidirectional relationship, marked by shared risk factors and pathophysiological mechanisms, underscores the need for a comprehensive understanding of how these two formidable health challenges intersect and influence each other. Cancer and its treatments can contribute to the progression of atherosclerosis, while atherosclerosis, with its inflammatory microenvironment, can exert profound effects on cancer development and outcomes. Both cancer and cardiovascular disease involve intricate interactions between general and personal exposomes. In this review, we aim to summarize the state of the art of translational data and try to show how oncologic studies on cardiotoxicity can broaden our knowledge of crucial pathways in cardiovascular biology and exert a positive impact on precision cardiology and cardio-oncology.

Marginal zone B cells produce 'natural' atheroprotective IgM antibodies in a T cell-dependent manner

AIMS

The adaptive immune response plays an important role in atherosclerosis. In response to a high-fat/high-cholesterol (HF/HC) diet, marginal zone B (MZB) cells activate an atheroprotective programme by regulating the differentiation and accumulation of 'poorly differentiated' T follicular helper (Tfh) cells. On the other hand, Tfh cells activate the germinal centre response, which promotes atherosclerosis through the production of class-switched high-affinity antibodies. We therefore investigated the direct role of Tfh cells and the role of IL18 in Tfh differentiation in atherosclerosis.

METHODS AND RESULTS

We generated atherosclerotic mouse models with selective genetic deletion of Tfh cells, MZB cells, or IL18 signalling in Tfh cells. Surprisingly, mice lacking Tfh cells had increased atherosclerosis. Lack of Tfh not only reduced class-switched IgG antibodies against oxidation-specific epitopes (OSEs) but also reduced atheroprotective natural IgM-type anti-phosphorylcholine (PC) antibodies, despite no alteration of natural B1 cells. Moreover, the absence of Tfh cells was associated with an accumulation of MZB cells with substantially reduced ability to secrete antibodies. In the same manner, MZB cell deficiency in Ldlr-/- mice was associated with a significant decrease in atheroprotective IgM antibodies, including natural anti-PC IgM antibodies. In humans, we found a positive correlation between circulating MZB-like cells and anti-OSE IgM antibodies. Finally, we identified an important role for IL18 signalling in HF/HC diet-induced Tfh.

CONCLUSION

Our findings reveal a previously unsuspected role of MZB cells in regulating atheroprotective 'natural' IgM antibody production in a Tfh-dependent manner, which could have important pathophysiological and therapeutic implications.

The role of immune system in atherosclerosis: Molecular mechanisms, controversies, and future possibilities

Numerous cardiovascular disorders have atherosclerosis as their pathological underpinning. Numerous studies have demonstrated that, with the aid of pattern recognition receptors, cytokines, and immunoglobulins, innate immunity, represented by monocytes/macrophages, and adaptive immunity, primarily T/B cells, play a critical role in controlling inflammation and abnormal lipid metabolism in atherosclerosis. Additionally, the finding of numerous complement components in atherosclerotic plaques suggests yet again how heavily the immune system controls atherosclerosis. Therefore, it is essential to have a thorough grasp of how the immune system contributes to atherosclerosis. The specific molecular mechanisms involved in the activation of immune cells and immune molecules in atherosclerosis, the controversy surrounding some immune cells in atherosclerosis, and the limitations of extrapolating from relevant animal models to humans were all carefully reviewed in this review from the three perspectives of innate immunity, adaptive immunity, and complement system. This could provide fresh possibilities for atherosclerosis research and treatment in the future.

Single-cell profiling of CD11c+ B cells in atherosclerosis

Circulating CD11c+ B cells, a novel subset of activated B cells, have been linked to autoimmunity and shown to expand with age. Atherosclerosis is an age-associated disease that involves innate and adaptive immune responses to modified self-antigens. Yet, the expression of CD11c on specific B-cell subtypes and its link to atherosclerosis are poorly understood. In this study, we characterized the frequency of CD11c+ B cells in tissues in mice with aging. We observed an age-associated increase in CD11c+ B cells in the spleen and bone marrow of ApoE-/- mice, and this was associated with an increase in aortic plaque. In addition, we also utilized single-cell multi-omics profiling of 60 human subjects undergoing advanced imaging for coronary artery disease (CAD) to subtype CD11c+ B cells and determine their frequency in subjects with high and low severity of CAD. Using unsupervised clustering, we identified four distinct clusters of CD11c+ B cells, which include CD27 and IgD double negative 2 (DN2), age-associated (ABC), CD11c+ unswitched memory (USWM), and activated Naïve (aNav) B cells. We observed an increase in the frequency of both ABC B cells and DN2 B cells in patients with high CAD severity. Pathway analysis further demonstrated augmentation of autophagy, IFNg signaling, and TLR signaling in DN2 cells in high-severity CAD patients. On the other hand, an increase in the negative regulator of BCR signaling through CD72 was found in ABC cells in low-severity CAD patients. Through investigating scRNAseq of atheroma, these DN2 cells were also found to infiltrate human coronary atheroma.

Deletion of mesencephalic astrocyte-derived neurotrophic factor delays and damages the development of white pulp in spleen

Mesencephalic astrocyte-derived neurotrophic factor (MANF) is an endoplasmic reticulum (ER) stress-induced protein, and it has been reported that ER stress and unfolded protein response (UPR) are closely related to the immune system. The spleen is an important immune organ and we have shown in our previous research that MANF is expressed in human spleen tissues. However, there have been limited studies about the effect of MANF on spleen development. In this study, we detected MANF expression in spleen tissues and found that MANF was expressed in the red pulp and marginal zone. Additionally, MANF was localized in the CD68+ and CD138+ cells of adult rat spleen tissues, but not in the CD3+ cells. We performed immunohistochemical staining to detect MANF expression in the spleen tissues of rats that were different ages, and we found that MANF+ cells were localized together in the spleen tissues of rats that were 1-4 weeks old. MANF was also expressed in CD68+ cells in the spleen tissues of rats and mice. Furthermore, we found that MANF deficiency inhibited white pulp development in MANF knockout mice, thus indicating that MANF played an important role in the white pulp development of rodent spleen tissues.

Knowledge mapping of B cell and atherosclerosis over the past 20 years: A bibliometric analysis

Atherosclerosis (AS) is the main underlying cause of cardiovascular disease, and B cells are considered a key immune cell type to regulate AS. So far, there is no bibliometric study on B cell and AS. This study aims to comprehensively analyze the scientific output about B cell and AS, summarize the literature characteristics, explore research hotspots, and point out emerging trends. We searched the literature from 2003 to 2022 from the Web of Science Core Collection (WoSCC) database. CiteSpace, VOSviewer, and the R package "Bibliometrix" were used for literature analysis and visualization. A total of 1,062 articles and reviews were identified. The number of annual publications generally showed an upward trend. The United States and China were the most productive countries. Medical University of Vienna was the most productive research institution, and Binder Christoph J. was the most productive author, who was also from Medical University of Vienna. "Arteriosclerosis Thrombosis and Vascular Biology" was the most published journal and the most frequently cited journal. The most cited reference was written by Caligiuri G (2002) in "Journal of Clinical Investigation." The most frequent keywords were "inflammation," "macrophages," "cardiovascular disease," "T cells," "apoptosis," "immunity," "cytokines," "lymphocytes," etc. The trend topics were mainly focused on "immune infiltration," "immunoglobulins," and "biomarkers." The complex role of B cell subtypes and a variety of B cell mediators is the main research direction at present. In-depth analysis of B cell-specific targets can provide new ideas and methods for the prevention and treatment of AS.

Statins in Graves Orbitopathy: A New Therapeutic Tool

PURPOSE

Graves orbitopathy (GO) is the most common extrathyroidal manifestation of Graves disease. Although its pathogenesis is not fully elucidated, GO is commonly considered an autoimmune disease due to loss of self-tolerance against autoantigens shared by thyroid epithelial cells and orbital fibroblasts. High-dose intravenous glucocorticoids (ivGCs) are the most used treatment for moderate-to-severe, active GO, but the addition of other immunomodulating treatments can improve the efficacy of ivGCs. Among the various risk factors that can affect the occurrence of GO, cholesterol may be worthy of interest. Since 2015 the role of cholesterol and cholesterol-lowering medications has been investigated. The purpose of this review is to discuss this topic, thereby offering new therapeutic opportunities for patients with GO.

METHODS

We searched PubMed for studies published between January 1, 1980 and June 1, 2023, using the search terms "Graves orbitopathy," "thyroid eye disease," "Graves ophthalmopathy," "thyroid ophthalmopathy," "thyroid-associated ophthalmopathy," "endocrine ophthalmopathy," "cholesterol," "lipids," "statins," "low-density lipoprotein," "atorvastatin," and "cholesterol-lowering drugs." Only English-language articles were included.

RESULTS

A correlation between low-density lipoprotein cholesterol and the risk of GO development has been reported. Furthermore, low-density lipoprotein cholesterol has been proposed as a risk factor that can affect the course of GO and the response to ivGCs. The protective role of cholesterol-lowering medications in preventing GO has been also investigated. Statin treatment was found to have potential benefits in reducing the risk of GO in patients with Graves disease. Given these findings, measurement of low-density lipoprotein cholesterol and treatment of hypercholesterolemia in patients with moderate-to-severe, active GO may be considered before starting ivGCs administration. Recently, a randomized clinical trial aimed at investigating the effects of statins in GO suggested that the addition of oral atorvastatin to ivGCs improves the overall outcome of moderate-to-severe, active GO in hypercholesterolemic patients given ivGCs.

CONCLUSIONS

Overall, statins seem to have a preventive and therapeutic role in moderate-to-severe active GO. Their efficacy can be related to cholesterol-lowering activity, pleiotropic actions, and interaction with methylprednisolone.

Atherosclerosis antigens as targets for immunotherapy

Atherosclerosis is a chronic inflammatory disease of the arteries that can lead to thrombosis, infarction and stroke, underlying the first cause of mortality worldwide. Adaptive immunity plays critical roles in atherosclerosis, and numerous studies have ascribed both atheroprotective and atherogenic functions to specific subsets of T and B cells. However, less is known on how antigen specificity determines the protective or adverse outcome of such adaptive responses. Understanding antigen triggers in atherosclerosis is crucial to delve deeper into mechanisms of disease initiation and progression and to implement specific immunotherapeutic approaches, including vaccination strategies. Here we review the role of adaptive immunity in atherosclerosis and the insights that single-cell technology has provided into the function of distinct immune cell subsets. We outline the most relevant atherosclerosis antigens and antibodies reported to date and examine their immunotherapeutic potential. Finally, we review the most promising vaccination-based clinical trials targeting the adaptive immune system.

Oxidized Phospholipid oxPAPC Alters Regulatory T-Cell Differentiation and Decreases Their Protective Function in Atherosclerosis in Mice

BACKGROUND

Regulatory T cells (Tregs) are protective in atherosclerosis but reduced during disease progression due to cell death and loss of stability. However, the mechanisms of Treg dysfunction remain unknown. Oxidized phospholipids are abundant in atherosclerosis and can activate innate immune cells, but little is known regarding their impact on T cells. Given Treg loss during atherosclerosis progression and oxidized phospholipid levels in the plaque microenvironment, we investigated whether oxidized 1-palmitoyl-2-arachidonoyl-sn-glycero-3-phosphocholine (oxPAPC), an oxidized phospholipid associated with atherosclerotic plaques, alters Treg differentiation and function.

METHODS

CD4+ T cells were polarized to Treg, T helper (Th) 1, and Th17 cells with or without oxPAPC and assessed by flow cytometry. Gene expression in oxPAPC-treated Tregs was analyzed by bulk RNA sequencing. Functional studies of oxPAPC-induced Tregs were performed by coculturing Tregs with CellTrace Violet-labeled cells in vitro, and by adoptively transferring Tregs to hyperlipidemic Ldlr-/- mice to measure atherosclerosis progression.

RESULTS

Compared with controls, oxPAPC-treated Tregs were less viable, but surviving cells expressed higher levels of the Th1-associated markers T-bet, CXCR3, and IFN (interferon)-γ. Th1 and Th17 skewing cultures were unaltered by oxPAPC. IFN-γ is linked to Treg instability, thus Treg polarization experiments were repeated using Ifngr1-/- CD4+ T cells. IFNγR1 (INF gamma receptor 1) deficiency did not improve cell viability in oxPAPC-treated Tregs; however, T-bet and IFN-γ expression was not increased in surviving cells suggesting a role for IFN-γsignaling. OxPAPC-treated Tregs were less suppressive in vitro, and adoptive transfer studies in hyperlipidemic Ldlr-/- mice showed that oxPAPC-induced Tregs possessed altered tissue homing and were insufficient to inhibit atherosclerosis progression.

CONCLUSIONS

OxPAPC elicits Treg-specific changes altering Treg differentiation and inducing a Th1-like phenotype in surviving cells partially through IFN-γ signaling. This is biologically relevant as oxPAPC-treated Tregs do not reduce atherosclerosis progression in Ldlr-/- mice. This study supports the role of oxidized phospholipids in negatively impacting Treg differentiation and atheroprotective function.

Human circulating CD24hi marginal zone B cells produce IgM targeting atherogenic antigens and confer protection from vascular disease

IgMs that inactivate oxidation-specific epitopes (IgMOSE), which are secondary products of lipid peroxidization, protect against inflammatory diseases, including diet-induced atherosclerosis. However, the human B cell subtype that produces IgMOSE remains unknown. In this study, we used single-cell mass cytometry and adoptive transfer of B cell subtypes to NOD.Cg-Prkdcscid Il2rgtm1Wjl/SzJ (NSG) mice to identify B27+IgM+CD24hi cells as the major producers of IgMOSE in humans. Notably, these cells have characteristics of human circulatory marginal zone B (MZB) cells, which are known to be atheoroprotective IgM producers in mice. CD24 antibody treatment to reduce MZB cells and IgM in a hyperlipidemic humanized mouse model provides the evidence that MZB cells protect against vascular inflammation. Consistent with these findings, the frequency of B27+IgM+CD24hi cells (MZB) in patients inversely correlates with coronary artery disease severity.

Targeting gut microbiota and immune crosstalk: potential mechanisms of natural products in the treatment of atherosclerosis

Atherosclerosis (AS) is a chronic inflammatory reaction that primarily affects large and medium-sized arteries. It is a major cause of cardiovascular disease and peripheral arterial occlusive disease. The pathogenesis of AS involves specific structural and functional alterations in various populations of vascular cells at different stages of the disease. The immune response is involved throughout the entire developmental stage of AS, and targeting immune cells presents a promising avenue for its treatment. Over the past 2 decades, studies have shown that gut microbiota (GM) and its metabolites, such as trimethylamine-N-oxide, have a significant impact on the progression of AS. Interestingly, it has also been reported that there are complex mechanisms of action between GM and their metabolites, immune responses, and natural products that can have an impact on AS. GM and its metabolites regulate the functional expression of immune cells and have potential impacts on AS. Natural products have a wide range of health properties, and researchers are increasingly focusing on their role in AS. Now, there is compelling evidence that natural products provide an alternative approach to improving immune function in the AS microenvironment by modulating the GM. Natural product metabolites such as resveratrol, berberine, curcumin, and quercetin may improve the intestinal microenvironment by modulating the relative abundance of GM, which in turn influences the accumulation of GM metabolites. Natural products can delay the progression of AS by regulating the metabolism of GM, inhibiting the migration of monocytes and macrophages, promoting the polarization of the M2 phenotype of macrophages, down-regulating the level of inflammatory factors, regulating the balance of Treg/Th17, and inhibiting the formation of foam cells. Based on the above, we describe recent advances in the use of natural products that target GM and immune cells crosstalk to treat AS, which may bring some insights to guide the treatment of AS.

Nano-Econazole Enhanced PD-L1 Checkpoint Blockade for Synergistic Antitumor Immunotherapy against Pancreatic Ductal Adenocarcinoma

Insufficienct T lymphocyte infiltration and unresponsiveness to immune checkpoint blockade therapy are still major difficulties for the clinical treatment of pancreatic ductal adenocarcinoma (PDAC). Although econazole has shown promise in inhibiting PDAC growth, its poor bioavailability and water solubility limit its potential as a clinical therapy for PDAC. Furthermore, the synergistic role of econazole and biliverdin in immune checkpoint blockade therapy in PDAC remains elusive and challenging. Herein, a chemo-phototherapy nanoplatform is designed by which econazole and biliverdin can be co-assembled (defined as FBE NPs), which significantly improve the poor water solubility of econazole and enhance the efficacy of PD-L1 checkpoint blockade therapy against PDAC. Mechanistically, econazole and biliverdin are directly released into the acidic cancer microenvironment, to activate immunogenic cell death via biliverdin-induced PTT/PDT and boost the immunotherapeutic response of PD-L1 blockade. In addition, econazole simultaneously enhances PD-L1 expression to sensitize anti-PD-L1 therapy, leading to suppression of distant tumors, long-term immune memory effects, improved dendritic cell maturation, and tumor infiltration of CD8⁺ T lymphocytes. The combined FBE NPs and α-PDL1 show synergistic antitumor efficacy. Collectively, FBE NPs show excellent biosafety and antitumor efficacy by combining chemo-phototherapy with PD-L1 blockade, which has promising potential in a precision medicine approach as a PDAC treatment strategy.

B cell-specific knockout of AID protects against atherosclerosis

Antigen-naive IgM-producing B cells are atheroprotective, whereas mature B cells producing class-switched antibodies promote atherosclerosis. Activation-induced cytidine deaminase (AID), which mediates class switch recombination (CSR), would thus be expected to foster atherosclerosis. Yet, AID also plays a major role in the establishment of B cell tolerance. We sought to define whether AID affects atherosclerotic plaque formation. We generated Ldlr^-/- chimeras transplanted with bone marrow from Aicda^-/- or wild-type (WT) mice, fed a HFD for 14 weeks. Decreased B cell maturation in Ldlr^-/-Aicda^-/- mice was demonstrated by 50% reduction in splenic and aortic BAFFR expression, a key signaling component of B2 cell maturation. This was associated with increased plasma IgM in Ldlr^-/-Aicda^-/- compared with Ldlr^-/-WT animals. Importantly, Ldlr^-/-Aicda^-/- mice had reduced atherosclerotic lesion area (0.20 ± 0.03mm²) compared with Ldlr^-/-WT (0.30 ± 0.04mm², P < 0.05), although no differences in plaque composition were noted between groups. In addition, immunofluorescence analysis revealed increased splenic B and T cell areas independent of cell number. AID depletion directly inhibits atherosclerotic plaque formation.

Antigen-specific B cells direct T follicular-like helper cells into lymphoid follicles to mediate Mycobacterium tuberculosis control

Tuberculosis (TB), caused by Mycobacterium tuberculosis (Mtb), is a global cause of death. Granuloma-associated lymphoid tissue (GrALT) correlates with protection during TB, but the mechanisms of protection are not understood. During TB, the transcription factor IRF4 in T cells but not B cells is required for the generation of the TH1 and TH17 subsets of helper T cells and follicular helper T (TFH)-like cellular responses. A population of IRF4+ T cells coexpress the transcription factor BCL6 during Mtb infection, and deletion of Bcl6 (Bcl6fl/fl) in CD4+ T cells (CD4cre) resulted in reduction of TFH-like cells, impaired localization within GrALT and increased Mtb burden. In contrast, the absence of germinal center B cells, MHC class II expression on B cells, antibody-producing plasma cells or interleukin-10-expressing B cells, did not increase Mtb susceptibility. Indeed, antigen-specific B cells enhance cytokine production and strategically localize TFH-like cells within GrALT via interactions between programmed cell death 1 (PD-1) and its ligand PD-L1 and mediate Mtb control in both mice and macaques.

Research progress on the active ingredients of traditional Chinese medicine in the intervention of atherosclerosis: A promising natural immunotherapeutic adjuvant

Atherosclerosis (AS) is a chronic inflammatory disease caused by disorders of lipid metabolism. Abnormal deposition of low-density lipoproteins in the arterial wall stimulates the activation of immune cells, including the adhesion and infiltration of monocytes, the proliferation and differentiation of macrophages and lymphocytes, and the activation of their functions. The complex interplay between immune cells coordinates the balance between pro- and anti-inflammation and plays a key role in the progression of AS. Therefore, targeting immune cell activity may lead to the development of more selective drugs with fewer side effects to treat AS without compromising host defense mechanisms. At present, an increasing number of studies have found that the active ingredients of traditional Chinese medicine (TCM) can regulate the function of immune cells in multiple ways to against AS, showing great potential for the treatment of AS and promising clinical applications. In this paper, we review the mechanisms of immune cell action in AS lesions and the potential targets and/or pathways for immune cell regulation by the active ingredients of TCM to promote the understanding of the immune system interactions of AS and provide a relevant basis for the use of active ingredients of TCM as natural adjuvants for AS immunotherapy.

Subclinical Atherosclerosis Is Associated with Discrepancies in BAFF and APRIL Levels and Altered Breg Potential of Precursor-like Marginal Zone B-Cells in Long-Term HIV Treated Individuals

Chronic inflammation persists in people living with HIV (PLHIV) despite antiretrovial therapy (ART) and is involved in their premature development of cardiovascular diseases (CVD) such as atherosclerosis. We have previously reported that an excess of “B-cell activating factor” (BAFF), an important molecule for the selection and activation of first-line Marginal Zone (MZ) B-cell populations, is associated with deregulations of precursor-like MZ (MZp), whose potent B-cell regulatory (Breg) capacities are altered in PLHIV, early on and despite 1−2 years of ART. Based on these observations, and growing evidence that MZ populations are involved in atherosclerosis control, we designed a cross sectional study to explore the associations between BAFF and its analogue “A proliferation-inducing ligand” (APRIL) with subclinical CVD in long-time-treated individuals of the Canadian HIV and Aging Cohort Study (CHACS) imaging sub-study group. We also characterized the Breg profile of MZp from the blood of these individuals. Results were correlated with the total volume of atherosclerotic plaques (TPV) and with CVD risk factors and biomarkers. TPV was measured using cardiac computerised tomography angiography, and presence of CVD was defined as TPV > 0. We report that blood levels of BAFF are elevated and correlate positively with CVD and its risk factors in PLHIV from the CHACS, in contrast to APRIL levels, which correlate negatively with these factors. The expression levels of Breg markers such as NR4A3, CD39, CD73 and CD83 are significantly lower in PLHIV when compared to those of HIV-uninfected controls. In vitro experiments show that APRIL upregulates the expression of Breg markers by blood MZp from HIV-uninfected individuals, while this modulation is dampened by the addition of recombinant BAFF. Altogether, our observations suggest that strategies viewed to modulate levels of BAFF and/or APRIL could eventually represent a potential treatment target for CVD in PLHIV.

Antibodies in action: the role of humoral immunity in the fight against atherosclerosis

The sequestering of oxidation-modified low-density lipoprotein by macrophages results in the accumulation of fatty deposits within the walls of arteries. Necrosis of these cells causes a release of intercellular epitopes and the activation of the adaptive immune system, which we predict leads to robust autoantibody production. T cells produce cytokines that act in the plaque environment and further stimulate B cell antibody production. B cells in atherosclerosis meanwhile have a mixed role based on subclass. The current model is that B-1 cells produce protective IgM antibodies in response to oxidation-specific epitopes that work to control plaque formation, while follicular B-2 cells produce class-switched antibodies (IgG, IgA, and IgE) which exacerbate the disease. Over the course of this review, we discuss further the validation of these protective antibodies while evaluating the current dogma regarding class-switched antibodies in atherosclerosis. There are several contradictory findings regarding the involvement of class-switched antibodies in the disease. We hypothesize that this is due to antigen-specificity, and not simply isotype, being important, and that a closer evaluation of these antibodies' targets should be conducted. We propose that specific antibodies may have therapeutical potential in preventing and controlling plaque development within a clinical setting.

Identification of core genes associated with the anti-atherosclerotic effects of Salvianolic acid B and immune cell infiltration characteristics using bioinformatics analysis

Background

Atherosclerosis (AS) is the greatest contributor to pathogenesis of atherosclerotic cardiovascular disease (ASCVD), which is associated with increased mortality and reduced quality of life. Early intervention to mitigate AS is key to prevention of ASCVD. Salvianolic acid B (Sal B) is mainly extracted from root and rhizome of Salvia Miltiorrhiza Bunge, and exerts anti-atherosclerotic effect. The purpose of this study was to screen for anti-AS targets of Sal B and to characterize immune cell infiltration in AS.

Methods

We identified targets of Sal B using SEA (http://sea.bkslab.org/) and SIB (https://www.sib.swiss/) databases. GSE28829 and GSE43292 datasets were obtained from Gene Expression Omnibus database. We identified differentially expressed genes (DEGs) and performed enrichment analysis. Weighted gene co-expression network analysis (WGCNA) was used to determine the most relevant module associated with atherosclerotic plaque stability. Intersecting candidate genes were evaluated by generating receiver operating characteristic (ROC) curves and molecular docking. Then, immune cell types were identified using CIBERSOFT and single-sample gene set enrichment analysis (ssGSEA), the relationship between candidate genes and immune cell infiltration was evaluated. Finally, a network-based approach to explore the candidate genes relationship with microRNAs (miRNAs) and Transcription factors (TFs).

Results

MMP9 and MMP12 were been selected as candidate genes from 64 Sal B-related genes, 81 DEGs and turquoise module with 220 genes. ROC curve results showed that MMP9 (AUC = 0.815, P<0.001) and MMP12 (AUC = 0.763, P<0.001) were positively associated with advanced atherosclerotic plaques. The results of immune infiltration showed that B cells naive, B cells memory, Plasma cells, T cells CD8, T cells CD4 memory resting, T cells CD4 memory activated, T cells regulatory (Tregs), T cells gamma delta, NK cells activated, Monocytes, and Macrophages M0 may be involved in development of AS, and the candidate genes MMP9 and MMP12 were associated with these immune cells to different degrees. What’ s more, miR-34a-5p and FOXC1, JUN maybe the most important miRNA and TFs.

Conclusion

The anti-AS effects of Sal B may be related to MMP9 and MMP12 and associated with immune cell infiltration, which is expected to be used in the early intervention of AS.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12906-022-03670-6.

Excess BAFF Alters NR4As Expression Levels and Breg Function of Human Precursor-like Marginal Zone B-Cells in the Context of HIV-1 Infection

We have reported excess B-cell activating factor (BAFF) in the blood of HIV-infected progressors, which was concomitant with increased frequencies of precursor-like marginal zone (MZp) B-cells, early on and despite antiretroviral therapy (ART). In controls, MZp possess a strong B-cell regulatory (Breg) potential. They highly express IL-10, the orphan nuclear receptors (NR)4A1, NR4A2 and NR4A3, as well as the ectonucleotidases CD39 and CD73, all of which are associated with the regulation of inflammation. Furthermore, we have shown MZp regulatory function to involve CD83 signaling. To address the impact of HIV infection and excessive BAFF on MZp Breg capacities, we have performed transcriptomic analyses by RNA-seq of sorted MZp B-cells from the blood of HIV-infected progressors. The Breg profile and function of blood MZp B-cells from HIV-infected progressors were assessed by flow-cytometry and light microscopy high-content screening (HCS) analyses, respectively. We report significant downregulation of NR4A1, NR4A2, NR4A3 and CD83 gene transcripts in blood MZp B-cells from HIV-infected progressors when compared to controls. NR4A1, NR4A3 and CD83 protein expression levels and Breg function were also downregulated in blood MZp B-cells from HIV-infected progressors and not restored by ART. Moreover, we observe decreased expression levels of NR4A1, NR4A3, CD83 and IL-10 by blood and tonsillar MZp B-cells from controls following culture with excess BAFF, which significantly diminished their regulatory function. These findings, made on a limited number of individuals, suggest that excess BAFF contributes to the alteration of the Breg potential of MZp B-cells during HIV infection and possibly in other situations where BAFF is found in excess.

The Role of the Coagulation System in Peripheral Arterial Disease: Interactions with the Arterial Wall and Its Vascular Microenvironment and Implications for Rational Therapies

Peripheral artery disease (PAD) is a clinical manifestation of atherosclerotic disease with a large-scale impact on the economy and global health. Despite the role played by platelets in the process of atherogenesis being well recognized, evidence has been increasing on the contribution of the coagulation system to the atherosclerosis formation and PAD development, with important repercussions for the therapeutic approach. Histopathological analysis and some clinical studies conducted on atherosclerotic plaques testify to the existence of different types of plaques. Likely, the role of coagulation in each specific type of plaque can be an important determinant in the histopathological composition of atherosclerosis and in its future stability. In this review, we analyze the molecular contribution of inflammation and the coagulation system on PAD pathogenesis, focusing on molecular similarities and differences between atherogenesis in PAD and coronary artery disease (CAD) and discussing the possible implications for current therapeutic strategies and future perspectives accounting for molecular inflammatory and coagulation targets. Understanding the role of cross-talking between coagulation and inflammation in atherosclerosis genesis and progression could help in choosing the right patients for future dual pathway inhibition strategies, where an antiplatelet agent is combined with an anticoagulant, whose role, despite pathophysiological premises and trials' results, is still under debate.

ATF3 in atherosclerosis: a controversial transcription factor

Atherosclerosis, the pathophysiological basis of most malignant cardiovascular diseases, remains a global concern. Transcription factors play a key role in regulating cell function and disease progression in developmental signaling pathways involved in atherosclerosis. Activated transcription factor (ATF) 3 is an adaptive response gene in the ATF/cAMP response element binding (CREB) protein family that acts as a transcription suppressor or activator by forming homodimers or heterodimers with other ATF/CREB members. Appropriate ATF3 expression is vital for normal physiological cell function. Notably, ATF3 exhibits distinct roles in vascular endothelial cells, macrophages, and the liver, which will also be described in detail. This review provides a new perspective for atherosclerosis therapy by summarizing the mechanism of ATF3 in atherosclerosis, as well as the structure and pathophysiological properties of ATF3. KEY MESSAGES: • In endothelial cells, ATF3 overexpression aggravates oxidative stress and inflammation. • In macrophages and liver cells, ATF3 can act as a negative regulator of inflammation and promote cholesterol metabolism. • ATF3 can be used as a potential therapeutic factor in the treatment of atherosclerosis.

GPR55 in B cells limits atherosclerosis development and regulates plasma cell maturation

Dissecting the pathways regulating the adaptive immune response in atherosclerosis is of particular therapeutic interest. Here we report that the lipid G-protein coupled receptor GPR55 is highly expressed by splenic plasma cells (PC), upregulated in mouse spleens during atherogenesis and human unstable or ruptured compared to stable plaques. Gpr55-deficient mice developed larger atherosclerotic plaques with increased necrotic core size compared to their corresponding controls. Lack of GPR55 hyperactivated B cells, disturbed PC maturation and resulted in immunoglobulin (Ig)G overproduction. B cell-specific Gpr55 depletion or adoptive transfer of Gpr55-deficient B cells was sufficient to promote plaque development and elevated IgG titers. In vitro, the endogenous GPR55 ligand lysophsophatidylinositol (LPI) enhanced PC proliferation, whereas GPR55 antagonism blocked PC maturation and increased their mitochondrial content. Collectively, these discoveries provide previously undefined evidence for GPR55 in B cells as a key modulator of the adaptive immune response in atherosclerosis.

Impaired TIGIT expression on B cells drives circulating follicular helper T cell expansion in multiple sclerosis

B cell depletion in patients with relapsing-remitting multiple sclerosis (RRMS) markedly prevents new MRI-detected lesions and disease activity, suggesting the hypothesis that altered B cell function leads to the activation of T cells driving disease pathogenesis. Here, we performed comprehensive analyses of CD40 ligand- (CD40L-) and IL-21-stimulated memory B cells from patients with MS and healthy age-matched controls, modeling the help of follicular helper T cells (Tfh cells), and found a differential gene expression signature in multiple B cell pathways. Most striking was the impaired TIGIT expression on MS-derived B cells mediated by dysregulation of the transcription factor TCF4. Activated circulating Tfh cells (cTfh cells) expressed CD155, the ligand of TIGIT, and TIGIT on B cells revealed their capacity to suppress the proliferation of IL-17-producing cTfh cells via the TIGIT/CD155 axis. Finally, CCR6+ cTfh cells were significantly increased in patients with MS, and their frequency was inversely correlated with that of TIGIT+ B cells. Together, these data suggest that the dysregulation of negative feedback loops between TIGIT+ memory B cells and cTfh cells in MS drives the activated immune system in this disease.

T Cell Help in the Autoreactive Germinal Center

The germinal center serves as a site of B cell selection and affinity maturation, critical processes for productive adaptive immunity. In autoimmune disease tolerance is broken in the germinal center reaction, leading to production of autoreactive B cells that may propagate disease. Follicular T cells are crucial regulators of this process, providing signals necessary for B cell survival in the germinal center. Here we review the emerging roles of follicular T cells in the autoreactive germinal center. Recent advances in immunological techniques have allowed study of the gene expression profiles and repertoire of follicular T cells at unprecedented resolution. These studies provide insight into the potential role follicular T cells play in preventing or facilitating germinal center loss of tolerance. Improved understanding of the mechanisms of T cell help in autoreactive germinal centers provides novel therapeutic targets for diseases of germinal center dysfunction.

The why and how of adaptive immune responses in ischemic cardiovascular disease

Atherosclerotic cardiovascular disease is a major cause of disability and death worldwide. Most therapeutic approaches target traditional risk factors but ignore the fundamental role of the immune system. This is a huge unmet need. Recent evidence indicates that reducing inflammation may limit cardiovascular events. However, the concomitant increase in the risk of lifethreatening infections is a major drawback. In this context, targeting adaptive immunity could constitute a highly effective and safer approach. In this Review, we address the why and how of the immuno-cardiovascular unit, in health and in atherosclerotic disease. We review and discuss fundamental mechanisms that ensure immune tolerance to cardiovascular tissue, and examine how their disruption promotes disease progression. We identify promising strategies to manipulate the adaptive immune system for patient benefit, including novel biologics and RNA-based vaccination strategies. Finally, we advocate for establishing a molecular classification of atherosclerosis as an important milestone in our quest to radically change the understanding and treatment of atherosclerotic disease.

The Spectrum of B Cell Functions in Atherosclerotic Cardiovascular Disease

B cells are a core element of the pathophysiology of atherosclerotic cardiovascular disease (ASCVD). Multiple experimental and epidemiological studies have revealed both protective and deleterious functions of B cells in atherosclerotic plaque formation. The spearhead property of B cells that influences the development of atherosclerosis is their unique ability to produce and secrete high amounts of antigen-specific antibodies that can act at distant sites. Exposure to an atherogenic milieu impacts B cell homeostasis, cell differentiation and antibody production. However, it is not clear whether B cell responses in atherosclerosis are instructed by atherosclerosis-specific antigens (ASA). Dissecting the full spectrum of the B cell properties in atherosclerosis will pave the way for designing innovative therapies against the devastating consequences of ASCVD.

How the immune system shapes atherosclerosis: roles of innate and adaptive immunity

Atherosclerosis is the root cause of many cardiovascular diseases. Extensive research in preclinical models and emerging evidence in humans have established the crucial roles of the innate and adaptive immune systems in driving atherosclerosis-associated chronic inflammation in arterial blood vessels. New techniques have highlighted the enormous heterogeneity of leukocyte subsets in the arterial wall that have pro-inflammatory or regulatory roles in atherogenesis. Understanding the homing and activation pathways of these immune cells, their disease-associated dynamics and their regulation by microbial and metabolic factors will be crucial for the development of clinical interventions for atherosclerosis, including potentially vaccination-based therapeutic strategies. Here, we review key molecular mechanisms of immune cell activation implicated in modulating atherogenesis and provide an update on the contributions of innate and adaptive immune cell subsets in atherosclerosis.

Marginal Zone B-Cell Populations and Their Regulatory Potential in the Context of HIV and Other Chronic Inflammatory Conditions

Inflammation in the context of Human Immunodeficiency Virus (HIV) establishes early and persists beyond antiretroviral therapy (ART). As such, we have shown excess B-cell activating factor (BAFF) in the blood of HIV-infected progressors, as soon as in the acute phase, and despite successful ART. Excess BAFF was associated with deregulation of the B-cell compartment; notably, with increased frequencies of a population sharing features of both transitional immature (TI) and marginal zone (MZ) B-cells, we termed Marginal Zone precursor-like (MZp). We have reported similar observations with HIV-transgenic mice, Simian Immunodeficiency Virus (SIV)-infected macaques, and more recently, with HIV-infected Beninese commercial sex workers, which suggests that excess BAFF and increased frequencies of MZp B-cells are reliable markers of inflammation in the context of HIV. Importantly, we have recently shown that in healthy individuals, MZps present an important regulatory B-cell (Breg) profile and function. Herein, we wish to review our current knowledge on MZ B-cell populations, especially their Breg status, and that of other B-cell populations sharing similar features. BAFF and its analog A Proliferation-Inducing Ligand (APRIL) are important in shaping the MZ B-cell pool; moreover, the impact that excess BAFF—encountered in the context of HIV and several chronic inflammatory conditions—may exert on MZ B-cell populations, Breg and antibody producing capacities is a threat to the self-integrity of their antibody responses and immune surveillance functions. As such, deregulations of MZ B-cell populations contribute to autoimmune manifestations and the development of MZ lymphomas (MZLs) in the context of HIV and other inflammatory diseases. Therefore, further comprehending the mechanisms regulating MZ B-cell populations and their functions could be beneficial to innovative therapeutic avenues that could be deployed to restore MZ B-cell immune competence in the context of chronic inflammation involving excess BAFF.

Splenic Marginal Zone B Lymphocytes Regulate Cardiac Remodeling After Acute Myocardial Infarction in Mice

BACKGROUND

Mature B lymphocytes alter the recovery of cardiac function after acute myocardial infarction (MI) in mice. Follicular B cells and marginal zone B (MZB) cells are spatially distinct mature B-cell populations in the spleen, and they exert specific functional properties. microRNA-21 (miR21)/hypoxia-inducible factor-α (HIF-α)-related pathways have been shown to govern B-cell functions.

OBJECTIVES

The goal of this study was to unravel the distinct role of MZB cells and that of endogenous activation of miR21/HIF-α signaling in MZB cells during post-ischemic injury.

METHODS

Acute MI was induced in mice by permanent ligation of the left anterior descending coronary artery. Cardiac function and remodeling were assessed by using echocardiography and immunohistochemistry. To determine the specific role of MZB cells, the study used mice with B-cell lineage-specific conditional deletion of Notch signaling, which leads to selection deficiency of MZB cells. To evaluate the role of the HIF-1α isoform, mice were generated with MZB-cell lineage-specific conditional deletion of Hif1a.

RESULTS

Acute MI prompted an miR21-dependent increase in HIF-1α, particularly in splenic MZB cells. MZB cell deficiency and MZB cell-specific deletion of miR21 or Hif1a improved cardiac function after acute MI. miR21/HIF-1α signaling in MZB cells was required for Toll-like receptor dependent expression of the monocyte chemoattractant protein CCL7, leading to increased mobilization of inflammatory monocytes to the ischemic myocardium and to adverse post-ischemic cardiac remodeling.

CONCLUSIONS

This work reveals a novel function for the miR21/HIF-1α pathway in splenic MZB cells with potential major implications for the modulation of cardiac function after acute MI.

IFNγ-Stimulated B Cells Inhibit T Follicular Helper Cells and Protect Against Atherosclerosis

B and T cells are interconnected in the T follicular helper—germinal center B cell (T_FH-GC B cell) axis, which is hyperactive during atherosclerosis development and loss of control along this axis results in exacerbated atherosclerosis. Inhibition of the T_FH–GC B cell axis can be achieved by providing negative co-stimulation to T_FH cells through the PD-1/PD-L1 pathway. Therefore, we investigated a novel therapeutic strategy using PD-L1-expressing B cells to inhibit atherosclerosis. We found that IFNγ-stimulated B cells significantly enhanced PD-L1 expression and limited T_FH cell development. To determine whether IFNγ-B cells can reduce collar-induced atherosclerosis, apoE^−/− mice fed a Western-type diet were treated with PBS, B cells or IFNγ-B cells for a total of 5 weeks following collar placement. IFNγ-B cells significantly increased PD-L1^hi GC B cells and reduced plasmablasts. Interestingly, IFNγ-B cells–treated mice show increased atheroprotective Tregs and T cell-derived IL-10. In line with these findings, we observed a significant reduction in total lesion volume in carotid arteries of IFNγ-B cells-treated mice compared to PBS-treated mice and a similar trend was observed compared to B cell-treated mice. In conclusion, our data show that IFNγ-stimulated B cells strongly upregulate PD-L1, inhibit T_FH cell responses and protect against atherosclerosis.

Therapeutic strategies targeting inflammation and immunity in atherosclerosis: how to proceed?

Atherosclerosis is a chronic inflammatory disease of the arterial wall, characterized by the formation of plaques containing lipid, connective tissue and immune cells in the intima of large and medium-sized arteries. Over the past three decades, a substantial reduction in cardiovascular mortality has been achieved largely through LDL-cholesterol-lowering regimes and therapies targeting other traditional risk factors for cardiovascular disease, such as hypertension, smoking, diabetes mellitus and obesity. However, the overall benefits of targeting these risk factors have stagnated, and a huge global burden of cardiovascular disease remains. The indispensable role of immunological components in the establishment and chronicity of atherosclerosis has come to the forefront as a clinical target, with proof-of-principle studies demonstrating the benefit and challenges of targeting inflammation and the immune system in cardiovascular disease. In this Review, we provide an overview of the role of the immune system in atherosclerosis by discussing findings from preclinical research and clinical trials. We also identify important challenges that need to be addressed to advance the field and for successful clinical translation, including patient selection, identification of responders and non-responders to immunotherapies, implementation of patient immunophenotyping and potential surrogate end points for vascular inflammation. Finally, we provide strategic guidance for the translation of novel targets of immunotherapy into improvements in patient outcomes.

In this Review, the authors provide an overview of the immune cells involved in atherosclerosis, discuss preclinical research and published and ongoing clinical trials assessing the therapeutic potential of targeting the immune system in atherosclerosis, highlight emerging therapeutic targets from preclinical studies and identify challenges for successful clinical translation.

Inflammation is an important component of the pathophysiology of cardiovascular disease; an imbalance between pro-inflammatory and anti-inflammatory processes drives chronic inflammation and the formation of atherosclerotic plaques in the vessel wall.

Clinical trials assessing canakinumab and colchicine therapies in atherosclerotic cardiovascular disease have provided proof-of-principle of the benefits associated with therapeutic targeting of the immune system in atherosclerosis.

The immunosuppressive adverse effects associated with the systemic use of anti-inflammatory drugs can be minimized through targeted delivery of anti-inflammatory drugs to the atherosclerotic plaque, defining the window of opportunity for treatment and identifying more specific targets for cardiovascular inflammation.

Implementing immunophenotyping in clinical trials in patients with atherosclerotic cardiovascular disease will allow the identification of immune signatures and the selection of patients with the highest probability of deriving benefit from a specific therapy.

Clinical stratification via novel risk factors and discovery of new surrogate markers of vascular inflammation are crucial for identifying new immunotherapeutic targets and their successful translation into the clinic.

nnResearch progress on B cells and thoracic aortic aneurysm/dissection

Thoracic aortic aneurysm/dissection (TAAD) is a rare cardiovascular disease characterized by acute onset, rapid progression and high morbidity and mortality. One of the crucial factors leading to TAAD is the inflammatory response, which is regulated by many immune cell subgroups, including B cells. Compared with normal aortic tissue, the number of B cells in the aortic tissue of TAAD patients is significantly higher. Activated B cells participate in the vascular immune inflammatory response by producing antibodies and inflammatory factors and activating the complement system. These effects can lead to collagen degradation and aortic wall remodeling, both of which are the main pathologic characteristics of TAAD. Therefore, B cells play a key role in the occurrence and development of TAAD. B cells can be divided into B1 cells, B2 cells and regulatory B cells, which have different mechanisms of action in TAAD. This article will review the role of B cells in TAAD from the perspective of three different subtypes of B cells.

Interleukin-23 receptor expressing γδ T cells locally promote early atherosclerotic lesion formation and plaque necrosis in mice

AIMS

Atherosclerosis is a chronic inflammatory disease of the vessel wall controlled by local and systemic immune responses. The role of interleukin-23 receptor (IL-23R), expressed in adaptive immune cells (mainly T helper 17 cells) and γδ T cells, in atherosclerosis is only incompletely understood. Here we investigated the vascular cell types expressing IL-23R and addressed the function of IL-23R and γδ T cells in atherosclerosis.

METHOD AND RESULTS

IL-23R+ cells were frequently found in the aortic root in contrast to the aorta in low density lipoprotein receptor deficient IL-23R reporter mice (Ldlr-/-Il23rgfp/+), and mostly identified as γδ T cells that express IL-17 and GM-CSF. scRNA-seq confirmed γδ T cells as the main cell type expressing Il23r and Il17a in the aorta. Ldlr-/-Il23rgfp/gfp mice deficient in IL-23R showed a loss of IL-23R+ cells in the vasculature, and had reduced atherosclerotic lesion formation in the aortic root compared to Ldlr-/- controls after 6 weeks of high fat diet feeding. In contrast, Ldlr-/-Tcrδ-/- mice lacking all γδ T cells displayed unaltered early atherosclerotic lesion formation compared to Ldlr-/- mice. In both HFD-fed Ldlr-/-Il23rgfp/gfp and Ldlr-/-Tcrδ-/- mice a reduction in the plaque necrotic core area was noted as well as an expansion of splenic regulatory T cells. In vitro, exposure of bone marrow-derived macrophages to both IL-17A and GM-CSF induced cell necrosis, and necroptotic RIP3K and MLKL expression, as well as inflammatory mediators.

CONCLUSIONS

IL-23R+ γδ T cells are predominantly found in the aortic root rather than the aorta and promote early atherosclerotic lesion formation, plaque necrosis and inflammation at this site. Targeting IL-23R may thus be explored as a therapeutic approach to mitigate atherosclerotic lesion development.

TRANSLATIONAL PERSPECTIVE

The mechanisms and cell types contributing to early inflammation and lesion formation are incompletely understood. Here we demonstrate that the aortic root harbors a population of IL23R-dependent γδ T cells that can release IL-17 and GM-CSF, and both cytokines together induce macrophage inflammation and necroptosis. IL-23R+ γδ T cells locally promote early lesion formation in the aortic root and contribute to the expansion of the necrotic core, a hallmark of vulnerable atherosclerotic lesions. Targeting IL-23R or IL-23 itself could thus be further explored as a therapeutic option in early atherosclerosis.

The Dynamics of B Cell Aging in Health and Disease

Aging is considered to be an important risk factor for several inflammatory diseases. B cells play a major role in chronic inflammatory diseases by antibody secretion, antigen presentation and T cell regulation. Different B cell subsets have been implicated in infections and multiple autoimmune diseases. Since aging decreases B cell numbers, affects B cell subsets and impairs antibody responses, the aged B cell is expected to have major impacts on the development and progression of these diseases. In this review, we summarize the role of B cells in health and disease settings, such as atherosclerotic disease. Furthermore, we provide an overview of age-related changes in B cell development and function with respect to their impact in chronic inflammatory diseases.

B Cell-Activating Factor Antagonism Attenuates the Growth of Experimental Abdominal Aortic Aneurysm

B cell-activating factor (BAFF), a tumor necrosis factor family of cytokine, was recently identified as a regulator of atherosclerosis; however, its role in aortic aneurysm has not been determined. Here, we examined the effect of selective BAFF antagonism using an anti-BAFF antibody (blocks binding of BAFF to receptors BAFF receptor 3, transmembrane activator and CAML interactor, and B-cell maturation antigen) and mBaffR-mFc (blocks binding of BAFF to BAFF receptor 3) on a murine model of abdominal aortic aneurysm (AAA). In a prevention strategy, the antagonists were injected before the induction of AAA, and in an intervention strategy, the antagonists were injected after the induction of AAA. Both strategies attenuated the formation of AAA. In the intervention group, BAFF antagonism depleted most of the mature B-cell subsets in spleen and circulation, leading to enhanced resolution of inflammation in AAA as indicated by decreased infiltration of B cells and proinflammatory macrophages and a reduced number of apoptotic cells. In AAA tissues, B cells and macrophages were found in close contact. In vitro, B cells, irrespective of treatment with BAFF, impaired the efferocytosis activity of macrophages, suggesting a direct innate role of B cells on macrophage function. Altogether, BAFF antagonism affects survival of the mature B cells, promotes resolution of inflammation in the aorta, and attenuates the growth of AAA in mice.

Humoral immunity in atherosclerosis and myocardial infarction: from B cells to antibodies

Immune mechanisms are critically involved in the pathogenesis of atherosclerosis and its clinical manifestations. Associations of specific antibody levels and defined B cell subsets with cardiovascular disease activity in humans as well as mounting evidence from preclinical models demonstrate a role of B cells and humoral immunity in atherosclerotic cardiovascular disease. These include all aspects of B cell immunity, the generation of antigen-specific antibodies, antigen presentation and co-stimulation of T cells, as well as production of cytokines. Through their impact on adaptive and innate immune responses and the regulation of many other immune cells, B cells mediate both protective and detrimental effects in cardiovascular disease. Several antigens derived from (oxidised) lipoproteins, the vascular wall and classical autoantigens have been identified. The unique antibody responses they trigger and their relationship with atherosclerotic cardiovascular disease are reviewed. In particular, we focus on the different effector functions of specific IgM, IgG, and IgE antibodies and the cellular responses they trigger and highlight potential strategies to target B cell functions for therapy.

The Emerging Role of B Lymphocytes in Cardiovascular Disease

B cells are traditionally known for their ability to produce antibodies in the context of adaptive immune responses. However, over the last decade B cells have been increasingly recognized as modulators of both adaptive and innate immune responses, as well as players in an important role in the pathogenesis of a variety of human diseases. Here, after briefly summarizing our current understanding of B cell biology, we present a systematic review of the literature from both animal models and human studies that highlight the important role that B lymphocytes play in cardiac and vascular disease. While many aspects of B cell biology in the vasculature and, to an even greater extent, in the heart remain unclear, B cells are emerging as key regulators of cardiovascular adaptation to injury.