Single-cell analysis of fate-mapped macrophages reveals heterogeneity, including stem-like properties, during atherosclerosis progression and regression

Infiltrating lipid-rich macrophage subpopulations identified as a regulator of increasing prostate size in human benign prostatic hyperplasia

Macrophages exhibit marked phenotypic heterogeneity within and across disease states, with lipid metabolic reprogramming contributing to macrophage activation and heterogeneity. Chronic inflammation has been observed in human benign prostatic hyperplasia (BPH) tissues, however macrophage activation states and their contributions to this hyperplastic disease have not been defined. We postulated that a shift in macrophage phenotypes with increasing prostate size could involve metabolic alterations resulting in prostatic epithelial or stromal hyperplasia. Single-cell RNA-seq of CD45+ transition zone leukocytes from 10 large (>90 grams) and 10 small (<40 grams) human prostates was conducted. Macrophage subpopulations were defined using marker genes. BPH macrophages do not distinctly categorize into M1 and M2 phenotypes. Instead, macrophages with neither polarization signature preferentially accumulate in large versus small prostates. Specifically, macrophage subpopulations with altered lipid metabolism pathways, demarcated by TREM2 and MARCO expression, significantly accumulate with increased prostate volume. TREM2+ and MARCO+ macrophage abundance positively correlates with patient body mass index and urinary symptom scores. TREM2+ macrophages have significantly higher neutral lipid than TREM2- macrophages from BPH tissues. Lipid-rich macrophages were observed to localize within the stroma in BPH tissues. In vitro studies indicate that lipid-loaded macrophages increase prostate epithelial and stromal cell proliferation compared to control macrophages. These data define two new BPH immune subpopulations, TREM2+ and MARCO+ macrophages, and suggest that lipid-rich macrophages may exacerbate lower urinary tract symptoms in patients with large prostates. Further investigation is needed to evaluate the therapeutic benefit of targeting these cells in BPH.

Molecular fingerprints of cardiovascular toxicities of immune checkpoint inhibitors

Immune checkpoint inhibitors (ICIs) have revolutionized cancer therapy by unleashing the power of the immune system against malignant cells. However, their use is associated with a spectrum of adverse effects, including cardiovascular complications, which can pose significant clinical challenges. Several mechanisms contribute to cardiovascular toxicity associated with ICIs. First, the dysregulation of immune checkpoints, such as cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) and programmed cell death protein-1 (PD-1) and its ligand (PD-L1), and molecular mimicry with cardiac autoantigens, leads to immune-related adverse events, including myocarditis and vasculitis. These events result from the aberrant activation of T cells against self-antigens within the myocardium or vascular endothelium. Second, the disruption of immune homeostasis by ICIs can lead to autoimmune-mediated inflammation of cardiac tissues, manifesting as cardiac dysfunction and heart failure, arrhythmias, or pericarditis. Furthermore, the upregulation of inflammatory cytokines, particularly tumor necrosis factor-alpha, interferon-γ, interleukin-1β, interleukin-6, and interleukin-17 contributes to cardiac and endothelial dysfunction, plaque destabilization, and thrombosis, exacerbating cardiovascular risk on the long term. Understanding the intricate mechanisms of cardiovascular side effects induced by ICIs is crucial for optimizing patient care and to ensure the safe and effective integration of immunotherapy into a broader range of cancer treatment protocols. The clinical implications of these mechanisms underscore the importance of vigilant monitoring and early detection of cardiovascular toxicity in patients receiving ICIs. Future use of these key pathological mediators as biomarkers may aid in prompt diagnosis of cardiotoxicity and will allow timely interventions.

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.

Significance of neutrophil extracellular traps-related gene in the diagnosis and classification of atherosclerosis

Atherosclerosis (AS) is a pathological process associated with various cardiovascular diseases. Upon different stimuli, neutrophils release reticular complexes known as neutrophil extracellular traps (NETs). Numerous researches have indicated a strong correlation between NETs and AS. However, its role in cardiovascular disease requires further investigation. By utilizing a machine learning algorithm, we examined the genes associated with NETs that were expressed differently in individuals with AS compared to normal controls. As a result, we identified four distinct genes. A nomogram model was built to forecast the incidence of AS. Additionally, we conducted analysis on immune infiltration, functional enrichment and consensus clustering in AS samples. The findings indicated that individuals with AS could be categorized into two groups, exhibiting notable variations in immune infiltration traits among the groups. Furthermore, to measure the NETs model, the principal component analysis algorithm was developed and cluster B outperformed cluster A in terms of NETs. Additionally, there were variations in the expression of multiple chemokines between the two subtypes. By studying AS NETs, we acquired fresh knowledge about the molecular patterns and immune mechanisms implicated, which could open up new possibilities for AS immunotherapy.

Macrophages in cardiovascular diseases: molecular mechanisms and therapeutic targets

The immune response holds a pivotal role in cardiovascular disease development. As multifunctional cells of the innate immune system, macrophages play an essential role in initial inflammatory response that occurs following cardiovascular injury, thereby inducing subsequent damage while also facilitating recovery. Meanwhile, the diverse phenotypes and phenotypic alterations of macrophages strongly associate with distinct types and severity of cardiovascular diseases, including coronary heart disease, valvular disease, myocarditis, cardiomyopathy, heart failure, atherosclerosis and aneurysm, which underscores the importance of investigating macrophage regulatory mechanisms within the context of specific diseases. Besides, recent strides in single-cell sequencing technologies have revealed macrophage heterogeneity, cell-cell interactions, and downstream mechanisms of therapeutic targets at a higher resolution, which brings new perspectives into macrophage-mediated mechanisms and potential therapeutic targets in cardiovascular diseases. Remarkably, myocardial fibrosis, a prevalent characteristic in most cardiac diseases, remains a formidable clinical challenge, necessitating a profound investigation into the impact of macrophages on myocardial fibrosis within the context of cardiac diseases. In this review, we systematically summarize the diverse phenotypic and functional plasticity of macrophages in regulatory mechanisms of cardiovascular diseases and unprecedented insights introduced by single-cell sequencing technologies, with a focus on different causes and characteristics of diseases, especially the relationship between inflammation and fibrosis in cardiac diseases (myocardial infarction, pressure overload, myocarditis, dilated cardiomyopathy, diabetic cardiomyopathy and cardiac aging) and the relationship between inflammation and vascular injury in vascular diseases (atherosclerosis and aneurysm). Finally, we also highlight the preclinical/clinical macrophage targeting strategies and translational implications.

The role of macrophage polarization in vascular calcification

Vascular calcification is an important factor in the high morbidity and mortality of Cardiovascular and cerebrovascular diseases. Vascular damage caused by calcification of the intima or media impairs the physiological function of the vascular wall. Inflammation is a central factor in the development of vascular calcification. Macrophages are the main inflammatory cells. Dynamic changes of macrophages with different phenotypes play an important role in the occurrence, progression and stability of calcification. This review focuses on macrophage polarization and the relationship between macrophages of different phenotypes and calcification environment, as well as the mechanism of interaction, it is considered that macrophages can promote vascular calcification by releasing inflammatory mediators and promoting the osteogenic transdifferentiation of smooth muscle cells and so on. In addition, several therapeutic strategies aimed at macrophage polarization for vascular calcification are described, which are of great significance for targeted treatment of vascular calcification.

Metabolism-inflammasome crosstalk shapes innate and adaptive immunity

Inflammasomes are a central component of innate immunity and play a vital role in regulating innate immune response. Activation of inflammasomes is also indispensable for adaptive immunity, modulating the development and response of adaptive immunity. Recently, increasing studies have shown that metabolic alterations and adaptations strongly influence and regulate the differentiation and function of the immune system. In this review, we will take a holistic view of how inflammasomes bridge innate and adaptive (especially T cell) immunity and how inflammasomes crosstalk with metabolic signals during the immune responses. And, special attention will be paid to the metabolic control of inflammasome-mediated interactions between innate and adaptive immunity in disease. Understanding the metabolic regulatory functions of inflammasomes would provide new insights into future research directions in this area and may help to identify potential targets for inflammasome-associated diseases and broaden therapeutic avenues.

Tryptophan Metabolism in Alzheimer's Disease with the Involvement of Microglia and Astrocyte Crosstalk and Gut-Brain Axis

Alzheimer's disease (AD) is an age-dependent neurodegenerative disease characterized by extracellular Amyloid Aβ peptide (Aβ) deposition and intracellular Tau protein aggregation. Glia, especially microglia and astrocytes are core participants during the progression of AD and these cells are the mediators of Aβ clearance and degradation. The microbiota-gut-brain axis (MGBA) is a complex interactive network between the gut and brain involved in neurodegeneration. MGBA affects the function of glia in the central nervous system (CNS), and microbial metabolites regulate the communication between astrocytes and microglia; however, whether such communication is part of AD pathophysiology remains unknown. One of the potential links in bilateral gut-brain communication is tryptophan (Trp) metabolism. The microbiota-originated Trp and its metabolites enter the CNS to control microglial activation, and the activated microglia subsequently affect astrocyte functions. The present review highlights the role of MGBA in AD pathology, especially the roles of Trp per se and its metabolism as a part of the gut microbiota and brain communications. We (i) discuss the roles of Trp derivatives in microglia-astrocyte crosstalk from a bioinformatics perspective, (ii) describe the role of glia polarization in the microglia-astrocyte crosstalk and AD pathology, and (iii) summarize the potential of Trp metabolism as a therapeutic target. Finally, we review the role of Trp in AD from the perspective of the gut-brain axis and microglia, as well as astrocyte crosstalk, to inspire the discovery of novel AD therapeutics.

Lipid-associated macrophages between aggravation and alleviation of metabolic diseases

Lipid-associated macrophages (LAMs) are phagocytic cells with lipid-handling capacity identified in various metabolic derangements. During disease development, they locate to atherosclerotic plaques, adipose tissue (AT) of individuals with obesity, liver lesions in steatosis and steatohepatitis, and the intestinal lamina propria. LAMs can also emerge in the metabolically demanding microenvironment of certain tumors. In this review, we discuss major questions regarding LAM recruitment, differentiation, and self-renewal, and, ultimately, their acute and chronic functional impact on the development of metabolic diseases. Further studies need to clarify whether and under which circumstances LAMs drive disease progression or resolution and how their phenotype can be modulated to ameliorate metabolic disorders.

PROSTATE CELL HETEROGENEITY AND CXCL17 UPREGULATION IN MOUSE STEROID HORMONE IMBALANCE

Benign prostatic hyperplasia (BPH) is a prevalent age-related condition often characterized by debilitating urinary symptoms. Its etiology is believed to stem from hormonal imbalance, particularly an elevated estradiol-to-testosterone ratio and chronic inflammation. Our previous studies using a mouse steroid hormone imbalance model identified a specific increase in macrophages that migrate and accumulate in the prostate lumen where they differentiate into lipid-laden foam cells in mice implanted with testosterone and estradiol pellets, but not in sham animals. The current study focused on further characterizing the cellular heterogeneity of the prostate in this model as well as identifying the specific transcriptomic signature of the recruited foam cells. Moreover, we aimed to identify the epithelia-derived signals that drive macrophage infiltration and luminal translocation. Male C57BL/6J mice were implanted with slow-release testosterone and estradiol pellets (T+E2) and harvested the ventral prostates two weeks later for scRNA-seq analysis, or performed sham surgery. We identified Ear2+ and Cd72+ macrophages that were elevated in response to steroid hormone imbalance, whereas a Mrc1+ resident macrophage population did not change. In addition, an Spp1+ foam cell cluster was almost exclusively found in T+E2 mice. Further markers of foam cells were also identified, including Gpnmb and Trem2, and GPNMB was confirmed as a novel histological marker with immunohistochemistry. Foam cells were also shown to express known pathological factors Vegf, Tgfb1, Ccl6, Cxcl16 and Mmp12. Intriguingly, a screen for chemokines identified the upregulation of epithelial-derived Cxcl17, a known monocyte attractant, in T+E2 prostates suggesting that it might be responsible for the elevated macrophage number as well as their translocation to the lumen. Our study identified macrophage subsets that respond to steroid hormone imbalance as well as further confirmed a potential pathological role of luminal foam cells in the prostate. These results underscore a pathological role of the identified prostate foam cells and suggests CXCL17-mediated macrophage migration as a critical initiating event.

MNDA, a PYHIN factor involved in transcriptional regulation and apoptosis control in leukocytes

Inflammation control is critical during the innate immune response. Such response is triggered by the detection of molecules originating from pathogens or damaged host cells by pattern-recognition receptors (PRRs). PRRs subsequently initiate intra-cellular signalling through different pathways, resulting in i) the production of inflammatory cytokines, including type I interferon (IFN), and ii) the initiation of a cascade of events that promote both immediate host responses as well as adaptive immune responses. All human PYRIN and HIN-200 domains (PYHIN) protein family members were initially proposed to be PRRs, although this view has been challenged by reports that revealed their impact on other cellular mechanisms. Of relevance here, the human PYHIN factor myeloid nuclear differentiation antigen (MNDA) has recently been shown to directly control the transcription of genes encoding factors that regulate programmed cell death and inflammation. While MNDA is mainly found in the nucleus of leukocytes of both myeloid (neutrophils and monocytes) and lymphoid (B-cell) origin, its subcellular localization has been shown to be modulated in response to genotoxic agents that induce apoptosis and by bacterial constituents, mediators of inflammation. Prior studies have noted the importance of MNDA as a marker for certain forms of lymphoma, and as a clinical prognostic factor for hematopoietic diseases characterized by defective regulation of apoptosis. Abnormal expression of MNDA has also been associated with altered levels of cytokines and other inflammatory mediators. Refining our comprehension of the regulatory mechanisms governing the expression of MNDA and other PYHIN proteins, as well as enhancing our definition of their molecular functions, could significantly influence the management and treatment strategies of numerous human diseases. Here, we review the current state of knowledge regarding PYHIN proteins and their role in innate and adaptive immune responses. Emphasis will be placed on the regulation, function, and relevance of MNDA expression in the control of gene transcription and RNA stability during cell death and inflammation.

High-Dimensional Single-Cell Multimodal Landscape of Human Carotid Atherosclerosis

BACKGROUND

Atherosclerotic plaques are complex tissues composed of a heterogeneous mixture of cells. However, our understanding of the comprehensive transcriptional and phenotypic landscape of the cells within these lesions is limited.

METHODS

To characterize the landscape of human carotid atherosclerosis in greater detail, we combined cellular indexing of transcriptomes and epitopes by sequencing and single-cell RNA sequencing to classify all cell types within lesions (n=21; 13 symptomatic) to achieve a comprehensive multimodal understanding of the cellular identities of atherosclerosis and their association with clinical pathophysiology.

RESULTS

We identified 25 cell populations, each with a unique multiomic signature, including macrophages, T cells, NK (natural killer) cells, mast cells, B cells, plasma cells, neutrophils, dendritic cells, endothelial cells, fibroblasts, and smooth muscle cells (SMCs). Among the macrophages, we identified 2 proinflammatory subsets enriched in IL-1B (interleukin-1B) or C1Q expression, 2 TREM2-positive foam cells (1 expressing inflammatory genes), and subpopulations with a proliferative gene signature and SMC-specific gene signature with fibrotic pathways upregulated. Further characterization revealed various subsets of SMCs and fibroblasts, including SMC-derived foam cells. These foamy SMCs were localized in the deep intima of coronary atherosclerotic lesions. Utilizing cellular indexing of transcriptomes and epitopes by sequencing data, we developed a flow cytometry panel, using cell surface proteins CD29, CD142, and CD90, to isolate SMC-derived cells from lesions. Lastly, we observed reduced proportions of efferocytotic macrophages, classically activated endothelial cells, and contractile and modulated SMC-derived cells, while inflammatory SMCs were enriched in plaques of clinically symptomatic versus asymptomatic patients.

CONCLUSIONS

Our multimodal atlas of cell populations within atherosclerosis provides novel insights into the diversity, phenotype, location, isolation, and clinical relevance of the unique cellular composition of human carotid atherosclerosis. These findings facilitate both the mapping of cardiovascular disease susceptibility loci to specific cell types and the identification of novel molecular and cellular therapeutic targets for the treatment of the disease.

Omics Approaches Unveiling the Biology of Human Atherosclerotic Plaques

Atherosclerosis is a chronic inflammatory disease of the arterial wall, characterized by the buildup of plaques with the accumulation and transformation of lipids, immune cells, vascular smooth muscle cells, and necrotic cell debris. Plaques with collagen-poor thin fibrous caps infiltrated by macrophages and lymphocytes are considered unstable because they are at the greatest risk of rupture and clinical events. However, the current histologic definition of plaque types may not fully capture the complex molecular nature of atherosclerotic plaque biology and the underlying mechanisms contributing to plaque progression, rupture, and erosion. The advances in omics technologies have changed the understanding of atherosclerosis plaque biology, offering new possibilities to improve risk prediction and discover novel therapeutic targets. Genomic studies have shed light on the genetic predisposition to atherosclerosis, and integrative genomic analyses expedite the translation of genomic discoveries. Transcriptomic, proteomic, metabolomic, and lipidomic studies have refined the understanding of the molecular signature of atherosclerotic plaques, aiding in data-driven hypothesis generation for mechanistic studies and offering new prospects for biomarker discovery. Furthermore, advancements in single-cell technologies and emerging spatial analysis techniques have unveiled the heterogeneity and plasticity of plaque cells. This review discusses key omics-based discoveries that have advanced the understanding of human atherosclerotic plaque biology, focusing on insights derived from omics profiling of human atherosclerotic vascular specimens.

Vascular damage in systemic lupus erythematosus

Vascular disease is a major cause of morbidity and mortality in patients with systemic autoimmune diseases, particularly systemic lupus erythematosus (SLE). Although comorbid cardiovascular risk factors are frequently present in patients with SLE, they do not explain the high burden of premature vascular disease. Profound innate and adaptive immune dysregulation seems to be the primary driver of accelerated vascular damage in SLE. In particular, evidence suggests that dysregulation of type 1 interferon (IFN-I) and aberrant neutrophils have key roles in the pathogenesis of vascular damage. IFN-I promotes endothelial dysfunction directly via effects on endothelial cells and indirectly via priming of immune cells that contribute to vascular damage. SLE neutrophils are vasculopathic in part because of their increased ability to form immunostimulatory neutrophil extracellular traps. Despite improvements in clinical care, cardiovascular disease remains the leading cause of mortality among patients with SLE, and treatments that improve vascular outcomes are urgently needed. Improved understanding of the mechanisms of vascular injury in inflammatory conditions such as SLE could also have implications for common cardiovascular diseases, such as atherosclerosis and hypertension, and may ultimately lead to personalized therapeutic approaches to the prevention and treatment of this potentially fatal complication.

BHLHE40/41 regulate microglia and peripheral macrophage responses associated with Alzheimer's disease and other disorders of lipid-rich tissues

Genetic and experimental evidence suggests that Alzheimer's disease (AD) risk alleles and genes may influence disease susceptibility by altering the transcriptional and cellular responses of macrophages, including microglia, to damage of lipid-rich tissues like the brain. Recently, sc/nRNA sequencing studies identified similar transcriptional activation states in subpopulations of macrophages in aging and degenerating brains and in other diseased lipid-rich tissues. We collectively refer to these subpopulations of microglia and peripheral macrophages as DLAMs. Using macrophage sc/nRNA-seq data from healthy and diseased human and mouse lipid-rich tissues, we reconstructed gene regulatory networks and identified 11 strong candidate transcriptional regulators of the DLAM response across species. Loss or reduction of two of these transcription factors, BHLHE40/41, in iPSC-derived microglia and human THP-1 macrophages as well as loss of Bhlhe40/41 in mouse microglia, resulted in increased expression of DLAM genes involved in cholesterol clearance and lysosomal processing, increased cholesterol efflux and storage, and increased lysosomal mass and degradative capacity. These findings provide targets for therapeutic modulation of macrophage/microglial function in AD and other disorders affecting lipid-rich tissues.

Developmental heterogeneity of vascular cells: Insights into cellular plasticity in atherosclerosis?

Smooth muscle cells, endothelial cells and macrophages display remarkable heterogeneity within the healthy vasculature and under pathological conditions. During development, these cells arise from numerous embryological origins, which confound with different microenvironments to generate postnatal vascular cell diversity. In the atherosclerotic plaque milieu, all these cell types exhibit astonishing plasticity, generating a variety of plaque burdening or plaque stabilizing phenotypes. And yet how developmental origin influences intraplaque cell plasticity remains largely unexplored despite evidence suggesting this may be the case. Uncovering the diversity and plasticity of vascular cells is being revolutionized by unbiased single cell whole transcriptome analysis techniques that will likely continue to pave the way for therapeutic research. Cellular plasticity is only just emerging as a target for future therapeutics, and uncovering how intraplaque plasticity differs across vascular beds may provide key insights into why different plaques behave differently and may confer different risks of subsequent cardiovascular events.

Orchestrating Resilience: How Neuropilin-2 and Macrophages Contribute to Cardiothoracic Disease

Immunity has evolved to balance the destructive nature of inflammation with wound healing to overcome trauma, infection, environmental insults, and rogue malignant cells. The inflammatory response is marked by overlapping phases of initiation, resolution, and post-resolution remodeling. However, the disruption of these events can lead to prolonged tissue damage and organ dysfunction, resulting long-term disease states. Macrophages are the archetypic phagocytes present within all tissues and are important contributors to these processes. Pleiotropic and highly plastic in their responses, macrophages support tissue homeostasis, repair, and regeneration, all while balancing immunologic self-tolerance with the clearance of noxious stimuli, pathogens, and malignant threats. Neuropilin-2 (Nrp2), a promiscuous co-receptor for growth factors, semaphorins, and integrins, has increasingly been recognized for its unique role in tissue homeostasis and immune regulation. Notably, recent studies have begun to elucidate the role of Nrp2 in both non-hematopoietic cells and macrophages with cardiothoracic disease. Herein, we describe the unique role of Nrp2 in diseases of the heart and lung, with an emphasis on Nrp2 in macrophages, and explore the potential to target Nrp2 as a therapeutic intervention.

Macrophage-targeted ultrasound nanobubbles for highly efficient sonodynamic therapy of atherosclerotic plaques by modulating M1-to-M2 polarization

BACKGROUND AND AIMS

Sonodynamic therapy (SDT) is a new approach for the treatment of atherosclerosis (AS), yet the poor targeting ability of sonosensitizers limits its therapeutic efficacy. Herein, we reported a plaque-targeted nanoplatform modified with macrophage type A scavenger receptor (SR-A)-targeted peptide (designated as SR-A-Ce6NB) to augment the efficacy of low-intensity pulsed ultrasound (LIPUS)-mediated SDT of atherosclerotic plaque.

METHODS

SR-A-Ce6NB was fabricated by thin hydration method and biotin-avidin system, and its physicochemical properties, biocompatibility and plaque-targeting ability were investigated. RAW 264.7 cells were used for in vitro experimental studies. Male 6-week-old apolipoprotein E-deficient mice were fed a high-fat diet for 16 weeks to induce aortic atherosclerotic plaques. Plaque-bearing mice were randomly allocated into five groups (n = 6): control group, Ce6 + LIPUS group, Ce6NB + LIPUS group, SR-A-Ce6NB + LIPUS group and atorvastatin group. After treatment in each group, the aortic artery was harvested for Oil red O, H&E, Masson's trichrome staining, immunohistochemical and immunofluorescent staining.

RESULTS

SR-A-Ce6NB with high stability and excellent biocompatibility was successfully fabricated. SR-A-Ce6NB could actively target activated macrophages and selectively accumulate in the plaque. SR-A-Ce6NB could be triggered by LIPUS and had a more potent sonodynamic effect than free Ce6 to potentiate SDT. SR-A-Ce6NB-mediated SDT enhanced the anti-atherogenic effect via modulating M1-to-M2 macrophage polarization and had an earlier onset of action on plaque than the statin-mediated effect. No apparent side effect was observed after intravenous SR-A-Ce6NB injection and LIPUS exposure.

CONCLUSIONS

Macrophage-targeted nanoplatform SR-A-Ce6NB-mediated SDT provides a safe, effective and preferable anti-atherogenic therapy by mediating M1-to-M2 macrophage polarization.

The Characteristics of Macrophage Heterogeneity in Atherosclerotic Aortas

Macrophage is the main effector cell during atherosclerosis. We applied single-cell RNA sequencing (scRNA) data to investigate the role of macrophage subsets in atherosclerosis. Monocyte and macrophage clusters were divided into 6 subclusters. Each subcluster's markers were calculated and validated by immunofluorescence. Elevated macrophage subclusters in the WD group were subject to enrichment pathway analysis and exhibited different phenotypes. Pseudotime analysis shows the subclusters originate from monocytes. We cultured bone marrow-derived macrophages with CSF-1 and ox-LDL to simulate an atherosclerotic-like environment and detected the transformation of subclusters. Macrophage-Vegfa and Macrophage-C1qb increased in the WD group. Macrophage-Vegfa acquires the characteristics of phagocytosis and immune response, while Macrophage-C1qb is not involved in lipid metabolism. The two subclusters are both enriched in cell movement and migration pathways. Experimental verification proved Monocyte-Ly6C evolved into Macrophage-Vegfa and Macrophage-C1qb during atherosclerosis progression.

Macrophage-based therapeutic approaches for cardiovascular diseases

Despite the advances in treatment options, cardiovascular disease (CVDs) remains the leading cause of death over the world. Chronic inflammatory response and irreversible fibrosis are the main underlying pathophysiological causes of progression of CVDs. In recent decades, cardiac macrophages have been recognized as main regulatory players in the development of these complex pathophysiological conditions. Numerous approaches aimed at macrophages have been devised, leading to novel prospects for therapeutic interventions. Our review covers the advancements in macrophage-centric treatment plans for various pathologic conditions and examines the potential consequences and obstacles of employing macrophage-targeted techniques in cardiac diseases.

The lncRNA GAS5 upregulates ANXA2 to mediate the macrophage inflammatory response during atherosclerosis development

Inflammatory macrophages play a crucial role in atherosclerosis development. The long non-coding RNA growth arrest-specific 5 (GAS5) regulates THP-1 macrophage inflammation by sponging microRNAs. The purpose of this study was to investigate the regulatory mechanism of GAS5 in atherosclerosis development. GSE40231, GSE21545, and GSE28829 datasets from the Gene Expression Omnibus database were integrated after adjusting for batch effect. Differential analysis was performed on the integrated dataset and validated using the Genotype-Tissue Expression and GSE57691 datasets. Potential biological functions of GAS5 and annexin A2 (ANXA2) were identified using gene set enrichment analysis (GSEA). ssGSEA, CIBERSORTx, and ImmuCellAI algorithms were used to identify immune infiltration in plaque samples. GAS5 and ANXA2 expression levels in RAW264.7 cells treated with oxidized low-density lipoprotein (ox-LDL) were measured by qRT-PCR and Western blot. Small interfering and short hairpin RNA were used to silence GAS5 expression. Plasmids of ANXA2 were used to establish ANXA2 overexpression. Apoptosis and inflammatory markers in macrophages were detected by Western blot. Aortic samples from APOE-/- mice were collected to validate the expression of GAS5 and ANXA2. GAS5 expression was significantly increased during atherosclerosis. GAS5 expression was positively correlated with macrophage activation and ANXA2 expression in plaques. Furthermore, ANXA2 upregulation was also related to the activation of macrophage. GSEA indicated similar biological functions for GAS5 and ANXA2 in plaques. Moreover, in vitro experiments showed that both GAS5 and ANXA2 contributed to macrophage apoptosis and inflammation. Rescue assays revealed that the inflammatory effects of GAS5 on macrophages were ANXA2-dependent. In vivo experiments confirmed the highly expression of Gas5 and Anxa2 in the plaque group. We identified the atherogenic roles of GAS5 and ANXA2 in the inflammatory response of macrophages. The inflammatory response in ox-LDL-treated macrophages was found to be mediated by GAS5-ANXA2 regulation, opening new avenues for atherosclerosis therapy.

Emerging applications of single-cell profiling in precision medicine of atherosclerosis

Atherosclerosis is a chronic, progressive, inflammatory disease that occurs in the arterial wall. Despite recent advancements in treatment aimed at improving efficacy and prolonging survival, atherosclerosis remains largely incurable. In this review, we discuss emerging single-cell sequencing techniques and their novel insights into atherosclerosis. We provide examples of single-cell profiling studies that reveal phenotypic characteristics of atherosclerosis plaques, blood, liver, and the intestinal tract. Additionally, we highlight the potential clinical applications of single-cell analysis and propose that combining this approach with other techniques can facilitate early diagnosis and treatment, leading to more accurate medical interventions.

Clonal Expansion in Cardiovascular Pathology

Clonal expansion refers to the proliferation and selection of advantageous "clones" that are better suited for survival in a Darwinian manner. In recent years, we have greatly enhanced our understanding of cell clonality in the cardiovascular context. However, our knowledge of the underlying mechanisms behind this clonal selection is still severely limited. There is a transpiring pattern of clonal expansion of smooth muscle cells and endothelial cells-and, in some cases, macrophages-in numerous cardiovascular diseases irrespective of their differing microenvironments. These findings indirectly suggest the possible existence of stem-like vascular cells which are primed to respond during disease. Subsequent clones may undergo further phenotypic changes to adopt either protective or detrimental roles. By investigating these clone-forming vascular cells, we may be able to harness this inherent clonal nature for future therapeutic intervention. This review comprehensively discusses what is currently known about clonal expansion across the cardiovascular field. Comparisons of the clonal nature of vascular cells in atherosclerosis (including clonal hematopoiesis of indeterminate potential), pulmonary hypertension, aneurysm, blood vessel injury, ischemia- and tumor-induced angiogenesis, and cerebral cavernous malformations are evaluated. Finally, we discuss the potential clinical implications of these findings and propose that proper understanding and specific targeting of these clonal cells may provide unique therapeutic options for the treatment of these cardiovascular conditions.

Immune Homeostasis Maintenance Through Advanced Immune Therapeutics to Target Atherosclerosis

Atherosclerosis remains the leading cause of coronary heart disease (CHD) with enormous health and societal tolls. Traditional drug development approaches have been focused on small molecule-based compounds that aim to lower plasma lipids and reduce systemic inflammation, two primary causes of atherosclerosis. However, despite the widely available lipid-lowering and anti-inflammatory small compounds and biologic agents, CHD prevalence still remains high. Based on recent advances revealing disrupted immune homeostasis during atherosclerosis pathogenesis, novel strategies aimed at rejuvenating immune homeostasis with engineered immune leukocytes are being developed. This chapter aims to assess basic and translational efforts on these emerging strategies for the effective development of atherosclerosis treatment, as well as key challenges in this important translational field.

Macrophage heterogeneity in atherosclerosis: A matter of context

During atherogenesis, plaque macrophages take up and process deposited lipids, trigger inflammation, and form necrotic cores. The traditional inflammatory/anti-inflammatory paradigm has proven insufficient in explaining their complex disease-driving mechanisms. Instead, we now appreciate that macrophages exhibit remarkable heterogeneity and functional specialization in various pathological contexts, including atherosclerosis. Technical advances for studying individual cells, especially single-cell RNA sequencing, indeed allowed to identify novel macrophage subsets in both murine and human atherosclerosis, highlighting the existence of diverse macrophage activation states throughout pathogenesis. In addition, recent studies highlighted the role of the local microenvironment in shaping the macrophages' phenotype and function. However, this remains largely undescribed in the context of atherosclerosis. In this review we explore the origins of macrophages and their functional specialization, shedding light on the diverse sources of macrophage accumulation in the atherosclerotic plaque. Next, we discuss the phenotypic diversity observed in both murine and human atherosclerosis, elucidating their distinct functions and spatial distribution within plaques. Finally, we highlight the importance of the local microenvironment in both phenotypic and functional specialization of macrophages in atherosclerosis and elaborate on the need for spatial multiomics approaches to provide a better understanding of the different macrophage subsets' roles in the pathogenesis of atherosclerosis.

An integrative analysis of single-cell and bulk transcriptome and bidirectional mendelian randomization analysis identified C1Q as a novel stimulated risk gene for Atherosclerosis

Background

The role of complement component 1q (C1Q) related genes on human atherosclerotic plaques (HAP) is less known. Our aim is to establish C1Q associated hub genes using single-cell RNA sequencing (scRNA-seq) and bulk RNA analysis to diagnose and predict HAP patients more effectively and investigate the association between C1Q and HAP (ischemic stroke) using bidirectional Mendelian randomization (MR) analysis.

Methods

HAP scRNA-seq and bulk-RNA data were download from the Gene Expression Omnibus (GEO) database. The C1Q-related hub genes was screened using the GBM, LASSO and XGBoost algorithms. We built machine learning models to diagnose and distinguish between types of atherosclerosis using generalized linear models and receiver operating characteristics (ROC) analyses. Further, we scored the HALLMARK_COMPLEMENT signaling pathway using ssGSEA and confirmed hub gene expression through qRT-PCR in RAW264.7 macrophages and apoE-/- mice. Furthermore, the risk association between C1Q and HAP was assessed through bidirectional MR analysis, with C1Q as exposure and ischemic stroke (IS, large artery atherosclerosis) as outcomes. Inverse variance weighting (IVW) was used as the main method.

Results

We utilized scRNA-seq dataset (GSE159677) to identify 24 cell clusters and 12 cell types, and revealed seven C1Q associated DEGs in both the scRNA-seq and GEO datasets. We then used GBM, LASSO and XGBoost to select C1QA and C1QC from the seven DEGs. Our findings indicated that both training and validation cohorts had satisfactory diagnostic accuracy for identifying patients with HPAs. Additionally, we confirmed SPI1 as a potential TF responsible for regulating the two hub genes in HAP. Our analysis further revealed that the HALLMARK_COMPLEMENT signaling pathway was correlated and activated with C1QA and C1QC. We confirmed high expression levels of C1QA, C1QC and SPI1 in ox-LDL-treated RAW264.7 macrophages and apoE-/- mice using qPCR. The results of MR indicated that there was a positive association between the genetic risk of C1Q and IS, as evidenced by an odds ratio (OR) of 1.118 (95%CI: 1.013-1.234, P = 0.027).

Conclusion

The authors have effectively developed and validated a novel diagnostic signature comprising two genes for HAP, while MR analysis has provided evidence supporting a favorable association of C1Q on IS.

Immunotherapy-Associated Atherosclerosis: A Comprehensive Review of Recent Findings and Implications for Future Research

Purpose of the Review

Even as immune checkpoint inhibitors (ICIs) have transformed the lifespan of many patients, they may also trigger acceleration of long-term cardiovascular disease. Our review aims to examine the current landscape of research on ICI-mediated atherosclerosis and address key questions regarding its pathogenesis and impact on patient management.

Recent Findings

Preclinical mouse models suggest that T cell dysregulation and proatherogenic cytokine production are key contributors to plaque development after checkpoint inhibition. Clinical data also highlight the significant burden of atherosclerotic cardiovascular disease (ASCVD) in patients on immunotherapy, although the value of proactively preventing and treating ASCVD in this population remains an open area of inquiry. Current treatment options include dietary/lifestyle modification and traditional medications to manage hypertension, hyperlipidemia, and diabetes risk factors; no current targeted therapies exist.

Summary

Early identification of high-risk patients is crucial for effective preventive strategies and timely intervention. Future research should focus on refining screening tools, elucidating targetable mechanisms driving ICI atherosclerosis, and evaluating long-term cardiovascular outcomes in cancer survivors who received immunotherapy. Moreover, close collaboration between oncologists and cardiologists is essential to optimize patient outcomes.

Itaconate suppresses atherosclerosis by activating a Nrf2-dependent antiinflammatory response in macrophages in mice

Itaconate has emerged as a critical immunoregulatory metabolite. Here, we examined the therapeutic potential of itaconate in atherosclerosis. We found that both itaconate and the enzyme that synthesizes it, aconitate decarboxylase 1 (Acod1, also known as immune-responsive gene 1 [IRG1]), are upregulated during atherogenesis in mice. Deletion of Acod1 in myeloid cells exacerbated inflammation and atherosclerosis in vivo and resulted in an elevated frequency of a specific subset of M1-polarized proinflammatory macrophages in the atherosclerotic aorta. Importantly, Acod1 levels were inversely correlated with clinical occlusion in atherosclerotic human aorta specimens. Treating mice with the itaconate derivative 4-octyl itaconate attenuated inflammation and atherosclerosis induced by high cholesterol. Mechanistically, we found that the antioxidant transcription factor, nuclear factor erythroid 2-related factor 2 (Nrf2), was required for itaconate to suppress macrophage activation induced by oxidized lipids in vitro and to decrease atherosclerotic lesion areas in vivo. Overall, our work shows that itaconate suppresses atherogenesis by inducing Nrf2-dependent inhibition of proinflammatory responses in macrophages. Activation of the itaconate pathway may represent an important approach to treat atherosclerosis.

Cells in Atherosclerosis: Focus on Cellular Senescence from Basic Science to Clinical Practice

Aging is a major risk factor of atherosclerosis through different complex pathways including replicative cellular senescence and age-related clonal hematopoiesis. In addition to aging, extracellular stress factors, such as mechanical and oxidative stress, can induce cellular senescence, defined as premature cellular senescence. Senescent cells can accumulate within atherosclerotic plaques over time and contribute to plaque instability. This review summarizes the role of cellular senescence in the complex pathophysiology of atherosclerosis and highlights the most important senotherapeutics tested in cardiovascular studies targeting senescence. Continued bench-to-bedside research in cellular senescence might allow the future implementation of new effective anti-atherosclerotic preventive and treatment strategies in clinical practice.

Inhibitory effect and mechanism of Rosiglitazone on M1 type polarization of central microglia in intracerebral hemorrhage mice based on JNK/STAT3 signaling pathway

BACKGROUND

Intracerebral hemorrhage (ICH) seriously threatens the health of people. In addition, microglia M1 polarization was confirmed to be involved in the progression of ICH. Rosiglitazone was able to be used as an antidiabetic agent, which could activate PPAR-γ, and PPAR-γ was reported to inhibit inflammation in microglia. However, the detailed function of Rosiglitazone in ICH remains unclear.

METHODS

In vivo and in vitro experiments were used to test the function of Rosiglitazone in ICH. In addition, RT-qPCR and western blot were performed to evaluate the mRNA and protein level of PPAR-γ, respectively. Immunofluorescence staining was performed to detect the levels of CD206 and CD86, and ELISA was used to measure the levels of pro-inflammatory cytokines.

RESULTS

PPAR-γ was downregulated in ICH mice, whereas p-JNK and p-STAT3 were upregulated. Thrombin notably downregulated the level of PPAR-γ in BV2 cells, whereas Rosiglitazone partially reversed this phenomenon. In addition, Rosiglitazone markedly reversed thrombin-induced microglia M1 polarization. Consistently, thrombin-induced inflammatory response in BV2 cells was abolished in the presence of Rosiglitazone. SP600125 (JNK/STAT3 inhibitor) greatly reversed thrombin-induced M1 polarization in microglia, and GW9662 abolished the effect of SP600125. Meanwhile, Rosiglitazone could inactivate JNK/STAT3 pathway through the upregulation of PPAR-γ. Furthermore, Rosiglitazone notably alleviated the symptom of ICH in vivo through inhibiting the apoptosis and mediating PPAR-γ/JNK/STAT3 axis.

CONCLUSION

Rosiglitazone could attenuate the inflammation in ICH through inhibiting microglia M1 polarization. Thus, our research would shed now lights on exploring new therapeutic strategies against ICH.

TSPAN4 and migrasomes in atherosclerosis regression correlated to myocardial infarction and pan-cancer progression

The migrasomes formation is mediated by the assembly of micron-scale tetraspanin macrodomains and the recruitment of tetraspanin 4 (TSPAN4). However, the physiological functions of TSPAN4 on migrasomes are less known. The TSPAN4 expression in macrophages in single-cell sequencing data, GEO datasets and TCGA database were determined. TSPAN4 expression was highly associated with atherosclerosis regression-related macrophages, intraplaque hemorrhage and ruptured plaques. TSPAN4 expression was upregulated in spontaneous MI and inducible MI mice model. Besides, TSPAN4 expression was highly correlated with tumor-associated macrophages. The study provided a critical role of TSPAN4 aberrant expression in the progression of atherosclerosis and pan-cancer, and the intervention of TSPAN4 and migrasomes may save dying patients' lives and improve their prognosis.

Unveiling the Hidden Landscape of Arterial Diseases at Single-Cell Resolution

High-resolution single-cell technologies have shed light on the pathogenesis of cardiovascular diseases by enabling the discovery of novel cellular and transcriptomic signatures associated with various conditions, and uncovering new contributions of inflammatory processes, immunity, metabolic stress, and risk factors. We review the information obtained from studies using single-cell technologies in tissues with atherosclerosis and aortic aneurysms. Insights are provided on the biology of endothelial, smooth muscle, and immune cells in the arterial intima and media. In addition to cellular diversity, numerous examples of plasticity and phenotype switching are highlighted and presented in the context of normal cell functions.

Trem2 promotes foamy macrophage lipid uptake and survival in atherosclerosis

Atherosclerosis is driven by the expansion of cholesterol-loaded 'foamy' macrophages in the arterial intima. Factors regulating foamy macrophage differentiation and survival in plaque remain poorly understood. Here we show, using trajectory analysis of integrated single-cell RNA sequencing data and a genome-wide CRISPR screen, that triggering receptor expressed on myeloid cells 2 (Trem2) is associated with foamy macrophage specification. Loss of Trem2 led to a reduced ability of foamy macrophages to take up oxidized low-density lipoprotein (oxLDL). Myeloid-specific deletion of Trem2 showed an attenuation of plaque progression, even when targeted in established atherosclerotic lesions, and was independent of changes in circulating cytokines, monocyte recruitment or cholesterol levels. Mechanistically, we link Trem2-deficient macrophages with a failure to upregulate cholesterol efflux molecules, resulting in impaired proliferation and survival. Overall, we identify Trem2 as a regulator of foamy macrophage differentiation and atherosclerotic plaque growth and as a putative therapeutic target for atherosclerosis.

New Targets in Atherosclerosis: Vascular Smooth Muscle Cell Plasticity and Macrophage Polarity

PURPOSE

Despite an increase in treatment options, and substantial reductions in cardiovascular mortality over the past half-century, atherosclerosis remains the most prevalent cause of premature mortality worldwide. The development of innovative new therapies is crucial to further minimize atherosclerosis-related deaths. The diverse array of cell phenotypes derived from vascular smooth muscle cells (SMCs) and macrophages within atherosclerotic plaques are increasingly becoming recognized for their beneficial and detrimental roles in plaque stability and disease burden. This review explores how contemporary transcriptomics and fate-mapping studies have revealed vascular cell plasticity as a relatively unexplored target for therapeutic intervention.

METHODS

Recent literature for this narrative review was obtained by searching electronic databases (ie, Google Scholar, PubMed). Additional studies were sourced from reference lists and the authors' personal databases.

FINDINGS

The lipid-rich and inflammatory plaque milieu induces SMC phenotypic switching to both beneficial and detrimental phenotypes. Likewise, macrophage heterogeneity increases with disease burden to a variety of pro-inflammatory and anti-inflammatory activation states. These vascular cell phenotypes are determinants of plaque structure stability, and it is therefore highly likely that they influence clinical outcomes. Development of clinical treatments targeting deleterious phenotypes or promoting pro-healing phenotypes remains in its infancy. However, existing treatments (statins) have shown beneficial effects toward macrophage polarization, providing a rationale for more targeted approaches. In contrast, beneficial SMC phenotypic modulation with these pharmacologic agents has yet to be achieved. The range of modulated vascular cell phenotypes provides a multitude of novel targets and the potential to reduce future adverse events.

IMPLICATIONS

Vascular cell phenotypic heterogeneity must continue to be explored to lower cardiovascular events in the future. The rapidly increasing weight of evidence surrounding the role of SMC plasticity and macrophage polarity in plaque vulnerability provides a strong foundation upon which development of new therapeutics must follow. This approach may prove to be crucial in reducing cardiovascular events and improving patient benefit in the future.

Myeloid BAF60a deficiency alters metabolic homeostasis and exacerbates atherosclerosis

Atherosclerosis, a leading health concern, stems from the dynamic involvement of immune cells in vascular plaques. Despite its significance, the interplay between chromatin remodeling and transcriptional regulation in plaque macrophages is understudied. We discovered the reduced expression of Baf60a, a component of the switch/sucrose non-fermentable (SWI/SNF) chromatin remodeling complex, in macrophages from advanced plaques. Myeloid-specific Baf60a deletion compromised mitochondrial integrity and heightened adhesion, apoptosis, and plaque development. BAF60a preserves mitochondrial energy homeostasis under pro-atherogenic stimuli by retaining nuclear respiratory factor 1 (NRF1) accessibility at critical genes. Overexpression of BAF60a rescued mitochondrial dysfunction in an NRF1-dependent manner. This study illuminates the BAF60a-NRF1 axis as a mitochondrial function modulator in atherosclerosis, proposing the rejuvenation of perturbed chromatin remodeling machinery as a potential therapeutic target.

The Multifaceted Role of Osteopontin in Prostate Pathologies

The prostate gland, located beneath the bladder and surrounding the proximal urethra in men, plays a vital role in reproductive physiology and sexual health. Despite its importance, the prostate is vulnerable to various pathologies, including prostatitis, benign prostatic hyperplasia (BPH) and prostate cancer (PCa). Osteopontin (OPN), a versatile protein involved in wound healing, inflammatory responses, and fibrotic diseases, has been implicated in all three prostate conditions. The role of OPN in prostatic pathophysiology, affecting both benign and malignant prostate conditions, is significant. Current evidence strongly suggests that OPN is expressed at a higher level in prostate cancer and promotes tumor progression and aggressiveness. Conversely, OPN is primarily secreted by macrophages and foam cells in benign prostate conditions and provokes inflammation and fibrosis. This review discusses the accumulating evidence on the role of OPN in prostatic diseases, cellular sources, and potential roles while also highlighting areas for future investigations.

Monocytes reprogrammed by 4-PBA potently contribute to the resolution of inflammation and atherosclerosis

Background

Chronic inflammation initiated by inflammatory monocytes underlies the pathogenesis of atherosclerosis. However, approaches that can effectively resolve chronic low-grade inflammation targeting monocytes are not readily available. The small chemical compound 4-phenylbutyric acid (4-PBA) exhibits broad anti-inflammatory effects in reducing atherosclerosis. Selective delivery of 4-PBA reprogrammed monocytes may hold novel potential in providing targeted and precision therapeutics for the treatment of atherosclerosis.

Methods

Systems analyses integrating single-cell RNA-sequencing and complementary immunological approaches characterized key resolving characteristics as well as defining markers of reprogrammed monocytes trained by 4-PBA. Molecular mechanisms responsible for monocyte reprogramming was assessed by integrated biochemical and genetic approaches. The inter-cellular propagation of homeostasis resolution was evaluated by co-culture assays with donor monocytes trained by 4-PBA and recipient naïve monocytes. The in vivo effects of monocyte resolution and atherosclerosis prevention by 4-PBA were assessed with the high fat diet-fed ApoE -/- mouse model with i.p. 4-PBA administration. Furthermore, the selective efficacy of 4-PBA trained monocytes were examined by i.v. transfusion of ex vivo trained monocytes by 4-PBA into recipient high fat diet-fed ApoE -/- mice.

Results

In this study, we found that monocytes can be potently reprogrammed by 4-PBA into an immune-resolving state characterized by reduced adhesion and enhanced expression of anti-inflammatory mediator CD24. Mechanistically, 4-PBA reduced the expression of ICAM-1 via reducing peroxisome stress and attenuating SYK-mTOR signaling. Concurrently, 4-PBA enhanced the expression of resolving mediator CD24 through promoting PPARγ neddylation mediated by TOLLIP. 4-PBA trained monocytes can effectively propagate anti-inflammation activity to neighboring monocytes through CD24. Our data further demonstrated that 4-PBA trained monocytes effectively reduce atherosclerosis pathogenesis when administered in vivo .

Conclusion

Our study describes a robust and effective approach to generate resolving monocytes, characterizes novel mechanisms for targeted monocyte reprogramming, and offers a precision-therapeutics for atherosclerosis based on delivering reprogrammed resolving monocytes.

Macrophage polarization and metabolism in atherosclerosis

Atherosclerosis is a chronic inflammatory disease characterized by the accumulation of fatty deposits in the inner walls of vessels. These plaques restrict blood flow and lead to complications such as heart attack or stroke. The development of atherosclerosis is influenced by a variety of factors, including age, genetics, lifestyle, and underlying health conditions such as high blood pressure or diabetes. Atherosclerotic plaques in stable form are characterized by slow growth, which leads to luminal stenosis, with low embolic potential or in unstable form, which contributes to high risk for thrombotic and embolic complications with rapid clinical onset. In this complex scenario of atherosclerosis, macrophages participate in the whole process, including the initiation, growth and eventually rupture and wound healing stages of artery plaque formation. Macrophages in plaques exhibit high heterogeneity and plasticity, which affect the evolving plaque microenvironment, e.g., leading to excessive lipid accumulation, cytokine hyperactivation, hypoxia, apoptosis and necroptosis. The metabolic and functional transitions of plaque macrophages in response to plaque microenvironmental factors not only influence ongoing and imminent inflammatory responses within the lesions but also directly dictate atherosclerotic progression or regression. In this review, we discuss the origin of macrophages within plaques, their phenotypic diversity, metabolic shifts, and fate and the roles they play in the dynamic progression of atherosclerosis. It also describes how macrophages interact with other plaque cells, particularly T cells. Ultimately, targeting pathways involved in macrophage polarization may lead to innovative and promising approaches for precision medicine. Further insights into the landscape and biological features of macrophages within atherosclerotic plaques may offer valuable information for optimizing future clinical treatment for atherosclerosis by targeting macrophages.

Migrasome: a new functional extracellular vesicle

Migrasome is a novel cellular organelle produced during cell migration, and its biogenesis depends on the migration process. It is generated in a variety of cells such as immune cells, metastatic tumor cells, other special functional cells like podocytes and cells in developing organisms. It plays important roles in various fields especially in the information exchange between cells. The discovery of migrasome, as an important supplement to the extracellular vesicle system, provides new mechanisms and targets for comprehending various biological or pathological processes. In this article, we will review the discovery, structure, distribution, detection, biogenesis, and removal of migrasomes and mainly focus on summarizing its biological functions in cell-to-cell communication, homeostatic maintenance, embryonic development and multiple diseases. This review also creates prospects for the possible research directions and clinical applications of migrasomes in the future.

Innate Immune Pathways in Atherosclerosis-From Signaling to Long-Term Epigenetic Reprogramming

Innate immune pathways play a crucial role in the development of atherosclerosis, from sensing initial danger signals to the long-term reprogramming of immune cells. Despite the success of lipid-lowering therapy, anti-hypertensive medications, and other measures in reducing complications associated with atherosclerosis, cardiovascular disease (CVD) remains the leading cause of death worldwide. Consequently, there is an urgent need to devise novel preventive and therapeutic strategies to alleviate the global burden of CVD. Extensive experimental research and epidemiological studies have demonstrated the dominant role of innate immune mechanisms in the progression of atherosclerosis. Recently, landmark trials including CANTOS, COLCOT, and LoDoCo2 have provided solid evidence demonstrating that targeting innate immune pathways can effectively reduce the risk of CVD. These groundbreaking trials mark a significant paradigm shift in the field and open new avenues for atheroprotective treatments. It is therefore crucial to comprehend the intricate interplay between innate immune pathways and atherosclerosis for the development of targeted therapeutic interventions. Additionally, unraveling the mechanisms underlying long-term reprogramming may offer novel strategies to reverse the pro-inflammatory phenotype of immune cells and restore immune homeostasis in atherosclerosis. In this review, we present an overview of the innate immune pathways implicated in atherosclerosis, with a specific focus on the signaling pathways driving chronic inflammation in atherosclerosis and the long-term reprogramming of immune cells within atherosclerotic plaque. Elucidating the molecular mechanisms governing these processes presents exciting opportunities for the development of a new class of immunotherapeutic approaches aimed at reducing inflammation and promoting plaque stability. By addressing these aspects, we can potentially revolutionize the management of atherosclerosis and its associated cardiovascular complications.

Single-Cell Analysis of CX3CR1+ Cells Reveals a Pathogenic Role for BIRC5+ Myeloid Proliferating Cells Driven by Staphylococcus aureus Leukotoxins

Our previous studies identified a population of stem cell-like proliferating myeloid cells within inflamed tissues that could serve as a reservoir for tissue macrophages to adopt different activation states depending on the microenvironment. By lineage-tracing cells derived from CX3CR1+ precursors in mice during infection and profiling by single-cell RNA sequencing, in this study, we identify a cluster of BIRC5+ myeloid cells that expanded in the liver during chronic infection with either the parasite Schistosoma mansoni or the bacterial pathogen Staphylococcus aureus. In the absence of tissue-damaging toxins, S. aureus infection does not elicit these BIRC5+ cells. Moreover, deletion of BIRC5 from CX3CR1-expressing cells results in improved survival during S. aureus infection. Hence the combination of single-cell RNA sequencing and genetic fate-mapping CX3CR1+ cells revealed a toxin-dependent pathogenic role for BIRC5 in myeloid cells during S. aureus infection.

Genetic inhibition of CARD9 accelerates the development of atherosclerosis in mice through CD36 dependent-defective autophagy

Caspase recruitment-domain containing protein 9 (CARD9) is a key signaling pathway in macrophages but its role in atherosclerosis is still poorly understood. Global deletion of Card9 in Apoe-/- mice as well as hematopoietic deletion in Ldlr-/- mice increases atherosclerosis. The acceleration of atherosclerosis is also observed in Apoe-/-Rag2-/-Card9-/- mice, ruling out a role for the adaptive immune system in the vascular phenotype of Card9 deficient mice. Card9 deficiency alters macrophage phenotype through CD36 overexpression with increased IL-1β production, increased lipid uptake, higher cell death susceptibility and defective autophagy. Rapamycin or metformin, two autophagy inducers, abolish intracellular lipid overload, restore macrophage survival and autophagy flux in vitro and finally abolish the pro-atherogenic effects of Card9 deficiency in vivo. Transcriptomic analysis of human CARD9-deficient monocytes confirms the pathogenic signature identified in murine models. In summary, CARD9 is a key protective pathway in atherosclerosis, modulating macrophage CD36-dependent inflammatory responses, lipid uptake and autophagy.

High-Dimensional Single-Cell Multimodal Landscape of Human Carotid Atherosclerosis

Background

Atherosclerotic plaques are complex tissues composed of a heterogeneous mixture of cells. However, we have limited understanding of the comprehensive transcriptional and phenotypical landscape of the cells within these lesions.

Methods

To characterize the landscape of human carotid atherosclerosis in greater detail, we combined cellular indexing of transcriptomes and epitopes by sequencing (CITE-seq) and single-cell RNA sequencing (scRNA-seq) to classify all cell types within lesions (n=21; 13 symptomatic) to achieve a comprehensive multimodal understanding of the cellular identities of atherosclerosis and their association with clinical pathophysiology.

Results

We identified 25 distinct cell populations each having a unique multi-omic signature, including macrophages, T cells, NK cells, mast cells, B cells, plasma cells, neutrophils, dendritic cells, endothelial cells, fibroblasts, and smooth muscle cells (SMCs). Within the macrophage populations, we identified 2 proinflammatory subsets that were enriched in IL1B or C1Q expression, 2 distinct TREM2 positive foam cell subsets, one of which also expressed inflammatory genes, as well as subpopulations displaying a proliferative gene expression signature and one expressing SMC-specific genes and upregulation of fibrotic pathways. An in-depth characterization uncovered several subsets of SMCs and fibroblasts, including a SMC-derived foam cell. We localized this foamy SMC to the deep intima of coronary atherosclerotic lesions. Using CITE-seq data, we also developed the first flow cytometry panel, using cell surface proteins CD29, CD142, and CD90, to isolate SMC-derived cells from lesions. Last, we found that the proportion of efferocytotic macrophages, classically activated endothelial cells, contractile and modulated SMC-derived cell types were reduced, and inflammatory SMCs were enriched in plaques of clinically symptomatic vs. asymptomatic patients.

Conclusions

Our multimodal atlas of cell populations within atherosclerosis provides novel insights into the diversity, phenotype, location, isolation, and clinical relevance of the unique cellular composition of human carotid atherosclerosis. This facilitates both the mapping of cardiovascular disease susceptibility loci to specific cell types as well as the identification of novel molecular and cellular therapeutic targets for treatment of the disease.

Single-cell and spatial transcriptomics identify a macrophage population associated with skeletal muscle fibrosis

Macrophages are essential for skeletal muscle homeostasis, but how their dysregulation contributes to the development of fibrosis in muscle disease remains unclear. Here, we used single-cell transcriptomics to determine the molecular attributes of dystrophic and healthy muscle macrophages. We identified six clusters and unexpectedly found that none corresponded to traditional definitions of M1 or M2 macrophages. Rather, the predominant macrophage signature in dystrophic muscle was characterized by high expression of fibrotic factors, galectin-3 (gal-3) and osteopontin (Spp1). Spatial transcriptomics, computational inferences of intercellular communication, and in vitro assays indicated that macrophage-derived Spp1 regulates stromal progenitor differentiation. Gal-3+ macrophages were chronically activated in dystrophic muscle, and adoptive transfer assays showed that the gal-3+ phenotype was the dominant molecular program induced within the dystrophic milieu. Gal-3+ macrophages were also elevated in multiple human myopathies. These studies advance our understanding of macrophages in muscular dystrophy by defining their transcriptional programs and reveal Spp1 as a major regulator of macrophage and stromal progenitor interactions.

Integrated single-cell analysis-based classification of vascular mononuclear phagocytes in mouse and human atherosclerosis

AIMS

Accumulation of mononuclear phagocytes [monocytes, macrophages, and dendritic cells (DCs)] in the vessel wall is a hallmark of atherosclerosis. Using integrated single-cell analysis of mouse and human atherosclerosis, we here aimed to refine the nomenclature of mononuclear phagocytes in atherosclerotic vessels and to compare their transcriptomic profiles in mouse and human disease.

METHODS AND RESULTS

We integrated 12 single-cell RNA-sequencing (scRNA-seq) datasets of immune cells isolated from healthy or atherosclerotic mouse aortas, and data from 11 patients (n = 4 coronary vessels, n = 7 carotid endarterectomy specimens) from two studies. Integration of mouse data identified subpopulations with discrete transcriptomic signatures within previously described populations of aortic resident (Lyve1), inflammatory (Il1b), as well as foamy (Trem2hi) macrophages. We identified unique transcriptomic features distinguishing aortic intimal resident macrophages from atherosclerosis-associated Trem2hi macrophages. Also, populations of Xcr1+ Type 1 classical DCs (cDC1), Cd209a+ cDC2, and mature DCs (Ccr7, Fscn1) with a 'mreg-DC' signature were detected. In humans, we uncovered macrophage and DC populations with gene expression patterns similar to those observed in mice. In particular, core transcripts of the foamy/Trem2hi signature (TREM2, SPP1, GPNMB, CD9) mapped to a specific population of macrophages in human lesions. Comparison of mouse and human data and direct cross-species data integration suggested transcriptionally similar macrophage and DC populations in mice and humans.

CONCLUSIONS

We refined the nomenclature of mononuclear phagocytes in mouse atherosclerotic vessels, and show conserved transcriptomic features of macrophages and DCs in atherosclerosis in mice and humans, emphasizing the relevance of mouse models to study mononuclear phagocytes in atherosclerosis.

New discoveries in the field of metabolism by applying single-cell and spatial omics

Single-cell multi-Omics (SCM-Omics) and spatial multi-Omics (SM-Omics) technologies provide state-of-the-art methods for exploring the composition and function of cell types in tissues/organs. Since its emergence in 2009, single-cell RNA sequencing (scRNA-seq) has yielded many groundbreaking new discoveries. The combination of this method with the emergence and development of SM-Omics techniques has been a pioneering strategy in neuroscience, developmental biology, and cancer research, especially for assessing tumor heterogeneity and T-cell infiltration. In recent years, the application of these methods in the study of metabolic diseases has also increased. The emerging SCM-Omics and SM-Omics approaches allow the molecular and spatial analysis of cells to explore regulatory states and determine cell fate, and thus provide promising tools for unraveling heterogeneous metabolic processes and making them amenable to intervention. Here, we review the evolution of SCM-Omics and SM-Omics technologies, and describe the progress in the application of SCM-Omics and SM-Omics in metabolism-related diseases, including obesity, diabetes, nonalcoholic fatty liver disease (NAFLD) and cardiovascular disease (CVD). We also conclude that the application of SCM-Omics and SM-Omics approaches can help resolve the molecular mechanisms underlying the pathogenesis of metabolic diseases in the body and facilitate therapeutic measures for metabolism-related diseases. This review concludes with an overview of the current status of this emerging field and the outlook for its future.

Lipid-associated macrophages transition to an inflammatory state in human atherosclerosis increasing the risk of cerebrovascular complications

The immune system is integral to cardiovascular health and disease. Targeting inflammation ameliorates adverse cardiovascular outcomes. Atherosclerosis, a major underlying cause of cardiovascular disease (CVD), is conceptualised as a lipid-driven inflammation where macrophages play a non-redundant role. However, evidence emerging so far from single cell atlases suggests a dichotomy between lipid associated and inflammatory macrophage states. Here, we present an inclusive reference atlas of human intraplaque immune cell communities. Combining scRNASeq of human surgical carotid endarterectomies in a discovery cohort with bulk RNASeq and immunohistochemistry in a validation cohort (the Carotid Plaque Imaging Project-CPIP), we reveal the existence of PLIN2hi/TREM1hi macrophages as a toll-like receptor-dependent inflammatory lipid-associated macrophage state linked to cerebrovascular events. Our study shifts the current paradigm of lipid-driven inflammation by providing biological evidence for a pathogenic macrophage transition to an inflammatory lipid-associated phenotype and for its targeting as a new treatment strategy for CVD.

Functionally and Metabolically Divergent Melanoma-Associated Macrophages Originate from Common Bone-Marrow Precursors

Tumor-associated macrophages (TAMs) can be widely heterogeneous, based on their ontogeny and function, and driven by the tissue-specific niche. TAMs are highly abundant in the melanoma tumor microenvironment (TME), usually correlating with worse prognoses. However, the understanding of their diversity may be harnessed for therapeutic purposes. Here, we used the clinically relevant YUMM1.7 model to study melanoma TAM origin and dynamics during tumor progression. In i.d. YUMM1.7 tumors, we identified distinct TAM subsets based on F4/80 expression, with the F4/80^high fraction increasing over time and displaying a tissue-resident-like phenotype. While skin-resident macrophages showed mixed ontogeny, F4/80⁺ TAM subsets in the melanoma TME originated almost exclusively from bone-marrow precursors. A multiparametric analysis of the macrophage phenotype showed a temporal divergence of the F4/80⁺ TAM subpopulations, which also differed from the skin-resident subsets and their monocytic precursors. Overall, the F4/80⁺ TAMs displayed co-expressions of M1- and M2-like canonical markers, while RNA sequencing showed differential immunosuppressive and metabolic profiles. Gene-set enrichment analysis (GSEA) revealed F4/80^high TAMs to rely on oxidative phosphorylation, with increased proliferation and protein secretion, while F4/80^low cells had high pro-inflammatory and intracellular signaling pathways, with lipid and polyamine metabolism. Overall, we provide an in-depth characterization of and compelling evidence for the BM-dependency of melanoma TAMs. Interestingly, the transcriptomic analysis of these BM-derived TAMs matched macrophage subsets with mixed ontogeny, which have been observed in other tumor models. Our findings may serve as a guide for identifying potential ways of targeting specific immunosuppressive TAMs in melanoma.