Single-cell RNA sequencing reveals B cell-T cell interactions in vascular adventitia of hyperhomocysteinemia-accelerated atherosclerosis

Role of hyperhomocysteinemia in atherosclerosis: from bench to bedside

BACKGROUND

Atherosclerosis is a leading cause of global mortality, driven by complex interactions between genetic, metabolic, and environmental factors. Among these, hyperhomocysteinemia (HHcy) has emerged as a significant and modifiable risk factor, contributing to endothelial dysfunction, oxidative stress, and vascular inflammation. Despite increasing recognition of its role in atherogenesis, the precise mechanisms and clinical implications of HHcy remain incompletely understood, necessitating a comprehensive review to connect recent mechanistic insights with practical applications.

METHODS

We analyzed the various mechanisms whereby HHcy accelerates the progression of atherosclerosis, and conducted a comprehensive review of publications in the fields of HHcy and atherosclerosis.

RESULTS

HHcy promotes atherosclerosis through several mechanisms, including inflammation, oxidative stress, epigenetic modification, and lipoprotein metabolism alteration. Moreover, this discussion extends to current strategies for the prevention and clinical management of HHcy-induced atherosclerosis.

CONCLUSION

This review consolidates and elucidates the latest advancements and insights into the role of HHcy in atherosclerosis. The comprehensive narrative connects fundamental research with clinical applications. Contemporary studies highlight the complex interplay between HHcy and atherosclerosis, establishing HHcy as not only a contributing risk factor but also an accelerator of various atherogenic processes.

Single-cell RNA sequencing (scRNA-seq) and its insights into cellular heterogeneity in atherosclerosis

Single-cell RNA sequencing (scRNA-seq) has transformed our understanding of cellular diversity in human biology, providing novel insights into disease mechanisms. In cardiovascular disease (CVD), scRNA-seq enables precise mapping of complex cell populations, uncovering unique cell types and states that influence disease progression and suggest new therapeutic targets. In atherosclerosis (AS), scRNA-seq has redefined plaque pathology by identifying distinct cell types, including endothelial cells (ECs), smooth muscle cells (SMCs), fibroblasts, macrophages, T cells, and B cells, each with specific roles in plaque stability, inflammation, and disease progression. In our review, we summarized these major cellular populations and their cellular heterogeneity in non-diseased and atherosclerotic aorta, as identified by scRNA-seq in mice and human tissues. We discussed conserved and species-specific subpopulations, their defining markers, and their functional implications in plaque progression. In addition, we integrated findings from scRNA-seq with experimental studies to highlight key molecular targets with therapeutic potential. In the future, these insights offer a refined cellular and molecular framework of atherosclerosis and may help the development of targeted interventions to promote plaque stabilization and reduce cardiovascular risk.

Increased burden of enlarged perivascular spaces in patients with patent foramen ovale

INTRODUCTION

Patent foramen ovale (PFO) patients may experience states of hypoxia and hypoperfusion, which may increase the burden of enlarged perivascular spaces (EPVS). However, to our knowledge, no data are available regarding EPVS in PFO patients. This study sought to investigate if patients with PFO exhibit a heightened burden of EPVS and to identify the mediating factors between PFO and EPVS.

METHODS

A total of 108 consecutive PFO patients (PFO group) and 110 healthy controls (HC group) from January 2022 to February 2024 were enrolled. The differences in centrum semiovale EPVS (CSO-EPVS) and basal ganglia EPVS (BG-EPVS) scores between PFO and HC groups were compared. The correlations among PFO diameters, laboratory indexes, and EPVS burdens were analyzed. The relationships among them were obtained using mediation analysis.

RESULTS

Mean age of PFO and HC group was 47.68 ± 14.47 and 48.14 ± 12.84 years. The CSO-EPVS and BG-EPVS scores were higher in PFO group than HC group (P < 0.001). The CSO-EPVS and BG-EPVS scores for PFO group were concentrated in the ranges 1-3 and 1-2 points, while for HC group were concentrated in the range 0-1 points. A positive correlation among PFO diameters and CSO-EPVS score (r = 0.62, P < 0.001), BG-EPVS score (r = 0.63, P < 0.001), and homocysteine (HCY)(r = 0.21, P = 0.03) was observed. Mediation analysis indicated that higher HCY significantly mediated the relationship between PFO diameter and BG-EPVS burden in PFO patients (P < 0.05).

CONCLUSION

These findings revealed the presence of glymphatic dysfunction in patients with PFO. HCY may mediate the impact of PFO diameter on glymphatic function.

Analysis of regulatory patterns of NLRP3 corpuscles and related genes and the role of macrophage polarization in atherosclerosis based on online database

Our study examined the relationships and interactions among 30 genes related to the NOD-like receptor protein 3 (NLRP3) inflammasome. We identified 368 interconnections between these 30 genes, with NLRP3 participating in 38 interactions. The potential roles of these genes in atherosclerosis were evaluated based on protein-protein interaction networks and coexpression analysis. We identified differential expression in 20 genes, five of which were significantly upregulated: P2RX7, CASP1, CD36, GBP5, and PYCARD. We also observed a strong positive association between P2RX7 and PYCARD and as a notable negative association between RELA and CD36. Furthermore, our analysis revealed a clear association between the expression of inflammasome-associated genes and immune cell infiltration in disease specimens. To diagnose AS, a logistic regression model based on six inflammasome-related genes, achieved an Area under the curve of 0.996, indicating excellent diagnostic performance. Genomic enrichment analysis indicated that inflammasome-related genes were primarily involved in various pathways, such as hypertrophic cardiomyopathy and ribosomal function. To validate our findings, we confirmed the expression of risk genes in AS cells using qRT-PCR and Western blot techniques. Additionally, we observed a shift toward M2 polarization in THP-1 macrophages upon P2RX7 knockdown, further supporting our findings.

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.

Single-cell transcriptome analysis reveals tumoral microenvironment heterogenicity and hypervascularization in human carotid body tumor

Carotid body tumor (CBT) is a rare neck tumor located at the adventitia of the common carotid artery bifurcation. The prominent pathological features of CBT are high vascularization and abnormal proliferation. However, single-cell transcriptome analysis of the microenvironment composition and molecular complexity in CBT has yet to be performed. In this study, we performed single-cell RNA sequencing (scRNA-seq) analysis on human CBT to define the cells that contribute to hypervascularization and chronic hyperplasia. Unbiased clustering analysis of transcriptional profiles identified 16 distinct cell populations including endothelial cells (ECs), smooth muscle cells (SMCs), neuron cells, macrophage cells, neutrophil cells, and T cells. Within the ECs population, we defined subsets with angiogenic capacity plus clear signs of later endothelial progenitor cells (EPCs) to normal ECs. Two populations of macrophages were detectable in CBT, macrophage1 showed enrichment in hypoxia-inducible factor-1 (HIF-1) and as well as an early EPCs cell-like population expressing CD14 and vascular endothelial growth factor. In addition to HIF-1-related transcriptional protein expression, macrophages1 also display a neovasculogenesis-promoting phenotype. SMCs included three populations showing platelet-derived growth factor receptor beta and vimentin expression, indicative of a cancer-associated fibroblast phenotype. Finally, we identified three types of neuronal cells, including chief cells and sustentacular cells, and elucidated their distinct roles in the pathogenesis of CBT and abnormal proliferation of tumors. Overall, our study provided the first comprehensive characterization of the transcriptional landscape of CBT at scRNA-seq profiles, providing novel insights into the mechanisms underlying its formation.

Exploring Immune Cell Diversity in the Lacrimal Glands of Healthy Mice: A Single-Cell RNA-Sequencing Atlas

The lacrimal gland is responsible for maintaining the health of the ocular surface through the production of tears. However, our understanding of the immune system within the lacrimal gland is currently limited. Therefore, in this study, we utilized single-cell RNA sequencing and bioinformatic analysis to identify and analyze immune cells and molecules present in the lacrimal glands of normal mice. A total of 34,891 cells were obtained from the lacrimal glands of mice and classified into 18 distinct cell clusters using Seurat clustering. Within these cell populations, 26 different immune cell subpopulations were identified, including T cells, innate lymphocytes, macrophages, mast cells, dendritic cells, and B cells. Network analysis revealed complex cell-cell interactions between these immune cells, with particularly significant interactions observed among T cells, macrophages, plasma cells, and dendritic cells. Interestingly, T cells were found to be the main source of ligands for the Thy1 signaling pathway, while M2 macrophages were identified as the primary target of this pathway. Moreover, some of these immune cells were validated using immunohistological techniques. Collectively, these findings highlight the abundance and interactions of immune cells and provide valuable insights into the complexity of the lacrimal gland immune system and its relevance to associated diseases.

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.

Meta-Analysis of Single-Cell RNA-Seq Data Reveals the Mechanism of Formation and Heterogeneity of Tertiary Lymphoid Organ in Vascular Disease

BACKGROUND

Tertiary lymphoid organs (TLOs) are ectopic lymphoid organs developed in nonlymphoid tissues with chronic inflammation, but little is known about their existence in different types of vascular diseases and the mechanism that mediated their development.

METHODS

To take advantage of single-cell RNA sequencing techniques, we integrated 28 single-cell RNA sequencing data sets containing 5 vascular disease models (atherosclerosis, abdominal aortic aneurysm, intimal hyperplasia, isograft, and allograft) to explore TLOs existence and environment supporting its growth systematically. We also searched Medline, Embase, PubMed, and Web of Science from inception to January 2022 for published histological images of vascular remodeling for histological evidence to support TLO genesis.

RESULTS

Accumulation and infiltration of innate and adaptive immune cells have been observed in various remodeling vessels. Interestingly, the proportion of such immune cells incrementally increases from atherosclerosis to intimal hyperplasia, abdominal aortic aneurysm, isograft, and allograft. Importantly, we uncovered that TLO structure cells, such as follicular helper T cells and germinal center B cells, present in all remodeled vessels. Among myeloid cells and lymphocytes, inflammatory macrophages, and T helper 17 cells are the major lymphoid tissue inducer cells which were found to be positively associated with the numbers of TLO structural cells in remodeled vessels. Vascular stromal cells also actively participate in vascular TLO genesis by communicating with myeloid cells and lymphocytes via CCLs (C-C motif chemokine ligands), CXCL (C-X-C motif ligand), lymphotoxin, BMP (bone morphogenetic protein) chemotactic, FGF-2 (fibroblast growth factor-2), and IGF (insulin growth factor) proliferation mechanisms, particularly for lymphoid tissue inducer cell aggregation. Additionally, the interaction between stromal cells and immune cells modulates extracellular matrix remodeling. Among TLO structure cells, follicular helper T, and germinal center B cells have strong interactions via TCR (T-cell receptor), CD40 (cluster of differentiation 40), and CXCL signaling, to promote the development and maturation of the germinal center in TLO. Consistently, by reviewing the histological images from the literature, TLO genesis was found in those vascular remodeling models.

CONCLUSIONS

Our analysis showed the existence of TLOs across 5 models of vascular diseases. The mechanisms that support TLOs formation in different models are heterogeneous. This study could be a valuable resource for understanding and discovering new therapeutic targets for various forms of vascular disease.

Identification of immune infiltration-related biomarkers in carotid atherosclerotic plaques

Atherosclerosis is a chronic lipid-driven inflammatory response of the innate and adaptive immune systems, and it is responsible for several cardiovascular ischemic events. The present study aimed to determine immune infiltration-related biomarkers in carotid atherosclerotic plaques (CAPs). Gene expression profiles of CAPs were extracted from the Gene Expression Omnibus database. Differentially expressed genes (DEGs) between the CAPs and control groups were screened by the "limma" package in R software. Immune cell infiltration between the CAPs and control groups was evaluated by the single sample gene set enrichment analysis. Key infiltrating immune cells in the CAPs group were screened by the Wilcoxon test and least absolute shrinkage and selection operator regression. The weighted gene co-expression network analysis was used to identify immune cell-related genes. Hub genes were identified by the protein-protein interaction (PPI) network. Receiver operating characteristic curve analysis was performed to assess the gene's ability to differentiate between the CAPs and control groups. Finally, we constructed a miRNA-gene-transcription factor network of hub genes by using the ENCODE database. Eleven different types of immune infiltration-related cells were identified between the CAPs and control groups. A total of 1,586 differentially expressed immunity-related genes were obtained through intersection between DEGs and immune-related genes. Twenty hub genes were screened through the PPI network. Eventually, 7 genes (BTK, LYN, PTPN11, CD163, CD4, ITGAL, and ITGB7) were identified as the hub genes of CAPs, and these genes may serve as the estimable drug targets for patients with CAPs.

Diversity of arterial cell and phenotypic heterogeneity induced by high-fat and high-cholesterol diet

Lipid metabolism disorder is the basis of atherosclerotic lesions, in which cholesterol and low-density lipoprotein (LDL) is the main factor involved with the atherosclerotic development. A high-fat and high-cholesterol diet can lead to this disorder in the human body, thus accelerating the process of disease. The development of single-cell RNA sequencing in recent years has opened the possibility to unbiasedly map cellular heterogeneity with high throughput and high resolution; alterations mediated by a high-fat and high-cholesterol diet at the single-cell transcriptomic level can be explored with this mean afterward. We assessed the aortic arch of 16-week old Apoe-/- mice of two control groups (12 weeks of chow diet) and two HFD groups (12 weeks of high fat, high cholesterol diet) to process single-cell suspension and use single-cell RNA sequencing to anatomize the transcripts of 5,416 cells from the control group and 2,739 from the HFD group. Through unsupervised clustering, 14 cell types were divided and defined. Among these cells, the cellular heterogeneity exhibited in endothelial cells and immune cells is the most prominent. Subsequent screening delineated ten endothelial cell subsets with various function based on gene expression profiling. The distribution of endothelial cells and immune cells differs significantly between the control group versus the HFD one. The existence of pathways that inhibit atherosclerosis was found in both dysfunctional endothelial cells and foam cells. Our data provide a comprehensive transcriptional landscape of aortic arch cells and unravel the cellular heterogeneity brought by a high-fat and high-cholesterol diet. All these findings open new perspectives at the transcriptomic level to studying the pathology of atherosclerosis.

Single-cell atlas reveals different immune environments between stable and vulnerable atherosclerotic plaques

Introduction

Regardless of the degree of stenosis, vulnerable plaque is an important cause of ischemic stroke and thrombotic complications. The changes of the immune microenvironment within plaques seem to be an important factor affecting the characteristics of the plaque. However, the differences of immune microenvironment between stable and vulnerable plaques were remained unknown.

Methods

In this study, RNA-sequencing was performed on superficial temporal arteries from 5 traumatic patients and plaques from 3 atherosclerotic patients to preliminary identify the key immune response processes in plaques. Mass cytometry (CyTOF) technology was used to explore differences in immune composition between 9 vulnerable plaques and 12 stable plaques. Finally, immunofluorescence technique was used to validate our findings in the previous analysis.

Results

Our results showed that more CD86+CD68+ M1 pro-inflammatory macrophages were found in vulnerable plaques, while CD4+T memory cells were mainly found in stable plaques. In addition, a CD11c+ subset of CD4+T cells with higher IFN-r secretion was found within the vulnerable plaque. In two subsets of B cells, CD19+CD20-B cells in vulnerable plaques secreted more TNF-a and IL-6, while CD19-CD20+B cells expressed more PD-1 molecules.

Conclusion

In conclusion, our study suggested that M1-like macrophages are the major cell subset affecting plaque stability, while functional B cells may also contribute to plaque stability.

Novel immune cell infiltration-related biomarkers in atherosclerosis diagnosis

Background

Immune cell infiltration (ICI) has a close relationship with the progression of atherosclerosis (AS). Therefore, the current study was aimed to explore the role of genes related to ICI and to investigate potential mechanisms in AS.

Methods

Single-sample gene set enrichment analysis (ssGSEA) was applied to explore immune infiltration in AS and controls. Genes related to immune infitration were mined by weighted gene co-expression network analysis (WGCNA). The function of those genes were analyzed by enrichment analyses of the Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology (GO). The interactions among those genes were visualized in the protein-protein interaction (PPI) network, followed by identification of hub genes through Cytoscape software. A receiver operating characteristic (ROC) plot was generated to assess the performance of hub genes in AS diagnosis. The expressions of hub genes were measured by reverse transcription quantitative real-time PCR (RT-qPCR) in human leukemia monocyticcell line (THP-1) derived foam cells and macrophages, which mimic AS and control, respectively.

Results

We observed that the proportions of 27 immune cells were significantly elevated in AS. Subsequent integrative analyses of differential expression and WGCNA identified 99 immune cell-related differentially expressed genes (DEGs) between AS and control. Those DEGs were associated with tryptophan metabolism and extracellular matrix (ECM)-related functions. Moreover, by constructing the PPI network, we found 11 hub immune cell-related genes in AS. The expression pattern and receiver ROC analyses in two independent datasets showed that calsequestrin 2 (CASQ2), nexilin F-Actin binding protein (NEXN), matrix metallopeptidase 12 (MMP12), C-X-C motif chemokine ligand 10 (CXCL10), phospholamban (PLN), heme oxygenase 1 (HMOX1), ryanodine receptor 2 (RYR2), chitinase 3 like 1 (CHI3L1), matrix metallopeptidase 9 (MMP9), actin alpha cardiac muscle 1 (ACTC1) had good performance in distinguishing AS from control samples. Furthermore, those biomarkers were shown to be correlated with angiogenesis and immune checkpoints. In addition, we found 239 miRNAs and 47 transcription factor s (TFs), which may target those biomarkers and regulate their expressions. Finally, we found that RT-qPCR results were consistent with sequencing results.

The emerging role of pyroptosis-related inflammasome pathway in atherosclerosis

Atherosclerosis (AS), a chronic sterile inflammatory disorder, is one of the leading causes of mortality worldwide. The dysfunction and unnatural death of plaque cells, including vascular endothelial cells (VEC), macrophages, and vascular smooth muscle cells (VSMC), are crucial factors in the progression of AS. Pyroptosis was described as a form of cell death at least two decades ago. It is featured by plasma membrane swelling and rupture, cell lysis, and consequent robust release of cytosolic contents and pro-inflammatory mediators, including interleukin-1β (IL-1β), IL-18, and high mobility group box 1 (HMGB1). Pyroptosis of plaque cells is commonly observed in the initiation and development of AS, and the levels of pyroptosis-related proteins are positively correlated with plaque instability, indicating the crucial contribution of pyroptosis to atherogenesis. Furthermore, studies have also identified some candidate anti-atherogenic agents targeting plaque cell pyroptosis. Herein, we summarize the research progress in understating (1) the discovery and definition of pyroptosis; (2) the characterization and molecular mechanisms of pyroptosis; (3) the regulatory mechanisms of pyroptosis in VEC, macrophage, and VSMC, as well as their potential role in AS progression, aimed at providing therapeutic targets for the prevention and treatment of AS.