Macrophage phenotypes in atherosclerosis

Anti-Oxidative, Anti-Apoptotic, and M2 Polarized DSPC Liposome Nanoparticles for Selective Treatment of Atherosclerosis

Purpose

Oxidative stress is one of the main pathogenic factors of atherosclerosis. However, no antioxidants have brought positive effects on the treatment of atherosclerosis. To selectively treat atherosclerosis, various means such as antioxidation, anti-apoptosis, and M2 polarization are used. The ultimate goal is that multiple regulatory pathways can help to treat atherosclerosis.

Patients and Methods

In this study, Simvastatin (SIM) as a model drug, EGCG as an antioxidant agent, and distearyl phosphatidylcholine (DSPC) as major carriers were used to make liposome nanoparticles (SE-LNPs). The cytotoxicity, phagocytosis, antioxidant, and anti-apoptotic properties of nanoparticles were tested in vitro. ApoE-/- atherosclerotic mice were treated with nanoparticles. The changes of aortic Oil red staining, blood lipid, HE, and Masson sections of the aortic root were observed.

Results

SE-LNPs exhibited a sustained release profile, potentially enabling the accumulation of the majority amount of drugs at the atherosclerotic plaque. The phagocytosis effect was stronger in RAW. The anti-oxidative and anti-apoptotic effects of the formulation were verified in vitro. SE-LNPs promoted the polarization of M2 macrophages. The therapeutic effect of SE-LNPs was assessed in the ApoE-/- mice model of atherosclerosis. SE-LNPs reduced reactive oxygen species and lipids in vivo. The results of Oil red staining, blood lipid, HE, and Masson sections of the aortic root showed the recovery of the focus.

Conclusion

Studies have shown that SE-LNPs could resist oxidation, and apoptosis, promote M2 polarization, and reduce blood lipids and lesions, which is a reliable and selective treatment for atherosclerosis.

A metal-organic framework-based immunomodulatory nanoplatform for anti-atherosclerosis treatment

Immunomodulatory therapy has become a promising method for the clinical treatment of many diseases. Recently, pilot studies revealed that immunomodulatory therapy exhibited good effects on the treatment of cardiovascular diseases, but many problems remain to be solved, such as useful platforms for drug co-delivery and combination therapies. In this study, we designed and constructed the multifunctional nanoparticle Rapa@UiO-66-NH-FAM-IL-1Ra (RUFI) for the treatment of atherosclerotic cardiovascular disease. This nanoplatform combined the advantages of metal-organic frameworks (MOFs) for drug co-delivery, rapamycin and IL-1Ra for immunomodulation, IL-1Ra for cellular targeting, and 5-FAM for fluorescence imaging. RUFI exhibited good drug release of rapamycin and IL-1Ra and specific cytotoxicity for inflammatory macrophages in vitro. In an atherosclerotic model of diet-fed ApoE^-/- mice, RUFI significantly targeted and reduced atherosclerosis plaques in coronary arteries, carotid arteries, and aortas. Mechanistic studies indicated that RUFI modulated macrophage phenotype, cytokine expression, and autophagy. This study demonstrated that combination therapy with rapamycin and IL-1Ra via MOF carriers enhanced the immunoregulatory effects against atherosclerosis. This drug co-delivery system suggests that MOF carriers loaded with immunomodulators are promising treatments for atherosclerosis or other inflammatory diseases.

Acute, but not chronic, aerobic exercise alters the impact of ex vivo LDL and fatty acid stimulation on monocytes and macrophages from healthy, young adults

BACKGROUND

Elevated low-density lipoprotein (LDL) and triglyceride concentrations are associated with future cardiovascular risk in young adults. Conversely, chronic physical activity is generally accepted to reduce CVD risk. Atherosclerosis is a major underlying cause of CVD, and atherogenesis is mediated by peripheral monocytes and monocyte-derived macrophages. The study aimed to determine if an individual's physical activity level impacts the phenotype of monocytes and monocyte-derived macrophages when stimulated with LDL and fatty acid ex vivo.

METHODS

Peripheral blood mononuclear cells (PBMCs) were obtained from healthy, young adults of differing physical activity levels before and after a single bout of moderate intensity exercise (25 min at 60% of VO_2peak). PBMCs were stimulated with LDL and palmitate ex vivo prior to differentiation into macrophages. Monocyte subset percentages and monocyte-derived macrophage expression of phenotypic (CD86, CD206) and functional (CCR2, ERK 1/2) markers were evaluated by flow cytometry.

RESULTS

Compared to baseline, ex vivo LDL and palmitate stimulation decreased (p = 0.038) non-classical monocyte percentage from 24.7 ± 3.2 to 21.5 ± 2.6% in all participants. When ex vivo lipid stimulation was preceded by acute exercise, non-classical monocyte percentage was similar to baseline levels (p = 0.670, 25.8 ± 2.15%). Macrophage CD86/CD206 was increased from 1.30 ± 0.14 to 1.68 ± 0.19 when preceded by acute exercise in all participants. No differences were observed between participants of differing physical activity levels.

CONCLUSIONS

Findings suggest that acute exercise modulates monocyte phenotype after LDL and palmitate stimulation in a protective manner, however, chronic physical activity does not alter monocyte/macrophage responses to any experimental condition in this population.

Role of prostaglandin E2 in macrophage polarization: Insights into atherosclerosis

Atherosclerosis, a trigger of cardiovascular disease, poses grave threats to human health. Although atherosclerosis depends on lipid accumulation and vascular wall inflammation, abnormal phenotypic regulation of macrophages is considered the pathological basis of atherosclerosis. Macrophage polarization mainly refers to the transformation of macrophages into pro-inflammatory (M1) or anti-inflammatory (M2) phenotypes, which has recently become a much-discussed topic. Increasing evidence has shown that M2 macrophage polarization can alleviate atherosclerosis progression. PGE₂ is a bioactive lipid that has been observed to be elevated in atherosclerosis and to play a pro-inflammatory role, yet recent studies have reported that PGE₂ promotes anti-inflammatory M2 macrophage polarization and mitigates atherosclerosis progression. However, the mechanisms by which PGE₂ acts remain unclear. This review summarizes current knowledge of PGE₂ and macrophages in atherosclerosis. Additionally, we discuss potential PGE₂ mechanisms of macrophage polarization, including CREB, NF-κB, and STAT signaling pathways, which may provide important therapeutic strategies based on targeting PGE₂ pathways to modulate macrophage polarization for atherosclerosis treatment.

Macrophage polarization states in atherosclerosis

Atherosclerosis, a chronic inflammatory condition primarily affecting large and medium arteries, is the main cause of cardiovascular diseases. Macrophages are key mediators of inflammatory responses. They are involved in all stages of atherosclerosis development and progression, from plaque formation to transition into vulnerable plaques, and are considered important therapeutic targets. Increasing evidence suggests that the modulation of macrophage polarization can effectively control the progression of atherosclerosis. Herein, we explore the role of macrophage polarization in the progression of atherosclerosis and summarize emerging therapies for the regulation of macrophage polarization. Thus, the aim is to inspire new avenues of research in disease mechanisms and clinical prevention and treatment of atherosclerosis.

Costunolide alleviates atherosclerosis in high-fat diet-fed ApoE-/- mice through covalently binding to IKKβ and inhibiting NF-κB-mediated inflammation

Costunolide (CTD) is a sesquiterpene lactone isolated from costus root and exhibits various biological activities including anti-inflammation. Since atherosclerosis is a chronic inflammatory disease, we herein investigated the anti-atherosclerotic effects of CTD and the underlying mechanism. Atherosclerosis was induced in ApoE-/- mice by feeding them with a high-fat diet (HFD) for 8 weeks, followed by administration of CTD (10, 20 mg ·kg-1·d-1, i.g.) for 8 weeks. We showed that CTD administration dose-dependently alleviated atherosclerosis in HFD-fed ApoE-/- mice. Furthermore, we found that CTD dose-dependently reduced inflammatory responses in aortas of the mice, as CTD prevented infiltration of inflammatory cells in aortas and attenuated oxLDL uptake in macrophages, leading to reduced expression of pro-inflammatory and pro-fibrotic molecules in aortas. Similar results were observed in oxLDL-stimulated mouse primary peritoneal macrophages (MPMs) in vitro. We showed that pretreatment with CTD (2.5, 5. 10 μM) restrained oxLDL-induced inflammatory responses in MPMs by blocking pro-inflammatory NF-κB/p65 signaling pathway. We further demonstrated that CTD inactivated NF-κB via covalent binding to cysteine 179 on IKKβ, a canonical upstream regulator of NF-κB, reducing its phosphorylation and leading to conformational change in the active loop of IKKβ. Our results discover IKKβ as the target of CTD for its anti-inflammatory activity and elucidate a molecular mechanism underlying the anti-atherosclerosis effect of CTD. CTD is a potentially therapeutic candidate for retarding inflammatory atherosclerotic diseases.

Inflammation driven metabolic regulation and adaptation in macrophages

Macrophages are a diverse population of phagocytic immune cells involved in the host defense mechanisms and regulation of homeostasis. Usually, macrophages maintain healthy functioning at the cellular level, but external perturbation in their balanced functions can lead to acute and chronic disease conditions. By sensing the cues from the tissue microenvironment, these phagocytes adopt a plethora of phenotypes, such as inflammatory or M1 to anti-inflammatory (immunosuppressive) or M2 subtypes, to fulfill their spectral range of functions. The existing evidence in the literature supports that in macrophages, regulation of metabolic switches and metabolic adaptations are associated with their functional behaviors under various physiological and pathological conditions. Since these macrophages play a crucial role in many disorders, therefore it is necessary to understand their heterogeneity and metabolic reprogramming. Consequently, these macrophages have also emerged as a promising target for diseases in which their role is crucial in driving the disease pathology and outcome (e.g., Cancers). In this review, we discuss the recent findings that link many metabolites with macrophage functions and highlight how this metabolic reprogramming can improve our understanding of cellular malfunction in the macrophages during inflammatory disorders. A systematic analysis of the interconnecting crosstalk between metabolic pathways with macrophages should inform the selection of immunomodulatory therapies for inflammatory diseases.

M1/M2 re-polarization of kaempferol biomimetic NPs in anti-inflammatory therapy of atherosclerosis

Atherosclerosis (AS), a leading cause of death worldwide, involves chronic macrophage inflammation from its initiation to the emergence of complications. Targeting plaque inflammation by re-polarizing pro-inflammatory M1 to anti-inflammatory M2 could therefore provide a promising strategy to treat AS, but currently available anti-inflammatory drugs limit clinical outcomes. In this study, we found that kaempferol (KPF) is capable of potential anti-inflammation as a novel drug candidate, which has been scarcely reported. Building upon these findings, we fabricated a macrophage-biomimetic KPF delivery platform, abbreviated as KPF@MM-NPs to potentiate therapeutic payloads, wherein the designed ROS-responsive Dextran-g-PBMEO NPs with π-π stacking were coated with macrophage membrane (MM) for effective target and accumulation in atherosclerotic lesions. Therapy of KPF@MM-NPs afforded significant decrease in proliferating macrophage inflammation while went with the reduction of key pro-inflammatory cytokines and re-polarization M1 to M2 phenotype, inducing excellent anti-AS responses in ApoE^-/- mice after i.p. delivery. The mechanism of KPF@MM-NPs was further investigated and found it related to block the ROS/NF-κB signaling pathways. Together with as well demonstrated biosafety profiles, this proof-of-concept opens an instructive door for the study of KPF-mediated nanodrugs in treatment of AS based on biomimetic NPs.

Tuning macrophages for atherosclerosis treatment

Atherosclerosis is a chronic inflammatory vascular disease and a leading cause of death worldwide. Macrophages play an important role in inflammatory responses, cell-cell communications, plaque growth and plaque rupture in atherosclerotic lesions. Here, we review the sources, functions and complex phenotypes of macrophages in the progression of atherosclerosis, and discuss the recent approaches in modulating macrophage phenotype and autophagy for atherosclerosis treatment. We then focus on the drug delivery strategies that target macrophages or use macrophage membrane-coated particles to deliver therapeutics to the lesion sites. These biomaterial-based approaches that target, modulate or engineer macrophages have broad applications for disease therapies and tissue regeneration.

Decidual macrophages in recurrent spontaneous abortion

Recurrent spontaneous abortion (RSA) is defined as two or more pregnancy loss, affecting the happiness index of fertility couples. The mechanisms involved in the occurrence of RSA are not clear to date. The primary problem for the maternal immune system is how to establish and maintain the immune tolerance to the semi-allogeneic fetuses. During the pregnancy, decidual macrophages mainly play an important role in the immunologic dialogue. The purpose of this study is to explore decidual macrophages, and to understand whether there is a connection between these cells and RSA by analyzing their phenotypes and functions. Pubmed, Web of Science and Embase were searched. The eligibility criterion for this review was evaluating the literature about the pregnancy and macrophages. Any disagreement between the authors was resolved upon discussion and if required by the judgment of the corresponding author. We summarized the latest views on the phenotype, function and dysfunction of decidual macrophages to illuminate its relationship with RSA.

Obesity Programs Macrophages to Support Cancer Progression

Obesity induces multifactorial effects such as dyslipidemia, insulin resistance, and arterial hypertension that influence the progression of many diseases. Obesity is associated with an increased incidence of cancers, and multiple mechanisms link obesity with cancer initiation and progression. Macrophages participate in the homeostasis of adipose tissue and play an important role in cancer. Adipose tissue expansion in obesity alters the balance between pro- and anti-inflammatory macrophages, which is a primary cause of inflammation. Chronic low-grade inflammation driven by macrophages is also an important characteristic of cancer. Adipocytes secrete various adipokines, including adiponectin, leptin, IL6, and TNFα, that influence macrophage behavior and tumor progression. Furthermore, other metabolic effects of obesity, such as hyperlipidemia, hyperglycemia, and hypercholesterolemia, can also regulate macrophage functionality in cancer. This review summarizes how obesity influences macrophage-tumor cell interactions and the role of macrophages in the response to anticancer therapies under obese conditions.

Identification and validation of a signature based on macrophage cell marker genes to predict recurrent miscarriage by integrated analysis of single-cell and bulk RNA-sequencing

Recurrent miscarriage (RM) is a chronic, heterogeneous autoimmune disease that has serious social and personal consequences. No valid and reliable diagnostic markers or therapeutic targets for RM have been identified. Macrophages impact the innate immune system and can be used as diagnostic and prognostic markers for many diseases. We first collected 16 decidua and villi tissue samples from 5 normal patients and 3 RM patients for single-cell RNA sequencing data analysis and identified 1293 macrophage marker genes. We then screened a recurrent miscarriage cohort (GSE165004) for 186 macrophage-associated marker genes that were significantly differentially expressed between RM patients and the normal pregnancy endometrial tissues, and performed a functional enrichment analysis of differentially expressed genes. We then identified seven core genes (ACTR2, CD2AP, MBNL2, NCSTN, PUM1, RPN2, and TBC1D12) from the above differentially expressed gene group that are closely related to RM using the LASSO, Random Forest and SVM-RFE algorithms. We also used GSE26787 and our own collection of clinical specimens to further evaluate the diagnostic value of the target genes. A nomogram was constructed of the expression levels of these seven target genes to predict RM, and the ROC and calibration curves showed that our nomogram had a high diagnostic value for RM. These results suggest that ACTR2 and NCSTN may be potential targets for preventative RM treatments.

Costimulatory and coinhibitory molecules of B7-CD28 family in cardiovascular atherosclerosis: A review

Accumulating evidence supports the active involvement of vascular inflammation in atherosclerosis pathogenesis. Vascular inflammatory events within atherosclerotic plaques are predominated by innate antigen-presenting cells (APCs), including dendritic cells, macrophages, and adaptive immune cells such as T lymphocytes. The interaction between APCs and T cells is essential for the initiation and progression of vascular inflammation during atherosclerosis formation. B7-CD28 family members that provide either costimulatory or coinhibitory signals to T cells are important mediators of the cross-talk between APCs and T cells. The balance of different functional members of the B7-CD28 family shapes T cell responses during inflammation. Recent studies from both mouse and preclinical models have shown that targeting costimulatory molecules on APCs and T cells may be effective in treating vascular inflammatory diseases, especially atherosclerosis. In this review, we summarize recent advances in understanding how APC and T cells are involved in the pathogenesis of atherosclerosis by focusing on B7-CD28 family members and provide insight into the immunotherapeutic potential of targeting B7-CD28 family members in atherosclerosis.

Increased Macrophage-Specific Arterial Infiltration Relates to Noncalcified Plaque and Systemic Immune Activation in People With Human Immunodeficiency Virus

BACKGROUND

Persistent immune activation is thought to contribute to heightened atherosclerotic cardiovascular disease (ASCVD) risk among people with human immunodeficiency virus (PWH).

METHODS

Participants (≥18 years) with or without human immunodeficiency virus (HIV) and without history of clinical ASCVD were enrolled. We hypothesized that increased macrophage-specific arterial infiltration would relate to plaque composition and systemic immune activation among PWH. We applied a novel targeted molecular imaging approach (technetium-99m [99mTc]-tilmanocept single photon emission computed tomography [SPECT]/CT) and comprehensive immune phenotyping.

RESULTS

Aortic 99mTc-tilmanocept uptake was significantly higher among PWH (n = 20) than participants without HIV (n = 10) with similar 10-year ASCVD risk (P = .02). Among PWH, but not among participants without HIV, noncalcified aortic plaque volume related directly to aortic 99mTc-tilmanocept uptake at different uptake thresholds. An interaction (P = .001) was seen between HIV status and noncalcified plaque volume, but not calcified plaque (P = .83). Systemic levels of caspase-1 (P = .004), CD14-CD16+ (nonclassical/patrolling/homing) monocytes (P = .0004) and CD8+ T cells (P = .005) related positively and CD4+/CD8+ T-cell ratio (P = .02) inversely to aortic 99mTc-tilmanocept uptake volume.

CONCLUSIONS

Macrophage-specific arterial infiltration was higher among PWH and related to noncalcified aortic plaque volume only among PWH. Key systemic markers of immune activation relating to macrophage-specific arterial infiltration may contribute to heightened ASCVD risk among PWH.

CLINICAL TRIALS REGISTRATION

NCT02542371.

Acinar ATP8b1/LPC pathway promotes macrophage efferocytosis and clearance of inflammation during chronic pancreatitis development

Noninflammatory clearance of dying cells by professional phagocytes, termed efferocytosis, is fundamental in both homeostasis and inflammatory fibrosis disease but has not been confirmed to occur in chronic pancreatitis (CP). Here, we investigated whether efferocytosis constitutes a novel regulatory target in CP and its mechanisms. PRSS1 transgenic (PRSS1^Tg) mice were treated with caerulein to mimic CP development. Phospholipid metabolite profiling and epigenetic assays were performed with PRSS1^Tg CP models. The potential functions of Atp8b1 in CP model were clarified using Atp8b1-overexpressing adeno-associated virus, immunofluorescence, enzyme-linked immunosorbent assay(ELISA), and lipid metabolomic approaches. ATAC-seq combined with RNA-seq was then used to identify transcription factors binding to the Atp8b1 promoter, and ChIP-qPCR and luciferase assays were used to confirm that the identified transcription factor bound to the Atp8b1 promoter, and to identify the specific binding site. Flow cytometry was performed to analyze the proportion of pancreatic macrophages. Decreased efferocytosis with aggravated inflammation was identified in CP. The lysophosphatidylcholine (LPC) pathway was the most obviously dysregulated phospholipid pathway, and LPC and Atp8b1 expression gradually decreased during CP development. H3K27me3 ChIP-seq showed that increased Atp8b1 promoter methylation led to transcriptional inhibition. Atp8b1 complementation substantially increased the LPC concentration and improved CP outcomes. Bhlha15 was identified as a transcription factor that binds to the Atp8b1 promoter and regulates phospholipid metabolism. Our study indicates that the acinar Atp8b1/LPC pathway acts as an important "find-me" signal for macrophages and plays a protective role in CP, with Atp8b1 transcription promoted by the acinar cell-specific transcription factor Bhlha15. Bhlha15, Atp8b1, and LPC could be clinically translated into valuable therapeutic targets to overcome the limitations of current CP therapies.

Identification of potential drug targets for vascular dementia and carotid plaques by analyzing underlying molecular signatures shared by them

Background

Vascular dementia (VaD) and carotid atherosclerotic plaques are common in the elderly population, conferring a heavy burden on families and society. Accumulating evidence indicates carotid atherosclerotic plaques to be a risk factor for VaD. However, the underlying mechanisms for this association are mainly unknown.

Materials and methods

We analyzed temporal cortex gene expression data of the GSE122063 dataset and gene expression data of the GSE163154 dataset to identify commonly differentially expressed genes (DEGs). Then we performed functional enrichment analysis, immune cell infiltration and evaluation, correlation analysis between differentially expressed immune-related genes (DEIRGs) and immune cells, receiver operating characteristic (ROC) analysis, and drug-gene analysis.

Results

We identified 41 overlapped DEGs between the VaD and carotid atherosclerosis plaque datasets. Functional enrichment analyses revealed that these overlapped DEGs were mainly enriched in inflammatory and immune-related processes. Immunocyte infiltration and evaluation results showed that M0 macrophages, M2 macrophages, and T cells gamma delta had a dominant abundance in carotid atherosclerosis plaque samples, and M0 macrophages showed a significantly different infiltration percentage between the early and advanced stage plaques group. Resting CD4 memory T cells, M2 macrophages, and naive B cells were the top three highest infiltrating fractions in VaD. Furthermore, B cells and NK cells showed a different infiltration percentage between VaD and matched controls. We identified 12 DEIRGs, and the result of correlation analysis revealed that these DEIRGs were closely related to differentially expressed immune cells. We identified five key DEIRGs based on ROC analysis. The drug-gene interaction analysis showed that four drugs (avacopan, CCX354, BMS-817399, and ASK-8007) could be potential drugs for VaD and carotid atherosclerotic plaques treatment.

Conclusion

Collectively, these findings indicated that inflammatory and immune-related processes be a crucial common pathophysiological mechanism shared by VaD and carotid plaques. This study might provide new insights into common molecular mechanisms between VaD and carotid plaques and potential targets for the treatment.

CCL7 as a novel inflammatory mediator in cardiovascular disease, diabetes mellitus, and kidney disease

Chemokines are key components in the pathology of chronic diseases. Chemokine CC motif ligand 7 (CCL7) is believed to be associated with cardiovascular disease, diabetes mellitus, and kidney disease. CCL7 may play a role in inflammatory events by attracting macrophages and monocytes to further amplify inflammatory processes and contribute to disease progression. However, CCL7-specific pathological signaling pathways need to be further confirmed in these chronic diseases. Given the multiple redundancy system among chemokines and their receptors, further experimental and clinical studies are needed to clarify whether direct CCL7 inhibition mechanisms could be a promising therapeutic approach to attenuating the development of cardiovascular disease, diabetes mellitus, and kidney disease.

Myeloid TM6SF2 Deficiency Inhibits Atherosclerosis

Genetic variants in transmembrane 6 superfamily member 2 (TM6SF2), such as E167K, are associated with atherosclerotic cardiovascular disease (ASCVD). Chronic inflammation and lipid-laden macrophage foam cell formation are the central pathogeneses in the development of atherosclerosis. This study was undertaken to illustrate the biological function of TM6SF2 in macrophages and its role during atherosclerosis development. We generated myeloid cell-specific Tm6sf2 knockout mice on ApoE-deficient background (LysM Cre+/Tm6sf2fl/fl/ApoE-/-, TM6 mKO) with littermate LysM Cre-/Tm6sf2fl/fl/ApoE-/- (Control) mice as controls. Mice were fed a Western diet for 12 weeks to induce atherosclerosis. Myeloid Tm6sf2 deficiency inhibited atherosclerosis and decreased foam cells in the plaques without changing the plasma lipid profile. RNA sequencing of bone marrow-derived macrophages (BMDMs) from TM6 mKO mice demonstrated the downregulation of genes associated with inflammation, cholesterol uptake, and endoplasmic reticulum (ER) stress. TM6SF2 was upregulated by oxidized low-density lipoprotein (oxLDL) in macrophages. Silencing TM6SF2 in THP-1-derived macrophages and Tm6sf2 deficiency in BMDMs reduced inflammatory responses and ER stress and attenuated cholesterol uptake and foam cell formation, while the overexpression of TM6SF2 showed opposite effects. In conclusion, myeloid TM6SF2 deficiency inhibits atherosclerosis development and is a potential therapeutic target for the treatment of atherogenesis.

Integration of single-cell and bulk RNA-seq to establish a predictive signature based on the differentiation trajectory of M2 macrophages in lung adenocarcinoma

Background: Tumor-associated macrophages as important members of the tumor microenvironment, are highly plastic and heterogeneous. TAMs can be classified into two preliminary subtypes: M1 and M2 macrophages. M2 macrophages are significantly associated with the progression of lung adenocarcinoma. However, no study has investigated the heterogeneity among M2 macrophages and their differentiation-related genes at the single-cell level to guide the clinical treatment of lung adenocarcinoma.

Methods: Using the available annotation information from the Tumor Immune Single-cell Hub database, we clustered and annotated 12 lung adenocarcinoma samples using the R package ‘Seurat’. Subsequently, we extracted M2 macrophages for secondary clustering analysis and performed cell trajectory analysis using the R package ‘monocle2’. Based on heterogeneous genes associated with the differentiation trajectory of M2 macrophages, we established a prognostic lung adenocarcinoma model using Lasso-Cox and multivariate stepwise regression. In addition, we also performed immunotherapy and chemotherapy predictions.

Results: M2 macrophages exhibit heterogeneity among themselves. M2 macrophages in different differentiation states showed significant differences in pathway activation and immune cell communication. Prognostic signature based on heterogeneous genes can be used to classify the prognostic status and abundance of immune cell infiltration in lung adenocarcinoma patients. In addition, the calculation of the Tumor Immune Dysfunction and Exclusion (TIDE) algorithm and the validation of the GSE126044 database indicated that lung adenocarcinoma patients with high-risk scores had poorer treatment outcomes when receiving immune checkpoint inhibitors treatment.

Conclusion: Based on scRNA-seq and Bulk-seq data, we identified M2 macrophage-associated prognostic signature with a potential clinical utility to improve precision therapy.

Tumor-associated macrophages in liver cancer: From mechanisms to therapy

Multidimensional analyses have demonstrated the presence of a unique tumor microenvironment (TME) in liver cancer. Tumor-associated macrophages (TAMs) are among the most abundant immune cells infiltrating the TME and are present at all stages of liver cancer progression, and targeting TAMs has become one of the most favored immunotherapy strategies. In addition, macrophages and liver cancer cells have distinct origins. At the early stage of liver cancer, macrophages can provide a niche for the maintenance of liver cancer stem cells. In contrast, cancer stem cells (CSCs) or poorly differentiated tumor cells are key factors modulating macrophage activation. In the present review, we first propose the origin connection between precursor macrophages and liver cancer cells. Macrophages undergo dynamic phenotypic transition during carcinogenesis. In this course of such transition, it is critical to determine the appropriate timing for therapy and block specific markers to suppress pro-tumoral TAMs. The present review provides a more detailed discussion of transition trends of such surface markers than previous reviews. Complex crosstalk occurs between TAMs and liver cancer cells. TAMs play indispensable roles in tumor progression, angiogenesis, and autophagy due to their heterogeneity and robust plasticity. In addition, macrophages in the TME interact with other immune cells by directing cell-to-cell contact or secreting various effector molecules. Similarly, tumor cells combined with other immune cells can drive macrophage recruitment and polarization. Despite the latest achievements and the advancements in treatment strategies following TAMs studies, comprehensive discussions on the communication between macrophages and cancer cells or immune cells in liver cancer are currently lacking. In this review, we discussed the interactions between TAMs and liver cancer cells (from cell origin to maturation), the latest therapeutic strategies (including chimeric antigen receptor macrophages), and critical clinical trials for hepatocellular carcinoma (HCC) and intrahepatic cholangiocarcinoma (iCCA) to provide a rationale for further clinical investigation of TAMs as a potential target for treating patients with liver cancer.

Adipose tissue macrophage in obesity-associated metabolic diseases

Adipose tissue macrophage (ATM) has been appreciated for its critical contribution to obesity-associated metabolic diseases in recent years. Here, we discuss the regulation of ATM on both metabolic homeostatsis and dysfunction. In particular, the macrophage polarization and recruitment as well as the crosstalk between ATM and adipocyte in thermogenesis, obesity, insulin resistance and adipose tissue fibrosis have been reviewed. A better understanding of how ATM regulates adipose tissue remodeling may provide novel therapeutic strategies against obesity and associated metabolic diseases.

Role of resveratrol in inhibiting pathological cardiac remodeling

Cardiovascular disease is a group of diseases with high mortality in clinic, including hypertension, coronary heart disease, cardiomyopathy, heart valve disease, heart failure, to name a few. In the development of cardiovascular diseases, pathological cardiac remodeling is the most common cardiac pathological change, which often becomes a domino to accelerate the deterioration of the disease. Therefore, inhibiting pathological cardiac remodeling may delay the occurrence and development of cardiovascular diseases and provide patients with greater long-term benefits. Resveratrol is a non-flavonoid polyphenol compound. It mainly exists in grapes, berries, peanuts and red wine, and has cardiovascular protective effects, such as anti-oxidation, inhibiting inflammatory reaction, antithrombotic, dilating blood vessels, inhibiting apoptosis and delaying atherosclerosis. At present, the research of resveratrol has made rich progress. This review aims to summarize the possible mechanism of resveratrol against pathological cardiac remodeling, in order to provide some help for the in-depth exploration of the mechanism of inhibiting pathological cardiac remodeling and the development and research of drug targets.

Identification Markers of Carotid Vulnerable Plaques: An Update

Vulnerable plaques have been a hot topic in the field of stroke and carotid atherosclerosis. Currently, risk stratification and intervention of carotid plaques are guided by the degree of luminal stenosis. Recently, it has been recognized that the vulnerability of plaques may contribute to the risk of stroke. Some classical interventions, such as carotid endarterectomy, significantly reduce the risk of stroke in symptomatic patients with severe carotid stenosis, while for asymptomatic patients, clinically silent plaques with rupture tendency may expose them to the risk of cerebrovascular events. Early identification of vulnerable plaques contributes to lowering the risk of cerebrovascular events. Previously, the identification of vulnerable plaques was commonly based on imaging technologies at the macroscopic level. Recently, some microscopic molecules pertaining to vulnerable plaques have emerged, and could be potential biomarkers or therapeutic targets. This review aimed to update the previous summarization of vulnerable plaques and identify vulnerable plaques at the microscopic and macroscopic levels.

Tribbles 3 deficiency promotes atherosclerotic fibrous cap thickening and macrophage-mediated extracellular matrix remodelling

Tribbles 3 (TRIB3) modulates lipid and glucose metabolism, macrophage lipid uptake, with a gain-of-function variant associated with increased cardiovascular risk. Here we set out to examine the role of this pseudokinase in atherosclerotic plaque development. Human endarterectomy atherosclerotic tissue specimens analysed by immunofluorescence showed upregulated TRIB3 in unstable plaques and an enrichment in unstable regions of stable plaques. Atherosclerosis was induced in full body Trib3^KO and Trib3^WT littermate mice by injecting mPCSK9 expressing adeno-associated virus and western diet feeding for 12 weeks. Trib3^KO mice showed expanded visceral adipose depot while circulatory lipid levels remained unaltered compared to wildtype mice. Trib3^KO mice aortae showed a reduced plaque development and improved plaque stability, with increased fibrous cap thickness and collagen content, which was accompanied by increased macrophage content. Analysis of both mouse and human macrophages with reduced TRIB3 expression showed elongated morphology, increased actin expression and altered regulation of genes involved in extracellular matrix remodelling. In summary, TRIB3 controls plaque development and may be atherogenic in vivo. Loss of TRIB3 increases fibrous cap thickness via altered metalloproteinase expression in macrophages, thus inhibiting collagen and elastic fibre degradation, suggesting a role for TRIB3 in the formation of unstable plaques.

Salvianolic acid B inhibits RAW264.7 cell polarization towards the M1 phenotype by inhibiting NF-κB and Akt/mTOR pathway activation

M1 macrophages secrete a large number of proinflammatory factors and promote the expansion of atherosclerotic plaques and processes. Salvianolic acid B (Sal B) exerts anti-inflammatory, antitumor and other effects, but no study has addressed whether Sal B can regulate the polarization of macrophages to exert these anti-atherosclerotic effects. Therefore, we investigated the inhibition of Sal B in M1 macrophage polarization and the underlying mechanism. The effects of different treatments on cell viability, gene expression and secretion of related proteins, phenotypic markers and cytokines were detected by MTT and western blot assays, RT‒qPCR and ELISAs. Cell viability was not significantly changed when the concentration of Sal B was less than 200 μM, and Lipopolysaccharide (LPS) (100 ng/mL) + interferon-γ (IFN-γ) (2.5 ng/mL) successfully induced M1 polarization. RT‒qPCR and ELISAs indicated that Sal B can downregulate M1 marker (Inducible Nitric Oxide Synthase (iNOS), Tumor Necrosis Factor-α (TNF-α), and Interleukin-6 (IL-6)) and upregulate M2 marker (Arginase-1 (Arg-1) and Interleukin-10 (IL-10)) expression. Western blotting was performed to measure the expression of Nuclear Factor-κB (NF-κB), p-Akt, p-mTOR, LC3-II, Beclin-1, and p62, and the results suggested that Sal B inhibits the M1 polarization of RAW264.7 macrophages by promoting autophagy via the NF-κB signalling pathway. The study indicated that Sal B inhibits M1 macrophage polarization by inhibiting NF-κB signalling pathway activation and downregulating Akt/mTOR activation to promote autophagy.

Immunomodulatory responses of differentially polarized macrophages to fungal infections

Macrophages, the first line of defense against invasive fungi in the innate immune system, are widely distributed in the blood and tissues of the body. In response to various internal and external stimulators, macrophages can polarize into classically activated macrophages (M1) and alternatively activated macrophages (M2). These two types of polarized macrophages play different roles in antifungal activity and in maintaining the steady-state balance between inflammation and tissue repair. However, the antifungal mechanisms of M1- and M2-type macrophages have not been fully described. In this review, the immune regulatory mechanisms against pathogenic fungi of these two classical types of macrophages in various tissues are summarized. The effects of antifungal factors on macrophage differentiation are also highlighted. The description of these data, on the one hand provides valuable insight for future investigations and also highlights new strategies for the treatment of pathogenic fungal infections.

ERCC5, HES6 and RORA are potential diagnostic markers of coronary artery disease

The mortality rate of patients with coronary artery disease (CAD) increases year by year, and the age of onset is decreasing, primarily because of the lack of an efficient and convenient diagnostic method for CAD. In the present study, we aimed to detect CAD-correlated biomarkers and the regulatory pathways involved through weighted co-expression network analysis. The microarray data originated from 93 CAD patients and 48 controls within the Gene Expression Omnibus (GEO) database. The gene network was implemented by weighted gene co-expression network analysis, and the genes were observed to fall into a range of modules. We took the intersection of genes in the modules most correlated with CAD with the differentially expressed genes of CAD, which were identified by applying the limma package. Lasso regression and support vector machine recursive feature elimination algorithms were used to determine CAD candidate signature genes. The biomarkers for diagnosing CAD were detected by validating candidate signature gene diagnostic capabilities (receiver operating characteristic curves) based on data sets from GEO. Three modules were selected, and 26 vital genes were identified. Eight of these genes were reported as the optimal candidate features in terms of CAD diagnosis. Through receiver operating characteristic curve analysis, we identified three genes (ERCC5, HES6 and RORA; area under the curve > 0.8) capable of distinguishing CAD from the control, and observed that these genes are correlated with the immune response. In summary, ERCC5, HES6 and RORA may have potential for diagnosis of CAD.

New insights into macrophage subsets in atherosclerosis

Macrophages in atherosclerotic patients are notably plastic and heterogeneous. Single-cell RNA sequencing (Sc RNA-seq) can provide information about all the RNAs in individual cells, and it is used to identify cell subpopulations in atherosclerosis (AS) and reveal the heterogeneity of these cells. Recently, some findings from Sc RNA-seq experiments have suggested the existence of multiple macrophage subsets in atherosclerotic plaque lesions, and these subsets exhibit significant differences in their gene expression levels and functions. These cells affect various aspects of plaque lesion development, stabilization, and regression, as well as plaque rupture. This article aims to review the content and results of current studies that used RNA-seq to explore the different types of macrophages in AS and the related molecular mechanisms as well as to identify the potential roles of these macrophage types in the pathogenesis of atherosclerotic plaques. Also, this review listed some new therapeutic targets for delaying atherosclerotic lesion progression and treatment based on the experimental results.

Integrating multiplex immunofluorescent and mass spectrometry imaging to map myeloid heterogeneity in its metabolic and cellular context

Cells often adopt different phenotypes, dictated by tissue-specific or local signals such as cell-cell and cell-matrix contacts or molecular micro-environment. This holds in extremis for macrophages with their high phenotypic plasticity. Their broad range of functions, some even opposing, reflects their heterogeneity, and a multitude of subsets has been described in different tissues and diseases. Such micro-environmental imprint cannot be adequately studied by single-cell applications, as cells are detached from their context, while histology-based assessment lacks the phenotypic depth due to limitations in marker combination. Here, we present a novel, integrative approach in which 15-color multispectral imaging allows comprehensive cell classification based on multi-marker expression patterns, followed by downstream analysis pipelines to link their phenotypes to contextual, micro-environmental cues, such as their cellular ("community") and metabolic ("local lipidome") niches in complex tissue. The power of this approach is illustrated for myeloid subsets and associated lipid signatures in murine atherosclerotic plaque.

Cyanidin-3-O-β-Glucoside Attenuates Platelet Chemokines and Their Receptors in Atherosclerotic Inflammation of ApoE-/- Mice

Platelet chemokines play well-established roles in the atherosclerotic inflammation. Cyanidin-3-O-β-glucoside (Cy-3-g) is one of the main bioactive compounds in anthocyanins, but its effects on chemokines during atherosclerosis have not been determined yet. In the present study, ApoE^-/- mice were fed on the chow diet, high-fat diet (HFD), and HFD-supplemented Cy-3-g at 200, 400, and 800 mg/kg diet. After 16 weeks, Cy-3-g significantly alleviated the atherosclerotic lesion and inhibited platelet aggregation and activation. Moreover, Cy-3-g significantly reduced inflammatory chemokines CXCL4, CXCL7, CCL5, CXCL5, CXCL12, and CCL2 in plasma and downregulated CXCR4, CXCR7, and CCR5 on platelets and peripheral blood mononuclear cells. Besides, Cy-3-g decreased the mRNA of TNFα, IFNγ, ICAM-1, VCAM-1, CD68, MMP7, CCL5, CXCR4, and CCR5 in the aorta of mice. Therefore, it suggests that Cy-3-g plays important preventive roles in the process of atherosclerosis via attenuating chemokines and receptors in ApoE^-/- mice.

Matrine inhibits advanced glycation end products-induced macrophage M1 polarization by reducing DNMT3a/b-mediated DNA methylation of GPX1 promoter

Advanced glycation end products (AGEs) are characterized diabetic metabolites inducing macrophage M1 polarization which is crucial in diabetes-exacerbated atherosclerosis. Matrine was proved anti-atherosclerotic. The current study was aimed to investigate the inhibitory effects of matrine on AGEs- induced macrophage M1 polarization and underlying molecular mechanisms. Primary mouse macrophages were exposed to AGEs. Receptor for AGEs (RAGE) and toll-like receptor 4 (TLR4) were over-expressed by vectors. Matrine was used to treat these cells. Inducible nitric oxide synthase (iNOS) expression and pro-inflammatory cytokine production were used to evaluate macrophage M1 polarization. Oxidative stress was assessed by intracellular reactive oxygen species (ROS) generation, total antioxidant capacity (TAC) and malondialdehyde (MDA) contents. Relative mRNA expression level was determined by real-time PCR. Western blotting was used to evaluate protein and protein phosphorylation levels. Bisulfite sequencing PCR (BSP) was used to evaluate DNA methylation. Matrine reduced AGEs exposure-elevated expressions of DNA methyltransferase (DNA MTase, DNMT)3a and DNMT3b in macrophages which were not affected by RAGE or TLR4 over expressions. DNA methylation rate of GPX1 promoter was reduced from 97.22% to 66.67% in AGEs- exposed macrophages treated by matrine. GPX1 expression was up-regulated by matrine, which further suppressed AGEs/RAGE-mediated oxidative stress. Thus, the activation of down-stream TLR4/STAT1 signaling pathway was inhibited by matrine treatment which eventually suppressed AGEs- induced macrophage M1 polarization. However, these effects of matrine were impaired by RAGE and TLR4 overexpression. Results from this study suggested that matrine inhibited AGEs- induced macrophage M1 polarization by suppressing RAGE-induced oxidative stress-mediated TLR4/STAT1 signaling pathway. Matrine exerted anti-oxidant effects via increasing GPX1 expression by inhibiting DNMT3a/b-induced GPX1 promoter DNA methylation.

Dirty Jobs: Macrophages at the Heart of Cardiovascular Disease

Cardiovascular disease (CVD) is one of the greatest public health concerns and is the leading cause of morbidity and mortality in the United States and worldwide. CVD is a broad yet complex term referring to numerous heart and vascular conditions, all with varying pathologies. Macrophages are one of the key factors in the development of these conditions. Macrophages play diverse roles in the maintenance of cardiovascular homeostasis, and an imbalance of these mechanisms contributes to the development of CVD. In the current review, we provide an in-depth analysis of the diversity of macrophages, their roles in maintaining tissue homeostasis within the heart and vasculature, and the mechanisms through which imbalances in homeostasis may lead to CVD. Through this review, we aim to highlight the potential importance of macrophages in the identification of preventative, diagnostic, and therapeutic strategies for patients with CVD.

Specialized Pro-Resolving Mediators Derived from N-3 Polyunsaturated Fatty Acids: Role in Metabolic Syndrome and Related Complications

Significance: Metabolic syndrome (MetS) prevalence continues to grow and represents a serious public health issue worldwide. This multifactorial condition carries the risk of hastening the development of type 2 diabetes (T2D), non-alcoholic fatty liver disease (NAFLD), and cardiovascular diseases (CVD). Another troubling aspect of MetS is the requirement of poly-pharmacological therapy not devoid of side effects. Therefore, there is an urgent need for prospecting alternative nutraceuticals as effective therapeutic agents for MetS. Recent Advances: Currently, there is an increased interest in understanding the regulation of metabolic derangements by specialized pro-resolving lipid mediators (SPMs), especially those derived from the long chain n-3 polyunsaturated fatty acids. Critical Issues: The SPMs are recognized as efficient modulators that are capable of inhibiting the production of pro-inflammatory cytokines, blocking neutrophil activation/recruitment, and inducing non-phlogistic (anti-inflammatory) activation of macrophage engulfment and removal of apoptotic inflammatory cells and debris. The aim of the present review is precisely to first underline key concepts relative to SPM functions before focusing on their status and actions on MetS components (e.g., obesity, glucose dysmetabolism, hyperlipidemia, hypertension) and complications such as T2D, NAFLD, and CVD. Future Directions: Valuable data from preclinical and clinical investigations have emphasized the SPM functions and influence on oxidative stress- and inflammation-related MetS. Despite these promising findings obtained without compromising host defense, additional efforts are needed to evaluate their potential therapeutic applications and further develop practical tools to monitor their bioavailability to cope with cardiometabolic disorders. Antioxid. Redox Signal. 37, 54-83.

Shaping Polarization Of Tumor-Associated Macrophages In Cancer Immunotherapy

Different stimuli can polarize macrophages into two basic types, M1 and M2. Tumor-associated macrophages (TAMs) in the tumor microenvironment (TME) are composed of heterogeneous subpopulations, which include the M1 anti-tumor and M2 pro-tumor phenotypes. TAMs predominantly play a M2-like tumor-promoting role in the TME and regulate various malignant effects, such as angiogenesis, immune suppression, and tumor metastasis; hence, TAMs have emerged as a hot topic of research in cancer therapy. This review focuses on three main aspects of TAMs. First, we summarize macrophage polarization along with the effects on the TME. Second, recent advances and challenges in cancer treatment and the role of M2-like TAMs in immune checkpoint blockade and CAR-T cell therapy are emphasized. Finally, factors, such as signaling pathways, associated with TAM polarization and potential strategies for targeting TAM repolarization to the M1 pro-inflammatory phenotype for cancer therapy are discussed.

Arsenite inhibits M2a polarization of macrophages through downregulation of peroxisome proliferator-activated receptor gamma

Arsenite (As⁺³) is a group one human carcinogen, which has been associated with many diseases. Previous studies indicated that As⁺³ could inhibit wound healing and repair. M2a cells are known as tissue remodeling macrophages, which play an important role in wound repair process. Peroxisome proliferator-activated receptor gamma (PPAR-γ), a key regulator of lipid and glucose metabolism, was found to mediate the IL-4-dependent M2a polarization of macrophages. In the present study, As⁺³ induced dose-dependent inhibition of M2a polarization starting from 0.1 μM in THP-1-derived macrophages stimulated with 20 ng/mL IL-4. Increased lipid accumulation and decreased PPAR-γ expression were also observed in As⁺³-treated M2a macrophages. Rosiglitazone (RSG), a potent PPAR-γ agonist, alleviated the suppressions of PPAR-γ and M2a polarization induced by 2 μM As⁺³. Collectively, these results not only demonstrated that As⁺³ was able to inhibit polarization of M2a cells through PPAR-γ suppression, but also indicated that PPAR-γ could be utilized as a target for the prevention and treatment of As⁺³-induced immunotoxicity.

CCL22-Polarized TAMs to M2a Macrophages in Cervical Cancer In Vitro Model

Macrophages are dynamic cells susceptible to the local microenvironment which includes tumor-associated macrophages (TAMs) in cancers. TAMs are a collection of heterogeneous macrophages, including M1 and M2 subtypes, shaped by various activation modes and labeled with various markers in different tumors. CCL22+-infiltrating cells are thought to be significantly associated with the prognosis of cervical cancer patients. Moreover, CCL22 is an established marker of M2a macrophages. Although the phenotypic identification of M1 and M2 macrophages is well established in mice and human macrophages cultured in a medium with fetal calf serum (FCS), fewer studies have focused on M2 subtypes. In addition, the question of whether CCL22 affects polarization of M2a macrophages remains unanswered. This study constructed a co-culture system to shape TAMs in vitro. We found that CCL22 was mainly secreted by TAMs but not cervical cancer cell lines. Human peripheral blood monocytes were differentiated into uncommitted macrophages (M0) and then polarized to M1, M2a, M2b, and M2c macrophages using LPS plus IFNr, IL-4, LPS plus IL1β, and IL-10, respectively. Using flowcytometry, we found CD80++ was the marker of M1 and M2b, CD206++ was the marker of M2a, and CD163++ was the marker of M2c, compared with M0 macrophages. By regulating CCL22, we found that the mean fluorescence intensity (MFI) of CD206 in TAMs was significantly affected compared to the control group. Therefore, CCL22 could polarize TAMs of cervical cancer toward M2a macrophages. In conclusion, our study revealed that CCL22 could be a therapeutic target for cervical cancer, which might be because of its role in regulating macrophage polarization.

Identification and Validation of Candidate Gene Module Along With Immune Cells Infiltration Patterns in Atherosclerosis Progression to Plaque Rupture via Transcriptome Analysis

Objective

To explore the differentially expressed genes (DEGs) along with infiltrating immune cells landscape and their potential mechanisms in the progression of atherosclerosis from onset to plaque rupture.

Methods

In this study, three atherosclerosis-related microarray datasets were downloaded from the NCBI-GEO database. The gene set enrichment analysis (GSEA) was performed for interpreting the biological insights of gene expression data. The CIBERSORTx algorithm was applied to infer the relative proportions of infiltrating immune cells of the atherosclerotic samples. DEGs of the datasets were screened using R. The protein interaction network was constructed via STRING. The cluster genes were analyzed by the Cytoscape software. Gene ontology (GO) enrichment was performed via geneontology.org. The least absolute shrinkage and selection operator (LASSO) logistic regression algorithm and receiver operating characteristics (ROC) analyses were performed to build machine learning models for differentiating atherosclerosis status. The Pearson correlation analysis was carried out to illustrate the relationship between cluster genes and immune cells. The expression levels of the cluster genes were validated in two external cohorts. Transcriptional factors and drug-gene interaction analysis were performed to investigate the promising targets for atherosclerosis intervention.

Results

Pathways related to immunoinflammatory responses were identified according to GSEA analysis, and the detailed fractions infiltrating immune cells were compared between the early and advanced atherosclerosis. Additionally, we identified 170 DEGs in atherosclerosis progression (|log2FC|≥1 and adjusted p < 0.05). They were mainly enriched in GO terms relating to inflammatory response and innate immune response. A cluster of nine genes, such as ITGB2, C1QC, LY86, CTSS, C1QA, CSF1R, LAPTM5, VSIG4, and CD163, were found to be significant, and their correlations with infiltrating immune cells were calculated. The cluster genes were also validated to be upregulated in two external cohorts. Moreover, C1QA and ITGB2 may exert pathogenic functions in the entire process of atherogenesis.

Conclusions

We reanalyzed the transcriptomic signature of atherosclerosis development from onset to plaque rupture along with the landscape of the immune cell, as well as revealed new insights and specific prospective DEGs for the investigation of disease-associated dynamic molecular processes and their regulations with immune cells.

(9S,13R)-12-oxo-phytodienoic acid attenuates inflammation by inhibiting mPGES-1 and modulating macrophage polarization via NF-κB and Nrf2/HO-1 pathways

Non-steroidal anti-inflammatory drugs (NSAIDs) relieve inflammation by suppressing prostaglandin E₂/cyclooxygenase 2 (PGE₂/COX-2) with cardiovascular and gastrointestinal bleeding risk. Theoretically, suppressing PGE₂ through inhibiting the terminal synthase microsomal prostaglandin E₂ synthase-1 (mPGES-1) instead of upstream COX-2 is ideal for inflammation. Here, (9S,13R)-12-oxo-phytodienoic acid (AA-24) extracted from Artemisia anomala was first screened as an anti-inflammatory candidate and decreased inducible nitric oxide synthase (iNOS), nitric oxide (NO), mPGES-1, and PGE₂ without affecting COX-1/2, thromboxane A₂ (TXA₂) and prostaglandin I₂ (PGI₂). Besides, AA-24 suppressed the differentiation of M0 macrophages to M1 phenotype but enhanced it to M2 phenotype, blocked the activation of NF-κB pathway, and increased the activation of Nrf2 and heme oxygenase-1 (HO-1). Moreover, AA-24 selectively inhibited mPGES-1 and reduced inflamed paw edema in carrageenan-induced mice. In conclusion, AA-24 attenuates inflammation by inhibiting mPGES-1 and modulating macrophage polarization via the NF-κB and Nrf2/HO-1 pathways and could be a promising candidate for developing anti-inflammatory drugs.

Correlation between CD163 expression and resting pain in patients with hip osteoarthritis: Possible contribution of CD163+ monocytes/macrophages to pain pathogenesis

Expression of CD163, a scavenger receptor specifically expressed by monocytes and macrophages, is elevated in the synovial tissue of patients with knee osteoarthritis (OA) compared with healthy controls. However, the association between CD163 expression in the synovium and pain in OA patients is unclear. We investigated the correlation between synovial CD163 expression and resting and active pain levels in patients with hip osteoarthritis (HOA). To investigate the possible contribution of CD163+ subsets to pain pathogenesis, we compared pain-related cytokine expression and M1/M2 macrophage marker expression in CD163+ and CD163- cells. We performed flow cytometric analysis to study the CD163+ cell population. We also examined pain-related cytokine expression and M1/M2 macrophage marker expression on CD163+ CD14^high and CD163+ CD14^low cells using cell sorting. Synovial CD163 expression significantly correlated with resting pain levels (p = 0.006; R = 0.321), but not active pain levels (p = 0.155; R = 0.169). Expression of the M1 macrophage marker CD80 was significantly higher in CD163+ than CD163- cells (p = 0.010), as was the expression of M2 macrophage markers CD206 and IL10 (CD206, p = 0.014; IL10, p = 0.005), and TNFA and IL1B (TNFA, p = 0.002; IL1B, p = 0.001). TNFA expression was significantly higher in CD163+ CD14^low than CD163+ CD14^high cells, while IL1B, IL10, and CD206 expression were comparable among these subsets. Our findings suggest that CD163 expression is associated with higher resting pain scores. As TNF-α plays a role in the pain process, CD163+ CD14^low cells expressing TNFA may be a potent contributor to the pathogenesis of resting pain in HOA.

Proteomic characterization of four subtypes of M2 macrophages derived from human THP-1 cells

Macrophages are widely distributed immune cells that contribute to tissue homeostasis. Human THP-1 cells have been widely used in various macrophage-associated studies, especially those involving pro-inflammatory M1 and anti-inflammatory M2 phenotypes. However, the molecular characterization of four M2 subtypes (M2a, M2b, M2c, and M2d) derived from THP-1 has not been fully investigated. In this study, we systematically analyzed the protein expression profiles of human THP-1-derived macrophages (M0, M1, M2a, M2b, M2c, and M2d) using quantitative proteomics approaches. The commonly and specially regulated proteins of the four M2 subtypes and their potential biological functions were further investigated. The results showed that M2a and M2b, and M2c and M2d have very similar protein expression profiles. These data could serve as an important resource for studies of macrophages using THP-1 cells, and provide a reference to distinguish different M2 subtypes in macrophage-associated diseases for subsequent clinical research.

Effects of IL-38 on Macrophages and Myocardial Ischemic Injury

Macrophages play an important role in clearing necrotic myocardial tissues, myocardial ischemia-reperfusion injury, and ventricular remodeling after myocardial infarction. M1 macrophages not only participate in the inflammatory response in myocardial tissues after infarction, which causes heart damage, but also exert a protective effect on the heart during ischemia. In contrast, M2 macrophages exhibit anti-inflammatory and tissue repair properties by inducing the production of high levels of anti-inflammatory cytokines and fibro-progenitor cells. Interleukin (IL)-38, a new member of the IL-1 family, has been reported to modulate the IL-36 signaling pathway by playing a role similar to that of the IL-36 receptor antagonist, which also affects the production and secretion of macrophage-related inflammatory factors that play an anti-inflammatory role. IL-38 can relieve myocardial ischemia-reperfusion injury by promoting the differentiation of M1 macrophages into M2 macrophages, inhibit the activation of NOD-like receptor thermal protein domain-associated protein 3 (NLRP3) inflammasome, and increase the secretion of anti-inflammatory cytokines, such as IL-10 and transforming growth factor-β. The intact recombinant IL-38 can also bind to interleukin 1 receptor accessory protein-like 1 (IL-1RAPL1) to activate the c-jun N-terminal kinase/activator protein 1 (JNK/AP1) pathway and increase the production of IL-6. In addition, IL-38 regulates dendritic cell-induced cardiac regulatory T cells, thereby regulating macrophage polarization and improving ventricular remodeling after myocardial infarction. Accordingly, we speculated that IL-38 and macrophage regulation may be therapeutic targets for ameliorating myocardial ischemic injury and ventricular remodeling after myocardial infarction. However, the specific mechanism of the IL-38 action warrants further investigation.

Overabundance of Veillonella parvula promotes intestinal inflammation by activating macrophages via LPS-TLR4 pathway

Hirschsprung’s disease-associated enterocolitis (HAEC) is the most common complication of Hirschsprung’s disease (HSCR). The microbiome pattern of intestinal flora in HAEC patients was significantly abnormal compared to that in HSCR patients. The overabundance of V. parvula was detected in the gut of HAEC patients. To elucidate the pathological mechanisms of the overabundance of V. parvula, we established and analyzed inflammatory models induced by LPS or single-bacterial strain transplantation in vivo. The transplantation of V. parvula induced inflammatory response in the colon of mice. Besides, we found that LPS from V. parvula can significantly impair the barrier function of colonic epithelial cells and then activate macrophages which impaired pacemaker function of interstitial cells of Cajal (ICCs). It was thus a vicious cycle, where the macrophage-related inflammation caused by V. parvula via LPS-TLR4 pathway damaged the intestinal motility, which further aggravated the intestinal flora dysbiosis and promoted the development of HAEC. Itaconic acid could break the vicious cycle by inhibiting the activation of macrophages. It could be a potential therapeutic strategy for HAEC patients with intestinal flora dysbiosis.

Macrophage behaviour 72 hours after implantation of biodegradable polymer-based sirolimus-eluting stent in a case of ST elevation myocardial infarction

While the vascular healing process after drug-eluting stent implantation is not fully elucidated, it is generally accepted that macrophages play an important role in inflammation. It is also known that macrophages involved in the pathogenesis of atherosclerosis may stem from several origins, that is, monocyte-derived macrophages versus resident macrophages. However, little is known about the role of human macrophages on reperfusion of culprit coronary arteries in patients with atherosclerotic disease who have sustained acute coronary syndrome. In this present case report, we describe the presence of cluster of differentiation (CD) 163-positive macrophages in close proximity to the stent struts at the luminal site 72 hours after drug-eluting stent implantation in the culprit coronary lesion for ST elevation myocardial infarction by postmortem examination.

Activation of Sigma-1 Receptor Alleviates ER-Associated Cell Death and Microglia Activation in Traumatically Injured Mice

BACKGROUND

Endoplasmic reticulum (ER) stress and unfolded protein response (UPR) is associated with neuroinflammation and subsequent cell death following traumatic brain injury (TBI). The sigma-1 receptor (Sig-1R) acts as a dynamic pluripotent modulator of fundamental cellular processes at the mitochondria-associated membranes (MAMs). The activation of Sig-1R is neuroprotective in a variety of central nervous system diseases, but its impact on ER stress induced by traumatic brain injury is not known. This study investigated the role of Sig-1R in regulating the ER stress-mediated microglial activation and programmed cell death (apoptosis and pyroptosis) induced by TBI.

METHODS

Ten human brain tissues were obtained from The Tianjin Medical University General Hospital. Four normal brain tissues were obtained from patients who underwent surgery for cerebral vascular malformation, through which peripheral brain tissues were isolated. Six severe TBI tissues were from patients with brain injury caused by accidents. None of the patients had any other known neurological disorders. Mice with Sig-1R deletion using CRISPR technology were subjected to controlled cortical impact-induced injury. In parallel, wild type C57BL/6J mice were analyzed for outcomes after they were exposed to TBI and received the Sig-1R agonist PRE-084 (10 mg/kg daily for three days) either alone or in combination with the Sig-1R antagonist BD-1047 (10 mg/kg).

RESULTS

The expression of Sig-1R and the 78 kDa glucose-regulated protein, a known UPR marker, were significantly elevated in the injured cerebral tissues from TBI patients and mice subjected to TBI. PRE-084 improved neurological function, restored the cerebral cortical perfusion, and ameliorated and brain edema in C57BL/6J mice subjected to TBI by reducing endoplasmic reticulum stress-mediated apoptosis, pyroptosis, and microglia activation. The effect of PRE-084 was abolished in mice receiving Sig-1R antagonist BD-1047.

CONCLUSIONS

ER stress and UPR were upregulated in TBI patients and mice subjected to TBI. Sig-1R activation by the exogenous activator PRE-084 attenuated microglial cells activation, reduced ER stress-associated programmed cell death, and restored cerebrovascular and neurological function in TBI mice.

Macrophage Subsets and Death Are Responsible for Atherosclerotic Plaque Formation

Cardiovascular diseases, the notorious killer, are mainly caused by atherosclerosis (AS) characterized by lipids, cholesterol, and iron overload in plaques. Macrophages are effector cells and accumulate to the damaged and inflamed sites of arteries to internalize native and chemically modified lipoproteins to transform them into cholesterol-loaded foam cells. Foam cell formation is determined by the capacity of phagocytosis, migration, scavenging, and the features of phenotypes. Macrophages are diverse, and the subsets and functions are controlled by their surrounding microenvironment. Generally, macrophages are divided into classically activated (M1) and alternatively activated (M2). Recently, intraplaque macrophage phenotypes are recognized by the stimulation of CXCL4 (M4), oxidized phospholipids (Mox), hemoglobin/haptoglobin complexes [HA-mac/M(Hb)], and heme (Mhem). The pro-atherogenic or anti-atherosclerotic phenotypes of macrophages decide the progression of AS. Besides, apoptosis, necrosis, ferroptosis, autophagy and pyrotopsis determine plaque formation and cardiovascular vulnerability, which may be associated with macrophage polarization phenotypes. In this review, we first summarize the three most popular hypotheses for AS and find the common key factors for further discussion. Secondly, we discuss the factors affecting macrophage polarization and five types of macrophage death in AS progression, especially ferroptosis. A comprehensive understanding of the cellular and molecular mechanisms of plaque formation is conducive to disentangling the candidate targets of macrophage-targeting therapies for clinical intervention at various stages of AS.

Foam Cells in Atherosclerosis: Novel Insights Into Its Origins, Consequences, and Molecular Mechanisms

Foam cells play a vital role in the initiation and development of atherosclerosis. This review aims to summarize the novel insights into the origins, consequences, and molecular mechanisms of foam cells in atherosclerotic plaques. Foam cells are originated from monocytes as well as from vascular smooth muscle cells (VSMC), stem/progenitor cells, and endothelium cells. Novel technologies including lineage tracing and single-cell RNA sequencing (scRNA-seq) have revolutionized our understanding of subtypes of monocyte- and VSMC-derived foam cells. By using scRNA-seq, three main clusters including resident-like, inflammatory, and triggering receptor expressed on myeloid cells-2 (Trem2 hi ) are identified as the major subtypes of monocyte-derived foam cells in atherosclerotic plaques. Foam cells undergo diverse pathways of programmed cell death including apoptosis, autophagy, necroptosis, and pyroptosis, contributing to the necrotic cores of atherosclerotic plaques. The formation of foam cells is affected by cholesterol uptake, efflux, and esterification. Novel mechanisms including nuclear receptors, non-coding RNAs, and gut microbiota have been discovered and investigated. Although the heterogeneity of monocytes and the complexity of non-coding RNAs make obstacles for targeting foam cells, further in-depth research and therapeutic exploration are needed for the better management of atherosclerosis.