Targeting of Scavenger Receptors Stabilin-1 and Stabilin-2 Ameliorates Atherosclerosis by a Plasma Proteome Switch Mediating Monocyte/Macrophage Suppression

Transcriptomic signatures of atheroresistance in the human atrium and ventricle highlight potential candidates for targeted atherosclerosis therapeutics

Atherosclerosis risk is not uniform throughout the cardiovascular system. This study therefore aimed to compare the transcriptomes of atheroresistant human atrium and ventricle with atheroprone coronary arteries to identify transcriptomic signatures of atheroresistance and potential targets for atherosclerosis therapeutics. Using publicly available gene read counts, differentially expressed genes between the atrium, ventricle, and coronary artery were identified for each contrast and validated against the Swiss Institute of Bioinformatics' Bgee database. Over-representation analysis and active-subnetwork-oriented enrichment assessment then identified enriched terms, which were grouped into endothelial dysfunction-related processes. Potential biological significance was further explored with pathway analysis. Among 21474 features, 12656 differentially expressed genes were identified across the three contrasts and associated with 1215 enriched terms. There were 315 down-regulated and 133 up-regulated genes associated with endothelial dysfunction-related processes across the contrasts, including immune modulators, cell adhesion molecules, and lipid metabolism- and coagulation-related molecules. Differentially expressed genes were associated with six down-regulated Kyoto Encyclopedia of Genes and Genomes pathways, related to immune cell and associated endothelium functions. Review of regulated genes associated with endothelial dysfunction-related processes and included in these pathways, indicate immune cell-associated B cell scaffold protein with ankyrin repeats 1, as well as arterial endothelial cell-associated vascular cell adhesion molecule 1 and cadherin 5, as potential atherosclerosis targets.

Identification of multiple novel procoagulant plasma ligands for stabilin-2

BACKGROUND

Damaging STAB2 gene variants are associated with increased venous thromboembolic risk. STAB2 encodes stabilin-2, a clearance receptor, expressed by the liver and spleen. Given its function, it is likely that the prothrombotic state associated with stabilin-2 deficiency is due to reduced procoagulant protein clearance, but the identity of these ligands is unknown.

OBJECTIVES

To identify plasma stabilin-2 ligands using proximity biotinylation proteomics.

METHODS

Cells stably expressing stabilin-2-TurboID were incubated with human plasma and biotin to initiate TurboID labeling of plasma ligands in endocytic vesicles. Biotinylated proteins were purified and identified using mass spectrometry. Candidate plasma ligands with roles in hemostasis were fluorescently labeled and incubated with stabilin-2 expressing and control cells. Flow cytometry assessed ligand surface binding and confocal microcopy assessed colocalization with stabilin-2 and lysosomes. Furthermore, plasma levels of ligands were measured in Stab2-deficient mice and littermate controls.

RESULTS

Twenty-eight stabilin-2 specific ligands were identified. Interactions with von Willebrand factor, fibrinogen, pro(thrombin), heparin cofactor II, high molecular weight kininogen, plasminogen, and C4b-binding protein were probed. Heparin cofactor II, high molecular weight kininogen, plasminogen, and fibrinogen showed binding to stabilin-2 using flow cytometry (>2-fold higher than controls). Confocal microscopy demonstrated stabilin-2 dependent colocalization of all ligands with lysosomes. In Stab2-deficient mice, ligand levels were not significantly increased, suggesting in mice stabilin-2 is not their main clearance receptor.

CONCLUSION

These results confirm the value of proximity labeling proteomics in identifying receptor ligands and suggest damaging STAB2 variants may increase venous thromboembolic risk potentially through altered hemostatic protein clearance.

Macrophage WEE1 Directly Binds to and Phosphorylates NF-κB p65 Subunit to Induce Inflammatory Response and Drive Atherosclerosis

Atherosclerosis has an urgent need for new therapeutic targets. Protein kinases orchestrate multiple cellular events in atherosclerosis and may provide new therapeutic targets for atherosclerosis. Here, a protein kinase, WEE1 G2 checkpoint kinase (WEE1), promoting inflammation in atherosclerosis is identified. Kinase enrichment analysis and experimental evidences reveal macrophage WEE1 phosphorylation at S642 in human and mouse atherosclerotic tissues. RNA-seq analysis, combined with experiment studies using mutant WEE1 plasmids, shows that WEE1 phosphorylation, rather than WEE1 expression, mediated oxLDL-induced inflammation in macrophages. Macrophage-specific deletion of WEE1 or pharmacological inhibition of WEE1 kinase activity attenuates atherosclerosis by reducing inflammation in mice. Mechanistically, RNA-seq and co-immunoprecipitation followed by proteomics analysis are used to explore the mechanism and substrate of WEE1. p-WEE1 promoted inflammatory response through activating NF-κB shown and further revealed that WEE1 can directly bind to the p65 subunit. It is confirmed that p-WEE1 directly interacts with the RHD domain of p65 and phosphorylates p65 at S536, thereby facilitating subsequent NF-κB activation and inflammatory response in macrophages. The findings demonstrate that macrophage WEE1 drives NF-κB activation and atherosclerosis by directly phosphorylating p65 at S536. This study identifies WEE1 as a new upstream kinase of p65 and a potential therapeutic target for atherosclerosis.

Omics research in atherosclerosis

Atherosclerosis (AS) is a chronic inflammatory disease characterized by lipid deposition within the arterial intima, as well as fibrous tissue proliferation and calcification. AS has long been recognized as one of the primary pathological foundations of cardiovascular diseases in humans. Its pathogenesis is intricate and not yet fully elucidated. Studies have shown that AS is associated with oxidative stress, inflammatory response, lipid deposition, and changes in cell phenotype. Unfortunately, there is currently no effective prevention or targeted treatment for AS. The rapid advancement of omics technologies, including genomics, transcriptomics, proteomics, and metabolomics, has opened up novel avenues to elucidate the fundamental pathophysiology and associated mechanisms of AS. Here, we review articles published over the past decade and focus on the current status, challenges, limitations, and prospects of omics in AS research and clinical practice. Emphasizing potential targets based on omics technologies will improve our understanding of this pathological condition and assist in the development of potential therapeutic approaches for AS-related diseases.

STAB1 Promotes Acute Myeloid Leukemia Progression by Activating the IKK/NF-κB Pathway and Increasing M2 Macrophage Polarization

As a multifunctional scavenger receptor, stabilin-1 (STAB1) has been identified to induce chronic inflammation and promote cancer progression. Although in silico studies from multiple data sets showed that STAB1 might facilitate the progression of acute myeloid leukemia (AML) and drug resistance, the real impacts of STAB1 expression on AML patients and the detailed mechanisms remain unclear. Herein, we found that a higher expression of STAB1 is associated with a worse prognosis in AML patients. Subsequent in vitro experiments demonstrated that STAB1 knockdown suppressed proliferation and promoted apoptosis through regulating the IKK/NF-κB pathway in human AML cell lines HEL and NB4. In addition, in vivo studies showed that STAB1 silencing prolonged survival, reduced proliferation, and inhibited aggressiveness of AML cells in xenograft mouse models. Moreover, we investigated the impact of STAB1 expression in AML cells on macrophage differentiation and found that co-culture of macrophages with conditioned medium from STAB1-knockdown AML cells reduced M2 polarization of macrophages. Taken together, our study suggests that STAB1 promotes growth and aggressiveness of AML cells through activating the IKK/NF-κB pathway while also regulating M2 macrophage polarization within the chronic inflammatory environment. Therefore, targeting STAB1 could be a potential therapeutic strategy for treating AML.

Scavenger endothelial cells alleviate tissue damage by engulfing toxic molecules derived from hemolysis

Hemolysis induces tissue damage by releasing cellular contents into the plasma. It is widely accepted that hemolysis-derived toxic molecules are cleared by macrophages or metabolized in hepatocytes. In zebrafish, we found that scavenger endothelial cells (SECs), a specialized endothelium with remarkable endocytosis capability, engulf both macromolecular hemoglobin (Hb) and small molecular unconjugated bilirubin (UCB), two primary toxic byproducts of hemolysis. These engulfment processes are mediated by the scavenger receptor Stab2. To demonstrate the protective function of SECs during hemolysis, we employed a zebrafish model of erythropoietic porphyria, characterized by excessive protoporphyrin IX (PPIX) accumulation due to ferrochelatase mutation, leading to light-sensitive hemolysis and larva death. We found that SECs facilitate the clearance of excess PPIX via Stab2, thereby mitigating PPIX-induced larval mortality. In addition, mouse SECs possess a conserved capability of scavenging Hb/UCB/PPIX. In conclusion, our study identifies SECs as a detoxification system during physiological and pathological hemolysis, shedding light on their protective role against hemolysis-induced damage.

Mechanisms underpinning the effect of exercise on the non-alcoholic fatty liver disease: review

Non-alcoholic Fatty Liver Disease (NAFLD) - whose terminology was recently replaced by metabolic liver disease (MAFLD) - is an accumulation of triglycerides in the liver of >5 % of its weight. Epidemiological studies indicated an association between NAFLD and reduced physical activity. In addition, exercise has been shown to improve NAFLD independently of weight loss. In this paper, we aim to systematically review molecular changes in sedentary experimental NAFLD models vs. those subjected to exercise. We utilized the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) checklist and standard review techniques. Studies were considered for inclusion if they addressed the primary question: the mechanisms by which exercise influenced NAFLD. This review summarized experimental evidence of improvements in NAFLD with exercise in the absence of weight loss. The pathways involved appeared to have AMPK as a common denominator. See also the graphical abstract(Fig. 1).

Proteomic analysis of whole blood to investigate the therapeutic effects of nervonic acid on cerebral ischemia-reperfusion injury in rats

Introduction

Blood proteomics offers a powerful approach for identifying disease-specific biomarkers. However, no reliable blood markers are currently available for the diagnosis stroke. Nervonic acid (NA), a vital long-chain monounsaturated fatty acid found in mammalian nervous tissue, shows promising therapeutic potential in neurological disorders. This study aimed to develop a reliable methodology for whole blood proteomics to identify early warning biomarkers and evaluate drug treatment efficacy.

Methods

After modeling via the classic thread embolization method, whole blood samples were collected from the rats. Morphological assessments of brain tissue indicated that NA significantly mitigated brain and neuronal damage in rats. The differential protein expression profile was analyzed using Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS) whole blood proteomics.

Results

ZZZGene Ontology (GO) analysis revealed that, compared to ginkgo biloba extract (EGb), the proteins differentially expressed under NA intervention were predominantly involved in oxidative stress response and calcium-dependent adhesion processes. Key targets of NA in the treatment of middle cerebral artery occlusion (MCAO) models included ENO1, STAT3, NME2, VCL, and CCT3.

Discussion

This whole blood proteomic approach provides a comprehensive understanding of protein profiles associated with disease states, offering valuable insights into potential therapeutic targets and enabling the evaluation of NA and EGb intervention efficacy. Our findings underscore the protective effects of NA against cerebral ischemia-reperfusion injury and highlight its potential as a treatment for stroke.

Inhibition of CCR2 attenuates NLRP3-dependent pyroptosis after myocardial ischaemia-reperfusion in rats via the NF-kB pathway

Myocardial infarction (MI) is a leading cause of mortality worldwide, contributing significantly to long-term cardiac dysfunction and heart failure. Effective therapeutic strategies are urgently needed to mitigate the extensive damage caused by MI and subsequent ischemia-reperfusion (I/R) injury. This study investigates the role of the Chemokine receptor 2 (CCR2) in regulating NLRP3-dependent cardiomyocyte pyroptosis following myocardial ischemia-reperfusion (MIR), elucidating its molecular mechanisms. A myocardial ischemia-reperfusion model was established using 124 Sprague-Dawley rats by ligating the left coronary artery, inducing 30 min of ischemia. Following ischemia, RS504393, a selective CCR2 antagonist, was administered intraperitoneally one hour after reperfusion. To further explore the underlying mechanisms, the NF-κB pathway agonist Phorbol 12-myristate 13-acetate (PMA) was administered 1 h post-MIR. The results showed a marked increase in CCR2 expression in the heart, peaking on the first day of reperfusion. Treatment with RS504393 significantly improved short-term cardiac function and reduced myocardial infarction size, decreased myocardial pyroptosis and suppressed the expression of NLRP3, GSDMD, Caspase-1, IL-1β, and IL-18 through inhibition of the NF-κB signaling pathway. This effect was reversed with the administration of PMA. In summary, the inhibition of CCR2 shows potential in mitigating myocardial injury following MIR by modulating the NF-κB signaling pathway. These findings highlight CCR2 as a promising therapeutic target for myocardial ischemia-reperfusion injury.

Male osteoporosis: the impact of lifestyle, from nutrition to physical activity

Male osteoporosis is an increasing worldwide pathological condition, characterized by an increased risk of fragility fractures, that is underestimated, underdiagnosed and undertreated. Prevention and treatment play a pivotal role in reducing fractures, and it is important to remember that therapeutic interventions include balanced nutrition and physical activity. Pharmacological treatments are the main and most effective tool to achieve numerous and decisive benefits in this population. Among these, testosterone replacement therapy, when allowed by circumstances and comorbidities, is useful. Anyway, the main goal is always to start from lifestyle, including nutrition and physical activity, plays a very important and crucial role. The many pieces of this puzzle, called lifestyle, need to be accurately collected and grouped carefully, in order to be able to have a broad picture of what needs to be integrated and what is sufficient for the ultimate purpose of enabling each individual man to have a sufficient basic health point. Thus, the purpose of this short narrative review is to highlight the preventive and therapeutic role of lifestyle components, particularly nutrition and physical activity, in males with osteoporosis. Finally, an evaluation of the impact of the main current diets used in recent years and the main physical activities as strategies for the safety of male bone health.

Development of anti-cancer drugs for tumor-associated macrophages: a comprehensive review and mechanistic insights

This review provides an in-depth summary of the development of anti-cancer drugs for tumor-associated macrophages (TAMs), with a particular focus on the development and tissue specialization of macrophages, and factors influencing the polarization of M1 and M2 macrophages, and mechanistic insights underlying the targeting therapeutic approaches. TAMs, pivotal in the tumor microenvironment, exhibit notable plasticity and diverse functional roles. Influenced by the complex milieu, TAMs polarize into M1-type, which suppresses tumors, and M2-type, which promotes metastasis. Notably, targeting M2-TAMs is a promising strategy for tumor therapy. By emphasizing the importance of macrophages as a therapeutic target of anti-cancer drugs, this review aims to provide valuable insights and research directions for clinicians and researchers.

Exploring the roles of SPARC as a proinflammatory factor and its potential as a novel therapeutic target against cardiovascular disease

Cardiovascular disease (CVD) is a leading cause of death worldwide, and the number of patients with CVD continues to increase despite extensive research and developments in this field. Chronic inflammation is a pivotal pathological component of CVD, and unveiling new proinflammatory factors will help devise novel preventive and therapeutic strategies. The extracellular matrix (ECM) not only provides structural support between cells but also contributes to cellular functions. Secreted protein acidic and rich in cysteine (SPARC) is a collagen-binding matricellular protein that is particularly induced during development and tissue remodeling. A proinflammatory role for SPARC has been demonstrated in various animal models, such as in the lipopolysaccharide-induced footpad model and dextran sodium sulfate-induced colitis model. Recent clinical studies reported a positive correlation between elevated plasma SPARC levels and hypertension, obesity, and the inflammatory marker high-sensitive C-reactive protein. In addition, SPARC gene deletion attenuates the cardiac injury induced by aging, myocardial infarction, and pressure load, suggesting that SPARC has deleterious effects on CVD. This review summarizes the regulatory and proinflammatory mechanisms of SPARC on CVD, chronic kidney disease (CKD), and cerebrovascular disease and discusses the rationale behind measuring SPARC as a biomarker of CVD and the effects of inhibition of SPARC in the prevention and treatment of CVD.

Phenotypical and biochemical characterization of murine psoriasiform and fibrotic skin disease models in Stabilin-deficient mice

Stabilin-1 (Stab1) and Stabilin-2 (Stab2) are scavenger receptors expressed by liver sinusoidal endothelial cells (LSECs). The Stabilin-mediated scavenging function is responsible for regulating the molecular composition of circulating blood in mammals. Stab1 and Stab2 have been shown to influence fibrosis in liver and kidneys and to modulate inflammation in atherosclerosis. In this context, circulating and localized TGFBi and POSTN are differentially controlled by the Stabilins as their receptors. To assess Stab1 and Stab2 functions in inflammatory and fibrotic skin disease, topical Imiquimod (IMQ) was used to induce psoriasis-like skin lesions in mice and Bleomycin (BLM) was applied subcutaneously to induce scleroderma-like effects in the skin. The topical treatment with IMQ, as expected, led to psoriasis-like changes in the skin of mice, including increased epidermal thickness and significant weight loss. Clinical severity was reduced in Stab2-deficient compared to Stab1-deficient mice. We did not observe differential effects in the skin of Stabilin-deficient mice after bleomycin injection. Interestingly, treatment with IMQ led to a significant increase of Stabilin ligand TGFBi plasma levels in Stab2-/- mice, treatment with BLM resulted in a significant decrease in TGFBi levels in Stab1-/- mice. Overall, Stab1 and Stab2 deficiency resulted in minor alterations of the disease phenotypes accompanied by alterations of circulating ligands in the blood in response to the disease models. Stabilin-mediated clearance of TGFBi was altered in these disease processes. Taken together our results suggest that Stabilin deficiency-associated plasma alterations may interfere with preclinical disease severity and treatment responses in patients.

Mechanism of efferocytosis in atherosclerosis

Atherosclerosis (AS) is a chronic inflammatory vascular disease that occurs in the intima of large and medium-sized arteries with the immune system's involvement. It is a common pathological basis for high morbidity and mortality of cardiovascular diseases. Abnormal proliferation of apoptotic cells and necrotic cells leads to AS plaque expansion, necrotic core formation, and rupture. In the early stage of AS, macrophages exert an efferocytosis effect to engulf and degrade apoptotic, dead, damaged, or senescent cells by efferocytosis, thus enabling the regulation of the organism. In the early stage of AS, macrophages rely on this effect to slow down the process of AS. However, in the advanced stage of AS, the efferocytosis of macrophages within the plaque is impaired, which leads to the inability of macrophages to promptly remove the apoptotic cells (ACs) from the organism promptly, causing exacerbation of AS. Moreover, upregulation of CD47 expression in AS plaques also protects ACs from phagocytosis by macrophages, resulting in a large amount of residual ACs in the plaque, further expanding the necrotic core. In this review, we discussed the molecular mechanisms involved in the process of efferocytosis and how efferocytosis is impaired and regulated during AS, hoping to provide new insights for treating AS.

MaiJiTong granule attenuates atherosclerosis by reducing ferroptosis via activating STAT6-mediated inhibition of DMT1 and SOCS1/p53 pathways in LDLR-/- mice

BACKGROUND AND PURPOSE

Atherosclerosis is the primary pathological basis of cardiovascular disease. Ferroptosis is a regulated form of cell death, a process of lipid peroxidation driven by iron, which can initiate and promote atherosclerosis. STAT6 is a signal transducer that shows a potential role in regulating ferroptosis, but, the exact role in ferroptosis during atherogenesis remains unclear. The Traditional Chinese Medicine Maijitong granule (MJT) is used for treating cardiovascular disease and shows a potential inhibitory effect on ferroptosis. However, the antiatherogenic effect and the underlying mechanism remain unclear. In this study, we determined the role of STAT6 in ferroptosis during atherogenesis, investigated the antiatherogenic effect of MJT, and determined whether its antiatherogenic effect was dependent on the inhibition of ferroptosis.

METHODS

8-week-old male LDLR-/- mice were fed a high-fat diet (HFD) at 1st and 10th week, respectively, to assess the preventive and therapeutic effects of MJT on atherosclerosis and ferroptosis. Simultaneously, the anti-ferroptotic effects and mechanism of MJT were determined by evaluating the expression of genes responsible for lipid peroxidation and iron metabolism. Subsequently, we reanalyzed microarray data in the GSE28117 obtained from cells after STAT6 knockdown or overexpression and analyzed the correlation between STAT6 and ferroptosis. Finally, the STAT6-/- mice were fed HFD and injected with AAV-PCSK9 to validate the role of STAT6 in ferroptosis during atherogenesis and revealed the antiatherogenic and anti-ferroptotic effect of MJT.

RESULTS

MJT attenuated atherosclerosis by reducing plaque lesion area and enhancing plaque stability in both preventive and therapeutic groups. MJT reduced inflammation via suppressing inflammatory cytokines and inhibited foam cell formation by lowering the LDL level and promoting ABCA1/G1-mediated lipid efflux. MJT ameliorated the ferroptosis by reducing lipid peroxidation and iron dysregulation during atherogenesis. Mechanistically, STAT6 negatively regulated ferroptosis by transcriptionally suppressing SOCS1/p53 and DMT1 pathways. MJT suppressed the DMT1 and SOCS1/p53 via stimulating STAT6 phosphorylation. In addition, STAT6 knockout exacerbated atherosclerosis and ferroptosis, which abolished the antiatherogenic and anti-ferroptotic effects of MJT.

CONCLUSION

STAT6 acts as a negative regulator of ferroptosis and atherosclerosis via transcriptionally suppressing DMT1 and SOCS1 expression and MJT attenuates atherosclerosis and ferroptosis by activating the STAT6-mediated inhibition of DMT1 and SOCS1/p53 pathways, which indicated that STAT6 acts a novel promising therapeutic target to ameliorate atherosclerosis by inhibiting ferroptosis and MJT can serve as a new therapy for atherosclerosis treatment.

Uptake of ox-LDL by binding to LRP6 mediates oxidative stress-induced BMSCs senescence promoting obesity-related bone loss

Obesity has long been thought to be a main cause of hyperlipidemia. As a systemic disease, the impact of obesity on organs, tissues and cells is almost entirely negative. However, the relationship between obesity and bone loss is highly controversial. On the one hand, obesity has long been thought to have a positive effect on bone due to increased mechanical loading on the skeleton, conducive to increasing bone mass to accommodate the extra weight. On the other hand, obesity-related metabolic oxidative modification of low-density lipoprotein (LDL) in vivo causes a gradual increase of oxidized LDL (ox-LDL) in the bone marrow microenvironment. We have reported that low-density lipoprotein receptor-related protein 6 (LRP6) acts as a receptor of ox-LDL and mediates the bone marrow stromal cells (BMSCs) uptake of ox-LDL. We detected elevated serum ox-LDL in obese mice. We found that ox-LDL uptake by LRP6 led to an increase of intracellular reactive oxygen species (ROS) in BMSCs, and N-acetyl-L-cysteine (NAC) alleviated the cellular senescence and impairment of osteogenesis induced by ox-LDL. Moreover, LRP6 is a co-receptor of Wnt signaling. We found that LRP6 preferentially binds to ox-LDL rather than dickkopf-related protein 1 (DKK1), both inhibiting Wnt signaling and promoting BMSCs senescence. Mesoderm development LRP chaperone (MESD) overexpression inhibits ox-LDL binding to LRP6, attenuating oxidative stress and BMSCs senescence, eventually rescuing bone phenotype.

Aging-related defects in macrophage function are driven by MYC and USF1 transcriptional programs

Macrophages are central innate immune cells whose function declines with age. The molecular mechanisms underlying age-related changes remain poorly understood, particularly in human macrophages. We report a substantial reduction in phagocytosis, migration, and chemotaxis in human monocyte-derived macrophages (MDMs) from older (>50 years old) compared with younger (18-30 years old) donors, alongside downregulation of transcription factors MYC and USF1. In MDMs from young donors, knockdown of MYC or USF1 decreases phagocytosis and chemotaxis and alters the expression of associated genes, alongside adhesion and extracellular matrix remodeling. A concordant dysregulation of MYC and USF1 target genes is also seen in MDMs from older donors. Furthermore, older age and loss of either MYC or USF1 in MDMs leads to an increased cell size, altered morphology, and reduced actin content. Together, these results define MYC and USF1 as key drivers of MDM age-related functional decline and identify downstream targets to improve macrophage function in aging.

Biomechanics-mediated endocytosis in atherosclerosis

Biomechanical forces, including vascular shear stress, cyclic stretching, and extracellular matrix stiffness, which influence mechanosensitive channels in the plasma membrane, determine cell function in atherosclerosis. Being highly associated with the formation of atherosclerotic plaques, endocytosis is the key point in molecule and macromolecule trafficking, which plays an important role in lipid transportation. The process of endocytosis relies on the mobility and tension of the plasma membrane, which is sensitive to biomechanical forces. Several studies have advanced the signal transduction between endocytosis and biomechanics to elaborate the developmental role of atherosclerosis. Meanwhile, increased plaque growth also results in changes in the structure, composition and morphology of the coronary artery that contribute to the alteration of arterial biomechanics. These cross-links of biomechanics and endocytosis in atherosclerotic plaques play an important role in cell function, such as cell phenotype switching, foam cell formation, and lipoprotein transportation. We propose that biomechanical force activates the endocytosis of vascular cells and plays an important role in the development of atherosclerosis.

Top Five Stories of the Cellular Landscape and Therapies of Atherosclerosis: Current Knowledge and Future Perspectives

Atherosclerosis (AS) is characterized by impairment and apoptosis of endothelial cells, continuous systemic and focal inflammation and dysfunction of vascular smooth muscle cells, which is documented as the traditional cellular paradigm. However, the mechanisms appear much more complicated than we thought since a bulk of studies on efferocytosis, transdifferentiation and novel cell death forms such as ferroptosis, pyroptosis, and extracellular trap were reported. Discovery of novel pathological cellular landscapes provides a large number of therapeutic targets. On the other side, the unsatisfactory therapeutic effects of current treatment with lipid-lowering drugs as the cornerstone also restricts the efforts to reduce global AS burden. Stem cell- or nanoparticle-based strategies spurred a lot of attention due to the attractive therapeutic effects and minimized adverse effects. Given the complexity of pathological changes of AS, attempts to develop an almighty medicine based on single mechanisms could be theoretically challenging. In this review, the top stories in the cellular landscapes during the initiation and progression of AS and the therapies were summarized in an integrated perspective to facilitate efforts to develop a multi-targets strategy and fill the gap between mechanism research and clinical translation. The future challenges and improvements were also discussed.

Deficiency of Stabilin-1 in the Context of Hepatic Melanoma Metastasis

BACKGROUND

This study analyzed the role of Stabilin-1 on hepatic melanoma metastasis in preclinical mouse models.

METHODS

In Stabilin-1-/- mice (Stab1 KO), liver colonization of B16F10 luc2 and Wt31 melanoma was investigated. The numbers, morphology, and vascularization of hepatic metastases and the hepatic microenvironment were analyzed by immunofluorescence.

RESULTS

While hepatic metastasis of B16F10 luc2 or Wt31 melanoma was unaltered between Stab1 KO and wildtype (Ctrl) mice, metastases of B16F10 luc2 tended to be smaller in Stab1 KO. The endothelial differentiation of both types of liver metastases was similar in Stab1 KO and Ctrl. No differences in initial tumor cell adhesion and retention to the liver vasculature were detected in the B16F10 luc2 model. Analysis of the immune microenvironment revealed a trend towards higher levels of CD45+Gr-1+ cells in Stab1 KO as compared to Ctrl in the B16F10 luc2 model. Interestingly, significantly higher levels of POSTN were found in the matrix of hepatic metastases of Wt31, while liver metastases of B16F10 luc2 showed a trend towards increased deposition of RELN.

CONCLUSIONS

Hepatic melanoma metastases show resistance to Stabilin-1 targeting approaches. This suggests that anti-Stab1 therapies should be considered with respect to the tumor entity or target organs.

Interactions between macrophage membrane and lipid mediators during cardiovascular diseases with the implications of scavenger receptors

The onset and progression of cardiovascular diseases with the major underlying cause being atherosclerosis, occur during chronic inflammatory persistence in the vascular system, especially within the arterial wall. Such prolonged maladaptive inflammation is driven by macrophages and their key mediators are generally attributed to a disparity in lipid metabolism. Macrophages are the primary cells of innate immunity, endowed with expansive membrane domains involved in immune responses with their signalling systems. During atherosclerosis, the membrane domains and receptors control various active organisations of macrophages. Their scavenger/endocytic receptors regulate the trafficking of intracellular and extracellular cargo. Corresponding influence on lipid metabolism is mediated by their dynamic interaction with scavenger membrane receptors and their integrated mechanisms such as pinocytosis, phagocytosis, cholesterol export/import, etc. This interaction not only results in the functional differentiation of macrophages but also modifies their structural configurations. Here, we reviewed the association of macrophage membrane biomechanics and their scavenger receptor families with lipid metabolites during the event of atherogenesis. In addition, the membrane structure of macrophages and the signalling pathways involved in endocytosis integrated with lipid metabolism are detailed. This article establishes future insights into the scavenger receptors as potential targets for cardiovascular disease prevention and treatment.

Bibliometric analysis of monoclonal antibodies for atherosclerosis

Atherosclerosis (AS) is a prevalent cardiovascular disease that greatly increases mortality in the aging population and imposes a heavy burden on global healthcare systems. The purpose of this study is to examine the research structure and current trends of monoclonal antibodies (mAbs) against AS from a bibliometric perspective, since the development of these drugs is currently booming. This study collected articles and reviews on mAbs against AS from the Web of Science Core Collection, spanning from 2003 to 2022. Biblioshiny was utilized to analyze and visualize the characteristics of countries, regions, authors, institutions, and journals included in this collection. We used VOS viewer to illustrate the frequency of country co-occurrence, and CiteSpace to visualize co-cited reference, keywords co-occurrence, keywords citation bursts, keywords clustering and timeline plots. The study included 1325 publications, with the United States emerging as a leading contributor to the field. ATHEROSCLEROSIS, CIRCULATION and ARTERIOSCLEROSISTHROMBOSIS AND VASCULAR BIOLOGY are core journals that publish high-quality literature on the latest advances in the field. Noteworthy authors with numerous high-quality publications include Witztum JL and Tsimikas S. Currently, lipid metabolism and inflammation are the main research areas of interest in this field. The mAbs against AS is an evolving field, and ongoing research continues to advance our understanding. This paper provides a comprehensive overview of the current state of knowledge in this area, highlighting two primary research directions: inflammation and lipid metabolism. Additionally, the paper identifies emerging research hotspots, which will provide researchers with useful insights to guide future investigations and anticipate research directions.

Nanomedicine for Diagnosis and Treatment of Atherosclerosis

With the changing disease spectrum, atherosclerosis has become increasingly prevalent worldwide and the associated diseases have emerged as the leading cause of death. Due to their fascinating physical, chemical, and biological characteristics, nanomaterials are regarded as a promising tool to tackle enormous challenges in medicine. The emerging discipline of nanomedicine has filled a huge application gap in the atherosclerotic field, ushering a new generation of diagnosis and treatment strategies. Herein, based on the essential pathogenic contributors of atherogenesis, as well as the distinct composition/structural characteristics, synthesis strategies, and surface design of nanoplatforms, the three major application branches (nanodiagnosis, nanotherapy, and nanotheranostic) of nanomedicine in atherosclerosis are elaborated. Then, state-of-art studies containing a sequence of representative and significant achievements are summarized in detail with an emphasis on the intrinsic interaction/relationship between nanomedicines and atherosclerosis. Particularly, attention is paid to the biosafety of nanomedicines, which aims to pave the way for future clinical translation of this burgeoning field. Finally, this comprehensive review is concluded by proposing unresolved key scientific issues and sharing the vision and expectation for the future, fully elucidating the closed loop from atherogenesis to the application paradigm of nanomedicines for advancing the early achievement of clinical applications.

Disrupted cardiac fibroblast BCAA catabolism contributes to diabetic cardiomyopathy via a periostin/NAP1L2/SIRT3 axis

BACKGROUND

Periostin is an extracellular matrix protein that plays a critical role in cell fate determination and tissue remodeling, but the underlying role and mechanism of periostin in diabetic cardiomyopathy (DCM) are far from clear. Thus, we aimed to clarify the mechanistic participation of periostin in DCM.

METHODS

The expression of periostin was examined in DCM patients, diabetic mice and high glucose (HG)-exposed cardiac fibroblasts (CF). Gain- and loss-of-function experiments assessed the potential role of periostin in DCM pathogenesis. RNA sequencing was used to investigate the underlying mechanisms of periostin in DCM.

RESULTS

A mouse cytokine antibody array showed that the protein expression of periostin was most significantly upregulated in diabetic mouse heart, and this increase was also observed in patients with DCM or HG-incubated CF. Periostin-deficient mice were protected from diabetes-induced cardiac dysfunction and myocardial damage, while overexpression of periostin held the opposite effects. Hyperglycemia stimulated the expression of periostin in a TGF-β/Smad-dependent manner. RNA sequencing results showed that periostin upregulated the expression of nucleosome assembly protein 1-like 2 (NAP1L2) which recruited SIRT3 to deacetylate H3K27ac on the promoters of the branched-chain amino acid (BCAA) catabolism-related enzymes BCAT2 and PP2Cm, resulting in BCAA catabolism impairment. Additionally, CF-derived periostin induced hypertrophy, oxidative injury and inflammation in primary cardiomyocytes. Finally, we identified that glucosyringic acid (GA) specifically targeted and inhibited periostin to ameliorate DCM.

CONCLUSION

Overall, manipulating periostin expression may function as a promising strategy in the treatment of DCM.

Highly oxidized albumin is cleared by liver sinusoidal endothelial cells via the receptors stabilin-1 and -2

Oxidized albumin (oxHSA) is elevated in several pathological conditions, such as decompensated cirrhosis, acute on chronic liver failure and liver mediated renal failure. Patient derived oxidized albumin was previously shown to be an inflammatory mediator, and in normal serum levels of oxHSA are low. The removal from circulation of oxidized albumins is therefore likely required for maintenance of homeostasis. Liver sinusoidal endothelial cells (LSEC) are prominent scavenger cells specialized in removal of macromolecular waste. Given that oxidized albumin is mainly cleared by the liver, we hypothesized the LSEC are the site of uptake in the liver. In vivo oxHSA was cleared rapidly by the liver and distributed to mainly the LSEC. In in vitro studies LSEC endocytosed oxHSA much more than other cell populations isolated from the liver. Furthermore, it was shown that the uptake was mediated by the stabilins, by affinity chromatography-mass spectrometry, inhibiting uptake in LSEC with other stabilin ligands and showing uptake in HEK cells overexpressing stabilin-1 or -2. oxHSA also inhibited the uptake of other stabilin ligands, and a 2-h challenge with 100 µg/mL oxHSA reduced LSEC endocytosis by 60% up to 12 h after. Thus the LSEC and their stabilins mediate clearance of highly oxidized albumin, and oxidized albumin can downregulate their endocytic capacity in turn.

Single-Cell RNA Sequencing of Coronary Perivascular Adipose Tissue From End-Stage Heart Failure Patients Identifies SPP1+ Macrophage Subpopulation as a Target for Alleviating Fibrosis

BACKGROUND

Perivascular adipose tissue (PVAT) is vital for vascular homeostasis, and PVAT dysfunction is associated with increased atherosclerotic plaque burden. But the mechanisms underlining coronary PVAT dysfunction in coronary atherosclerosis remain elusive.

METHODS

We performed single-cell RNA sequencing of the stromal vascular fraction of coronary PVAT from 3 groups of heart transplant recipients with end-stage heart failure, including 3 patients with nonobstructive coronary atherosclerosis, 3 patients with obstructive coronary artery atherosclerosis, and 4 nonatherosclerosis control subjects. Bioinformatics was used to annotate the cellular populations, depict the cellular developmental trajectories and interactions, and explore the differences among 3 groups of coronary PVAT at the cellular and molecular levels. Pathological staining, quantitative real-time polymerase chain reaction, and in vitro studies were performed to validate the key findings.

RESULTS

Ten cell types were identified among 67 936 cells from human coronary PVAT. Several cellular subpopulations, including SPP1+ (secreted phosphoprotein 1) macrophages and profibrotic fibroadipogenic progenitor cells, were accumulated in PVAT surrounding atherosclerotic coronary arteries compared with nonatherosclerosis coronary arteries. The fibrosis percentage was increased in PVAT surrounding atherosclerotic coronary arteries, and it was positively associated with the grade of coronary artery stenosis. Cellular interaction analysis suggested OPN (osteopontin) secreted by SPP1+ macrophages interacted with CD44 (cluster of differentiation 44)/integrin on fibroadipogenic progenitor cells. Strikingly, correlation analyses uncovered that higher level of SPP1 in PVAT correlates with a more severe fibrosis degree and a higher coronary stenosis grade. In vitro studies showed that conditioned medium from atherosclerotic coronary PVAT promoted the migration and proliferation of fibroadipogenic progenitor cells, while such effect was prevented by blocking CD44 or integrin.

CONCLUSIONS

SPP1+ macrophages accumulated in the PVAT surrounding atherosclerotic coronary arteries, and they promoted the migration and proliferation of fibroadipogenic progenitor cells via OPN-CD44/integrin interaction and thus aggravated the fibrosis of coronary PVAT, which was positively correlated to the coronary stenosis burden. Therefore, SPP1+ macrophages in coronary PVAT may participate in the progression of coronary atherosclerosis.

Tanshinone IIA alleviates atherosclerosis in LDLR-/- mice by regulating efferocytosis of macrophages

Background: Tanshinone IIA (TIIA) is the major lipid-soluble active ingredient of the traditional Chinese medicine Salvia miltiorrhiza, which slows down atherosclerosis (AS). However, it remains unclear whether TIIA has the potential to enhance macrophage efferocytosis and thereby improve atherosclerosis. Objective: The focus of this examination was to determine if TIIA could reduce lipid accumulation and treat AS by enhancing efferocytosis. Methods: Firstly, we conducted in vivo experiments using LDLR knockout (LDLR-/-) mice for a period of 24 weeks, using histopathological staining, immunofluorescence and Western blot experiments to validate from the efficacy and mechanism parts, respectively; in addition, we utilized cells to validate our study again in vitro. The specific experimental design scheme is as follows: In vivo, Western diet-fed LDLR-/- mice for 12 weeks were constructed as an AS model, and normal diet-fed LDLR-/- mice were taken as a blank control group. The TIIA group and positive control group (atorvastatin, ATO) were intervened for 12 weeks by intraperitoneal injection (15 mg/kg/d) and gavage (1.3 mg/kg/d), respectively. In vitro, RAW264.7 cells were cultured with ox-LDL (50 ug/mL) or ox-LDL (50 ug/mL) + TIIA (20 uM/L or 40 uM/L). Pathological changes in aortic plaques and foam cell formation in RAW264.7 cells were evaluated using Masson and Oil Red O staining, respectively. Biochemical methods were used to detect lipid levels in mice. The immunofluorescence assay was performed to detect apoptotic cells and efferocytosis-related signal expression at the plaques. RT-qPCR and Western blot were carried out to observe the trend change of efferocytosis-related molecules in both mouse aorta and RAW264.7 cells. We also used the neutral red assay to assess RAW264.7 cells' phagocytic capacity. Results: Compared with the model group, TIIA decreased serum TC, TG, and LDL-C levels (p < 0.01), reduced the relative lumen area of murine aortic lipid-rich plaques (p < 0.01), enhanced the stability of murine aortic plaques (p < 0.01), reduced ox-LDL-induced lipid build-up in RAW264.7 cells (p < 0.01), and upregulated efferocytosis-related molecules expression and enhance the efferocytosis rate of ox-LDL-induced RAW264.7 cells. Conclusion: TIIA might reduce lipid accumulation by enhancing the efferocytosis of macrophages and thus treat AS.

Rare variant associations with plasma protein levels in the UK Biobank

Integrating human genomics and proteomics can help elucidate disease mechanisms, identify clinical biomarkers and discover drug targets1-4. Because previous proteogenomic studies have focused on common variation via genome-wide association studies, the contribution of rare variants to the plasma proteome remains largely unknown. Here we identify associations between rare protein-coding variants and 2,923 plasma protein abundances measured in 49,736 UK Biobank individuals. Our variant-level exome-wide association study identified 5,433 rare genotype-protein associations, of which 81% were undetected in a previous genome-wide association study of the same cohort5. We then looked at aggregate signals using gene-level collapsing analysis, which revealed 1,962 gene-protein associations. Of the 691 gene-level signals from protein-truncating variants, 99.4% were associated with decreased protein levels. STAB1 and STAB2, encoding scavenger receptors involved in plasma protein clearance, emerged as pleiotropic loci, with 77 and 41 protein associations, respectively. We demonstrate the utility of our publicly accessible resource through several applications. These include detailing an allelic series in NLRC4, identifying potential biomarkers for a fatty liver disease-associated variant in HSD17B13 and bolstering phenome-wide association studies by integrating protein quantitative trait loci with protein-truncating variants in collapsing analyses. Finally, we uncover distinct proteomic consequences of clonal haematopoiesis (CH), including an association between TET2-CH and increased FLT3 levels. Our results highlight a considerable role for rare variation in plasma protein abundance and the value of proteogenomics in therapeutic discovery.

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

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

Deficiency for scavenger receptors Stabilin-1 and Stabilin-2 leads to age-dependent renal and hepatic depositions of fasciclin domain proteins TGFBI and Periostin in mice

Stabilin-1 (Stab1) and Stabilin-2 (Stab2) are two major scavenger receptors of liver sinusoidal endothelial cells that mediate removal of diverse molecules from the plasma. Double-knockout mice (Stab-DKO) develop impaired kidney function and a decreased lifespan, while single Stabilin deficiency or therapeutic inhibition ameliorates atherosclerosis and Stab1-inhibition is subject of clinical trials in immuno-oncology. Although POSTN and TFGBI have recently been described as novel Stabilin ligands, the dynamics and functional implications of these ligands have not been comprehensively studied. Immunofluorescence, Western Blotting and Simple Western™ as well as in situ hybridization (RNAScope™) and qRT-PCR were used to analyze transcription levels and tissue distribution of POSTN and TGFBI in Stab-KO mice. Stab-POSTN-Triple deficient mice were generated to assess kidney and liver fibrosis and function in young and aged mice. TGFBI and POSTN protein accumulated in liver tissue in Stab-DKO mice and age-dependent in glomeruli of Stabilin-deficient mice despite unchanged transcriptional levels. Stab-POSTN-Triple KO mice showed glomerulofibrosis and a reduced lifespan comparable to Stab-DKO mice. However, alterations of the glomerular diameter and vascular density were partially normalized in Stab-POSTN-Triple KO. TGFBI and POSTN are Stabilin-ligands that are deposited in an age-dependent manner in the kidneys and liver due to insufficient scavenging in the liver. Functionally, POSTN might partially contribute to the observed renal phenotype in Stab-DKO mice. This study provides details on downstream effects how Stabilin dysfunction affects organ function on a molecular and functional level.

The contribution of the sinusoidal endothelial cell receptors CLEC4M, stabilin-2, and SCARA5 to VWF-FVIII clearance in thrombosis and hemostasis

Quantitative abnormalities in factor VIII (FVIII) and its binding partner, von Willebrand factor (VWF), are associated with an increased risk of bleeding or thrombosis, and pathways that regulate the clearance of VWF-FVIII can strongly influence their plasma levels. In 2010, the Cohorts for Heart and Aging Research in Genome Epidemiology (CHARGE) on genome-wide association study meta-analysis identified variants in the genes for the sinusoidal endothelial receptors C-type lectin domain family 4 member M (CLEC4M), stabilin-2, and scavenger receptor class A member 5 (SCARA5) as being associated with plasma levels of VWF and/or FVIII in normal individuals. The ability of these receptors to bind, internalize, and clear the VWF-FVIII complex from the circulation has now been reported in a series of studies using in vitro and in vivo models. The receptor stabilin-2 has also been shown to modulate the immune response to infused VWF-FVIII concentrates in a murine model. In addition, the influence of genetic variants in CLEC4M, STAB2, and SCARA5 on type 1 von Willebrand disease/low VWF phenotype, FVIII pharmacokinetics, and the risk of venous thromboembolism has been described in a number of patient-based studies. Understanding the role of these receptors in the regulation of VWF-FVIII clearance has led to significant insights into the genomic architecture that modulates plasma VWF and FVIII levels, improving the understanding of pathways that regulate VWF-FVIII clearance and the mechanistic basis of quantitative VWF-FVIII pathologies.

Identification of TGF-β-related genes in cardiac hypertrophy and heart failure based on single cell RNA sequencing

BACKGROUND

Heart failure (HF) remains a huge medical burden worldwide. Pathological cardiac hypertrophy is one of the most significant phenotypes of HF. Several studies have reported that the TGF-β pathway plays a double-sided role in HF. Therefore, TGF-β-related genes (TRGs) may be potential therapeutic targets for cardiac hypertrophy and HF. However, the roles of TRGs in HF at the single-cell level remain unclear.

METHOD

In this study, to analyze the expression pattern of TRGs during the progress of cardiac hypertrophy and HF, we used three public single-cell RNA sequencing datasets for HF (GSE161470, GSE145154, and GSE161153), one HF transcriptome data (GSE57338), and one hypertrophic cardiomyopathy transcriptome data (GSE141910). Weighted gene co-expression network analysis (WGCNA), functional enrichment analysis and machine learning algorithms were used to filter hub genes. Transverse aortic constriction mice model, CCK-8, wound healing assay, quantitative real-time PCR and western blotting were used to validate bioinformatics results.

RESULTS

We observed that cardiac fibroblasts (CFs) and endothelial cells showed high TGF-β activity during the progress of HF. Three modules (royalblue, brown4, and darkturquoize) were identified to be significantly associated with TRGs in HF. Six hub genes (TANC2, ADAMTS2, DYNLL1, MRC2, EGR1, and OTUD1) showed anomaly trend in cardiac hypertrophy. We further validated the regulation of the TGF-β-MYC-ADAMTS2 axis on CFs activation in vitro.

CONCLUSIONS

This study identified six hub genes (TANC2, ADAMTS2, DYNLL1, MRC2, EGR1, and OTUD1) by integrating scRNA and transcriptome data. These six hub genes might be therapeutic targets for cardiac hypertrophy and HF.

Exploring scavenger receptor class F member 2 and the importance of scavenger receptor family in prediagnostic diseases

Scavenger Receptor Class F Member 2 (SCARF2), also known as the Type F Scavenger Receptor Family gene, encodes for Scavenger Receptor Expressed by Endothelial Cells 2 (SREC-II). This protein is a crucial component of the scavenger receptor family and is vital in protecting mammals from infectious diseases. Although research on SCARF2 is limited, mutations in this protein have been shown to cause skeletal abnormalities in both SCARF2-deficient mice and individuals with Van den Ende-Gupta syndrome (VDEGS), which is also associated with SCARF2 mutations. In contrast, other scavenger receptors have demonstrated versatile responses and have been found to aid in pathogen elimination, lipid transportation, intracellular cargo transportation, and work in tandem with various coreceptors. This review will concentrate on recent progress in comprehending SCARF2 and the functions played by members of the Scavenger Receptor Family in pre-diagnostic diseases.

Association of Differentially Altered Liver Fibrosis with Deposition of TGFBi in Stabilin-Deficient Mice

Liver sinusoidal endothelial cells (LSECs) control clearance of Transforming growth factor, beta-induced, 68kDa (TGFBi) and Periostin (POSTN) through scavenger receptors Stabilin-1 (Stab1) and Stabilin-2 (Stab2). Stabilin inhibition can ameliorate atherosclerosis in mouse models, while Stabilin-double-knockout leads to glomerulofibrosis. Fibrotic organ damage may pose a limiting factor in future anti-Stabilin therapies. While Stab1-deficient (Stab1-/-) mice were shown to exhibit higher liver fibrosis levels upon challenges, fibrosis susceptibility has not been studied in Stab2-deficient (Stab2-/-) mice. Wildtype (WT), Stab1-/- and Stab2-/- mice were fed experimental diets, and local ligand abundance, hepatic fibrosis, and ligand plasma levels were measured. Hepatic fibrosis was increased in both Stab1-/- and Stab2-/- at baseline. A pro-fibrotic short Methionine-Choline-deficient (MCD) diet induced slightly increased liver fibrosis in Stab1-/- and Stab2-/- mice. A Choline-deficient L-amino acid-defined (CDAA) diet induced liver fibrosis of similar distribution and extent in all genotypes (WT, Stab1-/- and Stab2-/-). A hepatic abundance of Stabilin ligand TGFBi correlated very highly with liver fibrosis levels. In contrast, plasma levels of TGFBi were increased only in Stab2-/- mice after the CDAA diet but not the MCD diet, indicating the differential effects of these diets. Here we show that a single Stabilin deficiency of either Stab1 or Stab2 induces mildly increased collagen depositions under homeostatic conditions. Upon experimental dietary challenge, the local abundance of Stabilin ligand TGFBi was differentially altered in Stabilin-deficient mice, indicating differentially affected LSEC scavenger functions. Since anti-Stabilin-directed therapies are in clinical evaluation for the treatment of diseases, these findings bear relevance to treatment with novel anti-Stabilin agents.

Reelin through the years: From brain development to inflammation

Reelin was originally identified as a regulator of neuronal migration and synaptic function, but its non-neuronal functions have received far less attention. Reelin participates in organ development and physiological functions in various tissues, but it is also dysregulated in some diseases. In the cardiovascular system, Reelin is abundant in the blood, where it contributes to platelet adhesion and coagulation, as well as vascular adhesion and permeability of leukocytes. It is a pro-inflammatory and pro-thrombotic factor with important implications for autoinflammatory and autoimmune diseases such as multiple sclerosis, Alzheimer's disease, arthritis, atherosclerosis, or cancer. Mechanistically, Reelin is a large secreted glycoprotein that binds to several membrane receptors, including ApoER2, VLDLR, integrins, and ephrins. Reelin signaling depends on the cell type but mostly involves phosphorylation of NF-κB, PI3K, AKT, or JAK/STAT. This review focuses on non-neuronal functions and the therapeutic potential of Reelin, while highlighting secretion, signaling, and functional similarities between cell types.

Low serum Klotho reflects senile inflammation in middle-aged and elderly patients with coronary atherosclerosis

BACKGROUND

Anti-aging protein Klotho has been reported to be associated with atherosclerosis, which was considered as a chronic inflammatory disease. However, the relationship between Klotho and senile inflammation remained unclear. The present study aims to ascertain the correlation of Klotho with inflammation in middle-aged and elderly coronary atherosclerotic disease (CAD).

METHODS

A total of 302 patients with CAD were included in this study. Coronary atherosclerosis was confirmed and quantified for all patients by coronary angiography. Serum Klotho was detected by enzyme linked immunosorbent assay. Serum concentrations of IL-6 and IL-8 were quantified by chemiluminescence assay. T-lymphocyte subsets were measured using flow cytometry.

RESULTS

Multivariate linear regression analysis showed that serum Klotho was an independent predictor for circulating monocytes (standard β = -0.321, P < 0.001) and CD4+/CD8+ ratio (standard β = -0.522, P < 0.001). After adjustment, serum Klotho was still independently associated with IL-6 (standard β = -0.395, P < 0.001) and IL-8 (standard β = -0.296, P < 0.001). Moreover, circulating monocytes, CD4+ and CD8+ lymphocytes were correlated with increased serum concentrations of IL-6 and IL-8, independent of CRP (P < 0.05). In receiver operating characteristic curve analysis, CD4+/CD8+ ratio (AUC = 0.863, P < 0.001), IL-6 (AUC = 0.893, P < 0.001) and IL-8 (AUC = 0.884, P < 0.001) presented the excellent predictive performance for significant CAD.

CONCLUSIONS

Decreased concentrations in serum Klotho reflect senile inflammation, which is related to the severity of CAD in middle-aged and elderly patients.

Heterogeneity of macrophages in atherosclerosis revealed by single-cell RNA sequencing

Technology at the single-cell level has advanced dramatically in characterizing molecular heterogeneity. These technologies have enabled cell subtype diversity to be seen in all tissues, including atherosclerotic plaques. Critical in atherosclerosis pathogenesis and progression are macrophages. Previous studies have only determined macrophage phenotypes within the plaque, mainly by bulk analysis. However, recent progress in single-cell technologies now enables the comprehensive mapping of macrophage subsets and phenotypes present in plaques. In this review, we have updated and discussed the definition and classification of macrophage subsets in mice and humans using single-cell RNA sequencing. We summarized the different classification methods and perspectives: traditional classification with an updated scoring system, inflammatory macrophages, foamy macrophages, and atherosclerotic-resident macrophages. In addition, some special types of macrophages were identified by specific markers, including IFN-inducible and cavity macrophages. Furthermore, we discussed macrophage subset-specific markers and their functions. In the future, these novel insights into the characteristics and phenotypes of these macrophage subsets within atherosclerotic plaques can provide additional therapeutic targets for cardiovascular diseases.

The serum soluble scavenger with 5 domains levels: A novel biomarker for individuals with heart failure

Background: We aimed to explore the relationship between the serum Soluble Scavenger with 5 Domains (SSC5D) levels and heart failure (HF). Methods and Results: We retrospectively enrolled 276 patients diagnosed with HF or normal during hospitalization in Shanghai General Hospital between September 2020 and December 2021. Previously published RNA sequencing data were re-analyzed to confirm the expression profile of SSC5D in failing and non-failing human and mouse heart tissues. Quantitative real-time polymerase chain reaction assay was used to quantify Ssc5d mRNA levels in murine heart tissue after myocardial infarction and transverse aortic constriction surgery. To understand the HF-induced secreted proteins profile, 1,755 secreted proteins were investigated using human dilated cardiomyopathy RNA-seq data, and the results indicated that SSC5D levels were significantly elevated in failing hearts compared to the non-failing. Using single-cell RNA sequencing data, we demonstrated that Ssc5d is predominantly expressed in cardiac fibroblasts. In a murine model of myocardial infarction or transverse aortic constriction, Ssc5d mRNA levels were markedly increased compared with those in the sham group. Similarly, serum SSC5D levels were considerably elevated in the HF group compared with the control group [15,789.35 (10,745.32-23,110.65) pg/mL, 95% CI (16,263.01-19,655.43) vs. 8,938.72 (6,154.97-12,778.81) pg/mL, 95% CI (9,337.50-11,142.93); p < 0.0001]. Moreover, serum SSC5D levels were positively correlated with N-terminal pro-B-type natriuretic peptide (R = 0.4, p = 7.9e-12) and inversely correlated with left ventricular ejection fraction (R = -0.46, p = 9.8e-16). Conclusion: We concluded that SSC5D was a specific response to HF. Serum SSC5D may function as a novel biomarker and therapeutic target for patients with HF.