Role of LOX-1 (Lectin-Like Oxidized Low-Density Lipoprotein Receptor 1) as a Cardiovascular Risk Predictor: Mechanistic Insight and Potential Clinical Use

The Dectin-1 and Dectin-2 clusters: C-type lectin receptors with fundamental roles in immunity

The ability of myeloid cells to recognize and differentiate endogenous or exogenous ligands rely on the presence of different transmembrane protein receptors. C-type lectin receptors (CLRs), defined by the presence of a conserved structural motif called C-type lectin-like domain (CTLD), are a crucial family of receptors involved in this process, being able to recognize a diverse range of ligands from glycans to proteins or lipids and capable of initiating an immune response. The Dectin-1 and Dectin-2 clusters involve two groups of CLRs, with genes genomically linked within the natural killer cluster of genes in both humans and mice, and all characterized by the presence of a single extracellular CTLD. Fundamental immune cell functions such as antimicrobial effector mechanisms as well as internalization and presentation of antigens are induced and/or regulated through activatory, or inhibitory signalling pathways triggered by these receptors after ligand binding. In this review, we will discuss the most recent concepts regarding expression, ligands, signaling pathways and functions of each member of the Dectin clusters of CLRs, highlighting the importance and diversity of their functions.

Single cell RNA sequencing of human eosinophils from nasal polyps reveals eosinophil heterogeneity in chronic rhinosinusitis tissue

BACKGROUND

Chronic rhinosinusitis with nasal polyps (CRSwNP) is characterized by type 2 inflammation in the United States, but the actual roles that eosinophils play in CRSwNP remain largely unclear.

OBJECTIVE

To reveal the roles and heterogeneity of eosinophils in nasal polyp (NP) tissue, we performed single cell RNA sequencing (scRNA-Seq) analysis of NP tissue.

METHODS

Sinonasal tissues (NP and control sinus tissue) and patient matched peripheral blood (PB) samples were obtained from 5 control patients and 5 patients with CRSwNP. Eosinophils were enriched before processing for scRNA-Seq. The gene expression profiles in eosinophils were determined by microwell-based scRNA-Seq technology (BD Rhapsody platform). We predicted the overall function of NP eosinophils by Gene Ontology (geneontology.org) enrichment and pathway analyses and confirmed expression of selected genes by flow cytometry.

RESULTS

After filtering out contaminating cells, we detected 5,542 eosinophils from control PB, 3,883 eosinophils from CRSwNP PB, 101 eosinophils from control sinus tissues (not included in further analyses), and 9,727 eosinophils from NPs by scRNA-Seq. We found that 204 genes were downregulated and 354 genes upregulated in NP eosinophils compared to all PB eosinophils (>1.5-fold, Padj < .05). Upregulated genes in NP eosinophils were associated with activation, cytokine-mediated signaling, growth factor activity, NF-κB signaling, and antiapoptotic molecules. NP eosinophils displayed 4 clusters revealing potential heterogeneity of eosinophils in NP tissue.

CONCLUSIONS

Elevated eosinophils in NP tissue appear to exist in several subtypes that may play important pathogenic roles in CRSwNP, in part by controlling inflammation and hyperproliferation of other cells.

Siglec-5 as a novel receptor mediates endothelial cells oxLDL transcytosis to promote atherosclerosis

BACKGROUND

Excessive subendothelial retention of oxidized low-density lipoprotein (oxLDL) and subsequent oxLDL engulfment by macrophages leads to the formation of foam cells and the development of atherosclerosis. Our previous study showed that the plasma level of sialic acid-binding immunoglobulin-like lectin 5 (Siglec-5) was a novel biomarker for the prognosis of atherosclerosis in diabetic patients. However, the role and underlying mechanisms of Siglec-5 in atherosclerosis have not been elucidated.

METHODS

The interaction between oxLDL and Siglec-5 was detected by fluorescence colocalization and coimmunoprecipitation. The effect of oxLDL on Siglec-5 expression was detected in endothelial cells and macrophages, and the effect of Siglec-5 on oxLDL transcytosis and uptake was investigated. Siglec-5 was overexpressed in mice using recombinant adeno-associated virus vector serotype 9 (rAAV9-Siglec-5) to evaluate the effect of Siglec-5 on oxLDL uptake and atherogenesis in vivo. In addition, the effects of Siglec-5 antibodies and soluble Siglec-5 proteins on oxLDL transcytosis and uptake and their role in atherogenesis were investigated in vivo and in vitro.

RESULTS

We found that oxLDL interacted with Siglec-5 and that oxLDL stimulated the expression of Siglec-5. Siglec-5 promotes the transcytosis and uptake of oxLDL, while both anti-Siglec-5 antibodies and soluble Siglec-5 protein attenuated oxLDL transcytosis and uptake. Interestingly, overexpression of Siglec-5 by recombinant adeno-associated viral vector serotype 9 (rAAV9-Siglec-5) promoted the retention of oxLDL in the aorta of C57BL/6 mice. Moreover, overexpression of Siglec-5 significantly accelerated the formation of atherosclerotic lesions in Apoe-/- mice. Moreover, both anti-Siglec-5 antibodies and soluble Siglec-5 protein significantly alleviated the retention of oxLDL in the aorta of rAAV9-Siglec-5-transfected C57BL/6 mice and the formation of atherosclerotic plaques in rAAV9-Siglec-5-transfected Apoe-/- mice.

CONCLUSION

Our results suggested that Siglec-5 was a novel receptor that mediated oxLDL transcytosis and promoted the formation of foam cells. Interventions that inhibit the interaction between oxLDL and Siglec-5, including anti-Siglec-5 antibody or soluble Siglec-5 protein treatment, may provide novel therapeutic strategies in treating atherosclerosis.

Targeting Gut Microbiota with Probiotics and Phenolic Compounds in the Treatment of Atherosclerosis: A Comprehensive Review

Atherosclerosis (AS) is a chronic inflammatory vascular disease. Dysregulated lipid metabolism, oxidative stress, and inflammation are the major mechanisms implicated in the development of AS. In addition, evidence suggests that gut dysbiosis plays an important role in atherogenesis, and modulation of the gut microbiota with probiotics and phenolic compounds has emerged as a promising strategy for preventing and treating AS. It has been shown that probiotics and phenolic compounds can improve atherosclerosis-related parameters by improving lipid profile, oxidative stress, and inflammation. In addition, these compounds may modulate the diversity and composition of the gut microbiota and improve atherosclerosis. The studies evaluated in the present review showed that probiotics and phenolic compounds, when consumed individually, improved atherosclerosis by modulating the gut microbiota in various ways, such as decreasing gut permeability, decreasing TMAO and LPS levels, altering alpha and beta diversity, and increasing fecal bile acid loss. However, no study was found that evaluated the combined use of probiotics and phenolic compounds to improve atherosclerosis. The available literature highlights the synergistic potential between phenolic compounds and probiotics to improve their health-promoting properties and functionalities. This review aims to summarize the available evidence on the individual effects of probiotics and phenolic compounds on AS, while providing insights into the potential benefits of nutraceutical approaches using probiotic strains, quercetin, and resveratrol as potential adjuvant therapies for AS treatment through modulation of the gut microbiota.

LOX-1 variants modulate the severity of cardiovascular disease: state of the art and future directions

Atherosclerosis is one of the major causes of cerebral infarction and many other ischemic cardio-cerebrovascular diseases. Although large randomized clinical trials have highlighted the impressive benefits of lipid-lowering therapies, the 50-70% of patients who have achieved their lipid-lowering goal remain at high cardiovascular disease risk. For this reason, there is a need to investigate other markers of atherosclerosis progression. LOX-1 is a scavenger receptor that accepts oxidized low-density lipoproteins as major ligand and internalizes it by endocytosis favoring its retention in subendothelial layer and triggering a wide variety of proatherogenic events. However, other factors such as cytokines, shear stress, and advanced glycation end-products can upregulate LOX-1. LOX-1 is encoded by the OLR1 gene, located in the p12.3-p13 region of chromosome 12. OLR1 gene has different isoforms induced by splicing, or single-nucleotide polymorphisms (SNPs). According to some authors, the expression of these isoforms induces a different effect on atherosclerosis and cardiovascular disease. In particular, LOXIN, an isoform lacking part of the functional domain, exerts an important role in atherosclerosis protection. In other cases, studies on SNPs showed an association with more severe forms, like in the case of 3'UTR polymorphisms. The knowledge of these variants can give rise to the development of new preventive therapies and can lead to the identification of subjects at greater risk of cardiovascular event. In this review, we reported the state of the art regarding SNPs with known effects on OLR1 splicing and how LOX-1 variants modulate the severity of cardiovascular disease.

Elevated levels of oxLDL and LOX-1: Implications for schizophrenia pathophysiology

Inflammation and oxidative stress are both considered to be factors in the etiopathogenesis of schizophrenia. LOX-1 (lectin-like oxidized low-density lipoprotein receptor-1) and ox-LDL (oxidized low-density lipoprotein) have been reported to be active in neuroinflammation pathways in which they are involved in oxidative stress and inflammation. However, its relationship with schizophrenia is unclear. This study aimed to assess the potential connection between serum ox-LDL and LOX-1 levels in schizophrenia patients, their unaffected first-degree relatives, and healthy controls. The study comprised 63 schizophrenia patients, 57 first-degree relatives, and 63 healthy controls who were age, gender, and BMI-matched. Serum ox-LDL and LOX-1 levels were measured. PANSS was used to assess the severity of the disease. Levels of both ox-LDL and LOX-1 were markedly elevated in individuals diagnosed with schizophrenia when compared to both their relatives and a control group. While ox-LDL levels were significantly higher in relatives of patients compared to controls, there was no significant difference between relatives of patients and control groups for LOX-1 levels. Significant correlations were observed between PANNS general and total and ox-LDL levels and PANNS negative and LOX-1 levels. The relationship between ox-LDL and LOX-1 and schizophrenia is quite limited in the literature and is a new field of study. Future studies are needed to evaluate their role in etiopathogenesis.

The PerioGene North Study Uncovers Serum Proteins Related to Periodontitis

The sequalae of periodontitis include irreversible degradation of tooth-supporting structures and circulatory spread of inflammatory mediators. However, the serum protein profile in periodontitis is not well described, which is partly attributable to the limited number of studies based on large and well-characterized periodontitis cohorts. This study aims to identify novel, circulating inflammation-related proteins associated with periodontitis within the PerioGene North case-control study, which includes 478 cases with severe periodontitis and 509 periodontally healthy controls. The serum concentrations of high-sensitivity C-reactive protein (hs-CRP) and a panel of 45 inflammation-related proteins were analyzed using targeted proteomics. A distinguishable serum protein profile was evident in periodontitis cases. The protein pattern could separate cases from controls with a sensitivity of 0.81 and specificity of 0.81 (area under the curve = 0.87). Adjusted levels for hs-CRP and 24 of the 45 proteins were different between cases and controls. High levels of hs-CRP and matrix metalloproteinase-12, and low levels of epidermal growth factor (EGF) and oxidized low-density lipoprotein receptor 1 (OLR-1) were detected among the cases. Furthermore, the levels of C-C motif chemokine-19, granulocyte colony-stimulating factor-3 (CSF-3), interleukin-7 (IL-7), and hs-CRP were significantly higher in cases with a high degree of gingival inflammation. The levels of CSF-3 and tumor necrosis factor ligand superfamily member-10 TNFSF-10 were higher in cases with many deep periodontal pockets. The PerioGene North study includes detailed clinical periodontal data and uncovers a distinct serum protein profile in periodontitis. The findings of lower EGF and OLR-1 among the cases are highlighted, as this has not been presented before. The role of EGF and OLR-1 in periodontitis pathogenesis and as possible future biomarkers should be further explored.

Lectin-type oxidized LDL receptor-1 as a potential therapeutic target for cerebral cavernous malformations treatment

Introduction

Cerebral cavernous malformations (CCMs) are pathologic lesions comprised of clusters of thin-walled capillaries characterized by abnormal proliferation, angiogenesis, and bleeding secondary to somatic or germline mutations in endothelial cells. CCMs can cause headaches, seizures and/or neurological defects. There is a clinical need to develop better tools to detect CCMs and follow their progression in conjunction with the current use of neuroimaging techniques. Here we present data supporting the utility of LOX-1 (lectin-type oxidized LDL receptor 1), a 50 kDa transmembrane protein implicated in endothelial cell dysfunction and ischemia, as a putative biomarker for CCM.

Methods

CCM urine samples (n = 23) were collected from pediatric CCM patients. Matched healthy controls (n = 24) were collected from pediatric patients with either Chiari I malformation or fatty filum terminale, and otherwise normal findings. All samples were collected with patient/family consent and institutional review board approval.Samples were analyzed with Olink Proteomic Proximity Extension Assay (PEA). Differences in expression for 2,925 unique proteins were quantified between healthy control urine samples and CCM urine samples. The results were normalized, validated, and analyzed for demographic bias. In addition to urine samples, CCM tissue from patients was harvested and used to create primary cell lines for in vitro analysis of LOX-1 expression, in addition to immunofluorescence of lesional tissue excised at surgery.

Results

ANOVA analysis of the CCM urine samples showed a statistically significant increase in LOX-1 compared to the control samples, with CCM patients exhibiting a > 5-fold increase in urinary expression. Corroborating these elevated levels of circulating marker, analysis of source tissue from surgically resected CCMs revealed that LOX-1 is increased in both CCM patient cavernoma primary cell lines and operative specimens.

Conclusion

LOX-1 is involved with pathways implicated in CCM pathogenesis and our data here reveals that LOX-1 expression is significantly elevated in CCM patients as compared to matched healthy control individuals, including both source tissue from surgically excised CCMs and in analysis of samples collected from outside of the central nervous system, particularly urine. This proof-of-principle data suggests that LOX-1 may have potential utility as a target for CCM treatment and supports further investigation related to its potential mechanistic impact on CCM pathogenesis.

Dysregulated lipid metabolism and intervertebral disc degeneration: the important role of ox-LDL/LOX-1 in endplate chondrocyte senescence and calcification

BACKGROUND

Lipid metabolism disorders are associated with degeneration of multiple tissues and organs, but the mechanism of crosstalk between lipid metabolism disorder and intervertebral disc degeneration (IDD) has not been fully elucidated. In this study we aim to investigate the regulatory mechanism of abnormal signal of lipid metabolism disorder on intervertebral disc endplate chondrocyte (EPC) senescence and calcification.

METHODS

Human intervertebral disc cartilage endplate tissue, cell model and rat hyperlipemia model were performed in this study. Histology and immunohistochemistry were used to human EPC tissue detection. TMT-labelled quantitative proteomics was used to detect differential proteins, and MRI, micro-CT, safranin green staining and immunofluorescence were performed to observe the morphology and degeneration of rat tail intervertebral discs. Flow cytometry, senescence-associated β-galactosidase staining, alizarin red staining, alkaline phosphatase staining, DCFH-DA fluorescent probe, and western blot were performed to detect the expression of EPC cell senescence, senescence-associated secretory phenotype, calcification-related proteins and the activation of cell senescence-related signaling pathways.

RESULTS

Our study found that the highly expressed oxidized low-density lipoprotein (ox-LDL) and Lectin-like oxidized low-density lipoprotein receptor 1 (LOX-1) in human degenerative EPC was associated with hyperlipidemia (HLP). TMT-labelled quantitative proteomics revealed enriched pathways such as cell cycle regulation, endochondral bone morphogenesis and inflammation. The rat model revealed that HLP could induce ox-LDL, LOX-1, senescence and calcification markers high expression in EPC. Moreover, we demonstrated that ox-LDL-induced EPCs senescence and calcification were dependent on the LOX-1 receptor, and the ROS/P38-MAPK/NF-κB signaling pathway was implicated in the regulation of senescence induced by ox-LDL/LOX-1 in cell model.

CONCLUSIONS

So our study revealed that ox-LDL/LOX-1-induced EPCs senescence and calcification through ROS/P38-MAPK/NF-κB signaling pathway, providing information on understanding the link between lipid metabolism disorders and IDD.

LOX-1 in Cardiovascular Disease: A Comprehensive Molecular and Clinical Review

LOX-1, ORL-1, or lectin-like oxidized low-density lipoprotein receptor 1 is a transmembrane glycoprotein that binds and internalizes ox-LDL in foam cells. LOX-1 is the main receptor for oxidized low-density lipoproteins (ox-LDL). The LDL comes from food intake and circulates through the bloodstream. LOX-1 belongs to scavenger receptors (SR), which are associated with various cardiovascular diseases. The most important and severe of these is the formation of atherosclerotic plaques in the intimal layer of the endothelium. These plaques can evolve into complicated thrombi with the participation of fibroblasts, activated platelets, apoptotic muscle cells, and macrophages transformed into foam cells. This process causes changes in vascular endothelial homeostasis, leading to partial or total obstruction in the lumen of blood vessels. This obstruction can result in oxygen deprivation to the heart. Recently, LOX-1 has been involved in other pathologies, such as obesity and diabetes mellitus. However, the development of atherosclerosis has been the most relevant due to its relationship with cerebrovascular accidents and heart attacks. In this review, we will summarize findings related to the physiologic and pathophysiological processes of LOX-1 to support the detection, diagnosis, and prevention of those diseases.

Radical Oxygen Species, Oxidized Low-Density Lipoproteins, and Lectin-like Oxidized Low-Density Lipoprotein Receptor 1: A Vicious Circle in Atherosclerotic Process

Atherosclerosis is a complex condition that involves the accumulation of lipids and subsequent plaque formation in the arterial intima. There are various stimuli, cellular receptors, and pathways involved in this process, but oxidative modifications of low-density lipoprotein (ox-LDL) are particularly important in the onset and progression of atherosclerosis. Ox-LDLs promote foam-cell formation, activate proinflammatory pathways, and induce smooth-muscle-cell migration, apoptosis, and cell death. One of the major receptors for ox-LDL is LOX-1, which is upregulated in several cardiovascular diseases, including atherosclerosis. LOX-1 activation in endothelial cells promotes endothelial dysfunction and induces pro-atherogenic signaling, leading to plaque formation. The binding of ox-LDLs to LOX-1 increases the generation of reactive oxygen species (ROS), which can induce LOX-1 expression and oxidize LDLs, contributing to ox-LDL generation and further upregulating LOX-1 expression. This creates a vicious circle that is amplified in pathological conditions characterized by high plasma levels of LDLs. Although LOX-1 has harmful effects, the clinical significance of inhibiting this protein remains unclear. Further studies both in vitro and in vivo are needed to determine whether LOX-1 inhibition could be a potential therapeutic target to counteract the atherosclerotic process.

A novel rabbit model of atherosclerotic vulnerable plaque established by cryofluid-induced endothelial injury

Acute thrombosis secondary to atherosclerotic plaque rupture is the main cause of acute cardiac and cerebral ischemia. An animal model of unstable atherosclerotic plaques is highly important for investigating the mechanism of plaque rupture and thrombosis. However, current animal models involve complex operations, are costly, and have plaque morphologies that are different from those of humans. We aimed to establish a simple animal model of vulnerable plaques similar to those of humans. Rabbits were randomly divided into three groups. Group A was given a normal formula diet for 13 weeks. Group C underwent surgery on the intima of the right carotid artery with - 80 °C cryofluid-induced injury after 1 week of a high-fat diet and further feeding a 12-week high-fat diet. Group B underwent the same procedure as Group C but without the - 80 °C cryofluid. Serum lipid levels were detected via ELISA. The plaque morphology, stability and degree of stenosis were evaluated through hematoxylin-eosin (HE) staining, Masson trichrome staining, Elastica van Gieson staining (EVG), and oil red O staining. Macrophages and inflammatory factors in the plaques were assessed via immunohistochemical analysis. The serum low-density lipoprotein cholesterol (LDL-C), triglyceride (TG), and total cholesterol (TC) levels in groups B and C were significantly greater than those in group A. No plaque formation was observed in group A. The plaques in group B were very small. In group C, obvious plaques were observed in the blood vessels, and the plaques exhibited a thin fibrous cap, a large lipid core, and partially visible neovascularization, which is consistent with the characteristics of vulnerable plaques. In the plaques of group C, a large number of macrophages were present, and matrix metalloproteinase 9 (MMP-9) and lectin-like oxidized LDL receptor 1 (LOX-1) were abundantly expressed. We successfully established a rabbit model of vulnerable carotid plaque similar to that of humans through the combination of cryofluid-induced endothelial injury and a high-fat diet, which is feasible and cost effective.

LOX-1 and MMP-9 Inhibition Attenuates the Detrimental Effects of Delayed rt-PA Therapy and Improves Outcomes After Acute Ischemic Stroke

BACKGROUND

Acute ischemic stroke triggers endothelial activation that disrupts vascular integrity and increases hemorrhagic transformation leading to worsened stroke outcomes. rt-PA (recombinant tissue-type plasminogen activator) is an effective treatment; however, its use is limited due to a restricted time window and hemorrhagic transformation risk, which in part may involve activation of MMPs (matrix metalloproteinases) mediated through LOX-1 (lectin-like oxLDL [oxidized low-density lipoprotein] receptor 1). This study's overall aim was to evaluate the therapeutic potential of novel MMP-9 (matrix metalloproteinase 9) ± LOX-1 inhibitors in combination with rt-PA to improve stroke outcomes.

METHODS

A rat thromboembolic stroke model was utilized to investigate the impact of rt-PA delivered 4 hours poststroke onset as well as selective MMP-9 (JNJ0966) ±LOX-1 (BI-0115) inhibitors given before rt-PA administration. Infarct size, perfusion, and hemorrhagic transformation were evaluated by 9.4-T magnetic resonance imaging, vascular and parenchymal MMP-9 activity via zymography, and neurological function was assessed using sensorimotor function testing. Human brain microvascular endothelial cells were exposed to hypoxia plus glucose deprivation/reperfusion (hypoxia plus glucose deprivation 3 hours/R 24 hours) and treated with ±tPA and ±MMP-9 ±LOX-1 inhibitors. Barrier function was assessed via transendothelial electrical resistance, MMP-9 activity was determined with zymography, and LOX-1 and barrier gene expression/levels were measured using qRT-PCR (quantitative reverse transcription PCR) and Western blot.

RESULTS

Stroke and subsequent rt-PA treatment increased edema, hemorrhage, MMP-9 activity, LOX-1 expression, and worsened neurological outcomes. LOX-1 inhibition improved neurological function, reduced edema, and improved endothelial barrier integrity. Elevated MMP-9 activity correlated with increased edema, infarct volume, and decreased neurological function. MMP-9 inhibition reduced MMP-9 activity and LOX-1 expression. In human brain microvascular endothelial cells, LOX-1/MMP-9 inhibition differentially attenuated MMP-9 levels, inflammation, and activation following hypoxia plus glucose deprivation/R.

CONCLUSIONS

Our findings indicate that LOX-1 inhibition and ± MMP-9 inhibition attenuate negative aspects of ischemic stroke with rt-PA therapy, thus resulting in improved neurological function. While no synergistic effect was observed with simultaneous LOX-1 and MMP-9 inhibition, a distinct interaction is evident.

Atherosclerosis and Toll-Like Receptor4 (TLR4), Lectin-Like Oxidized Low-Density Lipoprotein-1 (LOX-1), and Proprotein Convertase Subtilisin/Kexin Type9 (PCSK9)

Atherosclerosis is a leading cause of death in the world. A significant body of evidence suggests that inflammation and various players are implicated and have pivotal roles in the formation of atherosclerotic plaques. Toll-like receptor 4 (TLR4) is linked with different stages of atherosclerosis. This receptor is highly expressed in the endothelial cells (ECs) and atherosclerotic plaques. TLR4 activation can lead to the production of inflammatory cytokines and related responses. Lectin-like oxidized low-density lipoprotein-1 (LOX-1), an integral membrane glycoprotein with widespread expression on the ECs, is involved in atherosclerosis and has some common pathways with TLR4 in atherosclerotic lesions. In addition, proprotein convertase subtilisin/kexin type9 (PCSK9), which is a regulatory enzyme with different roles in cholesterol uptake, is implicated in atherosclerosis. At present, TLR4, PCSK9, and LOX-1 are increasingly acknowledged as key players in the pathogenesis of atherosclerotic cardiovascular diseases. Herein, we presented the current evidence on the structure, functions, and roles of TLR4, PCSK9, and LOX-1 in atherosclerosis.

Role of Lectin-Like Oxidized Low-Density Lipoprotein Receptor-1 in Inflammation and Pathogen-Associated Interactions

BACKGROUND

Lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) is known as a major receptor for oxidized low-density lipoproteins (oxLDL) and plays a significant role in the genesis of atherosclerosis. Recent research has shown its involvement in cancer, ischemic stroke, and diabetes. LOX-1 is a C-type lectin receptor and is involved in the activation of immune cells and inflammatory processes. It may further interact with pathogens, suggesting a role in infections or the host's response.

SUMMARY

This review compiles the current knowledge of potential implications of LOX-1 in inflammatory processes and in host-pathogen interactions with a particular emphasis on its regulatory role in immune responses. Also discussed are genomic and structural variations found in LOX-1 homologs across different species as well as potential involvements of LOX-1 in inflammatory processes from the angle of different cell types and organ-specific interactions.

KEY MESSAGES

The results presented reveal both similar and different structures in human and murine LOX-1 and provide clues as to the possible origins of different modes of interaction. These descriptions raise concerns about the suitability, particularly of mouse models, that are often used in the analysis of its functionality in humans. Further research should also aim to better understand the mostly unknown binding and interaction mechanisms between LOX-1 and different pathogens. This pursuit will not only enhance our understanding of LOX-1 involvement in inflammatory processes but also identify potential targets for immunomodulatory approaches.

Elevated soluble LOX-1 predicts risk of first-time myocardial infarction

BACKGROUND

There is an unmet clinical need for novel therapies addressing the residual risk in patients receiving guideline preventive therapy for coronary heart disease. Experimental studies have identified a pro-atherogenic role of the oxidized LDL receptor LOX-1. We investigated the association between circulating soluble LOX-1 (sLOX-1) and the risk for development of myocardial infarction.

METHODS

The study subjects (n = 4658) were part of the Malmö Diet and Cancer study. The baseline investigation was carried out 1991-1994 and the incidence of cardiovascular events monitored through national registers during a of 19.5 ± 4.9 years follow-up. sLOX-1 and other biomarkers were analyzed by proximity extension assay and ELISA in baseline plasma.

RESULTS

Subjects in the highest tertile of sLOX-1 had an increased risk of myocardial infarction (hazard ratio (95% CI) 1.76 (1.40-2.21) as compared with those in the lowest tertile. The presence of cardiovascular risk factors was related to elevated sLOX-1, but the association between sLOX-1 and risk of myocardial infarction remained significant when adjusting for risk factors.

CONCLUSIONS

In this prospective population study we found an association between elevated sLOX-1, the presence of carotid disease and the risk for first-time myocardial infarction. Taken together with previous experimental findings of a pro-atherogenic role of LOX-1, this observation supports LOX-1 inhibition as a possible target for prevention of myocardial infarction.

Clinical Utility of Soluble Lectin Type Oxidized Low-Density Lipoprotein Receptor as a Biomarker for Myocardial Infarction and Stable Angina

Background and objectives Endothelial soluble lectin-type oxidized low-density lipoprotein receptor 1 (sLOX-1) recognizes oxidized low-density lipoprotein (LDL) and triggers downstream signaling leading to atherosclerosis. The objective of this study was to demonstrate the utility of sLOX-1 as a biomarker for detecting acute myocardial infarction (MI) and stable angina (SA) and to develop a diagnostic algorithm for distinguishing coronary vasospasm from coronary plaque rupture. Methods We enrolled 62 patients who underwent diagnostic coronary angiography (CAG) and 30 healthy controls (21 men and nine women) and measured sLOX-1, troponin I, and cardiac myosin-binding protein C (c-MyBPC) using commercial kits. Results Patients with MI exhibited higher sLOX-1 levels (301.55 ± 196.16 pg/ml) than patients with stable angina (220.76 ± 103.65 pg/ml) and healthy controls (121.14 ± 77.10, F: 10.55, p<0.001). Although higher troponin I levels were detected in MI patients (263.00 ± 493.00 vs. 3.19 ± 2.15 ng/ml, p=0.0019), no significant elevation was observed in SA patients (1.91 ± 0.79 ng/ml). Plasma sLOX-1 levels showed a positive association with age (r=0.37, p=0.003), but not with gender (r=0.04, p=0.75). Troponin I showed no association with age (r=0.12, p=0.36) or gender (r=0.06, p=0.62). Receiver operating characteristic (ROC) curves revealed that among the three biomarkers, troponin-I showed a higher area under the curve (AUC) (AUC: 0.941), followed by sLOX-1 (AUC: 0.888), while c-MyBPC showed no clinical utility in the detection of MI (AUC: 0.666). Conclusions A marked elevation of sLOX-1 can detect MI and differentiate the presence or absence of plaque rupture, along with diagnosing stable angina.

Relationship of Soluble Lectin-Like Low-Density Lipoprotein Receptor-1 (sLOX-1) With Inflammation and Coronary Plaque Progression in Psoriasis

BACKGROUND

Psoriasis is a chronic inflammatory condition associated with coronary artery disease risk. Uptake of oxidized low-density lipoprotein by the lectin-like low-density lipoprotein receptor-1 triggers release of the soluble extracellular domain of the receptor (sLOX-1). We sought to characterize the relationship between sLOX-1, inflammation, and coronary plaque progression in psoriasis.

METHODS AND RESULTS

A total of 327 patients with psoriasis had serum sLOX-1 levels measured at baseline by an ELISA-based assay. Stratification by high-sensitivity C-reactive protein ≥4.0 mg/L (quartile 4), identified 81 participants who had coronary plaque phenotyping at baseline and were followed longitudinally by coronary computed tomography angiography. Subjects within high-sensitivity C-reactive protein quartile 4 were middle-aged (51.47±12.62 years), predominantly men (54.3%) with moderate psoriasis disease severity (6.60 [interquartile range, 3.30-13.40]). In the study cohort, participants with sLOX-1 above the median displayed increased vulnerable coronary plaque features. At baseline, sLOX-1 was associated with total burden (rho=0.296; P=0.01), noncalcified burden (rho=0.286; P=0.02), fibro-fatty burden (rho=0.346; P=0.004), and necrotic burden (rho=0.394; P=0.002). A strong relationship between sLOX-1, noncalcified burden (β=0.19; P=0.03), and fibro-fatty burden (β=0.29; P=0.003) was found in fully adjusted models at baseline and 1- and 4-year follow-up. Finally, coronary plaque features progressed over 1 year regardless of biologic or systemic treatment in subjects with high sLOX-1.

CONCLUSIONS

Patients with psoriasis with both high sLOX-1 and high-sensitivity C-reactive protein levels have increased coronary plaque burden associated with atherosclerotic plaque progression independent of biologic and systemic treatment. Thus, sLOX-1 might be considered as a promising marker in coronary artery disease risk estimation beyond traditional risk factors.

REGISTRATION

URL: https://www.clinicaltrials.gov; Unique identifier: NCT01778569.

Wall Teichoic Acid Mediates Staphylococcus aureus Binding to Endothelial Cells via the Scavenger Receptor LOX-1

The success of Staphylococcus aureus as a major cause for endovascular infections depends on effective interactions with blood-vessel walls. We have previously shown that S. aureus uses its wall teichoic acid (WTA), a surface glycopolymer, to attach to endothelial cells. However, the endothelial WTA receptor remained unknown. We show here that the endothelial oxidized low-density lipoprotein receptor 1 (LOX-1) interacts with S. aureus WTA and permits effective binding of S. aureus to human endothelial cells. Purified LOX-1 bound to isolated S. aureus WTA. Ectopic LOX-1 expression led to increased binding of S. aureus wild type but not of a WTA-deficient mutant to a cell line, and LOX-1 blockage prevented S. aureus binding to endothelial cells. Moreover, WTA and LOX-1 expression levels correlated with the efficacy of the S. aureus-endothelial interaction. Thus, LOX-1 is an endothelial ligand for S. aureus, whose blockage may help to prevent or treat severe endovascular infections.

Receptor basis of biological activity of polysaccharides

Polysaccharides, the most diverse forms of organic molecules in nature, exhibit a large number of different biological activities, such as immunomodulatory, radioprotective, antioxidant, regenerative, metabolic, signaling, antitumor, and anticoagulant. The reaction of cells to a polysaccharide is determined by its specific interaction with receptors present on the cell surface, the type of cells, and their condition. The effect of many polysaccharides depends non-linearly on their concentration. The same polysaccharide in different conditions can have very different effects on cells and organisms, up to the opposite; therefore, when conducting studies of the biological activity of polysaccharides, both for the purpose of developing new drugs or approaches to the treatment of patients, and in order to clarify the features of intracellular processes, information about already known research results is needed. There is a lot of scattered data on the biological activities of polysaccharides, but there are few reviews that would consider natural polysaccharides from various sources and possible molecular mechanisms of their action. The purpose of this review is to present the main results published at different times in order to facilitate the search for information necessary for conducting relevant studies.

Mechanism of the antidiabetic action of Nigella sativa and Thymoquinone: a review

Introduction

Long used in traditional medicine, Nigella sativa (NS; Ranunculaceae) has shown significant efficacy as an adjuvant therapy for diabetes mellitus (DM) management by improving glucose tolerance, decreasing hepatic gluconeogenesis, normalizing blood sugar and lipid imbalance, and stimulating insulin secretion from pancreatic cells. In this review, the pharmacological and pharmacokinetic properties of NS as a herbal diabetes medication are examined in depth, demonstrating how it counteracts oxidative stress and the onset and progression of DM.

Methods

This literature review drew on databases such as Google Scholar and PubMed and various gray literature sources using search terms like the etiology of diabetes, conventional versus herbal therapy, subclinical pharmacology, pharmacokinetics, physiology, behavior, and clinical outcomes.

Results

The efficiency and safety of NS in diabetes, notably its thymoquinone (TQ) rich volatile oil, have drawn great attention from researchers in recent years; the specific therapeutic dose has eluded determination so far. TQ has anti-diabetic, anti-inflammatory, antioxidant, and immunomodulatory properties but has not proved druggable. DM's intimate link with oxidative stress, makes NS therapy relevant since it is a potent antioxidant that energizes the cell's endogenous arsenal of antioxidant enzymes. NS attenuates insulin resistance, enhances insulin signaling, suppresses cyclooxygenase-2, upregulates insulin-like growth factor-1, and prevents endothelial dysfunction in DM.

Conclusion

The interaction of NS with mainstream drugs, gut microbiota, and probiotics opens new possibilities for innovative therapies. Despite its strong potential to treat DM, NS and TQ must be examined in more inclusive clinical studies targeting underrepresented patient populations.

The metabolic and functional roles of sensory nerves in adipose tissues

Homeostatic regulation of adipose tissue is critical for the maintenance of energy balance and whole-body metabolism. The peripheral nervous system provides bidirectional neural communication between the brain and adipose tissue, thereby providing homeostatic control. Most research on adipose innervation and nerve functions has been limited to the sympathetic nerves and their neurotransmitter norepinephrine. In recent years, more work has focused on adipose sensory nerves, but the contributions of subsets of sensory nerves to metabolism and the specific roles contributed by sensory neuropeptides are still understudied. Advances in imaging of adipose innervation and newer tissue denervation techniques have confirmed that sensory nerves contribute to the regulation of adipose functions, including lipolysis and browning. Here, we summarize the historical and latest findings on the regulation, function and plasticity of adipose tissue sensory nerves that contribute to metabolically important processes such as lipolysis, vascular control and sympathetic axis cross-talk.

Urinary cytokine measurements do not reflect surgery-induced inflammation in rhesus macaques

Measurement of the health and disease status of free-ranging primates is often limited by a lack of available biomarkers of immune activation and inflammation that can be applied noninvasively via the measurement of urine or fecal samples. Here, we evaluate the potential usefulness of noninvasive urinary measurements of a number of cytokines, chemokines, and other markers of inflammation and infection. We took advantage of surgery-associated inflammation in seven captive rhesus macaques, collecting urine samples before and after the medical interventions. We measured these urine samples for 33 different markers of inflammation and immune activation that are known to be responsive to inflammation and infection in rhesus macaque blood samples, via the Luminex platform. We also measured all samples for concentrations of the soluble urokinase plasminogen activator receptor (suPAR), which we had validated in a prior study as an effective biomarker of inflammation. Despite urine samples being collected in captivity under ideal conditions (clean, no contamination with feces or soil, frozen quickly), 13/33 biomarkers measured via Luminex were found at concentrations below detection limits in >50% of samples. Of the remaining 20 markers, only 2 showed significant increases in response to surgery-IL18 and MPO (myeloperoxidase). However, suPAR measurements of the same samples show a consistent marked increase in response to surgery that is absent from the patterns of IL18 and MPO measurement. Given that our samples were collected under conditions that are greatly preferable to those usually encountered in the field, urinary cytokine measurements via the Luminex platform seem overall unpromising for primate field studies.

Associations of Tissue and Soluble LOX-1 with Human Abdominal Aortic Aneurysm

Background Indication for prophylactic surgical abdominal aortic aneurysm (AAA) repair depends on the maximal aortic diameter. The lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) is the major receptor for uptake of oxidized low-density lipoprotein cholesterol and is implicated in atherosclerosis. A soluble form of LOX-1 (sLOX-1) has been discussed as a novel biomarker in coronary artery disease and stroke. Herein, we assessed the regulation of aortic LOX-1 as well as the diagnostic and risk stratification potential of sLOX-1 in patients with AAA. Methods and Results Serum sLOX-1 was assessed in a case-control study in AAA (n=104) and peripheral artery disease (n=104). sLOX-1 was not statistically different between AAA and peripheral artery disease but was higher in AAA (β=1.28, P=0.04) after adjusting for age, atherosclerosis, type 2 diabetes, prescription of statins, β-blockers, ACE inhibitors, and therapeutic anticoagulation. sLOX-1 was not associated with the aortic diameter, AAA volume, or the thickness of the intraluminal thrombus. Aortic LOX-1 mRNA expression tended to be higher in AAA when compared with disease, and expression was positively associated with cleaved caspase-3, smooth muscle actin, collagen, and macrophage content. Conclusions In AAA, sLOX-1 was differently affected by age, cardiometabolic diseases, and corresponding medical therapies. Comparison with nonatherosclerotic disease would be beneficial to further elucidate the diagnostic potential of sLOX-1, although it was not useful for risk stratification. Aneurysmal LOX-1 mRNA expression was increased and positively associated with smooth muscle cells and collagen content, suggesting that LOX-1 is eventually not deleterious in human AAA and could counteract AAA rupture.

Short and long-term associations between serum proteins linked to cardiovascular disease and particle exposure among constructions workers

OBJECTIVES

Construction workers are exposed to respirable dust, including respirable crystalline silica (RCS), which is a potential risk factor for cardiovascular disease (CVD). The aim of this study was to evaluate whether exposure to particles among construction workers is associated with short- and long-term alterations in CVD-related serum proteins.

METHODS

Using proximity extension assay, we measured 92 serum proteins linked to CVD among active male construction workers (N=65, non-smokers) sampled on two occasions: during work and after vacation. First, we used linear models to identify short-term changes in proteins associated with particle exposure (assessed as respirable dust and RCS) during work. Secondly, we used linear mixed models to evaluate whether these associations were long-term, ie, persistent after vacation.

RESULTS

The median exposure to respirable dust and RCS during work were 0.25 mg/m3 and 0.01 mg/m3, respectively. Respirable dust was associated with short-term changes in six proteins (tissue factor, growth hormone, heme oxygenase-1, dickkopf-related protein-1, platelet-derived growth factor-B, stem cell factor); long-term associations were observed for the former three proteins. RCS was associated with short-term changes in five proteins (carcinoembryonic antigen-related cell adhesion molecule-8, hydroxyacid oxidase-1, tissue factor, carbonic anhydrase-5A, lectin-like oxidized LDL receptor-1); long-term associations were observed for the former four proteins.

CONCLUSIONS

Moderate exposure to particles in the construction industry is associated with both short- and long-term changes in circulating CVD-related proteins. Further studies are needed to evaluate if these changes are predictors of occupationally induced clinical CVD.

Lectin-Like Oxidized Low-Density Lipoprotein Receptor 1 Inhibition in Type 2 Diabetes: Phase 1 Results

Background Blockade of the lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) is a potentially attractive mechanism for lowering inflammatory and lipid risk in patients with atherosclerosis. This study aims to assess the safety, tolerability, and target engagement of MEDI6570, a high-affinity monoclonal blocking antibody to LOX-1. Methods and Results This phase 1, first-in-human, placebo-controlled study (NCT03654313) randomized 88 patients with type 2 diabetes to receive single ascending doses (10, 30, 90, 250, or 500 mg) or multiple ascending doses (90, 150, or 250 mg once monthly for 3 months) of MEDI6570 or placebo. Primary end point was safety; secondary and exploratory end points included pharmacokinetics, immunogenicity, free soluble LOX-1 levels, and change in coronary plaque volume. Mean age was 57.6/58.1 years in the single ascending doses/multiple ascending doses groups, 31.3%/62.5% were female, and mean type 2 diabetes duration was 9.7/8.7 years. Incidence of adverse events was similar among cohorts. MEDI6570 exhibited nonlinear pharmacokinetics, with terminal half-life increasing from 4.6 days (30 mg) to 11.2 days (500 mg), consistent with target-mediated drug disposition. Dose-dependent reductions in mean soluble LOX-1 levels from baseline were observed (>66% at 4 weeks and 71.61-82.96% at 10 weeks in the single ascending doses and multiple ascending doses groups, respectively). After 3 doses, MEDI6570 was associated with nonsignificant regression of noncalcified plaque volume versus placebo (-13.45 mm3 versus -8.25 mm3). Conclusions MEDI6570 was well tolerated and demonstrated dose-dependent soluble LOX-1 suppression and a pharmacokinetic profile consistent with once-monthly dosing. Registration URL: https://clinicaltrials.gov/; Unique identifier: NCT03654313.

High Plasma Levels of Soluble Lectin-like Oxidized Low-Density Lipoprotein Receptor-1 Are Associated With Inflammation and Cardiometabolic Risk Profiles in Pediatric Overweight and Obesity

Background Lectin-like oxidized low-density lipoprotein (ox-LDL) receptor-1 is a scavenger receptor for oxidized low-density lipoprotein. In adults, higher soluble lectin-like ox-LDL receptor-1 (sLOX-1) levels are associated with cardiovascular disease, type 2 diabetes, and obesity, but a similar link in pediatric overweight/obesity remains uncertain. Methods and Results Analyses were based on the cross-sectional HOLBAEK Study, including 4- to 19-year-olds from an obesity clinic group with body mass index >90th percentile (n=1815) and from a population-based group (n=2039). Fasting plasma levels of sLOX-1 and inflammatory markers were quantified, cardiometabolic risk profiles were assessed, and linear and logistic regression analyses were performed. Pubertal/postpubertal children and adolescents from the obesity clinic group exhibited higher sLOX-1 levels compared with the population (P<0.001). sLOX-1 positively associated with proinflammatory cytokines, matrix metalloproteinases, body mass index SD score, waist SD score, body fat %, plasma alanine aminotransferase, serum high-sensitivity C-reactive protein, plasma low-density lipoprotein cholesterol, triglycerides, systolic and diastolic blood pressure SD score, and inversely associated with plasma high-density lipoprotein cholesterol (all P<0.05). sLOX-1 positively associated with high alanine aminotransferase (odds ratio [OR], 1.16, P=4.1 E-04), insulin resistance (OR, 1.16, P=8.6 E-04), dyslipidemia (OR, 1.25, P=1.8 E-07), and hypertension (OR, 1.12, P=0.02). Conclusions sLOX-1 levels were elevated during and after puberty in children and adolescents with overweight/obesity compared with population-based peers and associated with inflammatory markers and worsened cardiometabolic risk profiles. sLOX-1 may serve as an early marker of cardiometabolic risk and inflammation in pediatric overweight/obesity. Registration The HOLBAEK Study, formerly known as The Danish Childhood Obesity Biobank, ClinicalTrials.gov identifier number NCT00928473, https://clinicaltrials.gov/ct2/show/NCT00928473 (registered June 2009).

Oxidized low-density lipoprotein associates with cardiovascular disease by a vicious cycle of atherosclerosis and inflammation: A systematic review and meta-analysis

Background

Low-density lipoprotein cholesterol (LDL-C) is an established marker for cardiovascular disease (CVD) and a therapeutic target. Oxidized LDL (oxLDL) is known to be associated with excessive inflammation and abnormal lipoprotein metabolism. Chronic inflammatory diseases confer an elevated risk of premature atherosclerosis and adverse cardiovascular events. Whether oxLDL may serve as a potential biomarker for CVD stratification in populations with chronic inflammatory conditions remains understudied.

Objective

To perform a systematic review and meta-analysis evaluating the relationship between oxLDL and CVD (defined by incident CVD events, carotid intima-media thickness, presence of coronary plaque) in patients with chronic inflammatory diseases.

Methods

A systematic literature search was performed using studies published between 2000 and 2022 from PubMed, Cochrane Library, Embase (Elsevier), CINHAL (EBSCOhost), Scopus (Elsevier), and Web of Science: Core Collection (Clarivate Analytics) databases on the relationship between oxLDL and cardiovascular risk on inflamed population. The pooled effect size was combined using the random effect model and publication bias was assessed if P < 0.05 for the Egger or Begg test along with the funnel plot test.

Results

A total of three observational studies with 1,060 participants were ultimately included in the final meta-analysis. The results demonstrated that oxLDL is significantly increased in participants with CVD in the setting of chronic inflammatory conditions. This meta-analysis suggests that oxLDL may be a useful biomarker in risk stratifying cardiovascular disease in chronically inflamed patients.

Macrophage scavenger receptors: Tumor support and tumor inhibition

Tumor-associated macrophages (TAMs) are a heterogeneous population of myeloid cells that constitute up to 50% of the cell mass of human tumors. TAMs interact with the components of the tumor microenvironment (TME) by using scavenger receptors (SRs), a large superfamily of multifunctional receptors that recognize, internalize and transport to the endosomal/lysosomal pathway apoptotic cells, cytokines, matrix molecules, lipid modified lipoproteins and other unwanted-self ligands. In our review, we summarized state-of-the art for the role of macrophage scavenger receptors in tumor development and their significance as cancer biomarkers. In this review we focused on functional activity of TAM-expressing SRs in animal models and in patients, and summarized the data for different human cancer types about the prognostic significance of TAM-expressed SRs. We discussed the role of SRs in the regulation of cancer cell biology, cell-cell and cell-matrix interaction in TME, immune status in TME, angiogenesis, and intratumoral metabolism. Targeting of tumor-promoting SRs can be a promising therapeutic approach in anti-cancer therapy. In our review we provide evidence for both tumor supporting and tumor inhibiting functions of scavenger receptors expressed on TAMs. We focused on the key differences in the prognostic and functional roles of SRs that are specific for cancer types. We highlighted perspectives for inhibition of tumor-promoting SRs in anti-cancer therapy.

Abacavir causes leukocyte/platelet crosstalk by activating neutrophil P2X7 receptors thus releasing soluble lectin-like oxidized low-density lipoprotein receptor-1

BACKGROUND AND PURPOSE

Abacavir, an antiretroviral drug used in HIV therapy associated with myocardial infarction, promotes thrombosis through P2X7 receptors. The role of platelets as pro-thrombotic cells is acknowledged whereas that of neutrophils-due to their secretory capacity-is gaining recognition. This study analyses the role of neutrophils-specifically the secretome of abacavir-treated neutrophils (SN_ABC )-in platelet activation that precedes thrombosis.

EXPERIMENTAL APPROACH

Effects of abacavir or SN_ABC on platelet activation and platelet-leukocyte interactions and expression of lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) were analysed by flow cytometry. The secretome was analysed by proteomics. The role of leukocytes in the actions of abacavir was evaluated in a mouse model of thrombosis.

KEY RESULTS

Abacavir induced platelet-leukocyte interactions, not directly via effects of abacavir on platelets, but via activation of neutrophils, which triggered interactions between platelet P-selectin and neutrophil P-selectin glycoprotein ligand-1 (PSGL-1). SN_ABC stimulated platelet activation and platelet-leukocyte interactions through a process that was dependent on LOX-1, neutrophil P2X7 and platelet P2Y1, P2Y12 and P2X1 receptors. Abacavir induced the expression of LOX-1 on neutrophils and of the soluble form of LOX-1 (sLOX-1) in SN_ABC . Neutrophils, LOX-1, P2X7, P2Y1, P2Y12 and P2X1 receptors were required for the pro-thrombotic actions of abacavir in vivo.

CONCLUSION AND IMPLICATIONS

Neutrophils are target cells in abacavir-induced thrombosis. Abacavir released sLOX-1 from neutrophils via activation of their P2X7 receptors, which in turn activated platelets. Hence, sLOX-1 could be the missing link in the cardiovascular risk associated with abacavir.

Oxidized High-Density Lipoprotein Induces Endothelial Fibrosis Promoting Hyperpermeability, Hypotension, and Increased Mortality

During systemic inflammation, reactive oxygen species (ROS) are generated in the bloodstream, producing large amounts of oxidized HDL (oxHDL). OxHDL loses the vascular protective features of native HDL, acquiring detrimental actions. Systemic inflammation promotes endothelial fibrosis, characterized by adhesion protein downregulation and fibrotic-specific gene upregulation, disrupting endothelial monolayer integrity. Severe systemic inflammatory conditions, as found in critically ill patients in the intensive care unit (ICU), exhibit endothelial hyperpermeability, hypotension, and organ hypoperfusion, promoting organ dysfunction and increased mortality. Because endothelial fibrosis disturbs the endothelium, it is proposed that it is the cellular and molecular origin of endothelial hyperpermeability and the subsequent deleterious consequences. However, whether oxHDL is involved in this process is unknown. The aim of this study was to investigate the fibrotic effect of oxHDL on the endothelium, to elucidate the underlying molecular and cellular mechanism, and to determine its effects on vascular permeability, blood pressure, and mortality. The results showed that oxHDL induces endothelial fibrosis through the LOX-1/NOX-2/ROS/NF-κB pathway, TGF-β secretion, and ALK-5/Smad activation. OxHDL-treated rats showed endothelial hyperpermeability, hypotension, and an enhanced risk of death and mortality, which was prevented using an ALK-5 inhibitor and antioxidant diet consumption. Additionally, the ICU patients showed fibrotic endothelial cells, and the resuscitation fluid volume administered correlated with the plasma oxHDL levels associated with an elevated risk of death and mortality. We conclude that oxHDL generates endothelial fibrosis, impacting blood pressure regulation and survival.

Decrease of glutathione peroxidase in arrhythmic cardiac pathology in young individuals and its therapeutic implications

Glutathione peroxidase (GPx), as an antioxidant enzyme, is involved in the regulation of processes that cause cellular oxidative stress, with implications in various pathologies. The aim of the present study was to evaluate GPx variations in patients with arrhythmic, non-structural cardiac disorders. The research was performed on 120 patients, with a mean age of 33 years old, divided into 3 equal groups, of which 2 groups included patients with cardiac arrhythmias, the first group, associated with dyslipidemia and the second one, without dyslipidemia, and a control group consisting of healthy individuals. The method for determining GPx was based on the GPx enzyme catalysis reaction of the reduced glutathione (GSH) oxidation reaction by cumene hydroperoxide. The results revealed that GPx variation was decreased in patients with cardiac arrhythmias, with or without dyslipidemia, up to 66 and 74% of mean control values, respectively, the differences being statistically significant, showing the existence of an oxidative stress imbalance, that may be involved in triggering arrhythmogenic electrochemical mechanisms. The GPx deficiency determined in relation to cardiac arrhythmias was in dyslipidemic and non-lipidemic patients as follows: 29-35% in sinus bradycardia, 31-35% in associated cardiac arrhythmias, 30-33% in sinus tachycardia, 27-33% in atrial fibrillation, 32-33% in atrial flutter, 27-32% in atrial extrasystolic arrhythmia, 28-30% in ventricular extrasystolic arrhythmia and 18-26% in paroxysmal supraventricular tachycardia. Collectively, the results revealed that GPx, an antioxidant enzyme, is a specific biomarker, whose decrease indicated the existence of oxidative stress in young individuals with cardiac arrhythmias and its involvement in arrhythmogenic electrochemical processes. In addition, GPx deficiencies were between 18-35% in all types of cardiac arrhythmias, the highest being recorded in sinus bradycardia and the lowest in paroxysmal supraventircular tachycardia. Furthermore, the oxidative stress favored by the decrease of GPx induced lipid oxidation, regardless of the presence or absence of dyslipidemia, which triggered the formation of anti-lipid antibodies and a subclinical endothelial aggression, with early atherosclerotic potential. GPx evaluation may argue for the existence of oxidative stress in non-structural cardiac arrhythmias, and by its proper correction (antioxidants), prophylaxis of atherogenic dysfunction.

Serum cholesterol loading capacity on macrophages is linked to coronary atherosclerosis and cardiovascular event risk in rheumatoid arthritis

Objectives

Cholesterol loading capacity (CLC) describes the ability of serum to deliver cholesterol to cells. It is linked to foam cell formation, a pivotal step in atherosclerotic plaque development. We evaluate the associations of CLC with coronary atherosclerosis presence, burden and cardiovascular risk in patients with rheumatoid arthritis (RA).

Methods

Coronary atherosclerosis (any, high-risk low-attenuation plaque and obstructive plaque) was evaluated with CT angiography in 141 patients. Participants were prospectively followed for 6.0±2.4 years and cardiovascular events including cardiac death, myocardial infarction, unstable angina, stroke, claudication, revascularisation and hospitalised heart failure were recorded. CLC was quantified as intracellular cholesterol in human macrophages after incubation with patient serum.

Results

CLC was not linked to overall plaque presence or burden after adjustments for atherosclerotic cardiovascular disease (ASCVD) score, statin use and low-density lipoprotein cholesterol. However, CLC associated with presence and numbers of any, low-attenuation and obstructive plaques exclusively in biologic disease-modifying antirheumatic drugs (bDMARD) non-users (p for interaction ≤0.018). CLC associated with cardiovascular event risk overall after adjustments for ASCVD and number of segments with plaque (HR=1.76 (95% CI 1.16 to 2.67) per 1 SD increase in CLC, p=0.008). Additionally, bDMARD use modified the impact of CLC on event risk; CLC associated with events in bDMARD non-users (HR=2.52 (95% CI 1.36 to 4.65) per 1SD increase in CLC, p=0.003) but not users.

Conclusion

CLC was linked to long-term cardiovascular event risk in RA and associated with high-risk low attenuation and obstructive coronary plaque presence and burden in bDMARD non-users. Its prospective validation as a predictive biomarker may be, therefore, warranted.

Oxidized low-density lipoprotein receptor 1: a novel potential therapeutic target for intracerebral hemorrhage

Oxidized low-density lipoprotein receptor 1 (OLR1) is upregulated in neurons and participates in hypertension-induced neuronal apoptosis. OLR1 deletion exerts protective effects on cerebral damage induced by hypertensive-induced stroke. Therefore, OLR1 is likely involved in the progress of intracerebral hemorrhage. In this study, we examined the potential role of OLR1 in intracerebral hemorrhage using a rat model. OLR1 small interfering RNA (10 μL; 50 pmol/μL) was injected into the right basal ganglia to knock down OLR1. Twenty-four hours later, 0.5 U collagenase type VII was injected to induce intracerebral hemorrhage. We found that knockdown of OLR1 attenuated neurological behavior impairment in rats with intracerebral hemorrhage and reduced hematoma, neuron loss, inflammatory reaction, and oxidative stress in rat brain tissue. We also found that silencing of OLR1 suppressed ferroptosis induced by intracerebral hemorrhage and the p38 signaling pathway. Therefore, silencing OLR1 exhibits protective effects against secondary injury of intracerebral hemorrhage. These findings suggest that OLR1 may be a novel potential therapeutic target for intracerebral hemorrhage.

Gold Nanorods Induce Endoplasmic Reticulum Stress and Autocrine Inflammatory Activation in Human Neutrophils

Gold nanorods (AuNRs) are promising agents for diverse biomedical applications such as drug and gene delivery, bioimaging, and cancer treatment. Upon in vivo application, AuNRs quickly interact with cells of the immune system. On the basis of their strong intrinsic phagocytic activity, polymorphonuclear neutrophils (PMNs) are specifically equipped for the uptake of particulate materials such as AuNRs. Therefore, understanding the interaction of AuNRs with PMNs is key for the development of safe and efficient therapeutic applications. In this study, we investigated the uptake, intracellular processing, and cell biological response induced by AuNRs in PMNs. We show that uptake of AuNRs mainly occurs via phagocytosis and macropinocytosis with rapid deposition of AuNRs in endosomes within 5 min. Within 60 min, AuNR uptake induced an unfolded protein response (UPR) along with induction of inositol-requiring enzyme 1 α (IREα) and features of endoplasmic reticulum (ER) stress. This early response was followed by a pro-inflammatory autocrine activation loop that involves LOX1 upregulation on the cell surface and increased secretion of IL8 and MMP9. Our study provides comprehensive mechanistic insight into the interaction of AuNRs with immune cells and suggests potential targets to limit the unwanted immunopathological activation of PMNs during application of AuNRs.

Loxin Reduced the Inflammatory Response in the Liver and the Aortic Fatty Streak Formation in Mice Fed with a High-Fat Diet

Oxidized low-density lipoprotein (ox-LDL) is the most harmful form of cholesterol associated with vascular atherosclerosis and hepatic injury, mainly due to inflammatory cell infiltration and subsequent severe tissue injury. Lox-1 is the central ox-LDL receptor expressed in endothelial and immune cells, its activation regulating inflammatory cytokines and chemotactic factor secretion. Recently, a Lox-1 truncated protein isoform lacking the ox-LDL binding domain named LOXIN has been described. We have previously shown that LOXIN overexpression blocked Lox-1-mediated ox-LDL internalization in human endothelial progenitor cells in vitro. However, the functional role of LOXIN in targeting inflammation or tissue injury in vivo remains unknown. In this study, we investigate whether LOXIN modulated the expression of Lox-1 and reduced the inflammatory response in a high-fat-diet mice model. Results indicate that human LOXIN blocks Lox-1 mediated uptake of ox-LDL in H4-II-E-C3 cells. Furthermore, in vivo experiments showed that overexpression of LOXIN reduced both fatty streak lesions in the aorta and inflammation and fibrosis in the liver. These findings were associated with the down-regulation of Lox-1 in endothelial cells. Then, LOXIN prevents hepatic and aortic tissue damage in vivo associated with reduced Lox-1 expression in endothelial cells. We encourage future research to understand better the underlying molecular mechanisms and potential therapeutic use of LOXIN.

How Diabetes and Other Comorbidities of Elderly Patients and Their Treatment Influence Levels of Glycation Products

Medical care for geriatric patients is a great challenge, mainly due to various overlapping deficits relevant to numerous coexisting diseases, of which the most common are diabetes mellitus and atherosclerosis. In the case of diabetes, the glycation process is intensified, which accelerates atherosclerosis development and diabetic complications. Our goal was to investigate the relationship between the classical biochemical parameters of diabetes and atherosclerosis, as well as parameters which may indicate a nephropathy, and the parameters strictly related to glycation, taking into account the pharmacological treatment of patients. Methods: We analyzed the patients’ serum concentrations of fluorescent glycation product—pentosidine, concentrations of soluble receptors for advanced glycation products (sRAGE), lipoprotein receptor-1 (LOX-1), galectin 3 (GAL3), scavenger receptor class A (SR-A), and scavenger receptor class B (SR-BI), as well as the level of lipid peroxidation and free amine content. Among the identified correlations, the most interesting are the following: sRAGE with triglycerides (r = 0.47, p = 0.009), sRAGE with SR-BI (r = 0.47, p = 0.013), SR-BI with LOX-1 (r = 0.31, p = 0.013), and SR-BI with HDL (r = −0.30, p = 0.02). It has been shown that pentosidine and reactive free amine contents are significantly higher in elderly patients with ischemic heart disease. Pentosidine is also significantly higher in patients with arterial hypertension. Malondialdehyde turned out to be higher in patients with diabetes mellitus type 2 that was not treated with insulin or metformin than in those treated with both medications (p = 0.052). GAL3 was found to be lower both in persons without diabetes and in diabetics treated with metformin (p = 0.005). LOX-1 was higher in diabetic patients not treated with metformin or insulin, and lowest in diabetics treated with both insulin and metformin, with the effect of metformin reducing LOX-1 levels (p = 0.039). Our results were the basis for a discussion about the diagnostic value in the clinical practice of LOX-1 and GAL3 in geriatric patients with diabetes and also provide grounds for inferring the therapeutic benefits of insulin and metformin treatment.

Association of OLR1 gene polymorphism with live body weight and body morphometric traits in Awassi ewes: short communication

BACKGROUND

Oxidized low-density lipoprotein receptor 1 (OLR1) is an endothelial receptor that binds and degrades oxidized low-density lipoproteins (Ox-LDL), thus having a physiological role in metabolism. Polymorphisms in the OLR1 gene are associated with animals with different production traits. Due to this, the study aimed to determine if OLR1 polymorphisms in Awassi ewes associate with live body weight and body measurement.

METHODS AND RESULTS

In this study, 200 ewes between the ages of 2.5 and 5 years, not pregnant or lactating, were selected. Phenotypic measurements including live body weight and body measurements were collected. A sheep's blood was collected to extract genomic DNA, genotyped, and sequenced to confirm the presence of the variants that arose from the amplified fragments. One novel C246A single nucleotide polymorphism (SNP) was identified in the OLR1 gene (exon 3) that assigned two genotypes CC and CA. The study indicated significant differences (P ≤ 0.05) in live body weight and body measurements of the genotype CC compared with the genotype CA. The genotype CC correlated positively with live body weight, height at shoulder, height at hip, chest girth, and chest width (r = 0.67, P = 0.02), (r = 0.54, P = 0.03), (r = 0.61, P = 0.02), (r = 0.53, P = 0.01) and (r = 0.66, P = 0.04) respectively.

CONCLUSIONS

Sheep with the CC genotype had a higher live body weight and larger body measurement, making them better for productivity. These genotypic data and associations can be used to better select sheep for future marker-assisted selection programs.

Compliance with Cardiovascular Prevention Guidelines in Type 2 Diabetes Individuals in a Middle-Income Region: A Cross-Sectional Analysis

Stricter control of risk factors has been pursued as a compelling strategy to mitigate cardiovascular events (CVE) in type 2 diabetes (T2D) individuals. However, the achievement rate of the recommended goals has remained low in clinical practice. This study investigated the 2019 ESC guideline recommendation attainment among T2D individuals enrolled in a national cohort held in Brazil. Data from 1030 individuals (mean age: 58 years old; 54% male; mean T2D duration: 9.7 years) were analyzed. The control rates were 30.6% for SBP, 18.8% for LDL-C, and 41% for A1c, and only 3.2% of the study participants met all three targets. Statins and high-intensity lipid-lowering therapy prescription rates were 45% and 8.2%, respectively. Longer T2D duration and those at higher CV risk were less likely to be controlled. Longer diabetes duration and higher CV risk were inversely related to the chance of achieving the recommended targets. Treatment escalation using conventional therapies would be sufficient to gain optimal control in most of the study sample. In conclusion, a minimal proportion of T2D individuals comply with guidelines-oriented CV prevention targets. Given the significant burden of the disease, and the substantial effect size predicted for these therapies, bridging this gap between guidelines and clinical practice should be considered an urgent call to public health managers.

Periodontal Disease Augments Cardiovascular Disease Risk Biomarkers in Rheumatoid Arthritis

Objectives: Periodontal disease (PD) and rheumatoid arthritis (RA) are known chronic conditions with sustained inflammation leading to osteolysis. Cardiovascular diseases (CVD) are frequent comorbidities that may arise from sustained inflammation associated with both PD and RA. In order to determine CVD risk, alterations at the molecular level need to be identified. The objective of this study, therefore, was to assess the relationship of CVD associated biomarkers in RA patients and how it is influenced by PD. Methods: The study consisted of patient (26 RA with PD, 21 RA without PD, 51 patients with PD only) and systemically and periodontally healthy control (n = 20) groups. Periodontal parameters bleeding on probing, probing pocket depth, and marginal bone loss were determined to characterize the patient groups. Proteomic analysis of 92 CVD-related protein biomarkers was performed using a multiplex proximity extension assay. Biomarkers were clustered using the search tool for retrieval of interacting genes (STRING) to determine protein−protein interaction (PPI) networks. Results: RA patients with PD had higher detection levels for 47% of the measured markers (ANGPT1, BOC, CCL17, CCL3, CD4, CD84, CTRC, FGF-21, FGF-23, GLO1, HAOX1, HB-EGF, hOSCAR, HSP 27, IL16, IL-17D, IL18, IL-27, IL6, LEP, LPL, MERTK, MMP12, MMP7, NEMO, PAPPA, PAR-1, PARP-1, PD-L2, PGF, PIgR, PRELP, RAGE, SCF, SLAMF7, SRC, THBS2, THPO, TNFRSF13B, TRAIL-R2, VEGFD, VSIG2, and XCL1) as compared to RA without PD. Furthermore, a strong biological network was identified amongst these proteins (clustering coefficient = 0.52, PPI enrichment p-value < 0.0001). Coefficients for protein clusters involved in CVD (0.59), metabolic (0.53), and skeletal (0.51) diseases were strongest in the PD group. Conclusion: Periodontal disease augments CVD-related biomarkers in RA through shared pathological clusters, concurrently enhancing metabolic and skeletal disease protein interactions, independent of autoimmune status.

Novel Insights Into Sterol Uptake and Intracellular Cholesterol Trafficking During Eimeria bovis Macromeront Formation

Apicomplexan parasites are considered as defective in cholesterol synthesis. Consequently, they need to scavenge cholesterol from the host cell by either enhancing the uptake of extracellular cholesterol sources or by upregulating host cellular de-novo biosynthesis. Given that Eimeria bovis macromeront formation in bovine lymphatic endothelial host cells in vivo is a highly cholesterol-demanding process, we here examined host parasite interactions based on host cellular uptake of different low-density lipoprotein (LDL) types, i.e., of non-modified (LDL), oxidized (oxLDL), and acetylated LDL (acLDL). Furthermore, the expression of lipoprotein-oxidized receptor 1 (LOX-1), which mediates acLDL and oxLDL internalization, was monitored throughout first merogony, in vitro and ex vivo. Moreover, the effects of inhibitors blocking exogenous sterol uptake or intracellular transport were studied during E. bovis macromeront formation in vitro. Hence, E. bovis-infected primary bovine umbilical vein endothelial cells (BUVEC) were treated with inhibitors of sterol uptake (ezetimibe, poly-C, poly-I, sucrose) and of intracellular sterol transport and release from endosomes (progesterone, U18666A). As a read-out system, the size and number of macromeronts as well as merozoite I production were estimated. Overall, the internalization of all LDL modifications (LDL, oxLDL, acLDL) was observed in E. bovis-infected BUVEC but to different extents. Supplementation with oxLDL and acLDL at lower concentrations (5 and 10 µg/ml, respectively) resulted in a slight increase of both macromeront numbers and size; however, at higher concentrations (25-50 µg/ml), merozoite I production was diminished. LOX-1 expression was enhanced in E. bovis-infected BUVEC, especially toward the end of merogony. As an interesting finding, ezetimibe treatments led to a highly significant blockage of macromeront development and merozoite I production confirming the relevance of sterol uptake for intracellular parasite development. Less prominent effects were induced by non-specific inhibition of LDL internalization via sucrose, poly-I, and poly-C. In addition, blockage of cholesterol transport via progesterone and U18666A treatments resulted in significant inhibition of parasite development. Overall, current data underline the relevance of exogenous sterol uptake and intracellular cholesterol transport for adequate E. bovis macromeront development, unfolding new perspectives for novel drug targets against E. bovis.

Original contribution: sleeve gastrectomy reduces soluble lectin-like oxidized low-density lipoprotein receptor-1 (sLOX-1) levels in patients with morbid obesity

BACKGROUND

Early diagnosis of subclinical cardiovascular disease (CVD) in patients with morbid obesity is important. We investigated the effects of sleeve gastrectomy (SG) on serum soluble lectin-like oxidized low-density lipoprotein receptor-1 (sLOX-1), oxidized LDL (oxLDL), and other metabolic and inflammatory parameters associated with atherosclerosis in patients with morbid obesity.

METHODS

Body mass index (BMI) measurements and assays of metabolic and inflammatory markers were taken in patients in an SG surgery group and a healthy control group and compared at baseline and 12 months after SG. Correlations with changes in these parameters and variations in sLOX-1 were analyzed.

RESULTS

Metabolic and inflammatory marker values in the surgery (n = 20) and control (n = 20) groups were significantly different at baseline (p < 0.001). The majority of surgery group biomarker levels significantly decreased with mean BMI loss (- 11.8 ± 9.0, p < 0.001) at 12 months, trending toward control group values. Baseline albumin level as well as percentage reductions in oxLDL and the cholesterol retention fraction (CRF) were found to be significantly correlated with percentage reduction in sLOX-1 at 12 months following SG.

CONCLUSION

Metabolic and inflammatory biomarkers elevated at baseline significantly decreased after SG weight loss. Weight loss induced by SG may limit endothelial damage by reducing levels of oxLDL and LOX-1 as assessed by sLOX-1. These findings suggest that sLOX-1 may function as a marker of atherosclerotic disease states in patients with morbid obesity and that metabolic/bariatric surgery can play a meaningful role in CVD prevention.

Where the Action Is-Leukocyte Recruitment in Atherosclerosis

Atherosclerosis is the leading cause of death worldwide and leukocyte recruitment is a key element of this phenomenon, thus allowing immune cells to enter the arterial wall. There, in concert with accumulating lipids, the invading leukocytes trigger a plethora of inflammatory responses which promote the influx of additional leukocytes and lead to the continued growth of atherosclerotic plaques. The recruitment process follows a precise scheme of tethering, rolling, firm arrest, crawling and transmigration and involves multiple cellular and subcellular players. This review aims to provide a comprehensive up-to-date insight into the process of leukocyte recruitment relevant to atherosclerosis, each from the perspective of endothelial cells, monocytes and macrophages, neutrophils, T lymphocytes and platelets. In addition, therapeutic options targeting leukocyte recruitment into atherosclerotic lesions-or potentially arising from the growing body of insights into its precise mechanisms-are highlighted.

Anti-Inflammatory Effects of Thymoquinone in Atherosclerosis: A Mini Review

Atherosclerosis poses serious health problems and increases the risk of various cardiovascular diseases, including myocardial infarction, heart failure, ischemic stroke, and peripheral arterial disease. Atherosclerosis patients require long-term medications to prevent complications, some of which are costly and may result in unwanted adverse reactions. Natural products have emerged as potential sources of bioactive compounds that provide health benefits in cardiovascular diseases. Increased inflammation and vascular remodeling have been associated with atherosclerosis pathogenesis. The molecules involved in signaling pathways are considered valuable targets for new treatment approaches. Therefore, this review aimed to summarize the available evidence of the anti-inflammatory effects of thymoquinone, the major active compound isolated from Nigella sativa L., via inflammatory signaling pathways in atherosclerosis. Specifically, nuclear factor-κB and mitogen-activated protein kinase signaling pathways were considered. Furthermore, the potential toxic effects elicited by thymoquinone were addressed. These findings suggest a potential role of thymoquinone in managing atherosclerosis, and further studies are required to ascertain its effectiveness and safety profile.

Soluble Lectin-Like Oxidized Low-Density Lipoprotein Receptor-1 Level is Related to Clinical Prognosis In Patients with Acute Atherosclerosis-related Ischemic Stroke

To investigate the associations between soluble Lectin-like Oxidized Low-density lipoprotein receptor-1 (sLOX-1) and clinical prognosis, especially infarct volume in patients with acute atherosclerosis-related ischemic stroke. We recruited acute ischemic stroke patients within 3 days after onset. Patients were stratified into 3 groups by sLOX-1 level. Initial stroke severity was assessed using the National Institutes of Health Stroke Scale scores, and infarct volume was measured using DWI by ITK-SNAP software. The clinical prognosis was evaluated by DWI volume, clinical response at discharge, and functional outcome at 90 days. Spearman rank correlation analysis was used to examine associations between circulating sLOX-1 levels and infarct volumes. Logistic regression was used to explore the relationship between sLOX-1 levels and clinical prognosis. A total of 207 patients were included in our study. The median DWI volume in the lowest sLOX-1 tertile was 1.98 cm³, smaller than 4.26 cm³ in the highest sLOX-1 group. The Spearman rank correlation coefficient between sLOX-1 levels and DWI volume was 0.47 (P < .01). Compared with the highest sLOX-1 tertiles, patients in the lowest sLOX-1 tertile had a higher risk of favorable functional outcome at 90 days (OR = 3.47, 95% CI, 1.21-9.96) after adjusting traditional risk factors. However, there was no difference between sLOX-1 level and clinical response at discharge. For patients with acute atherosclerosis-related ischemic stroke, circulating sLOX-1 level is correlated with DWI volume in the acute phase and favorable functional outcome at 90 days, but not with the clinical response at discharge.

Dual Role of SIRT1 in Autophagy and Lipid Metabolism Regulation in Osteoarthritic Chondrocytes

Background and Objectives: Osteoarthritis (OA) is one of the most common and highly prevalent types of arthritis, also considered a multiphenotypic disease with a strong metabolic component. Ageing is the primary risk factor for OA, while the age-related decline in autophagic activity affects cell function and chondrocyte homeostasis. The aim of this study was to investigate the role of sirtuin 1 (SIRT1) in autophagy dysregulation and lipid metabolism in human OA chondrocytes. Materials and Methods: OA chondrocytes were treated with Resveratrol, Hydroxycloroquine (HCQ) or 3-Methyladenine (3-MA) and HCQ or 3-MA followed by siRNA against SIRT1 (siSIRT1). Then, SIRT1, AcNF-κBp65, LOX-1 and autophagy-related proteins ATG5, ATG13, PI3K class III, Beclin-1, LC3 and ULK protein levels were evaluated using Western blot. Normal articular chondrocytes were treated under serum starvation and/or siSIRT1, and the protein expression levels of the above autophagy-related proteins were evaluated. The staining patterns of LC3/p62 and LOX-1 were analyzed microscopically by immunofluorescence. SIRT1/LC3 complex formation was analyzed by immunoprecipitation. Results: SIRT1 and LOX-1 protein expression were negatively correlated in OA chondrocytes. SIRT1 regulated LOX-1 expression via NF-κΒ deacetylation, while treatment with Resveratrol enhanced SIRT1 enzymatic activity, resulting in LOX-1 downregulation and autophagy induction. In OA chondrocytes, SIRT1 was recognized as an autophagy substrate, formed a complex with LC3 and was consequently subjected to cytoplasmic autophagosome-lysosome degradation. Moreover, siSIRT1-treated normal chondrocytes showed decreased autophagic activity, while double-treated (siSIRT1 and serum starvation) cells showed no induction of autophagy. Conclusions: Our results suggest that SIRT1 regulates lipid homeostasis through LOX-1 expression regulation. Additionally, we indicate that the necessity of SIRT1 for autophagy induction in normal chondrocytes, together with its selective autophagic degradation in OA chondrocytes, could contribute to autophagy dysregulation in OA. We, therefore, suggest a novel regulatory scheme that functionally connects lipid metabolism and autophagy in late-stage OA.

High-density lipoproteins, reverse cholesterol transport and atherogenesis

Plasma HDL-cholesterol concentrations correlate negatively with the risk of atherosclerotic cardiovascular disease (ASCVD). According to a widely cited model, HDL elicits its atheroprotective effect through its role in reverse cholesterol transport, which comprises the efflux of cholesterol from macrophages to early forms of HDL, followed by the conversion of free cholesterol (FCh) contained in HDL into cholesteryl esters, which are hepatically extracted from the plasma by HDL receptors and transferred to the bile for intestinal excretion. Given that increasing plasma HDL-cholesterol levels by genetic approaches does not reduce the risk of ASCVD, the focus of research has shifted to HDL function, especially in the context of macrophage cholesterol efflux. In support of the reverse cholesterol transport model, several large studies have revealed an inverse correlation between macrophage cholesterol efflux to plasma HDL and ASCVD. However, other studies have cast doubt on the underlying reverse cholesterol transport mechanism: in mice and humans, the FCh contained in HDL is rapidly cleared from the plasma (within minutes), independently of esterification and HDL holoparticle uptake by the liver. Moreover, the reversibility of FCh transfer between macrophages and HDL has implicated the reverse process - that is, the transfer of FCh from HDL to macrophages - in the aetiology of increased ASCVD under conditions of very high plasma HDL-FCh concentrations.

Non-stenotic Carotid Plaques in Embolic Stroke of Unknown Source

Embolic stroke of unknown source (ESUS) represents one in five ischemic strokes. Ipsilateral non-stenotic carotid plaques are identified in 40% of all ESUS. In this narrative review, we summarize the evidence supporting the potential causal relationship between ESUS and non-stenotic carotid plaques; discuss the remaining challenges in establishing the causal link between non-stenotic plaques and ESUS and describe biomarkers of potential interest for future research. In support of the causal relationship between ESUS and non-stenotic carotid plaques, studies have shown that plaques with high-risk features are five times more prevalent in the ipsilateral vs. the contralateral carotid and there is a lower incidence of atrial fibrillation during follow-up in patients with ipsilateral non-stenotic carotid plaques. However, non-stenotic carotid plaques with or without high-risk features often coexist with other potential etiologies of stroke, notably atrial fibrillation (8.5%), intracranial atherosclerosis (8.4%), patent foramen ovale (5-9%), and atrial cardiopathy (2.4%). Such puzzling clinical associations make it challenging to confirm the causal link between non-stenotic plaques and ESUS. There are several ongoing studies exploring whether select protein and RNA biomarkers of plaque progression or vulnerability could facilitate the reclassification of some ESUS as large vessel strokes or help to optimize secondary prevention strategies.

Anti-inflammatory Treatment and Cardiovascular Outcomes: Results of Clinical Trials

Atherosclerosis is a chronic inflammatory disorder of the vasculature where cholesterol accumulates in the arterial wall stimulating infiltration of immune cells. This plays an important role in plaque formation, as well as complications caused by its build up. Pro-inflammatory cytokines and chemokines are implicated throughout the progression of the disease and different therapies that aim to resolve this chronic inflammation, reduce cardiovascular (CV) events and improve clinical outcomes have been tested. The results from the pivotal CANTOS trial show that targeting the pro-inflammatory cytokine IL-1β successfully reduces the incidence of secondary CV events. This review briefly assesses the role of inflammation in atherosclerosis, providing a picture of the multiple players involved in the process and offering a perspective on targeting inflammation to prevent atherosclerotic CV events, as well as focusing on the results of the latest Phase III clinical trials.