Lectin-like Oxidized Low-density Lipoprotein Receptor-1 Research Articles

OxLDL/LOX-1 mediated sex, age, stiffness, and endothelial dependent alterations in mouse thoracic aortic vascular reactivity

Elevated plasma levels of oxidized low-density lipoprotein (oxLDL) are a risk factor and key component that accelerates and worsens cardiovascular disease fueling inflammation, plaque buildup and vascular damage. OxLDL can elicit its detrimental action via lectin-like oxLDL receptor 1 (LOX-1). In this study, we determined whether oxLDL, via LOX-1, alters aortic vascular reactivity and determined if sex and age differences exist. Thoracic aortic endothelium-intact or -denuded ring segments were isolated from 7 to 12 months old intact C57BL/6J female and male mice and pre-incubated with oxLDL ex vivo (50ug/dL; 2 h). Using wire myography, cumulative concentration-response curves to phenylephrine (PE) were generated to determine contractile responses. From these curves, the EC50 was determined and used to contract rings to assess acetylcholine (ACh) dependent relaxation. Calculated aortic stiffness and remodeling were also assessed. BI-0115 (10 μM; selective LOX-1 inhibitor) was used to determine LOX-1 dependence. We observed differential sex, age, endothelial cell, and LOX-1 dependent alterations to the efficacy of PE-induced contractile responses and ACh-mediated vasorelaxation in thoracic aortic rings following oxLDL exposure. Additionally, we observed a distinct sex and age effect on thoracic aortic stiffness following exposure to oxLDL. There was also a sex effect on calculated vessel diameter, as well as an age effect on oxLDL-mediated aortic remodeling that was LOX-1 dependent. Thus, LOX-1 inhibition and the resulting attenuation of oxLDL/endothelial-mediated alterations in aortic function suggests that there are differential sex differences in the role of oxLDL/LOX-1 in the thoracic aorta of middle-aged male and female mice. NEW and NOTEWORTHY. We investigated the effects of oxLDL via the LOX-1 receptor on murine thoracic aortic vasoreactivity, stiffness, and remodeling across age and sex. Acute exposure to oxLDL led to altered vasoreactivity, endothelial dysfunction, and changes in aortic stiffness and remodeling. These effects were in-part age, sex, endothelial, and LOX-1 dependent. This study reveals potential complex interactions in oxLDL/LOX-1-mediated vascular responses that could serve as potential therapeutic intervention for vascular diseases such as atherosclerosis and stroke.

Apolipoprotein C3-rich low-density lipoprotein (AC3RL) exacerbates cerebral ischaemic stroke injury by increasing BBB leakage via LOX-1

Abstract Background Ischaemic stroke causes the abrupt reduction or cessation of blood flow to the brain results in a cascade of events that can compromise blood-brain barrier (BBB) integrity. We revealed that an increase in apolipoprotein C3 (ApoC3)-rich low-density lipoprotein (AC3RL) is associated with endothelial cell apoptosis and inflammatory responses, indicating that AC3RL is one of the risk factors for cardiovascular events. Lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) triggers a cascade of events within endothelial cells that leads to endothelial dysfunction. Purpose We aimed to investigate whether AC3RL affects BBB permeability via the LOX-1, and thus increases brain damage. Methods We collected the whole blood from normal and patients with ischaemic events and separated them by centrifugation. AC3RL were collected using FPLC. We performed middle cerebral artery occlusion (MCAO) surgery to induce ischaemic stroke using B6 (C57BL/6) and LOX-1-/- mice injected with AC3RL. Triphenyl tetrazolium chloride (TTC) and Evans blue stains were accessed to confirm brain injury and BBB permeability. Results FPLC results showed that patients with ischaemic events presented higher levels of AC3RL compared to normal people. TTC stain showed the increased area of ischaemic penumbra damage in B6 mice with AC3RL injection, and LOX-1-/- mice with AC3RL injection were significantly protected. Evans blue dye leakage was observed in the brain tissues of B6 mice with AC3RL injection. LOX-1-/- mice with AC3RL injection revealed a decrease in BBB permeability. The modified neurological severity score (mNSS) method revealed a significant rise in B6 mice with AC3RL injection, which suggested a decline in motor and nervous function. LOX-1-/- mice with AC3RL injection significantly improved in motor and neurological functioning. Conclusions We demonstrate that AC3RL, through its effects on LOX-1, is associated with an increased risk of BBB damage after stroke. Therefore, pharmacological inhibition of AC3RL-LOX-1 interaction will be the main strategy to reduce severe brain damage. Figure 1: (A) AC3RL percentage (%) in individuals. Normal: healthy people, Ischemic event: patients who have experienced an ischemic event. **p < 0.001 vs. Normal group. (B, C) TTC stain of brain tissue after euthanasia to pinpoint the site of brain damage. The white portion of the mice brains indicated the site of the injury. (D, E) Evans blue dye leakage study in mice brains exhibited BBB permeability changes. (F) Assessment of mice's motor and neurological performance using the mNSS. Data are expressed as the mean ± SEM. **p < 0.001, ****p < 0.0001 vs. sham group, ##p < 0.001 vs. B6 I.V. AC3RL group.Graphical abstractFigure 1.

Cardioprotection in coronary artery bypass graft surgery: the impact of remote ischemic preconditioning on modulating LOX-1 and SOD-1 to counteract oxidative stress.

Coronary artery bypass grafting (CABG) is frequently used to treat severe coronary artery disease (CAD), but it can lead to increased oxidative stress and inflammation, worsening patient outcomes. Remote ischemic preconditioning (RIPC) has been suggested as a potential strategy to protect against these effects by modulating oxidative stress and inflammatory responses, though its impact on specific biomarkers requires further investigation. This study aims to assess the effects of remote ischemic preconditioning on inflammation markers and oxidative stress in patients with severe CAD undergoing coronary artery bypass grafting. We conducted a case-control study involving 80 patients with severe coronary artery disease (CAD) scheduled for coronary artery bypass grafting (CABG). Fifty percent of these patients received ischemic preconditioning prior to surgery. Plasma levels of Lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) and Superoxide dismutase-1 (SOD-1) levels were measured in all individuals using the ELISA method at three important time points: before surgery (visit 1 or V1), immediately post-operatively (visit 2 or V2), and one week post-operatively (visit 3 or V3). We enrolled 80 patients, of which 40 were assigned to the studied group receiving remote ischemic preconditioning (RIPC) and 40 to the control group. There were no statistically significant differences between the groups regarding baseline, clinical, or operative characteristics. RIPC treatment significantly reduced plasma levels of Lectin-like oxidized low-density lipoprotein (LDL) receptor-1 (LOX-1) (p < 0.05) as well as significantly increasing total values of Superoxide dismutase-1 (SOD-1) (p < 0.05, respectively). There were notable differences between the studied and control groups at V2 and V3. The studied group had higher SOD-1 levels (p < 0.05) and significantly lower LOX-1 levels at both time points (p < 0.05). The significant changes in plasma levels of both LOX-1 and SOD-1 observed in this study strongly suggest that remote ischemic preconditioning (RIPC) plays an important role in reducing oxidative stress and enhancing the antioxidative status of patients. This is evidenced by the marked decrease in LOX-1 levels, alongside a corresponding increase in SOD-1 levels, indicating that RIPC may contribute to improved cardioprotection through these mechanisms.

Therapeutic Effects of Proanthocyanidins on Diabetic Erectile Dysfunction in Rats.

The rising occurrence of erectile dysfunction related to diabetes mellitus (DMED) has led to the creation of new medications. Proanthocyanidins (PROs) is a potential agent for DMED. In this study, the DMED rat model was established using streptozotocin (STZ) and erectile function was assessed using apomorphine (APO) in rats. Following this, the rats were subjected to oral treatment with PRO. Then, we evaluated the influence of PROs on DMED rats. The findings suggest that PROs significantly enhance erectile function in DMED rats. PROs modulated glucose and lipid metabolism in DMED rats by decreasing blood glucose and lipid levels while increasing liver glycogen and serum insulin levels. Furthermore, PROs enhanced vascular endothelial function in DMED rats by augmenting nitric oxide (NO) levels and reducing the levels of endothelin-1 (ET-1) and lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1). Additionally, PROs have been shown to elevate testosterone (T) levels, mitigate pathological testicular damage, and enhance sperm concentration and survival rates. Finally, the core targets were screened using network pharmacology, followed by validation through molecular docking, enzyme-linked immunoassay (ELISA), and real-time PCR methodologies. Our findings imply that PROs may treat DMED by elevating AKT1 levels while concurrently diminishing CASP3 levels, thereby effectively regulating the PI3K-Akt signaling pathway. Overall, these results support using PROs as a potential candidate for the treatment of DMED.

Mechanisms and consequences of myeloid adhesome dysfunction in atherogenesis.

In the context of atherosclerosis, macrophages exposed to oxidized low-density lipoprotein (oxLDL) exhibit cellular abnormalities, specifically in adhesome functions, yet the mechanisms and implications of these adhesive dysfunctions remain largely unexplored. This study reveals a significant depletion of Kindlin3 (K3) or Fermt3, an essential component of the adhesome regulating integrin functions, in macrophages located within atherosclerotic plaques in vivo and following oxLDL exposure in vitro. To examine the effects of K3 deficiency, the study utilized hyperlipidemic bone marrow chimeras devoid of myeloid Kindlin3 expression. Absence of myeloid K3 increased atherosclerotic plaque burden in the aortas in vivo and enhanced lipid accumulation and lipoprotein uptake in macrophages from Kindlin3-null chimeric mice in vitro. Importantly, re-expression of K3 in macrophages ameliorated these abnormalities.RNA sequencing of bone marrow-derived macrophages (BMDM) from K3-deficient mice revealed extensive deregulation in adhesion-related pathways, echoing changes observed in wild-type cells treated with oxLDL. Notably, there was an increase in Olr1 expression (encoding the Lectin-like oxidized LDL receptor-1 or LOX1), a gene implicated in atherogenesis. The disrupted K3-integrin axis in macrophages led to a significant elevation in the LOX1 receptor, contributing to increased oxLDL uptake and foam cell formation. Inhibition of LOX1 normalized lipid uptake in Kindlin3 null macrophages. A similar proatherogenic phenotype, marked by increased macrophage LOX1 expression and foam cell formation, was observed in myeloid-specific Itgβ1-deficient mice but not in Itgβ2-deficient mice, underscoring the critical role of K3/Itgβ1 interaction. This study shows that the loss of Kindlin3 in macrophages upon exposure to oxLDL leads to adhesome dysfunction in atherosclerosis and reveals the pivotal role of Kindlin3 in macrophage function and its contribution to the progression of atherosclerosis, providing valuable insights into the molecular mechanisms that could be targeted for therapeutic interventions.

Contribution of the OLR1 gene to the development of cardiovascular diseases

Cardiovascular diseases (CVDs) are the leading cause of death in the world. Studies on the molecular genetic mechanisms aimed at detecting pathogenetically significant molecular targets, as well as searching for informative biomarkers remain relevant. Some of these predictive/prognostic marker candidates are the OLR1 gene products and polymorphisms.The OLR1 gene encodes the lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1), the expression of which increases in response to proinflammatory or proatherogenic factors. LOX-1 plays an important pathogenetic role in the development of CVD and type 2 diabetes. Single nucleotide polymorphisms in the OLR1 gene can be used as a genetic biomarker predicting the CVDs, necessary for stratification of patients into risk groups within the concept of personalized medicine, as well as potential therapeutic targets for patients with certain clinical phenotypes. This review examines the main genetic and epidemiological studies of the OLR1 gene association with CVDs and the etiopathogenetic mechanisms of the OLR1 gene influence on their development.

Vegetable and Fruit Intake and LOX-Index in Japanese Municipal Workers.

Vegetable and fruit intake has been reported to be associated with decreased risk of cardiovascular disease. To date, however, no study has examined the association between vegetable and fruit intake and LOX-index, which reflects the progression of atherosclerosis and is a predictive biomarker of stroke and coronary heart disease. Here, we examined the cross-sectional association between vegetable and fruit intake and LOX-index in Japanese municipal workers. Participants were 338 workers (166 men and 172 women aged 19-71 y) with no history of serious disease who participated in a health and nutrition survey. Vegetable and fruit intake was assessed using a validated brief self-administered diet history questionnaire. LOX-index was calculated by multiplying serum concentrations of the soluble form of lectin-like oxidized LDL receptor-1 by those of LOX-1 ligands containing apolipoprotein B. Multiple regression analysis was used to estimate the geometric mean of LOX-index according to tertile of vegetable and/or fruit intake. Total vegetable and fruit intake was associated with a trend toward decreased LOX-index after adjustment for covariates (p for trend=0.067). In stratified analyses by sex, a significant inverse association between total vegetable and fruit intake and LOX-index was observed in women (p for trend=0.023), whereas such association was not observed in men (p for trend=0.70). None of the intakes of vegetables, fruit, green and yellow vegetables, or other vegetables was associated with LOX-index. Our results suggest that higher intake of total vegetables and fruit is associated with a lower LOX-index in Japanese women.

Unraveling the Mystery: How High Density Lipoprotein ‘Good’ Cholesterol Goes ‘Bad’?

Background: In recent years, research has highlighted the importance of Lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) in the progression of atherosclerosis, particularly its interaction with high-density lipoprotein (HDL). Our study aimed to explore the role of dysfunctional High-Density Lipoprotein (HDL) in binding to Lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) among patients with Coronary Artery Disease (CAD) and its implications for the advancement of atherosclerosis. Methods: We enrolled twenty-one patients who underwent multivessel CABG using internal mammary artery (IMA), radial artery (RA), and saphenous vein (SV) grafts between November 2019 and April 2020. Using CD31 to identify endothelial cells, we evaluated LOX-1 expression in all cultured cells. Results: Our study comprised 21 patients, including 17 (80.9%) males and 4 (19.04%) females. We observed a significant positive correlation between HDL and LOX-1+ expression in specimens extracted from all types of grafts (SV, r=0.60; RA, r=0.48; IMA, r=0.53). Approximately 28% of the variation in LOX-1+ expression for IMA (F=7.03; p

CAIP-Induced ROS Production Contributes to Sustaining Atherosclerotic Process Associated with Helicobacter cinaedi Infection through Macrophages and Endothelial Cells Activation.

Several lines of evidence have linked the intestinal bacterium Helicobacter cinaedi with the pathogenesis of atherosclerosis, identifying the Cinaedi Antigen Inflammatory Protein (CAIP) as a key virulence factor. Oxidative stress and inflammation are crucial in sustaining the atherosclerotic process and oxidized LDL (oxLDL) uptake. Primary human macrophages and endothelial cells were pre-incubated with 10 µM diphenyl iodonium salt (DPI) and stimulated with 20 µg/mL CAIP. Lectin-like oxLDL receptor (LOX-1) expression was evaluated by FACS analysis, reactive oxygen species (ROS) production was measured using the fluorescent probe H2DCF-DA, and cytokine release was quantified by ELISA assay. Foam cells formation was assessed by Oil Red-O staining, and phosphorylation of p38 and ERK1/2 MAP kinases and NF-κB pathway activation were determined by Western blot. This study demonstrated that CAIP triggered LOX-1 over-expression and increased ROS production in both macrophages and endothelial cells. Blocking ROS abrogated LOX-1 expression and reduced LDL uptake and foam cells formation. Additionally, CAIP-mediated pro-inflammatory cytokine release was significantly affected by ROS inhibition. The signaling pathway induced by CAIP-induced oxidative stress led to p38 MAP kinase phosphorylation and NF-κB activation. These findings elucidate the mechanism of action of CAIP, which heightens oxidative stress and contributes to the atherosclerotic process in H. cinaedi-infected patients.

Chelerythrine ameliorates Aspergillus fumigatus keratitis through suppressing the LOX-1/p38 MAPK signaling pathway

PurposeAspergillus fumigatus (A. fumigatus) keratitis is a type of infectious corneal disease that significantly impairs vision. The objective of this study is to evaluate the therapeutic potential of chelerythrine (CHE) on A. fumigatus keratitis. MethodsThe antifungal activity of CHE was assessed through various tests including the minimum inhibitory concentration test, scanning electron microscopy, transmission electron microscopy, propidium iodide uptake test and plate count. Neutrophil infiltration and activity were assessed using immunofluorescence staining and the myeloperoxidase test. RT-PCR, western blotting assay, and ELISA were performed to measure the expression levels of proinflammatory cytokines (IL-1β and IL-6), NF-E2-related factor (Nrf2), heme oxygenase-1 (HO-1), and lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1), as well as to determine the ratio of phosphorylated-p38 (p-p38) mitogen-activated protein kinase (MAPK) to p38 MAPK. ResultsIn vitro, CHE inhibited the growth of A. fumigatus conidia, reduced fungal hyphae survival, and prevented fungal biofilm formation. In vivo, CHE reduced the severity of A. fumigatus keratitis and exhibited an excellent anti-inflammatory effect by blocking neutrophil infiltration. Furthermore, CHE decreased the expression levels of proinflammatory cytokines and LOX-1 at both mRNA and protein levels, while also decreasing the p-p38 MAPK/p38 MAPK ratio. Additionally, CHE increased the expression levels of Nrf2 and HO-1. ConclusionCHE provides protection against A. fumigatus keratitis through multiple mechanisms, including reducing fungal survival, inducing anti-inflammatory effects, enhancing Nrf2 and HO-1 expression, and suppressing the signaling pathway of LOX-1/p38 MAPK.

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.

Roles of MDA-LDL/OX-LDL/LOX-1 and TNF-α/TLR4/NF-κB Signaling Pathways in Myocardial Damage by Implantations of Cardiac Pacemakers in Elderly Patients.

Permanent pacemakers are an established treatment for sick sinus syndrome and high-grade atrioventricular block. Permanent cardiac pacemaker implantations may damage the myocardium. This study evaluated markers of myocardial injury, oxidative stress and inflammation in elderly patients with permanent pacemaker implantations. Various markers were measured at 1, 2, 3 and 4 months after permanent pacemaker implantations in elderly patients. The levels of high-sensitivity troponin T (hsTnT), lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1), malondialdehyde-modified low-density lipoprotein (MDA-LDL), oxidized low-density lipoprotein (OX-LDL), tumour necrosis factor-α (TNF-α), toll-like receptor 4 (TLR4) and nuclear factor-kappa B (NF-κB) were increased in 2-month group compared with control and 1- month groups (P<0.001), and were further increased at 4-month group compared with 2- and 3- month groups after pacemaker implantations (P<0.001). Patients with dual-chamber pacemakers had higher levels of hsTnT, LOX-1, MDA-LDL, OX-LDL, TNF-α, TLR4 and NF-κB than patients with single chamber pacemakers (P<0.001). Patients who underwent the pacemakers with the active fixation leads had raised levels of hsTnT, LOX-1, MDA-LDL, OX-LDL, TNF-α, TLR4 and NF-κB compared patients with pacemakers using the passive fixation leads (P<0.001). Myocardial blood flows in 3-month and 4-month groups were lower than 1-month and 2-month groups (P<0.001). Levels of hsTnT, LOX-1, MDA-LDL, OX-LDL, TNF-α, TLR4 and NF-κB were elevated in elderly patients with permanent pacemaker implantations and the activations of oxidative stress and pro-inflammatory signalling pathways may be associated with myocardial damages and ischemia after pacemaker implantations in elderly patients.

Lipoproteins and Their Receptors Association in Cerebrovascular Disease Pathogenesis: A Comprehensive Analysis

Atherosclerosis, a leading cause of cardiovascular and cerebrovascular diseases, is driven by dyslipidemia and inflammatory processes. This study aimed to assess the relationship between lipoproteins and their receptors in patients with acute cerebrovascular accidents, using Receiver Operating Characteristic (ROC) analysis to evaluate their predictive value for stroke risk. A total of 165 patients with acute cerebrovascular events were included, and comprehensive assessments, including enzyme immunoassays for lipoprotein A (Lp(a)) and lipoprotein-associated phospholipase A2 (Lp-PLA2), were conducted. Results revealed significant associations between lipoprotein levels and neurological deficits, with a 2.3-fold increase in Lp(a) and a 2.2-fold decrease in low-density lipoprotein receptors (LDLR) in severe cases. Elevated lectin-like oxidized LDL receptor (LOX-1) and Lp-PLA2 levels were also noted, highlighting their roles in plaque destabilization and inflammation. The findings underscore the complex interplay of lipid metabolism, thrombus formation, and endothelial dysfunction in cerebrovascular events. This study emphasizes the importance of early detection and targeted interventions to modulate lipoprotein levels and reduce inflammation, offering potential strategies to mitigate stroke risk in atherosclerosis patients.

OxLDL/LOX-1 Mediated Sex, Age, and Cell Dependent Alterations in Mouse Thoracic Aortic Vascular Reactivity, Stiffness, and Remodeling

Elevated oxidized low-density lipoprotein (oxLDL) is a risk factor and component that worsens cardiovascular disease states. OxLDL can elicit its detrimental action, via lectin-like oxLDL receptor 1 (LOX-1) and has been shown to disrupt vascular function. In this study, we determined whether oxLDL, via LOX-1, alters aortic vascular reactivity and determined if sex differences exist. Thoracic aortic endothelium-intact or -denuded ring segments were isolated from intact C57BL/6J female and male mice and incubated with oxLDL ex vivo (50ug/dL; 2h). Using wire myography, cumulative concentration-response curves to phenylephrine (PE) were generated to determine contractile responses. From these curves, the EC50 was determined and used to contract rings to assess acetylcholine (ACh) dependent relaxation. Calculated aortic stiffness and remodeling, as well as mRNA expression of vasoactive and pro-inflammatory mediators were assessed. BI-0115 (10μM; selective LOX-1 inhibitor) was used to determine LOX-1 dependence. In this study, we investigated the effects of oxidized low-density lipoprotein (oxLDL) via the LOX-1 receptor on murine thoracic aortic vasoreactivity, stiffness, and remodeling across age and sex. Our results demonstrate a differential sex, age, endothelial cell, and LOX-1 dependent alterations to the effcacy of PE-induced contractile responses and ACh-mediated vasorelaxation in the thoracic aortic rings following oxLDL exposure. Additionally, we observed a distinct sex and age effect on thoracic aortic stiffness following exposure to oxLDL. There was also a sex effect on calculated vessel diameter, as well as an age effect on oxLDL-mediated inward remodeling that was LOX-1 dependent. We also observed an oxLDL and age dependent increase in LOX-1, IL-6, endothelin-1 (ET-1), and ET-1 receptor alpha and beta mRNA expression. Thus, LOX-1 inhibition and the resulting attenuation of oxLDL/endothelial-mediated alterations in aortic function suggests that there are differential sex differences in the role of oxLDL/LOX-1 in the thoracic aorta of male and female mice. In conclusion, acute exposure to oxLDL led to altered vasoreactivity, endothelial dysfunction, and changes in aortic stiffness and remodeling. These effects were in-part age, sex, endothelial, and LOX-1 dependent. This study reveals potential complex interactions in oxLDL/LOX-1-mediated vascular responses that could serve as potential therapeutic intervention for vascular diseases such as atherosclerosis. University of Arizona Valley Research Partnership Grant VRP37 P2 (RJG), American Heart Association 19AIREA34480018 (RJG), UA VRP Grant VRP55 P1a (TSW). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Hemoglobin-Mediated Oxidation of Low-Density Lipoprotein (oxLDL) Contributes to Lung Microvascular Endothelial Dysfunction Via Lectin-Like Oxidized LDL Receptor 1 (LOX-1)

Introduction: Lung microvascular endothelial barrier disruption is a critical feature of acute lung injury during several pathologies, including sepsis. Plasma cell-free hemoglobin (CFH) is elevated in approximately 80% of patients with sepsis and is independently associated with development of acute respiratory distress syndrome (ARDS) and mortality. However, the precise signaling mechanisms involved in CFH-mediated lung microvascular barrier dysfunction are incompletely understood. One potential mechanism by which CFH might disrupt the microvascular endothelial barrier is through its known ability to oxidize lipids and lipoproteins, including low-density lipoprotein (LDL). Oxidized LDL (oxLDL) is a known endothelial barrier disruptor, primarily signaling through scavenger receptors such as lectin-like oxidized LDL receptor 1 (LOX-1). We hypothesized that CFH-mediated oxidation of LDL exacerbates lung microvascular endothelial barrier dysfunction via LOX-1. Methods: For experimental studies, LDL was oxidized by combining LDL with CFH in a test tube overnight at 37°C and oxidation of LDL was quantified by TBARS assay. In primary human lung microvascular endothelial cells (HLMVEC), barrier dysfunction was assessed with expert permeability testing (XPerT) assay. HLMVEC were stimulated with vehicle control (PBS), LDL (0.05 mg/mL), CFH (0.5 mg/mL), or LDL oxidized by CFH (LDL+CFH) with or without one-hour pre-treatment of hemoglobin scavenger haptoglobin (1:1) or LOX-1 inhibitor BI-0115 (Boehringer Ingelheim, 10 μM). Cleaved caspase-3 (CST 9661, 1:500) was assessed with immunofluorescence microscopy. To test whether CFH and oxLDL are associated in clinical sepsis, circulating levels of CFH and oxLDL were measured in 60 sepsis patients via ELISA. Results: Oxidation of LDL by CFH (p=0.0006 by TBARS) exacerbated HLMVEC barrier dysfunction (p&lt;0.0001 by XPerT) but was partially prevented by scavenging CFH with haptoglobin (p&lt;0.0001 by XPerT) or blocking LOX-1 receptor (p&lt;0.0001 by XPerT). Oxidation of LDL by CFH stimulation of HLMVEC also increased caspase-3 activation (p&lt;0.0001 by immunofluorescence of cleaved caspase-3). In sepsis patients, circulating oxLDL levels correlated with CFH (r=0.4, p=0.002). Conclusions: Oxidation of LDL by CFH contributes to lung microvascular endothelial injury via LOX-1 receptor and activation of caspase-3; targeting this pathway may hold therapeutic potential to treat pathologies in which CFH is elevated, including sepsis-induced acute lung injury/ARDS. Funding: Parker B. Francis Fellowship (JEM); NIH K99HL166865 (JEM), R01HL158906 (LBW), R01HL164937 (LBW), R21GM144915 (LBW, JAB), R35HL150783 (JAB), RF1AG075341 (JAB). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review 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.

Antioxidant Vitamin Intake and LOX-Index in Japanese Municipal Workers.

Antioxidant vitamin intake has been reported to be associated with decreased risk of cardiovascular diseases. To date, however, no study has examined the association between antioxidant vitamin intake and LOX-index, a predictive biomarker of cardiovascular disease. We investigated the cross-sectional association between antioxidant vitamin (α-carotene, β-carotene, α-tocopherol, and vitamin C) intake and LOX-index in Japanese municipal workers. Participants were 346 workers (171 men and 175 women aged 19-71 y) who received a health check-up and participated in a nutrition and health survey. Antioxidant vitamin intake was assessed using a validated brief self-administered diet history questionnaire. LOX-index was calculated by multiplying serum concentrations of the soluble form of lectin-like oxidized LDL receptor 1 by those of LOX-1 ligands containing apolipoprotein B. Multiple regression analysis was used to estimate the geometric mean of LOX-index according to tertile of each antioxidant vitamin intake. Overall, α-carotene, β-carotene, α-tocopherol, and vitamin C intake were not associated with LOX-index. However, in stratified analyses by sex, geometric means of LOX-index tended to decrease with antioxidant vitamin intake in women, but not in men. The geometric means of LOX-index for the lowest through highest tertile of α-carotene intake were 771 (604-984), 639 (511-799), and 564 (469-677) (p for trend=0.07). Our results suggest that there is no association between antioxidant vitamin intake and LOX-index in Japanese workers. The suggestive inverse association between antioxidant vitamin intake and LOX-index in women warrants further investigation.

Novel Associations Between Mid-Pregnancy Cardiovascular Biomarkers and Preeclampsia: An Explorative Nested Case-Control Study.

Prediction of women at high risk of preeclampsia is important for prevention and increased surveillance of the disease. Current prediction models need improvement, particularly with regard to late-onset preeclampsia. Preeclampsia shares pathophysiological entities with cardiovascular disease; thus, cardiovascular biomarkers may contribute to improving prediction models. In this nested case-control study, we explored the predictive importance of mid-pregnancy cardiovascular biomarkers for subsequent preeclampsia. We included healthy women with singleton pregnancies who had donated blood in mid-pregnancy (~ 18weeks' gestation). Cases were women with subsequent preeclampsia (n = 296, 10% of whom had early-onset preeclampsia [< 34weeks]). Controls were women who had healthy pregnancies (n = 333). We collected data on maternal, pregnancy, and infant characteristics from medical records. We used the Olink cardiovascular II panel immunoassay to measure 92 biomarkers in the mid-pregnancy plasma samples. The Boruta algorithm was used to determine the predictive importance of the investigated biomarkers and first-trimester pregnancy characteristics for the development of preeclampsia. The following biomarkers had confirmed associations with early-onset preeclampsia (in descending order of importance): placental growth factor (PlGF), matrix metalloproteinase (MMP-12), lectin-like oxidized LDL receptor 1, carcinoembryonic antigen-related cell adhesion molecule 8, serine protease 27, pro-interleukin-16, and poly (ADP-ribose) polymerase 1. The biomarkers that were associated with late-onset preeclampsia were BNP, MMP-12, alpha-L-iduronidase (IDUA), PlGF, low-affinity immunoglobulin gamma Fc region receptor II-b, and T cell surface glycoprotein. Our results suggest that MMP-12 is a promising novel preeclampsia biomarker. Moreover, BNP and IDUA may be of value in enhancing prediction of late-onset preeclampsia.

LOX-1 regulation of H-type vascular endothelial cell regeneration in hyperglycemia.

Diabetic osteoporosis (DOP) is the most common secondary form of osteoporosis. Diabetes mellitus affects bone metabolism; however, the underlying pathophysiological mechanisms remain unclear. Lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) expression is upregulated in conditions characterized by vascular injury, such as atherosclerosis, hypertension, and diabetes. Additionally, Notch, HIF-1α, and VEGF are involved in angiogenesis and bone formation. Therefore, we aimed to investigate the expression of Notch, HIF-1α, and VEGF in the LOX-1 silencing state. Rat bone H-type vascular endothelial cells (THVECs) were isolated and cultured in vitro. Cell identification was performed using immunofluorescent co-expression of CD31 and Emcn. Lentiviral silencing vector (LV-LOX-1) targeting LOX-1 was constructed using genetic recombination technology and transfected into the cells. The experimental groups included the following: NC group, HG group, LV-LOX-1 group, LV-CON group, HG + LV-LOX-1 group, HG + LV-CON group, HG + LV-LOX-1 + FLI-06 group, HG + LV-CON + FLI-06 group, HG + LV-LOX-1 + LW6 group, and HG + LV-CON + LW6 group. The levels of LOX-1, Notch, Hif-1α, and VEGF were detected using PCR and WB techniques to investigate whether the expression of LOX-1 under high glucose conditions has a regulatory effect on downstream molecules at the gene and protein levels, as well as the specific molecular mechanisms involved. High glucose (HG) conditions led to a significant increase in LOX-1 expression, leading to inhibition of angiogenesis, whereas silencing LOX-1 can reverse this phenomenon. Further analysis reveals that changes in LOX-1 will promote changes in Notch/HIF-1α and VEGF. Moreover, Notch mediates the activation of HIF-1α and VEGF. The activation of LOX-1 and the inhibition of Notch/HIF-1α/VEGF in THVECs are the main causes of DOP. These findings contribute to our understanding of the pathogenesis of DOP and offer a novel approach for preventing and treating osteoporosis.

Impact of Endurance Exercise Training on Biomarkers of Aortic Endothelial Damage in Diabetic Rats

Given the heightened risk of diabetes‐related cardiovascular events associated with inactivity, this study investigates the molecular mechanisms of vascular damage in streptozotocin (STZ)‐induced diabetic rats. The aim is to elucidate the impact of different exercises (interval and continuous training) and metformin on biochemical parameters, aortic injury, oxidative stress, and inflammation to provide insights into potential therapeutic interventions for diabetes‐associated vascular complications. Male Wistar rats were administered a single dose of STZ (60 mg/kg) to induce diabetes. Diabetic rats underwent either interval training or continuous training (40 min/day, 5 days/week, 6 weeks), received metformin (300 mg/kg), or a combination of metformin and exercise. After 6 weeks, biochemical parameters in serum and oxidative stress markers and mRNA expression of endothelial nitric oxide synthase (eNOS), lectin‐like oxidized low‐density lipoprotein receptor‐1 (LOX‐1), and intercellular adhesion molecule‐1 (ICAM‐1) in aorta tissue were assessed. Serum levels of fasting blood sugar (FBS), triglyceride (TG), total cholesterol (TC), low‐density lipoprotein (LDL), TG/HDL, TC/HDL, and LDL/HDL ratios were significantly reduced in all treatment groups compared to the diabetes group. Both types of exercises, metformin, and exercise+metformin combinations, significantly reduced oxidative stress by decreasing malondialdehyde (MDA) and enhancing the antioxidant status in the aortic tissue compared to the diabetic group. In addition, in exercise groups, metformin, and combination groups, the expression of eNOS was significantly elevated, while LOX‐1 and ICAM‐1 expression significantly decreased compared to the diabetic group. In most cases, the combination of exercise and metformin (especially interval training) was more effective than exercise alone. It seems that exercise along with taking metformin can be considered as a therapeutic method by improving hyperglycemia and hyperlipidemia and reducing oxidative stress and vascular inflammatory responses, leading to ameliorating biomarkers function related to endothelial damage in experimental diabetes conditions.