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

Can circulating oxidative stress-related biomarkers be used as an early prognostic marker for COVID-19?

Oxidative stress plays an important role in the pathogenesis of many diseases. This study aimed to investigate the relationship between nuclear factor kappa B (NF-κB) and oxidative stress and the severity of the disease in new COVID-19 patients, and, to compare the levels of NF-κB, oxidized LDL (oxLDL), and lectin-like oxidized-LDL receptor-1 (LOX-1) with oxygen saturation, which is an indicator of the severity parameters of the disease in COVID-19 patients. In this prospective study, 100 COVID-19 patients and 100 healthy subjects were selected. LOX-1, NF-κB, and oxLDL were found to be higher in COVID-19 patients compared to the healthy subjects (p < 0.001 for all). According to the results of correlation analysis, it was found that there was no significant relationship between oxygen saturation and LOX-1, NF-κB and oxLDL parameters. There was significant relationship between oxLDL with LOX-1 and NF-κB in patients with COVID-19 disease. ROC analysis results of the highest discrimination power were oxLDL (AUC: 0.955, CI: 0.904-1.000; sensitivity: 77%, and specificity: 100%, for cutoff: 127.944 ng/l) indicating COVID-19. Oxidative stress plays an essential role in COVID-19. NF-κB, oxLDL, and LOX-1 seem to represent good markers in COVID-19. Our study also showed that oxLDL has the highest power in distinguishing patients with COVID-19 from the healthy subjects.

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

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 (SNABC )-in platelet activation that precedes thrombosis. Effects of abacavir or SNABC 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. 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). SNABC 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 SNABC . Neutrophils, LOX-1, P2X7, P2Y1, P2Y12 and P2X1 receptors were required for the pro-thrombotic actions of abacavir in vivo. 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.

PS-BPB01-5: LOX-1 DEFICIENCY INCREASES RUPTURED ABDOMINAL AORTIC ANEURYSM VIA THINNING OF ADVENTITIAL COLLAGEN

Objective: Lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) is a key mediator of inflammation and plays an important role in the pathogenesis of atherosclerosis. Both inflammation and atherosclerosis have been proposed as contributors to abdominal aortic aneurysm (AAA) pathogenesis. However, the role of LOX-1 in AAA pathogenesis remains unknown. We aimed to investigate effects of Olr1, which encodes LOX-1, deletion on angiotensin II (Ang II)-induced AAA in apolipoprotein E knockout (ApoE KO) mice to determine whether LOX-1 deficiency mitigates AAA development. Design and method: Either Ang II (1.44 mg/kg/day) or saline (control) was administered continuously through a subcutaneously implanted osmotic pump for 4 weeks in the following 8-week-old male mice: Apoe-/-Olr1+/+ mice (Ang II, n = 40; saline, n = 10), Apoe-/-Olr1+/- mice (Ang II, n = 30; saline, n = 9), and Apoe-/-Olr1-/- mice (Ang II, n = 39; saline, n = 9). Results: Ang II infusion raised systolic blood pressure by tail-cuff methods in all three groups. Serial non-invasive assessment with ultrasound demonstrated that Ang II gradually increased the maximum area of the suprarenal abdominal aortas leading to AAAs. Although the incidence and expansion rate of AAA were comparable among genotypes, Olr1 deletion significantly increased the severity and rupture rate of AAAs (p = 0.01; incidence of type IV and ruptured AAA was 25% in Apoe-/-Olr1-/- mice vs 5% in Apoe-/-Olr1+/+ mice). Since atherosclerosis is considered a major contributor to the development of AAAs, the extent of the atheroma burden localized in aneurysmal lesions was evaluated by Oil Red O staining. Olr1 deletion did not decrease atherosclerosis formation in the aneurysmal wall. Interestingly, further histopathological analysis revealed that aneurysmal lesions in LOX-1-deficient mice had fewer fibroblasts and myofibroblasts, as well as thinner adventitial collagen, although the degree of elastin fragmentation or disruption was similar between LOX-1-deficient and control mice. These in vivo data suggested that adventitial fibroblasts play a pivotal role in the increased severity of AAA in LOX-1-deficient mice. To further determine the effects of Olr1 deletion on fibroblast differentiation, fibroblasts were isolated from the adventitia of abdominal aortas harvested from 8-week-old Apoe-/-Olr1+/+ and Apoe-/-Olr1-/- mice, and then cultured with Ang II stimulation. An in vitro study confirmed that Olr1 deletion completely abolished the Ang II-induced proliferative activity in the aortic adventitial fibroblasts (p = 0.02). Conclusions: Olr1 deletion may not mitigate aneurysm development but rather increase the vulnerability to rupture by suppressing adventitial fibroblast proliferation and collagen.

Autophagic degradation of LOX-1 is involved in the maintenance of vascular integrity injured by oxLDL and protected by Berberine.

Damage to vascular endothelial cells (VECs) and vascular smooth muscle cells (VSMCs) caused by oxidized low-density lipoprotein (oxLDL) contributes to cardiovascular and cerebrovascular diseases. Protection effects of Berberine (BBR) on the cardiovascular system have been reported, however, the molecular mechanism of vascular protection is still unclear. In this study, we established two hyperlipidemia models in zebrafish and VEC-VSMC co-culture using high-cholesterol food (HCF) and oxLDL, respectively. We demonstrated that HCF doubled total cholesterol and total glyceride levels, and BBR decreased these indices in a concentration-dependent manner. Lipid staining and hematoxylin-eosin staining revealed that BBR inhibited oxLDL-induced VSMC bulge-like proliferation and migration toward VECs and prevented the HCF-induced trunk vascular obstruction in zebrafish. Immunoblot analysis, cell immunofluorescence, co-immunoprecipitation assays, and transmission electron microscopy showed that oxLDL/HCF increased lectin-like oxLDL receptor-1 (LOX-1) expression at least 5-fold and significantly inhibited autophagolysosome formation in the blood vessel cells and in zebrafish. These observations were associated with endothelial-to-mesenchymal transition (EMT) in VECs and triggered VE-cadherin ectopic expression in VSMCs, and they were responsible for aberrant VSMC migration and vascular occlusion. However, BBR, by promoting autolysosome formation and degradation of LOX-1, reversed the above events and maintained intracellular homeostasis of vessel cells and vascular integrity. In conclusion, regulation of autophagy may be an effective approach to treating oxLDL-induced cardiovascular diseases by reducing LOX-1 protein level. BBR can protect blood vessels by adjusting the oxLDL-LOX-1-EMT-autophagy axis. This study is a step toward the development of new applications of BBR.

TRIM59 attenuates ox-LDL-induced endothelial cell inflammation, apoptosis, and monocyte adhesion through AnxA2.

Atherosclerosis (AS), a chronic inflammatory vascular disease, is a cause of heart attack and ischemic stroke. Tripartite motif-containing protein 59 (TRIM59), a member of the tripartite motif family, has been reported to be involved in inflammatory diseases. This study was to investigate the role of TRIM59 in oxidized low-density lipoprotein (ox-LDL)-induced endothelial cells and examine the mechanism of TRIM59. To simulate a cellular model of AS in vitro, varying concentrations of ox-LDL (i.e., 20, 40, 60, 80, and 100 µg/mL) were used to treat the human umbilical vein endothelial cells (HUVECs) for 24 h. The messenger ribonucleic acid (RNA) and protein levels of TRIM59, lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1), and annexin 2 (AnxA2) were examined by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and western blot. The transfection efficacy of overexpression (Ov)-TRIM59 and small-interfering RNA-AnxA2 was examined by RT-qPCR and western blot. Cell counting kit-8 assays, lactate dehydrogenase (LDH) assays, enzyme-linked immunosorbent assays, and terminal-deoxynucleotidyl transferase mediated nick end labeling staining were used to examine viability, LDH expression, inflammation, and apoptosis in HUVECs. The protein levels of B-cell lymphoma 2, Bcl-2-associated X (BAX), cleaved caspase3, intercellular adhesion molecule 1, and vascular cell adhesion molecule 1 were assessed by western blot. Additionally, the adhesion of THP-1 to ox-LDL-induced HUVECs was detected using monocyte adhesion assays and the binding of TRIM59 and AnxA2 was verified by co-immunoprecipitation. This study showed that TRIM59 expression was decreased in the ox-LDL-induced HUVECs while LOX-1 expression was increased. After transfection with Ov-TRIM59, TRIM59 in ox-LDL-induced HUVECs was increased, and TRIM59 overexpression alleviated the viability damage, inflammation, and apoptosis of the ox-LDL-induced HUVECs. In addition, THP-1 adhesion to the ox-LDL-induced HUVECs was also suppressed by TRIM59 overexpression. This study also showed that TRIM59 could bind to AnxA2 and promote AnxA2 expression in ox-LDL-stimulated HUVECs. Moreover, the rescue experiments revealed that TRIM59 suppressed the viability damage, inflammation, apoptosis, and monocyte adhesion of the ox-LDL-induced HUVECs via AnxA2. TRIM59 protected against ox-LDL-induced AS by binding to AnxA2.

Andrographolide Attenuates Oxidized LDL-Induced Activation of the NLRP3 Inflammasome in Bone Marrow-Derived Macrophages and Mitigates HFCCD-Induced Atherosclerosis in Mice.

Andrographolide (AND) is a bioactive component of the herb Andrographis paniculata and a well-known anti-inflammatory agent. Atherosclerosis is a chronic inflammatory disease of the vasculature, and oxidized LDL (oxLDL) is thought to contribute heavily to atherosclerosis-associated inflammation. The aim of this study was to investigate whether AND mitigates oxLDL-mediated foam cell formation and diet-induced atherosclerosis (in mice fed a high-fat, high-cholesterol, high-cholic acid [HFCCD] diet) and the underlying mechanisms involved. AND attenuated LPS/oxLDL-mediated foam cell formation, IL-1[Formula: see text] mRNA and protein (p37) expression, NLR family pyrin domain containing 3 (NLRP3) mRNA and protein expression, caspase-1 (p20) protein expression, and IL-1[Formula: see text] release in BMDMs. Treatment with oxLDL significantly induced protein and mRNA expression of CD36, lectin-like oxLDL receptor-1 (LOX-1), and scavenger receptor type A (SR-A), whereas pretreatment with AND significantly inhibited protein and mRNA expression of SR-A only. Treatment with oxLDL significantly induced ROS generation and Dil-oxLDL uptake; however, pretreatment with AND alleviated oxLDL-induced ROS generation and Dil-oxLDL uptake. HFCCD feeding significantly increased aortic lipid accumulation, ICAM-1 expression, and IL-1[Formula: see text] mRNA expression, as well as blood levels of glutamic pyruvic transaminase (GPT), total cholesterol, and LDL-C. AND co-administration mitigated aortic lipid accumulation, the protein expression of ICAM-1, mRNA expression of IL-1[Formula: see text] and ICAM-1, and blood levels of GPT. These results suggest that the working mechanisms by which AND mitigates atherosclerosis involve the inhibition of foam cell formation and NLRP3 inflammasome-dependent vascular inflammation as evidenced by decreased SR-A expression and IL-1[Formula: see text] release, respectively.

PS-B12-6: OXIDIZED LDL ENHANCES AT1-GQ SIGNALING MEDIATED BY ANGIOTENSIN II THROUGH LOX-1-AT1 COMPLEX IN ADRENAL CELLS.

Objectives: Previous clinical studies have implied that dyslipidemia is associated with increase of blood pressure (BP) or the incidence of hypertension. Oxidized LDL (oxLDL), which is increased in dyslipidemia, binds to lectin-like oxLDL receptor (LOX-1), while angiotensin II (AII), which is involved in the development of hypertension, binds to AII type 1 receptor (AT1), a G protein-coupled receptor. Using vascular endothelial cells, we have shown that LOX-1 and AT1 form a complex on the plasma membrane and oxLDL activates AT1. Notably, the activation of G protein by oxLDL is partial as shown by the results that it activates Gai but not Gaq (Gq), the latter of which mediates the AII-induced BP elevation by mechanisms including the promotion of adrenal aldosterone synthesis. However, we recently found that additional treatment with oxLDL enhanced AT1-Gq signaling compared to AII alone in genetically engineered-Chinese hamster ovary cells expressing both AT1 and LOX-1. In the present study, we examined whether oxLDL enhances AII-Gq signaling in aldosterone-producing adrenal cells, in order to strengthen the hypothesis that oxLDL potentiates AII-induced aldosterone production. Design and Methods: H295R, human adrenal gland carcinoma cell line were treated with oxLDL, AII, or both. Gq-dependent activation of phospholipase C was quantified by measurement of inositol monophosphate (IP1) using the IP-One assay kit. When necessary, cells were pretreated with YM-254890, a Gq inhibitor or siRNA of AT1 or LOX-1. Gq-dependent activation of Ca2+ influx was quantified by measurement of intracellular Ca2+ concentrations using the Fura-2 Ca assay kit. Results: The IP1 assay showed that oxLDL additively increases AII-mediated IP1 production compared to AII alone. Pretreatment of Gq inhibitor or siRNA of AT1 completely abolished and siRNA of LOX-1 partially abolished the activation of AT1-Gq signaling by the combination of oxLDL and AII. In the Fura-2 Ca assay, although AII at concentrations as low as 10–11 M and oxLDL alone did not activate Ca influx, the combination of oxLDL and AII vigorously induced the phenomenon. Conclusions: These results suggest that oxLDL potentiates AII-Gq signaling via a pathway depending on the LOX-1-AT1 interaction in adrenal cells. Further investigation will be required to elucidate if this phenomenon contributes to enhanced production of aldosterone both in vitro and in vivo.

Gene Expression Profiling of Peripheral Blood Mononuclear Cells in Type 2 Diabetes: An Exploratory Study.

Background and Objectives: Visceral obesity is associated with chronic low-grade inflammation that predisposes to metabolic syndrome. Indeed, infiltration of adipose tissue with immune-inflammatory cells, including 'classical' inflammatory M1 and anti-inflammatory 'alternative' M2 macrophages, causes the release of a variety of bioactive molecules, resulting in the metabolic complications of obesity. This study examined the relative expression of macrophage phenotypic surface markers, cholesterol efflux proteins, scavenger receptors, and adenosine receptors in human circulating peripheral blood mononuclear cells (PBMCs), isolated from patients with type 2 diabetes mellitus (T2DM), with the aim to phenotypically characterize and identify biomarkers for these ill-defined cells. Materials and Methodology: PBMCs were isolated from four groups of adults: Normal-weight non-diabetic, obese non-diabetic, newly diagnosed with T2DM, and T2DM on metformin. The mRNA expression levels of macrophage phenotypic surface markers (interleukin-12 (IL-12), C-X-C motif chemokine ligand 10 (CXCL10), C-C motif chemokine ligand 17 (CCL17), and C-C motif receptor 7 (CCR7)), cholesterol efflux proteins (ATP-binding cassette transporter-1 (ABCA1), ATP binding cassette subfamily G member 1 (ABCG1), and sterol 27-hydroxylase (CYP27A)), scavenger receptors (scavenger receptor-A (SR-A), C-X-C motif ligand 16 (CXCL16), and lectin-like oxidized LDL receptor-1 (LOX-1)), and adenosine receptors (adenosine A2A receptor (A2AR) and adenosine A3 receptor (A3R)) were measured using qRT-PCR. Results: In PBMCs from T2DM patients, the expression of IL-12, CCR7, ABCA1, and SR-A1 was increased, whereas the expression of CXCL10, CCL17, ABCG1,27-hydroxylase, LOX-1, A2AR and A3R was decreased. On the other hand, treatment with the antidiabetic drug, metformin, reduced the expression of IL-12 and increased the expression of 27-hydroxylase, LOX-1, CXCL16 and A2AR. Conclusions: PBMCs in the circulation of patients with T2DM express phenotypic markers that are different from those typically present in adipose tissue M1 and M2 macrophages and could be representative of metabolically activated macrophages (MMe)-like cells. Our findings suggest that metformin alters phenotypic markers of MMe-like cells in circulation.

MiR-186-5p Dysregulation in Serum Exosomes from Patients with AMI Aggravates Atherosclerosis via Targeting LOX-1.

The formation of macrophage-derived foam cells via the uptake of modified lipoproteins is a pivotal development event in atherosclerosis. It has been reported that clinical and experimental myocardial infarction could accelerate atherosclerosis. Several studies have suggested the critical role of exosomes in cardiovascular diseases. However, the role of exosomes from patients with acute myocardial infarction (AMI) patients in atherogenesis remains unclear. Serum exosomes from AMI patients (AMI-Exo) and control individuals (Con-Exo) were isolated and characterized. These exosomes were studied in vitro and in vivo to determine their impact on macrophage foaming and atherogenesis. Our results showed that AMI-Exo promoted foam cell formation in oxidized low-density lipoprotein (ox-LDL)-treated macrophages and progression of atherosclerosis in high-fat/cholesterol diet-fed ApoE-/- mice together with a significantly upregulated levels of lectin-like ox-LDL receptor-1 (LOX-1). The miR-186-5p was found to be downregulated in AMI-Exo and macrophages administered with AMI-Exo. Moreover, serum exosomal miR-186-5p achieved high diagnostic performance for AMI. Luciferase reporter assay indicated that miR-186-5p directly inhibited LOX-1. The endogenous or exogenous miR-186-5p deficiency enhanced lipid accumulation by upregulating LOX-1, whereas miR-186-5p mimics had a reverse effect. In conclusion, the current findings suggest that dysregulated miR-186-5p in AMI-Exo may explain the contribution of acute ischemia events to the advancement of atherosclerosis by enhancing macrophage foaming via its target, LOX-1.

LOX-1 attenuates high glucose-induced autophagy via AMPK/HNF4α signaling in HLSECs

Type 2 diabetes mellitus (T2DM) combined with nonalcoholic fatty liver disease (NAFLD) is a common cause of death. Lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) is involved in the regulation of autophagy and associated with a variety of diseases, such as atherosclerosis, diabetes, and NAFLD. This study aimed to investigate the effect of LOX-1 on autophagy induced by high glucose levels in human liver sinusoidal endothelial cells (HLSECs) and whether it regulates autophagy through the adenosine monophosphate-activated protein kinase/hepatocyte nuclear factor 4α (AMPK/HNF4α) pathway. In this study, HLSECs cultured with high glucose medium showed increased expression of LOX-1, whereas autophagy was inhibited. High glucose levels decreased the AMPK phosphorylation, increased the HNF4α phosphorylation, and retained the HNF4α in the cytoplasm. By contrast, silencing of LOX-1 reversed the phenomenon induced by high glucose levels and restored the HNF4a localization. Taken together, our findings reveal a novel mechanism of high glucose-induced autophagy in HLSECs, namely, the LOX-1-mediated AMPK/HNF4α signaling pathway. Therefore, LOX-1 is an important target molecule for the regulation of autophagy in HLSECs.

Plasma exosomes confer hypoxic pulmonary hypertension by transferring LOX-1 cargo to trigger phenotypic switching of pulmonary artery smooth muscle cells

The pulmonary vascular remodeling (PVR), the pathological basis of pulmonary hypertension (PH), entails pulmonary artery smooth muscle cells (PASMCs) phenotypic switching, but appreciation of the underlying mechanisms is incomplete. Exosomes, a novel transfer machinery enabling delivery of its cargos to recipient cells, have been recently implicated in cardiovascular diseases including PH. The two critical questions of whether plasma-derived exosomes drive PASMCs phenotypic switching and what cargo the exosomes transport, however, remain unclear. Herein, by means of transmission electron microscopy and protein detection, we for the first time, characterized lectin like oxidized low-density lipoprotein receptor-1 (LOX-1) as a novel cargo of plasma-derived exosomes in PH. With LOX-1 knockout (Olr1-/-) rats-derived exosomes, we demonstrated that exosomal LOX-1 could be transferred into PASMCs and thus elicited cell phenotypic switching. Of importance, Olr1-/- rats exhibited no cell phenotypic switching and developed less severe PH, but administration of wild type rather than Olr1-/- exosomes to Olr1-/- rats recapitulated the phenotype of PH with robust PASMCs phenotypic switching. We also revealed that exosomal LOX-1 triggered PASMCs phenotypic switching, PVR and ultimately PH via ERK1/2-KLF4 signaling axis. This study has generated proof that plasma-derived exosomes confer PH by delivering LOX-1 into PASMCs. Hence, exosomal LOX-1 represents a novel exploitable target for PH prevention and treatment.

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

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. 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. 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. 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.

LOX-1 deficiency increases ruptured abdominal aortic aneurysm via thinning of adventitial collagen.

Lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) is a key mediator of inflammation and plays an important role in the pathogenesis of atherosclerosis. Conversely, LOX-1 deficiency has been shown to decrease inflammation and atherosclerosis, both of which have been proposed to contribute to abdominal aortic aneurysm (AAA) pathogenesis. However, the role of LOX-1 in AAA pathogenesis remains unknown. Here, we investigated the effects of Olr1 (which encodes LOX-1) deletion on angiotensin II (Ang II)-induced AAA in apolipoprotein E knockout (ApoE KO) mice to determine whether LOX-1 deficiency mitigates AAA development. To accomplish this, we used serial, non-invasive ultrasound assessment, which revealed that the incidence and expansion rate of AAA were similar regardless of Olr1 deletion. However, Olr1 deletion significantly increased severe AAAs, including ruptured AAAs resulting in death. Oil Red O staining of the harvested aortas showed that the extent of atheroma burden localized in aneurysmal lesions did not differ between LOX-1-deficient and control mice, suggesting that Olr1 deletion did not decrease atheroma burden in the aneurysmal wall. Further histopathological analysis revealed that aneurysmal lesions in LOX-1-deficient mice had fewer fibroblasts and myofibroblasts, as well as thinner adventitial collagen, although the degree of elastin fragmentation or disruption was similar between LOX-1-deficient and control mice. An in vitro study confirmed that the proliferation of adventitial fibroblasts collected from LOX-1-deficient mice was significantly attenuated despite Ang II stimulation. In conclusion, Olr1 deletion may not mitigate aneurysm development but rather increases the vulnerability of rupture by suppressing adventitial fibroblast proliferation and collagen synthesis.

LOX-1 Regulation in Anti-atherosclerosis of Active Compounds of Herbal Medicine: Current Knowledge and the New Insight.

Lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) have recently been identified to be closely related to the occurrence and development of atherosclerosis (AS). A growing body of evidence has suggested Chinese medicine takes unique advantages in preventing and treating AS. In this review, the related research progress of AS and LOX-1 has been summarized. And the anti-AS effects of 10 active components of herbal medicine through LOX-1 regulation have been further reviewed. As a potential biomarker and target for intervention in AS, LOX-1 targeted therapy might provide a promising and novel approach to atherosclerotic prevention and treatment.

Early Mid-pregnancy Blood-Based Proteins as Possible Biomarkers of Increased Infant Birth Size in Sex-Stratified Analyses

The objective of this study was to evaluate the associations of 92 maternal blood-based proteins with increased infant birth size. The study was performed at the Uppsala University Hospital, Sweden, and included 857 mother and child dyads. The mean age of the women was 30.3 years, and 53.2% were nulliparous. Blood samples were collected at mean 18 + 2 weeks’ gestation, and the Olink cardiovascular II panel was used to measure 92 proteins, either known to be or suspected to be markers of cardiovascular and inflammatory disease in humans. Multiple linear regression models adjusted for maternal age, parity, pre-conception BMI, height, and smoking were performed to evaluate the association of each individual protein with infant birth size. We also performed sex-stratified analyses. Eight proteins (Matrix metalloproteinase-12 (MMP-12), Prostasin (PRSS8), Adrenomedullin (ADM), Pappalysin-1 (PAPP-A), Angiotensin-converting enzyme 2 (ACE2), Sortilin (SORT1), Lectin-like oxidized LDL receptor 1 (LOX-1), and Thrombomodulin (TM)) were associated with infant birth size after false discovery rate adjustment. In the analyses including only female infants, ten proteins (MMP-12, Growth/differentiation factor 2 (GDF-2), PRSS8, SORT1, ADM, Interleukin-1 receptor antagonist protein (IL-1ra), Leptin (LEP), ACE2, TM, and Tumor necrosis factor receptor superfamily member 11A (TNFRSF11A)) were associated with infant birth size. Two proteins (PAPP-A and PRSS8) were associated with infant birth size among male infants. Our study suggests several proteins as potential biomarkers for increased birth weight, and our findings could act as a base for future research to identify new potential markers that could be added to improve screening for large infants.

Mechanism of antifungal activity and therapeutic action of β-ionone on Aspergillus fumigatus keratitis via suppressing LOX1 and JNK/p38 MAPK activation

PurposeTo investigate the anti-inflammatory and antifungal role of β-ionone (BI) in fungal keratitis (FK). MethodsIn vitro antifungal activity of BI against Aspergillus fumigatus (A. fumigatus) was evaluated by using minimum inhibitory concentration (MIC), crystal violet staining, biofilm biomass measurement, propidium iodide uptake test, and adherence assay. And RT-PCR was carried out to measure the levels of RodA, RodB, Rho, FKs, CshA-D, RlmA, Cyp51A-B and Cdr1B. Network pharmacology analysis was applied to predict the relationship between BI and FK. Cell Count Kit-8 (CCK8) assay was utilized to detect the cytotoxicity of BI to RAW264.7 and immortalized human corneal epithelial cells (HCECs). The underlying mechanism of BI at regulating the level of inflammatory factors in FK was assessed by RT-PCR, ELISA and Western blot in vitro and in vivo. The therapeutic effect of BI has investigated in A. fumigatus keratitis by employing the clinical score, pathological examination, plate count, immunofluorescence and myeloperoxidase (MPO) assay. We also used the slit-lamp microscopy, clinical scores, and HE staining to assess the effect of natamycin compared with BI treatment in vivo. ResultsBI suppressed the growth of A. fumigatus and had a significant effect on A. fumigatus biofilms and membrane permeability. RT-PCR demonstrated that exposure of A. fumigatus to BI inhibited the expression of genes that function in hydrophobin (RodA, RodB), cell wall integrity (Rho, FKs, CshA-D, RlmA), azole susceptibility (Cyp51A-B, Cdr1B). Network pharmacology showed that the effects of BI in FK implicate with C-type lectin receptor signaling pathway. In vivo, after A. fumigatus infection, BI treatment markedly reduced the severity of FK by decreasing clinical score, neutrophil recruitment, and fungal load. And BI treatment also obviously reduced the expression of inflammatory cytokines, Lectin-like oxidized LDL receptor (LOX-1), phosphorylation of p38MAPK and p-JNK versus the DMSO-treated group. BI and natamycin both significantly increased corneal transparency and decreased inflammatory cell recruitment in the FK in the mice model. ConclusionThese results indicated that BI had fungicidal activities against A. fumigatus. It also ameliorated FK in mice by reducing inflammation, which was regulated by LOX-1, p-p38MAPK and p-JNK.

LDL oxydées et récepteur des LDL oxydées associés à la proprotéine-convertase-subtilisine/kexine type 9 chez des patients avec diabète de type 2

AbstractProprotein Convertase Subtilisin/Kexin type 9 (PCSK9) plays a key role in the regulation of lipid metabolism, in inflammatory response and in the development of atherosclerosis. We evaluated plasma PCSK9 levels in Tunisian patients with type 2 diabetes mellitus (T2DM) and investigated its association with oxidized-LDL (Ox-LDL) and Lectin-Like Oxidized LDL Receptor-1 (LOX-1 ). Plasma PCSK9, Ox- LDL and LOX-1 levels were measured in a Tunisian cohort of patients with T2DM (n = 50) compared to an age- and gender-matched control group (n = 50). Plasma levels of PCSK9, Ox-LDL and LOX-1 were significantly higher in T2DM patients compared to controls (p < 0.0001). Univariate regression analysis showed that the plasma level of PCSK9 was positively associated to Ox-LDL and LOX-1 levels in diabetic patients (p = 0.004 ; p = 0.012; respectively); however, no-independent association was found after multiple linear regression analysis between those parameters. Our data showed that PCSK9 was positively associated to Ox-LDL and LOX-1 showing as specific regulation between the oxidative parameters and an enzyme regulating lipid metabolism. These results attest the impact of PCSK9 to develop atherosclerosis in T2DM in a Tunisian cohort. Finally, PCSK-9 could be a new marker of the development of atherosclerosis in diabetic patients.

The oxidized-LDL/LOX-1 axis in tumor endothelial cells enhances metastasis by recruiting neutrophils and cancer cells.

Epidemiological relationships between cancer and cardiovascular diseases have been reported, but a molecular basis remains unclear. Some proteoglycans that strongly bind low-density-lipoprotein (LDL) are abundant both in atherosclerotic regions and in high metastatic-tumor tissue. LDL retention is crucial for the initiation of atherosclerosis, although its contribution to malignancy of cancer is not known. In our study, we show the importance of the accumulation of LDL in tumor metastasis. We demonstrated that high metastatic-tumor tissue contains high amounts of LDL and forms more oxidized LDL (ox-LDL). Interestingly, lectin-like ox-LDL receptor 1 (LOX-1), a receptor for ox-LDL and a recognized key molecule for cardiovascular diseases, was highly expressed in tumor endothelial cells (TECs). Neutrophils are important for ox-LDL formation. Since we observed the accumulation and activation of neutrophils in HM-tumors, we evaluated the involvement of LOX-1 in neutrophil migration and activation. LOX-1 induced neutrophil migration via CCL2 secretion from TECs, which was enhanced by ox-LDL. Finally, we show genetic manipulation of LOX-1 expression in TECs or tumor stroma tended to reduce lung metastasis. Thus, the LOX-1/ox-LDL axis in TECs may lead to the formation of a high metastatic-tumor microenvironment via attracting neutrophils.

Anti-atherosclerotic effects of genistein in preventing ox-low-density lipoprotein-induced smooth muscle-derived foam cell formation via inhibiting SRC expression and L-Ca channel currents.

BackgroundAtherosclerosis (AS) is associated with inflammation and abnormal proliferation and migration of vascular smooth muscle cells (VSMCs). Genistein may curtail the migration of VSMCs. Therefore, explorations are required to determine the molecular mechanism of genistein in AS. In this context, animal and cell models were developed to ascertain mechanisms of genistein in AS by modulating VSMC activities.MethodsGenistein treatment and ectopic expression of lectin-like oxidized LDL receptor-1 (LOX-1) were conducted in high-fat diet-induced AS rats, followed by analyses of atherosclerotic plaque lesion areas and lipid deposition using Oil Red O and hematoxylin and eosin (HE) staining. The isolated VSMCs were stimulated with oxidized low-density lipoprotein (ox-LDL). Following genistein treatment combined with gain- and loss-of-function experiments in ox-LDL-exposed VSMCs, viability, migration, intracellular lipid deposition, intracellular cholesterol content, and L-type calcium (L-Ca) channel currents were assessed using Cell Counting Kit-8 (CCK-8), scratch test, Oil Red O staining, enzymatic colorimetry, and patch-clamp experiments, respectively. Western blot analysis was performed to evaluate the protein expression of SRC proto-oncogene, non-receptor tyrosine kinase (SRC), calcium voltage-gated channel subunit alpha1 C (CACNA1C), and LOX-1.ResultsGenistein treatment counteracted upregulated SRC phosphorylation, CACNA1C and LOX-1 expression, and L-Ca channel currents in aortic tissues of AS rats and ox-LDL-exposed VSMCs. Genistein deceased L-Ca channel currents by downregulating SRC, and SRC augmented LOX-1 expression by acting on the L-Ca channel subunit CACNA1C. The ox-LDL-induced VSMC proliferation, migration, and foaming of VSMCs were reduced by genistein treatment, silencing SRC, CACNA1C, or LOX-1, or suppressing L-Ca channels. Genistein treatment diminished atherosclerotic plaque lesion formation and lipid deposition, and these results were annulled by upregulating LOX-1.ConclusionsCollectively, genistein might block the SRC/CACNA1C/LOX-1 axis to impede ox-LDL-induced VSMC proliferation, migration, and foaming and alleviate AS formation.

OxLDL Mediates Brain Vascular Smooth Muscle Cell LOX‐1 Splicing, Oxidative Stress, and Inflammation Following Ischemic‐like Injury

A critical risk factor known to mediate vascular injury and found to be clinically correlated with acute ischemic stroke is elevated oxidized low‐density lipoprotein (OxLDL) levels. OxLDL, via the lectin‐like OxLDL receptor 1 (LOX‐1), has been shown to alter vascular wall function in part by mediating mechanisms associated with oxidative stress and inflammation. LOX‐1 is characterized by three alternative splice variants. Variant (V)1 corresponds to the full‐length protein that is able to bind OxLDL; whereas, this binding activity is disrupted in V2 and V3. LOX‐1 splice variant characterization as well as mediators of inflammation and oxidative stress in the cerebrovasculature has yet to be addressed following OxLDL exposure alone or in the context of acute ischemic injury. Therefore, we investigated the expression profile of LOX‐1 (V1, 2, 3), proinflammatory mediators (PTGS2, IL‐1β), and oxidative stress mediator (SOD1) in primary male human brain vascular smooth muscle cells (VSMCs) following an in vitro acute ischemic injury (HGD; hypoxia plus glucose depravation) ± OxLDL. We hypothesized that HGD would alter LOX‐1 variant expression as well as induce a proinflammatory and oxidative stress response that would be exacerbated by OxLDL via LOX‐1 receptor. VSMCs were preconditioned with human OxLDL (50 and 25μg/dL; 12h) or vehicle. Next VSMCs were treated with BI‐0115 (selective LOX‐1 inhibitor; 10 μM) or vehicle (&lt;0.1% DMSO) for 0.5h prior to being exposed to normoxia (21% O2) or HGD (1% O2) for 6h in the continued presence of OxLDL or vehicle. LOX‐1 variants were visualized using semi‐quantitative RT‐PCR analysis. PTGS2, IL‐1β, and SOD1 gene expression were assessed using quantitative real time‐PCR. COX‐2 glycosylation (active form) was measured via western blotting and used as a functional proinflammatory outcome. VSMCs exhibited a differential expression profile of the LOX‐1 variants under normoxia: V1 &gt; V3 &gt; V2. OxLDL alone increased V1 expression, had no effect on V2 levels, and increased V3 expression in a dose dependent manner. Following HGD, we observed a decrease in V1 expression with no change in V2 or V3 in comparison to normoxia. HGD plus OxLDL increased V1 and V2 expression; however, V2 expression was OxLDL dose dependent. Similarly, V3 expression was increased, however only at OxLDL 50 μg/dL in comparison to HGD alone. We next observed that HGD increased PTGS2, IL‐1β, and SOD1 mRNA expression, while OxLDL alone increased IL‐1β and SOD1 in a dose and LOX‐1 receptor dependent manner. Paradoxically HGD plus OxLDL decreased levels of IL‐1β and SOD1 in a LOX‐1 dependent manner. Moreover, LOX‐1 inhibition as well as OxLDL alone decreased levels of PTGS2 compared to HGD plus vehicles. Finally, we observed that HGD and OxLDL individually increased COX‐2 glycosylation, suggesting enzyme activation. In conclusion, the beneficial down‐regulation of LOX‐1 V1 by HGD was attenuated by the presence of OxLDL, suggesting that the combinatory effect predisposes the cerebrovasculature to an increased OxLDL/LOX‐1 response during acute ischemic stroke. Furthermore, LOX‐1 inhibition and the resulting attenuation of OxLDL‐mediated increases in VSMC IL‐1β and SOD1 transcription suggests that LOX‐1 may be a potential therapeutic target for patients with a higher risk of stroke.