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

LOX-1 expression is reduced in placenta from pregnancies complicated by preeclampsia and in hypoxic cytotrophoblast.

The lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) is upregulated in the maternal vasculature in preeclampsia, and contributes to oxidative stress and endothelial dysfunction. However, its function in the placenta is unclear. This paper investigated LOX-1 expression in models of placental dysfunction and preeclampsia, and whether candidate therapeutics for preeclampsia could alter its expression. Placentas were collected from preterm pregnancies and cases of preterm preeclampsia and fetal growth restriction. Blood was collected from participants whose pregnancies were complicated by preterm fetal growth restriction and/or preeclampsia. Primary cytotrophoblast and placental explant tissue were cultured under hypoxic (1% O2) or normoxic (8% O2) conditions. Cytotrophoblast were exposed to 10% preeclamptic or control serum. Cytotrophoblast and preeclamptic explant tissue were treated with 100µM esomeprazole, lansoprazole or rabeprazole. LOX-1 expression was assessed in all samples via qPCR. LOX-1 expression was reduced in placentas from cases of preterm preeclampsia, but not fetal growth restriction, compared to controls. LOX-1 expression was reduced in cytotrophoblast under hypoxia, but not in explant tissue. Treatment with preeclamptic serum in vitro did not alter cytotrophoblast LOX-1 expression. Circulating LOX-1 mRNA was unaltered in patients with fetal growth restriction, preeclampsia, and fetal hypoxia, compared to controls. Treatment with esomeprazole or lansoprazole in vitro increased placental LOX-1 expression. LOX-1 expression is reduced in preeclamptic placentas and hypoxic cytotrophoblast. Esomeprazole and lansoprazole increase placental LOX-1 expression. These findings demonstrate a role for LOX-1 in the placenta, and improve our understanding of maternal adaptations in pregnancy complications.

Double ‐ Stranded RNA Analog Poly I:C Enhances the Expression of Lectin‐Like Oxidized LDL Receptor‐1 in Macrophages: Role of ERK1/2 Signaling

We previously reported that bacterial lipopolysaccharide (LPS) enhanced the expression of lectin-like oxidized LDL receptor-1 (LOX-1) in macrophages through activation of the ERK1/2 signaling, thereby enhancing the cellular uptake of ox-LDL. Polyinosinic:polycytidylic acid (Poly I:C), a synthetic analog of double-stranded RNA (dsRNA), which activates various cell signaling via TLR3, has been shown to accelerate atherosclerotic lesions in multiple animal models. However, the underlying molecular mechanism mediating this response is obscure. Therefore, the present study aimed to investigate whether or not Poly I:C affects the expression of LOX-1 and explore the underlying molecular mechanisms. In RAW 264.7 macrophages, Poly I: C stimulation dose- and time-dependently enhanced the expression of LOX1. Although Poly I:C induced the activation of MAP kinases (p38, JNK1/2, ERK1/2), AP1 (c-FOS/JUN), and NF-kB signaling molecules, a specific ERK1/2 inhibitor (U0128) effectively inhibited the upregulation of LOX-1. Additionally, transient knockdown of ERK1/2 by small interference RNA prevented Poly I:C-induced overexpression of LOX1. Poly I:C stimulation augmented LOX-1 promoter activity, which is also inhibited by U0126 treatment. Similar results were also observed in human PMA-induced THP-1 human macrophages. Overall, we sought that Poly I:C, a viral mimic, upregulates the expression of LOX-1 through activation of the ERK1/2 signaling, highlighting a critical role of TLR3-mediated impaired LOX-1 signaling in the pathogenesis of atherosclerosis.

Effect of Candesartan Combined with Rosuvastatin on Myocardial Fibrosis in Rats with Alcoholic Cardiomyopathy by Mediating LOX-1 Expression

Objective: To analyze the effect of candesartan and rosuvastatin on myocardial fibrosis in rats with alcoholic cardiomyopathy by mediating the expression of lectin-like oxidized low-density lipoprotein receptor-1(LOX-1). Methods: The rats were selected as experimental samples, and these rats were randomly divided into observation group and alcohol feeding group (abbreviated as "alcohol group") and desartan combined with rosuvastatin intervention + alcoholic cardiomyopathy group (Referred to as the "intervention group"), the observation group is fed normally, the alcohol group is fed with alcohol, and the intervention group uses two drugs on the basis of the alcohol group to intervene. After 16 weeks of the three groups of experiments, analyze the results of the three groups of experiments. Myocardial structure, myocardial fibrosis and myocardial function. Results: After 16 weeks, the left ventricular short axis shortening rate (FS) and left ventricular ejection fraction in the alcohol group were lower than those in the observation group, while the collagen volume fraction (CVF) and left ventricular end-diastolic diameter (LVEDd) were higher than those in the observation group. The expression of LOX-1 in the intervention group was lower than that in the alcohol group, and the degree of fibrosis was reduced. The expression of LOX-1 in the alcohol group was higher than that in the observation group, and the degree of fiber increased. At the same time, the expression of TN-X and smad-3 protein in the alcohol group (86%± 7%, 83%±9%) were higher than those in the observation group (32%±10%, 30%±7%), while the expression of smad-7 protein (36%±8%) was lower than that in the observation group (78%± 9%), P<0.05 among the three groups of experiments, and there is statistical significance among the groups. Conclusion: Candesartan combined with Rosuvastatin can reduce myocardial fibrosis in rats with alcoholic cardiomyopathy by mediating the expression of LOX-1.

Oxidized low-density lipoprotein stimulates dendritic cells maturation via LOX-1-mediated MAPK/NF-κB pathway.

Dendritic cells (DCs) play a crucial role as central orchestrators of immune system response in atherosclerosis initiation and progression. Lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) is involved in the immune maturation of DCs, but the underlying mechanisms remain unclear. We isolated mouse bone marrow progenitors and stimulated them with granulocyte-macrophage colony-stimulating factor and interleukin (IL)-4 to induce immature DCs. We then treated DCs with oxidized low-density lipoprotein (oxLDL) to induce maturation. LOX-1 siRNA was used to investigate the modulation of LOX-1 on the development of DCs and the underlying signal pathways. CD11c-positive DCs were successfully derived from mouse bone marrow progenitors. OxLDL promoted the expressions of DCs maturation markers and pro-inflammatory cytokines. OxLDL also upregulated LOX-1 expression and activated MAPK/NF-κB pathways. LOX-1 siRNA could attenuate the expression of MAPK/NF-κB pathways and inflammatory cytokines. In conclusion, oxLDL induced the maturation of DCs via LOX-1-mediated MAPK/NF-κB pathway, which contributed to the initiation and progression of atherosclerosis.

Normal and reconstituted high-density lipoprotein protects differentiated monocytes from oxidized low-density lipoprotein-induced apoptosis.

BACKGROUNDThe progression of atherosclerosis is an ongoing struggle between cell division and cell death. Lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1), a novel receptor for oxidized low-density lipoprotein (ox-LDL), mediates ox-LDL-induced apoptosis of monocytes. The anti-atherogenic function of plasma high-density lipoprotein (HDL) includes the ability to inhibit apoptosis of macrophage, although the exact mechanism and consequences of apoptosis in the development and progression of this disease are still controversial. Thus, in the present study, the effect of normal HDL (nHDL) and reconstituted HDL (rHDL) on ox-LDL-induced cellular responses in differentiated monocytes in view of apoptosis and LOX-1 receptor expression was investigated.METHODSThe expression of B-cell lymphoma-2 (Bcl-2), B-cell lymphoma-extra large (Bcl-xL), caspase-3, and cytochrome c (cyt c) was assessed and substantiated in 30 hyper-LDL and control subjects. To assess the expression of LOX-1 on differentiated THP-1 cells, western blotting was carried out, followed by statistical analysis in 30 patients and control subjects.RESULTSnHDL/rHDL inhibited the ox-LDL-induced apoptosis in the differentiated human monocytic cells, THP-1 cells, and differentiated monocytes of patient and control subjects. Enhanced expression of scavenger receptor, LOX-1, in the differentiated monocytes was also downregulated in presence of nHDL/rHDL. nHDL/rHDL could inhibit the ox-LDL-induced mitochondrial apoptotic pathway and aberrant expression of LOX-1 in patients. Double immunostaining using fluorescein isothiocyanate (FITC)-conjugated ox-LDL and LOX-1 in apoptotic cells indicates its significant role in the differentiated monocytes.CONCLUSIONIt was observed that nHDL/rHDL could promote macrophage survival by preserving mitochondrial integrity from ox-LDL-induced apoptosis.

Decidua-derived granulocyte macrophage colony-stimulating factor induces polymorphonuclear myeloid-derived suppressor cells from circulating CD15+ neutrophils.

Do decidua-derived factors stimulate the conversion of circulating neutrophils to polymorphonuclear myeloid-derived suppressor cells (PMN-MDSCs) in early human pregnancy? Circulating neutrophils can acquire PMN-MDSC-like phenotypes and function via phosphorylated signal transducer and activator of transcription 5/programmed death ligand 2 (pSTAT5/PD-L2) signalling after stimulation with decidua-derived granulocyte macrophage colony-stimulating factor (GM-CSF). PMN-MDSCs are an important immunoregulatory cell type in early pregnancy. Neutrophils are of high heterogeneity and plasticity and can polarize to immunosuppressive PMN-MDSCs upon stimulation. For analysis of myeloid-derived suppressor cell (MDSC) subset proportions, 12 endometrium tissues and 12 peripheral blood samples were collected from non-pregnant women, and 40 decidua tissues and 16 peripheral blood samples were obtained from women with normal early pregnancy undergoing elective surgical pregnancy termination for nonmedical reasons with gestation age of 6-10 weeks. Twenty-nine decidua tissues were collected for isolation of CD15+ PMN-MDSCs. Twenty endometrium tissues and 30 decidua tissues were collected for cytokine analysis, immunohistochemistry or neutrophil stimulation. Peripheral blood samples were obtained from 36 healthy donors for isolation of CD3+ T cells and CD15+ neutrophils. The proportion of MDSC subsets in the decidua and peripheral blood of normal early pregnancy, endometrium and peripheral blood of non-pregnant women was analysed by flow cytometry. The phenotypes and function of decidual PMN-MDSCs and circulating neutrophils were compared by flow cytometry. Circulating neutrophils were stimulated with decidual explant supernatant (DES) and the phenotypes were measured by flow cytometry and immunofluorescence. The suppressive capacity of decidual PMN-MDSCs and DES-conditioned neutrophils was analysed by flow cytometry with or without anti-programmed cell death-1 (PD-1) antibody. Cytokines from DES and endometrial explant supernatant (EES) were detected by a Luminex assay. GM-CSF expression was determined by ELISA and immunohistochemistry. Neutrophils were stimulated with DES, EES, DES with anti-GM-CSF antibody or EES with GM-CSF. CD11b, lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1), PD-L2 and pSTAT5 expression were measured by flow cytometry. The frequency of PMN-MDSCs was significantly increased in the decidua of early pregnancy compared with peripheral blood of non-pregnant women, the endometrium of non-pregnant women or peripheral blood during early pregnancy. Decidual PMN-MDSCs suppressed T-cell proliferation and cytokine production. Phenotypes of decidual PMN-MDSCs were similar to mature activated neutrophils. DES-induced CD11b, LOX-1, PD-L2 expression and STAT5 phosphorylation in neutrophils. The PD-L2 expression in neutrophils was dependent on STAT5 phosphorylation. Both decidual PMN-MDSCs and DES-conditioned neutrophils suppressed T-cell proliferation via PD-1 signalling. GM-CSF was up-regulated in the decidua and induced CD11b, LOX-1 and PD-L2 expression on neutrophils. DES significantly induced CD11b, LOX-1, PD-L2 expression and STAT5 phosphorylation. Anti-GM-CSF antibody remarkably blocked such stimulation in neutrophils. EES did not induce CD11b, LOX-1, PD-L2 expression or STAT5 phosphorylation, while GM-CSF treatment sufficiently stimulated CD11b, LOX-1, PD-L2 expression and STAT5 phosphorylation in neutrophils. N/A. The study was based on in vitro experiments and we were not able to evaluate neutrophils differentiation to PMN-MDSCs in other sites before entering the maternal-foetal interface due to the limited availability of human samples. This needs to be explored using murine models. This is the first study demonstrating that decidual PMN-MDSCs are a group of immunoregulatory cells with mature status, and that neutrophils can be induced to a PMN-MDSC-like phenotype with decidua-derived GM-CSF via pSTAT5/PD-L2 signalling. This study indicates that GM-CSF can facilitate immune tolerance of early pregnancy through regulating PMN-MDSCs and further provides a potential role of GM-CSF in prevention and treatment for pregnancy complications. This work was supported by the National Natural Science Foundation of China (81671481) and National Natural Science Foundation of China (81871179). All authors have no competing interests to declare.

N-3 PUFAs inhibited hepatic ER stress induced by feeding of a high-saturated fat diet accompanied by the expression LOX-1

Excessive consumption of saturated fat leads to non-alcoholic fatty liver disease (NAFLD), which is attenuated by supplementation of n-3 polyunsaturated fatty acids (PUFAs). Endoplasmic reticulum (ER) stress is crucial in the development of NAFLD, but how high-saturated fat diet (HFD) causes ER stress and NAFLD remains unclear. Lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) is involved in hepatic ER stress. We aimed to explore the roles of LOX-1 in HFD-induced ER stress. Male Sprague–Dawley rats were fed an HFD without or with supplementation of fish oil for 16 weeks. The effects of n-3 PUFAs on hepatic ER stress degrees and the expression levels of LOX-1 were examined. Then human L02 hepatoma cells were treated with palmitate or palmitate and DHA to determine the ER stress and LOX-1 expression levels in vitro. After that the expression of LOX-1 in L02 cells was either knocked-down or overexpressed to analyze the roles of LOX-1 in palmitate-induced ER stress. The feeding of HFD induced NAFLD development and ER stress in the liver, and LOX-1 expressing level, which were all reversed by fish oil supplementation. In vitro, DHA treatment reduced the expression of LOX-1, and palmitate-induced ER stress. SiRNA-mediated knock-down of LOX-1 inhibited palmitate-induced ER stress, whereas overexpression of LOX-1 dramatically induced ER stress in L02 cells.LOX-1 is critical for HFD-induced ER stress, and inhibition of its expression under the treatment of n-3 PUFAs could ameliorate HFD-induced NAFLD.

Baicalein exerts neuroprotective effect against ischaemic/reperfusion injury via alteration of NF-kB and LOX and AMPK/Nrf2 pathway.

ischaemic stroke accounts for almost 11% of all deaths worldwide and has a high incidence of permanent disability among patients. Baicalein has many beneficial pharmacological properties, including anti-inflammatory and anti-oxidant effects. However, the neuroprotective effect of baicalein is still unclear. The current study scrutinizes the neuroprotective effect of baicalein against the ischaemic/reperfusion (I/R) injury via alteration of the nuclear factor kappa B (NF-kB) and AMP-activated protein kinase/nuclear factor erythroid 2-related factor 2 AMPK/Nrf2 signaling pathway. Wistar rats were used for the current study. In rats, I/R injury was caused by transient occlusion of the middle cerebral artery for 1h accompanied by reperfusion for 24h. The rats were divided into different groups and treated with the different doses of baicalein (2.5, 5 and 10mg/kg). The effects of baicalein on the murine neurological function were determined via infarct volume, neurological defect scores, and brain water content. The -inflammatory cytokines and oxidative stress were estimated in the region of the cortical along with the expression of apoptosis markers, such as B-cell lymphoma 2, Bax, and caspase-3. Quantitative reverse transcription polymerase chain reaction was used for the estimation of the NF-kB, cyclooxygenase-2 (COX-2), prostaglandin E2 (PGE2) and lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) expression. Baicalein significantly (p < 0.001) ameliorated the infarction volume, brain water content, and neurological outcome, and the malondialdehyde level, and reduced the level of interleukin-1β, interleukin-6, tumor necrosis factor-α, superoxide dismutase, glutathione, and catalase in a dose-dependent manner. Baicalein significantly (p < 0.001) altered the expression of COX-2, PGE2, LOX-1 and NF-kB as compared to I/R control group rats. Baicalein significantly reduced the Nrf2 and AMPK levels, and protected the rat brain against the I/R injury, suggesting a neuroprotective effect via down-regulation of NF-kB and LOX-1 expression and the AMPK/Nrf2 pathway.

Serum LOX-1 is a novel prognostic biomarker of colorectal cancer.

Colorectal cancer is the third most common cancer worldwide. If biomarkers can be identified in liquid biopsy, diagnosis and treatment can be optimized even when cancerous tissues are not available. The purpose of this study was to identify proteins from liquid biopsy that would be useful as markers of poor prognosis. First, we comprehensively analyzed serum proteins to identify potential biomarkers and focused on serum lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1). The relationship between LOX-1 and the prognosis of patients with colorectal cancer has not been reported. Next, we validated this marker using serum samples from 238 patients with colorectal cancer by ELISA and 100 tissue samples by immunohistochemical staining. The optimal cut-off value of serum LOX-1 was 538.7pg/mL according to time-dependent receiver operating characteristics curve analysis. The overall survival of patients with high levels of serum LOX-1 was significantly poorer than that of individuals with low levels of LOX-1 in the training and test datasets. In multivariate analysis for overall survival, serum LOX-1 was an independent prognostic factor identified in liquid biopsy (hazard ratio = 1.729, p = 0.027). The prognosis of patients with high LOX-1 expression in tumor tissues was significantly poorer than that of individuals with low expression (p =0.047 ). Additionally, inflammatory factors such as white blood cell count, C-reactive protein level, neutrophil/lymphocyte ratio, and monocyte/lymphocyte ratio were significantly higher in the group with high serum LOX-1 levels. Serum LOX-1 might be a useful biomarker of poor prognosis in colorectal cancer.

Role of Lectin-like Oxidized LDL Receptor-1 and Syncytiotrophoblast Extracellular Vesicles in the Vascular Reactivity of Mouse Uterine Arteries During Pregnancy

Vascular complications in pregnancy (e.g. preeclampsia) are a major source of maternal and foetal morbidity and mortality, and may be due to excessive release of placental syncytiotrophoblast-derived extracellular vesicles (STBEVs) into the maternal circulation. Increased activity of the multi-ligand scavenger receptor Lectin-like Oxidized LDL Receptor-1 (LOX-1) is associated with vascular dysfunction, and LOX-1 has been shown to interact with angiotensin II receptor type 1 (AT1). We hypothesized that STBEVs contribute to vascular dysfunction via LOX-1 and AT1 receptors during pregnancy. Uterine arteries from late pregnant wildtype and LOX-1 overexpressing mice were incubated overnight with or without STBEVs and vascular function was assessed using wire myography. STBEV-incubation decreased angiotensin II responsiveness only in wildtype mice, which coincided with decreased AT1 contribution and expression. Thus, STBEVs reduced angiotensin II responsiveness in normal pregnancy, but not in conditions of increased LOX-1 expression, suggesting that STBEVs (via LOX-1) play a role in normal adaptations to pregnancy. Oxidized LDL (a LOX-1 ligand) increased angiotensin II-induced vasoconstriction in STBEV-incubated arteries from both mouse strains, suggesting that the LOX-1 pathway may be involved in complicated pregnancies with elevated STBEVs and oxidized LDL levels (such as preeclampsia). These data increase our understanding of vascular complications during pregnancy.

ERK1/2-PPARγ pathway is involved in Chlamydia pneumonia-induced human umbilical vein endothelial cell apoptosis through increased LOX-1 expression

Chlamydia pneumonia (C.pn) is a common respiratory pathogen that is involved in human cardiovascular diseases and promotes the development of atherosclerosis in hyperlipidemic animal models. C.pn reportedly up-regulated lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) in endothelial cells. Recently, the anti-atherosclerotic activity of peroxisome proliferator-activated receptor γ (PPARγ) has been documented. In the present study, we investigated the effect of C.pn on LOX-1 expression in human umbilical vein endothelial cells (HUVECs) and identified the involvement of the PPARγ signaling pathway therein. The results showed that C.pn increased the expression of LOX-1 in HUVECs in a dose- and time-dependent manner. C.pn-induced up-regulation of LOX-1 was mediated by ERK1/2, whereas p38 MAPK and JNK had no effect on this process. C.pn induced apoptosis, inhibited cell proliferation, and decreased the expression PPARγ in HUVECs. Additionally, LOX-1 activity and cell injury caused by C.pn through activation of ERK1/2 was completely inhibited by rosiglitazone, a PPARγ agonist. In conclusion, we inferred that activation of PPARγ in HUVECs suppressed C.pn-induced LOX-1 expression and cell damage by inhibiting ERK1/2 signaling.

Association between impaired cutaneous microvascular endothelial function and lectin-like oxidized low-density lipoprotein receptor-1 in patients with coronary slow flow

ObjectiveAlthough increasing studies indicate coronary slow flow (CSF) is a systemic microvascular disorder, whether there is impaired cutaneous microvascular endothelial function in CSF patients remains unclear. This study was designed to test the hypothesis that the cutaneous microvascular endothelial function of CSF patients is impaired and correlates with lectin-like oxidized low-density lipoprotein receptor-1(LOX-1). Methods39 patients with CSF and 45 controls with normal coronary flow were enrolled. Velocity of coronary flow was quantitatively identified by thrombolysis in myocardial infarction frame count (TFC) method. LSCI system was used to assess subjects' cutaneous blood flow at rest and during PORH. Serum soluble LOX-1(sLOX-1) level was measured in all study subjects. ResultsPORH-induced vasodilation was significantly reduced in CSF group in comparison with control group (0.26 ± 0.10 vs 0.35 ± 0.07 APU/mmHg, P < 0.001) and negatively correlated with the mean TFC for three coronary arteries (r = −0.385, P = 0.016). Serum sLOX-1 level in CSF group was significantly increased (582.93 ± 74.89 vs 483.64 ± 51.38 pg/ml, P < 0.001) and positively correlated with mean TFC(r = 0.467, P = 0.003).PORH response amplitudes had a significantly negative relationship with serum sLOX-1 level in CSF patients (r = −0.588, P < 0.001). ConclusionThese data suggest that cutaneous microvascular endothelial function is impaired in patients with CSF, which is closely associated with increased LOX-1 expression.

Exosomal miRNA Let-7 from Menstrual Blood-Derived Endometrial Stem Cells Alleviates Pulmonary Fibrosis through Regulating Mitochondrial DNA Damage.

Idiopathic pulmonary fibrosis (IPF) is a prototype of chronic, progressive, and fibrotic lung disease with high morbidity and high mortality. Menstrual blood-derived stem cells (MenSCs) have proven to be an attractive tool for the treatment of acute lung injury and fibrosis-related diseases through immunosuppression and antifibrosis. However, whether MenSC-derived exosomes have the similar function on pulmonary fibrosis remains unclear. In the present study, exosomes secreted from MenSCs (MenSCs-Exo) were verified by transmission electron microscope (TEM), nanoparticle tracking analyzer (NTA), and western blotting. And MenSC-Exo addition significantly improved BLM-induced lung fibrosis and alveolar epithelial cell damage in mice, mainly reflected in BLM-mediated enhancement of the fibrosis score, blue collagen deposition, dry/wet gravity ratio, hydroxyproline and malondialdehyde levels, and downregulation of glutathione peroxidase, which were all robustly reversed by MenSC-Exo management. Additionally, BLM- and TGF-β1-evoked cellular reactive oxygen species (ROS), mitochondrial DNA (mtDNA) damage, and cell apoptosis were rescued by MenSCs-Exo in vivo and in vitro. Further study indicated that the MenSCs-Exo could transport miRNA Let-7 into recipient alveolar epithelial cells. Let-7 inhibitor administration significantly blocked the exosome-mediated improvement role on lung fibrosis in mice. Mechanistically, Let-7 was able to regulate the expression of lectin-like oxidized low-density lipoprotein receptor-1 (LOX1) through binding to its 3′-UTR region. Forced expression of LOX1 promoted the expression of apoptosis-related protein and mtDNA damage markers via regulating NLRP3 which was also confirmed in BLM model mice under the combination therapy of the exosome and Let-7 inhibitor. Collectively, this study demonstrates that exosomal Let-7 from MenSCs remits pulmonary fibrosis through regulating ROS, mtDNA damage, and NLRP3 inflammasome activation. This provides a new approach of exocytosis on the treatment of fibrotic lung disease.

Interleukin-1β Regulates Lipid Homeostasis in Human Glomerular Mesangial Cells.

Recent studies have shown that hyperlipidemia is closely related to the progression of kidney disease and glomerulosclerosis has similar pathophysiological mechanisms with atherosclerosis. Atherosclerosis is essentially a chronic inflammatory process and various kidney diseases are characterized by a micro-inflammatory state. Hyperlipidemia levels are not parallel to the degree of glomerulosclerosis, inflammatory factors together with lipids may contribute to the pathogenesis of glomerulosclerosis. Therefore, it is key to clarify lipid-mediated renal injury through studying the mechanism by which inflammation affects cholesterol homeostasis at the cellular level. Intracellular lipid homeostasis involves both lipid uptake and excretion, therefore in this study, we aimed to explore whether interleukin-1β (IL-1β) promotes the uptake of oxidized low-density lipoprotein (Ox-LDL) to increase in intracellular lipid levels, and to clarify the effect of IL-1β on the expression of lectin-like oxidized LDL receptor 1 (LOX-1) and ATP-binding cassette transporter A1 (ABCA1), which may regulate cholesterol homeostasis in human mesangial cells (HMCs). The effect of IL-1β on uptake of Ox-LDL labeled with fluorescent Dil (Dil-Ox-LDL) by HMCs was observed using laser confocal microscopy. The effect of IL-1β on LOX-1 and ABCA1 expression in HMCs was detected by polymerase chain reaction and western blotting. Laser confocal microscopy revealed that HMCs took up Dil-Ox-LDL. Treatment of HMCs with 5 ng/ml IL-1β for 24 h significantly increased uptake of Dil-Ox-LDL. IL-1β also promoted LOX-1 mRNA and protein expression in a dose-dependent manner. Moreover, ABCA1 mRNA and protein expression were reduced by IL-1β in lipid-loaded HMCs in a dose-dependent manner. IL-1β promotes the uptake of Ox-LDL and expression of LOX-1 in HMCs, whereas it inhibits expression of ABCA1 under lipid load. The imbalance in intracellular cholesterol resulted by IL-1β can in turn transform HMCs into foam cells and aggravate glomerulosclerosis.

Effects of crocin and saffron aqueous extract on gene expression of SIRT1, AMPK, LOX1, NF-κB, and MCP-1 in patients with coronary artery disease: A randomized placebo-controlled clinical trial.

This trial evaluated the potential impacts of saffron aqueous extract (SAE) and its main carotenoid on some of the atherosclerosis-related gene expression and serum levels of oxidized low-density cholesterol (ox-LDL) and Monocyte chemoattractant protein 1 (MCP-1) in patients with coronary artery disease (CAD). Participants of this randomized controlled trial included 84 CAD patients who categorized into three groups: Group 1 received crocin (30 mg/day), Group 2 SAE (30 mg/day), and Group 3 placebo for 8 weeks. Gene expression of Sirtuin 1 (SIRT1), 5'-adenosine monophosphate-activated protein kinase (AMPK), Lectin-like oxidized LDL receptor 1 (LOX1), nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), and MCP-1 in peripheral blood mononuclear cells assessed by real-time PCR. Furthermore, serum ox-LDL and MCP-1 levels measured at the beginning and end of the intervention. Compared with the placebo group, gene expression of SIRT1 and AMPK increased significantly in the crocin group (p = .001), and the expression of LOX1 and NF-κB decreased significantly (p = .016 and .004, respectively). Serum ox-LDL levels decreased significantly in the crocin group after the intervention (p = .002) while MCP-1 levels decreased both in crocin and SAE groups (p = .001). Crocin may have beneficial effects on CAD patients by increasing the gene expression of SIRT1 and AMPK and decreasing the expression of LOX1 and NF-κB.

ER stress of cancer cell SCC25 induces LOX-1-expressed immunosuppressive neutrophils

Abstract Background Immunosuppressive neutrophils with surface expression of lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) existed at both tumor sites and blood in patients with head and neck squamous cell carcinoma (HNSCC). Their immunosuppressive activities were proved to be induced by endoplasmic reticulum (ER) stress. In addition, ER stress of cancer cells could be “transmissed” to nearby myeloid cells such as dendritic cells and macrophages. Based on these findings, we hypothesized that ER stress of HNSCC could induce LOX-1 expression and immunosuppression of nearby neutrophils. Methods Conditioned medium (CM) from SCC25 cancer cells with or without treatment of thapsigargin (THG), a common ER stress inducer, was collected. Human neutrophils, isolated from peripheral blood of healthy donors, were then cultured in differently prepared conditioned medium. After 4 hours of culture, LOX-1 expression of neutrophils was evaluated by flow cytometry. In addition, the immunosuppressive effects of these conditioned neutrophils were evaluated by their abilities to inhibit nonspecific T cell proliferation using interleukin-2 (IL-2)/anti-CD3/anti-CD28 system. Results Higher percentages of neutrophils expressed LOX-1 after they were cultured in CM from THG-treated SCC 25 cells than in CM from naive SCC 25 cells. Moreover, conditioned neutrophils by THG-treated SCC 25 cells had more inhibitory effects in T cell proliferation than conditioned neutrophils by naive SCC25 cells. Conclusion ER stress induction of SCC25 could enhance both LOX-1 expression and immunosuppressive activities of neutrophils. Legal entity responsible for the study The authors. Funding Ministry of Science and Technology, Taiwan. Disclosure All authors have declared no conflicts of interest.

Naringin Reverses High-Cholesterol Diet-Induced Vascular Dysfunction and Oxidative Stress in Rats via Regulating LOX-1 and NADPH Oxidase Subunit Expression.

Hypercholesterolaemia is associated with oxidative stress and endothelial dysfunction and leads to the development of atherosclerosis. Naringin exhibits cardiovascular protective and antioxidant properties. Therefore, the aim of this study was to assess the effect of naringin administration on vascular oxidative stress and endothelial dysfunction in hypercholesterolaemic rats and to elucidate its underlying mechanism. Sprague Dawley rats were fed a diet with 1.5% cholesterol (HCD) for 8 weeks to induce hypercholesterolaemia. Naringin (100 mg/kg body weight) was orally administrated to rats during the last 4 weeks of the diet treatment. After 8 weeks, the thoracic aorta was isolated to determine vascular function and nitric oxide (NO) levels. The aortic superoxide anion (O2−) level was detected using dihydroethidium (DHE) fluorescence staining. Protein expression of lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1), nicotinamide adenine dinucleotide phosphate (NADPH) oxidase subunits, and inducible nitric oxide synthase (iNOS), as well as oxidative damage markers, was also evaluated in aortae. Naringin treatment of hypercholesterolaemic rats enhanced aortic NO levels, restored endothelium-dependent responses to acetylcholine (ACh), and reduced aortic O2− levels. Furthermore, naringin treatment decreased LOX-1, NADPH oxidase subunits (p47phox, Nox2, and Nox4), and iNOS as well as oxidative damage markers (3-nitrotyrosine (3-NT) and 4-hydroxynonenal (4-HNE)) expression in aortic tissues from hypercholesterolaemic rats. These results demonstrate that naringin treatment improves endothelium dysfunction in hypercholesterolaemic rats, at least partially by decreasing oxidative stress via downregulation of LOX-1 and NADPH oxidase.

Fisetin, via CKIP-1/REGγ, limits oxidized LDL-induced lipid accumulation and senescence in RAW264.7 macrophage-derived foam cells

To test the hypothesis that the flavonoid compound, fisetin, protects macrophages from lipid accumulation and senescence through regulation of casein kinase 2-interacting protein-1 (CKIP-1)/REGγ (11S regulatory particles, 28 kDa proteasome activator, proteasome activator subunit 3) signaling. RAW264.7 macrophage cells were exposed to 100 μg/ml oxidized low-density lipoprotein (ox-LDL) with or without 20 μg/ml fisetin for 24 h. Cell viability was detected by CCK-8 after 1 h. Intracellular lipid accumulation was measured using Oil Red O staining. Total cholesterol (TC) and free cholesterol (FC) contents were measured using assay kits, and cell senescence was inferred by β-gal staining. Protein expression levels of CKIP-1, REGγ, organic cation transporter 1 (Oct-1), lectin-like oxidized LDL receptor-1 (LOX-1), tumor suppressor protein p53 (p53), cell cycle regulatory protein p21 (p21), and multiple tumor suppressor-1 (p16) were detected by immunofluorescence and confirmed by Western blot. Stimulating RAW264.7 macrophage cells with 100 μg/ml ox-LDL for 24 h induced the formation of foam cells, increased intracellular lipid accumulation, increased TC and FC content, and promoted cell senescence. Furthermore, cells induced with 100 μg/ml ox-LDL for 24 h showed decreased CKIP-1 and REGγ protein, while the expressions of Oct-1, LOX-1, p53, p21 and p16 were increased. In contrast, treatment with 20 μg/ml fisetin reversed 100 μg/ml ox-LDL effects to increase cell viability, and decrease β-gal staining, intracellular lipid levels and TC and FC levels. These beneficial effects were associated with increased CKIP-1 and REGγ and decreased Oct-1, LOX-1, p53, p21, and p16 protein expression. Results indicated that fisetin limited ox-LDL-mediated lipid accumulation and senescence in RAW264.7 macrophage-derived foam cells. The mechanism underlying these effects may involve regulation of CKIP-1/REGγ signaling.

Serum soluble lectin-like oxidized low-density lipoprotein receptor-1 concentrations and prognosis of aneurysmal subarachnoid hemorrhage

BackgroundOxidized low-density lipoprotein (ox-LDL) and its receptor, lectin-like ox-LDL receptor-1 (LOX-1) are involved in the pathogenesis of atherosclerosis. Expression of LOX-1 was substantially raised in the basilar arterial wall of subarachnoid hemorrhage (SAH) rabbits. We ascertained the relationship between serum soluble LOX-1 concentrations and functional outcome after human aneurysmal SAH. MethodsWe enrolled 94 aneurysmal SAH patients and 94 healthy controls. Serum soluble TOX-1 concentrations were quantified using commercial enzyme-linked immunosorbent assay kit. A poor outcome was defined as Glasgow outcome scale score of 1–3. ResultsMedian values of serum soluble LOX-1 in stroke patients were significantly higher than those in controls (1.5 vs. 0.4 ng/ml, P < 0.001). Thirty patients (31.9%) had a poor outcome at 6 months after stroke. Serum soluble LOX-1 was a strong predictor of poor outcome (OR 5.20, 95% CI 1.25–22.04). Serum soluble LOX-1 concentrations exhibited a significant discriminatory capability (area under curve 0.811, 95% confidence interval 0.717–0.884). The predictive powers of World Federation of Neurological Surgeons grade, Hunt-Hess grade, modified Fisher grade, and serum soluble LOX-1 concentrations were comparable (all P > 0.05). ConclusionsSerum soluble LOX-1 appears to have the potential to become a promising prognostic predictor after human aneurysmal SAH.

Oxidized low-density lipoproteins induce tissue factor expression in T-lymphocytes via activation of lectin-like oxidized low-density lipoprotein receptor-1.

T-lymphocytes plays an important role in the pathophysiology of acute coronary syndromes. T-cell activation in vitro by pro-inflammatory cytokines may lead to functional tissue factor (TF) expression, indicating a possible contribution of immunity to thrombosis. Oxidized low-density lipoproteins (oxLDLs) are found abundantly in atherosclerotic plaques. We aimed at evaluating the effects of oxLDLs on TF expression in T cells and the role of the lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1). CD3+ cells were isolated from healthy volunteers. Gene, protein, and surface expression of TF, as well as of LOX-1, were assessed at different time-points after oxLDL stimulation. To determine whether oxLDL-induced TF was LOX-1 dependent, T cells were pre-incubated with an LOX-1 inhibiting peptide (L-RBP) or with an anti-LOX-1 blocking antibody. To exclude that TF expression was mediated by reactive oxygen species (ROS) generation, oxLDL-stimulated T cells were pre-incubated with superoxide dismutase + catalase or with 4-Hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl (Tempol), an intracellular free radical scavenger. Finally, to determine if the observed findings in vitro may have a biological relevance, the presence of CD3+/TF+/LOX-1+ cells was evaluated by immunofluorescence in human carotid atherosclerotic lesions. oxLDLs induced functionally active TF expression in T cells in a dose- and time-dependent manner, independently on ROS generation. No effect was observed in native LDL-treated T cells. LOX-1 expression was also induced by oxLDLs in a time- and dose-dependent manner. Pre-incubation with L-RBP or anti-LOX-1 antibody almost completely inhibited oxLDL-mediated TF expression. Interestingly, human carotid plaques showed significant infiltration of CD3+ cells (mainly CD8+ cells), some of which were positive for both TF and LOX-1. oxLDLs induce functional TF expression in T-lymphocytes in vitro via interaction of oxLDLs with LOX-1. Human carotid atherosclerotic plaques contain CD3+/CD8+cells that express both TF and LOX-1, indicating that also in patients these mechanisms may play an important role.