Lipopolysaccharide induced LOX-1 expression via TLR4/MyD88/ROS activated p38MAPK-NF-κB pathway

Excessive hypercholesterolemia in pregnancy impairs rat uterine artery function via activation of Toll-like receptor 4

Hypercholesterolemia in pregnancy is a physiological process required for normal fetal development. In contrast, excessive pregnancy-specific hypercholesterolemia increases the risk of complications, such as preeclampsia. However, the underlying mechanisms are unclear. Toll-like receptor 4 (TLR4) is a membrane receptor modulated by high cholesterol levels, leading to endothelial dysfunction; but whether excessive hypercholesterolemia in pregnancy activates TLR4 is not known. We hypothesized that a high cholesterol diet (HCD) during pregnancy increases TLR4 activity in uterine arteries, leading to uterine artery dysfunction. Sprague Dawley rats were fed a control diet (n=12) or HCD (n=12) during pregnancy (gestational day 6-20). Vascular function was assessed in main uterine arteries using wire myography (vasodilation to methacholine and vasoconstriction to phenylephrine; with and without inhibitors for mechanistic pathways) and pressure myography (biomechanical properties). Exposure to a HCD during pregnancy increased maternal blood pressure, induced proteinuria, and reduced the fetal-to-placental weight ratio for both sexes. Excessive hypercholesterolemia in pregnancy also impaired vasodilation to methacholine in uterine arteries, whereby at higher doses, methacholine caused vasoconstriction instead of vasodilation in only the HCD group, which was prevented by inhibition of TLR4 or prostaglandin H synthase 1. Endothelial nitric oxide synthase expression and nitric oxide levels were reduced in HCD compared with control dams. Vasoconstriction to phenylephrine and biomechanical properties were similar between groups. In summary, excessive hypercholesterolemia in pregnancy impairs uterine artery function, with TLR4 activation as a key mechanism. Thus, TLR4 may be a target for therapy development to prevent adverse perinatal outcomes in complicated pregnancies.

Effect of Copper and Zinc Ions on Biochemical and Molecular Characteristics of Calcium Oxalate Renal Stones: a Controlled Clinical Study

Contradictory results are existed in the literature regarding the impact of trace elements on the pathogenesis of calcium oxalate (CaOx) stone patients. Therefore, the aim of our study was to investigate the effect of Cu and Zn on biochemical and molecular characteristics of CaOx stones. Plasma and urine concentrations of Cu and Zn in 30 CaOx stones patients and 20 controls were determined by flame atomic absorption spectrometry (FAAS). Urinary levels of citric acid and oxalate were measured by commercial spectrophotometric kits. Blood levels of glutathione reduced (GSH) and catalase (CAT) were determined as markers of antioxidant activity, while blood malondialdehyde (MDA) and urine level of nitric oxide (NO) were used to assess oxidative stress. Gene expression of MAPk pathway (ERK, P38, and JNK) were estimated. The plasma and urine levels of Cu were significantly increased in the patient group compared to those of controls, while the levels of Zn were decreased. Excessive urinary excretion of citric acid and oxalate were found among CaOx stone patients. The GSH and CAT concentration were significantly reduced in CaOx stones patients compared to healthy group. The plasma MDA and urine NO concentration were significantly increased in CaOx stones patients compared to control group. The expressions of the studied genes were significantly increased in CaOx stones patients. These findings suggest that alteration in Cu and Zn might contribute to pathogenesis of CaOx patients through oxidative stress and MAPK pathway genes (ERK, P38 and JNK).

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

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

Pathogenic mechanisms and regulatory factors involved in alcoholic liver disease

Alcoholism is a widespread and damaging behaviour of people throughout the world. Long-term alcohol consumption has resulted in alcoholic liver disease (ALD) being the leading cause of chronic liver disease. Many metabolic enzymes, including alcohol dehydrogenases such as ADH, CYP2E1, and CATacetaldehyde dehydrogenases ALDHsand nonoxidative metabolizing enzymes such as SULT, UGT, and FAEES, are involved in the metabolism of ethanol, the main component in alcoholic beverages. Ethanol consumption changes the functional or expression profiles of various regulatory factors, such as kinases, transcription factors, and microRNAs. Therefore, the underlying mechanisms of ALD are complex, involving inflammation, mitochondrial damage, endoplasmic reticulum stress, nitrification, and oxidative stress. Moreover, recent evidence has demonstrated that the gut-liver axis plays a critical role in ALD pathogenesis. For example, ethanol damages the intestinal barrier, resulting in the release of endotoxins and alterations in intestinal flora content and bile acid metabolism. However, ALD therapies show low effectiveness. Therefore, this review summarizes ethanol metabolism pathways and highly influential pathogenic mechanisms and regulatory factors involved in ALD pathology with the aim of new therapeutic insights.

Phosphoenolpyruvate induces endothelial dysfunction and cell senescence through stimulation of metabolic reprogramming

Endothelial dysfunction is a key early link in the pathogenesis of atherosclerosis, and the accumulation of senescent vascular endothelial cells causes endothelial dysfunction. Phosphoenolpyruvate (PEP), which is a high-energy glycolytic intermediate, protects against ischemia-reperfusion injury in isolated rat lung, heart, and liver tissue by quickly providing ATP. However, it was reported that serum PEP concentrations are 13-fold higher in healthy elderly compare to the young. Unlike that of other cell types, the energy required for the physiological function of endothelial cells is mainly derived from glycolysis. Recently, it is unclear whether circulating accumulation of PEP affects endothelial cell function. In this study, we found for the first time that 50-250 μM of PEP significantly promoted THP-1 monocyte adhesion to human umbilical vein endothelial cells (HUVECs) through increased expression of vascular endothelial adhesion factor 1 (VCAM1) and intercellular adhesion factor 1 (ICAM1) in HUVECs. Meanwhile, 50-250 μM of PEP decreased the expression of endothelial nitric oxide synthase (eNOS) and cellular level of nitric oxide (NO) in HUVECs. Moreover, PEP increased levels of ROS, enhanced the numbers of SA-β-Gal-positive cells and upregulated the expression of cell cycle inhibitors such as p21, p16 and the phosphorylation level of p53 on Ser15, and the expression of proinflammatory factors including TNF-α, IL-1β, IL-6, IL-8, IL-18 and MCP-1 in HUVECs. Furthermore, PEP increased both oxygen consumption rate (OCR) and glycolysis rate, and was accompanied by reduced NAD⁺/NADH ratios and enhanced phosphorylation levels of AMPKα (Thr172), p38 MAPK (T180/Y182) and NF-κB p65 (Ser536) in HUVECs. Notably, PEP had no significant effect on hepG2 cells. In conclusion, these results demonstrated that PEP induced dysfunction and senescence in vascular endothelial cells through stimulation of metabolic reprogramming.

Effects of nicotine and lipopolysaccharide stimulation on adhesion molecules in human gingival endothelial cells

Smoking is a risk factor for periodontitis, and the immune response of periodontal tissues in patients with periodontitis may be strongly affected by smoking. The purpose of this study was to elucidate the bioactivity and signal transduction of human gingival endothelial cells (HGECs) due to nicotinic stimulation using a cultured medium supplemented with lipopolysaccharide (LPS) as a model of periodontitis. HGECs were cultured in medium supplemented with LPS, nicotine, nicotine + LPS, and medium supplemented without nicotine or LPS (control). Cell proliferation was assessed using Alamar blue. Cytotoxicity was assessed by lactate dehydrogenase leakage. The expression of adhesion molecule-1 (ICAM-1, VCAM-1) was assessed by reverse transcription quantitative polymerase chain reaction (RT-qPCR) and enzyme-linked immunosorbent assay. The expression of nicotinic acetylcholine receptor (nAChR) subunits (α3, α5, α7, β2 and β4) was evaluated by RT-PCR. The involvement of p38 mitogen-activated protein kinase (p38MAPK) and protein kinase C (PKC) cell signaling pathways in ICAM-1 and VCAM-1 expression was investigated by RT-qPCR with specific inhibitors. HGECs stimulated with LPS, nicotine and nicotine + LPS showed inhibition of cell proliferation, increase of cell death, and increase of gene and protein expression of ICAM-1. Moreover, HGECs showed the presence of α5 and α7 nAChR subunits. The expression of ICAM-1 in HGECs stimulated with LPS, nicotine, and nicotine + LPS was significantly suppressed by p38MAPK inhibitor, but not by a PKC inhibitor. The nAChR subunits of HGECs are α5 and α7, and that HGECs stimulated with nicotine and LPS express ICAM-1 via p38MAPK pathway.

Meloxicam inhibited oxidative stress and inflammatory response of LPS-stimulated bovine endometrial epithelial cells through Nrf2 and NF-κB pathways

Meloxicam is a selective cyclooxygenase-2 inhibitor and has been widely used in combination with antibiotics to alleviate uterine inflammation and provide analgesia in postpartum cows. Studies have shown that meloxicam has antioxidant and anti-inflammatory effects. However, the link between meloxicam and uterine inflammation and oxidative stress in dairy cows has not been studied. The purpose of this study was to research the effects of meloxicam (0.5 or 5 μM) on oxidative stress and inflammatory response of primary bovine endometrial epithelial cells (BEEC) stimulated by Escherichia coli lipopolysaccharide (1 μg/mL LPS). As a result, LPS stimulated the production of oxidative stress markers and the expression of inflammatory factors, accompanied by a decrease in the activity and the gene transcription of antioxidant enzymes. Co-treatment of meloxicam and LPS reduced the content of oxidative stress markers and the mRNA levels of the pro-inflammatory genes, and improved antioxidant enzyme activities and the corresponding gene expression as compared with the cells treated with LPS alone. Meloxicam attenuated the inhibitory effect of the Nrf2 pathway and the phosphorylation levels of p65 and IκBα caused by LPS. In conclusion, meloxicam alone had no effect on BEEC, but prevented oxidative stress and inflammatory response in LPS-stimulated BEEC.

Oridonin attenuates LPS-induced early pulmonary fibrosis by regulating impaired autophagy, oxidative stress, inflammation and EMT

CONTEXT

Oridonin (Ori) possesses anti-inflammatory, antioxidant and antitumor properties. However, the effects of Ori on Lipopolysaccharide (LPS)-induced early pulmonary fibrosis remain unclear.

OBJECTIVE

We evaluated the protective effects of Ori on the mice model of pulmonary fibrosis.

MATERIALS AND METHODS

The BALB/C mice were given LPS (1 mg/kg) or Ori (20 mg/kg) according to experimental grouping. Then the left lung tissues were used for HE, immunohistochemical and Masson staining, and the right lung tissues were used for hydroxyproline measurement and western blot experiments. Bronchoalveolar lavage fluid was collected for Giemsa staining.

RESULTS

The high levels of hydroxyproline induced by LPS were reduced by Ori treatment. Immunohistochemical staining and western blot analysis showed that Ori inhibited the increased levels of fibrosis-related proteins (α-smooth muscle actin, transforming growth factor-β, Collagen Ⅰ and phosphorylated-smad). Additionally, Ori treatment increased E-cadherin levels and decreased in Snail and Slug levels. Besides, Ori could suppress LPS-induced the infiltration of neutrophils and activation of the NLRP3 inflammasome. In addition, LPS caused the upregulation of NADPH oxidase 4 and exacerbated lung fibrosis. As the activator of NF-E2 related factor-2, Ori exerted protective effects in this animal model. Moreover, Ori reversed the LPS-triggered increases in Beclin-1, P62/sequestosome 1, autophagy related 3 and LC3.

CONCLUSIONS

These findings suggested that Ori protected against LPS-induced early pulmonary fibrosis by inhibiting NLRP3-dependent inflammation, NADPH oxidase 4-dependent oxidative stress, the impaired autophagy and epithelial mesenchymal transformation.

ApoA-I mimetics reduce systemic and gut inflammation in chronic treated HIV

Novel therapeutic strategies are needed to attenuate increased systemic and gut inflammation that contribute to morbidity and mortality in chronic HIV infection despite potent antiretroviral therapy (ART). The goal of this study is to use preclinical models of chronic treated HIV to determine whether the antioxidant and anti-inflammatory apoA-I mimetic peptides 6F and 4F attenuate systemic and gut inflammation in chronic HIV. We used two humanized murine models of HIV infection and gut explants from 10 uninfected and 10 HIV infected persons on potent ART, to determine the in vivo and ex vivo impact of apoA-I mimetics on systemic and intestinal inflammation in HIV. When compared to HIV infected humanized mice treated with ART alone, mice on oral apoA-I mimetic peptide 6F with ART had consistently reduced plasma and gut tissue cytokines (TNF-α, IL-6) and chemokines (CX3CL1) that are products of ADAM17 sheddase activity. Oral 6F attenuated gut protein levels of ADAM17 that were increased in HIV-1 infected mice on potent ART compared to uninfected mice. Adding oxidized lipoproteins and endotoxin (LPS) ex vivo to gut explants from HIV infected persons increased levels of ADAM17 in myeloid and intestinal cells, which increased TNF-α and CX3CL1. Both 4F and 6F attenuated these changes. Our preclinical data suggest that apoA-I mimetic peptides provide a novel therapeutic strategy that can target increased protein levels of ADAM17 and its sheddase activity that contribute to intestinal and systemic inflammation in treated HIV. The large repertoire of inflammatory mediators involved in ADAM17 sheddase activity places it as a pivotal orchestrator of several inflammatory pathways associated with morbidity in chronic treated HIV that make it an attractive therapeutic target.

Macrophage uptake of oxidized and acetylated low-density lipoproteins and generation of reactive oxygen species are regulated by linear stiffness of the growth surface

Macrophages are key players in the development of atherosclerosis: they scavenge lipid, transform into foam cells, and produce proinflammatory mediators. At the same time, the arterial wall undergoes profound changes in its mechanical properties. We recently showed that macrophage morphology and proinflammatory potential are regulated by the linear stiffness of the growth surface. Here we asked whether linear stiffness also regulates lipid uptake by macrophages. We cultured murine bone marrow-derived macrophages (BMMs) on polyacrylamide gels modeling stiffness of healthy (1kPa) and diseased (10-150kPa) blood vessels. In unprimed BMMs, increased linear stiffness increased uptake of oxidized (oxLDL) and acetylated (acLDL) low density lipoproteins and generation of reactive oxygen species, but did not alter phagocytosis of bacteria or silica particles. Macrophages adapted to stiff growth surfaces had increased mRNA and protein expression of two key lipoprotein receptors: CD36 and scavenger receptor b1. Regulation of the lipoprotein receptor, lectin-like receptor for ox-LDL, was more complex: mRNA expression decreased but surface protein expression increased with increased stiffness. Focal adhesion kinase was required for maximal uptake of oxLDL, but not of acLDL. Uptake of oxLDL and acLDL was independent of rho-associated coiled coil kinase. Through pharmacologic inhibition and genetic deletion, we found that transient receptor potential vanilloid 4 (TRPV4), a mechanosensitive ion channel, plays an inhibitory role in the uptake of acLDL, but not oxLDL. Together, these results implicate mechanical signaling in the uptake of acLDL and oxLDL, opening up the possibility of new pharmacologic targets to modulate lipid uptake by macrophages in vivo.

Immunoregulatory mechanism studies of ginseng leaves on lung cancer based on network pharmacology and molecular docking

Panax ginseng is one of the oldest and most generally prescribed herbs in Eastern traditional medicine to treat diseases. Several studies had documented that ginseng leaves have anti-oxidative, anti-inflammatory, and anticancer properties similar to those of ginseng root. The aim of this research was to forecast of the molecular mechanism of ginseng leaves on lung cancer by molecular docking and network pharmacology so as to decipher ginseng leaves' entire mechanism. The compounds associated with ginseng leaves were searched by TCMSP. TCMSP and Swiss Target Prediction databases were used to sort out the potential targets of the main chemical components. Targets were collected from OMIM, PharmGKB, TTD, DrugBank and GeneCards which related to immunity and lung cancer. Ginseng leaves exert its lung cancer suppressive function by regulating the several signaling proteins, such as JUN, STAT3, AKT1, TNF, MAPK1, TP53. GO and KEGG analyses indicated that the immunoreaction against lung cancer by ginseng leaves might be related to response to lipopolysaccharide, response to oxidative stress, PI3K-Akt, MAPK and TNF pathway. Molecular docking analysis demonstrated that hydrogen bonding was interaction's core forms. The results of CCK8 test and qRT-PCR showed that ginseng leaves inhibit cell proliferation and regulates AKT1 and P53 expression in A549. The present study clarifies the mechanism of Ginseng leaves against lung cancer and provides evidence to support its clinical use.

Critical role of oxidized LDL receptor-1 in intravascular thrombosis in a severe influenza mouse model

Although coagulation abnormalities, including microvascular thrombosis, are thought to contribute to tissue injury and single- or multiple-organ dysfunction in severe influenza, the detailed mechanisms have yet been clarified. This study evaluated influenza-associated abnormal blood coagulation utilizing a severe influenza mouse model. After infecting C57BL/6 male mice with intranasal applications of 500 plaque-forming units of influenza virus A/Puerto Rico/8/34 (H1N1; PR8), an elevated serum level of prothrombin fragment 1 + 2, an indicator for activated thrombin generation, was observed. Also, an increased gene expression of oxidized low-density lipoprotein (LDL) receptor-1 (Olr1), a key molecule in endothelial dysfunction in the progression of atherosclerosis, was detected in the aorta of infected mice. Body weight decrease, serum levels of cytokines and chemokines, viral load, and inflammation in the lungs of infected animals were similar between wild-type and Olr1 knockout (KO) mice. In contrast, the elevation of prothrombin fragment 1 + 2 levels in the sera and intravascular thrombosis in the lungs by PR8 virus infection were not induced in KO mice. Collectively, the results indicated that OLR1 is a critical host factor in intravascular thrombosis as a pathogeny of severe influenza. Thus, OLR1 is a promising novel therapeutic target for thrombosis during severe influenza.

Lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1): a crucial driver of atherosclerotic cardiovascular disease

Cardiovascular diseases (CVDs), specifically lipid-driven atherosclerotic CVDs, remain the number one cause of death worldwide. The lectin-like oxidized low-density lipoprotein (LDL) receptor-1 (LOX-1), a scavenger receptor that promotes endothelial dysfunction by inducing pro-atherogenic signalling and plaque formation via the endothelial uptake of oxidized LDL (oxLDL) and electronegative LDL, contributes to the initiation, progression, and destabilization of atheromatous plaques, eventually leading to the development of myocardial infarction and certain forms of stroke. In addition to its expression in endothelial cells, LOX-1 is expressed in macrophages, cardiomyocytes, fibroblasts, dendritic cells, lymphocytes, and neutrophils, further implicating this receptor in multiple aspects of atherosclerotic plaque formation. LOX-1 holds promise as a novel diagnostic and therapeutic target for certain CVDs; therefore, understanding the molecular structure and function of LOX-1 is of critical importance. In this review, we highlight the latest scientific findings related to LOX-1, its ligands, and their roles in the broad spectrum of CVDs. We describe recent findings from basic research, delineate their translational value, and discuss the potential of LOX-1 as a novel target for the prevention, diagnosis, and treatment of related CVDs.

Dihydrotanshinone I Attenuates Plaque Vulnerability in Apolipoprotein E-Deficient Mice: Role of Receptor-Interacting Protein 3

Aims: Vulnerable plaque disruption in advanced atherosclerosis leads to acute thrombus and subsequent myocardial infarction and severely threatens human health. Necroptosis of macrophage involved in the necrotic core is one key factor for plaque vulnerability. Dihydrotanshinone I (DHT) is a natural diterpenoid isolated from Danshen demonstrating effective anti-inflammatory property. It is accepted that inflammation plays a crucial role in the process of atherogenesis. However, whether DHT prevents atherosclerosis is poorly understood. Here, we investigated the effect of DHT on vulnerable plaque in an apolipoprotein E-deficient (ApoE^-/-) mice model of atherosclerosis and the underlying protective mechanisms. Results: In the in vitro experiment, first LPS/ZVAD (LPS, lipopolysaccharide; ZVAD, ZVAD-FMK, a cell-permeable pan-caspase inhibitor) stimulated necroptosis of macrophage in a receptor-interacting protein 3 (RIP3)-dependent pathway, which was regulated by Toll-like receptor 4 (TLR4) dimerization. Further study illustrated that activated RIP3 evoked endoplasmic reticulum stress as well as reactive oxygen species generation. Both DHT and RIP3 silence reversed the above phenomena. In the in vivo experiment, aorta and serum samples were collected to determine features of plaque stability, including plaque size, necrotic core area, as well as collagen content in fibrous cap and the expression of related protein molecules. Both DHT and RIP3 inhibitor GSK872 significantly enhanced plaque stability in ApoE^-/- mice by reducing oxidative stress, shrinking necrotic core area, increasing collagen content, and decreasing RIP3 expression. Innovation and Conclusion: Our study showed that DHT may stabilize vulnerable plaque by suppressing RIP3-mediated necroptosis of macrophage, which indicates its potential application as a lead compound for cardiovascular treatments, especially for advanced atherosclerosis. Antioxid. Redox Signal. 34, 351-363.

Link between microbiota and hypertension: Focus on LPS/TLR4 pathway in endothelial dysfunction and vascular inflammation, and therapeutic implication of probiotics

High blood pressure (BP) presents a significant public health challenge. Recent findings suggest that altered microbiota can exert a hypertensive effect on the host. One of the possible mechanisms involved is the chronic translocation of its components, mainly lipopolysaccharides (LPS) into systemic circulation leading to metabolic endotoxemia. In animal models, LPS has been commonly used to induce endothelial dysfunction and vascular inflammation. In human studies, plasma LPS concentration has been positively correlated with hypertension, however, the mechanistic link has not been fully elucidated. It is hypothesised here that the LPS-induced direct alterations to the vascular endothelium and resulting hypertension are possible targets for probiotic intervention. The methodology of this review involved a systematic search of the literature with critical appraisal of papers. Three tranches of search were performed: 1) existing review papers; 2) primary mechanistic animal, in vitro and human studies; and 3) primary intervention studies. A total of 70 peer-reviewed papers were included across the three tranches and critically appraised using SIGN50 for human studies and the ARRIVE guidelines for animal studies. The extracted information was coded into key themes and summarized in a narrative analysis. Results highlight the role of LPS in the activation of endothelial toll-like receptor 4 (TLR4) initiating a cascade of interrelated signalling pathways including: 1) Nicotinamide adenine dinucleotide phosphate (NADPH) oxidase/ Reactive oxygen species (ROS)/ Endothelial nitric oxide synthase (eNOS) pathway leading to endothelial dysfunction; and 2) Mitogen-Activated Protein Kinase (MAPK) and Nuclear factor kappa B (NF-κB) pathways leading to vascular inflammation. Findings from animal intervention studies suggest an improvement in vasorelaxation, vascular inflammation and hypertension following probiotic supplementation, which was mediated by downregulation of LPS-induced pathways. Randomised controlled trials (RCTs) and systematic reviews provided some evidence for the anti-inflammatory effect of probiotics with statistically significant antihypertensive effect in clinical samples and may offer a viable intervention for the management of hypertension.

Gliclazide alters macrophages polarization state in diabetic atherosclerosis in vitro via blocking AGE-RAGE/TLR4-reactive oxygen species-activated NF-kβ nexus

Hyperglycemic milieu in diabetes mellitus stimulates macrophages for exaggerated pro-inflammatory cytokine response, particularly IL-1β, IL-6, and TNF-α. Although hyperglycemia causes macrophages to produce pro-inflammatory cytokines, AGEs (advanced glycation end products) active inflammation, produced as a result of chronic hyperglycemia, inducers cause polarization of macrophages into pro-inflammatory M1 phenotype. AGEs in diabetes accelerate atherosclerotic plaque initiation and progression via promoting macrophages polarization towards pro-inflammatory state. Gliclazide (Glz) is a well known antidiabetic drug with excellent safety profile. Its repurposing in the management of diabetes-associated late complications has tremendous merit. The present study demonstrated that Glz retards diabetic atherosclerotic progression, and cytokines storm in a concentration dependent manner over a concentration range of 1-100 μM than those of AGEs (200 μg/ml)-treated cells through a mechanism that alters macrophage M1 polarization state. Glz exerted these beneficial effects, independent of its antidiabetic effect. Glz pretreatment significantly (P < 0.05) inhibited the AGEs-induced pro-inflammatory mediators (NO^•, reactive oxygen species, i-NOS), and production of pro-inflammatory cytokines, including IL-1β, IL-6, and TNF-α. It also significantly (P < 0.05) promoted the production of anti-inflammatory cytokines (IL-10 and TGF-β) in RAW 264.7 mouse macrophages. Glz pretreatment also effectively abated the AGEs-induced RAGE (~2-fold decrease), and CD86 surface marker expressions (P < 0.001 at 100 μM) on macrophages by inhibiting the NF-kβ activation in a concentration dependent manner (1-100 μM) (P < 0.001). In conclusion, our data demonstrates that Glz alleviates the diabetic atherosclerosis progression by ameliorating the AGEs-mediated M1 pro-inflammatory phenotype via blocking AGE-RAGE/TLR4-reactive oxygen species -activated NF-kβ nexus in macrophages.

The Role of Toll-like Receptors in Atherothrombotic Cardiovascular Disease

Toll-like receptors (TLRs) are dominant components of the innate immune system. Activated by both pathogen-associated molecular patterns and damage-associated molecular patterns, TLRs underpin the pathology of numerous inflammation related diseases that include not only immune diseases, but also cardiovascular disease (CVD), diabetes, obesity, and cancers. Growing evidence has demonstrated that TLRs are involved in multiple cardiovascular pathophysiologies, such as atherosclerosis and hypertension. Specifically, a trial called the Canakinumab Anti-inflammatory Thrombosis Outcomes Study showed the use of an antibody that neutralizes interleukin-1β, reduces the recurrence of cardiovascular events, demonstrating inflammation as a therapeutic target and also the research value of targeting the TLR system in CVD. In this review, we provide an update of the interplay between TLR signaling, inflammatory mediators, and atherothrombosis, with an aim to identify new therapeutic targets for atherothrombotic CVD.

Notoginsenoside R1 protects human keratinocytes HaCaT from LPS-induced inflammatory injury by downregulation of Myd88

Burn injury is a gigantic challenge in public health which brings multiple negative effects to patients both in physical and spiritual aspects. Inflammation plays vital roles in the progression of burn injury, and our study investigated whether notoginsenoside R1 (NGR1) alleviated lipopolysaccharide (LPS)-induced human keratinocyte HaCaT cell inflammatory injury. Inflammatory injury was induced by LPS in HaCaT cells. Stimulated cells were then treated by NGR1 in different concentrations. Cell viability and cell apoptosis were detected by Cell Counting Kit-8 and flow cytometry, respectively. The concentration of tumor necrosis factor α (TNF-α) and interleukin-6 (IL-6) was measured by enzyme-linked immunosorbent assay (ELISA). The accumulated levels of apoptosis-related proteins (caspase-3 and caspase-9), nuclear factor κB (NF-κB), p38 mitogen-activated protein kinase (p38MAPK) signal pathways–related proteins (p65, IκBα, and p38MAPK), and myeloid differentiation primary response 88 (MyD88) were examined by western blot. Transfection was used to alter the expression of MyD88. We found that LPS stimulated HaCaT cells and induced cell inflammation, evidenced by decreasing cell viability, increasing cell apoptosis, and elevating TNF-α and IL-6 expressions. Then, we found that NGR1 reversed the results by enhancing cell viability, inhibiting cell apoptosis, and reducing TNF-α and IL-6 expressions. In addition, NGR1 decreased the phosphorylation of p65, IκBα, and p38MAPK, which increased by LPS. Moreover, NGR1 negatively regulated the expression of MyD88, and transfection with pMyD88 led to the opposite results with what showed by NGR1 in LPS-stimulated HaCaT cells. To sum up, NGR1 alleviates LPS-induced HaCaT cell inflammatory injury by downregulation of MyD88, as well as inactivation of NF-κB and p38MAPK signal pathways.

Targeting Foam Cell Formation in Atherosclerosis: Therapeutic Potential of Natural Products

Foam cell formation and further accumulation in the subendothelial space of the vascular wall is a hallmark of atherosclerotic lesions. Targeting foam cell formation in the atherosclerotic lesions can be a promising approach to treat and prevent atherosclerosis. The formation of foam cells is determined by the balanced effects of three major interrelated biologic processes, including lipid uptake, cholesterol esterification, and cholesterol efflux. Natural products are a promising source for new lead structures. Multiple natural products and pharmaceutical agents can inhibit foam cell formation and thus exhibit antiatherosclerotic capacity by suppressing lipid uptake, cholesterol esterification, and/or promoting cholesterol ester hydrolysis and cholesterol efflux. This review summarizes recent findings on these three biologic processes and natural products with demonstrated potential to target such processes. Discussed also are potential future directions for studying the mechanisms of foam cell formation and the development of foam cell-targeted therapeutic strategies.

Oxidised Low-Density Lipoprotein and Its Receptor-Mediated Endothelial Dysfunction Are Associated with Coronary Artery Lesions in Kawasaki Disease

The study aimed to investigate the role of oxidised low-density lipoprotein (oxLDL)/lectin-like-oxLDL receptor-1 (LOX-1) in coronary artery lesions (CALs) in Kawasaki disease (KD) and of plasma oxLDL concentration in the early prediction of CALs in KD. This prospective study included 80 KD patients, 20 febrile and 20 healthy children. oxLDL, LOX-1 and other parameters were analysed in the acute phase. Plasma oxLDL concentration and LOX-1 mRNA expression in peripheral blood mononuclear cells (PBMCs) were significantly increased in KD patients compared with febrile and healthy children (P < 0.001 and P = 0.022, respectively), particularly in the group with CALs (P < 0.001 and P = 0.027, respectively). Coronary Z-score was significantly correlated with plasma oxLDL concentration and LOX-1 mRNA expression (r = 0.739 and 0.637, respectively; P < 0.01). The sensitivity and specificity of predicting CALs were 71.4% and 77.2%, respectively, at plasma oxLDL concentration ≥ 12.38 mU/L. oxLDL/LOX-1 may be involved in CAL development. The plasma oxLDL concentration in the acute phase is a potentially useful biological indicator for predicting CAL in KD patients.

Modulation of Nitric Oxide Synthases by Oxidized LDLs: Role in Vascular Inflammation and Atherosclerosis Development

The maintenance of physiological levels of nitric oxide (NO) produced by eNOS represents a key element for vascular endothelial homeostasis. On the other hand, NO overproduction, due to the activation of iNOS under different stress conditions, leads to endothelial dysfunction and, in the late stages, to the development of atherosclerosis. Oxidized LDLs (oxLDLs) represent the major candidates to trigger biomolecular processes accompanying endothelial dysfunction and vascular inflammation leading to atherosclerosis, though the pathophysiological mechanism still remains to be elucidated. Here, we summarize recent evidence suggesting that oxLDLs produce significant impairment in the modulation of the eNOS/iNOS machinery, downregulating eNOS via the HMGB1-TLR4-Caveolin-1 pathway. On the other hand, increased oxLDLs lead to sustained activation of the scavenger receptor LOX-1 and, subsequently, to NFkB activation, which, in turn, increases iNOS, leading to EC oxidative stress. Finally, these events are associated with reduced protective autophagic response and accelerated apoptotic EC death, which activates atherosclerotic development. Taken together, this information sheds new light on the pathophysiological mechanisms of oxLDL-related impairment of EC functionality and opens new perspectives in atherothrombosis prevention.

P38 MAPK signaling pathway mediates COM crystal-induced crystal adhesion change in rat renal tubular epithelial cells

The objective of the study is to clarify the mechanism of p38 mitogen-activated protein kinase (p38 MAPK) signaling pathway in the change of crystal adhesion in rat renal tubular epithelial cells (NRK-52E) induced by calcium oxalate monohydrate (COM) crystals. NRK-52E cells were divided into COM crystal-treated group and control group according to whether the cell culture medium contains different concentrations of COM crystals. The concentrations of lactate dehydrogenase in the both group medium were determined after being cultured for 24 h. Protein and RNA were extracted from both cell groups after being cultured at different time points. SB239063, an inhibitor of the activation of p38 MAPK, was pretreated for 2 h before incubation with COM crystals. Western blotting and RT-qPCR were performed to confirm the expression levels of relative genes. All the experimental results were summarized and analyzed by SPSS 20.0 statistical analysis software. COM crystals (146 µg/cm²) could induce the expression levels of NLRP3, caspase-1 and interleukin-1β (IL-1β) significantly increased in NRK-52E cells. Compared with the control group cells, the transcription and translation levels of p38 MAPK-related molecule (such as p-p38) and adhesion molecules (such as osteopontin, hyaluronic acid and CD44) were significantly increased in COM crystal-treated cells and can be inhibited by SB239063 and NLRP3 gene silencing. This study demonstrated that the p38 MAPK signaling pathway mediated the COM crystal-induced crystal adhesion change in NRK-52E cells and required the involvement of NLRP3 inflammasome.

Helicobacter pylori urease induces pro-inflammatory effects and differentiation of human endothelial cells: Cellular and molecular mechanism

BACKGROUND

Helicobacter pylori urease (HPU) is a key virulence factor that enables bacteria to colonize and survive in the stomach. We early demonstrated that HPU, independent of its catalytic activity, induced inflammatory and angiogenic responses in vivo and directly activated human neutrophils to produce reactive oxygen species (ROS). We have investigated the effects of HPU on endothelial cells, focusing on the signaling mechanism involved.

METHODS

Monolayers of human microvascular endothelial cells (HMEC-1) were stimulated with HPU (up to 10 nmol/L): Paracellular permeability was accessed through dextran-FITC passage. NO and ROS production was evaluated using intracellular probes. Proteins or mRNA expressions were detected by Western blotting and fluorescence microscopy or qPCR assays, respectively.

RESULTS

Treatment with HPU enhanced paracellular permeability of HMEC-1, preceded by VE-cadherin phosphorylation and its dissociation from cell-cell junctions. This caused profound alterations in actin cytoskeleton dynamics and focal adhesion kinase (FAK) phosphorylation. HPU triggered ROS and nitric oxide (NO) production by endothelial cells. Increased intracellular ROS resulted in nuclear factor kappa B (NF-κB) activation and upregulated expression of cyclooxygenase-2 (COX-2), hemeoxygenase-1 (HO-1), interleukin-1β (IL-1β), and intercellular adhesion molecule-1 (ICAM-1). Higher ICAM-1 and E-selectin expression was associated with increased neutrophil adhesion on HPU-stimulated HMEC monolayers. The effects of HPU on endothelial cells were dependent on ROS production and lipoxygenase pathway activation, being inhibited by esculetin. Additionally, HPU improved vascular endothelial growth factor receptor 2 (VEGFR-2) expression.

CONCLUSION

The data suggest that the pro-inflammatory properties of HPU drive endothelial cell to a ROS-dependent program of differentiation that contributes to the progression of H pylori infection.

OxHDL controls LOX-1 expression and plasma membrane localization through a mechanism dependent on NOX/ROS/NF-κB pathway on endothelial cells

Systemic inflammatory diseases enhance circulating oxidative stress levels, which results in the oxidation of circulating high-density lipoprotein (oxHDL). Endothelial cell function can be negatively impacted by oxHDL, but the underlying mechanisms for this remain unclear. Some reports indicate that the lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) is also a receptor for oxHDL. However, it is unknown if oxHDL induces increased LOX-1 expression at the plasma membrane, as an event that supports endothelial dysfunction. Therefore, the aims of this study were to determine if oxHDL induces plasma-membrane level changes in LOX-1 and, if so, to describe the underlying mechanisms in endothelial cells. Our results demonstrate that the incubation of arterial or vein endothelial cells with oxHDL (and not HDL) induces the increase of LOX-1 expression at the plasma membrane; effect prevented by LOX-1 inhibition. Importantly, same results were observed in endothelial cells from oxHDL-treated rats. Furthermore, the observed oxHDL-induced LOX-1 expression is abolished by the down-regulation of NOX-2 expression with siRNA (and no others NOX isoforms), by the pharmacological inhibition of NAD(P)H oxidase (with DPI or apocynin) or by the inhibition of NF-κB transcription factor. Coherently, LOX-1 expression is augmented by the incubation of endothelial cells with H₂O₂ or GSSG even in absence of oxHDL, indicating that the NOX-2/ROS/ NF-κB axis is involved. Interestingly, oxHDL incubation also increases TNF-α expression, cytokine that induces LOX-1 expression. Thus, our results suggest a positive feedback mechanism for LOX-1 receptor during inflammatory condition where an oxidative burst will generate oxHDL from native HDL, activating LOX-1 receptor which in turn will increase the expression of NOX-2, TNF-α and LOX-1 receptor at the plasma membrane. In conclusion, oxHDL-induced translocation of LOX-1 to the plasma membrane could constitute an induction mechanism of endothelial dysfunction in systemic inflammatory diseases.

Celastrol ameliorates Aspergillus fumigatus keratitis via inhibiting LOX-1

PURPOSE

To investigate the effect of Celastrol (CLT) on Aspergillus fumigatus (A. fumigatus) keratitis.

METHODS

Primary peritoneal macrophages of C57BL/6 mice were pretreated with CLT before A. fumigatus hyphae stimulation. C57BL/6 mice were infected with A. fumigatus. Mice corneas were treated with CLT from 1 day post infection. Clinical score, PCR, ELISA and Western blot were used to test expression of anti-inflammatory mediators, proinflammatory mediators and Lectin-like oxidized low-density lipoprotein receptor 1(LOX-1). The protein levels of p38MAPK after pretreated with CLT in macrophages of C57BL/6 mice challenged with A. fumigatus were tested by Western blot.

RESULTS

C57BL/6 mice treated with CLT from 1 day post infection showed decreased disease, IL-1β, TNF-α, IL-10, TGF-β, MIP-2 and LOX-1 levels. CLT treatment markedly inhibiting mRNA and proteins levels of anti-inflammatory mediators, proinflammatory mediators and LOX-1 in macrophages of C57BL/6 mice compared with control group. CLT pretreatment before A. fumigatus stimulation obviously inhibiting protein levels of p38MAPK versus DMSO pretreated group in macrophages of C57BL/6 mice challenged with A. fumigatus.

CONCLUSION

These data provide evidences that CLT ameliorates A. fumigatus keratitis of C57BL/6 mice via inhibiting LOX-1. CLT pretreatment before A. fumigatus stimulation decreased levels of inflammation in macrophages of C57BL/6 mice, which may be regulated by p-p38MAPK.

Targeting LOX-1 in atherosclerosis and vasculopathy: current knowledge and future perspectives

LOX-1 (lectin-like oxidized low-density lipoprotein receptor-1; also known as OLR1) is the dominant receptor that recognizes and internalizes oxidized low-density lipoproteins (ox-LDLs) in endothelial cells. Several genetic variants of LOX-1 are associated with the risk and severity of coronary artery disease. The LOX-1-ox-LDL interaction induces endothelial dysfunction, leukocyte adhesion, macrophage-derived foam cell formation, smooth muscle cell proliferation and migration, and platelet activation. LOX-1 activation eventually leads to the rupture of atherosclerotic plaques and acute cardiovascular events. In addition, LOX-1 can be cleaved to generate soluble LOX-1 (sLOX-1), which is a useful diagnostic and prognostic marker for atherosclerosis-related diseases in human patients. Of therapeutic relevance, several natural products and clinically used drugs have emerged as LOX-1 inhibitors that have antiatherosclerotic actions. We hereby provide an updated overview of role of LOX-1 in atherosclerosis and associated vascular diseases, with an aim to highlighting the potential of LOX-1 as a novel theranostic tool for cardiovascular disease prevention and treatment.

Albiflorin inhibits the formation of THP-1-derived foam cells through the LOX-1/NF-κB pathway

BACKGROUND

Foam cells are characteristic pathologic cells of atherosclerosis (AS), they are lipid-loaded macrophages present on atherosclerotic lesions. A large number of studies has shown that the pathogenesis of AS is the result of interactions between the lipid metabolism disorders and chronic inflammatory responses in the body. Albiflorin can inhibit the inflammatory response and it has shown a therapeutic effect on certain inflammatory diseases.

METHODS

In this study, a human acute monocytic leukemia cell line (THP-1)-derived foam cell model was established via oxidized low-density lipoprotein (ox-LDL) to observe the effects of albiflorin on the AS-characteristic foam cells.

RESULTS

Our results showed that, after the treatment with ox-LDL, macrophages induced by propylene glycol methyl ether acetate (PMA), presented large amounts of lipid deposition in their cytoplasm, indicating that the THP-1-derived foam cell model was successfully established. On the other hand, the same cells pretreated with albiflorin presented significantly reduced amounts of lipid deposition, and their contents of total cholesterol and triglyceride were also clearly lower. Besides, the expression levels of low-density lipoprotein receptor-1 (LOX-1) and nuclear factor-κB (NF-κB) were significantly decreased, and the expression levels of downstream factors interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) were also obviously decreased in the cells treated with albiflorin but not in the negative control cells. Moreover, after treatment of macrophages with different concentrations of ox-LDL, the expression levels of LOX-1 and NF-κB were up-regulated in an ox-LDL concentration-dependent manner, and so were the expression levels of IL-6 and TNF-α. And, it was found after treatment with LOX-1 neutralizing antibody or NF-κB inhibitor (during the foam cell formation induction via ox-LDL) that the lipid deposition in the cytoplasm of the cells was reduced, as in the cells treated with albiflorin.

CONCLUSIONS

Taken together, our findings suggest that albiflorin decreases lipid deposition in the cytoplasm and blocks the foaming process by regulating the LOX-1/NF-κB signaling pathway.

Oxidative Stress in Preeclampsia and Placental Diseases

Preeclampsia is a persistent hypertensive gestational disease characterized by high blood pressure and proteinuria, which presents from the second trimester of pregnancy. At the cellular level, preeclampsia has largely been associated with the release of free radicals by the placenta. Placenta-borne oxidative and nitrosative stresses are even sometimes considered as the major molecular determinants of the maternal disease. In this review, we present the recent literature evaluating free radical production in both normal and pathological placentas (including preeclampsia and other major pregnancy diseases), in humans and animal models. We then assess the putative effects of these free radicals on the placenta and maternal endothelium. This analysis was conducted with regard to recent papers and possible therapeutic avenues.

Ursolic Acid Attenuates Atherosclerosis in ApoE-/- Mice: Role of LOX-1 Mediated by ROS/NF-κB Pathway

Atherosclerosis, a chronic inflammatory disease, is a major contributor to cardiovascular diseases. Ursolic acid (UA) is a phytonutrient with widely biological effects including anti-oxidative, anti-inflammatory, and so on. At present, the effect of UA on atherosclerosis and the mechanism of action are still obscure. This study focused on investigating the effects of UA on atherosclerosis both in vivo and in vitro. We first selected LOX-1 as our target, which was reckoned as a new promising receptor for treating atherosclerosis. The evaluation in vitro suggested that UA significantly decreased endothelial LOX-1 expression induced by LPS both in mRNA and protein levels. Pre-treatment of UA also inhibited TLR4/MyD88 signaling activated by LPS. Moreover, UA reduced ROS production and suppressed the activation of NF-κB stimulated by LPS. Particularly, the evaluation in vivo further verified the conclusion obtained in vitro. In ApoE−/− mice fed with an atherogenic diet, both UA (100 mg/kg/day) and simvastatin significantly attenuated atherosclerotic plaque formation and shrunk necrotic core areas. The enhanced expression of LOX-1 in atherosclerotic aorta was also dramatically decreased by administration of UA. Taken together, these results suggested that UA, with anti-atherosclerotic activity through inhibition of LOX-1 mediated by ROS/NF-κB signaling pathways, may become a valuable vascular protective candidate for the treatment of atherosclerosis.

Repeated stimulation by LPS promotes the senescence of DPSCs via TLR4/MyD88-NF-κB-p53/p21 signaling

Dental pulp stem cells (DPSCs), one type of mesenchymal stem cells, are considered to be a type of tool cells for regenerative medicine and tissue engineering. Our previous studies found that the stimulation with lipopolysaccharide (LPS) might introduce senescence of DPSCs, and this senescence would have a positive correlation with the concentration of LPS. The β-galactosidase (SA-β-gal) staining was used to evaluate the senescence of DPSCs and immunofluorescence to show the morphology of DPSCs. Our findings suggested that the activity of SA-β-gal has increased after repeated stimulation with LPS and the morphology of DPSCs has changed with the stimulation with LPS. We also found that LPS bound to the Toll-like receptor 4 (TLR4)/myeloid differentiation factor (MyD) 88 signaling pathway. Protein and mRNA expression of TLR4, MyD88 were enhanced in DPSCs with LPS stimulation, resulting in the activation of nuclear factor-κB (NF-κB) signaling, which exhibited the expression of p65 improved in the nucleus while the decreasing of IκB-α. Simultaneously, the expression of p53 and p21, the downstream proteins of the NF-κB signaling, has increased. In summary, DPSCs tend to undergo senescence after repeated stimulation in an inflammatory microenvironment. Ultimately, these findings may lead to a new direction for cell-based therapy in oral diseases and other regenerative medicines.

Fluid shear stress regulates the expression of Lectin-like oxidized low density lipoprotein receptor-1 via KLF2-AP-1 pathway depending on its intensity and pattern in endothelial cells

BACKGROUND AND AIMS

Vascular endothelial cells (ECs) are exposed to fluid shear stress (FSS), which modulates vascular pathophysiology. Lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) is crucial in endothelial dysfunction and atherosclerosis. We elucidated the mechanism regulating LOX-1 expression in ECs by FSS.

METHODS

Human umbilical vein endothelial cells were exposed to laminar shear stress (LSS) of indicated intensities using a unidirectional steady flow, or to oscillatory shear stress (OSS) using a bidirectional disturbed flow. In vivo studies were performed in a mouse model of partial carotid ligation and human pulmonary artery sections.

RESULTS

Within ECs, OSS upregulated LOX-1 expression, while LSS (20 dyne/cm²) downregulated it. We confirmed that OSS-induced LOX-1 expression was suppressed when the mechanotransduction was inhibited by knockdown of the mechanosensory complex. In addition, we demonstrated that Kruppel-like factor 2 (KLF2) has an inhibitory role on OSS-induced LOX-1 expression. Next, we determined that activator protein-1 (AP-1) was the key transcription factor inducing LOX-1 expression by OSS, which was inhibited by KLF2 overexpression. To explore whether the intensity of LSS affects LOX-1 expression, we tested three different intensities (20, 60, and 120 dyne/cm²) of LSS. We observed higher LOX-1 expression with high shear stresses of 120 dyne/cm² compared to 20 and 60 dyne/cm², with OSS-like KLF2-AP-1 signaling patterns. Furthermore, ECs within disturbed flow regions showed upregulated LOX-1 expression in vivo.

CONCLUSIONS

We concluded that LOX-1 expression on ECs is regulated via FSS depending on its intensity as well as pattern. Furthermore, this is mediated through the KLF2-AP1 pathway of mechanotransduction.

Ginsenoside F1 Ameliorates Endothelial Cell Inflammatory Injury and Prevents Atherosclerosis in Mice through A20-Mediated Suppression of NF-kB Signaling

Atherosclerosis (AS) is a chronic inflammatory disease and endothelial cell injury is the initial event. In this study, we investigated the protective effects of ginsenoside F1 (GF1) on AS and the potential molecular mechanisms of ox-LDL induced endothelial injury. ApoE-/- mice were fed a high fat diet and orally treated with GF1 (50 mg/kg/day) for 8 weeks. Atherosclerotic plaque and LOX-1, TLR4, NF-κB expression levels in the aortic root and inflammatory factor MPO in whole body were measured. The treatment with GF1 induced a remarkable reduction in the atherosclerotic lesion area, LOX-1, TLR4 expression and decreased the MPO distribution. Meanwhile, in vitro study, we confirmed that GF1 treatment greatly increased ox-LDL-injured endothelial cell viability, ameliorated LOX-1, TLR4 expression levels and reduced monocytes adhesion. Protein microarray demonstrated that GF1 significantly inhibited G-CSF, ICAM-1, MIP-1δ, IL-1α, IL-15, IL-16 levels. Mechanistically, the GF1 treatment suppressed the NF-κB nuclear translocation. Furthermore, our data indicated that GF1 significantly increased A20 expression level and A20 siRNA markedly abolished the attenuation of GF1 on NF-κB nuclear translocation and inflammatory factors expression. Our results suggest that the GF1 may be a potential drug for anti-atherosclerosis.

Osthole inhibited TGF β-induced epithelial-mesenchymal transition (EMT) by suppressing NF-κB mediated Snail activation in lung cancer A549 cells

Epithelial-mesenchymal transition (EMT), the transdifferentiation of epithelial cells into mesenchymal cells, has been implicated in the metastasis and provides novel strategies for cancer therapy. Osthole (OST), a dominant active constituent of Chinese herb Cnidium monnieri, has been reported to inhibit cancer metastasis while the mechanisms remains unclear. Here, we studied the inhibitory effect and mechanisms of OST on TGF-β1-induced EMT in A549 cells. Cells were treated with TGF-β1 in the absence and presence of OST. The morphological alterations were observed with a microscopy. The protein and mRNA expressions were determined by Western blotting and real-time PCR. The protein localization was detected with immunofluorescence. The adhesion, migration, and invasion were determined by Matrigel, wound-healing, and Transwell assays. TGF-β1 treatment induced spindle-shaped alterations of cells, upregulation of N-cadherin, Vimentin, NF-κB p65, and downregulation of E-cadherin. Dysregulated membrane expression and mRNA expression of E-cadherin and N-cadherin were observed after TGF-β1 treatment. TGF-β1 increased abilities of migration and invasion and triggered the nuclear translocation of NF-κB p65. These alterations were dramatically inhibited by OST. Furthermore, PDTC, a NF-κB inhibitor, showed similar effects. In addition, TGF-β1-induced expression of Snail was significantly inhibited by OST and silenced Snail partially reversed TGF-β1-induced EMT biomarkers without affecting NF-κB p-65. In conclusion, OST inhibited TGF-β1-induced EMT, adhesion, migration, and invasion through inactivation of NF-κB-Snail pathways in A549 cells. This study provides novel molecular mechanisms for the anti-metastatic effect of OST.

Dioscin relieves endotoxemia induced acute neuro-inflammation and protect neurogenesis via improving 5-HT metabolism

Sepsis, in addition to causing fatality, is an independent risk factor for cognitive impairment among sepsis survivors. The pathologic mechanism of endotoxemia induced acute neuro-inflammation still has not been fully understood. For the first time, we found the disruption of neurotransmitters 5-HT, impaired neurogenesis and activation of astrocytes coupled with concomitant neuro-inflammation were the potential pathogenesis of endotoxemia induced acute neuro-inflammation in sepsis survivors. In addition, dioscin a natural steroidal saponin isolated from Chinese medicinal herbs, enhanced the serotonergic system and produced anti-depressant effect by enhancing 5-HT levels in hippocampus. What is more, this finding was verified by metabolic analyses of hippocampus, indicating 5-HT related metabolic pathway was involved in the pathogenesis of endotoxemia induced acute neuro-inflammation. Moreover, neuro-inflammation and neurogenesis within hippocampus were indexed using quantitative immunofluorescence analysis of GFAP DCX and Ki67, as well as real-time RT-PCR analysis of some gene expression levels in hippocampus. Our in vivo and in vitro studies show dioscin protects hippocampus from endotoxemia induced cascade neuro-inflammation through neurotransmitter 5-HT and HMGB-1/TLR4 signaling pathway, which accounts for the dioscin therapeutic effect in behavioral tests. Therefore, the current findings suggest that dioscin could be a potential approach for the therapy of endotoxemia induced acute neuro-inflammation.

Association of the LOX-1 rs1050283 Polymorphism with Risk for Atherosclerotic Cerebral Infarction and its Effect on sLOX-1 and LOX-1 Expression in a Chinese Population

AIMS

The interaction between lectin-like oxidized low density lipoprotein (LDL) receptor-1 (LOX-1) and oxidized LDL (ox-LDL) has been viewed as an important pathogenic factor for cardiovascular diseases. This study aimed to explore the association of a functional polymorphism rs1050283 in the 3'-untranslated region of the LOX-1 gene with atherosclerotic cerebral infarction (ACI) susceptibility, and we also investigated the effects of the rs1050283 polymorphism on LOX-1 expression and serum levels of sLOX-1 in patients with ACI.

METHODS

A case-controlled study was performed in 526 patients with ACI and 640 healthy controls. Genotyping was performed by DNA sequencing method. Real-time PCR and Western blotting were used to determine the level of LOX-1 expression. Serum levels of sLOX-1 were quantified using ELISA according to the manufacturer's instruction.

RESULTS

The results of the present study showed that the frequency of rs1050283 T allele was significantly higher in patients with ACI than in healthy controls. We also found that the rs1050283 polymorphism T allele was associated with increased LOX-1 expression at mRNA and protein levels in patients with ACI. Furthermore, we also observed that among patients with ACI, those with the rs1050283 T allele showed an increased serum level of sLOX-1.

CONCLUSION

Our research demonstrated that the rs1050283 T allele of LOX-1 is strongly associated with an increased risk for ACI in a Chinese population, which also affects levels of LOX-1 and sLOX-1.

Dihydrotanshinone I Attenuates Atherosclerosis in ApoE-Deficient Mice: Role of NOX4/NF-κB Mediated Lectin-Like Oxidized LDL Receptor-1 (LOX-1) of the Endothelium

Dihydrotanshinone I (DHT) is a natural compound extracted from Salvia miltiorrhiza Bunge which has been widely used for treating cardiovascular diseases. However, its role in atherosclerosis remains unclear. In this study, the effect of DHT on atherosclerosis were investigated using apolipoprotein E-deficient (ApoE^-/-) mice and endothelial cells. In lipopolysaccharide (LPS)-stimulated human umbilical vein endothelial cells (HUVECs), DHT (10 nM) decreased lectin-like ox-LDL receptor-1 (LOX-1) and NADPH oxidase 4 (NOX4) expression, reactive oxygen species (ROS) production, NF-κB nuclear translocation, ox-LDL endocytosis and monocytes adhesion. Silence NOX4 inhibited LPS-induced LOX-1 expression, NF-κB nuclear translocation, ox-LDL endocytosis and monocytes adhesion. In ApoE^-/- mice fed with an atherogenic diet, DHT (10 and 25 mg kg^-1) significantly attenuated atherosclerotic plaque formation, altered serum lipid profile, decreased oxidative stress and shrunk necrotic core areas. The enhanced expression of LOX-1, NOX4, and NF-κB in aorta was also dramatically inhibited by DHT. In conclusion, these results suggested that DHT showed anti-atherosclerotic activity through inhibition of LOX-1 mediated by NOX4/NF-κB signaling pathways both in vitro and in vivo. This finding suggested that DHT might be used as a potential vascular protective candidate for the treatment of atherosclerosis.

TLR-7 agonist attenuates airway reactivity and inflammation through Nrf2-mediated antioxidant protection in a murine model of allergic asthma

Toll-like receptors (TLRs) through innate immune system recognize pathogen associated molecular patterns and play an important role in host defense against bacteria, fungi and viruses. TLR-7 is responsible for sensing single stranded nucleic acids of viruses but its activation has been shown to be protective in mouse models of asthma. The NADPH oxidase (NOX) enzymes family mainly produces reactive oxygen species (ROS) in the lung and is involved in regulation of airway inflammation in response to TLRs activation. However, NOX-4 mediated signaling in response to TLR-7 activation in a mouse model of allergic asthma has not been explored previously. Therefore, this study investigated the role TLR-7 activation and downstream oxidant-antioxidant signaling in a murine model of asthma. Mice were sensitized with ovalbumin (OVA) intraperitoneally and treated with TLR-7 agonist, resiquimod (RSQ) intranasally before each OVA challenge from days 14 to 16. Mice were then assessed for airway reactivity, inflammation, and NOX-4 and nuclear factor E2-related factor 2 (Nrf2) related signaling [inducible nitric oxide synthase (iNOS), nitrotyrosine, lipid peroxides and copper/zinc superoxide dismutase (Cu/Zn SOD)]. Treatment with RSQ reduced allergen induced airway reactivity and inflammation. This was paralleled by a decrease in ROS which was due to induction of Nrf2 and Cu/Zn SOD in RSQ treated group. Inhibition of MyD88 reversed RSQ-mediated protective effects on airway reactivity/inflammation due to reduction in Nrf2 signaling. SOD inhibition produced effects similar to MyD88 inhibition. The current study suggests that TLR-7 agonist is beneficial and may be developed into a therapeutic option in allergic asthma.

The Interplay of Reactive Oxygen Species, Hypoxia, Inflammation, and Sirtuins in Cancer Initiation and Progression

The presence of ROS is a constant feature in living cells metabolizing O2. ROS concentration and compartmentation determine their physiological or pathological effects. ROS overproduction is a feature of cancer cells and plays several roles during the natural history of malignant tumor. ROS continuously contribute to each step of cancerogenesis, from the initiation to the malignant progression, acting directly or indirectly. In this review, we will (a) underline the role of ROS in the pathway leading a normal cell to tumor transformation and progression, (b) define the multiple roles of ROS during the natural history of a tumor, (c) conciliate many conflicting data about harmful or beneficial effects of ROS, (d) rethink the importance of oncogene and tumor suppressor gene mutations in relation to the malignant progression, and (e) collocate all the cancer hallmarks in a mechanistic sequence which could represent a "physiological" response to the initial growth of a transformed stem/pluripotent cell, defining also the role of ROS in each hallmark. We will provide a simplified sketch about the relationships between ROS and cancer. The attention will be focused on the contribution of ROS to the signaling of HIF, NFκB, and Sirtuins as a leitmotif of cancer initiation and progression.

Cryptotanshinone inhibits oxidized LDL-induced adhesion molecule expression via ROS dependent NF-κB pathways

Adhesion molecules, such as intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), and E-selectin, play important roles in the initial stage of atherosclerosis. Cryptotanshinone (CPT), a natural compound isolated from Salvia miltiorrhiza Bunge, exhibits anti-atherosclerotic activity although the underlying mechanisms remain elusive. In this study, the protective effect of CPT against oxidized low-density lipoprotein (ox-LDL)-induced adhesion molecule expression was investigated in human umbilical vein endothelial cells. Ox-LDL significantly induced ICAM-1, VCAM-1, and E-selectin expression at the mRNA and protein levels but reduced eNOS phosphorylation and NO generation, which were reversed by CPT pretreatment. Sodium nitroprusside, a NO donor, N-acetyl-L-cysteine (NAC), a reactive oxygen species (ROS) scavenger, and BAY117082, a NF-κB inhibitor, inhibited ox-LDL-induced ICAM-1, VCAM-1, and E-selectin expression. Ox-LDL-induced ROS production was significantly inhibited by CPT and NAC. Furthermore, ox-LDL activated the NF-κB signaling pathway by inducing phosphorylation of IKKβ and IκBα, promoting the interaction of IKKβ and IκBα, and increasing p65 nuclear translocation, which were significantly inhibited by CPT. In addition, CPT, NAC, and BAY117082 inhibited ox-LDL-induced membrane expression of ICAM-1, VCAM-1, E-selectin, and endothelial-monocyte adhesion and restored eNOS phosphorylation and NO generation. Results suggested that CPT inhibited ox-LDL-induced adhesion molecule expression by decreasing ROS and inhibiting the NF-κB pathways, which provides new insight into the anti-atherosclerotic mechanism of CPT.

EGCG attenuates atherosclerosis through the Jagged-1/Notch pathway

Atherosclerosis is the most common cause of cardiovascular diseases worldwide. Oxidized low-density lipoprotein (ox-LDL) is a particularly important risk factor in the pathogenesis of atherosclerosis. Accumulating evidence has indicated that epigallocatechin-3-gallate (EGCG; a catechin found in the popular beverage, greent tea) protects against ox-LDL-induced atherosclerosis. However, the underlying mechanisms remain unclear. In the present study, ox-LDL (100 mg/l) induced damage to, and the apoptosis of human umbilical vein endothelial cells (HUVECs) by reducing endothelial nitric oxide synthase (eNOS) expression and promoting inducible nitric oxide synthase (iNOS) expression; these effects were abrogated by the addition of 50 µM EGCG. Furthermore, ox-LDL rapidly activated the membrane translocation of p22phox, and altered the protein expression of Jagged-1 and Notch pathway-related proteins [Math1, hairy and enhancer of split (HES)1 and HES5]; these effects were also prevented by pre-treatment with 50 µM EGCG. In addition, Jagged-1 played a significant role in the EGCG-mediated protection against ox-LDL-induced apoptosis and ox-LDL‑diminished cell adhesion in the HUVECs. Finally, EGCG inhibited high-fat diet (HFD)-induced atherosclerosis in apolipoprotein E (ApoE) knockout (ApoE-KO) mice through the Jagged-1/Notch pathway. Taken together, these findings demonstrate that 50 µM EGCG protects against ox-LDL-induced endothelial dysfunction through the Jagged-1/Notch signaling pathway. Moreover, our data provide insight into the possible molecular mechanisms through which EGCG attenuates ox-LDL‑induced vascular endothelial dysfunction.

Oxidative stress response and Nrf2 signaling in aging

Increasing oxidative stress, a major characteristic of aging, has been implicated in a variety of age-related pathologies. In aging, oxidant production from several sources is increased, whereas antioxidant enzymes, the primary lines of defense, are decreased. Repair systems, including the proteasomal degradation of damaged proteins, also decline. Importantly, the adaptive response to oxidative stress declines with aging. Nrf2/EpRE signaling regulates the basal and inducible expression of many antioxidant enzymes and the proteasome. Nrf2/EpRE activity is regulated at several levels, including transcription, posttranslation, and interactions with other proteins. This review summarizes current studies on age-related impairment of Nrf2/EpRE function and discusses the changes in Nrf2 regulatory mechanisms with aging.

Parthenolide inhibits LPS-induced inflammatory cytokines through the toll-like receptor 4 signal pathway in THP-1 cells

Parthenolide (PTL) shows potent anti-inflammatory and anti-cancer activities. In the present study, the molecular mechanisms of PTL's activities were explored in lipopolysaccharide (LPS)-induced human leukemia monocytic THP-1 cells and human primary monocytes. The 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium salt (MTS) assay was used to analyze the effect of PTL on THP-1 cell viability. Enzyme-linked immunosorbent assay was used to determine the effect of PTL on LPS-induced inflammatory cytokine secretion. Flow cytometry and quantitative real-time polymerase chain reaction were used to assess the effect of PTL on LPS-induced toll-like receptor 4 (TLR4) expression. Phosphorylation levels of signaling molecules were determined by western blot analysis. Results showed that PTL <12.5 μM did not significantly affect THP-1 cells viability. LPS treatment led to a marked up-regulation of interleukin (IL)-6, IL-1β, IL-8, IL-12p40, tumor necrosis factor-α, IL-18, and NO in THP-1 cells. However, PTL inhibited the expression of these cytokines in a dose-dependent manner, with IC50 values of 1.091-2.620 μM. PTL blocked TLR4 expression with an IC50 value of 1.373 μM as determined by the flow cytometry analysis, and this blocking effect was verified at both protein and mRNA levels. Up-regulation of phosphorylation levels of extracellular signal-regulated kinase 1/2, Jun N-terminal kinase, p38, nuclear factor κB (NF-κB) p65, and IκBα and up-regulation of expressions of other molecules (inducible nitric oxide synthase, TLR4, and TNF receptor-associated factor 6) induced by LPS were abolished by PTL in a dose-dependent manner. The anti-inflammatory mechanisms of PTL operate partly through the TLR4-mediated mitogen-activated protein kinase and NF-κB signaling pathways. Therefore, TLR4 may be a new target for anti-inflammation therapies.

Molecular mechanisms of maternal vascular dysfunction in preeclampsia

In preeclampsia, as a heterogeneous syndrome, multiple pathways have been proposed for both the causal as well as the perpetuating factors leading to maternal vascular dysfunction. Postulated mechanisms include imbalance in the bioavailability and activity of endothelium-derived contracting and relaxing factors and oxidative stress. Studies have shown that placenta-derived factors [antiangiogenic factors, microparticles (MPs), cell-free nucleic acids] are released into the maternal circulation and act on the vascular wall to modify the secretory capacity of endothelial cells and alter the responsiveness of vascular smooth muscle cells to constricting and relaxing stimuli. These molecules signal their deleterious effects on the maternal vascular wall via pathways that provide the molecular basis for novel and effective therapeutic interventions.