Tanshinone IIA attenuates atherosclerosis via inhibiting NLRP3 inflammasome activation.

Tanshinone IIA (Tan IIA) possesses potent anti-atherogenic function, however, the underlying pharmacological mechanism remains incompletely understood. Previous studies suggest that oxidized LDL (oxLDL)-induced NLRP3 (NOD-like receptor (NLR) family, pyrin domain-containing protein 3) inflammasome activation in macrophages plays a vital role in atherogenesis. Whether the anti-atherogenic effect of Tan IIA relies on the inhibition of the NLRP3 inflammasome has not been investigated before. In this study, we found that Tan IIA treatment of high-fat diet fed ApoE-/- mice significantly attenuated NLRP3 inflammasome activation in vivo. Consistently, Tan IIA also potently inhibited oxLDL-induced NLRP3 inflammasome activation in mouse macrophages. Mechanically, Tan IIA inhibited NF-κB activation to downregulate pro-interleukin (IL) -1ß and NLRP3 expression, and decreased oxLDL-induced expression of lectin-like oxidized LDL receptor-1 (LOX-1) and cluster of differentiation 36 (CD36), thereby attenuating oxLDL cellular uptake and subsequent induction of mitochondrial and lysosomal damage - events that promote the NLRP3 inflammasome assembly. Through regulating both the inflammasome 'priming' and 'activation' steps, Tan IIA potently inhibited oxLDL-induced NLRP3 inflammasome activation, thereby ameliorating atherogenesis.

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.

Expression and Characterization of a Single-Chain Variable Fragment against Human LOX-1 in Escherichia coli and Brevibacillus choshinensis.

The single-chain variable fragment (scFv) against lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) is a promising molecule for its potential use in the diagnosis and immunotherapy of atherosclerosis. Producing this scFv in several milligram amounts could be the starting point for further engineering and application of the scFv. In this study, the abundant expression of the anti-LOX-1 scFv was attempted using Escherichia coli (E. coli) and Brevibacillus choshinensis (B. choshinensis). The scFv had limited soluble yield in E. coli, but it was efficiently secreted by B. choshinensis. The optimized fermentation was determined using the Plackett-Burman screening design and response surface methodology, under which the yield reached up to 1.5 g/l in a 5-L fermentor. Moreover, the properties of the scFvs obtained from the two expression systems were different. The antigen affinity, transition temperature, and particle diameter size were 1.01E-07 M, 55.2 ± 0.3°C, and 9.388 nm for the scFv expressed by B. choshinensis, and 4.53E-07 M, 52.5 ± 0.3°C, and 13.54 nm for the scFv expressed by E. coli. This study established an efficient scale-up production methodology for the anti-LOX-1 scFv, which will boost its use in LOX-1-based therapy.

ATRQß-001 vaccine prevents atherosclerosis in apolipoprotein E-null mice.

OBJECTIVE: Angiotensin II (AngII) type 1 receptor (AT1R) blockers have been proved to reduce atherosclerosis. Previously, we have invented ATRQß-001 vaccine which showed a desirable blocking effect for AT1R. The purpose of this study was to investigate whether ATRQß-001 vaccine would prevent atherosclerosis in apolipoprotein E-null (ApoE-/-) mice. METHODS: Male ApoE-/- mice were administered with ATRQß-001 vaccine, Qß virus-like particles, valsartan or vehicle over a period of 24 weeks. In vitro, human coronary artery endothelial cells preincubated with the anti-ATR-001 antibody, the neutralization antibody or valsartan for 2  h, were treated with AngII for 24  h. Histological stain and molecule biology methods were used to assess the atheroprotective effect of the vaccine. RESULTS: ATRQß-001 vaccine significantly reduced the lesion area and promoted the stability of atherosclerotic plaque. Meanwhile, macrophage infiltration as well as the expressions of adhesion molecules and monocyte chemoattractant protein-1 was obviously decreased in the ATRQß-001 vaccine group. Additionally, the vaccine markedly reduced the apoptosis in the lesions of the ApoE-/- mice. In vitro, the anti-ATR-001 antibody inhibited endothelial apoptosis induced by AngII. Furthermore, ATRQß-001 vaccine exhibited a dramatical attenuation in the expressions of lectin-like oxidized low-density lipoprotein receptor-1 and AT1R in the aortic. More importantly, compared with the valsartan group, no obvious feedback of the plasma renin-angiotensin system was elicited in the vaccine group. CONCLUSION: The results demonstrated that ATRQß-001 vaccine reduced the progression of atherosclerosis in ApoE-/- mice without obvious feedback of renin-angiotensin system.

A fermented bean flour extract downregulates LOX-1, CHOP and ICAM-1 in HMEC-1 stimulated by ox-LDL.

This study focused on an extract from fermented flour from the Lady Joy variety of the common bean Phaseolus vulgaris. The extract, Lady Joy lysate (Lys LJ), is enriched in antioxidant compounds during the fermentation. We assessed it for its protective effect on endothelial cells treated with oxidized-LDL (ox-LDL). The oxidative stress was determined by measuring the contents of thiobarbituric acid-reactive substances and reactive oxygen metabolites. ICAM-1, ET-1 and IL-6 concentrations were assessed using ELISA. LOX-1 and CHOP expression were analyzed using both quantitative RT-PCR and ELISA or western blotting. Ox-LDL treatment induced significant oxidative stress, which was strongly reduced by pre-treatment with the extract. The ox-LDL exposure significantly enhanced ICAM-1, IL-6 and ET-1 levels over basal levels. Lys LJ pre-treatment exerted an inhibitory effect on ox-LDL-induced endothelial activation with ICAM-1 levels comparable to those for the untreated cells. IL-6 and ET-1 production, although reduced, was still significantly higher than for the control. Both LOX-1 and CHOP expression were upregulated after ox-LDL exposure, but this effect was significantly decreased after Lys LJ pre-treatment. Lys LJ alone did not alter the ICAM-1, IL-6 and ET-1 concentrations or CHOP expression, but it did significantly lower the LOX-1 protein level. Our data suggest that Lys LJ is an effective antioxidant that is able to inhibit the oxidation process, but that it is only marginally active against inflammation and ET-1 production in HMEC-1 exposed to ox-LDL.

Sesamol reduces the atherogenicity of electronegative L5 LDL in vivo and in vitro.

Highly electronegative low-density lipoprotein (LDL) L5 induces endothelial cell (EC) apoptosis, which leads to the development of atherosclerosis. We examined the effects of sesamol (1), a natural organic component of sesame oil, on plasma L5 levels and atherosclerosis development in a rodent model and on the L5-induced apoptosis of ECs. Syrian hamsters, which have an LDL profile similar to that of humans, were fed a normal chow diet (control), a high-fat diet (HFD), or a HFD supplemented with the administration of 50 or 100 mg/kg of 1 via oral gavage (HFD+1) for 16 weeks (n = 8 per group). Hamsters in the HFD+1 groups had reduced plasma L5 levels when compared with the HFD group. Oil Red O staining showed that atherosclerotic lesion size was markedly reduced in the aortic arch of hamsters in the HFD+1 groups when compared with that in the HFD group. In human aortic ECs, 0.3-3 µM 1 blocked L5-induced apoptosis in a dose-dependent manner. Further mechanistic studies showed that 1 inhibited the L5-induced lectin-like oxidized LDL receptor-1 (LOX-1)-dependent phosphorylation of p38 MAPK and activation of caspase-3 and increased phosphorylation of eNOS and Akt. Our findings suggest that sesamol (1) protects against atherosclerosis by reducing L5-induced atherogenicity.

Losartan attenuated lipopolysaccharide-induced lung injury by suppression of lectin-like oxidized low-density lipoprotein receptor-1.

INTRODUCTION: Recent study has shown that renin-angiotensin system plays an important role in the development of acute lung injury (ALI) with high level of angiotensin II (AngII) generated form AngI catalyzed by angiotensin-converting enzyme. AngII plays a major effect mainly through AT1 receptor. Therefore, we speculate inhibition of AT1 receptor may possibly attenuate the lung injury. Losartan, an antagonist of AT1 receptor for angiotensin II, attenuated lung injury by alleviation of the inflammation response in ALI, but the mechanism of losartan in ALI still remains unclear. METHODS: Thirty male Sprague-Dawley rats were randomly divided into Control group, ALI group (LPS), and Losartan group (LPS + Losartan). Bronchoalveolar lavage fluid (BALF) and lung tissue were obtained for analysis. The expressions of lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1), intercellular adhesion molecule-1 (ICAM-1) and caspase-3 were detected by reverse transcriptase polymerase chain reaction (RT-PCR) and western blotting. RESULTS: In ALI group, TNF-α and protein level in BALF, MPO activity in lung tissue, pulmonary edema and lung injury were significantly increased. Losartan significantly reduced LPS-induced increase in TNF-α and protein level in BALF, MPO activity, pulmonary edema and lung injury in LPS-induced lung injury. The mRNA and protein expression levels of LOX-1 were significantly decreased with the administration of losartan in LPS-induced lung injury. Also, losartan blocked the protein levels of caspase-3 and ICAM-1 mediated by LOX-1 in LPS-induced lung injury. CONCLUSIONS: Losartan attenuated lung injury by alleviation of the inflammation and cell apoptosis by inhibition of LOX-1 in LPS-induced lung injury.

Role of oxidized LDL and lectin-like oxidized LDL receptor-1 in cerebral vasospasm after subarachnoid hemorrhage.

OBJECT: Cerebral vasospasm after subarachnoid hemorrhage (SAH) is a serious complication. Free radicals derived from subarachnoid clotting are recognized to play an important role. Oxidized low-density lipoprotein (ox-LDL) and lectin-like oxidized LDL receptor-1 (LOX-1) have been shown to be related to the pathogenesis of atherosclerosis and may increase in cerebral arteries after SAH, due to the action of free radicals derived from a subarachnoid clot. These molecules may also affect the pathogenesis of vasospasm, generating intracellular reactive oxygen species and downregulating the expression of endothelial NO synthase (eNOS). If so, apple polyphenol might be effective in the prevention of vasospasm due to an abundant content of procyanidins, which exhibit strong radical scavenging effects, and the ability to suppress ox-LDL and LOX-1. The purposes of this study were to investigate changes in levels of ox-LDL and LOX-1 after SAH and whether administering apple polyphenol can modify cerebral vasospasm. METHODS: Forty Japanese white rabbits were assigned randomly to 4 groups: an SAH group (n = 10); a shamoperation group (n = 10), which underwent intracisternal saline injection; a low-dose polyphenol group (n = 10) with SAH and oral administration of apple polyphenol at 10 mg/kg per day from Day 0 to Day 3; and a high-dose polyphenol group (n = 10) with SAH and oral administration of apple polyphenol at 50 mg/kg per day. At Day 4, the basilar artery and brain was excised from each rabbit. The degree of cerebral vasospasm was evaluated by measuring the cross-sectional area of each basilar artery, and the expression of ox-LDL, LOX-1, and eNOS was examined for each basilar artery by immunohistochemical staining and reverse transcriptase polymerase chain reaction. In addition, neuronal apoptosis in the cerebral cortex was evaluated by TUNEL. RESULTS: Compared with the sham group, the expression of ox-LDL and LOX-1 in the basilar arterial wall was significantly increased in the SAH group, the expression of eNOS was significantly decreased, and the cross-sectional area of basilar artery was significantly decreased. Compared with the SAH group, the cross-sectional area of basilar artery was increased in the polyphenol groups, together with the decreased expression of ox-LDL and LOX-1 and the increased expression of eNOS. In the high-dose polyphenol group, those changes were statistically significant compared with the SAH group. In the low-dose polyphenol group, those changes were smaller than in the high-dose polyphenol group. No apoptosis and no changes were seen in the cerebral cortex in all groups. CONCLUSIONS: This is the first study suggesting that ox-LDL and LOX-1 increase due to SAH and that they may play a role in the pathogenesis of vasospasm. It is assumed that procyanidins in apple polyphenol may inhibit a vicious cycle of ox-LDL, LOX-1, and ROS in a dose-dependent manner. Apple polyphenol is a candidate for preventive treatment of cerebral vasospasm.

LOX-1 expression and oxidized LDL uptake and toxicity in the HN33 neuronal cell line.

Cardiovascular risk factors appear to influence the risk and progression of neurodegenerative disease, but the mechanisms involved are poorly understood. We investigated the possible involvement of oxidized low-density lipoprotein receptor (LOX-1) and oxidized low-density lipoprotein (Ox-LDL) in neurodegeneration by studying the expression of LOX-1 and the effects of Ox-LDL in HN33 cells, a neuronal cell line of central nervous system origin. HN33 cells showed LOX-1 protein expression, hypoxic induction of LOX-1, Ox-LDL uptake and Ox-LDL toxicity. LOX-1/Ox-LDL signaling may contribute to the association between cardiovascular risk factors and neurodegenerative disease.

EETs alleviate ox-LDL-induced inflammation by inhibiting LOX-1 receptor expression in rat pulmonary arterial endothelial cells.

Oxidized low-density lipoprotein (Ox-LDL) is associated with atherosclerotic events through the modulation of arachidonic acid (AA) metabolism and activation of inflammatory signaling. Cytochrome P450 (CYP) epoxygenase-derived epoxyeicosatrienoic acids (EETs) mitigate inflammation through nuclear factor-κB (NF-κB). In this study, we explored the effects and mechanisms of exogenous EETs on the ox-LDL-induced inflammation of pulmonary artery endothelial cells (PAECs), which were cultured from rat pulmonary arteries. We determined that pre-treatment with 11,12-EET or 14,15-EET attenuated the ox-LDL-induced expression and release of intercellular adhesion molecule-1 (ICAM-1), E-selectin, and monocyte chemoattractant protein-1 (MCP-1) in a concentration-dependent manner. In addition, the ox-LDL-induced expression of CYP2J4 was upregulated by 11,12-EET and 14,15-EET (1µM). Furthermore, the endothelial receptor of lectin-like oxidized low-density lipoprotein (LOX-1) was downregulated in PAECs treated with EETs. The inflammatory responses evoked by ox-LDL (100µg/mL) were blocked by pharmacological inhibitors of Erk1/2 mitogen-activated protein kinase (MAPK) (U0126), p38 MAPK (SB203580), and NF-κB (PDTC). In addition, we confirmed that 11,12-EET suppresses phosphorylation of p38, degradation of IκBα, and activation of NF-κB (p65), whereas 14,15-EET can significantly suppress the phosphorylation of p38 and Erk1/2. Our results indicate that EETs exert beneficial effects on ox-LDL-induced inflammation primarily through the inhibition of LOX-1 receptor upregulation, MAPK phosphorylation, and NF-κB activation and through the upregulation of CYP2J4 expression. This study helps focus the current understanding of the contribution of EETs to the regulation of the inflammation of pulmonary vascular endothelial cells. Furthermore, the therapeutic potential of targeting the EET pathway in pulmonary vascular disease will be highlighted.

The hydrogen sulfide donor, GYY4137, exhibits anti-atherosclerotic activity in high fat fed apolipoprotein E(-/-) mice.

BACKGROUND AND PURPOSE: Atherosclerosis is associated with reduced vascular hydrogen sulfide (H2 S) biosynthesis. GYY4137 is a novel slow-releasing H2 S compound that may effectively mimic the time course of H2 S release in vivo. However, it is not known whether GYY4137 affects atherosclerosis. EXPERIMENTAL APPROACH: RAW 264.7 cells and human blood monocyte-derived macrophages were incubated with oxidized low density lipoprotein (ox-LDL) with/without GYY4137. ApoE(-/-) mice were fed a high-fat diet for 4 weeks and administered GYY4137 for 30 days. Lipid and atherosclerotic lesions were measured by oil red O staining. Endothelium-dependent relaxation was assessed in response to acetylcholine. Superoxide production was detected by dihydroethidium staining. Expression of mRNA and protein were evaluated by quantitative real-time PCR and Western blot. KEY RESULTS: GYY4137 inhibited ox-LDL-induced foam cell formation and cholesterol esterification in cultured cells. GYY4137 decreased the expression of lectin-like ox-LDL receptor-1, iNOS, phosphorylated IκBα, NF-κB, ICAM-1, VCAM-1 and chemokines, including CXCL2, CXCR4, CXCL10 and CCL17, but increased the scavenger protein CD36, in ox-LDL-treated RAW 264.7 cells. In vivo, GYY4137 decreased aortic atherosclerotic plaque formation and partially restored aortic endothelium-dependent relaxation in apoE(-/-) mice. GYY4137 decreased ICAM-1, TNF-α and IL-6 mRNA expression as well as superoxide (O2 (-) ) generation in aorta. In addition, GYY4137 increased aortic eNOS phosphorylation and expression of PI3K, enhanced Akt Ser(473) phosphorylation and down-regulated the expression of LOX-1. CONCLUSION AND IMPLICATIONS: GYY4137 inhibits lipid accumulation induced by ox-LDL in RAW 264.7 cells. In vivo, GYY4137 decreased vascular inflammation and oxidative stress, improved endothelial function and reduced atherosclerotic plaque formation in apoE(-/-) mice.

Losartan attenuates human monocyte-derived dendritic cell immune maturation via downregulation of lectin-like oxidized low-density lipoprotein receptor-1.

The angiotensin II receptor-1 blockers have generally been shown to have antiatherogenic effects, and dendritic cells (DCs) are the most efficient antigen presenting cells that play an active role in the development of atherosclerosis through inflammatory-immune responses. Here, we tested the hypothesis that the antiatherogenic effect of losartan, the first angiotensin II receptor-1 blockers, might partly be mediated by attenuating DCs maturation. In this study, we showed that oxidized low-density lipoprotein (oxLDL) and angiotensin II (Ang II) could induce the maturation of human monocyte-derived DCs, stimulate CD83, HLA-DR expressions and IL-12, interferon-gamma secretions and increase the capacity of DCs to stimulate T-cell proliferation, which were suppressed by losartan. OxLDL could promote the autocrine secretion of Ang II by DCs and upregulate the expressions of 3 scavenger receptors SR-A, CD36, and LOX-1. Losartan reduced oxLDL-induced LOX-1 expression but not SR-A and CD36 expressions. Ang II could only upregulate the LOX-1 expression, which was reduced by losartan. OxLDL- and Ang II-induced upregulation of CD83 and secretion of IL-12 were all attenuated by LOX-1 neutralizing antibody. In conclusion, losartan could attenuate the oxLDL- and Ang II-induced immune maturation of human monocyte-derived DCs partly through downregulation of the LOX-1 expression.

Calcium channel blocker (diltiazem) inhibits apoptosis of vascular smooth muscle cell exposed to high glucose concentration through lectin-like oxidized low density lipoprotein receptor-1 (LOX-1) pathway.

AIM: to examine the role of diltiazem in the prevention of VSMC apoptosis exposed to high glucose through inhibition of LOX-1 expression. METHODS: we performed experimental study on the primary culture of VSMCs. Expression LOX-1, and Caspase-3 activity (a key regulatory protease at which many signaling pathways merge for the execution of apoptosis) were measured by Elisa. Data were expressed as mean ± SEM. The statistical significance was assessed by one-way analysis of variance (ANOVA) followed by post hock analysis by Turckey test, p<0.05 was considered statistically significant. RESULTS: chronic exposed VSMC to high glucose concentration (25 mM), increase cytosolic Ca++ concentration (3127 ± 413.89 v.s. 2011.81 ± 410.93 unit/cell, p<0.01), expression of LOX-1 ((506.80 ± 10.47 v.s. 458.40 ± 36.49 ng/ml, p<0.05), and caspase-3 activity (129.98 ± 5.97 v.s. 114.73 ± 10.84%, p<0.05) respectively, compare exposed to 5mM glucose concentration. LOX-1 was related to caspase-3 activity, pre-treated with inhibitor LOX-1 activity, k-carragenan before being exposed to glucose 25 mM, prevents the increasing of caspase-3 activity (96.41 ± 5.11 v.s. 129.98 ± 5.98 %, p<0.01). Pre incubation with 10µM of diltiazem before being exposed to 25 mM glucose concentration significantly inhibits the elevation of cytosolic Ca++ concentration (2149.61 ± 339.49 v.s. 3127 ± 413.89 unit/cell, p<0.01), LOX-1 expression (468,60 ± 14.44 v.s. 506.80 ± 10.47 ng/ml, p < 0.05), and caspase-3 activity (82.50 ± 9.90 v.s. 129.98 ± 5.97%, p<0.01). CONCLUSION: overall, these results demonstrate that high glucose induces VSMCs apoptosis through caspase-3 pathway. This effect appears to be inhibited by diltiazem through decreasing LOX-1 expression and activity.

Association of scavenger receptors in adipose tissue with insulin resistance in nondiabetic humans.

OBJECTIVE: Scavenger receptors play crucial roles in the pathogenesis of atherosclerosis, but their role in insulin resistance has not been explored. We hypothesized that scavenger receptors are present in human adipose tissue resident macrophages, and their gene expression is regulated by adiponectin and thaizolidinediones. METHODS AND RESULTS: The gene expression of scavenger receptors including scavenger receptor-A (SRA), CD36, and lectin-like oxidized LDL receptor-1 (LOX-1) were studied in subcutaneous adipose tissue of nondiabetic subjects and in vitro. Adipose tissue SRA expression was independently associated with insulin resistance. Pioglitazone downregulated SRA gene expression in adipose tissue of subjects with impaired glucose tolerance and decreased LOX-1 mRNA in vitro. Macrophage LOX-1 expression was decreased when macrophages were cocultured with adipocytes or when exposed to adipocyte conditioned medium. Adding adiponectin neutralizing antibody resulted in a 2-fold increase in LOX-1 gene expression demonstrating that adiponectin regulates LOX-1 expression. CONCLUSIONS: Adipose tissue scavenger receptors are strongly associated with insulin resistance. Pioglitazone and adiponectin regulate gene expression of SRA and LOX-1, and this may have clinical implications in arresting the untoward sequalae of insulin resistance and diabetes, including accelerated atherosclerosis.

The protective effects of taurine against early renal injury in STZ-induced diabetic rats, correlated with inhibition of renal LOX-1-mediated ICAM-1 expression.

Oxidative stress is a key cause in the development of diabetic nephropathy (DN). As a main receptor of oxidized low-density lipoprotein (oxLDL), LOX-1 plays an important role in the induction of leukocyte adhesion molecules, such as intercellular cell adhesion molecule-1 (ICAM-1). Taurine (TAU), a potent endogenous antioxidant, showed renoprotective effects in several model animals. This study was designed to determine the renoprotective effect and possible mechanism involved LOX-1 and ICAM-1 expression of taurine in early DN. Six-week-old male Wistar rats were divided into three groups: normal control (NC), diabetes mellitus (DM), and taurine-treated DM (DM+TAU). Diabetes was induced by streptozotocin (STZ, 60 mg/kg, i.p.). After the onset of diabetes, drinking water containing 1% taurine was given to rats in the DM+TAU group. After six weeks of treatment, blood glucose (BG), serum levels of creatinine (sCr) and BUN, and LOX-1 and ICAM-1 expression (protein and gene) in kidney cortices were estimated. Meanwhile, renal malondialdehyde (MDA) levels and glutathione peroxidase (GSH-Px) activities were examined as parameters of oxidative stress in diabetic rats. For DM+TAU rats, when compared with DM rats, the levels of serum BUN, sCr, and renal MDA were reduced, and the activities of renal GSH-Px were increased, but the BG levels were not influenced. Simultaneously, taurine attenuated histopathologic evidence of renal damages and reduced the overexpression of LOX-1 and ICAM-1 in kidney cortices of diabetic rats. In conclusion, taurine showed protective effects against early renal injury in diabetic rats. These renoprotective effects may be partly caused by suppression of oxLDL/LOX-1 system and subsequently ICAM-1 overexpression on renal cortex via its antioxidative property.

The protective effect of bergamot oil extract on lecitine-like oxyLDL receptor-1 expression in balloon injury-related neointima formation.

Lectin-like oxyLDL receptor-1 (LOX-1) has recently been suggested to be involved in smooth muscle cell (SMC) proliferation and neointima formation in injured blood vessels. This study evaluates the effect of the nonvolatile fraction (NVF), the antioxidant component of bergamot essential oil (BEO), on LOX-1 expression and free radical generation in a model of rat angioplasty. Common carotid arteries injured by balloon angioplasty were removed after 14 days for histopathological, biochemical, and immunohistochemical studies. Balloon injury led to a significant restenosis with SMC proliferation and neointima formation, accompanied by increased expression of LOX-1 receptor, malondialdehyde and superoxide formation, and nitrotyrosine staining. Pretreatment of rats with BEO-NVF reduced the neointima proliferation together with free radical formation and LOX-1 expression in a dose-dependent manner. These results suggest that natural antioxidants may be relevant in the treatment of vascular disorders in which proliferation of SMCs and oxyLDL-related endothelial cell dysfunction are involved.

Calcium [corrected] channel blockers reduce angiotensin II-induced superoxide generation and inhibit lectin-like oxidized low-density lipoprotein receptor-1 expression in endothelial cells.

Calcium channel blockers have been shown to limit the progression of atherosclerosis and decrease the incidence of cardiovascular events. To investigate vasoprotective effects beyond the blood pressure-lowering effects of these agents, amlodipine (10(-6) mol/) and manidipine (10(-6) mol/l) were used to pretreat angiotensin (Ang) II-stimulated rat cultured aortic endothelial cells. A 3-h period of Ang II treatment enhanced superoxide generation and the expression of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase protein, as detected by dihydroethidium staining and Western blotting, respectively. Pretreatment with amlodipine or manidipine attenuated the increased production of superoxide and the overexpression of NADPH oxidase. The enhanced expression of heme oxygenase-1 (HO-1) mRNA induced by Ang II was further increased by amlodipine, whereas pretreatment with manidipine led to a reduction in the expression of HO-1. Furthermore, Ang II increased vascular cell adhesion molecule-1 (VCAM-1), intracellular adhesion molecule-1 (ICAM-1), and monocyte chemoattractant protein-1 (MCP-1) mRNA levels, as determined by reverse transcription (RT)-polymerase chain reaction (PCR). Pretreatment with either amlodipine or manidipine decreased the overexpression of VCAM-1, ICAM-1, and MCP-1. We also demonstrated that amlodipine or manidipine prevented the Ang II-induced increase in lectin-like oxidized low-density lipoprotein receptor1 (LOX-1) content, thereby restoring control levels. These observations showed that amlodipine and manidipine reduced superoxide generation by the inhibition of the overexpression of NADPH oxidase in Ang II-stimulated endothelial cells. Such antioxidant effects of these agents might in turn have led to a decrease in the expression of VCAM-1, ICAM-1 and MCP-1. The salutary effects of calcium channel blockers in atherogenesis include the inhibition of the expression of LOX-1.

[Lox-1--an actor in cardiovascular disease?]. / LOX-1--en aktør ved hjerte- og karsykdommer?

BACKGROUND: Among risk factors such as smoking, hypertension and LDL cholesterol, oxidized LDL (ox-LDL) has emerged as a new and interesting factor. Scavenger receptors are a group of cell-surface receptors located on various cell types within the vessel wall with special affinity for ox-LDL. Of all the scavenger receptors involved in coronary heart disease, the lectin-like oxidized low-density lipoprotein receptor (LOX-1) is probably the most important. MATERIAL AND METHODS: This article provides a general overview of the scavenger receptors, with special emphasis on LOX-1 and its role in hypertension, heart failure, atherosclerotic heart disease and diabetes mellitus, based on the literature and our own published data. RESULTS AND INTERPRETATION: LOX-1 is located in various cell types within atherosclerotic plaque, in humans as well in animals, and it accumulates during the progression of the plaque. The receptor is highly expressed in hypertension, hyperhomocysteinaemia and diabetes mellitus. Data indicate that there is a complex interaction between LOX-1 and a number of different processes, such as inflammation, lipid accumulation and oxidative stress. In addition, LOX-1 seems to have therapeutic potential, and a prospective treatment aiming to reduce the level of LOX-1 may be important in the development of atherosclerotic disease, such as coronary heart disease.

Cross-talk between dyslipidemia and renin-angiotensin system and the role of LOX-1 and MAPK in atherogenesis studies with the combined use of rosuvastatin and candesartan.

There is increasing evidence of cross-talk between dyslipidemia and renin-angiotensin system (RAS) in atherogenesis. Both dyslipidemia and RAS activation enhance the expression of a newly described receptor for oxidized-low density lipoprotein (ox-LDL), lectin-like ox-LDL receptor-1 (LOX-1). We postulated that the blockade of dyslipidemia with rosuvastatin, a 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor and RAS with candesartan, an angiotensin II type 1 receptor blocker, would have a synergistic inhibitory effect on LOX-1 expression and atherogenesis. Apo-E knockout mice were fed a high-cholesterol diet (1% cholesterol, HC-diet) alone, or HC-diet with rosuvastatin (1mg/(kgd)), candesartan (1mg/(kgd)) or with both. Twelve weeks later the extent of atherosclerosis was determined by Sudan IV staining. Apo-E knockout mice on HC-diet had extensive atherosclerosis. Both rosuvastatin and candesartan decreased the extent of atherosclerosis (by 23 and 26%, respectively), despite the HC-diet; however, the combination of rosuvastatin and candesartan reduced atherosclerosis further (by 67%). Rosuvastatin decreased plasma levels of total cholesterol by over 50%, whereas candesartan had no effect. LOX-1 protein expression was found to be markedly up-regulated in HC-diet-fed apo-E knockout mice. While rosuvastatin and candesartan each had a small inhibitory effect on the expression of LOX-1 in the atherosclerotic tissues, the combination totally blocked the up-regulation of LOX-1. P38 mitogen-activated protein kinase (MAPK) expression and phosphorylation were increased in apo-E knockout mice, attenuated by rosuvastatin or candesartan alone, and completely blocked by the combination of the two agents. P44/42 MAPK expression and phosphorylation were not affected by the HC-diet, rosuvastatin, candesartan, or their combination. This study demonstrates the potent effect of rosuvastatin and candesartan on atherogenesis, as well as on the expression of LOX-1 and on the activation of p38 MAPK, but not p44/42 MAPK.