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

Small Dense LDL Enhances THP-1 Macrophage Foam Cell Formation

Increased levels of small dense low-density lipoproteins (sd-LDL) have been reported more atherogenic compared to total low-density lipoprotein (LDL); however, no definitive experiments using macrophages have examined this concept in vitro. In this study, we isolated fractions of total LDL (density 1.019-1.063 g/ml) and sd-LDL (density 1.044-1.063 g/ml) from the plasma of subjects with modest hypertriglycidemia. Oxidizabilty as assessed by copper-induced generation (1.6 µmol/L CuSO(4),12 h) of thiobarbituric acid reactive substances (TBARS) was significantly greater (7-fold higher, p < 0.01) for sd-LDL (4.3 ± 1.1 nmol/mg) than for total LDL (0.6 ± 0.2 nmol/mg) at the same cholesterol concentrations. Moreover, oxidized sd-LDL induced more lipid staining in macrophages than oxidized total LDL. When non-oxidized sd-LDL were incubated with THP1 macrophages, there was much greater lipid accumulation as assessed by oil red O staining, and more than a 2-fold increase (p < 0.05) in intracellular triglyceride content as compared to non-oxidized total LDL. Furthermore, non-oxidized sd-LDL in contrast to non-oxidized total LDL enhanced macrophage lectin-like oxidized LDL receptor-1 (LOX-1) protein expression and significantly LOX-1 mRNA levels (+158%, p < 0.05), with no effect on scavenger receptor A or CD36 gene expression. These effects of non-oxidized sd-LDL on LOX-1 gene expression were suppressed when Toll-like receptor 4 was inactivated either by RNAi or antibody. Our data indicate for the first time that sd-LDL is much more effective in promoting macrophage triglyceride accumulation and LOX-1 gene expression than total LDL.

Vascular and Cardiac Impairments in Rats Inhaling Ozone and Diesel Exhaust Particles

BackgroundMechanisms of cardiovascular injuries from exposure to gas and particulate air pollutants are unknown.ObjectiveWe sought to determine whether episodic exposure of rats to ozone or diesel exhaust particles (DEP) causes differential cardiovascular impairments that are exacerbated by ozone plus DEP.Methods and resultsMale Wistar Kyoto rats (10–12 weeks of age) were exposed to air, ozone (0.4 ppm), DEP (2.1 mg/m3), or ozone (0.38 ppm) + DEP (2.2 mg/m3) for 5 hr/day, 1 day/week for 16 weeks, or to air, ozone (0.51 or 1.0 ppm), or DEP (1.9 mg/m3) for 5 hr/day for 2 days. At the end of each exposure period, we examined pulmonary and cardiovascular biomarkers of injury. In the 16-week study, we observed mild pulmonary pathology in the ozone, DEP, and ozone + DEP exposure groups, a slight decrease in circulating lymphocytes in the ozone and DEP groups, and decreased platelets in the DEP group. After 16 weeks of exposure, mRNA biomarkers of oxidative stress (hemeoxygenase-1), thrombosis (tissue factor, plasminogen activator inhibitor-1, tissue plasminogen activator, and von Willebrand factor), vasoconstriction (endothelin-1, endothelin receptors A and B, endothelial NO synthase) and proteolysis [matrix metalloprotease (MMP)-2, MMP-3, and tissue inhibitor of matrix metalloprotease-2] were increased by DEP and/or ozone in the aorta, but not in the heart. Aortic LOX-1 (lectin-like oxidized low-density lipoprotein receptor-1) mRNA and protein increased after ozone exposure, and LOX-1 protein increased after exposure to ozone + DEP. RAGE (receptor for advanced glycation end products) mRNA increased in the ozone + DEP group. Exposure to ozone or DEP depleted cardiac mitochondrial phospholipid fatty acids (DEP > ozone). The combined effect of ozone and DEP exposure was less pronounced than exposure to either pollutant alone. Exposure to ozone or DEP for 2 days (acute) caused mild changes in the aorta.ConclusionsIn animals exposed to ozone or DEP alone for 16 weeks, we observed elevated biomarkers of vascular impairments in the aorta, with the loss of phospholipid fatty acids in myocardial mitochondria. We conclude that there is a possible role of oxidized lipids and protein through LOX-1 and/or RAGE signaling.

Dihydrotestosterone Suppresses Foam Cell Formation and Attenuates Atherosclerosis Development

ABSTRACT The role of testosterone in atherosclerosis remains unclear because it is aromatized to estrogen. We investigated the effect of the nonaromatized natural androgen 5α-dihydrotestosterone (DHT) on the rabbit atherogenesis in relation to the proatherogenic molecule lectin-like oxidized-low-density lipoprotein receptor-1 (LOX-1) and its downstream molecules. Thirty-nine male New Zealand white rabbits were divided into four groups: 1) noncastrated group with normal chow diet (n = 6); 2) noncastrated group with high-cholesterol diet (HCD) (n = 10); 3) castrated group with HCD plus sc placebo pellet (n = 11); and 4) castrated group with HCD plus sc 150 mg DHT pellet (n = 12). Implantation of sc DHT or placebo pellet was performed at the time of castration. After castration or sham operation, the rabbits were fed the HCD for 8 wk, and plaque areas were assessed in the entire aorta. The HCD-induced increase in plaque area, which was most aggravated in the castration plus placebo group, was attenuated in the castration plus DHT group. Microscopic examination of the proximal descending aorta revealed that DHT significantly reduced HCD-induced foam cell formation, which was mostly composed of macrophages in the intima layer, compared with the placebo group. The decreased accumulation of foam cells with DHT treatment was accompanied by a marked reduction in the expression of LOX-1 mRNA in these cells. In cultured macrophages prepared from male wild-type mice that express the androgen receptor (AR), 1 × 10−8m and 1 × 10−9m DHT inhibited the formation of foam cells induced by oxidized low-density lipoprotein. Moreover, the expression of LOX-1 and inflammatory cytokines in the cultured macrophages was significantly suppressed by DHT. Such suppressive effects of DHT on foam cell formation and cytokine expression were not observed in cultured macrophages prepared from male AR-null mice, suggesting an involvement of AR in the mechanism. In conclusion, physiological levels of DHT attenuated the development of atherosclerosis in rabbits through the suppression of intimal foam cell formation of macrophage partly via the suppression of LOX-1 expression.

Dihydrotestosterone Suppresses Foam Cell Formation and Attenuates Atherosclerosis Development

The role of testosterone in atherosclerosis remains unclear because it is aromatized to estrogen. We investigated the effect of the nonaromatized natural androgen 5alpha-dihydrotestosterone (DHT) on the rabbit atherogenesis in relation to the proatherogenic molecule lectin-like oxidized-low-density lipoprotein receptor-1 (LOX-1) and its downstream molecules. Thirty-nine male New Zealand white rabbits were divided into four groups: 1) noncastrated group with normal chow diet (n = 6); 2) noncastrated group with high-cholesterol diet (HCD) (n = 10); 3) castrated group with HCD plus sc placebo pellet (n = 11); and 4) castrated group with HCD plus sc 150 mg DHT pellet (n = 12). Implantation of sc DHT or placebo pellet was performed at the time of castration. After castration or sham operation, the rabbits were fed the HCD for 8 wk, and plaque areas were assessed in the entire aorta. The HCD-induced increase in plaque area, which was most aggravated in the castration plus placebo group, was attenuated in the castration plus DHT group. Microscopic examination of the proximal descending aorta revealed that DHT significantly reduced HCD-induced foam cell formation, which was mostly composed of macrophages in the intima layer, compared with the placebo group. The decreased accumulation of foam cells with DHT treatment was accompanied by a marked reduction in the expression of LOX-1 mRNA in these cells. In cultured macrophages prepared from male wild-type mice that express the androgen receptor (AR), 1 x 10(-8) m and 1 x 10(-9) m DHT inhibited the formation of foam cells induced by oxidized low-density lipoprotein. Moreover, the expression of LOX-1 and inflammatory cytokines in the cultured macrophages was significantly suppressed by DHT. Such suppressive effects of DHT on foam cell formation and cytokine expression were not observed in cultured macrophages prepared from male AR-null mice, suggesting an involvement of AR in the mechanism. In conclusion, physiological levels of DHT attenuated the development of atherosclerosis in rabbits through the suppression of intimal foam cell formation of macrophage partly via the suppression of LOX-1 expression.

Left Ventricular Expression of Lectin-Like Oxidized Low-Density Lipoprotein Receptor-1 in Failing Rat Hearts

Lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) is a multiple ligand receptor induced by oxidative stress. However, its role in chronic heart failure remains unknown. The left ventricular (LV) expression of LOX-1 was examined in a salt-sensitive Dahl rat model of hypertension. Compared with controls, LOX-1 mRNA levels increased by 4.7-fold in the LV with hypertrophy, and by 32-fold in the LV with decreased systolic function. LV LOX-1 mRNA levels strongly correlated with the decrease in LV ejection fraction (EF) (r=-0.772), and with increases in the LV mRNA levels of B-type natriuretic peptide (r=0.814), monocyte chemoattractant protein-1 (r=0.943), transforming growth factor-beta(1) (r=0.936), and a macrophage marker, F4/80 (r=0.560). Serum levels of soluble LOX-1 were significantly elevated in patients with LV systolic dysfunction and hypertrophy, and significantly correlated with the decrease in EF (r=-0.495). Marked increase in the LV expression of LOX-1 in failing hearts may contribute to increased serum levels, and might be involved in chronic inflammation during the development of heart failure.

Effect of apocynin on NADPH oxidase-mediated oxidative stress-LOX-1-eNOS pathway in human endothelial cells exposed to high glucose

Hyperglycemia-induced generation of reactive oxygen species contributes to the development of proatherogenic changes and vasculopathy in diabetes. NADPH oxidase has been recognized as a major source of reactive oxygen species in the vasculature and the lectin-like oxLDL receptor-1 (LOX-1) appears to play a crucial role in the pathogenesis of diabetic endothelial dysfunction. The present study aimed to examine the relationships between the hyperglycemia-mediated NADPH oxidase-LOX-1 pathway activation and nitric oxide-mediated endothelial function. In addition, we investigated effect of the NADPH oxidase inhibitor, apocynin on these consequences. In human umbilical artery endothelial cells (HUAECs), the effect of high glucose on expressional regulations and functional consequences of NADPH oxidase subunits, LOX-1 and endothelial nitric oxide synthase (eNOS), in the absence and presence of apocynin (10 micromol/l) were evaluated. HUAECs were cultured under normal (5.5 mmol/l) or high glucose (30mmol/l) concentrations for 48 h in the absence and presence of apocynin. Our results showed that high glucose significantly enhanced the activity and the protein expression of NADPH oxidase subunits, Nox2 and p47(phox). High glucose markedly increased LOX-1 mRNA level and this was functionally reflected on the augmented uptake of Dil-labelled LDL (5 micromol/l, 3h) by HUAECs. Furthermore, high glucose attenuated eNOS protein and total nitrite levels. However, apocynin inhibited all these changes. Collectively, our study demonstrates that high glucose-induced oxidative stress via NADPH oxidase activation and this contributed to LOX-1 upregulation and eNOS downregulation in human endothelial cells. Apocynin efficiently reversed these consequences, suggesting its potential role as a vasculoprotective agent.

Association of Scavenger Receptors in Adipose Tissue With Insulin Resistance in Nondiabetic Humans

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. 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. 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.

LOX-1 augments oxLDL uptake by lysoPC-stimulated murine macrophages but is not required for oxLDL clearance from plasma

Oxidized LDL (oxLDL) promotes lipid accumulation as well as growth and survival signaling in macrophages. OxLDL uptake is mainly due to scavenger receptors SR-AI/II and CD36. However, other scavenger receptors such as lectin-like oxLDL receptor-1 (LOX-1) may also play a role. We used mice with targeted inactivation of the LOX-1 gene to define the role of this receptor in the uptake of oxLDL and in activation of survival pathways. There was no difference in uptake or degradation of 125I-oxLDL in unstimulated macrophages from wild-type and LOX-1 knockout mice and no difference in the rate of clearance of oxLDL from plasma in vivo. However, when expression of LOX-1 was induced with lysophosphatidylcholine, oxLDL uptake and degradation increased 2-fold in wild-type macrophages but did not change in LOX-1 knockout macrophages. Macrophages lacking LOX-1 showed the same stimulation of PKB phosphorylation and enhancement of survival by oxLDL as wild-type cells. These data show that LOX-1 does not alter the uptake of oxLDL in unstimulated macrophages and is not essential for the pro-survival effect of oxLDL in these cells. However, LOX-1 expression is highly inducible by lysophosphatidylcholine and pro-inflammatory cytokines, and if that occurred in macrophages within atheromas, LOX-1 could substantially increase oxLDL uptake by lesion macrophages.

A novel gene silencer, pyrrole–imidazole polyamide targeting human lectin-like oxidized low-density lipoprotein receptor-1 gene improves endothelial cell function

Pyrrole-imidazole polyamide can be combined in antiparallel side-by-side dimeric complexes along the minor groove of DNA in a sequence-specific manner. Pyrrole-imidazole polyamides are effective inhibitors of transcription factors as well as viral repressors and transactivators. Recently, lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) was reported to be a major factor contributing to the pathogenesis of coronary atherosclerosis. In this study, we designed a pyrrole-imidazole polyamide specific for the LOX-1 gene and evaluated its effect on LOX-1 gene transcription. A pyrrole-imidazole polyamide was designed to target the AP-1 binding site of the LOX-1 gene and synthesized by solid phase methods. This pyrrole-imidazole polyamide significantly inhibited LOX-1 promoter activity in HEK293 cells, determined by the luciferase assay. LOX-1 mRNA expression was also inhibited by the pyrrole-imidazole polyamide at a concentration of 10-9 mol/l in human umbilical vein endothelial cells (HUVEC), determined by the real-time PCR method. HUVEC were treated by pyrrole-imidazole polyamide targeting the LOX-1 gene, and apoptosis was assessed using Hoechst stain, terminal deoxy nucleotidyl transferase-mediated UTP end labeling method, and dye-uptake bioassay. Treatment of HUVEC for 72 h with LOX-1 targeted pyrrole-imidazole polyamide decreased apoptosis induced by angiotensin II and oxidized low-density lipoprotein (ox-LDL) loading in all assays. This novel therapeutic agent, pyrrole-imidazole polyamide, could specifically inhibit LOX-1 gene expression by reducing the promoter activity of the gene. Pyrrole-imidazole polyamide seems to be a powerful promising new agent that can be used to explore therapies based on inhibition of transcription. Molecular recognition of DNA by small molecules could provide insight into the development of new human medicines.

Correlation of oxidized low-density lipoprotein and lectin-like oxidized low-density lipoprotein receptor-1 with pre-eclampsia

To investigate the role of oxidized low-density lipoprotein (oxLDL) and lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) in pre-ecalmpsia. From June 2007 to January 2008, 73 women with pre-eclampsia who delivered in the Department of Obstetrics, Affiliated Hospital of Qingdao University Medical College, were recruited, including 35 women with mild pre-eclampsia (MPE group) and 38 women with severe pre-eclampsia (SPE group). And 45 healthy pregnant women were taken as control group. Enzyme-linked immunosorbent assay (ELISA) was used to measure the plasma concentrations of oxLDL in these women. Semiquantitative RT-PCR and Western blot were used to investigate the expression of LOX-1 mRNA and protein in placenta. The expression of caspase-3 mRNA in placenta was determined using Semiquantitative RT-PCR. (1) The plasma concentrations of oxLDL in MPE group (0.42 +/- 0.11) mg/L, SPE group (0.68 +/- 0.12) mg/L, were significantly higher compared with control group (0.35 +/- 0.14) mg/L (P < 0.01) and the concentrations of oxLDL in MPE group were significantly higher compared with SPE group (P < 0.01). (2) The expression of LOX-1 mRNA in placenta of MPE group (0.70 +/- 0.10) and SPE group (0.84 +/- 0.08) were significantly higher than that in control group (0.58 +/- 0.11) (P < 0.01) and the expression of LOX-1 mRNA in MPE group was significantly higher than that of SPE group (P < 0.01). (3) The expression of LOX-1 protein in placenta of MPE group (0.79 +/- 0.15) and SPE group (0.90 +/- 0.12) were significantly higher compared with control group (0.68 +/- 0.11) (P < 0.01), while the expression of LOX-1 protein of MPE group was significantly higher compared with SPE group (P < 0.01). (4) The expression of caspase-3 mRNA in placenta of MPE group (3.82 +/- 0.18) and SPE group (5.39 +/- 0.14) were significantly higher than that in control group (2.19 +/- 0.20) (P < 0.01), and the expression of caspase-3 mRNA in MPE group was significantly higher than that of SPE group (P < 0.01). (5) In pre-eclampsia groups, the levels of LOX-1 mRNA in placenta were positively correlated with the plasma concentrations of ox LDL (r = 0.93, P < 0.05), and caspase-3 mRNA expression were positively correlated with the expression of LOX-1 mRNA in placenta (r = 0.84, P < 0.05). Increased levels of oxLDL in plasma may induce excess expression of LOX-1 in placenta, which may be involved in the pathophysiological processes of pre-eclampsia.

Lectin-Like Oxidized LDL Receptor-1 (LOX-1) Expression in the Tubulointerstitial Area Likely Plays an Important Role in Human Diabetic Nephropathy

Diabetic nephropathy (DN) is a common cause of end-stage renal disease. However, the precise mechanism of DN, which involves the role of lipid, is still not fully understood. Lectin-like oxidized LDL receptor-1 (LOX-1) is a type II single-transmembrane protein that binds oxidized low density lipoprotein (Ox-LDL). This study examined the expression of LOX-1 mRNA in renal tissues from type 2 diabetes patients with DN using in situ hybridization (ISH). Renal tissues were obtained from 15 type 2 patients with DN and 5 minimal change nephrotic syndrome (MCNS), membranous nephropathy (MN) and normal human kidney (NHK). Glomerular and tubulointerstitial LOX-1 mRNA expression was evaluated by ISH. Results The cells positive for LOX-1 mRNA were identified in the glomeruli of DN, MCNS, MN and NHK, however, there was no positive signal in the tubulointerstitial area in MCNS and NHK. Some cells positive for LOX-1 mRNA were detectable in the tubulointerstitial area in DN and MN. In the results of glomerular staining, there was no significant difference between them. There was a significant correlation between the tubulointerstitial LOX-1 expression and the degree of the tubulointerstitial damage and urinary protein in DN. Increased expression of LOX-1 mRNA in the tubulointerstitial area may be closely linked to the development and progression of human DN, and in particular the tubulointerstitial damage.

Increased Lectin-Like Oxidized Low-Density Lipoprotein Receptor-1 Expression in the Maternal Vasculature of Women With Preeclampsia

Preeclampsia is a hypertensive disorder unique to pregnancy, in which the placenta may release factors into the maternal circulation resulting in systemic effects. Small dense low-density lipoprotein (LDL; which is susceptible for oxidation) is increased in preeclampsia. Lectin-like oxidized LDL receptor-1 (LOX-1) is a receptor for oxidized LDL. However, the expression levels and the regulation of LOX-1 in the maternal vasculature of women with preeclampsia are unknown. We hypothesized that there is an increased LOX-1 expression in arteries from women with preeclampsia. We further hypothesized that circulating factors in the plasma of women with preeclampsia would upregulate the LOX-1 expression in vascular endothelial cells and contribute to vascular endothelial oxidative stress. We observed abundant LOX-1 expression and the presence of oxidized LDL in arteries from women with preeclampsia, which was negligible in arteries from normotensive pregnant women. Human umbilical vein endothelial cells treated for 24 hours with 2% plasma from preeclamptic women increased LOX-1 expression and oxidized LDL uptake, as well as induced oxidative stress, as evidenced by increased NADPH oxidase activity and superoxide and peroxynitrite levels. These effects were significantly reduced by pretreatment with blocking antibody or small interfering RNA to LOX-1, as well as 5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrinato iron (III), chloride (FeTPPS), a peroxynitrite scavenger. Exogenous peroxynitrite and 3-morpholino sydnonimine (SIN-1) increased LOX-1 protein and mRNA expression. In conclusion, increased LOX-1 expression in the systemic vasculature of preeclampsia women provides a fundamental insight into the pathology of preeclampsia and likely contributes to the induction and maintenance of vascular oxidative stress.

Soluble lectin-like oxidized low density lipoprotein receptor-1 in type 2 diabetes mellitus

The lectin-like oxidized low density lipoprotein receptor-1 (LOX-1) can be proteolytically cleaved and released as soluble forms (sLOX-1). We have determined serums LOX-1 in type 2 diabetes and evaluated the effect of glucose and advanced glycation end products (AGEs) on sLOX-1 in vitro and in vivo. Endothelial cells were incubated with glucose or AGEs, and sLOX-1 in cell medium was measured. Serum sLOX-1 was measured in 219 diabetic patients and 187 controls by ELISA. The effect of lowering glucose and AGEs on sLOX-1 was determined in 38 poorly controlled diabetic patients after improvement in glycemic control. Incubation of endothelial cells with AGE-BSA led to a dose-dependent increase in sLOX-1, whereas the effect of glucose on sLOX-1 was less marked. Serum sLOX-1 was 9% higher in diabetic patients compared with controls (P<0.01). In the poorly controlled patients, serum sLOX-1 decreased by 12.5% after improvement in glycemic control (P<0.05). The magnitude of reduction in sLOX-1 correlated with the improvement in hemoglobin A1c and AGEs but not with the reduction in oxidized LDL. sLOX-1 level is increased in type 2 diabetes. Both glucose and AGEs are important determinants of LOX-1 expression, and lowering glucose and AGEs leads to a reduction in sLOX-1.

Novel Gene Silencer Pyrrole-Imidazole Polyamide Targeting Lectin-Like Oxidized Low-Density Lipoprotein Receptor-1 Attenuates Restenosis of the Artery After Injury

Lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) is a membrane protein that can support the binding, internalization, and proteolytic degradation of oxidized low-density lipoprotein. The LOX-1 expression increases in the neointima after balloon injury. To develop an efficient compound to inhibit LOX-1, we designed and synthesized a novel gene silencer pyrrole-imidazole (PI) polyamide targeting the rat LOX-1 gene promoter (PI polyamide to LOX-1) to the activator protein-1 binding site. We examined the effects of PI polyamide to LOX-1 on the LOX-1 promoter activity, the expression of LOX-1 mRNA and protein, and neointimal hyperplasia of the rat carotid artery after balloon injury. PI polyamide to LOX-1 significantly inhibited the rat LOX-1 promoter activity and decreased the expression of LOX-1 mRNA and protein. After balloon injury of the arteries, PI polyamide to LOX-1 was incubated for 10 minutes. Fluorescein isothiocyanate-labeled PI polyamide was distributed to almost all of the nuclei in the injured artery. PI polyamide to LOX-1 (100 microg) significantly inhibited the neointimal thickening by 58%. PI polyamide preserved the re-endothelialization in the injured artery. PI polyamide significantly inhibited the expression of LOX-1, monocyte chemoattractant protein-1, intercellular adhesion molecule-1, and matrix metalloproteinase-9 mRNAs in the injured artery. The synthetic PI polyamide to LOX-1 decreased the expression of LOX-1 and inhibited neointimal hyperplasia after arterial injury. This novel gene silencer PI polyamide to LOX-1 is, therefore, considered to be a feasible agent for the treatment of in-stent restenosis.

Relationship between the expressions of lectin-like oxidized low-density lipoprotein receptor-1 and apoptosis associated genes in placenta tissues and the pathogenesis of preeclampsia

To explore the expressions of lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) and apoptosis related genes caspase-3, Bax and bcl-2 in placenta, and their associations with the pathogenesis of preeclampsia. Thirty preeclampsia patients (preeclampsia group), hospitalized in Department of Obstetrics, Shengjing Hospital of China Medical University from June 2005 to December 2006, were selected as the subject group, and 40 normal pregnant women as control group. The expressions of LOX-1 and apoptosis related genes caspase-3, Bax and bcl-2 in different gestational weeks' placenta tissues were examined using immunohistochemistry, RT-PCR and western-blot. (1) Immunohistochemical detection in preeclampsia group: at 20 w+1 -24 w, 24 w+1 -28 w, 28 w+1 -32 w, 32 w+1 -36 w, 36 w+1 -40 w, respectively, the results of LOX-1 were 20.1 +/- 1.8, 25.6 +/- 1.3, 32.8 +/- 1.6, 34.3 +/- 1.5, 39.9 +/- 1.2; in the control group they respectively were 11.2 +/- 0.6, 18.5 +/- 1.6, 26.1 +/- 1.8, 28.3 +/- 1.6, 32.3 +/- 1.6; the difference was significant (P<0.05). In preeclampsia group, the results of caspase-3 were 12.3 +/- 0.9, 16.3 +/- 0.9, 24.4 +/- 0.8, 28.3 +/- 0.5, 36.3 +/- 1.1, and in the control group they respectively were 8.5 +/- 1.0, 12. 3 +/- 1.1, 17.4 +/- 1.2, 20.4 +/- 0.5, 24.2 +/- 1.3; the differences were significant (P<0.05). (2) RT-PCR and western-blot test: The expressions of LOX-1, caspase-3 and Bax mRNA and protein in placentas of preeclampsia group were stronger than those in normal pregnant women at different gestational weeks (P<0.05). However, the expression tendency of bcl-2 mRNA and proten was converse to the expression tendency of Bax. The expressions of LOX-1, caspase-3, and Bax are upregulated in placentas of preeclampsia patients, while bcl-2 is downregulated, both of which are associated with the pathogenesis of preeclampsia.

Expression and Localization of Lectin-like Oxidized Low-density Lipoprotein Receptor-1 (LOX-1) in Murine and Human Placentas

Lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) is one of the scavenger receptors that recognizes oxidized low-density lipoprotein as a major ligand. The placenta is a major source of prooxidant during pregnancy, and the level of placental oxidative stress increases rapidly at the end of the first trimester and tapers off later in gestation. In our study, we evaluated placental expression of LOX-1 during different gestational stages in mice and humans. We used immunohistochemistry and ISH to identify LOX-1-expressing cells in murine and human placentas. In both species, higher expression of LOX-1 mRNA during early to midgestational stages compared with late gestation-corresponding to the increased oxidative stress in early pregnancy-was shown by real-time RT-PCR. In murine placenta, we showed that LOX-1-expressing cells were fibroblast-like stromal cells in metrial glands and decidua basalis and that they were glycogen trophoblast cells in the junctional and labyrinth zones. In the human, LOX-1 expression was detected in villous cytotrophoblasts in both first trimester and term placentas. These localization patterns of LOX-1 in murine and human placentas suggest the possible involvement of LOX-1 in high oxidative stress conditions of pregnancy.

Zerumbone Suppresses Phorbol Ester-Induced Expression of Multiple Scavenger Receptor Genes in THP-1 Human Monocytic Cells

Unregulated uptake of oxidized low-density lipoproteins (ox-LDL) via macrophage scavenger receptors (SRs), such as lectin-like ox-LDL receptor-1 (LOX-1), is a key event in atherosclerosis. In the present study, we used differentiated Caco-2 cells as a model of the human small intestine to evaluate the suppressive effects of 16 traditional food items selected from Okinawa on 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced LOX-1 mRNA expression in THP-1 human monocyte-like cells. Three Zingiberaceae plants, Curcuma aromatica Salisbury, Curcuma longa L., and Zingiber zerumbet Smith, markedly suppressed that expression. When added to the apical sides of Caco-2 monolayers, zerumbone, a sesquiterpene from Z. zerumbet Smith, was found to permeate into the basolateral medium as an intact structure in a time-dependent manner. alpha-Humulene, a structural analog of zerumbone lacking the alpha,beta-unsaturated carbonyl group, did not suppress LOX-1 mRNA expression, indicating that its electrophilic moiety might play pivotal roles in its activities. Further, zerumbone attenuated the expression of SR-A, SR-PSOX, and CD36, but not that of CD68 or CLA-1, leading to a blockade of DiI-acLDL uptake, while it also inhibited the transcriptional activities of activator protein-1 and nuclear factor-kappaB. Together, our results indicate that zerumbone is a potential phytochemical for regulating atherosclerosis with reasonable action mechanisms.

Comparison of the antiatherosclerotic effects of dihydropyridine calcium channel blocker and HMG-CoA reductase inhibitor on hypercholesterolemic rabbits

The antiatherosclerotic effects of the dihydropyridine-type calcium channel blocker, benidipine hydrochloride (benidipine), and 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor, pravastatin sodium (pravastatin), were compared in hypercholesterolemic rabbits. Male, New Zealand white rabbits were fed a 0.5% cholesterol diet. Pravastatin (10 mg/kg) or benidipine (10 mg/kg) was orally administered once daily after start of feeding. After 8 weeks of cholesterol feeding, serum cholesterol was increased and endothelial function of thoracic aorta was impaired. Pravastatin prevented elevation of serum cholesterol and aortic tunica intima hyperplasia. Although benidipine had little effect on serum cholesterol, it significantly inhibited aortic tunica intima hyperplasia and impairment of endothelial function. Expression levels of the vascular cell adhesion molecule-1 (VCAM-1) and lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) mRNA in aorta of hypercholesterolemic rabbit were higher than those of normal rabbit. Benidipine significantly prevented upregulation of VCAM-1 mRNA expression and showed a tendency to inhibit elevation of LOX-1 mRNA expression. Pravastatin significantly prevented upregulation of both VCAM-1 and LOX-1 mRNA expression. The results demonstrate that pravastatin inhibits increase of serum cholesterol and vascular dysfunction in hypercholesterolemic rabbit. Benidipine is effective in preventing vascular hyperplasia without altering serum cholesterol levels and this may be due to inhibition of expression of VCAM-1.

Possible involvement of the oxidized low-density lipoprotein/lectin-like oxidized low-density lipoprotein receptor-1 system in pathogenesis and progression of human osteoarthritis

Using human cartilage samples and cultured chondrocytes, to assess the possible involvement of oxidized low-density lipoprotein (ox-LDL) and lectin-like ox-LDL receptor-1 (LOX-1) in pathogenesis and progression of osteoarthritis (OA). Thirty-two cartilage samples were obtained from 16 patients with knee OA, and 12 Control samples from six with femoral neck fracture. LOX-1 mRNA expressions in 12 OA and six Control samples were analyzed by reverse transcription-polymerase chain reaction (RT-PCR). Immunohistochemistry for ox-LDL and LOX-1 was performed in all samples. The histological OA grade was assessed with the modified Mankin score. The relative percentage of the ox-LDL and LOX-1 immunopositive chondrocytes was calculated in all samples. The effects of ox-LDL on cell viability in cultured human chondrocytes were investigated by the 3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide (MTT) assay and on proteoglycan synthesis by monitoring [35S] sulfate incorporation. There was a statistically significant difference between mean LOX-1/GAPDH (LOX-1/human glyceraldehyde-3-phosphate dehydrogenase) ratio of OA samples and that of Control samples (40.6%+/-10.3 and 11.9%+/-2.8, respectively, P<0.0001). The mean percentage of ox-LDL-positive cells was 23.0+/-15.7% in OA and 4.3+/-3.7% in Control cells (P=0.0002). The mean percentage of LOX-1-positive cells was 51.7+/-29.5% in OA and 10.0+/-8.1% in Control cells (P<0.0001). Both the ox-LDL immunoreactivity and the LOX-1 immunoreactivity were significantly correlated with the modified Mankin scores (R2=0.67 and 0.48, respectively; P<0.0001 for each). ox-LDL significantly reduced the human chondrocyte viability and proteoglycan synthesis, and pretreatment with anti-human LOX-1 monoclonal antibody reversed these effects. The ox-LDL/LOX-1 system may be involved in human OA.

Isorhamnetin prevent endothelial cell injuries from oxidized LDL via activation of p38MAPK

The present investigation was undertaken to determine the protective effects of isorhamnetin on endothelial cell line EA.hy926 injuries induced by oxidized low-density lipoprotein (ox-LDL) and to uncover some of the underlying mechanisms of these effects. Indices such as cell viability, lactate dehydrogenase (LDH), and nitric oxide (NO) release were measured to evaluate the protective effects of isorhamnetin. 2, 2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity, superoxide dismutase (SOD), superoxide and reactive oxygen species (ROS) generation were also detected to evaluate the antioxidant effects of isorhamnetin. Reverse Transcription-Polymerase Chain Reaction (RT-PCR) was used to confirm the expression of endothelial nitric oxide synthase (eNOS) mRNA and lectin-like ox-LDL receptor-1 mRNA. Western blotting was used to evaluate the protein expression of this receptor and eNOS, as well as p38-mitogen-activated protein kinase (p38MAPK) phosphorylation and NF-κB p65 translocation. As a result, cell viability decreased significantly ( P < 0.01) after 24 h treatment with ox-LDL, accompanied with apparent secretion disorders such as NO reduction and LDH increase. Pretreatment with isorhamnetin resulted in remarkable increase of cell viability ( P < 0.05) and modulation of secretion disorders mediated by ox-LDL in a concentration-dependent manner. Besides, ox-LDL led to upregulation of lectin-like ox-LDL receptor-1, phosphorylation of p38MAPK, translocation of NF-κB, and downregulation of the eNOS expression in endothelial cells. Isorhamnetin pretreatment inhibited the ox-LDL-induced downregulation of eNOS, upregulation of lectin-like ox-LDL receptor-1, phosphorylation of the p38MAPK and translocation of NF-κB. Moreover, isorhamnetin exhibited strong antioxidant activity, which was shown by its inhibition effects on ox-LDL-induced superoxide, ROS overproduction and significant SOD reduction. The data indicated the protective effects of isorhamnetin on endothelial cell line EA.hy926 from ox-LDL-induced cell injuries. These effects were obtained via inhibition of lectin-like ox-LDL receptor-1 upregulation, interference of ox-LDL-mediated intracellular signaling pathway (p38MAPK activation, NF-κB nuclear translocation, eNOS expression) and the antioxidant activity of isorhamnetin.