Liver-X-receptor-mediated expression of key genes in macrophages implicated in the control of cholesterol homeostasis and atherosclerosis

Atherosclerosis is a leading cause of morbidity and mortality in the western world. The deposition of lipoprotein cholesterol in the arterial wall is a critical early step in the pathogenesis of atherosclerosis. These atherogenic lipoproteins are then taken up by macrophages to transform into lipid-loaded foam cells. ATP-binding cassette transporter-Ai (ABCAi) is a membrane-bound protein that mediates efflux of cholesterol from cells, such as macrophages. Tangier disease, which arises due to mutations in the ABCAi gene, is associated with foam cells in a number of tissues and premature atherosclerosis. Proteins in HDL, such as apolipoprotein E (apoE), act as acceptors of cholesterol released from macrophages via the action of ABCAi, and take it to the liver where it can be excreted through the bile system. Increasing the expression of both ABCAi and apoE is therefore considered as a potential therapeutic approach for the prevention or treatment of atherosclerosis. Liver-X-receptors (LXRs) are members of a subfamily of nuclear receptors that are potent activators of ABCAi and apoE expression. Agonists of LXRs inhibit macrophage foam cell formation in vitro and atherosclerosis in mouse models of the disease. The signalling pathways through which LXR agonists induce the expression of ABCAi and apoE expression in macrophages are not known. The major aim of the studies presented in this thesis was to investigate such signalling pathways using the human macrophage THP-1 cell line as a model system with key findings confirmed in primary cultures. Both natural LXR agonists, such as combinations of 22-(R)-hydroxycholesterol (22-(R)-HC) and 9-cis-retinoic acid (9CRA), and synthetic ligands induced the expression of ABCAi and apoE. Such an induction of ABCAi and apoE expression was attenuated by treatment of the cells with pharmacological inhibitors of c-Jun-N-terminal kinase/stress- activated kinase (JNK/SAPK) and phosphoinositide-3-kinase (PI3K) pathways. The action of 22-(R)-HC and 9CRA was associated with activation of JNK/SAPK, its upstream component SEK1/MKK4 and its down-stream target c-Jun along with the key target for PI3K, protein kinase B (PKB). The role of these pathways was confirmed further by analysing the action of expression of dominant negative forms of key proteins on the activation of ABCAi promoter. In addition, small interfering RNA-mediated knockdown of JNK/SAPK was found to attenuate the induction of apoE expression. The action of these pathways culminated at the level of activator protein-1, a transcription factor that contains c-Jun, and whose binding sites are present in the regulatory regions of both the apoE and ABCAi genes. Finally, a potential cross-talk between the JNK/SAPK and PI3K pathways was identified in which protein kinase C played an important role. In conclusion, the studies presented in this thesis demonstrated, for the first time, an important role for a pathway involving PKB, PKC and JNK/SAPK cascade in the activation of ABCAi and apoE expression by LXR agonists, which has implications to macrophage foam cell formation and atherosclerosis.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Possible inhibition of hydroxy methyl glutaryl CoA reductase activity by nicotinic acid and ergosterol: as targeting for hypocholesterolemic action

Objective: Coronary artery diseases including atherosclerosis is considered as commonest problem worldwide. Ergosterols are the main components of vegetable oils and nuts. The objective of this study was to evaluate the potential hypoplipidemic and hypocholesterolemic effects of ergosterol in combination with niacin in rats fed high fat diet (HFD).Methods: Eighty male albino rats were included in this study divided into two main groups: Group I: Normal rats fed standard diet treated with either niacin (8.5 mg /kg b.w) or ergosterol (100 mg/Kg b.w) or both. Group II; rats fed HFD treated with either niacin (8.5 mg /kg b.w) or ergosterol (100 mg/Kg b.w) or both The feeding and treatment lasted for 8 weeks.Results: A significant elevation in the levels of total cholesterol, triacylglycerol, VLDL-c, LDL-c and atherogenic factor (p<0.001) in rats fed on HFD compared with normal control while HDL-c was significantly reduced in HFD rats compared with control group. Supplementation of diet with niacin or ergosterol or combined exerts improvement in the studied parameters by lowering triacylglycerol, total cholesterol, LDL-c and atherogenic factor and elevate HDL-c near to the value of control. Niacin combined with ergosterol were effective in the reduction of hydroxy methyl glutaryl-CoA reducatase (HMGCoA) compared with control (p<0.001). The combined effect was more potent than individual alone.Conclusion: Utilization of niacin and ergosterol may prevent the hypercholesterolemia and incidence of coronary heart diseases. These functional foods act as nutriceutical as dyslipidemics.Keywords: Nicotinic acid, cholesterol, ergostero

Renoprotective effect of red grape (Vitis vinifera L.) juice and dark raisins against hypercholesterolaemia-induced tubular renal affection in albino rats

Background: Red grape juice (RGJ) and dark raisins (DR) are rich in polyphenols and antioxidants. This study aimed to assess the efficacy of RGJ and DR in protec- ting the renal tubules against hypercholesteraemic-induced pathological changes.  Materials and methods: Forty albino rats divided into four groups (n = 10) were utilised in this study. They included the control, high cholesterol diet (HCD)-fed, HCD+RGJ-fed, and HCD+DR-fed groups. Body weight gain, food and water in- take, blood and insulin levels, lipid profile and kidney functions were assessed at the start of the experiment and after 12 weeks. The right kidney was dissected out and processed for both light and electron microscopic examination. Desmin and cytokeratin antibodies were utilised as histologic markers to assess the integrity of the proximal (PTs) and distal tubules (DTs) of the kidney.  Results: Administration of HCD resulted in hypercholesterolaemia in rats as evi- denced by the lipid profile. The PTs of hypercholesteraemic rats appeared dilated with hyaline casts and mitochondria in most of the tubular cells were affected. Immunohistochemical assessment revealed affection of both PTs and DTs. Both RGJ and DR, when administered along with the HCD for 12 weeks, improved the lipid profile, kidney functions as well as the histologic and cellular changes-induced by hypercholesterolaemia in the rats. The effect of raisins was superior to RGJ which might be due to its high contents of fibres and proteins.  Conclusions: This study highlighted the importance of supplementation of red grape and raisins in protection against the harmful effects induced by deposition of fat on the renal tubules’ structure and function.

PROTECTIVE ROLE OF CARNITINE SYNERGIZED WITH VITAMIN E AGAINST ISOPROTERENOL INDUCED CARDIAC INFARCTION IN RATS.

Background: The current study aimed to evaluate the role of carnitine in combination with vitamin E in protection against myocardial infarction induced by isoproterenol (ISO) in rats. Materials and Methods: Rats were grouped into 5 (each 10 rats): Group I. Control fed a standard diet. Group III: Rats were injected with vitamin E (100 IU/kg bw, i.p) daily. Group IV: Rats were given carnitine (20 mg/kg bw, i.p) daily .Group V: Rats were injected with both vitamin E (100 IU/kg bw, i.p) and carnitine (20 mg/kg bw, i.p) daily. On 7th, 8th, and 9th day, rats in groups (II-V) were injection i.p with ISO (55mg/kg b.w for successive three days). The treatment with carnitine and vitamin E were continuous for 21 days. Results: Canirine combined with vitamin E significantly increased coronary flow (CF) (

Efficiency of borage seeds oil against gamma irradiation-induced hepatotoxicity in male rats: possible antioxidant activity

Background: Borage (Borago officinal L.) is an annual herbaceous plant of great interest because its oil contains a high percentage of γ-linolenic acid (GLA). The present work was carried out to detect fatty acids composition of the oil extracted from borage seeds (BO) and its potential effectiveness against γ-irradiation- induced hepatotoxicity in male rats.Materials and Methods: GC-MS analysis of fatty acids methyl esters of BO was performed to identify fatty acids composition. Sixty rats were divided into five groups (12 rats each): Control, irradiated; rats were exposed to (6.5 Gy) of whole body γ-radiation, BO (50 mg/kg b.wt), irradiated BO post-treated and irradiated BO prepost-treated. Six rats from each group were sacrificed at two time intervals 7 and 15 days post-irradiation. Serum aspartate aminotransferase (AST), alanine aminotransferase (ALT), gamma glutamyl transferase (GGT) levels, lipids profile, as well as serum and hepatic reduced glutathione (GSH) and lipid peroxide (malondialdehyde) (MDA) levels were assessed. Histopathological examination of liver sections were also carried out.Results: The results showed that the high contents of BO extracted by cold pressing, were linoleic acid (34.23%) and GLA (24.79%). Also, oral administration of BO significantly improved serum levels of liver enzymes, lipids profile, as well as serum and hepatic GSH and MDA levels (p<0.001) as compared with irradiated rats after 15 days post irradiation. Moreover, it exerted marked amelioration against irradiation-induced histopathological changes in liver tissues. The improvement was more pronounced in irradiated BO prepost-treated group than irradiated BO post-treated.Conclusion: BO has a beneficial role in reducing hepatotoxicity and oxidative stress induced by radiation exposure. Therefore, BO may be used as a beneficial supplement for patients during radiotherapy treatment.Keywords: Borage seeds oil; γ-irradiation; Hepatotoxicity; Antioxidan

Serum proteins C and S levels as early biomarkers for kidney dysfunction in hemophilic patients

Background: Hemophilia is an inherited genetic disease characterized by the inability to coagulate blood after injury. The rationale of the current study was to evaluate serum proteins S and C and correlate to kidney function test in hemophilic patients for early diagnosis of abnormality in renal function.Subjects and Methods: This study was conducted on 80 males subjects divided into four groups. Group I: Control: Healthy subjects. Group II: Renal dysfunction (serum Creatinine >2mg/dl): Group III: Hemophilic patients. Group IV: Hemophilic patients with renal disorder. Serum urea, creatinine, sodium, potassium, protein C and protein S level were determined. Resuts: Protein C and S levels showed a significant decrease in hemophilic/and with renal dysfunction (P < 0.001,p<0.001). The level of plasma protein C and S levels were positively correlated with increased urinary albumin (P < 0.01). Urinary albumin was increased about 15 folds in hemophilic patients with renal dysfunction and nephrotic patients as compared with the control group. The cut-off value in 90% patients at the hemophilic patients with renal dysfunction 70%. Positive correlations were observed between urinary albumin (r=0.66), and creatinine (r=0.73). Conclusion: These biomarkers showed good predictive values with regard to ROC-AUC (0.41 and 0.75 for Proteins C and S, respectively).Keywords: Hemophilia, renal dysfunction, protein C, protein S

Signaling pathways regulated by Brassicaceae extract inhibit the formation of advanced glycated end products in rat brain

Background: The goal of this study was identification signaling molecules mediated the formation of AGEs in brain of rats injected with CdCl2 and the role of camel whey proteins and Brassicaceae extract on formation of AGEs in brain.Methods: Ninety male rats were randomly grouped into five groups; Normal control (GpI) and the other rats (groups II-V) were received a single dose of cadmium chloride i.p (5 μg/kg/b.w) for induction of neurodegeneration. Rats in groups III-V were treated daily with whey protein (1g/kg b.w) or Brassicaceae extract (1mg/kg b.w) or combined respectively for 12 weeks.Results: It was found that whey protein combined with Brassicaceae extract prevented the formation of AGEs and enhance the antioxidant activity compared with untreated group (p <0.001). Serum tumor necrosis factor (TNF-α) and interleukine (IL-6) levels were significantly decreased (p<0.01) in rats treated with whey protein and Brassicaceae extract formation compared with untreated. The combined treatment showed a better impact than individual ones (p<0.001). The level of cAMP but not cGMP were lowered in combined treatment than individual (p<0.01).Conclusion: it can be postulated that Whey protein + Brassicaceae extract formation could have potential benefits in the prevention of the onset and progression of neuropathy in patients.Keywords: Whey protein- Brassicaceae extract -neurodegeneration -rat

Possible inhibition of hydroxy methyl glutaryl CoA reductase activity by nicotinic acid and ergosterol: as targeting for hypocholesterolemic action.

Objective: Coronary artery diseases including atherosclerosis is considered as commonest problem worldwide. Ergosterols are the main components of vegetable oils and nuts. The objective of this study was to evaluate the potential hypoplipidemic and hypocholesterolemic effects of ergosterol in combination with niacin in rats fed high fat diet (HFD). Methods: Eighty male albino rats were included in this study divided into two main groups: Group I: Normal rats fed standard diet treated with either niacin (8.5 mg /kg b.w) or ergosterol (100 mg/kg b.w) or both. Group II; rats fed HFD treated with either niacin (8.5 mg /kg b.w) or ergosterol (100 mg/kg b.w) or both The feeding and treatment lasted for 8 weeks. Results: A significant elevation in the levels of total cholesterol, triacylglycerol, VLDL-c, LDL-c and atherogenic factor (p<0.001) in rats fed on HFD compared with normal control while HDL-c was significantly reduced in HFD rats compared with control group. Supplementation of diet with niacin or ergosterol or combined exerts improvement in the studied parameters by lowering triacylglycerol, total cholesterol, LDL-c and atherogenic factor and elevate HDL-c near to the value of control. Niacin combined with ergosterol were effective in the reduction of hydroxy methyl glutaryl-CoA reducatase (HMGCoA) compared with control (p<0.001). The combined effect was more potent than individual alone. Conclusion: Utilization of niacin and ergosterol may prevent the hypercholesterolemia and incidence of coronary heart diseases. These functional foods act as nutriceutical as dyslipidemics

Changes in erythrocyte ATPase activity under different pathological conditions

Background: Studies have shown that Na+-K+ ATPase activity was altered in disrupted red blood cell membranes and this enzyme is believed to be the site of active transport of Na+ and K+ in intact red blood cells. The enzyme is often referred to as Na+- K+ pump because it pumps Na+ out and K+ into the cell against gradients with the concomitant hydrolysis of intracellular ATP.Objective: The aim of this study was to find out the possibility of using Na+-K+-ATPase activity as a biomarker for the diagnosis of individuals with different physiological conditions.Materials and methods: The activity of Na+-K+ ATPase was determined in blood samples collected from different pathological and physiological conditions such as pregnancy, smoking, diabetes and renal dysfunction compared with healthy subjects matched for age and sex.Results: The Na+-K+ ATPase activity in pregnancy (0.094 ± 0.0051 μM Pi/min. mg protein), smoking (0.064 ± 0.0011 μM), diabetes (0.047 μM 0.002 μM) and kidney disease (0.069 ± 0.0014 μM) was higher compared to the measurements in healthy individuals (0.0081 ± 0.0031 μM).Conclusion: Na+- K+ATPase specific activity is a biomarker for the diagnosis of individuals with different physiological diseases.Keywords: Na+-K+ATPase, red blood cell, pregnancy, smoking, diabetes, kidney diseases

Analysis of SNPs of MC4R , GNB3 and FTO gene polymorphism in obese Saudi subjects

Background: The goal of this study was to analyze the association between the FTO rs17817449 (G>T), G protein beta3 subunit (GNB3) C825T and Melanocortin 4 receptor (MC4R) A822G single nucleotide  olymorphism (SNP) with obesity in Saudi subjects.Methods: The subjects were divided into 2 groups according to BMI: Obese (BMI> 29.9) and non- obese control (BMI<24.9). Genotyping of the target genes were determined by polymerase chain reaction (PCR) followed by restriction fragment length polymorphism analysis (RFLP).Results: We demonstrated the association of the FTO genotype TT with increased weight, BMI and leptin levels in both males and females. However, there was no association of genotype TT with fasting blood glucose, triglycerides and cholesterol levels. Regarding GNB3 rs5443 polymorphism, the likelihood of obesity was linked to the TT genotype which was also associated with increased leptin levels. On the other hand, the SNP of MC4R A822G did not exhibit any significant association with obesity among studied subjects and showed only the presence of homozygous AA genotype.Conclusion: The polymorphism of FTO gene rs17817449 and GNB3 gene rs5443 (C825T) may be a genetic determinant of obesity in Saudi population whereas impact of MC4R Asn274Ser change could not be detected.Keywords: Obesity, FTO gene-polymorphism