High-throughput Profiling Reveals Perturbation of Endoplasmic Reticulum Stress-Related Genes in Atherosclerosis Induced by High-Cholesterol Diet and the Protective Role of Vitamin E

Perinur Bozaykut, Ruchan Ekren, Osman Ugur Sezerman, Vadim N Gladyshev, Nesrin Kartal Ozer

Biofactors . 2020 May 8. doi: 10.1002/biof.1635.

Abstract

Formation of atherosclerotic plaques, called atherogenesis, is a complex process affected by genetic and environmental factors. It was proposed that endoplasmic reticulum (ER) stress is an important factor in the pathogenesis of atherosclerosis and that vitamin E affects atherosclerotic plaque formation via its antioxidant properties. Here, we investigated ER stress-related molecular mechanisms in high-cholesterol diet (HCD, 2%)-induced atherosclerosis model and the role of vitamin E supplementation in it, beyond its antioxidant properties. The consequences of HCD and vitamin E supplementation were examined by determining protein levels of ER stress markers in aortic tissues. As vitamin E supplementation acts on several unfolded protein response (UPR) factors, it decreased ER stress induced by HCD. To elucidate the associated pathways, gene expression profiling was performed, revealing differentially expressed genes enriched in ER stress-related pathways such as the proteasome and the apoptosis pathways. We further assessed the proteasomal activity impaired by HCD in the aorta and showed that vitamin E reversed it to that of control animals. Overall, the study characterized the effects of HCD and vitamin E on ER stress-related gene expression, revealing the role of proteolytic systems during atherogenesis.

Asbaghi O, Choghakhori R, Abbasnezhad A

Diabetes Metab Syndr. 2019 Jul - Aug;13(4):2525-2531. doi: 10.1016/j.dsx.2019.07.001. Epub 2019 Jul 9.

Abstract

BACKGROUND:

Results of the studies assessed the effect of omega-3 and vitamin E co-supplementation on lipid profile in patients with metabolic syndrome (MS) are contradictory. Therefore, we carried out a systematic review and meta-analysis of randomized controlled trials (RCTs), to assess the effect of omega-3 and vitamin E co-supplementation on total cholesterol (TC), triglycerides (TG), low-density lipoprotein (LDL) and high-density lipoprotein (HDL) in patients with MS.

METHODS:

A systematic search was performed to find the related articles, up to April, 2019. There was no language and time limitation. Meta-analyses were carried out using both the random and fixed effects model where appropriate, and I2 index was used to evaluate the heterogeneity.

RESULTS:

Search yielded 1236 publications. Five RCTs with 254 patients were eligible. Results of the meta-analysis indicated that omega-3 and vitamin E co-supplementation significantly reduced the serum concentrations of TG and LDL, whereas, it had no significant effect on the serum levels of TC and HDL in overweight patients with MS.

CONCLUSION:

Present systematic review and meta-analysis revealed that omega-3 and vitamin E co-supplementation have beneficial effects on lipid profile of overweight patients with MS. It significantly reduced the serum levels of TG and LDL in such patients.

Barzegar-Amini M, Ghazizadeh H, Seyedi SMR, Sadeghnia HR, Mohammadi A, Hassanzade-Daloee M, Barati E, Kharazmi-Khorassani S, Kharazmi-Khorassani J, Mohammadi-Bajgiran M, Tavallaie S, Ferns GA, Mouhebati M, Ebrahimi M, Tayefi M, Ghayour-Mobarhan M

Diabetes Metab Syndr. 2019 Jan - Feb;13(1):666-671. doi: 10.1016/j.dsx.2018.11.034. Epub 2018 Nov 13.

Abstract

OBJECTIVES:

Obesity and overweight are among the main causes of cardiovascular disease (CVD) mortality. Dyslipidemia, fatty liver index, is strongly related to CVD. Vitamin E as an antioxidant protects the hepatic cells against oxidative stress and prevents fatty liver disease. The aim of the current study is to evaluate the relationship between anthropometric parameters and fasted lipid profile with serum vitamin Elevels.

STUDY DESIGN:

A randomized trial was designed based on data from the Mashhad stroke and heart atherosclerotic disorders (MASHAD: 2010-2020).

METHODS:

363 CVD subjects (173 males and 190 females) was selected at random, among 9704 subjects in three regions of Mashhad, northeast of Iran to investigate the specific correlations among their serum vitamin E, lipid profile (TG, HDL-C, LDL-C and TC), and anthropometric features (height, weight, BMI, hip and waist circumferences.

RESULT:

The results indicated the significant relationships between vitamin E, and fasting serum lipid profile in subjects. Serum vitamin Ewas negatively correlated to TC, TG, and LDL-C and positively related to HDL-C. Also, statistically negative correlations were found between vitamin E and anthropometric parameters (weight, waist and hip circumference, middle Arm, and Systolic Blood Pressure). Moreover, vitamin E ratios such as vitamin E/(TC + TG) and vitamin E/TC values as standardized vitamin E, had significant negative correlation with BMI, the whole of anthropometric parameters, and dyslipidemia risk factors including TC, TG and LDL-C.

CONCLUSION:

We found that vitamin E profile was significantly lower in the dyslipidemia subjects. It is generally suggested that vitamin E monitoring might be used as a useful prognostic and therapeutic agent in dyslipidemia disorder.

Wong SK, Chin KY, Suhaimi FH, Ahmad F, Ima-Nirwana S

Int J Environ Res Public Health. 2018 Aug 24;15(9). pii: E1828. doi: 10.3390/ijerph15091828.

Abstract

The beneficial effects of vitamin E in improving components of MetS or bone loss have been established. This study aimed to investigate the potential of palm vitamin E (PVE) as a single agent, targeting MetS and bone loss concurrently, using a MetS animal model. Twelve-week-old male Wistar rats were divided into five groups. The baseline group was sacrificed upon arrival. The normal group was given standard rat chow. The remaining three groups were fed with high-carbohydrate high-fat (HCHF) diet and treated with tocopherol-stripped corn oil (vehicle), 60 mg/kg or 100 mg/kg PVE. At the end of the study, the rats were evaluated for MetS parameters and bone density. After euthanasia, blood and femurs were harvested for the evaluation of lipid profile, bone histomorphometric analysis, and remodeling markers. PVE improved blood pressure, glycemic status, and lipid profile; increased osteoblast surface, osteoid surface, bone volume, and trabecular thickness, as well as decreased eroded surface and single-labeled surface. Administration of PVE also significantly reduced leptin level in the HCHF rats. PVE is a potential agent in concurrently preventing MetS and protecting bone loss. This may be, in part, achieved by reducing the leptin level and modulating the bone remodeling activity in male rats.

Wong SK, Chin KY, Suhaimi FH, Ahmad F, Ima-Nirwana S

Bone. 2018 Jul 7. pii: S8756-3282(18)30260-6. doi: 10.1016/j.bone.2018.07.003. [Epub ahead of print]

Abstract

Metabolic syndrome (MetS) is associated with osteoporosis due to the underlying inflammatory and hormonal changes. Annatto tocotrienolhas been shown to improve medical complications associated with MetS or bone loss in animal studies. This study aimed to investigate the effects of annatto tocotrienol as a single treatment for MetS and osteoporosis in high-carbohydrate high-fat (HCHF) diet-induced MetS animals. Three-month-old male Wistar rats were randomly divided into five groups. The baseline group was euthanized at the onset of the study. The normal group received standard rat chow and tap water. The remaining groups received HCHF diet and treated with three different regimens orally daily: (a) tocopherol-stripped corn oil (the vehicle of tocotrienol), (b) 60 mg/kg annatto tocotrienol, and (c) 100 mg/kg annatto tocotrienol. At the end of the study, measurements of MetS parameters, body compositions, and bone mineral density were performed in animals before sacrifice. Upon euthanasia, blood and femur of the rats were harvested for the evaluations of bone microstructure, biomechanical strength, remodelling activities, hormonal changes, and inflammatory response. Treatment with annatto tocotrienol improved all MetS parameters (except abdominal obesity), trabecular bone microstructure, bone strength, increased osteoclast number, normalized hormonal changes and inflammatory response in the HCHF animals. In conclusion, annatto tocotrienol is a potential agent for managing MetS and osteoporosis concurrently. The beneficial effects of annatto tocotrienol may be attributed to its ability to prevent the hormonal changes and pro-inflammatory state in animals with MetS.

Wan Hasan WN, Chin KY, Jolly JJ, Abd Ghafar N, Soelaiman IN.

Endocr Metab Immune Disord Drug Targets. 2018 Apr 23. doi: 10.2174/1871530318666180423122409. [Epub ahead of print]

Abstract

BACKGROUND:

Osteoporosis is a silent skeletal disease characterized by low bone mass and destruction of skeletal microarchitecture, leading to an increased fracture risk. This occurs due to an imbalance in bone remodelling, whereby the rate of bone resorption is greater than bone formation. Mevalonate pathway, previously known to involve in cholesterol synthesis, is an important regulatory pathway for bone remodelling.

OBJECTIVE:

This review aimed to provide an overview of the relationship between mevalonate pathway and bone metabolism, as well as agents which act through this pathway to achieve their therapeutic potential.

DISCUSSION:

Mevalonate pathway produces farnesyl pyrophosphate and geranylgeranyl pyrophosphate essential in protein prenylation. An increase in protein prenylation favours bone resorption over bone formation. Non-nitrogen containing bisphosphonates inhibit farnesyl diphosphate synthase which produces farnesyl pyrophosphate. They are used as the first line therapy for osteoporosis. Statins, a well-known class of cholesterol-lowering agents, inhibit 3-hydroxy-3-methyl-glutaryl-coenzyme A (HMG-CoA) reductase, the rate-determining enzyme in the mevalonate pathway. It was shown to increase bone mineral density and prevent fracture in humans. Tocotrienol is a group of vitamin E commonly found in palm oil, rice bran and annatto bean. It causes degradation of HMG-CoA reductase. Many studies demonstrated that tocotrienol prevented bone loss in animal studies but its efficacy has not been tested in humans.

CONCLUSION:

mevalonate pathway can be exploited to develop effective antiosteoporosis agents.

KEYWORDS:

bone; bone metabolism; mevalonate pathway; tocotrienol; vitamin E.

Su M, Wang D, Chang W, Liu L, Cui M, Xu T

Assay Drug Dev Technol. 2018 Feb 22. doi: 10.1089/adt.2017.831. [Epub ahead of print]

Abstract

Atherosclerosis is a major cause for cardiovascular diseases. High-density lipoprotein (HDL) may reduce atherosclerosis through several different mechanisms. HDL is composed of lipids, cholesterol, cholesteryl esters, triglycerides, and phospholipids, mainly phosphatidylcholine plus specialized proteins called apolipoproteins (apos). In this study, we prepared vitamin E containing HDL (V_E-HDL) that contains egg phosphatidylcholine, cholesterol, vitamin E, and two kinds of recombinant human apolipoproteins (rhapo)-rhapoA-I and rhapoE in vitro by the facilitation of cholate. After that, we studied the effects of V_E-HDL on foam cell formation, cellular cholesterol efflux, oxidative low-density lipoprotein (oxLDL)-stimulated oxidative stress, and apoptosis of macrophages to evaluate the protective efficacy of V_E-HDL on macrophages. As the results showed, we prepared a new type of reconstituent HDL with apolipoproteins and vitamin E for the first time. V_E-HDL has protective efficacy on macrophages. It has the prospect of becoming a therapeutic agent on atherosclerosis in the future.

Kanchi MM, Shanmugam MK, Rane G, Sethi G, Kumar AP

Drug Discov Today. 2017 Aug 5. pii: S1359-6446(17)30137-X. doi: 10.1016/j.drudis.2017.08.001. [Epub ahead of print]

Abstract

Vitamin E family members: tocotrienols and tocopherols are widely known for their health benefits. Decades of research on tocotrienols have shown they have diverse biological activities such as antioxidant, anti-inflammatory, anticancer, neuroprotective and skin protection benefits, as well as improved cognition, bone health, longevity and reduction of cholesterol levels in plasma. Tocotrienols also modulate several intracellular molecular targets and, most importantly, have been shown to improve lipid profiles, reduce total cholesterol and reduce the volume of white matter lesions in human clinical trials. This review provides a comprehensive update on the little-known therapeutic potentials of tocotrienols, which tocopherols lack in a variety of inflammation-driven diseases.

Santolim LV, Amaral ME, Fachi JL, Mendes MF, Oliveira CA.

J Nutr Biochem. 2017 Jan;39:86-92. doi: 10.1016/j.jnutbio.2016.09.011. Epub 2016 Oct 11.

Abstract

Connexins (Cx) and cadherins are responsible for cell homeostasis. The Cx activity is directly related to cholesterol. The present work investigates whether vitamin E, with or without caloric restriction (CR), alters the mRNA expression of Cx26, Cx32, Cx43, N-cadherins (N-cads), E-cadherins (E-cads) and alpha-smooth muscle actin (α-SMA), and evaluates their relation to cholesterol metabolism in rat liver. Animals were divided into different groups: control with ad libitum diet (C), control+vitamin E (CV), aloric restriction with intake to 60% of group C (CR), and the intake of group CR+vitamin E (RV). There were increases of manganese superoxide dismutase (Mn-SOD) and glutathione S-transferase mu 1, indicating antioxidant effects of CR and vitamin E. An increase of nitric oxide in the CR group was in agreement with the Mn-SOD data. Supplementation with vitamin E, with or without CR, upregulated the expression of Cx26 mRNA and increased low-density lipoprotein cholesterol (LDL-c) in the CV group. Reductions of Cx32 and Cx43 were associated with lower LDL-c. Increases in Hmgcr and low-density lipoprotein receptor (LDLr) in the CV and RV groups could be explained by the effect of vitamin E. A reduction of LDLr in the CR group was due to the reduced dietary intake. Increases in cadherins in the CV, CR and RV groups were indicative of tissue maintenance, which was also supported by increases of α-SMA in groups CV and RV. Finally, vitamin E, with or without CR, increased Cx26, probably modulated by expression of the Hmgcr and LDLr genes. This suggests important relationship of Cxs and cholesterol metabolism genes.

Finno CJ, Bordbari MH, Valberg SJ, Lee D, Herron J, Hines K, Monsour T, Scott E, Bannasch DL, Mickelson J, Xu L.

Free Radic Biol Med. 2016 Dec;101:261-271. doi: 10.1016/j.freeradbiomed.2016.10.009. Epub 2016 Oct 15.

Abstract

Specific spontaneous heritable neurodegenerative diseases have been associated with lower serum and cerebrospinal fluid α-tocopherol (α-TOH) concentrations. Equine neuroaxonal dystrophy (eNAD) has similar histologic lesions to human ataxia with vitamin E deficiency caused by mutations in the α-TOH transfer protein gene (TTPA). Mutations in TTPA are not present with eNAD and the molecular basis remains unknown. Given the neuropathologic phenotypic similarity of the conditions, we assessed the molecular basis of eNAD by global transcriptome sequencing of the cervical spinal cord. Differential gene expression analysis identified 157 significantly (FDR<0.05) dysregulated transcripts within the spinal cord of eNAD-affected horses. Statistical enrichment analysis identified significant downregulation of the ionotropic and metabotropic group III glutamate receptor, synaptic vesicle trafficking and cholesterol biosynthesis pathways. Gene co-expression analysis identified one module of upregulated genes significantly associated with the eNAD phenotype that included the liver X receptor (LXR) targets CYP7A1, APOE, PLTP and ABCA1. Validation of CYP7A1 and APOE dysregulation was performed in an independent biologic group and CYP7A1 was found to be additionally upregulated in the medulla oblongata of eNAD horses. Evidence of LXR activation supports a role for modulation of oxysterol-dependent LXR transcription factor activity by tocopherols. We hypothesize that the protective role of α-TOH in eNAD may reside in its ability to prevent oxysterol accumulation and subsequent activation of the LXR in order to decrease lipid peroxidation associated neurodegeneration.