Coadministration of VDR and RXR agonists synergistically alleviates atherosclerosis through inhibition of oxidative stress: An in vivo and in vitro study

Hereditary hemochromatosis with homozygous C282Y HFE mutation: possible clinical model to assess effects of elevated reactive oxygen species on the development of cardiovascular disease

Hereditary hemochromatosis with the homozygous C282Y HFE mutation (HH-282H) is a genetic condition which causes iron overload (IO) and elevated reactive oxygen species (ROS) secondary to the IO. Interestingly, even after successful iron removal therapy, HH-282H subjects demonstrate chronically elevated ROS. Raised ROS are also associated with the development of multiple cardiovascular diseases and HH-282H subjects may be at risk to develop these complications. In this narrative review, we consider HH-282H subjects as a clinical model for assessing the contribution of elevated ROS to the development of cardiovascular diseases in subjects with fewer confounding clinical risk factors as compared to other disease conditions with high ROS. We identify HH-282H subjects as a potentially unique clinical model to assess the impact of chronically elevated ROS on the development of cardiovascular disease and to serve as a clinical model to detect effective interventions for anti-ROS therapy.

Bile Acid Network and Vascular Calcification-Associated Diseases: Unraveling the Intricate Connections and Therapeutic Potential

Bile acids play a crucial role in promoting intestinal nutrient absorption and biliary cholesterol excretion, thereby protecting the liver from cholesterol accumulation and bile acid toxicity. Additionally, bile acids can bind to specific nuclear and membrane receptors to regulate energy expenditure and specific functions of particular tissues. Vascular calcification refers to the pathological process of calcium-phosphate deposition in blood vessel walls, which serves as an independent predictor for cardiovascular adverse events. In addition to aging, this pathological change is associated with aging-related diseases such as atherosclerosis, hypertension, chronic kidney disease, diabetes mellitus, and osteoporosis. Emerging evidence suggests a close association between the bile acid network and these aforementioned vascular calcification-associated conditions. Several bile acids have been proven to participate in calcium-phosphate metabolism, affecting the transdifferentiation of vascular smooth muscle cells and thus influencing vascular calcification. Targeting the bile acid network shows potential for ameliorating these diseases and their concomitant vascular calcification by regulating pathways such as energy metabolism, inflammatory response, oxidative stress, and cell differentiation. Here, we present a summary of the metabolism and functions of the bile acid network and aim to provide insights into the current research on the profound connections between the bile acid network and these vascular calcification-associated diseases, as well as the therapeutic potential.

Mechanism of Simiao Decoction in the treatment of atherosclerosis based on network pharmacology prediction and molecular docking

To explore the molecular mechanism of Simiao Decoction (SMD) intervening atherosclerosis (AS). The main components and potential mechanisms of SMD remain unknown. This study aims to initially clarify the potential mechanism of SMD in the treatment of AS based on network pharmacology and molecular docking techniques. The principal components and corresponding protein targets of SMD were searched on Traditional Chinese Medicine Systems Pharmacology Database and Analysis Platform and the compound-target network was constructed by Cytoscape3.9.1. AS targets were searched on DrugBank, OMIM, and TTD databases. The intersection of compound target and disease target was obtained and the coincidence target was imported into STRING database to construct a protein-protein interaction network. We further performed Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis on the targets. The molecular docking method was used to verify the interaction between core components of SMD and targets. We created the active compounds-targets network and the active compounds-AS-targets network based on the network database containing Traditional Chinese Medicine Systems Pharmacology Database and Analysis Platform, DrugBank, OMIM, and TTD. We discovered that the therapy of AS with SMD involves 3 key substances-quercetin, kaempferol, and luteolin-as well as 5 crucial targets-ALB, AKT1, TNF, IL6, and TP53. The Gene Ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analysis revealed that the shared targets involved a number of signaling pathways, including the advanced glycosylation end product-receptor of AGE signaling pathway in diabetic complications, Hepatitis B, Lipid and atherosclerosis, Chemical Carcinogenesis-Receptor Activation, and Pathways in Cancer. The molecular docking demonstrated that the binding energies of quercetin, kaempferol, and luteolin with 5 important targets were favorable. This study reveals the active ingredients and potential molecular mechanism of SMD in the treatment of AS, and provides a reference for subsequent basic research.

Functional characterization of nutraceuticals using spectral clustering: Centrality of caveolae-mediated endocytosis for management of nitric oxide and vitamin D deficiencies and atherosclerosis

It is well recognized that redox imbalance, nitric oxide (NO), and vitamin D deficiencies increase risk of cardiovascular, metabolic, and infectious diseases. However, clinical studies assessing efficacy of NO and vitamin D supplementation have failed to produce unambiguous efficacy outcomes suggesting that the understanding of the pharmacologies involved is incomplete. This raises the need for using systems pharmacology tools to better understand cause-effect relationships at biological systems levels. We describe the use of spectral clustering methodology to analyze protein network interactions affected by a complex nutraceutical, Cardio Miracle (CM), that contains arginine, citrulline, vitamin D, and antioxidants. This examination revealed that interactions between protein networks affected by these substances modulate functions of a network of protein complexes regulating caveolae-mediated endocytosis (CME), TGF beta activity, vitamin D efficacy and host defense systems. Identification of this regulatory scheme and the working of embedded reciprocal feedback loops has significant implications for treatment of vitamin D deficiencies, atherosclerosis, metabolic and infectious diseases such as COVID-19.

1,25-dihydroxyvitamin D3 ameliorates high glucose-mediated proliferation, migration, and MCP-1 secretion of vascular smooth muscle cells by inhibiting MAPK phosphorylation

Objectives

To explore the impacts of 1,25-dihydroxyvitamin D₃ (1,25(OH)₂D₃) on the proliferation, migration, and monocyte chemoattractant protein-1 (MCP-1) secretion of vascular smooth muscle cells (VSMCs) in a high glucose environment and its possible mechanism.

Methods

We extracted VSMCs from the thoracic aorta of a male Sprague–Dawley rats before culturing them in a 25-mM glucose-containing medium in the presence or absence of 1,25(OH)₂D₃ (10⁻⁹ –10⁻⁷ M). Cell proliferation was determined by bromodeoxyuridine incorporation assays. Subsequently, cell migratory capacity was examined by performing a transwell assay. An enzyme-linked immunosorbent assay was conducted to assess MCP-1 levels. Protein levels of matrix metalloproteinase-9 (MMP-9), mitogen-activated protein kinases (MAPKs), cyclin D1, and phosphorylated MAPKs were determined by immunoblotting.

Results

1,25(OH)₂D₃ significantly suppressed the proliferation, migration, and MCP-1 secretion of VSMCs mediated by high glucose in a dose-dependent manner, diminished the enhanced protein expression of MMP-9 and cyclin D1, and attenuated MAPK phosphorylation. The p38 inhibitor SB203580 and ERK1/2 inhibitor PD98059 suppressed high glucose-mediated upregulation of MMP-9 and cyclin D1 protein expression and MCP-1 secretion, respectively.

Conclusions

1,25(OH)₂D₃ ameliorates high glucose-mediated proliferation, migration, and MCP-1 secretion of VSMCs by inhibiting MAPK phosphorylation, implying a potential therapeutic approach using 1,25(OH)₂D₃ for diabetic macrovascular complications.

MDM2-Mediated Ubiquitination of RXRβ Contributes to Mitochondrial Damage and Related Inflammation in Atherosclerosis

A novel function of retinoid X receptor beta (RXRβ) in endothelial cells has been reported by us during the formation of atherosclerosis. Here, we extended the study to explore the cellular mechanisms of RXRβ protein stability regulation. In this study, we discovered that murine double minute-2 (MDM2) acts as an E3 ubiquitin ligase to target RXRβ for degradation. The result showed that MDM2 directly interacted with and regulated RXRβ protein stability. MDM2 promoted RXRβ poly-ubiquitination and degradation by proteasomes. Moreover, mutated MDM2 RING domain (C464A) or treatment with an MDM2 inhibitor targeting the RING domain of MDM2 lost the ability of MDM2 to regulate RXRβ protein expression and ubiquitination. Furthermore, treatment with MDM2 inhibitor alleviated oxidized low-density lipoprotein-induced mitochondrial damage, activation of TLR9/NF-κB and NLRP3/caspase-1 pathway and production of pro-inflammatory cytokines in endothelial cells. However, all these beneficial effects were reduced by the transfection of RXRβ siRNA. Moreover, pharmacological inhibition of MDM2 attenuated the development of atherosclerosis and reversed mitochondrial damage and related inflammation in the atherosclerotic process in LDLr^-/- mice, along with the increased RXRβ protein expression in the aorta. Therefore, our study uncovers a previously unknown ubiquitination pathway and suggests MDM2-mediated RXRβ ubiquitination as a new therapeutic target in atherosclerosis.

Elevated NLRP3 Inflammasome Levels Correlate With Vitamin D in the Vitreous of Proliferative Diabetic Retinopathy

Purpose: This study aims to determine vitamin D concentrations in the vitreous and serum, as well as the expression levels of NLRP3 inflammasome pathway in the vitreous of patients with proliferative diabetic retinopathy (PDR). In addition, we investigated the possible correlation between NLRP3 inflammasome levels and vitamin D concentrations.

Methods: We obtained vitreous samples before vitrectomy from 55 PDR patients, 25 non-diabetic patients with idiopathic macular hole (IMH), and 10 non-proliferative diabetic retinopathy (NPDR) patients. We also collected serum samples from the same patients. Enzyme-linked immunosorbent assay (ELISA) was used to examine NLRP3 inflammasome pathway proteins, including NLRP3, caspase-1, IL-1β, and VEGF. In addition, vitamin D concentrations were analyzed in Roche Cobas 6000's module e601 platform using electrochemiluminescence immune assay.

Results: The levels of NLRP3 inflammasome pathway and VEGF increased dramatically in PDR vitreous. However, vitamin D concentrations in vitreous and serum followed the opposite trend. Meanwhile, vitreous and serum vitamin D concentrations were significantly negatively correlated with vitreous NLRP3 expression in PDR patients. Moreover, serum and vitreous vitamin D concentrations were positively correlated and demonstrated discriminatory ability in DR. The subgroup analysis of PDR group revealed that eyes with tractional retinal detachment (TRD) had higher NLRP3 inflammasome pathway and VEGF levels but lower vitamin D concentrations. Conversely, eyes that received preoperative pan-retinal photocoagulation (PRP) exhibited lower levels of NLRP3 inflammasome pathway, but vitamin D concentrations were irrelevant to laser treatment.

Conclusions: Our results demonstrate a strong correlation between increased NLRP3 inflammasome pathway and decreased vitamin D concentrations in the vitreous of PDR patients, which may be linked to PDR pathogenesis. In addition, vitamin D supplementation may play a key role in preventing, treating, and improving PDR prognosis due to its inhibitory impact on NLRP3 inflammasome pathway and VEGF.

Mechanisms Involved in the Relationship between Vitamin D and Insulin Resistance: Impact on Clinical Practice

Recent evidence has revealed anti-inflammatory properties of vitamin D as well as extra-skeletal activity. In this context, vitamin D seems to be involved in infections, autoimmune diseases, cardiometabolic diseases, and cancer development. In recent years, the relationship between vitamin D and insulin resistance has been a topic of growing interest. Low 25-hydroxyvitamin D (25(OH)D) levels appear to be associated with most of the insulin resistance disorders described to date. In fact, vitamin D deficiency may be one of the factors accelerating the development of insulin resistance. Vitamin D deficiency is a common problem in the population and may be associated with the pathogenesis of diseases related to insulin resistance, such as obesity, diabetes, metabolic syndrome (MS) and polycystic ovary syndrome (PCOS). An important question is the identification of 25(OH)D levels capable of generating an effect on insulin resistance, glucose metabolism and to decrease the risk of developing insulin resistance related disorders. The benefits of 25(OH)D supplementation/repletion on bone health are well known, and although there is a biological plausibility linking the status of vitamin D and insulin resistance supported by basic and clinical research findings, well-designed randomized clinical trials as well as basic research are necessary to know the molecular pathways involved in this association.

Paricalcitol inhibits oxidative stress-induced cell senescence of the bile duct epithelium dependent on modulating Sirt1 pathway in cholestatic mice

BACKGROUND

Clinical studies indicate that vitamin D receptor (VDR) expression is reduced in primary biliary cirrhosis patient livers. However, the mechanism by which activated VDR effect cholestatic liver injury remains unclear.

METHODS

Mice were injected intraperitoneally with the VDR agonist paricalcitol or a vehicle 3 days prior to bile duct ligation (BDL) and for 5 or 28 days after surgery. The analyses of liver morphology and necrotic areas were based on H&E staining. Serum biochemical indicators of liver damage were analyzed by commercial kits. The mechanisms of paricalcitol on cholestatic liver injury were determined by Western blot analysis.

RESULTS

Paricalcitol ameliorated the BDL-induced liver damage in mice. Paricalcitol increased the proliferation of BECs to promote the repair of the bile duct. Paricalcitol also reduced the BDL-induced oxidative stress level in the mice. Mechanistic analysis revealed that paricalcitol decreased the number of SA-β-gal-positive cells and downregulated the expression of p53, p21 and p16 proteins which was associated with reducing oxidative stress. Additionally, paricalcitol exerted the inhibitory effect of cell senescence was through reducing DNA damage and promoting DNA repair. Interesting, we found that paricalcitol prevented the downregulation of oxidative stress-induced Sirt1 expression in the BDL mice and t-BHP-induced BECs models. Moreover, paricalcitol suppressed cell senescence through a Sirt1-dependent pathway. These results were confirmed by antioxidant ALCAR and the Sirt1 inhibitor EX-527.

CONCLUSION

Paricalcitol alleviated cholestatic liver injury through promoting the repair of damaged bile ducts and reducing oxidative stress-induced cell senescence of the bile duct via modulating Sirt1 pathway.

Protective Effects of 1,25 Dihydroxyvitamin D3 against High-Glucose-Induced Damage in Human Umbilical Vein Endothelial Cells Involve Activation of Nrf2 Antioxidant Signaling

AIM

To explore the protective effects and related mech-anisms of 1,25 dihydroxyvitamin D3 (1,25(OH)2D3) on en-dothelial dysfunction under hyperglycemic conditions.

METHODS

Cultured human umbilical vein endothelial cells (HUVECs) were treated with normal glucose (glucose concentration of 5.5 mmol/L), high glucose (glucose concentration of 33 mmol/L), and high glucose plus 1,25(OH)2D3, respectively. Cell viability and apoptosis, intracellular reactive oxygen species (ROS) and nitric oxide (NO) contents, antioxidant enzyme activities, proinflammatory cytokine mRNA levels, and expression levels of proteins involved were measured.

RESULTS

High glucose decreased HUVEC viability, promoted ROS production and apoptosis, and reduced NO generation, which was associated with decreased activities of antioxidant enzymes and increased levels of proinflam-matory cytokines. 1,25(OH)2D3 treatment enhanced HUVEC viability, attenuated ROS generation and apoptosis, and -increased NO production, which was accompanied by -enhanced antioxidant enzyme activities and reduced -proinflammatory factors. Mechanically, 1,25(OH)2D3 promoted nuclear translocation of nuclear factor erythroid 2-related factor 2 (Nrf2) in a vitamin D receptor (VDR)-dependent manner, and Nrf2 siRNA abolished the antioxidative and -anti-inflammatory effects of 1,25(OH)2D3.

CONCLUSIONS

1,25(OH)2D3 attenuates high-glucose-induced endothelial oxidative injury through upregulation of the Nrf2 antioxidant pathway in a VDR-dependent manner.

Overexpression of retinoid X receptor beta provides protection against oxidized low-density lipoprotein-induced inflammation via regulating PGC1α-dependent mitochondrial homeostasis in endothelial cells

Retinoid X receptor beta (RXRβ) has been poorly studied in atherosclerosis. The aim of the present study is to explore the function of RXRβ in oxidized low density lipoprotein (ox-LDL)-induced inflammation in endothelial cells and the underlying mechanism. The protein expression of RXRβ in the aorta of atherosclerotic mice was detected. A lentivirus vector for RXRβ overexpression and RNA interference for RXRβ downregulation were constructed and transfected into human aortic endothelial cells (HAECs). The results showed that RXRβ protein expression was downregulated in aorta of high fat diet (HFD)-fed LDLr^-/- mice and ox-LDL-treated HAECs. The ox-LDL-induced production of pro-inflammatory cytokines and activations of TLR9/NF-κB and NLRP3/caspase-1 inflammasome pathway were significantly decreased by RXRβ overexpression but increased by RXRβ knockdown in HAECs. The ox‑LDL‑induced mitochondrial damage indicated as the increased generation of mitochondrial ROS, decreased mitochondrial membrane potential and increased mitochondrial DNA release was abolished by RXRβ overexpression but aggravated by RXRβ knockdown. Treatment with mito-TEMPO significantly reduced the increased production of pro-inflammatory cytokines and activations of TLR9/NF-κB and NLRP3/caspase-1 inflammasome induced by RXRβ knockdown in ox-LDL treated HAECs. Moreover, peroxisome proliferator-activated receptor-γ coactivator1α (PGC1α) protein expression was reduced in HFD-fed LDLr^-/- mice. RXRβ could interact with PGC1α in HAECs. Ox-LDL-induced reduction of PGC1α was significantly inhibited by RXRβ overexpression and aggravated by RXRβ downregulation. Our further study showed that transfection of PGC1α siRNA abrogated the alleviative effects of RXRβ overexpression on mitochondrial damage and inflammation in ox-LDL treated cells. The present study indicates that RXRβ exerted protective effects against the ox-LDL-induced inflammation may through regulating PGC1α-dependent mitochondrial homeostasis.

Integrated transcriptomic and proteomic analysis indicated that neurotoxicity of rats with chronic fluorosis may be in mechanism involved in the changed cholinergic pathway and oxidative stress

BACKGROUND

To reveal the underling molecular mechanism in brain damage induced by chronic fluorosis, the neurotoxicity and its correlation were investigated by transcriptomics and proteomics.

METHODS

Sprague-Dawley rats were treated with fluoride at different concentrations (0, 5, 50 and 100 ppm, prepared by NaF) for 3 months. Spatial learning and memory were evaluated by Morris water maze test; neuronal morphological change in the hippocampus was observed using Nissl staining; and the level of oxidative stress including reactive oxygen species (ROS), malondialdehyde (MDA) and superoxide dismutase (SOD) were detected by biological methods. The high-throughput transcriptome sequencing (RNA-Seq) and tandem mass tag (TMT) proteomic sequencing were performed to detect the expression of differentially expressed genes and proteins, respectively.

RESULTS

The results showed that compared with control group, rats exposed to high-dose fluoride exhibited declined abilities of learning and memory, decreased SOD activity and increased ROS and MDA levels, with lighter colored Nissl bodies. A total of 28 important differentially expressed genes (DEGs) were screened out by transcriptomics. Then, functional enrichment analyses showed that upregulated proteins enriched in cellular transport, while downregulated proteins enriched in synapse-related pathways. Thirteen corresponding DEGs and DAPs (cor-DEGs-DAPs) were identified by differential expressions selected with positively correlated genes/proteins, most of which were related to neurodegenerative changes and oxidative stress response.

CONCLUSION

These results provide new omics evidence that rats chronically exposed to high-dose fluoride can induce neurotoxicity in the brains through changes in the cholinergic pathway and oxidative stress.

Gene variants and haplotypes of Vitamin D biosynthesis, transport, and function in preeclampsia

Objective: To find whether the gene variants and haplotypes of cytochrome (CYP) 27B1 (1α-hydroxylase), group-specific component (GC) that is a vitamin D binding protein, vitamin D receptor (VDR), peroxisome proliferator-activated receptor γ (PPARγ) and retinoid-X receptor (RXR) affect the risk of preeclampsia. Methods: In a case-control study 100 women with preeclampsia and 100 healthy pregnant women were investigated for gene variants and haplotypes of vitamin D biosynthesis, transport, and function using the polymerase chain reaction-restriction fragment length polymorphism method. Results: The frequency of gene variants of PPARγ Pro12Ala and RXR -α (A/G, rs749759) were not significantly different comparing patients and controls. The TT genotype of CYP 27B1 (G > T) was associated with 2.2-fold (95% CI 1.04-4.7, p = 0.039) increased risk of early-onset preeclampsia. Also, the TT genotype of GC rs7041 (T > G) increased the risk of preeclampsia [OR = 2.13 (95% CI 1.09-4.17, p = 0.027)]. The VDR ApaI GT genotype elevated susceptibility to preeclampsia (OR = 2.55, p = 0.04). Further, the presence of VDR ApaI GT+TT genotype was associated with higher levels of body mass index, and systolic blood pressure, and lower level of 25 (OH)-D3. In the presence of haplotype CYP T, VDR T, and RXR A (TTA) compared to haplotype GTG the risk of preeclampsia was 6.71-fold (p = 0.044). Conclusions: The present study indicated an association between the CYP 27B1, GC, and VDR ApaI variants with the risk of preeclampsia. Also, the variants of the latter polymorphism influenced BMI, blood pressure, and vitamin D levels.

Retinoid X receptor agonists attenuates cardiomyopathy in streptozotocin-induced type 1 diabetes through LKB1-dependent anti-fibrosis effects

Diabetic cardiac fibrosis increases ventricular stiffness and facilitates the occurrence of diastolic dysfunction. Retinoid X receptor (RXR) plays an important role in cardiac development and has been implicated in cardiovascular diseases. In the present study, we investigated the effects of RXR agonist treatment on streptozotocin (STZ)-induced diabetic cardiomyopathy (DCM) and the underlying mechanism. Sprague-Dawley (SD) rats induced by STZ injection were treated with either RXR agonist bexarotene (Bex) or vehicle alone. Echocardiography was performed to determine cardiac structure and function. Cardiac fibroblasts (CFs) were treated with high glucose (HG) with or without the indicated concentration of Bex or the RXR ligand 9-cis-retinoic acid (9-cis-RA). The protein abundance levels were measured along with collagen, body weight (BW), blood biochemical indexes and transforming growth factor-β (TGF-β) levels. The effects of RXRα down-regulation by RXRα small interfering RNA (siRNA) were examined. The results showed that bexarotene treatment resulted in amelioration of left ventricular dysfunction by inhibiting cardiomyocyte apoptosis and myocardial fibrosis. Immunoblot with heart tissue homogenates from diabetic rats revealed that bexarotene activated liver kinase B1 (LKB1) signaling and inhibited p70 ribosomal protein S6 kinase (p70S6K). The increased collagen levels in the heart tissues of DCM rats were reduced by bexarotene treatment. Treatment of CFs with HG resulted in significantly reduced LKB1 activity and increased p70S6K activity. RXRα mediated the antagonism of 9-cis-RA on HG-induced LKB1/p70S6K activation changes in vitro. Our findings suggest that RXR agonist ameliorates STZ-induced DCM by inhibiting myocardial fibrosis via modulation of the LKB1/p70S6K signaling pathway. RXR agonists may serve as novel therapeutic agents for the treatment of DCM.

Role of Vitamin D in Patients with Heart Failure with Reduced Ejection Fraction

Heart failure (HF) with reduced ejection fraction (HFrEF) presents as the severest phenotype on the spectrum of HF. Although great progress has been made with respect to its treatment over the past 3 decades, morbidity and mortality remain high, posing a big burden on human health. Recent evidence suggests vitamin D has a critical role in maintaining heart health through activation of the vitamin D receptor expressed in cardiomyocytes, and vitamin D deficiency may be implicated in the pathophysiology of HFrEF through activation of the renin-angiotensin system, impaired calcium handling, exaggerated inflammation, secondary hyperparathyroidism, pro-fibrotic properties, and proatherogenic potential. Additionally, epidemiological data disclosed that vitamin D deficiency is highly prevalent in patients with HFrEF and is associated with poor clinical outcomes. However, randomized control trials of vitamin D supplementation in HF, especially in HFrEF, have shown inconsistent results. Thus, this article aims to review the epidemiology, pathophysiology, and prognostic value of vitamin D deficiency in HF, with a special focus on randomized control trials associated with vitamin D supplementation in patients with HFrEF.

Retinoic acid attenuates cardiac injury induced by hyperglycemia in pre- and post-delivery mice

The aim of the present study is to explore the effect of retinoic acid (RA) on cardiac injury induced by gestational diabetes mellitus (GDM). GDM mice were given 3 mg/kg RA once daily until the 19th day of pregnancy or the 7th day of post-partum. Compared to normal control and normal pregnant control mice, GDM mice before and after delivery showed significantly cardiac injury. RA treatment attenuated cardiac injury as evidenced by decreased heart mass and left ventricular mass, mRNA expressions of ANP and BNP, and cardiac fibrosis compared with that in GDM mice. The protective effect of RA on GDM cardiomyopathy was related to the decreased MDA content and ROS generation, the increased GSH-Px and SOD content as well as the reduced TNF-α and IL-1β content and inhibition of NF-κB signaling. In addition, RA treatment delayed the continuous rise of blood glucose before delivery and decreased the higher level of glucose after delivery. In conclusion, RA treatment could increase the activity of the antioxidant enzyme and suppress the oxidative stress, inflammation response, and activation of NF-κB signaling, thereby improving blood glucose level and cardiac injury of GDM mice before and after delivery.

Alternative retinoid X receptor (RXR) ligands

Retinoid X receptors (RXRs) control a wide variety of functions by virtue of their dimerization with other nuclear hormone receptors (NRs), contributing thereby to activities of different signaling pathways. We review known RXR ligands as transcriptional modulators of specific RXR-dimers and the associated biological processes. We also discuss the physiological relevance of such ligands, which remains frequently a matter of debate and which at present is best met by member(s) of a novel family of retinoids, postulated as Vitamin A5. Through comparison with other natural, but also with synthetic ligands, we discuss high diversity in the modes of ligand binding to RXRs resulting in agonistic or antagonistic profiles and selectivity towards specific subtypes of permissive heterodimers. Despite such diversity, direct ligand binding to the ligand binding pocket resulting in agonistic activity was preferentially preserved in the course of animal evolution pointing to its functional relevance, and potential for existence of other, species-specific endogenous RXR ligands sharing the same mode of function.

Molecular mechanisms and genetic regulation in atherosclerosis

Atherosclerosis (AS) manifested by lipid accumulation, extracellular matrix protein deposition, and calcification in the intima and media of the large to medium size arteries promoting arterial stiffness and reduction of elasticity. It has been accepted that AS leads to increased morbidity and mortality worldwide. Recent studies indicated that genetic abnormalities play an important role in the development of AS. Specific genetic mutation and histone modification have been found to induce AS formation. Furthermore, specific RNAs such as microRNAs and circular RNAs have been identified to play a crucial role in the progression of AS. Nevertheless, the mechanisms by which genetic mutation, DNA and histone modification, microRNAs and circular RNA induce AS still remain elusive. This review describes specific mechanisms and pathways through which genetic mutation, DNA and histone modification, microRNAs and circular RNA instigate AS. This review further provides a therapeutic strategic direction for the treatment of AS targeting genetic mechanisms.

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DNA and histone modifications promote transcriptional changes in atherosclerosis.

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Gene mutations cause dyslipidemia and hyperglycemia to promote atherosclerosis.

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miRNAs and cirRNA are involved in the development of atherosclerosis.

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Gene mutations associated oxidative stress and altered inflammatory and nutritive factors promote atherosclerosis.

Vitamin D improves vascular function and decreases monoamine oxidase A expression in experimental diabetes

The active form of vitamin D, 1,25-dihydroxycholecalciferol (1,25(OH)₂D₃), was reported to improve vascular function in patients with diabetes, yet the underlying mechanisms remain to be fully elucidated. Monoamine oxidase (MAO), a mitochondrial enzyme, with two isoforms (A and B) that generates hydrogen peroxide (H₂O₂) as by-product, has been recently reported to contribute to the pathogenesis of endothelial dysfunction in diabetes. The present study assessed the interaction between vitamin D and MAO in the vascular wall in the setting of type 1 experimental diabetes. To this aim, diabetes was induced in male Wistar rats via a single injection of streptozotocin (STZ, 50 mg/kg, IP) and 1 month later thoracic aortas were harvested and used for organ bath studies and H₂O₂ measurements. MAO expression was assessed by immunohistochemistry and RT-PCR. Endothelial function was evaluated in isolated aortic rings in the absence vs. presence of 1,25(OH)₂D₃ (100 nM, 24 h incubation). In diabetic animals, we found a significant reduction in the endothelial-dependent relaxation to acetylcholine and an increased expression of the MAO-A isoform, respectively. Vitamin D significantly improved vascular function, mitigated oxidative stress and decreased MAO-A expression in diabetic vascular preparations. In conclusion, MAO-A is induced in diabetic aortas and vitamin D can improve diabetes-induced endothelial dysfunction by modulating the MAO-A expression.

Vitamin D3 contributes to enhanced osteogenic differentiation of MSCs under oxidative stress condition via activating the endogenous antioxidant system

The anti-oxidative effects of vitamin D3 (Vd3) on mesenchymal stem cells (MSCs) have not been studied before. The present study suggested that Vd3 could not only promote the osteogenic differentiation of MSCs under normal condition but also partly protect it from oxidative stress damage by activating the endogenous antioxidant system.

INTRODUCTION

Evolving evidence proved that oxidative stress caused by reactive oxygen species (ROS) overproduction might lead to bone loss. Vd3, a commonly used osteogenic induction drug, was proved to exhibit potent anti-oxidative effects on other cell types. The present study aims to investigate the protective effects of Vd3 on oxidative stress-induced dysfunctions of MSCs, as well as its underlying mechanisms.

METHODS

The H₂O₂ was used as exogenous reactive oxygen species (ROS). The influence of ROS and anti-oxidative protection of Vd3 on MSCs were analyzed too. Multi-techniques were used to assess the beneficial effects of Vd3 on MSCs under oxidative stress condition.

RESULTS

The results demonstrated that Vd3 could significantly attenuate the H₂O₂-induced cell injury of MSCs via Sirt1/FoxO1 signaling pathway, and reduced the H₂O₂ exposure-induced intracellular oxidative stress status of MSCs. What's more, the H₂O₂ exposure resulted in the decreased osteogenic differentiation of MSCs, as evidenced by decreased alkaline phosphatase activity, calcium deposition level, and osteogenic differentiation gene mRNA levels, but the injury was restored via Vd3 administration.

CONCLUSIONS

The results suggested that Vd3 could not only promote the osteogenic differentiation of osteoblastic cells under normal condition but also partly protect the cell from oxidative stress damage by activating endogenous antioxidant system. The study shed light on the new roles of Vd3 in bone modeling and remodeling regulation.

VDR Agonist Prevents Diabetic Endothelial Dysfunction through Inhibition of Prolyl Isomerase-1-Mediated Mitochondrial Oxidative Stress and Inflammation

Background and aim

Upregulation of prolyl isomerase-1 (Pin1) protein expression and activity was associated with the pathogenesis of diabetic vasculopathy through induction of endothelial oxidative stress and inflammation. Moreover, VDR agonist protects against high glucose-induced endothelial apoptosis through the inhibition of oxidative stress. We aimed to explore the effects of the VDR agonist on diabetes-associated endothelial dysfunction and the role of Pin1 in this process.

Methods

Streptozocin-induced diabetic mice were randomly treated with vehicle, VDR agonist (10 μg/kg/d, i.g., twice a week), or Pin1 inhibitor, Juglone (1 mg/kg/d, i.p., every other day), for eight weeks. In parallel, human umbilical vein endothelial cells (HUVECs) exposed to high-glucose condition were treated with 1,25-dihydroxyvitamin D₃ and Juglone or vehicle for 72 hours. Organ chamber experiments were performed to assess endothelium-dependent relaxation to acetylcholine. Circulatory levels of Pin1, SOD, MDA, IL-1β, IL-6, and NO in diabetic mice, Pin1 protein expression and activity, subcellular distribution of p66Shc, and NF-κB p65 in high glucose-cultured HUVECs were determined.

Results

Both VDR agonist and Juglone significantly improved diabetes-associated endothelial dysfunction and reduced high glucose-induced endothelial apoptosis. Mechanistically, the circulatory levels of SOD and NO were increased compared with those of vehicle-treated diabetic mice. Additionally, Pin1 protein expression and activity, p66Shc mitochondrial translocation, and NF-κB p65 in high glucose-cultured HUVECs were also inhibited by VDR agonist and Juglone. Knockdown of VDR abolished the inhibitory effects of VDR agonist on high glucose-induced upregulation of Pin1 protein expression and activity.

Conclusions

VDR agonist prevents diabetic endothelial dysfunction through inhibition of Pin1-mediated mitochondrial oxidative stress and inflammation.

Role of Vitamin D in Cardiovascular Diseases

Vitamin D is critical in mineral homeostasis and skeletal health and plays a regulatory role in nonskeletal tissues. Vitamin D deficiency is associated with chronic inflammatory diseases, including diabetes and obesity, both strong risk factors for cardiovascular diseases (CVDs). CVDs, including coronary artery disease, myocardial infarction, hypertrophy, cardiomyopathy, cardiac fibrosis, heart failure, aneurysm, peripheral arterial disease, hypertension, and atherosclerosis, are major causes of morbidity and mortality. The association of these diseases with vitamin D deficiency and improvement with vitamin D supplementation suggest its therapeutic benefit. The authors review the findings on the association of vitamin D deficiency and CVDs.

1α,25(OH) 2D3 Sensitive Cytosolic pH Regulation and Glycolytic Flux in Human Endometrial Ishikawa Cells

BACKGROUND/AIMS

Tumor cell proliferation is modified by 1,25-Dihydroxy-Vitamin D3 (1,25(OH)2D3), a steroid hormone predominantly known for its role in calcium and phosphorus metabolism. Key properties of tumor cells include enhanced glycolytic flux with excessive consumption of glucose and formation of lactate. As glycolysis is highly sensitive to cytosolic pH, maintenance of glycolysis requires export of H+ ions and lactate, which is in part accomplished by Na+/H+ exchangers, such as NHE1 and monocarboxylate transporters, such as MCT4. An effect of 1,25(OH)2D3 on those transport processes has, however, never been reported. As cytosolic pH impacts on apoptosis, the study further explored the effect of 1,25(OH)2D3 on apoptosis and on the apoptosis regulating kinase AKT, transcription factor Forkhead box O-3 (FOXO3A) and B-cell lymphoma protein BCL-2.

METHODS

In human endometrial adenocarcinoma (Ishikawa) cells, cytosolic pH (pHi) was determined utilizing (2',7'-bis-(2-carboxyethyl)-5-(and-6)-carboxyfluorescein [BCECF] fluorescence, Na+/H+ exchanger activity from Na+ dependent realkalinization after an ammonium pulse, NHE1 and MCT4 transcript levels using qRT-PCR, NHE1, MCT4, total & phospho AKT, total & phospho-FOXO3A and BCL-2 protein abundance by Western blotting, lactate concentration in the supernatant utilizing a colorimetric enzyme assay and cell death quantification using CytoTox 96®, Annexin V and Propidium Iodide staining.

RESULTS

A 24 hours treatment with 1,25(OH)2D3 (100 nM) significantly increased cytosolic pH (pHi), significantly decreased Na+/H+ exchanger activity, NHE1 and MCT4 transcript levels as well as protein abundance and significantly increased lactate concentration in the supernatant. Treatment of Ishikawa cells with 1,25(OH)2D3 (100 nM) further triggered apoptosis, an effect paralleled by decreased phosphorylation of AKT and FOXO3A as well as decreased abundance of BCL-2.

CONCLUSIONS

In Ishikawa cells 1,25(OH)2D3 is a powerful stimulator of glycolysis, an effect presumably due to cytosolic alkalinization. Despite stimulation of glycolysis, 1,25(OH)2D3 stimulates slightly but significantly suicidal cell death, an effect presumably in part due to decreased activation of AKT with decreased inhibition of pro-apoptotic transcription factor FOXO3A and downregulation of the anti-apoptotic protein BCL-2.

Altered Clock and Lipid Metabolism-Related Genes in Atherosclerotic Mice Kept with Abnormal Lighting Condition

Background. The risk of atherosclerosis is elevated in abnormal lipid metabolism and circadian rhythm disorder. We investigated whether abnormal lighting condition would have influenced the circadian expression of clock genes and clock-controlled lipid metabolism-related genes in ApoE-KO mice. Methods. A mouse model of atherosclerosis with circadian clock genes expression disorder was established using ApoE-KO mice (ApoE-KO LD/DL mice) by altering exposure to light. C57 BL/6J mice (C57 mice) and ApoE-KO mice (ApoE-KO mice) exposed to normal day and night and normal diet served as control mice. According to zeitgeber time samples were acquired, to test atheromatous plaque formation, serum lipids levels and rhythmicity, clock genes, and lipid metabolism-related genes along with Sirtuin 1 (Sirt1) levels and rhythmicity. Results. Atherosclerosis plaques were formed in the aortic arch of ApoE-KO LD/DL mice. The serum lipids levels and oscillations in ApoE-KO LD/DL mice were altered, along with the levels and diurnal oscillations of circadian genes, lipid metabolism-associated genes, and Sirt1 compared with the control mice. Conclusions. Abnormal exposure to light aggravated plaque formation and exacerbated disorders of serum lipids and clock genes, lipid metabolism genes and Sirt1 levels, and circadian oscillation.