Strategies for the efficient biosynthesis of ß-carotene through microbial fermentation.

ß-Carotene is an orange fat-soluble compound, which has been widely used in fields such as food, medicine and cosmetics owing to its anticancer, antioxidant and cardiovascular disease prevention properties. Currently, natural ß-carotene is mainly extracted from plants and algae, which cannot meet the growing market demand, while chemical synthesis of ß-carotene cannot satisfy the pursuit for natural products of consumers. The ß-carotene production through microbial fermentation has become a promising alternative owing to its high efficiency and environmental friendliness. With the rapid development of synthetic biology and in-depth study on the synthesis pathway of ß-carotene, microbial fermentation has shown promising applications in the ß-carotene synthesis. Accordingly, this review aims to summarize the research progress and strategies of natural carotenoid producing strain and metabolic engineering strategies in the heterologous synthesis of ß-carotene by engineered microorganisms. Moreover, it also summarizes the adoption of inexpensive carbon sources to synthesize ß-carotene as well as proposes new strategies that can further improve the ß-carotene production.

Wogonin attenuates inflammation and oxidative stress in lipopolysaccharide-induced mastitis by inhibiting Akt/NF-κB pathway and activating the Nrf2/HO-1 signaling.

Mastitis is a disease involved in inflammation of breast which affects human and animals. Wogonin is one bioactive compound from many Chinese herbal medicines, which have multiple properties, including anti-inflammatory activity. However, the roles of wogonin in mastitis progression are largely undefined. Mastitis models were established using LPS-treated mice and mammary epithelial cells (MECs). Infiltration of inflammatory cells was analyzed by hematoxylin-eosin staining and myeloperoxidase (MPO) activity. Inflammatory cytokine (TNF-α and IL-1ß) levels were detected via ELISA. The phosphorylation and total of Akt and NF-κB levels and content of Nrf2 and HO-1 were measured via western blot. Cell viability was examined by CCK-8 assay. Oxidative stress was assessed by ROS generation and levels of MDA, GSH, and SOD. Wogonin attenuated LPS-induced infiltration of inflammatory cells, increase of MPO activity and levels of TNF-α and IL-1ß, and activation of the Akt/NF-κB pathway in murine mammary gland tissues, and promoted activation of Nrf2/HO-1 signaling. Wogonin did not affect MEC viability, but mitigated LPS-induced inflammation in MECs by reducing TNF-α and IL-1ß levels. Wogonin relieved LPS-induced oxidative stress in MECs through decreasing ROS generation and MDA level and increasing GSH and SOD levels. Wogonin repressed LPS-induced activation of the Akt/NF-κB pathway in MECs and increased Nrf2/HO-1 signaling activation. Activated Akt/NF-κB signaling or Nrf2/HO-1 signaling inactivation reversed the suppressive effects of wogonin on LPS-induced inflammation and oxidative stress in MECs. Wogonin mitigates LPS-induced inflammation and oxidative stress of MECs via suppressing activation of the Akt/NF-κB signaling and activating Nrf2/HO-1 pathway, indicating the therapeutic potential of wogonin in mastitis.

Vital role of SHMT2 in diverse disease.

One-carbon metabolism is essential for our human cells to carry out nucleotide synthesis, methylation, and reductive metabolism through one-carbon units, and these pathways ensure the high proliferation rate of cancer cells. Serine hydroxymethyltransferase 2 (SHMT2) is a key enzyme in one-carbon metabolism. This enzyme can convert serine into a one-carbon unit bound to tetrahydrofolate and glycine, ultimately supporting the synthesis of thymidine and purines and promoting the growth of cancer cells. Due to SHMT2's crucial role in the one-carbon cycle, it is ubiquitous in human cells and even in all organisms and highly conserved. Here, we summarize the impact of SHMT2 on the progression of various cancers to highlight its potential use in the development of cancer treatments.

High-Performance Bifunctional Porous Iron-Rich Phosphide/Nickel Nitride Heterostructures for Alkaline Seawater Splitting.

Seawater is the most abundant natural water resource in the world, which is an inexhaustible and low-cost feedstock for hydrogen production by alkaline water electrolysis. It is appearling to develop robust and stable electrocatalysts for alkaline seawater electrolysis. However, the development of seawater electrolysis is seriously impeded by anodic chloride corrosion and chlorine evolution reaction, and few non-noble electrocatalysts show prominent catalytic performance and excellent durability. Here, a heterogeneous electrocatalyst constructed by in situ growing highly dispersed iron-rich bimetallic phosphide nanoparticles on metallic Ni3 N (Fe2-2 x Co2 x P/Ni3 N), which exhibits outstanding bifunctional catalytic activities for alkaline seawater splitting, is reported. The optimal (Fe0.74 Co0.26 )2 P/Ni3 N and Fe2 P/Ni3 N electrocatalysts demand only 113 and 212 mV to afford 100 mA cm-2 for hydrogen and oxygen evolution reactions (HER and OER) in 1 m KOH, respectively, thus substantially expediting overall water/seawater electrolysis at 100 mA cm-2 with 1.592/1.645 V. Particularly, Fe2 P/Ni3 N displays an unprecedented overpotential of 302 mV at 500 mA cm-2 , which represents the best alkaline seawater oxygen evolution activity among the ever-reported non-noble electrocatalysts; and thus substantially expedites overall water/seawater splitting at 500 mA cm-2 with 1.701/1.768 V, surpassing most of the reported non-noble lectrocatalysts. This work provides a new approach for developing high-performance electrocatalysts for seawater splitting.

Engineering Multilevel Collaborative Catalytic Interfaces with Multifunctional Iron Sites Enabling High-Performance Real Seawater Splitting.

Given the abundant reserves of seawater and the scarcity of freshwater, real seawater electrolysis is a more economically appealing technology for hydrogen production relative to orthodox freshwater electrolysis. However, this technology is greatly precluded by the undesirable chlorine oxidation reaction and severe chloride corrosion at the anode, further restricting the catalytic efficiency of overall seawater splitting. Herein, a feasible strategy by engineering multifunctional collaborative catalytic interfaces is reported to develop porous metal nitride/phosphide heterostructure arrays anchoring on conductive Ni2P surfaces with affluent iron sites. Collaborative catalytic interfaces among iron phosphide, bimetallic nitride, and porous Ni2P supports play a positive role in improving water adsorption/dissociation and hydrogen adsorption behaviors of active Fe sites evidenced by theoretical calculations for hydrogen evolution reactions, and enhancing oxygenated species adsorption and nitrate-rich passivating layers resistant to chloride corrosion for oxygen evolution reaction, thus cooperatively propelling high-performance bifunctional seawater splitting. The resultant material Fe2P/Ni1.5Co1.5N/Ni2P performs excellently as a self-standing bifunctional catalyst for alkaline seawater splitting. It requires extremely low cell voltages of 1.624 and 1.742 V to afford current densities of 100 and 500 mA/cm2 in 1 M KOH seawater electrolytes, respectively, along with superior long-term stability, outperforming nearly all the ever-reported non-noble bifunctional electrocatalysts and benchmark Pt/IrO2 coupled electrodes for freshwater/seawater electrolysis. This work presents an effective strategy for greatly enhancing the catalytic efficiency of non-noble catalysts toward green hydrogen production from seawater electrolysis.

Case Report: Combined transcatheter arterial embolization and aortic stent-graft have better efficacy for bronchial artery aneurysms.

Bronchial artery aneurysm (BAA) is a rare and fatal condition that requires immediate treatment. However, conventional surgical and transcatheter arterial embolization treatments are less effective. In the present case, a 76-year-old hypertensive woman was admitted with dizziness and diagnosed with an unruptured bronchial artery aneurysm, which was treated by transcatheter arterial embolization and aortic stent-graft. The patient's clinical status was stable during the 4-year follow-up. Simultaneously, we reviewed 79 research papers, analyzing past BAA cases for their etiology, symptoms, and treatment outcomes. We found that catheter arterial embolization and aortic stent-graft implantation, especially for BAA of short-necked and arterial tortuosity, demonstrate superior efficacy compared to other methods. Therefore, we consider this approach to be the preferred choice in clinical BAA treatment.

Controlled Continuous Patterning of Spherical Stainless Steel by Multi-Axis Linkage Laser Milling.

While laser surface texturing is promising for the fabrication of planar surface microstructures, the continuously patterning with micrometer accuracy of non-planar surface on miniature parts with large curvature by laser ablation is challenging. In the present work, we demonstrate the feasibility of applying the proposed multi-axis laser milling in continuous patterning of 25 mm diameter spherical stainless steel with high uniformity and precision, based on a strategy of simultaneously adjusting the position and the posture of laser-surface interaction point for enabling the constant coincidence of laser beam with ablated surface normal. Specifically, a miniaturized five-axis platform for controlling workpiece motion with high degree-of-freedom is designed and integrated with a fixed nanosecond pulsed laser beam operating at 1064 nm. The precise path of laser-surface interaction point is derived based on the projection and transformation of pre-determined planar pattern on spherical surface. Meanwhile, a virtual prototype of the multi-axis laser milling with embedded interpolation algorithm is established, which enables the generation of NC codes for subsequent laser milling experiments. Furthermore, the sampling of laser processing parameters particularly for spherical surface is carried out. Finally, complex patterns are continuously structured on the spherical surface by employing the proposed multi-axis laser milling method, and subsequent characterization demonstrates both long range uniformity and local high accuracy of the fabricated patterns. Current work provides a feasible method for the continuous laser surface texturing of non-planar surfaces for miniature parts with large curvature.

Silencing of KIF18B restricts proliferation and invasion and enhances the chemosensitivity of breast cancer via modulating Akt/GSK-3ß/ß-catenin pathway.

Kinesin family member 18B (KIF18B) is a new tumor-associated protein that contributes to the carcinogenesis of multiple malignancies. However, the detailed relevance of KIF18B in breast cancer has not been fully elucidated. This work aimed was to evaluate a possible relationship between KIF18B and breast cancer progression. Our findings show KIF18B is increased in breast cancer and demonstrate that high KIF18B level predicts a reduced survival rate. Cellular functional studies revealed that knockdown of KIF18B markedly reduces the proliferation, invasion, and epithelial-mesenchymal transition of breast cancer cells and enhances their chemosensitivity toward doxorubicin. Further studies showed that KIF18B modulates the level of phospho-Akt, phospho-glycogen synthase kinase-3ß, and ß-catenin. Notably, suppression of Akt abolished KIF18B-overexpression-induced increases in activation of Wnt/ß-catenin pathway. In addition, re-expression of ß-catenin reversed KIF18B-silencing-induced cancer-promoting effect. In vivo animal experiments elucidated that knockdown of KIF18B significantly weakened the tumorigenicity of breast cancer cells. Taken together, data of this study illustrate that KIF18B exerts a potential cancer-promoting function in breast cancer via enhancement of Wnt/ß-catenin pathway through modulation of the Akt/GSK-3ß axis.

Efficacy of Antiviral Treatment in Liver Biopsy-Proven Immune-Tolerant Chronic Hepatitis B Patients: A Retrospective Cohort Study.

The optimal timing of initiating antiviral treatment for immune-tolerant (IT) patients remains unknown. We conducted this study in liver biopsy-proven IT patients to compare the long-term outcomes of untreated and treated patients suffering non-cirrhotic chronic hepatitis B (CHB). This retrospective cohort study recruited 171 consecutive treatment-naïve CHB patients who completed liver biopsy test. Patients were stratified into IT (n = 60), mildly-active (MA; n = 31), immune-active (IA; n = 80), according to alanine aminotransferase (ALT) and liver biopsy data. One hundred and nine patients receiving antiviral treatment constituted the treated set, and 62 patients under close follow-up comprised the untreated set. Primary outcomes were virological response, HBeAg seroconversion, HBsAg loss, ALT normalization, and liver stiffness measurement normalization (NCT03740789). The study population was predominantly male (62.6%) with a mean age of 31 years. The proportion of virological response in treated patients in the MA phase was 57.1%, and the proportion of HBeAg seroconversion was 28.6%, which showed no difference with the 43.8% virological response and 31.5% HBeAg seroconversion in IA patients. The proportions of virological response and seroconversion were 18.2 and 9.1%, respectively, in the IT phase, which were lower than the rates in the MA and IA phases. However, 95.5% of IT patients persisted normal ALT, and 100% of IT patients persisted normal liver stiffness measurement in the treated group. Therefore, antiviral treatment should be considered for CHB patients with high viral load regardless of phase to minimize further damage to hepatocytes.

Advanced glycation end products enhance macrophage polarization to the M1 phenotype via the HIF-1α/PDK4 pathway.

Atherosclerotic plaque rupture followed by luminal thrombosis is recognized as the main cause of acute cardiovascular events, especially in patients with diabetes. Although previous studies identified stimulation of macrophages polarization with advanced glycation end products (AGEs) results in the rapid progression of atherosclerosis, the underlying mechanisms are not understood fully. The purpose of this study was to investigate the effect of hypoxia-inducible factor-1α (HIF-1α) and pyruvate dehydrogenase kinase 4 (PDK4), critical proteins for regulating glucose metabolism, on macrophages polarization in diabetic atherosclerosis, and relevant mechanisms involved. We found that there is an increased number of M1 macrophages in carotid atherosclerotic tissues of diabetic mice and in AGE-bovine serum albumin (BSA)-treated RAW264.7 cells. Furthermore, we observed that HIF-1α was upregulated in AGE-BSA-induced M1 polarization and that the HIF-1α knockdown reduced macrophage polarization to M1 phenotype caused by AGE-BSA via regulation of PDK4. Thus, our study identified the critical role of HIF-1α/PDK4 axis in AGE-BSA-induced M1 polarization, which reflected the potential association between energy metabolism and inflammation in macrophages.

Lactate accelerates vascular calcification through NR4A1-regulated mitochondrial fission and BNIP3-related mitophagy.

Arterial media calcification is related to mitochondrial dysfunction. Protective mitophagy delays the progression of vascular calcification. We previously reported that lactate accelerates osteoblastic phenotype transition of VSMC through BNIP3-mediated mitophagy suppression. In this study, we investigated the specific links between lactate, mitochondrial homeostasis, and vascular calcification. Ex vivo, alizarin S red and von Kossa staining in addition to measurement of calcium content, RUNX2, and BMP-2 protein levels revealed that lactate accelerated arterial media calcification. We demonstrated that lactate induced mitochondrial fission and apoptosis in aortas, whereas mitophagy was suppressed. In VSMCs, lactate increased NR4A1 expression, leading to activation of DNA-PKcs and p53. Lactate induced Drp1 migration to the mitochondria and enhanced mitochondrial fission through NR4A1. Western blot analysis of LC3-II and p62 and mRFP-GFP-LC3 adenovirus detection showed that NR4A1 knockdown was involved in enhanced autophagy flux. Furthermore, NR4A1 inhibited BNIP3-related mitophagy, which was confirmed by TOMM20 and BNIP3 protein levels, and LC3-II co-localization with TOMM20. The excessive fission and deficient mitophagy damaged mitochondrial structure and impaired respiratory function, determined by mPTP opening rate, mitochondrial membrane potential, mitochondrial morphology under TEM, ATP production, and OCR, which was reversed by NR4A1 silencing. Mechanistically, lactate enhanced fission but halted mitophagy via activation of the NR4A1/DNA-PKcs/p53 pathway, evoking apoptosis, finally accelerating osteoblastic phenotype transition of VSMC and calcium deposition. This study suggests that the NR4A1/DNA-PKcs/p53 pathway is involved in the mechanism by which lactate accelerates vascular calcification, partly through excessive Drp-mediated mitochondrial fission and BNIP3-related mitophagy deficiency.

HIF-1α/PDK4/autophagy pathway protects against advanced glycation end-products induced vascular smooth muscle cell calcification.

Osteogenic differentiation of VSMC is one of the main causes of diabetic vascular calcification, and AGEs accumulation accelerates the calcification of VSMCs in diabetic patients. Autophagy has also been found to play an important role in the process of vascular calcification. However, the potential link between AGEs, autophagy and vascular calcification is still unclear and was investigated in this study. Primary VSMCs were isolated from the thoracic aorta of Sprague Dawley rats and cultured with AGEs-BSA to induce osteogenic differentiation. VSMCs calcification was evaluated by measuring the calcium content, RUNX2 protein levels, and by Alizarin red S staining. We demonstrated that treatment of VSMCs with AGE-BSA increased the expression of HIF-1α and PDK4. AGE-BSA treatment increased LC3-II and decreased p62 protein levels. AGE-BSA exposure enhanced autophagic flux determined by mRFP-GFP-LC3 adenovirus, induced co-localization of LC3-II and LAMP-1, and increased the number of autophagasome under TEM. HIF-1α/PDK4 pathway was activated during AGEs-induced autophagy of VSMCs. In addition, autophagy played a protective role during AGE-induced calcification of VSMCs. In conclusion, AGEs enhance autophagy via the HIF-1α/PDK4 signaling pathway, and autophagy helps attenuate AGE-induced calcification of VSMCs.

BDNF-mediated mitophagy alleviates high-glucose-induced brain microvascular endothelial cell injury.

Endothelial cell dysfunction and diabetic vascular complications are intrinsically linked. Although BDNF plays a protective role in cerebral microvascular complications caused by diabetes, the mechanisms of this activity are not fully clear. In this study, we investigated the role of BDNF in the hyperglycemic injury of BMECs and its associated intracellular signal transduction pathways. BMECs were treated with 33 mM glucose to imitate the endothelium under hyperglycemic conditions. The high-glucose treatment caused cell dysfunction, as evaluated by oxidative stress and cell apoptosis, which could be alleviated by BDNF. In addition, BDNF preserved mitochondrial function as assessed by mPTP opening, mitochondrial membrane potential, calcium content, and mitochondrial biogenesis markers. Western blot analysis of LC3-II, p62, and TOMM20 and the detection of mRFP-GFP-LC3 adenovirus for autophagy flux revealed that BDNF enhanced autophagy flux. Furthermore, BDNF activated mitophagy, which was confirmed by the observed colocalization of LC3-II with BNIP3 and from transmission electron microscopy observations. The HIF-1α/BNIP3 signaling pathway was associated with BDNF/TrkB-induced mitophagy. In addition, BDNF-induced mitophagy played a protective role against BMEC damage under hyperglycemia. Thus, the results of this study suggest that BDNF/TrkB/HIF-1α/BNIP3-mediated mitophagy protects BMECs from hyperglycemia.

High expression of SPAG5 sustains the malignant growth and invasion of breast cancer cells through the activation of Wnt/ß-catenin signalling.

Sperm-associated antigen 5 (SPAG5) has currently emerged as a novel oncogene in various cancers. High expression of SPAG5 has been frequently detected in breast cancer. However, the biological function and regulatory mechanism of SPAG5 in breast cancer remain unclear. In this study, we aimed to investigate the potential biological function of SPAG5 in breast cancer cells. Herein, we found that both the mRNA and protein expression of SPAG5 were significantly up-regulated in breast cancer cell lines. Functional experiments showed that silencing of SPAG5 inhibited the proliferation and invasion of breast cancer cells, while the overexpression of SPAG5 promoted the proliferation and invasion of breast cancer cells. Mechanistic investigation demonstrated that SPAG5 promoted the expression of Wnt3 and ß-catenin, and increased the activation of ß-catenin/TCF4 transcriptional activity. Notably, the inhibition of Wnt3 partially reversed the promotion effect of SPAG5 on breast cancer cell proliferation and invasion and ß-catenin/TCF4 signalling. In addition, the inhibition of ß-catenin also significantly abrogated SPAG5-mediated oncogenic effects in breast cancer. Taken together, these findings demonstrate that SPAG5 promotes the proliferation and invasion of breast cancer cells by activating Wnt/ß-catenin signalling via up-regulating Wnt3 expression.

Lactate accelerates calcification in VSMCs through suppression of BNIP3-mediated mitophagy.

Arterial media calcification is one of the major complications of diabetes mellitus, which is related to oxidative stress and apoptosis. Mitophagy is a special regulation of mitochondrial homeostasis and takes control of intracellular ROS generation and apoptotic pathways. High circulating levels of lactate usually accompanies diabetes. The potential link between lactate, mitophagy and vascular calcification is investigated in this study. Lactate treatment accelerated VSMC calcification, evaluated by measuring the calcium content, ALP activity, RUNX2, BMP-2 protein levels, and Alizarin red S staining. Lactate exposure caused excessive intracellular ROS generation and VSMC apoptosis. Lactate also impaired mitochondrial function, determined by mPTP opening rate, mitochondrial membrane potential and mitochondrial biogenesis markers. Western blot analysis of LC3-II and p62 and mRFP-GFP-LC3 adenovirus detection for autophagy flux revealed that lactate blocked autophagy flux. LC3-II co-staining with LAMP-1 and autophagosome quantification revealed lactate inhibited autophagy. Furthermore, lactate inhibited mitophagy, which was confirmed by TOMM20 and BNIP3 protein levels, LC3-II colocalization with BNIP3 and TEM assays. In addition, BNIP3-mediated mitophagy played a protective role against VSMC calcification in the presence of lactate. This study suggests that lactate accelerates osteoblastic phenotype transition of VSMC and calcium deposition partly through the BNIP3-mediated mitophagy deficiency induced oxidative stress and apoptosis.

MicroRNA-449b-5p suppresses the growth and invasion of breast cancer cells via inhibiting CREPT-mediated Wnt/ß-catenin signaling.

Accumulating evidence has suggested that microRNA-449b-5p (miR-449b-5p) plays an important role in the development and progression of multiple cancers. However, little is known about the role of miR-449b-5p in breast cancer. In this study, we aimed to investigate the expression level, biological function and underlying mechanism of miR-449b-5p in breast cancer. Our results showed that miR-449b-5p expression was frequently down-regulated in breast cancer cell lines and tissues. The overexpression of miR-449b-5p significantly inhibited growth and invasion, and induced the cell cycle arrest of breast cancer cells. In contrast, the inhibition of miR-449b-5p showed the opposite effect. Interestingly, bioinformatic analysis predicted that cell cycle-related and expression-elevated protein in tumor (CREPT), an important oncogene in breast cancer, was a potential target gene of miR-449b-5p. The overexpression of miR-449b-5p decreased CREPT expression while miR-449b-5p inhibition promoted CREPT expression in breast cancer cells. Restoration of CREPT expression in miR-449b-5p mimics transfected cells partially reversed the suppressive effect of miR-449b-5p on breast cancer cell growth and invasion. Notably, our results showed that miR-449b-5p overexpression decreased the expression of ß-catenin and suppressed the activation of Wnt/ß-catenin/TCF-4 signaling via targeting CREPT. In addition, blocking Wnt/ß-catenin partially reversed the promotion effect of miR-449b-5p inhibition on breast cancer cell growth and invasion. Overall, these results reveal a tumor suppressive role of miR-449b-5p that restricts the growth and invasion of breast cancer cells through targeting CREPT and inhibiting CREPT-mediated activation of Wnt/ß-catenin signaling. Our study suggests that the miR-449b-5p/CREPT/Wnt/ß-catenin axis may play an important role in the pathogenesis of breast cancer and miR-449-5p may serve as a potential therapeutic target for breast cancer.

Impact of smoking on all-cause mortality and cardiovascular events in patients after coronary revascularization with a percutaneous coronary intervention or coronary artery bypass graft: a systematic review and meta-analysis.

Although cigarette smoking is an independent risk factor for cardiovascular disease, inconsistent results have been published in the literature on its impacts on the cardiovascular health of patients after coronary revascularization with a percutaneous coronary intervention (PCI) or coronary artery bypass graft (CABG). We performed a comprehensive electronic database search through July 2018. Studies reporting the risk estimates of all-cause mortality and cardiovascular outcomes in patients after coronary revascularization with PCI or CABG on the basis of smoking status were selected. Multivariate-adjusted relative risks (RRs) and 95% confidence intervals (CIs) were pooled using random-effects models with inverse variance weighting. Data from 37 records including 126 901 participants were finally collected. Overall, the pooled RR (95% CI) associated with cigarette smoking was 1.26 (95% CI: 1.09-1.47) for all-cause mortality, 1.08 (95% CI: 0.92-1.28) for major adverse cardiovascular events, 0.96 (95% CI: 0.69-1.35) for cardiovascular mortality and 1.15 (95% CI: 0.81-1.64) for myocardial infarction. The increased risk of all-cause mortality was also observed in former smokers compared with those who had never smoked (RR: 1.19; 95% CI: 1.03-1.38). Furthermore, the negative effects of cigarette smoking on all-cause mortality were also observed in most subgroups. Cigarette smoking has been shown to increase the likelihood of all-cause mortality in patients after coronary revascularization with PCI or CABG. Smoking cessation is essential for PCI or CABG patients to manage their coronary artery disease.

Metformin Modulates High Glucose-Incubated Human Umbilical Vein Endothelial Cells Proliferation and Apoptosis Through AMPK/CREB/BDNF Pathway.

Cardiovascular disease (CVD) is a leading cause of mortality and morbidity among patients with diabetes. Endothelial dysfunction is an early physiological event in CVD. Metformin, a common oral antihyperglycemic agent, has been demonstrated to directly affect endothelial cell function. Brain-derived neurotrophic factor (BDNF), originally discovered in the brain as a neurotrophin, has also been reported to play a protective role in the cardiovascular system. In our study, we demonstrated that high glucose (HG) reduced cell proliferation and induced cell apoptosis via changes in BDNF expression and that metformin reversed the effects of HG injury by upregulating BDNF expression. Furthermore, we found that cyclic AMP response element binding (CREB) phosphorylation was reduced in HG-treated human umbilical vein endothelial cells (HUVECs), and this effect was reversed by the metformin treatment. However, the metformin effect on BDNF levels in HG-incubated HUVECs was blocked by a CREB inhibitor, which indicated that BDNF expression is regulated by metformin through CREB activation. In addition, we found that adenosine monophosphate-activated protein kinase (AMPK) activation is involved in CREB/BDNF regulation in HG-incubated HUVECs treated with metformin and that an AMPK inhibitor impaired the protective effects of metformin on HG-treated HUVECs. In conclusion, this study demonstrated that metformin affects cell proliferation and apoptosis via the AMPK/CREB/BDNF pathway in HG-incubated HUVECs.

Advanced glycation end products accelerate calcification in VSMCs through HIF-1α/PDK4 activation and suppress glucose metabolism.

Arterial media calcification is associated with diabetes mellitus. Previous studies have shown that advanced glycation end products (AGEs) are responsible for vascular smooth muscle cell (VSMC) calcification, but the underlying mechanisms remain unclear. Hypoxia-inducible factor-1α (HIF-1α), one of the major factors during hypoxia, and pyruvate dehydrogenase kinase 4 (PDK4), an important mitochondrial matrix enzyme in cellular metabolism shift, have been reported in VSMC calcification. The potential link among HIF-1α, PDK4, and AGEs-induced vascular calcification was investigated in this study. We observed that AGEs elevated HIF-1α and PDK4 expression levels in a dose-dependent manner and that maximal stimulation was attained at 24 h. Two important HIF-1α-regulated genes, vascular endothelial growth factor A (VEGFA) and glucose transporter 1 (GLUT-1), were significantly increased after AGEs exposure. Stabilization or nuclear translocation of HIF-1α increased PDK4 expression. PDK4 inhibition attenuated AGEs-induced VSMC calcification, which was evaluated by measuring the calcium content, alkaline phosphatase (ALP) activity and runt-related transcription factor 2 (RUNX2) expression levels and by Alizarin red S staining. In addition, the glucose consumption, lactate production, key enzymes of glucose metabolism and oxygen consumption rate (OCR) were decreased during AGEs-induced VSMC calcification. In conclusion, this study suggests that AGEs accelerate vascular calcification partly through the HIF-1α/PDK4 pathway and suppress glucose metabolism.

Association of genetic polymorphisms in vascular endothelial growth factor with susceptibility to coronary artery disease: a meta-analysis.

BACKGROUND: Single nucleotide polymorphisms (SNPs) located in the vascular endothelial growth factor (VEGF) gene may be correlated with the susceptibility to coronary artery disease (CAD) - although results have been controversial. The aim of this meta-analysis is to clarify the effects of VEGF -2578A/C (rs699947), -1154G/A (rs1570360), +405C/G (rs2010963), and + 936C/T (rs3025039) polymorphisms on CAD risk. METHODS: Pooled odds ratio (OR) and corresponding 95% confidence intervals (CIs) were calculated to estimate the strength of the association between VEGF gene polymorphisms and CAD risk. Fixed- or random-effects model was used depending on the heterogeneity between studies. RESULTS: In total, 13 eligible articles containing 29 studies were analysed. The pooled analysis indicated that the VEGF gene polymorphisms of rs699947, rs2010963, and rs3025039 were associated with an increased risk of CAD, whereas no significant associations were observed with the rs1570360 polymorphism. A subgroup analysis stratified by ethnicity revealed that the rs699947 and rs3025039 polymorphisms were associated with CAD risk in Asian populations. In addition, stratification by control source indicated an increased risk of CAD susceptibility with the rs699947 polymorphism for population-based studies of reduced heterogeneity. CONCLUSIONS: In summary, we concluded that the VEGF gene polymorphisms rs699947, rs2010963, and rs3025039 are correlated with an elevated CAD risk.