Nrf2 as an Endothelial Mechanosensitive Transcription Factor: Going With the Flow

Atlas of cardiac endothelial cell enhancer elements linking the mineralocorticoid receptor to pathological gene expression

Endothelial cells play crucial roles in physiology and are increasingly recognized as therapeutic targets in cardiovascular disease. Here, we analyzed the regulatory landscape of cardiac endothelial cells by assessing chromatin accessibility, histone modifications, and 3D chromatin organization and confirmed the functional relevance of enhancer-promoter interactions by CRISPRi-mediated enhancer silencing. We used this dataset to explore mechanisms of transcriptional regulation in cardiovascular disease and compared six different experimental models of heart failure, hypertension, or diabetes. Enhancers that regulate gene expression in diseased endothelial cells were enriched with binding sites for a distinct set of transcription factors, including the mineralocorticoid receptor (MR), a known drug target in heart failure and hypertension. For proof of concept, we applied endothelial cell-specific MR deletion in mice to confirm MR-dependent gene expression and predicted direct MR target genes. Overall, we have compiled here a comprehensive atlas of cardiac endothelial cell enhancer elements that provides insight into the role of transcription factors in cardiovascular disease.

Marginated aberrant red blood cells induce pathologic vascular stress fluctuations in a computational model of hematologic disorders

Red blood cell (RBC) disorders such as sickle cell disease affect billions worldwide. While much attention focuses on altered properties of aberrant RBCs and corresponding hemodynamic changes, RBC disorders are also associated with vascular dysfunction, whose origin remains unclear and which provoke severe consequences including stroke. Little research has explored whether biophysical alterations of RBCs affect vascular function. We use a detailed computational model of blood that enables characterization of cell distributions and vascular stresses in blood disorders and compare simulation results with experimental observations. Aberrant RBCs, with their smaller size and higher stiffness, concentrate near vessel walls (marginate) because of contrasts in physical properties relative to normal cells. In a curved channel exemplifying the geometric complexity of the microcirculation, these cells distribute heterogeneously, indicating the importance of geometry. Marginated cells generate large transient stress fluctuations on vessel walls, indicating a mechanism for the observed vascular inflammation.

Compact engineered human mechanosensitive transactivation modules enable potent and versatile synthetic transcriptional control

Engineered transactivation domains (TADs) combined with programmable DNA binding platforms have revolutionized synthetic transcriptional control. Despite recent progress in programmable CRISPR-Cas-based transactivation (CRISPRa) technologies, the TADs used in these systems often contain poorly tolerated elements and/or are prohibitively large for many applications. Here, we defined and optimized minimal TADs built from human mechanosensitive transcription factors. We used these components to construct potent and compact multipartite transactivation modules (MSN, NMS and eN3x9) and to build the CRISPR-dCas9 recruited enhanced activation module (CRISPR-DREAM) platform. We found that CRISPR-DREAM was specific and robust across mammalian cell types, and efficiently stimulated transcription from diverse regulatory loci. We also showed that MSN and NMS were portable across Type I, II and V CRISPR systems, transcription activator-like effectors and zinc finger proteins. Further, as proofs of concept, we used dCas9-NMS to efficiently reprogram human fibroblasts into induced pluripotent stem cells and demonstrated that mechanosensitive transcription factor TADs are efficacious and well tolerated in therapeutically important primary human cell types. Finally, we leveraged the compact and potent features of these engineered TADs to build dual and all-in-one CRISPRa AAV systems. Altogether, these compact human TADs, fusion modules and delivery architectures should be valuable for synthetic transcriptional control in biomedical applications.

Disturbed hemodynamics and oxidative stress interaction in endothelial dysfunction and AAA progression: Focus on Nrf2 pathway

Hemodynamic shear stress is one of the major factors that are involved in the pathogenesis of many cardiovascular diseases including atherosclerosis and abdominal aortic aneurysm (AAA), through its modulatory effect on the endothelial cell's redox homeostasis and mechanosensitive gene expression. Among important mechanisms, oxidative stress, endoplasmic reticulum stress activation, and the subsequent endothelial dysfunction are attributed to disturbed blood flow and low shear stress in the vascular curvature and bifurcations which are considered atheroprone regions and aneurysm occurrence spots. Many pathways were shown to be involved in AAA progression. Of particular interest from recent findings is, the (Nrf2)/Keap-1 pathway, where Nrf2 is a transcription factor that has antioxidant properties and is strongly associated with several CVDs, yet, the exact mechanism by which Nrf2 alleviates CVDs still to be elucidated. Nrf2 expression is closely affected by shear stress and was shown to participate in AAA. In the current review paper, we discussed the link between disturbed hemodynamics and its effect on Nrf2 as a mechanosensitive gene and its role in the development of endothelial dysfunction which is linked to the progression of AAA.

Endothelial mechanobiology in atherosclerosis

Cardiovascular disease (CVD) is a serious health challenge, causing more deaths worldwide than cancer. The vascular endothelium, which forms the inner lining of blood vessels, plays a central role in maintaining vascular integrity and homeostasis and is in direct contact with the blood flow. Research over the past century has shown that mechanical perturbations of the vascular wall contribute to the formation and progression of atherosclerosis. While the straight part of the artery is exposed to sustained laminar flow and physiological high shear stress, flow near branch points or in curved vessels can exhibit 'disturbed' flow. Clinical studies as well as carefully controlled in vitro analyses have confirmed that these regions of disturbed flow, which can include low shear stress, recirculation, oscillation, or lateral flow, are preferential sites of atherosclerotic lesion formation. Because of their critical role in blood flow homeostasis, vascular endothelial cells (ECs) have mechanosensory mechanisms that allow them to react rapidly to changes in mechanical forces, and to execute context-specific adaptive responses to modulate EC functions. This review summarizes the current understanding of endothelial mechanobiology, which can guide the identification of new therapeutic targets to slow or reverse the progression of atherosclerosis.

Integration of transcriptomics and metabolomics to reveal the effect of ginsenoside Rg3 on allergic rhinitis in mice

Increasing studies have demonstrated that ginsenoside Rg3 (Rg3) plays an important role in the prevention and treatment of various diseases, including allergic lower airway inflammation such as asthma. To investigate the role of Rg3 in allergic upper airway disease, the effect and therapeutic mechanism of Rg3 in allergic rhinitis (AR) were studied. Ovalbumin-induced AR model mice were intragastrically administered with Rg3. Nasal symptoms, levels of IgE, IL-4, IL-5, IL-13, SOD and MDA in serum, and histopathological analysis of nasal mucosa were used to evaluate the effect of Rg3 on ameliorating AR in mice. Moreover, nasal mucosa samples from the normal control group, AR model group and high dosage of Rg3 were collected to perform omics analysis. The differentially expressed genes and significantly changed metabolites were screened based on transcriptomics and metabolomics analyses, respectively. Integrative analysis was further performed to confirm the hub genes, metabolites and pathways. After Rg3 intervention, the nasal symptoms and inflammatory infiltration were effectively improved, the levels of IgE, IL-4, IL-5, IL-13 and MDA were significantly reduced, and the level of SOD was obviously increased. The results of the qRT-PCR assay complemented the transcriptomic findings. Integrated analysis showed that Rg3 played an anti-AR role mainly by regulating the interaction network, which was constructed by 12 genes, 8 metabolites and 4 pathways. Our findings suggested that Rg3 had a therapeutic effect on ovalbumin-induced AR in mice by inhibiting inflammation development and reducing oxidative stress. The present study could provide a potential natural agent for the treatment of AR.

Spirulina platensis Ameliorates Oxidative Stress Associated with Antiretroviral Drugs in HepG2 Cells

Lately, Spirulina platensis (SP), as an antioxidant, has exhibited high potency in the treatment of oxidative stress, diabetes, immune disorder, inflammatory stress, and bacterial and viral-related diseases. This study investigated the possible protective role of Spirulina platensis against ARV-induced oxidative stress in HepG2 cells. Human liver (HepG2) cells were treated with ARVs ((Lamivudine (3TC): 1.51 µg/mL, tenofovir disoproxil fumarate (TDF): 0.3 µg/mL and Emtricitabine (FTC): 1.8 µg/mL)) for 96 h and thereafter treated with 1.5 µg/mL Spirulina platensis for 24 h. After the treatments, the gene and protein expressions of the antioxidant response pathway were determined using a quantitative polymerase chain reaction (qPCR) and Western blots. The results show that Spirulina platensis decreased the gene expressions of Akt (p < 0.0001) and eNOS (↓p < 0.0001) while, on the contrary, it increased the transcript levels of NRF-2 (↑p = 0.0021), Keap1 (↑p = 0.0002), CAT (↑p < 0.0001), and NQO-1 (↑p = 0.1432) in the HepG2 cells. Furthermore, the results show that Spirulina platensis also decreased the protein expressions of NRF-2 (↓p = 0.1226) and pNRF-2 (↓p = 0.0203). Interestingly, HAART-SP induced an NRF-2 pathway response through upregulating NRF-2 (except for FTC-SP) (↑p < 0.0001), CAT (↑p < 0.0001), and NQO-1 (except for FTC-SP) (↑p < 0.0001) mRNA expression. In addition, NRF-2 (↑p = 0.0085) and pNRF-2 (↑p < 0.0001) protein expression was upregulated in the HepG2 cells post-exposure to HAART-SP. The results, therefore, allude to the fact that Spirulina platensis has the potential to mitigate HAART-adverse drug reactions (HAART toxicity) through the activation of antioxidant response in HepG2 cells. We hereby recommend further studies on Spirulina platensis and HAART synergy.

Nrf2-Mediated Dichotomy in the Vascular System: Mechanistic and Therapeutic Perspective

Nuclear factor-erythroid 2-related factor 2 (Nrf2), a transcription factor, controls the expression of more than 1000 genes that can be clustered into different categories with distinct functions ranging from redox balance and metabolism to protein quality control in the cell. The biological consequence of Nrf2 activation can be either protective or detrimental in a context-dependent manner. In the cardiovascular system, most studies have focused on the protective properties of Nrf2, mainly as a key transcription factor of antioxidant defense. However, emerging evidence revealed an unexpected role of Nrf2 in mediating cardiovascular maladaptive remodeling and dysfunction in certain disease settings. Herein we review the role of Nrf2 in cardiovascular diseases with a focus on vascular disease. We discuss the negative effect of Nrf2 on the vasculature as well as the potential underlying mechanisms. We also discuss the clinical relevance of targeting Nrf2 pathways for the treatment of cardiovascular and other diseases.

Nrf2-Keap-1 imbalance under acute shear stress induces inflammatory response in venous endothelial cells

Vascular endothelial cell stimulation is associated with the activation of different signalling pathways and transcription factors. Acute shear stress is known to induce different pro-inflammatory mediators such as IL-8. Nrf2 is activated by prolonged high shear stress promoting an antiinflammatory and athero-protective environment. However, little is known about the impact of acute shear stress on Nrf2 and Keap1 function and its role in IL-8 regulation. We aimed to examine Nrf2-Keap1 complex activation in-vitro and its role in regulating IL-8 transcripts under acute arterial shear stress (12 dyn/cm2) in venous endothelial cells (ECs). We note that acute high shear stress caused a significant upregulation of Nrf2 target genes, HO-1 and GCLM and an increased IL-8 upregulation at 90 and 120 minutes. Mechanistically, acute high shear did not affect Nrf2 nuclear translocation but resulted in reduced nuclear Keap1, suggesting that the reduction in nuclear Keap1 may result in increased free nuclear nrf2 to induce transcription. Consistently, the suppression of Keap1 using shRNA (shKeap1) resulted in significant upregulation of IL-8 transcripts in response to acute shear stress. Interestingly; the over expression of Nrf2 using Nrf2-Ad-WT or Sulforaphane was also associated with significant upregulation of IL-8 compared to controls. This study highlights the role of Keap1 in Nrf2 activation under shear stress and indicates that activation of Nrf2 may be deleterious in ECs in the context of acute haemodynamic injury.

Endothelial shear stress signal transduction and atherogenesis: From mechanisms to therapeutics

Atherosclerotic vascular disease and its complications are among the top causes of mortality worldwide. In the vascular lumen, atherosclerotic plaques are not randomly distributed. Instead, they are preferentially localized at the curvature and bifurcations along the arterial tree, where shear stress is low or disturbed. Numerous studies demonstrate that endothelial cell phenotypic change (e.g., inflammation, oxidative stress, endoplasmic reticulum stress, apoptosis, autophagy, endothelial-mesenchymal transition, endothelial permeability, epigenetic regulation, and endothelial metabolic adaptation) induced by oscillatory shear force play a fundamental role in the initiation and progression of atherosclerosis. Mechano-sensors, adaptor proteins, kinases, and transcriptional factors work closely at different layers to transduce the shear stress force from the plasma membrane to the nucleus in endothelial cells, thereby controlling the expression of genes that determine cell fate and phenotype. An in-depth understanding of these mechano-sensitive signaling cascades shall provide new translational strategies for therapeutic intervention of atherosclerotic vascular disease. This review updates the recent advances in endothelial mechano-transduction and its role in the pathogenesis of atherosclerosis, and highlights the perspective of new anti-atherosclerosis therapies through targeting these mechano-regulated signaling molecules.

Helichrysetin inhibits gastric cancer growth by targeting c-Myc/PDHK1 axis-mediated energy metabolism reprogramming

Helichrysetin (HEL), a chalcone isolated from Alpinia katsumadai Hayata, has an antitumor activity in human lung and cervical cancers. However, the inhibitory effect and underlying mechanism of HEL in gastric cancer have not been elucidated. Here, HEL significantly inhibited the growth of gastric cancer MGC803 cells in vitro and in vivo. HEL decreased expression and transcriptional regulatory activity of c-Myc and mRNA expression of c-Myc target genes. HEL enhanced mitochondrial oxidative phosphorylation (OXPHOS) and reduced glycolysis as evidenced by increased mitochondrial adenosine triphosphate (ATP) production and excessive reactive oxygen species (ROS) accumulation, and decreased the pPDHA1/PDHA1 ratio and Glyco-ATP production. Pyruvate enhanced OXPHOS after HEL treatment. c-Myc overexpression abolished HEL-induced inhibition of cell viability, glycolysis, and protein expression of PDHK1 and LDHA. PDHK1 overexpression also counteracted inhibitory effect of HEL on cell viability. Conversely, c-Myc siRNA decreased cell viability, glycolysis, and PDHK1 expression. NAC rescued the decrease in viability of HEL-treated cells. Additionally, HEL inhibited the overactivated mTOR/p70S6K pathway in vitro and in vivo. HEL-induced cell viability inhibition was counteracted by an mTOR agonist. mTOR inhibitor also decreased cell viability. Similar results were obtained in SGC7901 cells. HEL repressed lactate production and efflux in MGC803 cells. These results revealed that HEL inhibits gastric cancer growth by targeting mTOR/p70S6K/c-Myc/PDHK1-mediated energy metabolism reprogramming in cancer cells. Therefore, HEL may be a potential agent for gastric cancer treatment by modulating cancer energy metabolism reprogramming.

Blood-brain barrier leakage in Alzheimer's disease: From discovery to clinical relevance

Alzheimer's disease (AD) is the most common form of dementia. AD brain pathology starts decades before the onset of clinical symptoms. One early pathological hallmark is blood-brain barrier dysfunction characterized by barrier leakage and associated with cognitive decline. In this review, we summarize the existing literature on the extent and clinical relevance of barrier leakage in AD. First, we focus on AD animal models and their susceptibility to barrier leakage based on age and genetic background. Second, we re-examine barrier dysfunction in clinical and postmortem studies, summarize changes that lead to barrier leakage in patients and highlight the clinical relevance of barrier leakage in AD. Third, we summarize signaling mechanisms that link barrier leakage to neurodegeneration and cognitive decline in AD. Finally, we discuss clinical relevance and potential therapeutic strategies and provide future perspectives on investigating barrier leakage in AD. Identifying mechanistic steps underlying barrier leakage has the potential to unravel new targets that can be used to develop novel therapeutic strategies to repair barrier leakage and slow cognitive decline in AD and AD-related dementias.

Transcriptome analysis reveals fluid shear stress (FSS) and atherosclerosis pathway as a candidate molecular mechanism of short-term low salinity stress tolerance in abalone

Background

Transcriptome sequencing is an effective tool to reveal the essential genes and pathways underlying countless biotic and abiotic stress adaptation mechanisms. Although severely challenged by diverse environmental conditions, the Pacific abalone Haliotis discus hannai remains a high-value aquaculture mollusk and a Chinese predominantly cultured abalone species. Salinity is one of such environmental factors whose fluctuation could significantly affect the abalone’s cellular and molecular immune responses and result in high mortality and reduced growth rate during prolonged exposure. Meanwhile, hybrids have shown superiority in tolerating diverse environmental stresses over their purebred counterparts and have gained admiration in the Chinese abalone aquaculture industry.

The objective of this study was to investigate the molecular and cellular mechanisms of low salinity adaptation in abalone. Therefore, this study used transcriptome analysis of the gill tissues and flow cytometric analysis of hemolymph of H. discus hannai (DD) and interspecific hybrid H. discus hannai ♀ x H. fulgens ♂ (DF) during low salinity exposure. Also, the survival and growth rate of the species under various salinities were assessed.

Results

The transcriptome data revealed that the differentially expressed genes (DEGs) were significantly enriched on the fluid shear stress and atherosclerosis (FSS) pathway. Meanwhile, the expression profiles of some essential genes involved in this pathway suggest that abalone significantly up-regulated calmodulin-4 (CaM-4) and heat-shock protein90 (HSP90), and significantly down-regulated tumor necrosis factor (TNF), bone morphogenetic protein-4 (BMP-4), and nuclear factor kappa B (NF-kB).

Also, the hybrid DF showed significantly higher and sustained expression of CaM and HSP90, significantly higher phagocytosis, significantly lower hemocyte mortality, and significantly higher survival at low salinity, suggesting a more active molecular and hemocyte-mediated immune response and a more efficient capacity to tolerate low salinity than DD.

Conclusions

Our study argues that the abalone CaM gene might be necessary to maintain ion equilibrium while HSP90 can offset the adverse changes caused by low salinity, thereby preventing damage to gill epithelial cells (ECs).

The data reveal a potential molecular mechanism by which abalone responds to low salinity and confirms that hybridization could be a method for breeding more stress-resilient aquatic species.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12864-022-08611-8.

Oxidative Stress in Arterial Hypertension (HTN): The Nuclear Factor Erythroid Factor 2-Related Factor 2 (Nrf2) Pathway, Implications and Future Perspectives

Arterial hypertension (HTN) is one of the most prevalent entities globally, characterized by increased incidence and heterogeneous pathophysiology. Among possible etiologies, oxidative stress (OS) is currently extensively studied, with emerging evidence showing its involvement in endothelial dysfunction and in different cardiovascular diseases (CVD) such as HTN, as well as its potential as a therapeutic target. While there is a clear physiological equilibrium between reactive oxygen species (ROS) and antioxidants essential for many cellular functions, excessive levels of ROS lead to vascular cell impairment with decreased nitric oxide (NO) availability and vasoconstriction, which promotes HTN. On the other hand, transcription factors such as nuclear factor erythroid factor 2-related factor 2 (Nrf2) mediate antioxidant response pathways and maintain cellular reduction-oxidation homeostasis, exerting protective effects. In this review, we describe the relationship between OS and hypertension-induced endothelial dysfunction and the involvement and therapeutic potential of Nrf2 in HTN.

COVID-19: A Redox Disease-What a Stress Pandemic Can Teach Us About Resilience and What We May Learn from the Reactive Species Interactome About Its Treatment

Significance: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus causing coronavirus disease 2019 (COVID-19), affects every aspect of human life by challenging bodily, socioeconomic, and political systems at unprecedented levels. As vaccines become available, their distribution, safety, and efficacy against emerging variants remain uncertain, and specific treatments are lacking. Recent Advances: Initially affecting the lungs, COVID-19 is a complex multisystems disease that disturbs the whole-body redox balance and can be long-lasting (Long-COVID). Numerous risk factors have been identified, but the reasons for variations in susceptibility to infection, disease severity, and outcome are poorly understood. The reactive species interactome (RSI) was recently introduced as a framework to conceptualize how cells and whole organisms sense, integrate, and accommodate stress. Critical Issues: We here consider COVID-19 as a redox disease, offering a holistic perspective of its effects on the human body, considering the vulnerability of complex interconnected systems with multiorgan/multilevel interdependencies. Host/viral glycan interactions underpin SARS-CoV-2's extraordinary efficiency in gaining cellular access, crossing the epithelial/endothelial barrier to spread along the vascular/lymphatic endothelium, and evading antiviral/antioxidant defences. An inflammation-driven "oxidative storm" alters the redox landscape, eliciting epithelial, endothelial, mitochondrial, metabolic, and immune dysfunction, and coagulopathy. Concomitantly reduced nitric oxide availability renders the sulfur-based redox circuitry vulnerable to oxidation, with eventual catastrophic failure in redox communication/regulation. Host nutrient limitations are crucial determinants of resilience at the individual and population level. Future Directions: While inflicting considerable damage to health and well-being, COVID-19 may provide the ultimate testing ground to improve the diagnosis and treatment of redox-related stress diseases. "Redox phenotyping" of patients to characterize whole-body RSI status as the disease progresses may inform new therapeutic approaches to regain redox balance, reduce mortality in COVID-19 and other redox diseases, and provide opportunities to tackle Long-COVID. Antioxid. Redox Signal. 35, 1226-1268.

Comparative study of the effects of cigarette smoke versus next generation tobacco and nicotine product extracts on endothelial function

Tobacco smoking and hemodynamic forces are key stimuli for the development of endothelial dysfunction. As an alternative to smoking, next generation tobacco and nicotine products (NGP) are now widely used. However, little is known about their potential pro-inflammatory and atherogenic effects on the endothelium. In this study, we analyzed key parameters of endothelial function after exposure to aqueous smoke extracts (AqE) of a heated tobacco product (HTP), an electronic cigarette (e-cig), a conventional cigarette (3R4F) and pure nicotine. All experiments were performed under atheroprotective high laminar or atherogenic low flow with primary human endothelial cells. Treatment with 3R4F, but not alternative smoking products, reduced endothelial cell viability and wound healing capability via the PI3K/AKT/eNOS(NOS3) pathway. Laminar flow delayed detrimental effects on cell viability by 3R4F treatment. 3R4F stimulation led to activation of NRF2 antioxidant defense system at nicotine concentrations ≥0.56 μg/ml and increased expression of its target genes HMOX1 and NQO1. Treatment with HTP revealed an induction of HMOX1 and NQO1 at dosages with ≥1.68 μg/ml nicotine, whereas e-cig and nicotine exposure had no impact. Analyses of pro-inflammatory genes revealed an increased ICAM1 expression under 3R4F treatment. 3R4F reduced VCAM1 expression in a dose-dependent manner; HTP treatment had similar but milder effects; e-cig and nicotine treatment had no impact. SELE expression was induced by 3R4F under static conditions. High laminar flow prevented this upregulation. Stimulation with laminar flow led to downregulation of CCL2 (MCP-1). From this downregulated level, only 3R4F increased CCL2 expression at higher concentrations. Finally, under static conditions, all components increased adhesion of monocytes to endothelial cells. Interestingly, only stimulation with 3R4F revealed increased monocyte adhesion under atherosclerosis-prone low flow. In conclusion, all product categories activated anti-oxidative or pro-inflammatory patterns. NGP responses were typically lower than in 3R4F exposed cells. Also, 3R4F stimulation led to an impaired endothelial wound healing and induced a pro-inflammatory phenotype compared to NGP treatment.

Coronary Large Conductance Ca2+-Activated K+ Channel Dysfunction in Diabetes Mellitus

Diabetes mellitus (DM) is an independent risk of macrovascular and microvascular complications, while cardiovascular diseases remain a leading cause of death in both men and women with diabetes. Large conductance Ca2+-activated K+ (BK) channels are abundantly expressed in arteries and are the key ionic determinant of vascular tone and organ perfusion. It is well established that the downregulation of vascular BK channel function with reduced BK channel protein expression and altered intrinsic BK channel biophysical properties is associated with diabetic vasculopathy. Recent efforts also showed that diabetes-associated changes in signaling pathways and transcriptional factors contribute to the downregulation of BK channel expression. This manuscript will review our current understandings on the molecular, physiological, and biophysical mechanisms that underlie coronary BK channelopathy in diabetes mellitus.

ZNF416 is a pivotal transcriptional regulator of fibroblast mechanoactivation

Matrix stiffness is a central regulator of fibroblast function. However, the transcriptional mechanisms linking matrix stiffness to changes in fibroblast phenotype are incompletely understood. Here, we evaluated the effect of matrix stiffness on genome-wide chromatin accessibility in freshly isolated lung fibroblasts using ATAC-seq. We found higher matrix stiffness profoundly increased global chromatin accessibility relative to lower matrix stiffness, and these alterations were in close genomic proximity to known profibrotic gene programs. Motif analysis of these regulated genomic loci identified ZNF416 as a putative mediator of fibroblast stiffness responses. Genome occupancy analysis using ChIP-seq confirmed that ZNF416 occupies a broad range of genes implicated in fibroblast activation and tissue fibrosis, with relatively little overlap in genomic occupancy with other mechanoresponsive and profibrotic transcriptional regulators. Using loss- and gain-of-function studies, we demonstrated that ZNF416 plays a critical role in fibroblast proliferation, extracellular matrix synthesis, and contractile function. Together, these observations identify ZNF416 as novel mechano-activated transcriptional regulator of fibroblast biology.

Glycocalyx sialic acids regulate Nrf2-mediated signaling by fluid shear stress in human endothelial cells

Activation of the nuclear factor erythroid 2-related factor 2 (Nrf2) pathway is critical for vascular endothelial redox homeostasis in regions of high, unidirectional shear stress (USS), however the underlying mechanosensitive mediators are not fully understood. The endothelial glycocalyx is disrupted in arterial areas exposed to disturbed blood flow that also exhibit enhanced oxidative stress leading to atherogenesis. We investigated the contribution of glycocalyx sialic acids (SIA) to Nrf2 signaling in human endothelial cells (EC) exposed to atheroprotective USS or atherogenic low oscillatory shear stress (OSS). Cells exposed to USS exhibited a thicker glycocalyx and enhanced turnover of SIA which was reduced in cells cultured under OSS. Physiological USS, but not disturbed OSS, enhanced Nrf2-mediated expression of antioxidant enzymes, which was attenuated following SIA cleavage with exogenous neuraminidase. SIA removal disrupted kinase signaling involved in the nuclear accumulation of Nrf2 elicited by USS and promoted mitochondrial reactive oxygen species accumulation. Notably, knockdown of the endogenous sialidase NEU1 potentiated Nrf2 target gene expression, directly implicating SIA in regulation of Nrf2 signaling by USS. In the absence of SIA, deficits in Nrf2 responses to physiological flow were also associated with a pro-inflammatory EC phenotype. This study demonstrates that the glycocalyx modulates endothelial redox state in response to shear stress and provides the first evidence of an atheroprotective synergism between SIA and Nrf2 antioxidant signaling. The endothelial glycocalyx therefore represents a potential therapeutic target against EC dysfunction in cardiovascular disease and redox dyshomeostasis in ageing.

mTORC1 (Mechanistic Target of Rapamycin Complex 1) Signaling in Endothelial and Smooth Muscle Cells Is Required for Vascular Function

mTORC1 (Mechanistic target of rapamycin complex 1) serves as a molecular hub and intracellular energy sensor that regulate various cellular processes. Emerging evidence points to mTORC1 signaling as a critical regulator of cardiovascular function with implications for cardiovascular disease. Here, we show that selective disruption of mTORC1, through conditional Raptor gene deletion, in endothelial or smooth muscle cells alter vascular function. Endothelial cell-specific Raptor deletion results in reduced relaxation responses evoked by acetylcholine in the aorta but not in the mesenteric artery. Of note, endothelial-specific Raptor deletion did not affect endothelial-independent vasorelaxation nor the contractile responses of the aorta or mesenteric artery. Interestingly, endothelial Raptor haploinsufficiency did not alter vascular endothelial function but attenuated the endothelial dysfunction evoked by angiotensin II. Smooth muscle cell-specific conditional deletion of Raptor reduces both endothelial- and smooth muscle-dependent relaxation responses as well as receptor-dependent and -independent contractility in the aorta. This was associated with activation of autophagy signaling. Notably, the changes in vascular function evoked by endothelial and smooth muscle Raptor deletion were independent of changes in blood pressure and heart rate. Together, these data suggest that vascular mTORC1 signaling is a critical regulator of vascular endothelial and smooth muscle function. mTORC1 signaling may represent a potential target for the treatment of vascular diseases associated with altered mTORC1 activity.

Therapeutic Potential of Hydroxysafflor Yellow A on Cardio-Cerebrovascular Diseases

The incidence rate of cardio-cerebrovascular diseases (CCVDs) is increasing worldwide, causing an increasingly serious public health burden. The pursuit of new promising treatment options is thus becoming a pressing issue. Hydroxysafflor yellow A (HSYA) is one of the main active quinochalcone C-glycosides in the florets of Carthamus tinctorius L., a medical and edible dual-purpose plant. HSYA has attracted much interest for its pharmacological actions in treating and/or managing CCVDs, such as myocardial and cerebral ischemia, hypertension, atherosclerosis, vascular dementia, and traumatic brain injury, in massive preclinical studies. In this review, we briefly summarized the mode and mechanism of action of HSYA on CCVDs based on these preclinical studies. The therapeutic effects of HSYA against CCVDs were presumed to reside mostly in its antioxidant, anti-inflammatory, and neuroprotective roles by acting on complex signaling pathways.

Extracellular Vesicle-Mediated Vascular Cell Communications in Hypertension: Mechanism Insights and Therapeutic Potential of ncRNAs

Hypertension, a chronic and progressive disease, is an outstanding public health issue that affects nearly 40% of the adults worldwide. The increasing prevalence of hypertension is one of the leading causes of cardiovascular morbidity and mortality. Despite of the available treatment medications, an increasing number of hypertensive individuals continues to have uncontrolled blood pressure. In the vasculature, endothelial cells, vascular smooth muscle cells (VSMCs), and adventitial fibroblasts play a fundamental role in vascular homeostasis. The aberrant interactions between vascular cells might lead to hypertension and vascular remodeling. Identification of the precise mechanisms of vascular remodeling may be highly required to develop effective therapeutic approaches for hypertension. Recently, extracellular vesicle-mediated transfer of proteins or noncoding RNAs (ncRNAs) between vascular cells holds promise for the treatment of hypertension. Especially, extracellular vesicle-packaging ncRNAs have gained enormous attention of basic and clinical scientists because of their tremendous potential to act as novel clinical biomarkers and therapeutic targets of hypertension. Here we will discuss the current findings focusing on the emerging roles of extracellular vesicle-carrying ncRNAs in the pathologies of hypertension and its associated vascular remodeling. Furthermore, we will highlight the potential of extracellular vesicles and ncRNAs as biomarkers and therapeutic targets for hypertension. The future research directions on the challenges and perspectives of extracellular vesicles and ncRNAs in hypertensive vascular remodeling are also proposed.

Oxidative Stress and Microvessel Barrier Dysfunction

Clinical and experimental evidence indicate that increased vascular permeability contributes to many disease-associated vascular complications. Oxidative stress with increased production of reactive oxygen species (ROS) has been implicated in a wide variety of pathological conditions, including inflammation and many cardiovascular diseases. It is thus important to identify the role of ROS and their mechanistic significance in microvessel barrier dysfunction under pathological conditions. The role of specific ROS and their cross talk in pathological processes is complex. The mechanisms of ROS-induced increases in vascular permeability remain poorly understood. The sources of ROS in diseases have been extensively reviewed at enzyme levels. This review will instead focus on the underlying mechanisms of ROS release by leukocytes, the differentiate effects and signaling mechanisms of individual ROS on endothelial cells, pericytes and microvessel barrier function, as well as the interplay of reactive oxygen species, nitric oxide, and nitrogen species in ROS-mediated vascular barrier dysfunction. As a counter balance of excessive ROS, nuclear factor erythroid 2 related factor 2 (Nrf2), a redox-sensitive cell-protective transcription factor, will be highlighted as a potential therapeutic target for antioxidant defenses. The advantages and limitations of different experimental approaches used for the study of ROS-induced endothelial barrier function are also discussed. This article will outline the advances emerged mainly from in vivo and ex vivo studies and attempt to consolidate some of the opposing views in the field, and hence provide a better understanding of ROS-mediated microvessel barrier dysfunction and benefit the development of therapeutic strategies.

Unveiling the Role of Inflammation and Oxidative Stress on Age-Related Cardiovascular Diseases

The global population above 60 years has been growing exponentially in the last decades, which is accompanied by an increase in the prevalence of age-related chronic diseases, highlighting cardiovascular diseases (CVDs), such as hypertension, atherosclerosis, and heart failure. Aging is the main risk factor for these diseases. Such susceptibility to disease is explained, at least in part, by the increase of oxidative stress, in which it damages cellular components such as proteins, DNA, and lipids. In addition, the chronic inflammatory process in aging “inflammaging” also contributes to cell damage, creating a stressful environment which drives to the development of CVDs. Taken together, it is possible to identify the molecular connection between oxidative stress and the inflammatory process, especially by the crosstalk between the transcription factors Nrf-2 and NF-κB which are mediated by redox signalling and are involved in aging. Therapies that control this process are key targets in the prevention/combat of age-related CVDs. In this review, we show the basics of inflammation and oxidative stress, including the crosstalk between them, and the implications on age-related CVDs.

The Effects of Dietary Supplements that Overactivate the Nrf2/ARE System

Background:

Inflammation is one of the most misunderstood aspects of human health. People have been encouraged to eat foods that have a high antioxidant capacity, and in vitro tests for total antioxidant capacity emerged. They were based on measuring the destruction of oxidized test compounds in direct reactions with the antioxidants in foods. Many dietary supplements arrived in the market. They contained purified antioxidants, such as resveratrol and EGCG that were and still are widely assumed by many to be quite healthy at any dose.

Methods:

The literature on inflammation and the Nrf2/ARE antioxidant system was searched systematically. Articles from prestigious, peer-reviewed journals were obtained and read. The information obtained from them was used to write this review article.

Results:

Over 150 articles and books were read. The information obtained from them showed that very few dietary antioxidants exert their effects by reacting directly with Reactive Oxygen and Nitrogen Species (RONS). Instead, most of the effective antioxidants activate the endogenous Nrf2/ARE antioxidant system. This helps prevent smoldering inflammation and the diseases that it can cause. However, when overactivated or activated constitutively, the Nrf2/ARE antioxidant system can cause some of these diseases, including many types of multidrug resistant cancer, autoimmune, neurodegenerative and cardiovascular diseases.

Conclusion:

Even though green tea, as well as many fruits, vegetables and spices are quite healthy, dietary supplements that deliver much higher doses of antioxidants may not be. People who are diagnosed with cancer and plan to start chemotherapy and/or radiotherapy should probably avoid such supplements. This is because multidrug resistant tumors can hijack and overactivate the Nrf2/ARE antioxidant system.

MnTE-2-PyP, a manganese porphyrin, reduces cytotoxicity caused by irradiation in a diabetic environment through the induction of endogenous antioxidant defenses

Radiation is a common anticancer therapy for many cancer patients, including prostate cancer. Diabetic prostate cancer patients suffer from increased lymph node metastasis, tumor recurrence and decreased survival as compared to non-diabetic prostate cancer patients. These patients are also at increased risk for enhanced radiation-induced normal tissue damage such as proctitis. Diabetics are oxidatively stressed and radiation causes additional oxidative damage. We and others have reported that, MnTE-2-PyP, a manganese porphyrin, protects normal prostate tissue from radiation damage. We have also reported that, in an in vivo mouse model of prostate cancer, MnTE-2-PyP decreases tumor volume and increases survival of the mice. In addition, MnTE-2-PyP has also been shown to reduce blood glucose and inhibits pro-fibrotic signaling in a diabetic model. Therefore, to investigate the role of MnTE-2-PyP in normal tissue protection in an irradiated diabetic environment, we have treated human prostate fibroblast cells with MnTE-2-PyP in an irradiated hyperglycemic environment. This study revealed that hyperglycemia causes increased cell death after radiation as compared to normo-glycemia. MnTE-2-PyP protects against hyperglycemia-induced cell death after radiation. MnTE-2-PyP decreases expression of NOX4 and α-SMA, one of the major oxidative enzymes and pro-fibrotic molecules respectively. MnTE-2-PyP obstructs NF-κB activity by decreasing DNA binding of the p50-p50 homodimer in the irradiated hyperglycemic environment. MnTE-2-PyP increases NRF2 mediated cytoprotection by increasing NRF2 protein expression and DNA binding. Therefore, we are proposing that, MnTE-2-PyP protects fibroblasts from irradiation and hyperglycemia damage by enhancing the NRF2- mediated pathway in diabetic prostate cancer patients, undergoing radiotherapy.

Transcription Factor KLF2 and Its Role in the Regulation of Inflammatory Processes

KLF2 is a member of the Krüppel-like transcription factor family of proteins containing highly conserved DNA-binding zinc finger domains. KLF2 participates in the differentiation and regulation of the functional activity of monocytes, T lymphocytes, adipocytes, and vascular endothelial cells. The activity of KLF2 is controlled by several regulatory systems, including the MEKK2,3/MEK5/ERK5/MEF2 MAP kinase cascade, Rho family G-proteins, histone acetyltransferases CBP and p300, and histone deacetylases HDAC4 and HDAC5. Activation of KLF2 in endothelial cells induces eNOS expression and provides vasodilatory effect. Many KLF2-dependent genes participate in the suppression of blood coagulation and aggregation of T cells and macrophages with the vascular endothelium, thereby preventing atherosclerosis progression. KLF2 can have a dual effect on the gene transcription. Thus, it induces expression of multiple genes, but suppresses transcription of NF-κB-dependent genes. Transcription factors KLF2 and NF-κB are reciprocal antagonists. KLF2 inhibits induction of NF-κB-dependent genes, whereas NF-κB downregulates KLF2 expression. KLF2-mediated inhibition of NF-κB signaling leads to the suppression of cell response to the pro-inflammatory cytokines IL-1β and TNFα and results in the attenuation of inflammatory processes.

The protective effects of GLP-1 receptor agonist lixisenatide on oxygen-glucose deprivation/reperfusion (OGD/R)-induced deregulation of endothelial tube formation

Acute myocardial infarction (AMI) is a complication of atherosclerosis that takes place in coronary arteries. Cardiac endothelial cells play a significant role in the pathogenesis of AMI. Oxygen-glucose deprivation/reperfusion (OGD/R) is widely used as a model to simulate AMI in vitro. Recently, antidiabetic GLP-1 receptor agonists have been shown to exert pleiotropic effects that modulate cardiovascular complications. In this study, we investigated the vascular effect of lixisenatide. We show that pre-treatment of endothelial cells with lixisenatide protected them from OGD/R-induced cytotoxicity and improved their viability. Pre-treatment with lixisenatide ameliorated OGD/R-induced ROS accumulation and disturbed endothelial tube formation. At the molecular level, lixisenatide mitigated OGD/R-induced reduced eNOS expression and NO production but further promoted the expression of the anti-oxidant regulators Nrf2 and HO-1. Mechanistically, we confirmed that the PI3K/Akt pathway is essential for mediating the effects of lixisenatide, and blockage of PI3K/Akt using the inhibitor LY294002 abolished the ameliorative effect of lixisenatide on ROS production and impaired tube formation. These data indicate that lixisenatide possesses a beneficial effect on the vasculature in a model of ischemia-induced endothelial injury. We conclude that the GLP-1 receptor agonist lixisenatide has pleiotropic properties that can modulate vascular function independent of its anti-glycemic effect.

Acute myocardial infarction (AMI) is a complication of atherosclerosis that takes place in coronary arteries.

Cardamonin inhibits breast cancer growth by repressing HIF-1α-dependent metabolic reprogramming

Background

Cardamonin, a chalcone isolated from Alpiniae katsumadai, has anti-inflammatory and anti-tumor activities. However, the molecular mechanism by which cardamonin inhibits breast cancer progression largely remains to be determined.

Methods

CCK-8 and Hoechst 33258 staining were used to detect cell growth and apoptosis, respectively. HIF-1α driven transcription was measured by luciferase reporter assay. Glucose uptake and lactate content were detected with 2-NBDG and L-Lactate Assay Kit. Cell metabolism assays were performed on Agilent’s Seahorse Bioscience XF96 Extracellular Flux Analyzer. Mitochondrial membrane potential was measured with JC-1 probe. DCFH-DA was used to measure ROS level. Protein expression was detected by western blotting assay. Immunohistochemistry was performed to measure the expression of HIF-1α, LDHA and CD31 in tumor tissues.

Results

Cardamonin inhibited growth of the triple negative breast cancer cell line MDA-MB-231 in vitro and in vivo by suppressing HIF-1α mediated cell metabolism. Cardamonin inhibited the expression of HIF-1α at mRNA and protein levels by repressing the mTOR/p70S6K pathway, and subsequently enhanced mitochondrial oxidative phosphorylation and induced reactive oxygen species (ROS) accumulation. We also found that cardamonin inhibited the Nrf2-dependent ROS scavenging system which further increased intracellular ROS levels. Eventually, accumulation of the intracellular ROS induced apoptosis in breast cancer cells. In addition, cardamonin treatment reduced glucose uptake as well as lactic acid production and efflux, suggesting its function in repressing the glycolysis process.

Conclusions

These results reveal novel function of cardamonin in modulating cancer cell metabolism and suppressing breast cancer progression, and suggest its potential for breast cancer treatment.

Electronic supplementary material

The online version of this article (10.1186/s13046-019-1351-4) contains supplementary material, which is available to authorized users.

Protection of Male Rat Offspring against Hypertension Programmed by Prenatal Dexamethasone Administration and Postnatal High-Fat Diet with the Nrf2 Activator Dimethyl Fumarate during Pregnancy

Hypertension can originate from early-life exposure to oxidative stress. As reported, dimethyl fumarate (DMF) activates nuclear factor erythroid-derived 2-related factor 2 (Nrf2) and protects against oxidative stress damage. We examined whether maternal DMF therapy protects adult offspring against hypertension programmed by prenatal dexamethasone (DEX) and postnatal high-fat (HF) diet exposure. We examined male Sprague Dawley rat offspring at 4 months of age from five groups (n = 11-13/group): control, DEX (0.1mg/kg i.p. from gestational day 16 to 22), HF (D12331 diet from weaning to 16 weeks of age), DEX+HF, and DEX+HF+DMF (50mg/kg/day via gastric gavage for 3 weeks during pregnancy). Maternal DMF therapy prevented male offspring against hypertension programmed by combined DEX and HF exposures. The protective effects of maternal DMF include reduced oxidative stress, decreased plasma asymmetric dimethylarginine (ADMA) levels, downregulated the renin-angiotensin system (i.e. Ren, Agt, Ace, and Agtr1a), increased renal protein levels of certain nutrient-sensing signals, and promoted autophagy. In conclusion, maternal Nrf2 activation by DMF protects male adult offspring against hypertension programmed by combined DEX and HF exposures. Our results cast a new light on the therapeutic potential of targeting Nrf2 signaling pathway as reprogramming strategies to prevent programmed hypertension in children exposed to antenatal corticosteroids and postnatally excessive consumption of fat.

Magnesium lithospermate B protects the endothelium from inflammation-induced dysfunction through activation of Nrf2 pathway

Magnesium lithospermate B (MLB) is an active component of Salvia miltiorrhiza Radix, a traditional Chinese herb used in treating cardiovascular diseases. In this study, we investigated the protective effects of MLB against inflammation-induced endothelial dysfunction in vitro and in vivo, and the underlying mechanisms. Endothelial dysfunction was induced in human dermal microvascular endothelial cells (HMEC-1) in vitro by lipopolysaccharide (LPS, 1 μg/mL). We showed that pretreatment with MLB (10-100 μM) dose-dependently inhibited LPS-induced upregulation of inflammatory cytokines ICAM1, VCAM1, and TNFα, which contributed to reduced leukocytes adhesion and attenuation of endothelial hyperpermeability in HMEC-1 cells. SD rats were injected with LPS (10 mg/kg, ip) to induce endothelial dysfunction in vivo. We showed that pretreatment with MLB (25-100 mg/kg, ip) dose-dependently restored LPS-impaired endothelial-dependent vasodilation in superior mesenteric artery (SMA), attenuated leukocyte adhesion in mesenteric venules and decreased vascular leakage in the lungs. We further elucidated the mechanisms underlying the protective effects of MLB, and revealed that MLB pretreatment inhibited NF-κB activation through inhibition of IκBα degradation and subsequent phosphorylation of NF-κB p65 in vitro and in vivo. In HMEC-1 cells, MLB pretreatment activated the nuclear factor erythroid-2-related factor 2 (Nrf2) pathway. Knockdown of Nrf2 with siRNA abolished the inhibitory effects of MLB on IκBα degradation and ICAM1 up-regulation, which were mimicked by PKC inhibition (Gö6983) or PI3K/Akt inhibition (LY294002). In summary, our results demonstrate that MLB inhibits NF-κB activation through PKC- and PI3K/Akt-mediated Nrf2 activation in HMEC-1 cells and protects against LPS-induced endothelial dysfunction in murine model of acute inflammation.

Astragaloside IV Exerts a Myocardial Protective Effect against Cardiac Hypertrophy in Rats, Partially via Activating the Nrf2/HO-1 Signaling Pathway

Previous evidence suggested that astragaloside IV (ASIV) had a cardioprotective effect, but the potential mechanisms were undetermined. This study is aimed at validating the prevention of cardiac hypertrophy in chronic heart failure (CHF) rats and hypertrophy in H9c2 cardiomyocytes by ASIV and at exploring the potential mechanism involved. CHF rat models of abdominal aortic constriction (AAC) were used with the aim of determining the protective effect of ASIV in cardiac hypertrophy in the rats. We proved that ASIV could attenuate cardiac hypertrophy by improving left ventricular function and structure and showed that the expression of nuclear factor-erythroid 2-related factor 2 (Nrf2) and its downstream gene heme oxygenase-1 (HO-1) increased in the high-dose ASIV intervention group. To further investigate the specific mechanism of ASIV, we hypothesized that ASIV might prevent cardiac hypertrophy via activating the Nrf2/HO-1 signaling pathway. We established a cardiomyocyte hypertrophy model induced by angiotensin II (Ang II), which was then transfected with Nrf2 shRNA, to knock down the expression of the Nrf2 gene. We found that the protective effect of ASIV against Ang II-induced cardiomyocyte hypertrophy was abolished in the Nrf2 shRNA transfection group, ultimately aggravating cardiomyocyte hypertrophy induced by Ang II, and it is possible that oxidative stress may be involved in this process. Our results demonstrated that ASIV improved cardiac function and inhibited cardiac hypertrophy by upregulating Nrf2, and this effect was partially achieved by stimulating the Nrf2/HO-1 signaling pathway, suggesting that ASIV could have therapeutic potential for the treatment of cardiac hypertrophy and CHF.

Organ-Specific Mechanisms of Transendothelial Neutrophil Migration in the Lung, Liver, Kidney, and Aorta

Immune responses are dependent on the recruitment of leukocytes to the site of inflammation. The classical leukocyte recruitment cascade, consisting of capture, rolling, arrest, adhesion, crawling, and transendothelial migration, is thoroughly studied but mostly in model systems, such as the cremasteric microcirculation. This cascade paradigm, which is widely accepted, might be applicable to many tissues, however recruitment mechanisms might substantially vary in different organs. Over the last decade, several studies shed light on organ-specific mechanisms of leukocyte recruitment. An improved awareness of this matter opens new therapeutic windows and allows targeting inflammation in a tissue-specific manner. The aim of this review is to summarize the current understanding of the leukocyte recruitment in general and how this varies in different organs. In particular we focus on neutrophils, as these are the first circulating leukocytes to reach the site of inflammation. Specifically, the recruitment mechanism in large arteries, as well as vessels in the lungs, liver, and kidney will be addressed.

Schisandrin B protects against angiotensin II-induced endotheliocyte deficits by targeting Keap1 and activating Nrf2 pathway

Introduction

Schisandrin B (SchB), the main active constituent in Schisandra chinensis, has antioxidant activities. Endothelial dysfunction leads to various cardiovascular diseases. Oxidative stress is a crucial pathophysiological mechanism underpinning endothelial dysfunction.

Methods

We elucidated the role and underlying mechanisms of SchB in angiotensin II-induced rat aortic endothelial-cell deficits and explored targets of SchB through siRNA analysis and molecular docking. We measured apoptosis by TUNEL and oxidative stress by dihydroethidium (DHE) and 2’,7’ –dichlorofluorescin diacetate (DCF) staining.

Results

Our results demonstrated that SchB significantly ameliorated oxidative stress, mitochondrial membrane-potential depolarization and apoptosis in angiotensin II-challenged rat aortic endothelial cells. We further discovered that these antioxidative effects of SchB were mediated through induction of Nrf2. Importantly, using molecular docking and molecular dynamic simulation, we identified that Keap1, an adaptor for the degradation of Nrf2, was a target of SchB.

Conclusion

These findings support the potential use of SchB as a Keap1 inhibitor for attenuating oxidative stress, and Keap1 might serve as a therapeutic target in the treatment of cardiovascular diseases.

Small diameter helical vascular scaffolds support endothelial cell survival

There is an acute clinical need for small-diameter vascular grafts as a treatment option for cardiovascular disease. Here, we used an intelligent design system to recreate the natural structure and hemodynamics of small arteries. Nano-fibrous tubular scaffolds were fabricated from blends of polyvinyl alcohol and gelatin with inner helices to allow a near physiological spiral flow profile, using the electrospinning technique. Human coronary artery endothelial cells (ECs) were seeded on the inner surface and their viability, distribution, gene expression of mechanosensitive and adhesion molecules compared to that in conventional scaffolds, under static and flow conditions. We show significant improvement in cell distribution in helical vs. conventional scaffolds (94% ± 9% vs. 82% ± 7.2%; P < 0.05) with improved responsiveness to shear stress and better ability to withhold physiological pressures. Our helical vascular scaffold provides an improved niche for EC growth and may be attractive as a potential small diameter vascular graft.

HIV-associated cardiovascular disease: importance of platelet activation and cardiac fibrosis in the setting of specific antiretroviral therapies

HIV infection is a risk factor for cardiovascular disease (CVD). This risk is accentuated by certain combination antiretroviral therapies (cARTs), independent of their effects on lipid metabolism and insulin sensitivity. We sought to define potential mechanisms for this association through systematic review of clinical and preclinical studies of CVD in the setting of HIV/cART from the English language literature from 1989 to March 2018. We used PubMed, Web of Knowledge and Google Scholar, and conference abstracts for the years 2015-March 2018. We uncovered three themes: (1) a critical role for the HIV protease inhibitor (PI) ritonavir and certain other PI-based regimens. (2) The importance of platelet activation. Virtually all PIs, and one nucleoside reverse transcriptase inhibitor, abacavir, activate platelets, but a role for this phenomenon in clinical CVD risk may require additional postactivation processes, including: release of platelet transforming growth factor-β1; induction of oxidative stress with production of reactive oxygen species from vascular cells; suppression of extracellular matrix autophagy; and/or sustained proinflammatory signalling, leading to cardiac fibrosis and dysfunction. Cardiac fibrosis may underlie an apparent shift in the character of HIV-linked CVD over the past decade from primarily left ventricular systolic to diastolic dysfunction, possibly driven by cART. (3) Recognition of the need for novel interventions. Switching from cART regimens based on PIs to contemporary antiretroviral agents such as the integrase strand transfer inhibitors, which have not been linked to clinical CVD, may not mitigate CVD risk assumed under prior cART. In conclusion, attention to the effects of specific antiretroviral drugs on platelet activation and related profibrotic signalling pathways should help: guide selection of appropriate anti-HIV therapy; assist in evaluation of CVD risk related to novel antiretrovirals; and direct appropriate interventions.

Getting the Message? Native Reactive Electrophiles Pass Two Out of Three Thresholds to be Bona Fide Signaling Mediators

Precision cell signaling activities of reactive electrophilic species (RES) are arguably among the most poorly-understood means to transmit biological messages. Latest research implicates native RES to be a chemically-distinct subset of endogenous redox signals that influence cell decision making through non-enzyme-assisted modifications of specific proteins. Yet, fundamental questions remain regarding the role of RES as bona fide second messengers. Here, we lay out three sets of criteria we feel need to be met for RES to be considered as true cellular signals that directly mediate information transfer by modifying "first-responding" sensor proteins. We critically assess the available evidence and define the extent to which each criterion has been fulfilled. Finally, we offer some ideas on the future trajectories of the electrophile signaling field taking inspiration from work that has been done to understand canonical signaling mediators. Also see the video abstract here: https://youtu.be/rG7o0clVP0c.

Astaxanthin Induces the Nrf2/HO-1 Antioxidant Pathway in Human Umbilical Vein Endothelial Cells by Generating Trace Amounts of ROS

Astaxanthin is a powerful antioxidant that possesses potent protective effects against various human diseases and physiological disorders. However, the mechanisms underlying its antioxidant functions in cells are not fully understood. In the present study, the effects of astaxanthin on reactive oxygen species (ROS) production and antioxidant enzyme activity, as well as mitogen-activated protein kinases (MAPKs), phosphatidylinositol 3-kinase (PI3K)/Akt, and the nuclear factor erythroid 2-related factor 2 (Nrf-2)/heme oxygenase-1 (HO-1) pathways in human umbilical vein endothelial cells (HUVECs), were examined. It was shown that astaxanthin (0.1, 1, and 10 μM) induced ROS production by 9.35%, 14.8%, and 18.06% compared to control, respectively, in HUVECs. In addition, astaxanthin increased the mRNA levels of phase II enzymes HO-1 and also promoted GSH-Px enzyme activity. Furthermore, we observed ERK phosphorylation, nuclear translocation of Nrf-2, and activation of antioxidant response element-driven luciferase activity upon astaxanthin treatment. Knockdown of Nrf-2 by small interfering RNA inhibited HO-1 mRNA expression by 60%, indicating that the Nrf-2/ARE signaling pathway is activated by astaxanthin. Our results suggest that astaxanthin activates the Nrf-2/HO-1 antioxidant pathway by generating small amounts of ROS.

KRIT1 loss-of-function induces a chronic Nrf2-mediated adaptive homeostasis that sensitizes cells to oxidative stress: Implication for Cerebral Cavernous Malformation disease

KRIT1 (CCM1) is a disease gene responsible for Cerebral Cavernous Malformations (CCM), a major cerebrovascular disease of proven genetic origin affecting 0.3-0.5% of the population. Previously, we demonstrated that KRIT1 loss-of-function is associated with altered redox homeostasis and abnormal activation of the redox-sensitive transcription factor c-Jun, which collectively result in pro-oxidative, pro-inflammatory and pro-angiogenic effects, suggesting a novel pathogenic mechanism for CCM disease and raising the possibility that KRIT1 loss-of-function exerts pleiotropic effects on multiple redox-sensitive mechanisms. To address this possibility, we investigated major redox-sensitive pathways and enzymatic systems that play critical roles in fundamental cytoprotective mechanisms of adaptive responses to oxidative stress, including the master Nrf2 antioxidant defense pathway and its downstream target Glyoxalase 1 (Glo1), a pivotal stress-responsive defense enzyme involved in cellular protection against glycative and oxidative stress through the metabolism of methylglyoxal (MG). This is a potent post-translational protein modifier that may either contribute to increased oxidative molecular damage and cellular susceptibility to apoptosis, or enhance the activity of major apoptosis-protective proteins, including heat shock proteins (Hsps), promoting cell survival. Experimental outcomes showed that KRIT1 loss-of-function induces a redox-sensitive sustained upregulation of Nrf2 and Glo1, and a drop in intracellular levels of MG-modified Hsp70 and Hsp27 proteins, leading to a chronic adaptive redox homeostasis that counteracts intrinsic oxidative stress but increases susceptibility to oxidative DNA damage and apoptosis, sensitizing cells to further oxidative challenges. While supporting and extending the pleiotropic functions of KRIT1, these findings shed new light on the mechanistic relationship between KRIT1 loss-of-function and enhanced cell predisposition to oxidative damage, thus providing valuable new insights into CCM pathogenesis and novel options for the development of preventive and therapeutic strategies.

Astragaloside IV protects blood-brain barrier integrity from LPS-induced disruption via activating Nrf2 antioxidant signaling pathway in mice

Endothelial cells of cerebral microvessels are one of the components of blood-brain-barrier (BBB), which are connected by tight junctions (TJs). BBB disruption in cerebral diseases such as ischemic stroke, Alzhemer's disease, multiple sclerosis and traumatic brain injury is implicated to exacerbate the disease progression. Astragaloside IV (ASIV) isolated from Astragalus membranaceus prevents BBB breakdown in rodents induced with cerebral edema and experimental autoimmune encephalomyelitis. However, its underlying molecular mechanism has not been elucidated yet. In present study, ASIV was found to prevent the leakage of BBB in LPS-induced mice, which was accompanied with increased zo-1 and occludin but reduced VCAM-1 in brain microvessels. Similarly, in brain endothelial cell line bEnd.3 cells, ASIV mitigated the increased permeability induced by LPS, as evidenced by increased TEER and reduced sodium fluorescein extravasation. ASIV also enhanced the expression of TJ proteins such as zo-1, occludin and claudin-5 in LPS stimulated bEnd.3 cells. Meanwhile, it inhibited the inflammatory responses and prevented the monocyte adhesion onto bEnd.3 cells upon LPS stimulation. Further study disclosed that ASIV could alleviate ROS level and activate Nrf2 antioxidant pathway in bEnd.3 cells. When Nrf2 was silenced, the protective effect of ASIV was abolished. In brain microvessels of LPS-induced mice, ASIV also enhanced the expression of Nrf2 antioxidant pathway related proteins. Collectively, our results demonstrated that ASIV protected the integrity of BBB in LPS-induced mice, the mechanism of which might be mediated via activating Nrf2 signaling pathway. The findings suggested that ASIV might be a potential neuroprotective drug acting on BBB.

Role of Platelet-Derived Transforming Growth Factor-β1 and Reactive Oxygen Species in Radiation-Induced Organ Fibrosis

SIGNIFICANCE

This review evaluates the role of platelet-derived transforming growth factor (TGF)-β1 in oxidative stress-linked pathologic fibrosis, with an emphasis on the heart and kidney, by using ionizing radiation as a clinically relevant stimulus. Current radiation-induced organ fibrosis interventions focus on pan-neutralization of TGF-β or the use of anti-oxidants and anti-proliferative agents, with limited clinical efficacy. Recent Advances: Pathologic fibrosis represents excessive accumulation of collagen and other extracellular matrix (ECM) components after dysregulation of a balance between ECM synthesis and degradation. Targets based on endogenous carbon monoxide (CO) pathways and the use of redox modulators such as N-acetylcysteine present promising alternatives to current therapeutic regimens.

CRITICAL ISSUES

Ionizing radiation leads to direct DNA damage and generation of reactive oxygen species (ROS), with TGF-β1 activation via ROS, thrombin generation, platelet activation, and pro-inflammatory signaling promoting myofibroblast accumulation and ECM production. Feed-forward loops, as TGF-β1 promotes ROS, amplify these profibrotic signals, and persistent low-grade inflammation insures their perpetuation. We highlight differential roles for platelet- versus monocyte-derived TGF-β1, establishing links between canonical and noncanonical TGF-β1 signaling pathways in relationship to macrophage polarization and autophagy, and define points where pharmacologic agents can intervene.

FUTURE DIRECTIONS

Additional studies are needed to understand mechanisms underlying the anti-fibrotic effects of current and proposed therapeutics, based on limiting platelet TGF-β1 activity, promotion of macrophage polarization, and facilitation of collagen autophagy. Models incorporating endogenous CO and selective TGF-β1 pathways that impact the initiation and progression of pathologic fibrosis, including nuclear factor erythroid 2-related factor (Nrf2) and redox, are of particular interest. Antioxid. Redox Signal. 27, 977-988.

The Role of Nrf2 in Cardiovascular Function and Disease

Free radicals, reactive oxygen/nitrogen species (ROS/RNS), hydrogen sulphide, and hydrogen peroxide play an important role in both intracellular and intercellular signaling; however, their production and quenching need to be closely regulated to prevent cellular damage. An imbalance, due to exogenous sources of free radicals and chronic upregulation of endogenous production, contributes to many pathological conditions including cardiovascular disease and also more general processes involved in aging. Nuclear factor erythroid 2-like 2 (NFE2L2; commonly known as Nrf2) is a transcription factor that plays a major role in the dynamic regulation of a network of antioxidant and cytoprotective genes, through binding to and activating expression of promoters containing the antioxidant response element (ARE). Nrf2 activity is regulated by many mechanisms, suggesting that tight control is necessary for normal cell function and both hypoactivation and hyperactivation of Nrf2 are indicated in playing a role in different aspects of cardiovascular disease. Targeted activation of Nrf2 or downstream genes may prove to be a useful avenue in developing therapeutics to reduce the impact of cardiovascular disease. We will review the current status of Nrf2 and related signaling in cardiovascular disease and its relevance to current and potential treatment strategies.

Cigarette smoke extract counteracts atheroprotective effects of high laminar flow on endothelial function

Tobacco smoking and hemodynamic forces are key stimuli in the development of endothelial dysfunction and atherosclerosis. High laminar flow has an atheroprotective effect on the endothelium and leads to a reduced response of endothelial cells to cardiovascular risk factors compared to regions with disturbed or low laminar flow. We hypothesize that the atheroprotective effect of high laminar flow could delay the development of endothelial dysfunction caused by cigarette smoking. Primary human endothelial cells were stimulated with increasing dosages of aqueous cigarette smoke extract (CSEaq). CSEaq reduced cell viability in a dose-dependent manner. The main mediator of cellular adaption to oxidative stress, nuclear factor erythroid 2-related factor 2 (NRF2) and its target genes heme oxygenase (decycling) 1 (HMOX1) or NAD(P)H quinone dehydrogenase 1 (NQO1) were strongly increased by CSEaq in a dose-dependent manner. High laminar flow induced elongation of endothelial cells in the direction of flow, activated the AKT/eNOS pathway, increased eNOS expression, phosphorylation and NO release. These increases were inhibited by CSEaq. Pro-inflammatory adhesion molecules intercellular adhesion molecule-1 (ICAM1), vascular cell adhesion molecule-1 (VCAM1), selectin E (SELE) and chemokine (C-C motif) ligand 2 (CCL2/MCP-1) were increased by CSEaq. Low laminar flow induced VCAM1 and SELE compared to high laminar flow. High laminar flow improved endothelial wound healing. This protective effect was inhibited by CSEaq in a dose-dependent manner through the AKT/eNOS pathway. Low as well as high laminar flow decreased adhesion of monocytes to endothelial cells. Whereas, monocyte adhesion was increased by CSEaq under low laminar flow, this was not evident under high laminar flow. This study shows the activation of major atherosclerotic key parameters by CSEaq. Within this process, high laminar flow is likely to reduce the harmful effects of CSEaq to a certain degree. The identified molecular mechanisms might be useful for development of alternative therapy concepts.

Thirty Years of Saying NO: Sources, Fate, Actions, and Misfortunes of the Endothelium-Derived Vasodilator Mediator

Endothelial cells control vascular tone by releasing nitric oxide (NO) produced by endothelial NO synthase. The activity of endothelial NO synthase is modulated by the calcium concentration and by post-translational modifications (eg, phosphorylation). When NO reaches vascular smooth muscle, soluble guanylyl cyclase is its primary target producing cGMP. NO production is stimulated by circulating substances (eg, catecholamines), platelet products (eg, serotonin), autacoids formed in (eg, bradykinin) or near (eg, adiponectin) the vascular wall and physical factors (eg, shear stress). NO dysfunction can be caused, alone or in combination, by abnormal coupling of endothelial cell membrane receptors, insufficient supply of substrate (l-arginine) or cofactors (tetrahydrobiopterin), endogenous inhibitors (asymmetrical dimethyl arginine), reduced expression/presence/dimerization of endothelial NO synthase, inhibition of its enzymatic activity, accelerated disposition of NO by reactive oxygen species and abnormal responses (eg, biased soluble guanylyl cyclase activity producing cyclic inosine monophosphate) of the vascular smooth muscle. Major culprits causing endothelial dysfunction, irrespective of the underlying pathological process (aging, obesity, diabetes mellitus, and hypertension), include stimulation of mineralocorticoid receptors, activation of endothelial Rho-kinase, augmented presence of asymmetrical dimethyl arginine, and exaggerated oxidative stress. Genetic and pharmacological interventions improve dysfunctional NO-mediated vasodilatations if protecting the supply of substrate and cofactors for endothelial NO synthase, preserving the presence and activity of the enzyme and reducing reactive oxygen species generation. Common achievers of such improvement include maintained levels of estrogens and increased production of adiponectin and induction of silent mating-type information regulation 2 homologue 1. Obviously, endothelium-dependent relaxations are not the only beneficial action of NO in the vascular wall. Thus, reduced NO-mediated responses precede and initiate the atherosclerotic process.

The nuclear factor (erythroid-derived 2)-like 2 (Nrf2) activator dh404 protects against diabetes-induced endothelial dysfunction

Background

Vascular dysfunction is a pivotal event in the development of diabetes-associated vascular disease. Increased inflammation and oxidative stress are major contributors to vascular dysfunction. Nrf2, a master regulator of several anti-oxidant genes and a suppressor of inflammatory NF-κB, has potential as a target to combat oxidative stress and inflammation. The aim of this study was to investigate the effects of a novel Nrf2 activator, the bardoxolone methyl derivative dh404, on endothelial function in vitro and in vivo.

Methods

dh404 at 3 mg/kg was administered to male Akita mice, an established diabetic mouse model of insulin insufficiency and hyperglycemia, from 6 weeks of age. At 26 weeks of age, vascular reactivity was assessed by wire myography, pro-inflammatory expression was assessed in the aortas by qRT-PCR and immunohistochemistry, and systemic and vascular oxidative stress measurements were determined. Additionally, studies in human aortic endothelial cells (HAECs) derived from normal and diabetic patients in the presence or absence of dh404 included assessment of pro-inflammatory genes by qRT-PCR and western blotting. Oxidative stress was assessed by three methods; L-012, DCFDA and amplex red. Static adhesion assays were performed to determine the leukocyte–endothelial interaction in the presence or absence of dh404.

Results

Dh404 significantly attenuated endothelial dysfunction in diabetic Akita mice characterized by reduced contraction in response to phenylephrine and the downregulation of inflammatory genes (VCAM-1, ICAM-1, p65, IL-1β) and pro-oxidant genes (Nox1 and Nox2). Furthermore, reduced systemic and vascular oxidative stress levels were observed in diabetic Akita mice. dh404 exhibited cytoprotective effects in diabetic HAECs in vitro, reflected by significant upregulation of Nrf2-responsive genes, NAD(P)H quinone oxidoreductase 1 (NQO1) and heme oxygenase-1 (HO-1), reduction of oxidative stress markers (O₂^·− and H₂O₂), inhibition of inflammatory genes (VCAM-1 and the p65 subunit of NF-κB) and attenuation of leukocyte–endothelial interactions (P < 0.05 for all in vitro and in vivo parameters; one or two-way ANOVA as appropriate with post hoc testing).

Conclusion

These studies demonstrate that upregulation of Nrf2 by dh404 represents a novel therapeutic strategy to limit diabetes-associated vascular injury.

Electronic supplementary material

The online version of this article (doi:10.1186/s12933-017-0513-y) contains supplementary material, which is available to authorized users.

Cigarette smoke extract profoundly suppresses TNFα-mediated proinflammatory gene expression through upregulation of ATF3 in human coronary artery endothelial cells

Endothelial dysfunction caused by the combined action of disturbed flow, inflammatory mediators and oxidants derived from cigarette smoke is known to promote coronary atherosclerosis and increase the likelihood of myocardial infarctions and strokes. Conversely, laminar flow protects against endothelial dysfunction, at least in the initial phases of atherogenesis. We studied the effects of TNFα and cigarette smoke extract on human coronary artery endothelial cells under oscillatory, normal laminar and elevated laminar shear stress for a period of 72 hours. We found, firstly, that laminar flow fails to overcome the inflammatory effects of TNFα under these conditions but that cigarette smoke induces an anti-oxidant response that appears to reduce endothelial inflammation. Elevated laminar flow, TNFα and cigarette smoke extract synergise to induce expression of the transcriptional regulator activating transcription factor 3 (ATF3), which we show by adenovirus driven overexpression, decreases inflammatory gene expression independently of activation of nuclear factor-κB. Our results illustrate the importance of studying endothelial dysfunction in vitro over prolonged periods. They also identify ATF3 as an important protective factor against endothelial dysfunction. Modulation of ATF3 expression may represent a novel approach to modulate proinflammatory gene expression and open new therapeutic avenues to treat proinflammatory diseases.