Flavonoids inhibit high glucose-induced up-regulation of ICAM-1 via the p38 MAPK pathway in human vein endothelial cells

Kaempferol protects gut-vascular barrier from high glucose-induced disorder via NF-κB pathway

Kaempferol is a natural edible flavonoid reported to treat high-fat diet-induced intestinal inflammation; however, the underlying molecular mechanisms remain unclear. This research aims to investigate the protective effect of kaempferol on the gut-vascular barrier (GVB) induced by high glucose and elucidate the underlying mechanism. Evans blue albumin efflux assay was used to test endothelial cell permeability. The results showed that kaempferol (50 μM) significantly reversed the high glucose-induced monolayer barrier permeability of rat intestinal microvascular endothelial cells (RIMVECs), while kaempferol significantly alleviated the high glucose-induced rarefication of the tight junction protein Claudin-5. Moreover, kaempferol also reduced high glucose-induced angiogenesis and cell migration via inhibiting the VEGFR2/p38 pathway. Kaempferol also protected against high glucose-induced overproduction of intercellular adhesion molecule (ICAM)-1 and vascular cell adhesion molecule (VCAM)-1 by inhibiting NF-κB p65 nuclear translocation. In addition, kaempferol had similar effects to the NF-κB inhibitor SN50 in reducing high glucose-induced ICAM-1 expression and endothelial barrier permeabilization. Our findings in part reveal the pathological mechanism of hyperglycemia-related gastrointestinal diseases and underlie the molecular mechanism of kaempferol in inhibiting bowel inflammation from a novel perspective.

Nanocurcumin Reduces High Glucose and Particulate Matter-Induced Endothelial Inflammation: Mitochondrial Function and Involvement of miR-221/222

Purpose

Particulate matter (PM) 2.5, harmful air pollutants, and diabetes are associated with high morbidity and mortality from cardiovascular disease (CVD). However, the molecular mechanisms underlying the combined effects of PM and diabetes on CVD remain unclear.

Methods

Endothelial cells (ECs) treated with high glucose (HG) and PM mimic hyperglycemia and air pollutant exposure in CVD. Endothelial inflammation was evaluated by Western blot and immunofluorescence of ICAM-1 expression and monocyte adhesion. The mechanisms underlying endothelial inflammation were elucidated through MitoSOX Red analysis, JC-1 staining, MitoTracker analysis, and Western blot analysis of mitochondrial fission-related, autophagy-related, and mitophagy-related proteins. Furthermore. nanocurcumin (NCur) pretreatment was used to test if it has a protective effect.

Results

ECs under co-exposure to HG and PM increased ICAM-1 expression and monocyte adhesion, whereas NCur pretreatment attenuated these changes and improved endothelial inflammation. PM exposure increased mitochondrial ROS levels, worsened mitochondrial membrane potential, promoted mitochondrial fission, induced mitophagy, and aggravated inflammation in HG-treated ECs, while NCur reversed these changes. Also, HG and PM-induced endothelial inflammation is through the JNK signaling pathway and miR-221/222 specifically targeting ICAM-1 and BNIP3. PM exposure also aggravated mitochondrial ROS levels, mitochondrial fission, mitophagy, and endothelial inflammation in STZ-induced hyperglycemic mice, whereas NCur attenuated these changes.

Conclusion

This study elucidated the mechanisms underlying HG and PM-induced endothelial inflammation in vitro and in vivo. HG and PM treatment increased mitochondrial ROS, mitochondrial fission, and mitophagy in ECs, whereas NCur reversed these conditions. In addition, miR-221/222 plays a role in the amelioration of endothelial inflammation through targeting Bnip3 and ICAM-1, and NCur pretreatment can modulate miR-221/222 levels. Therefore, NCur may be a promising approach to intervene in diabetes and air pollution-induced CVD.

Citrus flavonoids and adhesion molecules: Potential role in the management of atherosclerosis

Atherosclerosis as a chronic inflammatory disorder is accompanied with oxidative stress which causes a high morbidity and mortality. Adhesion molecules, including intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), P-selectin, and E-selectin, are amongst the most important contributors in atherosclerosis. In such cases, dietary interventions with functional foods containing natural antioxidant and anti-inflammatory constituents are of a great interest. Citrus fruits are rich sources of flavonoids as natural pigments with potent antioxidant and anti-inflammatory activities. This study aims to review current evidence regarding the role of citrus flavonoids in the management of atherosclerosis with a focus on their effect on adhesion molecules. Electronic databases including PubMed, Scopus, and Web of Science were searched with the names of adhesion molecules and flavonoids from inception until January 2023. The included articles highly support the beneficial effects of citrus flavonoids in preclinical models of atherosclerosis. Quercetin, naringin and naringenin, hesperidin and hesperetin, nobiletin, rutin, luteolin, apigenin, and kaempferol are the most common flavonoids in citrus fruits which could modulate adhesion molecules including ICAM-1, VCAM-1, E-selectin, and P-selectin. Additionally, markers of chronic inflammation such as interleukins, tumor necrosis factor-α, nuclear factor-κB, and nitric oxide signaling, as well as oxidative stress markers like superoxide dismutase and glutathione were all normalized upon administration of citrus flavonoids. Conclusively, this review confirms the modulatory role of flavonoids on adhesion molecules in atherosclerosis based on the preclinical evaluations. Thus, citrus fruits can be further studied in atherosclerotic patients regarding their activity in reducing adhesion molecules.

Selected Plant-Derived Polyphenols as Potential Therapeutic Agents for Peripheral Artery Disease: Molecular Mechanisms, Efficacy and Safety

Vascular diseases, such as peripheral artery disease (PAD), are associated with diabetes mellitus and a higher risk of cardiovascular disease and even death. Surgical revascularization and pharmacological treatments (mainly antiplatelet, lipid-lowering drugs, and antidiabetic agents) have some effectiveness, but the response and efficacy of therapy are overly dependent on the patient’s conditions. Thus, the demand for new cures exists. In this regard, new studies on natural polyphenols that act on key points involved in the pathogenesis of vascular diseases and, thus, on PAD are of great urgency. The purpose of this review is to take into account the mechanisms that lead to endothelium dysfunction, such as the glycoxidation process and the production of advanced glycation end-products (AGEs) that result in protein misfolding, and to suggest plant-derived polyphenols that could be useful in PAD. Thus, five polyphenols are considered, baicalein, curcumin, mangiferin, quercetin and resveratrol, reviewing the literature in PubMed. The key molecular mechanisms and preclinical and clinical studies of each selected compound are examined. Furthermore, the safety profiles of the polyphenols are outlined, together with the unwanted effects reported in humans, also by searching the WHO database (VigiBase).

Orange Juice Attenuates Circulating miR-150-5p, miR-25-3p, and miR-451a in Healthy Smokers: A Randomized Crossover Study

Introduction: Tobacco smoke is associated with oxidative and inflammatory pathways, increasing the risk of chronic-degenerative diseases. Our goal was to evaluate the effects of acute “Pera” and “Moro” orange juice consumption on inflammatory processes and oxidative stress in microRNA (miRNA) expression in plasma from healthy smokers.

Methods: This was a randomized crossover study that included healthy smokers over 18 years old. Blood samples were collected before and 11 h after beverage ingestion. Participants were instructed to drink 400 mL of Pera orange juice (Citrus sinensis), Moro orange juice (Citrus sinensis L. Osbeck), or water. Each subject drank the beverages in a 3-way crossover study design. Inflammatory and oxidative stress biomarkers and circulating miRNA expression profiles were determined. The subjects maintained their usual tobacco exposure during the experiment.

Results: We included 18 individuals (12 men and 6 women), with 37.0 ± 12.0 years old. All subjects received the 3 interventions. Increased expression of circulating miRNAs (miR-150-5p, miR-25-3p, and miR-451a) was verified after cigarette smoking, which were attenuated after intake of both types of orange juice. There was no difference regarding serum levels of TNF-α, IL-6, MMP-9, and C-reactive protein. Despite the increased activity of serum superoxide dismutase and glutathione peroxidase after “Pera” or “Moro” orange juice intake, respectively, no changes in lipid hydroperoxide levels were detected.

Conclusion: Tobaccos smokers showed increased expression of miR-150-5p, miR-25-3p, and miR-451a was noted, and attenuated by orange juice intake. miRNAs were predicted to regulate 244 target genes with roles in oxidative stress, PI3K-Akt, and MAPK signaling, which are pathways frequently involved in smoking-related cardiovascular diseases and cancer.

Intermittent High Glucose Elevates Nuclear Localization of EZH2 to Cause H3K27me3-Dependent Repression of KLF2 Leading to Endothelial Inflammation

Epigenetic mechanisms have emerged as one of the key pathways promoting diabetes-associated complications. Herein, we explored the role of enhancer of zeste homolog 2 (EZH2) and its product histone 3 lysine 27 trimethylation (H3K27me3) in high glucose-mediated endothelial inflammation. To examine this, we treated cultured primary endothelial cells (EC) with different treatment conditions-namely, constant or intermittent or transient high glucose. Intermittent high glucose maximally induced endothelial inflammation by upregulating transcript and/or protein-level expression of ICAM1 and P-selectin and downregulating eNOS, KLF2, and KLF4 protein levels. We next investigated the underlining epigenetic mechanisms responsible for intermittent hyperglycemia-dependent endothelial inflammation. Compared with other high glucose treatment groups, intermittent high glucose-exposed EC exhibited an increased level of H3K27me3 caused by reduction in EZH2 threonine 367 phosphorylation and nuclear retention of EZH2. Intermittent high glucose also promoted polycomb repressive complex-2 (PRC2) assembly and EZH2's recruitment to histone H3. Abrupt enrichment of H3K27me3 on KLF2 and KLF4 gene promoters caused repression of these genes, further supporting endothelial inflammation. In contrast, reducing H3K27me3 through small molecule and/or siRNA-mediated inhibition of EZH2 rescued KLF2 level and inhibited endothelial inflammation in intermittent high glucose-challenged cultured EC and isolated rat aorta. These findings indicate that abrupt chromatin modifications cause high glucose-dependent inflammatory switch of EC.

100% Fruit juice intake and cardiovascular risk: a systematic review and meta-analysis of prospective and randomised controlled studies

PURPOSE

The relationship between 100% fruit juice (100%FJ) consumption and cardiovascular risk is object of debate: indeed, recently published investigations provided new but discrepant evidence on this important question and International dietary guidelines are not in agreement on recommendations about fruit juice consumption. Therefore, we performed a meta-analysis of the prospective studies and the randomised controlled trials (RCTs) that explored the relationship between 100%FJ intake, cardiovascular risk profile and risk of cardiovascular events.

METHODS

We performed a systematic search of publications up to August 2019. Summary relative risks and exploration of linearity of the association were estimated for prospective studies and summary mean differences (MDs) calculated for RCTs.

RESULTS

A total of 21 prospective studies and 35 RCTs met the inclusion criteria. Dose-response analysis detected a significant inverse association between low-moderate 100%FJ consumption and risk of stroke (up to 200 ml/day) or total CV events (up to 170 ml/day) compared with no consumption, with a non-linear relationship (p for non-linearity < 0.05). No significant association was found for coronary heart disease and diabetes risk. In RCTs, a favorable and significant effect of 100%FJ intake was detected on blood pressure (systolic, MD: - 3.14 mmHg; diastolic, MD: - 1.68 mmHg), arterial compliance (carotid-femoral pulse wave velocity, - 0.38 m/s) and endothelial function (flow-mediated dilation, 2.10%). Neutral effects were found on body weight, blood lipids and glucose metabolism.

CONCLUSIONS

The results of these analyses indicate that 100%FJ consumption is not associated with higher CV risk. A non-linear inverse dose-response relationship occurs between 100%FJ consumption and CV disease, in particular for risk of stroke, probably mediated by the decrease in blood pressure.

TRIAL REGISTRATION

PROSPERO registration number (CRD42019135577).

Effects of Citrus Fruit Juices and Their Bioactive Components on Inflammation and Immunity: A Narrative Review

The immune system provides defence to the host against pathogenic organisms. A weak immune system increases susceptibility to infections and allows infections to become more severe. One component of the immune response is inflammation. Where inflammation is excessive or uncontrolled it can damage host tissues and cause pathology. Limitation of oxidative stress is one means of controlling inflammation. Citrus fruit juices are a particularly good source of vitamin C and folate, which both have roles in sustaining the integrity of immunological barriers and in supporting the function of many types of immune cell including phagocytes, natural killer cells, T-cells and B-cells. Vitamin C is an antioxidant and reduces aspects of the inflammatory response. Important bioactive polyphenols in citrus fruit juices include hesperidin, narirutin and naringin. Hesperidin is a glycoside of hesperetin while narirutin and naringin are glycosides of naringenin. Hesperidin, hesperetin, naringenin, naringin and narirutin have all been found to have anti-inflammatory effects in model systems, and human trials of hesperidin report reductions in inflammatory markers. In humans, orange juice was shown to limit the post-prandial inflammation induced by a high fat-high carbohydrate meal. Consuming orange juice daily for a period of weeks has been reported to reduce markers of inflammation, including C-reactive protein, as confirmed through a recent meta-analysis. A newly emerging topic is whether polyphenols from orange juice have direct anti-viral effects. In summary, micronutrients and other bioactives present in citrus fruit juices have established roles in controlling oxidative stress and inflammation and in supporting innate and acquired immune responses. Trials in humans demonstrate that orange juice reduces inflammation; its effects on innate and acquired immunity require further exploration in well-designed trials in appropriate population sub-groups such as older people.

Exploring the role of polyphenols in rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic, inflammatory and autoimmune disorder which is mainly characterized by inflammation in joints, bone erosions and cartilaginous destruction that leads to joint dysfunction, deformation, and/or permanent functional impairment. The prevalence of RA is increasing, incurring a considerable burden on healthcare systems globally. The exact etiology of RA is unknown, with various pathways implicated in its pathophysiology. Non-steroidal anti-inflammatory drugs (NSAIDs) including celecoxib, diclofenac and ibuprofen, disease-modifying anti-rheumatic drugs (DMARD) including azathioprine, methotrexate and cyclosporine, biological agents including anakinra, infliximab, and rituximab and immunosuppressants are used for symptomatic relief in patients with RA, but these medications have severe adverse effects such as gastric ulcers, hypertension, hepatotoxicity and renal abnormalities which restrict their use in the treatment of RA; new RA treatments with minimal side-effects are urgently required. There is accumulating evidence that dietary polyphenols may show therapeutic efficacy in RA through their antioxidant, anti-inflammatory, apoptotic, and immunosuppressant activities and modulation of the tumor necrosis factor-α (TNF-α), interleukin (IL)-6, mitogen-activated protein kinase (MAPK), IL-1β, c-Jun N-terminal kinase (JNK), and nuclear factor κ light-chain-enhancer of activated B cell (NF-κB) pathways. While resveratrol, genistein, carnosol, epigallocatechin gallate, curcumin, kaempferol, and hydroxytyrosol have also been studied for the treatment of RA, the majority of data are derived from animal models. Here, we review the various pathways involved in the development of RA and the preclinical and clinical data supporting polyphenols as potential therapeutic agents in RA patients. Our review highlights that high-quality clinical studies are required to decisively establish the anti-rheumatic efficacy of polyphenolic compounds.

Naringin protects endothelial cells from apoptosis and inflammation by regulating the Hippo-YAP Pathway

Atherosclerosis is the primary cause of several cardiovascular diseases. Oxidized low-density lipoprotein (ox-LDL)-induced apoptosis, endothelial–mesenchymal transition (EndMT), and inflammation are crucial for the progression of cardiovascular diseases, including atherosclerosis. Naringin, a major compound from tomatoes, grapefruits, and related citrus, reportedly exhibits potential protective effects during atherosclerosis development; however, its effect on ox-LDL-induced human umbilical vein endothelial cell (HUVEC) damage remains unknown. In the present study, we investigated the anti-apoptotic and anti-inflammatory activities of naringin against ox-LDL-induced endothelial cells, and the underlying mechanism. Naringin pretreatment significantly and concentration-dependently inhibited ox-LDL-induced cell injury and apoptosis. Additionally, naringin restored endothelial barrier integrity by preventing VE-cadherin disassembly and F-actin remodeling, and down-regulated pro-inflammatory factors like IL-1β, IL-6, and IL-18, in the HUVECs. We also demonstrated that naringin treatment restored ox-LDL-induced YAP (yes-associated protein) down-regulation, given the YAP-shRNA attenuated cytoprotective effect of naringin on ox-LDL-induced endothelial cell injury and apoptosis. Collectively, our data indicate that naringin reversed ox-LDL-triggered HUVEC apoptosis, EndMT, and inflammation by inhibiting the YAP pathway. Therefore, naringin may have a therapeutic effect on endothelial injury-related disorders.

RPS4Y1 Promotes High Glucose-Induced Endothelial Cell Apoptosis and Inflammation by Activation of the p38 MAPK Signaling

AIM

Endothelial dysfunction is a key pathological basis for diabetes mellitus complications, including diabetic nephropathy, diabetic retinopathy, and diabetic cardiomyopathy. This study aimed to reveal the functional role of ribosomal protein S4 Y-linked 1 (RPS4Y1) in endothelial dysfunction.

METHODS

Human umbilical vein endothelial cells (HUVECs) were subjected to high glucose. The expression of RPS4Y1 in cells was overexpressed or silenced by plasmid or siRNA transfection. MTT assay, flow cytometry, JC-1 probe, scratch test, tube formation, and ELISA were conducted to assess the effects of RPS4Y1 on cell. Western blot was performed to assay the downstream signaling of RPS4Y1. The inhibitors of p38, ERK, and Jnk were used to treat cells to validate the involvement of them in RPS4Y1-mediated endothelial dysfunction.

RESULTS

RPS4Y1 was upregulated in HUVECs in response to high glucose in both dose- and time-dependent manners. Overexpression of RPS4Y1 induced viability loss, apoptosis, and inflammation, but inhibited cell migration and tube formation. Silence of RPS4Y1 impacted these aspects in a contrary trend. The phosphorylation of p38 rather than ERK and Jnk was activated by RPS4Y1. In addition, the dysfunction of HUVECs mediated by RPS4Y1 was attenuated by SB203580 (a specific inhibitor of p38 signaling).

CONCLUSION

The highly expressed RPS4Y1 in endothelial cells may contribute to high glucose-induced dysfunction through regulating p38 MAPK signaling. RPS4Y1 might be a potential therapeutic target for treating diabetes mellitus complications.

Polyphenols in the treatment of autoimmune diseases

In addition to protecting body from infections and diseases, the immune system produces auto-antibodies that can cause complex autoimmune disorders, such as Type I diabetes, primary biliary cirrhosis, rheumatoid arthritis, and multiple sclerosis, to name a few. In such cases, the immune system fails to recognize between foreign agents and its own body cells. Different factors, such as genetic factors (CD25, STAT4), epigenetic factors (DNA methylation, histone modifications) and environmental factors (xenobiotics, drugs, hormones) trigger autoimmunity. Glucocorticoids, non-steroidal anti-inflammatory drugs (NSAIDs), immunosuppressive and biological agents are currently used to manage autoimmune diseases of different origins. However, complete cure remains elusive. Many dietary and natural products including polyphenols have been widely studied as possible alternative treatment strategies for the management of autoimmune disorders. Polyphenols possess a wide-range of pharmacological and therapeutic properties, including antioxidant and anti-inflammatory activities. As immunomodulatory agents, polyphenols are emerging pharmaceutical tools for management of various autoimmune disorders including vitiligo, ulcerative colitis and multiple sclerosis (MS). Polyphenols activate intracellular pathways such as arachidonic acid dependent pathway, nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) signaling pathway, mitogen-activated protein kinases (MAPKs) pathway, phosphatidylinositol 3-kinase/protein kinase B (PI3K/Akt) signaling pathway and epigenetic modulation, which regulate the host's immune response. This timely review discusses putative points of action of polyphenols in autoimmune diseases, characterizing their efficacy and safety as therapeutic agents in managing autoimmune disorders.

The effects of flavonoids on human first trimester trophoblast spheroidal stem cell self-renewal, invasion and JNK/p38 MAPK activation: Understanding the cytoprotective effects of these phytonutrients against oxidative stress

Adequate invasion and complete remodelling of the maternal spiral arteries by the invading extravillous trophoblasts are the major determinants of a successful pregnancy. Increase in oxidative stress during pregnancy has been linked to the reduction in trophoblast invasion and incomplete conversion of the maternal spiral arteries, resulting in pregnancy complications such as pre-eclampsia, intrauterine growth restriction, and spontaneous miscarriages resulting in foetal/maternal mortality. The use of antioxidant therapy (vitamin C and E) and other preventative treatments (such as low dose aspirin) have been ineffective in preventing pre-eclampsia. Also, as the majority of antihypertensive drugs pose side effects, choosing an appropriate treatment would depend upon the efficacy and safety of mother/foetus. Since pre-eclampsia is mainly linked to placental oxidative stress, new diet-based antioxidants can be of use to prevent this condition. The antioxidant properties of flavonoids (naturally occurring phenolic compounds which are ubiquitously distributed in fruits and vegetables) have been well documented in non-trophoblast cells. Therefore, this study aimed to investigate the effects of flavonoids (quercetin, hesperidin) and their metabolites (Quercetin 3-O-β-glucuronide and hesperetin), either alone or in combination, on first trimester trophoblast cell line HTR-8/SVneo during oxidative stress. The data obtained from this study indicate that selected flavonoids, their respective metabolites significantly reduced the levels of reduced glutathione (p < 0.0001) during HR-induced oxidative stress. These flavonoids also inhibited the activation of pro-apoptotic kinases (p38 MAPK and c-Jun N-terminal kinase) during HR-induced phosphorylation. In addition, they enhanced spheroid stem-like cell generation from HTR8/SVneo cells, aiding their invasion. Our data suggest that dietary intake of food rich in quercetin or hesperidin during early pregnancy can significantly improve trophoblast (placenta) health and function against oxidative stress.

Rosuvastatin inhibits high glucose-stimulated upregulation of VCAM-1 via the MAPK-signalling pathway in endothelial cells

OBJECTIVE

The aim of this study is to investigate the molecular mechanisms and effect of rosuvastatin on adhesion molecule induction in human endothelial cells under high-glucose conditions (HG).

METHODS AND RESULTS

The effects of rosuvastatin on vascular cell adhesion molecule (VCAM)-1 production and pERK phosphorylation were measured in HG-induced human umbilical vein endothelial cells (HUVECs) with inhibitors targeting the mitogen-activated protein kinase (MAPK) signal pathway. HG increased levels of VCAM-1. Treatment with rosuvastatin inhibited VCAM-1 expression in a concentration- and time-dependent manner. In addition, we investigated the effects of rosuvastatin on the extracellular signal-regulated kinase (ERK) 1/2 signal pathway. Rosuvastatin completely inhibited HG-induced phosphorylation of ERK. ERK/MAPK inhibitors completely prevented the VCAM-1 inhibition effect of rosuvastatin under HG condition.

CONCLUSIONS

This study demonstrated that rosuvastatin suppresses HG-induced VCAM-1 production via the MAPK signalling pathway, playing a role in the suppression of atherosclerosis.

High glucose-mediated overexpression of ICAM-1 in human vaginal epithelial cells increases adhesion of Candida albicans

To investigate the involvement of ICAM-1 in the adhesion of Candida to the genitourinary epithelial cells in high glucose, we examined the adhesion of Candida albicans or Candida glabrata to human vaginal epithelial cells (VK2/E6E7) or human vulvovaginal epidermal cells (A431). These cells were cultured in 100, 500 or 3000 mg/dL glucose for three days and inoculated with Candida for 60 minutes. Followed by, adhering of Candida to the cells, which were counted. While the adhesion of Candida albicans to VK2/E6E7 significantly increased in the high glucose, A431 did not. We next examined the expression of ICAM-1 as a ligand on the epithelial cells. ICAM-1 expression was increased in VK2/E6E7 cultured in the high glucose; however, the expression level in A431 was not high compared with VK2/E6E7. This data suggested that ICAM-1 functions as one of ligands in the adhesion of Candida albicans to the vaginal epithelial cells in a high glucose environment. Impact statement What is already known on the subject: Candida's complement receptor is involved in the adhesion to epithelial cells. The expression of this receptor has been reported to increase as glucose concentration increases. This is considered as a contributing factor to the high risk for vulvovaginal candidiasis (VVC) in diabetes. On the host side, diabetic patients have a factor that facilitates adhesion of Candida to epithelial cells. This factor has been unknown until recently. What the results of this study add: In this study, we used a vaginal epithelial cell line and showed that the adhesion of C. albicans to cells increased at higher glucose concentrations. At the same time, ICAM-1 expression of cells also increased. Thereby, it is suggested that the expression of ICAM-1 in vaginal epithelial cells is increased by glucose such as urinary sugar in diabetic patients and is a condition for facilitating adhesion of Candida. What the implications are of these findings for clinical practice and/or further research: We expect not only host immune dysfunction but also alteration in epithelial cells will be focussed on as a cause of VVC in diabetic patients.

The endothelial border to health: Mechanistic evidence of the hyperglycemic culprit of inflammatory disease acceleration

The endothelial cell (EC) layer constitutes a barrier that controls movements of fluid, solutes and cells between blood and tissue. Further, the endothelial layer regulates vascular tone and directs local humoral and cellular inflammatory processes. The strategic position makes it an important player for maintenance of health and for development of a number of diseases. Endothelial dysfunction is known to be an important component of type 2 diabetes, but is also assumed to be involved in many other diseases, for example, rheumatoid arthritis, inflammatory bowel disease, asthma, and cardiovascular diseases. We here suggest that the EC plays a pivotal role in disease pathophysiology through initiation, potentiation, and maintenance of several inflammatory mechanisms. Our contention is based on the observation that hyperglycemia-intermittent or sustained, local or systemic-is a major culprit for several endothelial dysfunctions. There is also mounting epidemiological evidence that dietary intake of refined sugars is important for the development of a number of diseases beyond obesity and type 2 diabetes. Various diseases involving inflammatory and immunological components are accelerated by hyperglycemic events because the endothelium transduces "high glucose" signaling into significant pathophysiological phenomena leading to reduced endothelial barrier function, compromised vascular tone regulation and inflammation (e.g., cytokine secretion and RAGE activation). In addition, endothelial extracellular proteins form epitopes for potential specific antibody formation upon interactions with reducing sugars. This paper reviews the endothelial metabolism, biology, inflammatory processes, physical barrier functions, and summarizes evidence that although stochastic in nature, endothelial responses to hyperglycemia are major contributors to disease pathophysiology. We present molecular and mechanistic evidence that both biological and physical barriers, protein function, specific immunity, and inflammatory processes are compromised by hyperglycemic events and thus, hyperglycemic events alone should be considered risk factors for numerous human diseases. © 2017 IUBMB Life, 69(3):148-161, 2017.

Zinc Finger E-Box Binding Protein 2 (ZEB2) Suppress Apoptosis of Vascular Endothelial Cells Induced by High Glucose Through Mitogen-Activated Protein Kinases (MAPK) Pathway Activation

Background

Hyperglycemia has been confirmed to damage endothelial function of vascular and microvascular. The regulation of zinc finger E-box binding protein 2 (ZEB2) on vascular endothelial cells (VECs) is reported rarely. Our study investigates the role of ZEB2 on the apoptosis of VECs induced by high glucose through MAPK pathway.

Material/Methods

Downregulated and upregulated expression of ZEB2 in human umbilical vein endothelial cells (HUVECs) were performed by plasmids transfection. HUVECs are respectively treated with different concentrations of glucose (5.5 mM, 33 mM). The expression of mRNA and protein were detected by real-time quantified PCR and western blotting. Apoptotic cells were measured by flow cytometry. Proliferation and migration of HUVECs were detected by MTT assay and wound healing assay.

Results

The apoptosis of HUVECs detected by flow cytometry and western blot revealed that ZEB2 overexpression distinctly suppressed the apoptosis of HUVECs induced by high glucose. ZEB2 overexpression promoted the proliferative and migration activity of HUVECs. Besides, ZEB2 overexpression specifically accelerated the phosphorylation level of JNK, and suppressed the apoptosis and promoted the proliferative of VECs via JNK pathway.

Conclusion

ZEB2 suppress apoptosis of VECs induced by high glucose through MAPK pathway activation, which provides a novel insight and therapeutic target for endothelial injury.

Resveratrol attenuates ICAM-1 expression and monocyte adhesiveness to TNF-α-treated endothelial cells: evidence for an anti-inflammatory cascade mediated by the miR-221/222/AMPK/p38/NF-κB pathway

Resveratrol, an edible polyphenolic phytoalexin, improves endothelial dysfunction and attenuates inflammation. However, the mechanisms have not been thoroughly elucidated. Therefore, we investigated the molecular basis of the effects of resveratrol on TNF-α-induced ICAM-1 expression in HUVECs. The resveratrol treatment significantly attenuated the TNF-α-induced ICAM-1 expression. The inhibition of p38 phosphorylation mediated the reduction in ICAM-1 expression caused by resveratrol. Resveratrol also decreased TNF-α-induced IκB phosphorylation and the phosphorylation, acetylation, and translocation of NF-κB p65. Moreover, resveratrol induced the AMPK phosphorylation and the SIRT1 expression in TNF-α-treated HUVECs. Furthermore, TNF-α significantly suppressed miR-221/-222 expression, which was reversed by resveratrol. miR-221/-222 overexpression decreased p38/NF-κB and ICAM-1 expression, which resulted in reduced monocyte adhesion to TNF-α-treated ECs. In a mouse model of acute TNF-α-induced inflammation, resveratrol effectively attenuated ICAM-1 expression in the aortic ECs of TNF-α-treated wild-type mice. These beneficial effects of resveratrol were lost in miR-221/222 knockout mice. Our data showed that resveratrol counteracted the TNF-α-mediated reduction in miR-221/222 expression and decreased the TNF-α-induced activation of p38 MAPK and NF-κB, thereby suppressing ICAM-1 expression and monocyte adhesion. Collectively, our results show that resveratrol attenuates endothelial inflammation by reducing ICAM-1 expression and that the protective effect was mediated partly through the miR-221/222/AMPK/p38/NF-κB pathway.

Plantamajoside from Plantago asiatica modulates human umbilical vein endothelial cell dysfunction by glyceraldehyde-induced AGEs via MAPK/NF-κB

Background

Plantago asiatica has been traditionally used for traditional medicine around East Asia. Plantamajoside (PM), which is isolated from this plant, is known for biological properties including anti-inflammation and antioxidant activity. To demonstrate the biological activity of PM against endothelial dysfunction induced by advanced glycation end-products (AGEs), a cellular inflammatory mechanism system was evaluated in human umbilical vein endothelial cells (HUVECs).

Methods

We obtained PM through previous research in our laboratory. We formed the AGEs from bovine serum albumin with glyceraldehyde in the dark for seven days. To confirm the modulation of the inflammatory mechanism in endothelial dysfunction, we quantified the various pro-inflammatory cytokines and endothelial dysfunction-related proteins in the HUVECs with Western blotting and with real-time and quantitative real-time polymerase chain reactions.

Results

Co-treatment with PM and AGEs significantly suppressed inflammatory cytokines and adhesion molecule expression. Moreover, the PM treatment for down-regulated inflammatory signals and blocked monocyte adhesion on the HUVECs.

Conclusions

Theses results demonstrated that PM, as a potential natural compound, protects AGE-induced endothelial cells against inflammatory cellular dysfunction.

Electronic supplementary material

The online version of this article (doi:10.1186/s12906-017-1570-1) contains supplementary material, which is available to authorized users.

Flavonoids

Diabetes Mellitus is one of the major healthcare problems faced by the society today and has become alarmingly epidemic in many parts of the world. Despite enormous knowledge and technology advancement, available diabetes therapeutics only provide symptomatic relief by reducing blood glucose level, thereby, just slows down development and progression of diabetes and its associated complications. Thus, the need of the day is to develop alternate strategies that can not only prevent the progression but also reverse already “set-in” diabetic complications. Many flavonoids are reported, traditionally as well as experimentally, to be beneficial in averting diabetes and lowering risk of its accompanying complications. In the present chapter we have convened different flavonoids beneficial in diabetes and comorbid complications and discussed their mechanisms of action. Further, we conclude that coupling current therapeutics with flavonoids might provide exceptional advantage in the management of diabetes and its complications.

Anti-Inflammation of Natural Components from Medicinal Plants at Low Concentrations in Brain via Inhibiting Neutrophil Infiltration after Stroke

Inflammation after stroke consists of activation of microglia/astrocytes in situ and infiltration of blood-borne leukocytes, resulting in brain damage and neurological deficits. Mounting data demonstrated that most natural components from medicinal plants had anti-inflammatory effects after ischemic stroke through inhibiting activation of resident microglia/astrocytes within ischemic area. However, it is speculated that this classical activity cannot account for the anti-inflammatory function of these natural components in the cerebral parenchyma, where they are detected at very low concentrations due to their poor membrane permeability and slight leakage of BBB. Could these drugs exert anti-inflammatory effects peripherally without being delivered across the BBB? Factually, ameliorating blood-borne neutrophil recruitment in peripheral circulatory system has been proved to reduce ischemic damage and improve outcomes. Thus, it is concluded that if drugs could achieve effective concentrations in the cerebral parenchyma, they can function via crippling resident microglia/astrocytes activation and inhibiting neutrophil infiltration, whereas the latter will be dominating when these drugs localize in the brain at a low concentration. In this review, the availability of some natural components crossing the BBB in stroke will be discussed, and how these drugs lead to improvements in stroke through inhibition of neutrophil rolling, adhesion, and transmigration will be illustrated.

Exenatide Alters Gene Expression of Neural Cell Adhesion Molecule (NCAM), Intercellular Cell Adhesion Molecule (ICAM), and Vascular Cell Adhesion Molecule (VCAM) in the Hippocampus of Type 2 Diabetic Model Mice

Background

Glucagon-like peptide-1 (GLP-1), a potent and selective agonist for the GLP-1 receptor, ameliorates the symptoms of diabetes through stimulation of insulin secretion. Exenatide is a potent and selective agonist for the GLP-1 receptor. Cell adhesion molecules are members of the immunoglobulin superfamily and are involved in synaptic rearrangements in the mature brain.

Material/Methods

The present study demonstrated the effects of exenatide treatment (0.1 μg/kg, subcutaneously, twice daily for 2 weeks) on the gene expression levels of cell adhesion molecules, neural cell adhesion molecule (NCAM), intercellular cell adhesion molecule (ICAM), and vascular cell adhesion molecule (VCAM) in the brain tissue of diabetic BALB/c male mice by real-time quantitative polymerase chain reaction (PCR). Diabetes was induced by streptozotocin/nicotinamide (STZ-NA) injection to male mice.

Results

The results of this study revealed that hippocampal gene expression of NCAM, ICAM, and VCAM were found to be up-regulated in STZ-NA-induced diabetic mice compared to those of controls. A significant decrease in the gene expression levels of NCAM, ICAM, and VCAM were determined after 2 weeks of exenatide administration.

Conclusions

Cell adhesion molecules may be involved in the molecular mechanism of diabetes. Exenatide has a strong beneficial action in managing diabetes induced by STZ/NA by altering gene expression of NCAM, ICAM, and VCAM.

Anti-inflammatory and Antioxidant Effects of Flavonoid-Rich Fraction of Bergamot Juice (BJe) in a Mouse Model of Intestinal Ischemia/Reperfusion Injury

The flavonoid-rich fraction of bergamot juice (BJe) has demonstrated anti-inflammatory and antioxidant activities. The aim of work was to test the beneficial effects of BJe on the modulation of the ileum inflammation caused by intestinal ischemia/reperfusion (I/R) injury in mice. To understand the cellular mechanisms by which BJe may decrease the development of intestinal I/R injury, we have evaluated the activation of signaling transduction pathways that can be induced by reactive oxygen species production. Superior mesenteric artery and celiac trunk were occluded for 30 min and reperfused for 1 h. The animals were sacrificed after 1 h of reperfusion, for both histological and molecular examinations of the ileum tissue. The experimental results demonstrated that BJe was able to reduce histological damage, cytokines production, adhesion molecules expression, neutrophil infiltration and oxidative stress by a mechanism involved both NF-κB and MAP kinases pathways. This study indicates that BJe could represent a new treatment against inflammatory events of intestinal I/R injury.

Reversibility of endothelial dysfunction in diabetes: role of polyphenols

The endothelium, a thin single sheet of endothelial cells, is a metabolically active layer that coats the inner surface of blood vessels and acts as an interface between the circulating blood and the vessel wall. The endothelium through the secretion of vasodilators and vasoconstrictors serves as a critical mediator of vascular homeostasis. During the development of the vascular system, it regulates cellular adhesion and vessel wall inflammation in addition to maintaining vasculogenesis and angiogenesis. A shift in the functions of the endothelium towards vasoconstriction, proinflammatory and prothrombic states characterise improper functioning of these cells, leading to endothelial dysfunction (ED), implicated in the pathogenesis of many diseases including diabetes. Major mechanisms of ED include the down-regulation of endothelial nitric oxide synthase levels, differential expression of vascular endothelial growth factor, endoplasmic reticulum stress, inflammatory pathways and oxidative stress. ED tends to be the initial event in macrovascular complications such as coronary artery disease, peripheral arterial disease, stroke and microvascular complications such as nephropathy, neuropathy and retinopathy. Numerous strategies have been developed to protect endothelial cells against various stimuli, of which the role of polyphenolic compounds in modulating the differentially regulated pathways and thus maintaining vascular homeostasis has been proven to be beneficial. This review addresses the factors stimulating ED in diabetes and the molecular mechanisms of natural polyphenol antioxidants in maintaining vascular homeostasis.

SUR1 Receptor Interaction with Hesperidin and Linarin Predicts Possible Mechanisms of Action of Valeriana officinalis in Parkinson

Parkinson's disease (PD) is one of the most common neurodegenerative disorders. A theoretical approach of our previous experiments reporting the cytoprotective effects of the Valeriana officinalis compounds extract for PD is suggested. In addiction to considering the PD as a result of mitochondrial metabolic imbalance and oxidative stress, such as in our previous in vitro model of rotenone, in the present manuscript we added a genomic approach to evaluate the possible underlying mechanisms of the effect of the plant extract. Microarray of substantia nigra (SN) genome obtained from Allen Brain Institute was analyzed using gene set enrichment analysis to build a network of hub genes implicated in PD. Proteins transcribed from hub genes and their ligands selected by search ensemble approach algorithm were subjected to molecular docking studies, as well as 20 ns Molecular Dynamics (MD) using a Molecular Mechanic Poison/Boltzman Surface Area (MMPBSA) protocol. Our results bring a new approach to Valeriana officinalis extract, and suggest that hesperidin, and probably linarin are able to relieve effects of oxidative stress during ATP depletion due to its ability to binding SUR1. In addition, the key role of valerenic acid and apigenin is possibly related to prevent cortical hyperexcitation by inducing neuronal cells from SN to release GABA on brain stem. Thus, under hyperexcitability, oxidative stress, asphyxia and/or ATP depletion, Valeriana officinalis may trigger different mechanisms to provide neuronal cell protection.

Resveratrol and Ophthalmic Diseases

Resveratrol, a naturally occurring plant polyphenol found in grapes, is the principal biologically active component in red wine. Clinical studies have shown that resveratrol due to its potent anti-oxidant and anti-inflammatory properties are cardio-protective, chemotherapeutic, neuroprotective, and display anti-aging effects. Oxidative stress and inflammation play a critical role in the initiation and progression of age-related ocular diseases (glaucoma, cataract, diabetic retinopathy and macular degeneration) that lead to progressive loss of vision and blindness. In vitro and in vivo (animal model) experimental studies performed so far have provided evidence for the biological effects of resveratrol on numerous pathways including oxidative stress, inflammation, mitochondrial dysfunction, apoptosis, pro-survival or angiogenesis that are implicated in the pathogenesis of these age-related ocular disorders. In this review, we provide a brief overview of current scientific literature on resveratrol, its plausible mechanism(s) of action, its potential use and current limitations as a nutritional therapeutic intervention in the eye and its related disorders.

The Anti-Atherosclerotic Effect of Naringin Is Associated with Reduced Expressions of Cell Adhesion Molecules and Chemokines through NF-κB Pathway

Naringin has been reported to have an anti-atherosclerosis effect but the underlying mechanism is not fully understood. The aim of this study is to investigate the impact of naringin on the TNF-α-induced expressions of cell adhesion molecules, chemokines and NF-κB signaling pathway in human umbilical vein endothelial cells (HUVECs). The experiments revealed that naringin, at concentrations without cytotoxicity, dose-dependently inhibited the adhesion of THP-1 monocytes to the TNF-α-stimulated HUVECs. The TNF-α-induced expressions of cell adhesion molecules, including VCAM-1, ICAM-1 and E-selectin, at both the mRNA and protein levels, were significantly suppressed by naringin in a dose dependent manner. In addition, the TNF-α-induced mRNA and protein levels of chemokines, including fractalkine/CX3CL1, MCP-1 and RANTES, were also reduced by naringin. Naringin significantly inhibited TNF-α-induced nuclear translocation of NF-κB, which resulted from the inhibited phosphorylation of IKKα/β, IκB-α and NF-κB. Altogether, we proposed that naringin modulated TNF-α-induced expressions of cell adhesion molecules and chemokines through the inhibition of TNF-α-induced activation of IKK/NF-κB signaling pathway to exert the anti-atherosclerotic effect.

Angiotensin 1-7 significantly reduces diabetes-induced leukocyte recruitment both in vivo and in vitro

OBJECTIVE

Recent studies have demonstrated that Ang1-7 has anti-inflammatory effects. Since the formation of Ang1-7 is significantly altered in the setting of diabetes, here we aimed to evaluate whether Ang1-7 infusion could ameliorate diabetes-induced leukocyte recruitment.

METHODS

Wild-type male Wistar rats were randomly allocated to the following groups: control + saline, control + Ang1-7, diabetes + saline, diabetes + Ang1-7. Diabetes was induced by streptozotocin. Saline and Ang1-7 (576 μg/kg/day) were injected intraperitoneally daily. After 4 weeks leukocyte trafficking was studied in vivo by intravital microscopy in the mesenteric bed, where the expression of pro-oxidative, proinflammatory, and profibrotic molecules was also assessed. In parallel in vitro studies, HUVEC were grown in 5 mM, 22 mM, 30 mM, 40 mM, 50 mM, and 75 mM glucose media for 48 h, 72 h and 6 days and were treated either with placebo, or with Ang1-7, or with Ang1-7 and its inhibitor A779 in order to evaluate the expression of ICAM-1 and VCAM-1. We further studied leukocytes recruitment in vitro by evaluating PMN-HUVEC adhesion.

RESULTS

Ang1-7 prevented in vivo diabetes-induced leukocyte adhesion and extravasation, and it significantly reduced vascular hypertrophy and the other molecular changes due to diabetes. Ang 1-7 prevented also in vitro the hyperglycemia-induced increase of ICAM-1 and VCAM-1 as well as the hyperglycemia-induced PMN adhesion. A779 inhibited Ang 1-7 effects.

CONCLUSIONS

Ang1-7 significantly reduced diabetes-induced leukocyte recruitment both in vivo and in vitro. These findings emphasize the potential utility of ACE2/Ang1-7/Mas repletion as a strategy to reduce diabetes-induced atherosclerosis.

Beneficial effects of evodiamine on P2X(4)-mediated inflammatory injury of human umbilical vein endothelial cells due to high glucose

Evodiamine has been reported to exhibit anti-inflammatory and anti-nociceptive effects, but the underlying mechanisms remain to be defined. P2X4 receptor (P2X4R) is a subtype of ATP receptors and plays important roles in pain, inflammatory and immune responses. We aimed to investigate whether evodiamine has beneficial effects on endothelial inflammatory injury mediated by chronic high glucose condition. We found that culturing human umbilical vein endothelial cells (HUVECs) with high glucose significantly increased the expression of P2X4 receptor in HUVECs, cytosolic Ca(2+) concentrations and intracellular reactive oxygen species (ROS) while decreasing nitric oxide (NO); these effects could be reversed by evodiamine. High glucose also significantly increased the expression of the pro-inflammatory activators (NF-κB) and TNFR-ɑ, which was accompanied by the elevation of P2X4R levels. Evodiamine was able to down-regulate the elevated NF-κB, TNFR-ɑ, P2X4R and ROS, and up-regulate the decreased NO. Thus the evodiamine may exert the anti-inflammation activity on high-glucose challenge HUVEC via suppressing the P2X4R signaling pathway, exhibiting beneficial ability to protect HUVECs from glucotoxicity.

The ATP Receptors P2X7 and P2X4 Modulate High Glucose and Palmitate-Induced Inflammatory Responses in Endothelial Cells

Endothelial cells lining the blood vessels are principal players in vascular inflammatory responses. Dysregulation of endothelial cell function caused by hyperglycemia, dyslipidemia, and hyperinsulinemia often result in impaired vasoregulation, oxidative stress, inflammation, and altered barrier function. Various stressors including high glucose stimulate the release of nucleotides thus initiating signaling via purinergic receptors. However, purinergic modulation of inflammatory responses in endothelial cells caused by high glucose and palmitate remains unclear. In the present study, we investigated whether the effect of high glucose and palmitate is mediated by P2X7 and P2X4 and if they play a role in endothelial cell dysfunction. Transcript and protein levels of inflammatory genes as well as reactive oxygen species production, endothelial-leukocyte adhesion, and cell permeability were investigated in human umbilical vein endothelial cells exposed to high glucose and palmitate. We report high glucose and palmitate to increase levels of extracellular ATP, expression of P2X7 and P2X4, and inflammatory markers. Both P2X7 and P2X4 antagonists inhibited high glucose and palmitate-induced interleukin-6 levels with the former having a significant effect on interleukin-8 and cyclooxygenase-2. The effect of the antagonists was confirmed with siRNA knockdown of the receptors. In addition, P2X7 mediated both high glucose and palmitate-induced increase in reactive oxygen species levels and decrease in endothelial nitric oxide synthase. Blocking P2X7 inhibited high glucose and palmitate-induced expression of intercellular adhesion molecule-1 and vascular cell adhesion molecule-1 as well as leukocyte-endothelial cell adhesion. Interestingly, high glucose and palmitate enhanced endothelial cell permeability that was dependent on both P2X7 and P2X4. Furthermore, antagonizing the P2X7 inhibited high glucose and palmitate-mediated activation of p38-mitogen activated protein kinase. These findings support a novel role for P2X7 and P2X4 coupled to induction of inflammatory molecules in modulating high glucose and palmitate-induced endothelial cell activation and dysfunction.

Resveratrol analog piceatannol restores the palmitic acid-induced impairment of insulin signaling and production of endothelial nitric oxide via activation of anti-inflammatory and antioxidative heme oxygenase-1 in human endothelial cells

Growing evidence suggests that the elevation of free fatty acids, including palmitic acid (PA), are associated with inflammation and oxidative stress, which may be involved in endothelial dysfunction, characterized by the reduced bioavailability of nitric oxide (NO) synthesized from endothelial NO synthase (eNOS). Heme oxygenase-1 (HO-1) is important in the preservation of NO bioavailability. Piceatannol (Pic), with similar chemical structure to resveratrol, is suggested to possess similar protective effects as resveratrol. In the present study, human umbilical vein endothelial cells (HUVECs), stimulated with PA, were used to examine the endothelial protective effects of Pic. Pic increased the expression of HO-1 via nuclear factor erythroid-2-related factor-2 activation in the HUVECs, and decreased the PA-induced secretions of interleukin-6 and tumor necrosis factor-α, and the formation of reactive oxygen species ROS via inhibition of NF-κB activation. Notably, following inhibition of HO-1 activity by tin protoporphryin-IX, Pic did not prevent cytokine secretion, ROS formation, and NF-κB activation in the PA-stimulated HUVECs. PA attenuated insulin-mediated insulin receptor substrate-1 (IRS-1) tyrosine phosphorylation, leading to decreased glucose uptake, and phosphorylation of eNOS, leading to a reduction in the production of NO. Pic effectively mitigated the inhibitory effects of PA on the insulin-mediated phosphorylation of IRS-1 and eNOS, which was not observed following inhibition of HO‑1 activity. The results of the present study suggested that Pic may have the potential to prevent PA-induced impairment of insulin signaling and eNOS function, by inducing the expression of the anti-inflammatory and antioxidant, HO-1.

Molecular mechanisms behind the biological effects of hesperidin and hesperetin for the prevention of cancer and cardiovascular diseases

Hesperidin (Hsd) and its aglycone, hesperetin (Hst), are two flavonoids from citrus species that have various biological properties, particularly those for the prevention of cancer and cardiovascular diseases. Studies have shown both anti-cancer and cancer chemopreventive effects for Hsd and Hst. Cancer chemopreventive properties of Hsd and Hst are mainly associated with their antioxidant, radical scavenging and anti-inflammatory activities. In addition, Hsd and Hst interfere at different stages of cancer. Unlike conventional anti-cancer drugs, Hsd and Hst inhibit tumor growth by targeting multiple cellular protein targets at the same time, including caspases, Bcl-2 (B-cell lymphoma 2) and Bax (Bcl-2 associated X protein) for the induction of apoptosis, and COX-2 (cyclooxygenase-2), MMP-2 (matrix metalloproteinase-2) and MMP-9 for the inhibition of angiogenesis and metastasis. The results of the recent basic and clinical studies revealed the beneficial effects for Hst, Hsd and their derivatives in the treatment of heart failure and cardiac remodeling, myocardial ischemia and infarction, and hypertension. In addition, the valuable effects of Hst and Hsd in the treatment of diabetes and dyslipidemia with their anti-platelet and anticoagulant effects make them good candidates in the treatment of various cardiovascular diseases. In this review, new findings regarding the molecular targets of Hsd and Hst, animal studies and clinical trials are discussed.

Protection of vascular endothelial cells from high glucose-induced cytotoxicity by emodin

Induction of endothelial cytotoxicity by hyperglycemia in diabetes has been widely accepted. Emodin is a natural anthraquinone in rhubarb used for treatment of diabetes, but its mechanism of action is not fully understood. This study aimed to examine the potential beneficial effects of emodin on endothelial cytotoxicity caused by high glucose milieu. Culture of human umbilical vein endothelial cells (HUVECs) with high concentrations of glucose resulted in damage to the cells, leading to decreased formazan products by 14-27%, reduced DNA contents by 12-19%, and increased hypodiploid apoptosis by 40-109%. These adverse effects of high glucose could be prevented to a large extent by co-culture with 3 μM of emodin which per se did not affect HUVECs viability. In addition, CCL5 expression of HUVECs cultured in high glucose medium was significantly elevated at both mRNA and protein levels, an effect abolished after treatment with emodin. Moreover, the enhanced adhesion of monocytes to HUVECs (2.1-2.2 fold over control) and elevated chemotaxis activities (2.3-2.4 fold over control) in HUVECs cultured in high glucose medium were completely reversed by emodin. Emodin also suppressed activation of p38 MAPK and ERK1/2 due to high glucose. Our data demonstrated that endothelial cytotoxicity occurred clearly when HUVECs were exposed to high glucose milieu and emodin was able to alleviate the impairments. The protective effects of emodin might be related to the inhibition of CCL5 expression and subsequent cell stress/inflammatory events possibly mediated by activation of MAPK signaling pathways.

Anti-inflammatory activity of polyphenolics from açai (Euterpe oleracea Martius) in intestinal myofibroblasts CCD-18Co cells

This is the first time that the anti-inflammatory activities of açai polyphenols relevant to intestinal inflammation were demonstrated in colon fibroblasts cells.

The anti-inflammatory and antioxidant effects of bergamot juice extract (BJe) in an experimental model of inflammatory bowel disease

BACKGROUND & AIMS

The beneficial properties of the flavonoid fraction of bergamot juice (BJe) have been raising interest and have been the subject of recent studies, considering the potentiality of its health promoting substances. Flavonoids have demonstrated radical-scavenging and anti-inflammatory activities. The aim of the present study was to examine the effects of BJe in mice subjected to experimental colitis.

METHODS

Colitis was induced in mice by intracolonic instillation of dinitrobenzene sulfonic acid (DNBS). BJe was administered daily orally (at 5, 10 and 20 mg/kg).

RESULTS

Four days after DNBS administration, colon nuclear factor NF-κB translocation and MAP kinase phospho-JNK activation were increased as well as cytokine production such as tumor necrosis factor (TNF)-α and interleukin (IL)-1β. Neutrophil infiltration, by myeloperoxidase (MPO) activity, in the mucosa was associated with up-regulation of adhesion molecules (ICAM-1 and P-selectin). Immunohistochemistry for nitrotyrosine and poly ADP-ribose (PAR) also showed an intense staining in the inflamed colon. Treatment with BJe decreased the appearance of diarrhea and body weight loss. This was associated with a reduction in colonic MPO activity. BJe reduced nuclear NF-κB translocation, p-JNK activation, the pro-inflammatory cytokines release, the appearance of nitrotyrosine and PAR in the colon and reduced the up-regulation of ICAM-1 and P-selectin. In addition, colon inflammation was also associated with apoptotic damage. Treatment with BJe caused a decrease of pro-apoptotic Bax expression and an increase of anti-apoptotic Bcl-2 expression.

CONCLUSIONS

The results of this study suggested that administration of BJe induced, partly specified, anti-inflammatory mechanisms, which potentially may be beneficial for the treatment of IBD in humans.

Upregulation of ICAM-1 in diabetic rats after transient forebrain ischemia and reperfusion injury

Background

Hyperglycemia exacerbates brain damage caused by cerebral ischemia. Neuroinflammation may play a role in mediating such enhanced damage. The objectives of this study were to examine the mRNA and protein levels and cell type distribution of ICAM-1 after cerebral ischemia in normo-and diabetic hyperglycemic rats.

Results

Compared to normoglycemic ischemia animals, diabetes aggravated neuronal death, decreased Nissl body staining, and increased ICAM-1 mRNA and protein levels in the frontal cortex. The increased ICAM-1 was located not only in vascular endothelial cells but also in cortical neurons.

Conclusions

Our results suggest that exacerbated neuro-inflammation in the brain may mediate the detrimental effects of diabetes on the ischemic brain.

Resveratrol and cardiovascular health--promising therapeutic or hopeless illusion?

Resveratrol (3,5,4'-trihydroxy-trans-stilbene) is a natural polyphenolic compound that exists in Polygonum cuspidatum, grapes, peanuts and berries, as well as their manufactured products, especially red wine. Resveratrol is a pharmacologically active compound that interacts with multiple targets in a variety of cardiovascular disease models to exert protective effects or induce a reduction in cardiovascular risks parameters. This review attempts to primarily serve to summarize the current research findings regarding the putative cardioprotective effects of resveratrol and the molecular pathways underlying these effects. One intent is to hopefully provide a relatively comprehensive resource for clues that may prompt ideas for additional mechanistic studies which might further elucidate and strengthen the role of the stilbene family of compounds in cardiovascular disease and cardioprotection. Model systems that incorporate a significant functional association with tissues outside of the cardiovascular system proper, such as adipose (cell culture, obesity models) and pancreatic (diabetes) tissues, were reviewed, and the molecular pathways and/or targets related to these models and influenced by resveratrol are discussed. Because the body of work encompassing the stilbenes and other phytochemicals in the context of longevity and the ability to presumably mitigate a plethora of afflictions is replete with conflicting information and controversy, especially so with respect to the human response, we tried to remain as neutral as possible in compiling and presenting the more current data with minimal commentary, permitting the reader free reign to extract the knowledge most helpful to their own investigations.

p38 mitogen-activated protein kinase is involved in arginase-II-mediated eNOS-uncoupling in obesity

Background

Endothelial nitric oxide synthase (eNOS)-uncoupling links obesity-associated insulin resistance and type-II diabetes to the increased incidence of cardiovascular disease. Studies have indicated that increased arginase is involved in eNOS-uncoupling through competing with the substrate L-arginine. Given that arginase-II (Arg-II) exerts some of its biological functions through crosstalk with signal transduction pathways, and that p38 mitogen-activated protein kinase (p38mapk) is involved in eNOS-uncoupling, we investigated here whether p38mapk is involved in Arg-II-mediated eNOS-uncoupling in a high fat diet (HFD)-induced obesity mouse model.

Methods

Obesity was induced in wild type (WT) and Arg-II-deficient (Arg-II^-/-) mice on C57BL/6 J background by high-fat diet (HFD, 55% fat) for 14 weeks starting from age of 7 weeks. The entire aortas were isolated and subjected to 1) immunoblotting analysis of the protein level of eNOS, Arg-II and p38mapk activation; 2) arginase activity assay; 3) endothelium-dependent and independent vasomotor responses; 4) en face staining of superoxide anion and NO production with Dihydroethidium and 4,5-Diaminofluorescein Diacetate, respectively, to assess eNOS-uncoupling. To evaluate the role of p38mapk, isolated aortas were treated with p38mapk inhibitor SB203580 (10 μmol/L, 1 h) prior to the analysis. In addition, the role of p38mapk in Arg-II-induced eNOS-uncoupling was investigated in cultured human endothelial cells overexpressing Arg-II in the absence or presence of shRNA against p38mapk.

Results

HFD enhanced Arg-II expression/activity and p38mapk activity, which was associated with eNOS-uncoupling as revealed by decreased NO and enhanced L-NAME-inhibitable superoxide in aortas of WT obese mice. In accordance, WT obese mice revealed decreased endothelium-dependent relaxations to acetylcholine despite of higher eNOS protein level, whereas Arg-II^-/- obese mice were protected from HFD-induced eNOS-uncoupling and endothelial dysfunction, which was associated with reduced p38mapk activation in aortas of the Arg-II^-/- obese mice. Moreover, overexpression of Arg-II in human endothelial cells caused eNOS-uncoupling and augmented p38mapk activation. The Arg-II-induced eNOS-uncoupling was prevented by silencing p38mapk. Furthermore, pharmacological inhibition of p38mapk recouples eNOS in isolated aortas from WT obese mice.

Conclusions

Taking together, we demonstrate here for the first time that Arg-II causes eNOS-uncoupling through activation of p38 mapk in HFD-induced obesity.

Adenosine kinase inhibition protects the kidney against streptozotocin-induced diabetes through anti-inflammatory and anti-oxidant mechanisms

Adenosine provides anti-inflammatory effects in cardiovascular disease via the activation of adenosine A2A receptors; however, the physiological effect of adenosine could be limited due to its phosphorylation by adenosine kinase. We hypothesized that inhibition of adenosine kinase exacerbates extracellular adenosine levels to reduce renal inflammation and injury in streptozotocin-induced diabetes. Diabetes was induced in male C57BL/6 mice by daily injection of streptozotocin (50mg/kg/day, i.p. for 5 days). Control and diabetic mice were then treated with the adenosine kinase inhibitor ABT702 (1.5mg/kg, i.p. two times a week for 8 weeks, n=7-8/group) or the vehicle (5% DMSO). ABT702 treatment reduced blood glucose level in diabetic mice (∼20%; P<0.05). ABT702 also reduced albuminuria and markers of glomerular injury, nephrinuria and podocalyxin excretion levels, in diabetic mice. Renal NADPH oxidase activity and urinary thiobarbituric acid reactive substances (TBARS) excretion, indices of oxidative stress, were also elevated in diabetic mice and ABT702 significantly reduced these changes. ABT702 increased renal endothelial nitric oxide synthase expression (eNOS) and nitrate/nitrite excretion levels in diabetic mice. In addition, the diabetic mice displayed an increase in renal macrophage infiltration, in association with increased renal NFκB activation. Importantly, treatment with ABT702 significantly reduced all these inflammatory parameters (P<0.05). Furthermore, ABT702 decreased glomerular permeability and inflammation and restored the decrease in glomerular occludin expression in vitro in high glucose treated human glomerular endothelial cells. Collectively, the results suggest that the reno-protective effects of ABT702 could be attributed to the reduction in renal inflammation and oxidative stress in diabetic mice.

Resveratrol and clinical trials: the crossroad from in vitro studies to human evidence

Resveratrol (3,5,4’-trihydroxy-trans-stilbene) is a non-flavonoid polyphenol that may be present in a limited number of food-stuffs such as grapes and red wine. Resveratrol has been reported to exert a plethora of health benefits through many different mechanisms of action. This versatility and presence in the human diet have drawn the worldwide attention of many research groups over the past twenty years, which has resulted in a huge output of in vitro and animal (preclinical) studies. In line with this expectation, many resveratrol-based nutraceuticals are consumed all over the world with questionable clinical/scientific support. In fact, the confirmation of these benefits in humans through randomized clinical trials is still very limited. The vast majority of preclinical studies have been performed using assay conditions with a questionable extrapolation to humans, i.e. too high concentrations with potential safety concerns (adverse effects and drug interactions), short-term exposures, in vitro tests carried out with non-physiological metabolites and/or concentrations, etc. Unfortunately, all these hypothesis-generating studies have contributed to increased the number of ‘potential’ benefits and mechanisms of resveratrol but confirmation in humans is very limited. Therefore, there are many issues that should be addressed to avoid an apparent endless loop in resveratrol research. The so-called ‘Resveratrol Paradox’, i.e., low bioavailability but high bioactivity, is a conundrum not yet solved in which the final responsible actor (if any) for the exerted effects has not yet been unequivocally identified. It is becoming evident that resveratrol exerts cardioprotective benefits through the improvement of inflammatory markers, atherogenic profile, glucose metabolism and endothelial function. However, safety concerns remain unsolved regarding chronic consumption of high RES doses, specially in medicated people. This review will focus on the currently available evidence regarding resveratrol’s effects on humans obtained from randomized clinical trials. In addition, we will provide a critical outlook for further research on this molecule that is evolving from a minor dietary compound to a possible multi-target therapeutic drug.