Cyclooxygenase-2-dependent oxidative stress mediates palmitate-induced impairment of endothelium-dependent relaxations in mouse arteries

Interactions of N-Mannich Bases of Pyrrolo[3,4-c]pyrrole with Artificial Models of Cell Membranes and Plasma Proteins, Evaluation of Anti-Inflammatory and Antioxidant Activity

Despite the widespread and easy access to NSAIDs, effective and safe treatment of various inflammatory disorders is still a serious challenge because of the severe adverse effects distinctive to these drugs. The Mannich base derivatives of pyrrolo[3,4-c]pyrrole are potent, preferential COX-2 inhibitors with a COX-2/COX-1 inhibitory ratio better than meloxicam. Therefore, we chose the six most promising molecules and subjected them to further in-depth research. The current study presents the extensive biological, spectroscopic and in silico evaluation of the activity and physicochemical properties of pyrrolo[3,4-c]pyrrole derivatives. Aware of the advantages of dual COX-LOX inhibition, we investigated the 15-LOX inhibitory activity of these molecules. We also examined their antioxidant effect in several in vitro experiments in a protection and regeneration model. Furthermore, we defined how studied compounds interact with artificial models of cell membranes, which is extremely important for drugs administered orally with an intracellular target. The interactions and binding mode of the derivatives with the most abundant plasma proteins-human serum albumin and alpha-1-acid glycoprotein-are also described. Finally, we used computational techniques to evaluate their pharmacokinetic properties. According to the obtained results, we can state that pyrrolo[3,4-c]pyrrole derivatives are promising anti-inflammatory and antioxidant agents with potentially good membrane permeability.

Targeting endothelial dysfunction and inflammation

Vascular endothelium maintains vascular homeostasis through liberating a spectrum of vasoactive molecules, both protective and harmful regulators of vascular tone, structural remodeling, inflammation and atherogenesis. An intricate balance between endothelium-derived relaxing factors (nitric oxide, prostacyclin and endothelium-derived hyperpolarizing factor) and endothelium-derived contracting factors (superoxide anion, endothelin-1 and constrictive prostaglandins) tightly regulates vascular function. Disruption of such balance signifies endothelial dysfunction, a critical contributor in aging and chronic cardiometabolic disorders, such as obesity, diabetes, hypertension, dyslipidemia and atherosclerotic vascular diseases. Among many proposed cellular and molecular mechanisms causing endothelial dysfunction, oxidative stress and inflammation are often the pivotal players and they are naturally considered as useful targets for intervention in patients with cardiovascular and metabolic diseases. In this article, we provide a recent update on the therapeutic values of pharmacological agents, such as cyclooxygenase-2 inhibitors, renin-angiotensin-system inhibitors, bone morphogenic protein 4 inhibitors, peroxisome proliferator-activated receptor δ agonists, and glucagon-like peptide 1-elevating drugs, and the physiological factors, particularly hemodynamic forces, that improve endothelial function by targeting endothelial oxidative stress and inflammation.

Effects of Arachidonic Acid Metabolites on Cardiovascular Health and Disease

Arachidonic acid (AA) is an essential fatty acid that is released by phospholipids in cell membranes and metabolized by cyclooxygenase (COX), cytochrome P450 (CYP) enzymes, and lipid oxygenase (LOX) pathways to regulate complex cardiovascular function under physiological and pathological conditions. Various AA metabolites include prostaglandins, prostacyclin, thromboxanes, hydroxyeicosatetraenoic acids, leukotrienes, lipoxins, and epoxyeicosatrienoic acids. The AA metabolites play important and differential roles in the modulation of vascular tone, and cardiovascular complications including atherosclerosis, hypertension, and myocardial infarction upon actions to different receptors and vascular beds. This article reviews the roles of AA metabolism in cardiovascular health and disease as well as their potential therapeutic implication.

Assessing the Optimum Level of Supplementation with Camelina Seeds in Ewes' Diets to Improve Milk Quality

Camelina sativa seeds are rich in bioactive compounds such as polyunsaturated fatty acids (PUFA) and antioxidants, thus, their supplementation in ewes’ diets, may be an effective way to develop high nutritional dairy products. Therefore, the present study investigates the effect of the dietary inclusion of Camelina sativa seeds in ewes’ oxidative status and milk quality. Forty-eight dairy Chios ewes were divided into four homogenous groups and were fed individually. The concentrate of the control group (CON) had no inclusion of Camelina seeds, while the treatment groups (CSS6, CSS11, CSS16) were supplemented with 6%, 11%, and 16%, respectively. Including Camelina seeds in 6% and 11%, had no impact on milk performance, while in the CSS16, milk fat was significantly decreased compared to the CON. Supplementing Camelina seeds improved milk quality from a human health perspective by modifying the content of saturated fatty acid, the proportions of α-linolenic (C_{18:3 n-3}), and C_{18:2 cis-9, trans-11} (CLA), and the ω6/ω3 ratio. Furthermore, the activity of catalase (CAT) was significantly increased in the CSS11 and CSS16, and superoxide dismutase (SOD) activity also significantly upsurged in the CSS16. Still, the levels of malondialdehyde (MDA) were significantly increased in the CSS11 compared to the CON and CSS6, and in the CSS16 compared to the CSS6. In CSS16, protein carbonyls were significantly increased. Finally, in the CSS-fed ewes, milk oxidative stability was fortified, as suggested by the modifications in the activities of SOD, CAT, and glutathione peroxidase (GSH-Px), in the antioxidant capacity, and the oxidative stress biomarkers. Consequently, the incorporation of 6% Camelina seeds in the concentrates of ewes improves milk’s fatty acid profile and oxidative status. However, more research is required regarding the possible negative effects of the constant consumption of Camelina seeds by ewes.

Homocysteine Causes Endothelial Dysfunction via Inflammatory Factor-Mediated Activation of Epithelial Sodium Channel (ENaC)

Background

Hyperhomocysteinemia (HHcy) causes cardiovascular diseases via regulating inflammatory responses. We investigated whether and how the epithelial sodium channel (ENaC), a recently identified ion channel in endothelial cells, plays a role in HHcy-induced endothelial dysfunction.

Methods

Cell-attached patch-clamp recording in acute split-open aortic endothelial cells, western blot, confocal imaging, and wire myograph combined with pharmacological approaches were used to determine whether HHcy-mediated inflammatory signaling leads to endothelial dysfunction via stimulating ENaC.

Results

The data showed that 4 weeks after L-methionine diet the levels of plasma Hcy were significantly increased and the ENaC was dramatically activated in mouse aortic endothelial cells. Administration of benzamil, a specific ENaC blocker, ameliorated L-methionine diet-induced impairment of endothelium-dependent relaxation (EDR) and reversed Hcy-induced increase in ENaC activity. Pharmacological inhibition of NADPH oxidase, reactive oxygen species (ROS), cyclooxygenase-2 (COX-2)/thromboxane B2 (TXB2), or serum/glucocorticoid regulated kinase 1 (SGK1) effectively attenuated both the Hcy-induced activation of endothelial ENaC and impairment of EDR. Our in vitro data showed that both NADPH oxidase inhibitor and an ROS scavenger reversed Hcy-induced increase in COX-2 expression in human umbilical vein endothelial cells (HUVECs). Moreover, Hcy-induced increase in expression levels of SGK-1, phosphorylated-SGK-1, and phosphorylated neural precursor cell-expressed developmentally downregulated protein 4-2 (p-Nedd4-2) in HUVECs were significantly blunted by a COX-2 inhibitor.

Conclusion

We show that Hcy activates endothelial ENaC and subsequently impairs EDR of mouse aorta, via ROS/COX-2-dependent activation of SGK-1/Nedd4-2 signaling. Our study provides a rational that blockade of the endothelial ENaC could be potential method to prevent and/or to treat Hcy-induced cardiovascular disease.

Effects of Inclusion of Schizochytrium spp. and Forage-to-Concentrate Ratios on Goats' Milk Quality and Oxidative Status

Although the dietary inclusion level of polyunsaturated fatty acids (PUFA) and the forage: concentrate (F:C) ratio affect milk quality, their interaction has not been broadly studied. To address such gaps and limitations a two-phase trial using twenty-two dairy goats was carried out. During the first phase, both groups (20 HF n = 11; high forage and 20 HG n = 11; high grain) were supplemented with 20 g Schizochytrium spp./goat/day. The 20 HF group consumed a diet with F:C ratio 60:40 and the 20 HG-diet consisted of F:C = 40:60. In the second phase, the supplementation level of Schizochytrium spp. was increased to 40 g/day/goat while the F:C ratio between the two groups were remained identical (40 HF n = 11; high forage and 40 HG n = 11; high grain). Neither the Schizochytrium spp. supplementation levels (20 vs. 40) nor the F:C ratio (60:40 vs. 40:60) affected milk performance. The high microalgae level (40 g) in combination with high grain diet (40 HG) modified the proportions of docosahexaenoic acid (DHA), docosapentaenoic acid (DPA), and conjugated linoleic acid (CLA) and the ω3/ω6 ratio in milk, to a beneficial manner according to human health recommendation guidelines. However, the highest inclusion level of Schizochytrium spp. (40 g) and foremost in combination with the high grain diets (40 HG) induced an oxidative response as observed by the increased protein carbonyls (CP) and malondialdehyde (MDA) levels in milk and blood plasma indicating severe limitations for a long-term, on-farm application. In conclusion, the supplementation with 20 g Schizochytrium spp. and high forage diet (60:40) appears to be an ideal formula to enrich dairy products with essential biomolecules for human health without adversely affect milk oxidative stability.

Design, Synthesis and Comprehensive Investigations of Pyrrolo[3,4-d]pyridazinone-Based 1,3,4-Oxadiazole as New Class of Selective COX-2 Inhibitors

The long-term use of Non-Steroidal Anti-Inflammatory Drugs (NSAIDs) in treatment of different chronic inflammatory disorders is strongly restricted by their serious gastrointestinal adverse effects. Therefore, there is still an urgent need to search for new, safe, and efficient anti-inflammatory agents. Previously, we have reported the Mannich base-type derivatives of pyrrolo[3,4-d]pyridazinone which strongly inhibit cyclooxygenase, have better affinity to COX-2 isoenzyme and exert promising anti-oxidant activity. These findings encouraged us to perform further optimization of that structure. Herein, we present the design, synthesis, molecular docking, spectroscopic, and biological studies of novel pyrrolo[3,4-d]pyridazinone derivatives bearing 4-aryl-1-(1-oxoethyl)piperazine pharmacophore 5a,b–6a,b. The new compounds were obtained via convenient, efficient, one-pot synthesis. According to in vitro evaluations, novel molecules exert no cytotoxicity and act as selective COX-2 inhibitors. These findings stay in good correlation with molecular modeling results, which additionally showed that investigated compounds take a position in the active site of COX-2 very similar to Meloxicam. Moreover, all derivatives reduce the increased level of reactive oxygen and nitrogen species and prevent DNA strand breaks caused by oxidative stress. Finally, performed spectroscopic and molecular docking studies demonstrated that new compound interactions with bovine serum albumin (BSA) are moderate, formation of complexes is in one-to-one ratio, and binding site II (subdomain IIIA) is favorable.

Differential effects of saturated and unsaturated fatty acids on vascular reactivity in isolated mesenteric and femoral arteries of rats

Free fatty acid (FFA) intake regulates blood pressure and vascular reactivity but its direct effect on contractility of systemic arteries is not well understood. We investigated the effects of saturated fatty acid (SFA, palmitic acid), polyunsaturated fatty acid (PUFA, linoleic acid), and monounsaturated fatty acid (MUFA, oleic acid) on the contractility of isolated mesenteric (MA) and deep femoral arteries (DFA) of Sprague-Dawley rats. Isolated MA and DFA were mounted on a dual wire myograph and phenylephrine (PhE, 1-10 µM) concentration-dependent contraction was obtained with or without FFAs. Incubation with 100 µM of palmitic acid significantly increased PhE-induced contraction in both arteries. In MA, treatment with 100 µM of linoleic acid decreased 1 µM PhE-induced contraction while increasing the response to higher PhE concentrations. In DFA, linoleic acid slightly decreased PhE-induced contraction while 200 µM oleic acid significantly decreased it. In MA, oleic acid reduced contraction at low PhE concentration (1 and 2 µM) while increasing it at 10 µM PhE. Perplexingly, depolarization by 40 mM KCl-induced contraction of MA was commonly enhanced by the three fatty acids. The 40 mM KCl-contraction of DFA was also augmented by linoleic and oleic acids while not affected by palmitic acid. SFA persistently increased alpha-adrenergic contraction of systemic arteries whereas PUFA and MUFA attenuated PhE-induced contraction of skeletal arteries. PUFA and MUFA concentration-dependent dual effects on MA suggest differential mechanisms depending on the types of arteries. Further studies are needed to elucidate underlying mechanisms of the various effects of FFA on systemic arteries.

Maternal vitamin D deficiency increases the thromboxane/prostacyclin ratio through alterations in the one-carbon cycle in Wistar rats

This study aims to test the hypothesis that vitamin D deficiency can influence long-chain polyunsaturated fatty acid metabolism through alterations in the one-carbon cycle. Wistar rats (n = 8 per group) were given either a control (1,000 IU D3/kg diet) or a vitamin D deficient (VDD) (0 IU D3/kg diet) diet from pre-pregnancy to delivery. On day 20 of gestation, pregnant female rats were delivered by C-section to collect placenta and blood. VDD group demonstrated high serum parathyroid hormone, low serum phosphate, low plasma folate, higher plasma homocysteine, and higher plasma malondialdehyde levels (P < 0.05 for all) as compared to control. Lower protein levels of placental cystathionine-β-synthase enzyme (P < 0.05) were observed in the VDD group as compared to control. VDD group demonstrated higher placental mRNA levels of the enzymes phospholipase A₂ and cyclooxygenase-2 (P < 0.05 for both) as compared to control. Protein levels of the enzymes phospholipase A₂ and cyclooxygenase-2 were lower (P < 0.05 for both) in the VDD group as compared to the control group. The ratio of thromboxane B₂ and 6-keto prostaglandin F_1α in serum was higher (P < 0.05) in the VDD group as compared to control; although the serum levels of 6-keto prostaglandin F_1α and thromboxane B₂ were similar in both the groups. Our findings suggest that increased oxidative stress due to maternal vitamin D deficiency results in the imbalance between the vasoconstrictor (thromboxane B₂ ) and vasodilator (6-keto prostaglandin F_1α ) eicosanoids, which may lead to endothelial dysfunction and poor pregnancy outcome. © 2019 BioFactors, 45 (4):548-555, 2019.

Biological Evaluation and Molecular Docking Studies of Dimethylpyridine Derivatives

Cyclooxygenase inhibitors as anti-inflammatory agents can be used in chemoprevention. Many in vitro and in vivo studies on human and animal models have explained the mechanisms of the chemopreventive effect of COX inhibitors such as: induction of apoptosis, inhibition of neoplasia, angiogenesis suppression, induction of cell cycle inhibition and inhibition of the expression of peroxisome proliferator-activated receptors. Here, biological evaluation of twelve different Schiff base derivatives of N-(2-hydrazine-2-oxoethyl)-4,6-dimethyl-2-sulfanylpyridine- 3-carboxamide are presented. Their in vitro anti-COX-1/COX-2, antioxidant and anticancer activities were studied. The molecular docking study was performed in order to understand the binding interaction of compounds in the active site of cyclooxygenases. Compounds PS18 and PS33 showed a significant inhibitory activity on COX-1 at lower concentrations compared to meloxicam and piroxicam. The IC₅₀ of COX-1 of these compounds was 57.3 µM for PS18 and 51.8 µM for PS33. Out of the tested compounds, the highest therapeutic index was demonstrated by PS18, PS19, PS33, PS40 and PS41. Lower molar concentrations of these compounds inhibit the growth of cancer cells while not inhibiting the healthy cells. Compounds PS18, PS19 and PS33 simultaneously demonstrated a statistically-significant inhibition of COX-1 or COX-2. This opens up the possibility of applying these compounds in the chemoprevention of cancer.

AFM-based detection of glycocalyx degradation and endothelial stiffening in the db/db mouse model of diabetes

Degradation of the glycocalyx and stiffening of endothelium are important pathophysiological components of endothelial dysfunction. However, to our knowledge, these events have not been investigated in tandem in experimental diabetes. Here, the mechanical properties of the glycocalyx and endothelium in ex vivo mouse aorta were determined simultaneously in indentation experiments with an atomic force microscope (AFM) for diabetic db/db and control db/+ mice at ages of 11–19 weeks. To analyze highly heterogeneous aorta samples, we developed a tailored classification procedure of indentation data based on a bi-layer brush model supplemented with Hertz model for quantification of nanomechanics of endothelial regions with and without the glycocalyx surface. In db/db mice, marked endothelial stiffening and reduced glycocalyx coverage were present already in 11-week-old mice and persisted in older animals. In contrast, reduction of the effective glycocalyx length was progressive and was most pronounced in 19-week-old db/db mice. The reduction of the glycocalyx length correlated with an increasing level of glycated haemoglobin and decreased endothelial NO production. In conclusion, AFM nanoindentation analysis revealed that stiffening of endothelial cells and diminished glycocalyx coverage occurred in early diabetes and were followed by the reduction of the glycocalyx length that correlated with diabetes progression.

Correlation between Oxidative Stress, Nutrition, and Cancer Initiation

Inadequate or excessive nutrient consumption leads to oxidative stress, which may disrupt oxidative homeostasis, activate a cascade of molecular pathways, and alter the metabolic status of various tissues. Several foods and consumption patterns have been associated with various cancers and approximately 30-35% of the cancer cases are correlated with overnutrition or malnutrition. However, several contradictory studies are available regarding the association between diet and cancer risk, which remains to be elucidated. Concurrently, oxidative stress is a crucial factor for cancer progression and therapy. Nutritional oxidative stress may be induced by an imbalance between antioxidant defense and pro-oxidant load due to inadequate or excess nutrient supply. Oxidative stress is a physiological state where high levels of reactive oxygen species (ROS) and free radicals are generated. Several signaling pathways associated with carcinogenesis can additionally control ROS generation and regulate ROS downstream mechanisms, which could have potential implications in anticancer research. Cancer initiation may be modulated by the nutrition-mediated elevation in ROS levels, which can stimulate cancer initiation by triggering DNA mutations, damage, and pro-oncogenic signaling. Therefore, in this review, we have provided an overview of the relationship between nutrition, oxidative stress, and cancer initiation, and evaluated the impact of nutrient-mediated regulation of antioxidant capability against cancer therapy.

Planarian regeneration in space: Persistent anatomical, behavioral, and bacteriological changes induced by space travel

Regeneration is regulated not only by chemical signals but also by physical processes, such as bioelectric gradients. How these may change in the absence of the normal gravitational and geomagnetic fields is largely unknown. Planarian flatworms were moved to the International Space Station for 5 weeks, immediately after removing their heads and tails. A control group in spring water remained on Earth. No manipulation of the planaria occurred while they were in orbit, and space‐exposed worms were returned to our laboratory for analysis. One animal out of 15 regenerated into a double‐headed phenotype—normally an extremely rare event. Remarkably, amputating this double‐headed worm again, in plain water, resulted again in the double‐headed phenotype. Moreover, even when tested 20 months after return to Earth, the space‐exposed worms displayed significant quantitative differences in behavior and microbiome composition. These observations may have implications for human and animal space travelers, but could also elucidate how microgravity and hypomagnetic environments could be used to trigger desired morphological, neurological, physiological, and bacteriomic changes for various regenerative and bioengineering applications.

Palmitic acid triggers cell apoptosis in RGC-5 retinal ganglion cells through the Akt/FoxO1 signaling pathway

Hallmarks of the pathophysiology of glaucoma are oxidative stress and apoptotic death of retinal ganglion cells (RGCs). Lipotoxicity, involving a series of pathological cellular responses after exposure to elevated levels of fatty acids, leads to oxidative stress and cell death in various cell types. The phosphatidylinositol-3-kinase/protein kinase B/Forkhead box O1 (PI3K/Akt/FoxO1) pathway is crucial for cell survival and apoptosis. More importantly, FoxO1 gene has been reported to confer relatively higher risks for eye diseases including glaucoma. However, little information is available regarding the interaction between FoxO1 and RGC apoptosis, much less a precise mechanism. In the present study, immortalized rat retinal ganglion cell line 5 (RGC-5) was used as a model to study the toxicity of palmitic acid (PA), as well as underlying mechanisms. We found that PA exposure significantly decreased cell viability by enhancing apoptosis in RGC-5 cells, as measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and flow cytometry. PA also induced a remarkable increase in reactive oxygen species and malondialdehyde. Moreover, PA significantly decreased the level of phospho-Akt and phospho-FoxO1 in cells. Finally, shRNA knockdown and plasmid overexpression studies displayed that downregulation of Akt protein or upregulation of FoxO1 protein augmented cell death, while knockdown of FoxO1 or overexpression of Akt1 abolished PA-induced cell death. Collectively, our results indicated that PA-induced cell death is mediated through modulation of Akt/FoxO1 pathway activity.

A piperazidine derivative of 23-hydroxy betulinic acid induces a mitochondria-derived ROS burst to trigger apoptotic cell death in hepatocellular carcinoma cells

BACKGROUND

Elevated production of reactive oxygen species (ROS) and an altered redox state have frequently been observed in hepatocellular carcinoma (HCC); therefore, selective killing of HCC cells by chemotherapeutic agents that stimulate ROS generation or impair antioxidant systems may be a feasible approach in HCC chemotherapy. Recently, betulinic acid and its derivatives have attracted attention because they showed anti-cancer effects via a ROS- and mitochondria-related mechanism. However, the source of ROS overproduction and the role of mitochondria were poorly identified, and the weak in vivo antitumour activity of these compounds limits their development as drugs.

METHODS

Cytotoxicity was detected using MTT assays. In vivo anti-HCC effects were assessed using nude mice bearing HepG2 tumour xenografts. Cell cycle analysis, apoptosis rate and mitochondrial membrane potential were measured by flow cytometry. ROS production was detected using a microplate reader or a fluorescence microscope. Changes in gene and protein levels were measured by RT-PCR and western blotting, respectively. Other assays were performed using related detection kits.

RESULTS

B5G9, a piperazidine derivative of 23-hydroxy betulinic acid (23-HBA), showed excellent in vivo anti-HCC effects, with a tumour growth inhibitory rate of greater than 80%, and no significant side effects. B5G9 stimulated the production of ROS, which were derived from the mitochondria, but it had no effect on various other antioxidant systems. Moreover, B5G9 induced mitochondrial dysfunction, which was characterized by morphological changes, membrane potential collapse, membrane permeabilization, and decreases in the O2 consumption rate and ATP production. Furthermore, mtDNA-depleted ρ0 HepG2 cells were less sensitive to B5G9 treatment than wt HepG2 cells, indicating the importance of mitochondria in B5G9-induced cell death.

CONCLUSION

We discovered a piperazidine derivative of 23-HBA, B5G9, with excellent anti-HCC effects both in vivo and in vitro and no obvious toxic effects. The underlying mechanism was associated with mitochondria-derived ROS overproduction, and mitochondria played essential roles in B5G9-induced cell death. This study identified a potential agent for anti-HCC therapy and elucidated the mitochondria-related mechanism of BA and its derivatives.

Quercetin Inhibits Peripheral and Spinal Cord Nociceptive Mechanisms to Reduce Intense Acute Swimming-Induced Muscle Pain in Mice

The present study aimed to evaluate the effects of the flavonoid quercetin (3,3´,4´,5,7-pentahydroxyflavone) in a mice model of intense acute swimming-induced muscle pain, which resembles delayed onset muscle soreness. Quercetin intraperitoneal (i.p.) treatment dose-dependently reduced muscle mechanical hyperalgesia. Quercetin inhibited myeloperoxidase (MPO) and N-acetyl-β-D- glucosaminidase (NAG) activities, cytokine production, oxidative stress, cyclooxygenase-2 (COX-2) and gp91^phox mRNA expression and muscle injury (creatinine kinase [CK] blood levels and myoblast determination protein [MyoD] mRNA expression) as well as inhibited NFκB activation and induced Nrf2 and HO-1 mRNA expression in the soleus muscle. Beyond inhibiting those peripheral effects, quercetin also inhibited spinal cord cytokine production, oxidative stress and glial cells activation (glial fibrillary acidic protein [GFAP] and ionized calcium-binding adapter molecule 1 [Iba-1] mRNA expression). Concluding, the present data demonstrate that quercetin is a potential molecule for the treatment of muscle pain conditions related to unaccustomed exercise.

Mesenchymal Stem Cells Ameliorated Glucolipotoxicity in HUVECs through TSG-6

Glucolipotoxicity is one of the critical causal factors of diabetic complications. Whether mesenchymal stem cells (MSCs) have effects on glucolipotoxicity in human umbilical vein endothelial cells (HUVECs) and mechanisms involved are unclear. Thirty mM glucose plus 100 μM palmitic acid was used to induce glucolipotoxicity in HUVECs. MSCs and HUVECs were co-cultured at the ratio of 1:5 via Transwell system. The mRNA expressions of inflammatory factors were detected by RT-qPCR. The productions of reactive oxygen species (ROS), cell cycle and apoptosis were analyzed by flow cytometry. The tumor necrosis factor-α stimulated protein 6 (TSG-6) was knockdown in MSCs by RNA interference. High glucose and palmitic acid remarkably impaired cell viability and tube formation capacity, as well as increased the mRNA expression of inflammatory factors, ROS levels, and cell apoptosis in HUVECs. MSC co-cultivation ameliorated these detrimental effects in HUVECs, but no effect on ROS production. Moreover, TSG-6 was dramatically up-regulated by high glucose and fatty acid stimulation in both MSCs and HUVECs. TSG-6 knockdown partially abolished the protection mediated by MSCs. MSCs had protective effects on high glucose and palmitic acid induced glucolipotoxicity in HUVECs, and TSG-6 secreted by MSCs was likely to play an important role in this process.

Insights into the molecular mechanisms of diabetes-induced endothelial dysfunction: focus on oxidative stress and endothelial progenitor cells

Diabetes mellitus is a heterogeneous, multifactorial, chronic disease characterized by hyperglycemia owing to insulin insufficiency and insulin resistance (IR). Recent epidemiological studies showed that the diabetes epidemic affects 382 million people worldwide in 2013, and this figure is expected to be 600 million people by 2035. Diabetes is associated with microvascular and macrovascular complications resulting in accelerated endothelial dysfunction (ED), atherosclerosis, and cardiovascular disease (CVD). Unfortunately, the complex pathophysiology of diabetic cardiovascular damage is not fully understood. Therefore, there is a clear need to better understand the molecular pathophysiology of ED in diabetes, and consequently, better treatment options and novel efficacious therapies could be identified. In the light of recent extensive research, we re-investigate the association between diabetes-associated metabolic disturbances (IR, subclinical inflammation, dyslipidemia, hyperglycemia, dysregulated production of adipokines, defective incretin and gut hormones production/action, and oxidative stress) and ED, focusing on oxidative stress and endothelial progenitor cells (EPCs). In addition, we re-emphasize that oxidative stress is the final common pathway that transduces signals from other conditions-either directly or indirectly-leading to ED and CVD.

MAP kinases and the inflammatory signaling cascade as targets for the treatment of endometriosis?

INTRODUCTION

The pathogenesis of endometriosis, a common benign disease, remains ill-defined, although it is clear that chronic inflammation plays a crucial role through mitogen-activated protein kinase (MAPK) signaling pathways. All current medical therapies for endometriosis are antigonadotropic, and therefore have a contraceptive effect. A concerted research effort is hence warranted with the aim of delivering novel therapeutics that reduces disease symptoms without blocking ovulation.

AREAS COVERED

The authors review the complex pathogenic mechanisms of chronic inflammation in endometriosis and their relationships with MAPK pathways. The authors conducted a literature search of descriptive and functional targeted validation of MAPK in the pathogenesis of endometriosis. The effects of MAPK inhibitors, which constitute potential agents for future treatments, are also described.

EXPERT OPINION

Preliminary studies have highlighted a crucial role for MAPK in driving endometriosis-related inflammation. MAPK inhibitors exhibit potent activity in terms of controlling growth of endometriosis lesions both in vitro and in animal models. As MAPK inhibitors are known to have a multitude of undesirable side effects, their use in humans has to be approached with great care. Indeed, use of these drugs would probably be limited to short exposures prior to surgery in cases involving the most severe disease phenotypes.

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.