Resveratrol restores lysophosphatidylcholine-induced loss of endothelium-dependent relaxation in rat aorta tissue coinciding with inhibition of extracellular-signal-regulated protein kinase activation

Marked Impairment of Endothelium-Dependent Digital Vasodilatations in Patients With Microvascular Angina

Objective:

It remains to be elucidated whether and how endothelial functions are impaired in peripheral circulation of patients with coronary functional disorders, such as vasospastic angina (VSA) and microvascular angina (MVA). We simultaneously examined endothelial functions of peripheral conduit and resistance arteries in patients with coronary functional disorders, with a special reference to NO and endothelium-dependent hyperpolarization factors.

Approach and Results:

Based on the results of invasive coronary acetylcholine testing and coronary physiological measurements, we divided 43 patients into 3 groups; VSA, MVA, and VSA+MVA. Endothelium-dependent vasodilatations of the brachial artery and fingertip arterioles to intra-arterial infusion of bradykinin were simultaneously evaluated by ultrasonography and peripheral arterial tonometry, respectively. To assess NO and endothelium-dependent hyperpolarization factors, measurements were repeated after oral aspirin and intra-arterial infusion of N G -monomethyl-L-arginine. Additionally, endothelium-independent vasodilatations to sublingual nitroglycerin and plasma levels of biomarkers for endothelial functions were measured. Surprisingly, digital vasodilatations to bradykinin were almost absent in patients with MVA alone and those with VSA+MVA compared with those with VSA alone. Mechanistically, both NO- and endothelium-dependent hyperpolarization–mediated digital vasodilatations were markedly impaired in patients with MVA alone. In contrast, endothelium-independent vasodilatations to nitroglycerin were comparable among the 3 groups. Plasma levels of soluble VCAM (vascular cell adhesion molecule)-1 were significantly higher in patients with MVA alone compared with those with VSA alone.

Conclusions:

These results provide the first evidence that both NO- and endothelium-dependent hyperpolarization–mediated digital vasodilatations are markedly impaired in MVA patients, suggesting that MVA is a cardiac manifestation of the systemic small artery disease.

t-Resveratrol Protects against Acute High Glucose Damage in Endothelial Cells

Postprandial hyperglycemia in diabetic and nondiabetic subjects is associated with endothelial dysfunction. Evidence shows that high glucose generates oxidative stress and a pro-inflammatory state promoting the development of cardiovascular diseases. trans-Resveratrol (t-RV) has been shown to reduce cardiovascular risk. To determine whether t-RV acts as a protector against acute high glucose (AHG)-induced damage, two in vitro models, rat aortic rings (RAR) and human umbilical vein endothelial cells (HUVEC) were used. RAR pretreated with AHG (25 mM D-glucose) for 3 h dramatically decreased the endothelium-dependent relaxation (EDR) induced by acetylcholine in phenylephrine (PE)-precontracted vessels. However, coincubation with t-RV significantly mitigated the damage induced by AHG on EDR. Pretreatment with AHG did not affect the vasodilation induced by sodium nitroprusside. HUVEC treated with t-RV decreased cytotoxicity and reduced radical oxygen species production induced by AHG. Taken together, these results suggest that t-RV can mitigate the AHG-induced EDR damage through a mechanism involving ROS scavenging and probably an increase in the bioavailability of NO.

GPR55 agonist lysophosphatidylinositol and lysophosphatidylcholine inhibit endothelial cell hyperpolarization via GPR-independent suppression of Na+-Ca2+ exchanger and endoplasmic reticulum Ca2+ refilling

Lysophosphatidylinositol (LPI) and lysophosphatidylcholine (LPC) are lipid signaling molecules that induce endothelium-dependent vasodilation. In addition, LPC suppresses acetylcholine (Ach)-induced responses. We aimed to determine the influence of LPC and LPI on hyperpolarizing responses in vitro and in situ endothelial cells (EC) and identify the underlying mechanisms. Using patch-clamp method, we show that LPI and LPC inhibit EC hyperpolarization to histamine and suppress Na+/Ca2+ exchanged (NCX) currents in a concentration-dependent manner. The inhibition is non-mode-specific and unaffected by intracellular GDPβS infusion and tempol, a superoxide dismutase mimetic. In excised mouse aorta, LPI strongly inhibits the sustained and the peak endothelial hyperpolarization induced by Ach, but not by SKA-31, an opener of Ca2+-dependent K+ channels of intermediate and small conductance. The hyperpolarizing responses to consecutive histamine applications are strongly reduced by NCX inhibition. In a Ca2+-re-addition protocol, bepridil, a NCX inhibitor, and KB-R7943, a blocker of reversed NCX, inhibit the hyperpolarizing responses to Ca2+-re-addition following Ca2+ stores depletion. These finding indicate that LPC and LPI inhibit endothelial hyperpolarization to Ach and histamine independently of G-protein coupled receptors and superoxide anions. Reversed NCX is critical for ER Ca2+ refilling in EC. The inhibition of NCX by LPI and LPC underlies diminished endothelium-dependent responses and endothelial dysfunction accompanied by increased levels of these lipids in the blood.

Sulforaphane protected the injury of human vascular endothelial cell induced by LPC through up-regulating endogenous antioxidants and phase II enzymes

Sulforaphane (SFN), which is an isothiocyanate (ITC) that is found in cruciferous vegetables, has received considerable attention because of its beneficial effects. In this study, the protection by SFN in the lysophosphatidylcholine (LPC)-induced injury of human vascular endothelial EA.hy.926 cells was investigated. ROS intensity was obtained by fluorescence microscopic imaging. Levels of MDA, GSH and the activity of SOD were determined spectrophotometrically. Expressions of GST, GSH-Px, TrxR and Nrf-2 proteins were measured by western blotting analysis. SFN largely decreased ROS production, similar to vitamin E. The MDA level was decreased by SFN to a level that was comparable to the negative group. Incubation with 0.5, 1.25, 2.5 μmol L(-1) SFN for 24 h restored the activity of SOD by 58%, 64%, and 123%, respectively. SOD activities were individually increased by 53%, 97%, 103% after treatment with 2.5 μmol L(-1) SFN for 12 h, 24 h, and 48 h, respectively. SFN restored and up-regulated the expressions of GST, GSH-Px and TrxR both in dose- and time-dependent ways. Although VE presents comparable induction of phase 2 enzymes as 1.25 μmol L(-1) SFN, it cannot induce the translocation of Nrf-2 to the nucleus. SFN protected the injury of vascular endothelial cell by LPC by enhancing anti-oxidative capabilities mediated by Nrf-2 translocation.

Anti-inflammatory effects of Crataeva nurvala Buch. Ham. are mediated via inactivation of ERK but not NF-κB

ETHNOPHARMACOLOGICAL RELEVANCE

Crataeva nurvala Buch. Ham. is an important medicinal plant in India, and its extracts and components were used to treat various inflammatory diseases, such as urinary tract infection, rheumatoid arthritis, and colitis. However, no systemic studies about anti-inflammatory effects of Crataeva nurvala Buch. Ham. and its underlying mechanisms of action have been reported. This study aimed to explore the anti-inflammatory effects of ethanol extracts of Crataeva nurvala Buch. Ham. (ECN).

MATERIALS AND METHODS

The non-cytotoxic and maximal effective concentration of ECN was determined by measuring the formation of formazan from water-soluble tetrazolium salt in living cells. The inhibitory effect of ECN on nitric oxide (NO) synthesis was measured using Griess reagent, and Enzyme-linked immunosorbent assay (ELISA) was used to measure secreted tumor necrosis factor (TNF)-α and interleukin (IL)-6 protein levels. Furthermore, reverse transcription polymerase chain reaction (RT-PCR) and Western blotting analysis were used to assess the mRNA and protein expression of each inflammatory mediator or relating signaling protein, respectively.

RESULTS

A non-cytotoxic concentration of ECN (≤200 μg/ml) significantly reduced the production of NO and IL-6, but not TNF-α, in lipopolysaccharides (LPS)-stimulated RAW 264.7 macrophages. Decreased production of NO by ECN was correlated with reduced expression of iNOS at the mRNA and protein levels. However, cyclooxygenase (COX)-2 expressions at mRNA and protein level were not regulated by ECN. The mRNA expression of IL-6 and IL-1β, but not TNF-α, was also inhibited by ECN treatment in LPS-stimulated RAW 264.7 macrophages. Reduced production of inflammatory mediators by ECN was followed by decreased activity of mitogen-activated protein kinases (MAPKs), especially extracellular signal-regulated kinase (ERK), but not nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB).

CONCLUSIONS

These results indicate that ECN inhibits LPS-induced inflammatory responses via negative regulation of ERK in murine macrophages, suggesting that ECN is a candidate for alleviating severe inflammation.

Resveratrol ameliorates low shear stress‑induced oxidative stress by suppressing ERK/eNOS‑Thr495 in endothelial cells

Fluid shear stress has been revealed to differentially regulate endothelial nitric oxide synthase (eNOS) distribution in vessels. eNOS, a key enzyme in controlling nitric oxide (NO) release, has a crucial role in mediating oxidative stress, and resveratrol (RSV)‑mediated eNOS also attenuates oxidative damage and suppresses endothelial dysfunction. To observe the protective effect of RSV on low shear stress (LSS)‑induced oxidative damage and the potential mechanisms involved, a parallel‑plate flow chamber, which imposed a low level of stress of 2 dynes/cm2 to cells, was employed. Reactive oxygen species (ROS), NO and apoptotic cells were examined in LSS‑treated endothelial cells (ECs) with or without RSV. Western blot analysis was used to examine LSS‑regulated eNOS‑Ser1177, Thr495 and Ser633, which were tightly associated with NO release. To further determine the underlying signaling pathways involved, extracellular signal‑regulated kinase (ERK), a possible upstream target of eNOS‑Thr495, was investigated, followed by examination of eNOS‑Thr495 in ERK‑inhibited cells. Additionally, eNOS mRNA expression levels were analyzed in cells challenged with LSS. The results revealed that RSV markedly decreased LSS‑induced oxidative damage in ECs. Furthermore, eNOS‑Ser1177 and Thr495 as well as phospho‑ERK were time‑dependently activated by LSS. The ERK inhibitor deactivated eNOS‑Thr495, which was accompanied by increased intracellular superoxide dismutase (SOD) levels. Of note, the activation effect of LSS on ERK/eNOS was markedly eliminated by RSV. In conclusion, RSV exerts antioxidant effects by suppressing LSS-activated ERK/eNOS and may provide a potential therapeutic target for atherosclerosis.

Protective effects of 7-difluoromethyl-5,4'-dimethoxygenistein against human aorta endothelial injury caused by lysophosphatidyl choline

7-Difluoromethyl-5,4'-dimethoxygenistein (DFMG) is an active new derivative of genistein (GEN). It has shown effective protection in vascular endothelial injury. To further investigate its potential protective effects and its mechanism probably related to atherosclerosis, in present study, human aorta endothelial cells (HAECs) were chosen and treated with various concentrations of lysophosphatidyl choline (LPC) to establish an experimental model. Results showed that 10.0 μmol/l of LPC was optimal for inducing HAEC injury. DFMG pretreatment was able to prevent HAEC injury induced by LPC and restore cell viability in a concentration-dependent manner. The protective efficacy of DFMG (10.0 μmol/l) was significantly greater than that of GEN (10.0 μmol/l) and vitamin E (50.0 μmol/l). The mechanisms underlying the protective effects of DFMG are related to the activation of the antioxidant enzymes superoxide dismutase (SOD) and glutathione peroxidase and to the clearance of intracellular reactive oxygen species. DFMG inhibits the apoptosis of HAECs mediated by LPC involving the blockage of the mitochondrial apoptotic pathway.