Vitamin E distribution and modulation of the physical state and function of pulmonary endothelial cell membranes

Mitigation of Hydrochloric Acid (HCl)-Induced Lung Injury in Mice by Aerosol Therapy of Surface-Active Nanovesicles Containing Antioxidant and Anti-inflammatory Drugs

Acute lung injury leading to alveolar inflammation and surfactant dysfunction remains a medical challenge. Surface-active lipid nanovesicles of 200-250 nm size with antioxidant D-α-tocopheryl polyethylene glycol 1000 succinate (TPGS) and anti-inflammatory drug dexamethasone disodium phosphate (DXP) dual combination (Dual-NV) were developed for delivery as aerosols by nebulization in acid lung injury models. Drug deposition studies showed Dual-NV deposited ∼2.5 times more DXP compared to equivalent DXP solution. Nanovesicles are actively internalized by A549 cells through ATP- and clathrin-dependent pathways. The nanovesicles could be phagocytosed by RAW 264.7 macrophages and were nonimmunogenic and did not elicit overproduction of TNF-α, IL-1β, and IL-6. Dual-NV aerosol therapy at 200 mg/kg body weight, in HCl acid-induced lung injury in mice, markedly reduced pulmonary hemorrhage and protein leakage and improved capillary (airway) patency to ∼96%. Dual-NV aerosol therapy also significantly lowered production of inflammatory cytokine IL-1β, IL-6, and TNF-α and reduced oxidative stress by ∼95% in the injured group. Surface-active Dual-NV aerosol therapy is promising for replenishing the dysfunctional surfactant pool and mitigating inflammation and oxidative stress in lung injuries.

Antioxidant activity of Antrodia camphorata on free radical-induced endothelial cell damage

AIM OF THE STUDY

Antrodia camphorata (A. camphorata) is well known in Taiwan as a traditional Chinese medicine. The purpose of this study is to evaluate the antioxidant activity of Antrodia camphorata on free radical-induced endothelial cell damage.

MATERIALS AND METHODS

In this study, a human umbilical vein endothelial cell (EC) culture system was used to evaluate the effects of the fermented culture broth of A. camphorata (FCBA) and aqueous extracts of mycelia from A. camphorata (AEMA) against the oxidative cell damage induced by the free-radical generator AAPH.

RESULTS

The present investigations show that FCBA (25-100 microg/mL) and AEMA (50-200 microg/mL) effectively protect the ECs from damage after exposure to 15 mM AAPH for 16h. However, cell viability was not affected in ECs under controlled conditions after FCBA or AEMA treatment. An increase in EC prostacyclin (PGI(2)) production in response to AAPH exposure was positively and negatively correlated with cell damage and FCBA/AEMA concentration, respectively. Both FCBA and AEMA treatment significantly inhibited AAPH-apoptotic cell death in the ECs, as evidence by reduced DNA fragmentation, cytochrome c release, caspase-3 activation, and dysregulation of Bcl-2 and Bax. Moreover, the AAPH-induced reductions in EC SOD activity and protein levels are prevented by FCBA and AEMA.

CONCLUSION

Our findings suggest that A. camphorata possesses antioxidant properties and improves endothelial function, further offering effective protection from atherosclerosis.

Antioxidant diet preserves endothelium-dependent vasodilatation in resistance arteries of hypercholesterolemic rabbits exposed to environmental tobacco smoke

Environmental tobacco smoke (ETS) has been shown to impair endothelium-dependent vasodilation in vitro. This study was performed to investigate the effect of ETS on acetylcholine (ACh)-mediated blood pressure changes in vivo. Seventeen New Zealand White rabbits were fed a cholesterol diet (0.3%) for 13 weeks. Ten animals were exposed to ETS for 6 h/day, and seven animals were not exposed to ETS (non-ETS). Four of the ETS and three of the non-ETS-exposed rabbits received an antioxidant vitamin diet before and during their cholesterol diet for 21 weeks. Six rabbits served as healthy controls. To determine endothelium-dependent and independent blood pressure (BP) responses, BP was measured through a Tygon catheter, inserted into the right carotid artery at baseline and after each of three incremental intravenous doses of norepinephrine (NE; 1, 4, and 20 microg/kg), ACh (3.3, 10, and 30 microg/kg), and nitroglycerin (NTG; 1, 10, and 40 microg/kg). After NE, BP increases were significantly attenuated in the ETS group (p = 0.001) but not in animals receiving the antioxidant supplement. At both the middle and high ACh concentrations, ETS (p = 0.03 and p = 0.01, respectively) and hypercholesterolemia (p = 0.03 and p = 0.06, respectively) attenuated ACh-induced reductions in BP. At the highest ACh concentration, vitamins enhanced the reduction in BP (p = 0.002) and blocked the effect of ETS (p = 0.04). Neither ETS nor vitamins influenced NTG-induced decreases in BP. A combined antioxidant-vitamin diet can preserve endothelium-dependent vasodilatation in the hypercholesterolemic rabbit exposed to ETS.

An esterification protocol for cis-parinaric acid-determined lipid peroxidation in immune cells

Loss of fluorescence from cis-parinaric acid (cPnA) is a sensitive indicator of lipid peroxidation. The purpose of this study was to utilize cPnA to determine, at the level of the intact immune cell, whether enrichment of membranes with polyunsaturated fatty acids (PUFA) increased lipid peroxidation. P388D1 macrophages were labeled by addition of cPnA as an ethanolic solution. Within two minutes of addition, in the absence-of serum, cPnA rapidly intercalated into the plasma membrane. Lipid peroxidation was initiated by addition of Fe(2+)-EDTA resulting in a dose-dependent decrease in fluorescence with increased oxidant concentration. Cells previously enriched with PUFA and labeled by intercalation showed no differences in spontaneous or Fe(2+)-induced lipid peroxidation. In separate experiments, 20 microM cPnA in ethanolic solution was injected into cell culture media containing 0.1% essentially fatty acid free bovine serum albumin (BSA). Cells were resuspended and incubated for 90 min at 37 degrees C. After washing with BSA to remove cPnA which had not incorporated, 0.5% (0.1 microM) of the added cPnA was found esterified within cellular lipids. This level of cPnA provided a 100-fold increase over basal autofluorescence levels. Cells labeled in this manner also lost fluorescence in a dose-dependent manner as levels of oxidant stress increased. Cells enriched with PUFA and labeled by esterification had significantly increased rates and total amounts of lipid peroxidation. Co-incubation with alpha-tocopherol and PUFA resulted in a decrease in lipid peroxidation which was not significantly different from control cells. In conclusion, esterification of cPnA into membrane phospholipids can sensitively detect changes in lipid peroxidation induced by alteration of membrane PUFA and/or vitamin E content.

Overexpression of plasma membrane annexin II in NO2-exposed pulmonary artery endothelial cells

Because exposure to nitrogen dioxide (NO2) alters plasma membrane structure and function in pulmonary artery endothelial cells (PAEC), we examined whether NO2 exposure is associated with upregulation of plasma membrane-specific proteins in PAEC. Exposure to 5 ppm NO2 for 24 h had no significant effect on total protein synthesis. However, two-dimensional gel electrophoresis of isolated plasma membranes from [35S]-methionine pulse-labeled PAEC exposed to NO2 for 24 h demonstrated 3- to 9-fold increases in the synthesis of several proteins with molecular masses of 36, 39, and 40 kDa compared with controls. N-terminal amino acid sequencing and immunodetection analysis identified the 36kDa plasma membrane protein as annexin II (lipocortin II). Northern blotting analysis demonstrated that the mRNA expression for annexin II in NO2-exposed cells was also increased. These results suggest that exposure to NO2 results in induction of plasma membrane annexin II, an important multifunctional calcium- and phospholipid-binding protein in PAEC.

Effect of vitamin E on human aortic endothelial cell responses to oxidative injury

Reactive oxygen species produced by the cells present in the arterial wall may cause oxidative damage to cellular components altering endothelial cell (EC) function. Changes in the EC function appear to play a key role in the pathogenesis of atherosclerosis. Human aortic endothelial cells (HAEC) were employed to investigate the protective role of vitamin E upon exposure of endothelial cells to oxidative stress in vitro. HAEC assimilate d-alpha-tocopherol from the media in a dose-dependent manner. Exposure of HAEC to 16.5 mM of the free radical generator 2,2'-azobis (2-amidinopropane) hydrochloride (AAPH) for 16 h decreased cell viability (assessed by trypan blue exclusion) from 90 to 28%. HAEC preincubated with vitamin E at 15, 30, and 60 microM prior to the AAPH exposure resulted in a dose-dependent increase in resistance to oxidative stress and increased cell viability by 37, 66, and 85%, respectively. An increase in prostacyclin (PGI2) production by HAEC in response to AAPH exposure was correlated positively with cell damage and negatively with vitamin E concentration. Interleukin (IL)-1 production also increased in parallel with cell damage induced by AAPH. Vitamin E treatment significantly reduced IL-1 production after AAPH exposure. This modulatory role of vitamin E on HAEC function following exposure to an oxidative stress may reflect its antioxidant protection against lipid peroxidation.

Effects of vitamin E deficiency on vasomotor activity and ultrastructural organisation of rat thoracic aorta

1. The effects of vitamin E deficiency were evaluated in aortic rings isolated from rats maintained on a diet deficient in vitamin E. 2. Endothelium-dependent vasodilator responses to acetylcholine (ACh) and calcium ionophore, A23187, were reduced in preparations from treated animals, compared to the age-matched controls. The maximal vasodilation to ACh was 66.4 +/- 9 (n = 4) and 38.8 +/- 7 (n = 4) % in control and 10 month-treated preparations, respectively. 3. The endothelium-independent vasodilator responses to sodium nitroprusside as well as the concentration-dependent contractile responses to noradrenaline, did not differ between treated and control preparations. 4. Electron microscopic examination of vascular segments and revealed that, following vitamin E deficiency, normal tissue organisation was disrupted, the endothelial monolayer either not being in contact with the underlying tissue or being absent in most of the areas analysed. 5. It is concluded that during vitamin E deficiency both morphological disruption and functional impairment of endothelium occur without observable modification of muscle cell function and morphology.

Failure of vitamin E to protect cultured human arterial smooth muscle cells against oxysterol-induced cytotoxicity

OBJECTIVE

The cytotoxicity of oxysterols including 7 alpha-hydroxycholesterol (7 alpha OHC), 7 beta-hydroxycholesterol (7 beta OHC), cholesterol 5 alpha,6 alpha-epoxide (alpha epoxyC), cholesterol 5 beta,6 beta-epoxide (beta epoxyC), 7-ketocholesterol (7ketoC), 26-hydroxycholesterol (26OHC), cholesterol-3 beta,5 alpha,6 beta-triol (TriolC) and the possible protecting effect of vitamin E on 26OHC-induced cytotoxicity were investigated in smooth muscle cells isolated from the arteries of human umbilical cords.

METHODS

To study the cytotoxicity of oxysterols, the cells were incubated with each oxysterol at a level of 10 micrograms/ml from 24 to 120 hours, then 45Ca++ uptake, cytosolic free Ca++ level, [3H]thymidine incorporation, total DNA content and viable cell number were measured. Cholesterol was used as a control. For tracing the possible origin of cytotoxicity of 26OHC, cholesterol, phospholipid and 26OHC content in the membrane were investigated from 24 to 72 hours. For determining whether antioxidants had a protective effect against the cytotoxicity of 26OHC, vitamin E and butylated hydroxytoluene (BHT) were used.

RESULTS

The results indicated that the oxysterols elevated 45Ca++ uptake and cytosolic free Ca++ level, but diminished [3H]thymidine incorporation, total DNA content and viable cell number. 26OHC lowered the cholesterol content of the membrane and incorporated into the membrane after 24 hours of the incubation, but did not alter the total phospholipid content of the membrane until 72 hours. Neither vitamin E or BHT significantly protected the cells from the 26OHC-induced alterations.

CONCLUSION

We suggest that the cytotoxicity of oxysterols, which might result in an alteration in Ca++ ion flow into the cell by decreasing cholesterol content and incorporating oxysterol itself into the membranes, could not be protected by vitamin E.

Effect of phospholipid acyl chain modulation on vitamin E incorporation into pulmonary artery endothelial cell membranes

Incorporation of vitamin E (alpha-tocopherol) was measured in total membranes of pulmonary artery endothelial cells (PAEC) following treatment with eight synthetic phosphatidylethanolamines (PE) (Palmitoyloleoyl, 16:0-18:1 PE1; distearoyl, 18:0-18:0 PE2; dioleoyl, 18:1-18:1 PE3; stearoyl- linoleoyl, 18:0-18:2 PE4; dilinoleoyl, 18:2-18:2 PE5; stearoyl-arachidonyl, 18:0-20:4 PE6; diarachidonyl, 20:4-20:4 PE7; and stearoyl-docosahexenoyl, 18:0-22:6 PE8). Endogenous PE content of native membranes was 0.88 +/- 0.01 nmol/mg protein. Incorporation of PE irrespective of fatty acid content significantly (P < 0.02) increased the PE content of total membranes. Vitamin E incorporation in control membranes was 63 +/- 9 nmol/mg protein. Incorporation of vitamin E in PE1- to PE7-treated cells were significantly (P < 0.05) increased compared to controls and were comparable to each other. Vitamin E incorporation into PE8-treated cells was threefold greater (P < 0.001) than controls and twofold greater (P < 0.001) than PE1- to PE7-treated cells. Increased PE content results in increased vitamin E incorporation into PAEC membranes irrespective of the fatty acids present on the acyl chain, and maximal incorporation of vitamin E in PE8-treated cells may relate to the increased carbon chain length rather than to the degree of unsaturation at the sn2 position.