Prophylaxis against lipopolysaccharide-induced acute lung injury by alpha-tocopherol liposomes

Combination of Physicochemical Tropism and Affinity Moiety Targeting of Lipid Nanoparticles Enhances Organ Targeting

Two camps have emerged for targeting nanoparticles to specific organs and cell types: affinity moiety targeting and physicochemical tropism. Here we directly compare and combine both using intravenous (IV) lipid nanoparticles (LNPs) designed to target the lungs. We utilized PECAM antibodies as affinity moieties and cationic lipids for physicochemical tropism. These methods yield nearly identical lung uptake, but aPECAM LNPs show higher endothelial specificity. LNPs combining these targeting methods had >2-fold higher lung uptake than either method alone and markedly enhanced epithelial uptake. To determine if lung uptake is because the lungs are the first organ downstream of IV injection, we compared IV vs intra-arterial (IA) injection into the carotid artery, finding that IA combined-targeting LNPs achieve 35% of the injected dose per gram (%ID/g) in the first-pass organ, the brain, among the highest reported. Thus, combining the affinity moiety and physicochemical strategies provides benefits that neither targeting method achieves alone.

Recent strategies towards the surface modification of liposomes: an innovative approach for different clinical applications

Liposomes are very useful biocompatible tools used in diverse scientific disciplines, employed for the vehiculation and delivery of lipophilic, ampiphilic or hydrophilic compounds. Liposomes have gained the importance as drug carriers, as the drugs alone have limited targets, higher toxicity and develop resistance when used in higher doses. Conventional liposomes suffer from several drawbacks like encapsulation inefficiencies and partially controlled particle size. The surface chemistry of liposome technology started from simple conventional vesicles to second generation liposomes by modulating their lipid composition and surface with different ligands. Introduction of polyethylene glycol to lipid anchor was the first innovative strategy which increased circulation time, delayed clearance and opsonin resistance. PEGylated liposomes have been found to possess higher drug loading capacity up to 90% or more and some drugs like CPX-1 encapsuled in such liposomes have increased the disease control up to 73% patients suffering from colorectal cancer. The surface of liposomes have been further liganded with small molecules, vitamins, carbohydrates, peptides, proteins, antibodies, aptamers and enzymes. These advanced liposomes exhibit greater solubility, higher stability, long-circulating time and specific drug targeting properties. The immense utility and demand of surface modified liposomes in different areas have led their way to the modern market. In addition to this, the multi-drug carrier approach of targeted liposomes is an innovative method to overcome drug resistance while treating ceratin tumors. Presently, several second-generation liposomal formulations of different anticancer drugs are at various stages of clinical trials. This review article summarizes briefly the preparation of liposomes, strategies of disease targeting and exclusively the surface modifications with different entities and their clinical applications especially as drug delivery system.

Assessment of the phenolic profile, antimicrobial activity and oxidative stability of transgenic Perilla frutescens L.overexpressing tocopherol methyltransferase (γ-tmt) gene

This study evaluated the effects of enhanced concentrations of α-tocopherol and phenolic compounds on the resistance and stability of Perilla oil in transgenic Perilla frutescens plants against various tested pathogenic bacteria by over-expressing the γ-tmt gene. The concentration of phenolic compounds in the non-transgenic samples was 9313.198 ± 18.887 μg g^-1 dry weight (DW), whereas the total concentration of the transgenic samples ranged from 9118.015 ± 18.822 to 10527.612 ± 20.411 μg g^-1 DW. The largest increases in phenolic compounds in the transgenic plants in comparison with the control plants were observed in gallic acid, pyrogallol, 5-sulfosalicylic acid, catechin, chlorogenic acid, vanillin, syringic acid, naringenin, salicylic acid, quercetin, o-coumaric acid, kaempferol, and hesperetin. o-coumaric and benzoic acid acid were the most abundant phenolic acids found in the transgenic plants. Gram-negative bacteria (Salmonella typhimurium) were the most susceptible microorganism against transgenic ethyl acetate extracts with lower measurement of minimum inhibitory concentration (MICs) (0.25 ± 0.03 mg/ml) at an extract concentration of 2 mg/ml in dried plant material. The same extracts were more effective against gram-positive bacteria (Bacillus subtilis) when compared to control plants with MICs values of 0.52 ± 0.02 mg/ml. The suplementation of 20 μg of α-tocopherol (1000 ppm) in combination with ethyl acetate extracts enhanced the antimicrobial activity against S. typhimurium and B. subtilis, compared to the non-transgenic plants. The acid value of transgenic Perilla oil improved by 91.2% and 35.54% relative to the non-transgenic control oil and commercial Perilla oil, respectively. The low acid value suggests that the oil will be less susceptible to lipase action, and more economically viable and thus, may also improve the oil quality for industrial purposes. In addition, extracts obtained from transgenic plants could be a potential source of antimicrobial agents for the treatment of bacterial infections.

Mechanistic Evaluation of the Protective Effect of Carnosine on Acute Lung Injury in Sepsis Rats

This study analyzes the sepsis healing therapeutic potential of carnosine against experimentally sepsis-induced male albino rats. Carnosine in 2 different doses, 25 mg/kg and 50 mg/kg, were administered for 30 consecutive days. At the end of the treatment, lipid peroxidation, catalase, superoxide dismutase, glutathione peroxidase and myeloperoxidase activities were measured. Lungs weight and total protein content were determined in the bronchoalveolar fluid (BALF). Cytokines such as macrophage inhibitory factor (MIF), interleukin-8 (IL-8) and tumour necrosis factor-alpha (TNF-α) were determined in the BALF. In addition, the histopathological analysis was also carried out to understand the effect of carnosine in the cellular architecture. Carnosine treatment significantly renormalized the lipid peroxidation and other antioxidant enzymes. IL-β, TNF-α, and MIF were found to be reduced after carnosine treatment. After carnosine treatment, the intensity of sepsis was significantly reduced evidenced by histopathological analysis. In western blot analysis, carnosine treatment causes the upregulation of IκBα together with the downregulation of the expressions of p65 and p-IKKα/β (Ser 180/Ser 181).

Efficacy and Therapeutic Potential of Curcumin Against Sepsis-Induced Chronic Lung Injury in Male Albino Rats

The present study investigates curcumin effect against sepsis-induced chronic lung injury (CLI) of male albino rats. Rats were grouped into four groups such rats undergoing a sham cecal ligature puncture (CLP), rats undergoing CLP, rats undergoing CLP and treated with saline and rats undergoing CLP and treated with curcumin (100 mg/kg bwt). After 45 days of treatment, bronchoalveolar fluid (BALF), blood and lung tissues were collected from the each animal. The total protein content, wet and dry (W/D) weight of lung tissues and some inflammatory cells in the BALF were measured. Histopathological analysis was carried out to investigate the alteration of the cellular architecture of lung tissues. Lipid peroxidation malondialdehyde (MDA), superoxide dismutase (SOD) and myeloperoxidase (MPO) levels were determined. Cytokines such as interleukin-8 (IL-8), tumor necrosis factor-alpha (TNF-a) and macrophage inhibitory factor (MIF) were measured in the BALF. Curcumin administration significantly reduced CLP-induced inflammation and pulmonary edema. Curcumin treatment is significantly reduced MPO activity, and inflammatory cell accumulation in the BALF and also protein level, MDA, SOD, and W/D ratio were significantly reduced in the lung tissues. Also, curcumin reduced the expression of IL-A, TNF-a and MIF levels in the lung tissues. Histopathological study revealed the significant reduction of CLP-induced CLI in the curcumin-treated male albino rats. Taking all these data together, it is concluded that curcumin can act as a suitable therapeutic agent against CLP-induced CLI of male albino rats.

Cationic liposomes containing antioxidants reduces pulmonary injury in experimental model of sepsis: Liposomes antioxidants reduces pulmonary damage

The intracellular redox state of alveolar cells is a determining factor for tolerance to oxidative and pro-inflammatory stresses. This study investigated the effects of intratracheal co-administration of antioxidants encapsulated in liposomes on the lungs of rats subjected to sepsis. For this, male rats subjected to sepsis induced by lipopolysaccharide from Escherichia coli or placebo operation were treated (intratracheally) with antibiotic, 0.9% saline and antioxidants encapsulated or non-encapsulated in liposomes. Experimental model of sepsis by cecal ligation and puncture (CLP) was performed in order to expose the cecum. The cecum was then gently squeezed to extrude a small amount of feces from the perforation site. As an index of oxidative damage, superoxide anions, lipid peroxidation, protein carbonyls, catalase activity, nitrates/nitrites, cell viability and mortality rate were measured. Infected animals treated with antibiotic plus antioxidants encapsulated in liposomes showed reduced levels of superoxide anion (54% or 7.650±1.263 nmol/min/mg protein), lipid peroxidation (33% or 0.117±0.041 nmol/mg protein), protein carbonyl (57% or 0.039 ± 0.022 nmol/mg protein) and mortality rate (3.3%), p value <0.001. This treatment also reduced the level of nitrite/nitrate and increased cell viability (90.7%) of alveolar macrophages. Taken togheter, theses results support that cationic liposomes containing antioxidants should be explored as coadjuvants in the treatment of pulmonary oxidative damage.

Antioxidant strategies in respiratory medicine

Pulmonary oxidant stress plays an important pathogenetic role in disease conditions including acute lung injury/adult respiratory distress syndrome (ALI/ARDS), hyperoxia, ischemia-reperfusion, sepsis, radiation injury, lung transplantation, COPD, and inflammation. Reactive oxygen species (ROS), released from activated macrophages and leukocytes or formed in the pulmonary epithelial and endothelial cells, damage the lungs and initiate cascades of pro-inflammatory reactions propagating pulmonary and systemic stress. Diverse molecules including small organic compounds (e.g. gluthatione, tocopherol (vitamin E), flavonoids) serve as natural antioxidants that reduce oxidized cellular components, decompose ROS and detoxify toxic oxidation products. Antioxidant enzymes can either facilitate these antioxidant reactions (e.g. peroxidases using glutathione as a reducing agent) or directly decompose ROS (e.g. superoxide dismutases [SOD] and catalase). Many antioxidant agents are being tested for treatment of pulmonary oxidant stress. The administration of small antioxidants via the oral, intratracheal and vascular routes for the treatment of short- and long-term oxidant stress showed rather modest protective effects in animal and human studies. Intratracheal and intravascular administration of antioxidant enzymes are being currently tested for the treatment of acute oxidant stress. For example, intratracheal administration of recombinant human SOD is protective in premature infants exposed to hyperoxia. However, animal and human studies show that more effective delivery of drugs to cells experiencing oxidant stress is needed to improve protection. Diverse delivery systems for antioxidants including liposomes, chemical modifications (e.g. attachment of masking pegylated [PEG]-groups) and coupling to affinity carriers (e.g. antibodies against cellular adhesion molecules) are being employed and currently tested, mostly in animal and, to a limited extent, in humans, for the treatment of oxidant stress. Further studies are needed, however, in order to develop and establish effective applications of pulmonary antioxidant interventions useful in clinical practice. Although beyond the scope of this review, antioxidant gene therapies may eventually provide a strategy for the management of subacute and chronic pulmonary oxidant stress.

Therapeutic effect of liposomal-N-acetylcysteine against acetaminophen-induced hepatotoxicity

BACKGROUND

Acetaminophen (APAP) is an antipyretic analgesic drug that when taken in overdose causes depletion of glutathione (GSH) and hepatotoxicity. N-acetylcysteine (NAC) is the antidote of choice for the treatment of APAP toxicity; however, due to its short-half-life repeated dosing of NAC is required.

PURPOSE

To determine whether a NAC-loaded liposomal formulation (Lipo-NAC) is more effective than the conventional NAC in protecting against acute APAP-induced hepatotoxicity.

METHODS

Male Sprague-Dawley rats were challenged with an intragastric dose of APAP (850 mg/kg b.wt.); 4 h later, animals were administered saline, NAC, Lipo-NAC or empty liposomes and sacrificed 24 h post-APAP treatment.

RESULTS

APAP administration resulted in hepatic injury as evidenced by increases in plasma bilirubin, alanine (AST) and aspartate (ALT) aminotransferase levels and tissue levels of lipid peroxidation and myeloperoxidase as well as decreases in hepatic levels of reduced GSH, GSH peroxidase and GSH reductase. Treatment of animals with Lipo-NAC was significantly more effective than free NAC in reducing APAP-induced hepatotoxicity. Histological evaluation showed that APAP caused periacinar hepatocellular apoptosis and/or necrosis of hepatocytes around the terminal hepatic venules which was reduced by NAC treatment, the degree of reduction being greater for Lipo-NAC.

CONCLUSION

These data suggest that administration of Lipo-NAC ameliorated the APAP-induced hepatotoxicity.

Curcumin protects against sepsis-induced acute lung injury in rats

The present study aimed to investigate the effect of curcumin on sepsis-induced acute lung injury (ALI) in rats, and explore its possible mechanisms. Male Sprague-Dawley rats were randomly divided into the following five experimental groups (n = 20 per group): animals undergoing a sham cecal ligature puncture (CLP) (sham group); animals undergoing CLP (control group); or animals undergoing CLP and treated with vehicle (vehicle group), curcumin at 50 mg/kg (low-dose curcumin [L-Cur] group), or curcumin at 200 mg/kg (high-dose curcumin [H-Cur] group).At 6, 12, 24 h after CLP, blood, bronchoalveolar lavage fluid (BALF) and lung tissue were collected. The lung wet/dry weight (W/D) ratio, protein level, and the number of inflammatory cells in the BALF were determined. Optical microscopy was performed to examine the pathologic changes in lungs. Myeloperoxidase (MPO) activity, malondialdehyde (MDA) content, as well as superoxidase dismutase (SOD) activity were measured in lung tissues. The expression of inflammatory cytokines, tumor necrosis factor-alpha (TNF-α), interluekin-8 (IL-8), and macrophage migration inhibitory factor (MIF) were determined in the BALF. Survival rates were recorded at 72 h in the five groups in another experiment. Treatment with curcumin significantly attenuated the CLP-induced pulmonary edema and inflammation, as it significantly decreased lung W/D ratio, protein concentration, and the accumulation of the inflammatory cells in the BALF, as well as pulmonary MPO activity. This was supported by the histopathologic examination, which revealed marked attenuation of CLP-induced ALI in curcumin treated rats. In addition, curcumin significantly increased SOD activity with significant decrease in MDA content in the lung. Also, curcumin caused down-regulation of the inflammatory cytokines TNF-α, IL-8, and MIF levels in the lung. Importantly, curcumin improved the survival rate of rats by 40%-50% with CLP-induced ALI. Taken together, these results demonstrate the protective effects of curcumin against the CLP-induced ALI. This effect can be attributed to curcumin ability to counteract the inflammatory cells infiltration and, hence, ROS generation and regulate cytokine effects.

Liposomal Antioxidants for Protection against Oxidant-Induced Damage

Reactive oxygen species (ROS), including superoxide anion, hydrogen peroxide, and hydroxyl radical, can be formed as normal products of aerobic metabolism and can be produced at elevated rates under pathophysiological conditions. Overproduction and/or insufficient removal of ROS result in significant damage to cell structure and functions. In vitro studies showed that antioxidants, when applied directly and at relatively high concentrations to cellular systems, are effective in conferring protection against the damaging actions of ROS, but results from animal and human studies showed that several antioxidants provide only modest benefit and even possible harm. Antioxidants have yet to be rendered into reliable and safe therapies because of their poor solubility, inability to cross membrane barriers, extensive first-pass metabolism, and rapid clearance from cells. There is considerable interest towards the development of drug-delivery systems that would result in the selective delivery of antioxidants to tissues in sufficient concentrations to ameliorate oxidant-induced tissue injuries. Liposomes are biocompatible, biodegradable, and nontoxic artificial phospholipid vesicles that offer the possibility of carrying hydrophilic, hydrophobic, and amphiphilic molecules. This paper focus on the use of liposomes for the delivery of antioxidants in the prevention or treatment of pathological conditions related to oxidative stress.

Nilotinib ameliorates lipopolysaccharide-induced acute lung injury in rats

The present study aimed to investigate the effect of the new tyrosine kinase inhibitor, nilotinib on lipopolysaccharide (LPS)-induced acute lung injury (ALI) in rats and explore its possible mechanisms. Male Sprague-Dawley rats were given nilotinib (10mg/kg) by oral gavage twice daily for 1week prior to exposure to aerosolized LPS. At 24h after LPS exposure, bronchoalveolar lavage fluid (BALF) samples and lung tissue were collected. The lung wet/dry weight (W/D) ratio, protein level and the number of inflammatory cells in the BALF were determined. Optical microscopy was performed to examine the pathological changes in lungs. Malondialdehyde (MDA) content, superoxidase dismutase (SOD) and reduced glutathione (GSH) activities as well as nitrite/nitrate (NO(2)(-)/NO(3)(-)) levels were measured in lung tissues. The expression of inflammatory cytokines, tumor necrosis factor-α (TNF-α), transforming growth factor-β(1) (TGF-β(1)) and inducible nitric oxide synthase (iNOS) were determined in lung tissues. Treatment with nilotinib prior to LPS exposure significantly attenuated the LPS-induced pulmonary edema, as it significantly decreased lung W/D ratio, protein concentration and the accumulation of the inflammatory cells in the BALF. This was supported by the histopathological examination which revealed marked attenuation of LPS-induced ALI in nilotinib treated rats. In addition, nilotinib significantly increased SOD and GSH activities with significant decrease in MDA content in the lung. Nilotinib also reduced LPS mediated overproduction of pulmonary NO(2)(-)/NO(3)(-) levels. Importantly, nilotinib caused down-regulation of the inflammatory cytokines TNF-α, TGF-β(1) and iNOS levels in the lung. Taken together, these results demonstrate the protective effects of nilotinib against the LPS-induced ALI. This effect can be attributed to nilotinib ability to counteract the inflammatory cells infiltration and hence ROS generation and regulate cytokine effects.

Characterization, lung targeting profile and therapeutic efficiency of dipyridamole liposomes

The acute respiratory distress syndrome (ARDS) is a severe form of acute lung injury (ALI). Its pathogenesis is closely linked with reactive oxygen species (ROS). Antioxidation has been considered as an efficient treatment. Besides, liposomes are widely investigated as potential drug carriers due to their ability to protect and carry drug molecules to the target organ such as the lung. The present study was undertaken to investigate whether dipyridamole (DIP), delivered as a liposomal preparation, can ameliorate the lipopolysaccharides (LPS)-induced ALI due to the changes of its biodistribution. First, the liposomes entrapping DIP were prepared by film hydration for treating ARDS. Subsequently, the characterizations including entrapment efficiency, size, span and micrograph of DIP liposomes were measured. The concentration change of DIP in tissues and plasma of mice after intravenous administration of DIP injection and DIP liposomes was determined by RP-HPLC and calculated to lung targeting parameters. To prove the therapeutic efficiency, the effects of DIP liposomes on LPS-induced ALI were studied compared with DIP injection. The results showed DIP liposomes have the relative high entrapment efficiency and satisfying particle size. Compared with DIP injection, the liposomes increased the accumulation of DIP in the lung on a vast scale. Furthermore, DIP liposomes alleviated the ALI induced by LPS significantly. All of the results suggested that DIP liposomes have the potential efficacy in treating ALI/ARDS due to their obvious lung targeting.

Ability of antioxidant liposomes to prevent acute and progressive pulmonary injury

We recently showed that acute oxidant-related lung injury (ALI) in rats after application of 2-chloroethyl ethyl sulfide (CEES) is attenuated by the airway instillation of antioxidants. We investigated whether intratracheal administration of antioxidant-containing liposomes immediately after instillation of CEES would attenuate short-term as well as long-term (fibrotic) effects of CEES-induced lung injury. In the acute injury model (4 h after injury), N-acetylcysteine (NAC)-containing liposomes were protective and reduced to baseline levels both the lung permeability index and the appearance of proinflammatory mediators in bronchoalveolar lavage fluids from CEES-exposed lungs. Similar results were obtained when rat alveolar macrophages were incubated in vitro with either CEES or lipopolysaccharide in the presence of NAC-liposomes. When lung fibrosis 3 weeks after CEES was quantitated by using hydroxyproline content, liposomes containing NAC or NAC + glutathione had no effects, but liposomes containing alpha/gamma-tocopherol alone or with NAC significantly suppressed the increase in lung hydroxyproline. The data demonstrate that delivery of antioxidants via liposomes to CEES-injured lungs is, depending on liposomal content, protective against ALI, prevents the appearance of proinflammatory mediators in bronchoalveolar fluids, and suppresses progressive fibrosis. Accordingly, the liposomal strategy may be therapeutically useful in CEES-induced lung injury in humans.

Vitamin E down-modulates mitogen-activated protein kinases, nuclear factor-kappaB and inflammatory responses in lung epithelial cells

The airway epithelium plays an active role in acute lung inflammation by producing chemotactic factors and by expressing cell adhesion molecules involved in the migration of leucocytes to extravascular spaces. We have reported previously that neutrophil migration to airways can be down-modulated by exogenously administered vitamin E (alpha-tocopherol). The mechanism for this effect is not well understood, however. The action of alpha-tocopherol was investigated in human alveolar type II and bronchial epithelial cells stimulated with tumour necrosis factor-alpha. Treatment of alveolar epithelial cells with alpha-tocopherol resulted in down-regulated cell surface expression of intercellular adhesion molecule-1 (ICAM-1). On bronchial epithelial cells, both ICAM-1 and vascular adhesion molecule-1 were decreased, leading to diminished adherence of leucocytes to the cells. The production of the neutrophil chemoattractant interleukin-8 was attenuated in both alveolar and bronchial cells. These effects were preceded by reduced activation of the mitogen-activated protein kinases (MAPK), extracellular signal-regulated kinase (ERK1/2) and p38, as well as down-regulation of nuclear factor-kappaB. Comparing the effects of alpha-tocopherol with that of specific inhibitors of MAPK and protein kinase C (PKC) revealed that effects appear to be partly independent of PKC inhibition. These results implicate the anti-inflammatory action of alpha-tocopherol in addition to its anti-oxidant properties.

Nimesulide inhibits lipopolysaccharide-induced production of superoxide anions and nitric oxide and iNOS expression in alveolar macrophages

The study was designed to investigate the effect of nimesulide on lipopolysaccharide (LPS)-induced proinflammatory oxidants production by rat alveolar macrophages (AMs). Effects of LPS and nimesulide on antioxidant defense and the expression of inducible nitric oxide synthase (iNOS) were also studied. It was found that nimesulide could scavenge superoxide anions (O2*-), nitric oxide (NO*) and total oxidant burden induced by LPS in AMs in vitro. Approximately 850 nmoles of nimesulide had activity equivalent to one IU of superoxide dismutase (SOD). Further, to confirm the in vitro observation, Male Wistar rats were orally administered with nimesulide (9 mg/kg b. wt. twice daily) for one week followed by intratracheal instillation of 2 microg LPS to stimulate lung inflammation. AMs from bronchoalveolar lavage fluid were collected 18 h after instillation of LPS. Nimesulide pretreatment could inhibit O2*-, NO() and lipid peroxidation in AMs. Nimesulide also suppressed LPS-induced iNOS expression in AMs in vivo and in vitro. Nimesulide could also normalize LPS-induced changes in the levels of superoxide dismutase (SOD), glutathione reductase (GR) and reduced glutathione (GSH) in AMs. Inhibition in production of oxidants in LPS-challenged AMs by nimesulide could be one of the pathways for its anti-inflammatory action.

Aerosol-administered alpha-tocopherol attenuates lung inflammation in rats given lipopolysaccharide intratracheally

Intrapulmonary administration of bacterial lipopolysaccharide (LPS) induces a well-characterized lung inflammatory response involving alveolar macrophage activation, proinflammatory cytokine elaboration, and neutrophil influx. Vitamin E, a lipophilic antioxidant consisting of a family that includes tocopherols and tocotrienols, has previously been shown to have a variety of anti-inflammatory effects, raising interest in its possible uses in disease prevention or therapy. Because aerosol delivery is a specific and rapid way to administer agents to the lungs, the authors undertook to determine whether inhaled vitamin E aerosols would have an anti-inflammatory effect in the lungs. Using a rat model of acute lung inflammation caused by intratracheally administered LPS (10 microg Pseudomonas aeruginosa LPS), the authors examined the effect of aerosol-administered vitamin E, in this case alpha-tocopherol, on several indices of lung inflammation which are increased by LPS treatment. It was found that inhaled alpha-tocopherol aerosol, but not inhaled alpha-tocopherol acetate aerosol, decreased tumor necrosis factor alpha (TNFalpha) and cytokine-induced neutrophil chemoattractant-1 (CINC-1) mRNA levels in lung tissue, TNFalpha and CINC-1 immunoreactive protein levels in lung lavage, and the number of neutrophils recoverable by lung lavage from rats given LPS intratracheally. These results contribute to the increasing body of work describing immunomodulatory functions of alpha-tocopherol, and support the idea that direct aerosol administration of alpha-tocopherol may play a beneficial role in strategies to control inflammatory lung illnesses.

Therapeutic uses of antioxidant liposomes

This review will focus on the therapeutic uses of antioxidant liposomes. Antioxidant liposomes have a unique ability to deliver both lipid- and water-soluble antioxidants to tissues. This review will detail the varieties of antioxidants which have been incorporated into liposomes, their modes of administration, and the clinical conditions in which antioxidant liposomes could play an important therapeutic role. Antioxidant liposomes should be particularly useful for treating diseases or conditions in which oxidative stress plays a significant pathophysiological role because this technology has been shown to suppress oxidative stress. These diseases and conditions include cancer, trauma, irradiation, retinotherapy or prematurity, respiratory distress syndrome, chemical weapon exposure, and pulmonary infections.

Protective role of metallothionein in acute lung injury induced by bacterial endotoxin

BACKGROUND

Metallothionein (MT) is a protein that can be induced by inflammatory mediators and participate in cytoprotection. However, its role in inflammation remains to be established. A study was undertaken to determine whether intrinsic MT protects against acute inflammatory lung injury induced by bacterial endotoxin in MT-I/II knock out (-/-) and wild type (WT) mice.

METHODS

MT (-/-) and WT mice were given vehicle or lipopolysaccharide (LPS, 125 microg/kg) intratracheally and the cellular profile of the bronchoalveolar lavage (BAL) fluid, pulmonary oedema, lung histology, expression of proinflammatory molecules, and nuclear localisation of nuclear factor-kappaB (NF-kappaB) in the lung were evaluated.

RESULTS

MT (-/-) mice were more susceptible than WT mice to lung inflammation, especially to lung oedema induced by intratracheal challenge with LPS. After LPS challenge, MT deficiency enhanced vacuolar degeneration of pulmonary endothelial cells and type I alveolar epithelial cells and caused focal loss of the basement membrane. LPS treatment caused no significant differences in the enhanced expression of proinflammatory cytokines and chemokines nor in the activation of the NF-kappaB pathway in the lung between the two genotypes. Lipid peroxide levels in the lungs were significantly higher in LPS treated MT (-/-) mice than in LPS treated WT mice.

CONCLUSIONS

Endogenous MT protects against acute lung injury related to LPS. The effects are possibly mediated by the enhancement of pulmonary endothelial and epithelial integrity, not by the inhibition of the NF-kappaB pathway.

Pulmonary edema fluid antioxidants are depressed in acute lung injury

OBJECTIVE

To test the hypothesis that low concentrations of distal airspace water-soluble antioxidants are associated with acute lung injury.

DESIGN

Prospective, cohort study.

SETTING

Medical intensive care unit of two tertiary care hospitals.

SUBJECTS

Subjects were 29 patients with acute lung injury and 23 normal, healthy, volunteers.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Pulmonary edema fluid from subjects with acute lung injury was aspirated immediately after intubation. Compared with the bronchoalveolar lavage from normal subjects (corrected for dilution using urea concentrations), undiluted edema fluid from acute lung injury subjects had significantly lower concentrations of the antioxidants urate (757 +/- 232 microM vs. 328 +/- 75 microM), glutathione (138 +/- 25 microM vs. 7 +/- 4 microM), and ascorbate (85 +/- 21 microM vs. 27 +/- 10 microM).

CONCLUSIONS

Acute lung injury is associated with decreased concentrations of water-soluble antioxidants in the distal airspaces. In acute lung injury, the distal airspace antioxidants ascorbate, urate, and glutathione may play a role in attenuating lung injury.

Pseudomonas aeruginosa-induced lung injury: role of oxidative stress

Pseudomonas aeruginosa is a Gram-negative pathogen that can cause lung injury in immunocompromised patients, primarily by inducing a release of host-derived mediators responsible for the influx of phagocytes to the lung. These phagocytes exert their antimicrobial actions by releasing toxic metabolites, including reactive oxygen species and proteases, which can also cause cell injury. This study was carried out to assess the pulmonary oxidant-antioxidant status of male adult Sprague-Dawley rats infected with different numbers of P. aeruginosa (10(4)-10(7)cfu/animal). Intratracheal instillation of P. aeruginosa resulted in lung injury, as evidenced by increases in wet lung weight and decreases in the lung activities of angiotensin converting enzyme and alkaline phosphatase, enzymes localized primarily in pulmonary endothelial and alveolar type II epithelial cells, respectively. The P. aeruginosa -induced lung injury was directly related to the infiltration of neutrophils, as indicated by increases in myeloperoxidase activity. The challenge of animals with P. aeruginosa resulted in increases in lipid peroxidation and decreases in glutathione content, which were associated with the indices of lung injury and neutrophil infiltration. Such a challenge also resulted in weakening the antioxidant defence system, as evidenced by decreases in superoxide dismutase, catalase and glutathione peroxidase activities. These data suggest that changes in the pulmonary oxidant-antioxidant status may play an important role in the P. aeruginosa -induced lung injury.