Epithelial Lining Fluid GSH Research Articles

Evaluation of antioxidant and anti-lipid peroxidation potentials of Nigella sativa and onion extract on nicotine-induced lung damage.

The present work aimed to compare the protective effect of Nigella sativa (NS) and onion extract on the nicotine-induced lung damage in rats. The antioxidant and anti-lipid peroxidation potentials of both agents on nicotine-induced lung damage were studied. Thirty-six Sprague-Dawley albino rats, treated for 18 weeks, were divided into six groups: one negative control group, two positive control groups (oral onion and oral NS), nicotine-treated group, onion extract-treated group (concomitant nicotine and onion extract) and NS-treated group (concomitant nicotine and NS oil). The assessment of lung structure was based on haematoxylin and eosin and transmission electron microscopy. Lung malondialdehyde (MDA), superoxide dismutase activity (SOD), catalase (CAT), lung glutathione (GSH), and epithelial lining fluid GSH (ELF GSH) were used for assessment of the antioxidant and anti-lipid peroxidation potentials of NS and onion extract. The lung of the nicotine-treated group exhibited emphysematous air spaces, collapsed corrugated alveoli with ruptured interalveolar septa in some specimen and thickened septa in the others, massive congestion, extravasation of red blood cells, inflammatory cellular infiltration and fluid exudate. Much improvement was observed in the onion-treated group despite the presence of residual pathological affection. The lung in the NS-treated group showed the nearly normal architecture with slight congestion. Administration of nicotine promoted lipid peroxidation (elevation of MDA) and decreased the level of the antioxidant markers (SOD, CAT, lung GSH and ELF GSH). With the use of onion extract and NS, the level of MDA decreased by 17.85% and 35.71% while the levels of SOD, CAT, GSH, and ELF GSH increased. The increase was more prominent in the NS-treated group. The levels in the NS-treated group reached nearly the level markers of the control group. Nigella sativa and onion extract attenuate the pathological effect of nicotine in the lung rats through antioxidative and anti-lipid peroxidative mechanisms with higher protection to NS.

CFTR is the primary known apical glutathione transporter involved in cigarette smoke-induced adaptive responses in the lung

One of the most abundant antioxidants in the lung is glutathione (GSH), a low-molecular-weight thiol, which functions to attenuate both oxidative stress and inflammation. GSH is concentrated in the epithelial lining fluid (ELF) of the lung and can be elevated in response to the increased oxidant burden from cigarette smoke (CS). However, the transporter(s) responsible for the increase in ELF GSH with cigarette smoke is not known. Three candidate apical GSH transporters in the lung are CFTR, BCRP, and MRP2, but their potential roles in ELF GSH transport in response to CS have not been investigated. In vitro, the inhibition of CFTR, BCRP, or MRP2 resulted in decreased GSH efflux in response to cigarette smoke extract. In vivo, mice deficient in CFTR, BCRP, or MRP2 were exposed to either air or acute CS. CFTR-deficient mice had reduced basal and CS-induced GSH in the ELF, whereas BCRP or MRP2 deficiency had no effect on ELF GSH basal or CS-exposed levels. Furthermore, BCRP or MRP2 deficiency had little effect on lung tissue GSH. These data indicate that CFTR is predominantly involved in maintaining basal ELF GSH and increasing ELF GSH in response to CS.

Lung glutathione adaptive responses to cigarette smoke exposure

BackgroundSmoking tobacco is a leading cause of chronic obstructive pulmonary disease (COPD), but although the majority of COPD cases can be directly related to smoking, only a quarter of smokers actually develop the disease. A potential reason for the disparity between smoking and COPD may involve an individual's ability to mount a protective adaptive response to cigarette smoke (CS). Glutathione (GSH) is highly concentrated in the lung epithelial lining fluid (ELF) and protects against many inhaled oxidants. The changes in GSH that occur with CS are not well investigated; therefore the GSH adaptive response that occurs with a commonly utilized CS exposure was examined in mice.MethodsMice were exposed to CS for 5 h after which they were rested in filtered air for up to 16 h. GSH levels were measured in the ELF, bronchoalveolar lavage cells, plasma, and tissues. GSH synthesis was assessed by measuring γ-glutamylcysteine ligase (GCL) activity in lung and liver tissue.ResultsGSH levels in the ELF, plasma, and liver were decreased by as much as 50% during the 5 h CS exposure period whereas the lung GSH levels were unchanged. Next, the time course of rebound in GSH levels after the CS exposure was examined. CS exposure initially decreased ELF GSH levels by 50% but within 2 h GSH levels rebound to about 3 times basal levels and peaked at 16 h with a 6-fold increase and over repeat exposures were maintained at a 3-fold elevation for up to 2 months. Similar changes were observed in tissue GCL activity which is the rate limiting step in GSH synthesis. Furthermore, elevation in ELF GSH levels was not arbitrary since the CS induced GSH adaptive response after a 3d exposure period prevented GSH levels from dropping below basal levels.ConclusionsCS exposures evoke a powerful GSH adaptive response in the lung and systemically. These data suggests there may be a sensor that sets the ELF GSH adaptive response to prevent GSH levels from dipping below basal levels. Factors that disrupt GSH adaptive responses may contribute to the pathophysiology of COPD.

Macropinocytosis of Extracellular Glutathione Ameliorates Tumor Necrosis Factor α Release in Activated Macrophages

A number of inflammatory lung diseases have abnormally low glutathione (GSH) levels in the airway fluids. Lung macrophages are common mediators of inflammation, make up the majority of cells that are found in the airway epithelial lining fluid (ELF), and are commonly elevated in many lung diseases. Several animal models with altered ELF GSH levels are associated with similar alterations in the intracellular GSH levels of bronchoalveolar lavage (BAL) cells. The possible mechanisms and outcomes for this association between ELF GSH levels and intracellular BAL cell GSH are unknown. To investigate these issues, macrophages were grown in media supplemented with 500 µM GSH. GSH supplementation resulted in a 2–3 fold increase in macrophage intracellular GSH levels. The increase in macrophage intracellular GSH levels was associated with a significant reduction in NF-κB nuclear translocation and tumor necrosis factor α (TNFα) release upon LPS stimulation. Furthermore, co-treatment of macrophages with GSH and inhibitors of GSH breakdown or synthesis did not block GSH accumulation. In contrast, treatment with cytochalasin D, an inhibitor of actin dependent endocytosis, and amiloride, an inhibitor of macropinocytosis blocked, at least in part, GSH uptake. Furthermore, using two cigarette smoke exposure paradigms that result in two different GSH levels in the ELF and thus in the BAL cells resulted in modulation of cytokine release when stimulated with LPS ex vivo. These data suggest that macrophages are able to utilize extracellular GSH which can then modulate inflammatory signaling in response to proinflammatory stimuli. This data also suggests the lung can modulate inflammatory responses triggered by proinflammatory stimuli by altering ELF GSH levels and may help explain the dysregulated inflammation associated with lung diseases that have low ELF GSH levels.

Hypertonic saline increases lung epithelial lining fluid glutathione and thiocyanate: two protective CFTR-dependent thiols against oxidative injury

BackgroundCystic fibrosis is a debilitating lung disease due to mutations in the cystic fibrosis transmembrane conductance regulator protein (CFTR) and is associated with chronic infections resulting in elevated myeloperoxidase activity and generation of hypochlorous acid (HOCl). CFTR mutations lead to decreased levels of glutathione (GSH) and thiocyanate (SCN) in the epithelial lining fluid (ELF). Hypertonic saline is used to improve lung function however the mechanism is uncertain.MethodsIn the present study, the effect of GSH and SCN on HOCl-mediated cell injury and their changes in the ELF after hypertonic saline nebulization in wild type (WT) and CFTR KO mice was examined. CFTR sufficient and deficient lung cells were assessed for GSH, SCN and corresponding sensitivity towards HOCl-mediated injury, in vitro.ResultsCFTR (-) cells had lower extracellular levels of both GSH and SCN and were more sensitive to HOCl-mediated injury. In vivo, hypertonic saline increased ELF GSH in the WT and to a lesser extent in the CFTR KO mice but only SCN in the WT ELF. Finally, potential protective effects of GSH and SCN at concentrations found in the ELF against HOCl toxicity were examined in vitro.ConclusionsWhile the concentrations of GSH and SCN associated with the WT ELF protect against HOCl toxicity, those found in the CFTR KO mice were less sufficient to inhibit cell injury. These data suggests that CFTR has important roles in exporting GSH and SCN which are protective against oxidants and that hypertonic saline treatment may have beneficial effects by increasing their levels in the lung.

Aging Adversely Affects the Cigarette Smoke–induced Glutathione Adaptive Response in the Lung

Cigarette smoke (CS) is the leading cause of chronic obstructive pulmonary disease, accounting for more than 90% of cases. The prevalence of chronic obstructive pulmonary disease is much higher in the elderly, suggesting an age dependency. A prominent defense against the oxidant burden caused by CS is the glutathione (GSH) adaptive response in the lung epithelial lining fluid (ELF) and tissue. However, as one ages the ability to maintain GSH levels declines. Examine the effect of aging on the GSH adaptive response to CS and resulting lung sensitization to inflammation and oxidation. Both young (2 mo old) and aged (8, 13, 19, and 26 mo old) mice were used to study the effects of age on the GSH adaptive response after an acute exposure to CS. Young mice had a robust sixfold increase in ELF GSH after a single exposure to CS. The GSH response to CS decreased as a function of age and diminishes in the older mice to only a twofold increase over air controls. As a consequence, levels of CS-induced tumor necrosis factor-α and nitric oxide synthase, markers of inflammation, and 8-hydroxy-2-deoxyguanosine, a marker of DNA oxidation, were elevated in the aged mice compared with the young mice. Additionally, depletion of ELF GSH with buthionine sulfoximine in young mice recapitulated changes in ELF tumor necrosis factor-α as seen in old mice. These data suggest that the age-related maladaptive response to CS sensitizes the lung to both inflammation and oxidation potentially contributing to the development of CS-induced chronic obstructive pulmonary disease.

Airway glutathione homeostasis is altered in children with severe asthma: Evidence for oxidant stress

Severe asthma is characterized by persistent airway inflammation and increased formation of reactive oxygen species. Glutathione (GSH) is an important antioxidant in the epithelial lining fluid (ELF). We hypothesized that airway GSH homeostasis was altered in children with severe asthma and was characterized by decreased GSH and increased glutathione disulfide (GSSG) concentrations. Bronchoalveolar lavage was obtained from 65 children with severe asthma, including 35 children with baseline airway obstruction evidenced by FEV(1) <80%. Control data were obtained from 6 children with psychogenic (habit) cough or vocal cord dysfunction undergoing diagnostic bronchoscopy and 35 healthy adult controls. GSH, GSSG, and other determinants of airway oxidative stress including glutathione S-transferase (GST), glutathione reductase (GR), glutathione peroxidase (GPx), malondialdehyde, 8-isoprostane, and H(2)O(2) were measured in the ELF. The ELF redox potential was calculated from GSH and GSSG by using the Nernst equation. Compared with controls, subjects with severe asthma had lower airway GSH with increased GSSG despite no differences in GST, GR, and GPx activities between groups. This was accompanied by increased malondialdehyde, 8-isoprostane, and H(2)O(2) concentrations in the ELF. GSH oxidation was most apparent in subjects with severe asthma with airway obstruction and was supported by an upward shift in the ELF GSH redox potential. Children with severe asthma have increased biomarkers of oxidant stress in the ELF that are associated with increased formation of GSSG and a shift in the GSH redox potential toward the more oxidized state.

Mycoplasma pneumoniae Infection and Environmental Tobacco Smoke Inhibit Lung Glutathione Adaptive Responses and Increase Oxidative Stress

Chronic cigarette smoking evokes a lung glutathione (GSH) adaptive response that results in elevated GSH levels in the lung epithelial lining fluid (ELF). Currently, little is known about how the lung regulates or maintains steady-state levels of ELF GSH. Pathogens such as Mycoplasma pneumoniae can exacerbate airway inflammation and oxidative stress. The present study examined whether M. pneumoniae infections synergize with environmental tobacco smoke (ETS) to disrupt lung GSH adaptive responses. Mice were exposed separately and in combination to ETS and M. pneumoniae for 16 weeks. ETS exposure resulted in a doubling of ELF GSH levels, which was blocked in the M. pneumoniae-exposed mice. In addition, the ETS-plus-M. pneumoniae-exposed mice had elevated levels of oxidized glutathione (GSSG), resulting in a dramatic change in the ELF redox state that corresponded with an increase in lung tissue DNA oxidation. Similar findings were observed in human lung epithelial cells in vitro. Cells exposed separately or in combination to cigarette smoke extract and M. pneumoniae for 48 h had elevated apical levels of GSH compared to control cells, and these increases were blocked by M. pneumoniae and were also associated with increased cellular DNA oxidation. Further studies showed that M. pneumoniae exposure blocked ETS-induced increases in GSH reductase, an enzyme that recycles GSSG back to GSH, both in vitro and in vivo. These studies suggest that M. pneumoniae infection synergizes with ETS and suppresses the lung's ability to respond appropriately to environmental challenges leading to enhanced oxidative stress.

Fetal Alcohol Exposure Impairs Alveolar Macrophage Function via Decreased Glutathione Availability

Immature function of the alveolar macrophage increases the risk of pulmonary infections in premature newborns. In utero alcohol increases fetal systemic oxidative stress. Because the premature lung is deficient in glutathione (GSH), we hypothesized that chronic in utero alcohol (ethanol) exposure exacerbates the oxidative stress within the developing lung, thereby impairing alveolar macrophage function. Additionally, we evaluated the effects of in vivo and in vitro GSH availability on ethanol-exposed macrophage function. Using a guinea pig model of chronic in utero ethanol exposure, fetal epithelial lining fluid (ELF) and alveolar macrophage GSH were decreased with increased markers of oxidative stress. Ethanol-exposed macrophage exhibited impaired phagocytosis and increased apoptosis compared with gestational control. When the GSH precursor S-adenosyl-methionine (SAM) was added to the maternal drinking water containing ethanol, fetal ELF and macrophage GSH were maintained and ELF oxidative stress diminished. In vivo maternal SAM therapy maintained macrophage phagocytosis and decreased apoptosis. In vitro GSH supplements also improved phagocytosis and viability in both premature and ethanol-exposed macrophage. This suggested that in utero ethanol impaired premature macrophage function and viability via decreased GSH availability. Furthermore, GSH supplementation during and after ethanol exposure improved fetal macrophage function and viability. These results add a new dimension to the detrimental effects of fetal alcohol exposure on the developing alveolar macrophage, raising the possibility of GSH therapy to augment premature alveolar macrophage function.

Role for cystic fibrosis transmembrane conductance regulator protein in a glutathione response to bronchopulmonary pseudomonas infection.

The lung maintains an elevated level of glutathione (GSH) in epithelial lining fluid (ELF) compared to serum. The mechanism(s) by which the lung maintains high levels of ELF GSH and factors that modulate them are largely unexplored. We hypothesized that lung cystic fibrosis transmembrane conductance regulator protein (CFTR) modulates GSH efflux in response to extracellular stress, which occurs with lung infections. Mice were challenged intratracheally with Pseudomonas aeruginosa, and on the third day of infection bronchoalveolar lavage fluid was obtained and analyzed for cytokines and antioxidants. Lung tissue antioxidants and enzyme activities were also assessed. P. aeruginosa lung infection increased levels of inflammatory cytokines and neutrophils in the ELF. This corresponded with a marked threefold increase in GSH and a twofold increase in urate levels in the ELF of P. aeruginosa-infected wild-type mice. A twofold increase in urate levels was also observed among lung tissue antioxidants of P. aeruginosa-infected wild-type mice. There were no changes in markers of lung oxidative stress associated with the P. aeruginosa lung infection. In contrast with wild-type mice, the CFTR knockout mice lacked a significant increase in ELF GSH when challenged with P. aeruginosa, and this correlated with a decrease in the ratio of reduced to oxidized GSH in the ELF, a marker of oxidative stress. These data would suggest that the lung adapts to infectious agents with elevated ELF GSH and urate. Individuals with lung diseases associated with altered antioxidant transport, such as cystic fibrosis, might lack the ability to adapt to the infection and present with a more severe inflammatory response.

Glutathione aerosol suppresses lung epithelial surface inflammatory cell-derived oxidants in cystic fibrosis.

Cystic fibrosis (CF) is characterized by accumulation of activated neutrophils and macrophages on the respiratory epithelial surface (RES); these cells release toxic oxidants, which contribute to the marked epithelial derangements seen in CF. These deleterious consequences are magnified, since reduced glutathione (GSH), an antioxidant present in high concentrations in normal respiratory epithelial lining fluid (ELF), is deficient in CF ELF. To evaluate the feasibility of increasing ELF GSH levels and enhancing RES antioxidant protection, GSH aerosol was delivered (600 mg twice daily for 3 days) to seven patients with CF. ELF total, reduced, and oxidized GSH increased (P < 0.05, all compared with before GSH therapy), suggesting adequate RES delivery and utilization of GSH. Phorbol 12-myristate 13-acetate-stimulated superoxide anion (O2-.) release by ELF inflammatory cells decreased after GSH therapy (P < 0.002). This paralleled observations that GSH added in vitro to CF ELF inflammatory cells suppressed O2-. release (P < 0.001). No adverse effects were noted during treatment. Together, these observations demonstrate the feasibility of using GSH aerosol to restore RES oxidant-antioxidant balance in CF and support the rationale for further clinical evaluation.

Changes in gamma-glutamyltransferase activity in rat lung tissue, BAL, and type II cells after hyperoxia.

The effect of hyperoxia on gamma-glutamyltransferase (gamma-GT), an important enzyme for the uptake of precursor molecules for intracellular synthesis of glutathione (GSH), has not been established. Our aim was to investigate the effects of prolonged subtoxic levels of hyperoxia on gamma-GT activity and GSH levels in lung tissue, epithelial lining fluid (ELF), and isolated rat type II cells immediately after their isolation and 48 h later when kept in culture in normoxia. Seventeen male Wistar rats were divided in three groups (n = 5-7) and were exposed to air or to 60 or 85% O2 for 7 days. Pulmonary gamma-GT activity increased in the 60 and 85% O2-exposed animals (1.6- and 3.2-fold, respectively), and tissue GSH levels increased only in the 60% O2 group (1.3-fold). In isolated type II cells from 60 and 85% O2-exposed animals, gamma-GT activity decreased by -70 and -88%, respectively, which was supported by cytochemical staining. Type II cell gamma-GT mRNA expression tended only to decrease after 85% O2. Type II cell gamma-GT activity strongly correlated with ELF gamma-GT (r = 0.60, P < 0.001), and ELF gamma-GT strongly correlated with ELF GSH (r = 0.75, P < 0.0001). When in culture, type II cell gamma-GT activity and GSH levels remained, respectively, 2.5- and 1.9-fold lower in the 60% O2-exposed group, but, in the 85% O2-exposed group, gamma-GT activity increased 2.1-fold, and GSH levels dropped to the levels of the control cells. Hyperoxia led to a concentration-dependent decrease in gamma-GT activity in rat type II cells, possibly by direct inactivation, but led to an increase in whole lung tissue gamma-GT. There seemed to be a negative feedback between intracellular GSH levels and type II cell gamma-GT activity. gamma-GT levels in the ELF were correlated with type II cell gamma-GT activity, but ELF gamma-GT did not seem to play an active role in the regulation of the ELF GSH pool. Hyperoxia decreased ELF GSH levels, possibly by increased degradation of GSH in the parenchymal lung tissue as a result of the increased gamma-GT activity.

Alveolar Fluid Glutathione Decreases in Asymptomatic HIV-Seropositive Subjects Over Time

Initial investigations demonstrated a deficiency of glutathione (GSH) in the epithelial lining fluid (ELF) of HIV-seropositive patients. In a recent study, our laboratory was unable to document such a deficiency. The current study was performed in an attempt to reconcile those disparate findings. To determine if ELF GSH decreases over time in asymptomatic HIV-seropositive subjects. Prospective, longitudinal study. Major university medical center. Thirty-three asymptomatic HIV-seropositive volunteers. None. BAL was performed on 33 asymptomatic HIV-seropositive subjects at baseline, 6 months later, and 12 months later. The volume of ELF and the concentration of GSH and oxidized GSH were determined. The concentration of total GSH in ELF was 689.0+/-100.4 microM. This significantly decreased when measured 6 and 12 months later (355.9+/-41.7 microM, and 397.9+/-52.7 microM, respectively, p=0.01, compared with baseline, both comparisons). Significant decreases were also noted in the HIV-seropositive subjects who smoked cigarettes (baseline--762.6+/-142.4 microM; 6 months--373.7+/-45.9 microM; 12 months--459.3+/-73.8 microM, p<0.03, for baseline vs 6 months, and baseline vs 12 months). In nonsmoking HIV-seropositive subjects, there was a decrease in ELF GSH over time, but it did not reach statistical significance (baseline--589.1+/-138.2 microM; 6 months--335.3+/-74.1 microM; 12 months--345.8+/-74.0 microM, p>0.1, all comparisons). The percentage of total GSH in the oxidized form was similar at all three time points (baseline--3.8+/-0.5%; 6 months--3.1+/-0.5%; 12 months--3.9+/-0.9%, p>0.1, all comparisons). The current study demonstrates that the GSH level in ELF is significantly decreased in HIV-seropositive subjects 6 and 12 months after the initial determination.

N-acetylcysteine does not protect against type II cell injury after prolonged exposure to hyperoxia in rats.

Although the antioxidant properties of N-acetylcysteine (NAC) in vitro are widely accepted, the efficacy of NAC in the prevention of O2 toxicity in vivo is poorly documented. The aim of our study was to investigate the presumed protective effect of NAC on hyperoxic lung injury, focusing on gamma-glutamyltransferase (gamma-GT) activity and glutathione (GSH) levels in lung tissue, epithelial lining fluid (ELF), and isolated rat type II cells immediately after their isolation and 48 h later when kept in culture in normoxia. Thirty-four male Wistar rats were divided in three groups (n = 10-14) and were exposed to air or to 60 or 85% O2 for 7 days. One-half of the rats in each group received 200 mg/kg NAC intraperitoneally one time per day from 3 days before exposure until the end of the experiment, and the other one-half received the vehicle. In the 85% O2-exposed animals, NAC led to more respiratory distress and weight loss. NAC did not prevent the rise in bronchoalveolar lavage lactate dehydrogenase and alkaline phosphatase, but it did prevent the rise in calculated ELF volume. NAC decreased GSH levels (1.4-fold) and gamma-GT activity (1.8-fold) in the air-exposed type II cells. In the 60% O2-exposed group, no effects of NAC were seen (except for a decrease in gamma-GT mRNA expression), but, in the 85% O2-exposed group, NAC gave rise to higher GSH (2.6-fold) and higher gamma-GT activity (2.9-fold) in the ELF and lower GSH (6.9-fold) and higher gamma-GT activity (3.6-fold) in the type II cells. Even in culture, GSH levels remained 1.5-fold lower than in the cells from the air-exposed animals and 2-fold lower than in the cells from the 85% O2-exposed animals. There was increased DNA damage (as assessed by thymidine incorporation) and apoptosis after hyperoxia, especially after 60% O2, and this effect was amplified after NAC treatment. Although protective at the endothelial side, NAC treatment led to adverse effects at the epithelial side, despite, or probably because of, restoration of the ELF GSH levels in the presence of high O2 levels. Because NAC is rapidly metabolized to cysteine, it is plausible that the effects of NAC are manifested through the toxic effects of cysteine.

Alveolar fluid glutathione is not reduced in asymptomatic HIV-seropositive subjects.

Glutathione is an important antioxidant tripeptide that is found in high concentrations in the epithelial lining fluid (ELF) of the lung. Previous investigators demonstrated a deficiency of glutathione (GSH) in the epithelial lining fluid of human immunodeficiency virus (HIV)-seropositive patients. The current investigation performed bronchoalveolar lavage (BAL) on 59 asymptomatic HIV-seropositive subjects (mean CD4: 365.9 +/- 31.2 cells/mm3) and 12 normal control subjects. The volume of ELF and the concentration of glutathione and oxidized glutathione were determined. The concentration of total GSH in ELF was not significantly different in HIV-seropositive individuals compared with normal subjects (628.1 +/- 63.9 microM versus 499.9 +/- 86.0 microM, p = 0.38). However, there was a significantly higher concentration of ELF GSH in HIV-seropositive cigarette smokers (n = 30) compared with nonsmokers (n = 29) (800.3 +/- 107.7 microM versus 443.6 +/- 45.3 microM, p = 0.004). The percentage of total GSH in the oxidized form (GSSG) was similar in both the HIV-seropositive and the normal subject groups (3.4 +/- 0.3% versus 3.0 +/- 0.4%, p = 0.559). There were no significant correlations between ELF GSH or GSSG concentrations and age, CD4 count, or pulmonary function. There was, however, a significant negative correlation between BAL lymphocyte percentage and GSH. The current study suggests that for those patients whose HIV infection is at a relatively early phase, the levels of GSH in the lung ELF are normal.

Augmentation of glutathione in the fluid lining the epithelium of the lower respiratory tract by directly administering glutathione aerosol.

Glutathione (GSH), a cysteine-containing tripeptide, functions as an antioxidant, provides cells with cysteine, and is required for optimal function of the immune system. Because the epithelial-lining fluid (ELF) of the lower respiratory tract normally contains high GSH levels and lung ELF GSH deficiency states can exist, we evaluated the feasibility of augmenting lung ELF GSH levels by (i) administering GSH to sheep i.v. and by direct aerosolization and then (ii) measuring the GSH levels in lung ELF, lung lymph, venous plasma, and urine. When GSH (600 mg) was administered i.v. (n = 11), GSH levels in venous plasma, lung lymph, and ELF rose, but only transiently, suggesting the i.v. route would not deliver adequate GSH to the alveolar epithelial surface. For directly administering GSH to the lung by the aerosol route, in vitro studies were first conducted to show that greater than 50% of a GSH solution could be converted to droplets less than 3 microns in aerodynamic diameter without oxidizing the GSH. To target functional GSH to the lower respiratory tract, an aerosolized solution of GSH (600 mg) was administered to sheep (n = 12). Significantly, the GSH level in ELF increased 7-fold at 30 min (preaerosol, 45.7 +/- 10 microM; 30-min postaerosol, 337 +/- 64 microM; P less than 0.001). The ELF GSH levels remained above baseline at 1 hr (P less than 0.01), returning toward baseline over a 2-hr period. In contrast, GSH levels in lung lymph, venous plasma, and urine were not significantly increased during the period--i.e., aerosol therapy selectively augmented the GSH levels only at the lung epithelial surface. Thus, functional GSH can be delivered by aerosol to directly augment the ELF GSH levels of the lower respiratory tract. Such an approach may prove useful in treating a variety of lung disorders.