MAG-EPA resolves lung inflammation in an allergic model of asthma.

BACKGROUND: Asthma is a chronic disease characterized by airways hyperresponsiveness, inflammation and airways remodelling involving reversible bronchial obstruction. Omega-3 fatty acids and their derivatives are known to reduce inflammation in several tissues including lung. OBJECTIVES: The effects of eicosapentaenoic acid monoacylglyceride (MAG-EPA), a newly synthesized EPA derivative, were determined on the resolution of lung inflammation and airway hyperresponsiveness in an in vivo model of allergic asthma. METHODS: Ovalbumin (OVA)-sensitized guinea-pigs were treated or not with MAG-EPA administered per os. Isometric tension measurements, histological analyses, homogenate preparation for Western blot experiments or total RNA extraction for RT-PCR were performed to assess the effect of MAG-EPA treatments. RESULTS: Mechanical tension measurements revealed that oral MAG-EPA treatments reduced methacholine (MCh)-induced bronchial hyperresponsiveness in OVA-sensitized guinea-pigs. Moreover, MAG-EPA treatments also decreased Ca(2+) hypersensitivity of bronchial smooth muscle. Histological analyses and leucocyte counts in bronchoalveolar lavages revealed that oral MAG-EPA treatments led to less inflammatory cell recruitment in the lung of OVA-sensitized guinea-pigs when compared with lungs from control animals. Results also revealed a reduction in mucin production and MUC5AC expression level in OVA-sensitized animals treated with MAG-EPA. Following MAG-EPA treatments, the transcript levels of pro-inflammatory markers such as IL-5, eotaxin, IL-13 and IL-4 were markedly reduced. Moreover, per os MAG-EPA administrations reduced COX2 over-expression in OVA-sensitized animals. CONCLUSION AND CLINICAL RELEVANCE: We demonstrate that MAG-EPA reduces airway hyperresponsiveness and lung inflammation in OVA-sensitized animals, a finding consistent with a decrease in IL-4, IL-5, IL-13, COX-2 and MUC5AC expression levels in the lung. The present data suggest that MAG-EPA represents a new potential therapeutic strategy for resolving inflammation in allergic asthma.

Severe anaphylaxis caused by orally administered vancomycin to a patient with Clostridium difficile infection.

We report the first case of anaphylaxis to oral vancomycin in a cystic fibrosis patient with severe and relapsing Clostridium difficile infection (CDI) refractory to metronidazole. The patient's colitis has been successfully treated with a combination of intravenous metronidazole and tigecycline.

Taurine modulation of hypochlorous acid-induced lung epithelial cell injury in vitro. Role of anion transport.

Airway secretions of cystic fibrosis patients were found to contain high concentrations of taurine, which decreased with antibiotic therapy during acute respiratory exacerbations. Taurine, in a 1:1 molar ratio with HOCl/OCl-, caused a 10-fold increase in the amount of HOCl/OCl- needed to induce cytotoxicity to the cat lung epithelial cell line, AKD. Although DMSO protected cells against HOCl/OCl(-)-mediated injury, the presence of an equimolar concentration of taurine with HOCl/OCl- prevented DMSO from protecting cells and sulfhydryl groups against oxidation, suggesting the formation of taurine chloramines. Spectral properties confirmed the formation of monochloramines and dichloramines. Chloride-free buffer, DIDS, and low temperature (4 degrees C) each protected the cells against taurine/HOCl/OCl-, indicating that taurine chloramine uptake through anion transport pathways was required to induce cytotoxicity. A molar excess of taurine inhibited cytotoxicity, to induce cytotoxicity. A molar excess of taurine inhibited cytotoxicity, by decreasing taurine dichloramines and increasing the formation of less toxic taurine monochloramines. We conclude that taurine can protect lung epithelial cells by converting HOCl/OCl- to anionic monochloramines, but that taurine dichloramines can be toxic to respiratory epithelial cells through mechanisms that depend upon epithelial cell anion transport.

Antioxidant macromolecules in the epithelial lining fluid of the normal human lower respiratory tract.

We hypothesized that the alveolar structures may contain extracellular macromolecules with antioxidant properties to defend against oxidants. To evaluate this 51Cr-labeled human lung fibroblasts (HFL-1) and cat lung epithelial cells (AKD) were exposed to a H2O2-generating system and alveolar epithelial lining fluid (ELF) from healthy nonsmokers was tested for its ability to protect the lung cells from H2O2-mediated injury. The ELF provided marked antioxidant protection, with most from a H2O-soluble fraction in the 100-300-kD range. Plasma proteins with anti-H2O2 properties were in insufficient concentrations to provide the antioxidant protection observed. However, catalase, a normal intracellular antioxidant, was present in sufficient concentration to account for most of the observed anti-H2O2 properties of ELF. Depletion of ELF with an anticatalase antibody abolished the anti-H2O2 macromolecular defenses of ELF. Since catalase is not normally released by cells, a likely explanation for its presence in high concentrations in normal ELF is that it is released by lung inflammatory and parenchymal cells onto the epithelial surface of the lower respiratory tract during their normal turnover and collects there due to the slow turnover of ELF. It is likely that catalase in the ELF of normal individuals plays a role in protecting lung parenchymal cells against oxidants present in the extracellular milieu.

Oxidants spontaneously released by alveolar macrophages of cigarette smokers can inactivate the active site of alpha 1-antitrypsin, rendering it ineffective as an inhibitor of neutrophil elastase.

Current concepts relating to the pathogenesis of emphysema associated with cigarette smoking is that an imbalance exists within the lower respiratory tract between neutrophil elastase and the local anti-neutrophil elastase screen, enabling uninhibited neutrophil elastase to destroy the alveolar structures over time. The possible role of alveolar macrophages in contributing to this imbalance was investigated by evaluating the ability of cigarette smokers' alveolar macrophages to inactivate alpha 1-antitrypsin (alpha 1AT), the major anti-neutrophil elastase of the human lower respiratory tract. In vitro, alveolar macrophages of smokers spontaneously released 2.5-fold more superoxide anion and eightfold more H2O2 than macrophages of nonsmokers (P less than 0.01, both comparisons). Using a model system that reproduced the relative amounts of alveolar macrophages and alpha 1AT found in the epithelial lining fluid of the lower respiratory tract, we observed that smokers' macrophages caused a 60 +/- 5% reduction in the ability of alpha 1AT to inhibit neutrophil elastase. In marked contrast, under the same conditions, nonsmokers' macrophages had no effect upon the anti-neutrophil elastase function of alpha 1AT. Addition of superoxide dismutase, catalase, mannitol, and methionine prevented inactivation of alpha 1AT by smokers' macrophages, implying that the release of oxidants mediated the inactivation of alpha 1AT. In addition, by utilizing a recombinant DNA produced modified form of alpha 1AT containing an active site substitution (met358----val), the inactivation of alpha 1AT by smokers' alveolar macrophages was prevented, suggesting that the smokers' macrophages inactivate alpha 1AT by oxidizing the active site of the alpha 1AT molecule. These results suggest that in cigarette smokers, the alveolar macrophage can modulate the activity of alpha 1AT as an inhibitor of neutrophil elastase and thus play a role in the pathogenesis of emphysema associated with cigarette smoking.

Oxidant-mediated epithelial cell injury in idiopathic pulmonary fibrosis.

Lung inflammatory cells of patients with idiopathic pulmonary fibrosis (IPF) were evaluated for their ability to injure 51Cr-labeled AKD alveolar epithelial cells in the presence and absence of IPF alveolar epithelial lining fluid (ELF). The IPF cells were spontaneously releasing exaggerated amounts of superoxide (O.2) and hydrogen peroxide (H2O2) compared with normal (P less than 0.02). Cytotoxicity of the AKD cells was markedly increased when the IPF inflammatory cells were incubated with autologous ELF (P less than 0.02). The majority of IPF patients had ELF myeloperoxidase levels above normal (P less than 0.002). Incubation of IPF ELF with AKD cells in the presence of H2O2 caused increased cellular injury (P less than 0.01 compared with control), which was suppressed by methionine, a myeloperoxidase system scavenger. IPF patients with high concentrations of ELF myeloperoxidase deteriorated more rapidly than those with low ELF myeloperoxidase (P less than 0.05). Thus, IPF is characterized by an increased spontaneous production of oxidants by lung inflammatory cells, the presence of high concentrations of myeloperoxidase in the ELF of the lower respiratory tract, and a synergistic cytotoxic effect of alveolar inflammatory cells and ELF on lung epithelial cells, suggesting oxidants may play a role in causing the epithelial cell injury of this disorder.

Direct correlation of glutathione and ascorbate and their dependence on age and season in human lymphocytes.

BACKGROUND: Endogenous reactive oxygen species appear to contribute to aging and cancer and dietary antioxidants, present in fruit and vegetables, counteract these effects. OBJECTIVE: The objective was to examine the association between intracellular glutathione, ascorbate (vitamin C), and alpha-tocopherol (vitamin E) in human lymphocytes. DESIGN: The study group consisted of 240 healthy nonsmoking volunteers with an approximately equal number of male and female subjects subdivided into 3 age groups: 18-39, 40-59, and >/=60 y). Glutathione, glutathione disulfide, ascorbate, and alpha-tocopherol were measured in lymphocytes by HPLC. RESULTS: The average concentration of antioxidants in lymphocytes was 27 +/- 8 nmol/mg protein for glutathione, 21 +/- 8 nmol/mg protein for ascorbate, and 0.4 +/- 0.2 nmol/mg protein for alpha-tocopherol. There was a strong positive correlation between glutathione and ascorbate (r = 0.62, P < 0.001). No correlation was observed for glutathione and ascorbate with alpha-tocopherol. The concentration of glutathione in lymphocytes was inversely correlated with age (r = -0.19, P < 0.01), as was that of ascorbate (r = -0.22, P < 0.01), with 10-20% lower values in elderly than in young and elderly subjects. The concentrations of glutathione in lymphocytes were as much as 25% higher and those of ascorbate were as much as 38% higher during the summer than during the winter. The seasonal variation of ascorbate in lymphocytes was described by a linear function for age and a periodic sine function for season. CONCLUSION: Glutathione and ascorbate are directly correlated in human lymphocytes.

Spectrum of alveolitis in quartz-exposed human subjects.

To characterize silica-induced alveolitis in human subjects, we studied 22 workers in the granite stone cutting industry of Quebec and compared results with those of 22 manual workers without quartz exposure (group 1). All were nonsmokers and were of comparable age. On the basis of chest roentgenogram, seven were without disease (group 2), nine had silicosis without coalescence/conglomeration (group 3), and six had silicosis with coalescence/conglomeration (group 4). The alveolitis in subsets of silica-exposed workers with distinct clinical stages of disease was found to have distinct biologic characteristics.

Normal alveolar epithelial lining fluid contains high levels of glutathione.

The epithelial cells on the alveolar surface of the human lower respiratory tract are vulnerable to toxic oxidants derived from inhaled pollutants or inflammatory cells. Although these lung cells have intracellular antioxidants, these defenses may be insufficient to protect the epithelial surface against oxidants present at the alveolar surface. This study demonstrates that the epithelial lining fluid (ELF) of the lower respiratory tract contains large amounts of the sulfhydryl-containing antioxidant glutathione (GSH). The total glutathione (the reduced form GSH and the disulfide GSSG) concentration of normal ELF was 140-fold higher than that in plasma of the same individuals, and 96% of the glutathione in ELF was in the reduced form. Compared with nonsmokers, cigarette smokers had 80% higher levels of ELF total glutathione, 98% of which was in the reduced form. Studies of cultured lung epithelial cells and fibroblasts demonstrated that these concentrations of reduced glutathione were sufficient to protect these cells against the burden of H2O2 in the range released by alveolar macrophages removed from the lower respiratory tract of nonsmokers and smokers, respectively, suggesting that the glutathione present in the alveolar ELF of normal individuals likely contributes to the protective screen against oxidants in the extracellular milieu of the lower respiratory tract.

Antineutrophil elastase activity in cystic fibrosis serum.

The antigenic concentrations of alpha-1-antitrypsin (alpha 1AT) were measured in 13 patients with cystic fibrosis (CF) and in 11 healthy subjects. Serum alpha 1AT was purified by immunoaffinity chromatography and the antielastase activity of the purified alpha 1AT was determined by measuring the molar ratio necessary to inhibit human neutrophil elastase (HNE). The association rate constant of alpha 1AT with HNE was determined in a timed assay. The capacity of CF serum alpha 1AT to form complexes with porcine pancreatic elastase was studied by polyacrylamide gel electrophoresis. Antigenic concentrations of alpha 1AT mumol/L were markedly increased in the serum of all patients with CF (61.9 +/- 4.3 mumol/L) in comparison to a reference standard (36.7 +/- 1.8 mumol/L; P less than 0.0001). CF serum alpha 1AT was fully active against HNE, and its association rate constant in the presence of HNE was similar to that of healthy subjects. In addition, CF serum alpha 1AT formed complexes with porcine pancreatic elastase that were electrophoretically indistinguishable from those of normal serum alpha 1AT. These results indicate that patients with CF have increased serum alpha 1AT concentrations and that this antiprotease, when purified from serum, functions normally.

Nacystelyn, a novel lysine salt of N-acetylcysteine, to augment cellular antioxidant defence in vitro.

Nacystelyn (NAL), a recently-developed lysine salt of N-acetylcysteine (NAC), and NAG, both known to have excellent mucolytic capabilities, were tested for their ability to enhance cellular antioxidant defence mechanisms. To accomplish this, both drugs were tested in vitro for their capacity: (1) to inhibit O2- and H2O2 in cell-free assay systems; (2) to reduce O2- and H2O2 released by polymorphonuclear leukocytes (PMN); and (3) for their cellular glutathione (GSH) precursor effect. In comparison with GSH, NAL and NAC inhibited H2O2, but not O2-, in cell-free, in vitro test systems in a similar manner. The anti-H2O2 effect of these drugs was as potent as that of GSH, an important antioxidant in mammalian cells. To enhance cellular GSH levels, increasing concentrations (0-2 x 10(-4) mol l-1) of both substances were added to a transformed alveolar cell line (A549 cells). After NAC administration (2 x 10(-4) mol l-1), total intracellular GSH (GSH + 2GSSG) levels reached 4.5 +/- 1.1 x 10(-6) mol per 10(6) cells, whereas NAL increased GSH to 8.3 +/- 1.6 x 10(-6) mol per 10(6) cells. NAC and NAL administration also induced extracellular GSH secretion; about two-fold (NAC), and 1.5-fold (NAL), respectively. The GSH precursor potency of cystine was about two-fold higher than that of NAL and NAC, indicating that the deacetylation process of NAL and NAC slows the ability of both drugs to induce cellular glut production and secretion. Buthionine-sulphoximine, which is an inhibitor of GSH synthetase, blocked the cellular GSH precursor effect of all substances. In addition, these data demonstrate that NAC and NAL reduce H2O2 released by freshly-isolated cultured blood PMN from smokers with chronic obstructive pulmonary disease (COPD) (n = 10) in a similar manner (about 45% reduction of H2O2 activity by NAC or NAL at 4 x 10(-6) mol l-1). In accordance with the results obtained from cell-free, in vitro assays, O2- released by PMN was not affected. Ambroxol (concentrations: 10(-9)-10(-3) mol l-1) did not reduce activity levels of H2O2 and O2- in vitro. Due to the basic effect of dissolved lysine, which separates easily in solution from NAL, the acidic function of the remaining NAC molecule is almost completely neutralized [at concentration 2 x 10(-4) M: pH 3.6 (NAC), pH 6.4 (NAL)]. Due to their function as H2O2 scavengers, and due to their ability to enhance cellular glutathione levels, NAL and NAC both have potent antioxidant capabilities in vitro. The advantage of NAL over NAC is two-fold; it enhances intracellular GSH levels twice as effectively, and it forms neutral pH solutions whereas NAC is acidic. Concluding from these in vitro results, NAL could be an interesting alternative to enhance the antioxidant capacity at the epithelial surface of the lung by aerosol administration.

Cigarette smoke-induced proteostasis imbalance in obstructive lung diseases.

The airway and alveolar surface is exposed daily to 8,000 L of air containing oxygen, particles, bacteria, allergens and pollutants, all of which have the potential to induce oxidative stress within cells. If one is also a cigarette smoker, then the exposure to reactive oxidants increases exponentially. More than any other tissue, the lung is at risk of undergoing oxidative changes in protein expression, structure and function. The oxidant burden of chronic cigarette smoke exposure can overwhelm the lung cells' capacity to maintain proteostasis, a process of regulated protein synthesis, folding and turnover. Somewhat surprisingly, most chronic cigarette smokers do not develop chronic obstructive pulmonary disease (COPD), likely because cells initiate a highly effective unfolded protein response (UPR) in the presence of oxidant-derived endoplasmic reticulum (ER) stress that allows cells to survive. The UPR initiates several signaling pathways that decrease protein translation, limit cell cycle progression, increase protein degradation and chaperone-mediated protein folding, and activate the transcription factor Nrf2 that induces antioxidant gene expression. Each of these actions decreases ER stress in a process of "healthy proteostasis". If these responses are insufficient, apoptosis ensues. In this article, we review the mechanisms of healthy and dysfunctional proteostasis related to cigarette smoke exposure and COPD.

DNase I acutely increases cystic fibrosis sputum elastase activity and its potential to induce lung hemorrhage in mice.

The potential of DNase I to increase cystic fibrosis sputum elastase activity and lung damage was evaluated. Sputum from CF patients induced little lung hemorrhage when instilled intranasally in C57BL/6 mice. However, sputum treated in vitro by the addition of 1 mg/ml bovine DNase I showed increased neutrophil elastase activity (7.97 +/- 1.56 versus 3.91 +/- 0.62 microM, p < 0.01) and induced marked lung hemorrhage in mice (bronchoalveolar lavage fluid hemoglobin = 192.8 +/- 40.7 versus 44.5 +/- 12.0 microg/ml, p < 0.01). These effects were not observed with DNase I alone in phosphate buffer and were suppressed by the human neutrophil elastase inhibitor methoxysuccinyl-alanyl-alanyl-prolyl-valine-chloromethylketone (MeOSAAPV-CMK). In vivo administration of 2.5 mg aerosolized recombinant human DNase I to patients with CF resulted in a 2.2-fold increase of sputum elastase activity within 1 h of treatment. Elastase levels returned to pre-rhDNase therapy levels 24 h after aerosol treatment. Sputum collected 1 h after rhDNase on 4 separate days from two of six patients in which elastase levels were highest, induced lung hemorrhage when instilled intranasally in mice. We conclude that DNase I therapy of patients with cystic fibrosis can acutely increase the elastase activity of sputum and also its potential to induce hemorrhage in the murine lung.

Glutathione and inflammatory disorders of the lung.

Glutathione (GSH) is an essential tripeptide present in most eukaryotic cells. Because of its sulfhydryl group, GSH is a versatile molecule capable of protecting cells against oxidants and toxic xenobiotics. However, it also plays key roles in multiple metabolic pathways, such as the synthesis of certain leukotrienes, proteins, and DNA precursors as well as the activation of enzymes, the regulation of immune responses and others. Not only is GSH synthesized by cells for local use but it also participates in an elaborate intercellular exchange process regulated by the gamma-glutamyl cycle. Extracellular GSH in plasma and in alveolar epithelial lining fluid is thus subject to variations according to the degree of expression of gamma-glutamyl cycle enzymes and the rate of consumption of GSH by electrophilic molecules. Bronchoalveolar lavage has allowed us to observe many of these variations of GSH within the extracellular environment of the normal and diseased human lung. Studies of lung GSH have lead to a better understanding of pathogenic processes and have stimulated investigations of novel therapeutic approaches in lung inflammatory disorders.

Aerosolized prolastin suppresses bacterial proliferation in a model of chronic Pseudomonas aeruginosa lung infection.

High levels of active neutrophil elastase (HNE) are present in the respiratory secretions of patients with cystic fibrosis (CF). We hypothesized that aerosolized Prolastin (alpha(1)-protease inhibitor or alpha(1)PI, purified from human blood) could suppress airway neutrophil inflammation and accelerate bacterial clearance from the lung in a model of chronic Pseudomonas aeruginosa lung infection. Because human alpha(1)PI effectively inhibits rat as well as human neutrophil elastase (NE) activity in vitro, we choose to test this hypothesis using a rat agar bead model of chronic P. aeruginosa lung infection. In this model, aerosolized Prolastin significantly decreased elastase activity (p < 0.01), lung neutrophil counts (p < 0.01), and bacterial colony counts (p < 0.01). Prolastin had no direct bactericidal effect on P. aeruginosa in vitro. Lung tissue histopathology revealed a marked decrease in lung inflammation in animals treated with Prolastin. These studies indicate that Prolastin can significantly decrease the elastase burden in the chronically infected lung. In addition, not only does Prolastin suppress lung inflammation, but it also markedly decreases P. aeruginosa density in a rat model of chronic P. aeruginosa lung infection. These data suggest that aerosolized alpha(1)PI may represent a useful nonantibiotic adjunct in the treatment and control of infection and inflammation associated with CF lung disease.

Increased procollagen III aminoterminal peptide-related antigens and fibroblast growth signals in the lungs of patients with idiopathic pulmonary fibrosis.

Idiopathic pulmonary fibrosis (IPF) is a chronic lung disorder characterized by an increased density of inflammatory cells, fibroblasts, and collagen within the lung parenchyma. To gain insights into the mechanisms leading to the increased density of fibroblasts and altered collagen metabolism in the IPF lung, bronchoalveolar lavage fluid from normal subjects and patients with IPF or sarcoidosis was analyzed for (1) the presence of antigenic material related to the aminoterminal propeptide domain of type III procollagen, and (2) fibroblast growth-promoting activity in the extracellular milieu of the lower respiratory tract. Whereas bronchoalveolar lavage fluid (BALF) type III procollagen aminoterminal peptide-related antigen levels in 59 patients with sarcoidosis were similar to the levels of control subjects (p greater than 0.10), 31 patients with IPF had markedly increased levels (12-fold over controls; p less than 0.025, IPF versus controls; p less than 0.01, IPF versus sarcoidosis). Type III procollagen aminoterminal peptide-related antigen levels correlated with an increase in the ability of BALF to stimulate fibroblast proliferation (p less than 0.05). Furthermore, BALF from patients with IPF markedly stimulated human lung fibroblast proliferation in vitro (199% increase, p less than 0.01), whereas lavage fluid from patients with sarcoidosis and from control subjects did not. The enhanced fibroblast proliferation induced by IPF BALF occurred in the absence of serum and exogenous growth factors, suggesting that both competence- and progression-type growth factors were present in the lavage fluid.(ABSTRACT TRUNCATED AT 250 WORDS)

Hyaluronan (hyaluronic acid) in lung lavage of asbestos-exposed humans and sheep.

The concentration of hyaluronan was measured in the bronchoalveolar lavage fluid (BALF) of 18 control subjects and 27 workers from the asbestos mills and mines of Québec, 9 without asbestosis and 18 with asbestosis. Hyaluronan was also measured in the BALF of 9 control sheep exposed to 100 ml phosphate-buffered saline (PBS) at 10 day intervals for 39 months, and 13 sheep exposed at the same intervals to 100 mg chrysotile in 100 ml PBS for 24 months. At month 24, the asbestos-exposed sheep were classified into 3 groups: (A) 4 sheep exposed to PBS alone, (B) 4 sheep exposed to 10 mg chrysotile asbestos every 10 days, and (C) 5 sheep exposed to 100 mg chrysotile asbestos every 10 days for 15 months. The BALF hyaluronan averaged 53.9 +/- 7.4 ng/ml in human controls, 67.5 +/- 10.3 ng/ml in asbestos-exposed workers without asbestosis, and 206 +/- 83 ng/ml in workers with asbestosis (p less than 0.05 vs. normal). In the control sheep, BALF hyaluronan was 34.7 +/- 6.9 ng/ml, and it was 31.5 +/- 17.8 ng/ml in the low-dosage asbestos-exposed group (A), 83.0 +/- 27.7 ng/ml in the intermediate-dose group (B), and 248.0 +/- 134.7 ng/ml in the high-dosage group (C) (p less than 0.05 vs. controls). In contrast, the release of plasminogen activator, a protease that may play a role in limiting the fibrotic process, was increased in group A, but not in groups B and C. In conclusion, BALF hyaluronan constitutes an indicator of lung interstitial tissue changes that may reflect the activity of the fibrosing alveolitis associated with chronic asbestos exposure.

Extracellular glutathione suppresses human lung fibroblast proliferation.

Alveolar epithelial lining fluid glutathione (GSH) is markedly decreased in patients with idiopathic pulmonary fibrosis (IPF). Because patients with IPF have exaggerated numbers of fibroblasts in their lower respiratory tract, we hypothesized that GSH can suppress lung fibroblast proliferation. To verify this hypothesis, we examined the ability of GSH to suppress human lung fibroblast (ATCC; HFL-1) proliferation in vitro in the presence of either IPF bronchoalveolar lavage fluid (BAL) or calf serum (CS). Both CS at a concentration of 10% and IPF BAL markedly increased fibroblast proliferation when compared to cells grown without CS or IPF BAL (10% CS = 93 +/- 4%, P less than 0.001; IPF BAL = 47 +/- 4%, P less than 0.001). In the presence of physiologic concentrations of GSH (0 to 500 microM), both CS- and IPF BAL-mediated fibroblast proliferation were markedly reduced, with 500 microM GSH inducing complete inhibition. Interestingly, glutathione disulfide (GSSH) and S-methylglutathione did not suppress proliferation, whereas various sulfhydryl-containing molecules (cysteine, N-acetylcysteine, 2-mercaptoethanol, and low concentrations of dithiothreitol) induced an inhibition of fibroblast proliferation similar to that observed with GSH. Most of the suppressive effect of GSH was mediated at the cell level since incubation of fibroblasts with 500 microM GSH for 1 h completely blocked the ability of the cells to subsequently proliferate in the presence of untreated 10% CS. Treatment of CS with 500 microM GSH for 1 h followed by removal of GSH by molecular sieve chromatography had no detectable effect on fibroblast proliferation.(ABSTRACT TRUNCATED AT 250 WORDS)