Tumor Necrosis Factor/cachectin Research Articles

Tumor Necrosis Factor-Induced Endothelial Tissue Factor Is Associated With Subendothelial Matrix Vesicles But Is Not Expressed on the Apical Surface

Abstract Cultured endothelial cells can be induced by tumor necrosis factor/cachectin (TNF) and other cytokines to synthesize the procoagulant cofactor tissue factor (TF). Intact monolayers of TNF- treated endothelial cells showed only minimal TF activity. In contrast, after permeabilization of these monolayers with detergent (saponin, 0.02%), there was approximately 10- to 20-fold increase in TF-mediated, factor VIIa-dependent factor Xa formation. Extracellular matrix derived from TNF-treated endothelium, prepared after removing the cells by hypotonic lysis or ammonium hydroxide (0.1 N), also had similarly enhanced TF activity. Incubation with a blocking monoclonal antibody to TF inhibited the procoagulant activity of both TNF-stimulated endothelial cells, whether they were intact or permeabilized, and of their matrices. However, when the apical cell surface was pretreated with anti-TF antibody, washed, and then cells were lysed with water or permeabilized with saponin, similar augmentation of TF activity was still observed, suggesting the presence of a pool of TF to which the antibody did not initially gain access. Consistent with this concept, the presence of TF in the matrix of TNF-treated endothelial cells was shown by immunoblotting and morphologic studies; cultured endothelial monolayers and the native endothelium of aortic segments after exposure to TNF showed TF in extracellular matrix, associated with vesicles. In contrast, TF was virtually undetectable on the apical endothelial surface. Taken together, these findings suggest that endothelial TF can be present in a cryptic pool that only gains access to the blood after alteration in the integrity of the endothelial monolayer.

Tumor necrosis factor-induced endothelial tissue factor is associated with subendothelial matrix vesicles but is not expressed on the apical surface

Cultured endothelial cells can be induced by tumor necrosis factor/cachectin (TNF) and other cytokines to synthesize the procoagulant cofactor tissue factor (TF). Intact monolayers of TNF-treated endothelial cells showed only minimal TF activity. In contrast, after permeabilization of these monolayers with detergent (saponin, 0.02%), there was approximately 10- to 20-fold increase in TF-mediated, factor VIIa-dependent factor Xa formation. Extracellular matrix derived from TNF-treated endothelium, prepared after removing the cells by hypotonic lysis or ammonium hydroxide (0.1 N), also had similarly enhanced TF activity. Incubation with a blocking monoclonal antibody to TF inhibited the procoagulant activity of both TNF-stimulated endothelial cells, whether they were intact or permeabilized, and of their matrices. However, when the apical cell surface was pretreated with anti-TF antibody, washed, and then cells were lysed with water or permeabilized with saponin, similar augmentation of TF activity was still observed, suggesting the presence of a pool of TF to which the antibody did not initially gain access. Consistent with this concept, the presence of TF in the matrix of TNF-treated endothelial cells was shown by immunoblotting and morphologic studies; cultured endothelial monolayers and the native endothelium of aortic segments after exposure to TNF showed TF in extracellular matrix, associated with vesicles. In contrast, TF was virtually undetectable on the apical endothelial surface. Taken together, these findings suggest that endothelial TF can be present in a cryptic pool that only gains access to the blood after alteration in the integrity of the endothelial monolayer.

Hypercytokinemia in Familial Hemophagocytic Lymphohistiocytosis

AbstractFamilial hemophagocytic lymphohistiocytosis (FHL) is a frequently missed and almost uniformly fatal childhood disorder. It is characterized by fever, hepatosplenomegaly, cytopenia, coagulopathy, and hypertriglyceridemia. The pathogenesis of FHL is not known but the above clinical and laboratory findings are compatible with reported in vitro and in vivo effects of several inflammatory cytokines. We measured circulating interferon-γ (IFN-γ), tumor necrosis factor/cachectin (TNF), and interleukin-6 (IL-6) in nine children with FHL. During active disease, elevated IFN-γ was detected in seven of seven children, TNF in six of six, and IL-6 in two of six children studied. Thus, important inflammatory cytokines are augmented in active FHL and may contribute to the pathogenesis of the disease. Soluble CD8 was also increased in seven of seven children, which suggests a pathophysiologic importance of cytotoxic T lymphocytes. Because FHL appears to be associated with a systemic hypercytokinemia, our results also indicate that studies of FHL may contribute to the understanding of cytokine effects in vivo. Moreover, FHL is a hereditary disorder, suggesting that the hypercytokinemia is caused by a genetic defect in cytokine regulation.

Hypercytokinemia in familial hemophagocytic lymphohistiocytosis

Familial hemophagocytic lymphohistiocytosis (FHL) is a frequently missed and almost uniformly fatal childhood disorder. It is characterized by fever, hepatosplenomegaly, cytopenia, coagulopathy, and hypertriglyceridemia. The pathogenesis of FHL is not known but the above clinical and laboratory findings are compatible with reported in vitro and in vivo effects of several inflammatory cytokines. We measured circulating interferon-gamma (IFN-gamma), tumor necrosis factor/cachectin (TNF), and interleukin-6 (IL-6) in nine children with FHL. During active disease, elevated IFN-gamma was detected in seven of seven children, TNF in six of six, and IL-6 in two of six children studied. Thus, important inflammatory cytokines are augmented in active FHL and may contribute to the pathogenesis of the disease. Soluble CD8 was also increased in seven of seven children, which suggests a pathophysiologic importance of cytotoxic T lymphocytes. Because FHL appears to be associated with a systemic hypercytokinemia, our results also indicate that studies of FHL may contribute to the understanding of cytokine effects in vivo. Moreover, FHL is a hereditary disorder, suggesting that the hypercytokinemia is caused by a genetic defect in cytokine regulation.

Defective Tolerance to the Toxic and Metabolic Effects of Interleukin 1

The effect on food intake, body weight, and survival of mice given recombinant lipopolysaccharide (LPS), tumor necrosis factor/cachectin (TNF), or interleukin 1 (IL-1) (5 micrograms/mouse, ip, twice daily) was studied. All agents induced a rapid reduction of food intake and body weight after 1 day of treatment. Unlike TNF and LPS, IL-1 given as two daily administrations of 5 micrograms was lethal within 3 days. Mice treated with LPS or TNF rapidly developed tolerance to their anorectic effect, whereas tolerance to IL-1 required a longer time to develop and was not complete. We investigated the possible roles of changes in serum corticosterone and glucose in the effects of LPS, TNF and IL-1. A single injection of LPS, TNF, or IL-1 markedly increased serum corticosterone levels after 2 h. After only 2 days of chronic treatment, mice given LPS or TNF were refractory to induction of serum corticosterone by a subsequent injection of LPS or TNF, but mice given IL-1 for 2 days were still fully responsive to IL-1. IL-1, unlike TNF and LPS, induced a marked hypoglycemic response. Repeated administration of IL-1 sensitized to its hypoglycemic effect. This lack of adaptation to the increase of serum corticosterone and hypoglycemia was also observed when IL-1 was given at lower, nonlethal doses (0.25-1.0 microgram) and for a longer period (up to 8 days). The defective tolerance to the metabolic and toxic effects of IL-1 in this experimental model indicates that there are major differences between the in vivo biological responses to IL-1 and TNF.

Tumor necrosis factor/cachectin (TNF) induces neuroendocrine hormones changes during acute bacterial infections

Tumor necrosis factor/cachectin (TNF) induces neuroendocrine hormones changes during acute bacterial infections

Tumor necrosis factor/cachectin (TNF) induces neuroendocrine hormones changes during acute bacterial infections

Tumor necrosis factor/cachectin (TNF) induces neuroendocrine hormones changes during acute bacterial infections

Vascular permeability factor: a tumor-derived polypeptide that induces endothelial cell and monocyte procoagulant activity, and promotes monocyte migration.

Systemic infusion of low concentrations of tumor necrosis factor/cachectin (TNF) into mice that bear TNF-sensitive tumors leads to activation of coagulation, fibrin formation, and occlusive thrombosis exclusively within the tumor vascular bed. To identify mechanisms underlying the localization of this vascular procoagulant response, a tumor-derived polypeptide has been purified to homogeneity from supernatants of murine methylcholanthrene A-induced fibrosarcomas that induces endothelial tissue factor synthesis and expression (half-maximal response at approximately 300 pM), and augments the procoagulant response to TNF in a synergistic fashion. This tumor-derived polypeptide was identified as the murine homologue of vascular permeability factor (VPF) based on similar mobility on SDS-PAGE, an homologous NH2-terminal amino acid sequence, and recognition by a monospecific antibody to guinea pig VPF. In addition, VPF was shown to induce monocyte activation, as evidenced by expression of tissue factor. Finally, VPF was shown to induce monocyte chemotaxis across collagen membranes and endothelial cell monolayers. Taken together, these results indicate that VPF can modulate the coagulant properties of endothelium and monocytes, and can promote monocyte migration into the tumor bed. This suggests one mechanism through which tumor-derived mediators can alter properties of the vessel wall.

Ca2+Redistribution from Bound to Free Form Is Required for Tumor Necrosis Factor Actions in 30A5 Preadipocytes

Tumor necrosis factor/cachectin (TNF) inhibits differentiation of 30A5 preadipocytes into adipocytes. In this process, TNF inhibits the expression of the gene for acetyl-coenzyme-A carboxylase, the rate-limiting enzyme for biogenesis of long chain fatty acids. One of the early reactions caused by TNF is the Ca2+ redistribution of Ca2+ from the bound form to the free form. This Ca2+ redistribution results in a transient Ca2+ efflux. High concentrations of Mg2+ inhibit Ca2+ redistribution and efflux. This inhibition reverses the repression of acetyl-coenzyme-A carboxylase and reverses the TNF inhibition of the differentiation of 30A5 preadipocytes into adipocytes. This indicates that Ca2+ redistribution between the bound and the free form is an obligatory event in the sequence of actions caused by TNF in 30A5 cells.

Prognostic Values of Tumor Necrosis Factor/Cachectin, Interleukin-l, Interferon- , and Interferon- in the Serum of Patients with Septic Shock

Serum concentrations of immunoreactive tumor necrosis factor/cachectin (TNF), interleukin-1 beta (IL-1 beta), interferon-gamma (IFN gamma), and interferon-alpha (IFN alpha) were prospectively measured in 70 patients with septic shock to determine their evolution and prognostic values. In a univariate analysis, levels of TNF (P = .002) and IL-1 beta (P = .05) were associated with the patient's outcome, but not IFN alpha (P = .15) and IFN gamma (P = .26). In contrast, in a stepwise logistic regression analysis, the severity of the underlying disease (P = .01), the age of the patient (P = .02), the documentation of infection (nonbacteremic infections vs. bacteremias, P = .03), the urine output (P = .04), and the arterial pH (P = .05) contributed more significantly to prediction of patient outcome than the serum levels of TNF (P = .07). After 10 days, the median concentration of TNF was undetectable (less than 100 pg/ml) in the survivors, whereas it remained elevated (305 pg/ml, P = .002) in the nonsurvivors. Thus, in patients with septic shock due to various gram-negative bacteria, other parameters than the absolute serum concentration of immunoreactive TNF contributed significantly to the prediction of outcome.

Adaptation to bacterial lipopolysaccharide controls lipopolysaccharide-induced tumor necrosis factor production in rabbit macrophages.

These experiments provide an explanation for the observation that two intravenous injections of lipopolysaccharide (LPS) spaced 5 h apart in rabbits cause tumor necrosis factor/cachectin (TNF) levels to rise in the blood only after the first LPS injection. Herein we show that treatment of elicited peritoneal exudate rabbit macrophages (PEM) with two doses of LPS given 9 h apart results in a marked reduction in TNF production by the second LPS exposure. This state of hyporesponsiveness is a result of adaptation to LPS, is induced by LPS concentrations that are 1,000-fold less than required to induce TNF production (picograms vs. nanograms), is characterized by a decrease in LPS-induced TNF mRNA without any change in TNF mRNA half-life, is not changed by including indomethacin in cultures, and is specific for LPS since LPS-adapted cells display a TNF response to heat-killed Staphylococcus aureus that is at least as good as that observed in control PEM.

Tumor-necrosis factor and other cytokines in cerebral malaria: experimental and clinical data.

Evidence is presented here that tumor necrosis factor/cachectin (TNF), is of crucial importance in the pathogenesis of cerebral malaria. First, the central lesion of CM, hemorrhagic necrosis of cerebral vessels, corresponds to lesions observed during other pathological conditions associated with high serum TNF levels, such as endotoxemic shock or administration of TNF. Second, in both mouse and human, there is a close correlation between high serum TNF levels and CM. At least in mouse, high TNF levels and CM depend upon T lymphocytes of the CD4+ phenotype. Third, passive immunization against mouse TNF significantly prolongs the survival of P. berghei-infected CBA/Ca mice, and prevents the development of neurologic signs. Treatment with the anti-TNF antibody also prevents hemorrhagic necrosis of brain vessels. Fourth, in the mouse model, a cytokine cascade including at least GM-CSF, IL-3 and IFN-gamma is required for the elevation of TNF level. This cascade appears to involve two components: (a) a quantitative component: increased accumulation of macrophages results from the concomitant release of IL-3 and GM-CSF, and (b) a qualitative component: macrophage number has not only to be raised, but macrophages need to be activated by IFN-gamma. Fifth, metabolic parameters of CM and its main lesion in both mouse and human, i.e. the hemorrhagic necrosis of small brain vessels, correspond to the known properties of TNF.

Tumor necrosis factor/cachectin increases permeability of endothelial cell monolayers by a mechanism involving regulatory G proteins.

Endothelium is an important target of tumor necrosis factor/cachectin (TNF), a central mediator of the host response in endotoxemia and Gram-negative sepsis. In this report, TNF is shown to increase the permeability of endothelial cell monolayers to macromolecules and lower molecular weight solutes by a mechanism involving a pertussis toxin-sensitive regulatory G protein. Within 1-3 h of exposure to TNF (5 nM), changes in cell shape/cytoskeleton occurred that led to disruption of monolayer continuity with the formation of intercellular gaps. Correlated with these structural changes was an increase in endothelial permeability to macromolecular and lower molecular weight tracers; time-dependent, reversible increases in passage of these tracers, evident by 1-3 h, were observed after addition of TNF to cultures. Perturbation of barrier function by TNF also depended on the dose of TNF added being half-maximal by approximately 0.4 nM. Only a brief exposure (15 min) of TNF to endothelium was required to induce an increase in permeability, and this was not prevented by the presence of cycloheximide or actinomycin D. Preincubation of monolayers with pertussis toxin blocked in parallel TNF-induced increased passage of solutes and cell shape/cytoskeletal perturbation, indicating the close correlation between these changes in endothelial cell function. In contrast, pertussis toxin did not alter TNF-induced modulation of two endothelial cell coagulant properties. These data provide evidence for two intracellular pathways of TNF action that are distinguishable by pertussis toxin and provide insight into a mechanism underlying loss of solute from the intravascular space mediated by TNF: alteration in endothelial cell barrier function.

Pretreatment with recombinant murine tumor necrosis factor alpha/cachectin and murine interleukin 1 alpha protects mice from lethal bacterial infection.

Tumor necrosis factor/cachectin (TNF/C) is the principal mediator of bacterial endotoxin-induced shock and death. We found that the C3H/HeJ mouse, which is less able to produce TNF/C in response to endotoxin, has a 1,000-fold greater susceptibility to lethal infection with Escherichia coli than the TNF-responsive congenic mouse, C3H/HeN. This surprising finding suggested that this lethal peptide may also be involved in host protection. To test this hypothesis we pretreated the C3H/HeJ mouse with a combination of recombinant murine TNF/C-alpha and IL-1 alpha. This combination protected these mice against an intraperitoneal bacterial challenge of greater than 20 LD50S (nearly 2 x 10(2) CFU) that grew to a level of greater than 10(7) CFU/ml of blood and per gram of liver in untreated mice. This suggests a significant role for these cytokines in host defenses against invasive infections that require bacterial replication within the host. These protective mechanisms may not be important for less virulent organisms. These findings may have important implications for the proposed use of anti-TNF/C agents in the treatment of septic shock.

Interleukin-1, endotoxin or tumor necrosis factor/cachectin enhance the level of plasminogen activator inhibitor messenger RNA in bovine aortic endothelial cells

It is known that either endotoxin (LPS) or interleukin-1 (IL-1) increase the activity of plasminogen activator inhibitor (PAI) in the culture media of human and bovine endothelial cells. We have confirmed these results in bovine aortic endothelial cells (BAEC). To determine if this effect was mediated by increases in the level of PAI messenger RNA (mRNA) we examined the effects of these cytokines on PAI mRNA levels in BAEC, using RNA blot analyses. Treatment of BAEC with either IL-1, LPS, or human recombinant tumor necrosis factor/cachectin (TNF) dramatically increased the level of PAI mRNA. Since elevated levels of PAI will decrease fibrinolytic potential, this mechanism is in concert with the known increase in in vivo procoagulant potential induced by these agents and could contribute to thromboembolic phenomena.

Macrophages rapidly internalize their tumor necrosis factor receptors in response to bacterial lipopolysaccharide

The effect of bacterial lipopolysaccharide (LPS) on macrophage receptors for tumor necrosis factor/cachectin (TNF-R) was studied. At equilibrium, iodinated recombinant human TNF alpha (rTNF alpha) bound to 1100 +/- 200 sites/cell on macrophage-like RAW 264.7 cells with a Kd of 1.3 +/- 0.1 x 10(-9) M. Preexposure of RAW 264.7 cells to 10 ng/ml LPS for 1 h at 37 degrees C resulted in complete loss of cell surface TNF alpha binding sites. 50% loss ensued after 1 h with 0.6 ng/ml LPS, or after 15 min with 10 ng/ml LPS. Complete loss of TNF alpha binding sites occurred without change in numbers of complement receptor type 3. No decrease in TNF-R followed preexposure to LPS at 4 degrees C, nor could LPS displace 125I-rTNF alpha from its binding sites. Although TNF-R disappeared from the surface of intact macrophages following exposure to LPS, specific TNF alpha binding sites were unchanged in permeabilized macrophages, indicating that TNF-R were rapidly internalized. Conditioned media from LPS-treated RAW 264.7 cells induced 30% down-regulation of TNF-R on macrophages from LPS-hyporesponsive mice (C3H/HeJ), suggesting that a soluble macrophage product may be responsible for a minor portion of the LPS effect. Additional evidence against endogenous TNF alpha being the major cause of TNF-R internalization was the rapid onset of the effect of LPS on TNF-R compared to the reported onset of TNF alpha production, the relatively high concentrations of exogenous rTNF alpha required to mimic the effect of LPS, and the inability of TNF alpha-neutralizing antibody to block the effect of LPS. LPS-induced down-regulation of TNF-R was complete or nearly complete not only in RAW 264.7 cells, but also in primary macrophages of both human and murine origin, was less marked in human endothelial cells, and was absent in human granulocytes and melanoma cells and mouse L929 cells. Thus, in situ, macrophages and some other host cells may be resistant to the actions of TNF alpha produced during endotoxinemia, because such cells may internalize their TNF-R in response to LPS before TNF alpha is produced.

Cytokines increase rat lung antioxidant enzymes during exposure to hyperoxia.

Pretreatment with the combination of tumor necrosis factor/cachectin (TNF/C) and interleukin 1 (IL-1) increased glucose-6-phosphate dehydrogenase (G6PDH), glutathione reductase (GR), glutathione peroxidase (GPX), catalase (CAT), and superoxide dismutase (SOD) activities in lungs of rats continuously exposed to hyperoxia for 72 h, a time when all untreated rats had already died. Pretreatment with TNF/C and IL-1 also increased, albeit slightly, lung G6PDH and GR activities of rats exposed to hyperoxia for 4 or 16 h. By comparison, no differences occurred in lung antioxidant enzyme activities of TNF/C and IL-1- or saline-pretreated rats exposed to hyperoxia for 36 or 52 h; the latter is a time just before untreated rats began to succumb during exposure to hyperoxia. The results raise the possibility that TNF/C and IL-1 treatment can increase lung antioxidant enzyme activities and that increased lung antioxidant enzymes may contribute to the increased survival of TNF/C and IL-1-pretreated rats in hyperoxia for greater than 72 h.

Receptor-mediated monocytoid differentiation of human promyelocytic cells by tumor necrosis factor: synergistic actions with interferon- gamma and 1,25-dihydroxyvitamin D3 [published erratum appears in Blood 1988 Jan;71(1):272

Human myeloid leukemia cells respond to various signals by differentiating to more mature cells. This study was designed to evaluate the effects of a mononuclear phagocyte-derived factor, tumor necrosis factor/cachectin (TNF), on the proliferation and differentiation of the human cell lines HL-60 (promyelocytic) and U937 (monoblastic), and to characterize TNF receptors on these cells. TNF had no effect on HL-60 cell growth or thymidine incorporation, but it markedly inhibited that of U937 cells. HL-60 cells treated with TNF formed osteoclast-like polykaryons and developed nonspecific esterase positivity. In a dose-dependent fashion, TNF enhanced HL-60 cell nonspecific esterase activity, H2O2 production, NBT reduction, and acid phosphatase content. Together, TNF and interferon-gamma (IFN-gamma) additively and synergistically caused increases in these activities as well as the expression of HLA-DR and the monocyte antigens LeuM3 (CDw14) and OKM1 (CD11). TNF also synergistically enhanced the differentiating effects of 1,25-dihydroxyvitamin D3. The potentiating actions of D3 of IFN-gamma on the TNF effect were maximal when the two agents were present together throughout the incubation, and pretreatment with TNF augmented the subsequent response to D3, but not IFN-gamma. HL-60 and U937 cells bound 125I-labeled TNF specifically, rapidly, and reversibly with binding constants of 227 and 333 pmol/L and receptors per cell of 4,435 and 6,806 for HL-60 and U937, respectively. Scatchard plots were linear, which suggested single classes of receptors. HL-60 TNF receptors were not changed by a three-day treatment with IFN-gamma or D3. U937 and HL-60 cells internalized and degraded 125I-labeled TNF to comparable degrees. TNF has differing effects on HL-60 and U937 cells that are apparently mediated through comparable high-affinity TNF receptors. The unique responses of different cell types to TNF may be due to postreceptor factors.

Receptor-Mediated Monocytoid Differentiation of Human Promyelocytic Cells by Tumor Necrosis Factor: Synergistic Actions With Interferon-γ and 1,25-Dihydroxyvitamin D3

AbstractHuman myeloid leukemia cells respond to various signals by differentiating to more mature cells. This study was designed to evaluate the effects of a mononuclear phagocyte-derived factor, tumor necrosis factor/cachectin (TNF), on the proliferation and differentiation of the human cell lines HL-60 (promyelocytic) and U937 (monoblastic), and to characterize TNF receptors on these cells. TNF had no effect on HL-60 cell growth or thymidine incorporation, but it markedly inhibited that of U937 cells. HL-60 cells treated with TNF formed osteoclast-like polykaryons and developed nonspecific esterase positivity. In a dose-dependent fashion, TNF enhanced HL-60 cell nonspecific esterase activity, H2O2 production, NBT reduction, and acid phosphatase content. Together, TNF and interferon-γ (IFN-γ) additively and synergistically caused increases in these activities as well as the expression of HLA-DR and the monocyte antigens LeuM3 (CDw14) and OKM1 (CD11). TNF also synergistically enhanced the differentiating effects of 1,25-dihydroxyvitamin D3. The potentiating actions of D3 of IFN-γ on the TNF effect were maximal when the two agents were present together throughout the incubation, and pretreatment with TNF augmented the subsequent response to D3, but not IFN-γ. HL-60 and U937 cells bound 125I-labeled TNF specifically, rapidly, and reversibly with binding constants of 227 and 333 pmol/L and receptors per cell of 4,435 and 6,806 for HL-60 and U937, respectively. Scatchard plots were linear, which suggested single classes of receptors. HL-60 TNF receptors were not changed by a three-day treatment with IFN-γ or D3. U937 and HL-60 cells internalized and degraded 12SI-labeled TNF to comparable degrees. TNF has differing effects on HL-60 and U937 cells that are apparently mediated through comparable high-affinity TNF receptors. The unique responses of different cell types to TNF may be due to postreceptor factors.

Recombinant tumor necrosis factor/cachectin and interleukin 1 pretreatment decreases lung oxidized glutathione accumulation, lung injury, and mortality in rats exposed to hyperoxia.

Single, preexposure, parenteral injection with both recombinant tumor necrosis factor/cachectin (TNF/C) and interleukin-1 (IL-1) prolonged the survival of rats (144 +/- 9 h) in continuous hyperoxia (greater than 99% O2 at 1 atm) when compared with rats injected with boiled TNF/C and boiled IL-1 (61 +/- 2 h), TNF/C alone (61 +/- 2 h), IL-1 alone (62 +/- 2 h), or saline (64 +/- 3 h). After exposure to hyperoxia for 52 h, pleural effusion volume, pulmonary artery pressure, total pulmonary resistance, and lung morphologic damage were decreased in those rats given TNF/C and IL-1 as compared with saline-injected rats. In parallel, ratios of reduced (GSH) to oxidized (GSSG) glutathione were greater (P less than 0.05) in lungs of TNF/C + IL-1-injected rats (91 +/- 20) than of saline-injected rats (30 +/- 4) that had been exposed to hyperoxia for 52 h. No differences were found in superoxide dismutase, glutathione peroxidase, glutathione reductase, glucose-6-phosphate dehydrogenase, or catalase activities in lungs of TNF/C + IL-1- or saline-treated, hyperoxia-exposed rats. Our results indicate that pretreatment with TNF/C and IL-1 favorably altered lung glutathione redox status, decreased lung injury, and enhanced survival of rats exposed to hyperoxia.