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The serum amyloid A (SAA) proteins can be detected in the high density lipoprotein (HDL) fraction of plasma with in a few hours after an organism has sustained injury (1-4). The amount and N duration of SAA production depend upon the type of injury and its magnitude (2-6). Apo SAA proteins are cleared much more rapidly than other lipoproteins, with halflives of less than 2 hours (5). During homeostasis there is minimal, if any, SAA synthesis (2,4,7).

In order to investigate the correlation between stimulation of superoxide generation and induction of ornithine decarboxylase (ODC) by 12-O-tetradecanoylphorbol-13-acetate (TPA) we have used the macrophage cell line J774.16 and a clone derived from this line that, by contrast with the parental line, is unable to generate superoxides in response to TPA. No difference was observed between the normal and the defective cells, with respect to ODC induction by TPA over a wide range of TPA concentrations (0.2-5.0 micrograms/ml). Similar results were obtained comparing resident and caseinate-elicited mouse peritoneal macrophages. Although resident macrophages did not generate superoxides in response to TPA, they did not differ from superoxide-generating, caseinate-elicited macrophages with respect to ODC induction. These data suggest a dissociation between the stimulation of the oxidative burst by TPA and a growth factor-like effect such as ODC induction.

Mice bearing the S- 180 sarcoma displayed a depression of liver catalase and cytochrome P- 450 -dependent enzymes (ethoxycoumarin deethylase, ED) from day 6 following tumor implantation. Injection of serum obtained from tumor-bearing mice into normal mice caused depression of liver ED suggesting that a circulating factor was involved. Tumor-bearing mice did not show any significant change in serum triglycerides and food intake. By contrast, injection of endotoxin, interleukin- 1 (IL- 1 ) or tumor necrosis factor (TNF) caused not only a depression in liver ED but also a marked increase in serum triglycerides. To study the possible analogies between cancer-associated circulating factor and monokines, we studied the effect of dexamethasone (a known inhibitor of monokine synthesis) on liver ED activity in tumor-bearing mice. Dexamethasone (DEX) treatment increased (up to 60% ) liver ED activity in tumor-bearing mice. We conclude that: (i) a circulating factor is involved in cancer-associated ED depression; (ii) that this mediator is not necessarily identical to TNF or IL- 1 and (iii) that DEX reverses the depression of liver ED in cancer, possibly by inhibiting the synthesis, or the effects, of this factor.

Cloricromene, a coumarin derivative with antiaggregating and vasodilating properties, was tested in vitro on polymorphonuclear cell (PMN) adhesion to the endothelium, superoxide anion generation and chemotaxis. PMN adhesion was measured using cultured human umbilical vein endothelial cells (EC) either untreated or previously activated with interleukin-1 (IL-1). Cloricromene (5-50 microM) induced dose-related inhibition of PMN adhesion to untreated and IL-1 treated EC. Cloricromene also inhibited PMN superoxide generation induced by the tumor promoter 12-O-tetradecanoyl-phorbol-13-acetate (TPA) or by N-formyl-methionyl-leucyl-phenylalanine (FMLP). PMN and monocyte chemotaxis was evaluated by a modification of the Boyden chamber technique. Cloricromene inhibited both types of cell motility induced by FMLP in a concentration-dependent fashion. The major cloricromene metabolite (cloricromene acid) had no effect on any of the biological parameters studied up to a concentration of 500 microM. HPLC measurement showed that cloricromene accumulated in PMN within a few minutes and levels of the drug were still high after 60 min. In contrast its acid metabolite was not taken up in a significant amount during incubation periods up to 60 min. We conclude that cloricromene inhibits a series of PMN activities in vitro. This effect might be of pharmacological interest in view of the role of PMN activation in different pathophysiological conditions.

Culture supernatants from 14 mouse solid tumors, 2 mouse lymphomas, 8 human solid tumor lines and 3 human leukemia-lymphomas were examined for chemotactic activity in blind-well chemotaxis chambers using murine peritoneal macrophages and human blood monocytes as indicator cells. Culture supernatants from various murine and human solid tumors had appreciable chemotactic activity for mononuclear phagocytes. Chemotactic activity was found in murine tumors of different histology and transplantation history, including autochthonous mammary carcinomas and chemically-induced sarcomas. Chemotactic activity was not unique to neoplastic cells because is was detected also in supernatants of two preparations of mouse embryo fibroblasts and two human lung embryo fibroblast lines. Production of tumor-derived chemo-attractants did not require serum in the culture medium, was inhibited by the protein synthesis inhibitor Cycloheximide, but was unaffected by the DNA synthesis inhibitor Mitomycin C. Murine supernatants were active on human monocytes and vice-versa. A first preliminary characterization of the chemotactic activity of the human sarcoma line 8387 revealed that it was not dialyzable, that most of the activity was retained at 56deg;C for 30 min, but not at 100deg;C, and that it was susceptible to proteolytic enzymes (trypsin and proteinase K) but unaffected by DNase and RNase. Upon fractionation on a Sephadex G-75 column, the activity eluted in a single, relatively broad peak in the cytocrome C region, corresponding to an apparent molecular weight of about 12,000. In the heterogeneous series of murine solid tumors studied, a significant, though far from absolute, correlation (r=0.71, p=0.013) was found between chemotactic activity in culture supernatants (expressed as area under the chemotaxis titration curve) and the percentage of tumor-associated macrophages. It is suggested that tumor-derived chemotactic factor(s) play a role in the regulation of the macrophage content of neoplastic tissues.

Monosidum glutamate (MSG) given by gavage to 7-day-old mice at 2 g/kg body weight (b.wt.) as a 20% solution w/v resulted in a 27% increase in the glutamic acid (GA) content in the nucleus arcuatus of the hypothalamus (NAH). When MSG was administered by gavage to adult mice at 4 g/kg b.wt. as a 20% solution w/v, GA levels in NAH remained unchanged. Serum osmolality, measured after oral MSG, was elevated in infant mice but was unaffected in adults.

Supernatants from freshly disaggregated human ovarian carcinomas maintained in vitro for 24 hr, from primary ovarian carcinoma cultures (4-6 days in culture) and from established ovarian cancer cell lines were examined for chemotactic activity on blood monocytes in blind-well chemotaxis chambers. Tumor-cell culture supernatants induced migration of peripheral blood monocytes across polycarbonate filters with considerable heterogeneity among different tumors. Induction of migration occurred only in the presence of a gradient between the lower and upper compartments of the chamber. Chemotactic activity was characterized by means of supernatants from primary ovarian carcinoma cultures. Chemotactic factor(s) was (were) produced in serum-free conditions and the production was inhibited by emetine but not by mitomycin C. The activity was destroyed by exposure to proteolytic enzymes and by heating at 100 degrees C but was unaffected by RNase, DNase, lipase and exposure to extreme pH values or heating at 56 degrees C. Upon fractionation on Sephadex G 75, the activity eluted as a single peak in the cytochrome C region, corresponding to an apparent molecular weight of about 12 kd. The percentage of macrophages was assessed in 25 freshly disaggregated tumor specimens. Ovarian carcinomas were heterogeneous in their macrophage content with values ranging from 4 to 36%. A significant (r = 0.62; p = 0.00097), though far from absolute, correlation was found between chemotactic activity of culture supernatants and percentage of tumor-associated macrophages. Tumor-derived chemotactic factor(s) could be one of the mechanisms involved in the regulation of the macrophage content of human ovarian carcinomas.

Rats injected with interleukin-1 (10 micrograms) and tumor necrosis factor (10 micrograms) and then exposed continuously to hyperoxia (greater than 99% O2, 1 atm) survived longer, had increased lung reduced/oxidized glutathione ratios, smaller pleural effusions, less pulmonary hypertension and improved arterial blood gases. The percentage of animals surviving for 72 hours in hyperoxia increased from 8% to 94%. Although relatively small increases in glutathione redox cycle enzymes occurred four and sixteen hours following cytokine injection, dramatic increases in all major antioxidant enzymes including superoxide dismutase, glucose-6-phosphate dehydrogenase, glutathione reductase, glutathione peroxidase, and catalase had occurred following 72 hours of exposure to hyperoxia. The protective effect of IL-1 + TNF against lethal pulmonary O2 toxicity could be partially inhibited by pre-injection of lysine acetylsalicylate or, less effectively, of ibuprofen. Recent studies have suggested that both IL-1 and TNF can induce manganese (mitochondrial) superoxide dismutase mRNA and protein synthesis in a variety of cell types. Preliminary studies suggest that IL-1 alone, in ample dosage, can provide protection against lethal pulmonary O2 toxicity. Future studies should be directed toward identification of acute phase changes in lung antioxidant enzymes, surfactant proteins and/or lipid components, enzymes needed for synthesis of surfactant phospholipids, and/or other protective proteins. Additional work also needs to be done in identifying the lung cell types in which early enzyme induction occurs. These studies should provide a better understanding of mechanisms whereby protection against pulmonary O2 toxicity can occur. An understanding of the molecular mechanisms inducing protective proteins should lead to more precise pharmacologic control of these processes.

The effect of a single dose of bacterial endotoxin (lipopolysaccharide, LPS) was compared with that of tumor implantation in mice on the activity of several hepatic cytochrome P-450-dependent monooxygenases. These included ethoxycoumarin O-deethylase, p-nitrophenol hydroxylase, aminopyrine N-demethylase, pentoxyresorufin O-depentylase, ethoxyresorufin O-deethylase and testosterone hydroxylase. For this purpose, mice were treated i.p. with 5 micrograms of LPS or implanted in the right paw with S 180 sarcoma. A comparable depression (30-50%) of total microsomal P-450 content as well as of the different P-450 monooxygenase activities tested was observed in LPS-treated mice (24 h after LPS) and in tumor bearing mice (12 days after implantation). The lack of differences in the pattern of depression of microsomal enzymes between LPS-treated and tumor-bearing mice suggests that a common mechanisms might be involved in the depression of P-450 by LPS or S-180 implantation.

As indicated by its name, tumor necrosis factor (TNF), cloned in 1985, was originally described as a macrophage-derived endogenous mediator that can induce hemorrhagic necrosis of solid tumors and kill some tumor cell lines in vitro. Unfortunately, its promising use as an anticancer agent was biased by its toxicity, which was clear soon from the first clinical trials with TNF in cancer. Almost at the same time TNF was being developed as an anticancer drug, it became clear that TNF was identical to a mediator responsible for cachexia associated with sepsis, which was termed cachectin. This research led to the finding that TNF is, in fact, the main lethal mediator of sepsis and to the publication of a huge number of articles showing that TNF inhibits the toxic effects of bacterial endotoxins, which are now described as systemic inflammatory response. Although the clinical trials with anti-TNF in sepsis have not been successful thus far, undoubtedly as a result of the complexity of this clinical setting, these studies ultimately led to the identification of TNF as a key inflammatory mediator and to the development of anti-TNF molecules (soluble receptors and antibodies) for important diseases including rheumatoid arthritis and Crohn's disease. On the other side, the mechanisms by which TNF and related molecules induce cell death have been studied in depth, and their knowledge might, in the future, suggest means of improve the therapeutic index of TNF in cancer.

Interleukin (IL)-1 beta-deficient (IL-1 beta -/-) mice exhibited decreased zymosan-induced lethality and reduced production of IL-6 compared with wild-type controls (IL-1 beta +/+). In addition, IL-1 beta -/- mice had a diminished cellular infiltrate (33%) in the peritoneal cavity after zymosan. However, anorexia and hypoglycemia were not affected by the lack of IL-1 beta. The induction of corticosterone was only slightly reduced (14%) in IL-1 beta -/- mice. Peritoneal lavage fluid levels for IL-1 alpha, but not for tumor necrosis factor (TNF)-alpha, were also decreased. To evaluate the role of residual IL-1 alpha production in IL-1 beta -/- mice, we used IL-1-receptor antagonist (IL-1ra). In IL-1 beta +/+ mice, IL-1ra inhibited production of IL-6 after zymosan, without affecting TNF-alpha synthesis. There was no further inhibitory effect of IL-1ra on IL-6 production in IL-1 beta -/- mice, suggesting no role for IL-1 alpha in zymosan-induced IL-6. Our results demonstrate that IL-1 beta plays a significant, although not exclusive, role in the physiological and cytokine responses to zymosan-mediated inflammation.

Systemic and localized inflammation elicit a number of host responses which include fever, cachexia, hypoglycemia, and major changes in the concentration of liver plasma proteins. Interleukin 6 (IL-6) is considered an important mediator of the inflammatory response, together with IL-1 and tumor necrosis factor alpha (TNF-alpha). The purpose of this study was to unequivocally determine the role of IL-6 in these phenomena making use of IL-6-deficient mice that we have recently generated by gene targeting. We report here that in the absence of IL-6, mice are unable to mount a normal inflammatory response to localized tissue damage generated by turpentine injection. The induction of acute phase proteins is dramatically reduced, mice do not lose body weight and only suffer from mild anorexia and hypoglycemia. In contrast, when systemic inflammation is elicited through the injection of bacterial lipopolysaccharide (LPS), these parameters are altered to the same extent both in wild-type and IL-6-deficient mice, demonstrating that under these conditions IL-6 function is dispensable. Moreover, we show that LPS-treated IL-6-deficient mice produce three times more TNF-alpha than wild-type controls, suggesting that increased TNF-alpha production might be one of the compensatory mechanisms through which a normal response to LPS is achieved in the absence of IL-6. We also show that corticosterone is normally induced in IL-6-deficient mice, demonstrating that IL-6 is not required for the activation of the hypothalamic-pituitary-adrenal axis. Our results reinforce the idea that different patterns of cytokines are involved in systemic and localized tissue damage, and identify IL-6 as an essential mediator of the inflammatory response to localized inflammation.

Resident mouse peritoneal macrophages (M phi) produced significant amounts of superoxide anion (O2-) in response to phagocytic stimuli. When M phi were exposed in vitro for 20 hr to fibroblast interferon (IFN-beta), their capacity to release O2- was significantly reduced, such reduction being more evident with increasing IFN-beta concentrations. In contrast, O2- production by M phi exposed for 20 hr to the lymphokine macrophage activating factor (MAF) or treated with either MAF or IFN-beta for 4 hr was not significantly different from that of control cells. This pattern of activity closely followed that of M phi-mediated suppression of lymphocyte proliferation, which was dramatically reduced by 20 hr exposure of M phi to IFN-beta, but unchanged by treatment with MAF. No correlation was however found between superoxide anion generation and enhancement of tumoricidal capacity in IFN-beta-treated M phi. We thus concluded that O2- does not play a relevant role in IFN-beta-induced M phi cytolysis, whereas the reduction of O2- production could be of major importance in the decrease of M phi suppression induced by IFN-beta.

Interleukin 1 (IL-1) is an endogenous mediator produced by monocytes/macrophages, endothelial cells and other cell types. It was originally identified as the main endogenous pyrogen. It was later found that IL-1 was identical to other factors that had been defined leukocytic endogenous mediator, lymphocyte activating factor. It is now clear that IL-1 has two main aspects. On one side it is an immunostimulatory molecule and on the other side is a mediator of shock and inflammation. As an immunostimulating molecule, IL-1 is a potential immuno-modulating drug, while with respect to its proinflammatory action it might be important to identify antagonists or inhibitors that could be useful in the therapy of chronic inflammatory diseases.

Interferon (IFN) and IFN inducers are known to depress hepatic microsomal cytochrome P-450 levels, and the liver toxicity of IFN was reported to be lethal in newborn mice. We have observed that administration to mice of IFN and IFN inducers caused a marked increase in liver xanthine oxidase activity. Because this enzyme is well known to produce reactive oxygen intermediates and cytochrome P-450 was reported to be sensitive to the oxidative damage, we have tested the hypothesis that a free radical mechanism could mediate the depression of cytochrome P-450 levels by IFN. Administration to mice of the IFN inducer polyinosinic-polycytidylic acid (2 mg/kg i.p.) caused a 29 to 52% decrease in liver cytochrome P-450. Concomitant p.o. administration of the free radical scavenger, N-acetylcysteine (as a 2.5% solution in drinking water), or the xanthine oxidase inhibitor, allopurinol (100 mg/kg), protected against the IFN-mediated depression of P-450 kg), protected against the IFN-mediated depression of P-450 levels. The results suggest that an increased endogenous generation of free radicals, possibly due to the induction of xanthine oxidase, is implicated in the IFN-mediated depression of liver drug metabolism. The relevance of these data also extends to cases in which this side effect is observed in pathological situations (e.g., viral diseases and administration of vaccines) associated with an induction of IFN.

The mechanisms of interleukin-12 (IL-12) toxicity were studied in mice using a schedule (murine rIL-12, 400 ng/mouse, intraperitoneally [IP] once daily for 5 days) that markedly reduced body weight and food intake. On day 5, IL-12–treated mice had elevated serum and spleen IFN-γ and tumor necrosis factor (TNF). Serum sTNFR-P75 and corticosterone (CS) were also elevated. IL-12 toxicity was partially prevented by anti–IFN-γ antibodies or dexamethasone (DEX). A pre-dose of IL-12 (200 ng/mouse on day −14) completely prevented the toxicity of subsequent IL-12. The IL-12 predose also inhibited IL-12–induced IFN-γ levels, but did not modify IL-12–induced CS, TNF or sTNFR-P75. A protective effect was observed with a predose of lipopolysaccharide (LPS) or murine recombinant (r)IL-10. The protective effect of the IL-12 predose was reduced by coadministration of anti–IFN-γ, but a predose of murine rIFN-γ was not protective, suggesting that IFN-γ is necessary but not sufficient for the protective effect of IL-12. The IL-12 predose specifically protected against IL-12 toxicity and did not modify LPS toxicity. These data indicate that IL-12 can induce tolerance to its own toxicity, probably through a downregulation of IL-12–induced IFN-γ but independently of endogenous glucocorticoids. IFN-γ, and possibly IL-10, might be important in this tolerance.

The aim of this work was to study the relative role of the two TNF receptors (p55 and p75) in the central actions of TNF, studying the elevation of serum corticosterone (CS) and IL-6 levels after injection of recombinant murine (rm)TNF (intracerebroventricularly (i.c.v.)) in normal or p55-deficient (p55 -/-) mice. rmTNF induced high serum IL-6 levels and doubled serum CS in normal mice, whereas no elevation of serum IL-6 or CS was induced in p55 -/- mice. However, a normal CS response was observed in p55 -/- mice after LPS (2.5 microg, i.c.v.). p55 -/- mice also responded, although to a lesser extent than p55 +/+, in terms of LPS-induced IL-6 production. We also injected two agonist Abs specific for the two receptors, alpha p55 and alpha p75. While alpha p55 injected i.c.v. induced a marked elevation in CS and IL-6, alpha p75 induced CS (although less than alpha p55) but no IL-6. rmTNF, which binds both receptors, was more potent in inducing IL-6 and CS than injection of rhTNF, which in mice binds only p55. Finally, we investigated the role of p55 and p75 in IL-6 induction by TNF in a murine brain endothelioma. The results resembled closely those obtained in vivo: rmTNF was more potent than rhTNF and only alpha p55, and not alpha p75, induced IL-6 production. These data indicate that p55 plays a major role in TNF activation of the hypothalamus-pituitary-adrenal axis and in the centrally mediated induction of peripheral IL-6 by TNF, but p75, despite having little IL-6 inductive properties by itself, seems to potentiate p55 induction of IL-6.

This study measured, using ELISA or bioassay methodology, fluctuation in concentration of the circulating cytokines tumor necrosis factor (TNF) and interleukin 6 (IL-6), and the acute phase proteins serum amyloid A (apoSAA) and C-reactive protein (CRP), in five septic patients, during a one-week period starting from the day of diagnosis. All had consistently detectable levels of circulating TNF (range of peak values, 0.6-13.6 ng/ml); two also had high IL-6 levels, while the remaining three had detectable levels only at some time points (range of peak values, 105-31j pg/ ml). TNF concentrations fluctuated during the observation period, in some cases with a biphasic temporal pattern. TNF and IL-6 levels were undetectable (below 30 and 100 pg/ml, respectively) in the control population with our assuys12.ApoSAA concentrations in these patients (range of peak values, 65-975 fig/ml) were correlated with TNF and with high CRP concentrations (range of peak values, 7-329 pg/ ml). ApoSAA concentrations ranged from ...

IL-1 induces its own gene expression in human PBMC, in cultured smooth muscle and in endothelial cells. IL-1-induced IL-1 may be part of a self-amplification or an autocrine growth factor in a variety of responses, and thus the endogenous regulation of IL-1 production likely contributes to the outcome of immunologic or inflammatory responses. In the present study, IFN-gamma consistently increased LPS-induced IL-1, but reduced the total amount of IL-1-induced IL-1 from PBMC. This reduction was observed in populations of adherent cells and cells selected with anti-Leu M3 antibody. On a molar basis, IFN-gamma and IFN-alpha 2 were equally effective in reducing IL-1-induced IL-1 synthesis. In PBMC of 24 human subjects, IFN-gamma also reduced PMA-induced IL-1 synthesis (67% decrease, p less than 0.001). The augmentation of LPS-stimulated IL-1 by IFN-gamma was observed only when added at the same time as LPS, but IFN-gamma could be added 6 h after stimulation with IL-1 and still suppress IL-1 production. LPS-induced mRNA for IL-1 beta was modestly enhanced by IFN-gamma whereas mRNA levels for TNF were markedly increased. In contrast, IFN-gamma suppressed mRNA accumulation for IL-beta after stimulation with IL-1 alpha by 60 to 95%. The addition of IFN-gamma 30 min before stimulation of PBMC with IL-1 suppressed IL-1 beta mRNA for up to 30 h. The half-life of IL-1 beta mRNA of approximately 2 h was not influenced by IFN-gamma. Thus, IFN-gamma reduces IL-1-induced IL-1 synthesis by suppressing IL-1-induced transcription, whereas the same concentrations of IFN-gamma augment LPS-induced IL-1 production by increasing transcription.

Mouse peritoneal macrophages (M phi) expressed enhanced tumoricidal activity upon in vitro stimulation either with the lymphokine M phi-activating factor (MAF) or with fibroblast interferon (IFN-beta). In contrast, M phi suppressive activity on lymphoproliferation was not affected by MAF pretreatment, but was drastically reduced or abolished by IFN-beta. Catalase, the enzyme involved in the destruction of hydrogen peroxide (H2O2), did significantly decrease M phi suppressive capacity but had no effect on M phi tumoricidal activity. Analysis of the phagocytosis-dependent H2O2 production by IFN-beta-treated M phi demonstrated a strong impairment of the oxygen metabolite release, which strictly paralleled the decreased M phi suppressive capacity. On the other hand, MAF did not modify H2O2 release by M phi. Studies on M phi antibacterial activity against Salmonella typhimurium, a function thought to depend upon H2O2 production, showed that exposure of M phi to IFN-beta significantly impaired their bactericidal and bacteriostatic capacity, again in close correlation with the decrease in H2O2 production. Thus, IFN-beta appears as modulating both suppressive and antibacterial capacities of M phi through reduction of their oxygen metabolism, whereas regulation of M phi anti-tumour activity is possibly controlled by different mechanisms.

IL-1 plays an important role in the pathophysiologic responses to infection and inflammation, in part by mediating its own production and that of other proinflammatory cytokines. However, the relative contribution of IL-1 alpha and IL-1 beta to the inflammatory response has not been well clarified. Using IL-1 beta-deficient (IL-1 beta -/-) mice, we investigated the specific role of IL-1 beta in the in vivo and in vitro response to LPS. No differences between IL-1 beta +/+ and IL-1 beta -/- mice were observed in circulating levels for IL-1 alpha, IL-6, or TNF-alpha after the systemic administration of either a low (5 micrograms/kg) or high (5 mg/kg) dose of LPS. IL-1 beta -/- mice also had a normal response to LPS in terms of activation of the hypothalamus-pituitary-adrenal axis, hypoglycemia, serum amyloid A production, and anorexia. IL-1 beta -/- mice were normally sensitive to the lethal effect of LPS and were protected against LPS toxicity when pretreated with low-dose LPS. However, in vitro, peritoneal macrophages from IL-1 beta -/- mice stimulated with LPS produced significantly less IL-1 alpha than macrophages from IL-1 beta +/+ mice (p < 0.05). No differences in IL-6 or TNF-alpha synthesis were observed between macrophages from IL-1 beta +/+ and IL-1 beta -/- mice. In summary, our results suggest that either IL-1 beta is not essential for the in vivo systemic response to LPS or that its role can be fulfilled by other cytokines with overlapping activities.

Neuroactive steroids such as dehydroepiandrosterone sulfate and pregnenolone inhibit lipopolysaccharide (LPS)-induced tumor necrosis factor (TNF) production. Corticosteroids not only inhibit TNF production but their levels are increased in vivo after endotoxin injection, thus representing a feedback system that limits TNF production. We wondered whether the same could be true for neuroactive steroids. Thus, the possibility that neuroactive steroids might be increased concomitantly to TNF induction in vivo in mice treated with LPS was investigated. Increased plasma and hippocampal levels of allopregnanolone (but not of dehydroepiandrosterone or pregnenolone) were found 90 min after LPS injection. Allopregnanolone and progesterone (IC50 10- 7 and 10- 9 M, respectively) also inhibited TNF production by mouse peritoneal macrophages in vitro at concentrations in the range of those detected in vivo. These findings suggest that neuroactive steroids may act as endogenous inhibitors of cerebral and systemic TNF production.

Interleukin-2 (15 micrograms/mouse, i.p. twice daily for 4 days and once on the 5th day) significantly lowered cytochrome P-450 and heme content and increased heme oxygenase mRNA accumulation; the activities of 7-ethoxycoumarin O-deethylase, ethoxy- and pentoxyphenoxazone O-dealkylases were decreased. The activity of the type O form of hepatic xanthine oxidase increased, but there was no increase in lipid peroxide, expressed in terms of microsomal malondialdehyde. In vivo inactivation of xanthine oxidase activity by feeding mice with tungstate did not substantially change the degree of interleukin-2-induced cytochrome P-450 depression, suggesting that the two processes are not causally linked. Induction of tolerance to endotoxin by a 4-day pretreatment with lipopolysaccharide resulted in 50% protection against this depression despite inhibition of the interleukin-2 induced formation of tumor necrosis factor. This suggests that the release of tumor necrosis factor per se does not fully account for the depression of cytochrome P-450. Dexamethasone, already used in patients to reduce the toxicity of interleukin-2 therapy, provided full protection against the cytochrome P-450 depression.

Three secretory products of the macrophage, interleukin 1 (IL-1), tumor necrosis factor/cachectin (TNF) and hepatocyte stimulating factor/interleukin 6 (IL-6) modulate liver protein synthesis during the acute phase response. Induction of serum amyloid A (SAA) synthesis is one of the most notable acute phase changes in liver proteins, with maximal SAA concentrations varying over a thousand-fold range in proportion to the amount of tissue injury and cell necrosis. Exogenous IL-1 and TNF induce SAA synthesis in vivo and in vitro, while exogenous IL-6 is a far less potent stimulus of in vivo SAA gene expression. Dexamethasone (DEX), a potent inhibitor of macrophage IL-1, TNF and IL-6 synthesis, was utilized to analyze the endogenous mediators of SAA synthesis in mice injected with lipopolysaccharide (LPS). DEX, although itself exhibiting the capacity to stimulate SAA synthesis to a limited extent, significantly reduced LPS induced SAA production. However, DEX did not reduce, but rather potentiated, IL-1 and TNF stimulated SAA production, indicating that these monokines do not require macrophage products to mediate their in vivo SAA inducer activity. SAA synthesis was observed in adrenalectomized mice, following administration of LPS, IL-1 and TNF, indicating that SAA induction by monokines is not secondary to corticosteroid release.

Endotoxin-resistant C3H/HeJ mice were used to test the hypothesis that a macrophage product, possibly interleukin-1, might mediate the depression of liver cytochrome P-450-dependent drug metabolism in endotoxin-treated mice. Depression of liver drug metabolism by endotoxin was observed in normal mice (C3H/HeN) but not in C3H/HeJ mice. Serum transfer experiments demonstrated that a serum factor was responsible for the depression of liver drug metabolism. Experiments of passive transfer of peritoneal macrophages showed that this endotoxin-induced factor might be a macrophage product. In vitro experiments showed that endotoxin-stimulated monocytes produced a factor that depressed cytochrome P-450-dependent metabolism in cultured hepatocytes. Homogeneous human monocyte and recombinant interleukin-1 also depressed liver drug metabolism both in vivo and in vitro, suggesting that this macrophage product might be involved in the regulation of liver function by the immune system.

Background —Inflammation is an important component of ischemic heart disease. PTX3 is a long pentraxin whose expression is induced by cytokines in endothelial cells, mononuclear phagocytes, and myocardium. The possibility that PTX3 is altered in patients with acute myocardial infarction (AMI) has not yet been tested. Methods and Results —Blood samples were collected from 37 patients admitted to the coronary care unit (CCU) with symptoms of AMI. PTX3 plasma concentrations, as measured by ELISA, higher than the mean+2 SD of age-matched controls (2.01 ng/mL) were found in 27 patients within the first 24 hours of CCU admission. PTX3 peaked at 7.5 hours after CCU admission, and mean peak concentration was 6.94±11.26 ng/mL. Plasma concentrations of PTX3 returned to normal in all but 3 patients at hospital discharge and were unrelated to AMI site or extent, Killip class at entry, hours from symptom onset, and thrombolysis. C-reactive protein peaked in plasma at 24 hours after CCU admission, much later than PTX3 ( P 64 years old and women had significantly higher PTX3 concentrations at 24 hours ( P Conclusions —PTX3 is present in the intact myocardium, increases in the blood of patients with AMI, and disappears from damaged myocytes. We suggest that PTX3 is an early indicator of myocyte irreversible injury in ischemic cardiomyopathy.

Inflammation has been implicated in the pathogenesis of many neurodegenerative diseases. The chemokine IL-8 is thought to have a pathophysiological role in neurodegenerative diseases. IL-8 has recently been shown to induce death of primary cultured motor neurons in vitro. We determined IL-8 levels in the cerebrospinal fluid (CSF) from 38 patients with sporadic amyotrophic lateral sclerosis (ALS) compared to patients with other non-inflammatory neurological diseases (cerebrovascular disease, degenerative dementia, Parkinson's disease, compressive radiculo-myelopathy). Multiple sclerosis (MS) patients were used as positive controls. The levels of IL-8 in the CSF of ALS patients were significantly higher than those of patients with other, non-inflammatory neurological conditions and similar to those of MS patients. The only variable influencing IL-8 in ALS patients was sex, with higher levels in men than in women. The presence of the inflammatory cytokine IL-8 in the CSF of patients with ALS at the time of diagnosis strengthens the hypothesis of a role for this chemokine in neurodegenerative disorders.

Centrally administered interleukin (IL)-1 [both alpha and beta forms, 200 ng/rat intracerebroventricularly (icv)] results in a larger increase in serum IL-6 than after systemic injection, indicating the brain's role in the acute phase response. This action was prevented by the IL-1-receptor antagonist IL-1Ra (20 micrograms/rat icv). Neither antiserum against corticotropin-releasing factor (CRF) nor the alpha-helical-CRF antagonist (25 micrograms/rat icv) affected IL-6 induction by central IL-1 beta, which, however, was significantly prevented by the synthetic glucocorticoid dexamethasone [3 mg/kg intraperitoneally (ip)]. Naloxone, the opiate antagonist, but not naloxone methiodide, its quaternary salt that does not penetrate the blood-brain barrier (both administered at 10 mg/kg ip), antagonized this action of IL-1 beta. After intracerebroventricular IL-1 beta, IL-6 levels in brain areas (striatum, hippocampus, hypothalamus) were extremely low, suggesting that the brain does not significantly contribute to IL-6 synthesis in this condition. The results show that induction of high serum IL-6 levels by central IL-1 beta is mediated by brain IL-1 receptors and is sensitive to inhibition by corticosteroids. The inhibitory effect of naloxone suggests that central opiates are required for this action of IL-1 beta.

During the acute-phase response to bacterial endotoxins [lipopolysaccharide (LPS)] in mice, the hepatic activity of haem oxygenase (HO) is increased. We investigated the effects of the potential humoral mediators of inflammation, interleukin-1 (IL-1) and tumour necrosis factor (TNF), on hepatic HO activity. In mice, IL-1 or TNF (5 micrograms) caused an elevation of HO activity comparable with that after LPS exposure (20 micrograms). The induction of HO by both cytokines was more pronounced in adrenalectomized mice. In the intact mice induction of HO activity by cytokines was observed earlier than depression of 7-ethoxycoumarin O-de-ethylase, a cytochrome P-450-dependent enzyme activity. Pretreatment with dexamethasone of the intact mice (3 mg/kg) or of the adrenalectomized mice (0.4 mg/kg) prevented the induction of HO activity caused by LPS and IL-1 respectively. These results suggest that: (1) HO activity is increased during an IL-1- or TNF-mediated acute-phase response, so haem metabolism might be a potential target of inflammation, and (2) HO induction by IL-1 and TNF does not require glucocorticoids, which in fact act as antagonists of this cytokine-induced effect.

IL-1 possesses several biologic properties, some of which are associated with chronic inflammatory diseases. We have recently shown that IL-1 induces its own gene expression and, in the present studies, we have examined the effect of IFN-gamma on IL-1-induced IL-1 production. Whereas IFN-gamma increases the total amount of IL-1 (extracellular and cell-associated) produced after endotoxin stimulation of human PBMC, in the same cultures, IL-1-induced IL-1 production was markedly (greater than 70%) reduced in the presence of IFN-gamma. We observed this inhibition in the PBMC from over 40 human donors by employing non-cross-reacting RIA for either IL-1 beta or IL-1 alpha. IFN-gamma inhibited IL-1 beta-induced IL-1 alpha as well as IL-1 alpha-induced IL-1 beta production; furthermore, this inhibitory effect of IFN-gamma was unaffected by indomethacin. The ability of 100 U/ml of IFN-gamma to inhibit IL-1-induced IL-1 production was comparable to that accomplished by 10(-7) M dexamethasone. In contrast to its effect on IL-1 production from PBMC, IFN-gamma had no effect on the proliferative responses of T cells to IL-1. We conclude that IFN-gamma down-regulates synthesis of total IL-1-induced IL-1 production but up-regulates endotoxin-induced IL-1 production. These studies may explain the ameliorating effects of IFN-gamma in experimental models of IL-1-induced bone and cartilage degradation, in peritoneal fibrosis, and in patients with diseases associated with increased IL-1 production.

Macrophages were isolated from poorly immunogenic metastatic sarcomas (mFS6 and MN/MCA1) of C57BL/6 origin. Tumor-associated macrophages (TAM) showed little release of superoxide when exposed to phorbol myristate acetate. When exposed to a phagocytic stimulus (zymosan), TAM released appreciable amounts of superoxide. TAM had a lower number of specific binding sites for phorbol esters than resident or caseinate-elicited peritoneal macrophages, but had normal NADPH-cytochrome C reductase. The tumor environment, possibly through previously demonstrated products of neoplastic cells, may influence the functional status of in situ macrophages and, thus, impair host anti-tumor and anti-microbial defense mechanisms.

A polypeptide homologous to IL-1, with antagonistic activity (IL-1ra), has recently been described. Given the pleiotropic activity of interleukin (IL-1) it is important to establish the spectrum of inhibitory activity of IL-1ra on in vivo action of IL-1. We tested the effect of IL-1ra on IL-1 induced lethality in adrenalectomized mice, hypoglycemia, and induction of serum corticosterone and interleukin 6. Administration of IL-1ra (200 micrograms/mouse) protected adrenalectomized mice against the lethal effect of 1 microgram of IL-1. IL-1ra at 20 micrograms/mouse completely blocked induction of IL-6 and markedly inhibited hypoglycemia and increase in serum corticosterone induced by 0.1 micrograms of IL-1. These data indicate that IL-1ra inhibits the action of IL-1 on different target tissues involved in the various actions of IL-1 in vivo.

Concentrations of interleukin 6 (IL-6) in cerebrospinal fluid (CSF) and serum of infants and children with bacterial meningitis were determined and correlations were sought with other indices of inflammation and with outcome. Forty-two patients ages 1 month to 15 years (mean, 2.5 years) were studied. IL-6 activity was detectable (greater than 50 units/ml) in 30 of 36 CSF samples collected at admission from patients with meningitis and in 1 of 23 controls with fever and normal CSF findings. Mean values were 36,000 units/ml (range, 151-156,000). IL-6 activity in CSF persisted during the first 5 days of illness. IL-6 concentrations at admission were not associated with clinical findings, CSF leukocyte, protein and glucose concentrations, serum C-reactive protein concentration and neurologic complications or sequelae. IL-6 was also detected in the serum of 3 of 14 patients with meningitis and in 0 of 7 controls with no infectious disease. The presence of IL-6 was not associated with bacteremia or with duration of fever before admission. The presence of IL-6 in the CSF of pediatric patients with bacterial meningitis is in accordance with available data on other cytokines and suggests their role as mediators of meningeal inflammation.

Urocortin (UCN) is a neuropeptide homologous with corticotropin-releasing factor (CRF), which has anti-inflammatory activities not all mediated by corticosteroids. In mice, UCN (1 μg/mouse sc) significantly reduced lipopolysaccharide (LPS)-induced serum tumor necrosis factor (TNF) and interleukin (IL)-1β levels in vivo but did not affect serum IL-6. These effects were paralleled by a rise in corticosterone (CS) levels. Blockade of the CS increase by cyanoketone did not prevent TNF inhibition by UCN, suggesting the neuropeptide has anti-inflammatory mechanisms independent of the hypothalamus-pituitary-adrenal axis. In fact UCN had a direct inhibitory effect on LPS-induced TNF in rat Kupffer cells at concentrations between 10−10and 10−16M, and this effect was related to increased cAMP levels. However, the in vivo inhibition of LPS-induced IL-1β by UCN was reversed by cyanoketone, indicating that the increase of endogenous glucocorticoids might be more important in IL-1β inhibition than in TNF inhibition by UCN.

Nitric oxide (NO) plays a key role in the pathophysiology of inflammation and sepsis. The regulation of the peripheral inducible NO synthase (iNOS-responsible for the massive NO synthesis in inflammation) has been extensively studied in sepsis, but little is known about the actual NO production and its dependence on the location of the primary stimulus (endotoxin, LPS). We measured the activation of the NO pathway after a central (intracerebroventricular) or systemic (intravenous) low dose of LPS (2.5 micrograms/mouse) in three ways: the accumulation of its stable end products (nitrites/nitrates) in the circulation, the induction of iNOS mRNA and the decrease in sodium nitroprusside-dependent ADP ribosylation of proteins in the liver and brain. Plasma nitrites/nitrates increased after LPS by either route. iNOS mRNA was induced in the liver after intravenous and, to a lower extent, in the brain after intracerebroventricular LPS. Ex vivo ADP ribosylation was decreased in both organs after both administration routes, although to different degrees (higher in the liver after intravenous and in the brain after intracerebroventricular administration), suggesting that NO had been produced in the periphery and in the brain after both routes of LPS administration, despite the fact that no LPS is expected to reach the brain after peripheral low-dose injection. Our data thus demonstrate a cross-talk between periphery and brain in the regulation of NO by LPS. Additionally, the possibility of iNOS-independent NO synthesis stimulated by LPS is implied by the discrepancy between the amount of local NO production suggested by ADP ribosylation and the iNOS mRNA levels.

To verify the potential in vivo inhibitory effect on liver function of tumor necrosis factor (TNF), also known as cachectin, antipyrine and diazepam were chosen to probe the hepatic mixed-function oxidase system. A single dose of TNF (30 micrograms/kg) to rats significantly reduced the plasma clearance of antipyrine and diazepam by about 30% and 25%, respectively; this resulted in concomitant prolongation of the elimination half-life (t1/2) of the two drugs, although of borderline significance for the benzodiazepine. This was probably due to a decrease in hepatic cytochrome P-450 activities that are responsible for antipyrine and diazepam metabolism in TNF-treated rats. This could be of clinical relevance if a similar effect occurs in humans after therapeutically effective doses of this biological response modifier.

Nonsteroidal antiinflammatory drugs (NSAIDs) are widely used in the treatment of chronic inflammatory states. In addition, they show promise for the prevention and therapy of colon cancers and of Alzheimer's disease, although their gastrointestinal toxicity is of concern for these indications. Nitric oxide-releasing NSAIDs are reported to be safer than their parent compounds. We report here that flurbiprofen nitroxybutyl ester inhibits nuclear factor-kappaB (NF-kappaB) activity and cell growth in L929 cells at a concentration of 100 microM, whereas flurbiprofen is inactive. Inhibition of cell growth is not due to the induction of apoptosis, but to a retardation of all phases of the cell cycle. NF-kappaB is implicated both in the control of immune and inflammatory response and in the control of cell proliferation and apoptosis. Therefore, its inhibition at low concentrations by an NSAID with low gastrointestinal toxicity could be important for all the above-mentioned therapeutic indications.

Ciliary neurotrophic factor (CNTF) inhibits the production of tumor necrosis factor (TNF) in lipopolysaccharide (LPS)-treated mice and protects against LPS lethality when coadministered with its soluble receptor (sCNTFR alpha). Both of these activities are abolished in adrenalectomized (ADX) mice. LPS-induced pulmonary polymorphonuclear neutrophil (PMN) infiltration and nitric oxide (NO) production were also inhibited by CNTF + sCNTFR alpha but not by CNTF alone. sCNTFR alpha did not alter the clearance or tissue distribution of CNTF. Furthermore, CNTF variants coadministered with sCNTFR alpha protected against LPS toxicity in a manner related to their affinity for the beta components of CNTFR. Thus, inhibition of TNF production and protection against LPS lethality by CNTF/sCNTFR alpha require an intact hypothalamus-pituitary-adrenal axis (HPAA) and may be mediated by endogenous glucocorticoids. This protective effect is, at least in part, due to the inhibition of PMN infiltration and NO production, and appears to be mediated by cells displaying only beta-receptor subtypes.

The tissue-protective action of erythropoietin (EPO) in animal models is often associated with reduced inflammation. However, there are many contrasting reports of the effect of EPO on the production of inflammatory cytokines induced by lipopolysaccharide (LPS) in vitro, with different papers reporting an inhibition, an upregulation, or a lack of effect. Negative results are likely underestimated by a publication bias. As EPO has anti-inflammatory actions in models associated with tissue injury, we hypothesized that EPO could specifically inhibit the induction of inflammatory cytokines by danger signals associated with cell death, and investigated its effect on the induction of IL-6 or TNF by high-mobility group-box 1 protein (HMGB1) or by necrotic cells. We did not observe any significant effect of EPO in these models; neither EPO affected the response induced by TLR agonists different from LPS, or by extracellular ATP-mediated activation of the inflammasome. We conclude that the inhibition of inflammation by EPO is likely to be an indirect effect, secondary to its tissue-protective activity, or that it requires a prior priming induced by the injury.

Lipopolysaccharide (LPS) exerts its biological activity through the lipid A moiety. We tested the efficiency in inhibiting TNF production in sera and in tissues of mice and in the derma of rabbits challenged with LPS, of a synthetic anti-LPS peptide (SAEP-2) previously shown to specifically detoxify the lipid A region of LPS on the basis of structural similarities with the antibiotic polymyxin B (PMXB). In mice, SAEP-2 (100 μg/mouse, i.v.) injected with various schedules ('-30 to +10 min from LPS at 50 ng/mouse, i.v.) significantly inhibited serum TNF as well as liver, spleen and lung-associated TNF. In rabbits, SAEP-2 significantly inhibited TNF produced in dermal tissue and the resulting local hemorrhagic necrosis. The amount of tissue-associated TNF released by LPS challenge in the mouse was up to 6 times that present in the serum and inhibition by SAEP-2 or PMXB accounted for 75% of the total. Direct measurement of the binding kinetics by surface plasmon resonance and molecular filtration at equilibrium revealed that SAEP-2 and PMXB bind to LPS only in the presence of a significant amount of water but that they are unable to bind LPS in undiluted serum. Altogether these findings strongly suggest that inhibition of LPS-induced TNF by SAEP-2 and PMXB may occur in tissues.

The effect of the antioxidant N-acetyl-L-cysteine was studied in a model of polymicrobial sepsis induced in CD-1 mice by cecal ligation and puncture. N-Acetyl-L-cysteine significantly improved survival during the 6 days following sepsis induction and caused lower liver toxicity. This effect was not related to free radicals generated by xanthine oxidase which was significantly induced in liver after cecal ligation and puncture. A specific inhibitor of xanthine oxidase, allopurinol, significantly reduced this enzyme and reduced the early survival rate. The effect of N-acetyl-L-cysteine was not related either to a reduction in tumor necrosis factor production or to a modulation of nitrites or to liver glutathione content. These results show that the induction of xanthine oxidase is not deleterious in this model of sepsis and suggest that N-acetyl-L-cysteine works as a direct antioxidant and scavenger of free radicals generated from other sources.