Enhancement of lipopolysaccharide-induced tumor necrosis factor production in mice by carrageenan pretreatment

Penta-fluorophenol: a Smiles rearrangement-inspired cysteine-selective fluorescent probe for imaging of human glioblastoma

Two of the most critical factors for the survival of glioblastoma (GBM) patients are precision diagnosis and the tracking of treatment progress. At the moment, various sophisticated and specific diagnostic procedures are being used, but there are relatively few simple diagnosis methods. This work introduces a sensing probe based on a turn-on type fluorescence response that can measure the cysteine (Cys) level, which is recognized as a new biomarker of GBM, in human-derived cells and within on-site human clinical biopsy samples. The Cys-initiated chemical reactions of the probe cause a significant fluorescence response with high selectivity, high sensitivity, a fast response time, and a two-photon excitable excitation pathway, which allows the imaging of GBM in both mouse models and human tissue samples. The probe can distinguish the GBM cells and disease sites in clinical samples from individual patients. Besides, the probe has no short or long-term toxicity and immune response. The present findings hold promise for application of the probe to a relatively simple and straightforward following of GBM at clinical sites.

Physicochemical and biological characterizations of complex formation between lipopolysaccharide and lysozyme

Endotoxin (lipopolysaccharide, LPS) from Gram-negative bacteria induces a variety of biological effects in mammals. We have earlier demonstrated that lysozyme (LZM) will bind to both smooth and rough forms of LPS and lipid A with high affinity, and inhibits several of the immunomodulatory activities of LPS. The production of LZM/LPS complexes was suggested to be significantly influenced by both reaction temperature and ionic strength. In this manuscript, we describe experiments designed to examine the formation of LZM/LPS complexes prepared under various conditions as assessed by fluorescence measurements of dansylated LZM and also by separation of complexes via nitration methodologies. The results of these studies provide additional experimental evidence that complex formation requires both ionic and hydrophobic interactions. The most stable complexes were formed at conditions of low ionic strength and higher temperature. Under these conditions, hydrophobic interactions were predominant in complex formation. At lower temperatures, the extent of complex formation was less, and ionic interactions were predominant. TNF production by RAW264.7 cells in vitro was decreased by LZM/LPS complexes prepared in both high and low ionic strength, but was most significantly decreased at conditions of low ionic strength and higher temperatures. These facts suggest that both ionic and hydrophobic interactions of LZM with LPS are important for neutralizing the biological activity of LPS.

Degraded λ-carrageenan activates NF-κB and AP-1 pathways in macrophages and enhances LPS-induced TNF-α secretion through AP-1

BACKGROUND

Carrageenan (CGN), a high molecular weight sulfated polysaccharide, is a traditional ingredient used in food industry. Its degraded forms have been identified as potential carcinogens, although the mechanism remains unclear.

METHODS

The effects of degraded λ-carrageenan (λ-dCGN) on murine RAW264.7 cells and human THP-1-derived macrophage cells were investigated by studying its actions on tumor necrosis factor alpha (TNF-α) secretion, Toll-like receptor 4 (TLR4) expression, and activation of nuclear factor-κb (NF-κB) and activation protein-1 (AP-1) pathways.

RESULTS

We found that λ-dCGN was much stronger than native λ-CGN in the activation of macrophages to secrete TNF-α. Treatment of RAW264.7 cells with λ-dCGN resulted in the upregulation of TLR4, CD14 and MD-2 expressions, but it did not increase the binding of lipopolysacchride (LPS) with macrophages. Meanwhile, λ-dCGN treatment activated NF-κB via B-cell lymphoma/leukemia 10 (Bcl10) and nuclear factor of kappa light polypeptide gene enhancer in B-cells inhibitor, alpha (IκBα) phosphorylation. In addition, λ-dCGN induced extracellular signal-regulated kinases/1/2/mitogen-activated protein kinases (ERK1/2/MAPK) and AP-1 activation. Interestingly, pretreatment of RAW264.7 cells with λ-dCGN markedly enhanced LPS-stimulated TNF-α secretion. This pretreatment resulted in the enhanced phosphorylation of ERK1/2 and c-Jun N-terminal kinase (JNK) and intensified activation of AP-1.

CONCLUSIONS

λ-dCGN induced an inflammatory reaction via both NF-κB and AP-1, and enhanced the inflammatory effect of LPS through AP-1 activation.

GENERAL SIGNIFICANCE

The study demonstrated the role of λ-dCGN to induce the inflammatory reaction and to aggravate the effect of LPS on macrophages, suggesting that λ-dCGN produced during food processing and gastric digestion may be a safety concern.

Comparative analysis of hepatic CD14 expression between two different endotoxin shock model mice: relation between hepatic injury and CD14 expression

CD14 is a glycoprotein that recognizes gram-negative bacterial lipopolysaccharide (LPS) and exists in both membrane-bound and soluble forms. Infectious and/or inflammatory diseases induce CD14 expression, which may be involved in the pathology of endotoxin shock. We previously found that the expression of CD14 protein differs among the endotoxin shock models used, although the reasons for these differences are unclear. We hypothesized that the differences in CD14 expression might be due to liver injury, because the hepatic tissue produces CD14 protein. We investigated CD14 expression in the plasma and liver in the carrageenan (CAR)-primed and D-galN-primed mouse models of endotoxin shock. Our results showed that severe liver injury was not induced in CAR-primed endotoxin shock model mice. In this CAR-primed model, the higher mRNA and protein expression of CD14 was observed in the liver, especially in the interlobular bile duct in contrast to D-galN-primed-endotoxin shock model mice. Our findings indicated that the molecular mechanism(s) underlying septic shock in CAR-primed and D-galN-primed endotoxin shock models are quite different. Because CD14 expression is correlated with clinical observations, the CAR-primed endotoxin shock model might be useful for studying the functions of CD14 during septic shock in vivo.

Differences in polymorphonucleocyte function and local inflammatory response between horses and ponies

REASONS FOR PERFORMING STUDY

Wound healing proceeds faster in ponies than in horses and complications during healing, such as wound infection, occur less frequently in ponies. Earlier studies suggested that this difference might be related to differences in the initial post traumatic inflammatory response.

HYPOTHESIS

That polymorphonuclear leucocyte (PMN) function and profiles of humoral factors in local inflammatory processes are different in horses and ponies.

METHODS

PMNs were isolated from venous blood of horses and ponies. Chemotaxis and reactive oxygen species (ROS) production was determined. Tissue cages were implanted in limbs and necks of horses and ponies and injected with carrageenan and, 3 weeks later, with LPS. In sequential samples of inflammatory exudate, the numbers of macrophages and PMNs and the production of PGE2, TNFalpha, IL-1, IL-6 and chemoattractants were determined.

RESULTS

In vitro ROS production of PMNs was significantly higher in ponies than in horses, whereas in vitro PMN chemotaxis was significantly lower in ponies. In the tissue cages for both stimuli, the production of IL-1 and chemoattractants was significantly higher in ponies than in horses and remained so towards the end of the observation period in ponies.

CONCLUSIONS

This study demonstrated a higher production of various inflammatory mediators by pony leucocytes. Despite the lower in vitro chemotaxis of pony PMNs, this higher in vivo production resulted in a stronger initial inflammatory response in ponies, as has been reported in studies on wound healing, through the attraction of leucocytes and triggering of the production of other cytokines. A stronger initial inflammation may promote healing by more rapid elemination of contaminants and earlier transition to repair.

POTENTIAL RELEVANCE

Modulation of the initial inflammatory response might therefore be a valid option for therapeutic intervention in cases of problematic wound healing. Further, the intraspecies differences in leucocyte function may have an impact on many fields in equine medicine.

Escherichia coli lipopolysaccharide administration alters antioxidant profile during hypercholesterolemia

Pathogens, especially Gram-negative bacteria or bacterial endotoxin, along with other classical factors, may be involved in inflammatory response within the aortic endothelium during the progression of cardiovascular disease. Studies have shown that bacterial endotoxin activates various inflammatory processes in the body. Our study aims to establish a correlation between endotoxemia and vascular expression of antioxidant enzymes. Swiss albino mice (4 weeks old) were fed a high fat diet for 24 weeks and then were administered Escherichia coli endotoxin intraperitonealy, for 4 weeks. Tissue antioxidant enzymes, serum levels of IL-6 and TNF alpha were measured from the mice. We report that i.p. administration of endotoxin to hyperlipidemic mice resulted in elevation of superoxide dismutase and catalase enzymes, which was paralleled by a systemic reduction of serum cholesterol and LDL expression. Myeloperoxidase levels were also found to be elevated in aortic tissue, while an increase was also observed in the serum cytokine levels.

Ketamine suppresses intestinal TLR4 expression and NF-kappaB activity in lipopolysaccharide-treated rats

AIM

To investigate whether ketamine suppresses lipopolysaccharide (LPS)-induced increase in Toll-like receptor 4 (TLR4) expression and nuclear factor-kappa B (NF-kappaB) activity in the intestines of rats.

METHODS

Six groups of rats received one of the following: normal saline control, LPS (5 mg/kg) plus saline, LPS (5 mg/kg) plus ketamine (0.5 mg/kg), LPS (5 mg/kg) plus ketamine (2.5 mg/kg), LPS (5 mg/kg) plus ketamine (10 mg/kg), or ketamine (10 mg/kg) alone. Intestinal TLR4 mRNA expression was analyzed by reverse transcription polymerase chain reaction (RT-PCR), and NF-kappaB activity was tested by electrophoretic mobility shift assay (EMSA) 1, 3, or 5 hours after the LPS injection.

RESULTS

Lipopolysaccharide increased TLR4 expression and NF-kappaB activity in the intestines of rats. Ketamine at the dosage of 0.5, 2.5, and 10 mg/kg suppressed the LPS-induced increase in TLR4 expression and NF-kappaB activity. Ketamine alone had no effect.

CONCLUSION

The study demonstrated that ketamine inhibits NF-kappaB activation in the intestines of LPS-treated rats, possibly by suppressing TLR4 expression.

Increment of Plasma Soluble CD14 Level in Carrageenan-Primed Endotoxin Shock Model Mice

CD14 is membrane-associating or free soluble glycoprotein which recognizes lipopolysaccharide (LPS) and is assumed to be involved in the onset of endotoxin shock. There are some reports suggesting the relationship between increased expression of CD14 in infectious or inflammatory diseases. However, little has been reported concerning the soluble CD14 (sCD14) level, especially in mice. In this study, we measured the plasma level of sCD14, TNF-alpha and IL-6 in the iota-carrageenan (CAR)-primed endotoxin shock model in addition to the D-galactosamine (D-galN)-primed endotoxin shock model mice. It was confirmed that all mice were dead within 12 h after a higher dose of LPS-treatment in both animal models. The level of TNF-alpha, IL-6 and sCD14 significantly increased in the CAR-primed endotoxin shock model mice. However, the D-galN-primed endotoxin shock model mice showed only a slight increment of TNF-alpha and IL-6 level, and sCD14 was below the detectable level. In the examination using several doses of LPS in CAR-primed model mice, IL-6 and sCD14 were increased dependent on the LPS dose, but TNF-alpha remained at an almost equal level at any dose of LPS in this study condition. In conclusion, the production of TNF-alpha, IL-6 and sCD14 was significantly enhanced in the CAR-primed model mice, compared to the D-galN-primed model mice. Therefore, these data indicate the possibility that the sCD14 level did not increase consistently, even under a fatal condition in endotoxin shock. Also, CAR-primed endotoxin shock would be an important experimental model to examine the elevation mechanisms for sCD14 and IL-6 production.

Bupivacaine???s Action on the Carrageenan-Induced Inflammatory Response in Mice: Cytokine Production by Leukocytes After Ex-Vivo Stimulation

We aimed to study the effect of bupivacaine on the systemic response elicited by intraplantar injection of carrageenan. To that purpose, we studied the effects of carrageenan, bupivacaine, or both on the production of tumor necrosis factor (TNF)-alpha, interleukin (IL)-1beta, and IL-10 by whole blood cultured in the presence of lipopolysaccharide (LPS) and of heat-killed Staphylococcus Aureus Cowan (SAC). Mice received a hindpaw injection of carrageenan with or without encapsulated IM bupivacaine given contralaterally. Whole blood was sampled 15 h later and cultured for 24 h with LPS or SAC. The amounts of TNF-alpha, IL-1beta, and IL-10 in the supernatants were measured. In the presence of LPS or SAC, proinflammatory cytokine (TNF-alpha and IL-1beta) production was increased after carrageenan. Bupivacaine prevented this inflammatory response: 992 +/- 102 versus 2146 +/- 338 versus 919 +/- 116 pg/mL for TNF-alpha (bupivacaine + carrageenan versus carrageenan versus control after LPS stimulation). This effect of bupivacaine was less after SAC stimulation. Moreover, IL-10 was not involved in the inhibition of proinflammatory cytokine production observed after treatment by bupivacaine alone. These experiments show that carrageenan-induced hindpaw inflammation modifies the blood cell reactivity to LPS and SAC and that bupivacaine regulates the systemic response elicited by carrageenan. Furthermore, IL-10 does not seem to be a factor of the antiinflammatory response induced by bupivacaine. The precise mechanism underlying this effect of bupivacaine remains to be clarified.

Augmented expression of tumour necrosis factor-alpha induced by lipopolysaccharide in spleen of human monocyte chemoattractant protein-1 transgenic mouse enhances the lipopolysaccharide sensitivity of the marginal zone macrophages

Monocyte chemoattractant protein-1 (MCP-1) is a protective cytokine in murine endotoxaemia induced by lipopolysaccharide (LPS). In this study, LPS-induced pathophysiology in the human (h) MCP-1 transgenic mouse (Tgm) line was investigated. The hMCP-1 Tgm showed a marked increase in the mortality and weight loss following LPS administration. In the Tgm spleens, disappearance of marginal zone macrophages (MZMphi) and dendritic cells (DC) was induced by a smaller amount of LPS than that required for the disappearance in non-transgenic littermates. A significant number of apoptotic cells were seen in these areas. Furthermore, expressions of tumour necrosis factor-alpha (TNF-alpha), interleukin-1alpha (IL-1alpha), and IL-6 mRNA were enhanced and sustained in the LPS-treated Tgm. Neutralization of TNF-alpha considerably depressed the LPS-sensitivity of Tgm. These findings demonstrate that the continuous and systemic presence of MCP-1 is no more protective toward endotoxaemia and suggest that the high sensitivity of the MZMphi and DC to LPS is attributed to the enhanced TNF-alpha production in the hMCP-1 Tgm.

Role of interleukin-10 on hyporesponsiveness of endotoxin during surgery

OBJECTIVE

To examine whether surgical stress causes blood cells to lose their responsiveness to endotoxin during surgery.

DESIGN

Prospective case series.

SETTING

A university hospital.

PATIENTS

Sixteen volunteers classified as American Society of Anesthesiologists physical status I-II who were scheduled for elective distal partial gastrectomy.

INTERVENTIONS

We studied nine patients who underwent elective distal partial gastrectomy. Blood samples for tumor necrosis factor (TNF) and interleukin (IL)-10 assay were obtained before anesthesia, preincision, 2 hrs and 4 hrs postincision, postextubation, and 24 hrs postincision. The rest of each blood sample was diluted with 5 volumes of endotoxin-free saline, incubated for 4 hrs in the presence of lipopolysaccharide (LPS), centrifuged to remove cells, and assayed for TNF. In another seven patients, antihuman IL-10 antibody was added into the diluted whole blood sample before LPS stimulation.

MEASUREMENTS AND MAIN RESULTS

TNF activity was not detected in the blood of any patient throughout the study. In contrast, plasma cortisol and IL-10 levels increased rapidly during surgery (p < .01, p < .05, respectively). LPS-induced TNF activity in whole blood decreased significantly during surgery (p < .01) and recovered to control levels by 24 hrs postincision. The peak suppression of LPS-induced TNF and the peak value of plasma IL-10 levels occurred postextubation. Treatment with anti-IL-10 antibody partially restored the ability of LPS to induce TNF activity postextubation (p < .05).

CONCLUSIONS

Surgical trauma rapidly induces a transient hyporesponsiveness of blood cells to endotoxin. Plasma IL-10, which increases during surgery, participates in this hyporesponsiveness.

Measurement of blood clearance time by Limulus G test of Candida-water soluble polysaccharide fraction, CAWS, in mice

The Limulus G test, responsive to beta-1,3-D-glucan, is a well-established method for the detection of invasive fungal infection. We have recently found that Candida albicans released a water-soluble polysaccharide fraction (CAWS) into synthetic medium (Uchiyama et al., FEMS Immunol. Med. Microbiol. 24 (1999) 411-420). CAWS was composed of a mannoprotein-beta-glucan complex and activated Limulus factor G, and thus would be similar to the Limulus active substance in patient's blood. In a preliminary investigation, we have found that CAWS is lethal when administered intravenously in a murine system. In this study, we examined the toxicity and then the fate of CAWS in mice. The lethal toxicity was strain-dependent and strain DBA/2 was the most resistant. The toxicity was, at least in part, reduced by salbutamol sulfate and prednisolone treatment in the sensitive strains. On intravenous administration, the half clearance time (t1/2) was approximately 40 min in mice (DBA/2). On intraperitoneal administration, CAWS appeared in the blood with a peak concentration at 1 h. In order to establish a treatment plan, it is important to demonstrate the onset and the termination of deep-seated mycosis. The Limulus G test is suitable for the above purpose; however, it is necessary to fully understand the fate of beta-1,3-D-glucan in patients' blood.

Carrageenan primes leukocytes to enhance lipopolysaccharide-induced tumor necrosis factor alpha production

We have previously reported that pretreatment with carrageenan (CAR) enhances lipopolysaccharide (LPS)-induced tumor necrosis factor alpha (TNF-alpha) production in and lethality for mice. Whole blood cultured in vitro was used to show that CAR pretreatment results in about a 200-fold increase in LPS-induced TNF-alpha production. CAR by itself did not induce TNF-alpha production. However, CAR-treated cultured medium sensitized whole blood to make more LPS-induced TNF than did saline-treated cultured medium in vitro. It was also demonstrated that CAR pretreatment increases TNF-alpha mRNA levels of both blood cells and peritoneal exudate cells, but not of bone marrow cells. Immunoelectron microscopic analysis revealed that polymorphonuclear leukocytes and macrophages are TNF-alpha-producing cells in CAR-treated mice. In CAR-treated mice, TNF-alpha was seen early after LPS injection in leukocytes in hepatic sinusoids and on the surfaces of endothelial cells. TNF-alpha was also detected late after LPS injection in hepatocytes which become edematous. These results suggest that CAR primes leukocytes to produce TNF-alpha in response to LPS and that they play an important role in the pathogenesis of liver injury.

Dual mechanisms of action of interferon-gamma in potentiating responses to LPS in mice: IL1, TNFalpha and IL6 production in serum and hypothermia

IFNgamma potentiates the production of serum cytokines and mortality induced by LPS, but these responses do not change in parallel, and the underlying mechanisms are not clear. Pretreatment of mice with 15 microg rrIFNgamma intraperitoneally (IP) resulted in potentiation of LPS-induced serum cytokine production and hypothermia, but these changes depended on the pretreatment time and did not occur in parallel. TNFalpha and IL1beta levels showed peak potentiation after 8-h-IFNgamma pretreatment which may result from a process of sensitization of mechanisms involved in LPS responses. IL6 levels were most markedly potentiated after 3- and 6-h-IFNgamma-pretreatment and hypothermia was markedly potentiated after 0-8 h pretreatments. These effects may result from an additional synergistic action of IFNgamma with other mediators when it is present at significant levels earlier after its injection, given that IFNgamma had little (hypothermia) or no effect (cytokines) alone. The degree of potentiation induced by 18-h-IFNgamma pretreatment was related to the dose of LPS, the maximum response having been increased. Two injections of IFNgamma at 42 and 18 h prior to LPS induced greater increases in TNFalpha and IL1beta production than 18-h pretreatment alone, but not in IL6 production or hypothermia. There may be a maximum level of IL6 production which was surpassed under these conditions. These findings suggest that a balance of sensitizing and synergistic actions of IFNgamma with other mediators such as IL1 and TNFalpha, are the major mechanisms underlying its potentiation of LPS responses in mice.

Role of endogenous tumor necrosis factor alpha and gamma interferon in resistance to Corynebacterium pseudotuberculosis infection in mice

The production and roles of endogenous tumor necrosis factor alpha (TNF-alpha) and gamma interferon (IFN-gamma) in the infection of Corynebacterium (C.) pseudotuberculosis were investigated in mice. The maximum levels of TNF-alpha and IFN-gamma were detected on day 4 after infection. The administration of anti-TNF-alpha monoclonal antibody (mAb) as well as anti-IFN-gamma mAb increased bacterial proliferation in the organs, leading to the death of infected mice, but anti-IFN-gamma mAb showed a less marked effect than anti-TNF-alpha mAb. The suppressive effect of anti-TNF-alpha and anti-IFN-gamma mAbs on anticorynebacterial resistance was augmented by the simultaneous administration of these antibodies. Anti-TNF-alpha mAb was found to be highly effective when administered on day 0 and day 4, suggesting that TNF-alpha produced during the early stage of infection is critical for the generation of resistance. Histologically, many microabscesses, severe follicular swelling and lymphocyte destruction were observed in mice treated with anti-TNF-alpha or anti-IFN-gamma mAb. Injection of anti-CD4 or anti-CD8 mAb also resulted in significantly increased mortality and a marked suppression of IFN-gamma production, but had no effect on TNF-alpha production. Carrageenan also showed a marked effect on the exacerbation of infection. Taken together, these results suggest that endogenously produced TNF-alpha and IFN-gamma are both essential to the host defense against C. pseudotuberculosis infection and that these cytokines may have an additive effect.

Selective enhancement of LPS-induced serum TNF-alpha production by carrageenan pretreatment in mice

1. Bacterial lipopolysaccharide (LPS)-induced increases in serum cytokines (TNF-alpha, IL-1 and IL-6) and hypothermia were studied in mice sensitized by carrageenan pretreatment and compared with mice sensitized with heat-killed P. acnes or IFN-gamma, all given IP at appropriate intervals (24 hr, 7 days and 12-18 hr, respectively) before LPS. 2. In mice with localized peritoneal inflammation induced by carrageenan, peak TNF-alpha levels (1.5-2 h after LPS) were markedly enhanced after both doses of LPS tested (50 and 200 microg/mouse IP). However, IL-1beta levels were not changed and IL-6 levels were decreased only after the higher dose of LPS. Hypothermia showed weak and inconsistent changes in carrageenan-sensitized mice. 3. IL-1beta levels in spleen lysates were higher but paralleled those in the serum, being increased in IFN-gamma-sensitized but not in carrageenan-sensitized mice. The levels of both TNF-alpha and IL-1beta were high in the peritoneum of carrageenan-sensitized mice, suggesting that the increased serum TNF-alpha did not emanate from the peritoneum. 4. In mice sensitized with the other two agents, as expected, the levels of all three cytokines increased, but peak levels were attained at the same times post-LPS (TNF-alpha: 1-1.5 hr; IL-1: 3-4 hr; IL-6: 3-4 hr). In addition, hypothermia was increased with both of these methods of sensitization. 5. The lack of consistent correlation of the levels of cytokines studied, particularly TNF-alpha, with the degree of hypothermia, raises questions as to their causative role in its induction in these models. 6. The mechanisms underlying these models of sensitization are clearly different, and further understanding of these mechanisms would aid in the interpretation of the effects of drugs in the models.

Effect of O-antigenic polysaccharide of Escherichia coli on endotoxin neutralizing activity of lysozyme

Endotoxemia is considered to be associated with the high mortality of gram-negative septic patients. Increasing evidence shows that beta-lactam antibiotics have a propensity to induce endotoxin release from the bacterial outer membrane while killing bacteria. We have recently found that egg white lysozyme (EW-LZM) shows strong inhibition of beta-lactam induced bacteriolysis and lipopolysaccharide (LPS) release from Escherichia coli O111, resulting in reduction of the LPS-initiated inflammatory response. In this study, we compared the effect of EW-LZM on E. coli J5, which possesses rough-type LPS (RaLPS), in order to demonstrate the effect of O-antigenic polysaccharide on endotoxin neutralizing activity of EW-LZM and on inhibition of beta-lactam induced lysis by LZM. Both of the beta-lactam induced bacterial lysis and subsequent LPS release were almost completely inhibited by EW-LZM. The effect was more potent than that of wild-type LPS as assessed by released LPS concentration and LPS induced cytokine syntheses. In addition, EW-LZM was effective against lethal infection of E. coli J5 in cyclophosphamide induced leukopenic mice. These facts strongly suggested that O-antigenic polysaccharide negatively modulates LPS neutralizing activity of EW-LZM.

Acute induction of interleukin-6 and biphasic changes of serum complement C3 by carrageenan in mice

Carrageenan has been widely used as an irritant to evoke inflammation in animals or to selectively deplete macrophages in vivo. Although precise understanding of carrageenan activity is a prerequisite for the experimental use of this polysaccharide, the effects of this agent on host-biological systems are still poorly understood. We investigated the effect of carrageenan on serum concentrations of complement C3 and interleukin (IL)-6, a potent complement-inducing factor. Intraperitoneal administration of carrageenan (4 mg) in mice resulted in an initial fall in serum C3 (70% of control, P < 0.05) between 3 and 6 h, but was followed by a significant rise (180% of the control, P < 0.05) at 24h. Prior to the rise in complement C3, a sharp peak of serum IL-6 was observed at 6h after carrageenan treatment. These results indicate potential of carrageenan to enhance host complement systems, which may be associated with, at least in part, an acute induction of IL-6.

Contribution of neutrophils to lipopolysaccharide-induced tumor necrosis factor production and mortality in a carrageenan-pretreated mouse model

Carrageenan (CAR) pretreatment primes mice for lipopolysaccharide (LPS)-induced tumor necrosis factor (TNF)-alpha production in sera and increases their mortality rate. To study the contribution of neutrophils in this model, blood neutrophil count was regulated with cyclophosphamide. After LPS challenge, both serum TNF-alpha activity and mortality risk ratio were significantly higher in neutrophilic mice, but significantly lower in neutropenic mice. In vitro, CAR treatment primed for TNF-alpha production of blood neutrophils, but conversely, that of monocytes was suppressed. We suggest that neutrophils are the major cells to produce TNF-alpha and to determine mouse mortality after LPS challenge in the mouse CAR model.

Hypothermia as an indicator of the acute effects of lipopolysaccharides: comparison with serum levels of IL1 beta, IL6 and TNF alpha

1. Hypothermia was investigated as a parameter indicating the severity of the acute effects of lipopolysaccharides (LPS) in BALB/c mice, and was compared with the induction of serum levels of IL1 beta, TNF alpha and IL6. 2. Hypothermia induced by low doses of LPS (10-50 micrograms/mouse IP LPS E. coli 0111:B4) peaked at 2 hr after LPS and then either plateaued (50 micrograms) or declined. LPS, 100 and 300 mu, induced greater degrees of hypothermia that plateaued or continued to increase with time for 8 hr. Higher doses of LPS induced similar levels of hypothermia until 4 hr but then continued to increase markedly until 8 hr. 3. TNF alpha levels peaked early (1-2 hr) and declined rapidly, IL6 levels peaked at 3 hr and then declined slowly, and IL1 beta levels peaked at 4 hr, declined at lower doses of LPS, plateaued at higher doses and continued to slowly increase at highest doses. 4. The peak levels of the cytokines (IL1 beta up to 4 hr) and hypothermia (4 hr) increased in relation to the dose of LPS and maximum responses were apparently achieved in all cases at 300-1000 micrograms LPS. 5. A similar parallel between hypothermia and induction of cytokines was observed in C57BL6 and OF1 mice, which were good and poor responders to LPS, respectively, and with the more potent Shigella dysenteria LPS in BALB/c mice. 6. In conclusion, hypothermia is a useful parameter for indicating the strength of the acute effects of LPS. Further studies are necessary to determine whether or not the cytokines studied here play a causative role in hypothermia.

Role of nitric oxide during carrageenan-sensitized endotoxin shock in mice

We have previously clarified that sensitization with a sulfated polygalactose, carrageenan (CAR), enhances endotoxin-induced tumor necrosis factor (TNF) production and lethality in mice. The present study was performed to examine the role of nitric oxide (NO) in CAR-sensitized septic mice with two different types of NO synthase (NOS) inhibitors, a non-selective inhibitor to NOS subtypes, N omega-nitro-L-arginine methyl ester (L-NAME), and a selective inhibitor to inducible NOS, aminoguanidine. Seven or eight-week-old male ddY mice were given 5 mg of CAR intraperitoneally as a primer. Then, 5 micrograms of lipopolysaccharide (LPS) was injected into the tail vein 16 hours later the pretreatment. Marked synthesis of NO was induced in CAR-sensitized mice, as indicated by the high plasma levels of the stable endproducts, NO2-/NO3- peaking at 12 hr after the LPS challenge. The peak values at 12 hr after the LPS challenge were dependent on the dose of CAR with 1 to 5 mg, although the injection with 10 mg of CAR was adversely inhibited NO production compared with 5 mg of CAR. The LPS challenge was followed by either L-NAME (0.25, 0.5 or 1 mg) or aminoguanidine (1, 2 or 4 mg) in the septic mice sensitized with 5 mg of CAR. L-NAME reduced the plasma NO2-/NO3- level in a dose-dependent fashion, although it augmented liver injury, as measured by plasma levels of ornithine carbamyltransferase (OCT) and the LPS-induced lethality in a dose-dependent fashion. In contrast, aminoguanidine did not significantly deteriorate either liver injury or lethality in spite of the decrease of NO endproducts in a similar fashion to L-NAME. These findings suggest that the inhibition of constitutive NOS is detrimental and augments LPS-induced liver injury and subsequent lethality.

Effects of nickel oxide on the production of tumor necrosis factor by alveolar macrophages of rats

To evaluate the effect of green nickel oxide (NiO) on the production of tumor necrosis factor (TNF) by alveolar macrophages, alveolar macrophages were exposed to NiO in vitro and in vivo. For the in vitro study, rats alveolar macrophages were incubated with NiO on a microplate for 24 h. TNF activity in the culture supernatant was determined by the L929 bioassay. Rats alveolar macrophages cultured with 100 and 200 micrograms/mL of NiO in vitro induced the production of TNF, however, it was not statistically significant compared with the control that was free from NiO exposure. For exposure in vivo, rats were divided into two groups. Five were exposed to a daily concentration of 11.7 +/- 2.0 mg/m3 of NiO for an 8-hr/d, 5 d/wk, for 4 wk, and five rats (control) were kept in a cage and not exposed to NiO. Bronchoalveolar lavage was performed and the recovered alveolar macrophages were incubated on a microplate for 24 h. TNF production by exposed alveolar macrophages was significantly higher than that of controls.

Detoxification of lipopolysaccharide (LPS) by egg white lysozyme

Recent studies carried out by our group suggest that lysozyme binds to bacterial lipopolysaccharide with a high affinity to produce a complex, and inhibits various biological activities of lipopolysaccharide. Although the basic structure of lipopolysaccharide is independent of the species and strains of Gram-negative bacteria, many structural factors such as O-antigenic polysaccharide, lipid A, substituted groups, and associated molecules, affect the biological activities of lipopolysaccharide. In this study, we prepared lysozyme/lipopolysaccharide complexes using various structures of lipopolysaccharide and compared the activity and physicochemical properties. Native and dansylated lysozyme were found to bind to all tested lipopolysaccharides. The mitogenic activity and TNF production by all tested lipopolysaccharides were significantly reduced by complex formation in vitro. Administration of the complex prepared by various lipopolysaccharides produced significantly less quantities of TNF in the septic shock model. These results suggested that binding of lysozyme to lipopolysaccharide is important for the host both in pathophysiological responses to lipopolysaccharides and in the modification of lipopolysaccharide biological activity.

Quantitative measurement of carbohydrate binding activity of mouse macrophage lectin

A simple ELISA assay measuring lectin activity of a mouse macrophage galactose/N-acetylgalactosamine-specific C-type lectin (MMGL) was developed. The binding of galactosylated poly-lysine (termed a ligand) to the immobilized soluble form of MMGL (rML) was measured quantitatively. Consistent with the characteristics of MMGL, the binding was calcium dependent and inhibited by galactose and N-acetylgalactosamine. An antiserum against rML inhibited the ligand binding, demonstrating the usefulness of this method for the screening of blocking antibodies. Using this assay, we found a significant interaction between MMGL and carrageenans, a group of sulfated polygalactans. The inhibitory effect of carrageenans was not attributable to a nonspecific interaction because other types of sulfated polysaccharides, such as glycosaminoglycans and fucoidin, did not interfere with the ligand binding. The relevance of the present finding to the biological activities of carrageenans is discussed.

Effect of peripheral benzodiazepine receptor ligands on lipopolysaccharide-induced tumor necrosis factor activity in thioglycolate-treated mice

To investigate the effect of peripheral and central benzodiazepine receptor ligands on lipopolysaccharide (LPS)-induced tumor necrosis factor (TNF) activity in mouse macrophages, three types of ligands, 4'-chlorodiazepam (pure peripheral), midazolam (mixed), and clonazepam (pure central), were compared. Midazolam and 4'-chlorodiazepam significantly suppressed LPS (1-microgram/ml)-induced TNF activity in thioglycolate-elicited mouse macrophages. In every concentration examined (0.001 to 100 microM), 4'-chlorodiazepam was the most effective agent, clonazepam was the least effective agent, and midazolam had an effect intermediate between those of the other two ligands. The peripheral benzodiazepine receptor ligands had a dose-dependent suppressive effect, and the 50% inhibitory concentrations were 0.01 microM for 4'-chlorodiazepam and 5 microM for midazolam. Concomitant use of PK 11195 (10 microM), an antagonist of the peripheral benzodiazepine receptor, reversed this suppressive effect with 4'-chlorodiazepam (10 microM) or midazolam (10 microM). PK 11195 showed this antagonistic effect in a dose-dependent manner. Intravenous 4'-chlorodiazepam (5 mg/kg of body weight) significantly suppressed LPS (100-micrograms)-induced TNF activity of sera (2 h postchallenge with LPS) from thioglycolate-treated mice. The present findings suggest that the peripheral benzodiazepine receptor plays an important role in modulating LPS-induced TNF activity in mouse macrophages.

Binding of lysozyme to lipopolysaccharide suppresses tumor necrosis factor production in vivo

Endotoxin (lipopolysaccharide [LPS]) released during gram-negative bacterial infection induces varieties of cytokines which directly and/or indirectly cause shock, disseminated intravascular coagulation, and death. We previously showed that lysozyme (LZM) was an LPS-binding protein and inhibited various immunomodulating activities of LPS. In this study, we examined the effect of LZM on the LPS-triggered septic shock model induced by carrageenan treatment and assessed by tumor necrosis factor production. The data presented in this report strongly suggest that LZM-LPS complex formation completely abrogates tumor necrosis factor production and the mortality caused by LPS and that LZM may be useful for the treatment of endotoxin shock.

Dextran sulphate enhancement of lipopolysaccharide-induced tumour necrosis factor-alpha production by murine peritoneal macrophages: correlation with macrophage blockade

Proteose peptone-induced murine peritoneal macrophages (M phi) were preincubated with 100-800 micrograms/ml of dextran sulphate (DS) 500 (M(r) 500,000) or DS1000 (M(r) 1,000,000). After 2-24 h of the preincubation, the M phi were stimulated with 1 microgram/ml of lipopolysaccharide (LPS) in vitro for 18 h in DS-free culture medium. The culture supernatants were then collected for TNF assay. The LPS-induced TNF activity of M phi supernatant preincubated with DS500 or DS1000 for 6 h was enhanced by up to about ten-fold compared with those preincubated without DS. This enhancing effect was not observed when M phi were preincubated with 100-800 micrograms/ml of low molecular weight DS5 (M(r) 5,000) or neutral dextran (Dex) 500 (M(r) 500,000). The enhancement of LPS-induced TNF-alpha production from M phi was observed after 2 or 4 h of incubation with DS1000 or DS500, respectively. The phagocytic activity of M phi was determined in vitro by the ingestion index and phagocytic capacity using Saccharomyces cerevisiae. Treatment with DS500 or DS1000 significantly suppressed the phagocytic activity from 2 h after the incubation, but this suppression was not observed in M phi incubated with DS5 or Dex500. Our experiments indicate that DS500 and DS1000 act directly on M phi and enhance LPS-induced TNF-alpha production from M phi, and that the enhancement is closely related to the suppression of M phi phagocytic function.

An antagonist of platelet-activating factor suppresses endotoxin-induced tumor necrosis factor and mortality in mice pretreated with carrageenan

We found that carrageenan (CAR), that is, sulfated polygalactose, can enhance both lipopolysaccharide (LPS)-induced tumor necrosis factor (TNF) production and the rate of lethality in mice (M. Ogata, S. Yoshida, M. Kamochi, A. Shigematsu, and Y. Mizuguchi, Infect. Immun. 59:679-683, 1991). It has been reported that platelet-activating factor (PAF) antagonists reduce the rate of mortality from endotoxin shock. However, there are few reports regarding the effect of PAF antagonists on TNF production. The aim of the present study is to examine the effect of TCV-309, a new PAF antagonist, on LPS-induced TNF production and mortality in mice pretreated with CAR. ddY mice (6 to 7 weeks old) were injected intraperitoneally with CAR (5 mg per mouse) and were then divided into two groups: mice treated with a PAF antagonist (TCV-309; Takeda Pharmaceutical Co.) and control mice. The mice treated with PAF antagonist received indicated doses of TCV-309 subcutaneously (s.c.) at 30 min before LPS injection, while the control mice received 1 ml of saline s.c. at the same time. All mice were stimulated by intravenous injection of LPS (50 micrograms per mouse) at 24 h after pretreatment with CAR. At intervals after injection of LPS, serum samples were obtained for a TNF assay in which cytotoxicity to L929 cells was measured. TCV-309 both significantly suppressed LPS-induced TNF production and reduced mortality in a dose-dependent manner. When TCV-309 was administered at 30 min before injection of LPS, the effect of TCV-309 on the suppression of TNF activity was at its peak. Treatment with TCV-309 (990 micrograms per mouse) s.c. significantly improved the survival rate after challenge with LPS compared with the survival rate of control mice. Although the 50% lethal dose of LPS was 15 micrograms per mouse for control mice, it increased to 102 micrograms per mouse for mice that were treated s.c. with TCV-309 (990 micrograms per mouse). Even in vitro, TCV-309 also inhibited LPS-induced TNF production in thioglycolate-elicited macrophages. It was concluded that PAF plays an important role in endotoxin-induced TNF production and mortality.

The immunocytochemical localization of tumour necrosis factor and leukotriene in the rat liver after treatment with lipopolysaccharide

After administration of bacterial lipopolysaccharide, there is an increase in the number of leucocytes which adhere to the endothelial cell surface of the hepatic vessels and pass through the endothelial layer by comparison with controls. There is also marked endothelial cell damage including intracytoplasmic oedema, increased numbers of autophagic vacuoles and dilatation of the intercellular junction in LPS-treated samples. The presence of immunocytochemical products of leukotriene (LTR) and tumour necrosis factor (TNF) was examined using in both LPS-treated and control samples. Immunoreactions of LTR which were seen in specific granules of neutrophils and monocytes attached to the endothelial cell surface may indicate the onset of endothelial cell damage. Positive immunoreactions of TNF on the endothelial cell surface, seen only in LPS-treated samples, indicate that TNF may enhance the passage of blood cells through the endothelia and also increase the endocytotic activity of the liver parenchymal cells, as revealed by the present marker experiment using horseradish peroxidase. Positive reactions of TNF in lysosomes of the endothelial cells suggest that they are able to produce TNF and transport it to the cell surface.

Protective effects of a leukotriene inhibitor and a leukotriene antagonist on endotoxin-induced mortality in carrageenan-pretreated mice

The leukotrienes and tumor necrosis factor (TNF) play an important role in the pathophysiology of septic shock, in which hypotension, leukopenia, thrombocytopenia, and hemoconcentration are observed. This study was performed to examine the effects of a 5-lipoxygenase inhibitor (AA-861), a selective leukotriene receptor antagonist (ONO-1078), and a cyclooxygenase inhibitor (indomethacin) on endotoxin-induced mortality and TNF production in mice. Mice were injected intraperitoneally with carrageenan (5 mg per mouse), which we previously reported as an effective priming agent for lipopolysaccharide (LPS)-induced TNF production and mortality (M. Ogata, S. Yoshida, M. Kamochi, A. Shigematsu, and Y. Mizuguchi, Infect. Immun. 59:679-683, 1991). The indicated doses of AA-861, ONO-1078, indomethacin, or controls were administrated subcutaneously 30 min before LPS (50 micrograms per mouse) provocation. The mortality of mice was significantly decreased by pretreatment with AA-861 (P less than 0.001) or ONO-1078 (P less than 0.01) but not by pretreatment with indomethacin. The 50% lethal dose of LPS in the mice treated with dimethyl sulfoxide or ethanol was 32 or 33 micrograms, respectively, and it increased to 83 micrograms with AA-861 or 59 micrograms with ONO-1078, respectively. Neither AA-861 nor ONO-1078 suppressed LPS-induced TNF production in sera. Treatment with AA-861 significantly decreased the leukopenia and thrombocytopenia, and ONO-1078 significantly decreased the hemoconcentration and thrombocytopenia. The role of endogenous TNF was also examined in the carrageenan-pretreated mice. Treatment with 2 x 10(5) U of rabbit anti TNF-alpha antibody intravenously 2 h before LPS challenge significantly suppressed the LPS-induced TNF activity and decreased the mortality. Therefore, both leukotrienes and TNF play important roles in endotoxin-induced shock and mortality.

Priming effect of dextran sulphates on lipopolysaccharide-induced tumour necrosis factor production in mice

Dextran sulphate (DS) 500 (M.W. 500,000) is commonly used as a reticuloendothelial (RE) blocker. We found that lipopolysaccharide (LPS)-induced tumour necrosis factor (TNF) production in sera was enhanced when mice were pretreated with DS500. When mice were pretreated with DS1000 (M.W. 1,000,000), TNF activity in sera was also significantly enhanced by the LPS injection in comparison with the saline-treated group, but not by the pretreatment with the low molecular weight of DS5 (M.W. 5,000), neutral dextran (Dex) 500, or positively-charged diethylaminoethyl dextran (DEAE-Dex) 500. The enhancement of LPS-induced TNF production occurred from 2 h after DS500 pretreatment. Pretreatment with DS500 or DS1000 significantly suppressed the carbon clearance from the blood in mice from 2 h after DS injection, but this suppression was not detected by the pretreatment with DS5, Dex500, or DEAE-Dex500. We suggest that negative-charge and high molecular weight are essential for dextran derivatives to enhance LPS-induced TNF production, and that the enhancing effect of DS is closely related to the suppression of the RE function.

Experimental elimination of tumor necrosis factor in low-dose endotoxin models has variable effects on survival

Tumor necrosis factor alpha (TNF) is thought to play a major role in the pathogenesis of septic shock. Anti-TNF antibody was preadministered in low-dose endotoxin lethality models in which BALB/c mice were challenged with small amounts of lipopolysaccharide following their sensitization with either carrageenan (CAR) or D-galactosamine (D-GalN). Although the antibody virtually eliminated circulating TNF in both the CAR and the D-GalN models, only the D-GalN model mice were afforded survival, adding to a growing body of evidence that substances other than TNF play a key role in endotoxin-induced lethality. Further examination of sera from these mice showed a much greater elevation of interleukin-6 levels in the CAR-sensitized group than in the D-GalN-sensitized group.