Lipopolysaccharide-induced Tumor Necrosis Factor Production Research Articles

Electrostimulation of the carotid sinus nerve in mice attenuates inflammation via glucocorticoid receptor on myeloid immune cells

BackgroundThe carotid bodies and baroreceptors are sensors capable of detecting various physiological parameters that signal to the brain via the afferent carotid sinus nerve for physiological adjustment by efferent pathways. Because receptors for inflammatory mediators are expressed by these sensors, we and others have hypothesised they could detect changes in pro-inflammatory cytokine blood levels and eventually trigger an anti-inflammatory reflex.MethodsTo test this hypothesis, we surgically isolated the carotid sinus nerve and implanted an electrode, which could deliver an electrical stimulation package prior and following a lipopolysaccharide injection. Subsequently, 90 min later, blood was extracted, and cytokine levels were analysed.ResultsHere, we found that carotid sinus nerve electrical stimulation inhibited lipopolysaccharide-induced tumour necrosis factor production in both anaesthetised and non-anaesthetised conscious mice. The anti-inflammatory effect of carotid sinus nerve electrical stimulation was so potent that it protected conscious mice from endotoxaemic shock-induced death. In contrast to the mechanisms underlying the well-described vagal anti-inflammatory reflex, this phenomenon does not depend on signalling through the autonomic nervous system. Rather, the inhibition of lipopolysaccharide-induced tumour necrosis factor production by carotid sinus nerve electrical stimulation is abolished by surgical removal of the adrenal glands, by treatment with the glucocorticoid receptor antagonist mifepristone or by genetic inactivation of the glucocorticoid gene in myeloid cells. Further, carotid sinus nerve electrical stimulation increases the spontaneous discharge activity of the hypothalamic paraventricular nucleus leading to enhanced production of corticosterone.ConclusionCarotid sinus nerve electrostimulation attenuates inflammation and protects against lipopolysaccharide-induced endotoxaemic shock via increased corticosterone acting on the glucocorticoid receptor of myeloid immune cells. These results provide a rationale for the use of carotid sinus nerve electrostimulation as a therapeutic approach for immune-mediated inflammatory diseases.

Specific features of human monocytes activation by monophosphoryl lipid A

We deciphered the mechanisms of production of pro- and anti-inflammatory cytokines by adherent human blood mononuclear cells (PBMC) activated by lipopolysaccharide (LPS) or monophosphoryl lipid A (MPLA). Both LPS and MPLA induced tumor necrosis factor (TNF) production proved to be dependent on the production of interleukin-1β (IL-1β). Of note, MPLA induced IL-1β release in human adherent PBMCs whereas MPLA was previously reported to not induce this cytokine in murine cells. Both LPS and MPLA stimulatory effects were inhibited by Toll-like receptor-4 (TLR4) antagonists. Only monocytes activation by LPS was dependent on CD14. Other differences were noticed between LPS and MPLA. Among the different donors, a strong correlation existed in terms of the levels of TNF induced by different LPSs. In contrast, there was no correlation between the TNF productions induced by LPS and those induced by MPLA. However, there was a strong correlation when IL-6 production was analyzed. Blocking actin polymerization and internalization of the agonists inhibited MPLA induced TNF production while the effect on LPS induced TNF production depended on the donors (i.e. high TNF producers versus low TNF producers). Finally, conventional LPS, tolerized adherent PBMCs to TLR2 agonists, while MPLA primed cells to further challenge with TLR2 agonists.

C-Src deactivation by the polyphenol 3-O-caffeoylquinic acid abrogates reactive oxygen species-mediated glutamate release from microglia and neuronal excitotoxicity

3-O-caffeoylquinic acid (3-CQA) is an isomer of chlorogenic acid, which has been shown to regulate lipopolysaccharide-induced tumor necrosis factor production in microglia. Whereas overactivation of microglia is associated with neuronal loss in brain diseases via reactive oxygen species (ROS) production and glutamate excitotoxicity, naïve (nonactivated) microglia are believed to generate little ROS under basal conditions, contributing to the modulation of synaptic activity and nerve tissue repair. However, the signaling pathways controlling basal ROS homeostasis in microglial cells are still poorly understood. Here we used time-lapse microscopy coupled with highly sensitive FRET biosensors (for detecting c-Src activation, ROS generation, and glutamate release) and lentivirus-mediated shRNA delivery to study the pathways involved in antioxidant-regulated ROS generation and how this associates with microglia-induced neuronal cell death. We report that 3-CQA abrogates the acquisition of an amoeboid morphology in microglia triggered by Aβ oligomers or the HIV Tat peptide. Moreover, 3-CQA deactivates c-Src tyrosine kinase and abrogates c-Src activation during proinflammatory microglia stimulation, which shuts off ROS production in these cells. Moreover, forced increment of c-Src catalytic activity by overexpressing an inducible c-Src heteromerization construct in microglia increases ROS production, abrogating the 3-CQA effects. Whereas oxidant (hydrogen peroxide) stimulation dramatically enhances glutamate release from microglia, such release is diminished by the 3-CQA inhibition of c-Src/ROS generation, significantly alleviating cell death in cultures from embryonic neurons. Overall, we provide further mechanistic insight into the modulation of ROS production in cortical microglia, indicating antioxidant-regulated c-Src function as a pathway for controlling microglia-triggered oxidative damage.

Evaluation of the anti-endotoxin effects of polymyxin B in a feline model of endotoxemia

Directed, effective therapies for feline sepsis are needed to reduce the high morbidity and mortality associated with this disease. We investigated the anti-endotoxin effects of polymyxin B (PMB) in a blinded, placebo controlled fashion, both ex vivo in a feline whole blood culture system and in vivo, using a low-dose endotoxin infusion in cats. Serial measures of systemic inflammation, and hemodynamic stability, were compared between groups. Ex vivo, PMB significantly decreased lipopolysaccharide-induced tumor necrosis factor (TNF) production from whole blood. PMB (1mg/kg over 30min) demonstrated anti-endotoxin effects in vivo, including decreased peak plasma TNF activity (P<0.001) and increased white blood cell count (P=0.019), with no adverse effects. Given the apparent safety and anti-endotoxin effects of PMB in this endotoxemia model, a carefully designed, randomized, blinded, placebo controlled clinical trial evaluating the use of PMB in naturally occurring Gram-negative feline sepsis should be considered.

Effects of a MAPK p38 inhibitor on lung function and airway inflammation in equine recurrent airway obstruction

It has been suggested that many of the beneficial effects of corticosteroids are mediated through mitogen-activated protein kinase (MAPK) p38 inhibition. To investigate the efficacy of the MAPK p38 inhibitor compound MRL-EQ1 to either prevent (Phase 1) or treat (Phase 2) recurrent airway obstruction (RAO) in horses. MRL-EQ1 was administered i.v. at a dosage of 0.75-1.5 mg/kg bwt q. 12 h. In Phase 1, susceptible horses in clinical remission were divided into 2 groups (n = 5/group), based on historical values of respiratory mechanics. All horses were entered in the study in pairs (one control, one treated horse) and exposed to the same environmental challenge (stabling, mouldy hay and dusty conditions). The treatment group received MRL-EQ1 for 14 days while the control horses were untreated during the same period. In Phase 2, affected horses were ranked by severity of respiratory dysfunction and split randomly into either dexamethasone or MRL-EQ1 treatment groups (n = 5/group). Bronchoalveolar lavage fluid, respiratory mechanic measurements, MRL-EQ1 plasma concentration and tumour necrosis factor (TNF) whole blood activity were evaluated sequentially. In Phase 1, MRL-EQ1 did not prevent the occurrence of clinical signs and pulmonary inflammation. However, treatment was associated with a reduction in severity and a delay in the onset of signs and a reduction in pulmonary neutrophilia. In Phase 2, plasma concentrations achieved resulted in ex vivo suppression of lipopolysaccharide-induced TNF production in equine blood. MRL-EQ1 did not improve airway inflammation or lung function and was associated in a dose dependent manner with behavioural (depression, excitability) and blood changes (neutrophilia, increased serum muscle enzyme concentrations). Inhibition of p38 in the horse was partially effective in reducing clinical signs and airway inflammation when administered prior to, but not during clinical exacerbation in RAO. Inhibitors of p38 MAPK with a better toxicity profile may be effective in the prevention or treatment of RAO.

Insulin Inhibits LPS-Induced Signaling Pathways in Alveolar Macrophages

The systemic inflammatory response syndrome (SIRS) is triggered by lipopolysaccharide (LPS) from Gram-negative bacteria. Insulin was shown to have a protective role in SIRS related to sepsis. Lungs are particularly affected in this condition and provide a second wave of mediators/cytokines which amplifies SIRS. The aim of the present study was to investigate the effect of insulin on the signaling pathways elicited by LPS in alveolar macrophages (AMs) and its consequence in cellular response to LPS measured as production of tumor necrosis factor (TNF). To this purpose, resident AMs from male Wistar rats were obtained by lung lavage and stimulated by LPS (100 ng/mL). Insulin (1 mU/mL) was added 10 min before LPS. Activation (phosphorylation) of signaling molecules by LPS was analyzed by western blot, 30 min after LPS stimulation. TNF was measured in the AMs culture supernatants by bioassay using L-929 tumor cells. Relative to controls, LPS induced a significant increase in the activation of ERK (3.6-fold), p38 (4.4-fold), Tyr-326 Akt (4.7-fold), Ser-473 Akt (6.9-fold), PKCα (4.7-fold) and PKCδ (2.3-fold). Treatment of AMs with insulin before LPS stimulation, significantly reduced the activation of ERK (54%), p38 (48%), Tyr-326 Akt (64%), Ser-473 Akt (41%), PKCα (62%) and PKCδ (39%). LPS induced TNF production in AMs which was also inhibited by insulin (60%). These results show that insulin down-regulates MAPK, PI3K and PKCs and inhibits a downstream effect of LPS, TNF production, in rat AMs stimulated with LPS and suggest that the protective effect of insulin in sepsis could be through modulation of signal transduction pathways elicited by LPS in lung macrophages.

Elevated CD16 expression by monocytes from patients with tumor necrosis factor receptor–associated periodic syndrome

Tumor necrosis factor receptor-associated periodic syndrome (TRAPS) is an inherited autosomal-dominant autoinflammatory condition caused by mutations in the ectodomain of the 55-kd tumor necrosis factor (TNF) receptor superfamily 1A. Proinflammatory blood monocytes with the phenotype CD14+,CD16+,HLA-DR++ are a major source of TNF, and the number of such monocytes is increased during infection and inflammation. The aim of this study was to investigate whether the expression of circulating CD16+ monocytes is affected in patients with TRAPS. Peripheral blood obtained from patients with TRAPS and healthy control subjects was stained with monoclonal antibodies to detect CD14++,CD16- monocytes and CD14+,CD16+ monocytes, using flow cytometry. Lipopolysaccharide-induced TNF production was measured by intracellular cytokine staining. Activation-induced shedding of CD16 was investigated by treating blood samples with phorbol myristate acetate. The level of CD16 expression by CD14+,CD16+ monocytes, but not their absolute number, was significantly elevated in patients with TRAPS, even though the patients were not experiencing clinically overt episodes of autoinflammation at the time of sampling. These findings are similar to those for the C-reactive protein levels and erythrocyte sedimentation rates in the same patients. The enhanced level of CD16 expression by monocytes from patients with TRAPS was not attributable to a defect in activation-induced shedding of CD16. The CD14+,CD16+ monocytes were the predominant source of TNF in both patients and healthy control subjects. The level of CD16 expression by monocytes was elevated in patients with TRAPS, as a feature of the underlying constitutive inflammation status.

Expression of Constitutively Active STAT3 Can Replicate the Cytokine-suppressive Activity of Interleukin-10 in Human Primary Macrophages

There is general agreement that signal transducer and activation of transcription 3 (STAT3) is required to mediate the anti-inflammatory activities of interleukin (IL)-10. However, STAT3 is activated by multiple factors that do not share the anti-inflammatory activity of IL-10. The question remains whether STAT3 is sufficient for the anti-inflammatory effects or whether there are other signals required, as had been suggested previously. We set out to map the human IL-10 receptor and to identify the key elements involved in transducing the cytokine-suppressive effects of IL-10. We were able to show an absolute requirement for both of the tyrosine residues found within the YXXQ-STAT3-docking site within the IL-10 receptor 1 and that no other signals appeared to be required. We used a constitutively active STAT3 to determine whether expression of this factor could suppress lipopolysaccharide-induced tumor necrosis factor and IL-6 production. Our data show that STAT3 activity can suppress both IL-6 and tumor necrosis factor production in lipopolysaccharide-stimulated macrophages. However, in synovial fibroblasts, STAT3 did not suppress IL-6 production, suggesting that the cellular environment plays an important role in dictating whether STAT3 drives a pro- or anti-inflammatory response.

Modulation of redox signaling is invovled in zinc inhibition of lipopolysaccharide-induced tumor necrosis factor production and liver injury

Modulation of redox signaling is invovled in zinc inhibition of lipopolysaccharide-induced tumor necrosis factor production and liver injury

Adherence influences monocyte responsiveness to interleukin-10.

We studied the effects of adherence on the properties of interleukin (IL)-10 on monocyte-enriched peripheral blood mononuclear cells. We found that the decrease of CD11b expression induced by IL-10 was enhanced by adherence. Toll-like receptor (TLR)2 and TLR4 mRNA, as well as TLR4 surface expression, were significantly up-regulated by IL-10 in adherent cells. The absence of adherence prevented the inhibitory effects of IL-10 on lipopolysaccharide-induced tumor necrosis factor (TNF) and granulocyte-colony stimulating factor production and increased IL-1beta production and soluble TNF receptor II release in IL-10-pretreated cells. Similarly, the absence of adherence amplified the enhancement of phagocytosis induced by IL-10. Tyk2 and signal transducer and activator of transcription 3 (STAT3) phosphorylation and suppressor of cytokine signaling 3 (SOCS3) expression were induced by IL-10 in both conditions, but a longer activation and/or expression were observed in adherent monocytes. Finally, heme oxygenase-1, an anti-inflammatory molecule, was induced by IL-10 in adherent monocytes, whereas its expression remained low in nonadherent cells. Altogether, these data illustrate that adherence modulates the properties and the anti-inflammatory effects of IL-10.

Effects of anti-tumour necrosis factor, interleukin-10 and antibiotic therapy in the indometacin-induced bowel inflammation rat model.

The administration of indometacin to rats increases intestinal permeability and induces inflammatory pathology of the small bowel. This represents a potential model for Crohn's disease. To analyse the pathogenic role of T cells, tumour necrosis factor and bacterial flora in indometacin-induced changes in small bowel permeability and inflammation. Rats were given indometacin, 13 mg/kg, on day 1 and day 2. The effects of antibiotic (metronidazole, aztreonam and amoxicillin/clavulanic acid), anti- tumour necrosis factor and interleukin-10 therapy were evaluated. The parameters used were weight change, serum haemoglobin, chromium-51 ethylenediaminetetra-acetate permeability and macro-and microscopic score on day 5. Results in conventionally harboured rats were compared with those in T-cell-free rats. Additional in vitro experiments were carried out to test the effect of metronidazole on tumour necrosis factor production. Indometacin administration resulted in small bowel ulcers and inflammation, independently of T cells. Metronidazole was more potent than amoxicillin/clavulanic acid and anti-tumour necrosis factor in improving the indometacin-induced small bowel inflammation. Only part of the efficacy was through improvement of increased intestinal permeability. Aztreonam and interleukin-10 had no effect. Metronidazole also suppressed in vitro lipopolysaccharide-induced tumour necrosis factor production, suggesting a therapeutic effect of this drug through the inhibition of tumour necrosis factor. These data implicate anaerobic bacteria and tumour necrosis factor production, but not T cells, as essential elements of the pathogenesis of indometacin-induced small bowel inflammation. Tumour necrosis factor is also involved in the change in intestinal permeability. Metronidazole was the most efficacious drug in this model, probably because it suppressed anaerobic bacteria and directly inhibited tumour necrosis factor production.

Suppression of lipopolysaccharide-induced tumor necrosis factor-release and liver injury in mice by naringin

Suppressive effects of naringin on lipopolysaccharide-induced tumor necrosis factor (TNF) release followed by liver injury were investigated. Intraperitoneal (i.p.) treatment with naringin prior to an intravenous (i.v.) challenge of lipopolysaccharide significantly reduced serum TNF levels in a dose-dependent manner and was the most effective when administered 60 min prior to lipopolysaccharide challenge. Treatment with naringin 3 h prior to lipopolysaccharide challenge resulted in complete protection from lipopolysaccharide lethality in d-galactosamine-sensitized mice. Histological estimation revealed that massive cell infiltration followed by severe injury developed in the livers of lipopolysaccharide-treated and d-galactosamine-treated mice unless they had been pretreated with naringin. Appearance of apoptotic cells was also found to decrease by treatment with naringin. Increases in serum levels of aspartate aminotransferase, alanine aminotransferase and creatine kinase, responsible for lipopolysaccharide-induced liver injury, blocked by naringin administration and the levels were nearly to the normal level. These results indicate that action of naringin is mediated through suppression of lipopolysaccharide-induced TNF production.

Enteral vitamin E supplementation inhibits the cytokine response to endotoxin.

To evaluate the effect of short-term, high-dose enteral supplementation of 3 different vitamin E derivatives: free alpha-tocopherol (VE), alpha-tocopherol succinate (VES), and alpha-tocopherol acetate (VEA) on macrophage and monocyte activation. Sprague-Dawley rats (weight, 150-200 g) were assigned to 1 of 5 experimental groups: saline (control), ethanol (control), VES (100 mg/kg), VEA (100 mg/kg), or VE (100 mg/kg). Rats underwent oral gavage once per day for 5 days with 0.5 mL of their assigned solution. All vitamin E derivatives were diluted in 75% ethanol. Rats were then killed and whole-blood and peritoneal macrophages were harvested and stimulated with lipopolysaccharide (10 microg/mL) in vitro. Tumor necrosis factor (TNF) production was measured by enzyme-linked immunosorbent assay. Additional serum samples were analyzed for alpha-tocopherol concentration by high-performance lipid chromatography. Whole-blood TNF production was maximal in the control groups after 3 hours of incubation and began to decline by 6 hours. Supplementation with all 3 vitamin E derivatives resulted in suppression of lipopolysaccharide-induced TNF production at both time points when compared with both ethanol and saline controls (P<.05, analysis of variance [ANOVA]). All 3 vitamin E derivatives also resulted in significant inhibition of lipopolysaccharide-induced TNF production by peritoneal macrophages when compared with their ethanol-carrier control but not with the saline control (P<.05, ANOVA). The degree of TNF suppression correlated directly with serum alpha-tocopherol levels. Our data demonstrate that a short-term, high-dose enteral supplementation of vitamin E can modulate the monocyte and macrophage response to endotoxin. These data, along with other animal studies showing a protective effect of vitamin E treatment in sepsis and ischemia-reperfusion injury, suggest a potential role for vitamin E supplementation in patients at risk of the systemic inflammatory response syndrome.

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.

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)- α 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- α activity and mortality risk ratio were significantly higher in neutrophilic mice, but significantly lower in neutropenic mice. In vitro, CAR treatment primed for TNF- α production of blood neutrophils, but conversely, that of monocytes was suppressed. We suggest that neutrophils are the major cells to produce TNF- α and to determine mouse mortality after LPS challenge in the mouse CAR model.

A glucocorticoid receptor-independent mechanism for neurosteroid inhibition of tumor necrosis factor production

We investigated the effect of two neurosteroids, pregnenolone and dehydroepiandrosterone sulfate on lipopolysaccharide-induced tumor necrosis factor (TNF) production in vivo and in vitro. Dehydroepiandrosterone sulfate (0.3–30 mg/kg, i.p.) inhibited serum TNF induced by lipopolysaccharide (2.5 μg/mouse, i.p.), without affecting the induction of serum corticosterone. Intracerebroventricular (i.c.v.) administration of dehydroepiandrosterone sulfate (0.2–5 μg/mouse) also inhibited brain TNF induced by i.c.v. lipopolysaccharide (2.5 μg/mouse). Dehydroepiandrosterone sulfate and pregnenolone (10 −6–10 −4 M) inhibited TNF production in vitro by lipopolysaccharide-stimulated human peripheral blood mononuclear cells or by the human THP-1 cell line, suggesting that this action might also be relevant in humans. We obtained two lines of evidence that neurosteroids do not inhibit TNF via the glucocorticoid receptor. (1) Dehydroepiandrosterone sulfate and pregnenolone did not activate the α 1-acid glycoprotein promoter, a typical effect of glucocorticoids mediated by the glucocorticoid receptor, while strong activation of this promoter was observed with dexamethasone. (2) The inhibitory effect of dehydroepiandrosterone sulfate and pregnenolone on TNF production was not reversed by the glucocorticoid receptor antagonist, mifepristone (RU38486). On the contrary the inhibitory effect of dexamethasone, a classical glucocorticoid and inhibitor of TNF synthesis, was completely reversed by RU38486.

Regulation of lipopolysaccharide-induced tumor necrosis factor production by cyclosporin A in mice primed with muramyl dipeptide

The effect of cyclosporin A (CsA) on tumor necrosis factor (TNF) or interleukin-6 (IL-6) production was evaluated in vivo in primed or unprimed mice challenged with lipopolysaccharide (LPS). Both pretreatment with BCG infection or with muramyl dipeptide (MDP) prior to LPS challenge resulted in an increase in the cytokine bioactivity level in the blood. CsA administration inhibited the TNF production. In unprimed mice, either normal or sensitized to LPS lethality by galactosamine treatment, a marked decrease in the cytokine level was observed after injection of CsA. After adrenalectomy, the yield of both TNF and IL-6 following LPS injection was markedly elevated but decreased by CsA administration. Ex vivo experiments have shown that the inhibitory effect of CsA could be demonstrated at the level of macrophages from mice previously given the drug. If mice had received MDP, in vitro responses of cells to LPS were enhanced but again CsA decreased the mRNA expression and protein secretion.

Regulation of lipopolysaccharide-induced tumor necrosis factor production by cyclosporin A in mice primed with muramyl dipeptide

The effect of cyclosporin A (CsA) on tumor necrosis factor (TNF) or interleukin-6 (IL-6) production was evaluated in vivo in primed or unprimed mice challenged with lipopolysaccharide (LPS). Both pretreatment with BCG infection or with muramyl dipeptide (MDP) prior to LPS challenge resulted in an increase in the cytokine bioactivity level in the blood. CsA administration inhibited the TNF production. In unprimed mice, either normal or sensitized to LPS lethality by galactosamine treatment, a marked decrease in the cytokine level was observed after injection of CsA. After adrenalectomy, the yield of both TNF and IL-6 following LPS injection was markedly elevated but decreased by CsA administration. Ex vivo experiments have shown that the inhibitory effect of CsA could be demonstrated at the level of macrophages from mice previously given the drug. If mice had received MDP, in vitro responses of cells to LPS were enhanced but again CsA decreased the mRNA expression and protein secretion.

Independent down-regulation of central and peripheral tumor necrosis factor production as a result of lipopolysaccharide tolerance in mice

Lipopolysaccharide (LPS) induces a variety of central and peripheral effects that are largely mediated by cytokines, including tumor necrosis factor (TNF). Peripheral (intravenous [i.v.]) administration of LPS (2.5 micrograms per mouse) induced TNF levels in the serum and spleen but not in the brain, while central (intracerebroventricular [i.c.v.]) administration of LPS induced TNF production both in the brain and in the periphery. Mice challenged with LPS after LPS pretreatment (35 micrograms per mouse, intraperitoneally, as a single dose on day -3 or as a 4-day treatment on days -5 to -2) were unresponsive in terms of induction of serum TNF. When peripherally LPS-tolerant mice (where LPS pretreatment was given intraperitoneally) were challenged with an i.c.v. dose of LPS, brain (but not serum) TNF was still produced, meaning that the LPS-tolerant state was confined to the periphery. However, if LPS pretreatment was given i.c.v. (35 micrograms, as a single dose), the brain, like the periphery, became LPS tolerant in terms of TNF production. We investigated how tolerance to LPS affected two of its actions, decrease in food intake and induction of serum corticosterone (CS). After an i.v. challenge in peripherally LPS-tolerant mice, no decrease in food intake was observed, but this response was still elicited by an i.c.v. challenge. LPS tolerance reduced the CS response to i.v. and i.c.v. challenge. These results suggest that LPS-induced decrease in food intake might be a fully central effect, while the increase of serum CS might be due to both central and peripheral actions.

Suppression of lipopolysaccharide-induced fulminant hepatitis and tumor necrosis factor production by bisbenzylisoquinoline alkaloids in bacillus Calmette-Guerin-treated mice

The bisbenzylisoquinoline (BBI) alkaloids chondocurine, cycleanine, tetrandrine and berbamine were tested for their capacity to suppress hepatic injury and production of tumor necrosis factor (TNF) induced by lipopolysaccharide (LPS) in mice primed with bacillus Calmette-Guerin (BCG). When administered for three consecutive days before LPS injection, chondocurine, cycleanine and tetrandrine (10 mg/kg/day) strongly suppressed serum alanine aminotransferase (EC 2.6.1.1.) and aspartate aminotransferase (EC2.6.1.2.); however, berbamine gave only slight protection. Chondocurine, cycleanine and tetrandrine but not berbamine significantly reduced the level of TNF which peaked 2 hr after LPS injection. This study shows that BBI alkaloids prevent BCG/LPS-induced hepatitis at least in part by suppressing TNF production.