Mutations of Arabidopsis in potential transduction and response components of the phototropic signaling pathway

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.     

Involvement of TNF alpha, IL-1 beta and IL-1 receptor antagonist in LPS-induced rabbit uveitis

The objective of the study was to investigate involvement of TNF alpha, IL-1 beta and IL-1 receptor antagonist (IL-1Ra) in lipopolysaccharide (LPS)-induced uveitis. Intravitreal injection of LPS (100 ng) to rabbits induced a massive leukocyte infiltration and protein leakage into the aqueous humor. Aqueous leukocyte counts and protein levels reached a peak 24 hr after this injection. The peak concentrations of aqueous TNF alpha (230 +/- 37 pg ml-1, at 9 hr) and IL-1 beta (185 +/- 80 pg ml-1, at 18 hr) preceded peak levels of aqueous leukocyte counts and protein levels. In contrast, the levels of aqueous IL-1Ra peaked at 48 hr (12,239 +/- 1964 pg ml-1) and a fairly high concentration of IL-1Ra remained when the inflammatory reactions subsided. Immunohistochemistry and leukocyte-depletion studies showed that infiltrating leukocytes were the major cellular sources of aqueous TNF alpha, IL-1 beta and IL-1Ra. Intravitreal injection of homologous TNF alpha (0.1-1.5 micrograms) or IL-1 beta (0.5-5 ng) reproduced a rapid leukocyte infiltration and protein leakage. Administration of anti-TNF alpha mAb (10 micrograms) suppressed the number of LPS-induced infiltrating neutrophils by 50%, mononuclear cells by 58%, and protein leakage by 42%. Administration of rabbit IL-1Ra (10 micrograms) also suppressed neutrophil influx by 78%, however, neither mononuclear cell influx nor protein leakage was inhibited by rabbit IL-1Ra. Co-administration of the two inhibitors enhanced inhibition of neutrophil infiltration to 88%, and protein leakage to 64%. We conclude that TNF alpha and IL-1 beta are the principal mediators of LPS-induced uveitis. Our observations also suggest that endogenous IL-1Ra may down-regulate inflammatory reactions.     

Effect of homologous interleukin-1, interleukin-6 and tumor necrosis factor-alpha on the core body temperature of mice

Lipopolysaccharide (LPS) and homologous cytokines were tested for their effect on core temperature in mice using battery-operated telemetric devices placed in the peritoneal cavity. One microgram LPS injected intraperitoneally (i.p.) induced a biphasic effect on core body temperature (Tc), a rapid decrease in Tc with a peak around 30-45 min followed by a prolonged rise around 150-300 min. When a higher dose of LPS (5 microg) was used, the hypothermia was increased in magnitude and lasted much longer, and no fever was observed. Both the decrease and the increase in Tc caused by LPS were prevented by pretreating the mice with indomethacin, a cyclooxygenase inhibitor, but not by a nitric oxide synthase inhibitor. Mouse interleukin-1beta (mIL-1beta, 100 ng, i.p.) induced changes resembling those to LPS, a short-lived decrease in Tc, followed by a small increase. When 1 microg mIL-1beta was injected a profound hypothermia lasting more than 3 h was observed. Mouse IL-6 (1 microg) failed to alter core temperature after either intravenous (i.v.) or i.p. administration. Human IL-6 was also ineffective. Recombinant mouse tumor necrosis factor-alpha (mTNFalpha) also failed to alter the core temperature of mice when injected at a dose of 1 microg (i.p. or i.v.). However, a higher dose of mTNFalpha (5 microg i.p.) caused a short-lived decrease in Tc, followed by a small increase. Similar results were obtained with LPS and the cytokines in C57Bl/6J mice, except that mIL-1beta was ineffective in this strain. These results indicate that the endocrine, neurochemical and behavioral responses to IL-1, IL-6 and TNFalpha administration cannot be explained by changes in Tc, although they may contribute to them. They also suggest that IL-1beta may account for the fever observed following LPS, but that these cytokines are probably not the only factors involved in LPS-induced changes in Tc.     

Enhancement of the surface expression of tumor necrosis factor alpha (TNFalpha) but not the p55 TNFalpha receptor in the THP-1 monocytic cell line by matrix metalloprotease inhibitors

The monocytic cell line THP-1 can be induced to express and release tumor necrosis factor alpha (TNFalpha) and both TNFalpha receptors (p55 and p75) upon exposure to bacterial lipopolysaccharide (LPS). The broad-spectrum matrix metalloprotease (MMP) inhibitors [4-(N-hydroxyamino)-2R-isobutyl-3S-(phenylthiomethyl)succinyl]-L-p henylalanine-N-methylamide (GI-129471) and marimastat [2S-[N4(R*),2R*,3S*]]-N4[2,2-dimethyl-1-[(methylamino)carbonyl]propyl]-N 1,2-dihydroxy-3-(2-methylpropyl)butanediamide (BB-2516) were effective inhibitors of LPS-induced TNFalpha (soluble) release with IC50 values of 0.2 and 4.0 microM, respectively. Upon LPS stimulation, the expression of pro-TNFalpha (membrane associated) on the cell surface (FACS analysis) could not be observed. However, in the presence of GI-129471, a concentration-dependent increase in TNFalpha surface expression was observed. Peak expression (percentage of cells expressing pro-TNFalpha and mean fluorescence units) in the presence of GI-129471 was at 2 hr, and steadily declined to return to near control levels by 8 hr. This time course was similar to TNFalpha release, which also peaked at 2-4 hr after LPS exposure and then declined. Stimulation of THP-1 cells with LPS + phorbol myristate acetate increased the percentage of cells expressing pro-TNFalpha by 10-fold. In the presence of GI-129471, these increases were augmented further and peaked between 2 and 4 hr, but also returned to near control levels of expression by 24 hr. This was in contrast to the release of soluble TNFalpha, which continued to accumulate over a 24-hr time course. TNFalpha receptor I (p55, TNFRI) and II (p75, TNFRII) shedding was also inhibited by GI-129471 (IC50 = 1.5 and 3.1 microM, respectively) and BB-2516 (IC50 = 14 and 15 microM, respectively). Unlike pro-TNFalpha surface expression, surface expression of both TNFalpha receptors steadily increased over 72 hr. In contrast to pro-TNFalpha surface expression, TNFRI surface expression was not augmented by these MMP inhibitors in THP-1 cells after LPS stimulation. Surface expression of TNFRII was augmented by these MMP inhibitors. These results suggest that even in the continued presence of LPS stimulation and an inhibitor of TNFalpha processing, the augmented surface expression of TNFalpha is transient. The potential "deleterious" implications of high levels of surface pro-TNFalpha expression in the presence of these inhibitors may be lessened by its transient nature.     

Interferon-gamma potentiates interleukin (IL)-6 and tumor necrosis factor-alpha but not IL-1beta induced by endotoxin in the brain

Because interferon-gamma (IFN gamma) is present in the central nervous system during neurologic diseases associated with inflammation, its effect on endotoxin-induced cytokines was studied. Cerebrospinal fluid (CSF) and serum levels of interleukin (IL)-1beta, IL-6, and tumor necrosis factor-alpha (TNF alpha), their messenger RNA expression in brain areas (hypothalamus, hippocampus, and striatum) and in spleen were evaluated 2 and 8 h after endotoxin [lipopolysaccharide (LPS), 25 microg/rat i.c.v.], IFN gamma (2.5 microg/rat i.c.v.) or after their coadministration in rats. CSF and serum IL-1beta levels were increased by LPS alone and IFN gamma coadministration did not furtherly increase them. IFN gamma potentiated LPS effect on IL-6 and TNF alpha levels in both CSF and serum. LPS and IFN-gamma coadministration did not alter IL-1beta messenger RNA expression induced by LPS in brain areas and in spleen, but it potentiated that of IL-6 and TNF alpha. The present in vivo data show that i.c.v. coadministration of LPS and IFN gamma results in a potentiation of cytokine production (IL-6 and TNF alpha) which may trigger a cascade of events relevant to neurodegenerative processes. This action is independent of IL-1beta because the production of this cytokine is not altered by IFN gamma treatment.     

Different roles of brain interleukin 1 in the adrenocorticotropin response to central versus peripheral administration of lipopolysaccharide in the rat

Although it is well established that peripheral administration of endotoxin activates the hypothalamic-pituitary-adrenal (HPA) axis, information is very limited regarding whether central administration of endotoxin can similarly stimulate the endocrine axis. Moreover, it is also unknown whether a difference exists in the mode of involvement of brain-derived cytokines in determining the HPA response to peripheral vs central administration of endotoxin. In the present study, the authors attempted to gain more knowledge on these issues focusing on interleukin (IL) 1 in the brain, one of key pro-inflammatory cytokines mediating the immuno-endocrine network. In male rats, both intravenous (i.v., 100 micrograms/kg body weight) and intracerebroventricular [i.c.v. (the 3rd ventricle), 10 micrograms] injections of Escherichia coli lipopolysaccharide (LPS) caused a significant elevation of adrenocorticotropin (ACTH) levels in plasma, even though peaked ACTH responses occurred earlier after the i.v. (60 min post-injection) than the i.c.v. (120 min post-injection) LPS. Although the ACTH response to i.c.v. LPS was significantly suppressed by a prior (5 min) i.c.v. administration of IL-1 receptor antagonist (IL-1Ra, 1 microgram), the hormonal response to i.v. LPS was not. That this dose of IL-1Ra was not biologically a small dose was indicated by another experiment that the same dose of i.c.v. IL-1Ra was able to significantly suppress the ACTH response to an i.c.v. injection of recombinant human IL-1 beta (50 ng). These results suggest that i.c.v. LPS, as i.v. LPS, can stimulate ACTH secretion in the rat, and this hormonal response may, at least in part, be mediated by brain-derived IL-1. Although there is one previous study reporting an important role of central IL-1 in mediating the HPA response to systemic LPS treatment, our present data suggest that such a mechanism may not operate before and during an early, peak phase of ACTH secretion after i.v. LPS.     

Gastrodin and p-hydroxybenzyl alcohol facilitate memory consolidation and retrieval, but not acquisition, on the passive avoidance task in rats

This study evaluated synthetic trehalose dicorynomycolate (S-TDCM), an immunomodulator, for its survival enhancing capacity and behavioral toxicity in B6D2F1 female mice. In survival experiments, mice were administered S-TDCM (25-400 micrograms/mouse i.p.) 20-24 hr before 5.6 Gy mixed-field fission-neutron irradiation (n) and gamma-photon irradiation. The 30-day survival rates for mice treated with 100-400 micrograms/mouse S-TDCM were significantly enhanced compared to controls. Toxicity of S-TDCM was measured in nonirradiated mice by locomotor activity, food intake, water consumption, and alterations in body weight. A dose-dependent decrease was noted in all behavioral measures in mice treated with S-TDCM. Doses of 100 and 200 micrograms/mouse S-TDCM significantly reduced motor activity beginning 12 hr postinjection with recovery by 24 hr. A dose of 400 micrograms/mouse significantly decreased activity within the first 4 hr after administration and returned to control levels by 32 hr following injection. Food and water intake were significantly depressed at doses of 200 and 400 micrograms/mouse on the day following drug administration, and were recovered in 24 hr. Body weight was significantly decreased in the 200 micrograms/mouse group for 2 days and in the 400 micrograms/mouse group for 4 days following injection. A dose of 100 micrograms/mouse effectively enhanced survival after fission-neutron irradiation with no adverse effect on food consumption, water intake, or body weight and a minimal, short-term effect on locomotor activity.     

Mg2+ coordination in catalytic sites of F1-ATPase

Cytokines are hormone-like proteins which mediate and regulate inflammatory and immune responses. The purpose of this study was to investigate the effect of lipopolysaccharide (LPS) and inflammatory cytokines on regulation of interleukin-6 (IL-6) production by human gingival fibroblasts (HGF). The HGF cell lines used in this study, H-CL and F-CL, were established by the explant technique from healthy gingival tissue. Cultured cells were grown to confluency and incubated with various concentrations of LPS from Escherichia coli or Porphyromonas gingivalis or with the recombinant human cytokine tumor necrosis factor alpha (TNF-alpha), IL-1alpha, or IL-1beta. Culture supernatants were collected at various times and assessed for IL-6 production by enzyme-linked immunosorbent assay. Total RNA was isolated from the harvested cells and used to assess levels of IL-6 mRNA by the RNase protection assay. Both LPS preparations induced IL-6 production (1 to 4 ng of IL-6 per ml) by both HGF cell lines. Although TNF-alpha stimulated IL-6 production by HGF, > 10-fold-larger amounts were induced with IL-1alpha and IL-1beta. Furthermore, the addition of both IL-1alpha and TNF-alpha to cultured cells resulted in approximately 600- to 800-fold-higher levels of IL-6 than seen in control cultures, suggesting that these cytokines synergistically induced IL-6 production by HGF. IL-6 message in cultured cells was upregulated 20-fold by TNF-alpha, 1,000-fold by IL-1alpha and IL-1beta, and 1,400-fold by IL-1alpha plus TNF-alpha. IL-1alpha and TNF-alpha alone upregulate IL-6 production in a dose- and time-dependent fashion. The addition of IL-1alpha and TNF-alpha to cultured HGF cells resulted in a synergistic induction of IL-6 after 8 h of incubation and when greater than 10 pg of this combination per ml was used. Our studies show that inflammatory cytokines are hundreds of times more potent than LPS in stimulating IL-6 production by HGF.     

Sympatric mouse lemurs in north-west Madagascar: a new rufous mouse lemur species (Microcebus ravelobensis)

BACKGROUND: The sequential events in fever production after intravenous administration of lipopolysaccharide (LPS) remain unsettled and controversial. Vessels of the organum vasculosum laminae terminalis (OVLT) lack the tight junctions of the blood-brain barrier and allow substances of high molecular weight to enter the interstitium but not the neuropil. The present studies investigate the hypothesis that the OVLT is needed for fever production after intravenous administration of LPS in the rat. METHODS: Electrolytic lesions were produced in the OVLT of rats. After recovery, left carotid and right atrial catheters were inserted, and 24 hours later calorimetry was performed. Blood was drawn for baseline assay for cytokines and LPS after which LPS was given intravenously, with studies continued for 5 hours, and additional blood samples were drawn at 90 and 300 minutes. RESULTS: The maximal increment in rectal temperature for the sham lesion LPS group (1.25 +/- 0.44 degrees C) was significantly greater than for the sham-saline (-0.05 +/- 0.46 degrees C) and the lesion-LPS groups (0.35 +/- 0.45 degrees C) for minutes 120 to 300. Ninety minutes after LPS administration, serum levels of interleukin (IL)-6, tumor necrosis factor-alpha, and LPS were significantly elevated (p < 0.0001) above baseline for the sham-LPS and lesion-LPS groups. IL-1beta serum levels remained below detection levels. CONCLUSION: Large lesions of the OVLT prevent and/or attenuate fever due to LPS even though tumor necrosis factor-alpha and IL-6 are greatly increased in serum. IL-1beta does not seem to be an endogenous humoral mediator in this model.     

Cytokine mRNA levels in the hearts of inbred mice that develop different degrees of cardiomyopathy during infection with Trypanosoma cruzi

Profiles of cytokine mRNA expression were examined by semiquantitative RT-PCR in the hearts of DBA/2 (pathopermissive) and B10.D2 (pathoresistant) mice during infection with the Brazil strain of Trypanosoma cruzi. The levels and time-course profiles of IFNgamma, IL-1beta and IL-10 mRNA expression were similar in each strain. TNFalpha, iNOs, and IL-13 mRNA expression peaked at comparable levels and times after infection in each strain, but declined more rapidly in B10.D2 than in DBA/2 mice. Peak IL-2 mRNA levels were also similar between the two strains, but occurred earlier in DBA/2 than in B10.D2 mice. Levels of IL-4, IL-6 and IL-12 mRNA were significantly higher in DBA/2 than in B10.D2 mice from day 10 through day 50 of infection. With the exception of IL-1beta, which was expressed constitutively in both strains, the levels of mRNA of all other cytokines examined reached their peak no later than day 20 and declined significantly by day 50 after infection. The inflammatory infiltrate paralleled the latter cytokines; starting at day 10 in DBA/2 mice and at day 15 in the B10.D2 s, peaking between days 20 and 30 in both strains, decreasing to minimal levels by day 50 in the pathoresistant mice, but maintaining a mild amount through day 70 in the pathopermissive strain. The inflammation was composed mostly of lymphocytes and histiocytes throughout the entire process. These data demonstrate differences in the profiles of cytokine mRNA that may be related to the differential degree of cardiac pathology that develops in these two strains of mice upon infection with T. cruzi.     

Bladder instillation and intraperitoneal injection of Escherichia coli lipopolysaccharide up-regulate cytokines and iNOS in rat urinary bladder

Systemic bacterial lipopolysaccharides (LPS) induce inflammatory responses characteristic of sepsis. Instillation of LPS into rat bladder produces a localized inflammatory response similar to that seen in urinary tract infections (UTIs). Four hours after intravesical instillation of LPS, neutrophils infiltrate into the bladder, and mRNA for inducible nitric oxide synthase (iNOS) and the cytokines, interleukin (IL)-6 and IL-10, is detected in rat bladder but not in the kidney. Induction of iNOS protein is inferred because urinary nitrate and cGMP levels are increased 4 hr after LPS intravesical instillation and remain elevated for at least 24 hr. When LPS is injected intraperitoneally, iNOS and IL-6 mRNA are induced both in the bladder and in the kidney. These data are consistent with the effects of intravesical instillation of LPS remaining localized, iNOS activity increases in both particulate and soluble bladder fractions when measured 4 hr after intravesical instillation of LPS. The magnitude of these increases in iNOS activity in the bladder is not as great as when LPS is injected intraperitoneally. Intravesical instillation of LPS induces no increase in lung or kidney NOS activity. The localized inflammatory response produced by intravesical instillation of LPS demonstrates the importance of LPS as a mediator of the host response in UTIs and supports the use of urinary measurements of nitrate and cGMP in humans as indicative of the localized induction of iNOS in UTIs.     

Evidence for the persistence of monoclonal expansions of CD8+ T cells following primary simian immunodeficiency virus infection

We investigated in detail the effect of pegylated recombinant human megakaryocyte growth and development factor (PEG-rHuMGDF) on peripheral blood progenitor cell (PBPC) mobilization in male BDF1 mice. Treatment with PEG-rHuMGDF for 5 d stimulated a striking expansion of the circulating levels of multiple types of colony-forming units in culture (CFU-c), including CFU-granulocyte-macrophage, CFU-megakaryocyte, burst-forming units-erythroid, and multipotent CFU-c, and primitive day-12 CFU-spleen. All of these progenitors were mobilized into the peripheral blood (PB) with similar kinetics; their numbers peaked after the cessation of treatment and then declined earlier than platelet numbers peaked. The maximal increase in any of the four CFU-c in the PB was attained with at least 300 microg/kg/d of PEG-rHuMGDF, whereas peripheral platelet counts plateaued at 30 microg/kg/d. Adoptive transfer with PB from PEG-rHuMGDF-treated donor mice resulted in greater survival of lethally irradiated recipients. The majority of the recipients that survived at 187 d after transplantation with PEG-rHuMGDF-mobilized PB showed significant donor engraftment at the progenitor cell level. The combined administration of appropriate doses of PEG-rHuMGDF and recombinant human granulocyte colony-stimulating factor induced a synergistic increase in the circulating levels of the four CFU-c compared to either factor alone. These results indicate that PEG-rHuMGDF as a single agent can mobilize a full spectrum of PBPCs in mice.     

The swine as a model for studying exercise-induced changes in lipid metabolism

The function of cytokines produced during Hymenolepis nana egg infection in mice in protective immunity against re-infection was examined. Treatment of mice with monoclonal antibody (MAb) against mouse interferon (IFN)-gamma caused suppression of protective immunity against H. nana re-infection when the MAb was injected intraperitoneally at a daily dose of 40.0 mg kg-1 during the effector phase of protective immunity. Although high levels of IFN-gamma, tumor necrosis factor (TNF)-alpha and interleukin (IL)-1 beta were released into the intestinal tracts of the parasitised mice at challenge infection, there was almost no release of these cytokines in mice treated with the MAb. Daily administration of rolipram failed to suppress the protective immunity, even when 400 micrograms kg-1 of the agent was administered into mice during the effector phase of immunity. Treatment of mice with rolipram completely suppressed both TNF-alpha and IL-1 beta production in intestinal tracts, induced by H. nana challenge infection. However, endogenous IFN-gamma production in the intestine was scarcely affected by rolipram. These results strongly suggest that IFN-gamma is the most important (or essential) cytokine in protective immunity to H. nana re-infection, rather than TNF-alpha and IL-1 beta.     

Inhibition of IL-10 expression by IFN-gamma up-regulates transcription of TNF-alpha in human monocytes

Stimulation of human monocytes with LPS induces expression of multiple cytokines, including TNF-alpha, IL-1 beta, IL-6, and IL-10, IL-10 expression is delayed relative to that of TNF-alpha, IL-1 beta, and IL-6. Furthermore, IL-10 feedback inhibits expression of TNF-alpha, IL-1 beta, and IL-6, thus providing an efficient autocrine mechanism for controlling proinflammatory cytokine production in monocytes. The Th1-type lymphokine, IFN-gamma, markedly up-regulates TNF-alpha production in monocytes. However, the precise mechanism by which IFN-gamma mediates this effect is unknown. We examined the effects of IFN-gamma on IL-10 expression in LPS-stimulated monocytes, and the relationship between IL-10 and TNF-alpha production in these cells. LPS stimulation induced rapid, ordered expression of multiple cytokines. Steady-state mRNA levels for TNF-alpha increased rapidly, reached maximal levels by 2 to 3 h poststimulation, and then declined sharply. IL-1 beta and IL-6 mRNA levels also increased markedly following stimulation with LPS, but decreased more slowly than did TNF-alpha. Down-regulation of mRNA for TNF-alpha, IL-1 beta, and IL-6 coincided with a delayed and more gradual increase in IL-10 mRNA levels. Furthermore, neutralization of IL-10 with anti-IL-10 Abs prolonged TNF-alpha mRNA expression, and significantly increased net TNF-alpha production. IFN-gamma suppressed expression of IL-10 mRNA and protein in a dose-dependent manner. Moreover, inhibition of IL-10 production correlated with a marked increase in both the magnitude and duration of TNF-alpha expression. Thus, potentiation of TNF-alpha production by IFN-gamma in monocytes is coupled to inhibition of endogenous IL-10 expression.     

Production of inflammatory mediators by human macrophages obtained from ascites

Ascites is a readily available source of human macrophages (M phi), which can be used to study M phi functions in vitro. We characterized the mediators of inflammation produced by human peritoneal M phi (hp-M phi) obtained from patients with portal hypertension and ascites. The production of the cytokines interleukin-1 beta (IL-1 beta), interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-alpha) was found to be lipopolysaccharide (LPS) concentration dependent (0-10 micrograms/ml) with a maximal production at 10 micrograms/ml and also dependent on the time of exposure to the stimulus (0-36 h). IL-1 beta, IL-6 and TNF-alpha production after LPS administration reached a plateau at 24 h. In vitro stimulation for 24 h with LPS does not influence the eicosanoid production from endogenous arachidonate. 13 min of exposure of the cells to the calcium ionophore A23187 gives a significant increase in eicosanoid production from both exogenous and endogenous arachidonate. The main eicosanoids produced are the 5-lipoxgenase products LTB4 and 5-hydroxyeicosatetraenoic acid (HETE). The increase in production of the other eicosanoids is not significant. The eicosanoid production depends on the stimulus concentration. The optimal A23187 concentration is 1 microM. Oxygen radical production was measured in the M phi by a flowcytometric method. The fluorescence intensity of phorbol 12-myristate 13-acetate stimulated and dihydro-rhodamine 123 loaded hp-M phi increases significantly after 15 min. We conclude that LPS stimulation of hp-M phi from liver disease results in similar production of IL-1 beta, IL-6 and TNF-alpha, but that the profile of the eicosanoid production of these M phi stimulated with LPS and A23187 differs from M phi of other origin and species.     

Shift from anti- to proinflammatory cytokine profiles in microglia through LPS- or IFN-gamma-mediated pathways

In this study, cytokine mRNA profiles in microglia from newborn rats were detected by in situ hybridization. Under natural culture conditions, microglia expressed the immunosuppressive transforming growth factor-beta 1 (TGF-beta 1) and interleukin (IL) 10 to a greater degree than the pro-inflammatory cytokines IL-1 beta, IL-6, IL-12, interferon-gamma (IFN-gamma) and TNF-alpha. High TGF-beta 1 and IL-10 levels could reflect one mechanism for immune privilege within the CNS under physiological conditions. Stimulation of microglia with LPS or IFN gamma resulted in strong up-regulation of proinflammatory cytokines, while TGF-beta 1 and IL-10 were down-regulated. These effects of LPS or IFN-gamma are anticipated to reflect immunopathogenic processes within the CNS.     

Time course of increased plasma cytokines, cortisol, and urea nitrogen in pigs following intraperitoneal injection of lipopolysaccharide

The emerging view is that reduced feed intake, lean muscle accretion, and growth in immunologically challenged pigs is the result of increased cytokine activity, but this has not been directly tested. To begin addressing this issue, 72 crossbred barrows and gilts (11.55 +/- .19 kg BW) were not fed for 12 h and then injected i.p. with 0, .5, or 5 micrograms/kg of Escherichia coli lipopolysaccharide (LPS). Blood was collected by jugular puncture at 0, 2, 4, 8, 12, and 24 h after injection. Plasma levels of tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6), cortisol, plasma urea nitrogen (PUN), NEFA, and triglycerides were determined. Immunological stress was induced by LPS as indicated by increased secretion of TNF-alpha, IL-6, and cortisol. In pigs receiving 5 micrograms/kg of LPS, plasma TNF-alpha was increased 10-fold at 2 h after injection and was still elevated (P < .01) at 4 h. In these same pigs, plasma concentration of IL-6 was increased at 2 h and peaked at 4 h with levels exceeding baseline values by 200-fold (P < .01). Cortisol was elevated at 2, 4, and 8 h after injection (P < .01). The increased secretion of cytokines and cortisol in pigs injected with 5 micrograms/kg of LPS was followed by an increase in protein degradation, as evidenced by PUN values that were increased two- and threefold at 8 and 12 h after injection, respectively. However, unlike previous reports in laboratory animal species, plasma glucose, NEFA, and triglycerides were not altered by LPS. Nonetheless, as the period of feed deprivation progressed from 12 to 36 h, plasma NEFA and triglycerides increased (P < .05) and plasma glucose tended to decrease. We believe that immunological challenge induces cytokine synthesis and secretion in swine which, in turn, may induce protein catabolism.     

Enhanced toxicity for mice of combinations of bacterial lipopolysaccharide and vincristine

Sublethal doses of vincristine (VNC) and bacterial lipopolysaccharide (LPS) administered simultaneously to adult male mice resulted in markedly enhanced mortality. All of 10 strains of Pseudomonas aeruginosa tested, 4 of 7 strains of Bacteroides, and 6 of 10 strains of Listeria monocytogenes were able to substitute for purified LPS in enhancing mortality in VNC-treated mice. Inoculation of mice with each of 10 strains of Pseudomonas, each of 7 strains of Bacteroides, and about half of the 10 strains of Listeria tested elicited increased resistance to the lethal action of purified LPS. The patterns of responses of mice receiving a lethal combination of 2 mg of LPS/kg and 1 mg of VNC/kg resembled those of mice receiving a lethal dose of 10 mg of VNC/kg alone or 15 mg of LPS/kg alone with respect to (i) serum glutamic pyruvate transaminase activity, (ii) hematocrit values, and (iii) thrombocytopenia. The patterns of responses of mice receiving a lethal combination of LPS and VNC resembled those of mice receiving a lethal dose of LPS alone with respect to (i) hypothermia, (ii) retention of sulfobromophthalein, (iii) fibrinogen level, (iv) prothrombin activity, (v) blood urea nitrogen levels, and (vi) time of death. These data are consistent with the proposition that the combination of VNC and LPS produces a fatal renal failure. Histological studies confirmed that there was extensive renal damage in mice treated with lethal doses of LPS alone or a lethal combination of LPS and VNC.