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C Galanos

Publications and source records attributed to C Galanos.

At least 19 recordsLinked to original sources
PubMed2004

Infection of C57BL/10ScCr and C57BL/10ScNCr mice with Leishmania major reveals a role for Toll-like receptor 4 in the control of parasite replication.

The innate immune system is essential for host defense; it senses the presence of potentially pathogenic-invading microorganisms, and the contribution of Toll-like receptors (TLRs) to this response is increasingly recognized. In the present study, we investigated the contribution of TLR4 to the course of cutaneous leishmaniasis in vivo. We used C57BL/10ScNCr (TLR4(0/0)) and C57BL/10ScCr [TLR4/interleukin-12 (IL-12)Rbeta2(0/0)] mice and compared the course of Leishmania major infection, parasite load, cell recruitment, and cytokine profile with those of wild-type C57BL/10ScSn mice. Our results confirm the importance of IL-12 receptor-mediated signaling in resistance to L. major infections. Importantly, we show that the lack of TLR4 results in an increased permissiveness for parasite growth during the innate and adaptive phase of the immune response and in delayed healing of the cutaneous lesions. The use of the tlr4 transgenic mouse strain TCr5 demonstrated unequivocally that TLR4 contributes to the efficient control of Leishmania growth in vivo.

Animals↗
PubMed2001

A point mutation in the IL-12R beta 2 gene underlies the IL-12 unresponsiveness of Lps-defective C57BL/10ScCr mice.

Lps-defective C57BL/10ScCr (Cr) mice are homozygous for a deletion encompassing Toll-like receptor 4 that makes them refractory to the biological activity of LPS. In addition, these mice exhibit an inherited IL-12 unresponsiveness resulting in impaired IFN-gamma responses to different microorganisms. By positional cloning methods, we show here that this second defect of Cr mice is due to a mutation in a single gene located on mouse chromosome 6, in close proximity to the Igkappa locus. The gene is IL-12Rbeta2. Cr mice carry a point mutation creating a stop codon that is predicted to cause premature termination of the translated IL-12Rbeta2 after a lysine residue at position 777. The truncated beta2 chain can still form a heterodimeric IL-12R that allows phosphorylation of Janus kinase 2, but, unlike the wild-type IL-12R, can no longer mediate phosphorylation of STAT4. Because the phosphorylation of STAT4 is a prerequisite for the IL-12-mediated induction of IFN-gamma, its absence in Cr mice is responsible for their defective IFN-gamma response to microorganisms.

Animals↗
PubMed2001

Inherited IL-12 unresponsiveness contributes to the high LPS resistance of the Lps(d) C57BL/10ScCr mouse.

LPS(d) mouse strains are characterized by the presence of a defective LPS/tlr4 gene that make them refractory to the biological activity of LPS. One of the mouse strains commonly used to study LPS defects is the C57BL/10ScCr (Cr) strain. However, unlike other LPS(d) strains, the Cr strain also has a heavily impaired IFN-gamma response to micro-organisms. As a consequence, unlike other LPS(d) mouse strains, they do not acquire a partial LPS susceptibility when treated with sensitizing bacteria. Because IL-12 is important for the microbial induction of IFN-gamma, we investigated whether the production or function of IL-12 might be defective in Cr mice. IL-12 mRNA (p35 and p40) was present in the spleen of untreated Cr mice, IL-12p40 mRNA was inducible in mice injected with live or killed Salmonella typhimurium, and IL-12 (p70) was inducible in macrophages by bacteria. Thus, Cr mice exhibit normal IL-12 responses. In functional tests, splenocytes of untreated or of S. typhimurium-infected mice failed to produce IFN-gamma when stimulated with murine rIL-12 or with a combination of IL-12 and murine rIL-18 or Con A. Furthermore, Cr mice were identical with IL-12p35/p40 and IL-12 receptor beta(1) knockout mice in their impaired in vivo and in vitro IFN-gamma responses to bacteria. Thus, Cr mice carry a second genetic defect unrelated to the Lps/tlr4 mutation that underlies the IL-12 unresponsiveness and contributes to the LPS resistance and impaired innate immune response in this strain.

Animals↗
PubMed2001

TNF-alpha hyper-responses to Gram-negative and Gram-positive bacteria in Propionibacterium acnes primed or Salmonella typhimurium infected mice.

IFN-gamma-dependent hypersensitivity to LPS is inducible in mice by infection or pre-treatment with killed bacteria. Hypersensitive mice exhibit enhanced inflammatory responses to LPS, including the overproduction of TNF-alpha. Using Lps(n) BALB/c and Lps(d) BALB/c/l mice, primed with Propionibacterium acnes or infected with Salmonella typhimurium, we show that concurrently to hypersensitivity to LPS, a hypersensitivity to other constituents of killed Gram-negative or Gram-positive bacteria and to staphylococcal enterotoxin B (SEB) develops. The TNF-alpha hyper-responses in sensitized mice induced by different Gram-positive bacteria, are generally weaker than those by Gram-negative bacteria and vary significantly, due to the absence of a common, LPS-equivalent component. Using IFN-gamma R(-/-) and the respective wild-type mice, we demonstrate that although sensitization to LPS and killed Listeria monocytogenes is exclusively IFN-gamma-dependent, an IFN-gamma-independent, moderate sensitization to certain TNF-alpha-inducing constituents in bacteria may develop in parallel.

Animals↗
PubMed2001

Differential clearance and induction of host responses by various administered or released lipopolysaccharides.

The clearance and activity of different types of lipopolysaccharide (LPS) released during infection with Gram-negative bacteria were investigated. When highly purified preparations differing in their specific endotoxin activity were administered intravenously to mice, the clearance of rough (R)-form LPS preparations from Salmonella minnesota and Escherichia coli was much faster than that of a smooth (S)-form LPS preparation from Salmonella abortus equi, but slower than that of lipo-oligosaccharides (LOS) preparations from Bordetella pertussis and Helicobacter pylori. After intraperitoneal infection with 10(7) and 10(8) CFU E. coli O111:B4, relatively high levels of LPS were detected dose-dependently in the plasma of infected mice and persisted for a long time. In addition, plasma sCD14 levels in infected mice were higher than in LPS-administered mice. These results indicate that continuously higher levels of plasma LPS followed by stronger host responses occur during infection and suggest that these differences between LPS-administered and infected mice should be taken into consideration when analyzing host responses induced by LPS.

Animals↗
PubMed2000

Bacterial induction of beta interferon in mice is a function of the lipopolysaccharide component.

We investigated the reason for the inability of lipopolysaccharide (LPS)-resistant (Lps-defective [Lps(d)]) C57BL/10ScCr mice to produce beta interferon (IFN-beta) when stimulated with bacteria. For this purpose, the IFN-beta and other macrophage cytokine responses induced by LPS and several killed gram-negative and gram-positive bacteria in LPS-sensitive (Lps-normal [Lps(n)]; C57BL/10ScSn and BALB/c) and Lps(d) (C57BL/10ScCr and BALB/c/l) mice in vitro and in vivo were investigated on the mRNA and protein levels. In addition, double-stranded RNA (dsRNA) was used as a nonbacterial stimulus. LPS and all gram-negative bacteria employed induced IFN-beta in the Lps(n) mice but not in the Lps(d) mice. All gram-positive bacteria tested failed to induce significant amounts of IFN-beta in all four of the mouse strains used. As expected, all other cytokines tested (tumor necrosis factor alpha, interleukin 1alpha [IL-1alpha], IL-6, and IL-10) were differentially induced by gram-negative and gram-positive bacteria. Stimulation with dsRNA induced IFN-beta and all other cytokines mentioned above in all mouse strains, regardless of their LPS sensitivities. The results suggest strongly that LPS is the only bacterial component capable of inducing IFN-beta in significant amounts that are readily detectable under the conditions used in this study. Consequently, in mice, IFN-beta is inducible only by gram-negative bacteria, but not in C57BL/10ScCr or other LPS-resistant mice.

Animals↗
PubMed2000

Dose-dependent effects of endotoxin on human sleep.

The role of the central nervous system in the host response to infection and inflammation and modulation of these responses by the hypothalamic-pituitary-adrenal system are well established. In animals, activation of host defense mechanisms increases non-rapid eye movement (NREM) sleep amount and intensity, which, in turn, are thought to support host defense, or the body's ability to defend itself against challenges to its immune system. In humans, the evidence is conflicting. Therefore, we investigated the effects of three placebo-controlled doses of endotoxin on host response, including nocturnal sleep in healthy volunteers. Administered before nocturnal sleep onset, endotoxin dose dependently increased rectal temperature, heart rate, and the plasma levels of tumor necrosis factor (TNF)-alpha, soluble TNF receptors, interleukin (IL)-1 receptor antagonist, IL-6, and cortisol. The lowest dose reliably increased circulating levels of cytokines and soluble cytokine receptors, but it did not affect rectal temperature, heart rate, or cortisol. This subtle host defense activation increased deep NREM sleep amount, often referred to as slow-wave sleep (stages 3 and 4), and intensity (delta power). Conversely, the highest dose of endotoxin disrupted sleep. Whereas it is well established that the endocrine and thermoregulatory systems are very sensitive to endotoxin, this study shows that human sleep-wake behavior is even more sensitive to activation of host defense mechanisms.

Adult↗
PubMed2000

Changes in dehydroepiandrosterone (DHEA) and DHEA-sulfate plasma levels during experimental endotoxinemia in healthy volunteers.

Dehydroepiandrosterone (DHEA) and DHEA-sulfate (DHEA-S) have immunomodulatory effects in vitro and in vivo. Additionally, their plasma levels are altered during chronic infection and inflammation. However, it remains unknown whether these steroids are involved in early host responses to infection in humans. We examined DHEA and DHEA-S levels during experimental endotoxinemia, a well established pathophysiological model of bacterial infections in humans. Purified Salmonella abortus equi endotoxin (0.2, 0.4, or 0.8 ng/kg body weight) was injected in a single-blind, placebo-controlled experiment to 17 healthy male volunteers. During the following 12 h, rectal temperature and the plasma levels of ACTH, cortisol, DHEA, DHEA-S, interleukin 6, and tumor necrosis factor alpha were determined. Confirming earlier studies, temperature and cytokine levels showed monophasic, dose-dependent increases in response to endotoxin. In contrast, endocrinological effects of endotoxin showed a complex, biphasic pattern: cortisol levels were not affected by 0. 2 ng/kg but significantly increased during the first 6 h following 0. 4 and 0.8 ng/kg endotoxin, whereas ACTH and DHEA levels were significantly enhanced during the first 6 h following 0.8 ng/kg only. ACTH, DHEA, and cortisol secretion was blunted 6-12 h following 0.8 ng/kg. DHEA-S levels were unaffected during the first 6 h following all dosages, but between 6-12 h after injection they were significantly increased following 0.2 ng/kg, unaffected by 0.4 ng/kg, and significantly decreased following 0.8 ng/kg endotoxin. The present results suggest that similarly to glucocorticoids, the adrenal androgens DHEA and DHEA-S play an important role during early host responses to bacterial infections in humans.

Acetone↗
PubMed2000

MALP-2, a Mycoplasma lipopeptide with classical endotoxic properties: end of an era of LPS monopoly?

Although some activities of LPS are shared by other bacterial components, for half a century LPS has been regarded as unique in displaying many pathophysiological activities. Here we report on a synthetic lipopeptide, MALP-2 from Mycoplasma fermentans, which expresses potent endotoxin-like activity and whose lethal toxicity is comparable to that of LPS. With the exception of the Limulus lysate gelation test, in which MALP-2 was approximately 1000-fold less active than LPS, the synthetic lipopeptide induced all activities tested for, and in most cases to an extent comparable to that of LPS. Unlike LPS, the biological activities of MALP-2 were expressed both in LPS-responder and in LPS-non-responder mice (BALB/c/l, C57BL10/ScCr), indicating that MALP-2 signaling, unlike that of LPS, is not transduced via the Toll-like receptor (Tlr) 4 protein.MALP-2 expressed no toxicity in normal or sensitized Tlr2 knockout (Tlr2(-/-)) mice indicating that its toxic activity is induced via Tlr2 signaling. The phenomenology of the lethal shock induced by MALP-2 in normal or sensitized mice, i.e. the kinetics of its development and symptoms of illness exhibited by the treated animals, was very reminiscent of the lethal shock induced by LPS.

Animals↗
PubMed1999

The occurrence of 4-amino-4-deoxy-arabinose in LPS of supersusceptible strain Pseudomonas aeruginosa Z61: noncorrelation with polymyxin resistance.

Lipopolysaccharides (LPS) extracted from the supersusceptible strain Pseudomonas aeruginosa Z61 were compared with LPS from other strains with varying antimicrobial susceptibilities. The presence of 4-amino-4-deoxy-arabinose (4-AraN) in P. aeruginosa Z61 LPS was confirmed by gas-liquid chromatography/mass spectrometry (GLC-MS) and quantitated by high-performance liquid chromatography (HPLC). Z61 LPS (compared with wild-type strain PAO1) has reduced amounts of rhamnose and higher concentrations of hydroxy fatty acids, 4-AraN, and phosphates. 31P Nuclear magnetic resonance revealed that Z61 LPS phosphates are configured in monophosphates, phosphodiesters, pyrophosphomonoesters, and glycosidic pyrophosphodiester groups. The presence of 4-AraN in P. aeruginosa LPS did not correlate with antimicrobial resistance.

Amino Sugars↗
PubMed1999

Dose-dependence of bacterial lipopolysaccharide (LPS) effects on peak response and time course of the immune-endocrine host response in humans.

OBJECTIVE AND DESIGN: Dose-dependence of lipopolysaccharide (LPS) effects on peak and time course parameters of the immune-endocrine host response was examined in a placebo-controlled design. SUBJECTS: Data from 42 male volunteers were included. TREATMENT: 0.4 or 0.8 ng LPS/kg body weight were applied at 7.00 p.m. METHODS: Body temperature, heart rate and leukocyte counts were quantified. Plasma levels of tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6), adrenocorticotropic hormone (ACTH), cortisol and human growth hormone (hGH) were measured. RESULTS: LPS increased significantly the levels of immune (TNF-alpha, IL-6) and endocrine (ACTH, cortisol) parameters. HGH secretion was advanced without changes in the total amount of hGH released. Dose-dependence of endotoxin's effects was significant for neuroendocrine (cortisol) and physiological (temperature, heart rate) parameters. Examination of time course parameters demonstrated that the higher dose of endotoxin prolonged the increases in temperature, IL-6 and cortisol levels. CONCLUSIONS: Our data show that increases in the dosage of LPS lead to differential peak responses and changed time course patterns of the human host response.

Adrenocorticotropic Hormone↗
PubMed1999

Lactoferrin-lipid A-lipopolysaccharide interaction: inhibition by anti-human lactoferrin monoclonal antibody AGM 10.14.

Lactoferrin (LF) is a glycoprotein that exerts both bacteriostatic and bactericidal activities. The interaction of LF with lipopolysaccharide (LPS) of gram-negative bacteria seems to play a crucial role in the bactericidal effect. In this study, we evaluated, by means of an enzyme-linked immunosorbent assay, the binding of biotinylated LF to the S (smooth) and R (rough) (Ra, Rb, Rc, Rd1, Rd2, and Re) forms of LPS and different lipid A preparations. In addition, the effects of two monoclonal antibodies (AGM 10.14, an immunoglobulin G1 [IgG1] antibody, and AGM 2.29, an IgG2b antibody), directed against spatially distant epitopes of human LF, on the LF-lipid A or LF-LPS interaction were evaluated. The results showed that biotinylated LF specifically binds to solid-phase lipid A, as this interaction was prevented in a dose-dependent fashion by either soluble uncoupled LF or lipid A. The binding of LF to S-form LPS was markedly weaker than that to lipid A. Moreover, the rate of LF binding to R-form LPS was inversely related to core length. The results suggest that the polysaccharide O chain as well as oligosaccharide core structures may interfere with the LF-lipid A interaction. In addition, we found that soluble lipid A also inhibited LF binding to immobilized LPS, demonstrating that, in the whole LPS structure, the lipid A region contains the major determinant recognized by LF. AGM 10.14 inhibited LF binding to lipid A and LPS in a dose-dependent fashion, indicating that this monoclonal antibody recognizes an epitope involved in the binding of LF to lipid A or some epitope in its close vicinity. In contrast, AGM 2.29, even in a molar excess, did not prevent the binding of LF to lipid A or LPS. Therefore, AGM 10.14 may represent a useful tool for neutralizing selectively the binding of LF to lipid A. In addition, the use of such a monoclonal antibody could allow better elucidation of the consequences of the LF-lipid A interaction.

Animals↗
PubMed1998

Defective LPS signaling in C3H/HeJ and C57BL/10ScCr mice: mutations in Tlr4 gene.

Mutations of the gene Lps selectively impede lipopolysaccharide (LPS) signal transduction in C3H/HeJ and C57BL/10ScCr mice, rendering them resistant to endotoxin yet highly susceptible to Gram-negative infection. The codominant Lpsd allele of C3H/HeJ mice was shown to correspond to a missense mutation in the third exon of the Toll-like receptor-4 gene (Tlr4), predicted to replace proline with histidine at position 712 of the polypeptide chain. C57BL/10ScCr mice are homozygous for a null mutation of Tlr4. Thus, the mammalian Tlr4 protein has been adapted primarily to subserve the recognition of LPS and presumably transduces the LPS signal across the plasma membrane. Destructive mutations of Tlr4 predispose to the development of Gram-negative sepsis, leaving most aspects of immune function intact.

Amino Acid Sequence↗
PubMed1998

Endotoxin-induced changes in sleep and sleepiness during the day.

Sleepiness is a common symptom of infectious diseases. However, the peculiarities and causes of impaired vigilance during host defense activation are largely unknown. It has been shown earlier that mild host defense activation by endotoxin does not affect daytime sleepiness and non-rapid eye movement (NREM) sleep in humans. In the present study we investigated the effects of a more intensive stimulation of the host defense by Salmonella abortus equi endotoxin (0.8 ng/kg), administered 12 h following host response priming by granulocyte colony-stimulating factor (300 micrograms s.c.), on daytime sleep and sleepiness in a placebo-controlled design in ten healthy men. Six equidistant polysomnographically monitored naps were scheduled across the day and the time course of subjective sleepiness was assessed. Endotoxin induced prominent increases in rectal temperature, and in the plasma levels of tumor necrosis factor-alpha, interleukin-6, interleukin-1 receptor antagonist, and cortisol. In the first nap, 1 h following endotoxin administration, total sleep time and NREM sleep stage 2 were reduced, whereas wakefulness and sleep onset latency were increased. Following this nap sleepiness transiently increased peaking prior to the second nap. However, this nap and the following ones were not influenced by endotoxin. These results suggest that prominent host defense activation reduces daytime NREM sleep and increases sleepiness. One cause of daytime sleepiness during infections may be prior sleep disruption and this kind of sleepiness may not necessarily be associated with an increased sleep pressure.

Adult↗
PubMed1998

[Effect of adenosine on intravascular accumulation of leukocytes and tissue damage in striated muscle in endotoxemia].

Under the experimental conditions of endotoxinemia, the therapeutic use of an intravenous infusion of adenosine (110 micrograms x kg-1 x min-1) has been investigated in the microcirculation model of the BALB/c mouse. Injection of S. abortus-equi endotoxin (2 mg x kg-1 body wt. i.v.) elicited a significant increase of sticking leukocytes in postcapillary venules of striated skin muscle, which was associated with a swelling of microvascular endothelium and striated skin muscle. Infusion of adenosine effectively attenuated the endotoxin induced enhancement of leukocyte sticking and preserved microvascular endothelial and striated muscle integrity. These results imply the use of adenosine as therapeutic concept during endotoxinemia.

Adenosine↗
PubMed1997

Downregulation of the proinflammatory cytokine response to endotoxin by pretreatment with the nontoxic lipid A analog SDZ MRL 953 in cancer patients.

Interfering with the endotoxin-mediated cytokine cascade is thought to be a promising approach to prevent septic complications in gram-negative infections. The synthetic lipid A analog SDZ MRL 953 has been shown to be protective against endotoxic shock and bacterial infection in preclinical in vivo models. As part of a trial of unspecific immunostimulation in cancer patients, we conducted a double-blind, randomized, vehicle-controlled phase I trial of SDZ MRL 953 to investigate, first, its biologic effects and safety of administration in humans and, second, its influence on reactions to a subsequent challenge of endotoxin (Salmonella abortus equi). Twenty patients were treated intravenously with escalating doses of SDZ MRL 953 or vehicle control, followed by an intravenous application of endotoxin (2 ng/kg of body weight [BW]). Administration of SDZ MRL 953 was safe and well-tolerated. SDZ MRL 953 itself increased granulocyte counts and serum levels of granulocyte colony-stimulating factor (G-CSF) and interleukin-6 (IL-6), but not of the proinflammatory cytokines tumor necrosis factor-alpha (TNF-alpha), IL-1beta, and IL-8. Compared with vehicle control, pretreatment with SDZ MRL 953 markedly reduced the release of TNF-alpha, IL-1beta, IL-8, IL-6, and G-CSF, but augmented the increase in granulocyte counts to endotoxin. Induction of tolerance to the endotoxin-mediated cascade of proinflammatory cytokines by pretreatment with SDZ MRL 953 in patients at risk may help to prevent complications of gram-negative sepsis.

Adjuvants, Immunologic↗
PubMed1997

Leishmania major infection in C57BL/10 mice differing at the Lps locus: a new non-healing phenotype.

The course of cutaneous leishmaniasis was examined in mice from two genetically closely related strains, C57BL/10ScCr (Cr) and C57BL/10ScSn (Sn). Sn mice are able to heal Leishmania major infections, while Cr mice are unable to heal. The cutaneous lesions of the Cr mice progressed continuously and the increase in lesion size was paralleled by an unrestricted growth of the parasites in vivo. Cr mice, in contrast to their Sn counterparts, are highly resistant to all effects of lipopolysaccharide (LPS). The nonhealing L. major infection in Cr mice is in sharp contrast to the course of infection in another endotoxin-nonresponder mouse strain, C3H/HeJ, which heal infections with L. major. Cr mice exhibit, in addition to the defective LPS responsiveness, an impaired interferon-gamma (IFN-gamma) response after infection with a variety of microorganisms. The insufficient activation of parasitized macrophages to kill intracellular L. major could be due to the inability of splenocytes from infected Cr mice to secrete IFN-gamma upon restimulation with L. major. IFN-gamma is essential for the efficient activation of parasitized macrophages to kill intracellular L. major by producing nitric oxide (NO). Although bone marrow-derived Cr macrophage do not produce NO in response to LPS, both Sn and Cr macrophages release NO upon stimulation with IFN-gamma and tumor necrosis factor, indicating that they are responsive to activation by these cytokines.

Animals↗