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1.
J Allergy Clin Immunol ; 108(6): 908-14, 2001 Dec.
Article in English | MEDLINE | ID: mdl-11742266

ABSTRACT

BACKGROUND: The relationship between severity of asthma and bronchial inflammation is poorly understood. OBJECTIVE: We examined acute and subacute inflammatory responses to allergen in subjects with mild and moderate persistent asthma to evaluate whether different cellular and mediator responses to endobronchial allergen challenge are associated with differences in disease severity. METHODS: Segmental allergen challenge was performed in 8 subjects with mild and 10 subjects with moderate allergic asthma to compare baseline airways inflammation and allergen-induced inflammatory responses 24 hours later. This evaluation was repeated after 6 weeks in 9 subjects to investigate the reproducibility of these inflammatory responses. RESULTS: Subjects with mild and moderate asthma had similar decreases in FEV(1) in response to segmental allergen challenge (9.1% +/- 4.2% vs 15.1% +/- 4.6%, P = .35). There was no difference in inflammatory cell counts or cytokine concentrations in the groups with mild and moderate asthma at baseline or after saline or allergen challenge. Repeat segmental allergen challenge 6 weeks later showed that these cellular and cytokine responses were reproducible. CONCLUSION: Segmental allergen challenge in subjects with mild and moderate asthma produces similar allergen-specific physiologic and inflammatory responses that are reproducible 6 weeks later. In this model of allergic asthma, acute responses to allergen do not appear to be related to disease severity.


Subject(s)
Allergens/immunology , Asthma/immunology , Inflammation/etiology , Adult , Asthma/physiopathology , Bronchoalveolar Lavage Fluid/immunology , Female , Forced Expiratory Volume , Humans , Male , Reproducibility of Results , Vital Capacity
2.
J Interferon Cytokine Res ; 21(7): 485-94, 2001 Jul.
Article in English | MEDLINE | ID: mdl-11506742

ABSTRACT

Interleukin-1 (IL-1) plays an important role in host defenses against microbial pathogens. Excessive production of this cytokine, however, may be responsible in part for the lethality observed during sepsis. Our studies show that interferon-gamma (IFN-gamma) downregulates lipopolysaccharide (LPS)-induced interleukin-1beta (IL-1beta) transcription in primary macrophages. This phenomenon does not occur in splenocytes or bone marrow-derived macrophages from signal transducer and activator of transcription (Stat1)-deficient mice, suggesting that Stat1, a transcription factor involved in IFN signaling, plays a critical role in this process. Moreover, nitric oxide (NO) was also involved in the downregulation of LPS-induced IL-1 by IFN, as addition of the inducible nitric oxide synthase (iNOS) inhibitor L-N(6)-(1-iminoethyl)lysine (NIL) negated the effect. Kinetic analysis of IL-1 and IFN levels in LPS-treated mice in vivo suggests that IFN-mediated inhibition of IL-1 might be an important negative feedback mechanism for limiting IL-1 generation in vivo.


Subject(s)
DNA-Binding Proteins/physiology , Interferon-gamma/physiology , Interleukin-1/antagonists & inhibitors , Lipopolysaccharides/antagonists & inhibitors , Macrophages/immunology , Signal Transduction/immunology , Trans-Activators/physiology , Animals , Cell Line , Down-Regulation/genetics , Down-Regulation/immunology , Female , Injections, Intraperitoneal , Interferon-gamma/biosynthesis , Interleukin-1/genetics , Kinetics , Lipopolysaccharides/administration & dosage , Lipopolysaccharides/pharmacology , Macrophages/drug effects , Mice , Mice, Inbred C3H , Nitric Oxide/physiology , RNA, Messenger/antagonists & inhibitors , STAT1 Transcription Factor , Transcription, Genetic/immunology
3.
Infect Immun ; 69(6): 3906-15, 2001 Jun.
Article in English | MEDLINE | ID: mdl-11349058

ABSTRACT

We previously observed that Ureaplasma urealyticum respiratory tract colonization in infants with a birth weight of < or =1,250 g was associated with increases in the tracheal aspirate proinflammatory cytokines tumor necrosis factor alpha (TNF-alpha) and interleukin-8 (IL-8) relative to the counterregulatory cytokine IL-6 during the first week of life (A. M. Patterson, V. Taciak, J. Lovchik, R. E. Fox, A. B. Campbell, and R. M. Viscardi, Pediatr. Infect. Dis. J. 17:321-328, 1998). We hypothesized that U. urealyticum alters the host immune response in the presence of a coinflammatory stimulus (e.g., bacterial infection or hyperoxia) by shifting the balance of cytokine expression towards the proinflammatory cytokines. To test this hypothesis, we compared the release of TNF-alpha, IL-8, IL-6, and IL-10 in vitro by unstimulated and U. urealyticum (with or without lipopolysaccharide [LPS])-stimulated human monocytes from adult peripheral blood and from term and preterm cord blood. U. urealyticum alone and in combination with LPS induced concentration- and development-dependent changes in cytokine release. In vitro inoculation with low-inoculum U. urealyticum (10(3) color-changing units [CCU]) (i) partially blocked the LPS-stimulated IL-6 release by all cells and reduced LPS-stimulated IL-10 release by preterm cells, (ii) stimulated TNF-alpha and IL-8 release by preterm cells, and (iii) augmented LPS-stimulated TNF-alpha release in all cells. In preterm cells, high-inoculum U. urealyticum (10(6) CCU) (i) stimulated TNF-alpha and IL-8, but not IL-6 or IL-10, release and (ii) augmented LPS-stimulated TNF-alpha and IL-8 release. High-inoculum U. urealyticum (i) stimulated release of all four cytokines in term cells and IL-8 release in adult cells and (ii) augmented LPS-induced TNF-alpha, IL-10, and IL-8 release in term cells but did not significantly affect LPS-induced cytokine release in adult cells. We speculate that U. urealyticum enhances the proinflammatory response to a second infection by blocking expression of counterregulatory cytokines (IL-6 and IL-10), predisposing the preterm infant to prolonged and dysregulated inflammation, lung injury, and impaired clearance of secondary infections.


Subject(s)
Cytokines/metabolism , Fetal Blood/cytology , Lipopolysaccharides/pharmacology , Monocytes/immunology , Ureaplasma urealyticum/immunology , Adult , Humans , Infant, Newborn , Infant, Premature , Monocytes/drug effects , Monocytes/microbiology , Ureaplasma Infections/microbiology , Ureaplasma urealyticum/metabolism
4.
J Appl Physiol (1985) ; 90(1): 90-8, 2001 Jan.
Article in English | MEDLINE | ID: mdl-11133897

ABSTRACT

Fever is an important regulator of inflammation that modifies expression and bioactivity of cytokines, including tumor necrosis factor (TNF)-alpha. Pulmonary vascular endothelium is an important target of TNF-alpha during the systemic inflammatory response. In this study, we analyzed the effect of a febrile range temperature (39.5 degrees C) on TNF-alpha-stimulated changes in endothelial barrier function, capacity for neutrophil binding and transendothelial migration (TEM), and cytokine secretion in human pulmonary artery endothelial cells (EC). Permeability for [(14)C]BSA tracer was increased by treatment with TNF-alpha, and this effect was augmented by incubating EC at 39.5 degrees C. Treating EC with 2. 5 U/ml TNF-alpha stimulated an increase in subsequent neutrophil adherence and TEM. Incubating EC at 39.5 degrees C caused a 30% increase in TEM but did not modify the enhancement of neutrophil adherence or TEM by TNF-alpha treatment. Analysis of cytokine expression in EC cultures exposed to TNF-alpha at either 37 degrees or 39.5 degrees C revealed three patterns of temperature and TNF-alpha responsiveness. Granulocyte-macrophage colony stimulating factor (GM-CSF) and interleukin (IL)-8 were not detectable in untreated EC but were increased after TNF-alpha exposure, and this increase was enhanced at 39.5 degrees C. IL-6 expression was also increased with TNF-alpha exposure, but IL-6 expression was lower in 39.5 degrees C EC cultures. Transforming growth factor-beta(1) was constitutively expressed, and its expression was not influenced either by TNF-alpha or exposure to 39.5 degrees C. These data demonstrate that clinically relevant shifts in body temperature might cause important changes in the effects of proinflammatory cytokines on the endothelium.


Subject(s)
Body Temperature , Endothelium, Vascular/physiopathology , Fever/physiopathology , Tumor Necrosis Factor-alpha/physiology , Cell Adhesion/drug effects , Cell Movement/drug effects , Cell Survival/drug effects , Cells, Cultured , Cytokines/metabolism , Endothelium, Vascular/drug effects , Endothelium, Vascular/pathology , HSP72 Heat-Shock Proteins , Heat-Shock Proteins/metabolism , Humans , Neutrophils/physiology , Pulmonary Artery/pathology , Pulmonary Artery/physiopathology , Temperature , Tumor Necrosis Factor-alpha/pharmacology
5.
Clin Infect Dis ; 31 Suppl 5: S234-41, 2000 Oct.
Article in English | MEDLINE | ID: mdl-11113029

ABSTRACT

Sepsis is a clinical syndrome characterized by a systemic inflammatory response to infection. Mortality rates in sepsis have remained high, despite recent advances in our understanding of the immunological mechanisms that cause sepsis. Fever, a nonspecific acute-phase response, has been associated with improved survival and shortened disease duration in some infections. This article reviews the biological effects of fever and the influence of antipyretic therapy on the outcome in sepsis in experimental models and in humans and offers clinical recommendations for antipyretic therapy in early and late stages of the disorder.


Subject(s)
Analgesics, Non-Narcotic/therapeutic use , Sepsis/drug therapy , Analgesics, Non-Narcotic/adverse effects , Animals , Clinical Trials as Topic , Disease Models, Animal , Disease Progression , Humans , Outcome Assessment, Health Care , Sepsis/mortality , Sepsis/physiopathology
6.
Am J Respir Crit Care Med ; 161(4 Pt 1): 1229-36, 2000 Apr.
Article in English | MEDLINE | ID: mdl-10764316

ABSTRACT

The objective of this study was to determine the effects of allergen exposure on leukotriene generation and inflammation within the airways of allergic asthmatics and evaluate the effects of the 5-lipoxygenase inhibitor zileuton on these responses. We measured leukotriene-B(4) (LTB(4)) and LTC(4)/D(4)/E(4), inflammatory cytokine mediators, and cellular responses in bronchoalveolar lavage fluid (BALF) before and 24 h after segmental ragweed antigen challenge in 18 asthmatic subjects at baseline. Before initiating therapy with the 5-lipoxygenase inhibitor or placebo, only nine of 18 asthmatic subjects had a significant increase (234 +/- 102-fold, mean +/- SE) in BALF LTC(4)/D(4)/E(4) levels 24 h after segmental antigen challenge, whereas leukotriene levels were essentially unchanged (1.14 +/- 0.22-fold) in the other nine subjects. The high LT producers also had higher postantigen BALF levels of LTB(4), total protein, IL-5, IL-6, TNF-alpha, and recovery of more eosinophils than the low LT producers. Treatment with the 5-lipoxygenase inhibitor zileuton reduced postantigen BALF eosinophil count by 68% in the high LT producers, but had no detectable effect on BALF composition in the low LT producers. These data suggest that leukotriene inhibition may be more effective in a subset of asthmatics in whom leukotrienes are a major contributory factor in causing allergic inflammation.


Subject(s)
Asthma/drug therapy , Asthma/immunology , Hydroxyurea/analogs & derivatives , Leukotriene Antagonists/therapeutic use , Adult , Asthma/diagnosis , Bronchial Provocation Tests , Bronchoalveolar Lavage Fluid/chemistry , Bronchoalveolar Lavage Fluid/cytology , Cytokines/analysis , Double-Blind Method , Enzyme-Linked Immunosorbent Assay , Female , Humans , Hydroxyurea/therapeutic use , Inflammation Mediators/analysis , Leukotrienes/analysis , Lipoxygenase Inhibitors , Male , Skin Tests
7.
J Biol Chem ; 275(13): 9841-8, 2000 Mar 31.
Article in English | MEDLINE | ID: mdl-10734139

ABSTRACT

We previously reported that expression of tumor necrosis factor-alpha (TNFalpha) was attenuated in macrophages exposed to febrile range temperatures. In this study, we analyzed the influence of temperature on TNFalpha transcription in the Raw 264.7 macrophage cell line during incubation at 37 and 39.5 degrees C. The initial activation of TNFalpha transcription in response to endotoxin (LPS) was comparable in the 37 and 39.5 degrees C cell cultures, peaking within 10 min of LPS stimulation. However, the duration of transcriptional activation was markedly reduced in the 39.5 degrees C cells (30-60 min) compared with the 37 degrees C cells (2-4 h). Deletion mapping of the TNFalpha gene revealed that the proximal 85-nucleotide promoter sequence and the 5'-untranslated region were sufficient for temperature sensitivity. This sequence contains six heat shock response element (HRE) half-sites but no complete HREs. Electrophoretic mobility shift and immunoblot assays demonstrated that nuclear transclocation of heat shock factor (HSF) and its activation to a DNA-binding form occurred in the 39.5 degrees C cells in the absence of heat shock protein-70 gene activation. The proximal TNFalpha promoter/5'-untranslated region sequence competed for HSF binding to a classic HRE. Overexpression of HSF-1 reduced activity of the TNFalpha promoter. These data suggest that partial activation of HSF-1 during exposure to febrile, sub-heat shock temperatures may block TNFalpha transcription by binding to its proximal promoter or 5'-untranslated region.


Subject(s)
DNA-Binding Proteins/physiology , Fever/genetics , Gene Expression Regulation/physiology , Macrophages/metabolism , Transcription, Genetic , Tumor Necrosis Factor-alpha/genetics , Animals , Base Sequence , Cell Line , DNA Primers , Heat Shock Transcription Factors , Mice , Promoter Regions, Genetic , Protein Binding , Transcription Factors , Transcription, Genetic/physiology , Transcriptional Activation
8.
Infect Immun ; 68(3): 1265-70, 2000 Mar.
Article in English | MEDLINE | ID: mdl-10678936

ABSTRACT

Fever, a nonspecific acute-phase response, has been associated with improved survival and shortened disease duration in infections, but the mechanisms of these beneficial responses are poorly understood. We previously reported that increasing core temperature of bacterial endotoxin (LPS)-challenged mice to the normal febrile range modified expression of tumor necrosis factor alpha (TNF-alpha), interleukin 1beta (IL-1beta), and IL-6, three cytokines critical to mounting an initial defense against microbial pathogens, but survival was not improved in the warmer animals. We speculated that our inability to show a survival benefit of optimized cytokine expression in the warmer animals reflected our use of LPS, a nonreplicating agonist, rather than an infection with viable pathogens. The objective of this study was to determine if increasing murine core temperature altered cytokine expression and improved survival in an experimental bacterial peritonitis model. We showed that housing mice at 35.5 degrees C rather than 23 degrees C increased core temperature from 36.5 to 37.5 degrees C to 39.2 to 39.7 degrees C, suppressed plasma TNF-alpha expression for the initial 48 h, delayed gamma interferon expression, improved survival, and reduced the bacterial load in mice infected with Klebsiella pneumoniae peritonitis. We showed that the reduced bacterial load was not caused by a direct effect on bacterial proliferation and probably reflected enhanced host defense. These data suggest that the increase in core temperature that occurs during bacterial infections is essential for optimal antimicrobial host defense.


Subject(s)
Fever/etiology , Klebsiella Infections/physiopathology , Klebsiella pneumoniae , Peritonitis/physiopathology , Animals , Body Temperature , Interferon-gamma/blood , Interleukin-6/blood , Lipopolysaccharides/toxicity , Male , Mice , Tumor Necrosis Factor-alpha/analysis
9.
Microbes Infect ; 2(15): 1891-904, 2000 Dec.
Article in English | MEDLINE | ID: mdl-11165933

ABSTRACT

Sepsis is a highly lethal clinical syndrome characterized by a systemic inflammatory response to infection. Fever, a non-specific acute-phase response, has been associated with improved survival and shortened disease duration in non-life-threatening infections. However, the influence of fever and the effects of antipyresis in patients with sepsis has not been prospectively studied in humans. This paper reviews the state of our knowledge concerning the biological effects of fever in infected hosts and the influence of fever and antipyretic therapy on survival during sepsis in experimental models and in man.


Subject(s)
Analgesics, Non-Narcotic/therapeutic use , Fever/physiopathology , Infections/physiopathology , Animals , Fever/drug therapy , Fever/immunology , Humans , Infections/mortality , Sepsis/mortality , Sepsis/physiopathology
10.
Cell Stress Chaperones ; 5(5): 471-80, 2000 Nov.
Article in English | MEDLINE | ID: mdl-11189454

ABSTRACT

The heat shock response is an ancient and highly conserved process that is essential for surviving environmental stresses, including extremes of temperature. Fever is a more recently evolved response, during which organisms temporarily subject themselves to thermal stress in the face of infections. We review studies showing that fever is beneficial in the infected host. We show that core temperatures achieved during fever can activate the heat shock response and discuss some of the biochemical consequences of such an effect. We present data suggesting 4 possible mechanisms by which fever might confer protection: (1) directly killing or inhibiting growth of pathogens; (2) inducing cytoprotective heat shock proteins (Hsps) in host cells; (3) inducing expression of pathogen Hsps, an activator of host defenses; and (4) modifying and orchestrating host defenses. Two of these mechanisms directly involve the heat shock response. We describe how heat shock factor-1, the predominant heat-induced transcriptional enhancer not only activates transcription of Hsps but also regulates expression of pivotal cytokines and early response genes. The relationship between fever and the heat shock response is an illuminating example of how a more recently evolved response might exploit preexisting biochemical pathways for a new function.


Subject(s)
Fever/physiopathology , Heat-Shock Response/physiology , Animals , Humans
11.
J Interferon Cytokine Res ; 20(12): 1049-55, 2000 Dec.
Article in English | MEDLINE | ID: mdl-11152570

ABSTRACT

We have shown previously that febrile range temperatures modify cytokine production by adult macrophages. In this study, we compared the effects of moderate hyperthermia and hypothermia on the kinetics of lipopolysaccharide (LPS)-induced cytokine expression in monocytes and macrophages of newborns and adults. During culture at 40 degrees C, the initial rates of tumor necrosis factor-alpha (TNF-alpha) and interleukin-1 beta (IL-1 beta) secretion were preserved, but the duration of secretion was shorter than the duration at 37 degrees C. TNF-alpha and IL1-beta concentrations in 24-h 40 degrees C culture supernatants were reduced 18%-50%. IL-6 concentration in 24-h 40 degrees C cultures was reduced 26%-29% in all cells except adult macrophages. At 32 degrees C, changes in early (2 h) and sustained (24 h) cytokine expression were reversed compared with those caused by hyperthermia. Culturing adult macrophages at 32 degrees C blunted early secretion of TNF-alpha and IL-6 by 69% and 65%, respectively, and increased TNF-alpha concentration at 24 h by 48% compared with levels at 37 degrees C. In adult monocytes cultured at 32 degrees C, early IL-6 and IL-1 beta secretion was decreased 64% and 51%, respectively. We speculate that the burst/suppression cytokine profile at febrile temperatures might enhance early activation of host defenses and prevent prolonged exposure to potentially cytotoxic cytokines. Hypothermia, on the other hand, may worsen outcome in infections by delaying and prolonging cytokine production.


Subject(s)
Cytokines/metabolism , Phagocytes/metabolism , Adult , Age Factors , Cells, Cultured , Cytokines/biosynthesis , Humans , Hyperthermia, Induced , Hypothermia, Induced , Infant, Newborn , Temperature
12.
Am J Physiol ; 276(6): R1653-60, 1999 06.
Article in English | MEDLINE | ID: mdl-10362744

ABSTRACT

Fever is a phylogenetically ancient response that is associated with improved survival in acute infections. In endothermic animals, fever is induced by a set of pyrogenic cytokines [tumor necrosis factor-alpha (TNF-alpha), interleukin (IL)-1, and IL-6] that are also essential for survival in acute infections. We studied the influence of core temperature on cytokine expression using an anesthetized mouse model in which core temperature was adjusted by immersion in water baths. We showed that raising core temperature from basal (36.5-37.5 degrees C) to febrile (39.5-40 degrees C) levels increased peak plasma TNF-alpha and IL-6 levels by 4.1- and 2. 7-fold, respectively, and changed the kinetics of IL-1beta expression in response to lipopolysaccharide challenge. TNF-alpha levels were increased predominantly in liver, IL-1beta levels were higher in lung, and IL-6 levels were widely increased in multiple organs in the warmer mice. This demonstrates that the thermal component of fever may directly contribute to shaping the host response by regulating the timing, magnitude, and tissue distribution of cytokine generation during the acute-phase response.


Subject(s)
Body Temperature/physiology , Cytokines/metabolism , Endotoxins/pharmacology , Fever/physiopathology , Pyrogens/metabolism , Animals , Cytokines/blood , Dose-Response Relationship, Drug , Fever/blood , Fever/metabolism , HSP72 Heat-Shock Proteins , Heat-Shock Proteins/metabolism , Interleukin-1/metabolism , Interleukin-6/blood , Interleukin-6/metabolism , Kupffer Cells/physiology , Lipopolysaccharides/pharmacology , Male , Mice , Mice, Inbred Strains , Pyrogens/blood , Tissue Distribution/physiology , Tumor Necrosis Factor-alpha/metabolism
13.
Chest ; 115(3): 829-35, 1999 Mar.
Article in English | MEDLINE | ID: mdl-10084499

ABSTRACT

BACKGROUND: Chronic bronchitis in cigarette smokers shares many clinical and histologic features with environmental lung diseases attributed to bacterial endotoxin (lipopolysaccharide [LPS]) inhalation. Experimental LPS inhalation mimics many of the acute effects of cigarette smoke in the lower airway. Therefore, we reasoned that LPS may be a biologically active component of cigarette smoke. DESIGN: The Limulus amebocyte lysate (LAL) assay was used to measure LPS in the tobacco and filter tip components of unsmoked 1R4F experimental cigarettes and commercially available "light" cigarettes, as well as in mainstream (MS) and sidestream (SS) smoke particles generated with an automated smoking machine and collected on ventilator mainflow filters. SETTING AND PARTICIPANTS: Blood LPS activity and plasma cytokine concentrations were measured in groups of healthy smokers and nonsmokers who reported to the walk-in clinic at the Baltimore VA Medical Center for unrelated complaints. MEASUREMENTS: Blood LPS levels were measured by LAL assay and plasma levels of tumor necrosis factor-alpha (TNF-alpha), interleukin 6 (IL-6), soluble TNF receptors I and II (sTNFR I and sTNFR II) were measured by enzyme-linked immunosorbent assay. RESULTS: Bioactive LPS was detected in both the tobacco portion (1R4F, 17.8+/-1.0 microg/cigarette; light, 26.8+/-7.3 microg/cigarette [mean+/-SE]) and filter tips (1R4F, 0.67+/-0.55 microg/cigarette; light, 0.70+/-0.39 microg/cigarette) of cigarettes. Bioactive LPS was also detected in both MS (1R4F, 120+/-64 ng/cigarette; light: 45.3+/-16 ng/cigarette) and SS smoke (1R4F, 18+/-1.5 ng/cigarette; light: 75+/-49 ng/cigarette). Although systemic absorption of inhaled LPS may occur, we failed to detect any differences between nonsmokers and smokers in median blood LPS levels (median values, 66.75 and 72.1 pg/mL, respectively; p = 0.55) or plasma concentrations of TNF-alpha (0 vs 0 pg/mL, respectively; p = 0.71), sTNFR I(1,469 vs 1,576 pg/mL, respectively), sTNFR II (2,011 vs 3,110 pg/mL, respectively), or IL-6 (8.8 vs 0 pg/mL, respectively; p = 0.20). CONCLUSIONS: Smoking one pack of cigarettes per day delivers a dose of respirable LPS that is comparable to the levels of LPS associated with adverse health effects in cotton textile workers. Thus, we suggest that the bioactive LPS in cigarette smoke may contribute to the pathogenesis of chronic bronchitis that develops in susceptible cigarette smokers.


Subject(s)
Bronchitis/metabolism , Lipopolysaccharides/analysis , Nicotiana , Plants, Toxic , Smoke/analysis , Chronic Disease , Cytokines/analysis , Cytokines/blood , Escherichia coli , Humans , Lipopolysaccharides/blood
14.
Infect Immun ; 67(4): 1539-46, 1999 Apr.
Article in English | MEDLINE | ID: mdl-10084984

ABSTRACT

Fever improves survival in acute infections, but the effects of increased core temperature on host defenses are poorly understood. Tumor necrosis factor alpha (TNF-alpha) is an early activator of host defenses and a major endogenous pyrogen. TNF-alpha expression is essential for survival in bacterial infections but, if disregulated, can cause tissue injury. In this study, we show that passively increasing core temperature in mice from the basal (36.5 to 37.5 degrees C) to the febrile (39.5 to 40 degrees C) range modifies systemic TNF-alpha expression in response to bacterial endotoxin (lipopolysaccharide). The early TNF-alpha secretion rate is enhanced, but the duration of maximal TNF-alpha production is shortened. We identified Kupffer cells as the predominant source of the excess TNF-alpha production in the warmer animals. The enhanced early TNF-alpha production observed at the higher temperature in vivo could not be demonstrated in isolated Kupffer cells or in precision-cut liver slices in vitro, indicating the participation of indirect pathways. Therefore, expression of the endogenous pyrogen TNF-alpha is regulated by increments in core temperature during fever, generating an enhanced early, self-limited TNF-alpha pulse.


Subject(s)
Body Temperature Regulation/immunology , Fever/immunology , Lipopolysaccharides/immunology , Tumor Necrosis Factor-alpha/immunology , Animals , Disease Models, Animal , Kupffer Cells/immunology , Liver/immunology , Male , Mice , Tumor Necrosis Factor-alpha/metabolism
15.
Infect Immun ; 66(4): 1400-7, 1998 Apr.
Article in English | MEDLINE | ID: mdl-9529059

ABSTRACT

Bacterial lipopolysaccharide induces tyrosine phosphorylation of paxillin, actin reorganization, and opening of the transendothelial paracellular pathway through which macromoles flux. In this study, lipid A was shown to be the bioactive portion of the lipopolysaccharide molecule responsible for changes in endothelial barrier function. We then studied whether endotoxin-neutralizing protein, a recombinant peptide that is derived from Limulus antilipopolysaccharide factor and targets lipid A, could block the effects of lipopolysaccharide on protein tyrosine phosphorylation, actin organization, and movement of 14C-bovine serum albumin across bovine pulmonary artery endothelial cell monolayers. In the presence of serum, a 6-h exposure to lipopolysaccharide (10 ng/ml) increased transendothelial 14C-albumin flux compared to the simultaneous media control. Coadministration of endotoxin-neutralizing protein (> or =10 ng/ml) with lipopolysaccharide (10 ng/ml) protected against lipopolysaccharide-induced barrier dysfunction. This protection was dose dependent, conferring total protection at endotoxin-neutralizing protein/lipopolysaccharide ratios of > or =10:1. Similarly, endotoxin-neutralizing protein was capable of blocking the lipopolysaccharide-induced endothelial cell responses that are prerequisite to barrier dysfunction, including tyrosine phosphorylation of paxillin and actin depolymerization. Finally, endotoxin-neutralizing protein cross-protected against lipopolysaccharide derived from diverse gram-negative bacteria. Thus, endotoxin-neutralizing protein offers a novel therapeutic intervention for the vascular endothelial dysfunction of gram-negative sepsis and its attendant endotoxemia.


Subject(s)
Anti-Bacterial Agents/pharmacology , Endothelium, Vascular/drug effects , Invertebrate Hormones/pharmacology , Lipopolysaccharides/toxicity , Actins/metabolism , Animals , Antimicrobial Cationic Peptides , Arthropod Proteins , Cattle , Cells, Cultured , Endothelium, Vascular/metabolism , Lipopolysaccharides/antagonists & inhibitors , Phosphorylation , Serum Albumin, Bovine/metabolism , Structure-Activity Relationship , Tyrosine/metabolism
16.
Am J Respir Crit Care Med ; 156(5): 1523-9, 1997 Nov.
Article in English | MEDLINE | ID: mdl-9372670

ABSTRACT

An imbalance of proinflammatory cytokines such as TNF-alpha, IL-1 beta, and the neutrophil chemotactic factor IL-8 and inhibitors (e.g., soluble TNF receptors and IL-1ra) in the lung during the first week of life may contribute to prolonged pulmonary inflammation and fibrosis in bronchopulmonary dysplasia (BPD). Disodium cromoglycate (DSCG) has anti-inflammatory effects in asthma, a disease with many similarities with BPD. In a prospective, randomized, blinded study, we examined whether early DSCG therapy inhibits proinflammatory cytokines in infants at risk for BPD. Twenty-six infants who were identified as high risk (> or = 75% probability) for oxygen-dependency at 28 d by a 12-h predictive score and survived 48 h were randomized to nebulized DSCG 20 mg (n = 13) or 2 cc NS (control, n = 13) every 6 h from Day 3 to Day 28. Lung lavage was collected on Day 3 (pre-study) and Day 7 and analyzed for cell count and differential and TNF-alpha, sTNFR1, sTNFR2, IL-1 beta, IL-1ra, and IL-8 concentrations. The groups' pre-study lavage cytokine concentrations were similar, but TNF-alpha and IL-8 concentrations were 3.6- and 4.9-fold lower in the DSCG group on Day 7 compared with levels in the control group. Soluble TNF receptors were unaffected by DSCG. There was a trend towards lower IL-1 beta levels in DSCG-treated infants on Day 7, but IL-1ra levels were unaffected by DSCG therapy. Three control subjects, but no DSCG-treated infants, died during the study period (p = 0.07). There were no significant differences between survivors of the two groups for oxygen-dependency at 28 d (100% control subjects; 85% DSCG). These results suggest that nebulized DSCG may exert an anti-inflammatory effect in the lungs of infants < or = 1,000 g at risk for BPD.


Subject(s)
Bronchopulmonary Dysplasia/prevention & control , Cromolyn Sodium/therapeutic use , Cytokines/metabolism , Inflammation Mediators/metabolism , Bronchoalveolar Lavage Fluid/chemistry , Bronchoalveolar Lavage Fluid/cytology , Bronchopulmonary Dysplasia/metabolism , Cell Count , Double-Blind Method , Enzyme-Linked Immunosorbent Assay , Humans , Infant, Newborn , Interleukin-1/metabolism , Interleukin-8/metabolism , Macrophages/cytology , Neutrophils/cytology , Prospective Studies , Risk Factors , Tumor Necrosis Factor-alpha/metabolism
19.
J Biol Chem ; 272(34): 21120-7, 1997 Aug 22.
Article in English | MEDLINE | ID: mdl-9261116

ABSTRACT

In unstimulated RAW 264.7 macrophage-like cells, tumor necrosis factor-alpha (TNF-alpha) mRNA was transcribed and accumulated in the cytoplasm, but the TNF-alpha transcripts failed to associate with polysomes, and TNF-alpha protein was not detected. Stimulation with lipopolysaccharide (LPS) induced an increase in TNF-alpha transcription, cytoplasmic TNF-alpha mRNA accumulation, polysome association, and secretion of TNF-alpha protein. This process was associated with a 200-nucleotide increase in the apparent length of the TNF-alpha mRNA. The difference in TNF-alpha mRNA size was caused by marked truncation of the 3' poly(A) tail in unstimulated cells. Fully adenylated TNF-alpha mRNA appeared within 15 min of LPS stimulation. We speculate that removal of the poly(A) tail blocks initiation of TNF-alpha translation in unstimulated macrophages. LPS inactivates this process, allowing synthesis of translatable polyadenylated TNF-alpha mRNA.


Subject(s)
Gene Expression Regulation , Poly A/genetics , Tumor Necrosis Factor-alpha/genetics , Alternative Splicing , Animals , Cell Line , Cytoplasm/metabolism , Humans , Lipopolysaccharides/pharmacology , Macrophages/physiology , Mice , Monocytes/physiology , Poly A/metabolism , Polyribosomes/metabolism , Protein Biosynthesis/drug effects , Protein Synthesis Inhibitors/pharmacology , RNA Processing, Post-Transcriptional
20.
Clin Infect Dis ; 25(1): 119-38, 1997 Jul.
Article in English | MEDLINE | ID: mdl-9243046

ABSTRACT

Fever has been a preoccupation of clinicians since medicine's beginning. One might therefore expect that basic concepts relating to this physiological response would be well delineated and that such concepts would be widely known. In fact, only in the past several decades has the febrile response been subjected to scientific scrutiny. As a result of recent scientific investigation, modern concepts have evolved from a perception of fever as nothing more than a rise in core temperature to one in which fever is recognized as a complex physiological response characterized by a cytokine-mediated rise in temperature, as well as by generation of acute-phase reactants and activation of a panoply of physiological, endocrinologic, and immunologic systems. The average clinician appears to have little more than a regrettably rudimentary knowledge of these modern concepts of fever. This symposium summary considers many such concepts that have immediate relevance to the practice of medicine.


Subject(s)
Fever , Acute-Phase Proteins/physiology , Body Temperature , Cytokines/antagonists & inhibitors , Cytokines/physiology , Fever/etiology , Fever/physiopathology , Fever/therapy , Forecasting , HIV Infections/physiopathology , Humans
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