Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P43026 (lipopolysaccharide)
 62,215 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Interleukin-6 (IL-6) is a cytokine produced in response to a variety of inflammatory stimuli. Although IL-6 is often observed in increased amounts in acute respiratory distress syndrome, its role in the development of lung injury is unclear. The role of IL-6 was studied in the rat model of lung injury induced by the intra-alveolar deposition of IgG immune complexes. IL-6 induction, as determined by Northern blot analysis and bioactivity, was found as a function of time during the course of development of injury. Recombinant IL-6 instilled intratracheally at commencement of injury led to substantial reductions in lung vascular permeability, neutrophil accumulation, and levels of tumor necrosis factor (TNF)-alpha and macrophage inflammatory protein (MIP)-2 in bronchoalveolar lavage fluids. Conversely, blocking of intrinsic IL-6 by a neutralizing antibody resulted in increases in lung vascular permeability, neutrophil content, and TNF-alpha levels in bronchoalveolar lavage fluids. Rat alveolar macrophages stimulated in vitro with lipopolysaccharide in the presence of IL-6 showed a significant reduction in TNF-alpha expression. Together, these findings suggest that IL-6 acts as an intrinsic regulator of lung inflammatory injury after deposition of IgG immune complexes and that the protective effects of exogenously administered IL-6 may be in part linked to suppressed TNF-alpha production.
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PMID:Regulatory effects of interleukin-6 in immunoglobulin G immune-complex-induced lung injury. 921 45

Lung injury in the acute respiratory distress syndrome (ARDS) is in part due to polymorphonuclear leukocyte (PMN)-mediated oxidative tissue damage. By means of nuclear factor-kappaB (NF-kappaB) activation, oxidants may also induce several genes implicated in the inflammatory response. The dithiocarbamates are antioxidants with potent inhibitory effects on NF-kappaB. We postulated that the pyrrolidine derivative pyrrolidine dithiocarbamate (PDTC) would attenuate lung injury following intratracheal challenge with endotoxin (lipopolysaccharide; LPS) through its effect as an antioxidant and inhibitor of gene activation. Rats were given PDTC (1 mmole/kg) by intraperitoneal injection, followed by intratracheal administration of LPS. The transpulmonary flux of [125I] albumin (permeability index; PI) was used as a measure of lung injury. Northern blot analysis of total lung RNA was performed to assess induction of tumor necrosis factor-alpha (TNF-alpha) and intercellular adhesion molecule-1 (ICAM-1) messenger RNA (mRNA) as markers of NF-kappaB activation. The effect of in vivo treatment with PDTC on LPS-induced NF-kappaB DNA binding activity in macrophage nuclear extracts was evaluated with the electrophoretic mobility shift assay (EMSA). PDTC administration attenuated LPS-induced increases in lung permeability (PI = 0.16 +/- 0.02 for LPS versus 0.06 +/- 0.01 for LPS + PDTC; P < 0.05). TNF-alpha levels and PMN counts in bronchoalveolar lavage fluid (BALF) were unaffected, as were whole-lung TNF-alpha and ICAM-1 mRNA expression. PDTC had no effect on NF-kappaB activation as evaluated with EMSA. PDTC reduced lung lipid peroxidation as assessed by levels of malondialdehyde, without reducing neutrophil oxidant production. We conclude that PDTC attenuates LPS-induced acute lung injury. This effect occurs independently of any effect on NF-kappaB. PDTC reduces oxidant-mediated cellular injury, as demonstrated by a reduction in the accumulation of malondialdehyde. Administration of PDTC may represent a novel approach to limiting neutrophil-mediated oxidant injury.
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PMID:Pyrrolidine dithiocarbamate attenuates endotoxin-induced acute lung injury. 937 12

Distal lung epithelial cells (DLECs) play an active role in fluid clearance from the alveolus by virtue of their ability to actively transport Na+ from the alveolus to the interstitial space. The present study evaluated the ability of activated macrophages to modulate the bioelectric properties of DLECs. Low numbers of lipopolysaccharide (LPS)-treated macrophages were able to significantly reduce amiloride-sensitive short-circuit current (Isc) without affecting total Isc or monolayer resistance. This was associated with a rise in the flufenamic acid-sensitive component of the Isc. The effect was reversed by the addition of N-monomethyl-L-arginine to the medium, implying a role for nitric oxide. We hypothesized that macrophages exerted their effect by expressing inducible nitric oxide synthase (iNOS) in DLECs. The products of LPS-treated macrophages increased the levels of iNOS protein and mRNA transcripts in DLECs as well as causing a rise in iNOS activity. Immunofluorescence microscopy of LPS-stimulated macrophage-DLEC cocultures with anti-nitrotyrosine antibodies provided evidence for the generation of peroxynitrite in macrophages but not in DLECs. These data indicate that activated macrophages in the lung may contribute to impaired resolution of acute respiratory distress syndrome and suggest a novel mechanism whereby nitric oxide might alter cell function by altering its ion-transporting phenotype.
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PMID:Inhibition of amiloride-sensitive sodium-channel activity in distal lung epithelial cells by nitric oxide. 953 Jan 73

We present for the first time direct continuous assay of NO concentration (porphyrinic sensor) in the lung parenchyma of Sprague-Dawley rats in vivo during endotoxemia. Intravenous infusion of lipopolysaccharide (LPS, 2 mg x kg(-1) x min(-1) for 10 minutes) stimulated an acute burst of NO from constitutive NO synthase (NOS) that peaked 10 to 15 minutes after the start of LPS infusion, mirroring a coincident peak drop in arterial pressure. NO concentration declined over the next hour to twice above pre-LPS infusion NO levels, where it remained until the rats died, 5 to 6 hours after LPS infusion. The chronic drop in arterial pressure observed from 70 minutes to 6 hours after the start of LPS infusion was not convincingly mirrored by a chronic increase in NO concentration, even though indirect NO assay (Griess method, assaying NO decay products NO2-/NO3-) showed that NO production was increasing as a result of continuous NO release by inducible NOS. A NOS inhibitor, N(omega)-nitro-L-arginine (L-NNA, 10 mg/kg i.v.) injected 45 minutes before LPS infusion, resulted in sudden death accompanied by macroscopically/microscopically diagnosed symptoms similar to acute respiratory distress syndrome <25 minutes after the start of LPS infusion. Pharmacological analysis of this L-NNA+LPS model by replacing L-NNA with 1-amino-2-hydroxy-guanidine (selective inhibitor of inducible NOS) or by pretreatment with S-nitroso-N-acetyl-penicillamine (NO donor), camonagrel (thromboxane synthase inhibitor), or WEB2170 (platelet-activating factor receptor antagonist) indicated that in the early acute phase of endotoxemia, LPS stimulated the production of cytoprotective NO, cytotoxic thromboxane A2, and platelet-activating factor.
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PMID:Protective role of pulmonary nitric oxide in the acute phase of endotoxemia in rats. 956 42

The aim of this study was to characterize early ultrastructural, biochemical, and functional alterations of the pulmonary surfactant system induced by Salmonella minnesota lipopolysaccharide (LPS) in rat lungs. Experimental groups were: (1) control in vitro, 150 min perfusion; (2) LPS in vitro, 150 min perfusion, infusion of 50 microg/ml LPS after 40 min; (3) control ex vivo, 10 min perfusion; (4) LPS ex vivo, lungs perfused for 10 min from rats treated for 110 min with 20 mg/kg LPS intraperitoneally. Morphometry of type II pneumocytes showed that LPS increased stored surfactant. Lamellar bodies were increased in size, but decreased in numerical density, suggesting that giant lamellar bodies observed in LPS-treated lungs may result from fusion of normal bodies. Structural analysis of alveolar surfactant composition showed that LPS elicited an increase in lamellar body-like and multilamellar forms. Bronchoalveolar lavage (BAL) material from LPS-treated lungs was decreased in phospholipids. BAL bubble surfactometer analysis showed a reduction in hysteresis area caused by LPS. We conclude that LPS leads to alterations of intracellular and alveolar surfactant within 2 h: fusion of lamellar bodies, reduction in surfactant secretion, and changes in alveolar surfactant transformation, composition, and function, which may contribute to the development of respiratory distress.
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PMID:Early alterations in intracellular and alveolar surfactant of the rat lung in response to endotoxin. 960 48

Curosurf, a natural lung surfactant, is considered a potential candidate for improving the treatment of acute respiratory distress syndrome (ARDS). To investigate this in a rat model of early-stage ARDS, Curosurf (62.5, 125 or 250 mg x kg(-1)) was administered by intratracheal bolus at 10 or 24 h following an intratracheal lipopolysaccharide (LPS; 1.6 mg x kg(-1)) challenge. Survival, respiratory frequency (fR), lung wet weight (LWW), total protein and cell differentiation in bronchoalveolar lavage fluid (BALF) were assessed. Curosurf treatment at 10 h after LPS challenge resulted in 100% survival at both 62.5 and 125 mg x kg(-1); at a dose of 250 mg x kg(-1) administered at 10 h after LPS, 1 out of 6 animals died. At a dose of 125 mg x kg(-1) Curosurf administered at 24 h after LPS, 1 out of 6 animals died. In contrast, only 35% of animals survived when not treated with Curosurf. Curosurf treatment resulted in an improved fR and in a significantly decreased LWW, total protein and number of polymorphonuclear cells in BALF. In conclusion, Curosurf treatment improved respiratory frequency and decreased mortality, pulmonary oedema and inflammation. As the decreased mortality was observed in spontaneously breathing nonoxygenated animals, the results cannot be extrapolated to human artificially ventilated acute respiratory distress syndrome patients with the expectation of a decreased mortality. The results suggest, however, that Curosurf may be an important therapeutic measure in early-stage acute respiratory distress syndrome.
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PMID:Efficacy of Curosurf in a rat model of acute respiratory distress syndrome. 976 75

Mechanism in the pathogenesis of acute respiratory distress syndrome which is the clinical feature of pulmonary involvement in retinoic acid (RA) syndrome has been investigated. Pulmonary infiltration of matured neutrophils and leukemic cells is thought to be associated with the pathogenesis of pulmonary involvement in RA syndrome; however. Little is known about the mechanism in pulmonary infiltration of these cells. In the present study, we examined the effect of RA on IL-1beta and IL-1ra production by human alveolar macrophages in order to clarify the mechanism in pulmonary infiltration of neutrophils, since IL-1 has been shown to initiate neutrophil recruitment into the lung through up-regulated expression of adhesion molecules on vascular endothelium. RA enhanced IL-1beta and inhibited IL-1ra production by 4beta phorbol 12beta-myristate-13alpha acetate (PMA)- and lipopolysaccharide (LPS)-stimulated human alveolar macrophages. These results show that RA differentially regulates IL-1beta and IL-1ra production by alveolar macrophages and indicate that an imbalanced production between IL-1beta and IL-1ra may contribute to initiating neutrophil recruitment into the lung through up-regulated expression of adhesion molecules.
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PMID:Retinoic acid differentially regulates interleukin-1beta and interleukin-1 receptor antagonist production by human alveolar macrophages. 978 9

Inhaled endotoxin (lipopolysaccharide, LPS) can induce acute lung injury and at high doses may lead to respiratory distress syndrome. Using a mouse model of acute lung inflammation induced by inhalation of low doses of LPS we examined the kinetics of chemokine, proinflammatory cytokine, and metallothionein. Eight-week-old C57BL/6 mice were dosed for 10 min with LPS, resulting in an estimated alveolar dose of < 10 ng LPS/mouse, and euthanized 2,6, or 24 h postexposure. Analysis of bronchoalveolar lavage fluid demonstrated increased polymorphonuclear neutrophils (PMNs) of 6.94, 32.7, and 38.8% after 2, 6, and 24 h, respectively. Examination of proinflammatory cytokine, chemokine, and Mt mRNA in the lung revealed increases for messages encoding IL-1 alpha, IL-1 beta, IL-6, IFN-gamma, TNF alpha, Eotaxin, MIP-1 alpha, MIP-1 beta, MIP-2, Mt, and IP-10, while messages encoding IL-12, IL-10, IFN-beta, Ltn, MCP-1, TGF beta 1 + 2, and RANTES were unchanged from those of sham-exposed mice 2 h postexposure. By 6 h most messages had returned to near control levels. Comparison to 5 mg/kg body weight intraperitoneal injection and 5 micrograms/mouse intratracheal instillation 2 h postexposure demonstrated similar message responses. Our results demonstrate that low levels of LPS exposure by inhalation induce a strong PMN response and a selective cytokine response in the lung, supporting the hypothesis that PMNs may regulate inflammatory processes via cytokine and chemokine response.
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PMID:Pulmonary cytokine and chemokine mRNA levels after inhalation of lipopolysaccharide in C57BL/6 mice. 1004 33

The prophylactic effects of selectin inhibitors on lipopolysaccharide-induced acute lung injury were studied in rabbits by using sialyl Lewis X-oligosaccharide and PB1.3, an anti-human P-selectin monoclonal antibody. Lipopolysaccharide-induced acute lung injury resembles that of the acute respiratory distress syndrome, in which there is a decrease in arterial blood oxygen tension (PaO2) and an increase in the difference between alveolar and arterial oxygen tension (A-aDO2). Prophylactic treatment with the selectin inhibitors, sialyl Lewis X-oligosaccharide (55 mg kg(-1) i.v. bolus injection immediately before lipopolysaccharide administration + 36 mg kg(-1) h(-1) i.v. infusion for 4 h) and PB1.3 (5 mg kg(-1) i.v. bolus injection immediately before lipopolysaccharide administration), prevented the lipopolysaccharide-induced impairments in pulmonary gas exchange. In contrast, these agents had no significant effects on lipopolysaccharide-induced systemic hypotension, the decrease in the number of circulating white blood cells and platelets, the decline in blood pH, or the increase in arterial CO2 tension (PaCO2). These results indicate that selectin inhibitors including sialyl Lewis X-oligosaccharide and the anti-P-selectin antibody, PB1.3, attenuate lipopolysaccharide-induced acute lung injury in rabbits. This is the first demonstration that P-selectin is directly involved in the development of lipopolysaccharide-induced impairments in pulmonary gas exchange.
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PMID:Protective effects of sialyl Lewis X and anti-P-selectin antibody against lipopolysaccharide-induced acute lung injury in rabbits. 1032 79

Patients with unresolving acute respiratory distress syndrome (ARDS) have persistently elevated levels of proinflammatory cytokines in the lungs and circulation and increased rates of bacterial infections. Phagocytic cells hyperactivated with lipopolysaccharide (LPS), which induces high levels of proinflammatory cytokines in monocytic cells, are inefficient in killing ingested bacteria despite having intact phagocytic activity. On the other hand, phagocytic cells that are activated with an analogue of LPS that does not induce the expression of proinflammatory cytokines effectively ingest and kill bacteria. We hypothesized that in the presence of high concentrations of proinflammatory cytokines, bacteria may adapt and utilize cytokines to their growth advantage. To test our hypothesis, we primed a human monocytic cell line (U937) with escalating concentrations of the proinflammatory cytokines tumor necrosis factor alpha, interleukin-1beta (IL-1beta), and IL-6 and with LPS. These cells were then exposed to fresh isolates of three common nosocomial pathogens: Staphylococcus aureus, Pseudomonas aeruginosa, and an Acinetobacter sp. In human monocytes primed with lower concentrations of proinflammatory cytokines (10 to 250 pg) or LPS (1 and 10 ng), intracellular bacterial growth decreased. However, when human monocytes were primed with higher concentrations of proinflammatory cytokines (1 to 10 ng) or LPS (1 to 10 micrograms), intracellular growth of the tested bacteria increased significantly (P <0.0001). These results were reproduced with peripheral blood monocytes obtained from normal healthy volunteers. The specificity of the cytokine activity was demonstrated by neutralizing the cytokines with specific antibodies. Our findings provide a possible mechanism to explain the frequent development of bacterial infections in patients with an intense and protracted inflammatory response.
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PMID:Effects of cytokines and endotoxin on the intracellular growth of bacteria. 1033 88


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