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)

Airway mucosa consists of several types of cells including ciliated cells, mucus secreting cells, basal cells and Clara cells. In this review, fine structures of these epithelial cells and intercellular junctions are demonstrated by scanning and transmission electron microscopy, and the proposed kinetics of cellular maturation and development are discussed. Airway epithelium not only plays a role as a mechanical barrier at the air-surface interface but also possesses a wide variety of functions. Ciliary beating has been recognized to be one of the important determinants for mucociliary transport by clearing inhaled particles and bacteria from the airway. We found that the motility of cilia can be regulated by intracellular second messengers, such as Ca2+, cAMP, and protein kinase C. When ciliated epithelium is encountered by physicochemical stimuli, these signal transduction systems are activated through phosphatidylinositol turnover and/or Ca2+ channel opening, which subsequently modulate the synthesis of ATP, an energy source of ciliary beating. Airway epithelium contains the enzyme neutral endopeptidase which can degrade several peptides into inactive fragments, thus regulating the actions of tachykinins released from sensory C-fibers via axon reflex. Ion transport across airway mucosa is determined by Cl secretion and Na absorption in airway epithelium. To elucidate the mechanism of airway hypersecretion under several conditions of respiratory diseases, the effects of chemical mediators, neuropeptides, and inflammatory mediators on electrical properties of canine cultured tracheal epithelium were studied. We also expanded this idea to human subjects and found that indomethacin inhalation was valuable in reducing the amounts of sputum production by inhibiting Cl and water secretion into the airway lumen. In addition, airway epithelium can modulate contraction of airway smooth muscle by generating epithelium-derived relaxing factor (EpDRF). We have shown that lipopolysaccharide-induced airway hyperreactivity seems attributable to the loss of airway epithelium with EpDRF.
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PMID:[Structure and function of airway epithelial cells]. 207 99

Rat microglia in culture showed a high capacity to degrade neuropeptides compared with other glial cells. Leu-enkephalin was readily hydrolyzed to free tyrosine and Gly-Gly-Phe-Leu. Inhibition experiments and immunostaining revealed that aminopeptidase N (CD13) on the surface of microglia was responsible for enkephalin cleavage. Endopeptidase-24.11 ("enkephalinase"), angiotensin-converting enzyme, or carboxypeptidases could not be detected on microglia. Aminopeptidase N activity in microglia was considerably higher than in rat peripheral monocytes and macrophages, which both also exhibited low endopeptidase 24.11 activities. Activity of aminopeptidase N was upregulated by culture of microglia on astrocytes and down-regulated by exposure of microglia to lipopolysaccharide. The occurrence of aminopeptidase N on microglia is in line with the view that they originate from the monocytic lineage.
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PMID:Enkephalin metabolism by microglial aminopeptidase N (CD13). 753 37

1. As lipopolysaccharide is a major stimulator of neutrophil responses during Gram-negative bacterial infections, we studied its effect on the membrane expression of neutral endopeptidase 24.11/CD10 on neutrophils in a model of endotoxaemia in vitro. Lipopolysaccharide added to human whole-blood induced a marked and sustained CD10/neutral endopeptidase upregulation that was already detectable at 0.1 ng/ml and was maximal at a lipopolysaccharide concentration of 10 ng/ml. 2. We observed that neither tumour necrosis factor-alpha nor any newly synthesized protein was involved in the upregulation observed after 1 h incubation with 10 ng/ml lipopolysaccharide. 3. We further studied whether the lipopolysaccharide-induced CD10/neutral endopeptidase upregulation was mediated by lipopolysaccharide binding to the neutrophil CD14 receptor. Incubation of whole blood with an anti-CD14 monoclonal antibody before the addition of 0.1 ng/ml or 0.5 ng/ml lipopolysaccharide resulted in complete inhibition of CD10/neutral endopeptidase upregulation. In contrast, at a lipopolysaccharide concentration of 10 ng/ml, the anti-CD14 monoclonal antibody had an incomplete blocking effect. 4. The differential requirement for the CD14 receptor, depending on the lipopolysaccharide dose, was confirmed by the study of a patient suffering from paroxysmal nocturnal haemoglobinuria (in whom a complete defect in neutrophil CD14 expression was previously documented). 5. We finally confirmed these results using purified neutrophils, demonstrating that lipopolysaccharide-induced CD10/neutral endopeptidase upregulation depends on direct interaction with neutrophil CD14.
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PMID:Lipopolysaccharide induces upregulation of neutral endopeptidase 24.11 on human neutrophils: involvement of the CD14 receptor. 754 62

Inhalation of lipopolysaccharide (LPS) has been associated with increased airway responsiveness and inflammation both in humans and in animals. To investigate the contribution of capsaicin-sensitive nerves to these changes, we compared airway responsiveness and inflammation after intratracheal administration of 10 micrograms/kg LPS (Escherichia coli O55:B5 lipopolysaccharide) or saline in guinea pigs treated 10 days previously with 50 mg/kg capsaicin and in those pretreated with the capsaicin vehicle. Four hours after LPS, airway responsiveness and cell counts in the bronchoalveolar lavage were assessed. To determine airway responsiveness, guinea pigs were anesthetized, tracheotomized, and mechanically ventilated before exposure to increasing concentrations of aerosolized histamine (10(-4) to 10(-3) M). Capsaicin pretreatment prevented the LPS-induced increase in airway responsiveness in response to aerosolized histamine. It significantly reduced total cell recovery in the bronchoalveolar lavage after LPS (1,167 +/- 167 10(3) cells/ml in capsaicin-treated guinea pigs versus 2,171 +/- 184 10(3) in vehicle-treated guinea pigs) by reducing the LPS-induced influx of neutrophils and macrophages. Additional experiments demonstrated that the activity of neutral endopeptidase (NEP) in the tracheal epithelium was not significantly different in guinea pigs injected with LPS from that in the saline-treated control animals, and that the pretreatment with the NEP inhibitor phosphoramidon did not increase the LPS-induced influx of neutrophils into the bronchoalveolar lavage. These results demonstrate that in the guinea pig, capsaicin-sensitive nerves are involved in LPS-induced airway hyperresponsiveness and inflammation.
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PMID:Effects of capsaicin on the airway responses to inhaled endotoxin in the guinea pig. 811 69

The B1 receptors for kinins are selectively stimulated by bradykinin (BK) and Lys-BK metabolites that do not have the C-terminal arginine, des-Arg9-BK and Lys-des-Arg9-BK, respectively. B1 receptors mediate a definite subset of the cardiovascular effects of kinins in normal and septic animals. We have studied the metabolism of the best selective B1 antagonist, Lys[Leu8]des-Arg9-BK, in order to support the rational design of new antagonists that have increased metabolic stability. The affinity of the new compounds was evaluated using the pA2 scale and was based on the antagonism of the contractile effect of kinins in the rabbit isolated aortic preparation. Acetylation of the alpha-amino group of the N-terminal Lys residue provided an excellent protection from the degradation by rabbit blood plasma. This and the inhibitory effect of amastatin on the metabolism of Lys[Leu8]des-Arg9-BK indicated that aminopeptidase M (AmM) is the major route of inactivation for this class of peptides in plasma. Various other modifications afforded a more or less complete resistance to purified angiotensin I converting enzyme (ACE). One analog, Ac-Lys[MeAla6, Leu8]des-Arg9-BK, was found resistant to the above-mentioned enzymes and to neutral endopeptidase-24.11 extracted from rabbit kidney. This antagonist, although 100 times less potent than the parent peptide Lys[Leu8]des-Arg9-BK on the rabbit aortic preparation, was equipotent in vivo against the hypotensive effect of a B1 agonist in lipopolysaccharide-treated rabbits, and unlike the original compound, its effect was persistent after the end of the infusion. Ac-Lys[MeAla6, Leu8]des-Arg9-BK does not antagonize B2 receptors either in vitro or in vivo.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Development and in vivo evaluation of metabolically resistant antagonists of B1 receptors for kinins. 839 50

The mechanism by which bradykinin induces catecholamine release from neural tissues was investigated in two experimental models of rat origin. The rat phaeochromocytoma cell line PC12 was used to identify the subtype of bradykinin receptors involved in the stimulation of noradrenaline secretion and to compare the effects of three different B2-antagonists. An increase of catecholamine release induced by bradykinin in vivo could be confirmed by measuring plasma levels in pithed spontaneously hypertensive rats (SHR) during electric preganglionic stimulation of the spinal cord. In this whole animal model, the effects of inhibition of both uptake and alpha 2-adrenoceptors on plasma levels of noradrenaline and adrenaline were studied as well as the potentiation of exogenous bradykinin by inhibition of angiotensin I-converting enzyme and neutral endopeptidase. The receptor subtypes involved (i.e. B1 or B2) were characterized by application either of HOE 140 or desArg9-[Leu8]-bradykinin respectively. In PC12 cells bradykinin provoked a prominent increase of noradrenaline release at low concentrations (concentration required for 50% of the maximum response 1 nM), whereas the B1-agonist desArg9-bradykinin was only effective at concentrations higher than 30 microM. The effects of both kinins could be blocked by the B2-specific antagonist HOE 890307 which, like HOE 140, exerted no agonistic effect of its own. As has been shown in other neural cells, the B2-specific antagonist [Thi5,8, D-Phe7]-bradykinin only acted as a low-affinity agonist without any antagonistic effects. In experiments where the intention was to induce B1-receptor expression either by angiotensin I-converting enzyme inhibition or lipopolysaccharide application, no alteration of the secretory response of PC12 cells to bradykinin or desArg9-bradykinin could be shown. In pithed SHR, infusion of bradykinin (up to 1200 ng/min/kg) did not enhance stimulation-dependent release of noradrenaline or adrenaline. After pretreatment of the rats with ramipril bradykinin became effective and its effects were further potentiated by the concomitant application of phosphoramidon. B2-antagonism by HOE 140 abolished the bradykinin-induced release of noradrenaline and reduced the effect on plasma adrenaline. The B1-specific antagonist desArg9-[Leu8]-bradykinin was unable to diminish the stimulatory effects of bradykinin and instead brought about an increase of plasma adrenaline levels. In conclusion, bradykinin stimulates release of catecholamines from PC12 cells, peripheral sympathetic neurons and chromaffine cells by activation of ganglionic or presynaptic B2-receptors. The adrenal medulla and PC12 cells appear to be highly susceptible not only to stimulation by bradykinin, but also to non-specific stimulatory effects of certain kinin-antagonists.
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PMID:Bradykinin increases catecholamine release via B2 receptors. 899 50

We report a 70-year-old Japanese man who had splenic lymphoma with villous lymphocytes and a complex chromosomal abnormality. No monoclonal gammopathy was present. The peripheral blood film showed lymphocytes with thin and short villi arising from one or two poles of the cells. These cells were negative for tartrate-resistant acid phosphatase stain. Immunophenotyping of peripheral blood lymphocytes showed moderate to strong expression of surface membrane IgM, IgD, IgA, and lambda as well as CD19, CD20, CD21, CD24, and HLA-DR. In addition, there was weak CD5, CD22, and CD25 expression, but no CD10, CD11c, CD23, CD38, or B-ly-7 expression. All 20 metaphases obtained from peripheral blood cells cultured for 5 days with lipopolysaccharide showed an abnormal karyotype: 47, XY, +der(3) t(3; 13) (q26; q12) inv(3) (?), t(7; 14), (q21; q11), der(13) t(3; 13) (q26; q12). Our patient followed a relatively benign clinical course and splenectomy was not performed.
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PMID:[Splenic lymphoma with villous lymphocytes and complex chromosomal abnormality]. 924 32

The cerebral deposition of amyloid beta-peptide (A beta) is a histopathological characteristic of Alzheimer's disease. Because an impaired clearance of A beta might be involved in the disease, we investigated the proteolytic degradation of synthetic A beta (40-residue peptide) in cultures of glial cells and characterized a protease involved. Whereas rat astrocytes had a very low degradation capacity, cultivated rat microglia cells cleaved A beta. Microglia activity was considerably enhanced by stimulation with lipopolysaccharide and to a lesser extent by phorbol esters. Most of the A beta-degrading activity was released into the medium. By use of selective inhibitors the protease was characterized as a metalloprotease of approximately 200 kDa that was different from neutral endopeptidase (a neuropeptide-degrading enzyme), matrix metalloproteases, or macrophage elastase. Its activity was efficiently reduced by four hydroxamic acid-based zinc-metalloprotease inhibitors that have been shown to inhibit membrane protein secretases (disintegrins). We conclude that activated microglia cells might impair amyloid plaque formation by release of a metalloprotease that degrades soluble A beta, before polymerization.
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PMID:Proteolytic degradation of Alzheimer's disease amyloid beta-peptide by a metalloproteinase from microglia cells. 945 67

A number of studies using endothelin (ET) receptor antagonists support the participation of ETs in a variety of cardiovascular, renal, and other disorders. It has also been established that a number of cytokines, which are released in such diseases, modulate the expression and production of ETs and thus activate the ET system. This effect may represent one pathway by which these inflammatory mediators operate. By regulating endothelin-converting enzyme (ECE) activities, and thus ET synthesis, one can potentiate or attenuate the production of ETs and the receptor affinity/density in such pathologic conditions. Here, the stimulated (lipopolysaccharide or interleukin-1 beta) production of ET-1 from guinea pig tracheal epithelial cells was abolished by CGS 26303 or CGS 26393, two ECE/neutral endopeptidase (NEP) inhibitors, but was unaffected by CGS 24592, a specific NEP inhibitor. Therefore, such dual, and eventually selective ECE inhibitors are effective agents to prevent the stimulated production of ETs.
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PMID:Effects of dual endothelin-converting enzyme/neutral endopeptidase inhibitors, CGS 26303 and CGS 26393, on lipopolysaccharide or interleukin-1 beta-stimulated release of endothelin from guinea pig tracheal epithelial cells. 959 86

The lethal toxin of Bacillus anthracis consists of two proteins, PA and LF, which together induce lethal effects in animals and cause macrophage lysis. LF is a zinc-endopeptidase which cleaves two mitogen-activated protein kinase kinases (MAPKKs), Mek1 and Mek2, within the cytosol. Here, we show that also MKK3, another dual-specificity kinase that phosphorylates and activates p38 MAP kinase, is cleaved by LF in macrophages. No direct correlation between LF-induced cell death and cleavage of these MAPKKs was found in macrophage cell lines and primary peritoneal cells exhibiting different sensitivity to LF. However, we present the first evidence that sublytic doses of LF cleave Meks and cause a substantial reduction in the production of NO and tumour necrosis factor-alpha induced by lipopolysaccharide/interferon gamma. We suggest that this effect of LF is relevant during the first stages of B. anthracis infection, when a reduction of the inflammatory response would permit growth and diffusion of the bacterium.
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PMID:Anthrax lethal factor cleaves MKK3 in macrophages and inhibits the LPS/IFNgamma-induced release of NO and TNFalpha. 1058 Jan 19


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