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)

A Limulus intracellular coagulation inhibitor, designated LICI, was isolated from hemocytes of the Japanese horseshoe crab (Tachypleus tridentatus), using three steps of chromatography, including dextran sulfate-Sepharose CL-6B, Sephacryl S-200, and Mono S. LICI is a single-chain glycoprotein with an apparent M(r) = 48,000 estimated by SDS-polyacrylamide gel electrophoresis. It blocks the amidolytic activities of Limulus lipopolysaccharide-sensitive serine protease, factor C, by forming a covalent 1:1 complex with the protease. The second-order rate constant for inhibition of factor C was 2.5 x 10(6) M-1 s-1 at 37 degrees C. LICI also inhibited human alpha-thrombin, rat salivary kallikrein, bovine plasmin, and trypsin but not Limulus clotting enzyme, Limulus factor B, bovine factor Xa, human factor XIa, human tissue plasminogen activator, human urokinase, chymotrypsin, elastase, and papain. Glycosaminoglycans such as heparin and heparan sulfate had no effect on the inhibitory activity. A cDNA coding for LICI was isolated from a hemocyte cDNA library. The open reading frame of the 1,257-base pair cDNA codes for the mature protein of 394 amino acids, of which 223 residues were confirmed by amino acid sequence analysis. LICI shows significant sequence identities to members of the serpin superfamily, such as human plasminogen activator inhibitor type 2 (40%) and human monocyte/neutrophil elastase inhibitor (39%). LICI contains a putative reactive site, -Arg-Ser-, at the corresponding position present in several inhibitors of the serpin superfamily. The subcellular localization, determined using an anti-LICI polyclonal antibody, indicated that LICI colocates with the Limulus serine protease zymogens in large granules in the hemocyte.
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PMID:A Limulus intracellular coagulation inhibitor with characteristics of the serpin superfamily. Purification, characterization, and cDNA cloning. 827 48

A procedure using enzyme-linked immunosorbent assays for the assessment of complement function has been evaluated. The sera investigated were incubated in microtiter plates with solid-phase complement activators. Human polyclonal IgG or monoclonal IgM were used for classical activation pathway assays and Salmonella typhosa lipopolysaccharide (LPS) for alternative activation pathway assays. The analysis focussed on deposition of C9 and properdin as detected with enzyme-conjugated antibodies. In an attempt to avoid spurious results due to rheumatoid factors in patient sera, monoclonal mouse and chicken antibodies were unsuccessfully tested as indicator reagents in the assay with solid-phase IgG. However, the use of solid-phase IgM as an activator completely circumvented the influence of rheumatoid factors. With solid-phase IgG or IgM, properdin deposition occurred in the absence of factor D. A combination of assays is suggested for diagnostic purposes: IgM-coated plates with detection of bound C9 and properdin for the classical pathway and LPS-coated plates with detection of bound properdin for the alternative pathway. The procedure distinguished between defects of the classical activation pathway (C1, C4, C2), the alternative activation pathway (C3, factor B, factor D, properdin) and the terminal components (C5-C9). This analytical approach may be useful for detection of inherited complement deficiency and the assessment of complement function in acquired complement deficiency states.
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PMID:New procedure for the detection of complement deficiency by ELISA. Analysis of activation pathways and circumvention of rheumatoid factor influence. 828 79

This study describes activation of serum complement by lipoteichoic acid (LTA) from Streptococcus mutans OMZ 176, while in solution. Serum from 16 healthy students was taken. Test samples were incubated with increasing doses (1-5,000 micrograms/ml) of LTA or lipopolysaccharide (LPS) from Escherichia coli 0111:B4 for 1 h at 37 degrees C; then assayed for degradation of C3, C4 or factor B by crossed immunoelectrophoresis. Each preparation caused a significant (p < 0.05) dose-dependent conversion of C3. The response curves obtained were not statistically different. LPS was a stronger activator of the alternative pathway than LTA, as judged from analysis of C3 degradation in the presence of Mg2+/EGTA, and from their effects on factor B cleavage. LTA caused, however, pronounced alterations in the shape of C4 precipitation in the gels. Functional (hemolytic) assays showed that, when tested at 200 micrograms/ml, LTA and LPS triggered significant (p < 0.05) consumptions of both classical and alternative pathway proteins. LPS was a significantly (p < 0.05) stronger activator than LTA. Apparently, the C3 degradation found for this LTA involved the alternative pathway to a small extent; thus some other mechanism of fluid-phase C3 cleavage seemed also to be operative.
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PMID:Effects of a streptococcal lipoteichoic acid on complement activation in vitro. 845 83

We have shown by combining lipopolysaccharide (LPS) extracted and purified from Francisella tularensis live vaccine strain (LVS) with normal complement and back titrating with sensitised sheep red blood cells that the LPS activates complement. Deionising the LPS and converting it into the single salt forms of pyridine, ethanolamine and triethylamine altered the ability to activate complement according to the apparent molecular weight due to aggregation. Francisella tularensis LPS activated complement deficient in a component of the alternative pathway (factor B) but failed to activate complement deficient in a component of the classical pathway (C1q). In addition normal complement suspended in ethyleneglycol-bis-(beta-aminoethyl ether) N,N,N',N'-tetraacetic acid (EGTA) which inactivates the classic pathway was not activated by LPS, and we concluded that the LPS activates complement predominantly via the classical pathway. LPS bound to specific monoclonal antibodies activated complement more than LPS alone. An anti-core monoclonal antibody was approximately tenfold more potent when bound to LPS then an anti-O side chain monoclonal antibody in activating complement.
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PMID:Activation of the complement system by Francisella tularensis lipopolysaccharide. 851 May 68

Structural and serological studies were performed with the lipopolysaccharide (LPS) expressed by Escherichia coli K12 strains No. 30 and No. 64, into which cosmid clones derived from Vibrio cholerae O1 NIH 41 (Ogawa) and NIH 35A3 (Inaba) had been introduced, respectively. The two recombinant strains, No. 30 (Ogawa) and No. 64 (Inaba), produced LPS that included, in common, the O-polysaccharide chain composed of an alpha (1-->2)-linked N-(3-deoxy-L-glycero-tetronyl)-D-perosamine (4-amino-4,6-dideoxy-D-manno-pyranose) homopolymer attached to the core oligosaccharide of the LPS of E. coli K12. Structural analysis revealed the presence of N-(3-deoxy-L-glycero-tetronyl)-2-O-methyl-D-perosamine at the non-reducing terminus of the O-polysaccharide chain of LPS from No. 30 (Ogawa) but not from No. 64 (Inaba). Serological analysis revealed that No. 30 (Ogawa) and No. 64 (Inaba) LPS were found to share the group antigen factor A of V. cholerae O1. They were distinguished by presence of the Ogawa antigen factor B [co-existing with relatively small amounts of the Inaba antigen factor (c)] in the former LPS and the Inaba antigen factor C in the latter LPS. It appears, therefore, that No. 30 (Ogawa) and No. 64 (Inaba) have O-antigenic structures that are fully consistent with the AB(c) structure for the Ogawa and the AC structure for the Inaba O-forms of V. cholerae O1, respectively. Thus, the present study clearly confirmed our previous finding that the Ogawa antigenic factor B is substantially related to the 2-O-methyl group at the non-reducing terminus of the alpha (1-->2)-linked N-(3-deoxy-L-glycero-tetronyl)-D-perosamine homopolymer that forms the O-polysaccharide chain of LPS of V. cholerae O1 (Ogawa).
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PMID:Lipopolysaccharides of Escherichia coli K12 strains that express cloned genes for the Ogawa and Inaba antigens of Vibrio cholerae O1: identification of O-antigenic factors. 890 6

We demonstrate in vitro expression of complement components, i.e. C3, factor H (FH), factor B (FB), C4, C1-inhibitor (C1-inh), C1q, C5, C6, C7 and C9, by four human neuroblastoma cell lines IMR32, SKNSH, SH-SY5Y and KELLY. Activating proteins C4, C9 and C1q, and regulatory proteins FH and C1-inh were produced constitutively by the four cell lines. C3, C6 and FB were mainly produced by SKNSH and SH-SY5Y. Western blot experiments showed that secreted proteins were structurally similar to their serum counterparts. An additional polypeptide of 43 kDa with FH immunoreactivity was detected, which could correspond to the N-terminal truncated form found in plasma. Regulation of complement expression by inflammatory cytokines, lipopolysaccharide and dexamethasone was tested in vitro. These factors had no significant effects on activating synthesis of components C3, FB and C4, but expression of regulating components C1-inh and FH was strongly increased particularly by IFN-gamma and tumor necrosis factor-alpha. The rate of synthesis of complement components was dependent on the differentiation of neuroblastoma cells. This effect of differentiation was also observed on normal rat neurons. Rat cerebellar granule cells constitutively expressed mRNA for C4 and C1q, but expression of C3 mRNA was induced by differentiation. This study shows that neurons could be another local source of complement in the brain, besides astrocytes and microglia. Human neuroblastoma cell lines can constitute an interesting model to analyze complement biosynthesis by human neurons. Local complement expression by neurons in vivo may be implicated in some physio-pathological processes.
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PMID:Expression of a complete and functional complement system by human neuronal cells in vitro. 1088 13

The 155-kd soluble complement regulator factor H (FH), which consists of 20 short consensus repeats, increases the affinity of complement factor I (FI) for C3b by about 15 times. In addition to its cofactor activity, it prevents factor B from binding to C3b and promotes the dissociation of the C3bBb complex. The primary site of synthesis of FH, as well as of FI, is the liver, but the cell types responsible for the hepatic synthesis of both factors have not yet been clearly identified. In contrast to FI-mRNA, which was detectable only in hepatocytes (HC), FH-specific mRNA was identified in both HC and Kupffer cells (KC). As calculated for equal amounts of mRNA isolated from both cell types, FH-specific mRNA was found to be nearly 10-fold higher in KC than in HC, leading to the conclusion that KC are an abundant source of FH. Of the investigated proinflammatory cytokines IL-6, TNF-alpha, IL-1beta, and IFN-gamma, only IFN-gamma up-regulated FH-specific mRNA up to 6-fold in both primary HC and KC. This was also demonstrable on the protein level. However, FH-specific mRNA was not inducible in the rat hepatoma cell line H4IIE, which did not express FH-specific mRNA and could not be up-regulated in FAO cells that constitutively expressed FH-specific mRNA. This demonstrates that transformed cell lines do not reflect FH regulation in isolated primary HC. In addition to IFN-gamma, the endotoxin lipopolysaccharide (LPS) up-regulated FH-specific mRNA nearly 10-fold in KC after stimulation at concentrations of 10 or 1 ng/ml. In contrast, concentrations of up to 2 microg LPS/ml did not show any effect on HC. Our data suggest that LPS does not regulate the expression of FH in HC.
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PMID:Constitutive expression and regulation of rat complement factor H in primary cultures of hepatocytes, Kupffer cells, and two hepatoma cell lines. 1185 May 31

Bordetella pertussis must survive the defenses of the human respiratory tract including the complement system. The BrkA (Bordetella resistance to killing) protein prevents killing by the antibody-dependent classical pathway. In this study, the ability of B. pertussis to activate the human complement cascade by other pathways was examined. B. pertussis was not killed in serum depleted of C2, however serum depleted for factor B killed B. pertussis as efficiently as intact serum, suggesting complement activation occurred exclusively by the classical pathway. B. pertussis was not killed by serum depleted of antibody, suggesting the bacteria fail to activate the antibody-independent branches of the classical pathway, including the mannose binding lectin pathway. Mutants lacking the terminal trisaccharide of lipopolysaccharide retained the complement-resistant phenotype, suggesting this structure does not influence activation of complement.
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PMID:Activation of the complement cascade by Bordetella pertussis. 1267 Jun 91

The purple sea urchin, Strongylocentrotus purpuratus, possesses a non-adaptive immune system including elements homologous to C3 and factor B (Bf) of the vertebrate complement system. SpBf is composed of motifs typical of the Bf/C2 protein family. Expression of Sp152 (encodes SpBf) was identified in the phagocyte type of coelomocyte in addition to gut, pharynx and esophagus, which may have been due to the presence of these coelomocytes in and on all tissues of the animal. Sp152 expression in coelomocytes was constitutive and non-inducible based on comparisons between pre- and post-injection with lipopolysaccharide or sterile seawater. The pattern of five short consensus repeats (SCRs) in SpBf has been considered ancestral compared to other deuterostome Bf/C2 proteins that contain either three or four SCRs. Three alternatively spliced messages were identified for Sp152 and designated Sp152Delta1, Sp152Delta4, and Sp152Delta1+Delta4, based on which of the five SCRs were deleted. Sp152Delta4 had an in-frame deletion of SCR4, which would encode a putative SpBfDelta4 protein with four SCRs rather than five. On the other hand, both Sp152Delta1 and Sp152Delta1+Delta4 had a frame-shift that introduced a stop codon six amino acids downstream of the splice site for SCR1, and would encode putative proteins composed only of the leader. Comparisons between the full-length SpBf and its several splice variants with other Bf/C2 proteins suggested that the early evolution of this gene family may have involved a combination of gene duplications and deletions of exons encoding SCRs.
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PMID:Constitutive expression and alternative splicing of the exons encoding SCRs in Sp152, the sea urchin homologue of complement factor B. Implications on the evolution of the Bf/C2 gene family. 1544 41

Complement, a complex protein system, plays an essential role in host defense through bacterial lysis, stimulation of phagocytosis, recruitment of immune cells to infected tissue, and promotion of the inflammatory response. Although complement is most well-characterized in serum, complement activity is also present in the lung. Here we further characterize the complement system in the normal and inflamed lung. By Western blot, C5, C6, and factor I were detected in bronchoalveolar lavage (BAL) at lower levels than in serum, whereas C2 was detected at similar levels in BAL and serum. C4 binding protein (C4BP) was not detectable in BAL. Exposure to lipopolysaccharide (LPS) elevated levels of C1q, factor B, C2, C4, C5, C6, and C3 in human BAL and C3, C5, and factor B in mouse and rat BAL. Message for C1q-B, C1r, C1s, C2, C4, C3, C5, C6, factor B, and factor H, but not C9 or C4BP, was readily detectable by RT-PCR in normal mouse lung. Exposure to LPS enhanced factor B expression, decreased C5 expression, and did not affect C1q-B expression in mouse and rat lung. BAL from rats exposed to LPS had a greater ability to deposit C3b onto bacteria through complement activation than did BAL from control rats. In summary, these data demonstrate that complement levels, expression, and function are altered in acute lung injury and suggest that complement within the lung is regulated to promote opsonization of pathogens and limit potentially harmful inflammation.
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PMID:Complement levels and activity in the normal and LPS-injured lung. 1707 22


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