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

Both NOD2/CARD15 alleles are mutated in approximately 10% of Crohn's disease patients, causing loss of functional responses to low-dose muropeptide agonists. We hypothesized that NOD2 mutations may also impair NOD1/CARD4 responses, supported by data suggesting NOD2 1007fs/1007fs patients had reduced responses to a putative NOD1 agonist, diaminopimelic acid-containing muramyl tripeptide (M-TriDAP). We measured peripheral blood mononuclear cell (n = 8 NOD2 wild type, n = 4 1007fs/1007fs, n = 6 702Trp/1007fs, n = 5 702Trp/702Trp, n = 3 908Arg/1007fs) responses to NOD1 agonists alone (IL-8/TNF-alpha), and agonist enhancement of lipopolysaccharide (LPS) responses (IL-1beta). Significant responses were seen with M-TriDAP at 10 nM (as with NOD2 agonists), but only at > or =100 nM with FK565/TriDAP. M-TriDAP induced IL-8/TNF-alpha secretion, and enhancement of LPS IL-1beta responses was significantly reduced between NOD2 double mutation carriers versus healthy controls, whereas there was no difference with FK565 or TriDAP stimulation, or between 1007fs/1007fs cells and other genotypes. M-TriDAP contains both NOD1 (gamma-D-Glu-mesoDAP) and NOD2 (MurNAc-L-Ala-D-Glu) minimal structures whereas FK565/TriDAP contain only NOD1 activating structures. M-TriDAP has dual NOD1/NOD2 agonist activity in primary cells, possibly due to different intracellular peptidoglycan processing compared to the HEK293 cell system typically used for agonist specificity studies. Responses to specific NOD1 agonists are unaffected by NOD2 genotype, suggesting independent action of the NOD1 and NOD2 pathways.
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PMID:Normal responses to specific NOD1-activating peptidoglycan agonists in the presence of the NOD2 frameshift and other mutations in Crohn's disease. 1701 77

NOD1 (Card4) and NOD2 (Card15) are thought to be responsible for cytoplasmic defense against bacterial entry. To gain further knowledge about how their expressions are regulated in murine macrophages, we investigated the expression of NOD1 and NOD2 mRNAs after stimulation with various endotoxins, lipopolysaccharide, lipoteichoic acid and peptidoglycan. In macrophage RAW264.7 cells, the first and second rises in NOD1 and NOD2 mRNAs were observed at 2 hr and at 8-12 hr after endotoxin treatment. Increases in NOD1 and NOD2 mRNAs at 2 hr in lipopolysaccharide-treated RAW264.7 cells were reduced with the use of NF-kappaB inhibitor, caffeic acid phenethyl ester. In RAW264.7 cells, lipopolysaccharide-induced increases in NOD1 and NOD2 mRNAs were inhibited with anti-TLR4 antibody, and partially reduced in peritoneal macrophages obtained from TLR4-deficient mice. Furthermore, NOD1 and NOD2 mRNA expressions in RAW264.7 cells were increased by the treatment with proinflammatory cytokines, tumor necrosis factor-alpha (TNF-alpha), interleukin-1beta (IL-1beta), or IL-6. In TNF-alpha deficient macrophages, the expression of NOD molecules was minimal at 12 hr, and the second rise in NOD mRNA seen in lipopolysaccharide-treated RAW264.7 cells was inhibited with anti-TNF-alpha, but not with anti-IL-1beta or anti-IL-6 antibody. These observations suggest that immediate response of NODs to endotoxins could result from NF-kappaB activation via TLR signaling, whereas the second rise in NOD mRNAs might have resulted from TNF-alpha production possibly through NF-kappaB, TLR, and/or NOD signalings.
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PMID:Up-regulation of NOD1 and NOD2 through TLR4 and TNF-alpha in LPS-treated murine macrophages. 1675 90

Nucleotide-binding oligomerization domain (NOD) protein 1 (NOD1) and NOD2 are pathogen recognition receptors that sense breakdown products of peptidoglycan (PGN) (muropeptides). It is shown that a number of these muropeptides can induce tumor necrosis factor alpha (TNF-alpha) gene expression without significant TNF-alpha translation. This translation block is lifted when the muropeptides are coincubated with lipopolysaccharide (LPS), thereby accounting for an apparently synergistic effect of the muropeptides with LPS on TNF-alpha protein production. The compounds that induced synergistic effects were also able to activate NF-kappaB in a NOD1- or NOD2-dependent manner, implicating these proteins in synergistic TNF-alpha secretion. It was found that a diaminopimelic acid (DAP)-containing muramyl tetrapeptide could activate NF-kappaB in a NOD1-dependent manner, demonstrating that an exposed DAP is not essential for NOD1 sensing. The activity was lost when the alpha-carboxylic acid of iso-glutamic acid was modified as an amide. However, agonists of NOD2, such as muramyl dipeptide and lysine-containing muramyl tripeptides, were not affected by amidation of the alpha-carboxylic acid of iso-glutamic acid. Many pathogens modify the alpha-carboxylic acid of iso-glutamic acid of PGN, and thus it appears this is a strategy to avoid recognition by the host innate immune system. This type of immune evasion is in particular relevant for NOD1.
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PMID:Modification of the structure of peptidoglycan is a strategy to avoid detection by nucleotide-binding oligomerization domain protein 1. 1714 40

Pathogens are sensed by pattern recognition receptors (PRRs), which are germ line-encoded receptors, including transmembrane Toll-like receptors (TLRs) and cytosolic nucleotide oligomerisation domain (NOD) proteins, containing leucine-rich repeats (NLRs). Activation of PRRs by specific pathogen-associated molecular patterns (PAMPs) results in genomic responses in host cells involving activation transcription factors and the induction of genes. There are now at least 10 TLRs in humans and 13 in mice, and 2 NLRs (NOD1 and NOD2). TLR signalling is via interactions with adaptor proteins including MyD88 and toll-receptor associated activator of interferon (TRIF). NOD signalling is via the inflammasome and involves activation of Rip-like interactive clarp kinase (RICK). Bacterial lipopolysaccharide (LPS) from Gram-negative bacteria is the best-studied PAMP and is activated by or 'sensed' by TLR4. Lipoteichoic acid (LTA) from Gram-positive bacteria is sensed by TLR2. TLR4 and TLR2 have different signalling cascades, although activation of either results in symptoms of sepsis and shock. This review describes the rapidly expanding field of pathogen-sensing receptors and uses LPS and LTA as examples of how these pathways parallel and diverge from each other. The role of pathogen-sensing pathways in disease is also discussed.
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PMID:Critical role of toll-like receptors and nucleotide oligomerisation domain in the regulation of health and disease. 1753 71

Genetic factors, Helicobacter pylori infection, salt over-uptake, decreased vegetable/fruit consumption, smoking, and metabolic syndrome are risk factors of human gastric cancer. Germline mutations of CDH1 gene, and SNPs of PTPN11 (SHP2), TLR4, IL1B, TNFA, BMP6, GDF15 and RUNX3 genes are associated with gastric cancer. Helicobacter pylori activates CagA-SHP2-ERK and peptidoglycan-NOD1-NFkappaB signaling cascades in gastric epithelial cells using type IV secretion system, and also TRAF6-MAP3K7-NFkappaB and TRAF6-MAP3K7-AP-1 signaling cascades in epithelial and immune cells through lipopolysaccharide recognition by TLR2 or TLR4. IL-1beta, IL-6, IL-8, TNFalpha and IFNgamma are elevated in gastric mucosa with Helicobacter pylori infection. IL-6 and TNFalpha induce upregulation of WNT5A and WNT10B, respectively. WNT signals are transduced to beta-catenin-TCF/LEF, RhoA, JNK, PKC, NFAT, and NLK signaling cascades. WNT-beta-catenin-TCF/LEF signaling induces upregulation of MYC, CCND1, WISP1, FGF20, JAG1 and DKK1 genes. Notch signals are transduced to CSL-NICD-MAML and NFkappaB signaling cascades. FGF signals are transduced to ERK, PI3K-AKT, PKC, and NFAT signaling cascades. Helicobacter pylori infection induces SHH upregulation in parietal cell lineage, while BMP signals induce IHH upregulation in pit cell lineage. Hedgehog signals induce upregulation of GLI1, PTCH1, CCND2, FOXL1, JAG2 and SFRP1 genes. JAG1 and JAG2 activate Notch signaling, while DKK1 and SFRP1 inhibit WNT signaling. Stem cell signaling network, consisting of WNT, Notch, FGF, Hedgehog and BMP signaling pathways, is activated during chronic Helicobacter pylori infection. Epigenetic silencing of SFRP1 gene occurs in the earlier stage of carcinogenesis in the stomach, while amplification and overexpression of FGFR2 gene in the later stage. Dysregulation of the stem cell signaling network due to the accumulation of germline mutation, SNP, Helicobacter pylori infection, epigenetic change and genetic alteration gives rise to gastric cancer. SNP typing and custom-made microarray analyses on genes encoding stem cell signaling molecules could be utilized for the personalized medicine.
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PMID:Dysregulation of stem cell signaling network due to germline mutation, SNP, Helicobacter pylori infection, epigenetic change and genetic alteration in gastric cancer. 1756 83

Pattern-recognition receptors (PRRs) are important components of the innate immune system, enabling early detection of infection. Defective PRR function has been implicated in several infectious and immune-mediated diseases of human beings, including Crohn's disease (CD). Anal furunculosis (AF) is an immune-mediated disease which primarily occurs in German shepherd dogs (GSD) and could result from a similar type of PRR dysfunction. The aim of the current study was to investigate canine PRR responses in vitro and to test the hypothesis that these were altered in AF-affected GSD. The pattern-recognition receptors TLR1, TLR2, TLR4, TLR6, TLR9, NOD1 (nucleotide-binding oligomerisation domain) and NOD2 were evaluated in the DH82 canine monocyte/macrophage cell line. These cells were found to express mRNA for all the selected PRRs with TLR2 mRNA the most and TLR5 mRNA the least abundant. A similar pattern of expression was found in canine blood-derived monocyte/macrophages. Stimulation of DH82 cells and blood-derived monocyte/macrophages using specific PRR-ligands, resulted in expression of pro-inflammatory cytokine mRNA. Quantification of TNFalpha mRNA and protein secretion from stimulated cells demonstrated variable responses with lipopolysaccharide (TLR4 ligand) and PAM(3)CSK4 (TLR1/2 ligand) proving to be the most potent and CpG DNA (TLR9 ligand) the least potent. Comparing PRR responses in blood-derived monocyte/macrophages from healthy blood-donor dogs with those from AF-affected GSD showed a deficiency in the latter in response to LD-MDP (NOD2 ligand) at the mRNA level but not at the protein level. It is possible that dysfunctional NOD2 responses by cells of the monocyte/macrophage lineage are involved in the pathogenesis of AF.
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PMID:Pattern-recognition receptor mRNA expression and function in canine monocyte/macrophages and relevance to canine anal furunuclosis. 1847 95

Lyme borreliosis is a spirochetal infection caused by the Borrelia burgdorferi sensu lato complex that can proceed towards an inflammatory joint manifestation known as Lyme arthritis. Production of chemokines orchestrating neutrophil infiltration is supposed to be key to early arthritic pathogenesis. Using PMA-differentiated macrophage-like THP-1 (mTHP-1) cells we identified by antibody array methodology or mRNA analysis IL-8, GRO-alpha, NAP-2, and SDF-1alpha as being among those chemokines that are upregulated by bacterial lysates obtained from B. burgdorferi. Based on these observations, we set out to characterize in detail mechanisms mediating IL-8 release in this cellular model. TLR2 blocking antibodies, analysis of p65 translocation, and electromobility-shift analysis revealed activation of the TLR2/NF-kappaB axis by B. burgdorferi. The functional importance of this pathway was substantiated by suppression of IL-8 after inhibition of IkappaB kinase. Notably, MAP kinases, specifically the MEK1/2-ERK1/2 pathway, were essential for IL-8 secretion. Those data were confirmed by using freshly isolated adherent peripheral blood mononuclear cells. On the contrary, B. burgdorferi-induced IL-8 in mTHP-1 was unlikely related to flagellin, alpha3beta1-integrin signaling, lipopolysaccharide, bacterial DNA, NOD1/NOD2 agonists, or to intermediate production of IL-1beta and TNF-alpha. Induction of IL-8 by B. burgdorferi was not due to amplification of constitutive AP-1 DNA-binding activity detectable in mTHP-1 cells. Data presented herein validate that TLR2, particularly on mTHP-1 cells, holds a central position in mediating IL-8 secretion associated with extracellular B. burgdorferi and beyond that suggest inhibition of IkappaB kinase and MEK1/2 kinases as promising pharmacological strategies aiming at IL-8 in early Lyme arthritis.
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PMID:Systematic analysis highlights the key role of TLR2/NF-kappaB/MAP kinase signaling for IL-8 induction by macrophage-like THP-1 cells under influence of Borrelia burgdorferi lysates. 1857 57

Helicobacter spp. represent a proportionately small but significant component of the normal intestinal microflora of animal hosts. Several of these intestinal Helicobacter spp. are known to induce colitis in mouse models, yet the mechanisms by which these bacteria induce intestinal inflammation are poorly understood. To address this question, we performed in vitro co-culture experiments with mouse and human epithelial cell lines stimulated with a selection of Helicobacter spp., including known pathogenic species as well as ones for which the pathogenic potential is less clear. Strikingly, a member of the normal microflora of rodents, Helicobacter muridarum, was found to be a particularly strong inducer of CXC chemokine (Cxcl1/KC, Cxcl2/MIP-2) responses in a murine intestinal epithelial cell line. Time-course studies revealed a biphasic pattern of chemokine responses in these cells, with H. muridarum lipopolysaccharide (LPS) mediating early (24-48 h) responses and live bacteria seeming to provoke later (48-72 h) responses. H. muridarum LPS per se was shown to induce CXC chemokine production in HEK293 cells stably expressing Toll-like receptor 2 (TLR2), but not in those expressing TLR4. In contrast, live H. muridarum bacteria were able to induce NF-kappaB reporter activity and CXC chemokine responses in TLR2-deficient HEK293 and in AGS epithelial cells. These responses were attenuated by transient transfection with a dominant negative construct to NOD1, and by stable expression of NOD1 siRNA, respectively. Thus, the data suggest that both TLR2 and NOD1 may be involved in innate immune sensing of H. muridarum by epithelial cells. This work identifies H. muridarum as a commensal bacterium with pathogenic potential and underscores the potential roles of ill-defined members of the normal flora in the initiation of inflammation in animal hosts. We suggest that H. muridarum may act as a confounding factor in colitis model studies in rodents.
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PMID:A commensal Helicobacter sp. of the rodent intestinal flora activates TLR2 and NOD1 responses in epithelial cells. 1940 79

Nuclear oligomerization domains (NODs) are cytosolic pattern recognition receptors (PRRs) to detect bacterial component. In this study, the molecular cloning and genomic characterization of grass carp NOD1 (gcNOD1) and grass carp NOD2 (gcNOD2) were reported. The complete open reading frame of gcNOD1 contains 2814 bp, encoding a 937-amino acid polypeptide. The gcNOD2 cDNA sequence encodes 982-amino acid polypeptide. Both gcNOD1 and gcNOD2 possess three conserved domains: carboxy terminal leucine rich repeat (LRR) domains, a central NOD, NBS or NACHT domain, and an amino terminal CARD domain (two in the case of NOD2). At the genomic level, gcNOD1 consists of 11 exons, with 10 intervening introns, spanning approximately 9 kb of genomic sequence. Whereas gcNOD2 has a length of approximately 5 kb with 9 intervening introns. Real time PCR analysis showed gcNOD1 and gcNOD2 were ubiquitously expressed in adult tissues. The highest transcript level of gcNOD1 was detected in brain, but in head kidney for gcNOD2. Grass carp reovirus significantly induced the expression of gcNOD1 and gcNOD2 in spleen (from days 1 to 6). However, expression profiles differed in time course response. Induction experiments with lipopolysaccharide (LPS), peptidoglycan (PGN) and polyI:C revealed the differential expression and regulation of gcNOD1 and gcNOD2 in blood, head kidney, trunk kidney and spleen. All these data suggest a potential role of NOD1 and NOD2 in fish innate immune protection to bacterial and virus infections.
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PMID:Molecular characterization and expression analysis of nuclear oligomerization domain proteins NOD1 and NOD2 in grass carp Ctenopharyngodon idella. 1976 92

Human beta-defensins (hBDs) contribute to the protection of the respiratory tract against pathogens. It is reasonable to postulate that pathogens have developed countermeasures to resist them. Klebsiella pneumoniae capsule polysaccharide (CPS), but not the lipopolysaccharide O antigen, mediated resistance against hBD1 and hBD2. hBD3 was the most potent hBD against Klebsiella. We investigated the possibility that as a strategy for survival in the lung, K. pneumoniae may not activate the expression of hBDs. Infection of A549 and normal human bronchial cells with 52145-Deltawca(K2), a CPS mutant, increased the expression of hBD2 and hBD3. Neither the wild type nor the lipopolysaccharide O antigen mutant increased the expression of hBDs. In vivo, 52145-Deltawca(K2) induced higher levels of mBD4 and mBD14, possible mouse orthologues of hBD2 and hBD3, respectively, than the wild type. 52145-Deltawca(K2)-dependent upregulation of hBD2 occurred via NF-kappaB and mitogen-activated protein kinases (MAPKs) p44/42, Jun N-terminal protein kinase (JNK)-dependent pathways. The increase in hBD3 expression was dependent on the MAPK JNK. 52145-Deltawca(K2) engaged Toll-like receptors 2 and 4 (TLR2 and TLR4) to activate hBD2, whereas hBD3 expression was dependent on NOD1. K. pneumoniae induced the expression of CYLD and MKP-1, which act as negative regulators for 52145-Deltawca(K2)-induced expression of hBDs. Bacterial engagement of pattern recognition receptors induced CYLD and MKP-1, which may initiate the attenuation of proinflammatory pathways. The results of this study indicate that K. pneumoniae CPS not only protects the pathogen from the bactericidal action of defensins but also impedes their expression. These features of K. pneumoniae CPS may facilitate pathogen survival in the hostile environment of the lung.
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PMID:Klebsiella pneumoniae capsule polysaccharide impedes the expression of beta-defensins by airway epithelial cells. 2000 34


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