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)

Model systems to study the effects of chemicals of environmental concern on bacterial and parasitic diseases as well as the immunosurveillance and destruction of transplantable tumor cells were described and evaluated. Studies were conducted in female B6C3F1 mice following adult or pre/postnatal exposure to several prototype chemicals. The prototype chemicals employed included the synthetic estrogen diethylstilbestrol (DES), the polycyclic aromatic hydrocarbon benzo(a)pyrene (B[a]P), and the carcinogenesis promoting agent 12-0-tetradecanoyl-phorbol-13-0-acetate (TPA). The host resistance models employed depend primarily on functional thymus-dependent immunity, although humoral immunity is suggested to have a role in the parasite model as well. These models include: subcutaneous challenge with a dose of PYB6 tumor cell causing a 10-20% incidence (TD(10-20)) of tumor; intravenous challenge with B16 melanoma cells; challenge with a dose of Listeria monocytogenes causing a 10-20% incidence of mortality (LD(10-20)); challenge with a dose of E. coli lipopolysaccharide endotoxin causing a 10-20% incidence of lethality (LD(10-20)); and challenge with larvae of Trichinella spiralis for parasite expulsion kinetic studies. Increased mortality was observed following Listeria monocytogenes challenge in DES-exposed mice. B(a)P and TPA exposure did not alter host resistance to this organism. The increased mortality observed following DES was associated with a significant increase in the number of viable Listeria in the spleens and livers at 4 days, a time when T-cell immunity is thought to be expressed, but bacterial counts were similar to control mice at day 1, a time when MPhi are thought to exert their greatest effect. These data suggest that the increased Listeria susceptibility found following DES exposure may result from a T-cell defect, although the intracellular killing capacity of DES-treated Mvarphi's has not been well examined. Tumor susceptibility studies following challenge with 5 x 10(3) viable syngeneic PYB6 tumor cells revealed that nontreated adult B6C3F1 mice resisted tumor formation, with only a 10-20% incidence of tumor formation. In contrast, mice exposed to DES or TPA as adults had a tumor frequency of from 70-100% following TPA and up to 90% following DES exposure. In all cases the tumors were progressive and resulted in death. B(a)P did not alter the frequency of tumor incidence from controls in this model. Preliminary data, using the B16 melanoma intravenous challenge model and (125)IUdR to quantitate tumor mass revealed this model was sensitive to non-specifically activated macrophage kill. DES treated mice with activated macrophages did not demonstrate increased tumor mass, while mice exposed to TPA or the potent immunosuppressive agent cyclophosphamide had a significantly increased tumor mass in their lungs. Expulsion of Trichinella spiralis adults from the gut also apparently required functional T-cells and possibly some element of humoral immunity. Mice exposed to DES and B(a)P exhibited increased numbers of adult worms in the gut at day 14. Sensitivity to gram-negative endotoxin (LPS) was apparently increased following exposure to DES or B(a)P. These data suggest that the detoxification of LPS is related to an intact Mvarphi population. The data presented here demonstrate the sensitivity of the host resistance assay panel proposed for detecting immune alteration. Alteration of T-cell function appeared to correlate with increased susceptibility to bacterial and tumor cell challenge.
 ...
PMID:Application of tumor, bacterial and parasite susceptibility assays to study immune alterations induced by environmental chemicals. 706 May 48

Antibacterial and antitoxin responses in the acute and convalescent (7 to 10 days) sera of 14 cholera patients were determined by various serological techniques. Similar studies were also carried out with corresponding milk samples of six of these patients who were lactating women. A significant rise in antibacterial titers was observed in all convalescent serum and milk samples. A similar rise in antitoxin titers was observable in all serum and four milk samples. Specificity of the antibacterial titers was further evaluated by the indirect hemagglutination test using lipopolysaccharide antigen, and close correlations were noted between these titers and vibrio agglutination (P<0.001) and vibriocidal (P<0.001) titers of sera. Serum and milk convalescent cholera patients could effectively neutralize cholera toxin action in vivo, although the neutralizing activity of serum was higher than that of milk. Determination of antibody titers by the enzyme-linked immunosorbent assay demonstrated that anti-lipopolysaccharide activity in sera belonged predominantly to immunoglobulin M (IgM) and, to a lesser extent, to IgG and IgA, whereas such activity in milk was mostly contributed by secretory IgA, although some IgM antibodies also could be detected. On the other hand, antitoxic activity in convalescent sera primarily belonged to IgG, whereas such activity in milk was almost exclusively contributed by secretory IgA. These results demonstrate that an antibody response in the mammary gland was stimulated due to the antigen exposure in the gut and are consistent with the idea of a common homing pattern of immunocytes within the secretory immune system. Moreover, some differences in the antibody production mechanism between the systemic and secretory immune systems are indicated.
 ...
PMID:Antibacterial and antitoxin responses in the serum and milk of cholera patients. 721 79

This paper describes an experiment which provides information on the ontogeny of some parameters of the intestinal immune system in normal lambs. It is also demonstrated that oral administration of a gram negative bacterial vaccine to foeta lambs resulted in non-specific amplification of the population of IgA plasma cells in the gut and its associated lymphoid tissue, suggesting involvement of bacterial lipopolysaccharide, a recognised B-lymphocyte mitogen, in ontogeny of gut immunity.
 ...
PMID:Role of gram negative bacteria in ontogeny of gut immunity. 745 78

Anandamide (arachidonylethanolamide), isolated from the porcine brain, and 2-arachidonyl-glycerol (2-Ara-Gl), derived from the canine gut, are two recently identified putative endogenous cannabinoid receptor ligands. Both ligands have been reported to possess binding affinity for cannabinoid receptor subtypes, CB1 and CB2. The objective of the present studies was to investigate the immunomodulatory effects of both of these ligands in B6C3F1 mouse splenocytes. 2-Ara-Gl produced a marked and dose-related inhibition of the mixed lymphocyte response, anti-CD3 mAb-induced T-cell proliferation and LPS-induced B-cell proliferation, whereas having no inhibitory effect on phorbol-12-myristate-13-acetate/ionomycin-induced cell proliferation. Interestingly, the inhibitory effects by 2-Ara-Gl on proliferation were at least dependent in part on cell density. At high cell density, 2-Ara-Gl enhanced lymphoproliferation whereas exhibiting marked inhibitory activity at low cell density. Similarly, in vitro primary immunoglobulin M antibody-forming cell responses which are dependent on high cell density also were found to be enhanced by 2-Ara-Gl. Conversely, anandamide exhibited no inhibitory effects on cell proliferative responses to stimulation by anti-CD3 mAb, lipopolysaccharide or phorbol-12-myristate-13-acetate/ionomycin treatment. Anandamide also showed no effect on the in vitro sheep erythrocyte antibody-forming cell response. Although shown previously to markedly inhibit forskolin-stimulated cyclic AMP accumulation, 2-Ara-Gl exhibited no effect on basal adenylate cyclase activity in splenocytes. Additionally, anandamide showed negligible inhibitory effects at extremely high concentrations on forskolin-stimulated adenylate cyclase activity and no effect on basal adenylate cyclase activity in splenocytes.(ABSTRACT TRUNCATED AT 250 WORDS)
 ...
PMID:Effects of putative cannabinoid receptor ligands, anandamide and 2-arachidonyl-glycerol, on immune function in B6C3F1 mouse splenocytes. 747 35

Administration of lipopolysaccharide (LPS) to experimental animals leads to diminished mesenteric perfusion, increased ileal mucosal [H+] , and increased gut epithelial permeability to hydrophilic solutes. We sought to determine whether these phenomena are causally related. Experiments were performed in anesthetized pigs. Permeability was assessed by measuring the plasma-to-lumen clearance of fluorescein isothiocyanate dextran (4,000 Da; FD-4) by a segment of ileum perfused with Ringer lactate solution. Mucosal perfusion (Qmuc) and [H4+] were estimated using laser-Doppler flowmetry and tonometry, respectively. In an initial series of experiments, we showed that mucosal permeability was linearly correlated with mucosal [H+] in animals subjected to graded degrees of mechanically induced mesenteric ischemia (n = 14, R2 = 0.58, P < 0.002) or injected with graded doses of LPS (n = 11, R2 = 0.93, P < 0.0001). In a second series of experiments, we induced mucosal acidosis in normal pigs by mechanical ventilation with either a hypoxic (n = 7) or a hypercapnic (n = 5) gas mixture. In both groups, ileal mucosal permeability to FD-4 increased significantly (P < 0.05), although transmesenteric release of lactate increased significantly only in the hypoxic group. Qmuc was unchanged in both groups. These data suggest that mucosal acidosis, even in the absence of tissue ischemia or hypoxia, increases intestinal permeability to a macromolecular hydrophilic solute. Tissue acidosis may be an important factor contributing to LPS-induced gut mucosal hyperpermeability.
 ...
PMID:Endotoxin-induced ileal mucosal hyperpermeability in pigs: role of tissue acidosis. 751 59

Cyclophosphamide (CY) is used in many animal studies, including models of bacteraemia, to deplete peripheral neutrophils and induce a compromised state. Although CY also influences lymphocyte function, the protective role of lymphocytes in bacteraemia is unclear. Therefore, CY (200 mg/kg) was administered to ddY mice and its influence on the number, cellular composition, and function of lymphocytes in the spleen and Peyer's patches was examined. A single dose of CY reduced the number of lymphocytes in a time-dependent fashion. Flow cytometry showed that B cells carrying B220 antigen decreased significantly. The production of IgA in Peyer's patches, as measured by enzyme-linked immunosorbent assay, was also suppressed in a time-dependent fashion. Blastogenic responses of splenic lymphocytes to Concanavalin-A, lipopolysaccharide and heat-killed Pseudomonas aeruginosa were suppressed 48 h after CY administration. The results suggest that CY suppresses the number and function of lymphocytes, especially B cells. This may lead to bacterial overgrowth in the gut and result in bacteraemia. Intravenous transfusion of normal lymphocytes or oral inoculation of IgA to mice with P. aeruginosa D4 endogenous bacteraemia significantly increased survival rates, indicating that lymphocytes and their products have a protective role in bacteraemia in mice.
 ...
PMID:A protective role for lymphocytes in cyclophosphamide-induced endogenous bacteraemia in mice. 762 54

Factors in circulating air may play a role in immune responses after surgery through induction of gut-derived lipopolysaccharide (LPS) translocation across the gut. CD-1 mice were randomized to one of four treatment groups: controls, laparoscopy with carbon dioxide inflation, laparoscopy with air inflation and laparotomy. The peritoneal and systemic immune response was assessed by evaluating peritoneal macrophage, blood monocyte and neutrophil activity. In a second study, the effect of each of the treatments on fluorescein isothiocyanate (FITC)-LPS translocation across the gut was assessed. There were significant (P < 0.05) increases in peritoneal tissue macrophage release of superoxide and tumour necrosis factor after laparoscopy with air and laparotomy compared with control procedures and carbon dioxide laparoscopy. However, peritoneal macrophage FITC-Candida albicans ingestion was significantly decreased after air laparoscopy and laparotomy compared with controls and carbon dioxide laparoscopy (P < 0.05). These findings correlated with a significant (P < 0.05) decrease in CD11b expression. Significant translocation into the peritoneal cavity and systemic circulation occurred after air laparoscopy and laparotomy only. Factors in circulating air can induce LPS translocation and subsequent stimulation of postoperative immune responses. The beneficial effects of laparoscopic surgery may be explained by the minimal air contamination of the peritoneal cavity.
 ...
PMID:Exposure of the peritoneal cavity to air regulates early inflammatory responses to surgery in a murine model. 764 54

The regulation of urokinase receptor (u-PAR) gene expression during endotoxemia was studied in vivo with a murine model system. Northern blot analysis demonstrated relatively high levels of u-PAR mRNA in mouse placenta, with intermediate levels in lung and spleen and very low levels in heart and kidney. No u-PAR mRNA could be detected in liver, gut, thymus, brain, or skeletal muscle. Intraperitoneal injection of endotoxin (lipopolysaccharide) increased the steady-state levels of u-PAR mRNA in most tissues examined. The greatest induction (sevenfold) was observed in the lung at 1 hour after injection. The cellular localization of u-PAR mRNA was assessed by in situ hybridization. In control mice, u-PAR mRNA was detected primarily in alveolar macrophages of the lung and lymphocytes of the spleen and thymus, although a specific signal was also present in other cell types. In general, endothelial cells lacked detectable u-PAR mRNA. The induction of u-PAR mRNA by lipopolysaccharide was apparent within 30 minutes and was localized to tissue macrophages, lymphocytes, and endothelial cells lining arteries and veins. At later times (1 to 3 hours), specialized epithelial cells present in gastrointestinal tract, bile ducts, and uterus were also positive for u-PAR mRNA. Induction of u-PAR in vivo by lipopolysaccharide may facilitate the extravasation and migration of leukocytes during inflammation.
 ...
PMID:Endotoxin stimulates expression of the murine urokinase receptor gene in vivo. 767 80

We isolated lipopolysaccharide and capsular polysaccharide (K antigen)-defective mutants from two Klebsiella pneumoniae parental strains, and compared their ability to colonize in vivo the germfree chicken gut. The high-molecular weight lipopolysaccharide (LPS) (O antigen) was found necessary for the colonization while the capsular polysaccharide (K2 or K29) was not of importance.
 ...
PMID:The role of the O-antigen lipopolysaccharide on the colonization in vivo of the germfree chicken gut by Klebsiella pneumoniae. 769 9

To assess the humoral immunological responses at the subclass level in shigellosis, specific antibody responses against Shigella dysenteriae 1 lipopolysaccharide (LPS), S. flexneri Y LPS, invasion plasmid-coded protein antigens (Ipa), and Shiga toxin were analyzed. Antibody responses of 41 patients with S. dysenteriae 1 infection (SDIP) and 15 patients with S. flexneri infection (SFIP) were compared with those of controls (n = 40). The levels of total immunoglobulin G (IgG), IgA, IgM, and albumin in serum and stool samples were analyzed. In addition, total IgA (t-IgA), secretory IgA (s-IgA), and antigen-specific s-IgA in fecal samples were analyzed to evaluate the specificities and magnitudes of the mucosal immune responses. By comparing the relative increases in optical density for each IgG subclass separately, it was determined that the anti-LPS (homologous) response initially increased in the order IgG2 > IgG1 > IgG3 > IgG4 and that this order changed to IgG2 > IgG3 > IgG1 > IgG4 later in the disease. The IgG subclass response against protein antigens initially showed the order IgG1 > IgG3 > IgG2 > IgG4, which changed to IgG3 > IgG1 > IgG2 > IgG4 later in the disease. A significant increase in the proportion of IgA2 among t-IgA compared with that in controls was seen in both SDIP and SFIP, while significant changes in the proportions of IgG1 and IgG2 among t-IgG compared with controls was seen only in SDIP. The anti-LPS IgA2 response was more prominent in SDIP than in SFIP. We found an early peak of antigen-specific s-IgA in fecal samples, with a shorter duration than the corresponding response in serum samples. The simultaneous increase of serum IgA, fecal t-IgA, and s-IgA in SDIP compared with those in SFIP suggests that there is a massive increase in the local IgA production, giving an increase in systemic IgA concomitant with an extensive gut mucosal inflammation leading to an increased loss of albumin, IgG, and IgA with a high ratio of t-IgA to s-IgA.
 ...
PMID:Immunoglobulin subclass distribution and dynamics of Shigella-specific antibody responses in serum and stool samples in shigellosis. 772 20


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>