lipoteichoic-acid and Shock--Septic

The cell wall of Gram-positive bacteria contains lipoteichoic acid (LTA) and peptidoglycan (PepG), which synergise to cause shock and organ failure in animals, and to activate human blood to release proinflammatory cytokines. The structural elements within LTA and PepG that are essential for the observed synergism are discussed.

Topics: Animals; Drug Synergism; Humans; Lipopolysaccharides; Macrophage Activation; Macrophages; Mice; Multiple Organ Failure; Peptidoglycan; Shock, Septic; Staphylococcal Infections; Staphylococcus aureus; Teichoic Acids

Previous studies have shown lipopolysaccharide from Gram-negative bacteria is cleared from the circulation via LDL receptors on hepatocytes, which are downregulated by PCSK9. Whether clearance of Gram positive bacterial lipoteichoic acid (LTA) shows similar dependence on PCSK9, and whether this is clinically relevant in Gram positive human sepsis, is unknown. We examined survival data from three cohorts of patients who had Gram positive septic shock (n = 170, n = 130, and n = 59) and found that patients who carried a PCSK9 loss-of-function (LOF) allele had significantly higher 28-day survival (73.8%) than those with no LOF alleles (52.8%) (p = 0.000038). Plasma clearance of LTA was also found to be increased in PCSK9 knockout mice compared to wildtype control mice (p = 0.002). In addition, hepatocytes pre-treated with recombinant wildtype PCSK9 showed a dose-dependent decrease in uptake of fluorescently-labeled LTA (p < 0.01). In comparison to wildtype PCSK9, hepatocytes pre-treated with 3 different LOF variants of recombinant PCSK9 showed an increase in LTA uptake. This study shows the clearance of LTA follows a similar route as lipopolysaccharide, which is dependent on hepatic LDL receptors. This has important implications in health as strategies aimed at inhibiting PCSK9 function may be an effective treatment option for both Gram-positive and negative sepsis.

Topics: Animals; Female; Flow Cytometry; Gram-Positive Bacterial Infections; Hepatocytes; Humans; Lipopolysaccharides; Male; Mice, Knockout; Middle Aged; Proprotein Convertase 9; Shock, Septic; Survival Analysis; Teichoic Acids

It has been previously reported that pretreatment with exogenous heat shock protein 70 (Hsp70) is able to protect cells and animals from the deleterious effects of bacterial lipopolysaccharide (LPS) produced by Gram-negative bacteria. However, the effects of Hsp70 pretreatment on lipoteichoic acid (LTA) challenge resulted from Gram-positive bacteria infection have not been fully elucidated. In this study, we demonstrated that preconditioning with human recombinant Hsp70 ameliorates various manifestations of systematic inflammation, including reactive oxygen species, TNFα, and CD11b/CD18 adhesion receptor expression induction observed in different myeloid cells after LTA addition. Therefore, exogenous Hsp70 may provide a mechanism for controlling excessive inflammatory responses after macrophage activation. Furthermore, in a rat model of LTA-induced sepsis, we demonstrated that prophylactic administration of exogenous human Hsp70 significantly exacerbated numerous homeostatic and hemodynamic disturbances induced by LTA challenge and partially normalized the coagulation system and multiple biochemical blood parameters, including albumin and bilirubin concentrations, which were severely disturbed after LTA injections. Importantly, prophylactic intravenous injection of Hsp70 before LTA challenge significantly reduced mortality rates. Thus, exogenous mammalian Hsp70 may serve as a powerful cellular defense agent against the deleterious effects of bacterial pathogens, such as LTA and LPS. Taken together, our findings reveal novel functions of this protein and establish exogenous Hsp70 as a promising pharmacological agent for the prophylactic treatment of various types of sepsis.

Topics: Animals; Apoptosis; Bilirubin; CD11b Antigen; CD18 Antigens; Cells, Cultured; Hemodynamics; HSP70 Heat-Shock Proteins; Humans; Inflammation; Lipopolysaccharides; Male; Monocytes; Neutrophils; Rats; Rats, Sprague-Dawley; Reactive Oxygen Species; Recombinant Proteins; Serum Albumin; Shock, Septic; Teichoic Acids; Tumor Necrosis Factor-alpha

In this study, the effect of Lactobacillus plantarum lipoteichoic acid (pLTA) on LPS-induced MAPK activation, NF-kappaB activation, and the expression of TNF-alpha and IL-1R-associated kinase M (IRAK-M) was examined. The expression of the pattern recognition receptor and the survival rate of mice were also examined. pLTA pretreatment inhibited the phosphorylation of ERK, JNK, and p38 kinase. It also inhibited the degradation of IkappaBalpha and IkappaBbeta, as well as the activation of the LPS-induced TNF-alpha factor in response to subsequent LPS stimulation. These changes were accompanied by the suppression of the LPS-induced expression of TLR4, NOD1, and NOD2, and the induction of IRAK-M, with a concurrent reduction of TNF-alpha secretion. Furthermore, the overexpression of pattern recognition receptors such as TLR4, NOD1, and NOD2 and the degradation of IRAK-M by transient transfection were found to reinstate the production of TNF-alpha after LPS restimulation. In addition, the i.p. injection of pLTA suppressed fatality, and decreased the level of TNF-alpha in the blood, in LPS-induced endotoxin shock mice. In conclusion, these data extend our understanding of the pLTA tolerance mechanism, which is related to the inhibition of LPS-induced endotoxin shock, and suggest that pLTA may have promise as a new therapeutic agent for LPS-induced septic shock.

Topics: Animals; Cell Line, Tumor; Humans; Immune Tolerance; Lactobacillus plantarum; Lipopolysaccharides; Male; MAP Kinase Signaling System; Mice; Mice, Inbred BALB C; Mice, Knockout; Shock, Septic; Teichoic Acids; Toll-Like Receptor 2; Tumor Necrosis Factor-alpha; U937 Cells

In the present study, the signal pathways involved in NO formation and iNOS expression in RAW 264.7 macrophages stimulated by LTA were investigated. We also compared the relative inhibitory activities and mechanisms of PMC, a novel potent antioxidant of alpha-tocopherol derivatives, with those of YC-1, an sGC activator, on the induction of iNOS expression by LTA in cultured macrophages in vitro and LTA-induced hypotension in vivo. LTA induced concentration (0.1-50 microg/mL)- and time (4-24 hr)-dependent increases in nitrite (an indicator of NO biosynthesis) in macrophages. Both PMC (50 microM) and YC-1 (10 microM) inhibited NO production, iNOS protein, mRNA expression, and IkappaBalpha degradation upon stimulation by LTA (20 microg/mL) in macrophages. On the other hand, PMC (50 microM) almost completely suppressed JNK/SAPK activation, whereas YC-1 (10 microM) only partially inhibited its activation in LTA-stimulated macrophages. Moreover, PMC (10 mg/kg, i.v.) and YC-1 (5 mg/kg, i.v.) significantly inhibited the fall in MAP stimulated by LTA (10 mg/kg, i.v.) in rats. In conclusion, we demonstrate that YC-1 shows more-potent activity than PMC at abrogating the expression of iNOS in macrophages in vitro and reversing delayed hypotension in rats with endotoxic shock stimulated by LTA. The inhibitory mechanisms of PMC may be due to its antioxidative properties, with a resulting influence on JNK/SAPK and NF-kappaB activations. YC-1 may be mediated by increasing cyclic GMP, followed by, at least partly, inhibition of JNK/SAPK and NF-kappaB activations, thereby leading to inhibition of iNOS expression.

Topics: Animals; Chromans; Drug Interactions; Enzyme Activation; Gene Expression; Indazoles; Lipopolysaccharides; Macrophages; Male; Mice; Mitogen-Activated Protein Kinases; NF-kappa B; Nitric Oxide Synthase; Nitric Oxide Synthase Type II; Nitrites; Rats; Rats, Wistar; RNA, Messenger; Shock, Septic; Teichoic Acids

Whether nitric oxide (NO) protects or impairs the liver function and structure during the early phase of sepsis is still controversial. The aim of this study is to evaluate the effect of NO on lipopolysaccharide (LPS) or lipoteichoic acid (LTA) induced liver injury in rats.. One hundred twenty-six Wistar rats were assigned randomly and equally to LTA and LPS groups. Each group was divided into three subgroups which received saline, L-Arginine (L-Arg) or NG-nitro-L-arginine methylester (L-NAME) consecutively, one hour prior to either 5 mg/kg LPS or 3 mg/kg LTA injection. Plasma nitrite plus nitrate [NOx] were measured. Liver injury was assessed by measuring the rises in circulating liver enzymes and by scoring the extent of liver necrosis.. Administration of L-NAME+LPS not only reduced [NOx] production but also enhanced liver damage. LNAME+ LTA caused an increase in the plasma levels of [NOx] (p=0.0006), and produced sinusoidal enlargement in liver. L-Arg protected the hepatocytes against LPS injury, whereas, enhanced the liver damage in the LTA group.. Our data indicated that overproduction of NO exerts detrimental effect on LTA-treated rats while providing a protective function in LPS group.

Topics: Animals; Arginine; Disease Models, Animal; Enzyme Inhibitors; Lipopolysaccharides; Liver; Liver Function Tests; Male; NG-Nitroarginine Methyl Ester; Nitrates; Nitrites; Random Allocation; Rats; Rats, Wistar; Shock, Septic; Teichoic Acids

Despite the fact that gram-positive infections constitute around 50% of all cases leading to septic shock, little is yet known about the mechanisms involved. This study was carried out to find out more about the effects of cell wall components peptidoglycan (PepG) and lipoteichoic acid (LTA) of the gram-positive bacterium Streptococcus pyogenes in the pig. Specific pathogen-free pigs (20 kg bodyweight) were pretreated with metyrapone (a cortisol-synthesis inhibitor) and then were given 2-h infusions of 160 microg/kg of PepG (n = 5), 160 microg/kg LTA (n=5), or a combination of both (LTA + PepG, 160 microg/kg each, n = 5). Four hours after start of the infusions, the PepG, LTA, and LTA + PepG groups showed decreases in mean arterial pressure (change of -11%, -25%, and -47% from baseline, respectively), dynamic lung compliance (-18%, -24%, and -38%), arterial oxygen tension (-10%, -16%, and -37%), changes in blood leukocyte numbers (+11%, -27%, and -67%), and increases in pulmonary vascular resistance index (+7%, +106%, and +307% from baseline) and metabolic acidosis (base excess values decreased with 1.8, 2.3 and 8.1 units). The differences between the PepG and LTA + PepG groups were statistically significant (P < 0.05, Kruskal-Wallis tests), but not between LTA and LTA + PepG groups. However, no changes in systemic nitric oxide (NO) production could be detected, which is much in contrast to studies on lower order animals. Moreover, comparison of the results obtained using this model with those obtained in a model of endotoxin-induced septic shock showed distinct difference in the mechanisms by which gram-positive and gram-negative bacterial components exert their actions. For example, a marked fall in systemic blood pressure and dynamic lung compliance is seen in both models, but in the present gram-positive sepsis model, much less interleukin-8 and tumor necrosis factor-alpha are produced. In conclusion, this study showed that PepG and LTA act synergistically to cause respiratory failure and septic shock in the pig. The infusion of the combination of PepG and LTA in the pig could serve as a new, well-controlled model for studies of gram-positive sepsis.

Topics: Animals; Drug Synergism; Endothelin-1; Endotoxins; Female; Hydrocortisone; Interleukin-8; Leukocyte Count; Lipopolysaccharides; Lung Compliance; Male; Metyrapone; Nitric Oxide; Oxygen; Peptidoglycan; Pulmonary Circulation; Sepsis; Shock, Septic; Specific Pathogen-Free Organisms; Streptococcus pyogenes; Swine; Teichoic Acids; Tumor Necrosis Factor-alpha; Vascular Resistance

In this study, gram-positive Staphylococcus aureus lipoteichoic acid (LTA) dose-dependently (0.1-1.0 microg/ml) and time-dependently (10-60 min) inhibited platelet aggregation in human platelets stimulated by agonists. LTA also dose-dependently inhibited phosphoinositide breakdown and intracellular Ca+2 mobilization in human platelets stimulated by collagen. LTA (0.5 and 1.0 microg/ml) also significantly inhibited thromboxane A2 formation stimulated by collagen in human platelets. Moreover, LTA (0.1-1.0 microg/ml) dose-dependently decreased the fluorescence of platelet membranes tagged with diphenylhexatrience. Rapid phosphorylation of a platelet protein of Mr. 47,000 (P47), a marker of protein kinase C activation, was triggered by PDBu (30 nM). This phosphorylation was markedly inhibited by LTA (0.5 and 1.0 microg/ml) within a 10-min incubation period. These results indicate that the antiplatelet activity of LTA may be involved in the following pathways: LTA's effects may initially be due to induction of conformational changes in the platelet membrane, leading to a change in the activity of phospholipase C, and subsequent inhibition of phosphoinositide breakdown and thromboxane A2 formation, thereby leading to inhibition of both intracellular Ca+2 mobilization and phosphorylation of P47 protein. Therefore, LTA-mediated alteration of platelet function may contribute to bleeding diathesis in gram-positive septicemic and endotoxemic patients.

Topics: Calcium Signaling; Cell Membrane; Collagen; Cytosol; Dose-Response Relationship, Drug; Endotoxemia; Enzyme Activation; Gram-Negative Bacterial Infections; Gram-Positive Bacterial Infections; Hemorrhagic Disorders; Humans; L-Lactate Dehydrogenase; Lipopolysaccharides; Membrane Fluidity; Membrane Lipids; Nitric Oxide Synthase; Nitric Oxide Synthase Type II; Peptides; Phorbol 12,13-Dibutyrate; Phosphatidylinositols; Phosphorylation; Platelet Aggregation; Platelet Aggregation Inhibitors; Platelet Glycoprotein GPIIb-IIIa Complex; Protein Kinase C; Protein Processing, Post-Translational; Sepsis; Shock, Septic; Staphylococcus aureus; Teichoic Acids; Thromboxane A2; Thromboxane B2

An enhanced formation of reactive oxygen species contributes to the multiple organ dysfunction syndrome (MODS) caused by endotoxin. We have recently discovered that two cell wall components, namely lipoteichoic acid (LTA) and peptidoglycan (PepG) of the gram-positive bacterium, Staphylococcus aureus, synergize to cause shock and MODS in the rat. Here, we investigate the effects of a membrane-permeable radical scavenger (tempol) on the circulatory failure and MODS (kidney, liver, lung) caused by coadministration of LTA (3 mg/kg i.v.) and PepG (10 mg/kg i.v.) in the anesthetized rat.. Prospective, randomized study.. University-based research laboratory.. Thirty-four anesthetized, male Wistar rats.. After surgical preparation, anesthetized rats were observed for 6 hrs. Control rats were given vehicle (control plus saline, 2 mL/kg bolus injection, followed by an infusion of 1.5 mL/kg i.v., n = 6) or tempol (control plus tempol, 100 mg/kg i.v. bolus injection, followed by an infusion of 30 mg/kg i.v., n = 6). Gram-positive septic shock was induced by coadministration of LTA (3 mg/kg i.v.) and PepG (10 mg/kg i.v.) (LTA/PepG plus saline, n = 12). Another group of rats was pretreated with tempol before shock was induced (LTA/PepG plus tempol, 100 mg/kg i.v. bolus injection, 15 mins before LTA/PepG administration, followed by an infusion of 30 mg/kg i.v., n = 10).. Within 6 hrs, administration of LTA/PepG resulted in hypotension, acute renal dysfunction, hepatocellular injury, pancreatic injury, and increased plasma concentrations of nitrite/nitrate. Pretreatment of rats with tempol augmented the hypotension but attenuated the renal dysfunction and the hepatocellular injury/dysfunction caused by LTA/PepG. Tempol did not affect the increase in nitrite/nitrate caused by LTA/PepG.. These results imply that an enhanced formation of reactive oxygen species (including superoxide anions) contributes to the kidney and liver injury and dysfunction caused by LTA/PepG in the anesthetized rat.

Topics: Animals; Blood Pressure; Cyclic N-Oxides; Free Radical Scavengers; Kidney; Lipopolysaccharides; Liver; Lung; Male; Multiple Organ Failure; Multiple Trauma; Nitrates; Nitrites; Peptidoglycan; Random Allocation; Rats; Rats, Wistar; Shock, Septic; Spin Labels; Staphylococcal Infections; Teichoic Acids; Tyrosine

In this study, Gram-positive Staphylococcus aureus lipoteichoic acid (LTA) dose dependently (0.1-1.0 microg/mL) and time dependently (10-60 min) inhibited platelet aggregation in human platelets stimulated by agonists (i.e., thrombin and collagen). LTA also dose dependently inhibited intracellular Ca(2+) mobilization in human platelets stimulated by collagen. In addition, LTA (0.5 and 1.0 microg/mL) dose dependently increased the formation of cyclic AMP but not cyclic GMP in platelets. LTA (0.5 and 1.0 microg/mL) did not significantly increase the production of nitrate within a 10-min incubation period. Rapid phosphorylation of a platelet protein of M(r) 47,000, a marker of protein kinase C activation, was triggered by PDBu (0.03 microM). This phosphorylation was dose dependently inhibited by LTA (0.5 and 1.0 microg/mL) within a 10-min incubation period. Furthermore, LTA (0.5 and 1.0 microg/mL) also inhibited platelet aggregation induced by PDBu (0.03 microM) in human platelets. These results indicate that the antiplatelet activity of LTA may be involved in the increase of cyclic AMP, leading to inhibition of intracellular Ca(2+) mobilization and protein kinase C activity. Therefore, LTA-mediated alteration of platelet function may contribute to bleeding diathesis in septicemic and endotoxemic patients.

Topics: Alprostadil; Blood Platelets; Blood Proteins; Calcium Signaling; Collagen; Cyclic AMP; Cyclic GMP; Cytokines; Enzyme Induction; Gram-Positive Bacteria; Humans; Lipopolysaccharides; Molecular Weight; Nitrates; Nitric Oxide; Nitric Oxide Synthase; Nitric Oxide Synthase Type II; Nitroglycerin; Phorbol 12,13-Dibutyrate; Phosphorylation; Platelet Aggregation Inhibitors; Protein Kinase C; Protein Processing, Post-Translational; Second Messenger Systems; Shock, Septic; Staphylococcus aureus; Teichoic Acids

The present study was carried out to gain insight into the mechanisms involved in the pathogenesis of streptococcal toxic shock syndrome (TSS) and other acute invasive diseases caused by Streptococcus pyogenes (GAS). Specifically, since both whole bacteria and their soluble products are often present in the blood in these conditions, we sought to detect possible synergic activities of somatic and extracellular products in inducing mediators release. For this purpose, whole blood cultures from healthy donors were incubated with different concentrations of streptococcal pyrogenic exotoxin A (SpeA), which is considered a major molecular effector of TSS, heat-killed GAS and cell-wall components such as lipoteichoic acid (LTA) and soluble peptidoglican (sPGN). Significant levels of TNF-alpha, IL-1 alpha and IFN-gamma were found in supernatants from cultures incubated with each of the four inducers alone. Whole GAS and both cell-wall components were more effective (p < 0.05) than SpeA in inducing cytokine release. Whole GAS, at weight basis, was a more potent inducer than LTA and sPGN and LTA, at weight basis, was a more potent inducer than sPGN. In order to verify possible additive or synergic effects of exotoxic and parietal compounds in inducing cytokine release, whole blood cells were incubated with mixtures of SpeA and LTA at different molecular ratio. TNF-alpha, IL-1 alpha and IFN-gamma levels in supernatants were significantly (p < 0.05) higher in supernatants of cultures stimulated simultaneously with the two components than those of cultures stimulated with a single agent. Moreover, these levels were significantly higher than the sum of cytokine levels induced by single components. This study shows that parietal compounds can act in synergy with exotoxins in inducing the release of cytokines, which appear to be the major mediators of TSS.

Topics: Bacterial Proteins; Blood Cells; Cells, Cultured; Cytokines; Exotoxins; Humans; Interferon-gamma; Interleukin-1; Lipopolysaccharides; Membrane Proteins; Shock, Septic; Streptococcal Infections; Streptococcus pyogenes; Teichoic Acids; Tumor Necrosis Factor-alpha

The incidence of septic shock caused by gram-positive bacteria has risen markedly in the last few years. It is largely unclear how gram-positive bacteria (which do not contain endotoxin) cause shock and multiple organ failure. We have discovered recently that two cell wall fragments of the pathogenic gram-positive bacterium Staphylococcus aureus, lipoteichoic acid (LTA) and peptidoglycan (PepG), synergize to cause the induction of nitric oxide (NO) formation, shock, and organ injury in the rat. We report here that a specific fragment of PepG, N-acetylglucosamine-beta-[1--> 4]-N-acetylmuramyl-L-alanine-D-isoglutamine, is the moiety within the PepG polymer responsible for the synergism with LTA (or the cytokine interferon gamma) to induce NO formation in the murine macrophage cell line J774.2. However, this moiety is also present in the PepG of the nonpathogenic bacterium Bacillus subtilis. We have discovered subsequently that S. aureus LTA synergizes with PepG from either bacterium to cause enhanced NO formation, shock, and organ injury in the rat, whereas the LTA from B. subtilis does not synergize with PepG of either bacterium. Thus, we propose that the structure of LTA determines the ability of a particular bacterium to cause shock and multiple organ failure (pathogenicity), while PepG acts to amplify any response induced by LTA.

Topics: Animals; Bacillus subtilis; Cell Line; Enzyme Induction; Lipopolysaccharides; Macrophages; Mice; Multiple Organ Failure; Nitric Oxide Synthase; Peptide Fragments; Peptidoglycan; Rats; Shock, Septic; Staphylococcal Infections; Staphylococcus aureus; Teichoic Acids

1. The pathological features of Gram-positive shock can be mimicked by the co-administration of two cell wall components of Staphylococcus aureus, namely lipoteichoic acid (LTA) and peptidoglycan (PepG). This is associated with the expression of the inducible isoform of nitric oxide synthase (iNOS) in various organs. We have investigated the effects of dexamethasone (which prevents the expression of iNOS protein) or aminoguanidine (an inhibitor of iNOS activity) on haemodynamics, multiple organ dysfunction syndrome (MODS) as well as iNOS activity elicited by LTA + PepG in anaesthetized rats. 2. Co-administration of LTA (3 mg kg-1, i.v.) and PepG (10 mg kg-1, i.v.) resulted in a significant increase in the plasma levels of tumour necrosis factor-alpha (TNF alpha, maximum at 90 min) as well as a biphasic fall in mean arterial blood pressure (MAP) from 120 +/- 3 mmHg (time 0) to 77 +/- 5 mmHg (at 6 h, n = 8; P < 0.05). This hypotension was associated with a significant tachycardia (4-6 h, P < 0.05) and a reduction of the pressor response elicited by noradrenaline (NA, 1 microgram kg-1, i.v., at 1-6 h; n = 8, P < 0.05). Furthermore, LTA + PepG caused time-dependent increases in the serum levels of markers of hepatocellular injury, glutamate-pyruvate-transminase (GPT) and glutamate-oxalacetate-transaminase (GOT). In addition, urea and creatinine (indicators of renal dysfunction) were increased. There was also a fall in arterial oxygen tension (PaO2), indicating respiratory dysfunction, and metabolic acidosis as shown by the significant drop in pH, PaCO2 and HCO3-. These effects caused by LTA + PepG were associated with the induction of iNOS activity in aorta, liver, kidney and lungs as well as increases in serum levels of nitrite+nitrate (total nitrite). 3. Pretreatment of rats with dexamethasone (3 mg kg-1, i.p.) at 120 min before LTA + PepG administration significantly attenuated these adverse effects as well as the increases in the plasma levels of TNF alpha caused by LTA + PepG. The protective effects of dexamethasone were associated with a prevention of the increase in iNOS activity (in aorta, liver, lung, kidney), the expression of iNOS protein (in lungs), as well as in the increase in the plasma levels of total nitrite. 4. Treatment of rats with aminoguanidine (5 mg kg-1 + 10 mg kg-1 h-1) starting at 120 min after LTA + PepG attenuated most of the adverse effects and gave a significant inhibition of iNOS activity (in various organs) as well as an inhibi

Topics: Acid-Base Equilibrium; Animals; Anti-Inflammatory Agents; Blotting, Western; Dexamethasone; Enzyme Inhibitors; Guanidines; Hemodynamics; Kidney; Lipopolysaccharides; Liver; Lung; Male; Nitric Oxide; Nitric Oxide Synthase; Peptidoglycan; Rats; Rats, Wistar; Shock, Septic; Staphylococcus aureus; Teichoic Acids; Tumor Necrosis Factor-alpha

Although the incidence of Gram-positive sepsis has risen strongly, it is unclear how Gram-positive organisms (without endotoxin) initiate septic shock. We investigated whether two cell wall components from Staphylococcus aureus, peptidoglycan (PepG) and lipoteichoic acid (LTA), can induce the inflammatory response and multiple organ dysfunction syndrome (MODS) associated with septic shock caused by Gram-positive organisms. In cultured macrophages, LTA (10 micrograms/ml), but not PepG (100 micrograms/ml), induces the release of nitric oxide measured as nitrite. PepG, however, caused a 4-fold increase in the production of nitrite elicited by LTA. Furthermore, PepG antibodies inhibited the release of nitrite elicited by killed S. aureus. Administration of both PepG (10 mg/kg; i.v.) and LTA (3 mg/kg; i.v.) in anesthetized rats resulted in the release of tumor necrosis factor alpha and interferon gamma and MODS, as indicated by a decrease in arterial oxygen pressure (lung) and an increase in plasma concentrations of bilirubin and alanine aminotransferase (liver), creatinine and urea (kidney), lipase (pancreas), and creatine kinase (heart or skeletal muscle). There was also the expression of inducible nitric oxide synthase in these organs, circulatory failure, and 50% mortality. These effects were not observed after administration of PepG or LTA alone. Even a high dose of LTA (10 mg/kg) causes only circulatory failure but no MODS. Thus, our results demonstrate that the two bacterial wall components, PepG and LTA, work together to cause systemic inflammation and multiple systems failure associated with Gram-positive organisms.

Topics: Animals; Cell Line; Cell Wall; Enzyme Induction; Hemodynamics; Interferon-gamma; Isoenzymes; Lipopolysaccharides; Lung; Macrophages; Male; Mice; Multiple Organ Failure; Nitric Oxide Synthase; Organ Specificity; Peptidoglycan; Rats; Rats, Wistar; Shock, Septic; Staphylococcal Infections; Staphylococcus aureus; Teichoic Acids; Tumor Necrosis Factor-alpha; Virulence

1. This study investigates the effects of two structurally different antagonists of platelet-activating factor (PAF), BN52021 and WEB2086, on the circulatory and renal failure elicited by lipoteichoic acid (LTA) from Staphylococcus aureus (an organism without endotoxin) in anaesthetized rats. 2. Administration of LTA (10 mg kg-1, i.v.) caused hypotension and vascular hyporeactivity to noradrenaline (1 microgram kg-1, i.v.) WEB2086 (5 mg kg-1, i.v., 20 min before and 150 min after LTA) inhibited the delayed fall in mean arterial blood pressure (at 300 min: 99 +/- 6 mmHg vs. 75 +/- 6 mmHg, P < 0.01) and prevented the decrease in pressor response to noradrenaline (at 300 min: 36 +/- 5 mmHg min vs. 17 +/- 5 mmHg min, P < 0.01). Surprisingly, BN52021 (20 mg kg-1, i.v., 20 min before and 150 min after LTA) neither prevented the hypotension (74 +/- 6 mmHg) nor the vascular hyporeactivity (21 +/- 5 mmHg min). However, BN52021 inhibited the hypotension to injections of PAF as well as the circulatory failure elicited by lipopolysaccharides (10 mg kg-1, i.v.). 3. LTA caused an increase in plasma concentration of creatinine from 39 +/- 5 microM (sham-operated) to 70 +/- 8 microM and urea from 4.7 +/- 0.1 to 13.1 +/- 1.6 mM. The renal failure elicited by LTA was significantly inhibited by WEB2086 (creatinine: 45 +/- 4 microM and urea: 5.7 +/- 0.7 mM), but not by BN52021. 4. The induction of nitric oxide synthase activity in lungs by LTA was attenuated by WEB2086 from 98 +/- 17 to 40 +/- 15 pmol L-citrulline 30 min-1 mg-1 protein (P < 0.01), but not by BN52021 (148 +/- 21 pmol L-citrulline 30 min-1 mg-1 protein). Similarly, WEB2086, but not BN52021, inhibited the increase in plasma nitrite concentration associated with the delayed circulatory failure caused by LTA. The release of tumour necrosis factor-alpha (TNF-alpha) after injection of LTA was not attenuated by WEB2086. 5. The induction of nitrite release by cultured macrophages activated with LTA (10 micrograms ml-1 for 24 h) was inhibited by 74 +/- 4% by WEB2086 (3 x 10(-4) M), but not by BN52021, indicating that only WEB2086 acts on intracellular PAF receptors. 6. Thus, the intracellular release of PAF contributes to the circulatory and renal failure and induction of nitric oxide synthase elicited by LTA in anaesthetized rats. The difference between the two structurally different PAF antagonists in our septic shock models using either LTA or lipopolysaccharide (LPS), shows the importance of models for Gram-positi

Topics: Acute Kidney Injury; Animals; Azepines; Cells, Cultured; Diterpenes; Ginkgolides; Hemodynamics; Lactones; Lipopolysaccharides; Lung; Male; Nitric Oxide Synthase; Nitrites; Norepinephrine; Plant Extracts; Platelet Activating Factor; Rats; Rats, Wistar; Shock, Septic; Streptomyces; Teichoic Acids; Triazoles; Tumor Necrosis Factor-alpha