Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0036690 (sepsis)
 59,461 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Stimulation of human neutrophils by LPS is central to the pathogenesis of sepsis and the adult respiratory distress syndrome. The intracellular signaling pathway that results in cellular responses following LPS stimulation in neutrophils is unknown. We report that exposure of neutrophils to LPS results in the phosphorylation and activation of a p38 mitogen-activated protein (MAP) kinase, occurring in a concentration-dependent manner, with maximum response at 20 to 25 min. Partial purification of a p38 MAP kinase by ion exchange chromatography established it as distinct from the p42/p44 (extracellular signal-regulated kinases (ERK-1 and ERK-2) MAP kinases). Activation of the p38 MAP kinase by LPS in human neutrophils occurs via CD14, a proposed LPS receptor, and requires the presence of plasma containing the LPS-binding protein. This intracellular signaling pathway is independent of protein kinase C and does not involve Raf, MAP/ERK kinase kinase-1, MAP/ERK kinase-1, or MAP/ERK kinase-2 and does not result in the activation of the p42/p44 ERK MAP kinases or the c-jun N-terminal kinases.
 ...
PMID:Activation of a p38 mitogen-activated protein kinase in human neutrophils by lipopolysaccharide. 864 36

Altered endotoxin (LPS) signal transduction in macrophages (Mphi) may mediate development of organ dysfunction in sepsis. C3H/HeJ Mphi have a specific genetic defect that renders them "tolerant" to in vitro LPS activation. LPS tolerance can be induced in normal C3H/HeN Mphi following in vitro LPS pretreatment. In these experiments, in vitro LPS-stimulated activation of Mphi mitogen-activated protein (MAP) kinases were compared in C3H/HeJ and C3H/HeN mice. C3H/HeJ and C3H/HeN Mphi were cultured+/-10 ng/mL LPS pretreatment for 24 h, then stimulated with 0-1,000 ng/mL LPS for 6 h. Western blots were performed on lysates with monoclonal antibody to active ERK1,2 (p42/44), stress-activated protein kinase (SAPK, p54/46), and p38 kinase. Supernatant TNF or IL-1 was determined by bioassay. High dose LPS stimulation activated ERK, SAPK, and p38 kinases in both C3H/HeN and C3H/HeJ Mphi. ERK activation, p46 SAPK, and p38 activation were inhibited in C3H/HeN Mphi after LPS pretreatment, whereas they were unchanged or increased in HeJ Mphi. TNF secretion was significantly decreased in C3H/HeN Mphi following LPS pretreatment, but absent in C3H/HeJ Mphi at all times. Mphi from normal C3H/HeN mice rendered endotoxin tolerant by in vitro, low dose LPS pretreatment have specific signal transduction defects that are not present in genetically LPS hyporesponsive C3H/HeJ mice.
 ...
PMID:In vitro macrophage endotoxin tolerance: defective in vitro macrophage map kinase signal transduction after LPS pretreatment is not present in macrophages from C3H/HeJ endotoxin resistant mice. 992 18

During gram-negative sepsis, human monocytes are triggered to produce large quantities of proinflammatory cytokines such as tumor necrosis factor alpha (TNF-alpha) in response to endotoxin (lipopolysaccharide [LPS]). Several studies have identified signal transduction pathways that are activated by LPS, including activation of nuclear factor-kappaB (NF-kappaB) and activation of mitogen-activated protein kinases (MAPKs), including ERK1 and ERK2, c-Jun N-terminal kinase, and p38. In this study, the relevance of ERK1 and ERK2 activation for LPS-induced TNF-alpha production by primary human monocytes has been addressed with PD-098059, which specifically blocks activation of MAPK kinase (MEK) by Raf-1. TNF-alpha levels in the monocyte culture supernatant, induced by 10 ng of LPS/ml, were reduced by PD-098059 (50 microM). In addition, PD-098059 also reduced TNF-alpha mRNA expression when cells were stimulated for 1 h with LPS. On the other hand, LPS-induced interleukin-10 (IL-10) levels in the monocyte supernatant were only slightly inhibited by PD-098059. Ro 09-2210, a recently identified MEK inhibitor, completely abrogated TNF-alpha levels at nanomolar concentrations. IL-10 levels also were strongly reduced. To show the efficacy of PD-098059 and Ro 09-2210, ERK1 and -2 activation was monitored by Western blotting with an antiserum that recognizes the phosphorylated (i.e., activated) forms of ERK1 and ERK2. Addition of LPS to human monocytes resulted in activation of both ERK1 and ERK2 in a time- and concentration (50% effective concentration between 1 and 10 ng of LPS/ml)-dependent manner. Activation of ERK2 was blocked by PD-098059 (50 microM), whereas ERK1 seemed to be less affected. Ro 09-2210 completely prevented LPS-induced ERK1 and ERK2 activation. LPS-induced p38 activation also was prevented by Ro 09-2210. These data further support the view that the ERK signal transduction pathway is causally involved in the synthesis of TNF-alpha by human monocytes stimulated with LPS.
 ...
PMID:Lipopolysaccharide-induced tumor necrosis factor alpha production by human monocytes involves the raf-1/MEK1-MEK2/ERK1-ERK2 pathway. 1041 44

Neutrophils exposed to low concentrations of gram-negative lipopolysaccharide (LPS) become primed and have an increased oxidative response to a second stimulus (e.g., formyl-methionyl-leucyl-phenylalanine [fMLP]). In studies aimed at understanding newborn sepsis, we have shown that neutrophils of newborns are not primed in response to LPS. To further understand the processes involved in LPS-mediated priming of neutrophils, we explored the role of extracellular signal-related protein kinases (ERK 1 and 2) of the mitogen-activated protein kinase family. We found that LPS activated ERK 1 and 2 in cells of both adults and newborns and that activation was plasma dependent (maximal at > or =5%) through LPS-binding protein. Although fibronectin in plasma is required for LPS-mediated priming of neutrophils of adults assessed by fMLP-triggered oxidative burst, it was not required for LPS-mediated activation of ERK 1 and 2. LPS-mediated activation was dose and time dependent; maximal activation occurred with approximately 5 ng of LPS per ml and at 10 to 40 min. We used the inhibitor PD 98059 to study the role of ERK 1 and 2 in the LPS-primed fMLP-triggered oxidative burst. While Western blotting showed that 100 microM PD 98059 completely inhibited LPS-mediated ERK activation, oxidative response to fMLP by a chemiluminescence assay revealed that the same concentration inhibited the LPS-primed oxidative burst by only 40%. We conclude that in neutrophils, LPS-mediated activation of ERK 1 and 2 requires plasma and that this activation is not dependent on fibronectin. In addition, we found that the ERK pathway is not responsible for the lack of LPS priming in neutrophils of newborns but may be required for 40% of the LPS-primed fMLP-triggered oxidative burst in cells of adults.
 ...
PMID:Activation of extracellular signal-related protein kinases 1 and 2 of the mitogen-activated protein kinase family by lipopolysaccharide requires plasma in neutrophils from adults and newborns. 1129 34

Reduction of neutrophil apoptosis represents a major cause for granulocytosis and increases the destructive potential of theses cells during systemic inflammatory response syndrome (SIRS) and sepsis. In this light, the role of protein kinases for the regulation of altered neutrophil apoptosis under infectious conditions was investigated. Neutrophils, obtained from patients with severe sepsis (n = 18), were incubated ex vivowith either LPS (1 microg/mL) or interferon-gamma (IFN-gamma; 10 ng/mL) for 16 h. Apoptosis was determined by propidium iodine (PI) staining of DNA fragments and was compared with the rate of spontaneous apoptosis. Tyrosine kinases were inhibited by herbimycin (1 microM), the mitogen-activated protein (MAP) kinase ERK was inhibited with PD98059 (50 microM), and p38 MAP kinase was inhibited with SB203580 (5 microM). Herbimycin reconstituted LPS-reduced apoptosis in neutrophils from controls (39.9 +/- 3.8%) and patients (20.8 +/- 2.8%) to levels seen in spontaneous apoptosis (70.9 +/- 2.8% and 40.7 +/- 3.7%, respectively). Inhibition of the ERK kinase yielded similar results, whereas SB203580 had no effect on LPS-reduced apoptosis. However, inhibition of p38 partially reconstituted IFN-gamma-reduced apoptosis (51.3 +/- 7.7% and 25.6 +/- 5.8%) and increased spontaneous apoptosis (82.4 +/- 3.3% and 42.0 +/- 5.8%) in controls and patients, respectively. Western blot analysis revealed phosphorylation of both MAP kinases by LPS, but not by IFN-gamma. Inhibition of MAP kinases did not augment neutrophil apoptosis in patients to the level seen in controls, indicating that other mechanisms must be involved in the regulation of neutrophil apoptosis. Although the ERK kinase regulates LPS-induced reduction of apoptosis, the p38 MAP kinase might be involved in IFN-gamma signaling and the feedback regulation of neutrophil apoptosis.
 ...
PMID:Activation of mitogen-activated protein kinases during granulocyte apoptosis in patients with severe sepsis. 1241 17

An imbalance between thrombin and antithrombin III contributed to vascular hyporeactivity in sepsis, which can be attributed to excess NO production by inducible nitric-oxide synthase (iNOS). In view of the importance of the thrombin-activated coagulation pathway and excess NO as the culminating factors in vascular hyporeactivity, this study investigated the effects of thrombin on the induction of iNOS and NO production in macrophages. Thrombin induced iNOS protein in the Raw264.7 cells, which was inhibited by a thrombin inhibitor, LB30057. Thrombin increased NF-kappaB DNA binding, whose band was supershifted with anti-p65 and anti-p50 antibodies. Thrombin elicited the phosphorylation and degradation of I-kappaBalpha prior to the nuclear translocation of p65. The NF-kappaB-mediated iNOS induction was stimulated by the overexpression of activated mutants of Galpha(12/13) (Galpha(12/13)QL). Protein kinase C depletion inhibited I-kappaBalpha degradation, NF-kappaB activation, and iNOS induction by thrombin or the iNOS induction by Galpha(12/13)QL. JNK, p38 kinase, and ERK were all activated by thrombin. JNK inhibition by the stable transfection with a dominant negative mutant of JNK1 (JNK1(-)) completely suppressed the NF-kappaB-mediated iNOS induction by thrombin. Conversely, the inhibition of p38 kinase enhanced the expression of iNOS. In addition, JNK and p38 kinase oppositely controlled the NF-kappaB-mediated iNOS induction by Galpha(12/13)QL. Hence, iNOS induction by thrombin was regulated by the opposed functions of JNK and p38 kinase downstream of Galpha(12/13). In the JNK1(-) cells, thrombin did not increase either the NF-kappaB binding activity or I-kappaBalpha degradation despite I-kappaBalpha phosphorylation. These results demonstrated that thrombin induces iNOS in macrophages via Galpha(12) and Galpha(13), which leads to NF-kappaB activation involving the protein kinase C-dependent phosphorylation of I-kappaBalpha and the JNK-dependent degradation of phosphorylated I-kappaBalpha.
 ...
PMID:Thrombin induces nitric-oxide synthase via Galpha12/13-coupled protein kinase C-dependent I-kappaBalpha phosphorylation and JNK-mediated I-kappaBalpha degradation. 1260 53

To treat complex human diseases effectively, a systems-level approach is needed to understand the interplay of environmental cues, intracellular signals, and cellular behaviors that underlie disease states. This approach requires high-throughput, multiplex techniques that measure quantitative temporal variations of multiple protein activities in the intracellular signaling network. Here, we describe a single microtiter-based format that simultaneously quantifies protein kinase activities in the phosphatidylinositol 3-kinase pathway (Akt), nuclear factor-kappaB pathway (IKK), and three core mitogen-activated protein kinase pathways (ERK, JNK1, MK2). These parallel high-throughput assays are stringently linear, redundantly specific, reproducible, and sensitive compared with classical low-throughput techniques. When applied to a model of sepsis-induced colon epithelial apoptosis, this approach identified a late phase of Akt activity as a critical mediator of cell survival that quantitatively contributed to the efficacy of insulin as an anti-apoptotic cue. Thus, sampling parallel nodes in the intracellular signaling network identified part of the molecular mechanism underlying the efficacy of insulin in the treatment of human sepsis.
 ...
PMID:A high-throughput quantitative multiplex kinase assay for monitoring information flow in signaling networks: application to sepsis-apoptosis. 1283 60

Endothelial cells facilitate sepsis-induced neutrophil adherence through the production of adhesion molecules and proinflammatory cytokines. The production of these factors requires coordinated intracellular inflammatory signaling. Recently, patients prone to sepsis-induced complications have been shown to have derangements in intracellular calcium and potentially calcium/calmodulin-dependent protein kinase (CaMK) activity, but the impact of these impairments is unknown. Human umbilical vein endothelial vein endothelial cells (HUVECs) were exposed to lipopolysaccharide (LPS) for various periods of time. Select HUVECs were pretreated with an inhibitor of CaMK II, KN62. Total cellular and nuclear proteins were extracted and analyzed for various components of the Toll-mediated signal cascade. Neutrophil adhesion was assayed fluorometrically using calcein-labeled neutrophils on treated HUVECs. LPS stimulation led to mitogen-activated protein kinase activation and translocation of activator protein-1 (AP-1) and nuclear factor (NF)-kappaB. CaMK blockade inhibited LPS induced ERK 1/2 and JNK but enhanced p38 activity. This selective MAPK inhibition was associated with a reduction in AP-1 activity, with no affect on NF-kappaB activity. Associated with this altered cell signaling was increased ICAM-1 production and enhanced neutrophil adhesion. Altered CaMK activity resulted in dysregulated mitogen-activated protein kinase signaling, demonstrated by reduced ERK 1/2 and JNK activity but enhanced p38 activity. This altered signaling is associated with reduced AP-1 activation and unaffected NF-kappaB activation. Neutrophil adhesion, however, is enhanced presumably through increased ICAM-1 production. Therefore, CaMK inhibition of endothelial cells, characteristic of sustained increases in intracellular calcium, appears to result in a dysregulated proadhesive phenotype.
 ...
PMID:Modulation of endotoxin-induced endothelial function by calcium/calmodulin-dependent protein kinase. 1286 64

Thermal injury increases the capacity of macrophages (Mphi) to produce various inflammatory mediators, (i.e., Mphi hyperactivity), which is believed to be involved in the development of subsequent immunosuppression, sepsis, and multiple organ failure. The signal transduction pathways involved in the expression of Mphi hyperactivity post-burn, however, remain to be clearly elucidated. To study this C57BL/6 female mice were subjected to a 25% TBSA burn and splenic Mphis were isolated 7 days later. LPS-stimulated inflammatory mediator production and MAPK expression (P38 ERK 1/2 and JNK) were determined. Burn injury increased LPS-induced P38 MAPK, suppressed JNK activation and ERK 1/2 activation was unaltered. These changes in MAPK activation were paralleled by the increased production of PGE(2), TNF-alpha, IL-1beta, IL-6, and IL-10. Differential sensitivity to the inhibition of the MAPK pathways was observed with regard to the mediator evaluated and the presence or absence of burn injury. In general cytokine production in the burn group was in part resistant to the inhibition of a single MAPK pathway as compared with shams. Thus, burn injury increases cross-talk between the MAPKs pathways, suggesting that alterations MAPK activation and signal transduction contribute to the development Mphi hyperactivity post-injury.
 ...
PMID:MAP kinases differentially regulate the expression of macrophage hyperactivity after thermal injury. 1528 Oct 87

Sepsis caused by gram-positive bacteria lacking lipopolysaccharide (LPS) has become a major and increasing cause of mortality in intensive-care units. We have recently demonstrated that the gram-positive-specific bacterial cell wall component lipoteichoic acid (LTA) stimulates the release of the proinflammatory cytokines in Kupffer cells in culture. In the present study, we have started to assess the signal transduction events by which LTA induces the production of tumor necrosis factor alpha (TNF-alpha), interleukin-6 (IL-6), and the anti-inflammatory cytokine IL-10 in rat Kupffer cells. LTA was found to trigger phosphorylation of mitogen-activated protein kinases (MAPK) (p38 MAPK and ERK 1/2) and protein kinase B (PKB). Compared to LPS, LTA was more potent in inducing PKB phosphorylation after 40 min, although we found that the cytokine responses were similar. For both bacterial molecules, blocking phosphatidylinositol 3-kinase (PI3-K; Ly294002) or Janus kinase 2 (JAK-2; AG490) particularly affected the induction of IL-6 and IL-10 release, whereas TNF-alpha levels were strongly reduced by inhibition of Src family tyrosine kinases (PP2). All three cytokines were reduced by inhibition of p38 MAPK (SB202190) or the broad-range tyrosine kinase inhibitor genistein, whereas IL-6 release was particularly blocked by inhibition of ERK 1/2 (PD98059). Divergences in the regulatory pathways controlling TNF-alpha, IL-10, and IL-6 production in Kupffer cells following LPS or LTA stimulation may create a basis for understanding how the balance between pro- and anti-inflammatory cytokines is regulated in the liver following infections by gram-positive or gram-negative bacteria.
 ...
PMID:The phosphatidylinositol 3-kinase/protein kinase B signaling pathway is activated by lipoteichoic acid and plays a role in Kupffer cell production of interleukin-6 (IL-6) and IL-10. 1538 69


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