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Summary U18666A is a cholesterol transport-inhibiting agent that is used widely to mimic Niemann–Pick type C disease. The effect of U18666A on tumour necrosis factor (TNF)-α production in mouse macrophage cell line, RAW 264·7 cells and peritoneal macrophages was examined. U18666A induced TNF-α mRNA expression 48 h after the treatment, and TNF-α production 48 and 72 h after stimulation in RAW 264·7 cells. U18666A accumulated intracellular free cholesterol in the culture of normal medium but not cholesterol-free medium. U18666A also induced reactive oxygen species (ROS) generation in normal medium but much less in cholesterol-free medium. Anti-oxidant N-acetyl-L-cysteine (NAC) abolished U18666A-induced TNF-α production. U18666A led to the phosphorylation of p38 mitogen-activated protein kinase 24 and 48 h after the stimulation and the p38 activation was inhibited in presence of cholesterol-free medium or NAC. A p38 inhibitor reduced U18666A-induced TNF-α production. Taken together, U18666A was suggested to induce TNF-α production in RAW 264·7 cells via free cholesterol accumulation-mediated ROS generation.

The effect of toll-like receptor (TLR) 7 ligand pretreatment on the production of tumor necrosis factor (TNF)-α in response to TLR7 or TLR2 ligand was examined in order to establish a new TLR-mediated tolerance. RAW 264.7 macrophage-like cells were treated with imiquimod R837 as a TLR7 ligand for 18 h, washed and incubated in fresh culture medium 6 h. The second challenge with imiquimod R837 as a TLR7 ligand or Pam3CysSK4 as a TLR2 ligand resulted in reduced TNF-α production in TLR7 ligand-pretreated cells. There was impaired activation of NF-κB, p38 and stress-activated protein kinase (SAPK) in the tolerant cells. The expression of IRAK-M as a negative regulator of TLR signaling was markedly augmented in the tolerant cells while the interleukin-1 receptor-associated kinase (IRAK)-1 functioned normally. The involvement of IRAK-M in the TLR7-mediated tolerance is discussed.

The mechanism of interleukin (IL)-10-mediated inhibition of tumor necrosis factor (TNF)-α production was studied by lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophage cells. IL-10 inhibited TNF-α production transiently at an early stage after LPS stimulation. IL-10 inhibited the activation of nuclear factor (NF)-κB, p38 and stress-activated protein kinase (SAPK) in LPS-stimulated RAW 264.7 cells. Although the level of MyD88 protein increased in response to LPS, IL-10 prevented the LPS-induced MyD88 augmentation. There was no significant difference in the MyD88 mRNA expression between the cells pretreated with or without IL-10 in response to LPS. Therefore, IL-10 was suggested to inhibit LPS-induced TNF-α production via reduced MyD88 expression.

The mechanism underlying acute lung injury in lethal endotoxic shock induced by administration of lipopolysaccharide (LPS) into alpha-galactosylceramide (alpha-GalCer)-sensitized mice was studied. Sensitization with alpha-GalCer resulted in the increase of natural killer T (NK T) cells and the production of interferon (IFN)-gamma in the lung. The IFN-gamma that was produced induced expression of adhesion molecules, especially vascular cell adhesion molecule-1 (VCAM-1), on vascular endothelial cells in the lung. Anti-IFN-gamma antibody inhibited significantly the VCAM-1 expression in alpha-GalCer-sensitized mice. Very late activating antigen-4-positive cells, as the counterpart of VCAM-1, accumulated in the lung. Anti-VCAM-1 antibody prevented LPS-mediated lethal shock in alpha-GalCer-sensitized mice. The administration of LPS into alpha-GalCer-sensitized mice caused local production of excessive proinflammatory mediators, such as tumour necrosis factor (TNF)-alpha, interleukin (IL)-1beta, IL-6 and nitric oxide. LPS caused microvascular leakage of proteins and cells into bronchoalveolar lavage fluid. Taken together, sensitization with alpha-GalCer was suggested to induce the expression of VCAM-1 via IFN-gamma produced by NK T cells and recruit a number of inflammatory cells into the lung. Further, LPS was suggested to lead to the production of excessive proinflammatory mediators, the elevation of pulmonary permeability and cell death. The putative mechanism of acute lung injury in LPS-mediated lethal shock using alpha-GalCer sensitization is discussed.

Summary The effect of interferon (IFN)-γ and/or lipopolysaccharide (LPS) on Fas-mediated cell death with anti-Fas agonistic antibody in vascular endothelial cells was examined using a mouse END-D cell line. Anti-Fas agonistic antibody exhibited cytotoxic actions on END-D cells. Fas-mediated cell death was enhanced by LPS or IFN-γ. The combination of IFN-γ and LPS significantly enhanced cell death compared to IFN-γ or LPS alone. IFN-γ and LPS augmented cell surface expression of Fas, but not tumour necrosis factor (TNF) receptor 1. Inhibitors of p38 mitogen-activated protein kinase (MAPK) prevented augmentation of Fas expression in IFN-γ and LPS-treated END-D cells. IFN-γ and LPS-treated END-D cells did not become susceptible to TNF-α or nitric oxide-mediated cytotoxicity. IFN-γ and LPS thus appear to augment selectively Fas expression via activation of p38 MAPK and enhance Fas-mediated cell death in END-D cells. Furthermore, administration of IFN-γ and LPS into mice induced in vivo expression of Fas on vascular endothelial cells and Fas ligand (FasL) on peripheral blood leucocytes. The relationship between enhancement of Fas-mediated cell death by IFN-γ and LPS and the development of vascular endothelial injury is discussed.

Lipopolysaccharide (LPS) enhances the production of nitric oxide (NO) in interferon (IFN)-gamma-stimulated vascular endothelial cells. We studied the mechanism by which LPS enhances IFN-gamma-induced NO production by using the murine vascular endothelial cell line, END-D. LPS enhanced IFN-gamma-induced NO production via augmented expression of inducible type NO synthase (iNOS) mRNA. LPS significantly augmented the activation of interferon regulatory factor (IRF)-1 in IFN-gamma-stimulated END-D cells, although it did not affect the activation of either MyD88-dependent nuclear factor (NF)-kappaB or MyD88-independent IRF-3. SB203580, an inhibitor of p38 mitogen-activated protein kinase (MAPK), prevented the nuclear translocation of IRF-1 in LPS and IFN-gamma-stimulated END-D cells, and inhibited the iNOS expression and NO production in those cells. Therefore, it is proposed that LPS enhanced NO production in IFN-gamma-stimulated END-D cells via augmenting p38 MAPKmediated IRF-1 activation.

Antioxidants are able to inhibit inflammatory gene expression in response to lipopolysaccharide via down-regulating generation of intracellular reactive oxygen species (ROS) as second messengers. The effect of manganese (III) tetrakis (4-benzoic acid) porphyrin (MnTBAP), a synthetic metalloporphyrin with antioxidant activity, on tumor necrosis factor (TNF)-alpha production in lipopolysaccharide-stimulated RAW 264.7 macrophage cells was examined. MnTBAP prevented the generation of intracellular ROS in lipopolysaccharide-stimulated RAW 264.7 cells and further inhibited lipopolysaccharide-induced TNF-alpha production. MnTBAP exclusively prevented the phosphorylation of p38 mitogen-activated protein kinase (MAPK) and stress-activated protein kinase (SAPK/JNK) whereas it did not affect the phosphorylation and activation of nuclear factor-kappaB and extracellular signal regulated kinase 1/2. MnTBAP was suggested to inhibit lipopolysaccharide-induced TNF-alpha production by the prevention of intracellular ROS generation and subsequent inactivation of p38 MAPK and SAPK/JNK.

The effect of 5-fluorouracil (5-FU) on the production of nitric oxide (NO) in macrophages was examined by using lipopolysaccharide (LPS)-stimulated RAW 264.7 cells. 5-FU at non-toxic concentrations significantly inhibited NO production in LPS-stimulated RAW 264.7 cells. The inhibition by 5-FU was mediated by attenuated expression of an inducible NO synthase protein and mRNA. 5-FU inhibited the activation of nuclear factor (NF)-kappaB and the subsequent nuclear translocation. Furthermore, 5-FU inhibited the phosphorylation of Akt, an upstream molecule of NF-kappaB signaling. 5-FU did not affect a series of mitogen-activated protein kinases. Therefore, 5-FU was suggested to inhibit the LPS-induced NO production in activated macrophages through preventing Akt-dependent NF-kappaB activation.

The effect of lipopolysaccharide (LPS) on the cell death induced by endoplasmic reticulum (ER) stress agents in RAW 264.7 cells was studied. LPS prevented the cell death by brefeldin A, but not thapsigargin and tunicamycin. CpG DNA as well as LPS prevented brefeldin A-induced cell death whereas tumor necrosis factor-alpha or interferon-gamma did not. Brefeldin A-induced cell death was mediated with apoptotic cell death and it was significantly inhibited by LPS. LPS abolished the activation of ER stress-related caspases, such as caspases 1, 3, and 4. LPS prevented brefeldin A-induced morphological changes in RAW 264.7 cells. Further, LPS prevented brefeldin A-induced Golgi dispersion. Therefore, LPS was suggested to diminish the stress of ER/Golgi complexes induced by brefeldin A and inhibit apoptosis. The preventive action of LPS on brefeldin A-induced apoptosis is discussed.

The effect of alpha-galactosylceramide (alpha-GalCer) on lipopolysaccharide (LPS)-induced nitric oxide (NO) production in mouse peritoneal cells was studied. alpha-GalCer augmented LPS-induced NO production in mouse peritoneal cells, but not in RAW 264.7 macrophage cells. alpha-GalCer augmented NO production, but not tumor necrosis factor (TNF)-alpha production in LPS-stimulated peritoneal cells. Peritoneal cells produced a significant level of interferon (IFN)-gamma in response to alpha-GalCer and anti-IFN-gamma antibody abolished the augmentation of LPS-induced NO production by alpha-GalCer. Moreover, anti-IFN-gamma antibody prevented the enhanced expression of an inducible type of NO synthase mRNA by alpha-GalCer. alpha-GalCer did not augment LPS-induced NO production in peritoneal cells from natural killer T (NKT)-deficient mice. Therefore, it was suggested that alpha-GalCer might augment LPS-induced NO production in peritoneal cells through release of IFN-gamma from NKT cells.

The effect of lipopolysaccharide on doxorubicin-induced cell death was studied by using mouse RAW 264.7 macrophage cells. Pretreatment with lipopolysaccharide at 10 ng/mL prevented doxorubicin-induced cell death and the inhibition was roughly dependent on the concentration of lipopolysaccharide. Posttreatment with lipopolysaccharide for 1 hour also prevented doxorubicin-induced cell death. Lipopolysaccharide inhibited DNA fragmentation and caspase-3 activation in doxorubicin-treated RAW 264.7 cells, suggesting the prevention of doxorubicin-induced apoptosis. Lipopolysaccharide did not significantly inhibit doxorubicin-induced DNA damage detected by single-cell gel electrophoresis (comet) assay. Lipopolysaccharide definitely inhibited the stabilization and nuclear translocation of p53 in doxorubicin-treated RAW 264.7 cells. Lipopolysaccharide, as well as being an inhibitor of p53, abolished doxorubicin-induced apoptosis. Therefore, p53 was suggested to play a pivotal role in the prevention of doxorubicin-induced apoptosis in RAW 264.7 cells by lipopolysaccharide.

The role of p38 mitogen-activated protein kinase (MAPK) on vacuole formation in lipopolysaccharide (LPS)-stimulated RAW 264.7 cells was examined. LPS definitely induced the formation of vacuoles in RAW 264.7 cells and SB202190 as a p38 specific inhibitor also induced slight vacuole formation. The simultaneous treatment with LPS and SB202190 induced many more vacuoles in RAW 264.7 cells than the treatment with LPS or SB202190 alone, and the vacuoles were extraordinarily large in size. On the other hand, an inactive inhibitor of p38 MAPK did not augment LPS-induced vacuole formation. Further, the inhibitors of other MAPKs and nuclear factor (NF)-kappaB pathways did not affect it. The extraordinarily large vacuoles in RAW 264.7 cells treated with LPS and SB202190 were possibly formed via fusion of small vacuoles. However, SB202190 did not augment vacuole formation in CpG DNA or interferon (IFN)-gamma-stimulated RAW 264.7 cells. The role of p38 MAPK in the vacuole formation in LPS-stimulated macrophages is discussed.

The effect of piceatannol on lipopolysaccharide (LPS)-induced nitric oxide (NO) production was examined. Piceatannol significantly inhibited NO production in LPS-stimulated RAW 264.7 cells. The inhibition was due to the reduced expression of an inducible isoform of NO synthase (iNOS). The inhibitory effect of piceatannol was mediated by down-regulation of LPS-induced nuclear factor (NF)-kappaB activation, but not by its cytotoxic action. Piceatannol inhibited IkappaB kinase (IKK)-alpha and beta phosphorylation, and subsequently IkappaB-alpha phosphorylation in LPS-stimulated RAW 264.7 cells. On the other hand, piceatannol did not affect activation of mitogen-activated protein (MAP) kinases including extracellular signal regulated kinase 1/2 (Erk1/2), p38 and stress-activated protein kinase/c-Jun NH2-terminal kinase (SAPK/JNK). Piceatannol inhibited the phosphorylation of Akt and Raf-1 molecules, which regulated the activation of IKK-alpha and beta phosphorylation. The detailed mechanism of the inhibition of LPS-induced NO production by piceatannol is discussed.

Twenty-one atypicalShigella flexneritype 4 strains isolated from patients attending the Dhaka treatment center of the International Centre for Diarrhoeal Disease Research, Bangladesh, were extensively characterized and compared withS. flexneriserotypes 4a and 4b. The atypical strains agglutinated only with the type antigen factor 4 and did not agglutinate with any group factors, thereby excluding their characterization into serotype 4a or 4b. Of the 21 strains, 85.7% did not ferment mannitol but were able to ferment most of the sugars, whereas the remaining 14.3% strains fermented mannitol but were unable to ferment most of the sugars. Most of the strains were resistant to ampicillin, tetracycline, and trimethoprim-sulfomethoxazole. All of the strains harbored the 140-MDa plasmid, had theipaHgene, had thesengene (encodingShigellaenterotoxin 2), had the ability to bind Congo red, and were positive for keratoconjunctivitis in the guinea pig eye, attesting their invasive properties. All of the strains contained a middle-range plasmid (35 to 62 MDa) as well as a number of stable small plasmids, yielding mainly two plasmid profiles which were different from those of 4a and 4b strains. Conjugation and curing experiments suggested that the middle-range plasmids harbored a self-transferable multiple antibiotic resistance marker. Pulsed-field gel electrophoresis analysis of all of the tested strains yielded two types with numerous subtypes, whereas ribotyping yielded only two types which were completely different from those of types 4a and 4b. This study concluded that two different clones of atypicalS. flexneritype 4 exist and strongly suggests that these are new subserotypes ofS. flexnerithat await further serological classification.

Moraxella catarrhalis is a Gram-negative bacterium, exclusively present in humans and a leading causative agent of otitis media (OM) in children. Most children (80 %) experience at least one episode of OM by their third birthday and half suffer multiple episodes of infection. Over the last 10 years, increased evidence suggests that M. cat possesses multiple virulence factors which can be carried through biologically active outer membrane vesicles (OMVs) that are themselves able to activate host-immune responses. It has also been noted that multiple toll-like receptors are responsible for M. cat recognition. This review is intended to summarize the key findings and progress in recent years of the molecular mechanisms of M. cat-induced otitis media with particular emphasis on adhesion, invasion, and activation of the host immune system, biofilm formation, and vaccine development.

Moraxella catarrhalis is a gram negative bacterium and a leading causative agent of otitis media (OM) in children. Several recent reports have provided strong evidence for an association between toll like receptors and OM. It has been found that both Streptococcus pneumoniae and nontypeable Haemophilus influenzae activate host protective immune responses through toll like receptors (TLRs), however, the precise mechanism by which Moraxella catarrhalis initiates the host immune response is currently unknown. In this report, using murine macrophages generated from a series of knock-out mice, we have demonstrated that M. catarrhalis lipooligosaccharide (LOS) and either heat killed or live bacteria are recognized by one or more TLRs. LOS activates the host immune response through a membrane bound CD14-TLR4 complex, while both heat killed and live M.cat require recognition by multiple toll like receptors such as TLR2, TLR4 and TLR9 without the requirement of CD14. We have also shown that M.cat stimuli are capable of triggering the host innate immune response by both MyD88- and TRIF- dependent signaling pathways. We further showed that M.cat induced activation of mitogen activated protein kinase (MAPK) is essential in order to achieve optimal secretion of pro-inflammatory cytokine TNF-α. We finally showed that TLR4 mutant C3H/HeJ mice produce significantly lower levels of pro-inflammatory cytokines TNF-α and IL-6 in vivo, An increased bacterial loads at 12 and 24 hours (P

We have proposed the novel concept that the macrophage ubiquitin-proteasome pathway functions as a key regulator of Lipopolysaccharide (LPS)-induced inflammation signaling. These findings suggest that proteasome-associated protease subunits X, Y, and Z are replaced by LMP subunits after LPS treatment of RAW 264.7 cells. The objective here was to determine the contribution of selective LMP proteasomal subunits to LPS-induced nitric oxide (NO) and TNF-α production in primary murine macrophages. Accordingly, thioglycollate-elicited macrophages from LMP7, LMP2, LMP10 (MECL-1), and LMP7/MECL-1 double knockout mice were stimulated in vitro with LPS, and were found to generate markedly reduced NO levels compared to wild-type (WT) mice, whereas TNF-α levels responses were essentially unaltered relative to wild-type responses. The recent studies suggest that the TRIF/TRAM pathway is defective in LMP knockouts which may explain why iNOS/NO are not robustly induced in LPS-treated macrophages from knockouts. Treating these macrophages with IFN-γ and LPS, however, reverses this defect, leading to robust NO induction. TNF-α is induced by LPS in the LMP knockout macrophages because IκB and IRAK are degraded normally via the MyD88 pathway. Collectively, these findings strongly support the concept that LMP7/MECL-1 proteasomes subunits actively function to regulate LPS-induced NO production by affecting the TRIF/TRAM pathway.

The effect of thalidomide on lipopolysaccharide (LPS)-induced tumor necrosis factor (TNF)-α production was studied by using RAW 264.7 murine macrophage-like cells. Thalidomide significantly inhibited LPS-induced TNF-α production. Thalidomide prevented the activation of nuclear factor (NF)-KB by down-regulating phosphorylation of inhibitory KB factor (IKB), and IKB kinase (IKK)-α and IKK-β Moreover, thalidomide inhibited LPS-induced phosphorylation of AKT, p38 and stress-activated protein kinase (SAPK)/JNK. The expression of myeloid differentiation factor 88 (MyD88) protein and mRNA was markedly reduced in thalidomide-treated RAW 264.7 cells but there was no significant alteration in the expression of interleukin-1 receptor-associated kinase (IRAK) 1 and TNF receptor-associated factor (TRAF) 6 in the cells. Thalidomide did not affect the cell surface expression of Toll-like receptor (TLR) 4 and CD14, suggesting the impairment of intracellular LPS signalling in thalidomide-treated RAW 264.7 cells. Thalidomide significantly inhibited the TNF-α production in response to palmitoyl-Cys(RS)-2,3-di(palmitoyloxy) propyl)-Ala-Gly-OH (Pam3Cys) as a MyD88-dependent TLR2 ligand. Therefore, it is suggested that thalidomide might impair LPS signalling via down-regulation of MyD88 protein and mRNA and inhibit LPS-induced TNF-α production. The putative mechanism of thalidomide-induced MyD88 down-regulation is discussed.

RAW 264.7 macrophage cells differentiate into osteoclast-like cells in the presence of RANKL. Participation of M-CSF in RANKL-induced osteoclast formation of RAW 264.7 cells was examined. TRAP-positive osteoclast-like cells appeared in RAW 264.7 cells cultured in the presence of RANKL. RANKL-induced osteoclast formation was markedly inhibited by anti-M-CSF antibody. RANKL augmented M-CSF mRNA expression and M-CSF production in RAW 264.7 cells. Further, anti-M-CSF antibody inhibited the expression of RANK, c-fms, c-fos and TRAP mRNA in RANKL-stimulated RAW 264.7 cells. However, anti-M-CSF antibody did not affect the expression of DC-STAMP in the stimulated cells. Therefore, RANKL was suggested to induce osteoclast formation in RAW 264.7 cells via augmented production of M-CSF. The putative role of M-CSF in RANKL-induced osteoclast formation of RAW 264.7 cells is discussed.

Summary The effect of lipopolysaccharide (LPS) on the in vivo lethal action of doxorubicin (DOX) against mice was studied. DOX killed LPS-pretreated mice much earlier than untreated mice, and exhibited a stronger toxic action against LPS-pretreated mice. DOX-induced lethality in LPS-pretreated mice was due to severe hepatic damage, but there were no significant lesions in the heart, kidney and lung. Hepatic lesions were accompanied by caspase 3-positive cells and fragmented DNA-positive cells, suggesting the involvement of apoptosis. DOX induced the production of a high level of interferon (IFN)-γ and tumour necrosis factor (TNF)-α in LPS-pretreated mice, but not in non-treated mice. The DOX-induced lethality was prevented significantly by anti-IFN-γ antibody, but not anti-TNF-α antibody. Administration of recombinant IFN-γ in place of LPS augmented definitively the DOX-induced lethality. LPS augmented the DOX-induced lethality in TNF-α-deficient mice. Taken together, LPS was suggested to enhance DOX-induced IFN-γ production and augment the in vivo lethal action via hepatic damage.

Lipopolysaccharide (LPS) is a potent bone resorbing factor. The effect of LPS on osteoclast formation was examined by using murine RAW 264.7 macrophage cells. LPS-induced the formation of multinucleated giant cells (MGC) in RAW 264.7 cells 3 days after the exposure. MGCs were positive for tartrate-resistant acid phosphatase (TRAP) activity. Further, MGC formed resorption pits on calcium-phosphate thin film that is a substrate for osteoclasts. Therefore, LPS was suggested to induce osteoclast formation in RAW 264.7 cells. LPS-induced osteoclast formation was abolished by anti-tumor necrosis factor (TNF)-alpha antibody, but not antibodies to macrophage-colony stimulating factor (M-CSF) and receptor activator of nuclear factor (NF)-kappaB ligand (RANKL). TNF-alpha might play a critical role in LPS-induced osteoclast formation in RAW 264.7 cells. Inhibitors of NF-kappaB and stress activated protein kinase (SAPK/JNK) prevented the LPS-induced osteoclast formation. The detailed mechanism of LPS-induced osteoclast formation is discussed.

Previously, we found that mouse TH2.52 cells possess the characteristic of CD5+ B1 cells and proliferate in response to lipopolysaccharide (LPS). The effect of LPS on cytokine production by TH2.52 B1 cells was studied. TH2.52 cells constitutively produced a small amount of tumor necrosis factor (TNF)-α and interleukin (IL)-6, and TNF-α and IL-6 production was markedly enhanced by LPS stimulation. Although interferon (IFN)-γ caused the production of various cytokines, such as IL-2, IL-4, IL-6 and TNF-α in TH2.52 cells, LPS did not cause the production of such cytokines. LPS did not induce IFN-β production in TH2.52 cells and TH2.52 cells lacked the expression of several molecules participating in the MyD88-independent pathway in LPS signaling. Defective responsiveness of TH2.52 B1 cells to LPS in cytokine production might be responsible for the failure of IFN-β production due to the lack of molecules participating in the MyD88-independent pathway.

Biological activities of lipopolysaccharide (LPS) from Brucella melitensis 16M were characterized in comparison with LPS from Escherichia coli O55. LPS extracted from B. melitensis was smooth type by electrophoretic analysis with silver staining. The endotoxin-specific Limulus activity of B. melitensis LPS was lower than that of E. coli LPS. There was no significant production of tumor necrosis factor-alpha and nitric oxide in RAW 264.7 macrophage cells stimulated with B. melitensis LPS, although E. coli LPS definitely induced their production. On the other hand, B. melitensis LPS exhibited a higher anti-complement activity than E. coli LPS. B. melitensis LPS as well as E. coli LPS exhibited a strong adjuvant action on antibody response to bovine serum. The characteristic biological activities of B. melitensis are discussed.

The effect of alpha-galactosylceramide (alpha-GalCer) on lipopolysaccharide (LPS)-mediated lethality was examined. Administration of LPS killed all mice pretreated with alpha-GalCer, but not untreated control mice. The lethal shock in alpha-GalCer-sensitized mice was accompanied by severe pulmonary lesions with marked infiltration of inflammatory cells and massive cell death. On the other hand, hepatic lesions were focal and mild. A number of cells in pulmonary and hepatic lesions underwent apoptotic cell death. alpha-GalCer sensitization was ineffective for the development of the systemic lethal shock in Valpha14-positive natural killer T cell-deficient mice. Sensitization with alpha-GalCer led to the circulation of a high level of interferon (IFN)-gamma and further augmented the production of tumor necrosis factor (TNF)-alpha in response to LPS. The lethal shock was abolished by the administration of anti-IFN-gamma or TNF-alpha antibody. Further, the lethal shock did not occur in TNF-alpha-deficient mice. Taken together, alpha-GalCer sensitization rendered mice very susceptible to LPS-mediated lethal shock, and IFN-gamma and TNF-alpha were found to play a critical role in the preparation and execution of the systemic lethal shock, respectively. The LPS-mediated lethal shock using alpha-GalCer sensitization might be useful for researchers employing experimental models of sepsis and septic shock.

The present study was conducted to determine effects of U0126, a specific inhibitor of mitogen-activated kinase kinase 1/2, on production of nitric oxide (NO) in RAW264.7 macrophage cells. U0126 significantly enhanced NO production in lipopolysaccharide (LPS) but not CpG DNA or interferon-gamma-stimulated RAW264.7 cells. In contrast, U0124, a negative control for U0126, did not affect LPS-induced NO production. Further, a series of inhibitors of p38, phosphatidyl-inositol 3-kinase and Janus tyrosine kinase rather caused suppression in LPS-stimulated RAW264.7 cells. U0126 was found to definitely inhibit phosphorylation of extracellular signal-regulated kinase (Erk) 1/2 and augment the levels of inducible type of NO synthase. Antisense oligonucleotides of Erk1/2 also augmented LPS-induced NO production. Inactivation of Erk1/2 by U0126 furthermore inhibited LPS-induced activating protein-1 activation, but not nuclear factor-kappaB activation. The results suggest that Erk1/2 might negatively regulate NO production in LPS-stimulated RAW264.7 cells.

The effect of inhibition of mitogen and stress-activated protein kinases 1/2 (MSK1/2) on lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophage cells was investigated. Pretreatment with Ro 31-8220, an inhibitor of MSK1/2, induced cell death in LPS-stimulated RAW 264.7 cells. In contrast, calphostin C, another inhibitor of protein kinase C, did not cause cell death. Cell death was not mediated by the release of pro-inflammatory mediators from LPS-stimulated RAW 264.7 cells. Cell death was accompanied by DNA fragmentation and annexin V binding, suggesting apoptotic cell death. Further, several caspase inhibitors did not prevent LPS-induced cell death of Ro 31-8220-pretreated RAW 264.7 cells. Nuclear translocation of apoptosis-inducing factor (AIF) was detected in Ro 31-8220-pretreated cells after LPS stimulation. Cell death was due to mitochondrial damage. Ro 31-8220 exclusively inhibited the phosphorylation of cAMP-responsive element binding protein (CREB), a substrate of MSK1/2. RAW 264.7 cells transfected with the dominant-negative MSK1 clones underwent cell death in response to LPS. Hence, it was suggested that MSK1/2 might play a critical role in the survival of LPS-stimulated RAW 264.7 cells.

The effect of butyrate, a natural bacterial product of colonic bacterial flora, on nitric oxide (NO) production in murine vascular endothelial cell line END-D in response to IFN-gamma and/or LPS was studied. Butyrate significantly augmented NO production in END-D cells in response to IFN-gamma or IFN-gamma + LPS, but not LPS alone. The NO production was augmented by the addition of butyrate until 6 h after the stimulation with IFN-gamma or IFN-gamma + LPS. The augmentation was abolished by the removal of butyrate from the cultures. Butyrate enhanced the expression of inducible type NO synthase (iNOS) in the stimulated END-D cells. Furthermore, butyrate-enhanced NO production in the presence of various signal inhibitors down-regulating the signal pathways using nuclear factor (NF)-kappaB, mitogen-activated protein (MAP) kinases and Janus tyrosine kinase. The putative mechanism of butyrate-induced augmentation of NO production in response to IFN-gamma or IFN-gamma + LPS is discussed.

The effect of D-galactosamine (D-GalN) on nitric oxide (NO) production in lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophage cells was examined. D-GalN augmented the production of NO, but not tumor necrosis factor (TNF)-alpha in LPS-stimulated RAW 264.7 cells. Pretreatment of D-GalN augmented the NO production whereas its post-treatment did not. D-GalN augmented the NO production in RAW 264.7 cells stimulated with either TNF-alpha and interferon-gamma. The augmentation of LPS-induced NO production by D-GalN was due to enhanced expressions of an inducible type of NO synthase mRNA and proteins. Intracellular reactive oxygen species (ROS) were exclusively generated in RAW 264.7 cells stimulated with D-GalN and LPS. Scavenging of intracellular ROS abrogated the augmentation of NO production. It was therefore suggested that D-GalN might augment LPS-induced NO production through the generation of intracellular ROS.

Moraxella catarrhalis is a gram negative bacterium and a leading causative agent of otitis media (OM) in children. Recent reports have provided strong evidence for the presence of high levels of matrix metalloproteinase (MMPs) in effusion fluids from children suffering with OM, however, the precise mechanisms by which MMPs are generated are currently unknown. We hypothesized that MMPs are secreted from macrophages in the presence of M. catarrhalis lipooligosaccharide (LOS). In this report, we demonstrate that in vitro stimulation of murine macrophage RAW 264.7 cells with LOS leads to secretion of MMP-9 as determined by ELISA and zymogram assays. We have also shown that inhibition of ERK1/2 and p38 kinase completely blocked LOS induced MMP-9 production. In contrast, inhibition of JNK1/2 by the specific inhibitor SP600125 actually increased the level of expression and production of MMP-9 at both mRNA and protein levels, respectively by almost five fold. This latter result was confirmed by knocking down JNK1/2 using siRNA. Similar results have been observed in murine bone marrow derived macrophages in vitro. In contrast to and in parallel with the LOS-induced increased levels of MMP-9 in the presence of SP600125, we found a corresponding dose-dependent inhibition of TIMP-1 (tissue inhibitor of matrix metalloproteinase-1) secretion. Results of subsequent in vitro studies provided evidence that when JNK1/2 was inhibited prior to stimulation with LOS, it significantly increased both the extent of macrophage cell migration and invasion compared to control cells or cells treated with LOS alone. The results of these studies contribute to an increased understanding of the underlying pathophysiology of OM with effusion in children.

Background: There are no licensed vaccines available against Moraxella catarrhalis, a significant human respiratory pathogen. Lipooligosaccharide (LOS) based conjugate vaccines derived from individual serotype M. catarrhalis only showed partial protection coverage. A vaccine combining LOS conjugates of two or three serotypes might provide a broader protection. Methods: Mice were immunized intranasally with the combined conjugates consisting of LOS from serotype A and B or serotype A, B, and C followed by challenge with different M. catarrhalis strains of three serotypes. Mouse lungs, nasal washes, and sera were collected after each challenge for bacterial counts, histological evaluation, cytokine profiles, antibody level and binding activity determinations. Results: Intranasal administration of the combined LOS conjugates not only enhanced pulmonary bacterial clearance of all three serotypes of M. catarrhalis strains in vaccinated mice, but also elevated serotype-specific anti-LOS immunoglobulin (Ig)A and IgG titers in nasal wash and serum respectively. Mice vaccinated with the combined LOS conjugates also showed increased interferon (IFN)-c, interleukin (IL)-12, and IL-4 in the lungs after challenges. Compared to the control group, mice immunized with the combined LOS conjugates also showed reduced lung inflammation after M. catarrhalis infections. The hyperimmune sera induced by the combined conjugates exhibited a broad cross-reactivity toward all three serotypes of M. catarrhalis under transmission electron microscopy. Conclusions: The combined vaccine of serotype A and B LOS conjugates provides protection against most M. catarrhalis strains by eliciting humoral and cellular immune responses.