Induction of apoptosis in lymphoid tissues of mice after intramuscular injection of enterotoxigenic Escherichia coli enterotoxin

Although it has been reported that intravenous injection of Escherichia coli enterotoxin induces atrophies of the thymus and spleen by necrosis, the toxin injected intramuscularly to mice induced atrophies of both tissues, which were associated with apoptosis of lymphocytes. Apoptosis predominantly occurred in the thymus and increased in a time-dependent manner up to 26 h and faint ladder band patterns of DNA were observed at 36 h. Although the high dose of toxin also induced in vitro apoptosis in cultured thymocytes, the toxin was not detected in the serum at levels sufficient to cause in vitro apoptosis after intramuscular administration. By flow cytometric analysis, CD4+ CD8+ double-positive T cell and CD45+ positive B cell numbers were found to be mainly decreased in thymus and spleen, respectively, of mice. These results suggest that the atrophies of thymus and spleen by intramuscular administration of the toxin to mice are due to apoptosis of CD4+ CD8+ double-positive T and CD45+ positive B cells, respectively, but the toxin does not reach these cells via the circulation. A different mechanism from that in vitro in cultured cells might be involved in the induction of apoptosis in vivo.

Two distinct antigenic types of the polysaccharide chains of Helicobacter pylori lipopolysaccharides characterized by reactivity with sera from humans with natural infection

We have purified lipopolysaccharides (LPS) from 10 Helicobacter pylori clinical isolates which were selected on the basis of chemotype and antigenic variation. Data from immunoblotting of the purified LPS with sera from humans with H. pylori infection and from absorption of the sera with LPS indicated the presence of two distinct epitopes, termed the highly antigenic and the weakly antigenic epitopes, on the polysaccharide chains. Among 68 H. pylori clinical isolates, all smooth strains possessed either epitope; the epitopes were each carried by about 50% of the smooth strains. Thus, H. pylori strains can be classified into three types on the basis of their antigenicity in humans: those with smooth LPS carrying the highly antigenic epitope, those with smooth LPS carrying the weakly antigenic epitope, and those with rough LPS. Sera from humans with H. pylori infection could be grouped into three categories: those containing immunoglobulin G (IgG) antibodies against the highly antigenic epitope, those containing IgG against the weakly antigenic epitope, and those containing both specific IgGs; these groups made up about 50%, less than 10%, and about 40%, respectively, of all infected sera tested. In other words, IgG against the highly antigenic epitope were detected in more than 90% of H. pylori-infected individuals with high titers. IgG against the weakly antigenic epitope were detected in about 50% of the sera tested; however, the antibody titers were low. The two human epitopes existed independently from the mimic structures of Lewis antigens, which are known to be an important epitope of H. pylori LPS. No significant relationship between the reactivities toward purified LPS of human sera and a panel of anti-Lewis antigen antibodies was found. Moreover, the reactivities of the anti-Lewis antigen antibodies, but not human sera, were sensitive to particular alpha-L-fucosidases. The human epitopes appeared to be located on O-polysaccharide chains containing endo-beta-galactosidase-sensitive galactose residues as the backbone. Data from chemical analyses indicated that all LPS commonly contained galactose, glucosamine, glucose, and fucose (except one rough strain) as probable polysaccharide components, together with typical components of inner core and lipid A. We were not able to distinguish between the differences of antigenicity in humans by on the basis of the chemical composition of the LPS.

The inhibitory action of butyrate on lipopolysaccharide-induced nitric oxide production in RAW 264.7 murine macrophage cells

The effect of butyrate, a natural bacterial product of colonic bacterial flora, on lipopolysaccharide (LPS)-induced nitric oxide (NO) production in RAW 264.7 murine macrophage cells was studied. Butyrate significantly reduced NO production in LPS-stimulated RAW cells. The inhibition was abolished by the removal of butyrate. Butyrate also inhibited the expression of inducible type NO synthase (iNOS) in LPS-stimulated RAW cells. Furthermore, butyrate prevented the activation of nuclear factor (NF)-kappaB through the stabilization of IkappaB-alpha and IkappaB-beta. Butyrate did not affect the phosphorylation of mitogen-activated protein (MAP) kinases by LPS. It was, therefore, suggested that butyrate down-regulated LPS-induced NO production in RAW cells through preventing the expression of iNOS, and that it was due to the inhibitory action of butyrate on the activation of NF-kappaB.

Primary cultures of human endothelial cells are susceptible to low doses of Shiga toxins and undergo apoptosis

Various endothelial cells, with the exception of those from human microvasculatures, have been known to resist Shiga toxins (Stxs) in vitro. However, freshly prepared primary cultures of human endothelial cells from the umbilical vein and artery and the saphenous vein were shown to be killed by a very low dose of Stxs. This cytotoxicity of Stxs involves apoptosis, which seems to be caused by a mechanism distinct from the well-known action of Stxs to inhibit protein synthesis, since the blockade of protein synthesis by cycloheximide could not induce apoptosis or enhance the effect of Stxs. Passaged human endothelial cells have been found to be highly resistant to Stxs, which is consistent with previous reports, and not to show any evidence of apoptosis even when they are killed by a high dose of Stxs.

Distribution of JC virus DNA in peripheral blood lymphocytes of hematological disease cases

OBJECTIVE

The distribution of JC virus DNA in peripheral blood was surveyed by the polymerase chain reaction using the late genes as markers.

RESULTS

Six out of 52 cases of hematological diseases and one systemic lupus erythematosus case out of 17 cases were positive for JCV DNA. After separation into B and T lymphocytes by a cell sorter, JCV DNA was found in both cell types prepared from adult T cell leukemia and PML patients.

CONCLUSION

Only 1 or 2 copies of JCV genome were calculated to exist in a cell based on the time course analysis of PCR. Only B lymphocytes and glial brain cells are known to produce nuclear factors which support the growth of the virus. The result that B lymphocytes contained a copy number of JCV genome similar to T lymphocytes suggests that there is some barrier to viral growth in susceptible B lymphocytes, and that the growth of JCV is different from that of other virulent viruses.

Molecular phylogeny of labyrinthulids and thraustochytrids based on the sequencing of 18S ribosomal RNA gene

Labyrinthulids and thraustochytrids are unicellular heterotrophs, formerly considered as fungi, but presently are recognized as members in the stramenopiles of the kingdom Protista sensu lato. We determined the 18S ribosomal RNA gene sequences of 14 strains from different species of the six genera and analyzed the molecular phylogenetic relationships. The results conflict with the current classification based on morphology, at the genus and species levels. These organisms are separated, based on signature sequences and unique inserted sequences, into two major groups, which were named the labyrinthulid phylogenetic group and the thraustochytrid phylogenetic group. Although these groupings are in disagreement with many conventional taxonomic characters, they correlated better with the sugar composition of the cell wall. Thus, the currently used taxonomic criteria need serious reconsideration.

Soluble E-selectin as a marker of disease activity in pustulosis palmaris et plantaris

In this study, we investigated a possible correlation between adhesion molecules and activity of pustulosis palmaris et plantaris (PPP). Serum levels of soluble E-selectin (sE-selectin), soluble intercellular adhesion molecules 1 (sICAM-1) and tumour necrosis factor alpha (TNF-alpha) in 30 untreated PPP patients were examined, and compared with those in 20 healthy subjects. Values in 10 PPP patients were re-examined after treatment. Serum levels of sE-selectin and TNF-alpha in untreated PPP patients were significantly higher than those in healthy subjects. There was a statistically significant correlation between the disease activity and serum levels of sE-selectin in untreated PPP patients. Furthermore, disease activity of PPP was higher in patients who smoked and during the summer, with elevation of serum sE-selectin levels. Serum levels of sE-selectin were downregulated with the recovery from PPP. These results suggest that sE-selectin may play a role in the pathogenesis of PPP and could be a reliable marker of its disease activity.

Production of murine collagen-induced arthritis using Klebsiella pneumoniae O3 lipopolysaccharide as a potent immunological adjuvant

Collagen-induced arthritis (CIA) was produced in mice with non H-2q and H-2r haplotypes by repeated immunization of porcine type-II collagen (CII) together with Klebsiella O3 lipopolysaccharide (KO3 LPS) as an immunological adjuvant. Histological changes that appeared in joints of repeatedly immunized mice were characterized by destruction of normal joint structure, synovial hyperplasia with proliferation of synovial cells, and infiltration of inflammatory cells. No such lesions were produced in mice receiving repeated injections of CII alone or KO3 LPS alone. Development of the humoral antibody and the delayed-type hypersensitivity to CII was exclusively found in mice immunized with the mixture of CII and KO3 LPS. It was therefore suggested that arthritis lesions induced by repeated immunization with the mixture of CII and KO3 LPS might be caused by an autoimmune mechanism, and that the experimental model might be useful for characterization of human rheumatoid arthritis (RA).

Complement-dependent accumulation and degradation of platelets in the lung and liver induced by injection of lipopolysaccharides

We found unique behaviors among platelets within a few minutes of the intravenous injection of lipopolysaccharide (LPS) into mice. Platelets accumulated primarily in the liver at lower doses of LPS, but at higher doses they accumulated largely in the lungs. When the platelets accumulated in these organs were degraded, there was a rapid anaphylactoid shock. The platelet response depended on the strain of mouse and on the source of LPS. Of various LPSs tested, the LPS from the smooth type of Klebsiella O3 (KO3-S LPS) was the most potent at inducing the platelet response and shock. K-76 monocarboxylic acid, an inhibitor of complement C5, effectively prevented the KO3-S LPS-induced degradation (but not accumulation) of platelets and the ensuing rapid shock in BALB/c mice. Moreover, in DBA/2 mice (which are deficient in complement C5), platelets accumulated in the lungs and liver in response to KO3-S LPS but soon returned to the circulation without degradation, and there was no rapid shock. The LPS from the rough type of KO3 induced an accumulation of platelets in the liver and lungs but not a degradation of platelets. On the basis of these results and those reported by other investigators, we propose that in the platelet response to LPS, the lectin pathway to form C3 convertase from C4 and C2 is involved in the rapid accumulation of platelets in the liver and lungs and that the pathway from C5 to C9 is involved in the destruction of platelets and the consequent anaphylactoid shock.

Production of tissue factor in CD14-expressing human umbilical vein endothelial cells by lipopolysaccharide

Production of tissue factor (TF) in response to lipopolysaccharide (LPS) was examined in human umbilical vein endothelial cells (HUVECs) transfected with human CD14 DNA. The expression of CD14 on HUVECs dramatically enhanced the production of TF at a low concentration of LPS in the absence of fetal calf serum (FCS). On the other hand, mock-transfected HUVECs did not respond to even a high concentration of LPS. TF production in CD14-expressing HUVECs was significantly inhibited by anti-CD14 monoclonal antibody. Addition of FCS to the culture of CD14-expressing HUVECs markedly augmented the LPS-induced TF production, whereas only a marginal effect was observed in mock-transfected HUVECs. The findings suggested that the integration of membrane CD14 rendered HUVECs highly sensitive to LPS in the production of TF irrespective of the presence of FCS.

Production of tissue factor in CD14-expressing human umbilical vein endothelial cells by lipopolysaccharide

Production of tissue factor (TF) in response to lipopolysaccharide (LPS) was examined in human umbilical vein endothelial cells (HUVECs) transfected with human CD14 DNA. The expression of CD14 on HUVECs dramatically enhanced the production of TF at a low concentration of LPS in the absence of fetal calf serum (FCS). On the other hand, mock-transfected HUVECs did not respond to even a high concentration of LPS. TF production in CD14-expressing HUVECs was significantly inhibited by anti-CD14 monoclonal antibody. Addition of FCS to the culture of CD14-expressing HUVECs markedly augmented the LPS-induced TF production, whereas only a marginal effect was observed in mock-transfected HUVECs. The findings suggested that the integration of membrane CD14 rendered HUVECs highly sensitive to LPS in the production of TF irrespective of the presence of FCS.

Expression of Fas and Fas ligand on mouse renal tubular epithelial cells in the generalized shwartzman reaction and its relationship to apoptosis

Previously we reported that the consecutive injection of lipopolysaccharide (LPS) into LPS-sensitized mice for the generalized Shwartzman reaction (GSR) appeared to induce the injury of renal tubular epithelial cells via apoptosis. The aim of this study was to characterize the mechanism of renal tubular epithelial cell injury in GSR. The expression of Fas and Fas ligand was immunohistochemically detected on renal tubular epithelial cells from GSR-induced mice, although neither Fas nor Fas ligand was found in cells from untreated control mice or in cells from mice receiving a single injection of LPS. GSR-induced renal tubular epithelial cell injury was produced in neither Fas-negative MRL-lpr/lpr mice nor Fas ligand-negative MRL-gld/gld mice. The administration of anti-gamma interferon antibody together with a preparative injection of LPS prevented the expression of Fas and Fas ligand and the apoptosis of renal tubular epithelial cells. A provocative injection of tumor necrosis factor alpha into LPS-sensitized mice augmented Fas and Fas ligand expression and the apoptosis of renal tubular epithelial cells. The administration of tumor necrosis factor alpha to interleukin-12-sensitized mice resulted in Fas and Fas ligand expression and the apoptosis. Sensitization with interleukin-12 together with anti-gamma interferon antibody did not cause the apoptosis of renal tubular epithelial cells. It was suggested that the Fas/Fas ligand system probably plays a critical role in the development of renal tubular epithelial cell injury through apoptotic cell death.

Mechanism of DNA gyrase-mediated illegitimate recombination: characterization of Escherichia coli gyrA mutations that confer hyper-recombination phenotype

To study the mechanism of DNA gyrase-mediated illegitimate recombination in Escherichia coli, we isolated temperature-sensitive gyrA mutants that confer spontaneous illegitimate recombination and spontaneous induction of lambda prophage at higher frequencies than that in the wild-type. After reconstruction of single mutations by targeted mutagenesis, we confirmed that two single mutations, gyrAL492P and gyrAL488P, and a double mutation, gyrAI203V+gyrAI205V, show the same properties as those described above. With respect to the phenotypes of hyper-recombination and higher induction of lambda prophage, these mutations were dominant over the wild-type. Analysis of recombination junctions of lambdabio transducing phages formed spontaneously in these mutants showed that the parental E. coli bio and lambda recombination sites have a homologous sequence of only 0. 7 base-pair on average, indicating that homology is not required for this illegitimate recombination. Analysis of nucleotide sequences of mutant gyrA genes revealed that the gyrAL492P and gyrAL488P mutations contain amino acid substitutions of Leu492-->Pro and Leu488-->Pro, respectively, which correspond to the alpha18 helix in the breakage-reunion domain of DNA gyrase A subunit. The gyrAI203V and gyrAI205V mutations contain Ile203-->Val and Ile205-->Val, respectively, which correspond to the alpha10' helix, also in the breakage-reunion domain of DNA gyrase A subunit. Biochemical analysis indicated that the GyrA63 protein that contains the L492P mutation has an apparently normal supercoiling activity, but it also produces a small amount of linear DNA in the absence of DNA gyrase inhibitor during the supercoiling reaction, suggesting that the mutant DNA gyrase may have a defect at the step of religation or a defect in the subunit interaction. These results suggest that the recombination is induced by defects of religation and/or dimer formation in the mutant DNA gyrases, implying that two alpha helices, alpha10' and alpha18, of DNA gyrase A subunit have crucial roles in subunit interaction and/or resealing of DNA.

Activation of the transcription factor ISGF3 by interferon-gamma

The interferon-stimulated gene factor 3 (ISGF3) transcription factor has been extensively studied in the context of the type I interferon (IFN-alpha/beta)-mediated antiviral response; it consists of the major DNA-binding component p48, and the signal transducers and activators of transcription (Stat)1 and Stat2. We show here that type II IFN (IFN-gamma) can also invoke the activation of ISGF3 in mouse primary embryonic fibroblasts. In fact, the two Stat proteins were tyrosine phosphorylated in IFN-gamma stimulated cells. Our present findings reveal an additional mechanism by which these two distinct types of cytokines, IFN-alpha/beta and -gamma, can commonly elicit antiviral activities.

Loss of transcription factor IRF-1 affects tumor susceptibility in mice carrying the Ha-ras transgene or nullizygosity for p53

The transcription factor IRF-1 has been implicated in tumor suppression: IRF-1 suppresses cell transformation and mediates apoptosis in vitro. Here we show that the loss of IRF-1 alleles per se has no effect on spontaneous tumor development in the mouse but dramatically exacerbates previous tumor predispositions caused by the c-Ha-ras transgene or by nullizygosity for p53. Grossly altered tumor spectrum, as compared to p53-null mice, was also observed in mice lacking both IRF-1 and p53, and cells from these mice show significantly higher mutation rate. Our results suggest that IRF-1 is a new member of the tumor susceptibility genes.

Experimental murine model for autoimmune enterocolitis using Klebsiella pneumoniae O3 lipopolysaccharide as a potent immunological adjuvant

An experimental model for autoimmune enterocolitis was produced in mice by repeated immunization of homologous colon extract together with Klebsiella 03 lipopolysaccharide (KO3 LPS) as an immunological adjuvant. Histological changes in the intestinal lesions were characterized by infiltration with polymorphonuclear leukocytes in the lamina propria, muscularis mucosae and submucosa of repeatedly immunized mice. No such intestinal lesions were produced in mice receiving injections of colon extract alone or KO3 LPS alone. Development of the autoantibody and delayed-type hypersensitivity against colon extract were found in mice immunized with the mixture of colon extract and KO3 LPS. Distinct positive staining was detected specifically on the columnar epithelium of villi. Sera from hyperimmunized mice defined organ-specific antigens present in the intestine. Therefore, it was suggested that the intestinal lesions might be caused by an autoimmune mechanism.

Role of nitric oxide in lipopolysaccharide-induced hepatic injury in D-galactosamine-sensitized mice as an experimental endotoxic shock model

The role of nitric oxide (NO) in lipopolysaccharide (LPS)-induced hepatic injury was studied in D-galactosamine (D-GalN)-sensitized mice. The inducible isoform of NO synthase (iNOS) was immunohistochemically detected on hepatocytes around blood vessels in livers of mice injected with D-GalN and LPS not on hepatocytes in mice injected with D-GalN or LPS alone, although mRNA for iNOS was found in those mice. Nitrotyrosine (NT) was also found in livers of mice injected with D-GalN and LPS. The localization of NT was consistent with that of iNOS, and the time courses of NT and iNOS expression were almost the same. Expression of iNOS and NT was detected exclusively in the hepatic lesions of mice injected with D-GalN and LPS. Anti-tumor necrosis factor alpha neutralizing antibody inhibited iNOS and NT expression and hepatic injury. The results suggested that NO from iNOS may play a role in LPS-induced hepatic injury on D-GalN-sensitized mice as an experimental endotoxic shock model.

Functional dissection of the cytoplasmic subregions of the IL-2 receptor betac chain in primary lymphocyte populations

The interleukin 2 (IL-2) receptor betac chain (IL-2Rbetac) is known to regulate the development and function of distinct lymphocyte populations. Thus far, the functions of the IL-2Rbetac cytoplasmic subregions have been studied extensively by using cultured cell lines; however, this approach has limitations with respect to their functions in distinct primary lymphocyte populations. In the present study, we generated mice each expressing a mutant form of an IL-2Rbetac transgene, lacking the cytoplasmic A- or H-region, on an IL-2Rbetac null background. We show that lack of the H-region, which mediates activation of the Stat5/Stat3 transcription factors, selectively affects the development of natural killer cells and T cells bearing the gamma delta T cell receptor. This region is also required for the IL-2-induced proliferation of T cells in vitro, by upregulating IL-2Ralpha expression. In contrast, the A-region, which mediates activation of the Src family protein tyrosine kinase (PTK) members, contributes to downregulation of the T cell proliferation function. The IL-2Rbetac null mutant mice develop severe autoimmune symptoms; these are all suppressed following the expression of either of the mutants, suggesting that neither the Stats nor the Src PTK members are required. Thus, our present approach offers new insights into the functions of these cytoplasmic subregions of the IL-2Rbetac chain.

Role of CD86 (B7-2) in triggering of antigen-specific IgE antibody response by lipopolysaccharide

The role of CD86 in triggering of ascaris extract-specific IgE antibody response by lipopolysaccharide was studied. The simultaneous administration of anti-CD86 antibody with ascaris extract and lipopolysaccharide prevented the production of IgE antibody response to ascaris extract. CD86+ cells were detected in peritoneal cavities and spleens of mice injected intraperitoneally with lipopolysaccharide. CD86+ cells appeared in peritoneal cavities and spleens eight hours after lipopolysaccharide injection, and they were detectable for a week. CD86+ cells in peritoneal cavities and spleens were mainly surface Ig-positive B-cells and some Ig-negative cells. It was suggested that lipopolysaccharide induced the expression of CD86 mainly on B-cells, and that CD86+ cells induced by lipopolysaccharide injection might play an important role as antigen-presenting cells on triggering of ascaris extract-specific IgE antibody response by lipopolysaccharide.

Role of CD86 (B7-2) in triggering of antigen-specific IgE antibody response by lipopolysaccharide

The role of CD86 in triggering of ascaris extract-specific IgE antibody response by lipopolysaccharide was studied. The simultaneous administration of anti-CD86 antibody with ascaris extract and lipopolysaccharide prevented the production of IgE antibody response to ascaris extract. CD86+ cells were detected in peritoneal cavities and spleens of mice injected intraperitoneally with lipopolysaccharide. CD86+ cells appeared in peritoneal cavities and spleens eight hours after lipopolysaccharide injection, and they were detectable for a week. CD86+ cells in peritoneal cavities and spleens were mainly surface Ig-positive B-cells and some Ig-negative cells. It was suggested that lipopolysaccharide induced the expression of CD86 mainly on B-cells, and that CD86+ cells induced by lipopolysaccharide injection might play an important role as antigen-presenting cells on triggering of ascaris extract-specific IgE antibody response by lipopolysaccharide.

Human antibody response to Helicobacter pylori lipopolysaccharide: presence of an immunodominant epitope in the polysaccharide chain of lipopolysaccharide

We have examined the antibody response to Helicobacter pylori lipopolysaccharides (LPS) in humans. We used sera from patients with gastroduodenal diseases and healthy adults infected or not infected with H. pylori. Data from the experiments for antibody binding to LPS suggested that the polysaccharide chains from many H. pylori strains showed high immunogenicity in humans. Sera from most (above 70%) H. pylori-infected individuals contained immunoglobulin G (IgG) antibodies against the polysaccharide region highly immunogenic H. pylori LPS. The IgG titers of individual serum samples that reacted strongly with highly immunogenic LPS were quite similar (r2 = 0.84 to 0.98). The results suggest wide distribution among H. pylori strains of a highly antigenic epitope in the polysaccharide moieties of their LPS. Also, the similarity in the titers of individual serum samples against highly immunogenic LPS points to the existence of epitopes sharing a common structural motif. However, some strains showed low antigenicity, even those with polysaccharide-carrying LPS. The dominant subclass of IgG that reacted with the highly immunogenic LPS was IgG2, which was preferentially raised against polysaccharide antigens. Recently, a structure that mimics that of the Lewis antigens was identified in the O-polysaccharide fraction of H. pylori LPS; however, no correlation between antigenicity of the polysaccharide chain in humans and the presence of Lewis antigens was found. The IgA and IgM titers against H. pylori LPS seemed to be mostly nonspecific and directed against lipid A. In a few cases, however, sera from individuals infected with H. pylori gave strong IgA and IgM titers against the highly immunogenic polysaccharide. In conclusion, the LPS of many H. pylori strains possess an antigenic epitope in their polysaccharide regions that is immunogenic in humans. However, our results show that the antigenic epitope is unlikely to be immunologically related to structures mimicking Lewis antigens.

Biological characterization of endotoxins released from antibiotic-treated Pseudomonas aeruginosa and Escherichia coli

The supernatants taken from Pseudomonas aeruginosa and Escherichia coli cultures in human sera or chemically defined M9 medium in the presence of ceftazidime (CAZ) contained high levels of endotoxin, while those taken from the same cultures in the presence of imipenem (IPM) yielded a very low level of endotoxin. The biological activities of endotoxin in the supernatants were compared with those of phenol water-extracted lipopolysaccharide (LPS). The endotoxin released from the organisms as a result of CAZ treatment (CAZ-released endotoxin) contained a large amount of protein. The protein, however, lacked endotoxic activity, since the endotoxin did not show any in vivo toxic effects in LPS-hyporesponsive C3H/HeJ mice sensitized with D-(+)-galactosamine (GalN) or any activation of C3H/HeJ mouse macrophages in vitro. The activities of CAZ- and IPM-released endotoxin (as assessed by a chromogenic Limulus test) were fundamentally the same as those of P. aeruginosa LPS, since their regression lines were parallel. The CAZ-released endotoxin was similar to purified LPS with respect to the following biological activities in LPS-responsive C3H/HeN mice and LPS-hyporesponsive C3H/HeJ mice: lethal toxicity in GalN-sensitized mice, in vitro induction of tumor necrosis factor- and NO production by macrophages, and mitogen-activated protein kinase activation in macrophages. The macrophage activation by CAZ-released endotoxin as well as LPS was mainly dependent on the presence of serum factor and CD14 antigen. Polymyxin B blocked the activity. These findings indicate that the endotoxic activity of CAZ-released endotoxin is due primarily to LPS (lipid A).

Protective effects of a human 18-kilodalton cationic antimicrobial protein (CAP18)-derived peptide against murine endotoxemia

CAP18 (an 18-kDa cationic antimicrobial protein) is a granulocyte-derived protein that can bind lipopolysaccharide (LPS) and inhibit various activities of LPS in vitro. The present study examined the protective effect of a synthetic 27-amino-acid peptide (CAP18(109-135)) from the LPS-binding domain of CAP18 against antibiotic-induced endotoxin shock, using highly LPS-sensitive D-(+)-galactosamine (D-GalN)-sensitized C3H/HeN mice. The antibiotic-induced endotoxin (CAZ-endotoxin) was prepared from the culture filtrate of Pseudomonas aeruginosa PAO1 exposed to ceftazidime (CAZ). Injection of CAP18(109-135) protected the mice injected with LPS or CAZ-endotoxin from death and lowered their tumor necrosis factor (TNF) levels in serum in a dose-dependent manner. Treatment with CAZ caused death of the D-GalN-sensitized P. aeruginosa PAO-infected mice within 48 h, while injection with CAP18(109-135) rescued the mice from death. In the mice rescued from death by injection with CAP18(109-135), endotoxin levels in plasma and TNF production by liver tissues were decreased but the numbers of viable infecting bacteria in their blood were not decreased significantly and remained at the levels in CAZ-treated mice. These results indicate that CAP18(109-135) is capable of preventing antibiotic-induced endotoxic shock in mice with septicemia and that the effect is due to its LPS-neutralizing activity rather than to its antibacterial activity.

Generation of Escherichia coli O9a serotype, a subtype of E. coli O9, by transfer of the wb* gene cluster of Klebsiella O3 into E. coli via recombination

Genetic characterization of the wb* gene in a series of Escherichia coli and Klebsiella strains possessing the mannose homopolymer as the O-specific polysaccharide was carried out. The partial nucleotide sequences and PCR-restriction fragment length polymorphism analysis suggested that E. coli serotype O9a, a subtype of E. coli O9, might have been generated by the insertion of the Klebsiella O3 wb* gene into a certain E. coli strain.