Protection of mice against bacterial infection by oral administration of bacterial lipopolysaccharide

The effect of orally administered bacterial lipopolysaccharide (LPS) on host resistance against bacterial infections was studied. LPS orally given for 5 consecutive days prior to infection caused no apparent toxic effect and protected mice against Pseudomonas aeruginosa and Listeria monocytogenes infections.     

Augmentation of resistance of mice to bacterial infection by a polysaccharide-peptidoglycan complex (PSPG) extracted fromLactobacillus casei

A water-soluble polysaccharide-peptidoglycan complex (PSPG) was prepared from heat-killedLactobacillus casei by digesting the bacteria with N-acetylmuramidase. The molecular weight of PSPG was over 30,000, and the polysaccharide portion of PSPG, its main component was composed of rhamnose, glucose, galactose, glucosamine and galactosamine. Mice pretreated intraperitoneally with PSPG survived after a lethal infection withListeria monocytogenes orPseudomonas aeruginosa. The growth of infecting bacteria (L. monocytogenes, P. aeruginosa, Salmonella typhimurium, Escherichia coli) in both the peritoneal cavity and the liver was inhibited markedly in the mice that had been treated with PSPG. It was suggested that macrophages may be the main effector for the anti-infectious effect of PSPG since treatment of mice with carrageenan, a selective macrophage blocker, markedly reduced the anti-infectious effect of PSPG.     

Augmentation of protective immune responses against viral infection by oral administration of schizophyllan

An oral administration of fungal polysaccharide schizophyllan has augmented protective immune responses to Sendai virus infection in mice and the rodshaped DNA virus of Penaeus japonicus (RV-PJ) infection in Kuruma shrimps. When schizophyllan was administered orally at a dose of 50 or 100 mg/kg body weight per day, the survival rates after virus challenge were significantly higher than those of the control groups. High phagocytic activities were observed in the haemocytes of the schizophyllan-fed shrimps.These results suggest that schizophyllan confers effective protection against viral infection by increasing antiviral immune responses, and that it could be used to boost immunity to virus infection in animals or in invertebrates.     

Augmentation of host resistance to Candida albicans infection in ascites tumor-bearing mice.

We found that the number of peripheral blood polymorphonuclear leukocytes (PMN) dramatically increased in both sarcoma 180 (S-180) and MM-46 mammary carcinoma (MM-46) ascites tumor-bearing mice, and mice required a remarkable resistance to Candida albicans infection via intravenous route. When the resistance was determined by number of cells of C. albicans in the kidney, a significant decrease in the number of fungal cells was observed in the kidneys of infected ascites tumor-bearing mice. An increase of active oxygen levels of PMN from ascites tumor-bearing mice was observed, suggesting that this factor is important in developing of resistance in ascites tumor-bearing mice. Additionally, a culture supernatant of tumor cells co-cultivated with bone-marrow cells in vitro increased the number of granulocytes and macrophages differentiated from the bone-marrow cells.     

Insect peptides with improved protease-resistance protect mice against bacterial infection

At a time of the emergence of drug-resistant bacterial strains, the development of antimicrobial compounds with novel mechanisms of action is of considerable interest. Perhaps the most promising among these is a family of antibacterial peptides originally isolated from insects. These were shown to act in a stereospecific manner on an as-yet unidentified target bacterial protein. One of these peptides, drosocin, is inactive in vivo due to the rapid decomposition in mammalian sera. However, another family member, pyrrhocoricin, is significantly more stable, has increased in vitro efficacy against gram-negative bacterial strains, and if administered alone, as we show here, is devoid of in vitro or in vivo toxicity. At low doses, pyrrhocoricin protected mice against Escherichia coli infection, but at a higher dose augmented the infection of compromised animals. Analogs of pyrrhocoricin were, therefore, synthesized to further improve protease resistance and reduce toxicity. A linear derivative containing unnatural amino acids at both termini showed high potency and lack of toxicity in vivo and an expanded cyclic analog displayed broad activity spectrum in vitro. The bioactive conformation of native pyrrhocoricin was determined by nuclear magnetic resonance spectroscopy, and similar to drosocin, reverse turns were identified as pharmacologically important elements at the termini, bridged by an extended peptide domain. Knowledge of the primary and secondary structural requirements for in vivo activity of these peptides allows the design of novel antibacterial drug leads.     

Arabidopsis histidine kinase 5 regulates salt sensitivity and resistance against bacterial and fungal infection

? The ability of plants to adapt to multiple stresses imposed by the natural environment requires cross-talk and fine-tuning of stress signalling pathways. The hybrid histidine kinase Arabidopsis histidine kinase 5 (AHK5) is known to mediate stomatal responses to exogenous and endogenous signals in Arabidopsis thaliana. The purpose of this study was to determine whether the function of AHK5 in stress signalling extends beyond stomatal responses. ? Plant growth responses to abiotic stresses, tissue susceptibility to bacterial and fungal pathogens, and hormone production and metabolism of reactive oxygen species were monitored in a T-DNA insertion mutant of AHK5. ? The findings of this study indicate that AHK5 positively regulates salt sensitivity and contributes to resistance to the bacterium Pseudomonas syringae pv. tomato DC3000 and the fungal pathogen Botrytis cinerea. ? This is the first report of a role for AHK5 in the regulation of survival following challenge by a hemi-biotrophic bacterium and a necrotrophic fungus, as well as in the growth response to salt stress. The function of AHK5 in regulating the production of hormones and redox homeostasis is discussed.     

Intranasal administration of a detoxified endotoxin vaccine protects mice against heterologous Gram-negative bacterial pneumonia

When given passively or elicited actively, antibodies induced by a detoxified Escherichia coli J5 mutant lipopolysaccharide (J5dLPS)-group B meningococcal outer membrane protein (-OMP) vaccine previously protected animals from lethal sepsis. To assess the use of this vaccine for the treatment of Gram-negative bacillary pneumonia, we vaccinated mice, with or without the adjuvant CpG, by intranasal (i.n.) or intraperitoneal (i.p.) routes of administration. Local and systemic IgG levels were 2-3 logs higher following i.p. immunization compared to i.n. However, i.n. immunization elicited both local and systemic IgA, unlike i.p. administration. The addition of CpG to the vaccine, by either route of administration, elicited greater levels of antibody. Intranasal immunization protected mice against lethal heterologous Gram-negative bacillary pneumonia and post-immunization serum and broncho-alveolar lavage fluid mediated enhanced bacterial killing with peritoneal and alveolar macrophages in vitro. We conclude that further studies on the use of J5dLPS-OMP for the prevention of nosocomial pneumonia are warranted.     

Structural-functional changes in the peripheral nerves after administration of several drugs]

Structural and functional changes in the sciatic nerve induced by some drugs were studied using morphological and electrophysiological methods. It was stated that the application of this drug on the nerve causes different degenerating changes. Electrophysiological data, using the regeneration of action potential, proved the presence of structural changes in the nerve after application of mentioned drugs and showed partly preserved conduction of the nerve trunks.     

Regulation of granulopoiesis and distribution of granulocytes in early phase of bacterial infection

Studies have been carried out to determine the effect of bacterial infection on CSF production, CFU-C activation, and bacterial clearance by mature granulocytes in mice infected with Escherichia coli. These studies have shown that immediately after bacterial infection (5 minutes), serum colony-stimulating factor (CSF) levels and bone marrow colony-forming units in culture (CFU-C) levels are elevated. This is followed by oscillator rises in both of these parameters and the appearance of granulocytes in the infected site. With clearance of bacteria, CSF and CFU-C levels return to normal. These studies have indicated further that bacterial infection is a major stimulus for granulocyte production through the CSF-CFU-C system and that clearance of bacteria by mature granulocytes may serve as a negative feedback regulatory arm.     

细菌素的抗细菌耐药研究及应用现状

随着青霉素等抗生素的问世,人类因细菌感染所致疾病的死亡率大为降低;但在抗生素广泛应用至今,我们又面临着细菌耐药日趋严重、耐药菌感染难以控制、新抗生素研发脚步迟滞的严峻局势。如何应对这一全球性的难题,研究者们殚精竭虑,力求在抗生素以外寻求新的突破,有着比抗生素更悠久历史、同样具有抗菌活性的细菌素引起了研究者们的重视。但抗菌谱、产量等问题使细菌素的应用受到了限制,打破瓶颈成了当下研究的热点。本文主要对细菌素的研究现状、应用及异源表达做了相关综述。     

Augmentation of delayed-type hypersensitivity and resistance against allogeneic or syngeneic methylcholanthrene-induced tumors in mice preimmunized with the tumor extracts

Delayed-type hypersensitivity (DTH) responses against methylcholanthrene-induced fibrosarcomas in C3H/He and BDF1 mice were developed in BDF1 mice by sc injection of the respective mitomycin C-treated tumor cells. The DTH responses to the allogeneic and the syngeneic tumor cells were accelerated and enhanced tumor-specifically by priming 7 days previously with KCl extracts of the respective tumors. The ability in the mice primed with the tumor extracts enhancing the DTH response against the tumor cells could be transferred to recipient mice by the spleen cells, but not by the T-cell-depleted spleen cells. Rejection of allogeneic tumor was accelerated under the development of accelerated and enhanced DTH response against the allogeneic tumor antigens. Moreover, resistance to syngeneic tumor growth increased significantly with the development of accelerated and enhanced DTH response against the syngeneic tumor antigens. Thus, the augmentation of DTH response by preimmunization with tumor extracts was accompanied by the increased resistance to tumor growth, suggesting that T cells involved in the augmentation of tumor-specific DTH response play some role in increasing the resistance to tumor growth.     

Host resistance against Candida alibcans infection in mice with adjuvant induced arthritis

In mice and humans two distinct CD4+ helper T cells, known as Th1 and Th2 are identified. They are characterized by the different cytokine milleau they induce. The balance between Th1 and Th2 responses is thought to be decisive for the initiation and course of some autoimmune disorders, as well as for the outcome of infectious processes. In the present study the development of Candida alibcans infection in mice with adjuvant-induced arthritis was investigated. An impaired host resistance against C. alibcans in arthritic mice was registered when the inoculation was done during the early and the established phases of arthritis. In contrast, the slight elevation of the number of survivors was detected when the infection was induced at the peak of inflammation. These data correlated with the changes of serum TNF-α level and delayed type hypersensitivity (DTH) toC. alibcans. This revised version was published online in June 2006 with corrections to the Cover Date.     

Oral administration of lactobacilli from human intestinal tract protects mice against influenza virus infection

Aims: Our study was conducted to evaluate the potent protective effects of oral administration of probiotic Lactobacillus strains against influenza virus (Flu) infection in a mouse model. Method and Results: Lyophilized Lactobacillus rhamnosus GG (LGG) and Lactobacillus gasseri TMC0356 (TMC0356) were orally administered to BALB/c mice for 19 days. The test mice were intranasally infected with Flu A/PR/8/34 (H1N1) on day 14, and any changes in clinical symptoms were monitored. After 6 days of infection, the mice were killed and pulmonary virus titres were determined. The clinical symptom scores of mice administered oral LGG and TMC0356 were significantly ameliorated, compared to those of the control mice (P < 0·01). The pulmonary virus titres of the mice fed LGG and TMC0356 were also significantly decreased compared to those of control mice (P < 0·05). Conclusions: These results indicate that oral administration of lactobacilli, such as LGG and TMC0356, might protect a host animal against Flu infection. Significance and Impact of the Study: These results demonstrate that oral administration of selected lactobacilli might protect host animals from Flu infection by interactions with gut immunity.     

Apoptotic features of peripheral blood granulocytes and monocytes during primary, acute HIV infection

Apoptosis plays a major role during HIV infection, including the primary, acute HIV syndrome (AHS), during which such phenomenon is massive. We asked whether apoptosis involved not only peripheral blood lymphocytes, but also monocytes (PBM) and granulocytes (PBG). Thus, we studied cells from different patients during the acute phase of the viral syndrome. The CD95 molecule was expressed at high density on the PBM and PBG surface during AHS. Culturing PBG for a few hours resulted in a significant membrane expression of phosphatidylserine, consistent with apoptosis. However, cells maintained for hours plasma membrane integrity and showed no relevant changes in mitochondrial membrane potential. The overexpression of CD95 was not associated with high plasmatic levels of sCD95 and, together with apoptosis and its related markers decreased after a few weeks of highly active antiretroviral therapy. During AHS, a deregulation of the CD95 system occurs in monocytes and granulocytes, is related to a high propensity of PBG to undergo apoptosis, and may contribute to the pathogenesis of the disease. Antiretroviral treatment resulted not only in a decrease of virus production, but also in a reduced PBG tendency to undergo spontaneous apoptosis. Even if the mechanism(s) responsible for this phenomenon remains to be elucidated, our data suggest a possible (indirect?) action of antiretroviral therapies on PBG and PBM which could explain, at least partially, the rescue of natural immunity and the reduced use of granulocyte-colony stimulating factor during such treatments.     

Augmentation of delayed-type hypersensitivity by vesicular stomatitis virus infection in mice

Effects of the infection with vesicular stomatitis virus (VSV) on delayed-type hypersensitivity (DTH) to heterologous erythrocytes were investigated in mice. Infection at the time of immunization resulted in production of high levels of DTH that were specific to the antigen used for immunization. The high level of DTH produced in VSV-infected mice could not be attributed to the nonspecific enhancement of the footpad swelling with the infection. Augmentation of DTH was observed in all strains of the mouse (CBA, BALB/c, C3H/He, and C57BL/6) used. The augmenting effect of VSV infection was not as apparent in adult thymectomized mice in which the level of VSV-replicating T cells was reduced. These results strongly suggest that DTH-mediating T cells are resistant to infection by VSV, and also that there are VSV-sensitive cells that may be engaged in the suppression of DTH. It seems improbable, however, that the cells sensitive to VSV infection represent the suppressor cells themselves, since the enhancing effect was not observed in mice in which the suppressor cells were induced by the administration of high doses of the antigen.     

Immunohistological characterization of leukocytes in the lungs of healthy mice and after bacterial intratracheal infection

Leukocytes in the peripheral lung parenchyma of mice have not been characterized histologically during bacterial infection. The aim of this study was to investigate (a) the immunohistological characteristics of healthy murine lungs and (b) the cell kinetics during acute inflammation. BALB/c and MF1 mice were examined; as well as transgenic mice with the gene defect of cystic fibrosis (CF) in the airways as an animal model for this disease. MF1 mice served as controls for the transgenic animals. Lavaged and perfused lungs were snap frozen. B and T lymphocytes, CD4+ and CD8+ cells, dendritic cells, neutrophils and a subset of macrophages were enumerated on cryostat lung sections. The lung tissue and bronchoalveolar lavage (BAL) of BALB/c mice, infected intratracheally with Haemophilus influenzae type b (Hib), were studied at different time points after infection. In the lungs of healthy mice, including CF mice, the largest population was that of T cells, CD4+ cells being always more frequent than CD8+ cells. During acute inflammation the number of neutrophils in the lung parenchyma and BAL increased strongly within the first hours after bacterial instillation and reached baseline levels within one week. This study provides a semi-quantitative analysis of immunocompetent cells in normal and infected murine lung tissue. Differences in cell numbers are found between different strains. Moreover, the cellular reaction during Hib infection in mouse lungs is dominated by neutrophils, as expected in a primary immune response. In uninfected CF mice the numbers and distribution of immune cells in the lung tissue are normal, indicating that the cellular defense is adequate.     

Expression of the ginseng PgPR10-1 in Arabidopsis confers resistance against fungal and bacterial infection

Korean ginseng (Panax ginseng C. A. Meyer) consists of nine cultivars from three Jakyung, Chungkyung, and Hwangsook lines. Among three previously identified PR-10 homologs from ginseng (PgPR10-1, PgPR10-2, and PgPR10-3), we found that the exact same sequence of PgPR10-2 exist in all tested nine cultivars. But a deletion and SNP was found in American ginseng (Panax quinquefolius). PR-10 proteins are known to be small and cytosolic, and showed similar three-dimensional structure. Here we show that the heterologous overexpression of PgPR10-1 in Arabidopsis showed enhanced resistance against Pseudomonas syringe, Fusarium oxysporum, and Botrytis cinerea and in-frame tagging with fluorescent protein showed its cytoplasm and nucleus localization. Protein–protein interaction of PgPR10-2 with PgPR10-1, PgPR10-2 and PgPR10-3 suggests that the PgPR10 proteins might form multimeric complexes in different cellular compartments to function in development and in defense-related mechanism. Differential response of PgPR10-1 and PgPR10-2 against different sets of biotic stresses in ginseng plant supports this notion.