p53 and c-myc activation by Pasteurella haemolytica leukotoxin is correlated with bovine mononuclear cells apoptosis

To analyse the role of Pasteurella haemolytica Leukotoxin (LKT) in the mechanism of apoptotic cell death of bovine lymphocytes, we evaluated DNA fragmentation and p53 and c-myc expression. P. haemolytica strain ATCC 14003 was cultivated for LKT production. DNA fragmentation was analysed by electrophoresis on Agarose gel. DNA strand breaks in individual apoptotic cells were also detected by an in situ Terminal deoxy nucleotidyl Transferase (TdT). The Polymerase Chain Reaction (PCR) procedure was used for verified p53 and c-myc activation by P. haemolytica LKT. LKT was able to induce DNA fragmentation in a dose and time-dependent fashion. The greatest apoptotic effect was obtained using LKT at a concentration of 0.25 U. The results show that p53 and c-myc activation by LKT is correlated with apoptosis of bovine lymphocytes and monocytes. Our data suggest that LKT may have an important role in the bacterial virulence of Pasteurella haemolytica.

Role of Pasteurella multocida, Pasteurella haemolytica and Salmonella typhimurium porins on inducible nitric oxide release by murine macrophages

The aim of this study was to verify whether Pasteurella haemolytica, P. multocida and Salmonella typhimurium porins could affect the inducible nitric oxide synthase (iNOS) expression and nitric oxide (NO) release by murine resident peritoneal macrophages in vitro. We also compared their effect with that elicited by P. haemolytica, P. multocida and S. typhimurium lipopolysaccharide (LPS) whose biological activity is well known. Variations in NO release and iNOS mRNA expression due to variable concentrations of porins were recorded and compared. We also investigated the synergism between bacterial products and interferon gamma (IFN-gamma). With this aim cells were incubated with porins together with murine rIFN-gamma prior to assessing the presence of NO in the supernatant and mRNA analysis. Porins in themselves were not able to induce NO release by resident peritoneal macrophages. Incubation of macrophages with IFN-gamma in the presence of porins increased NO release, whereas incubation in the presence of the arginine analog N(G)-monomethyl-L-arginine (NMA) inhibited NO release. The greatest NO release was obtained using porins at a concentration of 5 microg/mL. Porins, together with IFN-gamma, were also able to upregulate the mRNA expression of iNOS. Our findings suggest that gram-negative porins are able to modulate inflammatory and immunological responses by affecting the release of NO and the expression of iNOS gene in activated macrophages.

Effect of transforming growth factor beta on experimental Salmonella typhimurium infection in mice

We have investigated the effect of the in vivo administration of recombinant transforming growth factor beta (rTGF-beta) on the pathogenic mechanisms involved in Salmonella typhimurium experimental infection in mice. The protective response elicited by macrophages was induced by rTGF-beta1 by 2 days after experimental infection, as demonstrated by an increased NO production, while the humoral protective effect began with cytokine mRNA expression 2 days after the challenge and continued after 5 days with cytokine release and lymphocyte activation. We demonstrated that all mice who received rTGF-beta1 survived 7 days after infection. The number of bacteria recovered in the spleens and in the livers of rTGF-beta1-treated mice 2 and 5 days after infection was significantly smaller than that found in the same organs after phosphate-buffered saline (PBS) inoculation. Furthermore, 2 and 5 days after infection, splenic macrophages from rTGF-beta1-treated mice showed a greater NO production than did those from PBS-treated mice. The effect of rTGF-beta1 on S. typhimurium infection in mice was correlated with the expression of cell costimulatory CD28 molecules. Five days after S. typhimurium infection, the percentage of CD28(+)-expressing T cells in splenic lymphocytes from rTGF-beta1-treated mice increased with respect to that from control mice. Gamma interferon (IFN-gamma) mRNA was present in a greater amount in spleen cells from rTGF-beta1-treated mice after 2 days, although the intensity of the band decreased 5 days after the challenge. A similar pattern was obtained with the mRNAs for interleukin-1alpha (IL-1alpha), IL-6, TGF-beta, and inducible nitric oxide synthase, which showed greater expression in cells obtained from rTGF-beta1-treated and S. typhimurium-infected mice 2 days after challenge. The treatment with rTGF-beta1 induced an increase in IL-1alpha and IFN-gamma release in the supernatant of splenocyte cultures 5 days after the experimental infection with S. typhimurium. Moreover, we demonstrated that 5 days after infection, the IFN-gamma titer was significantly greater in the sera of rTGF-beta-treated mice than in those of PBS-treated mice. Also, hsp60 showed greater expression 2 days after the challenge in splenocytes from rTGF-beta1-treated mice. The role played by proinflammatory and immunoregulatory cytokines and by CD28 is discussed.

Role of Pasteurella multocida porin on cytokine expression and release by murine splenocytes

The aim of this study was to verify whether Pasteurella multocida porin can affect the expression and release of IL-1alpha, IL-6, TNF-alpha, IL-4, IFN-gamma, IL-10 and IL-12 by murine splenocytes in vitro. P. multocida porin and lipopolysaccharide (LPS) were able to induce the release of IL-1alpha, IL-6, TNF-alpha, IFN-gamma and IL-12 in a dose-dependent fashion. The greatest release of these cytokines was obtained using P. multocida porin at a concentration of 5 microg ml(-1) and LPS at a concentration of 1 microg ml(-1). The time-courses of release showed that P. multocida LPS was able to stimulate the production of IL-1alpha, IL-6, TNF-alpha, IFN-gamma and IL-12 earlier than porin and at a greater rate. No effect was observed on IL-4 and IL-10 release under the same experimental conditions. P. multocida porin and LPS were also able to up-regulate the mRNA expression of IL-1alpha, IL-6, TNF-alpha, IFN-gamma and IL-12 p40. Our findings suggest that P. multocida porin is able to modulate inflammatory and immunological responses by affecting the release of several cytokines and the expression of their genes.

TNF-alpha expression and herpes simplex infection in human monocytes treated with growth hormone, prolactin and insulin

We evaluated the in vitro effect of growth hormone (GH), prolactin (PRL) and insulin treatment of human monocytes on Herpes simplex virus type 1 (HSV-1) infection. GH and PRL increased cell susceptibility to infection which was related to a slight TNF-alpha expression and release. Insulin had no significant effect. Cells activated with lipopolysaccharide (LPS) and then treated with PRL showed a lower susceptibility to HSV infection related to a significant increase in TNF-alpha expression and release. On the contrary, GH and insulin increased the susceptibility to infection of activated cells but did not modify TNF-alpha expression with respect to cells treated only with hormones.

Th1 and Th2 cell involvement in immune response to Salmonella typhimurium porins

In understanding the regulation of the specific immune response to Salmonella typhimurium, the role of a surface major component (porins) was studied. In this study we demonstrate that purified porins are able to induce a different response to that induced by the porins present on the S. typhimurium cell surface. Porin-treated or orally infected mice show anti-porin antibodies with bactericidal activity. The complete adoptive transfer of resistance to S. typhimurium is achieved only using splenic T cells from survivor mice after experimental infection. After stimulation with specific antigen in vitro CD4+ cells from porin-immunized mice released large amounts of interleukin-4 (IL-4), at a time when CD4+ cells from S. typhimurium-infected mice predominantly secreted interferon-gamma (IFN-gamma). Limiting dilution analysis showed that infection resulted in a higher precursor frequency of IFN-gamma-producing CD4+ T cells and a lower precursor frequency of IL-4-producing CD4+ T cells, while immunization with porins resulted in a higher precursor frequency of IL-4-producing cells and a low frequency of IFN-gamma-producing cells. Analysis of polymerase chain reaction-amplified cDNA from the spleens of infected mice revealed that IFN-gamma, IL-2 and IL-12 p40 mRNA were found 5 days after in vitro challenge and increased after 15 days; IL-10 expression was barely present after both 5 and 15 days, while IL-4 mRNA expression was not detected. In immunized mice, the IL-4 mRNA expression increased after 15 days, IFN-gamma mRNA expression disappeared entirely after 15 days, while IL-2, IL-10 and IL-12 mRNA remained relatively unchanged.

Cytokine and adhesion molecule expression in human monocytes and endothelial cells stimulated with bacterial heat shock proteins

Bacterial heat shock proteins (HSPs) from Escherichia coli (GroES, GroEL, and DNAk) were tested for their ability to induce by themselves the expression and release of interleukin-6 (IL-6), tumor necrosis factor alpha (TNF-alpha), and granulocyte-monocyte colony-stimulating factor (GM-CSF) by human monocytes and GM-CSF, IL-6, E-selectin, intercellular adhesion molecule-1 (ICAM-1), and vascular cell adhesion molecule-1 (VCAM-1) by human umbilical vein endothelial cells (HUVEC). Our study demonstrated that treatment of monocytes with DNAk increased IL-6, TNF-alpha, and GM-CSF release in a dose-dependent manner. The same effect was elicited by GroEL but at a lower rate. Treatment of HUVEC cultures with DNAk and GroEL also increased GM-CSF, IL-6, E-selectin, ICAM-1, and VCAM-1 release in a dose-dependent fashion. In any case, the greatest release was obtained by using DNAk and GroEL at a concentration of 1 microg/ml. DNAk and GroEL were also able to up-regulate the surface expression of E-selectin, ICAM-1, and VCAM-1. As detected by reverse transcription-PCR analysis, DNAk and GroEL also increased the steady-state levels of cytokines and adhesion molecules in human monocytes and endothelial cells. In our study GroES showed a significant activity only on the release, surface expression, and mRNA transcription of E-selectin. Adhesion molecule expression seems to be a direct effect of HSPs and not via cytokines. Furthermore, these effects are due to HSPs properties because they are inhibited by specific monoclonal antibodies. These findings support the potential role of HSPs in modulating cell interactions during immunological and inflammatory responses.

Growth hormone modulates IL-alpha and IFN-gamma release by murine splenocytes activated by LPS or porins of Salmonella typhimurium

The effect of growth hormone (GH) on the release of IL-1alpha and IFN-gamma from murine splenocytes was investigated. Their release from splenocytes activated by Salmonella enterica serovar Typhimurium lipopolysaccharide (LPS) 0.5 microg/ml was increased by c. 65% in the presence of GH 100 pg/ml. With splenocytes activated by S. Typhimurium porins 5 microg/ml, GH increased the production of both IL-1alpha and IFN-gamma by c. 56%. Polymyxin treatment abolished the cytokine-releasing activity of LPS but had no effect on the activity of the porin preparation.

Interleukin-1 and interleukin-6 gene expression in human monocytes stimulated with Salmonella typhimurium porins

The aim of this study was to verify whether Salmonella typhimurium porins can affect the expression of interleukin-1 (IL-1) and interleukin-6 (IL-6) genes. Human monocytes were treated with porins, and total RNAs were analysed by Northern blotting to evaluate the expression of IL-1 alpha, IL-1 beta and IL-6 in both treated and untreated cell cultures. Porins induced a significant increase in IL-1 and IL-6 transcripts. This increase was related to the dose of porins, and it peaked 5 hr after treatment. The same results were obtained when polymyxin B was added to the porin preparation to eliminate eventual traces of lipopolysaccharide (LPS) associated with porins. The porins-mediated increase in interleukin transcripts did not require de novo protein synthesis, and it was because of the enhanced half-life of IL-1 and IL-6 mRNAs, rather an increased rate of gene transcription. These data suggest that porins may affect inflammatory and immunological responses by enhancing the expression of cytokine genes.

Effect of growth hormone, prolactin and insulin on the release of IL-1 alpha, IFN-gamma and IL-4 by staphylococcal enterotoxin A-stimulated splenocytes

The regulation by peptide hormones (Growth Hormone, Prolactin, Insulin) of cytokine secretion by splenocytes stimulated with Staphylococcal Enterotoxin A was studied. Growth hormone increases the release of IFN-gamma from splenocytes stimulated with Enterotoxin A by 50% but considerably decreases IL-1 alpha release by 93%. Prolactin decreases the release of IL-1 alpha by 80%, but has no significant effects on IFN-gamma release. Insulin causes a 50% decrease in IFN-gamma and 95% decrease in IL-1 alpha. IL-4 release was not changed. The results are discussed in terms of the possibility of an interesting function for these endocrine peptides which expands their range of biologic activities within the immune system.

Effect of low-nutrient seawater on morphology, chemical composition, and virulence of Salmonella typhimurium

The response of Salmonella typhimurium to low nutrient levels was determined by measuring the concentrations of lipids, carbohydrates, DNA, RNA, and proteins over a 32-day starvation period. Ultrastructural integrity was observed by transmission electron microscopy. Lipid and carbohydrate content of bacterial cells rapidly declined within the first 16 days, while DNA and proteins exhibited a more gradual decline over the 32 days of starvation. In contrast, RNA content did not decrease appreciably upon nutrient starvation. Structural damage occurred especially after 16 days of starvation. After 32 days of nutrient deprivation, we recorded degenerative cellular forms, a coccoidal cell shape, a decrease in cellular volume, and the loss of the three-layered outer membrane. The morphological and structural alterations correlated with virulence in infected animals. We observed a decrease in virulence of S. typhimurium after 9, 16, and 32 days of starvation, reaching a maximal decrease after 32 days of nutrient deprivation. The decrease in virulence correlated to surface hydrophobicity alterations, adherence to eukaryotic cells, and phagocytosis.

Correlation between changes in surface hydrophobicity and interaction of Streptococcus pyogenes with human polymorphonuclear leukocytes after prolonged starvation in sea water

The aim of this research was to evaluate the persistence of virulence characteristics of Streptococcus pyogenes cells after prolonged starvation in sea water. Studies were carried out on changes in viability, alterations in the chemical composition and surface hydrophobicity and the interaction of S. pyogenes with human polymorphonuclear leukocytes (PMN) after starvation. Results showed that surface hydrophobicity decreased progressively starting after three days of starvation and was correlated with the decrease in total carbohydrate, lipid and protein content. These values correlated with a better interaction of S. pyogenes cells with the PMN, as shown by a chemiluminescence increase that reached a peak after 32 days of starvation. Furthermore, bacterial cells became more easily phagocytized and killed by human PMN.

Biological activities of cell envelope fragments of the archaeobacterium Sulfolobus solfataricus: lethal toxicity, local hypersensitivity, pyrogenicity and spleen lymphocyte mitogenicity

The sensitizing effect and the local and general toxicity related to membrane components of the archaeobacterium Sulfolobus solfataricus was studied. Cell envelope fragments were biologically active but this activity was lost upon separation of the lipid and protein components. The envelope fragments exerted lethal effects on mice sensitized with D-galactosamine that were prevented by pretreatment with anti-TNF-alpha serum. This lethal activity occurred in both LPS-responder (BALB/cByJ) and LPS-nonresponder (C3H/HeJ) mouse strains. In addition, Sulfolobus envelope fragments tested in rabbits caused a local Schwartzman reaction, and showed pyrogenic activity. In vitro, the envelope fragments that act on spleen lymphocytes of the LPS-responder (BALB/cByJ) and LPS-nonresponder (C3H/HeJ) mice caused an uptake of [3H]thymidine similar to that caused by concanavalin A. A similar toxic activity to that exerted by eubacteria is therefore exerted by this non-pathogenic archaeobacterium despite the difference in surface chemistry.

Alterations of the endoalveolar surfactant after surgery with extracorporeal circulation

In 10 patients who required extracorporeal circulation (ECC) during surgery, we studied the damage induced by surgery to the pulmonary surfactant and the effectiveness of ambroxol in preventing changes in the phospholipid pool. There were 5 control patients and 5 patients who were given 1 g/day of ambroxol on the 4 days prior to and the 4 days after surgery. To follow changes in phospholipid concentrations, bronchoalveolar lavage (BAL) was performed before surgery and 24 h and 8 days after ECC. Phospholipids were assayed in the BAL liquid by two-dimensional thin-layer chromatography. There were marked decreases in total phosphorus and quantitative alterations of individual phospholipid species in the surfactant of the control group, but not in the patients treated with ambroxol.

[Incidence of cefotetan sensitivity in anaerobic microbes responsible for acute and chronic relapsing bronchopneumonia]

Bronchial fluid samples obtained from 50 patients with respiratory tract infections were analyzed for anaerobic flora isolation, identification of micro-organisms and evaluation of their sensitivity to cefotetan. Anaerobic strains were identified in 18 patients (36%), generally with exacerbations of chronic diseases: cefotetan was active on 100% of isolates.