Espressione di citochine e molecole di adesione in cellule endoteliali umane stimolate con diversi componenti batterici

Dottorato di ricerca in scienze microbiologiche. 8. ciclo. A.a. 1992-95. Relatore e coordinatore F. Galdiero. Controrelatore M. A. TufanoConsiglio Nazionale delle Ricerche - Biblioteca Centrale - P.le Aldo Moro, 7, Rome; Biblioteca Nazionale Centrale - P.za Cavalleggeri, 1, Florence / CNR - Consiglio Nazionale delle RichercheSIGLEITItal

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

Human monocytes and gingival fibroblasts release tumor necrosis factor-alpha, interleukin-1 alpha and interleukin-6 in response to particulate and soluble fractions of Prevotella melaninogenica and Fusobacterium nucleatum

In this study we provide evidence that structural and soluble components of periodontopathogenic bacteria, such as Prevotella melaninogenica and Fusobacterium nucleatum, induce the release of cytokines in vitro known to cause in vivo necrotic inflammatory phenomena and bone resorption (tumor necrosis factor-α, interleukin-1α and interleukin-6). Human monocytes and gingival fibroblasts were cultivated in vitro in the presence of both particulate and soluble bacterial fractions. A dose-dependent production of tumor necrosis factor-α by monocytes and gingival fibroblasts was observed in the presence of fractions of P. melaninogenica and F. nucleatum. Interleukin-1α was produced in approximately the same quantities in the presence of soluble fractions of either P. melaninogenica or F. nucleatum, but in greater quantities in response to particulate fractions of P. melaninogenica. Monocytes release larger amounts of interleukin-1α (about 3000 pg/ml) than gingival fibroblasts (about 1500 pg/ml). Interleukin-6 was released in greater quantities by monocytes in the presence of the pellet fraction of P. melaninogenica (about 5.5 ng/ml), but gingival fibroblasts released larger amounts of interleukin-6, especially in the presence of particulate and soluble components of F. nucleatum (about 12 ng/ml). The ability to induce the release of these cytokines notably increases the pathogenic potential of the bacteria involved in the damage of periodontal tissue

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

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

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

TNF-α 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-α 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-α expression and release. On the contrary, GH and insulin increased the susceptibility to infection of activated cells but did not modify TNF-α expression with respect to cells treated only with hormones