Endothelial progenitor cells are produced in the bone marrow and have the hemangioblast as common precursor to hematopoietic stem cells. They have been identified in 1997 in the peripheral blood stream. The EPC are able to migrate, proliferate and differentiate into mature endothelial cells and to determine the formation of new blood vessels even in the postnatal period. These cells can be infected by Bartonella henselae, a Gram-negative pathogen, aetiological agent of a series of human diseases known as bartonellosis. Polysaccharide A pro-duced by Bacteroides fragilis, a human intestinal bacterium, has immunoregulatory properties, among which is proven in mice to provide protection from inflammation caused by B. henselae. We have infected the EPC with B. henselae, B. fragilis WT or B. fragilis PSA (not able to produce the polysaccharide A), or coinfected with B. henselae and B. fragilis, WT or PSA respectively, to assess whether the polysaccharide A had a role in the response of these cells to the infection. After the ultrastructural characterization of bacterial strains used in our experiments, Bacteroides ability to infect EPC was assessed by CLSM. Both bacterial strains are internalized already at 24h after infection and at a multiplicity of infection of 100. By TEM it was observed that Bacteroides in contrast to Bartonella, are internalized activating cytoplasmic lysosomes that digest them. B. henselae instead infects those cells forming invasomes in which they continues to proliferate. So polysaccharide A accentuates the macrophagic features that these cells have in their early differentiation stage. Analysis of genic expression using real time PCR from total RNA extracted by the cell cultures have shown the up-regulation of the gene coding for the IL-10 anti-inflammatory cytokine in cells co-infected with B. fragilis WT and B. henselae compared to the cells infected only with B. henselae. The main inflammatory cytokines secretion evaluated by ELISA has also evidenced an increase of IL-10 produced by cells coinfected with B. fragilis WT and B. henselae. These cells react to the co-infection in the same manner of macrophages. These data assert that the EPC does not play only a key role in vasculogenesis, but in an adult organism they could also play an essential role in the immune response. The EPC may collaborate with macrophages and T cells CD4+, to the inflammatory process triggered by the polysaccharide A after infection.

Effects of polysaccharide A product by Bacteroides fragilis on endothelial progenitor cells / Cerciello, Raimondo; Anna, Di Biase; Colicchio, Roberta; Casamassimi, Amelia; Claudio, Napoli; Salvatore, Paola; Avallone, Bice. - In: EUROPEAN JOURNAL OF HISTOCHEMISTRY. - ISSN 1121-760X. - 59:1(2015), pp. 3-4. (Intervento presentato al convegno 61ST CONGRESS OF THE ITALIAN EMBRYOLOGICAL GROUP (GEI) tenutosi a PISA nel 7-10 giugno).

Effects of polysaccharide A product by Bacteroides fragilis on endothelial progenitor cells

CERCIELLO, RAIMONDO;COLICCHIO, ROBERTA;CASAMASSIMI, AMELIA;SALVATORE, PAOLA;AVALLONE, BICE
2015

Abstract

Endothelial progenitor cells are produced in the bone marrow and have the hemangioblast as common precursor to hematopoietic stem cells. They have been identified in 1997 in the peripheral blood stream. The EPC are able to migrate, proliferate and differentiate into mature endothelial cells and to determine the formation of new blood vessels even in the postnatal period. These cells can be infected by Bartonella henselae, a Gram-negative pathogen, aetiological agent of a series of human diseases known as bartonellosis. Polysaccharide A pro-duced by Bacteroides fragilis, a human intestinal bacterium, has immunoregulatory properties, among which is proven in mice to provide protection from inflammation caused by B. henselae. We have infected the EPC with B. henselae, B. fragilis WT or B. fragilis PSA (not able to produce the polysaccharide A), or coinfected with B. henselae and B. fragilis, WT or PSA respectively, to assess whether the polysaccharide A had a role in the response of these cells to the infection. After the ultrastructural characterization of bacterial strains used in our experiments, Bacteroides ability to infect EPC was assessed by CLSM. Both bacterial strains are internalized already at 24h after infection and at a multiplicity of infection of 100. By TEM it was observed that Bacteroides in contrast to Bartonella, are internalized activating cytoplasmic lysosomes that digest them. B. henselae instead infects those cells forming invasomes in which they continues to proliferate. So polysaccharide A accentuates the macrophagic features that these cells have in their early differentiation stage. Analysis of genic expression using real time PCR from total RNA extracted by the cell cultures have shown the up-regulation of the gene coding for the IL-10 anti-inflammatory cytokine in cells co-infected with B. fragilis WT and B. henselae compared to the cells infected only with B. henselae. The main inflammatory cytokines secretion evaluated by ELISA has also evidenced an increase of IL-10 produced by cells coinfected with B. fragilis WT and B. henselae. These cells react to the co-infection in the same manner of macrophages. These data assert that the EPC does not play only a key role in vasculogenesis, but in an adult organism they could also play an essential role in the immune response. The EPC may collaborate with macrophages and T cells CD4+, to the inflammatory process triggered by the polysaccharide A after infection.
2015
Effects of polysaccharide A product by Bacteroides fragilis on endothelial progenitor cells / Cerciello, Raimondo; Anna, Di Biase; Colicchio, Roberta; Casamassimi, Amelia; Claudio, Napoli; Salvatore, Paola; Avallone, Bice. - In: EUROPEAN JOURNAL OF HISTOCHEMISTRY. - ISSN 1121-760X. - 59:1(2015), pp. 3-4. (Intervento presentato al convegno 61ST CONGRESS OF THE ITALIAN EMBRYOLOGICAL GROUP (GEI) tenutosi a PISA nel 7-10 giugno).
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11588/635384
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