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B lymphocytes undergo TLR2-dependent apoptosis upon Shigella infection.

Nothelfer K, Arena ET, Pinaud L, Neunlist M, Mozeleski B, Belotserkovsky I, Parsot C, Dinadayala P, Burger-Kentischer A, Raqib R, Sansonetti PJ, Phalipon A - J. Exp. Med. (2014)

Bottom Line: The induction of a type three secretion apparatus (T3SA)-dependent B cell death is observed in the human CL-01 B cell line in vitro, as well as in mouse B lymphocytes in vivo.The presence of bacterial co-signals is required to sensitize B cells to apoptosis and to up-regulate tlr2, thus enhancing IpaD binding.Apoptotic B lymphocytes in contact with Shigella-IpaD are detected in rectal biopsies of infected individuals.

View Article: PubMed Central - HTML - PubMed

Affiliation: Institut Pasteur, INSERM U786, Unité de Pathogénie Microbienne Moléculaire, 75015 Paris, FranceInstitut Pasteur, INSERM U786, Unité de Pathogénie Microbienne Moléculaire, 75015 Paris, France.

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S. flexneri interacts with and invades B lymphocytes upon ex vivo infection of human colonic tissue. (A and B) Fluorescence microscopy of histological analysis. T3SA− bacteria were found attached to the epithelium (A), whereas WT bacteria ruptured the epithelial barrier and got access to underlying tissue (B). (C) Confocal imaging of whole-mount tissue infected with WT bacteria, with top view (C) and orthogonal slice (C’). Reflection is shown in gray and crypts are outlined with a dashed line. (D and E) Confocal imaging of isolated lymph follicles in 150-µm-thick tissue sections, with top view (D) and orthogonal slices (E). Bacteria were stained with an antibody specific for S. flexneri 5a (red), B cells with anti-CD20cy (membrane receptor, green), and DAPI nuclei staining is shown in blue. Arrows point to bacteria. Bars: (A and B) 50 µm; (C and C’) 40 µm; (D) 20 µm; (E) 5 µm.
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fig1: S. flexneri interacts with and invades B lymphocytes upon ex vivo infection of human colonic tissue. (A and B) Fluorescence microscopy of histological analysis. T3SA− bacteria were found attached to the epithelium (A), whereas WT bacteria ruptured the epithelial barrier and got access to underlying tissue (B). (C) Confocal imaging of whole-mount tissue infected with WT bacteria, with top view (C) and orthogonal slice (C’). Reflection is shown in gray and crypts are outlined with a dashed line. (D and E) Confocal imaging of isolated lymph follicles in 150-µm-thick tissue sections, with top view (D) and orthogonal slices (E). Bacteria were stained with an antibody specific for S. flexneri 5a (red), B cells with anti-CD20cy (membrane receptor, green), and DAPI nuclei staining is shown in blue. Arrows point to bacteria. Bars: (A and B) 50 µm; (C and C’) 40 µm; (D) 20 µm; (E) 5 µm.

Mentions: To assess whether or not S. flexneri comes into contact with B lymphocytes upon infection, we used an ex vivo infection model of human colonic tissue to mimic the natural environment in which the bacterium triggers its infectious process (Coron et al., 2009). Human colonic tissue pieces were incubated for 6 h with WT, invasive S. flexneri, or a noninvasive S. flexneri mutant, which is unable to assemble the T3SA (T3SA− or mxiD mutant). Immunohistochemistry of the infected tissues showed that WT but not T3SA− bacteria breached the epithelial barrier (Fig. 1, A and B). Confocal analysis of fixed whole-mount tissues revealed that WT S. flexneri came into contact with LP B cells at sites of epithelial destruction (Fig. 1, C and C′). For confocal analysis deeper within the tissue, we used 150-µm-thick transversal vibratome sections and found WT S. flexneri within ILFs both in contact with and intracellular within B cells (Fig. 1, D and E; and Video 1). These findings indicate that invasive Shigella interacts with and may invade B lymphocytes upon crossing of the epithelial barrier.


B lymphocytes undergo TLR2-dependent apoptosis upon Shigella infection.

Nothelfer K, Arena ET, Pinaud L, Neunlist M, Mozeleski B, Belotserkovsky I, Parsot C, Dinadayala P, Burger-Kentischer A, Raqib R, Sansonetti PJ, Phalipon A - J. Exp. Med. (2014)

S. flexneri interacts with and invades B lymphocytes upon ex vivo infection of human colonic tissue. (A and B) Fluorescence microscopy of histological analysis. T3SA− bacteria were found attached to the epithelium (A), whereas WT bacteria ruptured the epithelial barrier and got access to underlying tissue (B). (C) Confocal imaging of whole-mount tissue infected with WT bacteria, with top view (C) and orthogonal slice (C’). Reflection is shown in gray and crypts are outlined with a dashed line. (D and E) Confocal imaging of isolated lymph follicles in 150-µm-thick tissue sections, with top view (D) and orthogonal slices (E). Bacteria were stained with an antibody specific for S. flexneri 5a (red), B cells with anti-CD20cy (membrane receptor, green), and DAPI nuclei staining is shown in blue. Arrows point to bacteria. Bars: (A and B) 50 µm; (C and C’) 40 µm; (D) 20 µm; (E) 5 µm.
© Copyright Policy - openaccess
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4042640&req=5

fig1: S. flexneri interacts with and invades B lymphocytes upon ex vivo infection of human colonic tissue. (A and B) Fluorescence microscopy of histological analysis. T3SA− bacteria were found attached to the epithelium (A), whereas WT bacteria ruptured the epithelial barrier and got access to underlying tissue (B). (C) Confocal imaging of whole-mount tissue infected with WT bacteria, with top view (C) and orthogonal slice (C’). Reflection is shown in gray and crypts are outlined with a dashed line. (D and E) Confocal imaging of isolated lymph follicles in 150-µm-thick tissue sections, with top view (D) and orthogonal slices (E). Bacteria were stained with an antibody specific for S. flexneri 5a (red), B cells with anti-CD20cy (membrane receptor, green), and DAPI nuclei staining is shown in blue. Arrows point to bacteria. Bars: (A and B) 50 µm; (C and C’) 40 µm; (D) 20 µm; (E) 5 µm.
Mentions: To assess whether or not S. flexneri comes into contact with B lymphocytes upon infection, we used an ex vivo infection model of human colonic tissue to mimic the natural environment in which the bacterium triggers its infectious process (Coron et al., 2009). Human colonic tissue pieces were incubated for 6 h with WT, invasive S. flexneri, or a noninvasive S. flexneri mutant, which is unable to assemble the T3SA (T3SA− or mxiD mutant). Immunohistochemistry of the infected tissues showed that WT but not T3SA− bacteria breached the epithelial barrier (Fig. 1, A and B). Confocal analysis of fixed whole-mount tissues revealed that WT S. flexneri came into contact with LP B cells at sites of epithelial destruction (Fig. 1, C and C′). For confocal analysis deeper within the tissue, we used 150-µm-thick transversal vibratome sections and found WT S. flexneri within ILFs both in contact with and intracellular within B cells (Fig. 1, D and E; and Video 1). These findings indicate that invasive Shigella interacts with and may invade B lymphocytes upon crossing of the epithelial barrier.

Bottom Line: The induction of a type three secretion apparatus (T3SA)-dependent B cell death is observed in the human CL-01 B cell line in vitro, as well as in mouse B lymphocytes in vivo.The presence of bacterial co-signals is required to sensitize B cells to apoptosis and to up-regulate tlr2, thus enhancing IpaD binding.Apoptotic B lymphocytes in contact with Shigella-IpaD are detected in rectal biopsies of infected individuals.

View Article: PubMed Central - HTML - PubMed

Affiliation: Institut Pasteur, INSERM U786, Unité de Pathogénie Microbienne Moléculaire, 75015 Paris, FranceInstitut Pasteur, INSERM U786, Unité de Pathogénie Microbienne Moléculaire, 75015 Paris, France.

Show MeSH
Related in: MedlinePlus