| 1. |
- Krocova, Zuzana, et al.
(författare)
-
Interaction of B cells with intracellular pathogen Francisella tularensis.
- 2008
-
Ingår i: Microbial pathogenesis. - : Elsevier BV. - 0882-4010. ; 45:2, s. 79-85
-
Tidskriftsartikel (refereegranskat)abstract
- Immunity to Francisella tularensis is largely mediated by T lymphocytes but an important role of B lymphocytes in early stage of infection was previously uncovered. We wanted to find out if F. tularensis is able to infect B cells and/or influence them by direct contact. To investigate this possibility we infected B cell lines from mouse (A20) or humans (Ramos RA-1), or primary mouse spleen cells, with F. tularensis LVS and F. tularensis FSC200 in vitro. In all cases, we detected bacteria on the cell surface and inside the B cells using transmission electron microscopy. More than 20% cells were infected by microbes after 24h. The number of bacteria, determined by CFU, increased about 1 log during 24h. Infection with live bacteria led to apoptosis of Ramos cells and mouse CD19(+) spleen cells. Approximately 30% of cells were apoptotic after 24h and 70% after 48 h, independently of the F. tularensis strain, while only 10% of non-infected cell were apoptotic at either time point. Apoptosis was confirmed by Western blot using anti-PARP antibodies. Thus, this study demonstrates unique phenomenon - namely, the ability of the intracellular pathogen F. tularensis to invade and induce apoptosis in B cells.
|
|
| 2. |
- Zivna, Lucie, et al.
(författare)
-
Activation of B cell apoptotic pathways in the course of Francisella tularensis infection.
- 2010
-
Ingår i: Microbial pathogenesis. - : Elsevier BV. - 1096-1208 .- 0882-4010. ; 49:5, s. 226-36
-
Tidskriftsartikel (refereegranskat)abstract
- Francisella tularensis is a facultative intracellular, gram-negative bacterium that induces apoptosis in macrophages and B cells. Here we show apoptotic pathways that are activated in the Ramos human B cell line in the course of F. tularensis infection. Live bacteria F. tularensis FSC200 activate caspases 8, 9 and 3, as well as Bid; release cytochrome c and apoptosis-inducing factor from mitochondria; and induce depolarization of mitochondrial membrane potential in the Ramos cell line, thus leading these cells to apoptosis. Unlike live bacteria, killed F. tularensis FSC200 bacteria activated only caspase 3, and did not cause apoptosis of Ramos cells as measured by annexin V. Killed bacteria also caused accumulation of anti-apoptotic protein Bclx(L) in mitochondrial membranes. Thus, live F. tularensis activates both caspase pathways (receptor-mediated and intrinsic) as well as caspase-independent mitochondrial death.
|
|
