Chlamydia
Many unresolved puzzles surround Chlamydia. How do the bacteria manage to set up their home in a human cell? What event, what bacterial component does the human host cell notice when it is infected? Why is the host cell prepared to deliver nutrients to the parasites within? Why does Chlamydia cause such devastating infections as it does in a substantial number of female patients? We are trying to understand some of these issues, from the question of how Chlamydia blocks apoptosis (Fischer et al., 2004a; Fischer et al., 2004b; Kontchou et al., 2016), over the role of a protease Chlamydia secretes to the recognition of Chlamydia by the host cell (Christian et al., 2010; Christian et al., 2011; Volceanov et al., 2014). A further question we ask is how the immune system recognizes chlamydial infections, and how the tissue damage that is typical of chlamydial infections comes about.
References
Christian, J., Vier, J., Paschen, S.A., and Hacker, G. (2010). Cleavage of the NF-{kappa}B family protein p65/RelA by the chlamydial protease-like activity factor (CPAF) impairs proinflammatory signaling in cells infected with Chlamydiae. The Journal of biological chemistry 285, 41320-41327.
Christian, J.G., Heymann, J., Paschen, S.A., Vier, J., Schauenburg, L., Rupp, J., Meyer, T.F., Hacker, G., and Heuer, D. (2011). Targeting of a chlamydial protease impedes intracellular bacterial growth. PLoS pathogens 7, e1002283.
Fischer, S.F., Harlander, T., Vier, J., and Hacker, G. (2004a). Protection against CD95-induced apoptosis by chlamydial infection at a mitochondrial step. Infect.Immun. 72, 1107-1115.
Fischer, S.F., Vier, J., Kirschnek, S., Klos, A., Hess, S., Ying, S., and Hacker, G. (2004b). Chlamydia Inhibit Host Cell Apoptosis by Degradation of Proapoptotic BH3-only Proteins. The Journal of experimental medicine 200, 905-916.
Kontchou, C.W., Tzivelekidis, T., Gentle, I.E., and Hacker, G. (2016). Infection of epithelial cells with Chlamydia trachomatis inhibits TNF-induced apoptosis at the level of receptor internalisation while leaving non-apoptotic TNF-signalling intact. Cellular microbiology.
Volceanov, L., Herbst, K., Biniossek, M., Schilling, O., Haller, D., Nolke, T., Subbarayal, P., Rudel, T., Zieger, B., and Hacker, G. (2014). Septins arrange F-actin-containing fibers on the Chlamydia trachomatis inclusion and are required for normal release of the inclusion by extrusion. mBio 5, e01802-01814.