Guest guest Posted July 10, 2006 Report Posted July 10, 2006 Basically, apoptosis (which almost equivalent to the term " host- directed cell death " ) is likely to have a role in getting rid of chronic intracellular infections. NFkB activation is pretty much at the center of the immune response. NFkB is present all the time but not in activated form. When it becomes activated it migrates to the cell nucleus and changes the transcription rate of many, many genes, thus changing whats going on in the host cell. NFkB activation generally opposes host-directed cell death. This is a little contraintuitive. Why shouldnt it favor host-directed cell death, which can get us rid of infected cells? The reason is probably that host cell death is a double edged sword. Say you suffer alot of epithelial cell death in the lung epithelium (epithelium is the exposed surface). Those cells have tight junctions between them, so that nothing can get thru. If lots of epithelial cells die, then any microbe you inhale can get into your tissue by travelling around the spaces between the cells underneath the epithelium, which do not have tight junctions. Further, there are many infectious agents that want to kill your cells (at least white cells, and probably other cells too) before those cells kill said agents. In many cases these agents may do so at least in part by subverting the host equipment designed for host-directed cell death. In this case the fact that NFkB activation opposes host-directed cell death is an advantage. Finally, it seems that some bacteria are not severely harmed by host- directed cell death. Unfotunately I cannot seem to remember which ones. In these cases death of the infected cell is of somewhat limited use. Marie Krouns compendium on this topic is excellent reading, however NFkB activation has been shown not to be necessary for the anti- apoptotic power exerted by certain rickettsiae. > > Will someone please decipher this? > > http://lymerick.ulmarweb.dk/NFkB.htm > > It looks very interesting, but its way over my head, for sure. > > Best wishes, > > Mickie > Quote
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