I have been reading about the cellular process of autophagy, which involves the phagocytosis of components within the cell and fusion of the autophagosome with a lysosome. Autophagy is used by the cell to dispose of protein aggregates, and damaged organelles. One of the main stimuli for induction of autophagy is cellular stress, but recently it has been studied in the context of viral invasion. Autophagy has been shown to be important during the antiviral response, but whether it is beneficial to the host or to the virus is still a matter of debate. For instance, retroviruses have been shown to use autophagy proteins to aid in assembly of viral capsid proteins [1]. However, it has also been proposed that autophagy might be important for cross presentation of endogenous viral antigens on MHC class II molecules in dendritic cells [2].
I find it very interesting that basic cellular processes like autophagy can have dual roles in either aiding our own immune system, or aiding a pathogen. What are some other ways you think autophagy can help our immune system, or ways it can help the pathogen?
Here is a nice review on the role of autophagy in innate and adaptive immunity:
http://www.ncbi.nlm.nih.gov/pubmed?term=Unveiling%20the%20roles%20of%20autophagy%20in%20innate%20and%20adaptive%20immunity
[1]
Autophagy pathway intersects with
HIV-1 biosynthesis and
regulates viral yields in
macrophages.
http://www.ncbi.nlm.nih.gov/pubmed?term=Autophagy%20pathway%20intersects%20with%20HIV-1%20biosynthesis%20and%20regulates%20viral%20yields%20in%20macrophages
[2] Nimmerjahn, F. et al. Major histocompatibility complex class II-restricted presentation of a cytosolic antigen by autophagy. Eur. J. Immunol. 33, 1250–1259 (2003).
Autophagy has been linked to cancer cell growth. It is thought that autophagy provides nutrients to cancer cells. Autophagy has also been seen to be involved in getting rid of bacterial infections by the innate immune system. I think it depends on the situation if autophagy is good or bad. Another way autophagy helps are immune system is in the development of B and T cells. Researchers have seen that B and T cells cannot develop without autophagy.
ReplyDeleteRathmell, J. Metabolism and autophagy in the immune system. Immunological Review 2012. 249: 5-13
The autophagy in cancer is an interesting fact because when apoptosis is induced stress signals are released in order to stimulate the release of the cell's contents and autophagy. I work in breast cancer research and actually cancers with central necrosis have a worse prognosis than ones without.
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