Caspases 4, 5 and 11 are Intracellular LPS Receptors

A LPS receptor has already been identified by Beutler and colleagues. This finding was awarded the NOBEL prize in 2011. In the actual issue of Nature (doi:10.1038/nature13683) Shi and colleagues describe the role of caspases – enzymes triggerung cell death called apoptosis – as intracellular receptors for LPS.

When LPS is delived intracellarly into macrophages, epithelial cells or keratinocytes these cells undergo necrosis. The process is specific for intact Lipid A. Murine caspase-11 as well as human caspases 4 and 5 bind to LPS and Lipid A. They induce what is called pyroptosis. The paper is nicely done, however, one might wonder when and how LPS is released from the phagolysosome and becomes available within a cell.

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