The complement membrane attack complex triggers intracellular Ca2+ fluxes leading to NLRP3 inflammasome activation.

The membrane attack complex of complement (MAC), apart from its classical role of lysing cells, can also trigger a range of non-lethal effects on cells, acting as a drive to inflammation. In the present study, we chose to investigate these non-lethal effects on inflammasome activation. We found that, following sublytic MAC attack, there is increased cytosolic Ca(2+) concentration, at least partly through Ca(2+) release from the endoplasmic reticulum lumen via the inositol 1,4,5-triphosphate receptor (IP3R) and ryanodine receptor (RyR) channels. This increase in intracellular Ca(2+) concentration leads to Ca(2+) accumulation in the mitochondrial matrix via the 'mitochondrial calcium uniporter' (MCU), and loss of mitochondrial transmembrane potential, triggering NLRP3 inflammasome activation and IL-1β release. NLRP3 co-localises with the mitochondria, probably sensing the increase in calcium and the resultant mitochondrial dysfunction, leading to caspase activation and apoptosis. This is the first study that links non-lethal effects of sublytic MAC attack with inflammasome activation and provides a mechanism by which sublytic MAC can drive inflammation and apoptosis.

Citation

Kathy Triantafilou, Timothy R Hughes, Martha Triantafilou, B Paul Morgan. The complement membrane attack complex triggers intracellular Ca2+ fluxes leading to NLRP3 inflammasome activation. Journal of cell science. 2013 Jul 1;126(Pt 13):2903-13

PMID: 23613465

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