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Updated: Jun 14, 2026

Activation and Measurement of NLRP3 Inflammasome Activity Using IL-1β in Human Monocyte-derived Dendritic Cells
Published on: May 22, 2014
Innate immune detection of bacterial virulence factors via the NLRC4 inflammasome
Edward A Miao1, Sarah E Warren
1Institute for Systems Biology, 1441 N 34th St, Seattle, WA 98103, USA. emiao@systemsbiology.org
Introduction:
Cytokine production by innate immune cells is initiated by signaling downstream of pattern recognition receptors, including Toll-like receptors.
Discussion:
A subset of cytokines, including IL-1beta and IL-18, require post-translational proteolysis before secretion, which provides a second mechanism of regulation. This proteolysis is dependent upon caspase 1, which is activated by Nod-like receptor (NLR) signaling. NLRC4 (previously named Ipaf) activates caspase 1 in response to bacterial virulence factors including type III and IV secretion systems (T3SS and T4SS). NLRC4 recognizes T3SS/T4SS in two ways: indirectly by detecting flagellin, and directly by detecting the T3SS rod protein. Both flagellin and rod protein are unintentionally delivered to the mammalian cytosol by the bacterium through the T3SS.
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