In non-stimulated cells, the activity of NLRP3 is inhibited through binding of the LRR to the NACHT domain, thereby blocking oligomerization and binding of the apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC) (Fig 2). This auto-inhibition is relieved through the binding of a stimulant molecule to the LRRs. This enables the oligomerization and binding of NLRPs to the adapter protein ASC and pro-caspase-1, making a large multiprotein inflammasome complex, which results in the activation of caspase-1 and cleavage of pro-IL-1β (Tschopp et al., 2003). Four inflammasome complexes have been partially characterized to date: NLRP1, NLRP3, NLRC4 (also called IPAF) and AIM2 (Bryant and Fitzgerald, 2009) (Fig 2).
