Bacterial lipopolysaccharide (LPS) is an endotoxin that can lead to lethal infection sepsis by activating innate immune responses. Cytoplasmic LPS(cLPS) induces the assembly of an inflammasome that contains
caspases-4/5 in humans or
caspase-11 in mice NLRP11 serves as a pattern recognition receptor for cLPS and can result in
caspase-4 inflammasome activation. There is also a novel role of NLRP11 in the regulation of inflammatory responses in human cells. In primates, NLRP11 also serves as a conserved negative regulator of TLR signaling. NLRP11 acts as a negative regulator of type I IFN and virus-induced apoptosis by disrupting the
Mitochondrial antiviral-signaling protein (MAVS) signalosome activity. ATP-dependent RNA helicase
DDX3X is a novel binding partner of NLRP11. NLRP11 suppressed the positive effect of DDX3X on
NLRP3 inflammasome-mediated caspase-1 activation. Research also suggested that there might be a role of NLRP11 function in innate immunity. NLRP11 and DDX3X might become promising targets for the modulation of innate immune responses. Upon viral infection, Type I IFN activates NLRP11, and upon activation, it translocates to mitochondria to interact with MAVS. NLRP11 degrades TRAF6 using MAVS to attenuate the production of type I IFNs and virus-induced apoptosis. NLRP11 acts as a negative regulator of type I IFN and virus-induced apoptosis via disrupting the activity of MAVS signalosome. In human macrophages, NLRP11 is an indispensable component of the NLRP3 inflammasome. The most studied inflammasome sensor molecule of the NLR family is NLRP3, and it contains an amino-terminal PYRIN (PYD) domain, a nucleotide-binding NACHT domain, and a carboxyterminal leucine-rich repeat (LRR) domain. The ATP binding is required for NLRP3 activation, NACHT domain of NLRP3 contains ATPase activity, and mutation of this site reduces ATP binding, caspase-1 activation, IL-1 production, cell death, macromolecular complex formation, and its association with
apoptosis-associated speck-like protein containing a CARD (ASC). There is an interaction between NLRP11, NLRP3, and ASC. NLRP3 inflammasome activation is inhibited by specific deletion of NLRP11, which leads to inhibition of ASC polymerization, caspase-1 activation, and subsequent cytokine release. NLRP3 mutations that cause
cryopyrin-associated periodic syndrome (CAPS) also require NLRP11 for inflammasome responses. The complex biology of
inflammasome regulation is being explored, and the role of NLRP11 in diseases is partially understood. == References ==