NLRP3 regulates neutrophil functions and contributes to hepatic ischemia-reperfusion injury independently of inflammasomes.
Inflammation plays a key role in the pathophysiology of hepatic ischemia-reperfusion (I/R) injury. However, the mechanism by which hepatic I/R induces inflammatory responses remains unclear. Recent evidence indicates that a sterile inflammatory response triggered by I/R is mediated through a multiple-protein complex called the inflammasome. Therefore, we investigated the role of the inflammasome in hepatic I/R injury and found that hepatic I/R stimuli upregulated the inflammasome-component molecule, nucleotide-binding oligomerization domain-like receptor (NLR) family pyrin domain-containing 3 (NLRP3), but not apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC). NLRP3(-/-) mice, but not ASC(-/-) and caspase-1(-/-) mice, had significantly less liver injury after hepatic I/R. NLRP3(-/-) mice showed reduced inflammatory responses, reactive oxygen species production, and apoptosis in I/R liver. Notably, infiltration of neutrophils, but not macrophages, was markedly inhibited in the I/R liver of NLRP3(-/-) mice. Bone marrow transplantation experiments showed that NLRP3 not only in bone marrow-derived cells, but also in non-bone marrow-derived cells contributed to liver injury after I/R. In vitro experiments revealed that keratinocyte-derived chemokine-induced activation of heterotrimeric G proteins was markedly diminished. Furthermore, NLRP3(-/-) neutrophils decreased keratinocyte-derived chemokine-induced concentrations of intracellular calcium elevation, Rac activation, and actin assembly formation, thereby resulting in impaired migration activity. Taken together, NLRP3 regulates chemokine-mediated functions and recruitment of neutrophils, and thereby contributes to hepatic I/R injury independently of inflammasomes. These findings identify a novel role of NLRP3 in the pathophysiology of hepatic I/R injury.
Division of Inflammation Research, Center for Molecular Medicine, Jichi Medical University, Tochigi 329-0498, Japan;
Yoshiyuki
Y
Inoue
Koumei
K
Shirasuna
Hiroaki
H
Kimura
Fumitake
F
Usui
Akira
A
Kawashima
Tadayoshi
T
Karasawa
Kenji
K
Tago
Katsuya
K
Dezaki
Satoshi
S
Nishimura
Junji
J
Sagara
Tetsuo
T
Noda
Yoichiro
Y
Iwakura
Hiroko
H
Tsutsui
Shun'ichiro
S
Taniguchi
Ken
K
Yanagisawa
Toshihiko
T
Yada
Yoshikazu
Y
Yasuda
Masafumi
M
Takahashi
D000818:Animals; D017209:Apoptosis / Q000276:immunology; D015153:Blotting, Western; D002352:Carrier Proteins / Q000276:immunology* / Q000378:metabolism; D002634:Chemotaxis, Leukocyte; D005434:Flow Cytometry; D007150:Immunohistochemistry; D058847:Inflammasomes / Q000276:immunology; D008099:Liver / Q000276:immunology* / Q000378:metabolism / Q000473:pathology; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D000071199:NLR Family, Pyrin Domain-Containing 3 Protein; D009504:Neutrophils / Q000276:immunology* / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction; D015427:Reperfusion Injury / Q000276:immunology* / Q000473:pathology; D020133:Reverse Transcriptase Polymerase Chain Reaction
D002352:Carrier Proteins; D058847:Inflammasomes; D000071199:NLR Family, Pyrin Domain-Containing 3 Protein; C492716:Nlrp3 protein, mouse