Inflammasome-mediated regulation of hepatic stellate cells.
The inflammasome is a cytoplasmic multiprotein complex that has recently been identified in immune cells as an important sensor of signals released by cellular injury and death. Analogous to immune cells, hepatic stellate cells (HSC) also respond to cellular injury and death. Our aim was to establish whether inflammasome components were present in HSC and could regulate HSC functionality. Monosodium urate (MSU) crystals (100 microg/ml) were used to experimentally induce inflammasome activation in LX-2 and primary mouse HSC. Twenty-four hours later primary mouse HSC were stained with alpha-smooth muscle actin and visualized by confocal microscopy, and TGF-beta and collagen1 mRNA expression was quantified. LX-2 cells were further cultured with or without MSU crystals for 24 h in a transwell chemotaxis assay with PDGF as the chemoattractant. We also examined inhibition of calcium (Ca(2+)) signaling in LX-2 cells treated with or without MSU crystals using caged inositol 1,4,5-triphosphate (IP(3)). Finally, we confirmed an important role of the inflammasome in experimental liver fibrosis by the injection of carbon tetrachloride (CCl(4)) or thioacetamide (TAA) in wild-type mice and mice lacking components of the inflammasome. Components of the inflammasome are expressed in LX-2 cells and primary HSC. MSU crystals induced upregulation of TGF-beta and collagen1 mRNA and actin reorganization in HSCs from wild-type mice but not mice lacking inflammasome components. MSU crystals inhibited the release of Ca(2+) via IP(3) in LX-2 cells and also inhibited PDGF-induced chemotaxis. Mice lacking the inflammasome-sensing and adaptor molecules, NLRP3 and apoptosis-associated speck-like protein containing CARD, had reduced CCl(4) and TAA-induced liver fibrosis. We concluded that inflammasome components are present in HSC, can regulate a variety of HSC functions, and are required for the development of liver fibrosis.
Department of Digestive Disease, Yale Univ., 1080 LMP, PO Box 208019, New Haven, CT 06520-8019, USA.
Azuma
A
Watanabe
Muhammad Adnan
MA
Sohail
Dawidson Assis
DA
Gomes
Ardeshir
A
Hashmi
Jun
J
Nagata
Fayyaz Shiraz
FS
Sutterwala
Shamail
S
Mahmood
Muhammad Nauman
MN
Jhandier
Yan
Y
Shi
Richard Anthony
RA
Flavell
Wajahat Zafar
WZ
Mehal
D000199:Actins / Q000378:metabolism; D000818:Animals; D051017:Apoptosis Regulatory Proteins; D053468:CARD Signaling Adaptor Proteins; D020013:Calcium Signaling / Q000187:drug effects; D002251:Carbon Tetrachloride / Q000494:pharmacology; D002352:Carrier Proteins / Q000235:genetics; D002461:Cell Line, Transformed; D002633:Chemotaxis / Q000187:drug effects / Q000235:genetics; D024042:Collagen Type I / Q000235:genetics; D003598:Cytoskeletal Proteins / Q000235:genetics; D015870:Gene Expression / Q000187:drug effects / Q000235:genetics; D055166:Hepatic Stellate Cells / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D007249:Inflammation / Q000139:chemically induced / Q000378:metabolism / Q000503:physiopathology*; D015544:Inositol 1,4,5-Trisphosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D008099:Liver / Q000378:metabolism / Q000473:pathology; D008103:Liver Cirrhosis / Q000139:chemically induced / Q000209:etiology / Q000378:metabolism / Q000473:pathology; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D000071199:NLR Family, Pyrin Domain-Containing 3 Protein; D010982:Platelet-Derived Growth Factor / Q000494:pharmacology; D013853:Thioacetamide / Q000494:pharmacology; D016212:Transforming Growth Factor beta / Q000235:genetics; D014527:Uric Acid / Q000494:pharmacology
C558396:Acta2 protein, mouse; D000199:Actins; D051017:Apoptosis Regulatory Proteins; D053468:CARD Signaling Adaptor Proteins; D002352:Carrier Proteins; D024042:Collagen Type I; D003598:Cytoskeletal Proteins; D000071199:NLR Family, Pyrin Domain-Containing 3 Protein; C453881:NLRP3 protein, human; C492716:Nlrp3 protein, mouse; C402202:PYCARD protein, human; D010982:Platelet-Derived Growth Factor; C498534:Pycard protein, mouse; D016212:Transforming Growth Factor beta; D013853:Thioacetamide; C061868:inositol 1,4,5-trisphosphate 1-(2-nitrophenyl)ethyl ester; D014527:Uric Acid; D015544:Inositol 1,4,5-Trisphosphate; D002251:Carbon Tetrachloride