Shiga Toxins Activate the NLRP3 Inflammasome Pathway To Promote Both Production of the Proinflammatory Cytokine Interleukin-1β and Apoptotic Cell Death.
Shiga toxin (Stx)-mediated immune responses, including the production of the proinflammatory cytokines tumor necrosis-α (TNF-α) and interleukin-1β (IL-1β), may exacerbate vascular damage and accelerate lethality. However, the immune signaling pathway activated in response to Stx is not well understood. Here, we demonstrate that enzymatically active Stx, which leads to ribotoxic stress, triggers NLRP3 inflammasome-dependent caspase-1 activation and IL-1β secretion in differentiated macrophage-like THP-1 (D-THP-1) cells. The treatment of cells with a chemical inhibitor of glycosphingolipid biosynthesis, which suppresses the expression of the Stx receptor globotriaosylceramide and subsequent endocytosis of the toxin, substantially blocked activation of the NLRP3 inflammasome and processing of caspase-1 and IL-1β. Processing and release of both caspase-1 and IL-1β were significantly reduced or abolished in Stx-intoxicated D-THP-1 cells in which the expression of NLRP3 or ASC was stably knocked down. Furthermore, Stx mediated the activation of caspases involved in apoptosis in an NLRP3- or ASC-dependent manner. In Stx-intoxicated cells, the NLRP3 inflammasome triggered the activation of caspase-8/3, leading to the initiation of apoptosis, in addition to caspase-1-dependent pyroptotic cell death. Taken together, these results suggest that Stxs trigger the NLRP3 inflammasome pathway to release proinflammatory IL-1β as well as to promote apoptotic cell death.
Infection and Immunity Research Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon, South Korea.
Moo-Seung
MS
Lee
Infection and Immunity Research Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon, South Korea.
Haenaem
H
Kwon
Infection and Immunity Research Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon, South Korea.
Eun-Young
EY
Lee
Division of Drug Screening and Evaluation, New Drug Development Center, Osong Medical Innovation Foundation, Cheongju, Chungbuk, South Korea.
Dong-Jae
DJ
Kim
College of Veterinary Medicine, Chonnam National University, Gwangju, South Korea.
Jong-Hwan
JH
Park
Department of Microbial Pathogenesis and Immunology, Texas A&M University Health Science Center, Bryan, Texas, USA.
Vernon L
VL
Tesh
Infection and Immunity Research Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon, South Korea.
Tae-Kwang
TK
Oh
Infection and Immunity Research Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon, South Korea mhk8n@kribb.re.kr.
Myung Hee
MH
Kim
D053468:CARD Signaling Adaptor Proteins / Q000235:genetics / Q000276:immunology; D002135:Calcium-Binding Proteins / Q000235:genetics / Q000276:immunology; D002352:Carrier Proteins / Q000235:genetics / Q000276:immunology*; D020170:Caspase 1 / Q000235:genetics / Q000276:immunology*; D053148:Caspase 3 / Q000276:immunology; D053181:Caspase 8 / Q000276:immunology; D045744:Cell Line, Tumor; D003598:Cytoskeletal Proteins / Q000235:genetics / Q000276:immunology; D004268:DNA-Binding Proteins / Q000235:genetics / Q000276:immunology; D004789:Enzyme Activation / Q000276:immunology; D006028:Glycosphingolipids / Q000096:biosynthesis; D006801:Humans; D007249:Inflammation / Q000276:immunology; D053583:Interleukin-1beta / Q000096:biosynthesis* / Q000276:immunology / Q000378:metabolism; D000071199:NLR Family, Pyrin Domain-Containing 3 Protein; D000069292:Pyroptosis / Q000276:immunology*; D034622:RNA Interference; D034741:RNA, Small Interfering; D022603:Shiga Toxins / Q000276:immunology*; D054323:Shiga-Toxigenic Escherichia coli / Q000378:metabolism; D015398:Signal Transduction / Q000276:immunology; D014281:Trihexosylceramides / Q000096:biosynthesis; D014409:Tumor Necrosis Factor-alpha / Q000276:immunology
C410167:AIM2 protein, human; D053468:CARD Signaling Adaptor Proteins; D002135:Calcium-Binding Proteins; D002352:Carrier Proteins; D003598:Cytoskeletal Proteins; D004268:DNA-Binding Proteins; D006028:Glycosphingolipids; C508585:IL1B protein, human; D053583:Interleukin-1beta; D000071199:NLR Family, Pyrin Domain-Containing 3 Protein; C435692:NLRC4 protein, human; C453881:NLRP3 protein, human; C402202:PYCARD protein, human; D034741:RNA, Small Interfering; D022603:Shiga Toxins; D014281:Trihexosylceramides; D014409:Tumor Necrosis Factor-alpha; C018549:globotriaosylceramide; D053148:Caspase 3; D053181:Caspase 8; D020170:Caspase 1