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Yao R, Chen Y, Hao H, Guo Z, Cheng X, Ma Y, Ji Q, Yang X, Wang Y, Li X, Wang Z. Pathogenic effects of inhibition of mTORC1/STAT3 axis facilitates Staphylococcus aureus-induced pyroptosis in human macrophages. Cell Commun Signal 2020; 18:187. [PMID: 33256738 PMCID: PMC7706204 DOI: 10.1186/s12964-020-00677-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Accepted: 10/26/2020] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND Pyroptosis is a recently identified pathway of caspase-mediated cell death in response to microbes, lipopolysaccharide, or chemotherapy in certain types of cells. However, the mechanism of how pyroptosis is regulated is not well-established. METHODS Herein, the intracellular bacteria were detected by staining and laser confocal microscopy and TEM. Live/dead cell imaging assay was used to examine macrophage death. Western blot and immunohistochemical staining were used to examine the protein changes. IFA was used to identify typical budding vesicles of pyroptosis and the STAT3 nuclear localization. SEM was used to observe the morphological characteristics of pyroptosis. ELISA was used to detect the level of inflammatory cytokines. Pyroptosis was filmed in macrophages by LSCM. RESULTS S. aureus was internalized by human macrophages. Intracellular S. aureus induced macrophage death. S. aureus invasion increased the expression of NLRP3, Caspase1 (Casp-1 p20) and the accumulation of GSDMD-NT, GSDMD-NT pore structures, and the release of IL-1β and IL-18 in macrophages. Macrophages pyroptosis induced by S. aureus can be abrogated by blockage of S. aureus phagocytosis. The pyroptosic effect by S. aureus infection was promoted by either rapamycin or Stattic, a specific inhibitor for mTORC1 or STAT3. Inhibition of mTORC1 or STAT3 induced pyroptosis. mTORC1 regulated the pyroptosic gene expression through governing the nuclear localization of STAT3. mTORC1/STAT3 axis may play a regulatory role in pyroptosis within macrophages. CONCLUSIONS S. aureus infection induces human macrophage pyroptosis, inhibition of mTORC1/STAT3 axis facilitates S. aureus-induced pyroptosis. mTORC1 and STAT3 are associated with pyroptosis. Our findings demonstrate a regulatory function of the mTORC1/STAT3 axis in macrophage pyroptosis, constituting a novel mechanism by which pyroptosis is regulated in macrophages. Video Abstract Macrophages were infected with S. aureus for 3 h (MOI 25:1), and pyroptosis was filmed in macrophages by laser confocal microscopy. A representative field was recorded. Arrow indicates lysing dead cell.
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Affiliation(s)
- Ruiyuan Yao
- State Key Laboratory of Reproductive Regulation and Breeding of Grassland Livestock, School of Life Sciences, Inner Mongolia University, Hohhot, 010070, China
| | - Yuhao Chen
- State Key Laboratory of Reproductive Regulation and Breeding of Grassland Livestock, School of Life Sciences, Inner Mongolia University, Hohhot, 010070, China.,School of Life Sciences, Jining Normal University, Jining, 012000, China
| | - Huifang Hao
- State Key Laboratory of Reproductive Regulation and Breeding of Grassland Livestock, School of Life Sciences, Inner Mongolia University, Hohhot, 010070, China
| | - Zhixin Guo
- State Key Laboratory of Reproductive Regulation and Breeding of Grassland Livestock, School of Life Sciences, Inner Mongolia University, Hohhot, 010070, China
| | - Xiaoou Cheng
- State Key Laboratory of Reproductive Regulation and Breeding of Grassland Livestock, School of Life Sciences, Inner Mongolia University, Hohhot, 010070, China
| | - Yuze Ma
- State Key Laboratory of Reproductive Regulation and Breeding of Grassland Livestock, School of Life Sciences, Inner Mongolia University, Hohhot, 010070, China
| | - Qiang Ji
- State Key Laboratory of Reproductive Regulation and Breeding of Grassland Livestock, School of Life Sciences, Inner Mongolia University, Hohhot, 010070, China
| | - Xiaoru Yang
- State Key Laboratory of Reproductive Regulation and Breeding of Grassland Livestock, School of Life Sciences, Inner Mongolia University, Hohhot, 010070, China
| | - Yanfeng Wang
- State Key Laboratory of Reproductive Regulation and Breeding of Grassland Livestock, School of Life Sciences, Inner Mongolia University, Hohhot, 010070, China
| | - Xihe Li
- State Key Laboratory of Reproductive Regulation and Breeding of Grassland Livestock, School of Life Sciences, Inner Mongolia University, Hohhot, 010070, China. .,Research Center for Animal Genetic Resources of Mongolia Plateau, Inner Mongolia University, Hohhot, 010070, China.
| | - Zhigang Wang
- State Key Laboratory of Reproductive Regulation and Breeding of Grassland Livestock, School of Life Sciences, Inner Mongolia University, Hohhot, 010070, China.
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Speir M, Lawlor KE. RIP-roaring inflammation: RIPK1 and RIPK3 driven NLRP3 inflammasome activation and autoinflammatory disease. Semin Cell Dev Biol 2020; 109:114-124. [PMID: 32771377 DOI: 10.1016/j.semcdb.2020.07.011] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2020] [Revised: 07/13/2020] [Accepted: 07/16/2020] [Indexed: 01/05/2023]
Abstract
Autoinflammatory syndromes comprise a spectrum of clinical disorders characterised by recurrent, inflammatory episodes, many of which result from the release of the pro-inflammatory cytokine, interleukin-1β (IL-1β). Inflammation and programmed cell death are tightly linked, and lytic forms of cell death, such as necroptosis and pyroptosis, are considered to be inflammatory due to the release of damage-associated molecular patterns (DAMPs). In contrast, apoptosis is traditionally regarded as immunologically silent. Recent studies, however, have uncovered a high degree of crosstalk between cell death and inflammatory signalling pathways, and effectively consolidated them into one interconnected network that converges on NLRP3 inflammasome-mediated activation of IL-1β. The receptor-interacting protein kinases (RIPK) 1 and 3 are central to this network, as highlighted by the fact that mutations in genes encoding repressors of RIPK1 and/or RIPK3 activity can lead to heightened inflammation, particularly via NLRP3 inflammasome activation. In this review, we give an overview of extrinsic cell death and inflammatory signalling pathways, and then highlight the growing number of autoinflammatory diseases that are associated with aberrant cell death and inflammasome activation.
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Affiliation(s)
- Mary Speir
- Centre for Innate Immunity and Infectious Diseases, Hudson Institute of Medical Research, Melbourne, Victoria, Australia; Department of Molecular and Translational Science, Monash University, Melbourne, Victoria, Australia.
| | - Kate E Lawlor
- Centre for Innate Immunity and Infectious Diseases, Hudson Institute of Medical Research, Melbourne, Victoria, Australia; Department of Molecular and Translational Science, Monash University, Melbourne, Victoria, Australia.
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Burgener SS, Leborgne NGF, Snipas SJ, Salvesen GS, Bird PI, Benarafa C. Cathepsin G Inhibition by Serpinb1 and Serpinb6 Prevents Programmed Necrosis in Neutrophils and Monocytes and Reduces GSDMD-Driven Inflammation. Cell Rep 2020; 27:3646-3656.e5. [PMID: 31216481 DOI: 10.1016/j.celrep.2019.05.065] [Citation(s) in RCA: 154] [Impact Index Per Article: 38.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2018] [Revised: 01/31/2019] [Accepted: 05/17/2019] [Indexed: 12/20/2022] Open
Abstract
Neutrophil granule serine proteases contribute to immune responses through cleavage of microbial toxins and structural proteins. They induce tissue damage and modulate inflammation if levels exceed their inhibitors. Here, we show that the intracellular protease inhibitors Serpinb1a and Serpinb6a contribute to monocyte and neutrophil survival in steady-state and inflammatory settings by inhibiting cathepsin G (CatG). Importantly, we found that CatG efficiently cleaved gasdermin D (GSDMD) to generate the signature N-terminal domain GSDMD-p30 known to induce pyroptosis. Yet GSDMD deletion did not rescue neutrophil survival in Sb1a.Sb6a-/- mice. Furthermore, Sb1a.Sb6a-/- mice released high levels of pro-inflammatory cytokines upon endotoxin challenge in vivo in a CatG-dependent manner. Canonical inflammasome activation in Sb1a.Sb6a-/- macrophages showed increased IL-1β release that was dependent on CatG and GSDMD. Together, our findings demonstrate that cytosolic serpins expressed in myeloid cells prevent cell death and regulate inflammatory responses by inhibiting CatG and alternative activation of GSDMD.
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Affiliation(s)
- Sabrina Sofia Burgener
- Institute of Virology and Immunology, 3147 Mittelhäusern, Switzerland; Department of Infectious Diseases and Pathobiology, Vetsuisse Faculty, University of Bern, 3012 Bern, Switzerland; Graduate School for Cellular and Biomedical Sciences, University of Bern, 3012 Bern, Switzerland
| | - Nathan Georges François Leborgne
- Institute of Virology and Immunology, 3147 Mittelhäusern, Switzerland; Department of Infectious Diseases and Pathobiology, Vetsuisse Faculty, University of Bern, 3012 Bern, Switzerland; Graduate School for Cellular and Biomedical Sciences, University of Bern, 3012 Bern, Switzerland
| | - Scott J Snipas
- Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA 92037, USA
| | - Guy S Salvesen
- Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA 92037, USA
| | - Phillip Ian Bird
- Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Melbourne, VIC 3800, Australia
| | - Charaf Benarafa
- Institute of Virology and Immunology, 3147 Mittelhäusern, Switzerland; Department of Infectious Diseases and Pathobiology, Vetsuisse Faculty, University of Bern, 3012 Bern, Switzerland.
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E. coli induced larger neutrophils in the peritoneal cavity of mice with severe septic peritonitis. Mol Immunol 2018; 105:86-95. [PMID: 30500625 DOI: 10.1016/j.molimm.2018.11.010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2018] [Revised: 10/23/2018] [Accepted: 11/14/2018] [Indexed: 12/26/2022]
Abstract
Neutrophils, classified as professional phagocytes, are crucial in killing bacteria and preventing inflammation. When studying the roles of neutrophils in the development of the septic peritonitis induced by E. coli, we noticed some of the larger cells existed among peritoneal lavage fluid cells (PLCs). Besides the large size, their nuclei are segmented and flat, and squeezed to the marginal zone of the inner membrane. The cells, therefore, were designated as E. coli induced larger neutrophils (e-Neus). Further studies showed that, the e-Neus were ly6G positive, indicating the e-Neus were a type of neutrophils. The enlarged cell size and marginal nucleus of the e-Neus were caused by engulfing abundant of E. coli, marking the active participation of the e-Neus in clearance of E. coli. Functionally, the e-Neus generated reactive oxygen species (ROS) and IL-10. Furthermore, the occurrence and accumulation of the e-Neus were closely correlated with the severity of septic peritonitis and mortality of the mice. Overall, the e-Neus presented here may enrich the understandings on neutrophil transitions in response to various insults, and could be used to evaluate the severity of septic peritonitis induced by E. coli.
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Abstract
Purpose: Fungal keratitis is a major cause of corneal ulcers, resulting in significant visual impairment and blindness. Fenretinide, a derivative of vitamin A, has been shown to suppress inflammation in a multitude of diseases. In this study, we aimed to characterize the effect of fenretinide in Aspergillus fumigatus keratitis of the eye in a mouse model. Methods: In vivo and in vitro experiments were performed in mouse models and THP-1 macrophage cell cultures infected with A. fumigatus, respectively. Experimental subjects were first pretreated with fenretinide, and then the effect of the compound was assessed with clinical evaluation, neutrophil staining, myeloperoxidase assay, quantitative polymerase chain reaction (qRT-PCR), and western blot. Results: We confirmed that fenretinide contributed to protection of corneal transparency during early mouse A. fumigatus keratitis by reducing neutrophil recruitment, decreasing myeloperoxidase (MPO) levels and increasing apoptosis. Compared with controls, fenretinide impaired proinflammatory cytokine interleukin 1 beta (IL-1β) production in response to A. fumigatus exposure with contributions by lectin-type oxidized LDL receptor 1 (LOX-1) and c-Jun N-terminal kinase (JNK). Conclusions: Together, these findings demonstrate that fenretinide may suppress inflammation through reduced neutrophil recruitment and inflammatory cytokine production in A. fumigatus keratitis.
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Petrie EJ, Hildebrand JM, Murphy JM. Insane in the membrane: a structural perspective of MLKL function in necroptosis. Immunol Cell Biol 2017; 95:152-159. [DOI: 10.1038/icb.2016.125] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2016] [Revised: 10/31/2016] [Accepted: 10/31/2016] [Indexed: 12/28/2022]
Affiliation(s)
- Emma J Petrie
- Cell Signalling and Cell Death Division, Walter and Eliza Hall Institute of Medical Research Parkville Victoria Australia
- Department of Medical Biology, University of Melbourne Parkville Victoria Australia
| | - Joanne M Hildebrand
- Cell Signalling and Cell Death Division, Walter and Eliza Hall Institute of Medical Research Parkville Victoria Australia
- Department of Medical Biology, University of Melbourne Parkville Victoria Australia
| | - James M Murphy
- Cell Signalling and Cell Death Division, Walter and Eliza Hall Institute of Medical Research Parkville Victoria Australia
- Department of Medical Biology, University of Melbourne Parkville Victoria Australia
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