Metabolic Remodeling, Inflammasome Activation, and Pyroptosis in Macrophages Stimulated by Porphyromonas gingivalis and Its Outer Membrane Vesicles

Frontiers in Cellular and Infection Microbiology

Achuthan, Adrian¹  Lee, Ming-Chin¹  Brien-Simpson, Neil M.¹  Reynolds, Eric C.¹  Fleetwood, Andrew J.¹  Lee, Man K.S.²  Cook, Andrew D.²  Murphy, Andrew J.³  Dashper, Stuart G.³  O'³  Singleton, William³ 

[1] Department of Medicine, University of Melbourne, Royal Melbourne Hospital, Parkville, VIC, Australia;Haematopoiesis and Leukocyte Biology, Baker Heart and Diabetes Institute, Melbourne, VIC, Australia;Oral Health Cooperative Research Centre, Melbourne Dental School, Bio21 Institute, University of Melbourne, VIC, Australia

关键词: Macrophages;    Metabolism;    Inflammasome;    P. gingivalis;    vesicles;    pyroptosis;    Cytokines;    inflammation;    glycolysis;    oxidative phosphorylation;   

DOI  :  10.3389/fcimb.2017.00351

学科分类：生物科学（综合）

来源: Frontiers

【 摘 要 】

Porphyromonas gingivalis is one of the bacterial species most closely associated with periodontitis and can shed large numbers of outer membrane vesicles (OMVs), which are increasingly thought to play a significant role in bacterial virulence and pathogenicity. Macrophages are amongst the first immune cells to respond to bacteria and their products, so we sought to directly compare the response of macrophages to P. gingivalis or its purified OMVs. Macrophages stimulated with OMVs produced large amounts of TNF, IL-12p70, IL-6, IL-10, IFN and nitric oxide compared to cells infected with P. gingivalis, which produced very low levels of these mediators. Both P. gingivalis and OMVs induced a shift in macrophage metabolism from oxidative phosphorylation (OXPHOS) to glycolysis, which was supported by enhanced lactate release, decreased mitochondrial oxygen consumption with reduced spare respiratory capacity, as well as increased mitochondrial reactive oxygen species (ROS) production. Corresponding to this metabolic shift, gene expression analysis of macrophages infected with P. gingivalis or stimulated with OMVs revealed a broad transcriptional upregulation of genes critical to glycolysis and a downregulation of genes associated with the TCA cycle. Upon examination of inflammasome signalling and pyroptosis it was found that P. gingivalis did not activate the inflammasome in macrophages as the mature forms of caspase-1, IL-1β and IL-18 were not detected and there was no extracellular release of lactate dehydrogenase (LDH) or 7-AAD staining. In comparison, macrophages stimulated with OMVs potently activated caspase-1, produced large amounts of IL-1β, IL-18, released LDH and were positive for 7-AAD indicative of pyroptotic cell death. These data directly quantitate the distinct effects of P. gingivalis and its OMVs on macrophage inflammatory phenotype, mitochondrial function, inflammasome activation and pyroptotic cell death that may have potential implications for their roles in chronic periodontitis.

【 授权许可】

CC BY