Barbora Konecna1, Jinbong Park, Woon-Yong Kwon, Barbora Vlkova, Quanzhi Zhang, Wei Huang, Hyo In Kim, Michael B Yaffe, Leo E Otterbein, Kiyoshi Itagaki, Carl J Hauser. 1. From the Institute of Molecular Biomedicine (B.K., B.V.), Comenius University, Bratislava, Slovakia; Department of Surgery (J.P., W.H., H.I.K., M.B.Y., L.E.O., K.I., C.J.H.), Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachussets; Department of Emergency Medicine (W-.Y.K.), Seoul National University College of Medicine Seoul, Korea; College of Nursing (Q.Z.), Harbin Medical School, Daqing, China; and Departments of Biology and Biological Engineering (M.B.Y.), Massachusetts Institute of Technology, Boston, Massachussets.
Abstract
BACKGROUND: Trauma and sepsis both increase the risk for secondary infections. Injury mobilizes mitochondrial (MT) danger-associated molecular patterns (mtDAMPs) directly from cellular necrosis. It is unknown, however, whether sepsis can cause active MT release and whether mtDAMPs released by sepsis might affect innate immunity. METHODS: Mitochondrial release from human monocytes (Mo) was studied after LPS stimulation using electron microscopy and using fluorescent video-microscopy of adherent Mo using Mito-Tracker Green (MTG) dye. Release of MTG+ microparticles was studied using flow cytometry after bacterial stimulation by size exclusion chromatography of supernatants with polymerase chain reaction (PCR) for mitochondrial DNA (mtDNA). Human neutrophil (PMN), chemotaxis, and respiratory burst were studied after PMN incubation with mtDNA. RESULTS: LPS caused Mo to release mtDAMPs. Electron microscopy showed microparticles containing MT. mtDNA was present both in microvesicles and exosomes as shown by PCR of the relevant size exclusion chromatography bands. In functional studies, PMN incubation with mtDNA suppressed chemotaxis in a dose-dependent manner, which was reversed by chloroquine, suggesting an endosomal, toll-like receptor-9-dependent mechanism. In contrast, PMN respiratory burst was unaffected by mtDNA. CONCLUSION: In addition to passive release of mtDAMPs by traumatic cellular disruption, inflammatory and infectious stimuli cause active mtDAMP release via microparticles. mtDNA thus released can have effects on PMN that may suppress antimicrobial function. mtDAMP-mediated "feed-forward" mechanisms may modulate immune responses and potentially be generalizable to other forms of inflammation. Where they cause immune dysfunction the effects can be mitigated if the pathways by which the mtDAMPs act are defined. In this case, the endosomal inhibitor chloroquine is benign and well tolerated. Thus, it may warrant study as a prophylactic antiinfective after injury or prior sepsis.
BACKGROUND:Trauma and sepsis both increase the risk for secondary infections. Injury mobilizes mitochondrial (MT) danger-associated molecular patterns (mtDAMPs) directly from cellular necrosis. It is unknown, however, whether sepsis can cause active MT release and whether mtDAMPs released by sepsis might affect innate immunity. METHODS: Mitochondrial release from human monocytes (Mo) was studied after LPS stimulation using electron microscopy and using fluorescent video-microscopy of adherent Mo using Mito-Tracker Green (MTG) dye. Release of MTG+ microparticles was studied using flow cytometry after bacterial stimulation by size exclusion chromatography of supernatants with polymerase chain reaction (PCR) for mitochondrial DNA (mtDNA). Human neutrophil (PMN), chemotaxis, and respiratory burst were studied after PMN incubation with mtDNA. RESULTS:LPS caused Mo to release mtDAMPs. Electron microscopy showed microparticles containing MT. mtDNA was present both in microvesicles and exosomes as shown by PCR of the relevant size exclusion chromatography bands. In functional studies, PMN incubation with mtDNA suppressed chemotaxis in a dose-dependent manner, which was reversed by chloroquine, suggesting an endosomal, toll-like receptor-9-dependent mechanism. In contrast, PMN respiratory burst was unaffected by mtDNA. CONCLUSION: In addition to passive release of mtDAMPs by traumatic cellular disruption, inflammatory and infectious stimuli cause active mtDAMP release via microparticles. mtDNA thus released can have effects on PMN that may suppress antimicrobial function. mtDAMP-mediated "feed-forward" mechanisms may modulate immune responses and potentially be generalizable to other forms of inflammation. Where they cause immune dysfunction the effects can be mitigated if the pathways by which the mtDAMPs act are defined. In this case, the endosomal inhibitor chloroquine is benign and well tolerated. Thus, it may warrant study as a prophylactic antiinfective after injury or prior sepsis.
Authors: Saverio Marchi; Emma Guilbaud; Stephen W G Tait; Takahiro Yamazaki; Lorenzo Galluzzi Journal: Nat Rev Immunol Date: 2022-07-25 Impact factor: 108.555
Authors: Ghee Rye Lee; David Gallo; Rodrigo W Alves de Souza; Shilpa Tiwari-Heckler; Eva Csizmadia; James D Harbison; Sidharth Shankar; Valerie Banner-Goodspeed; Michael B Yaffe; Maria Serena Longhi; Carl J Hauser; Leo E Otterbein Journal: JCI Insight Date: 2021-10-22