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Wang J, Hu L, Zhang Z, Sui C, Zhu X, Wu C, Zhang L, Lv M, Yang W, Zhou D, Shang Z. Mice fatal pneumonia model induced by less-virulent Streptococcus pneumoniae via intratracheal aerosolization. Future Microbiol 2024:1-16. [PMID: 38913747 DOI: 10.1080/17460913.2024.2355738] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2023] [Accepted: 05/10/2024] [Indexed: 06/26/2024] Open
Abstract
Aim: Animal models of fatal pneumonia caused by Streptococcus pneumoniae (Spn) have not been reliably generated using many strains of less virulent serotypes. Materials & methods: Pulmonary infection of a less virulent Spn serotype1 strain in the immunocompetent mice was established via the intratracheal aerosolization (ITA) route. The survival, local and systemic bacterial spread, pathological changes and inflammatory responses of this model were compared with those of mice challenged via the intratracheal instillation, intranasal instillation and intraperitoneal injection routes. Results: ITA and intratracheal instillation both induced fatal pneumonia; however, ITA resulted in better lung bacterial deposition and distribution, pathological homogeneity and delivery efficiency. Conclusion: ITA is an optimal route for developing animal models of severe pulmonary infections.
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Affiliation(s)
- Jiazhen Wang
- Department of Immunology of Basic Medical College, Guizhou Medical University, Guian New Area, 561113, China
- State Key Laboratory of Pathogen & Biosecurity, Beijing Institute of Microbiology & Epidemiology, Academy of Military Medical Sciences, Beijing, 100071, China
| | - Lingfei Hu
- State Key Laboratory of Pathogen & Biosecurity, Beijing Institute of Microbiology & Epidemiology, Academy of Military Medical Sciences, Beijing, 100071, China
| | - Zhijun Zhang
- State Key Laboratory of Pathogen & Biosecurity, Beijing Institute of Microbiology & Epidemiology, Academy of Military Medical Sciences, Beijing, 100071, China
| | - Chengyu Sui
- State Key Laboratory of Pathogen & Biosecurity, Beijing Institute of Microbiology & Epidemiology, Academy of Military Medical Sciences, Beijing, 100071, China
- Department of Microbiology of Basic Medical College, Anhui Medical University, Hefei, 230032, China
| | - Xiaoyu Zhu
- State Key Laboratory of Pathogen & Biosecurity, Beijing Institute of Microbiology & Epidemiology, Academy of Military Medical Sciences, Beijing, 100071, China
| | - Chengxi Wu
- State Key Laboratory of Pathogen & Biosecurity, Beijing Institute of Microbiology & Epidemiology, Academy of Military Medical Sciences, Beijing, 100071, China
| | - Lili Zhang
- State Key Laboratory of Pathogen & Biosecurity, Beijing Institute of Microbiology & Epidemiology, Academy of Military Medical Sciences, Beijing, 100071, China
| | - Meng Lv
- State Key Laboratory of Pathogen & Biosecurity, Beijing Institute of Microbiology & Epidemiology, Academy of Military Medical Sciences, Beijing, 100071, China
| | - Wenhui Yang
- State Key Laboratory of Pathogen & Biosecurity, Beijing Institute of Microbiology & Epidemiology, Academy of Military Medical Sciences, Beijing, 100071, China
| | - Dongsheng Zhou
- State Key Laboratory of Pathogen & Biosecurity, Beijing Institute of Microbiology & Epidemiology, Academy of Military Medical Sciences, Beijing, 100071, China
| | - Zhengling Shang
- Department of Immunology of Basic Medical College, Guizhou Medical University, Guian New Area, 561113, China
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Horner E, Lord JM, Hazeldine J. The immune suppressive properties of damage associated molecular patterns in the setting of sterile traumatic injury. Front Immunol 2023; 14:1239683. [PMID: 37662933 PMCID: PMC10469493 DOI: 10.3389/fimmu.2023.1239683] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2023] [Accepted: 07/31/2023] [Indexed: 09/05/2023] Open
Abstract
Associated with the development of hospital-acquired infections, major traumatic injury results in an immediate and persistent state of systemic immunosuppression, yet the underlying mechanisms are poorly understood. Detected in the circulation in the minutes, days and weeks following injury, damage associated molecular patterns (DAMPs) are a heterogeneous collection of proteins, lipids and DNA renowned for initiating the systemic inflammatory response syndrome. Suggesting additional immunomodulatory roles in the post-trauma immune response, data are emerging implicating DAMPs as potential mediators of post-trauma immune suppression. Discussing the results of in vitro, in vivo and ex vivo studies, the purpose of this review is to summarise the emerging immune tolerising properties of cytosolic, nuclear and mitochondrial-derived DAMPs. Direct inhibition of neutrophil antimicrobial activities, the induction of endotoxin tolerance in monocytes and macrophages, and the recruitment, activation and expansion of myeloid derived suppressor cells and regulatory T cells are examples of some of the immune suppressive properties assigned to DAMPs so far. Crucially, with studies identifying the molecular mechanisms by which DAMPs promote immune suppression, therapeutic strategies that prevent and/or reverse DAMP-induced immunosuppression have been proposed. Approaches currently under consideration include the use of synthetic polymers, or the delivery of plasma proteins, to scavenge circulating DAMPs, or to treat critically-injured patients with antagonists of DAMP receptors. However, as DAMPs share signalling pathways with pathogen associated molecular patterns, and pro-inflammatory responses are essential for tissue regeneration, these approaches need to be carefully considered in order to ensure that modulating DAMP levels and/or their interaction with immune cells does not negatively impact upon anti-microbial defence and the physiological responses of tissue repair and wound healing.
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Affiliation(s)
- Emily Horner
- Institute of Inflammation and Ageing, University of Birmingham, Birmingham, United Kingdom
| | - Janet M. Lord
- Institute of Inflammation and Ageing, University of Birmingham, Birmingham, United Kingdom
- National Institute for Health Research Surgical Reconstruction and Microbiology Research Centre, Queen Elizabeth Hospital Birmingham, Birmingham, United Kingdom
| | - Jon Hazeldine
- Institute of Inflammation and Ageing, University of Birmingham, Birmingham, United Kingdom
- National Institute for Health Research Surgical Reconstruction and Microbiology Research Centre, Queen Elizabeth Hospital Birmingham, Birmingham, United Kingdom
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Macáková K, Kaczmarek E, Itagaki K. Can Neutrophils Prevent Nosocomial Pneumonia after Serious Injury? Int J Mol Sci 2023; 24:ijms24087627. [PMID: 37108790 PMCID: PMC10141656 DOI: 10.3390/ijms24087627] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2023] [Revised: 04/11/2023] [Accepted: 04/18/2023] [Indexed: 04/29/2023] Open
Abstract
Nosocomial pneumonia is a leading cause of critical illness and mortality among seriously injured trauma patients. However, the link between injury and the development of nosocomial pneumonia is still not well recognized. Our work strongly suggests that mitochondrial damage-associated molecular patterns (mtDAMPs), especially mitochondrial formyl peptides (mtFPs) released by tissue injury, play a significant role in developing nosocomial pneumonia after a serious injury. Polymorphonuclear leukocytes (neutrophils, PMN) migrate toward the injury site by detecting mtFPs through formyl peptide receptor 1 (FPR1) to fight/contain bacterial infection and clean up debris. Activation of FPR1 by mtFPs enables PMN to reach the injury site; however, at the same time it leads to homo- and heterologous desensitization/internalization of chemokine receptors. Thus, PMN are not responsive to secondary infections, including those from bacteria-infected lungs. This may enable a progression of bacterial growth in the lungs and nosocomial pneumonia. We propose that the intratracheal application of exogenously isolated PMN may prevent pneumonia coupled with a serious injury.
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Affiliation(s)
- Kristína Macáková
- Department of Surgery, Beth Israel Deaconess Medical Center/Harvard Medical School, Boston, MA 02215, USA
- Institute of Molecular Biomedicine, Faculty of Medicine, Comenius University, Sasinkova 4, 811 08 Bratislava, Slovakia
| | - Elzbieta Kaczmarek
- Department of Surgery, Beth Israel Deaconess Medical Center/Harvard Medical School, Boston, MA 02215, USA
| | - Kiyoshi Itagaki
- Department of Surgery, Beth Israel Deaconess Medical Center/Harvard Medical School, Boston, MA 02215, USA
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Tiwari-Heckler S, Lee GR, Harbison J, Ledderose C, Csizmadia E, Melton D, Zhang Q, Junger W, Chen G, Hauser CJ, Otterbein LE, Longhi MS, Robson SC. Extracellular mitochondria drive CD8 T cell dysfunction in trauma by upregulating CD39. Thorax 2023; 78:151-159. [PMID: 35613855 PMCID: PMC9691787 DOI: 10.1136/thoraxjnl-2021-218047] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Accepted: 04/04/2022] [Indexed: 01/21/2023]
Abstract
RATIONALE The increased mortality and morbidity seen in critically injured patients appears associated with systemic inflammatory response syndrome (SIRS) and immune dysfunction, which ultimately predisposes to infection. Mitochondria released by injury could generate danger molecules, for example, ATP, which in turn would be rapidly scavenged by ectonucleotidases, expressed on regulatory immune cells. OBJECTIVE To determine the association between circulating mitochondria, purinergic signalling and immune dysfunction after trauma. METHODS We tested the impact of hepatocyte-derived free mitochondria on blood-derived and lung-derived CD8 T cells in vitro and in experimental mouse models in vivo. In parallel, immune phenotypic analyses were conducted on blood-derived CD8 T cells obtained from trauma patients. RESULTS Isolated intact mitochondria are functional and generate ATP ex vivo. Extracellular mitochondria perturb CD8+ T cells in co-culture, inducing select features of immune exhaustion in vitro. These effects are modulated by scavenging ATP, modelled by addition of apyrase in vitro. Injection of intact mitochondria into recipient mice markedly upregulates the ectonucleotidase CD39, and other immune checkpoint markers in circulating CD8+ T cells. We note that mice injected with mitochondria, prior to instilling bacteria into the lung, exhibit more severe lung injury, characterised by elevated neutrophil influx and by changes in CD8+ T cell cytotoxic capacity. Importantly, the development of SIRS in injured humans, is likewise associated with disordered purinergic signalling and CD8 T cell dysfunction. CONCLUSION These studies in experimental models and in a cohort of trauma patients reveal important associations between extracellular mitochondria, aberrant purinergic signalling and immune dysfunction. These pathogenic factors with immune exhaustion are linked to SIRS and could be targeted therapeutically.
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Affiliation(s)
- Shilpa Tiwari-Heckler
- Gastroenterology, University Hospital Heidelberg Medical Clinic, Heidelberg, Germany.,Center for Inflammation Research, Department of Anesthesia, Critical Care and Pain Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, USA.,Division of Gastroenterology, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, USA
| | - Ghee Rye Lee
- Department of Surgery, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, USA
| | - James Harbison
- Department of Surgery, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, USA
| | - Carola Ledderose
- Department of Surgery, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, USA
| | - Eva Csizmadia
- Department of Surgery, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, USA
| | - David Melton
- Center for Inflammation Research, Department of Anesthesia, Critical Care and Pain Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, USA
| | | | - Wolfgang Junger
- Department of Surgery, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, USA
| | - Guanqing Chen
- Center for Inflammation Research, Department of Anesthesia, Critical Care and Pain Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, USA
| | - Carl J Hauser
- Department of Surgery, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, USA
| | - Leo E Otterbein
- Department of Surgery, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, USA
| | - Maria Serena Longhi
- Center for Inflammation Research, Department of Anesthesia, Critical Care and Pain Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, USA
| | - Simon Christopher Robson
- Center for Inflammation Research, Department of Anesthesia, Critical Care and Pain Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, USA .,Division of Gastroenterology, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, USA
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5
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Itagaki K, Riça I, Konecna B, Kim HI, Park J, Kaczmarek E, Hauser CJ. Role of Mitochondria-Derived Danger Signals Released After Injury in Systemic Inflammation and Sepsis. Antioxid Redox Signal 2021; 35:1273-1290. [PMID: 33847158 PMCID: PMC8905257 DOI: 10.1089/ars.2021.0052] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Significance: Sepsis is a major public health concern, with high mortality and morbidity, especially among patients undergoing trauma. It is characterized by a systemic inflammatory response syndrome (SIRS) occurring in response to infection. Although classically associated with pathogens, many patients with SIRS do not have infection. The variability of the disease course cannot be fully explained by our current understanding of its pathogenesis. Thus, other factors are likely to play key roles in the development and progression of SIRS/sepsis. Recent Advances: Circulating levels of damage-associated molecular patterns (DAMPs) seem to correlate with SIRS/sepsis morbidity and mortality. Of the known DAMPs, those of mitochondrial (mt) origin have been of particular interest, since their DNA (mtDNA) and formyl peptides (mtFPs) resemble bacterial DNA and peptides, and hence, when released, may be recognized as "danger signals." Critical Issues: mtDAMPs released after tissue injury trigger immune responses similar to those induced by pathogens. Thus, they can result in systemic inflammation and organ damage, similar to that observed in SIRS/sepsis. We will discuss recent findings on the roles of mtDAMPs, particularly regarding the less recognized mtFPs, in the activation of inflammatory responses and development of SIRS/sepsis. Future Directions: There are no established methods to predict the course of SIRS/sepsis, but clinical studies reveal that plasma levels of mtDAMPs may correlate with the outcome of the disease. We propose that non-pathogen-initiated, mtDAMPs-induced SIRS/sepsis events need further studies aimed at early clinical recognition and better treatment of this disease.
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Affiliation(s)
- Kiyoshi Itagaki
- Department of Surgery, Beth Israel Deaconess Medical Center/Harvard Medical School, Boston, Massachusetts, USA
| | - Ingred Riça
- The David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Barbora Konecna
- Institute of Molecular Biomedicine, Comenius University, Bratislava, Slovakia
| | - Hyo In Kim
- Department of Surgery, Beth Israel Deaconess Medical Center/Harvard Medical School, Boston, Massachusetts, USA
| | - Jinbong Park
- Department of Surgery, Beth Israel Deaconess Medical Center/Harvard Medical School, Boston, Massachusetts, USA
| | - Elzbieta Kaczmarek
- Department of Surgery, Beth Israel Deaconess Medical Center/Harvard Medical School, Boston, Massachusetts, USA.,Center for Vascular Biology Research, Beth Israel Deaconess Medical Center/Harvard Medical School, Boston, Massachusetts, USA
| | - Carl J Hauser
- Department of Surgery, Beth Israel Deaconess Medical Center/Harvard Medical School, Boston, Massachusetts, USA
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Ng J, Guo F, Marneth AE, Ghanta S, Kwon MY, Keegan J, Liu X, Wright KT, Kamaz B, Cahill LA, Mullally A, Perrella MA, Lederer JA. Augmenting emergency granulopoiesis with CpG conditioned mesenchymal stromal cells in murine neutropenic sepsis. Blood Adv 2020; 4:4965-4979. [PMID: 33049055 PMCID: PMC7556132 DOI: 10.1182/bloodadvances.2020002556] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2020] [Accepted: 09/02/2020] [Indexed: 12/17/2022] Open
Abstract
Patients with immune deficiencies from cancers and associated treatments represent a growing population within the intensive care unit with increased risk of morbidity and mortality from sepsis. Mesenchymal stromal cells (MSCs) are an integral part of the hematopoietic niche and express toll-like receptors, making them candidate cells to sense and translate pathogenic signals into an innate immune response. In this study, we demonstrate that MSCs administered therapeutically in a murine model of radiation-associated neutropenia have dual actions to confer a survival benefit in Pseudomonas aeruginosa pneumo-sepsis that is not from improved bacterial clearance. First, MSCs augment the neutrophil response to infection, an effect that is enhanced when MSCs are preconditioned with CpG oligodeoxynucleotide, a toll-like receptor 9 agonist. Using cytometry by time of flight, we identified proliferating neutrophils (Ly6GlowKi-67+) as the main expanded cell population within the bone marrow. Further analysis revealed that CpG-MSCs expand a lineage restricted progenitor population (Lin-Sca1+C-kit+CD150-CD48+) in the bone marrow, which corresponded to a doubling in the myeloid proliferation and differentiation potential in response to infection compared with control. Despite increased neutrophils, no reduction in organ bacterial count was observed between experimental groups. However, the second effect exerted by CpG-MSCs is to attenuate organ damage, particularly in the lungs. Neutrophils obtained from irradiated mice and cocultured with CpG-MSCs had decreased neutrophil extracellular trap formation, which was associated with decreased citrullinated H3 staining in the lungs of mice given CpG-MSCs in vivo. Thus, this preclinical study provides evidence for the therapeutic potential of MSCs in neutropenic sepsis.
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Affiliation(s)
- Julie Ng
- Division of Pulmonary and Critical Care, Department of Medicine
| | | | | | | | - Min-Young Kwon
- Division of Pulmonary and Critical Care, Department of Medicine
| | | | - Xiaoli Liu
- Division of Pulmonary and Critical Care, Department of Medicine
- Department of Pediatric Newborn Medicine, and
| | - Kyle T Wright
- Department of Pathology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA
| | | | | | | | - Mark A Perrella
- Division of Pulmonary and Critical Care, Department of Medicine
- Department of Pediatric Newborn Medicine, and
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Itagaki K, Kaczmarek E, Kwon WY, Chen L, Vlková B, Zhang Q, Riça I, Yaffe MB, Campbell Y, Marusich MF, Wang JM, Gong WH, Gao JL, Jung F, Douglas G, Otterbein LE, Hauser CJ. Formyl Peptide Receptor-1 Blockade Prevents Receptor Regulation by Mitochondrial Danger-Associated Molecular Patterns and Preserves Neutrophil Function After Trauma. Crit Care Med 2020; 48:e123-e132. [PMID: 31939811 PMCID: PMC7337247 DOI: 10.1097/ccm.0000000000004094] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVES Trauma predisposes to systemic sterile inflammation (systemic inflammatory response syndrome) as well as infection, but the mechanisms linking injury to infection are poorly understood. Mitochondrial debris contains formyl peptides. These bind formyl peptide receptor-1, trafficking neutrophils to wounds, initiating systemic inflammatory response syndrome, and wound healing. Bacterial formyl peptides, however, also attract neutrophils via formyl peptide receptor-1. Thus, mitochondrial formyl peptides might suppress neutrophils antimicrobial function. Also, formyl peptide receptor-1 blockade used to mitigate systemic inflammatory response syndrome might predispose to sepsis. We examined how mitochondrial formyl peptides impact neutrophils functions contributing to antimicrobial responses and how formyl peptide receptor-1 antagonists affect those functions. DESIGN Prospective study of human and murine neutrophils and clinical cohort analysis. SETTING University research laboratory and level 1 trauma center. PATIENTS Trauma patients, volunteer controls. ANIMAL SUBJECTS C57Bl/6, formyl peptide receptor-1, and formyl peptide receptor-2 knockout mice. INTERVENTIONS Human and murine neutrophils functions were activated with autologous mitochondrial debris, mitochondrial formyl peptides, or bacterial formyl peptides followed by chemokines or leukotrienes. The experiments were repeated using formyl peptide receptor-1 antagonist cyclosporin H, "designer" human formyl peptide receptor-1 antagonists (POL7178 and POL7200), or anti-formyl peptide receptor-1 antibodies. Mouse injury/lung infection model was used to evaluate effect of formyl peptide receptor-1 inhibition. MEASUREMENTS AND MAIN RESULTS Human neutrophils cytosolic calcium, chemotaxis, reactive oxygen species production, and phagocytosis were studied before and after exposure to mitochondrial debris, mitochondrial formyl peptides, and bacterial formyl peptides. Mitochondrial formyl peptide and bacterial formyl peptides had similar effects on neutrophils. Responses to chemokines and leukotrienes were suppressed by prior exposure to formyl peptides. POL7200 and POL7178 were specific antagonists of human formyl peptide receptor-1 and more effective than cyclosporin H or anti-formyl peptide receptor-1 antibodies. Formyl peptides inhibited mouse neutrophils responses to chemokines only if formyl peptide receptor-1 was present. Formyl peptide receptor-1 blockade did not inhibit neutrophils bacterial phagocytosis or reactive oxygen species production. Cyclosporin H increased bacterial clearance in lungs after injury. CONCLUSIONS Formyl peptides both activate and desensitize neutrophils. Formyl peptide receptor-1 blockade prevents desensitization, potentially both diminishing systemic inflammatory response syndrome and protecting the host against secondary infection after tissue trauma or primary infection.
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Affiliation(s)
| | | | - Woon Yong Kwon
- Beth Israel Deaconess Medical Center/Harvard Medical School
- Seoul National University Hospital, South Korea
| | - Li Chen
- Beth Israel Deaconess Medical Center/Harvard Medical School
- PLA General Hospital, Beijing, China
| | - Barbora Vlková
- Beth Israel Deaconess Medical Center/Harvard Medical School
- Comenius University, Bratislava, Slovakia
| | - Quanzhi Zhang
- Beth Israel Deaconess Medical Center/Harvard Medical School
- Harbin Medical School, Daqing, China
| | | | | | | | | | | | | | - Ji-Liang Gao
- National Institute of Allergy and Infectious Diseases/NIH
| | | | | | | | - Carl J. Hauser
- Beth Israel Deaconess Medical Center/Harvard Medical School
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8
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A subset of five human mitochondrial formyl peptides mimics bacterial peptides and functionally deactivates human neutrophils. J Trauma Acute Care Surg 2019; 85:936-943. [PMID: 29787548 DOI: 10.1097/ta.0000000000001971] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
BACKGROUND Trauma causes inflammation by releasing mitochondria that act as Danger-Associated Molecular Patterns (DAMPs). Trauma also increases susceptibility to infection. Human mitochondria contain 13 N-formyl peptides (mtFPs). We studied whether mtFPs released into plasma by clinical injury induce neutrophil (PMN) inflammatory responses, whether their potency reflects their similarity to bacterial FPs and how their presence at clinically relevant concentration affects PMN function. METHODS N-terminal sequences of the 13 mtFPs were synthesized. Changes in human PMN cytosolic Ca concentration ([Ca]i) and chemotactic responses to mtFPs were studied. Sequence similarity of mtFPs to the canonical bacterial peptide f-Met-Leu-Phe (fMLF/fMLP) was studied using the BLOcks SUbstitution Matrix 62 (BLOSUM 62) system. The presence of mtFPs in plasma of trauma patients was assayed by Enzyme-linked immunosorbent assay (ELISA). The effects of the most potent mtFP (ND6) on PMN signaling and function were then studied at ambient clinical concentrations by serial exposure of native PMN to ND6, chemokines and leukotrienes. RESULTS Five mtFPs (ND6, ND3, ND4, ND5, and Cox 1) induced [Ca]i flux and chemotaxis in descending order of potency. Evolutionary similarity to fMLF predicted [Ca]i flux and chemotactic potency linearly (R = 0.97, R = 0.95). Chemoattractant potency was also linearly related to [Ca]i flux induction (R = 0.92). Active mtFPs appear to circulate in significant amounts immediately after trauma and persist through the first week. The most active mtFP, ND6, suppresses responses to physiologic alveolar chemoattractants (CXCL-1, leukotriene B4) as well as to fMLF where CXCL-1 and leukotriene B4 do not suppress N-formyl peptide receptor (FPR)-1 responses to mtFPs. Prior FPR-1 inhibition rescues PMN from heterologous suppression of CXCR-1 and BLT-1 by mtFPs. CONCLUSION The data suggest mtFPs released by injured tissue may attract PMN to trauma sites while suppressing PMN responses to other chemoattractants. Inhibition of mtFP-FPR1 interactions might increase PMN recruitment to lung bacterial inoculation after trauma. These findings suggest new paradigms for preventing infections after trauma. LEVEL OF EVIDENCE Therapeutic, Level IV.
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9
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Danger signals from mitochondrial DAMPS in trauma and post-injury sepsis. Eur J Trauma Emerg Surg 2018; 44:317-324. [PMID: 29797026 DOI: 10.1007/s00068-018-0963-2] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2018] [Accepted: 05/19/2018] [Indexed: 12/13/2022]
Abstract
In all multicellular organisms, immediate host responses to both sterile and infective threat are initiated by very primitive systems now grouped together under the general term 'danger responses'. Danger signals are generated when primitive 'pattern recognition receptors' (PRR) encounter activating 'alarmins'. These molecular species may be of pathogenic infective origin (pathogen-associated molecular patterns) or of sterile endogenous origin (danger-associated molecular patterns). There are many sterile and infective alarmins and there is considerable overlap in their ability to activate PRR, but in all cases the end result is inflammation. It is the overlap between sterile and infective signals acting via a relatively limited number of PRR that generally underlies the great clinical similarity we see between sterile and infective systemic inflammatory responses. Mitochondria (MT) are evolutionarily derived from bacteria, and thus they sit at the crossroads between sterile and infective danger signal pathways. Many of the molecular species in mitochondria are alarmins, and so the release of MT from injured cells results in a wide variety of inflammatory events. This paper discusses the known participation of MT in inflammation and reviews what is known about how the major.
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10
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Halbgebauer R, Schmidt CQ, Karsten CM, Ignatius A, Huber-Lang M. Janus face of complement-driven neutrophil activation during sepsis. Semin Immunol 2018; 37:12-20. [PMID: 29454576 DOI: 10.1016/j.smim.2018.02.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/12/2017] [Revised: 02/06/2018] [Accepted: 02/07/2018] [Indexed: 12/28/2022]
Abstract
During local and systemic inflammation, the complement system and neutrophil granulocytes are activated not only by pathogens, but also by released endogenous danger signals. It is recognized increasingly that complement-mediated neutrophil activation plays an ambivalent role in sepsis pathophysiology. According to the current definition, the onset of organ dysfunction is a hallmark of sepsis. The preceding organ damage can be caused by excessive complement activation and neutrophil actions against the host, resulting in bystander injury of healthy tissue. However, in contrast, persistent and overwhelming inflammation also leads to a reduction in neutrophil responsiveness as well as complement components and thus may render patients at enhanced risk of spreading infection. This review provides an overview on the molecular and cellular processes that link complement with the two-faced functional alterations of neutrophils in sepsis. Finally, we describe novel tools to modulate this interplay beneficially in order to improve outcome.
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Affiliation(s)
- R Halbgebauer
- Institute of Clinical and Experimental Trauma Immunology, Ulm University Hospital, Helmholtzstr. 8/1, 89081 Ulm, Germany.
| | - C Q Schmidt
- Institute of Pharmacology of Natural Products and Clinical Pharmacology, Ulm University, Helmholtzstr. 20, 89081 Ulm, Germany.
| | - C M Karsten
- Institute for Systemic Inflammation Research, University of Luebeck, Ratzeburger Allee 160, 23562 Luebeck, Germany.
| | - A Ignatius
- Institute of Orthopedic Research and Biomechanics, University Medical Center Ulm, Helmholtzstr. 14, 89081 Ulm, Germany.
| | - M Huber-Lang
- Institute of Clinical and Experimental Trauma Immunology, Ulm University Hospital, Helmholtzstr. 8/1, 89081 Ulm, Germany.
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