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Rello J, Allam C, Ruiz-Spinelli A, Jarraud S. Severe Legionnaires' disease. Ann Intensive Care 2024; 14:51. [PMID: 38565811 PMCID: PMC10987467 DOI: 10.1186/s13613-024-01252-y] [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: 10/14/2023] [Accepted: 01/18/2024] [Indexed: 04/04/2024] Open
Abstract
BACKGROUND Legionnaires' disease (LD) is a common but under-diagnosed cause of community-acquired pneumonia (CAP), although rapid detection of urine antigen testing (UAT) and advances in molecular testing have improved the diagnosis. LD entails intensive care unit (ICU) admission in almost one-third of cases, and the mortality rate ranges from 4% to 40%. This review aims to discuss recent advances in the study of this condition and to provide an update on the diagnosis, pathogenesis and management of severe LD. RESULTS The overall incidence of LD has increased worldwide in recent years due to the higher number of patients with risk factors, especially immunosuppression, and to improvements in diagnostic methods. Although LD is responsible for only around 5% of all-cause CAP, it is one of the three most common causes of CAP requiring ICU admission. Mortality in ICU patients, immunocompromised patients or patients with a nosocomial source of LD can reach 40% despite appropriate antimicrobial therapy. Regarding pathogenesis, no Legionella-specific virulence factors have been associated with severity; however, recent reports have found high pulmonary Legionella DNA loads, and impairments in immune response and lung microbiome in the most severe cases. The clinical picture includes severe lung injury requiring respiratory and/or hemodynamic support, extrapulmonary symptoms and non-specific laboratory findings. LD diagnostic methods have improved due to the broad use of UAT and the development of molecular methods allowing the detection of all Lp serogroups. Therapy is currently based on macrolides, quinolones, or a combination of the two, with prolonged treatment in severe cases. CONCLUSIONS Numerous factors influence the mortality rate of LD, such as ICU admission, the underlying immune status, and the nosocomial source of the infection. The host immune response (hyperinflammation and/or immunoparalysis) may also be associated with increased severity. Given that the incidence of LD is rising, studies on specific biomarkers of severity may be of great interest. Further assessments comparing different regimens and/or evaluating host-directed therapies are nowadays needed.
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Affiliation(s)
- Jordi Rello
- Global Health ECore, Vall d'Hebron Institut of Research (VHIR), Barcelona, Spain
- Formation Recherche Evaluation (FOREVA) Research Group, CHU Nîmes, Nîmes, France
| | - Camille Allam
- Institut des Agents Infectieux, Centre National de Référence des Légionelles, Hospices Civils de Lyon, Lyon, France
- Centre International de Recherche en Infectiologie (CIRI), Équipe Pathogenèse des Légionelles, Université Lyon, Inserm, U1111,Université Claude Bernard Lyon 1, CNRS, UMR5308,École Normale Supérieure de Lyon, Lyon, France
| | | | - Sophie Jarraud
- Institut des Agents Infectieux, Centre National de Référence des Légionelles, Hospices Civils de Lyon, Lyon, France.
- Centre International de Recherche en Infectiologie (CIRI), Équipe Pathogenèse des Légionelles, Université Lyon, Inserm, U1111,Université Claude Bernard Lyon 1, CNRS, UMR5308,École Normale Supérieure de Lyon, Lyon, France.
- Centre National de Reference des Légionelles, Institut des Agents Infectieux, Hospices Civils de Lyon, 103 Grande rue de la Croix Rousse, 69317, Lyon Cedex 04, France.
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Korkmaz FT, Traber KE. Innate immune responses in pneumonia. Pneumonia (Nathan) 2023; 15:4. [PMID: 36829255 PMCID: PMC9957695 DOI: 10.1186/s41479-023-00106-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Accepted: 01/05/2023] [Indexed: 02/26/2023] Open
Abstract
The lungs are an immunologically unique environment; they are exposed to innumerable pathogens and particulate matter daily. Appropriate clearance of pathogens and response to pollutants is required to prevent overwhelming infection, while preventing tissue damage and maintaining efficient gas exchange. Broadly, the innate immune system is the collection of immediate, intrinsic immune responses to pathogen or tissue injury. In this review, we will examine the innate immune responses of the lung, with a particular focus on their role in pneumonia. We will discuss the anatomic barriers and antimicrobial proteins of the lung, pathogen and injury recognition, and the role of leukocytes (macrophages, neutrophils, and innate lymphocytes) and lung stromal cells in innate immunity. Throughout the review, we will focus on new findings in innate immunity as well as features that are unique to the lung.
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Affiliation(s)
- Filiz T Korkmaz
- Department of Medicine, Division of Immunology & Infectious Disease, University of Massachusetts, Worcester, MA, USA
- Pulmonary Center, Boston University School of Medicine, Boston, MA, USA
| | - Katrina E Traber
- Pulmonary Center, Boston University School of Medicine, Boston, MA, USA.
- Department of Medicine, Boston University School of Medicine, Boston, MA, USA.
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Yang JL, Li D, Zhan XY. Concept about the Virulence Factor of Legionella. Microorganisms 2022; 11:microorganisms11010074. [PMID: 36677366 PMCID: PMC9867486 DOI: 10.3390/microorganisms11010074] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Revised: 12/23/2022] [Accepted: 12/23/2022] [Indexed: 12/29/2022] Open
Abstract
Pathogenic species of Legionella can infect human alveolar macrophages through Legionella-containing aerosols to cause a disease called Legionellosis, which has two forms: a flu-like Pontiac fever and severe pneumonia named Legionnaires' disease (LD). Legionella is an opportunistic pathogen that frequently presents in aquatic environments as a biofilm or protozoa parasite. Long-term interaction and extensive co-evolution with various genera of amoebae render Legionellae pathogenic to infect humans and also generate virulence differentiation and heterogeneity. Conventionally, the proteins involved in initiating replication processes and human macrophage infections have been regarded as virulence factors and linked to pathogenicity. However, because some of the virulence factors are associated with the infection of protozoa and macrophages, it would be more accurate to classify them as survival factors rather than virulence factors. Given that the molecular basis of virulence variations among non-pathogenic, pathogenic, and highly pathogenic Legionella has not yet been elaborated from the perspective of virulence factors, a comprehensive explanation of how Legionella infects its natural hosts, protozoans, and accidental hosts, humans is essential to show a novel concept regarding the virulence factor of Legionella. In this review, we overviewed the pathogenic development of Legionella from protozoa, the function of conventional virulence factors in the infections of protozoa and macrophages, the host's innate immune system, and factors involved in regulating the host immune response, before discussing a probably new definition for the virulence factors of Legionella.
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Effah CY, Drokow EK, Agboyibor C, Ding L, He S, Liu S, Akorli SY, Nuamah E, Sun T, Zhou X, Liu H, Xu Z, Feng F, Wu Y, Zhang X. Neutrophil-Dependent Immunity During Pulmonary Infections and Inflammations. Front Immunol 2021; 12:689866. [PMID: 34737734 PMCID: PMC8560714 DOI: 10.3389/fimmu.2021.689866] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Accepted: 09/23/2021] [Indexed: 01/08/2023] Open
Abstract
Rapid recruitment of neutrophils to an inflamed site is one of the hallmarks of an effective host defense mechanism. The main pathway through which this happens is by the innate immune response. Neutrophils, which play an important part in innate immune defense, migrate into lungs through the modulation actions of chemokines to execute a variety of pro-inflammatory functions. Despite the importance of chemokines in host immunity, little has been discussed on their roles in host immunity. A holistic understanding of neutrophil recruitment, pattern recognition pathways, the roles of chemokines and the pathophysiological roles of neutrophils in host immunity may allow for new approaches in the treatment of infectious and inflammatory disease of the lung. Herein, this review aims at highlighting some of the developments in lung neutrophil-immunity by focusing on the functions and roles of CXC/CC chemokines and pattern recognition receptors in neutrophil immunity during pulmonary inflammations. The pathophysiological roles of neutrophils in COVID-19 and thromboembolism have also been summarized. We finally summarized various neutrophil biomarkers that can be utilized as prognostic molecules in pulmonary inflammations and discussed various neutrophil-targeted therapies for neutrophil-driven pulmonary inflammatory diseases.
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Affiliation(s)
| | - Emmanuel Kwateng Drokow
- Department of Radiation Oncology, Zhengzhou University People’s Hospital & Henan Provincial People’s Hospital, Zhengzhou, China
| | - Clement Agboyibor
- School of Pharmaceutical Sciences, Zhengzhou University, Zhengzhou, China
| | - Lihua Ding
- College of Public Health, Zhengzhou University, Zhengzhou, China
| | - Sitian He
- College of Public Health, Zhengzhou University, Zhengzhou, China
| | - Shaohua Liu
- General ICU, Henan Key Laboratory of Critical Care Medicine, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
| | - Senyo Yao Akorli
- College of Agriculture and Natural Sciences, University of Cape Coast, Cape Coast, Ghana
| | - Emmanuel Nuamah
- College of Agriculture and Natural Sciences, University of Cape Coast, Cape Coast, Ghana
| | - Tongwen Sun
- General ICU, Henan Key Laboratory of Critical Care Medicine, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
| | - Xiaolei Zhou
- Department of Respiratory, Henan Provincial Chest Hospital, Zhengzhou, China
| | - Hong Liu
- Department of Respiratory, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
| | - Zhiwei Xu
- Department of Respiratory and Critical Care Medicine, People’s Hospital of Zhengzhou University & Henan Provincial People’s Hospital, Zhengzhou, China
| | - Feifei Feng
- College of Public Health, Zhengzhou University, Zhengzhou, China
| | - Yongjun Wu
- College of Public Health, Zhengzhou University, Zhengzhou, China
| | - Xiaoju Zhang
- Department of Respiratory and Critical Care Medicine, People’s Hospital of Zhengzhou University & Henan Provincial People’s Hospital, Zhengzhou, China
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Human macrophages utilize a wide range of pathogen recognition receptors to recognize Legionella pneumophila, including Toll-Like Receptor 4 engaging Legionella lipopolysaccharide and the Toll-like Receptor 3 nucleic-acid sensor. PLoS Pathog 2021; 17:e1009781. [PMID: 34280250 PMCID: PMC8321404 DOI: 10.1371/journal.ppat.1009781] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Revised: 07/29/2021] [Accepted: 07/03/2021] [Indexed: 12/15/2022] Open
Abstract
Cytokines made by macrophages play a critical role in determining the course of Legionella pneumophila infection. Prior murine-based modeling indicated that this cytokine response is initiated upon recognition of L. pneumophila by a subset of Toll-like receptors, namely TLR2, TLR5, and TLR9. Through the use of shRNA/siRNA knockdowns and subsequently CRISPR/Cas9 knockouts (KO), we determined that TRIF, an adaptor downstream of endosomal TLR3 and TLR4, is required for full cytokine secretion by human primary and cell-line macrophages. By characterizing a further set of TLR KO's in human U937 cells, we discerned that, contrary to the viewpoint garnered from murine-based studies, TLR3 and TLR4 (along with TLR2 and TLR5) are in fact vital to the macrophage response in the early stages of L. pneumophila infection. This conclusion was bolstered by showing that i) chemical inhibitors of TLR3 and TLR4 dampen the cytokine output of primary human macrophages and ii) transfection of TLR3 and TLR4 into HEK cells conferred an ability to sense L. pneumophila. TLR3- and TLR4-dependent cytokines promoted migration of human HL-60 neutrophils across an epithelial layer, pointing to the biological importance for the newfound signaling pathway. The response of U937 cells to L. pneumophila LPS was dependent upon TLR4, a further contradiction to murine-based studies, which had concluded that TLR2 is the receptor for Legionella LPS. Given the role of TLR3 in sensing nucleic acid (i.e., dsRNA), we utilized newly-made KO U937 cells to document that DNA-sensing by cGAS-STING and DNA-PK are also needed for the response of human macrophages to L. pneumophila. Given the lack of attention given them in the bacterial field, C-type lectin receptors were similarly examined; but, they were not required. Overall, this study arguably represents the most extensive, single-characterization of Legionella-recognition receptors within human macrophages.
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Zhang H, He F, Li P, Hardwidge PR, Li N, Peng Y. The Role of Innate Immunity in Pulmonary Infections. BIOMED RESEARCH INTERNATIONAL 2021; 2021:6646071. [PMID: 33553427 PMCID: PMC7847335 DOI: 10.1155/2021/6646071] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/31/2020] [Revised: 12/26/2020] [Accepted: 01/08/2021] [Indexed: 02/07/2023]
Abstract
Innate immunity forms a protective line of defense in the early stages of pulmonary infection. The primary cellular players of the innate immunity against respiratory infections are alveolar macrophages (AMs), dendritic cells (DCs), neutrophils, natural killer (NK) cells, and innate lymphoid cells (ILCs). They recognize conserved structures of microorganisms through membrane-bound and intracellular receptors to initiate appropriate responses. In this review, we focus on the prominent roles of innate immune cells and summarize transmembrane and cytosolic pattern recognition receptor (PRR) signaling recognition mechanisms during pulmonary microbial infections. Understanding the mechanisms of PRR signal recognition during pulmonary pathogen infections will help us to understand pulmonary immunopathology and lay a foundation for the development of effective therapies to treat and/or prevent pulmonary infections.
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Affiliation(s)
- Huihui Zhang
- College of Animal Medicine, Southwest University, Chongqing, China
| | - Fang He
- College of Animal Medicine, Southwest University, Chongqing, China
| | - Pan Li
- College of Animal Medicine, Southwest University, Chongqing, China
| | | | - Nengzhang Li
- College of Animal Medicine, Southwest University, Chongqing, China
| | - Yuanyi Peng
- College of Animal Medicine, Southwest University, Chongqing, China
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Theresine M, Patil ND, Zimmer J. Airway Natural Killer Cells and Bacteria in Health and Disease. Front Immunol 2020; 11:585048. [PMID: 33101315 PMCID: PMC7546320 DOI: 10.3389/fimmu.2020.585048] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2020] [Accepted: 09/08/2020] [Indexed: 12/16/2022] Open
Abstract
Natural killer (NK) cells are innate lymphoid cells at the interface between innate and adaptive immunity and mostly studied for their important roles in viral infections and malignant tumors. They can kill diseased cells and produce cytokines and chemokines, thereby shaping the adaptive immune response. Nowadays, NK cells are considered as a strong weapon for cancer immunotherapy and can for example be transduced to express tumor-specific chimeric antigen receptors or harnessed with therapeutic antibodies such as the so-called NK engagers. Whereas a large body of literature exists about the antiviral and antitumoral properties of NK cells, their potential role in bacterial infections is not that well delineated. Furthermore, NK cells are much more heterogeneous than previously thought and have tissue-characteristic features and phenotypes. This review gives an overview of airway NK cells and their position within the immunological army dressed against bacterial infections in the upper and predominantly the lower respiratory tracts. Whereas it appears that in several infections, NK cells play a non-redundant and protective role, they can likewise act as rather detrimental. The use of mouse models and the difficulty of access to human airway tissues for ethical reasons might partly explain the divergent results. However, new methods are appearing that are likely to reduce the heterogeneity between studies and to give a more coherent picture in this field.
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Affiliation(s)
- Maud Theresine
- CG I Group, Department of Infection and Immunity, Luxembourg Institute of Health, Esch-sur-Alzette, Luxembourg
| | - Neha D Patil
- CG I Group, Department of Infection and Immunity, Luxembourg Institute of Health, Esch-sur-Alzette, Luxembourg
| | - Jacques Zimmer
- CG I Group, Department of Infection and Immunity, Luxembourg Institute of Health, Esch-sur-Alzette, Luxembourg
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Papian S, Mohabati Mobarez A, Khoramabadi N, Mehdi Abdol M, Talebi Bezmin Abadi A. Investigating the role of L. pnuemophila LPS derivatives in formation of specific cell-mediated immune responses against the pathogen. Microb Pathog 2020; 147:104396. [PMID: 32687938 DOI: 10.1016/j.micpath.2020.104396] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Accepted: 07/10/2020] [Indexed: 02/06/2023]
Abstract
Legionella pneumophila is a Gram-negative intracellular bacterium and causes legionnaire's disease an -atypical pneumonia in humans. Lipopolysaccharide (LPS) is the main antigen of Gram-negative bacteria but is less studied because of its carbohydrate nature. Here, we immunized mice with detoxified LPS and O-antigen polysaccharide in combination with bovine serum albumin (BSA) and explored the immunological responses of mice to the bacterial infection. LPS of L. pneumophila was extracted by hot phenol-water method. Purified LPS was detoxified by sodium hydroxide alkaline procedure. O-polysaccharide antigen (OPS) obtained by acetic acid treatment of LPS. BALB/c mice were immunized mainly with non-covalent combination of detoxified LPS (dLPS) or OPS with BSA separately. Pure polysaccharide antigens did not elicit significant serum IgG against LPS. Combination of the dLPS and OPS with BSA resulted in risen IgG and its subclasses (IgG1 and IgG2a) against lipopolysaccharide. Mice were challenged intravenously with sublethal dose of L. pneumpphila. Then, splenocytes were cultured and cytokine responses of splenocytes to pathogenic Legionella was studied by ELISA. Mice immunized with combination of the dLPS or OPS and BSA showed significant elevation of cytokine responses to pathogenic L. pneumophila. Our results suggest that combination of the polysaccharide antigen derived from Legionella LPS may confer raised cell-mediated responses against the pathogen when combined with a protein antigen which is capable of eliciting cell-mediated responses. Although not covalently bond, Legionella polysaccharides combined with BSA effectively elicited Th-1 type cytokines and humoral responses against L. pneumophila in BALB/c mice.
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Affiliation(s)
- Shaghayegh Papian
- Department of Bacteriology, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran
| | - Ashraf Mohabati Mobarez
- Department of Bacteriology, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran.
| | - Nima Khoramabadi
- Department of Bacteriology, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran
| | - Mohsen Mehdi Abdol
- Department of Bacteriology, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran
| | - Amin Talebi Bezmin Abadi
- Department of Bacteriology, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran
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Overlapping Roles for Interleukin-36 Cytokines in Protective Host Defense against Murine Legionella pneumophila Pneumonia. Infect Immun 2018; 87:IAI.00583-18. [PMID: 30323031 PMCID: PMC6300640 DOI: 10.1128/iai.00583-18] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2018] [Accepted: 10/12/2018] [Indexed: 01/19/2023] Open
Abstract
Legionella pneumophila causes life-threatening pneumonia culminating in acute lung injury. Innate and adaptive cytokines play an important role in host defense against L. pneumophila infection. Interleukin-36 (IL-36) cytokines are recently described members of the larger IL-1 cytokine family known to exert potent inflammatory effects. In this study, we elucidated the role for IL-36 cytokines in experimental pneumonia caused by L. pneumophila Intratracheal (i.t.) administration of L. pneumophila induced the upregulation of both IL-36α and IL-36γ mRNA and protein production in the lung. Compared to the findings for L. pneumophila-infected wild-type (WT) mice, the i.t. administration of L. pneumophila to IL-36 receptor-deficient (IL-36R-/-) mice resulted in increased mortality, a delay in lung bacterial clearance, increased L. pneumophila dissemination to extrapulmonary organs, and impaired glucose homeostasis. Impaired lung bacterial clearance in IL-36R-/- mice was associated with a significantly reduced accumulation of inflammatory cells and the decreased production of proinflammatory cytokines and chemokines. Ex vivo, reduced expression of costimulatory molecules and impaired M1 polarization were observed in alveolar macrophages isolated from infected IL-36R-/- mice compared to macrophages from WT mice. While L. pneumophila-induced mortality in IL-36α- or IL-36γ-deficient mice was not different from that in WT animals, antibody-mediated neutralization of IL-36γ in IL-36α-/- mice resulted in mortality similar to that observed in IL-36R-/- mice, indicating redundant and overlapping roles for these cytokines in experimental murine L. pneumophila pneumonia.
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Advanced Role of Neutrophils in Common Respiratory Diseases. J Immunol Res 2017; 2017:6710278. [PMID: 28589151 PMCID: PMC5447318 DOI: 10.1155/2017/6710278] [Citation(s) in RCA: 56] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2017] [Revised: 03/22/2017] [Accepted: 04/16/2017] [Indexed: 12/18/2022] Open
Abstract
Respiratory diseases, always being a threat towards the health of people all over the world, are most tightly associated with immune system. Neutrophils serve as an important component of immune defense barrier linking innate and adaptive immunity. They participate in the clearance of exogenous pathogens and endogenous cell debris and play an essential role in the pathogenesis of many respiratory diseases. However, the pathological mechanism of neutrophils remains complex and obscure. The traditional roles of neutrophils in severe asthma, chronic obstructive pulmonary diseases (COPD), pneumonia, lung cancer, pulmonary fibrosis, bronchitis, and bronchiolitis had already been reviewed. With the development of scientific research, the involvement of neutrophils in respiratory diseases is being brought to light with emerging data on neutrophil subsets, trafficking, and cell death mechanism (e.g., NETosis, apoptosis) in diseases. We reviewed all these recent studies here to provide you with the latest advances about the role of neutrophils in respiratory diseases.
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