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Bastani MN, Jalilian S. Unraveling the enigma: The emerging significance of pulmonary surfactant proteins in predicting, diagnosing, and managing COVID-19. Immun Inflamm Dis 2024; 12:e1302. [PMID: 38860749 PMCID: PMC11165688 DOI: 10.1002/iid3.1302] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2024] [Revised: 04/23/2024] [Accepted: 05/19/2024] [Indexed: 06/12/2024] Open
Abstract
BACKGROUND Severe cases of COVID-19 often lead to the development of acute respiratory syndrome, a critical condition believed to be caused by the harmful effects of SARS-CoV-2 on type II alveolar cells. These cells play a crucial role in producing pulmonary surfactants, which are essential for proper lung function. Specifically focusing on surfactant proteins, including Surfactant protein A (SP-A), Surfactant protein B, Surfactant protein C, and Surfactant protein D (SP-D), changes in the levels of pulmonary surfactants may be a significant factor in the pathological changes seen in COVID-19 infection. OBJECTIVE This study aims to gain insights into surfactants, particularly their impacts and changes during COVID-19 infection, through a comprehensive review of current literature. The study focuses on the function of surfactants as prognostic markers, diagnostic factors, and essential components in the management and treatment of COVID-19. FINDING In general, pulmonary surfactants serve to reduce the surface tension at the gas-liquid interface, thereby significantly contributing to the regulation of respiratory mechanics. Additionally, these surfactants play a crucial role in the innate immune system within the pulmonary microenvironment. Within the spectrum of COVID-19 infections, a compelling association is observed, characterized by elevated levels of SP-D and SP-A across a range of manifestations from mild to severe pneumonia. The sudden decline in respiratory function observed in COVID-19 patients may be attributed to the decreased synthesis of surfactants by type II alveolar cells. CONCLUSION Collectin proteins such as SP-A and SP-D show promise as biomarkers, offering potential avenues for predicting and monitoring pulmonary alveolar injury in the context of COVID-19. This clarification enhances our understanding of the molecular complexities contributing to respiratory complications in severe COVID-19 cases, providing a foundation for targeted therapeutic approaches using surfactants and refined clinical management strategies.
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Affiliation(s)
- Mohammad Navid Bastani
- Department of Medical Virology, School of MedicineAhvaz Jundishapur University of Medical SciencesAhvazIran
| | - Shahram Jalilian
- Department of Medical Virology, School of MedicineAhvaz Jundishapur University of Medical SciencesAhvazIran
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2
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Abstract
Pulmonary surfactant is a critical component of lung function in healthy individuals. It functions in part by lowering surface tension in the alveoli, thereby allowing for breathing with minimal effort. The prevailing thinking is that low surface tension is attained by a compression-driven squeeze-out of unsaturated phospholipids during exhalation, forming a film enriched in saturated phospholipids that achieves surface tensions close to zero. A thorough review of past and recent literature suggests that the compression-driven squeeze-out mechanism may be erroneous. Here, we posit that a surfactant film enriched in saturated lipids is formed shortly after birth by an adsorption-driven sorting process and that its composition does not change during normal breathing. We provide biophysical evidence for the rapid formation of an enriched film at high surfactant concentrations, facilitated by adsorption structures containing hydrophobic surfactant proteins. We examine biophysical evidence for and against the compression-driven squeeze-out mechanism and propose a new model for surfactant function. The proposed model is tested against existing physiological and pathophysiological evidence in neonatal and adult lungs, leading to ideas for biophysical research, that should be addressed to establish the physiological relevance of this new perspective on the function of the mighty thin film that surfactant provides.
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Affiliation(s)
- Fred Possmayer
- Department of Biochemistry, Western University, London, Ontario N6A 3K7, Canada
- Department of Obstetrics/Gynaecology, Western University, London, Ontario N6A 3K7, Canada
| | - Yi Y Zuo
- Department of Mechanical Engineering, University of Hawaii at Manon, Honolulu, Hawaii 96822, United States
- Department of Pediatrics, John A. Burns School of Medicine, University of Hawaii, Honolulu, Hawaii 96826, United States
| | - Ruud A W Veldhuizen
- Department of Physiology & Pharmacology, Western University, London, Ontario N6A 5C1, Canada
- Department of Medicine, Western University, London, Ontario N6A 3K7, Canada
- Lawson Health Research Institute, London, Ontario N6A 4V2, Canada
| | - Nils O Petersen
- Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2, Canada
- Department of Chemistry, Western University, London, Ontario N6A 5B7, Canada
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Watson A, Madsen J, Clark HW. SP-A and SP-D: Dual Functioning Immune Molecules With Antiviral and Immunomodulatory Properties. Front Immunol 2021; 11:622598. [PMID: 33542724 PMCID: PMC7851053 DOI: 10.3389/fimmu.2020.622598] [Citation(s) in RCA: 57] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Accepted: 12/14/2020] [Indexed: 01/08/2023] Open
Abstract
Surfactant proteins A (SP-A) and D (SP-D) are soluble innate immune molecules which maintain lung homeostasis through their dual roles as anti-infectious and immunomodulatory agents. SP-A and SP-D bind numerous viruses including influenza A virus, respiratory syncytial virus (RSV) and human immunodeficiency virus (HIV), enhancing their clearance from mucosal points of entry and modulating the inflammatory response. They also have diverse roles in mediating innate and adaptive cell functions and in clearing apoptotic cells, allergens and other noxious particles. Here, we review how the properties of these first line defense molecules modulate inflammatory responses, as well as host-mediated immunopathology in response to viral infections. Since SP-A and SP-D are known to offer protection from viral and other infections, if their levels are decreased in some disease states as they are in severe asthma and chronic obstructive pulmonary disease (COPD), this may confer an increased risk of viral infection and exacerbations of disease. Recombinant molecules of SP-A and SP-D could be useful in both blocking respiratory viral infection while also modulating the immune system to prevent excessive inflammatory responses seen in, for example, RSV or coronavirus disease 2019 (COVID-19). Recombinant SP-A and SP-D could have therapeutic potential in neutralizing both current and future strains of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus as well as modulating the inflammation-mediated pathology associated with COVID-19. A recombinant fragment of human (rfh)SP-D has recently been shown to neutralize SARS-CoV-2. Further work investigating the potential therapeutic role of SP-A and SP-D in COVID-19 and other infectious and inflammatory diseases is indicated.
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Affiliation(s)
- Alastair Watson
- Clinical and Experimental Sciences, Faculty of Medicine, Southampton General Hospital, University of Southampton, Southampton, United Kingdom
- Southampton NIHR Respiratory Biomedical Research Centre, Southampton General Hospital, Southampton, United Kingdom
- Birmingham Medical School, University of Birmingham, Birmingham, United Kingdom
| | - Jens Madsen
- Neonatology, EGA Institute for Women’s Health, Faculty of Population Health Sciences, University College London, London, United Kingdom
| | - Howard William Clark
- Neonatology, EGA Institute for Women’s Health, Faculty of Population Health Sciences, University College London, London, United Kingdom
- NIHR Biomedical Research Centre, University College London Hospital (UCLH), University College London (UCL), London, United Kingdom
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Zhang J, Tan SB, Guo ZG. CD47 decline in pancreatic islet cells promotes macrophage-mediated phagocytosis in type I diabetes. World J Diabetes 2020; 11:239-251. [PMID: 32547698 PMCID: PMC7284019 DOI: 10.4239/wjd.v11.i6.239] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/07/2019] [Revised: 03/30/2020] [Accepted: 04/19/2020] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Type I diabetes (T1D) is characterized by insulin loss caused by inflammatory cells that excessively infiltrate and destroy the pancreas, resulting in dysregulation of tissue homeostasis, mechanobiological properties, and the immune response. The streptozotocin (STZ)-induced mouse model exhibits multiple features of human T1D and enables mechanistic analysis of disease progression. However, the relationship between the mechanochemical signaling regulation of STZ-induced T1D and macrophage migration and phagocytosis is unclear.
AIM To study the mechanochemical regulation of STZ-induced macrophage response on pancreatic beta islet cells to gain a clearer understanding of T1D.
METHODS We performed experiments using different methods. We stimulated isolated pancreatic beta islet cells with STZ and then tested the macrophage migration and phagocytosis.
RESULTS In this study, we discovered that the integrin-associated surface factor CD47 played a critical role in immune defense in the STZ-induced T1D model by preventing pancreatic beta islet inflammation. In comparison with healthy mice, STZ-treated mice showed decreased levels of CD47 on islet cells and reduced interaction of CD47 with signal regulatory protein α (SIRPα), which negatively regulates macrophage-mediated phagocytosis. This resulted in weakened islet cell immune defense and promoted macrophage migration and phagocytosis of target inflammatory cells. Moreover, lipopolysaccharide-activated human acute monocytic leukemia THP-1 cells also exhibited enhanced phagocytosis in the STZ-treated islets, and the aggressive attack of the inflammatory islets correlated with impaired CD47-SIRPα interactions. In addition, CD47 overexpression rescued the pre-labeled targeted cells.
CONCLUSION This study indicates that CD47 deficiency promotes the migration and phagocytosis of macrophages and provides mechanistic insights into T1D by associating the interactions between membrane structures and inflammatory disease progression.
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Affiliation(s)
- Jing Zhang
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing 210097, Jiangsu Province, China
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, United States
| | - Su-Bee Tan
- National Key Laboratory for Biochemistry, College of Life Sciences, Nanjing University, Nanjing 210093, Jiangsu Province, China
| | - Zhi-Gang Guo
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing 210097, Jiangsu Province, China
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5
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Surfactant Protein A Impairs Genital HPV16 Pseudovirus Infection by Innate Immune Cell Activation in A Murine Model. Pathogens 2019; 8:pathogens8040288. [PMID: 31817644 PMCID: PMC6963799 DOI: 10.3390/pathogens8040288] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2019] [Revised: 12/03/2019] [Accepted: 12/04/2019] [Indexed: 02/06/2023] Open
Abstract
Infection by oncogenic human papillomavirus (HPV) is the principle cause of cervical cancer and other anogenital cancers. The majority of cervical cancer cases occur in low- and middle-income countries (LMIC). Prophylactic vaccines exist to combat HPV infection but accessibility to these in LMIC is limited. Alternative preventative measures against HPV infection are therefore also needed to control cervical cancer risk. HPV employs multiple mechanisms to evade the host immune response. Therefore, an approach to promote HPV recognition by the immune system can reduce infection. Surfactant proteins A and D (SP-A and SP-D) are highly effective innate opsonins of pathogens. Their function is primarily understood in the lung, but they are also expressed at other sites of the body, including the female reproductive tract (FRT). We hypothesized that raised levels of SP-A and/or SP-D may enhance immune recognition of HPV and reduce infection. Co-immunoprecipitation and flow cytometry experiments showed that purified human SP-A protein directly bound HPV16 pseudovirions (HPV16-PsVs), and the resulting HPV16-PsVs/SP-A complex enhanced uptake of HPV16-PsVs by RAW264.7 murine macrophages. In contrast, a recombinant fragment of human SP-D bound HPV16-PsVs weakly and had no effect on viral uptake. To assess if SP-A modulates HPV16-PsVs infection in vivo, a murine cervicovaginal challenge model was applied. Surprisingly, neither naïve nor C57BL/6 mice challenged with HPV16-PsVs expressed SP-A in the FRT. However, pre-incubation of HPV16-PsVs with purified human SP-A at a 1:10 (w/w) ratio significantly reduced the level of HPV16-PsV infection. When isolated cells from FRTs of naïve C57BL/6 mice were incubated with HPV16-PsVs and stained for selected innate immune cell populations by flow cytometry, significant increases in HPV16-PsVs uptake by eosinophils, neutrophils, monocytes, and macrophages were observed over time using SP-A-pre-adsorbed virions compared to control particles. This study is the first to describe a biochemical and functional association of HPV16 virions with the innate immune molecule SP-A. We show that SP-A impairs HPV16-PsVs infection and propose that SP-A is a potential candidate for use in topical microbicides which provide protection against new HPV infections.
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Watson A, Phipps MJS, Clark HW, Skylaris CK, Madsen J. Surfactant Proteins A and D: Trimerized Innate Immunity Proteins with an Affinity for Viral Fusion Proteins. J Innate Immun 2018; 11:13-28. [PMID: 30293076 PMCID: PMC6738215 DOI: 10.1159/000492974] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2018] [Accepted: 08/16/2018] [Indexed: 12/20/2022] Open
Abstract
Innate recognition of viruses is an essential part of the immune response to viral pathogens. This is integral to the maintenance of healthy lungs, which are free from infection and efficient at gaseous exchange. An important component of innate immunity for identifying viruses is the family of C-type collagen-containing lectins, also known as collectins. These secreted, soluble proteins are pattern recognition receptors (PRRs) which recognise pathogen-associated molecular patterns (PAMPs), including viral glycoproteins. These innate immune proteins are composed of trimerized units which oligomerise into higher-order structures and facilitate the clearance of viral pathogens through multiple mechanisms. Similarly, many viral surface proteins form trimeric configurations, despite not showing primary protein sequence similarities across the virus classes and families to which they belong. In this review, we discuss the role of the lung collectins, i.e., surfactant proteins A and D (SP-A and SP-D) in viral recognition. We focus particularly on the structural similarity and complementarity of these trimeric collectins with the trimeric viral fusion proteins with which, we hypothesise, they have elegantly co-evolved. Recombinant versions of these innate immune proteins may have therapeutic potential in a range of infectious and inflammatory lung diseases including anti-viral therapeutics.
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Affiliation(s)
- Alastair Watson
- Child Health, Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton General Hospital, Southampton, United Kingdom
| | - Maximillian J S Phipps
- Computational Chemistry, Chemistry, Faculty of Natural and Environmental Sciences, University of Southampton, Southampton, United Kingdom
| | - Howard W Clark
- Child Health, Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton General Hospital, Southampton, United Kingdom.,Institute for Life Sciences, University of Southampton, Southampton, United Kingdom.,National Institute for Health Research, Southampton Respiratory Biomedical Research Unit, Southampton Centre for Biomedical Research, University Hospital Southampton NHS Foundation Trust, Southampton, United Kingdom
| | - Chris-Kriton Skylaris
- Computational Chemistry, Chemistry, Faculty of Natural and Environmental Sciences, University of Southampton, Southampton, United Kingdom
| | - Jens Madsen
- Child Health, Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton General Hospital, Southampton, United .,Institute for Life Sciences, University of Southampton, Southampton, United .,National Institute for Health Research, Southampton Respiratory Biomedical Research Unit, Southampton Centre for Biomedical Research, University Hospital Southampton NHS Foundation Trust, Southampton, United
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7
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Casals C, Campanero-Rhodes MA, García-Fojeda B, Solís D. The Role of Collectins and Galectins in Lung Innate Immune Defense. Front Immunol 2018; 9:1998. [PMID: 30233589 PMCID: PMC6131309 DOI: 10.3389/fimmu.2018.01998] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2018] [Accepted: 08/14/2018] [Indexed: 12/16/2022] Open
Abstract
Different families of endogenous lectins use complementary defense strategies against pathogens. They may recognize non-self glycans typically found on pathogens and/or host glycans. The collectin and galectin families are prominent examples of these two lectin categories. Collectins are C-type lectins that contain a carbohydrate recognition domain and a collagen-like domain. Members of this group include surfactant protein A (SP-A) and D (SP-D), secreted by the alveolar epithelium to the alveolar fluid. Lung collectins bind to several microorganisms, which results in pathogen aggregation and/or killing, and enhances phagocytosis of pathogens by alveolar macrophages. Moreover, SP-A and SP-D influence macrophage responses, contributing to resolution of inflammation, and SP-A is essential for tissue-repair functions of macrophages. Galectins also function by interacting directly with pathogens or by modulating the immune system in response to the infection. Direct binding may result in enhanced or impaired infection of target cells, or can have microbicidal effects. Immunomodulatory effects of galectins include recruitment of immune cells to the site of infection, promotion of neutrophil function, and stimulation of the bactericidal activity of infected macrophages. Moreover, intracellular galectins can serve as danger receptors, promoting autophagy of the invading pathogen. This review will focus on the role of collectins and galectins in pathogen clearance and immune response activation in infectious diseases of the respiratory system.
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Affiliation(s)
- Cristina Casals
- Centro de Investigación Biomédica en Red de Enfermedades Respiratorias (CIBERES), Instituto de Salud Carlos III, Madrid, Spain.,Departamento de Bioquímica y Biología Molecular, Universidad Complutense de Madrid, Madrid, Spain
| | - María A Campanero-Rhodes
- Centro de Investigación Biomédica en Red de Enfermedades Respiratorias (CIBERES), Instituto de Salud Carlos III, Madrid, Spain.,Instituto de Química Física Rocasolano, CSIC, Madrid, Spain
| | - Belén García-Fojeda
- Centro de Investigación Biomédica en Red de Enfermedades Respiratorias (CIBERES), Instituto de Salud Carlos III, Madrid, Spain.,Departamento de Bioquímica y Biología Molecular, Universidad Complutense de Madrid, Madrid, Spain
| | - Dolores Solís
- Centro de Investigación Biomédica en Red de Enfermedades Respiratorias (CIBERES), Instituto de Salud Carlos III, Madrid, Spain.,Instituto de Química Física Rocasolano, CSIC, Madrid, Spain
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8
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Abstract
Only a few extracellular soluble proteins are known to modulate apoptosis. We considered that surfactant-associated protein D (SP-D), an innate immune collectin present on many mucosal surfaces, could regulate apoptosis. Although SP-D is known to be important for immune cell homeostasis, whether SP-D affects apoptosis is unknown. In this study we aimed to determine the effects of SP-D on Jurkat T cells and human T cells dying by apoptosis. Here we show that SP-D binds to Jurkat T cells and delays the progression of Fas (CD95)-Fas ligand and TRAIL-TRAIL receptor induced, but not TNF-TNF receptor-mediated apoptosis. SP-D exerts its effects by reducing the activation of initiator caspase-8 and executioner caspase-3. SP-D also delays the surface exposure of phosphatidylserine. The effect of SP-D was ablated by the presence of caspase-8 inhibitor, but not by intrinsic pathway inhibitors. The binding ability of SP-D to dying cells decreases during the early stages of apoptosis, suggesting the release of apoptotic cell surface targets during apoptosis. SP-D also delays FasL-induced death of primary human T cells. SP-D delaying the progression of the extrinsic pathway of apoptosis could have important implications in regulating immune cell homeostasis at mucosal surfaces.
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9
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Surfactant Proteins SP-A and SP-D Ameliorate Pneumonia Severity and Intestinal Injury in a Murine Model of Staphylococcus Aureus Pneumonia. Shock 2018; 46:164-72. [PMID: 26849628 DOI: 10.1097/shk.0000000000000587] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
UNLABELLED Staphylococcus aureus pneumonia is an important cause of sepsis which causes gut injury, inflammation, and apoptosis. The surfactant proteins surfactant protein A (SP-A) and surfactant protein D (SP-D) bind bacterial pathogens and facilitate clearance of pathogens, apoptotic bodies, and modulate immune responses. SP-A and SP-D are expressed in both lung and gut epithelia. We hypothesize SP-A and SP-D regulate pneumonia severity and gut injury during pneumonia. METHODS Wild-type (WT) and SP-A and SP-D double knockout (SP-A/D KO) mice were subjected to S. aureus or sham pneumonia. Bronchoalveolar lavage and tissue harvest were performed 24 h later. Pneumonia severity, gut mucosal injury, inflammation, and apoptosis were measured using a combination of histology, immunohistochemistry, cytokine assay, TUNEL assay, quantitative real-time polymerase chain reaction, and Western blot analyses. RESULTS Pneumonia increased gut inflammation, apoptosis, and mucosal injury in both groups. Pneumonia histology and bacterial growth in bronchoalveolar lavage fluid demonstrate more severe infection in SP-A/D KO mice compared with WT controls. SP-A/D KO mice with pneumonia also demonstrate more severe histologic gut mucosal injury, increased gut apoptosis, elevated caspase-3 levels, and Bax/Bcl-2 mRNA expression compared with WT pneumonia mice. Nuclear factor κB (NF-κB) p65 expression and its nuclear translocation, gut levels of tumor necrosis factor α and interleukin-1β were all increased in SP-A/D KO mice with pneumonia compared with WT controls. CONCLUSIONS These data provide evidence SP-A and SP-D attenuate S. aureus pneumonia severity resulting in decreased intestinal mucosal injury, apoptosis, and inflammation. Improved pulmonary clearance of S. aureus decreased caspase-3 and Bax/Bcl-2 expressions and decreased activation of the NF-κB signaling pathway in intestine represent potential mechanisms for the effects of SP-A and SP-D on gut injury during pneumonia.
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Djiadeu P, Farmakovski N, Azzouz D, Kotra LP, Sweezey N, Palaniyar N. Surfactant protein D regulates caspase-8-mediated cascade of the intrinsic pathway of apoptosis while promoting bleb formation. Mol Immunol 2017; 92:190-198. [PMID: 29107869 DOI: 10.1016/j.molimm.2017.10.016] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Revised: 10/17/2017] [Accepted: 10/17/2017] [Indexed: 01/10/2023]
Abstract
Surfactant-associated protein D (SP-D) is a soluble innate immune collectin present on many mucosal surfaces. We recently showed that SP-D suppresses the extrinsic pathway of apoptosis by downregulating caspase-8 activation. However, the effects of SP-D on the intrinsic pathway of apoptosis are not clearly understood. In the intrinsic pathway, cytochrome c is released by mitochondria into the cytoplasm. Oxidation of cytochrome c by cytochrome c oxidase activates the apoptosome and caspase-9 cascade. Both caspase-8- and caspase-9-mediated branches are activated in the intrinsic pathway of apoptosis; however, little is known about the relevance of the caspase-8 pathway in this context. Here we studied the effects of SP-D on different branches of the intrinsic pathway of apoptosis using UV-irradiated Jurkat T-cells. We found that SP-D does not inhibit the caspase-9 branch of apoptosis and the relevance of the caspase-8-related branch became apparent when the caspase-9 pathway was inhibited by blocking cytochrome c oxidase. Under these conditions, SP-D reduces the activation of caspase-8, executioner caspase-3 and exposure of phosphatidylserine (PS) on the membranes of dying cells. By contrast, SP-D increases the formation of nuclear and membrane blebs. Inhibition of caspase-8 confirms the effect of SP-D is unique to the caspase-8 pathway. Overall, SP-D suppresses certain aspects of the intrinsic pathway of apoptosis via reduction of caspase-8 activation and PS flipping while at the same time increasing membrane and nuclear bleb formation. This novel regulatory aspect of SP-D could help to regulate intrinsic pathway of apoptosis to promote effective blebbing and breakdown of dying cells.
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Affiliation(s)
- Pascal Djiadeu
- Lung Innate Immunity Research Laboratory, Program in Translational Medicine, Peter Gilgan Centre for Research and Learning, The Hospital for Sick Children, 686 Bay St, Toronto, ON, M5G 0A4, Canada; Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Ontario, M5S 3M2, Canada
| | - Nicole Farmakovski
- Lung Innate Immunity Research Laboratory, Program in Translational Medicine, Peter Gilgan Centre for Research and Learning, The Hospital for Sick Children, 686 Bay St, Toronto, ON, M5G 0A4, Canada
| | - Dhia Azzouz
- Lung Innate Immunity Research Laboratory, Program in Translational Medicine, Peter Gilgan Centre for Research and Learning, The Hospital for Sick Children, 686 Bay St, Toronto, ON, M5G 0A4, Canada
| | - Lakshmi P Kotra
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Ontario, M5S 3M2, Canada; Center for Molecular Design and Preformulations, Toronto General Research Institute, University Health Network, 101 College Street, Toronto, Ontario, M5G 1L7, Canada
| | - Neil Sweezey
- Lung Innate Immunity Research Laboratory, Program in Translational Medicine, Peter Gilgan Centre for Research and Learning, The Hospital for Sick Children, 686 Bay St, Toronto, ON, M5G 0A4, Canada; Departments of Paediatrics, Physiology and Institute of Medical Sciences, Faculty of Medicine, University of Toronto, Toronto, ON, M5G 1X8, Canada
| | - Nades Palaniyar
- Lung Innate Immunity Research Laboratory, Program in Translational Medicine, Peter Gilgan Centre for Research and Learning, The Hospital for Sick Children, 686 Bay St, Toronto, ON, M5G 0A4, Canada; Departments of Laboratory Medicine and Pathobiology and Institute of Medical Sciences, Faculty of Medicine, University of Toronto, Toronto, ON, M5S 1A8, Canada.
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11
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Noutsios GT, Willis AL, Ledford JG, Chang EH. Novel role of surfactant protein A in bacterial sinusitis. Int Forum Allergy Rhinol 2017; 7:897-903. [PMID: 28727907 DOI: 10.1002/alr.21985] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Revised: 05/22/2017] [Accepted: 06/08/2017] [Indexed: 01/22/2023]
Abstract
BACKGROUND Chronic rhinosinusitis (CRS) is a common inflammatory disorder of the upper airway characterized by chronic inflammation and significant sinonasal remodeling. CRS is comprised of 2 major subgroups, based on whether polyps are present or absent. In some cases, it is characterized by colonization with opportunistic pathogens such as Pseudomonas aeruginosa (PA), Staphylococcus aureus, and other bacteria. The innate immune system of the sinonasal epithelium is the first line of defense against inhaled pathogens. Surfactant protein A (SP-A) is a member of the collectin family secreted by the airway epithelia and plays a critical role in airway innate immunity, as it can aggregate bacteria. We hypothesized that SP-A plays a role in bacterial CRS. METHODS Air-liquid interface (ALI) cultures of nasal epithelial cells were derived from human ex-vivo healthy and CRS sinus tissues (n = 26) and challenged with PA. SP-A levels were measured with western blot and quantitative reverse transcript-polymerase chain reaction (qRT-PCR) in ALI and sinus tissues. RESULTS We determined that SP-A: (i) mRNA and protein levels are increased significantly in CRS tissues compared with healthy sinuses; (ii) although primarily expressed in the lung, it is also synthesized and expressed in sinonasal epithelia; (ii) is expressed in the sinuses of an SP-A humanized transgenic mouse but not in SP-A knockout mice; (iv) mRNA levels are upregulated significantly during PA challenge, but protein levels are downregulated 4 hours postchallenge and upregulated at 12 hours. CONCLUSION Our data suggest that SP-A is expressed in the sinuses and that it plays a role in the sinus innate immune responses during bacterial infections.
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Affiliation(s)
- George T Noutsios
- Department of Otolaryngology-Head & Neck Surgery, University of Arizona College of Medicine, Tucson, AZ
| | - Amanda L Willis
- Department of Otolaryngology-Head & Neck Surgery, University of Arizona College of Medicine, Tucson, AZ
| | - Julie G Ledford
- Department of Medicine & Immunobiology, University of Arizona College of Medicine, Tucson, AZ
| | - Eugene H Chang
- Department of Otolaryngology-Head & Neck Surgery, University of Arizona College of Medicine, Tucson, AZ
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12
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Que Y, Shen X. Changes in blood monocyte Toll-like receptor and serum surfactant protein A reveal a pathophysiological mechanism for community-acquired pneumonia in patients with type 2 diabetes. Intern Med J 2016; 46:213-9. [PMID: 26648341 DOI: 10.1111/imj.12978] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2015] [Revised: 11/29/2015] [Accepted: 12/01/2015] [Indexed: 01/04/2023]
Abstract
BACKGROUND The lung is one of the target organs of microangiopathy in diabetes mellitus (DM); patients with type 2 diabetes mellitus (T2DM) are vulnerable to pneumonia, and a variety of pathophysiological mechanisms has been described. AIM This study aimed to determine the pathophysiological mechanism of community-acquired pneumonia (CAP) in T2DM patients. METHODS A total of 90 individuals was included in this study comprised of three groups (n = 30): healthy control, T2DM and T2DM+ CAP groups. Toll-like receptor (TLR)2 and 4 protein and messenger RNA expression in peripheral blood monocytes(PBMC) was assessed by western blot and reverse transcription-polymerase chain reaction, respectively, and surfactant protein A (SP-A) levels were examined in serum samples by enzyme-linked immunosorbent assay. RESULTS In T2DM and T2DM+CAP groups, levels of both TLR2/4 protein and mRNA in PBMC were decreased compared with controls (P <0.05), with lower levels observed in the T2DM+CAP group in comparison with T2DM patients (P <0.05). The serum SP-A levels in T2DM+CAP individuals were significantly higher than the values obtained for T2DM patients (P <0.05). It also showed apparent increases when compared with that in controls although no statistical significance was detected. CONCLUSION In T2DM patients with pneumonia, TLR2/4 levels in PBMC and serum SP-A were altered, maybe playing an important role in the susceptibility to pneumonia in T2DM patients.
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Affiliation(s)
- Y Que
- Department of Endocrinology and Metabolism, Zhongnanshan Hospital Xiamen University, Xiamen, China
| | - X Shen
- Department of Endocrinology and Metabolism, Zhongnanshan Hospital Xiamen University, Xiamen, China
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Ujma S, Horsnell WGC, Katz AA, Clark HW, Schäfer G. Non-Pulmonary Immune Functions of Surfactant Proteins A and D. J Innate Immun 2016; 9:3-11. [PMID: 27794581 DOI: 10.1159/000451026] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2016] [Accepted: 09/26/2016] [Indexed: 11/19/2022] Open
Abstract
Surfactant proteins A (SP-A) and D (SP-D) are established as essential components of our innate immune system for protecting the lung from pathogens and allergens. They essentially exert their protective functions by regulating pulmonary homeostasis. Both proteins are however widely expressed throughout the body, including the female reproductive tract, urinary tract, gastrointestinal tract, the eye, ear, nasal compartment, central nervous system, the coronary artery and the skin. The functions of SP-A and SP-D at these sites are a relatively underinvestigated area, but it is emerging that both SP-A and SP-D contribute significantly to the regulation of inflammation and protection from infection at these sites. This review presents our current understanding of the roles of SP-A and SP-D in non-pulmonary sites.
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Affiliation(s)
- Sylvia Ujma
- UCT Receptor Biology Research Unit, Division of Medical Biochemistry and Structural Biology, Department of Integrative Biomedical Sciences, University of Cape Town, Cape Town, South Africa
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14
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Kumral A, Iscan B, Engur D, Tuzun F, Ozbal S, Ergur BU, Kaynak Turkmen M, Duman N, Ozkan H. Intranasal surfactant protein D as neuroprotective rescue in a neonatal rat model of periventricular leukomalacia. J Matern Fetal Neonatal Med 2016; 30:446-451. [PMID: 27109442 DOI: 10.1080/14767058.2016.1174996] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
BACKGROUND Periventricular leukomalacia (PVL) is the leading cause of neurocognitive deficits in children with prematurity. We previously hypothesized that surfactant protein D (SPD) with its ability to bind toll-like receptors may have a possible ameliorating effect in PVL. METHODS Three groups were defined as: LPS-administered and postnatal intranasal saline administered group, LPS-administered and postnatal intranasal SPD-treated group, and control group. Twenty-eight offspring rats were reared with their dams until their sacrifice for histological evaluation on day 7. RESULTS A significant loss of brain weight occurred in the LPS group compared with controls. The postnatal intranasal SPD treatment significantly reduced the number of TUNEL-positive cells in the periventricular white matter as compared with the LPS-treated group. Compared with the control group, LPS injection in the rat brain significantly reduced the MBP-positive staining. Postnatal SPD treatment greatly prevented LPS-stimulated loss of MBP staining. CONCLUSIONS Present study demonstrated a neuroprotective effect of SPD in a rat model of PVL. Our results offer future implications towards increasing our understanding about multifactorial mechanisms underlying periventricular leukomalacia and developing plausible therapeutic strategies in order to prevent neurocognitive deficits in preterm infants.
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Affiliation(s)
- Abdullah Kumral
- a Department of Pediatrics , Division of Neonatology, School of Medicine, Dokuz Eylul University , Izmir , Turkey
| | - Burcin Iscan
- a Department of Pediatrics , Division of Neonatology, School of Medicine, Dokuz Eylul University , Izmir , Turkey
| | - Defne Engur
- b Department of Pediatrics , Division of Neonatology, School of Medicine, Adnan Menderes University , Aydin , Turkey , and
| | - Funda Tuzun
- a Department of Pediatrics , Division of Neonatology, School of Medicine, Dokuz Eylul University , Izmir , Turkey
| | - Seda Ozbal
- c Department of Histology , School of Medicine, Dokuz Eylul University , Izmir , Turkey
| | - Bekir Ugur Ergur
- c Department of Histology , School of Medicine, Dokuz Eylul University , Izmir , Turkey
| | - Munevver Kaynak Turkmen
- b Department of Pediatrics , Division of Neonatology, School of Medicine, Adnan Menderes University , Aydin , Turkey , and
| | - Nuray Duman
- a Department of Pediatrics , Division of Neonatology, School of Medicine, Dokuz Eylul University , Izmir , Turkey
| | - Hasan Ozkan
- a Department of Pediatrics , Division of Neonatology, School of Medicine, Dokuz Eylul University , Izmir , Turkey
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15
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Tengood JE, Levy RJ, Stachelek SJ. The use of CD47-modified biomaterials to mitigate the immune response. Exp Biol Med (Maywood) 2016; 241:1033-41. [PMID: 27190273 DOI: 10.1177/1535370216647130] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Addressing the aberrant interactions between immune cells and biomaterials represents an unmet need in biomaterial research. Although progress has been made in the development of bioinert coatings, identifying and targeting relevant cellular and molecular pathways can provide additional therapeutic strategies to address this major healthcare concern. To that end, we describe the immune inhibitory motif, receptor-ligand pairing of signal regulatory protein alpha and its cognate ligand CD47 as a potential signaling pathway to enhance biocompatibility. The goals of this article are to detail the known roles of CD47-signal regulatory protein alpha signal transduction pathway and to describe how immobilized CD47 can be used to mitigate the immune response to biomaterials. Current applications of CD47-modified biomaterials will also be discussed herein.
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Affiliation(s)
- Jillian E Tengood
- Division of Cardiology, Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA Perelman School of Medicine, The University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Robert J Levy
- Division of Cardiology, Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA Perelman School of Medicine, The University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Stanley J Stachelek
- Division of Cardiology, Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA Perelman School of Medicine, The University of Pennsylvania, Philadelphia, PA 19104, USA
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16
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Sun Y, Qiu X, Wu G, Wang J, Li J, Tang H, Xia Z. The effects of porcine pulmonary surfactant on smoke inhalation injury. J Surg Res 2015; 198:200-7. [PMID: 26073349 DOI: 10.1016/j.jss.2015.05.019] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2015] [Revised: 05/04/2015] [Accepted: 05/12/2015] [Indexed: 11/16/2022]
Abstract
BACKGROUND Our previous study, consistent with others, demonstrated that administering an exogenous surfactant was a potential therapy for acute lung injury and acute respiratory distress syndrome. However, the underlying mechanisms remain largely unknown. In the present study, we investigated the effect of instilled porcine pulmonary surfactant (PPS) on rat inhalation injury model induced by smoke and the possible mechanism. MATERIALS AND METHODS Fifteen Sprague-Dawley rats were equally randomized to three groups as follows (n = 5 in each group): sham control group (C group), inhalation injury group (II group), and inhalation injury + PPS treatment group (PPS group). Lung tissues were assayed for wet/dry ratio, histologic, terminal dUTP nick-end labeling staining, and Western blotting examinations. The myeloperoxidase activity was tested in lung tissues as well. Bronchoalveolar lavage fluid was collected to determine the total protein concentrations, inflammatory cytokines, surfactant protein A (SP-A), and SP-D. RESULTS Our present work exhibited that PPS had therapeutic effects on smoke inhalation injury reflected by significant increase of PaO2 values, improved edema status, decreased vascular permeability, amelioration of lung histopathology, and reduction of inflammatory response. In addition, PPS treatment could increase endogenous SP-A levels both in lung tissue and bronchoalveolar lavage fluid. Further correlation analysis showed that SP-A was negatively correlated with both myeloperoxidase activity and interleukin 8 levels. CONCLUSIONS These results indicate that PPS can attenuate smoke-induced inhalation injury at least partly through stimulating production of endogenous SP-A and inhibiting the release of proinflammatory cytokines such as interleukin 8. The increasing production of endogenous SP-A may be due to the antioxidant effect of PPS, which contains no SP-A.
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Affiliation(s)
- Yu Sun
- Department of Burn Surgery, Changhai Hospital, Second Military Medical University, Shanghai, P. R. China
| | - Xiaochen Qiu
- Department of General Surgery, 309th Hospital of PLA, Beijing, P.R. China
| | - Guosheng Wu
- Department of Burn Surgery, Changhai Hospital, Second Military Medical University, Shanghai, P. R. China
| | - Junjie Wang
- Department of Burn Surgery, Changhai Hospital, Second Military Medical University, Shanghai, P. R. China
| | - Jiahui Li
- Department of Burn Surgery, Changhai Hospital, Second Military Medical University, Shanghai, P. R. China
| | - Hao Tang
- Department of Respiratory Medicine, Changzheng Hospital, Second Military Medical University, Shanghai, P. R. China
| | - Zhaofan Xia
- Department of Burn Surgery, Changhai Hospital, Second Military Medical University, Shanghai, P. R. China.
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17
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Ou CY, Chen CZ, Hsiue TR, Lin SH, Wang JY. Genetic variants of pulmonary SP-D predict disease outcome of COPD in a Chinese population. Respirology 2014; 20:296-303. [DOI: 10.1111/resp.12427] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2014] [Revised: 07/25/2014] [Accepted: 09/16/2014] [Indexed: 12/28/2022]
Affiliation(s)
- Chih-Ying Ou
- Division of Chest Medicine; Department of Internal Medicine
| | | | | | | | - Jiu-Yao Wang
- Division of Allergy and Clinical Immunology; Department of Pediatrics; National Cheng Kung University Hospital; College of Medicine; National Cheng Kung University; Tainan
- Graduate Institute of Integrated Medicine; School of Chinese Medicine; China Medical University; Taichung Taiwan
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18
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Nayak A, Dodagatta-Marri E, Tsolaki AG, Kishore U. An Insight into the Diverse Roles of Surfactant Proteins, SP-A and SP-D in Innate and Adaptive Immunity. Front Immunol 2012; 3:131. [PMID: 22701116 PMCID: PMC3369187 DOI: 10.3389/fimmu.2012.00131] [Citation(s) in RCA: 128] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2011] [Accepted: 05/07/2012] [Indexed: 01/20/2023] Open
Abstract
Surfactant proteins SP-A and SP-D are hydrophilic, collagen-containing calcium-dependent lectins, which appear to have a range of innate immune functions at pulmonary as well as extrapulmonary sites. These proteins bind to target ligands on pathogens, allergens, and apoptotic cells, via C-terminal homotrimeric carbohydrate recognition domains, while the collagen region brings about the effector functions via its interaction with cell surface receptors. SP-A and SP-D deal with various pathogens, using a range of innate immune mechanisms such as agglutination/aggregation, enhancement of phagocytosis, and killing mechanisms by phagocytic cells and direct growth inhibition. SP-A and SP-D have also been shown to be involved in the control of pulmonary inflammation including allergy and asthma. Emerging evidence suggest that SP-A and SP-D are capable of linking innate immunity with adaptive immunity that includes modulation of dendritic cell function and helper T cell polarization. This review enumerates immunological properties of SP-A and SP-D inside and outside lungs and discusses their importance in human health and disease.
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Affiliation(s)
- Annapurna Nayak
- Centre for Infection, Immunity and Disease Mechanisms, School of Health Sciences and Social Care, Brunel University London, UK
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19
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Willems CH, Urlichs F, Seidenspinner S, Kunzmann S, Speer CP, Kramer BW. Poractant alfa (Curosurf®) increases phagocytosis of apoptotic neutrophils by alveolar macrophages in vivo. Respir Res 2012; 13:17. [PMID: 22405518 PMCID: PMC3310829 DOI: 10.1186/1465-9921-13-17] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2011] [Accepted: 03/09/2012] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Clearance of apoptotic neutrophils in the lung is an essential process to limit inflammation, since they could become a pro-inflammatory stimulus themselves. The clearance is partially mediated by alveolar macrophages, which phagocytose these apoptotic cells. The phagocytosis of apoptotic immune cells by monocytes in vitro has been shown to be augmented by several constituents of pulmonary surfactant, e.g. phospholipids and hydrophobic surfactant proteins. In this study, we assessed the influence of exogenous poractant alfa (Curosurf®) instillation on the in vivo phagocytosis of apoptotic neutrophils by alveolar macrophages. METHODS Poractant alfa (200 mg/kg) was instilled intratracheally in the lungs of three months old adult male C57/Black 6 mice, followed by apoptotic neutrophil instillation. Bronchoalveloar lavage was performed and alveolar macrophages and neutrophils were counted. Phagocytosis of apoptotic neutrophils was quantified by determining the number of apoptotic neutrophils per alveolar macrophages. RESULTS Exogenous surfactant increased the number of alveolar macrophages engulfing apoptotic neutrophils 2.6 fold. The phagocytosis of apoptotic neutrophils was increased in the presence of exogenous surfactant by a 4.7 fold increase in phagocytosed apoptotic neutrophils per alveolar macrophage. CONCLUSIONS We conclude that the anti-inflammatory properties of surfactant therapy may be mediated in part by increased numbers of alveolar macrophages and increased phagocytosis of apoptotic neutrophils by alveolar macrophages.
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Affiliation(s)
- Coen Hmp Willems
- Department of Pediatrics, School for Mental Health and Neuroscience (NUTRIM), School for Oncology and Developmental Biology (GROW), Maastricht University Medical Centre, Maastricht, The Netherlands
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20
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Scotton CJ, Chambers RC. Innate Immunity in Lung Fibrosis: A Therapeutic Role for Surfactant Protein D? Am J Respir Crit Care Med 2012; 185:471-3. [DOI: 10.1164/rccm.201112-2193ed] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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21
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Kang YH, Urban BC, Sim RB, Kishore U. Human complement Factor H modulates C1q-mediated phagocytosis of apoptotic cells. Immunobiology 2011; 217:455-64. [PMID: 22088229 DOI: 10.1016/j.imbio.2011.10.008] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2011] [Revised: 10/04/2011] [Accepted: 10/18/2011] [Indexed: 11/19/2022]
Abstract
Complement is implicated in the clearance of apoptotic cells by phagocytes. Deficiencies in early complement components, particularly C1q, are associated with an increased risk of the development of systemic lupus erythematosus. C1q is considered to be important in this process through interaction with apoptotic cells and phagocytes. In the present study, we confirm that apoptotic cells are recognized not only by C1q but also by the complement regulatory protein Factor H. Both C1q and Factor H bind to apoptotic cells in a dose-dependent and saturable manner. We further examined the role of C1q and Factor H in the clearance of apoptotic cells by monocytes. C1q enhanced uptake/adhesion of apoptotic cells by monocytes whereas Factor H alone had no effect on this process. However, when both C1q and Factor H were present on the apoptotic cell surface, C1q-mediated enhancement of uptake/adhesion of the apoptotic cells by monocytes was reduced. This effect of Factor H also occurred if monocytes were pre-treated with Factor H, and then exposed to C1q-coated apoptotic cells. The results were consistent with Factor H interacting with monocytes through the integrin CD11b/CD18. We conclude that under physiological conditions, Factor H may be important in controlling the inflammation which might arise from C1q deposition on apoptotic cells.
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Affiliation(s)
- Yu-Hoi Kang
- MRC Immunochemistry Unit, Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK
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22
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Natural IgM and innate immune collectin SP-D bind to late apoptotic cells and enhance their clearance by alveolar macrophages in vivo. Mol Immunol 2010; 48:37-47. [DOI: 10.1016/j.molimm.2010.09.014] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2010] [Revised: 09/16/2010] [Accepted: 09/22/2010] [Indexed: 11/16/2022]
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23
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Identification of four novel DC-SIGN ligands on Mycobacterium bovis BCG. Protein Cell 2010; 1:859-70. [PMID: 21203928 PMCID: PMC4875224 DOI: 10.1007/s13238-010-0101-3] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2010] [Accepted: 08/03/2010] [Indexed: 11/18/2022] Open
Abstract
Dendritic-cell-specific intercellular adhesion molecule-3-grabbing non-integrin (DC-SIGN; CD209) has an important role in mediating adherence of Mycobacteria species, including M. tuberculosis and M. bovis BCG to human dendritic cells and macrophages, in which these bacteria can survive intracellularly. DC-SIGN is a C-type lectin, and interactions with mycobacterial cells are believed to occur via mannosylated structures on the mycobacterial surface. Recent studies suggest more varied modes of binding to multiple mycobacterial ligands. Here we identify, by affinity chromatography and mass-spectrometry, four novel ligands of M. bovis BCG that bind to DC-SIGN. The novel ligands are chaperone protein DnaK, 60 kDa chaperonin-1 (Cpn60.1), glyceraldehyde-3 phosphate dehydrogenase (GAPDH) and lipoprotein lprG. Other published work strongly suggests that these are on the cell surface. Of these ligands, lprG appears to bind DC-SIGN via typical proteinglycan interactions, but DnaK and Cpn60.1 binding do not show evidence of carbohydrate-dependent interactions. LprG was also identified as a ligand for DC-SIGNR (L-SIGN; CD299) and the M. tuberculosis orthologue of lprG has been found previously to interact with human toll-like receptor 2. Collectively, these findings offer new targets for combating mycobacterial adhesion and within-host survival, and reinforce the role of DCSIGN as an important host ligand in mycobacterial infection.
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Surface-bound myeloperoxidase is a ligand for recognition of late apoptotic neutrophils by human lung surfactant proteins A and D. Protein Cell 2010; 1:563-72. [PMID: 21204009 DOI: 10.1007/s13238-010-0076-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2010] [Accepted: 05/28/2010] [Indexed: 10/19/2022] Open
Abstract
Surfactant proteins A (SP-A) and D (SP-D), both members of the collectin family, play a well established role in apoptotic cell recognition and clearance. Recent in vitro data show that SP-A and SP-D interact with apoptotic neutrophils in a distinct manner. SP-A and SP-D bind in a Ca(2+)-dependent manner to viable and early apoptotic neutrophils whereas the much greater interaction with late apoptotic neutrophils is Ca(2+)-independent. Cell surface molecules on the apoptotic target cells responsible for these interactions had not been identified and this study was done to find candidate target molecules. Myeloperoxidase (MPO), a specific intracellular defense molecule of neutrophils that becomes exposed on the outside of the cell upon apoptosis, was identified by affinity purification, mass-spectrometry and western blotting as a novel binding molecule for SP-A and SP-D. To confirm its role in recognition, it was shown that purified immobilised MPO binds SP-A and SP-D, and that MPO is surface-exposed on late apoptotic neutrophils. SP-A and SP-D inhibit binding of an anti-MPO monoclonal Ab to late apoptotic cells. Fluorescence microscopy confirmed that anti-MPO mAb and SP-A/SP-D colocalise on late apoptotic neutrophils. Desmoplakin was identified as a further potential ligand for SP-A, and neutrophil defensin as a target for both proteins.
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25
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Lin KW, Jen KY, Suarez CJ, Crouch EC, Perkins DL, Finn PW. Surfactant protein D-mediated decrease of allergen-induced inflammation is dependent upon CTLA4. THE JOURNAL OF IMMUNOLOGY 2010; 184:6343-9. [PMID: 20435925 DOI: 10.4049/jimmunol.0901947] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Pulmonary surfactant protein D (SP-D), a member of the collectin family, is an innate immune molecule critical for defense that can also modulate adaptive immune responses. We previously showed that SP-D-deficient mice exhibit enhanced allergic responses and that SP-D induction requires lymphocytes. Thus, we postulated that SP-D may decrease adaptive allergic responses through interaction with T cells. In this study, we used two forms of SP-D, a dodecamer and a shorter fragment containing the trimeric neck and carbohydrate recognition domains (SP-D NCRD). Both forms decreased immune responses in vitro and in a murine model of pulmonary inflammation. SP-D NCRD increased transcription of CTLA4, a negative regulator of T cell activation, in T cells. SP-D NCRD no longer decreased lymphoproliferation and IL-2 cytokine production when CTLA4 signals were abrogated. Administration of SP-D NCRD in vivo no longer decreased allergen induced responses when CTLA4 was inhibited. Our results indicate that SP-D decreases allergen responses, an effect that may be mediated by increase of CTLA4 in T cells.
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Affiliation(s)
- Ko-Wei Lin
- Division of Pulmonary and Critical Medicine, University of California, San Diego, La Jolla, CA 92093, USA
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Surfactant protein A (SP-A) binds to phosphatidylserine and competes with annexin V binding on late apoptotic cells. Protein Cell 2010; 1:188-97. [PMID: 21203987 DOI: 10.1007/s13238-010-0024-z] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2009] [Accepted: 12/24/2009] [Indexed: 12/16/2022] Open
Abstract
The role of surfactant protein A (SP-A) in the recognition and clearance of apoptotic cells is well established, but to date, it is still not clear which surface molecules of apoptotic cells are involved in the process. Here we present evidence that phosphatidylserine (PS) is a relevant binding molecule for human SP-A. The binding is Ca(2+)-dependent and is not inhibited by mannose, suggesting that the sugar-binding site of the carbohydrate recognition domain (CRD) of SP-A is not involved. Flow cytometry studies on apoptotic Jurkat cells revealed apparent inhibition of annexin V binding by increasing concentrations of SP-A in late apoptotic but not early apoptotic cells, and this was consistent for Jurkat cells and neutrophils. Supporting these data, confocal microscopy results show a co-localisation of annexin V and SP-A in late apoptotic but not early apoptotic cells. However, we cannot conclude that this inhibition is exclusively due to the binding of SP-A to PS on the cell surface, as annexin V is not wholly specific for PS and SP-A also interacts with other phospholipids that might become exposed on the apoptotic cell surface.
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