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Elucidating the enhanced binding affinity of a double mutant SP-D with trimannose on the influenza A virus using molecular dynamics. Comput Struct Biotechnol J 2022; 20:4984-5000. [PMID: 36097510 PMCID: PMC9452405 DOI: 10.1016/j.csbj.2022.08.045] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2022] [Revised: 08/19/2022] [Accepted: 08/20/2022] [Indexed: 12/02/2022] Open
Abstract
The Asp325Ala mutation in SP-D promotes a trimannose conformational change to a more stable state. The Arg343Val mutation in SP-D reduces its interaction with Glu333 to increase the binding affinity with trimannose. The Arg343Val mutation contributes more to the increase of SP-D’s binding affinity with trimannose than Asp325Ala.
Surfactant protein D (SP-D) is an essential component of the human pulmonary surfactant system, which is crucial in the innate immune response against glycan-containing pathogens, including Influenza A viruses (IAV) and SARS-CoV-2. Previous studies have shown that wild-type (WT) SP-D can bind IAV but exhibits poor antiviral activities. However, a double mutant (DM) SP-D consisting of two point mutations (Asp325Ala and Arg343Val) inhibits IAV more potently. Presently, the structural mechanisms behind the point mutations’ effects on SP-D’s binding affinity with viral surface glycans are not fully understood. Here we use microsecond-scale, full-atomistic molecular dynamics (MD) simulations to understand the molecular mechanism of mutation-induced SP-D’s higher antiviral activity. We find that the Asp325Ala mutation promotes a trimannose conformational change to a more stable state. Arg343Val increases the binding with trimannose by increasing the hydrogen bonding interaction with Glu333. Free energy perturbation (FEP) binding free energy calculations indicate that the Arg343Val mutation contributes more to the increase of SP-D’s binding affinity with trimannose than Asp325Ala. This study provides a molecular-level exploration of how the two mutations increase SP-D binding affinity with trimannose, which is vital for further developing preventative strategies for related diseases.
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Key Words
- CRD, Carbohydrate Recognition Domain
- DM, Double mutant
- FEP, Free Energy Perturbation
- Free Energy Perturbation
- HA, Hemagglutinin
- IAV, Influenza A Viruses
- MD, Molecular Dynamics
- Molecular Dynamics Simulation
- PAP, Pulmonary Alveolar Proteinosis
- PME, Particle Mesh Ewald
- PS, Pulmonary Surfactant
- Protein-Glycan Complexes
- RMSD, Root Mean Square Deviation
- RMSF, Root Mean Square Fluctuation
- SP-A, Surfactant Protein A
- SP-B, Surfactant Protein B
- SP-C, Surfactant Protein C
- SP-D, Surfactant Protein D
- Surfactant Protein D
- WT, Wild-type
- λ-REMD, λ-Replica-Exchange Molecular Dynamics
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2
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The Potential Role of SP-G as Surface Tension Regulator in Tear Film: From Molecular Simulations to Experimental Observations. Int J Mol Sci 2022; 23:ijms23105783. [PMID: 35628592 PMCID: PMC9148136 DOI: 10.3390/ijms23105783] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Revised: 05/11/2022] [Accepted: 05/18/2022] [Indexed: 12/07/2022] Open
Abstract
The ocular surface is in constant interaction with the environment and with numerous pathogens. Therefore, complex mechanisms such as a stable tear film and local immune defense mechanisms are required to protect the eye. This study describes the detection, characterization, and putative role of surfactant protein G (SP-G/SFTA2) with respect to wound healing and surface activity. Bioinformatic, biochemical, and immunological methods were combined to elucidate the role of SP-G in tear film. The results show the presence of SP-G in ocular surface tissues and tear film (TF). Increased expression of SP-G was demonstrated in TF of patients with dry eye disease (DED). Addition of recombinant SP-G in combination with lipids led to an accelerated wound healing of human corneal cells as well as to a reduction of TF surface tension. Molecular modeling of TF suggest that SP-G may regulate tear film surface tension and improve its stability through specific interactions with lipids components of the tear film. In conclusion, SP-G is an ocular surface protein with putative wound healing properties that can also reduce the surface tension of the tear film.
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3
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Nissen CG, Mosley DD, Kharbanda KK, Katafiasz DM, Bailey KL, Wyatt TA. Malondialdehyde Acetaldehyde-Adduction Changes Surfactant Protein D Structure and Function. Front Immunol 2022; 13:866795. [PMID: 35669781 PMCID: PMC9164268 DOI: 10.3389/fimmu.2022.866795] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Accepted: 04/13/2022] [Indexed: 11/23/2022] Open
Abstract
Alcohol consumption with concurrent cigarette smoking produces malondialdehyde acetaldehyde (MAA)-adducted lung proteins. Lung surfactant protein D (SPD) supports innate immunity via bacterial aggregation and lysis, as well as by enhancing macrophage-binding and phagocytosis. MAA-adducted SPD (SPD-MAA) has negative effects on lung cilia beating, macrophage function, and epithelial cell injury repair. Because changes in SPD multimer structure are known to impact SPD function, we hypothesized that MAA-adduction changes both SPD structure and function. Purified human SPD and SPD-MAA (1 mg/mL) were resolved by gel filtration using Sephadex G-200 and protein concentration of each fraction determined by Bradford assay. Fractions were immobilized onto nitrocellulose by slot blot and assayed by Western blot using antibodies to SPD and to MAA. Binding of SPD and SPD-MAA was determined fluorometrically using GFP-labeled Streptococcus pneumoniae (GFP-SP). Anti-bacterial aggregation of GFP-SP and macrophage bacterial phagocytosis were assayed by microscopy and permeability determined by bacterial phosphatase release. Viral injury was measured as LDH release in RSV-treated airway epithelial cells. Three sizes of SPD were resolved by gel chromatography as monomeric, trimeric, and multimeric forms. SPD multimer was the most prevalent, while the majority of SPD-MAA eluted as trimer and monomer. SPD dose-dependently bound to GFP-SP, but SPD-MAA binding to bacteria was significantly reduced. SPD enhanced, but MAA adduction of SPD prevented, both aggregation and macrophage phagocytosis of GFP-SP. Likewise, SPD increased bacterial permeability while SPD-MAA did not. In the presence of RSV, BEAS-2B cell viability was enhanced by SPD, but not protected by SPD-MAA. Our results demonstrate that MAA adduction changes the quaternary structure of SPD from multimer to trimer and monomer leading to a decrease in the native anti-microbial function of SPD. These findings suggest one mechanism for increased pneumonia observed in alcohol use disorders.
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Affiliation(s)
- Claire G. Nissen
- Department of Environmental, Agricultural and Occupational Health, College of Public Health, University of Nebraska Medical Center, Omaha, NE, United States
| | - Deanna D. Mosley
- Department of Internal Medicine, College of Medicine, University of Nebraska Medical Center, Omaha, NE, United States
| | - Kusum K. Kharbanda
- Department of Internal Medicine, College of Medicine, University of Nebraska Medical Center, Omaha, NE, United States
- Research Service Veterans Affairs Nebraska-Western Iowa Health Care System, Omaha, NE, United States
| | - Dawn M. Katafiasz
- Department of Internal Medicine, College of Medicine, University of Nebraska Medical Center, Omaha, NE, United States
| | - Kristina L. Bailey
- Department of Internal Medicine, College of Medicine, University of Nebraska Medical Center, Omaha, NE, United States
- Research Service Veterans Affairs Nebraska-Western Iowa Health Care System, Omaha, NE, United States
| | - Todd A. Wyatt
- Department of Environmental, Agricultural and Occupational Health, College of Public Health, University of Nebraska Medical Center, Omaha, NE, United States
- Department of Internal Medicine, College of Medicine, University of Nebraska Medical Center, Omaha, NE, United States
- Research Service Veterans Affairs Nebraska-Western Iowa Health Care System, Omaha, NE, United States
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4
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Pioselli B, Salomone F, Mazzola G, Amidani D, Sgarbi E, Amadei F, Murgia X, Catinella S, Villetti G, De Luca D, Carnielli V, Civelli M. Pulmonary surfactant: a unique biomaterial with life-saving therapeutic applications. Curr Med Chem 2021; 29:526-590. [PMID: 34525915 DOI: 10.2174/0929867328666210825110421] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Revised: 06/26/2021] [Accepted: 06/29/2021] [Indexed: 11/22/2022]
Abstract
Pulmonary surfactant is a complex lipoprotein mixture secreted into the alveolar lumen by type 2 pneumocytes, which is composed by tens of different lipids (approximately 90% of its entire mass) and surfactant proteins (approximately 10% of the mass). It is crucially involved in maintaining lung homeostasis by reducing the values of alveolar liquid surface tension close to zero at end-expiration, thereby avoiding the alveolar collapse, and assembling a chemical and physical barrier against inhaled pathogens. A deficient amount of surfactant or its functional inactivation is directly linked to a wide range of lung pathologies, including the neonatal respiratory distress syndrome. This paper reviews the main biophysical concepts of surfactant activity and its inactivation mechanisms, and describes the past, present and future roles of surfactant replacement therapy, focusing on the exogenous surfactant preparations marketed worldwide and new formulations under development. The closing section describes the pulmonary surfactant in the context of drug delivery. Thanks to its peculiar composition, biocompatibility, and alveolar spreading capability, the surfactant may work not only as a shuttle to the branched anatomy of the lung for other drugs but also as a modulator for their release, opening to innovative therapeutic avenues for the treatment of several respiratory diseases.
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Affiliation(s)
| | | | | | | | - Elisa Sgarbi
- Preclinical R&D, Chiesi Farmaceutici, Parma. Italy
| | | | - Xabi Murgia
- Department of Biotechnology, GAIKER Technology Centre, Zamudio. Spain
| | | | | | - Daniele De Luca
- Division of Pediatrics and Neonatal Critical Care, Antoine Béclère Medical Center, APHP, South Paris University Hospitals, Paris, France; Physiopathology and Therapeutic Innovation Unit-U999, South Paris-Saclay University, Paris. France
| | - Virgilio Carnielli
- Division of Neonatology, G Salesi Women and Children's Hospital, Polytechnical University of Marche, Ancona. Italy
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5
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ARAKI M, OHTAKI T, KIMURA J, HOBO S, TAYA K, TSUNODA N, TANIYAMA H, TSUMAGARI S, NAMBO Y. Presence of surfactant proteins in the uteri and placentae of pregnant mares. J Vet Med Sci 2021; 83:1167-1172. [PMID: 34135243 PMCID: PMC8349814 DOI: 10.1292/jvms.20-0174] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2020] [Accepted: 05/18/2021] [Indexed: 11/22/2022] Open
Abstract
Immunohistochemical investigations of the expression of surfactant protein A (SP-A) and surfactant protein D (SP-D) in the uterine and placental tissues of 13 pregnant mares were performed using anti-horse monoclonal primary antibodies. Strong positive reactions for both SP-A and SP-D were observed in the trophoblasts in the microcotyledons of the placentae at 182 to 314 days of gestation; in uterine glandular epithelial cells, faint-to-weak reactions were observed during gestation. This study describes, for the first time, the changes in the SP-A and SP-D expression levels in the endometrium of mares during gestation; the SP-A and SP-D expression levels increased after the second trimester of gestation.
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Affiliation(s)
| | - Tadatoshi OHTAKI
- Department of Veterinary Medicine, College of Bioresource Sciences, Nihon University, Fujisawa, Kanagawa 252-0880, Japan
| | - Junpei KIMURA
- College of Veterinary Medicine, Seoul National University, Seoul 151-742, Korea
| | - Seiji HOBO
- Joint Faculty of Veterinary Medicine, Kagoshima University, Kagoshima, Kagoshima 890-0065, Japan
| | - Kazuyoshi TAYA
- Laboratory of Veterinary Physiology, Cooperative Department of Veterinary Medicine, Faculty of Agriculture, Tokyo University of
Agriculture and Technology, Fuchu, Tokyo 183-8509, Japan
- Shadai Corporation, 275 Hayakitagenbu, Abira-cho, Yufutsu-gun, Hokkaido 059-1432, Japan
| | - Nobuo TSUNODA
- Shadai Corporation, 275 Hayakitagenbu, Abira-cho, Yufutsu-gun, Hokkaido 059-1432, Japan
| | | | - Shigehisa TSUMAGARI
- Department of Veterinary Medicine, College of Bioresource Sciences, Nihon University, Fujisawa, Kanagawa 252-0880, Japan
| | - Yasuo NAMBO
- Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Hokkaido 080-8555, Japan
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6
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Arroyo R, Grant SN, Colombo M, Salvioni L, Corsi F, Truffi M, Ottolina D, Hurst B, Salzberg M, Prosperi D, Kingma PS. Full-Length Recombinant hSP-D Binds and Inhibits SARS-CoV-2. Biomolecules 2021; 11:1114. [PMID: 34439781 PMCID: PMC8393632 DOI: 10.3390/biom11081114] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Revised: 07/21/2021] [Accepted: 07/23/2021] [Indexed: 12/15/2022] Open
Abstract
SARS-CoV-2 infection of host cells is driven by binding of the SARS-CoV-2 spike-(S)-protein to lung type II pneumocytes, followed by virus replication. Surfactant protein SP-D, member of the front-line immune defense of the lungs, binds glycosylated structures on invading pathogens such as viruses to induce their clearance from the lungs. The objective of this study is to measure the pulmonary SP-D levels in COVID-19 patients and demonstrate the activity of SP-D against SARS-CoV-2, opening the possibility of using SP-D as potential therapy for COVID-19 patients. Pulmonary SP-D concentrations were measured in bronchoalveolar lavage samples from patients with corona virus disease 2019 (COVID-19) by anti-SP-D ELISA. Binding assays were performed by ELISAs. Protein bridge and aggregation assays were performed by gel electrophoresis followed by silver staining and band densitometry. Viral replication was evaluated in vitro using epithelial Caco-2 cells. Results indicate that COVID-19 patients (n = 12) show decreased pulmonary levels of SP-D (median = 68.9 ng/mL) when compared to levels reported for healthy controls in literature. Binding assays demonstrate that SP-D binds the SARS-CoV-2 glycosylated spike-(S)-protein of different emerging clinical variants. Binding induces the formation of protein bridges, the critical step of viral aggregation to facilitate its clearance. SP-D inhibits SARS-CoV-2 replication in Caco-2 cells (EC90 = 3.7 μg/mL). Therefore, SP-D recognizes and binds to the spike-(S)-protein of SARS-CoV-2 in vitro, initiates the aggregation, and inhibits viral replication in cells. Combined with the low levels of SP-D observed in COVID-19 patients, these results suggest that SP-D is important in the immune response to SARS-CoV-2 and that rhSP-D supplementation has the potential to be a novel class of anti-viral that will target SARS-CoV-2 infection.
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Affiliation(s)
- Raquel Arroyo
- Division of Neonatology and Pulmonary Biology, Cincinnati Children’s Hospital, Cincinnati, OH 45229, USA;
| | - Shawn N. Grant
- Airway Therapeutics Inc., Cincinnati, OH 45249, USA; (S.N.G.); (M.S.)
| | - Miriam Colombo
- NanoBio laboratory, Department of Biotechnology and Bioscience, University of Milano-Bicocca, 20126 Milano, Italy; (M.C.); (L.S.); (D.P.)
| | - Lucia Salvioni
- NanoBio laboratory, Department of Biotechnology and Bioscience, University of Milano-Bicocca, 20126 Milano, Italy; (M.C.); (L.S.); (D.P.)
| | - Fabio Corsi
- Istituti Clinici Scientifici Maugeri IRCCS, via Maugeri 4, 27100 Pavia, Italy; (F.C.); (M.T.)
| | - Marta Truffi
- Istituti Clinici Scientifici Maugeri IRCCS, via Maugeri 4, 27100 Pavia, Italy; (F.C.); (M.T.)
| | - Davide Ottolina
- Division of Anesthesiology and Intensive Care Medicine, ASST Fatebenefratelli Sacco, Luigi Sacco Hospital, University of Milan, 20157 Milano, Italy;
| | - Brett Hurst
- Institute for Antiviral Research, Utah State University, Logan, UT 84322, USA;
| | - Marc Salzberg
- Airway Therapeutics Inc., Cincinnati, OH 45249, USA; (S.N.G.); (M.S.)
| | - Davide Prosperi
- NanoBio laboratory, Department of Biotechnology and Bioscience, University of Milano-Bicocca, 20126 Milano, Italy; (M.C.); (L.S.); (D.P.)
| | - Paul S. Kingma
- Division of Neonatology and Pulmonary Biology, Cincinnati Children’s Hospital, Cincinnati, OH 45229, USA;
- Department of Pediatrics, University of Cincinnati, Cincinnati, OH 45229, USA
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7
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Arroyo R, Kingma PS. Surfactant protein D and bronchopulmonary dysplasia: a new way to approach an old problem. Respir Res 2021; 22:141. [PMID: 33964929 PMCID: PMC8105703 DOI: 10.1186/s12931-021-01738-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Accepted: 05/03/2021] [Indexed: 02/07/2023] Open
Abstract
Surfactant protein D (SP-D) is a collectin protein synthesized by alveolar type II cells in the lungs. SP-D participates in the innate immune defense of the lungs by helping to clear infectious pathogens and modulating the immune response. SP-D has shown an anti-inflammatory role by down-regulating the release of pro-inflammatory mediators in different signaling pathways such as the TLR4, decreasing the recruitment of inflammatory cells to the lung, and modulating the oxidative metabolism in the lungs. Recombinant human SP-D (rhSP-D) has been successfully produced mimicking the structure and functions of native SP-D. Several in vitro and in vivo experiments using different animal models have shown that treatment with rhSP-D reduces the lung inflammation originated by different insults, and that rhSP-D could be a potential treatment for bronchopulmonary dysplasia (BPD), a rare disease for which there is no effective therapy up to date. BPD is a complex disease in preterm infants whose incidence increases with decreasing gestational age at birth. Lung inflammation, which is caused by different prenatal and postnatal factors like infections, lung hyperoxia and mechanical ventilation, among others, is the key player in BPD. Exacerbated inflammation causes lung tissue injury that results in a deficient gas exchange in the lungs of preterm infants and frequently leads to long-term chronic lung dysfunction during childhood and adulthood. In addition, low SP-D levels and activity in the first days of life in preterm infants have been correlated with a worse pulmonary outcome in BPD. Thus, SP-D mediated functions in the innate immune response could be critical aspects of the pathogenesis in BPD and SP-D could inhibit lung tissue injury in this preterm population. Therefore, administration of rhSP-D has been proposed as promising therapy that could prevent BPD.
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Affiliation(s)
- Raquel Arroyo
- Division of Neonatology and Pulmonary Biology, Cincinnati Children's Hospital Medical Center, 3333 Burnet Ave. ML7029, Cincinnati, OH, 45229-3039, USA
| | - Paul S Kingma
- Division of Neonatology and Pulmonary Biology, Cincinnati Children's Hospital Medical Center, 3333 Burnet Ave. ML7029, Cincinnati, OH, 45229-3039, USA. .,Airway Therapeutics Inc, Cincinnati, OH, 45249, USA. .,Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH, 45229, USA.
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8
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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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9
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Attias Cohen S, Kingma PS, Whitsett J, Goldbart R, Traitel T, Kost J. SP-D loaded PLGA nanoparticles as drug delivery system for prevention and treatment of premature infant's lung diseases. Int J Pharm 2020; 585:119387. [DOI: 10.1016/j.ijpharm.2020.119387] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Revised: 03/21/2020] [Accepted: 04/28/2020] [Indexed: 01/13/2023]
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10
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Arroyo R, Echaide M, Wilmanowski R, Martín-González A, Batllori E, Galindo A, Rosenbaum JS, Moreno-Herrero F, Kingma PS, Pérez-Gil J. Structure and activity of human surfactant protein D from different natural sources. Am J Physiol Lung Cell Mol Physiol 2020; 319:L148-L158. [PMID: 32432921 DOI: 10.1152/ajplung.00007.2020] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Surfactant protein D (SP-D) is a C-type lectin that participates in the innate immune defense of lungs. It binds pathogens through its carbohydrate recognition domain in a calcium-dependent manner. Human surfactant protein D (hSP-D) has been routinely obtained from bronchoalveolar lavage of patients suffering from pulmonary alveolar proteinosis (PAP) and from amniotic fluid (AF). As a consequence of the disease, hSP-D obtained from PAP is found in higher amounts and is mainly composed of higher order oligomeric forms. However, PAP-hSP-D has never been directly compared with nonpathological human protein in terms of structure and biological activity. Moreover, the quantitative distribution of the different hSP-D oligomeric forms in human protein obtained from a natural source has never been evaluated. In this work, we have determined the quantitative distribution of AF-hSP-D oligomers, characterized the sugars attached through the N-glycosylation site of the protein, and compared the activity of hSP-D from AF and PAP with respect to their ability to bind and agglutinate bacteria. We have found that fuzzy balls (40%) are the most abundant oligomeric form in AF-hSP-D, very closely followed by dodecamers (33%), with both together constituting 73% of the protein mass. The glycan attached to the N-glycosylation site was found to be composed of fucose, galactose, sialic acid, and N-acetylglucosamine. Finally, in the functional assays performed, hSP-D obtained from PAP showed higher potency, probably as a consequence of its higher proportion of large oligomers compared with hSP-D from AF.
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Affiliation(s)
- Raquel Arroyo
- Department of Biochemistry, Faculty of Biology, Complutense University, Madrid, Spain.,Research Institut "Hospital 12 de Octubre (imas12)", Madrid, Spain
| | - Mercedes Echaide
- Department of Biochemistry, Faculty of Biology, Complutense University, Madrid, Spain.,Research Institut "Hospital 12 de Octubre (imas12)", Madrid, Spain
| | | | | | - Emma Batllori
- Research Institut "Hospital 12 de Octubre (imas12)", Madrid, Spain.,Department of Obstetrics and Gyneacology, Hospital Universitario 12 de Octubre, Madrid, Spain
| | - Alberto Galindo
- Research Institut "Hospital 12 de Octubre (imas12)", Madrid, Spain.,Department of Obstetrics and Gyneacology, Hospital Universitario 12 de Octubre, Madrid, Spain.,Fetal Medicine Unit-SAMID, Hospital Universitario 12 de Octubre, Madrid, Spain
| | - Jan S Rosenbaum
- Research and Development Department, Airway Therapeutics LLC, Cincinnati, Ohio
| | - Fernando Moreno-Herrero
- Department of Macromolecular Structures, National Center of Biotechnology, CSIC, Madrid, Spain
| | - Paul S Kingma
- Division of Neonatology and Pulmonary Biology, Perinatal Institute, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio.,Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, Ohio
| | - Jesús Pérez-Gil
- Department of Biochemistry, Faculty of Biology, Complutense University, Madrid, Spain.,Research Institut "Hospital 12 de Octubre (imas12)", Madrid, Spain
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11
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Yin B, Chan CKW, Liu S, Hong H, Wong SHD, Lee LKC, Ho LWC, Zhang L, Leung KCF, Choi PCL, Bian L, Tian XY, Chan MN, Choi CHJ. Intrapulmonary Cellular-Level Distribution of Inhaled Nanoparticles with Defined Functional Groups and Its Correlations with Protein Corona and Inflammatory Response. ACS NANO 2019; 13:14048-14069. [PMID: 31725257 DOI: 10.1021/acsnano.9b06424] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Concerns over the health risks associated with airborne exposure to ultrafine particles [PM0.1, or nanoparticles (NPs)] call for a comprehensive understanding in the interactions of inhaled NPs along their respiratory journey. We prepare a collection of polyethylene glycol-coated gold nanoparticles that bear defined functional groups commonly identified in atmospheric particulates (Au@PEG-X NPs, where X = OCH3, COOH, NH2, OH, or C12H25). Regardless of the functional group, these ∼50 nm NPs remain colloidally stable following aerosolization and incubation in bronchoalveolar lavage fluid (BALF), without pronouncedly crossing the air-blood barrier. The type of BALF proteins adhered onto the NPs is similar, but the composition of protein corona depends on functional group. By subjecting Balb/c mice to inhalation of Au@PEG-X NPs for 6 h, we demonstrate that the intrapulmonary distribution of NPs among the various types of cells (both found in BALF and isolated from the lavaged lung) and the acute inflammatory responses induced by inhalation are sensitive to the functional group of NPs and postinhalation period (0, 24, or 48 h). By evaluating the pairwise correlations between the three variables of "lung-nano" interactions (protein corona, intrapulmonary cellular-level distribution, and inflammatory response), we reveal strong statistical correlations between the (1) fractions of albumin or carbonyl reductase bound to NPs, (2) associations of inhaled NPs to neutrophils in BALF or macrophages in the lavaged lung, and (3) level of total protein in BALF. Our results provide insights into the effect of functional group on lung-nano interactions and health risks associated with inhalation of PM0.1.
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Affiliation(s)
| | | | | | | | | | | | | | | | - Ken Cham-Fai Leung
- Department of Chemistry , Hong Kong Baptist University , Kowloon , Hong Kong
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Mackay RA, Townsend JP, Calvert J, Anthony M, Wilkinson AR, Postle AD, Clark HW, Todd DA. Increased surfactant protein-D levels in the airways of preterm neonates with sepsis indicated responses to infectious challenges. Acta Paediatr 2019; 108:870-876. [PMID: 30375054 PMCID: PMC6492096 DOI: 10.1111/apa.14630] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Revised: 10/11/2018] [Accepted: 10/25/2018] [Indexed: 11/30/2022]
Abstract
AIM Sepsis is multifactorial and potentially devastating for preterm neonates. Changes in surfactant protein-D (SP-D), phosphatidylcholine (PC) and PC molecular species during infection may indicate innate immunity or inflammation during sepsis. We aimed to compare these important pulmonary molecules in ventilated neonates without or with sepsis. METHODS Endotracheal aspirates were collected from preterm neonates born at 23-35 weeks and admitted to the neonatal intensive care unit at the John Radcliffe Hospital, Oxford, UK, from October 2000 to March 2002. Samples were collected at one day to 30 days and analysed for SP-D, total PC and PC molecular species concentrations using enzyme-linked immunosorbent assay and mass spectrometry. RESULTS We found that 8/54 (14.8%) neonates developed sepsis. SP-D (p < 0.0001), mono- and di-unsaturated PC were significantly increased (p = 0.05), and polyunsaturated PC was significantly decreased (p < 0.01) during sepsis compared to controls. SP-D:PC ratios were significantly increased during sepsis (p < 0.001), and SP-D concentrations were directly related to gestational age in neonates with sepsis (r2 = 0.389, p < 0.01). CONCLUSION Increased SP-D levels and changes in PC molecular species during sepsis were consistent with direct or indirect pulmonary inflammatory processes. Very preterm neonates we able to mount an acute inflammatory innate immune response to infectious challenges, despite low levels of surfactant proteins at birth.
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Affiliation(s)
- Rose‐Marie A. Mackay
- Faculty of Medicine Child Health, Academic Unit of Clinical and Experimental Sciences University of Southampton Southampton UK
| | - J. Paul Townsend
- Respiratory Biomedical Research Unit Southampton NIHR Southampton UK
- Neonatal Intensive Care Unit Princess Anne Hospital University Hospital Southampton NHS Foundation Trust Southampton UK
| | - Jennifer Calvert
- Neonatal Intensive Care Unit Cardiff and Vale University Health Board University Hospital of Wales Cardiff Wales UK
- Neonatal Intensive Care Unit Department of Paediatrics John Radcliffe Hospital University of Oxford Oxford UK
| | - Mark Anthony
- Neonatal Intensive Care Unit Department of Paediatrics John Radcliffe Hospital University of Oxford Oxford UK
| | - Andrew R. Wilkinson
- Neonatal Intensive Care Unit Department of Paediatrics John Radcliffe Hospital University of Oxford Oxford UK
| | - Anthony D. Postle
- Faculty of Medicine Child Health, Academic Unit of Clinical and Experimental Sciences University of Southampton Southampton UK
- Respiratory Biomedical Research Unit Southampton NIHR Southampton UK
- Neonatal Intensive Care Unit Princess Anne Hospital University Hospital Southampton NHS Foundation Trust Southampton UK
| | - Howard W. Clark
- Faculty of Medicine Child Health, Academic Unit of Clinical and Experimental Sciences University of Southampton Southampton UK
- Respiratory Biomedical Research Unit Southampton NIHR Southampton UK
- Neonatal Intensive Care Unit Princess Anne Hospital University Hospital Southampton NHS Foundation Trust Southampton UK
- Neonatal Intensive Care Unit Department of Paediatrics John Radcliffe Hospital University of Oxford Oxford UK
| | - David A. Todd
- Faculty of Medicine Child Health, Academic Unit of Clinical and Experimental Sciences University of Southampton Southampton UK
- Department of Neonatology Centenary Hospital Canberra ACT Australia
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13
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The Basic Science and Molecular Mechanisms of Lung Injury and Acute Respiratory Distress Syndrome. Int Anesthesiol Clin 2019; 56:1-25. [PMID: 29227309 DOI: 10.1097/aia.0000000000000177] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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14
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Chen CY, Anderson NC, Becker S, Schicht M, Stoddard C, Bräuer L, Paulsen F, Grabel L. Examining the role of the surfactant family member SFTA3 in interneuron specification. PLoS One 2018; 13:e0198703. [PMID: 30408033 PMCID: PMC6224035 DOI: 10.1371/journal.pone.0198703] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2018] [Accepted: 10/23/2018] [Indexed: 01/31/2023] Open
Abstract
The transcription factor NKX2.1, expressed at high levels in the medial ganglionic eminence (MGE), is a master regulator of cortical interneuron progenitor development. To identify gene candidates with expression profiles similar to NKX2.1, previous transcriptome analysis of human embryonic stem cell (hESC)-derived MGE-like progenitors revealed SFTA3 as the strongest candidate. Quantitative real-time PCR analysis of hESC-derived NKX2.1-positive progenitors and transcriptome data available from the Allen Institute for Brain Science revealed comparable expression patterns for NKX2.1 and SFTA3 during interneuron differentiation in vitro and demonstrated high SFTA3 expression in the human MGE. Although SFTA3 has been well studied in the lung, the possible role of this surfactant protein in the MGE during embryonic development remains unexamined. To determine if SFTA3 plays a role in MGE specification, SFTA3-/- and NKX2.1 -/- hESC lines were generated using custom designed CRISPRs. We show that NKX2.1 KOs have a significantly diminished capacity to differentiate into MGE interneuron subtypes. SFTA3 KOs also demonstrated a somewhat reduced ability to differentiate down the MGE-like lineage, although not as severe relative to NKX2.1 deficiency. These results suggest NKX2.1 and SFTA3 are co-regulated genes, and that deletion of SFTA3 does not lead to a major change in the specification of MGE derivatives.
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Affiliation(s)
- Christopher Y. Chen
- Department of Biology, Wesleyan University, Middletown, Connecticut, United States of America
| | - Nickesha C. Anderson
- Department of Biology, Wesleyan University, Middletown, Connecticut, United States of America
| | - Sandy Becker
- Department of Biology, Wesleyan University, Middletown, Connecticut, United States of America
| | - Martin Schicht
- Institute of Functional and Clinical Anatomy, Friedrich Alexander University Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Christopher Stoddard
- Genome Sciences, University of Connecticut Health, Farmington, Connecticut, United States of America
| | - Lars Bräuer
- Institute of Functional and Clinical Anatomy, Friedrich Alexander University Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Friedrich Paulsen
- Institute of Functional and Clinical Anatomy, Friedrich Alexander University Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Laura Grabel
- Department of Biology, Wesleyan University, Middletown, Connecticut, United States of America
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15
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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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16
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Hsieh IN, De Luna X, White MR, Hartshorn KL. The Role and Molecular Mechanism of Action of Surfactant Protein D in Innate Host Defense Against Influenza A Virus. Front Immunol 2018; 9:1368. [PMID: 29951070 PMCID: PMC6008380 DOI: 10.3389/fimmu.2018.01368] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2018] [Accepted: 06/01/2018] [Indexed: 12/16/2022] Open
Abstract
Influenza A viruses (IAVs) continue to pose major risks of morbidity and mortality during yearly epidemics and periodic pandemics. The genomic instability of IAV allows it to evade adaptive immune responses developed during prior infection. Of particular concern are pandemics which result from wholesale incorporation of viral genome sections from animal sources. These pandemic strains are radically different from circulating human strains and pose great risk for the human population. For these reasons, innate immunity plays a strong role in the initial containment of IAV infection. Soluble inhibitors present in respiratory lining fluids and blood provide a level of early protection against IAV. In general, these inhibitors act by binding to the viral hemagglutinin (HA). Surfactant protein D (SP-D) and mannose-binding lectin (MBL) attach to mannosylated glycans on the HA in a calcium dependent manner. In contrast, surfactant protein A, ficolins, and other inhibitors present sialic acid rich ligands to which the HA can bind. Among these inhibitors, SP-D seems to be the most potent due to its specific mode of binding to viral carbohydrates and its ability to strongly aggregate viral particles. We have studied specific properties of the N-terminal and collagen domain of SP-D that enable formation of highly multimerized molecules and cooperative binding among the multiple trimeric lectin domains in the protein. In addition, we have studied in depth the lectin activity of SP-D through expression of isolated lectin domains and targeted mutations of the SP-D lectin binding site. Through modifying specific residues around the saccharide binding pocket, antiviral activity of isolated lectin domains of SP-D can be markedly increased for seasonal strains of IAV. Wild-type SP-D causes little inhibition of pandemic IAV, but mutated versions of SP-D were able to inhibit pandemic IAV through enhanced binding to the reduced number of mannosylated glycans present on the HA of these strains. Through collaborative studies involving crystallography of isolated lectin domains of SP-D, glycomics analysis of the HA, and molecular modeling, the mechanism of binding of wild type and mutant forms of SP-D have been determined. These studies could guide investigation of the interactions of SP-D with other pathogens.
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Affiliation(s)
- I-Ni Hsieh
- Boston University School of Medicine, Boston, MA, United States
| | - Xavier De Luna
- Boston University School of Medicine, Boston, MA, United States
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17
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White MR, Kandel R, Hsieh IN, De Luna X, Hartshorn KL. Critical role of C-terminal residues of the Alzheimer's associated β-amyloid protein in mediating antiviral activity and modulating viral and bacterial interactions with neutrophils. PLoS One 2018; 13:e0194001. [PMID: 29547627 PMCID: PMC5856391 DOI: 10.1371/journal.pone.0194001] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2017] [Accepted: 02/22/2018] [Indexed: 11/18/2022] Open
Abstract
Recent studies have shown that the Alzheimer's associated β-amyloid protein (βA) can inhibit growth of bacteria, fungi and viruses. We reported that the 42 amino acid βA protein inhibits replication of seasonal and pandemic strains of H3N2 and H1N1 influenza A virus (IAV) in vitro and modulates activation of neutrophils and monocytes exposed IAV. We here show that fragments composed of the N and C terminal domain of βA42, including βA22-42 and the 8 amino acid βA35-42, retain viral neutralizing and viral aggregating activity, whereas fragments lacking the C-terminal amino acids 41 and 42 (e.g. βA1-40, βA1-34, βA1-28, βA22-40 or βA33-40) have markedly diminished activities on these assays. βA22-42 also increased viral uptake, and virus induced respiratory burst responses, by human neutrophils, while peptides lacking residues 41 and 42 did not. Similar results were obtained with regard to bacterial aggregation, or promotion of bacterial uptake by neutrophils. Published structural studies have shown that βA1-42 has a greater propensity to form neurotoxic oligomers than βA1-40 due to a molecular interaction between Met35 and Ala42. Our findings suggest that there is a relationship between neurotoxic and antimicrobial activities of βA1-42. Truncated peptides containing the last 8 C-terminal amino acids of βA1-42 retain antimicrobial and opsonizing activities likely resulting from their ability to induce viral or bacterial aggregation.
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Affiliation(s)
- Mitchell R White
- Boston University School of Medicine, Department of Medicine, Boston, MA, United States of America
| | - Ruth Kandel
- Boston University School of Medicine, Department of Medicine, Boston, MA, United States of America
| | - I-Ni Hsieh
- Boston University School of Medicine, Department of Medicine, Boston, MA, United States of America
| | - Xavier De Luna
- Boston University School of Medicine, Department of Medicine, Boston, MA, United States of America
| | - Kevan L Hartshorn
- Boston University School of Medicine, Department of Medicine, Boston, MA, United States of America
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18
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Wu NC, Liao FT, Cheng HM, Sung SH, Yang YC, Wang JJ. Intravenous superoxide dismutase as a protective agent to prevent impairment of lung function induced by high tidal volume ventilation. BMC Pulm Med 2017; 17:105. [PMID: 28747201 PMCID: PMC5530466 DOI: 10.1186/s12890-017-0448-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2016] [Accepted: 07/19/2017] [Indexed: 12/12/2022] Open
Abstract
Background Positive-pressure mechanical ventilation is essential in assisting patients with respiratory failure in the intensive care unit and facilitating oxygenation in the operating room. However, it was also recognized as a primary factor leading to hospital-acquired pulmonary dysfunction, in which pulmonary oxidative stress and lung inflammation had been known to play important roles. Cu/Zn superoxide dismutase (SOD) is an important antioxidant, and possesses anti-inflammatory capacity. In this study, we aimed to study the efficacy of Cu/Zn SOD, administered intravenously during high tidal volume (HTV) ventilation, to prevent impairment of lung function. Methods Thirty-eight male Sprague-Dawley rats were divided into 3 groups: 5 h ventilation with (A) low tidal volume (LTV; 8 mL/kg; n = 10), (B) high tidal volume (HTV; 18 mL/kg; n = 14), or (C) HTV and intravenous treatment of Cu/Zn SOD at a dose of 1000 U/kg/h (HTV + SOD; n = 14). Lung function was evaluated both at baseline and after 5-h ventilation. Lung injury was assessed by histological examination, lung water and protein contents in the bronchoalveolar lavage fluid (BALF). Pulmonary oxidative stress was examined by concentrations of methylguanidine (MG) and malondialdehyde (MDA) in BALF, and antioxidative activity by protein expression of glutathione peroxidase-1 (GPx-1) in the lung. Severity of lung inflammation was evaluated by white blood cell and differential count in BALF, and protein expression of inducible nitric oxide synthase (iNOS), intercellular adhesion molecule-1 (ICAM-1), tumor necrosis factor-α (TNF-α), matrix metalloproteinase-9 (MMP-9), and mRNA expression of nuclear factor-κB (NF-κB) in the lung. We also examined protein expression of surfactant protein (SP)-A and D and we measured hourly changes in serum nitric oxide (NO) level. Results Five hours of LTV ventilation did not induce a major change in lung function, whereas 5 h of HTV ventilation induced apparent combined restrictive and obstructive lung disorder, together with increased pulmonary oxidative stress, decreased anti-oxidative activity and increased lung inflammation (P < 0.05). HTV ventilation also decreased SP-A and SP-D expression and suppressed serum NO level during the time course of ventilation. Cu/Zn SOD administered intravenously during HTV ventilation effectively reversed associated pulmonary oxidative stress and lung inflammation (P < 0.05); moreover, it preserved SP-A and SP-D expressions in the lung and increased serum nitric oxide (NO) level, enhancing vascular NO bioavailability. Conclusions HTV ventilation can induce combined restrictive and obstructive lung disorders. Intravenous administration of Cu/Zn SOD during HTV ventilation can prevent lung function impairment and lung injury via reducing pulmonary oxidative stress and lung inflammation, preserving pulmonary surfactant expression, and enhancing vascular NO bioavailability.
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Affiliation(s)
- Nan-Chun Wu
- Division of Cardiovascular Surgery, Department of Surgery, Chi-Mei Foundation Hospital, 901, Chung Hwa Rd. Yung Kang, Tainan, Taiwan
| | - Fan-Ting Liao
- School of Medicine, Fu Jen Catholic University, No. 510, Zhongzheng Rd., Xinzhuang Dist, New Taipei City, 24205, Taiwan
| | - Hao-Min Cheng
- Department of Medical Education, Taipei Veterans General Hospital, Taipei, Taiwan.,Institute of Public Health and Community Medicine Research Center, National Yang-Ming University, Taipei, Taiwan.,Department of Medicine, National Yang-Ming University, Taipei, Taiwan
| | - Shih-Hsien Sung
- Division of Cardiology, Department of Internal Medicine, Taipei Veterans General Hospital, Taipei, Taiwan.,Institute of Public Health and Community Medicine Research Center, National Yang-Ming University, Taipei, Taiwan.,Department of Medicine, National Yang-Ming University, Taipei, Taiwan
| | - Yu-Chun Yang
- School of Medicine, Fu Jen Catholic University, No. 510, Zhongzheng Rd., Xinzhuang Dist, New Taipei City, 24205, Taiwan
| | - Jiun-Jr Wang
- School of Medicine, Fu Jen Catholic University, No. 510, Zhongzheng Rd., Xinzhuang Dist, New Taipei City, 24205, Taiwan.
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19
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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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20
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Yang X, Yan J, Feng J. Surfactant protein A is expressed in the central nervous system of rats with experimental autoimmune encephalomyelitis, and suppresses inflammation in human astrocytes and microglia. Mol Med Rep 2017; 15:3555-3565. [PMID: 28393255 PMCID: PMC5436200 DOI: 10.3892/mmr.2017.6441] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2015] [Accepted: 02/13/2017] [Indexed: 12/03/2022] Open
Abstract
The collectin surfactant protein-A (SP-A), a potent host defense molecule, is well recognized for its role in the maintenance of pulmonary homeostasis and the modulation of inflammatory responses. While previous studies have detected SP-A in numerous extrapulmonary tissues, there is still a lack of information regarding its expression in central nervous system (CNS) and potential effects in neuroinflammatory diseases, such as multiple sclerosis (MS). The present study used experimental autoimmune encephalomyelitis (EAE), the most commonly used animal model of MS, to investigate the expression of SP-A in the CNS at different stages of disease progression. In addition, in vitro experiments with lipopolysaccharide (LPS)-stimulated human astrocytes and microglia were performed to investigate the potential role of SP-A in the modulation of CNS inflammatory responses. The results of the present study demonstrated widespread distribution of SP-A in the rat CNS, and also identified specific expression patterns of SP-A at different stages of EAE. In vitro, the current study revealed that treatment of human astrocytes and microglia with LPS promoted SP-A expression in a dose-dependent manner. Furthermore, exogenous SP-A protein significantly decreased Toll-like receptor 4 and nuclear factor-κB expression, and reduced interleukin-1β and tumor necrosis factor-α levels. The results of the current study indicate a potential role for SP-A in the modulation of CNS inflammatory responses.
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Affiliation(s)
- Xue Yang
- Department of Neurology, Shengjing Hospital, Affiliated Hospital of China Medical University. Shenyang, Liaoning 110004, P.R. China
| | - Jun Yan
- Department of Neurology, Shengjing Hospital, Affiliated Hospital of China Medical University. Shenyang, Liaoning 110004, P.R. China
| | - Juan Feng
- Department of Neurology, Shengjing Hospital, Affiliated Hospital of China Medical University. Shenyang, Liaoning 110004, P.R. China
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21
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Lung epithelium and myeloid cells cooperate to clear acute pneumococcal infection. Mucosal Immunol 2016; 9:1288-302. [PMID: 26627460 PMCID: PMC4990776 DOI: 10.1038/mi.2015.128] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2015] [Accepted: 11/01/2015] [Indexed: 02/04/2023]
Abstract
The Gram-positive bacterium Streptococcus pneumoniae causes life-threatening infections, especially among immunocompromised patients. The host's immune system senses S. pneumoniae via different families of pattern recognition receptors, in particular the Toll-like receptor (TLR) family that promotes immune cell activation. Yet, while single TLRs are dispensable for initiating inflammatory responses against S. pneumoniae, the central TLR adapter protein myeloid differentiation factor 88 (MyD88) is of vital importance, as MyD88-deficient mice succumb rapidly to infection. Since MyD88 is ubiquitously expressed in hematopoietic and non-hematopoietic cells, the extent to which MyD88 signaling is required in different cell types to control S. pneumoniae is unknown. Therefore, we used novel conditional knockin mice to investigate the necessity of MyD88 signaling in distinct lung-resident myeloid and epithelial cells for the initiation of a protective immune response against S. pneumoniae. Here, we show that MyD88 signaling in lysozyme M (LysM)- and CD11c-expressing myeloid cells, as well as in pulmonary epithelial cells, is critical to restore inflammatory cytokine and antimicrobial peptide production, leading to efficient neutrophil recruitment and enhanced bacterial clearance. Overall, we show a novel synergistic requirement of compartment-specific MyD88 signaling in S. pneumoniae immunity.
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22
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Crosby HA, Kwiecinski J, Horswill AR. Staphylococcus aureus Aggregation and Coagulation Mechanisms, and Their Function in Host-Pathogen Interactions. ADVANCES IN APPLIED MICROBIOLOGY 2016; 96:1-41. [PMID: 27565579 DOI: 10.1016/bs.aambs.2016.07.018] [Citation(s) in RCA: 77] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The human commensal bacterium Staphylococcus aureus can cause a wide range of infections ranging from skin and soft tissue infections to invasive diseases like septicemia, endocarditis, and pneumonia. Muticellular organization almost certainly contributes to S. aureus pathogenesis mechanisms. While there has been considerable focus on biofilm formation and its role in colonizing prosthetic joints and indwelling devices, less attention has been paid to nonsurface-attached group behavior like aggregation and clumping. S. aureus is unique in its ability to coagulate blood, and it also produces multiple fibrinogen-binding proteins that facilitate clumping. Formation of clumps, which are large, tightly packed groups of cells held together by fibrin(ogen), has been demonstrated to be important for S. aureus virulence and immune evasion. Clumps of cells are able to avoid detection by the host's immune system due to a fibrin(ogen) coat that acts as a shield, and the size of the clumps facilitates evasion of phagocytosis. In addition, clumping could be an important early step in establishing infections that involve tight clusters of cells embedded in host matrix proteins, such as soft tissue abscesses and endocarditis. In this review, we discuss clumping mechanisms and regulation, as well as what is known about how clumping contributes to immune evasion.
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Affiliation(s)
- H A Crosby
- University of Iowa, Iowa City, IA, United States
| | - J Kwiecinski
- University of Iowa, Iowa City, IA, United States
| | - A R Horswill
- University of Iowa, Iowa City, IA, United States
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Jaillon S, Ponzetta A, Magrini E, Barajon I, Barbagallo M, Garlanda C, Mantovani A. Fluid phase recognition molecules in neutrophil-dependent immune responses. Semin Immunol 2016; 28:109-18. [PMID: 27021644 DOI: 10.1016/j.smim.2016.03.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/01/2016] [Revised: 03/09/2016] [Accepted: 03/12/2016] [Indexed: 01/01/2023]
Abstract
The innate immune system comprises both a cellular and a humoral arm. Neutrophils are key effector cells of the immune and inflammatory responses and have emerged as a major source of humoral pattern recognition molecules (PRMs). These molecules, which include collectins, ficolins, and pentraxins, are specialised in the discrimination of self versus non-self and modified-self and share basic multifunctional properties including recognition and opsonisation of pathogens and apoptotic cells, activation and regulation of the complement cascade and tuning of inflammation. Neutrophils act as a reservoir of ready-made soluble PRMs, such as the long pentraxin PTX3, the peptidoglycan recognition protein PGRP-S, properdin and M-ficolin, which are stored in neutrophil granules and are involved in neutrophil effector functions. In addition, other soluble PRMs, such as members of the collectin family, are not expressed in neutrophils but can modulate neutrophil-dependent immune responses. Therefore, soluble PRMs are an essential part of the innate immune response and retain antibody-like effector functions. Here, we will review the expression and general function of soluble PRMs, focusing our attention on molecules involved in neutrophil effector functions.
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Affiliation(s)
- Sébastien Jaillon
- Department of Immunology and Inflammation, Humanitas Clinical and Research Center, via Manzoni 56, 20089 Rozzano, Milan, Italy; Department of Biomedical Sciences, Humanitas University, Via Manzoni 113, 20089 Rozzano, Milan, Italy.
| | - Andrea Ponzetta
- Department of Immunology and Inflammation, Humanitas Clinical and Research Center, via Manzoni 56, 20089 Rozzano, Milan, Italy
| | - Elena Magrini
- Department of Immunology and Inflammation, Humanitas Clinical and Research Center, via Manzoni 56, 20089 Rozzano, Milan, Italy
| | - Isabella Barajon
- Department of Biomedical Sciences, Humanitas University, Via Manzoni 113, 20089 Rozzano, Milan, Italy
| | - Marialuisa Barbagallo
- Department of Immunology and Inflammation, Humanitas Clinical and Research Center, via Manzoni 56, 20089 Rozzano, Milan, Italy
| | - Cecilia Garlanda
- Department of Immunology and Inflammation, Humanitas Clinical and Research Center, via Manzoni 56, 20089 Rozzano, Milan, Italy; Department of Biomedical Sciences, Humanitas University, Via Manzoni 113, 20089 Rozzano, Milan, Italy
| | - Alberto Mantovani
- Department of Immunology and Inflammation, Humanitas Clinical and Research Center, via Manzoni 56, 20089 Rozzano, Milan, Italy; Department of Biomedical Sciences, Humanitas University, Via Manzoni 113, 20089 Rozzano, Milan, Italy.
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Abstract
Pulmonary surfactant is essential for life as it lines the alveoli to lower surface tension, thereby preventing atelectasis during breathing. Surfactant is enriched with a relatively unique phospholipid, termed dipalmitoylphosphatidylcholine, and four surfactant-associated proteins, SP-A, SP-B, SP-C, and SP-D. The hydrophobic proteins, SP-B and SP-C, together with dipalmitoylphosphatidylcholine, confer surface tension-lowering properties to the material. The more hydrophilic surfactant components, SP-A and SP-D, participate in pulmonary host defense and modify immune responses. Specifically, SP-A and SP-D bind and partake in the clearance of a variety of bacterial, fungal, and viral pathogens and can dampen antigen-induced immune function of effector cells. Emerging data also show immunosuppressive actions of some surfactant-associated lipids, such as phosphatidylglycerol. Conversely, microbial pathogens in preclinical models impair surfactant synthesis and secretion, and microbial proteinases degrade surfactant-associated proteins. Deficiencies of surfactant components are classically observed in the neonatal respiratory distress syndrome, where surfactant replacement therapies have been the mainstay of treatment. However, functional or compositional deficiencies of surfactant are also observed in a variety of acute and chronic lung disorders. Increased surfactant is seen in pulmonary alveolar proteinosis, a disorder characterized by a functional deficiency of the granulocyte-macrophage colony-stimulating factor receptor or development of granulocyte-macrophage colony-stimulating factor antibodies. Genetic polymorphisms of some surfactant proteins such as SP-C are linked to interstitial pulmonary fibrosis. Here, we briefly review the composition, antimicrobial properties, and relevance of pulmonary surfactant to lung disorders and present its therapeutic implications.
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Manifold-Wheeler BC, Elmore BO, Triplett KD, Castleman MJ, Otto M, Hall PR. Serum Lipoproteins Are Critical for Pulmonary Innate Defense against Staphylococcus aureus Quorum Sensing. THE JOURNAL OF IMMUNOLOGY 2015; 196:328-35. [PMID: 26608923 DOI: 10.4049/jimmunol.1501835] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/14/2015] [Accepted: 10/30/2015] [Indexed: 01/12/2023]
Abstract
Hyperlipidemia has been extensively studied in the context of atherosclerosis, whereas the potential health consequences of the opposite extreme, hypolipidemia, remain largely uninvestigated. Circulating lipoproteins are essential carriers of insoluble lipid molecules and are increasingly recognized as innate immune effectors. Importantly, severe hypolipidemia, which may occur with trauma or critical illness, is clinically associated with bacterial pneumonia. To test the hypothesis that circulating lipoproteins are essential for optimal host innate defense in the lung, we used lipoprotein-deficient mice and a mouse model of Staphylococcus aureus pneumonia in which invasive infection requires virulence factor expression controlled by the accessory gene regulator (agr) operon. Activation of agr and subsequent virulence factor expression is inhibited by apolipoprotein B, the structural protein of low-density lipoprotein, which binds and sequesters the secreted agr-signaling peptide (AIP). In this article, we report that lipoprotein deficiency impairs early pulmonary innate defense against S. aureus quorum-sensing-dependent pathogenesis. Specifically, apolipoprotein B levels in the lung early postinfection are significantly reduced with lipoprotein deficiency, coinciding with impaired host control of S. aureus agr-signaling and increased agr-dependent morbidity (weight loss) and inflammation. Given that lipoproteins also inhibit LTA- and LPS-mediated inflammation, these results suggest that hypolipidemia may broadly impact posttrauma pneumonia susceptibility to both Gram-positive and -negative pathogens. Together with previous reports demonstrating that hyperlipidemia also impairs lung innate defense, these results suggest that maintenance of normal serum lipoprotein levels is necessary for optimal host innate defense in the lung.
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Affiliation(s)
- Brett C Manifold-Wheeler
- Department of Pharmaceutical Sciences, University of New Mexico College of Pharmacy, Albuquerque, NM 87131; and
| | - Bradley O Elmore
- Department of Pharmaceutical Sciences, University of New Mexico College of Pharmacy, Albuquerque, NM 87131; and
| | - Kathleen D Triplett
- Department of Pharmaceutical Sciences, University of New Mexico College of Pharmacy, Albuquerque, NM 87131; and
| | - Moriah J Castleman
- Department of Pharmaceutical Sciences, University of New Mexico College of Pharmacy, Albuquerque, NM 87131; and
| | - Michael Otto
- Pathogen Molecular Genetics Section, Laboratory of Bacteriology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892
| | - Pamela R Hall
- Department of Pharmaceutical Sciences, University of New Mexico College of Pharmacy, Albuquerque, NM 87131; and
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26
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Stolberg VR, McCubbrey AL, Freeman CM, Brown JP, Crudgington SW, Taitano SH, Saxton BL, Mancuso P, Curtis JL. Glucocorticoid-Augmented Efferocytosis Inhibits Pulmonary Pneumococcal Clearance in Mice by Reducing Alveolar Macrophage Bactericidal Function. THE JOURNAL OF IMMUNOLOGY 2015; 195:174-84. [PMID: 25987742 DOI: 10.4049/jimmunol.1402217] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Received: 08/28/2014] [Accepted: 04/22/2015] [Indexed: 12/31/2022]
Abstract
Inhaled corticosteroids (ICS) increase community-acquired pneumonia (CAP) incidence in patients with chronic obstructive pulmonary disease (COPD) by unknown mechanisms. Apoptosis is increased in the lungs of COPD patients. Uptake of apoptotic cells (ACs) ("efferocytosis") by alveolar macrophages (AMøs) reduces their ability to combat microbes, including Streptococcus pneumoniae, the most common cause of CAP in COPD patients. Having shown that ICS significantly increase AMø efferocytosis, we hypothesized that this process, termed glucocorticoid-augmented efferocytosis, might explain the association of CAP with ICS therapy in COPD. To test this hypothesis, we studied the effects of fluticasone, AC, or both on AMøs of C57BL/6 mice in vitro and in an established model of pneumococcal pneumonia. Fluticasone plus AC significantly reduced TLR4-stimulated AMø IL-12 production, relative to either treatment alone, and decreased TNF-α, CCL3, CCL5, and keratinocyte-derived chemoattractant/CXCL1, relative to AC. Mice treated with fluticasone plus AC before infection with viable pneumococci developed significantly more lung CFUs at 48 h. However, none of the pretreatments altered inflammatory cell recruitment to the lungs at 48 h postinfection, and fluticasone plus AC less markedly reduced in vitro mediator production to heat-killed pneumococci. Fluticasone plus AC significantly reduced in vitro AMø killing of pneumococci, relative to other conditions, in part by delaying phagolysosome acidification without affecting production of reactive oxygen or nitrogen species. These results support glucocorticoid-augmented efferocytosis as a potential explanation for the epidemiological association of ICS therapy of COPD patients with increased risk for CAP, and establish murine experimental models to dissect underlying molecular mechanisms.
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Affiliation(s)
| | | | - Christine M Freeman
- Research Service, VA Ann Arbor Healthcare System, Ann Arbor, MI 48105; Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, University of Michigan Health System, Ann Arbor, MI 48109
| | - Jeanette P Brown
- Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, University of Michigan Health System, Ann Arbor, MI 48109
| | - Sean W Crudgington
- Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, University of Michigan Health System, Ann Arbor, MI 48109
| | - Sophina H Taitano
- Graduate Program in Immunology, University of Michigan, Ann Arbor, MI 48109
| | | | - Peter Mancuso
- Graduate Program in Immunology, University of Michigan, Ann Arbor, MI 48109; Department of Environmental Health Sciences, School of Public Health, University of Michigan, Ann Arbor, MI 48109; and
| | - Jeffrey L Curtis
- Graduate Program in Immunology, University of Michigan, Ann Arbor, MI 48109; Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, University of Michigan Health System, Ann Arbor, MI 48109; Medical Service, VA Ann Arbor Healthcare System, Ann Arbor, MI 48105
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27
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Diler E, Schicht M, Rabung A, Tschernig T, Meier C, Rausch F, Garreis F, Bräuer L, Paulsen F. The novel surfactant protein SP-H enhances the phagocytosis efficiency of macrophage-like cell lines U937 and MH-S. BMC Res Notes 2014; 7:851. [PMID: 25427765 PMCID: PMC4256058 DOI: 10.1186/1756-0500-7-851] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2014] [Accepted: 11/18/2014] [Indexed: 11/10/2022] Open
Abstract
Background Surfactant proteins (SP) secreted by alveolar type 2 cells, play an essential role in maintaining the air-liquid barrier of the lung and are also involved in the opsonisation and clearance of bacteria by phagocytes. We have recently described a novel surfactant protein, SP-H (SFTA3). Expression of SP-H was earlier demonstrated to be upregulated by LPS and negatively regulated by IL-1β and IL-23 in vitro. The influence of SP-H on phagocytosis was measured using a murine and a human phagocytic cell line and fluorescent latex beads. Findings SP-H markedly increases phagocytosis in vitro in the murine-derived alveolar macrophage cell lines MH-S and in human-derived differentiated U937 cells. Conclusion It can be assumed that SP-H is involved in regulating phagocytic activity of macrophages. SP-H is a new player in pulmonary host defence.
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Affiliation(s)
| | | | | | - Thomas Tschernig
- Institute of Anatomy and Cell Biology, Saarland University, 66421 Homburg/Saar, Germany.
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28
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Protein modeling and molecular dynamics simulation of the two novel surfactant proteins SP-G and SP-H. J Mol Model 2014; 20:2513. [PMID: 25381619 PMCID: PMC7101549 DOI: 10.1007/s00894-014-2513-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2014] [Accepted: 10/21/2014] [Indexed: 11/14/2022]
Abstract
Surfactant proteins are well known from the human lung where they are responsible for the stability and flexibility of the pulmonary surfactant system. They are able to influence the surface tension of the gas–liquid interface specifically by directly interacting with single lipids. This work describes the generation of reliable protein structure models to support the experimental characterization of two novel putative surfactant proteins called SP-G and SP-H. The obtained protein models were complemented by predicted posttranslational modifications and placed in a lipid model system mimicking the pulmonary surface. Molecular dynamics simulations of these protein-lipid systems showed the stability of the protein models and the formation of interactions between protein surface and lipid head groups on an atomic scale. Thereby, interaction interface and strength seem to be dependent on orientation and posttranslational modification of the protein. The here presented modeling was fundamental for experimental localization studies and the simulations showed that SP-G and SP-H are theoretically able to interact with lipid systems and thus are members of the surfactant protein family.
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29
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van Kessel KPM, Bestebroer J, van Strijp JAG. Neutrophil-Mediated Phagocytosis of Staphylococcus aureus. Front Immunol 2014; 5:467. [PMID: 25309547 PMCID: PMC4176147 DOI: 10.3389/fimmu.2014.00467] [Citation(s) in RCA: 110] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2014] [Accepted: 09/12/2014] [Indexed: 01/13/2023] Open
Abstract
Initial elimination of invading Staphylococcus aureus from the body is mediated by professional phagocytes. The neutrophil is the major phagocyte of the innate immunity and plays a key role in the host defense against staphylococcal infections. Opsonization of the bacteria with immunoglobulins and complement factors enables efficient recognition by the neutrophil that subsequently leads to intracellular compartmentalization and killing. Here, we provide a review of the key processes evolved in neutrophil-mediated phagocytosis of S. aureus and briefly describe killing. As S. aureus is not helpless against the professional phagocytes, we will also highlight its immune evasion arsenal related to phagocytosis.
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Affiliation(s)
- Kok P M van Kessel
- Medical Microbiology, University Medical Center Utrecht , Utrecht , Netherlands
| | - Jovanka Bestebroer
- Medical Microbiology, University Medical Center Utrecht , Utrecht , Netherlands
| | - Jos A G van Strijp
- Medical Microbiology, University Medical Center Utrecht , Utrecht , Netherlands
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30
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Klonoski JM, Hurtig HR, Juber BA, Schuneman MJ, Bickett TE, Svendsen JM, Burum B, Penfound TA, Sereda G, Dale JB, Chaussee MS, Huber VC. Vaccination against the M protein of Streptococcus pyogenes prevents death after influenza virus: S. pyogenes super-infection. Vaccine 2014; 32:5241-9. [PMID: 25077423 DOI: 10.1016/j.vaccine.2014.06.093] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2014] [Revised: 06/12/2014] [Accepted: 06/13/2014] [Indexed: 12/21/2022]
Abstract
Influenza virus infections are associated with a significant number of illnesses and deaths on an annual basis. Many of the deaths are due to complications from secondary bacterial invaders, including Streptococcus pneumoniae, Staphylococcus aureus, Haemophilus influenzae, and Streptococcus pyogenes. The β-hemolytic bacteria S. pyogenes colonizes both skin and respiratory surfaces, and frequently presents clinically as strep throat or impetigo. However, when these bacteria gain access to normally sterile sites, they can cause deadly diseases including sepsis, necrotizing fasciitis, and pneumonia. We previously developed a model of influenza virus:S. pyogenes super-infection, which we used to demonstrate that vaccination against influenza virus can limit deaths associated with a secondary bacterial infection, but this protection was not complete. In the current study, we evaluated the efficacy of a vaccine that targets the M protein of S. pyogenes to determine whether immunity toward the bacteria alone would allow the host to survive an influenza virus:S. pyogenes super-infection. Our data demonstrate that vaccination against the M protein induces IgG antibodies, in particular those of the IgG1 and IgG2a isotypes, and that these antibodies can interact with macrophages. Ultimately, this vaccine-induced immunity eliminated death within our influenza virus:S. pyogenes super-infection model, despite the fact that all M protein-vaccinated mice showed signs of illness following influenza virus inoculation. These findings identify immunity against bacteria as an important component of protection against influenza virus:bacteria super-infection.
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Affiliation(s)
- Joshua M Klonoski
- Division of Basic Biomedical Sciences, Sanford School of Medicine, University of South Dakota, Vermillion, SD, United States
| | - Heather R Hurtig
- Division of Basic Biomedical Sciences, Sanford School of Medicine, University of South Dakota, Vermillion, SD, United States
| | - Brian A Juber
- Division of Basic Biomedical Sciences, Sanford School of Medicine, University of South Dakota, Vermillion, SD, United States
| | - Margaret J Schuneman
- Division of Basic Biomedical Sciences, Sanford School of Medicine, University of South Dakota, Vermillion, SD, United States
| | - Thomas E Bickett
- Division of Basic Biomedical Sciences, Sanford School of Medicine, University of South Dakota, Vermillion, SD, United States
| | - Joshua M Svendsen
- Division of Basic Biomedical Sciences, Sanford School of Medicine, University of South Dakota, Vermillion, SD, United States
| | - Brandon Burum
- Department of Chemistry, University of South Dakota, Vermillion, SD, United States
| | - Thomas A Penfound
- University of Tennessee Health Science Center and the Veterans Affairs Medical Center Research Service, Memphis, TN, United States
| | - Grigoriy Sereda
- Department of Chemistry, University of South Dakota, Vermillion, SD, United States
| | - James B Dale
- University of Tennessee Health Science Center and the Veterans Affairs Medical Center Research Service, Memphis, TN, United States
| | - Michael S Chaussee
- Division of Basic Biomedical Sciences, Sanford School of Medicine, University of South Dakota, Vermillion, SD, United States
| | - Victor C Huber
- Division of Basic Biomedical Sciences, Sanford School of Medicine, University of South Dakota, Vermillion, SD, United States.
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31
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Surfactant Protein D modulates HIV infection of both T-cells and dendritic cells. PLoS One 2013; 8:e59047. [PMID: 23527085 PMCID: PMC3601116 DOI: 10.1371/journal.pone.0059047] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2012] [Accepted: 02/11/2013] [Indexed: 11/19/2022] Open
Abstract
Surfactant Protein D (SP-D) is an oligomerized C-type lectin molecule with immunomodulatory properties and involvement in lung surfactant homeostasis in the respiratory tract. SP-D binds to the enveloped viruses, influenza A virus and respiratory syncytial virus and inhibits their replication in vitro and in vivo. SP-D has been shown to bind to HIV via the HIV envelope protein gp120 and inhibit infectivity in vitro. Here we show that SP-D binds to different strains of HIV (BaL and IIIB) and the binding occurs at both pH 7.4 and 5.0 resembling physiological relevant pH values found in the body and the female urogenital tract, respectively. The binding of SP-D to HIV particles and gp120 was inhibited by the presence of several hexoses with mannose found to be the strongest inhibitor. Competition studies showed that soluble CD4 and CVN did not interfere with the interaction between SP-D and gp120. However, soluble recombinant DC-SIGN was shown to inhibit the binding between SP-D and gp120. SP-D agglutinated HIV and gp120 in a calcium dependent manner. SP-D inhibited the infectivity of HIV strains at both pH values of 7.4 and 5.0 in a concentration dependent manner. The inhibition of the infectivity was abolished by the presence of mannose. SP-D enhanced the binding of HIV to immature monocyte derived dendritic cells (iMDDCs) and was also found to enhance HIV capture and transfer to the T-cell like line PM1. These results suggest that SP-D can bind to and inhibit direct infection of T-cells by HIV but also enhance the transfer of infectious HIV particles from DCs to T-cells in vivo.
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32
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Hillaire MLB, Haagsman HP, Osterhaus ADME, Rimmelzwaan GF, van Eijk M. Pulmonary surfactant protein D in first-line innate defence against influenza A virus infections. J Innate Immun 2013; 5:197-208. [PMID: 23391661 DOI: 10.1159/000346374] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2012] [Accepted: 12/06/2012] [Indexed: 12/21/2022] Open
Abstract
Influenza A viruses (IAV) cause respiratory tract infections annually associated with excess mortality and morbidity. Nonspecific, innate immune mechanisms play a key role in protection against viral invasion at early stages of infection. A soluble protein present in mucosal secretions of the lung, surfactant protein D (SP-D), is an important component of this initial barrier that helps to prevent and limit IAV infections of the respiratory epithelium. This collagenous C-type lectin binds IAVs and thereby inhibits attachment and entry of the virus but also contributes to enhanced clearance of SP-D-opsonized virus via interactions with phagocytic cells. In addition, SP-D modulates the inflammatory response and helps to maintain a balance between effective neutralization/killing of IAV, and protection against alveolar damage resulting from IAV-induced excessive inflammatory responses. The mechanisms of interaction between SP-D and IAV not only depend on the structure and binding properties of SP-D but also on strain-specific features of IAV, and both issues will be discussed. SP-D from pigs exhibits distinct anti-IAV properties and is discussed in more detail. Finally, the potential of SP-D as a prophylactic and/or therapeutic antiviral agent to protect humans against infections by IAV is discussed.
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Affiliation(s)
- Marine L B Hillaire
- Erasmus Medical Centre, Department of Viroscience, Rotterdam, The Netherlands
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33
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Kantyka T, Pyrc K, Gruca M, Smagur J, Plaza K, Guzik K, Zeglen S, Ochman M, Potempa J. Staphylococcus aureus proteases degrade lung surfactant protein A potentially impairing innate immunity of the lung. J Innate Immun 2012; 5:251-60. [PMID: 23235402 DOI: 10.1159/000345417] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2012] [Accepted: 10/23/2012] [Indexed: 11/19/2022] Open
Abstract
The pulmonary surfactant is a complex mixture of lipids and proteins that is important for respiratory lung functions, which also provides the first line of innate immune defense. Pulmonary surfactant protein-A (SP-A) is a major surfactant component with immune functions with importance during Staphylococcus aureus infections that has been demonstrated in numerous studies. The current study showed that S. aureus can efficiently cleave the SP-A protein using its arsenal of proteolytic enzymes. This degradation appears to be mediated by cysteine proteases, in particular staphopain A (ScpA). The staphopain-mediated proteolysis of SP-A resulted in a decrease or complete abolishment of SP-A biological activity, including the promotion of S. aureus phagocytosis by neutrophils, aggregation of Gram-negative bacteria and bacterial cell adherence to epithelium. Significantly, ScpA has also efficiently degraded SP-A in complete bronchi-alveolar lavage fluid from human lungs. This indicates that staphopain activity in the lungs is resistant to protease inhibitors, thus suggesting that SP-A can be cleaved in vivo. Collectively, this study showed that the S. aureus protease ScpA is an important virulence factor that may impair innate immunity of the lungs.
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Affiliation(s)
- Tomasz Kantyka
- Department of Microbiology, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Krakow, Poland
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Rausch F, Schicht M, Paulsen F, Ngueya I, Bräuer L, Brandt W. "SP-G", a putative new surfactant protein--tissue localization and 3D structure. PLoS One 2012; 7:e47789. [PMID: 23094088 PMCID: PMC3475697 DOI: 10.1371/journal.pone.0047789] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2012] [Accepted: 09/17/2012] [Indexed: 12/30/2022] Open
Abstract
Surfactant proteins (SP) are well known from human lung. These proteins assist the formation of a monolayer of surface-active phospholipids at the liquid-air interface of the alveolar lining, play a major role in lowering the surface tension of interfaces, and have functions in innate and adaptive immune defense. During recent years it became obvious that SPs are also part of other tissues and fluids such as tear fluid, gingiva, saliva, the nasolacrimal system, and kidney. Recently, a putative new surfactant protein (SFTA2 or SP-G) was identified, which has no sequence or structural identity to the already know surfactant proteins. In this work, computational chemistry and molecular-biological methods were combined to localize and characterize SP-G. With the help of a protein structure model, specific antibodies were obtained which allowed the detection of SP-G not only on mRNA but also on protein level. The localization of this protein in different human tissues, sequence based prediction tools for posttranslational modifications and molecular dynamic simulations reveal that SP-G has physicochemical properties similar to the already known surfactant proteins B and C. This includes also the possibility of interactions with lipid systems and with that, a potential surface-regulatory feature of SP-G. In conclusion, the results indicate SP-G as a new surfactant protein which represents an until now unknown surfactant protein class.
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Affiliation(s)
- Felix Rausch
- Department of Bioorganic Chemistry, Leibniz Institute of Plant Biochemistry, Halle, Germany
| | - Martin Schicht
- Institute of Anatomy, Department II, Friedrich Alexander University Erlangen-Nuremberg, Erlangen, Germany
| | - Friedrich Paulsen
- Institute of Anatomy, Department II, Friedrich Alexander University Erlangen-Nuremberg, Erlangen, Germany
| | - Ivan Ngueya
- Institute of Anatomy, Department II, Friedrich Alexander University Erlangen-Nuremberg, Erlangen, Germany
| | - Lars Bräuer
- Institute of Anatomy, Department II, Friedrich Alexander University Erlangen-Nuremberg, Erlangen, Germany
| | - Wolfgang Brandt
- Department of Bioorganic Chemistry, Leibniz Institute of Plant Biochemistry, Halle, Germany
- * E-mail:
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35
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Kurimura Y, Nishitani C, Ariki S, Saito A, Hasegawa Y, Takahashi M, Hashimoto J, Takahashi S, Tsukamoto T, Kuroki Y. Surfactant protein D inhibits adherence of uropathogenic Escherichia coli to the bladder epithelial cells and the bacterium-induced cytotoxicity: a possible function in urinary tract. J Biol Chem 2012; 287:39578-88. [PMID: 23012359 DOI: 10.1074/jbc.m112.380287] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The adherence of uropathogenic Escherichia coli (UPEC) to the host urothelial surface is the first step for establishing UPEC infection. Uroplakin Ia (UPIa), a glycoprotein expressed on bladder urothelium, serves as a receptor for FimH, a lectin located at bacterial pili, and their interaction initiates UPEC infection. Surfactant protein D (SP-D) is known to be expressed on mucosal surfaces in various tissues besides the lung. However, the functions of SP-D in the non-pulmonary tissues are poorly understood. The purposes of this study were to investigate the possible function of SP-D expressed in the bladder urothelium and the mechanisms by which SP-D functions. SP-D was expressed in human bladder mucosa, and its mRNA was increased in the bladder of the UPEC infection model in mice. SP-D directly bound to UPEC and strongly agglutinated them in a Ca(2+)-dependent manner. Co-incubation of SP-D with UPEC decreased the bacterial adherence to 5637 cells, the human bladder cell line, and the UPEC-induced cytotoxicity. In addition, preincubation of SP-D with 5637 cells resulted in the decreased adherence of UPEC to the cells and in a reduced number of cells injured by UPEC. SP-D directly bound to UPIa and competed with FimH for UPIa binding. Consistent with the in vitro data, the exogenous administration of SP-D inhibited UPEC adherence to the bladder and dampened UPEC-induced inflammation in mice. These results support the conclusion that SP-D can protect the bladder urothelium against UPEC infection and suggest a possible function of SP-D in urinary tract.
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Affiliation(s)
- Yuichiro Kurimura
- Department of Biochemistry, Sapporo Medical University School of Medicine, Sapporo 060-8556, Japan
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36
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Kasahara K, Matsumura Y, Ui K, Kasahara K, Komatsu Y, Mikasa K, Kita E. Intranasal priming of newborn mice with microbial extracts increases opsonic factors and mature CD11c+ cells in the airway. Am J Physiol Lung Cell Mol Physiol 2012; 303:L834-43. [PMID: 22923643 DOI: 10.1152/ajplung.00031.2012] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Nasal exposure to the mixture of microbial extracts (MME) after ablactation enhanced airway resistance of newborn mice to Streptococcus pneumoniae (J Physiol Lung Cell Mol Physiol 298: L67, 2010). The present study was addressed to elucidate effective factors responsible for the enhanced innate resistance in the airway of MME-exposed newborn mice. MME exposure significantly increased the amount of pulmonary surfactants (SP-A and SP-D) in the airway. Bronchoalveolar lavage fluid of the exposed mice exhibited greater levels of opsonic activity, thereby enhancing the phagocytic and intracellular killing activities of alveolar macrophages (MØ) against S. pneumoniae. The exposure itself did not increase a complement component C3 and mannan-binding lectin-A (MBL-A) in the airway, whereas intratracheal infection with S. pneumoniae increased the quantity of SP-A, SP-D, C3, and MBL-A in the exposed mice to a significant extent compared with control mice. The exposure enhanced the expression of the class A scavenger MØ receptor with collagenous structure on alveolar MØ and also increased the frequency of major histocompatibility complex II+ CD11c+ cells in the lung; the cells were able to produce IL-10 and transforming growth factor-β in vitro. These results suggest that microbial exposure early in life increases the amounts of SP-A and SP-D and the number of scavenger MØ and also promotes maturation of CD11c+ cells in the airway of newborn mice, which may be involved in airway resistance to S. pneumoniae.
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Affiliation(s)
- Kazuki Kasahara
- Department of Bacteriology, Nara Medical University, School of Medicine, Kashihara, Japan
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37
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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: 123] [Impact Index Per Article: 10.3] [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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Soluble host defense lectins in innate immunity to influenza virus. J Biomed Biotechnol 2012; 2012:732191. [PMID: 22665991 PMCID: PMC3362216 DOI: 10.1155/2012/732191] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2011] [Accepted: 02/21/2012] [Indexed: 12/24/2022] Open
Abstract
Host defenses against viral infections depend on a complex interplay of innate (nonspecific) and adaptive (specific) components. In the early stages of infection, innate mechanisms represent the main line of host defense, acting to limit the spread of virus in host tissues prior to the induction of the adaptive immune response. Serum and lung fluids contain a range of lectins capable of recognizing and destroying influenza A viruses (IAV). Herein, we review the mechanisms by which soluble endogenous lectins mediate anti-IAV activity, including their role in modulating IAV-induced inflammation and disease and their potential as prophylactic and/or therapeutic treatments during severe IAV-induced disease.
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Fournier B, Andargachew R, Robin AZ, Laur O, Voelker DR, Lee WY, Weber D, Parkos CA. Surfactant protein D (Sp-D) binds to membrane-proximal domain (D3) of signal regulatory protein α (SIRPα), a site distant from binding domain of CD47, while also binding to analogous region on signal regulatory protein β (SIRPβ). J Biol Chem 2012; 287:19386-98. [PMID: 22511785 DOI: 10.1074/jbc.m111.324533] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Signal regulatory protein α (SIRPα), a highly glycosylated type-1 transmembrane protein, is composed of three immunoglobulin-like extracellular loops as well as a cytoplasmic tail containing three classical tyrosine-based inhibitory motifs. Previous reports indicate that SIRPα binds to humoral pattern recognition molecules in the collectin family, namely surfactant proteins D and A (Sp-D and Sp-A, respectively), which are heavily expressed in the lung and constitute one of the first lines of innate immune defense against pathogens. However, little is known about molecular details of the structural interaction of Sp-D with SIRPs. In the present work, we examined the molecular basis of Sp-D binding to SIRPα using domain-deleted mutant proteins. We report that Sp-D binds to the membrane-proximal Ig domain (D3) of SIRPα in a calcium- and carbohydrate-dependent manner. Mutation of predicted N-glycosylation sites on SIRPα indicates that Sp-D binding is dependent on interactions with specific N-glycosylated residues on the membrane-proximal D3 domain of SIRPα. Given the remarkable sequence similarity of SIRPα to SIRPβ and the lack of known ligands for the latter, we examined Sp-D binding to SIRPβ. Here, we report specific binding of Sp-D to the membrane-proximal D3 domain of SIRPβ. Further studies confirmed that Sp-D binds to SIRPα expressed on human neutrophils and differentiated neutrophil-like cells. Because the other known ligand of SIRPα, CD47, binds to the membrane-distal domain D1, these findings indicate that multiple, distinct, functional ligand binding sites are present on SIRPα that may afford differential regulation of receptor function.
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Affiliation(s)
- Bénédicte Fournier
- Epithelial Pathobiology Research Unit, Department of Pathology and Laboratory Medicine, Emory University School of Medicine, Atlanta, Georgia 30322, USA.
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Stidsen JV, Khorooshi R, Rahbek MKU, Kirketerp-Møller KL, Hansen PBL, Bie P, Kejling K, Mandrup S, Hawgood S, Nielsen O, Nielsen CH, Owens T, Holmskov U, Sørensen GL. Surfactant protein d deficiency in mice is associated with hyperphagia, altered fat deposition, insulin resistance, and increased basal endotoxemia. PLoS One 2012; 7:e35066. [PMID: 22509382 PMCID: PMC3324408 DOI: 10.1371/journal.pone.0035066] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2011] [Accepted: 03/09/2012] [Indexed: 12/18/2022] Open
Abstract
Pulmonary surfactant protein D (SP-D) is a host defence lectin of the innate immune system that enhances clearance of pathogens and modulates inflammatory responses. Recently it has been found that systemic SP-D is associated with metabolic disturbances and that SP-D deficient mice are mildly obese. However, the mechanism behind SP-D's role in energy metabolism is not known. Here we report that SP-D deficient mice had significantly higher ad libitum energy intake compared to wild-type mice and unchanged energy expenditure. This resulted in accumulation but also redistribution of fat tissue. Blood pressure was unchanged. The change in energy intake was unrelated to the basal levels of hypothalamic Pro-opiomelanocortin (POMC) and Agouti-related peptide (AgRP) gene expression. Neither short time systemic, nor intracereberoventricular SP-D treatment altered the hypothalamic signalling or body weight accumulation. In ad libitum fed animals, serum leptin, insulin, and glucose were significantly increased in mice deficient in SP-D, and indicative of insulin resistance. However, restricted diets eliminated all metabolic differences except the distribution of body fat. SP-D deficiency was further associated with elevated levels of systemic bacterial lipopolysaccharide. In conclusion, our findings suggest that lack of SP-D mediates modulation of food intake not directly involving hypothalamic regulatory pathways. The resulting accumulation of adipose tissue was associated with insulin resistance. The data suggest SP-D as a regulator of energy intake and body composition and an inhibitor of metabolic endotoxemia. SP-D may play a causal role at the crossroads of inflammation, obesity, and insulin resistance.
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Affiliation(s)
- Jacob V. Stidsen
- Cardiovascular and Renal Research, Institute for Molecular Medicine, University of Southern Denmark, Odense, Denmark
| | - Reza Khorooshi
- Department of Neurobiology Research, Institute for Molecular Medicine, University of Southern Denmark, Odense, Denmark
| | - Martin K. U. Rahbek
- Cardiovascular and Renal Research, Institute for Molecular Medicine, University of Southern Denmark, Odense, Denmark
| | - Katrine L. Kirketerp-Møller
- Cardiovascular and Renal Research, Institute for Molecular Medicine, University of Southern Denmark, Odense, Denmark
| | - Pernille B. L. Hansen
- Cardiovascular and Renal Research, Institute for Molecular Medicine, University of Southern Denmark, Odense, Denmark
| | - Peter Bie
- Cardiovascular and Renal Research, Institute for Molecular Medicine, University of Southern Denmark, Odense, Denmark
| | - Karin Kejling
- Cardiovascular and Renal Research, Institute for Molecular Medicine, University of Southern Denmark, Odense, Denmark
| | - Susanne Mandrup
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
| | - Samuel Hawgood
- School of Medicine, University of California San Francisco, San Francisco, United States of America
| | - Ole Nielsen
- Department of Pathology, Odense University Hospital, Odense, Denmark
| | - Claus H. Nielsen
- Institute for Inflammation Research, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark
| | - Trevor Owens
- Department of Neurobiology Research, Institute for Molecular Medicine, University of Southern Denmark, Odense, Denmark
| | - Uffe Holmskov
- Cardiovascular and Renal Research, Institute for Molecular Medicine, University of Southern Denmark, Odense, Denmark
| | - Grith L. Sørensen
- Cardiovascular and Renal Research, Institute for Molecular Medicine, University of Southern Denmark, Odense, Denmark
- * E-mail:
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Doss M, Ruchala P, Tecle T, Gantz D, Verma A, Hartshorn A, Crouch EC, Luong H, Micewicz ED, Lehrer RI, Hartshorn KL. Hapivirins and diprovirins: novel θ-defensin analogs with potent activity against influenza A virus. THE JOURNAL OF IMMUNOLOGY 2012; 188:2759-68. [PMID: 22345650 DOI: 10.4049/jimmunol.1101335] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
θ-Defensins are cyclic octadecapeptides found in nonhuman primates whose broad antiviral spectrum includes HIV-1, HSV-1, severe acute respiratory syndrome coronavirus, and influenza A virus (IAV). We previously reported that synthetic θ-defensins called retrocyclins can neutralize and aggregate various strains of IAV and increase IAV uptake by neutrophils. This study describes two families of peptides, hapivirins and diprovirins, whose design was inspired by retrocyclins. The goal was to develop smaller partially cyclic peptides that retain the antiviral activity of retrocyclins, while being easier to synthesize. The novel peptides also allowed for systemic substitution of key residues to evaluate the role of charge or hydrophobicity on antiviral activity. Seventy-two hapivirin or diprovirin peptides are described in this work, including several whose anti-IAV activity equals or exceeds that of normal α- or θ-defensins. Some of these also had strong antibacterial and antifungal activity. These new peptides were active against H3N2 and H1N1 strains of IAV. Structural features imparting strong antiviral activity were identified through iterative cycles of synthesis and testing. Our findings show the importance of hydrophobic residues for antiviral activity and show that pegylation, which often increases a peptide's serum t(1/2) in vivo, can increase the antiviral activity of DpVs. The new peptides acted at an early phase of viral infection, and, when combined with pulmonary surfactant protein D, their antiviral effects were additive. The peptides strongly increased neutrophil and macrophage uptake of IAV, while inhibiting monocyte cytokine generation. Development of modified θ-defensin analogs provides an approach for creating novel antiviral agents for IAV infections.
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Affiliation(s)
- Mona Doss
- Department of Medicine, Boston University School of Medicine, Boston, MA 02118, USA
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Crouch E, Nikolaidis N, McCormack FX, McDonald B, Allen K, Rynkiewicz MJ, Cafarella TM, White M, Lewnard K, Leymarie N, Zaia J, Seaton BA, Hartshorn KL. Mutagenesis of surfactant protein D informed by evolution and x-ray crystallography enhances defenses against influenza A virus in vivo. J Biol Chem 2011; 286:40681-92. [PMID: 21965658 DOI: 10.1074/jbc.m111.300673] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The recognition of influenza A virus (IAV) by surfactant protein D (SP-D) is mediated by interactions between the SP-D carbohydrate recognition domains (CRD) and glycans displayed on envelope glycoproteins. Although native human SP-D shows potent antiviral and aggregating activity, trimeric recombinant neck+CRDs (NCRDs) show little or no capacity to influence IAV infection. A mutant trimeric NCRD, D325A/R343V, showed marked hemagglutination inhibition and viral neutralization, with viral aggregation and aggregation-dependent viral uptake by neutrophils. D325A/R343V exhibited glucose-sensitive binding to Phil82 hemagglutinin trimer (HA) by surface plasmon resonance. By contrast, there was very low binding to the HA trimer from another virus (PR8) that lacks glycans on the HA head. Mass spectrometry demonstrated the presence of high mannose glycans on the Phil82 HA at positions known to contribute to IAV binding. Molecular modeling predicted an enhanced capacity for bridging interactions between HA glycans and D325A/R343V. Finally, the trimeric D325A/R343V NCRD decreased morbidity and increased viral clearance in a murine model of IAV infection using a reassortant A/WSN/33 virus with a more heavily glycosylated HA. The combined data support a model in which altered binding by a truncated mutant SP-D to IAV HA glycans facilitates viral aggregation, leading to significant viral neutralization in vitro and in vivo. These studies demonstrate the potential utility of homology modeling and protein structure analysis for engineering effective collectin antivirals as in vivo therapeutics.
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Affiliation(s)
- Erika Crouch
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
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Lingappa JR, Dumitrescu L, Zimmer SM, Lynfield R, McNicholl JM, Messonnier NE, Whitney CG, Crawford DC. Identifying host genetic risk factors in the context of public health surveillance for invasive pneumococcal disease. PLoS One 2011; 6:e23413. [PMID: 21858107 PMCID: PMC3156135 DOI: 10.1371/journal.pone.0023413] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2011] [Accepted: 07/16/2011] [Indexed: 11/18/2022] Open
Abstract
Host genetic factors that modify risk of pneumococcal disease may help target future public health interventions to individuals at highest risk of disease. We linked data from population-based surveillance for invasive pneumococcal disease (IPD) with state-based newborn dried bloodspot repositories to identify biological samples from individuals who developed invasive pneumococcal disease. Genomic DNA was extracted from 366 case and 732 anonymous control samples. TagSNPs were selected in 34 candidate genes thought to be associated with host response to invasive pneumococcal disease, and a total of 326 variants were successfully genotyped. Among 543 European Americans (EA) (182 cases and 361 controls), and 166 African Americans (AA) (53 cases and 113 controls), common variants in surfactant protein D (SFTPD) are consistently underrepresented in IPD. SFTPD variants with the strongest association for IPD are intronic rs17886286 (allelic OR 0.45, 95% confidence interval (CI) [0.25, 0.82], with p = 0.007) in EA and 5' flanking rs12219080 (allelic OR 0.32, 95%CI [0.13, 0.78], with p = 0.009) in AA. Variants in CD46 and IL1R1 are also associated with IPD in both EA and AA, but with effects in different directions; FAS, IL1B, IL4, IL10, IL12B, SFTPA1, SFTPB, and PTAFR variants are associated (p≤0.05) with IPD in EA or AA. We conclude that variants in SFTPD may protect against IPD in EA and AA and genetic variation in other host response pathways may also contribute to risk of IPD. While our associations are not corrected for multiple comparisons and therefore must be replicated in additional cohorts, this pilot study underscores the feasibility of integrating public health surveillance with existing, prospectively collected, newborn dried blood spot repositories to identify host genetic factors associated with infectious diseases.
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Affiliation(s)
- Jairam R Lingappa
- Department of Global Health, University of Washington, Seattle, Washington, United States of America.
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Sims MW, Beers MF, Ahya VN, Kawut SM, Sims KD, Lederer DJ, Palmer SM, Wille K, Lama VN, Shah PD, Orens JB, Bhorade S, Crespo M, Weinacker A, Demissie E, Bellamy S, Christie JD, Ware LB. Effect of single vs bilateral lung transplantation on plasma surfactant protein D levels in idiopathic pulmonary fibrosis. Chest 2011; 140:489-496. [PMID: 21349925 DOI: 10.1378/chest.10-2065] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
BACKGROUND Serum levels of surfactant protein D (SP-D) have been suggested as reflecting epithelial damage in acute lung injury, COPD, and idiopathic pulmonary fibrosis (IPF). However, little is known about SP-D levels in the setting of lung transplantation. METHODS We examined plasma SP-D levels in 104 subjects from a prospective, multicenter cohort study of lung allograft recipients. Plasma SP-D was measured by enzyme-linked immunosorbent assay prior to transplant and daily for 3 days after transplant. RESULTS Subjects undergoing transplant for IPF had higher baseline SP-D levels (median, 325 ng/mL) compared with subjects with cystic fibrosis, COPD, and pulmonary hypertension (median, 100, 80, and 82 ng/mL, respectively; P = .0001). Among subjects with IPF undergoing bilateral transplant, SP-D levels declined rapidly postoperatively. In contrast, SP-D levels in subjects undergoing single lung transplant for IPF remained significantly higher than those of bilateral allograft recipients. Among subjects undergoing single lung transplant for IPF, the development of primary graft dysfunction (PGD) was associated with a subsequent rise in SP-D levels, whereas SP-D levels in IPF subjects undergoing bilateral transplant declined, even in the presence of grade 3 PGD. Importantly, single lung allograft recipients without PGD had higher postoperative SP-D levels than bilateral allograft recipients with PGD. CONCLUSIONS Subjects undergoing lung transplant for IPF have significantly higher baseline plasma SP-D levels compared with those with other diagnoses. Plasma SP-D is likely a biomarker of the air-blood barrier integrity in the native IPF lung, but may be less useful as a biomarker of PGD after transplant.
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Affiliation(s)
- Michael W Sims
- Division of Pulmonary, Allergy, and Critical Care Medicine, University of Pennsylvania School of Medicine, Philadelphia, PA.
| | - Michael F Beers
- Division of Pulmonary, Allergy, and Critical Care Medicine, University of Pennsylvania School of Medicine, Philadelphia, PA
| | - Vivek N Ahya
- Division of Pulmonary, Allergy, and Critical Care Medicine, University of Pennsylvania School of Medicine, Philadelphia, PA
| | - Steven M Kawut
- Division of Pulmonary, Allergy, and Critical Care Medicine, University of Pennsylvania School of Medicine, Philadelphia, PA; Department of Biostatistics and Epidemiology, University of Pennsylvania School of Medicine, Philadelphia, PA
| | - Karen D Sims
- Division of Infectious Diseases, University of Pennsylvania School of Medicine, Philadelphia, PA
| | - David J Lederer
- Division of Pulmonary, Allergy, and Critical Care Medicine, Columbia University College of Physicians and Surgeons, New York City, NY
| | - Scott M Palmer
- Division of Pulmonary, Allergy, and Critical Care Medicine, Duke University School of Medicine, Durham, NC
| | - Keith Wille
- Division of Pulmonary, Allergy, and Critical Care Medicine, University of Alabama at Birmingham, Ann Arbor, MI
| | - Vibha N Lama
- Division of Pulmonary and Critical Care Medicine, University of Michigan Health System, Ann Arbor, MI
| | - Pali D Shah
- Division of Allergy, Pulmonary, and Critical Care Medicine, Vanderbilt University School of Medicine, Nashville TN
| | - Jonathan B Orens
- Division of Pulmonary and Critical Care Medicine, The Johns Hopkins University School of Medicine, Baltimore, MD
| | - Sangeeta Bhorade
- Division of Pulmonary and Critical Care Medicine, University of Chicago Medical Center, Chicago, IL
| | - Maria Crespo
- Division of Pulmonary, Allergy, and Critical Care Medicine, University of Pittsburgh Medical Center, Pittsburgh, PA
| | - Ann Weinacker
- Division of Pulmonary and Critical Care Medicine, Stanford University School of Medicine, Stanford, CA
| | - Ejigayehu Demissie
- Department of Biostatistics and Epidemiology, University of Pennsylvania School of Medicine, Philadelphia, PA
| | - Scarlett Bellamy
- Department of Biostatistics and Epidemiology, University of Pennsylvania School of Medicine, Philadelphia, PA
| | - Jason D Christie
- Division of Pulmonary, Allergy, and Critical Care Medicine, University of Pennsylvania School of Medicine, Philadelphia, PA; Department of Biostatistics and Epidemiology, University of Pennsylvania School of Medicine, Philadelphia, PA
| | - Lorraine B Ware
- Division of Allergy, Pulmonary, and Critical Care Medicine, Vanderbilt University School of Medicine, Nashville TN
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Miyamoto T, Takanashi M, Horino R, Yamanaka H, Narita M. Development of enzyme-linked immunosorbent assay for bovine surfactant protein D in bronchoalveolar lavage fluid. J Vet Med Sci 2010; 72:1337-43. [PMID: 20526045 DOI: 10.1292/jvms.10-0101] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Surfactant protein D (SP-D) is a pattern recognition molecule that has an important role in pulmonary host defense. In this study, we developed an enzyme-linked immunosorbent assay (ELISA) for bovine SP-D and determined the concentration of SP-D in bronchoalveolar lavage fluid (BALF) from calves. Bovine SP-D was purified from BALF using a mannose-Shepharose 6B column. The obtained 44 kDa protein was identified as bovine SP-D by N-terminal amino acid sequence analysis and SDS-PAGE analysis. The peptides corresponding to bovine SP-D amino acid residues SDTRKEGT, which have little homology across bovine serum collectins, were synthesized and used to raise an antibody in rabbits. The obtained antibody was specific for bovine SP-D and did not react with collectins in serum. The anti-bovine SP-D antibody was purified and an ELISA system was developed. The detection range of this assay was 4-125 ng/ml, and the intra-assay and inter-assay coefficients of variation were 5.6 and 9.7%, respectively. The concentrations of SP-D in BALF collected from calves experimentally infected with bovine adenovirus type-3 or Mannheimia haemolytica were determined by the ELISA. Elevation of SP-D was found in BALF from inoculated lobes of infected calves compared with those of non-inoculated lobes and those from control animals. These data suggest that the ELISA developed in this study may be available to investigate the physiological role of bovine SP-D in bovine lung.
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Affiliation(s)
- Toru Miyamoto
- Production Disease Research Team, National Institute of Animal Health, Kannondai, Tsukuba, Ibaraki, Japan.
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Atochina-Vasserman EN, Beers MF, Gow AJ. Review: Chemical and structural modifications of pulmonary collectins and their functional consequences. Innate Immun 2010; 16:175-82. [PMID: 20423921 PMCID: PMC4361894 DOI: 10.1177/1753425910368871] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
The lung is continuously exposed to inhaled pathogens (toxic pollutants, micro-organisms, environmental antigens, allergens) from the external environment. In the broncho-alveolar space, the critical balance between a measured protective response against harmful pathogens and an inappropriate inflammatory response to harmless particles is discerned by the innate pulmonary immune system. Among its many components, the surfactant proteins and specifically the pulmonary collectins (surfactant proteins A [SP-A] and D [SP-D]) appear to provide important contributions to the modulation of host defense and inflammation in the lung. Many studies have shown that multimerization of SP-A and SP-D are important for efficient local host defense including neutralization and opsonization of influenza A virus, binding Pneumocystis murina and inhibition of LPS-induced inflammatory cell responses. These observations strongly imply that oligomerization of collectins is a critical feature of its function. However, during the inflammatory state, despite normal pool sizes, chemical modification of collectins can result in alteration of their structure and function. Both pulmonary collectins can be altered through proteolytic inactivation, nitration, S-nitrosylation, oxidation and/or crosslinking as a consequence of the inflammatory milieu facilitated by cytokines, nitric oxide, proteases, and other chemical mediators released by inflammatory cells. Thus, this review will summarize recent developments in our understanding of the relationship between post-translational assembly of collectins and their modification by inflammation as an important molecular switch for the regulation of local innate host defense.
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47
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Christensen AF, Hoegh SV, Lottenburger T, Holmskov U, Tornoe I, Hørslev-Petersen K, Sørensen GL, Junker P. Circadian rhythm and the influence of physical activity on circulating surfactant protein D in early and long-standing rheumatoid arthritis. Rheumatol Int 2010; 31:1617-23. [DOI: 10.1007/s00296-010-1538-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2010] [Accepted: 05/16/2010] [Indexed: 01/10/2023]
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48
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Phelps DS. Surfactant Regulation of Host Defense Function in the Lung: A Question of Balance. ACTA ACUST UNITED AC 2010. [DOI: 10.1080/15513810109168822] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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49
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Gulla KC, Gupta K, Krarup A, Gal P, Schwaeble WJ, Sim RB, O'Connor CD, Hajela K. Activation of mannan-binding lectin-associated serine proteases leads to generation of a fibrin clot. Immunology 2010; 129:482-95. [PMID: 20002787 PMCID: PMC2842495 DOI: 10.1111/j.1365-2567.2009.03200.x] [Citation(s) in RCA: 112] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2009] [Revised: 10/11/2009] [Accepted: 10/14/2009] [Indexed: 01/19/2023] Open
Abstract
The lectin pathway of complement is activated upon binding of mannan-binding lectin (MBL) or ficolins (FCNs) to their targets. Upon recognition of targets, the MBL-and FCN-associated serine proteases (MASPs) are activated, allowing them to generate the C3 convertase C4b2a. Recent findings indicate that the MASPs also activate components of the coagulation system. We have previously shown that MASP-1 has thrombin-like activity whereby it cleaves and activates fibrinogen and factor XIII. MASP-2 has factor Xa-like activity and activates prothrombin through cleavage to form thrombin. We now report that purified L-FCN-MASPs complexes, bound from serum to N-acetylcysteine-Sepharose, or MBL-MASPs complexes, bound to mannan-agarose, generate clots when incubated with calcified plasma or purified fibrinogen and factor XIII. Plasmin digestion of the clot and analysis using anti-D-dimer antibodies revealed that the clot was made up of fibrin and was similar to that generated by thrombin in normal human plasma. Fibrinopeptides A and B (FPA and FPB, respectively) were released after fibrinogen cleavage by L-FCN-MASPs complexes captured on N-acetylcysteine-Sepharose. Studies of inhibition of fibrinopeptide release indicated that the dominant pathway for clotting catalysed by the MASPs is via MASP-2 and prothrombin activation, as hirudin, a thrombin inhibitor that does not inhibit MASP-1 and MASP-2, substantially inhibits fibrinopeptide release. In the light of their potent chemoattractant effects on neutrophil and fibroblast recruitment, the MASP-mediated release of FPA and FPB may play a role in early immune activation. Additionally, MASP-catalysed deposition and polymerization of fibrin on the surface of micro-organisms may be protective by limiting the dissemination of infection.
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50
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Christensen AF, Sørensen GL, Hørslev-Petersen K, Holmskov U, Lindegaard HM, Junker K, Hetland ML, Stengaard-Pedersen K, Jacobsen S, Lottenburger T, Ellingsen T, Andersen LS, Hansen I, Skjødt H, Pedersen JK, Lauridsen UB, Svendsen A, Tarp U, Pødenphant J, Vestergaard A, Jurik AG, Østergaard M, Junker P. Circulating surfactant protein -D is low and correlates negatively with systemic inflammation in early, untreated rheumatoid arthritis. Arthritis Res Ther 2010; 12:R39. [PMID: 20211020 PMCID: PMC2888186 DOI: 10.1186/ar2948] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2009] [Revised: 01/11/2010] [Accepted: 03/08/2010] [Indexed: 01/05/2023] Open
Abstract
INTRODUCTION Surfactant protein D (SP-D) is a collectin with immuno-regulatory functions, which may depend on oligomerization. Anti-microbial and anti-inflammatory properties have been attributed to multimeric SP-D variants, while trimeric subunits per se have been suggested to enhance inflammation. Previously, we reported low circulating SP-D in early rheumatoid arthritis (RA), and the present investigation aims to extend these data by serial SP-D serum measurements, studies on synovial fluid, SP-D size distribution and genotyping in patients with early RA. METHODS One-hundred-and-sixty disease-modifying antirheumatic drug (DMARD) naïve RA patients with disease duration less than six months were studied prospectively for four years (CIMESTRA (Ciclosporine, Methotrexate, Steroid in RA) trial) including disease activity measures (C-reactive protein, joint counts and Health Assessment Questionnaire (HAQ) score), autoantibodies, x-ray findings and SP-D. SP-D was quantified by enzyme-linked immunosorbent assay (ELISA) and molecular size distribution was assessed by gel filtration chromatography. Further, SP-D Met11Thr single nucleotide polymorphism (SNP) analysis was performed. RESULTS Serum SP-D was significantly lower in RA patients at baseline compared with healthy controls (P < 0.001). SP-D increased slightly during follow-up (P < 0.001), but was still subnormal at four years after adjustment for confounders (P < 0.001). SP-D in synovial fluid was up to 2.5-fold lower than in serum. While multimeric variants were detected in serum, SP-D in synovial fluid comprised trimeric subunits only. There were no significant associations between genotype distribution and SP-D. Baseline SP-D was inversely associated to CRP and HAQ score. A similar relationship was observed regarding temporal changes in SP-D and CRP (zero to four years). SP-D was not associated to x-ray findings. CONCLUSIONS This study confirms that circulating SP-D is persistently subnormal in early and untreated RA despite a favourable therapeutic response obtained during four years of follow-up. SP-D correlated negatively to disease activity measures, but was not correlated with x-ray progression or SP-D genotype. These observations suggest that SP-D is implicated in RA pathogenesis at the protein level. The exclusive presence of trimeric SP-D in affected joints may contribute to the maintenance of joint inflammation. TRIAL REGISTRATION (j.nr NCT00209859).
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