1
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Manna S, McAuley J, Jacobson J, Nguyen CD, Ullah MA, Sebina I, Williamson V, Mulholland EK, Wijburg O, Phipps S, Satzke C. Synergism and Antagonism of Bacterial-Viral Coinfection in the Upper Respiratory Tract. mSphere 2022; 7:e0098421. [PMID: 35044807 PMCID: PMC8769199 DOI: 10.1128/msphere.00984-21] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Accepted: 12/28/2021] [Indexed: 01/03/2023] Open
Abstract
Streptococcus pneumoniae (the pneumococcus) is a leading cause of pneumonia in children under 5 years of age. Coinfection by pneumococci and respiratory viruses enhances disease severity. Little is known about pneumococcal coinfections with respiratory syncytial virus (RSV). Here, we developed a novel infant mouse model of coinfection using pneumonia virus of mice (PVM), a murine analogue of RSV, to examine the dynamics of coinfection in the upper respiratory tract, an anatomical niche that is essential for host-to-host transmission and progression to disease. Coinfection increased damage to the nasal tissue and increased production of the chemokine CCL3. Nasopharyngeal pneumococcal density and shedding in nasal secretions were increased by coinfection. In contrast, coinfection reduced PVM loads in the nasopharynx, an effect that was independent of pneumococcal strain and the order of infection. We showed that this "antagonistic" effect was absent using either ethanol-killed pneumococci or a pneumococcal mutant deficient in capsule production and incapable of nasopharyngeal carriage. Colonization with a pneumococcal strain naturally unable to produce capsule also reduced viral loads. The pneumococcus-mediated reduction in PVM loads was caused by accelerated viral clearance from the nasopharynx. Although these synergistic and antagonistic effects occurred with both wild-type pneumococcal strains used in this study, the magnitude of the effects was strain dependent. Lastly, we showed that pneumococci can also antagonize influenza virus. Taken together, our study has uncovered multiple novel facets of bacterial-viral coinfection. Our findings have important public health implications, including for bacterial and viral vaccination strategies in young children. IMPORTANCE Respiratory bacterial-viral coinfections (such as pneumococci and influenza virus) are often synergistic, resulting in enhanced disease severity. Although colonization of the nasopharynx is the precursor to disease and transmission, little is known about bacterial-viral interactions that occur within this niche. In this study, we developed a novel mouse model to examine pneumococcal-viral interactions in the nasopharynx with pneumonia virus of mice (PVM) and influenza. We found that PVM infection benefits pneumococci by increasing their numbers in the nasopharynx and shedding of these bacteria in respiratory secretions. In contrast, we discovered that pneumococci decrease PVM numbers by accelerating viral clearance. We also report a similar effect of pneumococci on influenza. By showing that coinfections lead to both synergistic and antagonistic outcomes, our findings challenge the existing dogma in the field. Our work has important applications and implications for bacterial and viral vaccines that target these microbes.
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Affiliation(s)
- Sam Manna
- Infection and Immunity, Murdoch Children’s Research Institute, Royal Children's Hospital, Parkville, Victoria, Australia
- Department of Paediatrics, The University of Melbourne, Parkville, Victoria, Australia
- Department of Microbiology and Immunology at the Peter Doherty Institute for Infection and Immunity, The University of Melbourne, Melbourne, Victoria, Australia
| | - Julie McAuley
- Department of Microbiology and Immunology at the Peter Doherty Institute for Infection and Immunity, The University of Melbourne, Melbourne, Victoria, Australia
| | - Jonathan Jacobson
- Infection and Immunity, Murdoch Children’s Research Institute, Royal Children's Hospital, Parkville, Victoria, Australia
| | - Cattram D. Nguyen
- Infection and Immunity, Murdoch Children’s Research Institute, Royal Children's Hospital, Parkville, Victoria, Australia
- Department of Paediatrics, The University of Melbourne, Parkville, Victoria, Australia
| | - Md. Ashik Ullah
- Respiratory Immunology Laboratory, QIMR Berghofer Medical Research Institute, Herston, Queensland, Australia
| | - Ismail Sebina
- Respiratory Immunology Laboratory, QIMR Berghofer Medical Research Institute, Herston, Queensland, Australia
| | - Victoria Williamson
- Infection and Immunity, Murdoch Children’s Research Institute, Royal Children's Hospital, Parkville, Victoria, Australia
| | - E. Kim Mulholland
- Infection and Immunity, Murdoch Children’s Research Institute, Royal Children's Hospital, Parkville, Victoria, Australia
- Department of Paediatrics, The University of Melbourne, Parkville, Victoria, Australia
- Department of Infectious Disease Epidemiology, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Odilia Wijburg
- Department of Microbiology and Immunology at the Peter Doherty Institute for Infection and Immunity, The University of Melbourne, Melbourne, Victoria, Australia
| | - Simon Phipps
- Respiratory Immunology Laboratory, QIMR Berghofer Medical Research Institute, Herston, Queensland, Australia
| | - Catherine Satzke
- Infection and Immunity, Murdoch Children’s Research Institute, Royal Children's Hospital, Parkville, Victoria, Australia
- Department of Paediatrics, The University of Melbourne, Parkville, Victoria, Australia
- Department of Microbiology and Immunology at the Peter Doherty Institute for Infection and Immunity, The University of Melbourne, Melbourne, Victoria, Australia
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2
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McMillan CLD, Cheung STM, Modhiran N, Barnes J, Amarilla AA, Bielefeldt-Ohmann H, Lee LYY, Guilfoyle K, van Amerongen G, Stittelaar K, Jakon V, Lebas C, Reading P, Short KR, Young PR, Watterson D, Chappell KJ. Development of molecular clamp stabilized hemagglutinin vaccines for Influenza A viruses. NPJ Vaccines 2021; 6:135. [PMID: 34750396 PMCID: PMC8575991 DOI: 10.1038/s41541-021-00395-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Accepted: 10/01/2021] [Indexed: 11/25/2022] Open
Abstract
Influenza viruses cause a significant number of infections and deaths annually. In addition to seasonal infections, the risk of an influenza virus pandemic emerging is extremely high owing to the large reservoir of diverse influenza viruses found in animals and the co-circulation of many influenza subtypes which can reassort into novel strains. Development of a universal influenza vaccine has proven extremely challenging. In the absence of such a vaccine, rapid response technologies provide the best potential to counter a novel influenza outbreak. Here, we demonstrate that a modular trimerization domain known as the molecular clamp allows the efficient production and purification of conformationally stabilised prefusion hemagglutinin (HA) from a diverse range of influenza A subtypes. These clamp-stabilised HA proteins provided robust protection from homologous virus challenge in mouse and ferret models and some cross protection against heterologous virus challenge. This work provides a proof-of-concept for clamp-stabilised HA vaccines as a tool for rapid response vaccine development against future influenza A virus pandemics.
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Affiliation(s)
- Christopher L D McMillan
- School of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia, QLD, 4072, Australia.
| | - Stacey T M Cheung
- School of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia, QLD, 4072, Australia
| | - Naphak Modhiran
- School of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia, QLD, 4072, Australia
| | - James Barnes
- WHO Collaborating Centre for Reference and Research on Influenza, Peter Doherty Institute for Infection and Immunity, Melbourne, VIC, 3000, Australia
| | - Alberto A Amarilla
- School of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia, QLD, 4072, Australia
| | - Helle Bielefeldt-Ohmann
- School of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia, QLD, 4072, Australia.,Australian Infectious Diseases Research Centre, Global Virus Network Centre of Excellence, Brisbane, QLD, 4072 and 4029, Australia.,School of Veterinary Science, The University of Queensland Gatton Campus, Gatton, QLD, 4343, Australia
| | - Leo Yi Yang Lee
- WHO Collaborating Centre for Reference and Research on Influenza, Peter Doherty Institute for Infection and Immunity, Melbourne, VIC, 3000, Australia
| | - Kate Guilfoyle
- Viroclinics Xplore, Landerd Campus, Nistelrooise Baan 3, 5374 RE, Schaijk, The Netherlands
| | - Geert van Amerongen
- Viroclinics Xplore, Landerd Campus, Nistelrooise Baan 3, 5374 RE, Schaijk, The Netherlands
| | - Koert Stittelaar
- Viroclinics Xplore, Landerd Campus, Nistelrooise Baan 3, 5374 RE, Schaijk, The Netherlands
| | - Virginie Jakon
- Vaccine Formulation Institute, Chemin des Aulx 14, 1228 Plan-Les-Ouates, Geneva, Switzerland
| | - Celia Lebas
- Vaccine Formulation Institute, Chemin des Aulx 14, 1228 Plan-Les-Ouates, Geneva, Switzerland
| | - Patrick Reading
- WHO Collaborating Centre for Reference and Research on Influenza, Peter Doherty Institute for Infection and Immunity, Melbourne, VIC, 3000, Australia.,Department of Microbiology and Immunology, Peter Doherty Institute for Infection and Immunity, The University of Melbourne, Parkville, VIC, 3000, Australia
| | - Kirsty R Short
- School of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia, QLD, 4072, Australia.,Australian Infectious Diseases Research Centre, Global Virus Network Centre of Excellence, Brisbane, QLD, 4072 and 4029, Australia
| | - Paul R Young
- School of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia, QLD, 4072, Australia. .,Australian Infectious Diseases Research Centre, Global Virus Network Centre of Excellence, Brisbane, QLD, 4072 and 4029, Australia. .,The Australian Institute of Biotechnology and Nanotechnology, The University of Queensland, St Lucia, QLD, 4072, Australia.
| | - Daniel Watterson
- School of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia, QLD, 4072, Australia. .,Australian Infectious Diseases Research Centre, Global Virus Network Centre of Excellence, Brisbane, QLD, 4072 and 4029, Australia. .,The Australian Institute of Biotechnology and Nanotechnology, The University of Queensland, St Lucia, QLD, 4072, Australia.
| | - Keith J Chappell
- School of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia, QLD, 4072, Australia. .,Australian Infectious Diseases Research Centre, Global Virus Network Centre of Excellence, Brisbane, QLD, 4072 and 4029, Australia. .,The Australian Institute of Biotechnology and Nanotechnology, The University of Queensland, St Lucia, QLD, 4072, Australia.
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3
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Sinclair JE, Bloxham CJ, Chiu H, Chew KY, Russell J, Yoshikawa Y, Bielefeldt-Ohmann H, Steele LE, Hulme KD, Verzele NA, Noye EC, Wu M, Reichelt ME, Thomas WG, Gallo LA, Redd MA, Short KR. Type I Diabetes Mellitus Increases the Cardiovascular Complications of Influenza Virus Infection. Front Cell Infect Microbiol 2021; 11:714440. [PMID: 34595130 PMCID: PMC8476859 DOI: 10.3389/fcimb.2021.714440] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Accepted: 08/30/2021] [Indexed: 01/01/2023] Open
Abstract
People with diabetes mellitus are susceptible to both cardiovascular disease and severe influenza A virus infection. We hypothesized that diabetes also increases risks of influenza-associated cardiac complications. A murine type 1 (streptozotocin-induced) diabetes model was employed to investigate influenza-induced cardiac distress. Lung histopathology and viral titres revealed no difference in respiratory severity between infected control and diabetic mice. However, compared with infected control mice, infected diabetic mice had increased serum cardiac troponin I and creatine-kinase MB, left ventricular structural changes and right ventricular functional alterations, providing the first experimental evidence of type I diabetes increasing risks of influenza-induced cardiovascular complications.
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Affiliation(s)
- Jane E Sinclair
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD, Australia
| | - Conor J Bloxham
- School of Biomedical Sciences, The University of Queensland, Brisbane, QLD, Australia
| | - Han Chiu
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD, Australia
| | - Keng Yih Chew
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD, Australia
| | - Jake Russell
- School of Biomedical Sciences, The University of Queensland, Brisbane, QLD, Australia
| | - Yusuke Yoshikawa
- School of Biomedical Sciences, The University of Queensland, Brisbane, QLD, Australia
| | - Helle Bielefeldt-Ohmann
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD, Australia.,School of Veterinary Science, The University of Queensland, Brisbane, QLD, Australia
| | - Lauren E Steele
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD, Australia
| | - Katina D Hulme
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD, Australia
| | - Nathalie Aj Verzele
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD, Australia
| | - Ellesandra C Noye
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD, Australia
| | - Melanie Wu
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD, Australia
| | - Melissa E Reichelt
- School of Biomedical Sciences, The University of Queensland, Brisbane, QLD, Australia
| | - Walter G Thomas
- School of Biomedical Sciences, The University of Queensland, Brisbane, QLD, Australia
| | - Linda A Gallo
- School of Biomedical Sciences, The University of Queensland, Brisbane, QLD, Australia
| | - Meredith A Redd
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD, Australia
| | - Kirsty R Short
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD, Australia
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4
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Utility of Three Nebulizers in Investigating the Infectivity of Airborne Viruses. Appl Environ Microbiol 2021; 87:e0049721. [PMID: 34085856 DOI: 10.1128/aem.00497-21] [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] [Indexed: 11/20/2022] Open
Abstract
Laboratory-generated bioaerosols are widely used in aerobiology studies of viruses; however, few comparisons of alternative nebulizers exist. We compared aerosol production and virus survival for a Collison nebulizer, vibrating mesh nebulizer (VMN), and hydraulic spray atomizer (HSA). We also measured the dry size distribution of the aerosols produced and calculated the droplet sizes before evaporation and the dry size distribution from normal saline solution. Dry count median diameters of 0.11, 0.22, and 0.30 μm were found for normal saline from the Collison nebulizer, VMN, and HSA, respectively. The volume median diameters were 0.323, 1.70, and 1.30 μm, respectively. The effect of nebulization on the viability of two influenza A viruses (IAVs) (H1N1 and H3N2) and human rhinovirus 16 (HRV-16) was assessed by nebulization into an SKC BioSampler. The HSA had the least impact on surviving fractions (SFs) of H1N1 and H3N2 (89% ± 3% and 94% ± 2%, respectively), followed by the Collison nebulizer (83% ± 1% and 82% ± 2%, respectively). The VMN yielded SFs of 78% ± 2% and 76% ± 2%, respectively. Conversely, for HRV-16, the VMN produced higher SFs (87% ± 8%). Our findings indicate that there were no statistical differences between SFs of the viruses nebulized by these nebulizers. However, VMN produced higher aerosol concentrations within the airborne size range, making it more suitable where high aerosol mass production is required. IMPORTANCE Viral respiratory tract infections cause millions of lost days of work and physician visits globally, accounting for significant morbidity and mortality. Respiratory droplets and droplet nuclei from infected hosts are the potential carriers of such viruses within indoor environments. Laboratory-generated bioaerosols are applied in understanding the transmission and infection of viruses, modeling the physiological aspects of bioaerosol generation in a controlled environment. However, little comparative characterization exists for nebulizers used in infectious disease aerobiology, including Collison nebulizer, vibrating mesh nebulizer, and hydraulic spray atomizer. This study characterized the physical features of aerosols generated by laboratory nebulizers and their performance in producing aerosols at a size relevant to airborne transmission used in infectious disease aerobiology. We also determined the impact of nebulization mechanisms of these nebulizers on the viability of human respiratory viruses, including IAV H1N1, IAV H3N2, and HRV-16.
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5
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Briestenská K, Mikušová M, Tomčíková K, Kostolanský F, Varečková E. Quantification of bacteria by in vivo bioluminescence imaging in comparison with standard spread plate method and reverse transcription quantitative PCR (RT-qPCR). Arch Microbiol 2021; 203:4737-4742. [PMID: 34184097 PMCID: PMC8360831 DOI: 10.1007/s00203-021-02458-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2021] [Revised: 06/03/2021] [Accepted: 06/21/2021] [Indexed: 12/23/2022]
Abstract
In vivo bioluminescence imaging (BLI) offers a unique opportunity to analyze ongoing bacterial infections qualitatively and quantitatively in intact animals over time, leading to a reduction in the number of animals needed for a study. Since accurate determination of the bacterial burden plays an essential role in microbiological research, the present study aimed to evaluate the ability to quantify bacteria by non-invasive BLI technique in comparison to standard spread plate method and reverse transcription quantitative PCR (RT-qPCR). For this purpose, BALB/c mice were intranasally infected with 1 × 105 CFU of bioluminescent Streptococcus pneumoniae A66.1. At day 1 post-infection, the presence of S. pneumoniae in lungs was demonstrated by spread plate method and RT-qPCR, but not by in vivo BLI. However, on the second day p.i., the bioluminescent signal was already detectable, and the photon flux values positively correlated with CFU counts and RT-qPCR data within days 2–6. Though in vivo BLI is valuable research tool allowing the continuous monitoring and quantification of pneumococcal infection in living mice, it should be kept in mind that early in the infection, depending on the infective dose, the bioluminescent signal may be below the detection limit.
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Affiliation(s)
- Katarína Briestenská
- Biomedical Research Center of the Slovak Academy of Sciences, Institute of Virology, Dúbravská cesta 9, 845 05, Bratislava, Slovakia
| | - Miriam Mikušová
- Biomedical Research Center of the Slovak Academy of Sciences, Institute of Virology, Dúbravská cesta 9, 845 05, Bratislava, Slovakia
| | - Karolína Tomčíková
- Biomedical Research Center of the Slovak Academy of Sciences, Institute of Virology, Dúbravská cesta 9, 845 05, Bratislava, Slovakia
| | - František Kostolanský
- Biomedical Research Center of the Slovak Academy of Sciences, Institute of Virology, Dúbravská cesta 9, 845 05, Bratislava, Slovakia
| | - Eva Varečková
- Biomedical Research Center of the Slovak Academy of Sciences, Institute of Virology, Dúbravská cesta 9, 845 05, Bratislava, Slovakia.
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6
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Tong ZWM, Karawita AC, Kern C, Zhou H, Sinclair JE, Yan L, Chew KY, Lowther S, Trinidad L, Challagulla A, Schat KA, Baker ML, Short KR. Primary Chicken and Duck Endothelial Cells Display a Differential Response to Infection with Highly Pathogenic Avian Influenza Virus. Genes (Basel) 2021; 12:genes12060901. [PMID: 34200798 PMCID: PMC8230508 DOI: 10.3390/genes12060901] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Revised: 06/05/2021] [Accepted: 06/08/2021] [Indexed: 01/12/2023] Open
Abstract
Highly pathogenic avian influenza viruses (HPAIVs) in gallinaceous poultry are associated with viral infection of the endothelium, the induction of a ‘cytokine storm, and severe disease. In contrast, in Pekin ducks, HPAIVs are rarely endothelial tropic, and a cytokine storm is not observed. To date, understanding these species-dependent differences in pathogenesis has been hampered by the absence of a pure culture of duck and chicken endothelial cells. Here, we use our recently established in vitro cultures of duck and chicken aortic endothelial cells to investigate species-dependent differences in the response of endothelial cells to HPAIV H5N1 infection. We demonstrate that chicken and duck endothelial cells display a different transcriptional response to HPAI H5N1 infection in vitro—with chickens displaying a more pro-inflammatory response to infection. As similar observations were recorded following in vitro stimulation with the viral mimetic polyI:C, these findings were not specific to an HPAIV H5N1 infection. However, similar species-dependent differences in the transcriptional response to polyI:C were not observed in avian fibroblasts. Taken together, these data demonstrate that chicken and duck endothelial cells display a different response to HPAIV H5N1 infection, and this may help account for the species-dependent differences observed in inflammation in vivo.
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Affiliation(s)
- Zhen Wei Marcus Tong
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane 4072, Australia; (Z.W.M.T.); (A.C.K.); (J.E.S.); (L.Y.); (K.Y.C.)
| | - Anjana C. Karawita
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane 4072, Australia; (Z.W.M.T.); (A.C.K.); (J.E.S.); (L.Y.); (K.Y.C.)
- CSIRO, Australian Centre for Disease Preparedness, Health, and Biosecurity Business Unit, Geelong 3219, Australia; (S.L.); (L.T.); (A.C.); (M.L.B.)
| | - Colin Kern
- Department of Animal Science, University of California, Davis, CA 95616, USA; (C.K.); (H.Z.)
| | - Huaijun Zhou
- Department of Animal Science, University of California, Davis, CA 95616, USA; (C.K.); (H.Z.)
| | - Jane E. Sinclair
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane 4072, Australia; (Z.W.M.T.); (A.C.K.); (J.E.S.); (L.Y.); (K.Y.C.)
| | - Limin Yan
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane 4072, Australia; (Z.W.M.T.); (A.C.K.); (J.E.S.); (L.Y.); (K.Y.C.)
| | - Keng Yih Chew
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane 4072, Australia; (Z.W.M.T.); (A.C.K.); (J.E.S.); (L.Y.); (K.Y.C.)
| | - Sue Lowther
- CSIRO, Australian Centre for Disease Preparedness, Health, and Biosecurity Business Unit, Geelong 3219, Australia; (S.L.); (L.T.); (A.C.); (M.L.B.)
| | - Lee Trinidad
- CSIRO, Australian Centre for Disease Preparedness, Health, and Biosecurity Business Unit, Geelong 3219, Australia; (S.L.); (L.T.); (A.C.); (M.L.B.)
| | - Arjun Challagulla
- CSIRO, Australian Centre for Disease Preparedness, Health, and Biosecurity Business Unit, Geelong 3219, Australia; (S.L.); (L.T.); (A.C.); (M.L.B.)
| | - Karel A. Schat
- Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA;
| | - Michelle L. Baker
- CSIRO, Australian Centre for Disease Preparedness, Health, and Biosecurity Business Unit, Geelong 3219, Australia; (S.L.); (L.T.); (A.C.); (M.L.B.)
| | - Kirsty R. Short
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane 4072, Australia; (Z.W.M.T.); (A.C.K.); (J.E.S.); (L.Y.); (K.Y.C.)
- Australian Infectious Diseases Research Centre, The University of Queensland, Brisbane 4072, Australia
- Correspondence:
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7
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Hulme KD, Karawita AC, Pegg C, Bunte MJ, Bielefeldt-Ohmann H, Bloxham CJ, Van den Hoecke S, Setoh YX, Vrancken B, Spronken M, Steele LE, Verzele NA, Upton KR, Khromykh AA, Chew KY, Sukkar M, Phipps S, Short KR. A paucigranulocytic asthma host environment promotes the emergence of virulent influenza viral variants. eLife 2021; 10:61803. [PMID: 33588989 PMCID: PMC7886327 DOI: 10.7554/elife.61803] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Accepted: 01/23/2021] [Indexed: 12/12/2022] Open
Abstract
Influenza virus has a high mutation rate, such that within one host different viral variants can emerge. Evidence suggests that influenza virus variants are more prevalent in pregnant and/or obese individuals due to their impaired interferon response. We have recently shown that the non-allergic, paucigranulocytic subtype of asthma is associated with impaired type I interferon production. Here, we seek to address if this is associated with an increased emergence of influenza virus variants. Compared to controls, mice with paucigranulocytic asthma had increased disease severity and an increased emergence of influenza virus variants. Specifically, PB1 mutations exclusively detected in asthmatic mice were associated with increased polymerase activity. Furthermore, asthmatic host-derived virus led to increased disease severity in wild-type mice. Taken together, these data suggest that at least a subset of patients with asthma may be more susceptible to severe influenza and may be a possible source of new influenza virus variants.
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Affiliation(s)
- Katina D Hulme
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Australia
| | - Anjana C Karawita
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Australia
| | - Cassandra Pegg
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Australia
| | - Myrna Jm Bunte
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Australia
| | - Helle Bielefeldt-Ohmann
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Australia.,Australian Infectious Diseases Research Centre, The University of Queensland, Brisbane, Australia.,School of Veterinary Science, The University of Queensland, Brisbane, Australia
| | - Conor J Bloxham
- School of Biomedical Sciences, The University of Queensland, Brisbane, Australia
| | - Silvie Van den Hoecke
- VIB-UGent Center for Medical Biotechnology, Ghent, Belgium.,Department of Biomedical Molecular Biology, Ghent University, Ghent, Belgium
| | - Yin Xiang Setoh
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Australia.,Australian Infectious Diseases Research Centre, The University of Queensland, Brisbane, Australia.,Environmental Health Institute, National Environment Agency, Singapore, Singapore
| | - Bram Vrancken
- KU Leuven, Department of Microbiology and Immunology, Rega Institute, Laboratory of Evolutionary and Computational Virology, Leuven, Belgium
| | | | - Lauren E Steele
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Australia
| | - Nathalie Aj Verzele
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Australia
| | - Kyle R Upton
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Australia
| | - Alexander A Khromykh
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Australia.,Australian Infectious Diseases Research Centre, The University of Queensland, Brisbane, Australia
| | - Keng Yih Chew
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Australia
| | - Maria Sukkar
- Discipline of Pharmacy, Graduate School of Health, University of Technology Sydney, Australia; Woolcock Institute of Medical Research, Sydney Medical School, University of Sydney, NSW, Australia
| | - Simon Phipps
- Australian Infectious Diseases Research Centre, The University of Queensland, Brisbane, Australia.,QIMR Berghofer Medical Research Institute, Brisbane, Australia
| | - Kirsty R Short
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Australia.,Australian Infectious Diseases Research Centre, The University of Queensland, Brisbane, Australia
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8
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Hulme KD, Yan L, Marshall RJ, Bloxham CJ, Upton KR, Hasnain SZ, Bielefeldt-Ohmann H, Loh Z, Ronacher K, Chew KY, Gallo LA, Short KR. High glucose levels increase influenza-associated damage to the pulmonary epithelial-endothelial barrier. eLife 2020; 9:56907. [PMID: 32697191 PMCID: PMC7392605 DOI: 10.7554/elife.56907] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2020] [Accepted: 07/17/2020] [Indexed: 12/13/2022] Open
Abstract
Diabetes mellitus is a known susceptibility factor for severe influenza virus infections. However, the mechanisms that underlie this susceptibility remain incompletely understood. Here, the effects of high glucose levels on influenza severity were investigated using an in vitro model of the pulmonary epithelial-endothelial barrier as well as an in vivo murine model of type II diabetes. In vitro we show that high glucose conditions prior to IAV infection increased virus-induced barrier damage. This was associated with an increased pro-inflammatory response in endothelial cells and the subsequent damage of the epithelial junctional complex. These results were subsequently validated in vivo. This study provides the first evidence that hyperglycaemia may increase influenza severity by damaging the pulmonary epithelial-endothelial barrier and increasing pulmonary oedema. These data suggest that maintaining long-term glucose control in individuals with diabetes is paramount in reducing the morbidity and mortality associated with influenza virus infections.
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Affiliation(s)
- Katina D Hulme
- School of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia, Australia
| | - Limin Yan
- School of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia, Australia
| | - Rebecca J Marshall
- School of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia, Australia
| | - Conor J Bloxham
- School of Biomedical Sciences, The University of Queensland, Woolloongabba, Australia
| | - Kyle R Upton
- School of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia, Australia
| | - Sumaira Z Hasnain
- Mater Research Institute, The University of Queensland, Translational Research Institute, Woolloongabba, Australia
| | - Helle Bielefeldt-Ohmann
- School of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia, Australia.,Australian Infectious Diseases Research Centre, The University of Queensland, St Lucia, Australia
| | - Zhixuan Loh
- Institute for Molecular Bioscience, The University of Queensland, St. Lucia, Australia
| | - Katharina Ronacher
- Mater Research Institute, The University of Queensland, Translational Research Institute, Woolloongabba, Australia.,Australian Infectious Diseases Research Centre, The University of Queensland, St Lucia, Australia
| | - Keng Yih Chew
- School of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia, Australia
| | - Linda A Gallo
- School of Biomedical Sciences, The University of Queensland, Woolloongabba, Australia.,Mater Research Institute, The University of Queensland, Translational Research Institute, Woolloongabba, Australia
| | - Kirsty R Short
- School of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia, Australia.,Australian Infectious Diseases Research Centre, The University of Queensland, St Lucia, Australia
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9
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Abstract
Every winter, people with diabetes are at increased risk of severe influenza. At present, the mechanisms that cause this increased susceptibility are unclear. Here, we show that the fluctuations in blood glucose levels common in people with diabetes are associated with severe influenza. These data suggest that glycemic stability could become a greater clinical priority for patients with diabetes during outbreaks of influenza. People with diabetes are two times more likely to die from influenza than people with no underlying medical condition. The mechanisms underlying this susceptibility are poorly understood. In healthy individuals, small and short-lived postprandial peaks in blood glucose levels occur. In diabetes mellitus, these fluctuations become greater and more frequent. This glycemic variability is associated with oxidative stress and hyperinflammation. However, the contribution of glycemic variability to the pathogenesis of influenza A virus (IAV) has not been explored. Here, we used an in vitro model of the pulmonary epithelial-endothelial barrier and novel murine models to investigate the role of glycemic variability in influenza severity. In vitro, a history of glycemic variability significantly increased influenza-driven cell death and destruction of the epithelial-endothelial barrier. In vivo, influenza virus-infected mice with a history of glycemic variability lost significantly more body weight than mice with constant blood glucose levels. This increased disease severity was associated with markers of oxidative stress and hyperinflammation both in vitro and in vivo. Together, these results provide the first indication that glycemic variability may help drive the increased risk of severe influenza in people with diabetes mellitus.
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10
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Yeh HW, Wu T, Chen M, Ai HW. Identification of Factors Complicating Bioluminescence Imaging. Biochemistry 2019; 58:1689-1697. [PMID: 30810040 DOI: 10.1021/acs.biochem.8b01303] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In vivo bioluminescence imaging (BLI) has become a standard, non-invasive imaging modality for following gene expression or the fate of proteins and cells in living animals. Currently, bioluminescent reporters used in laboratories are mostly derivatives of two major luciferase families: ATP-dependent insect luciferases and ATP-independent marine luciferases. Inconsistent results of experiments using different bioluminescent reporters, such as Akaluc and Antareas2, have been reported. Herein, we re-examined the inconsistency in several experimental settings and identified the factors, such as ATP dependency, stability in serum, and molecular sizes of luciferases, that contributed to the observed differences. We expect this study will make the research community aware of these factors and facilitate more accurate interpretation of BLI data by considering the nature of each bioluminescent reporter.
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Affiliation(s)
- Hsien-Wei Yeh
- Center for Membrane and Cell Physiology, Department of Molecular Physiology and Biological Physics, Department of Chemistry, and UVA Cancer Center , University of Virginia , 1340 Jefferson Park Avenue , Charlottesville , Virginia 22908 , United States
| | - Tianchen Wu
- Center for Membrane and Cell Physiology, Department of Molecular Physiology and Biological Physics, Department of Chemistry, and UVA Cancer Center , University of Virginia , 1340 Jefferson Park Avenue , Charlottesville , Virginia 22908 , United States
| | - Minghai Chen
- Center for Membrane and Cell Physiology, Department of Molecular Physiology and Biological Physics, Department of Chemistry, and UVA Cancer Center , University of Virginia , 1340 Jefferson Park Avenue , Charlottesville , Virginia 22908 , United States
| | - Hui-Wang Ai
- Center for Membrane and Cell Physiology, Department of Molecular Physiology and Biological Physics, Department of Chemistry, and UVA Cancer Center , University of Virginia , 1340 Jefferson Park Avenue , Charlottesville , Virginia 22908 , United States
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11
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Avci P, Karimi M, Sadasivam M, Antunes-Melo WC, Carrasco E, Hamblin MR. In-vivo monitoring of infectious diseases in living animals using bioluminescence imaging. Virulence 2017; 9:28-63. [PMID: 28960132 PMCID: PMC6067836 DOI: 10.1080/21505594.2017.1371897] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Traditional methods of localizing and quantifying the presence of pathogenic microorganisms in living experimental animal models of infections have mostly relied on sacrificing the animals, dissociating the tissue and counting the number of colony forming units. However, the discovery of several varieties of the light producing enzyme, luciferase, and the genetic engineering of bacteria, fungi, parasites and mice to make them emit light, either after administration of the luciferase substrate, or in the case of the bacterial lux operon without any exogenous substrate, has provided a new alternative. Dedicated bioluminescence imaging (BLI) cameras can record the light emitted from living animals in real time allowing non-invasive, longitudinal monitoring of the anatomical location and growth of infectious microorganisms as measured by strength of the BLI signal. BLI technology has been used to follow bacterial infections in traumatic skin wounds and burns, osteomyelitis, infections in intestines, Mycobacterial infections, otitis media, lung infections, biofilm and endodontic infections and meningitis. Fungi that have been engineered to be bioluminescent have been used to study infections caused by yeasts (Candida) and by filamentous fungi. Parasitic infections caused by malaria, Leishmania, trypanosomes and toxoplasma have all been monitored by BLI. Viruses such as vaccinia, herpes simplex, hepatitis B and C and influenza, have been studied using BLI. This rapidly growing technology is expected to continue to provide much useful information, while drastically reducing the numbers of animals needed in experimental studies.
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Affiliation(s)
- Pinar Avci
- a Wellman Center for Photomedicine, Massachusetts General Hospital , Boston , MA , USA.,b Department of Dermatology , Harvard Medical School , Boston , MA , USA
| | - Mahdi Karimi
- a Wellman Center for Photomedicine, Massachusetts General Hospital , Boston , MA , USA.,c Department of Medical Nanotechnology , School of Advanced Technologies in Medicine, Iran University of Medical Sciences , Tehran , Iran.,d Cellular and Molecular Research Center, Iran University of Medical Sciences , Tehran , Iran
| | - Magesh Sadasivam
- a Wellman Center for Photomedicine, Massachusetts General Hospital , Boston , MA , USA.,e Amity Institute of Nanotechnology, Amity University Uttar Pradesh , Noida , India
| | - Wanessa C Antunes-Melo
- a Wellman Center for Photomedicine, Massachusetts General Hospital , Boston , MA , USA.,f University of Sao Paulo , Sao Carlos-SP , Brazil
| | - Elisa Carrasco
- a Wellman Center for Photomedicine, Massachusetts General Hospital , Boston , MA , USA.,g Department of Biosciences , Durham University , Durham , United Kingdom
| | - Michael R Hamblin
- a Wellman Center for Photomedicine, Massachusetts General Hospital , Boston , MA , USA.,b Department of Dermatology , Harvard Medical School , Boston , MA , USA.,h Harvard-MIT Division of Health Sciences and Technology , Cambridge , MA , USA
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12
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Reduced PU.1 expression underlies aberrant neutrophil maturation and function in β-thalassemia mice and patients. Blood 2017; 129:3087-3099. [PMID: 28325862 DOI: 10.1182/blood-2016-07-730135] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Accepted: 02/28/2017] [Indexed: 01/13/2023] Open
Abstract
β-Thalassemia is associated with several abnormalities of the innate immune system. Neutrophils in particular are defective, predisposing patients to life-threatening bacterial infections. The molecular and cellular mechanisms involved in impaired neutrophil function remain incompletely defined. We used the Hbbth3/+ β-thalassemia mouse and hemoglobin E (HbE)/β-thalassemia patients to investigate dysregulated neutrophil activity. Mature neutrophils from Hbbth3/+ mice displayed a significant reduction in chemotaxis, opsonophagocytosis, and production of reactive oxygen species, closely mimicking the defective immune functions observed in β-thalassemia patients. In Hbbth3/+ mice, the expression of neutrophil CXCR2, CD11b, and reduced NAD phosphate oxidase components (p22phox, p67phox, and gp91phox) were significantly reduced. Morphological analysis of Hbbth3/+ neutrophils showed that a large percentage of mature phenotype neutrophils (Ly6GhiLy6Clow) appeared as band form cells, and a striking expansion of immature (Ly6GlowLy6Clow) hyposegmented neutrophils, consisting mainly of myelocytes and metamyelocytes, was noted. Intriguingly, expression of an essential mediator of neutrophil terminal differentiation, the ets transcription factor PU.1, was significantly decreased in Hbbth3/+ neutrophils. In addition, in vivo infection with Streptococcus pneumoniae failed to induce PU.1 expression or upregulate neutrophil effector functions in Hbbth3/+ mice. Similar changes to neutrophil morphology and PU.1 expression were observed in splenectomized and nonsplenectomized HbE/β-thalassemia patients. This study provides a mechanistic insight into defective neutrophil maturation in β-thalassemia patients, which contributes to deficiencies in neutrophil effector functions.
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13
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Short KR, von Köckritz-Blickwede M, Langereis JD, Chew KY, Job ER, Armitage CW, Hatcher B, Fujihashi K, Reading PC, Hermans PW, Wijburg OL, Diavatopoulos DA. Antibodies mediate formation of neutrophil extracellular traps in the middle ear and facilitate secondary pneumococcal otitis media. Infect Immun 2014; 82:364-70. [PMID: 24191297 PMCID: PMC3911859 DOI: 10.1128/iai.01104-13] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2013] [Accepted: 10/14/2013] [Indexed: 12/16/2022] Open
Abstract
Otitis media (OM) (a middle ear infection) is a common childhood illness that can leave some children with permanent hearing loss. OM can arise following infection with a variety of different pathogens, including a coinfection with influenza A virus (IAV) and Streptococcus pneumoniae (the pneumococcus). We and others have demonstrated that coinfection with IAV facilitates the replication of pneumococci in the middle ear. Specifically, we used a mouse model of OM to show that IAV facilitates the outgrowth of S. pneumoniae in the middle ear by inducing middle ear inflammation. Here, we seek to understand how the host inflammatory response facilitates bacterial outgrowth in the middle ear. Using B cell-deficient infant mice, we show that antibodies play a crucial role in facilitating pneumococcal replication. We subsequently show that this is due to antibody-dependent neutrophil extracellular trap (NET) formation in the middle ear, which, instead of clearing the infection, allows the bacteria to replicate. We further demonstrate the importance of these NETs as a potential therapeutic target through the transtympanic administration of a DNase, which effectively reduces the bacterial load in the middle ear. Taken together, these data provide novel insight into how pneumococci are able to replicate in the middle ear cavity and induce disease.
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Affiliation(s)
- Kirsty R. Short
- Department of Microbiology and Immunology, The University of Melbourne, Melbourne, Australia
| | | | - Jeroen D. Langereis
- Laboratory of Pediatric Infectious Diseases, Department of Pediatrics, Radboud University Medical Centre, Nijmegen, The Netherlands
| | - Keng Yih Chew
- Department of Zoology, The University of Melbourne, Melbourne, Australia
| | - Emma R. Job
- Department of Microbiology and Immunology, The University of Melbourne, Melbourne, Australia
| | - Charles W. Armitage
- Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Queensland, Australia
| | - Brandon Hatcher
- Department of Pediatric Dentistry and Microbiology, The University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Kohtaro Fujihashi
- Department of Pediatric Dentistry and Microbiology, The University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Patrick C. Reading
- Department of Microbiology and Immunology, The University of Melbourne, Melbourne, Australia
- WHO Collaborating Centre for Reference and Research on Influenza, Parkville, Victoria, Australia
| | - Peter W. Hermans
- Laboratory of Pediatric Infectious Diseases, Department of Pediatrics, Radboud University Medical Centre, Nijmegen, The Netherlands
| | - Odilia L. Wijburg
- Department of Microbiology and Immunology, The University of Melbourne, Melbourne, Australia
| | - Dimitri A. Diavatopoulos
- Laboratory of Pediatric Infectious Diseases, Department of Pediatrics, Radboud University Medical Centre, Nijmegen, The Netherlands
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14
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Abstract
Influenza A virus (IAV) predisposes individuals to secondary infections with the bacterium Streptococcus pneumoniae (the pneumococcus). Infections may manifest as pneumonia, sepsis, meningitis, or otitis media (OM). It remains controversial as to whether secondary pneumococcal disease is due to the induction of an aberrant immune response or IAV-induced immunosuppression. Moreover, as the majority of studies have been performed in the context of pneumococcal pneumonia, it remains unclear how far these findings can be extrapolated to other pneumococcal disease phenotypes such as OM. Here, we used an infant mouse model, human middle ear epithelial cells, and a series of reverse-engineered influenza viruses to investigate how IAV promotes bacterial OM. Our data suggest that the influenza virus HA facilitates disease by inducing a proinflammatory response in the middle ear cavity in a replication-dependent manner. Importantly, our findings suggest that it is the inflammatory response to IAV infection that mediates pneumococcal replication. This study thus provides the first evidence that inflammation drives pneumococcal replication in the middle ear cavity, which may have important implications for the treatment of pneumococcal OM.
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15
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Increased nasopharyngeal bacterial titers and local inflammation facilitate transmission of Streptococcus pneumoniae. mBio 2012; 3:mBio.00255-12. [PMID: 23015738 PMCID: PMC3518912 DOI: 10.1128/mbio.00255-12] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
The transmission of the bacterium Streptococcus pneumoniae (the pneumococcus) marks the first step toward disease development. To date, our ability to prevent pneumococcal transmission has been limited by our lack of understanding regarding the factors which influence the spread of this pathogen. We have previously developed an infant mouse model of pneumococcal transmission which was strictly dependent on influenza A virus (IAV) coinfection of both the experimentally colonized “index mice” and the naive cohoused “contact mice.” Here, we sought to use this model to further elucidate the factors which facilitate S. pneumoniae transmission. In the present report, we demonstrate that increasing the nasopharyngeal load of S. pneumoniae in the colonized index mice (via the depletion of neutrophils) and inducing a proinflammatory response in the naive cohoused contact mice (as demonstrated by cytokine production) facilitates S. pneumoniae transmission. Thus, these data provide the first insights into the factors that help mediate the spread of S. pneumoniae throughout the community. Streptococcus pneumoniae (the pneumococcus) is a major cause of worldwide morbidity and mortality and is a leading cause of death among children under the age of five years. Transmission of S. pneumoniae marks the first step toward disease development. Therefore, understanding the factors that influence the spread of pneumococci throughout the community plays an essential role in preventing pneumococcal disease. We previously developed the first reproducible infant mouse model for pneumococcal transmission and showed that coinfection with influenza virus facilitates the spread of S. pneumoniae. Here, we show that increasing the bacterial load in the nasal cavity of colonized individuals as well as inducing an inflammatory response in naive “contact cases” facilitates the spread of pneumococci. Therefore, this study helps to identify the factors which must be inhibited in order to successfully prevent pneumococcal disease.
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16
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Modified lipooligosaccharide structure protects nontypeable Haemophilus influenzae from IgM-mediated complement killing in experimental otitis media. mBio 2012; 3:e00079-12. [PMID: 22761391 PMCID: PMC3398534 DOI: 10.1128/mbio.00079-12] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Nontypeable Haemophilus influenzae (NTHi) is a Gram-negative, human-restricted pathogen. Although this bacterium typically colonizes the nasopharynx in the absence of clinical symptoms, it is also one of the major pathogens causing otitis media (OM) in children. Complement represents an important aspect of the host defense against NTHi. In general, NTHi is efficiently killed by complement-mediated killing; however, various resistance mechanisms have also evolved. We measured the complement resistance of NTHi isolates isolated from the nasopharynx and the middle ear fluids of OM patients. Furthermore, we determined the molecular mechanism of NTHi complement resistance. Complement resistance was strongly increased in isolates from the middle ear, which correlated with decreased binding of IgM. We identified a crucial role for the R2866_0112 gene in complement resistance. Deletion of this gene altered the lipooligosaccharide (LOS) composition of the bacterium, which increased IgM binding and complement-mediated lysis. In a novel mouse model of coinfection with influenza virus, we demonstrate decreased virulence for the R2866_0112 deletion mutant. These findings identify a mechanism by which NTHi modifies its LOS structure to prevent recognition by IgM and activation of complement. Importantly, this mechanism plays a crucial role in the ability of NTHi to cause OM. Nontypeable Haemophilus influenzae (NTHi) colonizes the nasopharynx of especially young children without any obvious symptoms. However, NTHi is also a major pathogen in otitis media (OM), one of the most common childhood infections. Although this pathogen is often associated with OM, the mechanism by which this bacterium is able to cause OM is largely unknown. Our study addresses a key biological question that is highly relevant for child health: what is the molecular mechanism that enables NTHi to cause OM? We show that isolates collected from the middle ear fluid exhibit increased complement resistance and that the lipooligosaccharide (LOS) structure determines IgM binding and complement activation. Modification of the LOS structure decreased NTHi virulence in a novel NTHi-influenza A virus coinfection OM mouse model. Our findings may also have important implications for other Gram-negative pathogens harboring LOS, such as Neisseria meningitidis, Moraxella catarrhalis, and Bordetella pertussis.
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