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Bhalla M, Herring S, Lenhard A, Wheeler JR, Aswad F, Klumpp K, Rebo J, Wang Y, Wilhelmsen K, Fortney K, Bou Ghanem EN. The prostaglandin D2 antagonist asapiprant ameliorates clinical severity in young hosts infected with invasive Streptococcus pneumoniae. Infect Immun 2024; 92:e0052223. [PMID: 38629842 PMCID: PMC11075459 DOI: 10.1128/iai.00522-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2023] [Accepted: 03/29/2024] [Indexed: 05/03/2024] Open
Abstract
Streptococcus pneumoniae (pneumococcus) remains a serious cause of pulmonary and systemic infections globally, and host-directed therapies are lacking. The aim of this study was to test the therapeutic efficacy of asapiprant, an inhibitor of prostaglandin D2 signaling, against pneumococcal infection. Treatment of young mice with asapiprant after pulmonary infection with invasive pneumococci significantly reduced systemic spread, disease severity, and host death. Protection was specific against bacterial dissemination from the lung to the blood but had no effect on pulmonary bacterial burden. Asapiprant-treated mice had enhanced antimicrobial activity in circulating neutrophils, elevated levels of reactive oxygen species (ROS) in lung macrophages/monocytes, and improved pulmonary barrier integrity indicated by significantly reduced diffusion of fluorescein isothiocyanate (FITC)-dextran from lungs into the circulation. These findings suggest that asapiprant protects the host against pneumococcal dissemination by enhancing the antimicrobial activity of immune cells and maintaining epithelial/endothelial barrier integrity in the lungs.
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Affiliation(s)
- Manmeet Bhalla
- Department of Microbiology and Immunology, School of Medicine, University at Buffalo, Buffalo, New York, USA
| | - Sydney Herring
- Department of Microbiology and Immunology, School of Medicine, University at Buffalo, Buffalo, New York, USA
| | - Alexsandra Lenhard
- Department of Microbiology and Immunology, School of Medicine, University at Buffalo, Buffalo, New York, USA
| | - Joshua R. Wheeler
- Department of Pathology, Stanford University, Stanford, California, USA
| | - Fred Aswad
- BIOAGE Labs Inc., Richmond, California, USA
| | | | | | - Yan Wang
- BIOAGE Labs Inc., Richmond, California, USA
| | | | | | - Elsa N. Bou Ghanem
- Department of Microbiology and Immunology, School of Medicine, University at Buffalo, Buffalo, New York, USA
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Mitochondrial ROS production by neutrophils is required for host antimicrobial function against Streptococcus pneumoniae and is controlled by A2B adenosine receptor signaling. PLoS Pathog 2022; 18:e1010700. [DOI: 10.1371/journal.ppat.1010700] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2022] [Revised: 11/28/2022] [Accepted: 11/07/2022] [Indexed: 11/15/2022] Open
Abstract
Polymorphonuclear cells (PMNs) control Streptococcus pneumoniae (pneumococcus) infection through various antimicrobial activities. We previously found that reactive oxygen species (ROS) were required for optimal antibacterial function, however, the NADPH oxidase is known to be dispensable for the ability of PMNs to kill pneumococci. In this study, we explored the role of ROS produced by the mitochondria in PMN antimicrobial defense against pneumococci. We found that the mitochondria are an important source of overall intracellular ROS produced by murine PMNs in response to infection. We investigated the host and bacterial factors involved and found that mitochondrial ROS (MitROS) are produced independent of bacterial capsule or pneumolysin but presence of live bacteria that are in direct contact with PMNs enhanced the response. We further found that MyD88-/- PMNs produced less MitROS in response to pneumococcal infection suggesting that released bacterial products acting as TLR ligands are sufficient for inducing MitROS production in PMNs. To test the role of MitROS in PMN function, we used an opsonophagocytic killing assay and found that MitROS were required for the ability of PMNs to kill pneumococci. We then investigated the role of MitROS in host resistance and found that MitROS are produced by PMNs in response to pneumococcal infection. Importantly, treatment of mice with a MitROS scavenger prior to systemic challenge resulted in reduced survival of infected hosts. In exploring host pathways that control MitROS, we focused on extracellular adenosine, which is known to control PMN anti-pneumococcal activity, and found that signaling through the A2B adenosine receptor inhibits MitROS production by PMNs. A2BR-/- mice produced more MitROS and were significantly more resistant to infection. Finally, we verified the clinical relevance of our findings using human PMNs. In summary, we identified a novel pathway that controls MitROS production by PMNs, shaping host resistance against S. pneumoniae.
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Bhalla M, Nayerhoda R, Tchalla EYI, Abamonte A, Park D, Simmons SR, Pfeifer BA, Bou Ghanem EN. Liposomal Encapsulation of Polysaccharides (LEPS) as an Effective Vaccine Strategy to Protect Aged Hosts Against S. pneumoniae Infection. FRONTIERS IN AGING 2021; 2. [PMID: 35291600 PMCID: PMC8920316 DOI: 10.3389/fragi.2021.798868] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Despite the availability of licensed vaccines, pneumococcal disease caused by the bacteria Streptococcus pneumoniae (pneumococcus), remains a serious infectious disease threat globally. Disease manifestations include pneumonia, bacteremia, and meningitis, resulting in over a million deaths annually. Pneumococcal disease disproportionally impacts older adults aged ≥65 years. Interventions are complicated through a combination of complex disease progression and 100 different bacterial capsular polysaccharide serotypes. This has made it challenging to develop a broad vaccine against S. pneumoniae, with current options utilizing capsular polysaccharides as the primary antigenic content. However, current vaccines are substantially less effective in protecting the elderly. We previously developed a Liposomal Encapsulation of Polysaccharides (LEPS) vaccine platform, designed around limitations of current pneumococcal vaccines, that allowed the noncovalent coupling of polysaccharide and protein antigen content and protected young hosts against pneumococcal infection in murine models. In this study, we modified the formulation to make it more economical and tested the novel LEPS vaccine in aged hosts. We found that in young mice (2-3 months), LEPS elicited comparable responses to the pneumococcal conjugate vaccine Prevnar-13. Further, LEPS immunization of old mice (18-22 months) induced comparable antibody levels and improved antibody function compared to Prevnar-13. Importantly, LEPS protected old mice against both invasive and lung localized pneumococcal infections. In summary, LEPS is an alternative and effective vaccine strategy that protects aged hosts against different manifestations of pneumococcal disease.
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Affiliation(s)
- Manmeet Bhalla
- Department of Microbiology and Immunology, University at Buffalo, The State University of New York, Buffalo, NY, United States
| | - Roozbeh Nayerhoda
- Department of Biomedical Engineering, University at Buffalo, The State University of New York, Buffalo, NY, United States
| | - Essi Y I Tchalla
- Department of Microbiology and Immunology, University at Buffalo, The State University of New York, Buffalo, NY, United States
| | - Alexsandra Abamonte
- Department of Microbiology and Immunology, University at Buffalo, The State University of New York, Buffalo, NY, United States
| | - Dongwon Park
- Department of Chemical and Biological Engineering, University at Buffalo, The State University of New York, Buffalo, NY, United States
| | - Shaunna R Simmons
- Department of Microbiology and Immunology, University at Buffalo, The State University of New York, Buffalo, NY, United States
| | - Blaine A Pfeifer
- Department of Chemical and Biological Engineering, University at Buffalo, The State University of New York, Buffalo, NY, United States.,Gene and Tissue Engineering Center, University at Buffalo, The State University of New York, Buffalo, NY, United States
| | - Elsa N Bou Ghanem
- Department of Microbiology and Immunology, University at Buffalo, The State University of New York, Buffalo, NY, United States
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