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Trousil J, Frgelecová L, Kubíčková P, Řeháková K, Drašar V, Matějková J, Štěpánek P, Pavliš O. Acute Pneumonia Caused by Clinically Isolated Legionella pneumophila Sg 1, ST 62: Host Responses and Pathologies in Mice. Microorganisms 2022; 10:microorganisms10010179. [PMID: 35056629 PMCID: PMC8781576 DOI: 10.3390/microorganisms10010179] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Revised: 01/11/2022] [Accepted: 01/12/2022] [Indexed: 11/16/2022] Open
Abstract
Legionnaires’ disease is a severe form of lung infection caused by bacteria belonging to the genus Legionella. The disease severity depends on both host immunity and L. pneumophila virulence. The objective of this study was to describe the pathological spectrum of acute pneumonia caused by a virulent clinical isolate of L. pneumophila serogroup 1, sequence type 62. In A/JOlaHsd mice, we compared two infectious doses, namely, 104 and 106 CFU, and their impact on the mouse status, bacterial clearance, lung pathology, and blood count parameters was studied. Acute pneumonia resembling Legionnaires’ disease has been described in detail.
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Affiliation(s)
- Jiří Trousil
- Institute of Macromolecular Chemistry, Czech Academy of Sciences, Heyrovského nám. 2, 162 00 Prague, Czech Republic;
- Correspondence: or
| | - Lucia Frgelecová
- Department of Pathological Morphology and Parasitology, Faculty of Veterinary Medicine, University of Veterinary Sciences Brno, Palackého tř. 1946/1, 612 42 Brno, Czech Republic;
| | - Pavla Kubíčková
- Military Health Institute, Military Medical Agency, Tychonova 1, 160 00 Prague, Czech Republic; (P.K.); (O.P.)
| | - Kristína Řeháková
- Small Animal Clinical Laboratory, Faculty of Veterinary Medicine, University of Veterinary Sciences Brno, Palackého tř. 1946/1, 612 42 Brno, Czech Republic;
| | - Vladimír Drašar
- National Legionella Reference Laboratory, Public Health Institute Ostrava, Masarykovo náměstí 16, 682 01 Vyškov, Czech Republic;
| | - Jana Matějková
- Department of Medical Microbiology, Second Faculty of Medicine, Charles University, Motol University Hospital, V Úvalu 84, 150 06 Prague, Czech Republic;
| | - Petr Štěpánek
- Institute of Macromolecular Chemistry, Czech Academy of Sciences, Heyrovského nám. 2, 162 00 Prague, Czech Republic;
| | - Oto Pavliš
- Military Health Institute, Military Medical Agency, Tychonova 1, 160 00 Prague, Czech Republic; (P.K.); (O.P.)
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Abstract
Legionella pneumophila is a gram-negative bacterium that infects many species of unicellular protozoa in freshwater environments. The human infection is accidental, and the bacteria may not have evolved strategies to bypass innate immune signaling in mammalian macrophages. Thus, L. pneumophila triggers many innate immune pathways including inflammasome activation. The inflammasomes are multimolecular platforms assembled in the host cell cytoplasm and lead to activation of inflammatory caspases. Inflammasome activation leads to secretion of inflammatory cytokines, such as IL-1β and IL-18, and an inflammatory form of cell death called pyroptosis, which initiates with the induction of a pore in the macrophage membranes. In this chapter we provide detailed protocols to evaluate Legionella-induced inflammasome activation in macrophages, including real-time pore formation assay, western blotting to detect activation of inflammatory caspases (cleavage and pulldown), and the measurement of inflammatory cytokines.
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Affiliation(s)
- Danielle P A Mascarenhas
- Department of Cell Biology, School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Dario S Zamboni
- Department of Cell Biology, School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, SP, Brazil.
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Characterization of aerosols containing Legionella generated upon nebulization. Sci Rep 2016; 6:33998. [PMID: 27671446 PMCID: PMC5037422 DOI: 10.1038/srep33998] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2016] [Accepted: 09/01/2016] [Indexed: 01/01/2023] Open
Abstract
Legionella pneumophila is, by far, the species most frequently associated with Legionnaires' disease (LD). Human infection occurs almost exclusively by aerosol inhalation which places the bacteria in juxtaposition with alveolar macrophages. LD risk management is based on controlling water quality by applying standardized procedures. However, to gain a better understanding of the real risk of exposure, there is a need (i) to investigate under which conditions Legionella may be aerosolized and (ii) to quantify bacterial deposition into the respiratory tract upon nebulization. In this study, we used an original experimental set-up that enables the generation of aerosol particles containing L. pneumophila under various conditions. Using flow cytometry in combination with qPCR and culture, we determined (i) the size of the aerosols and (ii) the concentration of viable Legionella forms that may reach the thoracic region. We determined that the 0.26-2.5 μm aerosol size range represents 7% of initial bacterial suspension. Among the viable forms, 0.7% of initial viable bacterial suspension may reach the pulmonary alveoli. In conclusion, these deposition profiles can be used to standardize the size of inoculum injected in any type of respiratory tract model to obtain new insights into the dose response for LD.
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