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Updated: Mar 9, 2026
A Non-invasive and Technically Non-intensive Method for Induction and Phenotyping of Experimental Bacterial Pneumonia in Mice
Published on: September 28, 2016
Innate immunity against Legionella pneumophila during pulmonary infections in mice
Bonggoo Park1, Gayoung Park1,2, Jiyoung Kim1
1Global Research Laboratory, Department of Biochemistry and Molecular Biology, Korea University College of Medicine, 126-1 Anam-dong 5-ga, Seongbuk-gu, Seoul, 136-713, Korea.
Abstract:
Legionella pneumophila is an etiological agent of the severe pneumonia known as Legionnaires' disease (LD). This gram-negative bacterium is thought to replicate naturally in various freshwater amoebae, but also replicates in human alveolar macrophages. Inside host cells, legionella induce the production of non-endosomal replicative phagosomes by injecting effector proteins into the cytosol. Innate immune responses are first line defenses against legionella during early phases of infection, and distinguish between legionella and host cells using germline-encoded pattern recognition receptors such as Toll-like receptors , NOD-like receptors, and RIG-I-like receptors, which sense pathogen-associated molecular patterns that are absent in host cells. During pulmonary legionella infections, various inflammatory cells such as macrophages, neutrophils, natural killer (NK) cells, large mononuclear cells, B cells, and CD4+ and CD8+ T cells are recruited into infected lungs, and predominantly occupy interstitial areas to control legionella. During pulmonary legionella infections, the interplay between distinct cytokines and chemokines also modulates innate host responses to clear legionella from the lungs. Recognition by NK cell receptors triggers effector functions including secretion of cytokines and chemokines, and leads to lysis of target cells. Crosstalk between NK cells and dendritic cells, monocytes, and macrophages provides a major first-line defense against legionella infection, whereas activation of T and B cells resolves the infection and mounts legionella-specific memory in the host.
Insights
Legionella pneumophila causes Legionnaires
Area of Science:
- * Immunology
- * Microbiology
- * Infectious Diseases
Background:
- * Legionella pneumophila is the bacterium responsible for Legionnaires' disease, a severe pneumonia.
- * This bacterium replicates within host cells, including macrophages, by manipulating phagosome formation.
- * Innate immune receptors recognize pathogen-associated molecular patterns to initiate defense against Legionella.
Purpose of the Study:
- * To elucidate the complex interplay of immune cells and signaling molecules during Legionella pneumophila infection.
- * To understand the mechanisms of innate and adaptive immune responses against Legionnaires' disease.
Main Methods:
- * Review of current literature on Legionella pneumophila pathogenesis and host immune responses.
- * Analysis of the roles of pattern recognition receptors, cytokines, and chemokines.
- * Examination of the functions of various immune cells, including macrophages, NK cells, T cells, and B cells.
Main Results:
- * Innate immune cells like macrophages and NK cells are crucial for early control of Legionella.
- * Cytokines and chemokines orchestrate the inflammatory response and recruit immune cells to the lungs.
- * Adaptive immune cells, specifically T and B cells, are essential for resolving the infection and establishing long-term immunity.
Conclusions:
- * Effective clearance of Legionella pneumophila relies on a coordinated effort between innate and adaptive immunity.
- * Crosstalk between different immune cell types, such as NK cells and antigen-presenting cells, is vital for initial defense.
- * The development of Legionella-specific memory by T and B cells ensures protection against future infections.
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