Chlamydia pneumoniae hides inside apoptotic neutrophils to silently infect and propagate in macrophages

• Published in: PloS one Vol. 4; no. 6; p. e6020
• Main Authors: Rupp, Jan, Pfleiderer, Lisa, Jugert, Christiane, Moeller, Sonja, Klinger, Matthias, Dalhoff, Klaus, Solbach, Werner, Stenger, Steffen, Laskay, Tamas, van Zandbergen, Ger
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 23.06.2009; Public Library of Science (PLoS)
• Subjects: Adults; Alveoli; Annexins; Antigens; Apoptosis; Bacteria; Cell Line - microbiology; Cell Separation; Children; Chlamydia; Chlamydia infections; Chlamydia pneumoniae; Chlamydophila pneumoniae - pathogenicity; Chlamydophila pneumoniae - physiology; Complications; Cytokines; Cytokines - biosynthesis; Disease transmission; Flow Cytometry; Genetic recombination; Granulocytes; Granulocytes - microbiology; Health aspects; Humans; Hygiene; Infections; Infectious Diseases; Leishmania; Leukocytes (granulocytic); Leukocytes (neutrophilic); Lungs; Macrophages; Macrophages - metabolism; Macrophages, Alveolar - metabolism; Macrophages, Alveolar - microbiology; Macrophages, Alveolar - pathology; Masking; Metabolism; Microbiology/Cellular Microbiology and Pathogenesis; Microbiology/Immunity to Infections; Models, Biological; Neutrophils; Neutrophils - cytology; Neutrophils - metabolism; Pathogens; Phagocytes; Pneumonia; Respiratory Medicine/Respiratory Infections; Respiratory tract; Respiratory tract diseases; Reverse Transcriptase Polymerase Chain Reaction; RNA polymerase; Sexually transmitted diseases; Transforming growth factors; Tumor necrosis factor-α; Germany
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0006020

Intracellular pathogens have developed elaborate strategies for silent infection of preferred host cells. Chlamydia pneumoniae is a common pathogen in acute infections of the respiratory tract (e.g. pneumonia) and associated with chronic lung sequelae in adults and children. Within the lung, alveolar macrophages and polymorph nuclear neutrophils (PMN) are the first line of defense against bacteria, but also preferred host phagocytes of chlamydiae. We could show that C. pneumoniae easily infect and hide inside neutrophil granulocytes until these cells become apoptotic and are subsequently taken up by macrophages. C. pneumoniae infection of macrophages via apoptotic PMN results in enhanced replicative activity of chlamydiae when compared to direct infection of macrophages, which results in persistence of the pathogen. Inhibition of the apoptotic recognition of C. pneumoniae infected PMN using PS- masking Annexin A5 significantly lowered the transmission of chlamydial infection to macrophages. Transfer of apoptotic C. pneumoniae infected PMN to macrophages resulted in an increased TGF-ss production, whereas direct infection of macrophages with chlamydiae was characterized by an enhanced TNF-alpha response. Taken together, our data suggest that C. pneumoniae uses neutrophil granulocytes to be silently taken up by long-lived macrophages, which allows for efficient propagation and immune protection within the human host.