Macrophages Subvert Adaptive Immunity to Urinary Tract Infection

• Published in: PLoS pathogens Vol. 11; no. 7; p. e1005044
• Main Authors: Mora-Bau, Gabriela, Platt, Andrew M, van Rooijen, Nico, Randolph, Gwendalyn J, Albert, Matthew L, Ingersoll, Molly A
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 01-07-2015; Public Library of Science (PLoS)
• Subjects: Adaptive Immunity - immunology; Animals; Antibiotics; Antigens; Bacteria; Bacterial infections; Bladder; Cells, Cultured; Chemokines; Cytokines; Dendritic cells; E coli; Escherichia coli Infections - immunology; Escherichia coli Infections/immunology Female; Experiments; Female; Funding; Immunity, Innate - immunology; Immunology; Infections; Life Sciences; Macrophages - cytology; Macrophages - immunology; Mice, Inbred C57BL; Studies; T cell receptors; Urinary tract diseases; Urinary Tract Infections - immunology; Urinary Tract Infections - microbiology; Urogenital system
• ISSN: 1553-7374; 1553-7366; 1553-7374
• DOI: 10.1371/journal.ppat.1005044

Urinary tract infection (UTI) is one of the most common bacterial infections with frequent recurrence being a major medical challenge. Development of effective therapies has been impeded by the lack of knowledge of events leading to adaptive immunity. Here, we establish conclusive evidence that an adaptive immune response is generated during UTI, yet this response does not establish sterilizing immunity. To investigate the underlying deficiency, we delineated the naïve bladder immune cell compartment, identifying resident macrophages as the most populous immune cell. To evaluate their impact on the establishment of adaptive immune responses following infection, we measured bacterial clearance in mice depleted of either circulating monocytes, which give rise to macrophages, or bladder resident macrophages. Surprisingly, mice depleted of resident macrophages, prior to primary infection, exhibited a nearly 2-log reduction in bacterial burden following secondary challenge compared to untreated animals. This increased bacterial clearance, in the context of a challenge infection, was dependent on lymphocytes. Macrophages were the predominant antigen presenting cell to acquire bacteria post-infection and in their absence, bacterial uptake by dendritic cells was increased almost 2-fold. These data suggest that bacterial uptake by tissue macrophages impedes development of adaptive immune responses during UTI, revealing a novel target for enhancing host responses to bacterial infection of the bladder.