Cellular effectors mediating Th17-dependent clearance of pneumococcal colonization in mice
Zhe Zhang, … , Thomas B. Clarke, Jeffrey N. Weiser
Zhe Zhang, … , Thomas B. Clarke, Jeffrey N. Weiser
Published June 8, 2009
Citation Information: J Clin Invest. 2009;119(7):1899-1909. https://doi.org/10.1172/JCI36731.
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Research Article Infectious disease

Cellular effectors mediating Th17-dependent clearance of pneumococcal colonization in mice

Abstract

Microbial colonization of mucosal surfaces may be an initial event in the progression to disease, and it is often a transient process. For the extracellular pathogen Streptococcus pneumoniae studied in a mouse model, nasopharyngeal carriage is eliminated over a period of weeks and requires cellular rather than humoral immunity. Here, we demonstrate that primary infection led to TLR2-dependent recruitment of monocyte/macrophages into the upper airway lumen, where they engulfed pneumococci. Pharmacologic depletion of luminal monocyte/macrophages by intranasal instillation of liposomal clodronate diminished pneumococcal clearance. Efficient clearance of colonization required TLR2 signaling to generate a population of pneumococcal-specific IL-17–expressing CD4+ T cells. Depletion of either IL-17A or CD4+ T cells was sufficient to block the recruitment of monocyte/macrophages that allowed for effective late pneumococcal clearance. In contrast with naive mice, previously colonized mice showed enhanced early clearance that correlated with a more robust influx of luminal neutrophils. As for primary colonization, these cellular responses required Th17 immunity. Our findings demonstrate that monocyte/macrophages and neutrophils recruited to the mucosal surface are key effectors in clearing primary and secondary bacterial colonization, respectively.

Authors

Zhe Zhang, Thomas B. Clarke, Jeffrey N. Weiser

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Figure 1

Macrophages are recruited to nasopharynx in association with clearance of pneumococcal isolate P1121, and responses are attenuated in the absence of TLR2 signaling.

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Macrophages are recruited to nasopharynx in association with clearance o...
Upper respiratory tract lavages were analyzed at the time indicated following i.n. inoculation of C57BL/6 WT mice (filled symbols) and congenic Tlr2–/– mice (open symbols) for quantitative culture to determine the time course of P1121 colonization (A). Cells in cytospin preparations of colonized mice were used to determine the time course of (B) neutrophil and (C) mononuclear cell recruitment. Animals at day 0 were mock colonized. n = 5 to 20 mice per group per time point. Values represent means ± SEM. (D) MOMA-2–positive mononuclear cells are recruited to the lumen of the nasopharynx. MOMA-2 mAb staining (red) of mononuclear cells in the cytospin preparations of nasal lavages from mice 7 days after P1121 challenge with or without Nomarski optics. Isotype-matched antibody was used as a negative control (Neg.). Nuclei were stained with DAPI (blue). Lower right panel shows a mononuclear cell (arrow) and olfactory epithelium lining the nasal cavity in a tissue section stained with H&E. Original magnification, ×1000 (upper panels); ×400 (lower left panel); ×200 (lower right panel). (E) Quantification by flow cytometry showing a representative experiment comparing the number of infiltrating macrophages in pooled nasal lavages from 5 WT or Tlr2–/– mice at day 21 of P1121 colonization. Naive mice were mock inoculated with PBS. The numbers in the upper left corners indicate the number of Ly6C+ and CD45+–double-positive cells in the sample. **P < 0.01; ***P < 0.001.