Related Experiment Video
Updated: Jan 5, 2026
Characterization of Inflammatory Responses During Intranasal Colonization with Streptococcus pneumoniae
Published on: January 17, 2014
Persistent colonization of non-lymphoid tissue-resident macrophages by Stenotrophomonas maltophilia
Ichiro Takahashi1,2, Koji Hosomi2, Takahiro Nagatake2
1Department of Mucosal Immunology, Graduate School of Biomedical and Health Science, Hiroshima University, Hiroshima, Japan.
Abstract:
Accumulating evidence has revealed that lymphoid tissue-resident commensal bacteria (e.g. Alcaligenes spp.) survive within dendritic cells. We extended our previous study by investigating microbes that persistently colonize colonic macrophages. 16S rRNA-based metagenome analysis using DNA purified from murine colonic macrophages revealed the presence of Stenotrophomonas maltophilia. The in situ intracellular colonization by S. maltophilia was recapitulated in vitro by using bone marrow-derived macrophages (BMDMs). Co-culture of BMDMs with clinically isolated S. maltophilia led to increased mitochondrial respiration and robust IL-10 production. We further identified a 25-kDa protein encoded by the gene assigned as smlt2713 (recently renamed as SMLT_RS12935) and secreted by S. maltophilia as the factor responsible for enhanced IL-10 production by BMDMs. IL-10 production is critical for maintenance of the symbiotic condition, because intracellular colonization by S. maltophilia was impaired in IL-10-deficient BMDMs, and smlt2713-deficient S. maltophilia failed to persistently colonize IL-10-competent BMDMs. These findings indicate a novel commensal network between colonic macrophages and S. maltophilia that is mediated by IL-10 and smlt2713.
Insights
Commensal Stenotrophomonas maltophilia colonizes colonic macrophages, enhancing IL-10 production via a secreted protein (smlt2713). This interaction is crucial for maintaining symbiosis between the bacteria and host immune cells.
Area of Science:
- Microbiology
- Immunology
- Gastroenterology
Background:
- Commensal bacteria reside in lymphoid tissues and can colonize immune cells like dendritic cells.
- Previous studies demonstrated bacterial survival within dendritic cells.
Purpose of the Study:
- To investigate microbes that persistently colonize colonic macrophages.
- To elucidate the mechanism of interaction between Stenotrophomonas maltophilia and colonic macrophages.
Main Methods:
- 16S rRNA-based metagenome analysis of murine colonic macrophages.
- In vitro colonization assays using bone marrow-derived macrophages (BMDMs).
- Identification of a secreted bacterial protein (smlt2713) responsible for immune modulation.
Main Results:
- Stenotrophomonas maltophilia was identified as a persistent colonizer of murine colonic macrophages.
- S. maltophilia enhanced mitochondrial respiration and interleukin-10 (IL-10) production in BMDMs.
- A secreted S. maltophilia protein, smlt2713, was identified as the key factor driving IL-10 production and symbiotic colonization.
Conclusions:
- A novel commensal network exists between colonic macrophages and S. maltophilia.
- This symbiosis is mediated by bacterial IL-10 production, induced by the S. maltophilia protein smlt2713.
- IL-10 is essential for the persistent intracellular colonization of macrophages by S. maltophilia.
