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TLR2 promotes macrophage recruitment and Streptococcus pneumoniae clearance during mouse otitis media
Yifei Huang1,2, Zimeng Wang1, Chunfang Jin1
1Key Laboratory of Diagnostic Medicine Designated by the Ministry of Education, Chongqing Medical University, Chongqing, China.
Background:
The natural course of otitis media (OM) in most children is acute and self-limiting; however, approximately 10-20% of children can experience persistent or recurrent OM. Determining the host factors that influence outcome of OM will help us design better therapies. This study focused on the role of Toll-like receptor 2 (TLR2) in a pneumococcal OM mouse model.
Methods:
The middle ears (MEs) of wild-type (WT) and TLR2-/- mice were inoculated with Streptococcus pneumoniae (Spn) serotype 19F via transbullar injection. ME TLR2 expression in WT mice was determined by qRT-PCR and immunofluorescence. ME pathological manifestations, inflammatory response, and pneumococcal clearance between WT and TLR2-/- mice were compared after Spn inoculation.
Results:
TLR2 expression in ME mucosa was markedly enhanced following infection with Spn in WT mice. In contrast to WT mice, TLR2-/- mice exhibited unaffected early ME inflammatory response. During late stage of ME infection, however, the absence of TLR2 can lead to reduced macrophage recruitment, impaired Spn clearance, and prolonged ME inflammation.
Conclusion:
Our results demonstrate that TLR2 signaling is critical for bacterial clearance and timely resolution of inflammation in OM induced by Spn.
Insights
Toll-like receptor 2 (TLR2) plays a crucial role in resolving middle ear infections caused by Streptococcus pneumoniae. Its absence impairs bacterial clearance and prolongs inflammation in otitis media.
Area of Science:
- Immunology
- Microbiology
- Otolaryngology
Background:
- Otitis media (OM) is common in children, with 10-20% experiencing persistent or recurrent infections.
- Host factors influencing OM outcomes are key to developing improved therapies.
- This study investigated the role of Toll-like receptor 2 (TLR2) in a pneumococcal OM mouse model.
Purpose of the Study:
- To determine the role of TLR2 in the host response to Streptococcus pneumoniae (Spn) infection in the middle ear.
- To compare the inflammatory response and bacterial clearance in wild-type (WT) versus TLR2-deficient (TLR2-/-) mice.
Main Methods:
- Wild-type and TLR2-/- mice were infected with Streptococcus pneumoniae serotype 19F via transbullar injection.
- TLR2 expression in the middle ear mucosa was assessed using qRT-PCR and immunofluorescence.
- Pathological changes, inflammatory markers, and bacterial clearance were compared between mouse groups.
Main Results:
- TLR2 expression significantly increased in WT mice after Spn infection.
- TLR2-/- mice showed no difference in early inflammatory response compared to WT mice.
- Absence of TLR2 resulted in reduced macrophage recruitment, impaired Spn clearance, and prolonged middle ear inflammation during the late stage of infection.
Conclusions:
- TLR2 signaling is essential for effective bacterial clearance in pneumococcal otitis media.
- TLR2 is critical for the timely resolution of middle ear inflammation following Spn infection.
