Related Experiment Video
Updated: May 12, 2026
Murine Model of Epicutaneously-Induced Immunomodulation
Published on: June 24, 2025
NTHi induction of Cxcl2 and middle ear mucosal metaplasia in mice
Diego Preciado1, Katelyn Burgett, Svetlana Ghimbovschi
1Center for Genetic Medicine Research, Children's National Medical Center, Washington, DC, U.S.A; Division of Pediatric Otolaryngology-Head and Neck Surgery, Children's National Medical Center, Washington, DC, U.S.A.
Objectives/Hypothesis:
Chronic otitis media (COM) develops after sustained inflammation and is characterized by secretory middle ear epithelial metaplasia and effusion, most frequently mucoid. Nontypeable Haemophilus influenzae (NTHi), the most common acute otitis media (OM) pathogen, is known to activate inflammation and mucin expression in vitro and in animal models of OM. The goals of this study were to examine histopathological and expression profiling epithelial effects of NTHi challenge in murine middle ears.
Study Design:
In vitro and in vivo murine model of OM.
Methods:
Weekly transtympanic inoculation of Balb/c mice with 300 μg/ml of NTHi lysates versus saline was performed. Histopathologic analysis was carried out at 4 weeks. Expression microarray analysis was performed at 1 and 7 days. Microarray findings were validated in independent animal samples and in a cultured murine middle ear epithelial cell (mMEEC) line.
Results:
Histopathologic analyses revealed middle ear mucosal thickening after NTHi exposure. Microarray analyses of inflammatory response genes which changed significantly demonstrated that the chemokine Cxcl2 had the largest fold-change, with significantly increased expression at 1 and 7 days after NTHi injection compared to either saline or no-injection (P <0.01). Validation by real-time qPCR revealed similar significantly increased relative mRNA levels for Cxcl2. NTHi lysates were also found to significantly upregulate the transcription of Cxcl2 in mMEEC in a time- and dose-dependent manner (P <0.05).
Conclusions:
Middle ear NTHi challenge in mice leads to chronic epithelial mucosal metaplasia and overexpression of inflammatory mediators, most notably Cxcl2. This finding is parallel to NTHi-mediated pulmonary mucosal metaplasia where Cxcl2 has been identified as an important inflammatory mediator.
Insights
Nontypeable Haemophilus influenzae (NTHi) infection in mice causes chronic middle ear inflammation and metaplasia. This study found NTHi significantly increases the inflammatory mediator Cxcl2 in the middle ear epithelium.
Area of Science:
- Otolaryngology
- Microbiology
- Immunology
Background:
- Chronic otitis media (COM) involves middle ear epithelial metaplasia and effusion.
- Nontypeable Haemophilus influenzae (NTHi) is a common pathogen linked to otitis media and inflammation.
Purpose of the Study:
- To investigate the epithelial effects of NTHi challenge in a murine middle ear model.
- To analyze histopathological changes and gene expression profiles.
Main Methods:
- A murine model of otitis media using weekly NTHi lysate inoculations.
- Histopathologic analysis at 4 weeks and expression microarray analysis at 1 and 7 days.
- Validation of gene expression using real-time qPCR and cultured middle ear epithelial cells.
Main Results:
- NTHi exposure led to middle ear mucosal thickening.
- The chemokine Cxcl2 showed the largest significant fold-change increase in expression post-NTHi challenge.
- NTHi upregulated Cxcl2 transcription in middle ear epithelial cells in a time- and dose-dependent manner.
Conclusions:
- NTHi challenge induces chronic epithelial metaplasia and overexpression of inflammatory mediators, particularly Cxcl2, in the middle ear.
- This finding aligns with Cxcl2's role in NTHi-mediated pulmonary inflammation.
