SIRT3 Deficiency Exacerbates Eustachian Tube Dysfunction in Middle-Ear Infections
Middle-ear infections, a common pediatric ailment, are often caused by Gram-negative bacteria. When the eustachian tube, responsible for pressure balance and mucus clearance, fails to function properly during infection, inflammation persists, increasing the risk of chronic otitis media. Lipopolysaccharide (LPS), a bacterial component, is used to model this inflammatory injury. SIRT3, a mitochondrial regulator involved in energy homeostasis and inflammation control, has shown protective roles in various organs. However, its function in the middle ear has been largely unexplored.
A recent study published in the Journal of Otology (November 2025) by researchers from Tongji Medical College and collaborating hospitals reveals that SIRT3 deficiency significantly intensifies eustachian tube dysfunction following LPS-induced acute otitis media in mice. Through detailed imaging, mucus analysis, and pressure-regulation assessments, the team uncovered how the absence of SIRT3 heightens tissue vulnerability, leading to thicker mucus, weakened cilia, and impaired tube opening. These findings offer a mechanistic understanding of how mitochondrial resilience influences the progression and severity of middle-ear infections.
To investigate the role of SIRT3 in inflammatory responses in the ear, researchers compared wild-type and SIRT3-knockout mice after LPS injection into the middle ear. Both groups showed similar eustachian tube structure under baseline conditions. However, once inflammation was triggered, their responses diverged. Histological and immunohistochemical analyses revealed that SIRT3-deficient mice developed more goblet-cell proliferation, abundant mucus plugs, and increased MUC5AC expression, leading to denser, more adhesive mucus. Scanning electron microscopy further demonstrated pronounced shortening and loss of epithelial cilia, suggesting weakened mucociliary transport capacity.
Functional measurements supported these structural findings. SIRT3-knockout mice showed a higher passive opening pressure, indicating increased resistance to tube opening. While neither SIRT3 deficiency nor LPS alone produced a substantial drop in mucociliary clearance, their combination caused a significant decline in transport distance. The ability to actively clear negative pressure was also reduced under baseline conditions, implying that SIRT3 contributes to maintaining mechanical responsiveness.
The results clearly show that without SIRT3, the eustachian tube becomes more susceptible to inflammatory overload, as mucus thickens, cilia deteriorate, and pressure-regulation mechanisms fail. This discovery highlights the role of SIRT3 as a stabilizing force during inflammation, and its absence leads to a loss of resilience, with mucus becoming heavier, clearance slowing, and pressure equalization becoming more difficult. Understanding this protective role helps explain why certain individuals are more prone to chronic or recurrent ear infections, and it may guide new therapeutic strategies.
The study suggests that SIRT3 governs mucus secretion, ciliary integrity, and pressure regulation, opening up new therapeutic opportunities for treating eustachian tube dysfunction and preventing chronic otitis media. Enhancing SIRT3 activity or targeting its downstream protective pathways may help restore mucociliary function, reduce mucus obstruction, and accelerate recovery from infection-driven inflammation. Since excessive MUC5AC production and ciliary impairment are also observed in respiratory diseases, these insights may extend beyond otology to broader airway research. Ultimately, therapies that strengthen mitochondrial resilience could reshape clinical approaches to persistent middle-ear and airway conditions.
