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Surfactant Protein A can Affect the Surface Tension of the Eustachian Tube and Macrophage Migration
Guodong Li1,2, Tao Chen1,3, Yanyan Mao1
1Department of Otolaryngology-Head and Neck surgery, Shandong Provincial ENT Hospital, Shandong University, Jinan, Shandong, China.
Objective:
To assess the role and possible mechanism of surfactant protein A (SPA) in the pathogenesis of otitis media with effusion (OME).
Methods:
This was a multi-part study with both an in vivo mouse model study as well as an in vitro study. The control and study groups (OME group) received phosphate-buffered saline and inactivated Streptococcus pneumoniae, respectively, via external auditory meatus injections. Changes in the surface tension of secretions from the eustachian tube (ET) and SPA expression were measured in both groups. A transwell assay was performed to observe the effect of different concentrations of SPA on the migration ability of macrophages. We examined the differentially expressed genes related to SPA-treated macrophages using RNA-seq analysis.
Results:
On Day 3, the surface tension of the OME group was higher than that of the control group (p = 0.014). The variation intensity of SPA in the ET of the OME group was significantly lower than that of the control group (p < 0.001). Surface tension was correlated with SPA (r = -0.525, p = 0.037). The expression of SPA and macrophages in the ET was different between the two groups. In vitro experiments revealed that macrophages showed different migration abilities with SPA concentration changes (p < 0.05). RNA-seq and western blotting were performed after macrophages were treated with SPA. The results showed that RhoA and Rac1/2/3 were differentially expressed.
Conclusions:
SPA can change the surface tension of secretions from the ET and affect macrophage migration to alter the function of the ET. Although research in this field of OME is nascent, initial work suggests that SPA likely plays an important role in OME progression.
Level Of Evidence:
NA Laryngoscope, 133:1726-1733, 2023.
Insights
Surfactant protein A (SPA) influences eustachian tube secretions and macrophage activity, impacting otitis media with effusion (OME) progression. Lower SPA levels correlate with increased surface tension in OME.
Area of Science:
- Otorhinolaryngology
- Immunology
- Pulmonary Biology
Background:
- Otitis media with effusion (OME) is a common condition affecting the middle ear.
- The role of specific immune factors like surfactant protein A (SPA) in OME pathogenesis is not fully understood.
Purpose of the Study:
- To investigate the role of surfactant protein A (SPA) in the development of otitis media with effusion (OME).
- To elucidate the potential mechanisms by which SPA influences OME pathogenesis.
Main Methods:
- A multi-part study combining in vivo mouse models and in vitro experiments.
- Assessment of eustachian tube (ET) secretion surface tension and SPA expression in control and OME groups.
- In vitro analysis of macrophage migration and gene expression (RNA-seq) following SPA treatment.
Main Results:
- OME group exhibited higher ET secretion surface tension and lower SPA expression compared to controls.
- SPA levels were inversely correlated with surface tension (r = -0.525, p = 0.037).
- SPA concentration affected macrophage migration, and differentially expressed genes included RhoA and Rac1/2/3.
Conclusions:
- Surfactant protein A (SPA) modulates ET secretion surface tension and macrophage migration, influencing ET function.
- SPA appears to play a significant role in the progression of otitis media with effusion (OME).
- Further research is warranted given the nascent stage of SPA investigation in OME.
