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Otitis media in sperm-associated antigen 6 (Spag6)-deficient mice.

Li X, Xu L, Li J, Li B, Bai X, Strauss JF, Zhang Z, Wang H - PLoS ONE (2014)

Bottom Line: These features are associated with disordered cilia orientation, confirmed by scanning electron microscopy, which leads to uncoordinated cilia beating.However, there were no significant differences in bacterial populations, epithelial goblet cell density, mucin expression and Eustachian tube angle between the mutant and wild-type mice, suggesting that OM was due to accumulation of fluid and mucus secondary to the ciliary dysfunction.Our studies demonstrate a role for Spag6 in the pathogenesis of OM in mice, possibly through its role in the regulation of cilia/basal body polarity through the PCP-dependent mechanisms in the middle ear and Eustachian tubes.

View Article: PubMed Central - PubMed

Affiliation: Otolaryngology-Head and Neck Surgery, Provincial Hospital Affiliated to Shandong University, Jinan, Shandong Province, PR China; Shandong Provincial Key Laboratory of Otology, Jinan, Shandong Province, PR China.

ABSTRACT
Mammalian SPAG6 protein is localized to the axoneme central apparatus, and it is required for normal flagella and cilia motility. Recent studies demonstrated that the protein also regulates ciliogenesis and cilia polarity in the epithelial cells of brain ventricles and trachea. Motile cilia are also present in the epithelial cells of the middle ear and Eustachian tubes, where the ciliary system participates in the movement of serous fluid and mucus in the middle ear. Cilia defects are associated with otitis media (OM), presumably due to an inability to efficiently transport fluid, mucus and particles including microorganisms. We investigated the potential role of SPAG6 in the middle ear and Eustachian tubes by studying mice with a targeted mutation in the Spag6 gene. SPAG6 is expressed in the ciliated cells of middle ear epithelial cells. The orientation of the ciliary basal feet was random in the middle ear epithelial cells of Spag6-deficient mice, and there was an associated disrupted localization of the planar cell polarity (PCP) protein, FZD6. These features are associated with disordered cilia orientation, confirmed by scanning electron microscopy, which leads to uncoordinated cilia beating. The Spag6 mutant mice were also prone to develop OM. However, there were no significant differences in bacterial populations, epithelial goblet cell density, mucin expression and Eustachian tube angle between the mutant and wild-type mice, suggesting that OM was due to accumulation of fluid and mucus secondary to the ciliary dysfunction. Our studies demonstrate a role for Spag6 in the pathogenesis of OM in mice, possibly through its role in the regulation of cilia/basal body polarity through the PCP-dependent mechanisms in the middle ear and Eustachian tubes.

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Otitis media is observed in Spag6-deficient mice.(A–B) Effusion and two bubbles (arrows) could be seen in the mutant mice. (C–D) Some crystals (arrows) were found in a mutant mouse aged 6 months. Fibrous tissue fills the whole middle ear cavity (dotted box). (E–F) At P12 (n = 4, each genotype), the mutant mice did not show otitis media with effusion (OME), some mesenchymal cells (arrows in F) could be observed in the middle ear cavity (ME). (G–H) At P18 (n = 4, each genotype), inflammatory cells began to show in the middle ears of the mutant mice (arrows in H). (I–P) At P180 (n = 1, each genotype), inflammatory cells and effusion were full of the ME(J) and Eustachian tube (ET) (L), Eustachian tube opening (ETO) was blocked by the inflammatory effusions (P). The middle ear epithelium also became thickened in the mutant mice (N, two-ended arrow). Otosteon (OS) was fixed by the surrounding cholesterol crystals (O). Co, cochlea; OE: outer ear; M, mutant; WT, wild-type. (5× magnification, E–J; 20× magnification, K–L; 40× magnification, M–P).
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pone-0112879-g002: Otitis media is observed in Spag6-deficient mice.(A–B) Effusion and two bubbles (arrows) could be seen in the mutant mice. (C–D) Some crystals (arrows) were found in a mutant mouse aged 6 months. Fibrous tissue fills the whole middle ear cavity (dotted box). (E–F) At P12 (n = 4, each genotype), the mutant mice did not show otitis media with effusion (OME), some mesenchymal cells (arrows in F) could be observed in the middle ear cavity (ME). (G–H) At P18 (n = 4, each genotype), inflammatory cells began to show in the middle ears of the mutant mice (arrows in H). (I–P) At P180 (n = 1, each genotype), inflammatory cells and effusion were full of the ME(J) and Eustachian tube (ET) (L), Eustachian tube opening (ETO) was blocked by the inflammatory effusions (P). The middle ear epithelium also became thickened in the mutant mice (N, two-ended arrow). Otosteon (OS) was fixed by the surrounding cholesterol crystals (O). Co, cochlea; OE: outer ear; M, mutant; WT, wild-type. (5× magnification, E–J; 20× magnification, K–L; 40× magnification, M–P).

Mentions: To explore the potential role for Spag6 in the middle ear of mice, Spag6−/− mice and wild-type littermates were studied at five time points from postnatal days 12 (P12) to 6 months of age (four mutant and four wild-type at each time point), and their ears were examined by otoscope and histological sections with H&E staining. Before 12 days (Figure 2E, F), although mesenchymal tissue still existed, cavitation of the middle ear was larger and appeared to proceed earlier in wild-type mice than in mutants. By 18 days (Figure 2G, H), all the mutant mice had bilateral effusion in the middle ear cavity or/and Eustachian tube, thickened tympanic mucosa with inflammatory cells, indicating that the mutant mice have manifestations of OM. The trend continued in 30-day-old mutant mice. At 30 days (Figure 2A, B), effusions had spread throughout the middle ear cavities of mutant mice as OM progressed. Wild-type mice at 30 days showed no OM pathology. Almost all mutant mice die from hydrocephalus by six months of age, but in one mutant mouse surviving to 6 months, the previously noted middle ear pathology was accompanied by capillary hyperplasia, cholesterol crystals, fixation of otosteon and fibrosis (Figure 2C, D, I–P), indicating that tympanosclerosis is secondary to OM.


Otitis media in sperm-associated antigen 6 (Spag6)-deficient mice.

Li X, Xu L, Li J, Li B, Bai X, Strauss JF, Zhang Z, Wang H - PLoS ONE (2014)

Otitis media is observed in Spag6-deficient mice.(A–B) Effusion and two bubbles (arrows) could be seen in the mutant mice. (C–D) Some crystals (arrows) were found in a mutant mouse aged 6 months. Fibrous tissue fills the whole middle ear cavity (dotted box). (E–F) At P12 (n = 4, each genotype), the mutant mice did not show otitis media with effusion (OME), some mesenchymal cells (arrows in F) could be observed in the middle ear cavity (ME). (G–H) At P18 (n = 4, each genotype), inflammatory cells began to show in the middle ears of the mutant mice (arrows in H). (I–P) At P180 (n = 1, each genotype), inflammatory cells and effusion were full of the ME(J) and Eustachian tube (ET) (L), Eustachian tube opening (ETO) was blocked by the inflammatory effusions (P). The middle ear epithelium also became thickened in the mutant mice (N, two-ended arrow). Otosteon (OS) was fixed by the surrounding cholesterol crystals (O). Co, cochlea; OE: outer ear; M, mutant; WT, wild-type. (5× magnification, E–J; 20× magnification, K–L; 40× magnification, M–P).
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4231073&req=5

pone-0112879-g002: Otitis media is observed in Spag6-deficient mice.(A–B) Effusion and two bubbles (arrows) could be seen in the mutant mice. (C–D) Some crystals (arrows) were found in a mutant mouse aged 6 months. Fibrous tissue fills the whole middle ear cavity (dotted box). (E–F) At P12 (n = 4, each genotype), the mutant mice did not show otitis media with effusion (OME), some mesenchymal cells (arrows in F) could be observed in the middle ear cavity (ME). (G–H) At P18 (n = 4, each genotype), inflammatory cells began to show in the middle ears of the mutant mice (arrows in H). (I–P) At P180 (n = 1, each genotype), inflammatory cells and effusion were full of the ME(J) and Eustachian tube (ET) (L), Eustachian tube opening (ETO) was blocked by the inflammatory effusions (P). The middle ear epithelium also became thickened in the mutant mice (N, two-ended arrow). Otosteon (OS) was fixed by the surrounding cholesterol crystals (O). Co, cochlea; OE: outer ear; M, mutant; WT, wild-type. (5× magnification, E–J; 20× magnification, K–L; 40× magnification, M–P).
Mentions: To explore the potential role for Spag6 in the middle ear of mice, Spag6−/− mice and wild-type littermates were studied at five time points from postnatal days 12 (P12) to 6 months of age (four mutant and four wild-type at each time point), and their ears were examined by otoscope and histological sections with H&E staining. Before 12 days (Figure 2E, F), although mesenchymal tissue still existed, cavitation of the middle ear was larger and appeared to proceed earlier in wild-type mice than in mutants. By 18 days (Figure 2G, H), all the mutant mice had bilateral effusion in the middle ear cavity or/and Eustachian tube, thickened tympanic mucosa with inflammatory cells, indicating that the mutant mice have manifestations of OM. The trend continued in 30-day-old mutant mice. At 30 days (Figure 2A, B), effusions had spread throughout the middle ear cavities of mutant mice as OM progressed. Wild-type mice at 30 days showed no OM pathology. Almost all mutant mice die from hydrocephalus by six months of age, but in one mutant mouse surviving to 6 months, the previously noted middle ear pathology was accompanied by capillary hyperplasia, cholesterol crystals, fixation of otosteon and fibrosis (Figure 2C, D, I–P), indicating that tympanosclerosis is secondary to OM.

Bottom Line: These features are associated with disordered cilia orientation, confirmed by scanning electron microscopy, which leads to uncoordinated cilia beating.However, there were no significant differences in bacterial populations, epithelial goblet cell density, mucin expression and Eustachian tube angle between the mutant and wild-type mice, suggesting that OM was due to accumulation of fluid and mucus secondary to the ciliary dysfunction.Our studies demonstrate a role for Spag6 in the pathogenesis of OM in mice, possibly through its role in the regulation of cilia/basal body polarity through the PCP-dependent mechanisms in the middle ear and Eustachian tubes.

View Article: PubMed Central - PubMed

Affiliation: Otolaryngology-Head and Neck Surgery, Provincial Hospital Affiliated to Shandong University, Jinan, Shandong Province, PR China; Shandong Provincial Key Laboratory of Otology, Jinan, Shandong Province, PR China.

ABSTRACT
Mammalian SPAG6 protein is localized to the axoneme central apparatus, and it is required for normal flagella and cilia motility. Recent studies demonstrated that the protein also regulates ciliogenesis and cilia polarity in the epithelial cells of brain ventricles and trachea. Motile cilia are also present in the epithelial cells of the middle ear and Eustachian tubes, where the ciliary system participates in the movement of serous fluid and mucus in the middle ear. Cilia defects are associated with otitis media (OM), presumably due to an inability to efficiently transport fluid, mucus and particles including microorganisms. We investigated the potential role of SPAG6 in the middle ear and Eustachian tubes by studying mice with a targeted mutation in the Spag6 gene. SPAG6 is expressed in the ciliated cells of middle ear epithelial cells. The orientation of the ciliary basal feet was random in the middle ear epithelial cells of Spag6-deficient mice, and there was an associated disrupted localization of the planar cell polarity (PCP) protein, FZD6. These features are associated with disordered cilia orientation, confirmed by scanning electron microscopy, which leads to uncoordinated cilia beating. The Spag6 mutant mice were also prone to develop OM. However, there were no significant differences in bacterial populations, epithelial goblet cell density, mucin expression and Eustachian tube angle between the mutant and wild-type mice, suggesting that OM was due to accumulation of fluid and mucus secondary to the ciliary dysfunction. Our studies demonstrate a role for Spag6 in the pathogenesis of OM in mice, possibly through its role in the regulation of cilia/basal body polarity through the PCP-dependent mechanisms in the middle ear and Eustachian tubes.

Show MeSH
Related in: MedlinePlus