Fig 2: TSA alleviates the induction of inflammatory cytokines in Col4a3 KO mice.(A) The mRNA level of proinflammatory cytokines IL-1β and TGF-β1 was higher in the cochlea of Col4a3 KO mice, while IL-6 and TNF-α were significantly increased compared to wild-type (WT) mice. This effect was attenuated by TSA treatment (n = 7). (B) The protein level of IL-6, IL1β, TNF-α, and TGF-β1 was all significantly increased in HEK293T cells following transient transfection of siCol4α3. This effect was attenuated by TSA treatment (n = 3). (C) TSA treatment significantly decreased IL-6, IL1β, TNF-α, and TGF-β1 protein levels in HEI-OC1 cells (n = 7). Data are presented as mean ± SEM. *P < 0.05, **P < 0.01, ***P < 0.001 based on ANOVA with Tukey’s post hoc test.

Fig 3: TSA inhibits Col4a3 KO-induced oxidative stress in stria vascularis.(A) Representative image of SV mice. SV immunostaining was conducted using antibodies directed towards 4-HNE (green). (B) The protein expressions of 4-HNE and 3-NT were significantly increased in HEK293T cells after transient transfection with siCol4α3. This effect was attenuated by TSA treatment (n = 6). Data are presented as mean ± SEM. *P < 0.05, **P < 0.01, ***P < 0.001 based on ANOVA with Tukey’s post hoc test. (C) Treatment of HEI-OC1 cells with TSA resulted in reduced expressions of 4-HNE and 3-NT proteins. The quantification results showed that TSA treatment of HEI-OC1 cells reduced the protein expressions of 4-HNE and 3NT (n = 3). Data are presented as mean ± SEM. *P < 0.05, **P < 0.01, ***P < 0.001 based on ANOVA with Tukey’s post hoc test.

Fig 4: Schematic diagrams of TSA protection against progressive sensorineural hearing loss induced by Col4a3 KO.Collagen type 4 α3 chain (Col4a3) knockout (KO) induces inflammation and oxidative stress in the cochlea. Basement membrane (BM) of the stria vascularis vessels is thickened which all leads to hearing impairment. Trichostatin A (TSA) increases the expression of HO-1. The upregulation of HO-1 inhibits proinflammatory gene activation, ROS gene production and reduces stria vascularis BM thickening.

Fig 5: TSA attenuates Col4a3 KO-induced stria vascularis basement membrane thickening.(A) Transmission electron microscopy (TEM) shows a thickened basement membrane of the stria vascularis in Col4a3 KO mice, a pathology that is reduced by TSA treatment. Insets (red square) are shown at a higher magnification on the bottom. On the bottom lane, red straight lines illustrate the basement membrane. (B) Quantification results for the basement membrane thickness in the stria vascularis. Data are presented as mean ± S.E.M. *P < 0.05, **P < 0.01, ***P < 0.001 based on ANOVA with Tukey’s post hoc test. Numerals in bar graphs represent the number of samples.