Curcumin Inhibits NTHi-Induced MUC5AC Mucin Overproduction in Otitis Media via Upregulation of MAPK Phosphatase MKP-1

Figure 4

Postinfection administration of curcumin inhibits MUC5AC expression in middle ear epithelial cells in vitro and in vivo. (a) HMEECs were pretreated with curcumin (20 μM) 1 h prior to NTHi stimulation or posttreated with curcumin (20 μM) 1 h after NTHi stimulation. MUC5AC mRNA expression was measured after 5 h NTHi stimulation. (b) HMEECs were posttreated with 20 μM curcumin 1 h after NTHi stimulation. 12 h after NTHi stimulation, MUC5AC protein levels in cell culture supernatants were measured by ELISA. (c, d) Mice were given 50 mg/kg (i.p) curcumin 1 h prior to transtympanic inoculation of NTHi or were given 50 mg/kg (i.p) curcumin 1 h after NTHi inoculation. (c) MUC5AC mRNA expression in dissected middle ear was measured after 6 h NTHi inoculation. (d) MUC5AC protein (Alexa 488) expression in dissected middle ear was visualized by immunofluorescence assay after 9 h NTHi inoculation. DAPI, nuclear stain. Original magnification: 400x. Scale bar, 20 μm. (e) Schematic representation illustrating that curcumin suppresses NTHi-induced MUC5AC expression via MKP-1-dependent inhibition of p38 MAPK. (a, c) , ANOVA (Tukey’s post hoc). (b) , -test. n.s., not significant. Data are representative of three or more independent experiments.

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