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

Figure 1

Curcumin suppresses NTHi-induced MUC5AC expression in middle ear epithelial cells in vitro and in vivo. (a) HMEECs were pretreated with 10, 20, or 50 μM curcumin for 1 h, followed by NTHi for 5 h, and MUC5AC mRNA expression was measured. (b) HMEECs were pretreated with 20 μM curcumin for 1 h, followed by NTHi strain 12, 2627, or 9274 for 5 h, and MUC5AC mRNA expression was measured. (c) HMEECs were transfected with MUC5AC promoter-driven luciferase vector. Cells were pretreated with 20 μM curcumin for 1 h, followed by stimulation with NTHi for 5 h. MUC5AC promoter-driven luciferase activity was measured. (d) HMEECs were pretreated with 20 μM curcumin for 1 h, followed by stimulation with NTHi for 12 h, and MUC5AC protein level in cell culture supernatants was measured by ELISA. (e) HMEECs were pretreated with 20 μM curcumin for 1 h, followed by NTHi stimulation for 12 h. MUC5AC protein (Alexa 488) was visualized by immunofluorescence staining. DAPI, nuclear stain. Original magnification: 400x. Scale bar, 20 μm. (f, g) Mice were given 50 mg/kg (i.p) curcumin 1 h prior to transtympanic inoculation of NTHi. (f) MUC5AC mRNA expression in dissected middle ear was measured after 6 h NTHi inoculation. (g) 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. Data are mean ± s.d. (). (a) , ANOVA (Tukey’s post hoc). (b)–(d), (f) , -test. Data are representative of three or more independent experiments.

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