Figure 4

NTHi-induced HBD-2 expression in HMEEC-1 utilizes the TLR2-dependent IRAK-TRAF6-p38MAPK signaling cascade. (A and B) Cells treated with siRNA specific for TLR2, interleukin receptor associated kinase 1 (IRAK1), tumor necrosis factor receptor associated factor 6 (TRAF6), MAP kinase kinase 3 (MKK3), MKK6 and p38 showed significantly lower HBD-2 expression compared to a negative control. (C) The targeted gene knock down using siRNA was confirmed either by RT-PCR or(D) quantitative PCR. (E) Reduced HBD-2 peptide production in the HMEEC-1 cells treated with target specific siRNA, after treatment with NTHi lysate. The siRNA knock down cells were treated with NTHi lysate for 24 hours. The culture supernatant was collected and HBD-2 protein levels were measured by ELISA. The HBD-2 secretion from cells with target gene knock down was substantially lower than in negative siRNA treated controls. In experiments A, B, D and E, values are given as mean ± standard deviation. N = 3. *: p < 0.05.