TLR4 and cystic fibrosis: Interestingly, neither CF nor the IHCM expressed TLR2, while the expression of TLR4 was slightly increased after 8 and 24 h stimulation with LPS in CF but not in the IHCM, and TLR3 was highly expressed after 8 and 24 h stimulation with PolyIC in CF but not in the IHCM (Fig. 1a, b, and c).