Airway epithelial MyD88 restores control of Pseudomonas aeruginosa murine infection via an IL-1-dependent pathway.

The opportunistic human pathogen Pseudomonas aeruginosa causes rapidly progressive and tissue-destructive infections, such as hospital-acquired and ventilator-associated pneumonias. Innate immune responses are critical in controlling P. aeruginosa in the mammalian lung, as demonstrated by the increased susceptibility of MyD88(-/-) mice to this pathogen. Experiments conducted using bone marrow chimeric mice demonstrated that radio-resistant cells participated in initiating MyD88-dependent innate immune responses to P. aeruginosa. In this study we used a novel transgenic mouse model to demonstrate that MyD88 expression by epithelial cells is sufficient to generate a rapid and protective innate immune response following intranasal infection with P. aeruginosa. MyD88 functions as an adaptor for many TLRs. However, mice in which multiple TLR pathways (e.g., TLR2/TLR4/TLR5) are blocked are not as compromised in their response to P. aeruginosa as mice lacking MyD88. We demonstrate that IL-1R signaling is an essential element of MyD88-dependent epithelial cell responses to P. aeruginosa infection.