TLR4 and corneal infection: We examined the host response in corneal ulcers from patients with culture positive P. aeruginosa or S. pneumoniae, and found elevated expression of the pathogen recognition receptors TLR2, TLR4 and TLR9, pro-inflammatory cytokines IL-1α, IL-1β, and IFN-γ, and the inflammasome components NLRP3, NLRC4 and ASC compared with donor corneas.