TLR4 and infection: In line, our laboratory previously exposed a protective role for TLR2 during airway infection with a S. pneumoniae strain deficient for pneumolysin, an intracellular toxin recognized by TLR4, suggesting that during infection with WT S. pneumoniae TLR2 deficiency can be compensated for by pneumolysin-induced TLR4 signaling [12].