TLR4 and infection: While the protective impact of TLR4 against infection has been known for some time, recent data has shown that TLR4/LPS signaling induces neutrophil extracellular trap formation and variations in O-antigen can impact susceptibility to bacterial killing by NETs, where uropathogenic E. coli that expresses O-antigen exhibits higher levels of NET formation but also increased resistance to killing (116).