In vitro stimulation of a bladder cell line with the non-pathogenic strain E. coli K-12 causes TLR4 activation and inflammatory cytokine response (leading to phagocyte recruitment), while stimulation with uropathogenic E. coli (UPEC) reduces cytokine production and activation of immune surveillance, even during co-infection with activators [40,41]. This evidence concerns the gene TLR4 and coinfection.