Thus, the influence of dehydration on susceptibility to pyelonephritis is mediated, at least in part, by vasopressin signaling via V2R that impairs uropathogenic Escherichia coli (UPEC)‐UTI clearance by attenuating Tlr‐4‐dependent innate immune responses to UPEC‐UTI (Chassin et al., 2007). Here, TLR4 is linked to pyelonephritis.