Considering the anatomical location of the urethral meatus, it is surprising that urine is
normally sterile. The defensive properties of uroepithelia help maintain this sterility as
strategically necessary for long-term survival. Epithelia lining the urinary tract prevent
adhesion of bacteria by release of Tamm-Horsfall protein, lactoferrin, lipocalin, and
constitutive and inducible bactericidal antimicrobial peptides such as α-and β-defensins and
cathelicidin. Microbes that overwhelm these early defenses contact uroepithelia and activate …