Innate and adaptive immune responses in the urinary tract.

As new and intriguing details of how uropathogens initiate infections and persist within the urinary tract have emerged, so has important information regarding how the immune system functions within the urinary tract. Recent studies have revealed the existence of a multifaceted innate immune response triggered by Toll-like receptor (TLR) 4 on superficial bladder epithelial cells directed at clearing infection by Gram negative pathogens. Other studies have reported that the adaptive immune response in the urinary tract is effective and that vaccines comprised of bacterial virulence factors or whole dead bacteria can evoke protective immunity against urinary tract infections (UTIs) in animals and humans. As antibiotic therapy becomes increasingly ineffective, modulating the innate and adaptive immune system in the urinary tract using TLR4 ligands and other immunomodulators may become viable options to combat UTIs.