Uroepithelium

The uroepithelium, also known as the urothelium, is a specialized stratified tissue that lines the urinary tract, including the renal pelvis, ureters, bladder, and proximal urethra (StatPearls, 2023). It serves as a critical blood-urine barrier, preventing the passage of water, ions, and toxic metabolic waste products back into the systemic circulation (NCBI, 2019). This barrier is maintained by unique proteins called uroplakins and tight junctional complexes that ensure high electrical resistance (Nature Reviews Urology, 2020). Beyond its barrier function, the uroepithelium acts as a sensory organ that communicates with the underlying nervous and muscular systems to coordinate bladder filling and voiding (PubMed, 2015). It expresses various receptors, such as muscarinic and adrenergic receptors, which are targets for treating overactive bladder (NIH, 2021). In clinical practice, it is the primary site for urothelial carcinoma and is frequently affected by inflammatory conditions like interstitial cystitis and infections (Nature Reviews Urology, 2020). While not a single molecular target, it is a major site for intravesical drug delivery, where therapeutic agents like BCG or gemcitabine are instilled directly into the bladder (PubMed, 2018). Pathogens like Uropathogenic E. coli (UPEC) specifically target urothelial cells by binding to uroplakin receptors to initiate infection (Nature Reviews Microbiology, 2022).

Other names

UrotheliumTransitional epitheliumUrinary epithelium

Drugs targeting the uroepithelium generally work through intravesical instillation to achieve high local concentrations for treating malignancy or by modulating receptors (e.g., muscarinic, adrenergic, or vanilloid) on urothelial cells to alter bladder sensation and contractility.