High resolution 2-dimensional electrophoretic analysis of proteins in saline bladder washings

Human urine contains a spectrum of proteins derived from various organs in the body. This investigation was undertaken to identify a group of proteins secreted primarily by bladder urothelium. Saline bladder washouts were collected from 9 male and 4 female patients undergoing routine cystoscopic examination. Each sample was sieved, desalted, freeze-dried and solubilized in urea mix. identical amounts of proteins were pooled according to donor sex. All individual and pooled samples were then subjected to 2-dimensional gel analysis using the ISO-DALT system. Profiles of both groups of subjects were highly reproducible, comparable and resembled those of urine and plasma. Several hundred spots were visualized although most of them as yet remain unrecognized. The proteins identified in bladder washouts include albumin, transferrin, IgG gamma-heavy chain, Gc-globulin, alpha 1-antichymotrypsin, alpha 1-antitrypsin, alpha 1-acid glycoprotein, G4, IgG light chains, alpha 1-microglobulin, and low and high density lipoproteins. Most importantly, while some abundant urinary macromolecules such as Tamm-Horsfall mucoprotein and most acidic urinary proteins were undetectable, albumin and transferrin were relatively less expressed. The 2-dimensional profiles we developed can be used as a data base to study urothelium derived proteins in various disease conditions such as bladder cancer.