Characterization of urinary bikunin and its role in urolithiasis
Fouad Atmani
Abstract
A new urinary inhibitor of calcium oxalate formation was isolated from the urine of healthy subjects. The same protein isolated from the urine of stone formers showed less inhibitory activity than that of controls. This inhibitor was also isolated from the urine of rats and bovine kidneys. It was identified later as urinary bikunin, the light chain of inter-alpha-inhibitor (I-a-I). Its presence in organic matrices of crystals and kidney stones indicates that it may fulfill a directive role in lithogenesis. By using a nephrolithic rat model, it was demonstrated that bikunin gene can be expressed in the kidney. Altogether, the data suggests that kidneys possess a defense system against calcium oxalate crystallization and stone formation which is mainly driven by proteins of I-a-I family, especially urinary bikunin. Key words: ARDS, surfactant, PLA2, Prostaglandin E2, TNF