The Expression of Interleukin-6 and Its Receptor in the Developing Rat Kidney

Lee, Choong Bum; Syn, Ha U; Cho, Dae Haeng; Choi, Jae Youn; Cha, Jung Ho

Abstract

Interleukin-6 (IL-6) and its receptor are presumed to play important roles in the developing nervous system. However, little is known about their potential role(s) in the developing kidney. To investigate this, we have studied the expression of IL-6 and its receptor (IL-6R) in the developing rat kidney. Kidneys from 16- (F16), 18- and 20-day-old (F20) fetuses, 1- (P1), 3- (P3), 7- (P7) and 14-day-old (P14) pups, and adult rats were extracted. Renal expressions of IL-6 and its receptors were examined by immunohistochemistry and in situ hybridization respectively. Il-6 protein already appeared in F16. The early stage of renal development before birth, IL-6 showed strong immunoreactivity in the ureteric bud, metanephric mesenchymal cells (MMC) and developing glomerulus. The expression pattern of IL-6 in nephrogenic zone are very similar even after birth. In matured nephron after birth, IL-6 immunoreactivities were detected in distal tubules strongly, and collecting ducts moderately and thick ascending limb weekly. IL-6R hybridization signals have also already appeared in 16-day old fetal kidney. Before birth, IL-6R mRNAs were expressed in ureteric bud, MMC and developing glomerulus. In the matured nephron after birth, IL-6R mRNA was expressed in the thick ascending limb, distal tubules, collecting ducts and S3 segment of proximal tubule. These results suggest that IL-6 and its receptor may be involved in regulation of nephron formation in nephrogenic zone of rat, and play a role in distal nephron including collecting duct after birth.