Role of leukocyte adhesion molecules in monocyte/macrophage infiltration in weanling rats with unilateral ureteral obstruction

Background: Unilateral ureteral obstruction (UUO) of rats is a well-establi shed model for studying obstructive nephropathy. Meanwhile, pathophysiology of pediatric obstructive nephropathy is not well understood. In this repor t, we studied monocyte/macrophage infiltration and expression of intercellu lar adhesion molecule 1 (ICAM-1) and macrophage antigen 1 (Mac-1) in weanli ng rats with UUO. Methods: Three-week-old male Sprague-Dawley rats underwent left unilateral ureteral ligation. Both obstructed kidneys (OBK) and contralateral kidneys (CLK) were harvested at, 6, 12, 24, 72 and 120 h after surgery. Monocyte/ma crophage infiltration and expression of ICAM-1 and Mac-1 were evaluated imm unohistochemically, and results were compared with those of sham-operated c ontrol rats (SOK). Results: Monocyte/macrophage infiltration was observed in the interstitium and perivascular region in the cortex of OBK within 6 h. The CLK and SOK sh owed slight monocyte/macrophage infiltration. Expression of ICAM-1 was mark edly observed in the periarterial and peritubular interstitium and in renal cortical peritubular capillaries 12 h after obstruction. In CLK and SOK, I CAM-1 was slightly expressed in the endothelium of microvessels and parieta l linings of Bowman's capsule. Expression of Mac-1 was detected mainly in c ells infiltrating the perivascular interstitium in OBK. In CLK and SOK, few Mac-1-positive cells were observed. Conclusions: Adhesion molecules, ICAM-1 and Mac-1, are expected to recruit monocyte/ macrophage infiltration into OBK of weanling rats with UUO.