Intercellular Adhesion Molecule 1 Mediates Mononuclear Cell Infiltration into Rat Glomeruli after Renal Ablation

Mononuclear cells, primarily macrophages and lymphocytes, infiltrate the renal glomeruli and are involved in the progression of various glomerular diseases. Intercellular adhesion molecule 1 (ICAM-1) is expressed on the vascular endothelium and mediates the infiltration of leukocytes into the site of inflammation. Although the expression of ICAM-1 can be induced by the stimulation of inflammatory cytokine, ICAM-1 expression can also be induced by such nonimmune mechanisms as shear stress. Glomerular hyperfiltration is a major mechanism that contributes to the progression of the glomerular sclerosis that results from the loss of functioning nephrons. In the present study, we examined the role of ICAM-1 for mononuclear cell infiltration in the glomeruli of the five-sixth nephrectomized rat as a model of glomerular hyperfiltration. The fluorescence intensity score of the staining for ICAM-1 in the glomeruli of the five-sixth nephrectomized rats was significantly increased as compared with that in the control (sham-operated) rats at 1 week (1.51 ± 0.15 vs. 0.61 ± 0.13; p < 0.01) and 2 weeks (1.31 ± 0.17 vs. 0.51 ± 0.09; p < 0.01). The number of leukocytes present in the glomeruli was significantly increased in the five-sixth nephrectomized rats compared with control (sham-operated) rats at 1 week (3.44 ± 0.16 vs. 0.99 ± 0.08; p < 0.01) and 2 weeks (3.14 ± 0.14 vs. 0.89 ± 0.07; p < 0.01). Leukocytes mainly consisted of macrophages in the five-sixth nephrectomized rats at 1 week (2.39 ± 0.19) and 2 weeks (1.46 ± 0.11). Anti-ICAM-1 monoclonal antibody effectively prevented the infiltration of macrophages into the glomeruli following nephrectomy. These results indicate that glomerular hyperfiltration may be involved in the induction of the expression of ICAM-1 and the infiltration of macrophages into the renal glomeruli following glomerular injury.