Glomerular endothelial cells and podocytes can express CD80 in patients with minimal change disease during relapse

Background Urinary CD80 has emerged as potential biomarker in idiopathic nephrotic syndrome (INS). However, its cellular source remains controversial. The aim of the study was to assess whether CD80 is truly expressed by glomerular cells in INS patients during relapse and in the LPS mouse model of podocyte injury. Methods The presence of CD80 in glomeruli was evaluated by combining immunostaining, immunogold labeling, and in situ hybridization techniques. Results CD80 was present along the surface of glomerular endothelial cells (GEC) and rarely in podocytes in six of nine minimal change disease (MCD) patients in relapse, two of eleven patients with focal segmental glomerulosclerosis in relapse, and absent in controls. In mice, CD80 was upregulated at mRNA and protein level in GEC and podocytes, in a similar pattern to that seen in MCD patients. Conclusions Glomerular endothelial cells and podocytes can express CD80 in patients with MCD during relapse. A better understanding of the role of CD80 in glomerular cells may provide further insights into the mechanisms of proteinuria in INS.