Intraglomerular expressions of IL-1 alpha and platelet-derived growth factor (PDGF-B) mRNA in experimental immune complex-mediated glomerulonephritis.

Both PDGF and IL-1 play important roles as autocrine growth factors for cultured mesangial cells, and may be closely associated with the progression of glomerulonephritis. In this study we investigated intraglomerular expressions of PDGF-B and IL-1 alpha mRNA in mice with bovine serum albumin (BSA) nephritis, a model of immune complex-mediated glomerulonephritis, using the reverse transcription-polymerase chain reaction (RT-PCR) method. We also quantified intraglomerular PDGF-B mRNA by the competitive PCR and studied the correlation between the level of intraglomerular PDGF-B mRNA expression and the degree of observed glomerular injury. While expression of neither PDGF-B nor IL-1 alpha mRNA was detected in glomeruli from control mice, both were strongly expressed in glomeruli from mice with BSA nephritis. IL-1 alpha mRNA in glomeruli showed low accumulation in mice with mild glomerular injury, and was increased in mice with moderate glomerular injury. In contrast, high intraglomerular expression of PDGF-B mRNA occurred in all mice with mild glomerular injury and continued throughout the course of the disease. We observed no correlation between the level of PDGF-B mRNA expression and the histologic grade of renal damage. These results suggest that PDGF and IL-1 have different growth properties, and PDGF might play a role as a competence factor rather than a progression factor in the pathogenesis of immune complex-mediated glomerulonephritis.