Fig. 2

PDGF is the major growth factor for mesangial cells we therefore wanted to investigate the expression of PDGF in mesangial cells from controls or patients with IgA deposits as well as their response to stimulation with PDGF. Mesangial cells (MCs) from patients with IgA nephropathy (IgAN) and controls were stimulated with IgA1 purified from blood from healthy controls (cIgA) or patients with IgAN (gd-IgA) or medium only for 6 h and the gene expression was investigated. The gene expression of PDGFB was not affected for the control MCs when stimulated with either cIgA or gd-IgA. The gene expression of PDGFB was increased for the IgAN MCs when stimulated with either cIgA or gd-IgA and stimulation of gd-IgA on IgAN MCs had a significantly higher expression than in control MCs stimulated with gd-IgA (a). In contrast the gene expression of PDGFRB (gene coding for platelet-derived growth factor receptor beta) was lower in all samples from IgAN MCs compared to the control MCs, but the gene was not further affected by stimulation with either cIgA or gd-IgA (b). Medium was collected from IgAN MCs and control MCs after 6 and 24 h of stimulation with cIgA and gd-IgA and the release of PDGF-BB into the medium was measured. Both the IgAN MCs and control MCs released the highest amounts of PDGF-BB when stimulated with gd-IgA, but the levels was significantly higher for the IgAN MCs than for the control-MCs after 6 h (c) and 24 h (d). Mesangial cells from patients with IgAN and control were treated with 50 ng of either PDGF-AB or -BB or medium only and the relative proliferation of the cells was measured. Stimulation of the IgAN MCs with PDGF gave a significant increase of the relative proliferation compared to control MCs (e). Grey bars represent control MCs, black bars represent IgAN MCs *P < 0.05, **P < 0.01, **P < 0.001. Error bars in (a), (b), (c) and (d) represent SEM and in D min to max, + represents mean