Pathogenesis of Henoch-Schönlein purpura nephritis

The severity of renal involvement is the major factor determining the long-term outcome of children with Henoch-Schönlein purpura (HSP) nephritis (HSPN). Approximately 40% children with HSP develop nephritis, usually within 4 to 6 weeks after the initial onset of the typical purpuric rashes. Although the pathogenetic mechanisms are still not fully delineated, several studies suggest that galactose-deficient IgA1 (Gd-IgA1) is recognized by anti-glycan antibodies, leading to the formation of the circulating immune complexes and their mesangial deposition that induce renal injury in HSPN.

Crosstalk between peroxisome proliferator-activated receptor-gamma and angiotensin II in renal tubular epithelial cells in IgA nephropathy

Our recent study suggested that peroxisome proliferator-activated receptor-gamma (PPAR-gamma) agonist attenuates inflammatory response in activated tubular epithelial cells in IgA nephropathy (IgAN). Here, we explore thiazolidinediones as new therapeutic additives to established treatment regime of renin angiotensin blockade in IgAN. Human proximal tubular epithelial cells (PTEC) were pretreated with PPAR-gamma agonist, rosiglitazone, and/or angiotensin II (AngII) type 1 receptor (ATR1) blocker (ARB), losartan, followed by activation with the conditioned medium collected from human mesangial cells incubated with pIgA1 (IgA-HMC) from patients with IgAN. IgA-HMC conditioned medium up-regulated expression of ICAM-1, IL-6 and ATR1 and activated NF-kappaB and ERK1/2 in PTEC. Dual treatment of rosiglitazone and losartan provided synergistic effect in reducing ICAM-1, IL-6 and ATR1 expression and NF-kappaB and ERK1/2 activation induced by the conditioned media when compared with monotherapy. Our data suggest that rosiglitazone trans-represses AngII signaling and may offer additional potential when combined with ARB in treating IgAN.