Suppression of tumor necrosis factor receptor associated factor (TRAF)-2 attenuates the proinflammatory and proliferative effect of aggregated IgG on rat renal mesangial cells

Abstract

Immune-complex (IC) mediated glomerulonephritis (GN) is a common cause of chronic kidney disease associated with increased levels of tumor necrosis factor (TNF)-alpha in renal cells. TNF-alpha signaling pathways involve complicated interactions between multiple proteins including TNF-receptor-associated factor (TRAF)-2. We have previously found markedly up-regulated expression of TRAF-2 in renal tissues from IC mediated lupus nephritis patients. Here we investigated the effect of TRAF-2 on inflammatory response in rat mesangial cells (MCs). The results showed that treatment with soluble aggregated IgG (AIgG) resulted in a time- and dose-dependent increase in the expression of interleukin (IL)-1beta and IL-6. Significant cell proliferation was also observed after the treatment with soluble AIgG. Knockdown TRAF-2 by siRNA significantly suppressed soluble AIgG induced up-regulation of TRAF-2, IL-1beta, and IL-6. Meanwhile the cell proliferation was inhibited and apoptotic cells were increased. It was concluded that TRAF-2 could induce the proinflammatory and proliferative effects of soluble AIgG on rat MCs. Thus, TRAF-2 may represent a future target for therapy of IC mediated GN.