Up-regulated renal expression of TNF-α signalling adapter proteins in lupus glomerulonephritis

The role of tumour necrosis factor (TNF-alpha) signalling adapters in lupus nephritis (LN) is poorly understood. This study investigated renal expression of TNF-alpha and TNF signalling adapter proteins, including TNF receptor-associated death domain protein (TRADD), receptor-interacting protein (RIP) and TNF receptor-associated factor-2 (TRAF-2) in patients with LN. The renal expression of proliferating cell nuclear antigen (PCNA) and CD68 was also measured. The study showed that glomerular and tubular expression of TNF-alpha, TRADD, RIP and TRAF-2 was significantly up-regulated in class III and IV LN in which the intense staining was observed on the crescents, proximal and distal tubules and interstitial mononuclear cells. The number of PCNA-positive cells and CD68-positive cells (macrophages) was increased obviously in class III and IV LN. There was a correlation between the expression levels of TNF-alpha, TRADD, RIP, TRAF-2 and the number of PCNA-positive or CD68-positive cells and active index of renal pathology. These findings suggest that TNF-alpha and TNF-alpha adapters in patients with LN play a role in immunopathogenic injury via transmitting abnormal cell proliferating and proinflammatory signals. The findings have provided further insights into the role of TNF-alpha and its adapter proteins in the pathogenesis of LN and have important therapeutic implications.