TNF and fibrosis: Many inflammatory cytokines are involved in the pathogenesis of DN, including cell adhesion molecules (CAMs), monocyte chemotactic protein-1 (MCP-1), tumor necrosis factor-α (TNF-α), interleukin-1 (IL-1), interleukin-6 (IL-6), interleukin-18 (IL-18), transforming growth factor-β (TGF-β), adiponectin, leptin, and resistin which are believed to be essential for DN because of cellular injury and progressive fibrosis [4].