TNF and endothelial dysfunction: The hallmark of endothelial dysfunction is reduced synthesis of nitric oxide (NO), increased vasoconstrictor peptide endothelin-1 (ET-1), and increased production of the asymmetric dimethylarginine (ADMA) and inflammatory cytokines, including interleukin-6 (IL-6), C-reactive protein (CRP) and tumor necrosis factor-a (TNF-a) [24].