TNF and chronic kidney disease: Methods: The circulating MMP-2/TIMP-2 system, proinflammatory cytokines (tumor necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6), and the marker of oxidative stress—Cu/Zn superoxide dismutase (Cu/Zn SOD)—were measured in 23 CKD patients treated with β-blockers [β-blockers (+)] and in 27 CKD patients not receiving the above medication [β-blockers (−)].