TNF and chronic obstructive pulmonary disease: Several inflammatory cytokines, including tumour necrosis factor-α (TNFα), interleukin(IL)-6, CXCL8 (IL-8), and IL-18, and acute phase proteins, such as C-reactive protein (CRP), serum amyloid A, and fibrinogen, are increased within the circulation of patients with COPD, particularly during exacerbations [4].