TNF and chronic obstructive pulmonary disease: The levels of circulating IL-6, fibrinogen and tumour necrosis factor (TNF) were higher in the subjects with COPD (V1) compared with baseline values for both HV groups (online supplementary figure E5B; COPD vs LPS-treated HVs: p<0.001, p=0.005 and p<0.001, respectively; COPD vs saline-treated HVs: p=0.003, p=0.024 and p=0.017, respectively).