TNFRSF1A and chronic obstructive pulmonary disease: Circulating exosomes, identified as CD9+ macrovesicles, and plasmatic systemic inflammation biomarkers, such as C-reactive protein (CRP), soluble tumor necrosis factor receptor-1 (sTNFR1) and interleukin (IL)-6, were quantified in patients with acute exacerbation of COPD (n = 20) or stable COPD (n = 20), and non-smoking healthy controls (n = 20).