NLRP3 and chronic obstructive pulmonary disease: The same results were obtained for IL-33, where we observed that neither the inhibition of caspase-1 (Figures 5A–D) nor the inhibition of NLRP3 and caspase-8 (Figures 5A–D) altered the levels of the cytokine released from PBMCs obtained from unstable COPD patients exposed to combustion-generated UFPs.