CASP1 and chronic obstructive pulmonary disease: However, in another study by Di Stephano et al. [10], no significant activation of inflammasomes was found based on protein expression of caspase-1 and NLRP3 in bronchial mucosa and IL-1β, IL-18 in BAL of smokers and patients with mild/moderate or severe COPD compared to healthy non-smokers.