NLRP3 and chronic obstructive pulmonary disease: On the other hand, all three groups of COPD patients in terms of smoking status showed to have increased NLRP3 mRNA levels in comparison to healthy non-smokers but only former and current COPD smokers had increased NLRP3 expression compared to healthy smokers, while COPD non-smokers did not differ in NLRP3 expression from healthy smokers.