C34-18 The Role of Nrf2 in Regulating Neutrophilic Airway Inflammation via the Nlrp3 Inflammasome

Abstract Introduction Nuclear factor erythroid 2-related 2 (Nrf2) is a master transcription factor that coordinates cellular defense programs by inducing genes that mitigate oxidative stress. We previously showed that Nrf2-deficient mice develop more severe neutrophilic airway inflammation than wild-type (WT) mice, and that neutralization of interleukin-17 (IL-17) partially attenuates this phenotype. The incomplete rescue, however, suggests additional mechanisms driving neutrophilic inflammation.The nucleotide-binding oligomerization domain-like receptor pyrin domain containing 3 (NLRP3) inflammasome is a multiprotein complex that senses pathogen- and danger-associated molecular patterns. Upon activation, NLRP3 promotes maturation of pro-caspase-1 into caspase-1, which in turn processes proinflammatory cytokines IL-1β and IL-18 to their active forms and facilitates their secretion. NLRP3 activation has been implicated in neutrophilic asthma, and several reports link NLRP3 activity to neutrophilic airway inflammation.Here, we investigated whether NLRP3 inflammasome signaling contributes to exaggerated neutrophilic airway inflammation in Nrf2-deficient mice and whether targeting Nrf2 could be a therapeutic strategy for neutrophilic asthma. Methods Female BALB/c WT mice (8-12-weeks old) were purchased, and Nrf2-deficient mice on the same background were generated in-house. Mice were sensitized intraperitoneally with 40 µg house dust mite (HDM) plus aluminum hydroxide on day 0 and challenged intranasally with 50 µg HDM on day 10. In additional groups, mice received sulforaphane (Nrf2 activator; 12.5 mg/kg, intraperitoneally, once daily on days 8-13). Ninety-six hours after the final HDM exposure, bronchoalveolar lavage fluid (BALF), lung tissue, and isolated alveolar macrophages were analyzed for inflammatory cell differentials (BALF), ELISA (lung/macrophages), reverse transcription quantitative PCR (lung/macrophages), and Western blotting (lung). Results In an HDM-induced asthma model, Nrf2-deficient mice showed augmented neutrophilic airway inflammation compared with WT controls; lung lysates displayed increased caspase-1 protein and higher IL-1β levels, and alveolar macrophages exhibited significantly elevated NLRP3 and IL-1β. In WT mice, sulforaphane reduced HDM-induced neutrophilic airway inflammation. Together, these data indicate that Nrf2 deficiency amplifies the NLRP3-caspase-1-IL-1β signaling axis and that pharmacologic activation of Nrf2 dampens this response. Conclusions NLRP3 inflammasome signaling contributes to neutrophilic airway inflammation in Nrf2-deficient mice, and Nrf2 activation emerges as a potential therapeutic approach for neutrophilic asthma. This abstract is funded by: None