The effect of β2-adrenoceptor agonist formoterol on activation of NLRP3 inflammasome and pyroptosis in N9 mouse microglial cells

Microglia are immune cells that play an important role in the development of innate immune responses in the central nervous system. The NOD-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome is a multi-protein structure crucial for innate immunity, activated by various danger signals. Overactivation of the NLRP3 inflammasome prompts the release of cytokines like interleukin-1β (IL-1β) and interleukin-18 (IL-18) via caspase-1 and stimulates pyroptotic cell death, contributing to the pathogenesis of neurodegenerative diseases (NDs). Therefore, regulation and inhibition of inflammasome activation may be a beneficial approach in the treatment and prevention of NDs. β2-agonists are drugs that activate β2-adrenoceptors, and they are widely used in the clinic for the treatment of respiratory diseases such as asthma and chronic obstructive pulmonary disease. β2-adrenoceptors are highly expressed in the brain, and studies in which β2-adrenoceptor agonists have been used as a therapeutic approach in NDs have reported that they have potent anti-inflammatory and neuroprotective effects. However, there is no study in the literature that evaluates the effects of the β2-adrenoceptor agonist Formoterol on NLRP3 inflammasome activation and pyroptosis in microglial cells. This study aimed to investigate the impact of Formoterol on inflammasome activation and pyroptosis in N9 microglial cells. Activation of the NLRP3 inflammasome in N9 microglia cells was induced by LPS and ATP. Afterwards, the effect of formoterol on inflammasome activation and pyroptosis in N9 microglia cells was investigated. Cell viability was determined by CCK-8, cytotoxicity and pyroptosis by LDH assay. To determine inflammasome activation and pyroptosis; IL-1β and IL-18 levels were determined by ELISA, pyroptotic death by active caspase-1 and PI staining, and the levels of proteins associated with NLRP3 inflammasome and pyroptosis by Western blot. The study revealed that Formoterol suppressed caspase-1 activity, IL-1β, and IL-18 cytokine release in the NLRP3 inflammasome model, reduced levels of NLRP3 inflammasome-related proteins, inhibited these processes through the IκBα/NF-κB pathway, and prevented pyroptotic cell death.