β2 ADRENERGIC SIGNALING STIMULATES EARLY IL-1β SECRETION IN MACROPHAGES BY INDUCING MAPK-DEPENDENT Il1b TRANSCRIPTION [ATAC-Seq]

Activating β2 adrenergic receptor (β2AR) on macrophages inhibits the expression of several proinflammatory cytokines, a phenomenon primarily associated with NF-κB inhibition. IL-1β is a hallmark inflammatory cytokine, and NF-κB plays a role in the transcriptional activation of Il1b in the priming phase of the NLRP3 inflammasome. Here, we report that contrarily to expectations, β2AR signaling stimulated transcription of the Il1b gene, either alone or in combination with TLR ligands. Moreover, in vivo experiments demonstrated that mice with increased sympathetic tonus (Adra2ac-/-) produced higher levels of IL-1β in a β2AR-dependent manner during alum-induced peritonitis. Assay for Transposase-Accessible Chromatin using Sequencing (ATAC-Seq) experiments, genome-wide analyses of clustered genomic regions and the utilization of pharmacological inhibitors revealed that β2AR-induced Il1b expression occurs in PKA-, MAP Kinases- and AP-1-dependent manner. Our findings describe that β2AR signaling can regulate macrophage effector function in a complex way that may involve gene-specific mechanisms increasing the expression of pro-inflammatory cytokines such as IL-1β.