Unraveling β2-Adrenergic Receptor Signaling Bias Between Gαs and Gα15 in Shaping Macrophage Function

Myocardial infarction and heart failure are leading global causes of mortality. Chronic {beta}-adrenergic receptor ({beta}ARs) activation in cardiomyocytes promotes heart failure via Gs signaling after myocardial infarction, whereas {beta}2AR activation may also provide cardiac protection and repair through alternative pathways. Macrophages play a pivotal role in cardiac repair, and {beta}2AR has been reported to signal via the hematopoietic-specific G15 in these cells. We aim to characterize signaling bias between Gs and G15 downstream of {beta}2AR and to elucidate their roles in macrophage polarization. Using TRUPATH BRET assays, we demonstrate that several {beta}2AR agonists activate G15 with at least an order of magnitude greater potency than Gs. Clinically used {beta}-blockers exhibit differential inhibition on these two pathways. Transcriptome analysis of THP-1-derived macrophage-like cells treated with the {beta}2AR agonist clenbuterol revealed a mixed transcriptional profile with enrichment of both M1 inflammatory and M2/repair-associated gene sets. Knockdown experiments showed that Gs suppresses M1-like phenotypes while enhancing M2-like phenotypes, whereas G15 is specifically required for M2-like regulation. Pharmacological blockade of the Gs-adenylyl cyclase interaction produced opposing effects on M1/M2 signatures compared to Gs knockdown, while producing concordant effects on the repair-associated gene sets. These findings characterize the distinct pharmacological profiles of {beta}2AR ligands toward Gs and G15 and reveal how {beta}2AR agonism modulates macrophage function through dual-transducer signaling. Significance statement{beta}2AR displays marked signaling bias toward the hematopoietic-specific G15 over canonical Gs, with multiple clinically relevant agonists activating G15 at [≥]10-fold higher potency. Clinically used {beta}-blockers exhibit differential inhibition--timolol preferentially blocks Gs, while labetalol has reduced efficacy against G15--while in macrophages, Gs suppresses pro-inflammatory M1 programs and supports M2 repair signatures, whereas G15 specifically reinforces M2-associated and tissue-repair transcriptional modules, revealing a dual-transducer mechanism that may enhance macrophage-mediated cardiac repair after myocardial infarction and support biased {beta}2AR ligands.