Acute activation of Gq-signaling in islet macrophages inhibits β-cell insulin secretion through AMPK-sphingolipid axis.

Obesity-associated inflammation disrupts pancreatic β-cell function, but the immune-derived signals that directly regulate insulin secretion remain incompletely defined. Here, we identify myeloid Gq signaling as a critical immunometabolic node that links macrophage activation to β-cell dysfunction. For the first time, we employed a chemogenetic approach (DREADDs) to selectively and temporally activate Gq-coupled GPCR signaling in myeloid cells to examine its effect on islet function. Our findings reveal that acute Gq activation in islet-resident macrophages impaired glucose-stimulated insulin secretion, uncovering a previously unrecognized immune-endocrine axis. Conversely, myeloid-specific Gαq deletion improves systemic glucose homeostasis, underscoring the physiological relevance of this pathway. Mechanistic analysis revealed that Gq activation in macrophages stimulates AMPK signaling and drives the secretion of sphingolipids. These lipids suppress insulin secretion and introduce a new mechanism for immune-islet communication, extending beyond traditional cytokine-based models. We further identify the lipid-sensing receptor GPR18 as an upstream activator of the Gq-AMPK pathway in macrophages. GPR18 stimulation recapitulated the Gq-dependent sphingolipid secretion and β-cell inhibitory phenotype, which was abolished in myeloid Gαq-deficient mice. Collectively, these findings establish a mechanistic framework whereby macrophage Gq signaling integrates lipid sensing and metabolic stress to modulate β-cell function. This work reveals a previously unrecognized macrophage-β-cell communication axis with therapeutic potential for restoring insulin secretion in metabolic diseases such as obesity and type 2 diabetes.