Mechanical activation of adipose tissue macrophages mediated by Piezo1 protects against diet-induced obesity by regulating sympathetic activity

Objective: Obesity-induced mechanical changes in white adipose tissue (WAT), including adipocyte hypertrophy and fibrosis, are hypothesized to alter adipose tissue macrophage (ATM) function through mechanosensitive pathways. This study aimed to determine whether the mechanosensor Piezo1 in ATMs regulates obesity-associated metabolic dysfunction and thermogenesis. Methods: To investigate macrophage Piezo1 in obesity, myeloid-specific Piezo1-deficient mice (Piezo1 Delta lyz2) and littermate controls (Piezo1flox/+) were fed a high-fat diet (HFD) to induce obesity for 12 weeks. Metabolic assessments (GTT/ITT), tissue analyses (H&E staining, micro-CT), and RNA-seq were performed. Bone marrow transplantation and co-culture experiments (BMDMs with 3T3L1 adipocytes/PC12 neurons) were performed to evaluate macrophage-adipocyte/neuron crosstalk. Sympathetic activity was tested via cold exposure, NE measurement, and 6-OHDA/alpha MPT denervation. Molecular mechanisms were investigated using ChIP-qPCR. Results: Piezo1 Delta lyz2 mice exhibited aggravated HFD-induced obesity and insulin resistance despite reduced pro-inflammatory responses. Piezo1 deficiency in ATMs suppressed Slit3-ROBO1 signaling, leading to diminished NE secretion and impaired thermogenesis. Pharmacological inhibition of NE release (6-OHDA) or ROBO1 knockdown (shROBO1) abolished thermogenic disparities between Piezo1 Delta lyz2 and control mice. Mechanistically, Piezo1 activation triggered SP1 nuclear translocation, directly binding to the Slit3 promoter to drive Slit3 transcription and secretion. Conclusion: Piezo1 in ATMs mitigates obesity progression by promoting Slit3-ROBO1-dependent NE secretion and thermogenesis, independent of its pro-inflammatory role. This mechanosensitive pathway links WAT mechanical remodeling to metabolic regulation, which may offer a novel approach for managing obesity.