SIRT1 targeted bioengineered extracellular vesicles chrono-reprogram microglia to reverse non-dipping hypertension -...

Chronic stress-induced neuroinflammation within autonomic brain nuclei drives stress-induced hypertension (SIH), yet circadian-neuroimmune mechanisms underlying maladaptive hemodynamic rhythms remain unclear. We delineate a novel chronobiological axis where CLOCK dysregulation in rostral ventrolateral medulla (RVLM) microglia orchestrates non-dipping hypertension via Sirt1-dependent polarization and redox-sensitive HMGB1 modifications. Using a foot-shock noise stress paradigm, we observed sustained hypertension with disrupted BP circadian rhythms, attenuated CLOCK oscillations, and diurnal cytokine dysrhythmia in RVLM microglia. Mechanistically, stress-induced CLOCK upregulation disrupted Sirt1 activity via mitochondrial ROS, driving HMGB1 acetylation and ds-HMGB1 release. RVLM CLOCK knockout (Cre-CX3CR1/CLOCK^fl/fl) restored Sirt1-HMGB1 homeostasis, normalized cytokine rhythms, and rescued BP chronobiology. SRT1720 attenuated HMGB1 hyperacetylation and reversed non-dipping hypertension. Notably, genetic CLOCK ablation caused anxiety/depressive behaviors, while whole-brain Sirt1 overexpression induced astrocyte A1 polarization with emotional deficits, highlighting microglia-specific Sirt1 modulation necessity. To target the mitochondria-Sirt1 axis precisely, we engineered bioengineered extracellular vesicles (MG-Sirt1-EVs) for microglia-specific Sirt1 overexpression. Beyond rescuing RVLM mitochondrial homeostasis, circadian oscillations, and neuroinflammation - MG-Sirt1-EVs reversed stress-induced myocardial remodeling: Masson's trichrome/WGA staining revealed reduced fibrosis and normalized cardiomyocyte size; echocardiography showed improved diastolic function (elevated E/A ratio); TH immunostaining and HRV LF/HF ratio confirmed attenuated sympathetic overactivity; molecular markers (BNP, cTnT) were downregulated. MG-Sirt1-EVs outperformed SRT1720 in rest-phase hemodynamic efficacy, reversing non-dipping hypertension while restoring BP rhythms. Dual benefits in cardiovascular (myocardial remodeling reversal) and neuropsychiatric (behavioral rescue) domains were consistently observed. Our findings establish CLOCK/Sirt1-mediated microglial activation as a driver of neuroimmune-cardiovascular dysregulation, offering a translational macromolecule platform for chrono-immunotherapy of comorbid disorders.