Endothelial p22phox-dependent NADPH oxidases govern regional myocardial vulnerability in Takotsubo syndrome

Background Takotsubo syndrome (TTS) is an acute heart failure syndrome characterized by transient, regionally confined left ventricular (LV) systolic dysfunction triggered by catecholamine excess. Beyond dysregulated β-adrenergic signaling, endothelial oxidative stress and inflammation contribute to TTS pathophysiology. cAMP/PKA signaling regulates endothelial redox balance, and prior endothelial studies showed that TTS plasma induces reactive oxygen species (ROS), attenuated by cAMP elevation. Redox-sensitive metabolic pathways, including SGLT2, have emerged as modulators of cardiovascular oxidative stress. Purpose To determine whether endothelial NADPH oxidase-derived ROS mediate apical LV dysfunction in an epinephrine-induced mouse model of TTS. Methods Mice with endothelial-specific deletion of the NADPH oxidase subunit p22phox (ecp22phoxKO) and wild-type littermates received intraperitoneal epinephrine (2.5 mg/kg). Transthoracic echocardiography was performed at baseline and up to 24 h post-injection. Myocardial ROS formation was assessed by dihydroethidium fluorescence, gene expression by RT-qPCR, protein localization by immunofluorescence, and inflammatory cell infiltration by CD68 immunostaining. Plasma proteomic profiling was performed in TTS patients (n=19) and healthy controls (n=20). Results Wild-type mice developed rapid, transient, and regionally restricted apical LV dysfunction, recapitulating the hallmark phenotype of human TTS, with reduced ejection fraction, increased systolic diameter, and impaired apical strain while basal function was preserved. Apical dysfunction was accompanied by increased ROS formation, upregulation of NADPH oxidase subunits, endothelial activation (ICAM-1, VCAM-1), senescence (p16, p21), pro-inflammatory cytokines (TNF-α, IL-6), CD68⁺ macrophage infiltration, and apex-specific upregulation of endothelial SGLT2 expression. In contrast, ecp22phoxKO mice were protected from apical LV dysfunction, with preservation of systolic function and marked attenuation of oxidative stress, endothelial activation, inflammatory signaling, macrophage infiltration, and SGLT2 upregulation, indicating redox-dependent regulation downstream of endothelial NADPH oxidases. Plasma proteomics revealed enrichment of adrenergic, cAMP/PKA, oxidative stress, endothelial activation, and inflammatory pathways, supporting the translational relevance of endothelial redox signaling in TTS. Conclusion This study identifies endothelial p22phox-dependent NADPH oxidases as critical determinants of catecholamine-induced apical LV dysfunction. Human plasma proteomic signatures implicating adrenergic, cAMP/PKA, oxidative stress, and inflammatory pathways support endothelial redox dysregulation as a central mechanism of regional myocardial vulnerability in TTS. Apex-specific SGLT2 upregulation downstream of endothelial NADPH oxidases highlights redox-responsive metabolic remodeling in stress-induced heart failure.