Knockout of p47phox inhibits deep vein thrombosis by regulating the PAC-1/FNG/MAC-1 signaling axis and ameliorating mitochondrial dysfunction.

OBJECTIVE: To elucidate the role and molecular mechanism of the NADPH oxidase key subunit p47phox in deep vein thrombosis (DVT) formation by investigating its regulatory effects on neutrophil extracellular traps (NETs) generation, the PAC-1/FNG/MAC-1 signaling axis, and endothelial mitochondrial function, thereby providing a theoretical basis for targeted therapeutic strategies. METHODS: Peripheral blood was collected from healthy volunteers and DVT patients to assess p47phox expression, NET-related markers, and coagulation parameters. A DVT model was established using p47phox gene knockout (p47phox-/-) mice and wild-type (WT) C57BL/6NJ mice to compare thrombus incidence, weight, and length. Platelets, neutrophils, and human umbilical vein endothelial cells (HUVECs) were isolated, and p47phox expression was experimentally manipulated. Flow cytometry was used to assess integrin αIIbβ3 activation (PAC-1 binding), MAC-1 activation levels, and ROS production. Western blot was used to analyze the expression of relevant signaling proteins and mitochondrial function proteins. Immunofluorescence was used to detect NET markers and the colocalization of PAC-1, FNG, and MAC-1. Assays for NETosis, coagulation function (prothrombin time [PT], activated partial thromboplastin time [APTT], tissue factor pathway inhibitor [TFPI], etc.), and adenosine triphosphate (ATP) production were performed for supplementary validation. RESULTS: p47phox-/- mice exhibited lower thrombus incidence, weight, and length compared to WT mice. DVT patients showed increased p47phox mRNA and protein expression in neutrophils. In p47phox-/- mice, histone H3-positive signals in thrombi were reduced, along with lower levels of plasma cell-free DNA (cfDNA), myeloperoxidase (MPO), and neutrophil elastase (NE); NET release upon phorbol 12-myristate 13-acetate (PMA) stimulation was also attenuated. Platelets from p47phox-/- mice exhibited reduced PAC-1 binding and fibrinogen (FNG) binding capacity, as well as decreased PAC-1-FNG-MAC-1 colocalization area and related signaling protein expression in thrombi. p47phox knockdown in HUVECs led to decreased ROS generation, accompanied by increased mitochondrial number, membrane potential, and ATP production. CONCLUSION: Systemic p47phox deficiency suppresses DVT formation by inhibiting the PAC-1/FNG/MAC-1 signaling axis, thereby affecting platelet-neutrophil interactions and NET generation, and by protecting endothelial cells through amelioration of ROS-mediated mitochondrial dysfunction. Although in vitro experiments suggest the involvement of these multicellular mechanisms, the specific contributions of individual cell types require further validation.