Roles of mitofusin-2 in mouse neutrophil adhesion and development

Neutrophils play a critical role in inflammation and innate immunity. A crucial step in neutrophil recruitment is their adhesion to vascular endothelium. Previous research demonstrated the necessity of mitofusin-2 (MFN2) for integrin activation, adhesion, and the development of neutrophil-like HL60 cells. However, it remains unknown whether this holds true for primary neutrophils. Additionally, neutrophil adhesion is closely associated with their development, making it challenging to independently investigate the roles of MFN2 in regulating mouse neutrophil adhesion and development. In this study, we successfully addressed these challenges by utilizing two distinct conditional knockout mouse models. Our findings revealed that blood neutrophils from MFN2 flox/flox LysM-cre mice exhibited approximately a 50% reduction in MFN2 expression. Remarkably, these MFN2 knockdown (KD) mice did not display any defects in neutrophil development. In contrast, blood neutrophils from MFN2 flox/flox Vav-iCre mice showed a substantial (>90%) reduction in MFN2 expression. These MFN2 knockout mice exhibited a notable defect in the maturation of band cells into polymorphonuclear neutrophils. We further investigated the neutrophil adhesion using MFN2 knockdown mice and identified the neutrophil adhesion defect using microfluidics, the integrin activation defect using soluble ligand binding, and the Ca 2+ flux defect using time-lapse flow cytometry. These findings provide valuable insights into the role of MFN2 in leukocyte adhesion and development and offer potential new perspectives for understanding and treating MFN2-deficiency-related diseases. This research was supported by grants from the National Institutes of Health, National Heart, Lung, and Blood Institute, USA (R01HL145454), National Institute of General Medical Sciences (R35GM119787), National Institute on Aging (P30AG024832), a Career re-entry fellowship from the American Association of Immunologists (G602182), and a startup fund from UConn Health. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.