HMOX1-mediated ferroptosis participates in gangrenous mastitis in dairy goats

Gangrenous mastitis is a severe disease caused by bacterial infection. It can lead to sepsis and even death in affected goats, posing a significant threat to the development of the dairy goat industry. The pathogenesis of this disease is not fully understood. In this study, a Staphylococcus aureus isolate obtained from a goat with gangrenous mastitis was used to establish in vivo and in vitro models. Using omics sequencing and detection of iron, MDA, GSH, and ROS levels, along with RT-qPCR and western blot, the occurrence of ferroptosis was assessed. Furthermore, by employing ferrostatin-1 (Fer-1), siRNA to inhibit HMOX1, and mitochondrial division inhibitor-1 (Mdivi-1), we explored the role of HMOX1 in regulating ferroptosis and the inflammatory response, as well as its association with mitophagy. The results showed the gangrenous mastitis model had typical symptoms, including mammary gland cyanosis, and bloody milk. Gene Set Enrichment Analysis (GSEA) revealed significant enrichment of the ferroptosis pathway, with HMOX1 being the most differentially expressed gene. Both gangrenous mastitis tissues and goat mammary epithelial cells infected with Staphylococcus aureus showed ferroptosis features, such as iron, MDA, and ROS accumulation, GSH depletion, and upregulation of HMOX1, along with downregulation of GPX4 and SLC7A11, while Fer-1 reversed these processes. Mitophagy-related proteins BNIP3, FUNDC1, and LC3 were upregulated, while Mdivi-1 inhibited them and alleviated ferroptosis. Inhibiting HMOX1 reduced ferroptosis, mitophagy and reduced inflammation. This study demonstrated that HMOX1 drives ferroptosis via mitophagy, providing new insights into the disease's pathogenesis and potential treatment strategies.