# SELENOF Mitigates Bovine Mastitis by Preserving Mitochondrial Homeostasis and Suppressing NLRP3-Mediated Pyroptosis

## TL;DR

This study shows that Selenoprotein F protects cow mammary cells from mastitis by maintaining mitochondria health and reducing inflammation.

## Contribution

The study identifies Selenoprotein F as a novel target for mitigating bovine mastitis through mitochondrial preservation and suppression of pyroptosis.

## Key findings

- SELENOF overexpression restores mitochondrial membrane potential and reduces inflammation in mastitis-affected cells.
- SELENOF suppresses NLRP3-mediated pyroptosis by inhibiting caspase-1/GSDMD-N pathway activation.
- SELENOF is significantly downregulated in mastitic tissue, linking its deficiency to disease progression.

## Abstract

Bovine mastitis is a common and costly inflammatory disease in dairy cows that damages mammary tissue and reduces milk production. This study investigated how a protein called Selenoprotein F helps protect cow mammary cells from this disease. The researchers examined tissue samples from cows with mastitis and found severe cell damage, inflammation, and a specific type of cell death called pyroptosis. They also discovered that Selenoprotein F levels were significantly lower in diseased tissue. Using laboratory cell experiments, the team showed that increasing Selenoprotein F levels could repair damaged mitochondria (the cell’s energy centers) and reduce harmful inflammation. These results point to Selenoprotein F as an important defender against mastitis, highlighting its potential to shield dairy cows from this damaging inflammatory condition. This discovery opens the door to a novel nutritional approach for safeguarding cattle health, which could in turn help curb the heavy reliance on antibiotics within the dairy sector.

Bovine mastitis threatens the dairy industry with limited effective therapies. The selenoprotein family offers potential anti-inflammatory interventions, yet the role of Selenoprotein F (SELENOF) remains unclear. This study investigated SELENOF in mitochondrial damage and pyroptosis using clinical mammary biopsies and a Staphylococcus aureus-induced Mammary alveolar cell-type T (MAC-T) cell model. Histology, TEM, immunofluorescence, Western blot, qPCR, RNA-seq, and mitochondrial staining (MitoTracker Red and JC-1) were employed. Mastitic mammary tissue exhibited severe architectural disruption, including focal necrosis with coalescing vacuoles of variable size, extensive epithelial denudation, and interstitial thickening with dense inflammatory infiltrates. At the ultrastructural level, mitochondrial swelling, cristae loss, and plasma membrane rupture were evident. Additionally, these tissue specimens exhibited marked upregulation of inflammatory mediator transcripts, notably IL-1β, IL-6, and TNF-α, alongside heightened abundance of pyroptosis-associated proteins including NOD-like receptor family pyrin domain containing 3 (NLRP3), cleaved caspase-1, and GSDMD-N (Gasdermin D N-terminal domain). RNA-seq identified SELENOF as significantly downregulated. The MAC-T model recapitulated the mitochondrial dysfunction, inflammatory response, and pyroptosis observed in mastitic tissue. SELENOF overexpression restored mitochondrial membrane potential, dampened the output of inflammatory signaling molecules, and suppressed NLRP3-mediated pyroptosis via attenuation of caspase-1/GSDMD-N pathway activation. These findings establish SELENOF as a novel target that mitigates bovine mastitis by preserving mitochondrial homeostasis and suppressing NLRP3-mediated pyroptosis.