Sulfur Amino Acid Metabolism and the Role of Endogenous Cystathionine-γ-lyase/H 2 S in Holstein Cows with Clinical Mastitis.

H 2 S plays an important role in various inflammatory diseases. However, the role of H 2 S and synthetic enzymes in Holstein cows with CM is unknown. The aim of this study was to identify DEPs associated with sulfide metabolism and further investigate their roles in dairy cows with CM. From 3739 DEPs generated by data-independent acquisition proteomics, we identified a total of 17 DEPs included in 44 GO terms and five KEGG pathways related to sulfide metabolism, including CTH and cystathionine-β-synthase (CBS). Immunohistochemical and immunofluorescence staining results showed that CTH and CBS proteins were present mainly in the cytoplasm of mammary epithelial cells. Endogenous H 2 S production in the serum of the CM group was significantly lower than that of the healthy Holstein cows. CTH and CBS mRNA and protein levels in the mammary glands of the CM group were significantly downregulated compared to those of the healthy group. These results indicate that CTH and H 2 S were correlated with the occurrence and development of CM in Holstein cows, which provides important insights into the function and regulatory mechanism of CTH/H 2 S in Holstein cows.