Sulfur Amino Acid Metabolism and the Role of Endogenous Cystathionine-gamma-lyase/H2S in Holstein Cows with Clinical Mastitis

Endogenous hydrogen sulfide (H2S) has been implicated in many physiological and pathological processes, particularly in inflammatory responses and adaptive immunity. In this study, we identified the candidate differentially expressed proteins (DEPs) associated with H2S metabolism in Holstein cows with clinical mastitis (CM). The results revealed 17 DEPs included in 44 Gene Ontology (GO) terms and five Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways related to sulfide metabolism and indicated the important role of cystathionine-gamma-lyase (CTH)/H2S in CM. Our findings can support research into the function and regulatory mechanism of CTH/H2S in Holstein cows and provide a basis for the prevention and treatment of CM. H2S plays an important role in various inflammatory diseases. However, the role of H2S 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-beta-synthase (CBS). Immunohistochemical and immunofluorescence staining results showed that CTH and CBS proteins were present mainly in the cytoplasm of mammary epithelial cells. Endogenous H2S 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 H2S were correlated with the occurrence and development of CM in Holstein cows, which provides important insights into the function and regulatory mechanism of CTH/H2S in Holstein cows.