Staphylococcus aureus-induced proteomic changes in the mammary tissue of rats: A TMT study

Staphylococcus aureus is one of the most important pathogens causing mastitis in dairy cows. The objective of this study was to establish a rat mastitis model induced by a S.aureus infection and to explore proteins that change in proteomes of mammary tissue in different udders states,which provided a better understanding of the host immune response to S. aureus mastitis. Six 72 h postpartum rats were randomly divided into two groups (n=3), with either 100 µL of PBS (blank group) or a S. aureus suspension containing 2×107 CFU·ml−1 (challenge group) infused into the mammary gland duct,respectively. After 24 h of infection, the rats were sacrificed, and mammary gland tissue was collected. A tandem mass tag (TMT)-based technology was applied to compare the proteomes of healthy and mastitic mammary tissue. Compared with the control group, the challenge group had 555 proteins with significant differences in expression, of which 428 were significantly up-regulated (FC>1.2 and p<0.05) and 127 were down-regulated (FC>0.83 and p<0.05 or p<0.01). Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses revealed that up-regulated differentially significant expressed proteins (DSEPs) were associated with mainly immune responses,including integrin alpha M,inter-α-trypsin inhibitor heavy chain 4,alpha-2-macroglobulin.