Staphylococcus aureus (S. aureus) is one of the main pathogens causing
mastitis in dairy cows. The current work mainly focuses on the pathway of apoptosis induction in MAC-T cells caused by S. aureus
infection or other factors. However, the physiological characteristics of S. aureus infected MAC-T cells and the resulting
mRNA expression profile remain unknown particularly in the case of diverse drug resistant strains. Methicillin-resistant S. aureus (MRSA) and
methicillin-susceptible S. aureus (MSSA) strains were used to infect MAC-T cells to investigate this issue. The adhesion, invasion and apoptosis ability of MRSA-infected group and MSSA-infected group was assessed over time (2, 4, 6, 8, and 12 h). After 8 h, the
RNA sequencing was conducted on the MRSA-infected and the MSSA-infected with uninfected MAC-T cells as controls. The results showed that the adhesion and invasion ability of MRSA-infected and MSSA-infected to MAC-T cells increased and then decreased with
infection time, peaking at 8 h. The adhesion and invasion rates of the MSSA-infected were substantially lower than those of the MRSA-infected, and the invasion rate of the MSSA-infected group was nearly non-existent. Then the apoptosis rate of MAC-T cells increased as the
infection time increased. The transcriptome analysis revealed 549 differentially expressed mRNAs and 390 differentially expressed mRNAs in MRSA-infected and MSSA-infected MAC-T cells, respectively, compared to the uninfected MAC-T cells. According to GO analysis, these differentially expressed genes were involved in immune response,
inflammation, apoptosis, and other processes. The Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis indicated the following pathways were linked to adhesion, invasion
inflammation and apoptosis, including AMPK, FOXO, HIF-1,
IL-17, JAK-STAT, MAPK, mTOR, NF-κB, p53, PI3K-Akt, TNF,
Toll-like receptor, Rap1, RAS,
prion disease, the bacterial invasion of epithelial cells pathway. We found 86 DEGs from 41 KEGG-enriched pathways associated with adhesion, invasion, apoptosis, and
inflammation, all of which were implicated in MAC-T cells resistance to MRSA and MSSA
infection. This study offers helpful data toward understanding the effect of different drug-resistant S. aureus on dairy cow mammary epithelial cells and aid in the prevention of
mastitis in the dairy industry.