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Published on: March 28, 2017
Effect of Two Different Drug-Resistant Staphylococcus aureus Strains on the Physiological Properties of MAC-T Cells
Lijiao Yan1, Yuze Yang2, Xiaojun Ma1
1College of Veterinary Medicine, Gansu Agricultural University, Lanzhou, China.
Abstract:
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.
Insights
This study investigated how methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-susceptible S. aureus (MSSA) affect dairy cow mammary cells. MRSA showed higher adhesion and invasion, while both strains induced apoptosis and altered gene expression related to immune responses.
Area of Science:
- Bacteriology and Immunology
- Molecular Biology
- Dairy Science
Background:
- Staphylococcus aureus (S. aureus) is a primary cause of mastitis in dairy cows.
- Understanding the cellular and molecular responses of mammary epithelial cells to S. aureus infection, especially drug-resistant strains, is crucial for disease prevention.
- Previous research has focused on apoptosis pathways but lacked detailed physiological and transcriptomic profiles for diverse S. aureus strains.
Purpose of the Study:
- To investigate the physiological characteristics and mRNA expression profiles of MAC-T cells infected with methicillin-resistant S. aureus (MRSA) and methicillin-susceptible S. aureus (MSSA).
- To compare the adhesion, invasion, and apoptosis capabilities of MRSA and MSSA in MAC-T cells over time.
- To identify key molecular pathways and differentially expressed genes involved in the host response to S. aureus infection.
Main Methods:
- MAC-T cells were infected with MRSA and MSSA strains for 2, 4, 6, 8, and 12 hours.
- Adhesion, invasion, and apoptosis assays were performed to assess bacterial interaction and cell viability.
- RNA sequencing was conducted on infected and uninfected MAC-T cells at 8 hours post-infection, followed by Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses.
Main Results:
- Bacterial adhesion and invasion peaked at 8 hours, with MRSA exhibiting significantly higher rates than MSSA.
- Apoptosis in MAC-T cells increased with infection time for both strains.
- Transcriptome analysis identified 549 differentially expressed mRNAs in MRSA-infected cells and 390 in MSSA-infected cells, primarily involved in immune response, inflammation, and apoptosis pathways.
Conclusions:
- MRSA demonstrates greater adhesion and invasion capabilities compared to MSSA in MAC-T cells.
- Both MRSA and MSSA infections trigger significant changes in gene expression related to host defense mechanisms, including immune response and apoptosis.
- The study identified 86 differentially expressed genes across 41 KEGG pathways implicated in MAC-T cell resistance, providing insights into dairy cow mammary epithelial cell responses to S. aureus and aiding mastitis prevention strategies.
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