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Dai Y, Gao C, Chen L, Chang W, Yu W, Ma X, Li J. Heterogeneous Vancomycin-Intermediate Staphylococcus aureus Uses the VraSR Regulatory System to Modulate Autophagy for Increased Intracellular Survival in Macrophage-Like Cell Line RAW264.7. Front Microbiol 2019; 10:1222. [PMID: 31214151 PMCID: PMC6554704 DOI: 10.3389/fmicb.2019.01222] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2019] [Accepted: 05/16/2019] [Indexed: 12/14/2022] Open
Abstract
The VraSR two-component system is a vancomycin resistance-associated sensor/regulator that is upregulated in vancomycin-intermediate Staphylococcus aureus (VISA) and heterogeneous VISA (hVISA) strains. VISA/hVISA show reduced susceptibility to vancomycin and an increased ability to evade host immune responses, resulting in enhanced clinical persistence. However, the underlying mechanism remains unclear. Recent studies have reported that S. aureus strains have developed some strategies to survive within the host cell by using autophagy processes. In this study, we confirmed that clinical isolates with high vraR expression showed increased survival in murine macrophage-like RAW264.7 cells. We constructed isogenic vraSR deletion strain Mu3ΔvraSR and vraSR-complemented strain Mu3ΔvraSR-C to ascertain whether S. aureus uses the VraSR system to modulate autophagy for increasing intracellular survival in RAW264.7. Overall, the survival of Mu3ΔvraSR in RAW264.7 cells was reduced at all infection time points compared with that of the Mu3 wild-type strain. Mu3ΔvraSR-infected RAW264.7 cells also showed decreased transcription of autophagy-related genes Becn1 and Atg5, decreased LC3-II turnover and increased p62 degradation, and fewer visible punctate LC3 structures. In addition, we found that inhibition of autophagic flux significantly increased the survival of Mu3ΔvraSR in RAW264.7 cells. Together, these results demonstrate that S. aureus uses the VraSR system to modulate host-cell autophagy processes for increasing its own survival within macrophages. Our study provides novel insights into the impact of VraSR on bacterial infection and will help to further elucidate the relationship between bacteria and the host immune response. Moreover, understanding the autophagic pathway in vraSR associated immunity has potentially important implications for preventing or treating VISA/hVISA infection.
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Affiliation(s)
- Yuanyuan Dai
- Department of Infectious Diseases, First Affiliated Hospital of Anhui Medical University, Hefei, China.,Department of Clinical Laboratory, First Affiliated Hospital of University of Science and Technology of China, Hefei, China
| | - Caihong Gao
- Department of Infectious Diseases, First Affiliated Hospital of Anhui Medical University, Hefei, China.,Department of Clinical Laboratory, First Affiliated Hospital of University of Science and Technology of China, Hefei, China
| | - Li Chen
- Department of Clinical Laboratory, First Affiliated Hospital of University of Science and Technology of China, Hefei, China
| | - Wenjiao Chang
- Department of Clinical Laboratory, First Affiliated Hospital of University of Science and Technology of China, Hefei, China
| | - Wenwei Yu
- Department of Clinical Laboratory, First Affiliated Hospital of University of Science and Technology of China, Hefei, China
| | - Xiaoling Ma
- Department of Clinical Laboratory, First Affiliated Hospital of University of Science and Technology of China, Hefei, China
| | - Jiabin Li
- Department of Infectious Diseases, First Affiliated Hospital of Anhui Medical University, Hefei, China.,Anhui Center for Surveillance of Bacterial Resistance, Hefei, China.,Department of Infectious Diseases, Chaohu Hospital of Anhui Medical University, Hefei, China
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Regulation of saeRS, agrA and sarA on sasX Expression in Staphylococcus aureus. Jundishapur J Microbiol 2018. [DOI: 10.5812/jjm.13821] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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