Establishment of a Burkholderia thailandensis invaded RAW264.7 cell model and underlying mechanism of infection

Abstract

Objective To establish a cell model of Burkholderia thailandensis (B. thailandensis, our isolated strain was named as BPM) infecting RAW264.7 cells in order to lay a foundation for further study on its pathogenic mechanism. Methods The bacterial solution containing same concentration of BPM was prepared to infect RAW264.7 cells with different diluted concentrations. The bacterial entry rate and intracellular survival status were analyzed by the bacterial uptake rate of BPM in RAW264.7 cells at different infection phases. The intracellular infection of bacteria and the ultra-structural pathological changes of host cells were dynamically observed by transmission electron microscopy (TEM) and Giemsa staining. The apoptosis induced by different phase points was detected by flow cytometry. The expression of inflammatory factors in cell supernatant was detected by LEGENDplexTM reagent. Results TEM displayed that some bacteria invaded into the cells 12 h after infection. The formation of typical multinucleate giant cells (MNGC) was observed at the earliest 8 h after BPM infection by Giemsa staining. With the elapse of infection time, MNGC formation rate and inflammatory factor expression were gradually increased. Conclusion The intracellular infection model of BPM is successfully constructed, and the inflammatory response of B. thailandensis infection in host cells is clarified, laying the experimental foundation for further study of the mechanism of B. thailandensis infection.

Keywords

• burkholderia thailandensis
• raw264.7 cells
• cell model
• inflammatory factors
• infection mechanism