Observation for the process of Vibrio vulnificus inducing dendritic cell apoptosis

Objective To observe the process of Vibrio vulnificus inducing dendritic cell strain apoptosis.Methods We established the mixed culture model of mouse dendritic cell ( DC 2.4 strain) and Vibrio vulnificus( Vv1.1758 strain ),analyzed morphological characteristics of cell apoptosis by DAPI fluorescence staining,detect DNA fragmentation level of apoptosis cells by DNA Ladder assay,analyze DC2.4 apoptosis rate by Annexin V FITC/PI staining,determine activities of caspase-3 and caspase-8 by means of spectrophotometric method and detect changes of mitochondrial transmembrane potential ( △ Ψm ) by JC-1 fluorescence labeling.Results After Vv1.1758 strain and DC2.4 cell were mixed and cultured for 4 h,DAPI fluorescence staining showed typical apoptosis characteristics-chromatin condensation and marginalization; DNA agarose gel electrophoresis showed apoptosis band; apoptosis rates at 2,4 and 6 h were respectively (37.8±9.8) ％,(54.3 ± 12.7 ) ％ and ( 68.2± 14.6 ) ％ ; Mitochondrial transmembrane potentials (△Ψm) at 1 h,2 h and 4 h reduced by 7.1％,16.1％ and 46.7％ respectively; caspase-8 activity increased at 1.5 h and reached the peak at 2 h [ (2.48±0.19) U/μg],while caspase-3 activity started to increase at 3h and reached the peak at 4 h [ ( 1.91 ±0.16) U/μg ].Conclusion Vibrio vulnificus could induce dendritic cells by two pathways: reducing mitochondrial transmembrane potential and activating caspase-8 promoter and finally activate effector caspase-3 to promote apoptosis. Key words: Vibrio vulnificus (Vv); Dendritic cells ( DC ); Apoptosis; Mitochondrial transmembrane potential(△Ψm); Cysteine aspartase family (caspase)