Objective: To investigate the c-Jun N-terminal kinase (JNK), CCAAT/enhancer-binding protein homologous protein (CHOP) pathway apoptosis and the changes of cytokine levels in immune-related organs and tissues of sepsis mice at different time points.
Methods: Twenty-seven male BALB/c mice were divided into normal group, sepsis 6 hours group and sepsis 12 hours group by the block randomization method, with 9 mice in each group. The sepsis model was made by cecal ligation and puncture (CLP). Blood sample was collected from each group at the corresponding time point, and the serum levels of tumor necrosis factor-α (TNF-α), interleukin (IL-1β, IL-10) were measured by enzyme linked immunosorbent assay (ELISA). The spleen, thymus and appendix tissues were taken from the mice to detect the expressions of phosphorylation-JNK (p-JNK), JNK1, CHOP and cleaved caspase-3 protein by Western Blot.
Results: The level of cytokines, p-JNK/JNK1 ratio, CHOP and caspase-3 in spleen tissues, and the CHOP, caspase-3 in thymus and appendix tissue in the sepsis 6 hours group were significantly higher than those in the normal group [serum TNF-α (ng/L): 24.29±3.09 vs. 2.93±2.09, serum IL-1β (ng/L): 5.00±3.19 vs. 3.54±1.53, serum IL-10 (ng/L): 1 963.93±270.20 vs. 275.09±45.21, spleen p-JNK/JNK1 ratio: 0.257±0.126 vs. 0.154±0.068, spleen CHOP/β-actin: 0.201±0.131 vs. 0.142±0.068, spleen caspase-3/β-actin: 0.215±0.126 vs. 0.098±0.088, thymus CHOP/β-actin: 0.122±0.071 vs. 0.089±0.067, thymus caspase-3/β-actin: 0.258±0.145 vs. 0.108±0.045, appendix CHOP/β-actin: 0.361±0.134 vs. 0.215±0.112, appendix caspase-3/β-actin: 0.439±0.211 vs. 0.321±0.145, all P < 0.05]. However, there were no significant difference in the p-JNK/JNK1 ratio in thymus and appendix (thymus p-JNK/JNK1 ratio: 1.221±0.776 vs. 1.168±0.475, appendix p-JNK/JNK1 ratio: 2.014±1.227 vs. 1.828±0.915, both P > 0.05). Cytokine levels and the p-JNK/JNK1 ratio, CHOP, caspase-3 in spleen, thymus, and appendix in the sepsis 12 hours group were further increased when compared with those in the sepsis 6 hours group, except for a significant decrease in IL-10 level [serum IL-10 (ng/L): 1 698.98±210.52 vs. 1 963.93±270.20, serum TNF-α (ng/L): 41.66±6.57 vs. 24.29±3.09, serum IL-1β (ng/L): 10.37±4.14 vs. 5.00±3.19, spleen p-JNK/JNK1 ratio: 0.399±0.135 vs. 0.257±0.126, spleen CHOP/β-actin: 0.298±0.145 vs. 0.201±0.131, spleen caspase-3/β-actin: 0.353±0.145 vs. 0.215±0.126, thymus p-JNK/JNK1 ratio: 1.667±0.891 vs. 1.221±0.776, thymus CHOP/β-actin: 0.207±0.133 vs. 0.122±0.071, thymus caspase-3/β-actin: 0.416±0.179 vs. 0.258±0.145, appendix p-JNK/JNK1 ratio: 2.425±1.361 vs. 2.014±1.227, appendix CHOP/β-actin: 0.456±0.189 vs. 0.361±0.134, appendix caspase-3/β-actin: 0.635±0.289 vs. 0.439±0.211, all P < 0.05].
Conclusions: The endoplasmic reticulum pathway JNK and CHOP pathways are involved in immune-related cell apoptosis and cytokine expression in mice with sepsis. Apoptosis is more obvious at 12 hours than at 6 hours, and the inflammatory response is stronger.