Fig. 4

TRQ protects mouse hippocampal neuronal HT22 cells by decreasing IL1B from DENV-2-stimulated BV2 cells. A, B DENV-2 shows no obvious toxicities in HT22 cells. HT22 cells were incubated with DENV-2 for 24, 36 or 48 h and then examined by CCK-8 (A) and LDH (B) assays. C Steps of adoptive culture. BV2 cells were infected with DENV-2 (0.5 MOI or 5 MOI) in the presence or absence of TRQ for 24 h. Then, HT22 cells were incubated with cell-free supernatants from BV2 cells for 24 or 48 h. D, E TRQ protects HT22 cells from DENV-2-stimulated BV2 cells supernatants induced death. After adoptive culture, the morphological change and the cell viability of HT22 cells were examined by microscopy (40 ×) (D) and CCK-8 assay (E). F TRQ inhibits apoptosis in HT22 cells induced by supernatants from DENV-2-stimulated BV2 cells. After adoptive culture, the number of apoptotic HT22 cells was analyzed by PI/Annexin V-FITC staining. G–I IL1B counteracts the protective effect of TRQ. BV2 cells were infected with DENV-2 (0.5 MOI) in the presence or absence of TRQ for 24 h. Then, HT22 cells were incubated with cell-free supernatants from BV2 cells in the presence or absence of IL1B for 48 h. Morphological observation of cell viability and apoptosis of the HT22 cells were performed by microscopy (40 ×) (G), CCK-8 assay (H) and PI/Annexin V-FITC staining (I). ^***P < 0.001 vs. control group, ^##P < 0.01, ^###P < 0.001 vs. DENV-2 group, ^$$$P < 0.001 vs. DENV-2 + TRQ group, ⁺⁺⁺P < 0.001 vs. DENV-2 + TRQ + IL1B group