Fig. 4: Repression of caspase-1 activity in 5-FU-treated MDSC mediated by DHA exposure.

a Analysis of 5-FU-induced caspase-1 activity by FLICA in MSC-2 treated with 5-FU (1 µM) for 12 h ±DHA (20–60 µM) or oleic acid (OA). Error bars represent mean ± SD from three independent experiments. b Measure of caspase-1 activity by FLICA in MDSC (CD11b⁺ Gr-1⁺) purified 48 h after a single intraperitoneal injection of 5-FU (50 mg/kg) to EL4 tumor-bearing mice fed control (ctrl) or DHA-enriched diet. Error bars represent mean ± SEM. c, d Correlation between plasma DHA content before 5-FU therapy and ratio of caspase-1 activity (after (D1) and before (D0) 5-FU chemotherapy) in HLA-DR⁻ CD33⁺ CD14⁺ cells c or in HLA-DR⁻ CD33⁺ CD15⁺ cells d (n = 26 patients). e Effect of DHA on 5-FU induced caspase-1 activity in β-arrestin-2-silenced MDSC. MSC-2 with stable knockdown of β-arrestin-2 was obtained by transduction with β-arrestin-2 (ARRB2) shRNA lentiviral vector and compared to ctrl shRNA vector. Cells were treated with 5-FU (1 µM) ±DHA (60 µM) for 12 h and harvested for active caspase-1 analysis by FLICA. Error bars represent mean ± SD from three independent experiments. f Caspase-1 activity analyzed by FLICA in 5-FU-treated MSC-2 for 12 h ±JNK inhibitor SP600125 (4 and 10 µM). Error bars represent mean ± SD from four independent experiments. *p < 0.05; **p < 0.01; ***p < 0.001; ****p < 0.0001; ns nonsignificant