To investigate the effects of caspase-11 non-canonical inflammasome on the Leptospira interrogans (L.interrogans)-induced secretion of inflammatory cytokines in J774A.1 cells.

Murine mononuclear macrophage cells (J774A.1) were infected with L. interrogans strain 56601. Expression of caspase-11, IL-1β, IL-1α and IL-18 at mRNA level in J774A.1 cells were detected by real-time RT-PCR. The levels of caspase-11, IL-1β, IL-1α and IL-18 in the culture supernatants of J774A.1 cells were detected by ELISA.

Real-time RT-PCR showed that caspase-11 expression at mRNA level was 5.12, 14.21, 8.94, 14.06, 18.58 and 0.93 times of that in uninfected cells after 1, 2, 4, 8, 12 and 24 h of L. interrogans infection, and respectively decreased to 0.10, 0.07, 0.10, 0.09, 0.07 and 0.45 times after caspase-11 inhibitor intervention (P<0.05). Expression of IL-1β, IL-1α and IL-18 at mRNA level was significantly increased after infection (P<0.05). After the intervention with caspase-11 inhibitor, IL-1β mRNA decreased to 0.05, 0.03, 0.02, 0.05, 0.06 and 0.02 times (P<0.05); IL-1α mRNA decreased to 0.14, 0.07, 0.15, 0.10, 0.03 and 0.06 times (P<0.05); IL-18 mRNA decreased to 0.08, 0.10, 0.16, 0.18, 0.10 and 0.07 times (P<0.05). ELISA results showed that the expression of caspase-11, IL-1β, IL-1α and IL-18 at protein level was significantly increased. After the intervention with caspase-11 inhibitor, caspase-11 level decreased to 43.07, 41.64, 51.96, 86.56, 105.36, and 129.95 pg/ml (P<0.05); IL-1β level decreased to 15.01, 14.19, 68.02, 31.20, 173.13 and 104.98 pg/ml (P<0.05); IL-1α level decreased to 12.14, 15.40, 38.01, 21.97, 24.48 and 27.09 pg/ml (P<0.05); IL-18 level decreased to 96.27, 102.21, 85.34, 116.28, 155.36 and 114.03 pg/ml (P<0.05).

Caspase-11 non-canonical inflammasome was involved in the mediation of IL-1β, IL-1α and IL-18 secretion in mouse mononuclear macrophages after L. interrogans infection.

Leptospira interrogans; Caspase-11 non-canonical inflammasome; Inflammatory cytokine; Macrophage; Gene silencing