Relationship between TIPE2 and caspase-11 during pyroptosis in macrophages of mice

Abstract

Objective To evaluate the relationship between tumor necrosis factor-alpha-induced protein 8-like 2 (TIPE2) and caspase-11 during pyroptosis in macrophages of mice. Methods J774A.1 macrophages of mice were divided into 4 groups (n=6 each) using a random number table method: non-specific siRNA (Scr-siRNA) group (S group), Scr-siRNA plus LPS/ATP group (S+ LPS/ATP group), TIPE2-siRNA group (T group) and TIPE2-siRNA plus LPS/ATP group (T+ LPS/ATP group). The corresponding siRNA and Lipofectamine2000 transfection reagents were added to each group, and transfection was performed for 24-48 h, and in addition LPS 1.0 μg/ml was then added, cells were incubated for 5 h, then ATP 5.0 mmol/L was added, and cells were incubated for 1 h in S+ LPS/ATP and T+ LPS/ATP groups.Cells were collected to detect the expression of TIPE2, caspase-11, NOD-like receptor familypyrin domain containing 3 (NLRP3) and caspase-1 (by Western blot). The supernatant was collected for determination of lactic dehydrogenase (LDH) and myeloperoxidase (MPO) activities and concentrations of interleukin-1beta (IL-1β) and IL-18 (by enzyme-linked immunosorbent assay). Results Compared with group S, the expression of TIPE2 was significantly down-regulated, the expression of caspase-11, NLRP3 and caspase-1 was up-regulated, and the activities of LDH and MPO and concentrations of IL-1β and IL-18 in supernatant were increased in group S+ LPS/ATP (P<0.05). Compared with group T, the expression of TIPE2 was significantly down-regulated, the expression of caspase-11, NLRP3 and caspase-1 was up-regulated, and the activities of LDH and MPO and concentrations of IL-1β and IL-18 in supernatant were increased in group T+ LPS/ATP (P<0.05). Compared with group S+ LPS/ATP, the expression of TIPE2 was significantly down-regulated, the expression of caspase-11, NLRP3 and caspase-1 was up-regulated, and and the activities of LDH and MPO and concentrations of IL-1β and IL-18 in supernatant were increased in group T+ LPS/ATP (P<0.05). Conclusion TIPE2 inhibits pyroptosis in macrophages through down-regulating the expression of caspase-11 in mice. Key words: Pyroptosis; Macrophages; Caspases; TIPE2