Study of curcumin up-regulating mitofusion2 for inhibiting lymphocytes apoptosis of septic mice

Abstract

Objective To investigate the effect and mechanism of curcumin oninhibiting lymphocyte apoptosis of septic mice. Methods Forty-five male BALB/c mice of clean grade were randomly (raudom number)divided into three groups: sham operation group (n=15), sepsis model group (n=15) and curcumin treatment group (n=15). The experiment was repeated 3 times. Mice in sepsis group were made to be sepsis models by cecal ligation and puncture (CLP) and lavaged the stomach with normal saline (NS) once a day for a week before operation.In curcumin group, mice dealt with CLP were given curcumin once a day for a week in dose of 200 mg/kg before operation. Mice in sham group were only dealt with open abdominal without ligation and puncture, and equal volumes NS was given instead for a week before surgery. The mortality of mice in each group were calculated 24 h after operation and all the survived mice were sacrificed for getting spleen lymphocytes. Apoptosis of lymphocytes were detected by flow cytometry and TUNEL; mitochondrial membrane potential was detected by flow cytometry; Mitofusion2 (Mfn2), Bax (pro-apoptotic protein, promotion of cell death), Bcl-2 (B-cell lymphoma-2, anti-apoptotic protein, prevention of cell death) were detected by Western blot.Data were analyzed by SPSS 18.0. Chisquare test was used to analyzed the counting data, and the measurement data were analyzed by using One-way analysis of variance (ANOVA). Results The mortality rate of mice in sepsis group was higher than that in sham group (46.7%vs. 0.00%, P<0.01), curcumin obviously reduced the death rate compared with sepsis group (40.0%vs. 46.7%, P=0.01). Sepsis group demonstrated a significant increase in lymphocytes apoptosis compared with sham group [(17.1±1.67)%vs. (9.43±1.06)%, P<0.01] , which was dramatically reduced by cureumin dealt with [(12.70±1.25)%vs. (17.1±1.67)%, P=0.012]. Meanwhile, the reduction rate of mitochondrial membrane potentials in sepsis group was more noticeable than that in sham group [(45.13±4.14)%vs. (21.63±1.62), P<0.01], which was significantly decreased by curcumin protection [(29.67±2.15)%vs. (45.13±4.14)%, P=0.001]. The expressions of Bax in cytoplasm in sepsis group significantly decreased compared with sham group (P<0.01) and the expression of Bax in plastosome increased (P=0.001). Pretreatment with curcumin obviously up-regulated (P<0.01) the levels of Bax in cytoplasm and down-regulated (P=0.02) the levels in plastosome. Compared with sham group, the expression of Mfn2 (P=0.015) and Bcl-2 (P=0.01) in sepsis group reduced, and when pretreatment with curcumin, the Mfn2(P=0.002) and Bcl-2(P=0.001) protein levels significantly increased. Conclusions Cureumin can obviously raise the protein level of Mfn2, promote the mitochondria fusion and then suppress the spleen lymphocyte apoptosis of septic mice. Key words: Curcumin; Sepsis; Mice; Lymphocyte; Apoptosis; Mitochondria; Mitofusion2; Mitochondria fusion