Effect of Xuebijing injection on lipopolysaccharide-induced apoptosis of CD4+ CD25+ regulatory T cells and immune function of effector T cells in vitro.

Abstract

Objective To investigate the effect of Xuebijing injectiong on lipopolysaccharide(LPS)-induced apoptosis of CD4+CD25+regulatory T cells(Tregs)and immune function of effector T cells(Teff)in vitro.Method CD4+CD25+Tregs isolated from rat spleens were divided into the control group,anti-CD3/CD28 group,anti-CD3/CD28+LPS group,anti-CD3/CD28+Xuebijing injection group,and anti-CD3/CD28+LPS+Xuebijing injection group.The apoptosis rate and expression of forkhead/winged helix transcription factor p3 (Foxp3)and cytotoxic T-lymphocyte-associated antigen 4(CTLA-4)of CD4+CD25+Tregs were detected by flow cytometry(FCM),and the secretion of IL-10 of Tregs was measured by ELBA on day 3.CD4+CD25-T cells were co-cultured with CD4+CD25+Tregs(1:1)for 68 hours,proliferative activity of Teff was determined by MTT,and interleukin(IL)-2/sIL-2Rα levels were measured by ELISA.Results The apoptosis rate of CD4+CD25+Tregs in anti-CD3/CD28 group was 33.70± 3.06%,which was significantly higher than that in control group(12.84±0.84%).Also,apoptosis rate of CD4 CD25+Tregs in anti-CD3/CD28+LPS+Xuebijing injection group(45.13±2.70%)was much higher than that in anti-CD3/CD28+IPS group(29.41 ± 1.63%,P＜0.01).The expression of Foxp3 as well as CTLA-4,and the secretion of IL-10 were markedly decreased along with increases in the apoptosis rates.Compared with control group(54.48%),the mean inhibitory rate of Teff proliferative activity in response to Con A was significantly decreased in anti-CD3/CD28+Xuebijing injection group(31.26%,P＜0.05),and it was markedly decreased in anti-CD3/CD28+LPS+Xuebijing injection group comaped to anti-CD3/CD28+LPS group(P＜0.01).In addition,IL-2 levels in the supernatant of anti-CD3/CD28+Xuebijing injection group and anti-CD3/CD28+LPS+Xuebijing injection group were significantly higher than those of anti-CD3/CD28+IPS group(P＜0.01).Conclusions The inhibitory activity of CD4+CD25+Tregs on Teff appears to be upregulated by IPS stimulation in vitro,and Xuebijing injection could markedly enhance apoptosis of CD4+CD25+Tregs,thereby improving suppressive immune function of Teff. Key words: Sepsis; Regulatory T cells; Effector T cells; Apoptosis; Xuebijing injection