Effects of lipopolysaccharides in different concentrations on the proliferation and interleukin-6, interleukin-1β and tumor necrosis factor-α secretion of intestinal epithelial cell of rats in vitro

Objective To investigate the effects of lipopolysaccharides(LPS) in different concentrations on the proliferation and interleukin(IL)-6, IL-1β and tumor necrosis factor-α(TNF-α) secretion of intestinal epithelial cells(IEC-6) of rats in vitro. Methods IEC-6 of rats were divided into normal group(0 mg/L, group A), 0.1 mg/L group(group B), 0.5 mg/L group(group C), 1.0 mg/L group(group D), 5.0 mg/L group(group E) and 10.0 mg/L group(group F). Different groups cells were exposed to LPS with different concentrations for 3 h, 5 h and 7 h. Thiazolyl blue(MTT)was performed to investigate the proliferation of IEC-6.The concentrations of IL-6, IL-1β and TNF-α in culture supernatant were detected by enzyme linked immunosorbent assay(ELISA). Results The proliferation rate of IEC-6 was gradually lower while the concentration of LPS increased.After co-culture with LPS 3 h and 5 h, the proliferation rates of group B, group C, group D, group E and group F had no significant difference with those of group A(all P>0.05); after co-culture with LPS 7 h, the proliferation rates of group B, group C, and group D had no significant difference with those of group A(all P>0.05); the proliferation rates of group E and group F had significant difference with those of group A(t=4.216, P=0.014; t=14.991, P=0.000). The proliferation rates of group E and group F were lower after co-culture with LPS 5 h than 7 h, and there were significant differences(t=2.576, P=0.033; t=2.975, P=0.018); but there was no significant differences between group E and group A after co-culture with LPS 5 h(P>0.05). Group B, group C, group D, group E and group F all had a significant higher level of IL-6 than group A after co-culture with LPS 3 h, 5 h and 7 h(all P 0.05). Conclusions In a certain concentration, incubation time range, the proliferation rates of IEC-6 cells were gradually lower while the concentration of LPS increased.Co-cultured IEC-6 cells with LPS(0-10.0 mg/L) can stimulate them secrete to IL-6.The highest level of IL-6 was of group E after 5 h co-culture.LPS had no effects on TNF-α and IL-1β level of IEC-6 cells cultural supernatant.So 5.0 mg/L concentration of LPS stimulating IEC-6 cells for 5 h can be chosen to build the IEC-6 inflammatory models. Key words: Intestinal epithelial cell; Rat; Lipopolysaccharide; Interleukin-6; Interleukin-1β; Tumor necrosis factor-α; Cell proliferation