Effect of bilirubin on inflammatory signaling pathway mediated by NOD-like receptor 2 in premature infants / 中华实用儿科临床杂志

ABSTRACT

Objective@#To investigate the effect of bilirubin on inflammatory signaling pathway mediated by NOD-like receptor 2(NOD2) in premature infants.@*Methods@#Fifteen cases of premature infants hospitalized at the Department of Neonatology, Children′s Hospital of Soochow University from April 2016 to January 2017, were selected, and 2 mL peripheral blood were collected from 15 cases of premature infants, and the mononuclear cells were isolated and divided into 6 groups, including blank control group (group A), muramyl dipeptide(MDP) group (group B), 102 μmol/L bilirubin group(group C), 102 μmol/L bilirubin+ MDP group (group D), 153 μmol/L bilirubin+ MDP group (group E), 255 μmol/L bilirubin+ MDP group (group F). Group A and group B were stimulated by buffer, group C, group D, group E and group F were stimulated by 102 μmol/L, 102 μmol/L, 153 μmol/L, 255 μmol/L bilirubin, respectively.The supernatant was discarded after 1 h, then the medium was added to group A and group C, and the rest of the 4 groups were agonisted with MDP, the cells were stimulated for 24 h, and then the cells and supernatant fluids were collected respectively, the expression levels of NOD2 mRNA in the cells were determinated by real time-PCR, and the expression levels interleukin-6(IL-6) and tumor necrosis factor-α(TNF-α) in the supernatant was determinated by enzyme linked immunosorbent assay.@*Results@#The expression levels of NOD2 mRNA had no obvious changes after being stimulated by MDP or by different concentrations of bilirubin(7.16±3.08, 6.19±1.99, 7.02±4.04, 6.84±1.81) compared to those of the blank control group(7.46±3.70)(all P>0.05). After being stimulated by MDP, the expression level of IL-6 (5.13±2.36)was significantly higher than that of the blank control group(3.84±1.44), and the difference was statistically significant(P<0.05), but TNF-α had no obvious changes(4.85±2.47 vs.4.04±2.26, P>0.05). The expression levels of IL-6 and TNF-α had no obvious changes compared to those of the blank control group after being stimulated by 102 μmol/L bilirubin(3.26±1.06 vs.3.84±1.44, 3.45±1.84 vs.4.04±2.26, all P>0.05); but the expression levels of IL-6 and TNF-α were significantly lower after 153 μmol/L and 255 μmol/L bilirubin stimulation (IL-6 2.58±1.33, 2.16±0.94; TNF-α 2.32±1.49, 2.42±1.42)compared to those of the blank control group(3.84±1.44, 4.04±2.26), and the differences were statistically significant(all P<0.05).@*Conclusions@#Bilirubin have no obvious inhibitory effect on NOD2, and low concentration of bilirubin had no obvious inhibitory effect on IL-6 or TNF-α in this study, but high concentration of bilirubin can inhibit the expression levels of IL-6 and TNF-α, hyperbilirubin may inhibit the ability of anti-infection immune response in body by inhibiting inflammatory signaling pathway mediated by NOD2.