Expression of Toll-like receptor-2 in premature rats with necrotizing enterocolitis and regulatory effects of glutamine

Abstract

Objective To study the expression of Toll-like receptor-2 (TLR-2) and caspase-3 in the intestine of premature rats with necrotizing enterocolitis (NEC),and to explore the protective effects and possible regulatory mechanism of glutamine (Gln) in the NEC.Methods Sixty premature rats (gestational age 21 d) were divided into three groups (n = 20 each) according to the random number table: control group,model group and Gln intervention group.Rats in model group were given formula feeding,hypoxia and cold stress.Rats in Gln intervention group were given Gln 0.3 g/kg to the formula feeding,hypoxia and cold stress.All the premature rats were sacrificed and the intestine tissues were obtained on the third day after birth.The histological changes of ileal tissues were scored after HE staining.The expression of TLR-2 and caspase-3 in jejunum,ileum and colon were detected by inmunohistochemistry,and the expression of TLR-2 mRNA in jejunum,ileum and colon were detected by real-time fluorescence quantitative reverse transcription-polymerase chain reaction.Results Pathology score of ileum in model group,Gln intervention group and control group were 3.10 ±0.99,2.40 ± 0.69 and 0.30 ±0.48,respectively.The expressions of TLR-2 protein in ileum were 2.53±0.94,2.15±0.82 and 1.57 ± 0.62 in the three groups respectively,and the expression of caspase-3 protein were 2.83 ± 0.45,2.70 ± 0.04 and 0.91 ± 0.29.The content of TLR2 mRNA in model group was 1.46 times higher than that of Gln intervention group and was 2.10 times higher than that of control group.Compared with the control group,the pathology score,expression of TLR-2 and caspase-3 protein,and TLR-2 mRNA in model group were significantly higher,P＜0.01.However,compared with the model group,those changes were improved in Gln intervention group,P＜0.05.Expression of TLR-2 mRNA positively correlated to the expression of caspase-3 protein (r=0.71,P＜0.01) and pathology score (r = 0.69,P＜ 0.01).Expression of caspase-3 protein positively correlated to the intestine injury pathology score (r=0.81,P＜0.01).Conclusions TLR-2 may be involved in the pathogenesis of NEC.Gln might reduce the expression of TLR-2 in the intestine,and decrease the apoptosis of intestinal epithelial cells to protect the intestine of preterm birth rats. Key words: Enterocolitis,necrotizing; Glutamine; Toll-like receptor 2; Apoptosis; Premature birth; Rats