Protective role of Pim-3 gene in intestinal mucosa damaged by burn or lipopolysaccharide

Abstract

To explore the protective role of Pim-3 gene in intestinal mucosa damaged by burn or lipopolysaccharide (LPS). (1) Ninety Wistar mice were randomly divided into 3 equal groups: Group A, undergoing 30% grade III burning on the back; Group B, undergoing intraperitoneal injection of LPS; and Group C, undergoing intraperitoneal injection of normal saline. 3, 6, 12, 24, and 48 hours after the treatment 5 rats from each group were killed with their small intestine tissues taken out. RT-PCR was used to detect the mRNA expression of Pim-3, a serine/threonine kinase, occludin, intercellular adhesion molecule (ICAM)-1, and Western blotting was used to detect the protein expression of Pim-3 and occludin. (2) Intestinal endothelial cells (IECs) of newborn Wistar rats were collected, cultured, and divided into 6 groups: Group (1), treated with LPS (endotoxin), Group (2), transfected with blank plasmid pEGFP-N(2) and treated with LPS, Group (3), transfected with recombinant pEGFP-N(2)/Pim-3and treated with LPS, Group (4), as normal control group, Group (5), transfected with blank plasmid pEGFP-N(2), and Group (6), transfected with recombinant plasmid pEGFP-N(2)/Pim-3. Six hours later RT-PCR was used to detect the mRNA expression of Pim-3, ICAM-1, and occludin. The apoptosis of the cells was examined by flow cytometry. (1) In Groups A and B the mRNA expression of Pim-3 began to increase 3 h later, peaked 6 h later, and then gradually decreased. The Pim-3 mRNA expression of Group C, however, remained always at a low level. The ICAM-1 mRNA expression levels of Groups A and B were constantly up-regulated 6 h later, all significantly higher than those of Group C (all P < 0.01). The occludin mRNA expression levels of Groups A and B began to increase 3 hours later, and peaked 12 hours later, all significantly higher than those of Group C (all P < 0.05). (2) The mRNA expression levels of Pim-3 and occludin of Group (6) was significantly higher than those of Groups (4) and (5) (both P < 0.05). However, there was no significant difference in ICAM-1 mRNA expression among Groups (4), (5), and (6). The mRNA expression levels of Pim-3, occluding, and ICAM-1 of Groups (3) were all significantly higher than those of Groups (1) and (2) (all P < 0.05). The mRNA expression levels of ICAM-1 of Groups (1), (2), and (3) were all significantly lower than those of Groups (4), (5), and (6) (all P < 0.05). The apoptotic rates of groups (4), (5), and (6) were all very low. The apoptotic rates of Groups (1) and (2) were 41.3% and 44.80% respectively, both significantly higher than that of Group (3) (36.03%, both P < 0.05). Both burning and LPS stimulate endogenous Pim-3 gene expression in small intestine which lasts a short time. Pim-3 gene not only suppresses the apoptosis of IECs, but also strengthens the occludin expression and inhibits the intestinal tract inflammatory reaction induced by LPS. LPS induces ICAM-1 expression, which can be inhibited by Pim-3.