| Objective:Acute mesenteric ischemia(AMI)is a life-threatening condition that occurs when an abrupt decrease in visceral blood flow,leading to high mortality.Vasodilatation is the initial response,but prolonged ischemia leads to vasoconstriction,which can persist even after the reestablishment of intestinal blood perfusion.The further development of AMI can result in worse vasospasm,impaired intestinal mucosal barrier function,potentially impairing mechanisms that prevent the translocation of bacteria from the intestinal lumen,further regional ischemia and more extensive injury to the bowel.Without intervention,the damage can progress to full-thickness injury,infarction,short bowel syndrome(SBS),multiple organ dysfunction syndrome(MODS)and even death.Despite years of advances in the clinical treatment,AMI remains a challenging process,for which a resection of the necrotic bowel is required ultimately.Early intervention to AMI and to restore perfusion more rapidly is critical for bowel saving.Angiogenesis is essential for intestinal function recovery after revascularization of the occluded main vessel.Published studies have shown angiogenic function in the neuronal guidance molecule netrin-1.Netrin-1,mainly known for its function in brain development where it provides instructive environmental cues to axons navigating the developing central nervous system,also promotes angiogenesis.To provide therapeutic target and theoretical basis in clinical treatment of AMI,the aim of this study is to investigate the angiogenic effect of netrin-1 in AMI and cells under hypoxia.Methods:Part 1:To evaluate Netrin-1 expression in Caco-2 cells exposed to normoxia and hypoxia and investigate the variation of netrin-1 over indicated time periods.Caco-2 cells were exposed to normobaric hypoxia(2%O2,5%CO2)for 0 h,12 h,24 h,36 h and 48 h,respectively.The expression of netrin-1 mRNA and protein was determined with Real-time PCR and Western blotting,respectively.Part 2:According to the classic Vichow triad,two clinical types of acute superior mesenteric venous thrombosis(ASMVT)animal models,the central-type ASMVT(ASMVT-C)and peripheral-type ASMVT(ASMVT-P)were established.The differentiation of netrin-1 expression and impaired intestinal mucosal barrier function were compared between the two types of ASMVT using Real-time PCR,Western bolt and immunohistochemistry.Part 3:Normal and ischemic bowel specimens after surgery in ASMVT were collected.Western bolt,Real-time PCR and immunohistochemistry were carried out to compare the relation between netrin-1 expression of partial intestinal specimens and the prognosis.Results:Part 1:When exposed to hypoxia,the expression levels of netrin-1 mRNA and protein were in a time-dependent manner.As hypoxia time extends,more netrin-1 mRNA and proteins were produced.Part 2:Compared with ASMVT-P group,the expression of netrin-1 mRNA and protein were significantly higher in ASMVT-C group,while a lower level of Chu's score and endotoxin levels were found.Netrin-1 expression of partial intestinal specimens were carried out and revealed that ASMVT-C group had a higher level of expression and milder impairment of intestinal mucosal barrier function.Part 3:Compared with the expression of netrin-1 in normal intestinal specimens,the netrin-1 expression of the bowel resected in ASMVT was higher.When patients divided in two groups by IHC score,the higher expression of netrin-1 protein in ASMVT 8 achieve better outcome(shorter bowel resection and lower SBS rate)than patients with lower-netrin-1 expression.Conclusion:(1)The expression of netrin-1 in Caco-2 cells increased gradually with the extending time of hypoxia.(2)Compared with sham group,two ASMVT groups had a higher expression of netrin-1.(3)ASMVT-C group had a higher netrin-1 expression and milder impairment of intestinal mucosal barrier function in comparison to ASMVT-P group.(4)In ASMVT patients,the length of necrotic bowel resected and the recovery of intestinal function in ASMVT-C group were better than ASMVT-P group. |
PDF Full Text Request