Study On The Role And Mechanism Of TREM-1 In Choroidal Neovascularization

Objective:To explore the expression of triggering receptor expressed on myeloid cells-1(TREM-1)in choroidal neovascularization(CNV)and its role on the formation of CNV,so as to provide a new idea for the study of the pathogenesis,diagnosis and treatment of CNV.Methods:1.The mouse CNV models induced by laser was established.TREM-1,vascular endothelial growth factor(VEGF)and tumor necrosis factor(TNF-α)in chorioretinal tissue were detected by western blot at 1 day(1d),3 days(3d),7 days(7 d),14 days(14d)and 28days(28d)after laser induction and were compared with the normal control group.2.At 7days after laser induction,the mice were divided into groups according to the treatment methods:(1)Normal control group;(2)Injury(CNV)control group;(3)Intravitreal injection(IVI)of ranibizumab(RBZ)group;(4)Intraperitoneal injection(IPI)of LP17(TREM-1 inhibitor,LQVTDSGLYRCVIYHPP)group;(5)In the combination drug group,mice were treated with IVI of RBZ and IPI of LP17 at the same time.3.The expression of TREM-1 was detected by immunohistochemical staining,and the effects of expression of TREM-1,VEGF and TNF-α on different treatment methods were detected by western blot.4.Fundus fluorescein angiography(FFA),indocyanine green angiography(ICGA)and choroidal flat mounting were used to evaluate the effects of leakage area of CNV on different treatment methods.HE staining was used to detect the retinal structure and integrity of CNV region in different treatment groups.The localization of TREM-1 and VEGF in CNV in different treatment groups was detected by immunofluorescence.The aggregation of macrophages in CNV area in different treatment groups was detected by choroidal spread immunofluorescence staining.Results:1.The mouse CNV models was induced by laser photocoagulation.The results of immunohistochemical showed that the expression of TREM-1 in the choroidal region of CNV increased at 7th day after laser photocoagulation compared with the normal control group.2.Western blot showed that compared with the normal control group,the expression of TNF-α,TREM-1 and VEGF increased gradually with time after laser photocoagulation(P<0.05),peaked at 7-14 days,and then decreased gradually.3.At 7th day after laser photocoagulation,the mice were treated with different drugs.Western blot showed that being compared with the injury control group,the expression of VEGF decreased significantly in RBZ group,however there was no statistical significance difference among the expression of TREM-1 and TNF-α(P>0.05).The expression of TNF-α,VEGF and TREM-1 in LP17 group and combination group decreased significantly.The results of FFA and ICGA showed that the leakage area of CNV reduced significantly in RBZ group,LP17 group and combination group.HE staining also showed that the area of CNV significantly reduced and the integrity of retinal structure in CNV area was protected in RBZ group,LP17 group and combination group.4.Immunofluorescence of tissue sections showed that 7 days after laser photocoagulation,TREM-1 and VEGF were significantly located in the choroidal layer of CNV region.LP17 significantly down-regulated the expression of VEGF and TREM-1 by inhibiting TREM-1.The immunofluorescence staining of choroidal flat mounting showed that the macrophages in the drug treatment group decreased significantly.Conclusions:Inhibition of TREM-1 represses formation of CNV by reducing expression of TNF-α and VEGF.This may become an alternative therapeutic target.Antagonizing TREM-1 alone or combined with anti-VEGF treatment is expected to improve the therapeutic effect of CNV.