Disabled-2(DAB2)Overexpression Inhibits Monocyte-derived Dendritic Cells' Function In Vogt-koyanagi-harada Disease

Background:VKH disease is a uveitis entity that has a high risk of blinding in Asians.It is a systemic autoimmune disease directed against melanosome-associated antigens and affects tissues expressing these antigens.It is characterized by both intraocular and extraocular features,such as bilateral granulomatous panuveitis,vitiligo,and auditory abnormalities.Although the specific pathogenesis of VKH disease is still in the research phase,various types of immune cells have been proposed to be involved.Dendritic cells,macrophages,Th1 and Th17 cells in CD4~+T cells,and their associated inflammatory factors have been proved to be involved in the pathogenesis of Vogt-Koyanagi Harada.DAB2,a member of the endocytic receptor family,has been found as a negative regulatory gene controlling the function of DCs.The deletion of DAB2 in mouse bone marrow–derived DCs results in an increased antigen uptake capacity and enhances the stimulation of T cells.An increased DAB2 expression downregulates the maturation of DCs by inhibiting the Src/PI3K/Akt-NF-kB pathway.DAB2 is a also a tumor suppressor gene and its expression is decreased in some tumors,such as breast cancer and nasopharyngeal carcinoma.DAB2 has also been shown to negatively affect the function of various types of cells participating in the immune response.It is a target gene of forkhead box P3(Foxp3),and DAB2-deficiency impairs the function of regulatory T cells.The expression of DAB2 is different between M1 and M2 phenotypes in C57Bl/6 mice bone marrow–derived macrophages,whereby it is upregulated in M2 and suppressed in M1 macrophages.Previous studies have reported that DAB2is transiently increased during the acute phase of multiple sclerosis,and it has been shown to exacerbate the severity of experimental autoimmune encephalomyelitis.Whether DAB2 affects the function of DCs in an autoimmune disease such as VKH is not yet known and was,therefore,the subject of the study reported here.According to the background information mentioned above,this study mainly focused on the following parts:(1)The mRNA and protein expression of DAB2 in DC from patients with Vogt-Koyanagi Harada syndrome.(2)The possible mechanism of abnormal expression of DAB2 in DCs from active VKH patients.(3)The function of DC after DAB2 overexpression in active VKH patients.(4)The activation and stimulation ability of DCs on CD4+T cells after overexpression of DAB2 in DCs from active VKH patients.(5)The possible molecular mechanism of these changes after DAB2overexpression.Through these contents,we can discover the possible function of DAB2in immune cells and autoimmune diseases,find new therapeutic target gene of Vogt-Koyanagi Harada disease.Objective:DAB2 is a negative regulator gene in mouse bone-derived DC,and DC is an important member of the pathogenesis of Vogt-Koyanagida syndrome.The purpose of this study was to investigate the main role of DAB2 in patients with Vogt-Koyanagida syndrome and the effect of DAB2overexpression on DC cells,and further explore the possible molecular mechanism.Methods:The mRNA and protein levels of DAB2 were quantified by quantitative real-time PCR and Western blot.The Sequenom MassARRAY system was used to detect the promoter methylation level.An adenovirus carrying the DAB2 gene was transduced into immature DCs,isolated,and induced from active VKH patients.The surface markers of DCs,the frequency of T helper(Th)type 1(Th1)and Th17 cells in CD4+T cells,which were co-cultured with DCs,were tested by flow cytometry.ELISA was used to analyze the inflammatory cytokines produced by DC and CD4+T cell co-cultures.Results:The mRNA and protein expression levels of DAB2 in DCs obtained from active VKH patients were decreased,while the DAB2 promoter methylation level was marginally increased when compared with inactive VKH patients and normal controls.The expression of CD86 on DCs was significantly down-regulated by DAB2 overexpression.The DC-related inflammatory factors IL-6 and TNF-?were also decreased.The frequency of Th1 and Th17 cells and their related cytokines were reduced significantly after co-culture with DAB2 overexpressing DCs.DAB2overexpression did not affect autophagy in DCs from VKH patients.Conclusions:These results suggest that the decreased expression of DAB2 in DCs plays a role in the pathogenesis of VKH disease.DAB2 overexpression inhibits DC function,but this is not mediated via autophagy.