The Cellular Mechanism Of Lymphocytes Homing In DTMUV Infected Spleen Of Duck

In 2010,a disease characterized by bleeding and rupture of follicles from laying ducks in Zhejiang and Shanghai in China,which quickly spread to Shandong,Fujian and other provinces,caused serious economic losses to the duck industry in China.The disease was once named "Duck Hemorrhagic Ovaritis".Through the research of scholars,it was found that the disease was caused by a virus which is an RNA virus.The virus has a high homology with the flavivirus Ntaia virus.Then the disease was officially named Duck Tembusu virus(DTMUV).In addition to,DTMUV can be isolated in various animals.The current research on DTMUV mainly focuses on gene structure,protein composition,detection methods,and preventive treatment.The integration and control of the systemic immune response depends on the regulated transport of lymphocytes.During lymphocyte recycling,there is a unique high endothelial venules(HEV)present in various lymphoid tissues and organs,which is an important structure for lymphocyte redistribution.The process is called lymphocyte homing that lymphocytes are distributed to lymphoid tissues and organs through high endothelial venules.This lymphocyte "homing" process disperses the immunologic repertoire,directs lymphocyte subsets to the specialized microenvironments that control their differentiation and regulate their survival,and targets immune effector cells to sites of antigenic or microbial invasion.Lymphocyte homing requires the interaction of vascular addressins on the surface of HEV endothelial cells and homing factors on the surface of lymphocytes to promote the adhesion and migration of lymphocytes to vascular endothelial cells.Lymphocyte homing is a multi-step process involving specific adhesion and homing receptors.High endothelial venules have been found in human lymph nodes and tissues except the spleen.However,HEV were found in the spleen of chickens and Chinese turtle and relative with lymphocyte homing.The current research on lymphocyte homing mainly focuses on its structural basis,homing-related receptors,and migration methods.There is little research on lymphocyte homing in duck spleen and the relationship between proteoglycans and lymphatic homing.This article mainly uses morphological and cytological research methods to explore the changes of lymphocyte homing in duck spleen after DTMUV infection.Experiment Ⅰ The structural of duck spleen lymphocyte homing and the distribution of proteoglycan.In this experiment,HE staining and transmission electron microscopy were used to observe that the sheath capillary located in the center of the ellipsoid of the white pulp of the duck spleen was HEV,and its endothelial cells had a typical stereomorphic shape with developed golgi bodies.Besides,the sheath capillaries are surrounded by a large number of lymphocytes,forming a periellipsoidal lymphatic sheaths(PELS).Secondly,this test used 5,6-carboxyfluorescein diacetate succinimidyl ester(CFSE)markers of lymphocytes by jugular vein injection duck,the results showed that the lymphocytes can through the sheath capillaries into duck spleen tissue,and concentration in the PELS,which shows that the sheath capillaries is an important channel for lymphocytes to enter the duck spleen from the blood.In addition,positive colloid iron staining was firstly used to identify the distribution of proteoglycan in duck spleen.The results showed that proteoglycan was expressed in sheath capillaries and PELS,which may be related to the homing movement of lymphocytes.Experiment Ⅱ The cytological mechanism of lymphocytes of the duck spleen.mechanism of lymphocytes of the duck spleen.In this study,the isolated and purified DTMUV strain XZ-2012 was used as a strain model to intramuscularly inject the six-month egg-laying shelducks with 0.2ml DTMUV(5× 105 TCID50/mL)and chosed different infection time(3d,5d,7d)to observed the cytological mechanism of lymphocytes homing in DTMUV infected spleen of the duck by HE staining,transmission electron microscopy and positive colloidal iron staining.At 3dpi,the PELS site was damaged by the virus and vacuolized,but the lymphocytes and high endothelial cells were active,and the number of lymphocytes around the sheath capillaries increased.The distribution of proteoglycans in the sheath capillaries increased compared with the control group and decreased in the PELS site.When the virus was infected for 5 days,the lymphocytes in the spleen tissue increased a lot,and the deformed lymphocytes were observed.The vacuoles at the PELS of the spleen were reduced,and the expression of proteoglycans in the ellipsoid increased.When the virus was infected for 7 days,the spleen tissue gradually returned to normal,and the vacuolation of the PELS site basically disappeared.In addition,a large number of lymphocytes surround the sheath capillaries and the expression of proteoglycans in the sheath capillaries increased compared with the pre-infection period and the proteoglycans at PELS was re-expressed.In summary,after DTMUV infection in adult ducks,lymphocytes were stimulated to continuously enter spleen tissues from sheath capillaries,and high endothelial cells and lymphocytes were active.The expression of proteoglycans after viral infection was higher than that of the normal group,indicating that proteoglycan was closely related to the homing movement of lymphocytes.