MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, Jiangsu Province, 210095, China.
Avian Dis. 2020 Sep 1;64(3):286-293. doi: 10.1637/aviandiseases-D-20-00002.
The present study was designed to analyze the histologic and cytologic changes of lymphocyte homing in noninfected and duck Tembusu virus (DTMUV)-infected duck spleens. At first, we investigated the noninfected structure that facilitates lymphocyte homing. Under light and electron microscopy, results showed that sheath capillaries were located in the white pulp of the spleen, and the endothelial cells of sheath capillaries were cuboidal in shape, which is a typical characteristic of high endothelial venules. To monitor the lymphocyte homing, 5,6-carboxy fluoresceindiacetate succinimidyl ester (CFSE)-labeled lymphocytes that were intravenously injected into noninfected ducks appeared in the periellipsoidal sheaths (PELS), which proved that lymphocytes can return to the spleen through sheath capillaries. Furthermore, proteoglycans (PGs) associated with homing factors were positively observed in sheath capillaries and PELS by colloidal iron staining. This suggests that PGs are associated with lymphocyte homing. The results of the DTMUV infection experiment showed that PELS appeared vacuolized at 3 dpi. The spleen tissue gradually recovered at 5 and 7 dpi. In addition, the lymphocytes increased around sheath capillaries, and the expression of PGs in sheath capillaries increased after virus infection. Meanwhile, the gaps between endothelial cells were enlarged, and the lymphocytes were mainly in the lumen and basement membrane. In conclusion, lymphocytes could recruit into the spleen through sheath capillaries, and PGs participated and promoted the lymphocyte homing, suggesting that the unique high endothelial capillaries favor lymphocyte homing, which promotes tissue repair and antigen clearance in the duck.
本研究旨在分析非感染和鸭坦布苏病毒（DTMUV）感染鸭脾脏中淋巴细胞归巢的组织学和细胞学变化。首先，我们研究了有利于淋巴细胞归巢的非感染结构。在光镜和电镜下，结果表明，套区毛细血管位于脾脏白髓内，套区毛细血管的内皮细胞呈立方形，这是高内皮微静脉的典型特征。为了监测淋巴细胞归巢，静脉注射到非感染鸭体内的 5,6-羧基荧光素二乙酸琥珀酰亚胺酯（CFSE）标记的淋巴细胞出现在围绕小动脉的鞘（PELS）中，这证明了淋巴细胞可以通过套区毛细血管返回脾脏。此外，胶体铁染色显示，与归巢因子相关的蛋白聚糖（PGs）在套区毛细血管和 PELS 中呈阳性。这表明 PGs 与淋巴细胞归巢有关。DTMUV 感染实验结果表明，PELS 在 3dpi 时出现空泡化。脾脏组织在 5 和 7dpi 时逐渐恢复。此外，淋巴细胞在套区毛细血管周围增加，病毒感染后套区毛细血管中 PGs 的表达增加。同时，内皮细胞之间的间隙扩大，淋巴细胞主要位于管腔和基底膜中。总之，淋巴细胞可以通过套区毛细血管募集到脾脏，PGs 参与并促进了淋巴细胞归巢，提示独特的高内皮毛细血管有利于淋巴细胞归巢，从而促进鸭组织修复和抗原清除。
