ANALYSIS OF CYTOTOXIC MECHANISMS OF ACTIVATED EOSINOPHILS IN BILIARY CELL INJURY : ESTABLISHMENT OF AN ANIMAL MODEL FOR PRIMARY BILIARY CIRRHOSIS

活化的嗜酸性粒细胞浸润是肝移植慢性排斥、移植物抗宿主病或类似慢性CVHD的原发性胆汁性肝硬变的常见组织学特征。在这些情况下，活化的嗜酸性粒细胞在肝脏损伤中起重要作用，尽管其确切的机制尚未被分析。利用IL-5转基因小鼠(IL-5 Tg)，首次建立了嗜酸性粒细胞活化所致肝损伤的实验模型。虽然这只小鼠在外周表现出明显的嗜酸性粒细胞增多(30-70%)，但在任何器官中都没有观察到组织损伤。IL5Tg小鼠于2周后腹膜腔内注射25杯明尼苏达沙门氏菌Re 595。组织学检查显示明显的门脉炎症，汇管区有嗜酸性细胞浸润(&gt；50%)，…周围有广泛的肺泡坏死。更多的是有标记的嗜酸性粒细胞。部分小胆管变性破坏，可见嗜酸性集合体，导管上皮内可见嗜酸性粒细胞渗入。电子显微镜检查显示嗜酸性细胞毒颗粒脱颗粒进入导管细胞。IL5Tg小鼠几乎没有肝脏以外的组织损伤。在对照小鼠(C3H/HEN)中，注射脂多糖未引起任何组织损伤，经LPS刺激的IL5Tg中的Spleen细胞(2x107细胞；嗜酸性粒细胞；50%)被静脉转移到非转基因小鼠(C3H/HEN)中，但从未引起任何组织损伤。提示除激活的嗜酸性粒细胞外，内毒素刺激的枯否细胞释放包括肿瘤坏死因子在内的多种细胞因子也是导致嗜酸性肝损伤所必需的。进一步分析与嗜酸性粒细胞趋化和脱颗粒有关的细胞因子或趋化因子的动态变化，以了解该动物模型中的肝损伤。较少

Activated eosinophilic infiltration is a common histological feature in diseased liver such as chronic rejection of transplanted liver, GVHD, or primary biliary cirrhosis (PBC) resembling chronic CVHD.In such conditions, it is suggested that activated eosinophils play an important role in liver damages, though precise mechanisms have not been analyzed. Using IL-5 transgenic (IL5Tg) mouse, we have first established an experimental model of liver injury caused by activated eosinophils.lL5Tg mice (C3H/HeN-TgN(IL-5)Imeq) have been established and provided from DR.Tominaga, Kochi Medical School. Although this mouse exhibits marked eosinophilia (30-70%) in the periphery, tissue injuries are not observed in any organs. IL5Tg mice were injected with 25 mug of LPS (Salmonella minesota Re 595) interaperitoneally and sacrificed 2 weeks later. Histological examinations showed marked portal inflammation with eosinophilic infiltrations (>50%) in portal tracts and extensive lobutar necrosis surround … More by marked eosinophils. Some small bile ducts were degenerated and destructed with eosinophihic aggregates, where eositiophilic infiltrations into ductal epithelium were observed. Electron microscopic examinations showed degranulation of eosinophilic cytotoxic granules into the ductal cells. Tissue injuries other than liver were almost absent in IL5Tg mice. in control mice (C3H/HeN), LPS injection did not induced any tissue injuries.Spleen cells (2x107 cells ; eosinophils>50%) from IL5Tg primed with LPS were transferred into none-transgenic mice (C3H/HeN) intravenously, but any tissue injuries were never induced. This result suggests that in addition to activated eosinophils, another factors such as various cytokines including TNF a released from LPS stimulated Kupffer cells are necessary for the induction of eosinophilic hepatic injury. Further analysis for dynamic changes of cytokines or chemokines, which are related to chemotaxis and degranulation of activated eosinophils, is needed for understanding the hepatic injury in this animal model. Less