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

激活的嗜酸性粒细胞浸润是病变肝脏的常见组织学特征，如移植肝的慢性排斥反应、GVHD或原发性胆汁性肝硬化（PBC），类似慢性CVHD。在这种情况下，活化的嗜酸性粒细胞在肝损伤中起重要作用，尽管精确的机制尚未分析。利用IL-5转基因（IL5Tg）小鼠，我们首次建立了活化嗜酸性粒细胞引起肝损伤的实验模型。lL5Tg小鼠（C3H/HeN-TgN(IL-5)Imeq）已建立并由高知医学院tominaga博士提供。尽管这只小鼠在周围表现出明显的嗜酸性粒细胞（30-70%），但在任何器官中均未观察到组织损伤。对IL5Tg小鼠腹腔注射25杯LPS（沙门菌Re 595）， 2周后处死。组织学检查显示明显的门静脉炎症伴嗜酸性粒细胞浸润（bbb50 %），门静脉束周围有广泛的小叶坏死。部分小胆管变性破坏，可见嗜酸性粒细胞聚集，导管上皮内可见嗜正性浸润。电镜检查显示嗜酸性细胞毒颗粒脱粒进入导管细胞。IL5Tg小鼠除肝脏外几乎无其他组织损伤。在对照组小鼠（C3H/HeN）中，LPS注射未引起任何组织损伤。将LPS诱导的il - 5tg的脾细胞（2x107细胞，嗜酸性粒细胞>50%）静脉转入非转基因小鼠（C3H/HeN），但未引起任何组织损伤。这一结果提示，除了活化的嗜酸性粒细胞外，LPS刺激的Kupffer细胞释放的各种细胞因子（包括TNF a）也是诱导嗜酸性肝损伤所必需的。进一步分析与活化的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，是了解该动物模型肝损伤的必要条件。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