探討IL-37於免疫媒介之肝臟疾病之免疫調控作用

Abstract

IL-37是具有抑制發炎功能的細胞激素，可以調控先天免疫反應並且對許多發炎疾病有很好的治療效果。目前，IL-37對於免疫引起之肝臟疾病的效果仍不清楚。原發性膽汁性膽管炎 (Primary biliary cholangitis, PBC)是發生在肝臟內小膽管的自體免疫疾病，浸潤的免疫細胞造成肝臟發炎，進而導致肝纖維化以及肝硬化，最後引發肝臟衰竭。在我們的研究中，我們建構表現人類IL-37的腺相關病毒 (AAV-hIL-37)於小鼠肝臟中表現來探討IL-37在PBC小鼠模式中的功能。我們在利用2-OA-OVA致敏小鼠產生PBC前三天給予AAV-hIL-37，並且在致敏小鼠後第五和第十周犧牲小鼠以分析PBC的相關指標。我們的實驗結果顯示，AAV-hIL-37並沒有減緩PBC小鼠肝臟發炎的情況，而自體抗體、浸潤細胞數以及發炎相關細胞激素在給予AAV-hIL-37以及AAV-mock兩組PBC小鼠之間也沒有差異。然而，我們發現給予感染AAV-hIL-37之293細胞的培養上清液的巨噬細胞在LPS刺激的情況下其分泌的IL-6竟顯著的上升。我們接著探討AAV-hIL-37在另一個免疫媒介肝損傷─ concanavalin A (Con-A)引起之肝炎小鼠模式的免疫調控功能。小鼠在注射Con-A前給予AAV-mock或AAV-hIL-37，我們發現，給予AAV-hIL-37的Con-A小鼠肝臟內浸潤的免疫細胞數，以及自然殺手細胞、自然殺手T細胞、樹突細胞以及嗜中性球在肝臟浸潤細胞中的比例都有顯著的上升；除此之外，給予AAV-hIL-37的Con-A小鼠血清中IFN-的表現在給Con-A一個小時後就有顯著的上升。綜合上述結果，AAV-hIL-37無法減輕PBC但是會促進Con-A引起之肝炎小鼠的肝臟發炎情形。因此，IL-37對於免疫引起之肝臟發炎疾病的免疫調控功能需要更仔細的研究。

IL-37 is an anti-inflammatory cytokine that regulates innate immunity in vitro and shows benefits in many inflammatory disease models in vivo. However, the effects of IL-37 in immune-mediated liver diseases are still unclear. Primary biliary cholangitis (PBC) is an autoimmune disease that mainly occurs in intrahepatic bile ducts with immune cell infiltration, resulting in portal inflammation, followed by liver fibrosis, cirrhosis and eventually liver failure. Innate immunity plays a critical role in the natural history of PBC. In this study, we constructed and generated adeno-associated virus expressing human IL-37 (AAV-hIL-37) to investigate the effects of IL-37 in murine PBC. Mice were given AAV-hIL-37 three days before 2-OA-OVA immunization and PBC features were examined at 5 and 11 weeks post first immunization. Our results showed that AAV-IL-37 did not alleviate the liver inflammation of PBC mice. Autoantibodies, liver infiltrating cells and inflammatory cytokines were no differences between PBC mice administered with AAV-hIL-37 and AAV-mock. By adding culture supernatants of AAV-hIL-37 or AAV-mock transfected 293 cells to LPS stimulated thioglycollate-elicited peritoneal macrophages, we surprisingly found the culture supernatants of AAV-hIL-37 transfected cells significantly increased IL-6 secretion of macrophages. We then further investigated the effects of AAV-hIL-37 in another immune-mediated injury, concanavalin A (Con-A) induced hepatitis model. Mice were given AAV-hIL-37 or AAV-mock before Con-A injection. We found that the numbers of liver infiltrating immune cells and the frequencies of NK cells, NKT cells, dendritic cells (DC) and polymorphic nuclear cells (PMNs) were significantly increased in the liver of AAV-hIL-37 administered Con-A mice. In addition, serum IFN- of Con-A mice receiving AAV-hIL-37 was increased as soon at 1 hour after Con-A injection. Taken together, these results suggested that AAV-hIL-37 did not affect PBC whereas increased the inflammation in the liver of Con-A induced hepatitis. The immunoregulatory functions of IL-37 in the liver immune-mediated diseases need further careful studies.