介白素二十(Interleukin-20, IL-20)是介白素十(Interleukin-10, IL-10)家族之ㄧ的成員，IL-10家族包含了有IL-10、IL-19、IL-20、IL-22、IL-24、IL-26等成員。在IL-10家族中IL-19、IL-20、IL-24共用了相同的受體；其中IL-19、IL-20、IL-24可以透過IL-20R1/IL-20R2進行下游訊息傳遞，而IL-20、IL-24還可透過IL-22R1/IL20-R2進行傳遞。目前有許多研究顯示，在乾癬、類風濕性關節炎、腎衰竭、粥狀動脈硬化，以及缺血性中風等疾病的致病機轉中，IL-20不僅參與其中，同時也扮演著重要的角色。在細胞與動物實驗模式中，IL-20的單株抗體可中和由IL-20所引起的致病發炎反應。由這些實驗結果顯示，IL-20與其單株抗體結合的抗原決定位（epitope）對IL-20 所調控的細胞反應非常重要。因此本研究目標在於鑑定IL-20和其單株抗體的抗原決定位置。首先我們構築並表現各種不同長短序列之IL-20重組蛋白，並經由西方墨點法的實驗證實IL-20與其單株抗體的結合位置。研究結果顯示，這些單株抗體主要來自於兩株不同的母株，一個來自於7E，另一個則來自於C2，他們各自辨認不同的抗原決定位。而先前研究結果已證實7E與IL-20之確切的結合位置，且也證實它確實具有中和致病反應的活性，在此研究中，我們也鑑定出單株抗體C2與IL-20的結合位置。而與7E不同之處在於我們初步證實C2並沒有中和致病反應的作用。同時我也利用狗IL-20更進一步去確定單株抗體7E辨認IL-20的結構為何。這些研究成果對於針對IL-20所開發的單株抗體藥物會帶來莫大的助益。

Interleukin-20 (IL-20) belongs to the IL-10 family, which includes IL-10, IL-19, IL-20, IL-22, IL-24, and IL-26. IL-19, IL-20, and IL-24 share their receptor subunits; all three members are capable of signaling through IL-20R1/IL-20R2, while IL-20 and IL-24 can also use IL-22R1/IL-20R2. Previous studies showed that IL-20 is involved in several diseases, such as psoriasis, rheumatoid arthritis, renal failure, atherosclerosis, and ischemic stroke. IL-20-mediated inflammatory responses can be neutralized by its monoclonal antibody 7E in vitro. These results suggested that the binding motif of IL-20 by monoclonal antibody must be very important in the IL-20-mediated cellular response. Therefore, we aimed to determine the epitope on IL-20 recognized by 7E. We performed a serial deletion of IL-20 coding region and expressed the recombinant proteins of these deleted mutants in E. coli. We mapped the epitope of IL-20 which was recognized by 7E by using Western blot. Western blot showed that the monoclonal antibodies, 7E and C2, recognized different binding motif on IL-20. Previously, we determined the binding epitope of IL-20 by 7E and showed that 7E could neutralize IL-20-mediated cellular responses, and also determined the binding epitope of IL-20 by C2 in this study. In contrast to 7E, C2 showed no neutralization activity for IL-20-mediated cellular response. I also used Dog IL-20 as a model to further delineate the structure recognized by 7E. Our study provide information for further development of IL-20-specific targeting therapy.

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