重組脂化免疫原為基礎的治療型子宮頸癌疫苗之抗腫瘤機制探討

Anti-tumor mechanisms of recombinant lipoimmunogen-based therapeutic HPV vaccines

張立昇(Li-Sheng Chang)

指導教授 ： 黃海美 ； 劉士任

國立清華大學/生命科學院/生物科技研究所/博士(2014年)

摘要

人類乳突病毒(human papillomavirus, HPV)不僅造成每年全球有50萬子宮頸癌新增病例，還導致其它如生殖道及頭頸癌的發生。在HPV所引起的癌症缺乏有效的治療方法的當今，治療型子宮頸癌疫苗的開發是癌症免疫療法的一個理想的選擇。雖然毒殺型T細胞(cytotoxic T lymphocytes, CTLs) 在癌症免疫治療上扮演重要的角色，癌症相關的免疫抑制環境通常會限制這類治療的成功。因此，在免疫治療中同時誘導腫瘤專一性的毒殺型T細胞以及讓免疫抑制狀態倒轉是必要的。我們的研究團隊建立了重組脂質化蛋白質的技術平台，能生產具有活化類鐸受體 2 (toll-like receptor 2, TLR2)的脂質化免疫原(immunogens)，利用此平台製備出不活化之人類乳突病毒16型E7脂蛋白(rlipo-E7m)，並證實它能活化樹突狀細胞 (Dendritic cell, DC)，小鼠注射後可以誘發 Th1 免疫反應來對抗腫瘤。為了提升抗腫瘤效果在小鼠腫瘤大於200mm3的模式下，利用類鐸受體9促進劑(TLR9 agonist)- 含CpG序列非甲基化寡聚去氧核苷酸(unmethylated CpG oligodeoxynucleotide, CpG ODN)與重組脂化免疫原(rlipo-E7m)的混合來對抗大腫瘤。我們發現注射一劑rlipo-E7m/CpG不但能夠在誘導腫瘤專一性毒殺型T細胞(cytotoxic T lymphocytes, CTLs) 方面有加乘效果，且能夠治癒帶有直徑6到8毫米腫瘤的小鼠。而該治療除了能大幅地減少腫瘤內免疫抑制細胞(immunosuppressive cells) (如: CD11b+Gr1+, CD11b+F4/80+ 及 CD4+CD25+FOXP3+)的數目，並且能增加毒殺型T細胞的浸潤。進一步研究發現，帶有直徑大於10毫米腫瘤的小鼠接受rlipo-E7m/CpG以及化療藥物的合併治療後能有效提升存活率。這些結果顯示由脂質化免疫原與含CpG ODN組合而成的免疫療法，其產生之顯著抗腫瘤效果可能反映出毒殺型T細胞的增幅以及免疫抑制細胞被有效抑制的結果。這項以重組脂蛋白為基礎的免疫療法是一套非常具有潛力能被運用在其它癌症疫苗發展的方法。

關鍵字

類鐸受體 ； 人類乳突瘤病毒 ； 免疫治療 ； 癌症疫苗

並列摘要

High-risk types of human papillomavirus (HPV) cause over 500,000 cervical, anogenital, and a subset of head and neck cancers cases per year. Owning to lack of efficacious treatment regimen currently, therapeutic HPV vaccine is an ideal option to control HPV-mediated maligancies. Although induction of cytotoxic T lymphocytes (CTLs) is important for therapeutic vaccination, the cancer-associated immunosuppressive milieu often impairs the efficacy of such therapies. Therefore, the simultaneous induction of tumor-specific CTLs and reversal of the immunosuppression is necessary for therapeutic vaccination. A recombinant lipidated immunogen (rlipo-E7m) containing an inactivated HPV16E7 (E7m) and a bacterial lipid moiety with toll-like receptor 2 (TLR2) agonist activity has been demonstrated possess robust anti-tumor activity through induction of CTL response. To enhance therapeutic effects, TLR9 agonist (unmethylated CpG oligodeoxynucleotide, CpG ODN) was admixed with rlipo-E7m to treat large tumor in a mouse model of HPV-associated cancer. We found that CpG ODN synergistically enhanced tumor-specific CTL responses in tumor-bearing mice and eradicates large tumors (6-8 mm in diameter) when combined with rlipo-E7m. In addition, the combinations dramatically inhibit local immunosuppressive cells (CD11b+Gr1+, CD11b+F4/80+ and CD4+CD25+FOXP3+) numbers and increase infiltrating CTLs number in tumors. Administration of suboptimal doses of chemotherapeutic agent with rlipo-E7m and CpG ODN increased the survival time of mice-bearing large tumor (＞10 mm in diameter). These findings suggest a novel therapeutic role for targeted injections of TLR2 agonist-fused tumor antigen and CpG ODN to direct CTL migration to the tumor bed and repress the immunosuppressive environment in tumor-bearing host. This promising approach could be applied for the development of additional therapeutic cancer vaccines.

並列關鍵字

Toll-like recepor ； human papillomavirus ； MDSC ； Treg ； immunotherapy ； CpG ODN

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