Department of Infectious Disease, Shanghai No. 6 People's Hospital, College of Medicine, Shanghai JiaoTong University, Shanghai 200233, China.
Acta Biochim Biophys Sin (Shanghai). 2013 Mar;45(3):203-12. doi: 10.1093/abbs/gms116. Epub 2013 Jan 7.
Previous studies have demonstrated that the therapeutic vaccine based on the enhancement of hepatitis B virus (HBV)-specific cytotoxic T lymphocyte (CTL) activity may lead to viral clearance in HBV-infected individuals. The endoplasmic reticulum (ER) chaperone Tapasin plays an important role in major histocompatibility complex (MHC) class I assembly and enhances specific MHC class I-restricted CTL activity by allowing more peptides to be translocated into the ER. Combining the specificity of hepatitis B core antigen (HBcAg) CTL epitope, the cell-penetrating property of cytoplasmic transduction peptide (CTP), and chaperone Tapasin may elicit robust specific HBV immune responses. In the present study, we confirmed the cytoplasmic localization preference of CTP-HBcAg(18-27)-Tapasin fusion protein in vitro and evaluated the effects on promoting bone marrow-derived dendritic cells (BMDCs) maturation and enhancing T cells response to generate specific CTLs. Our results showed that CTP-HBcAg(18-27)-Tapasin fusion protein could not only penetrate into the cytoplasm exactly and effectively to elevate Tapasin expression, but also increase the expression of surface molecules (CD80, CD83, CD86, and MHC-I) and secretion of cytokine (IL-12p70) of DCs. Moreover, DCs treated with the above fusion proteins increased significantly the cytokine secretion of proliferated T cells in vitro, the percentages of IFN-γ(+)CD8(+) T cells and specific CTL responses compared with control groups. In conclusion, the modification of Tapasin can enhance the presentation of targeting antigens via intracellular delivery to DCs and elicit specific CTL immune responses efficiently.
先前的研究表明，基于增强乙型肝炎病毒（HBV）特异性细胞毒性 T 淋巴细胞（CTL）活性的治疗性疫苗可能导致 HBV 感染个体的病毒清除。内质网（ER）伴侣 Tapasin 在 MHC I 类组装中发挥重要作用，并通过允许更多的肽进入 ER 来增强特定的 MHC I 类限制的 CTL 活性。结合乙型肝炎核心抗原（HBcAg）CTL 表位的特异性、细胞质转导肽（CTP）的细胞穿透特性和伴侣 Tapasin，可能引发强烈的特异性 HBV 免疫反应。在本研究中，我们证实了 CTP-HBcAg（18-27）-Tapasin 融合蛋白在体外的细胞质定位偏好，并评估了其促进骨髓来源树突状细胞（BMDC）成熟和增强 T 细胞反应以产生特异性 CTL 的作用。我们的结果表明，CTP-HBcAg（18-27）-Tapasin 融合蛋白不仅可以精确有效地穿透细胞质，从而提高 Tapasin 的表达，还可以增加树突状细胞表面分子（CD80、CD83、CD86 和 MHC-I）的表达和细胞因子（IL-12p70）的分泌。此外，与对照组相比，上述融合蛋白处理的 DCs 可显著增加体外增殖 T 细胞的细胞因子分泌、IFN-γ（+）CD8（+）T 细胞的百分比和特异性 CTL 反应。总之，Tapasin 的修饰可以通过细胞内递送来增强靶向抗原的呈递，并有效地引发特异性 CTL 免疫反应。
