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An Immune-Stimulatory Helix-Loop-Helix Peptide: Selective Inhibition of CTLA-4-B7 Interaction.
ACS Chemical Biology ( IF 3.5 ) Pub Date : 2020-01-08 , DOI: 10.1021/acschembio.9b00743
Tharanga M R Ramanayake Mudiyanselage 1 , Masataka Michigami 2 , Zhengmao Ye 2 , Atsuko Uyeda 3 , Norimitsu Inoue 4 , Kikuya Sugiura 1 , Ikuo Fujii 2 , Daisuke Fujiwara 2
Affiliation  

Molecular-targeting peptides and mini-proteins are promising alternatives to antibodies in a wide range of applications in bioscience and medicine. We have developed a helix-loop-helix (HLH) peptide as an alternative to antibodies to inhibit specific protein interactions. Cytotoxic T lymphocyte antigen-4 (CTLA-4) downregulates immune responses of cytotoxic T-cells by interaction with B7-1, a co-stimulatory molecule expressed on antigen presenting cells (APCs). To induce immune stimulatory activity, we used directed evolution methods to generate a HLH peptide that binds to CTLA-4, inhibiting the CTLA-4-B7-1 interaction and inducing immune stimulatory activity. Yeast-displayed libraries of HLH peptides were constructed and screened against CTLA-4 and identified the binding peptide Y-2, which exhibits a moderate affinity. The affinity of Y-2 was improved by in vitro affinity maturation to afford a stronger binder, ERY2-4. Peptide ERY2-4 specifically bound to CTLA-4 with a KD of 196.8 ± 2.3 nM, comparable to the affinity of the CTLA-4-B7-1 interaction. Furthermore, ERY2-4 inhibited the CTLA-4-B7-1 interaction with an IC50 of 1.1 ± 0.03 μM and blocked the interaction between CTLA-4 and dendritic cells (DCs) presenting B7 on their surface. Importantly, ERY2-4 showed no cross-reactivity against CD28, suggesting it does not suppress T-cell activation. Finally, in a mixed lymphocyte reaction assay with DCs and T cells, ERY2-4 enhanced an allogeneic lymphocyte response. Since CTLA-4 is a critical immune checkpoint for restricting the cancer immune response, this inhibitory HLH peptide represents a new class of drug candidates for immunotherapy.

中文翻译:

免疫刺激的螺旋环螺旋肽:CTLA-4-B7相互作用的选择性抑制。

在生物科学和医学领域的广泛应用中,分子靶向肽和微型蛋白是抗体的有希望的替代品。我们已经开发了螺旋-环-螺旋(HLH)肽作为抗体的替代品,以抑制特定的蛋白质相互作用。细胞毒性T淋巴细胞抗原4(CTLA-4)通过与B7-1相互作用而下调细胞毒性T细胞的免疫反应,B7-1是在抗原呈递细胞(APC)上表达的一种共刺激分子。为了诱导免疫刺激活性,我们使用了定向进化方法来生成与CTLA-4结合,抑制CTLA-4-B7-1相互作用并诱导免疫刺激活性的HLH肽。构建了酵母展示的HLH肽文库,并针对CTLA-4进行了筛选,并鉴定了具有中等亲和力的结合肽Y-2。Y-2的亲和力通过体外亲和力成熟得到改善,从而提供了更强的结合基ERY2-4。肽ERY2-4与CTLA-4特异性结合,其KD为196.8±2.3 nM,与CTLA-4-B7-1相互作用的亲和力相当。此外,ERY2-4以1.1±0.03μM的IC50抑制CTLA-4-B7-1相互作用,并阻止CTLA-4与在其表面呈递B7的树突状细胞(DC)之间的相互作用。重要的是,ERY2-4对CD28没有交叉反应,表明它不抑制T细胞活化。最后,在具有DC和T细胞的混合淋巴细胞反应测定中,ERY2-4增强了同种异体淋巴细胞反应。由于CTLA-4是限制癌症免疫反应的关键免疫检查点,因此这种抑制性HLH肽代表了一类用于免疫治疗的新型药物。
更新日期:2020-01-08
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