研究人员发现鞘脂激活蛋白原（pSAP）可驱动CD8 T细胞介导的肿瘤免疫，而其在肿瘤树突状细胞（DC）中的高糖基化可导致癌症免疫逃逸。研究人员发现溶酶体pSAP及其单saposin同源物介导了肿瘤细胞衍生的凋亡体的解体，从而促进膜相关抗原的呈现和T细胞的活化。在肿瘤微环境中，转化生长因子-β（TGF-β）诱导了pSAP的高糖基化及其随后的分泌，最终导致溶酶体溶酶体蛋白的耗竭。
在黑色素瘤患者的肿瘤相关直流细胞中也观察到了pSAP的高糖基化，用pSAP重组可挽救肿瘤浸润T细胞的活化。用重组pSAP靶向DC可触发肿瘤保护并增强免疫检查点疗法。这项研究证明了pSAP在肿瘤免疫中的关键功能，并可能支持其在免疫疗法中的作用。
据了解，肿瘤通过抑制抗原递呈来制定逃避免疫的策略。
附：英文原文
Title: Hyperglycosylation of prosaposin in tumor dendritic cells drives immune escape
Author: Pankaj Sharma, Xiaolong Zhang, Kevin Ly, Ji Hyung Kim, Qi Wan, Jessica Kim, Mumeng Lou, Lisa Kain, Luc Teyton, Florian Winau
Issue&Volume: 2024-01-12
Abstract: Tumors develop strategies to evade immunity by suppressing antigen presentation. In this work, we show that prosaposin (pSAP) drives CD8 T cell–mediated tumor immunity and that its hyperglycosylation in tumor dendritic cells (DCs) leads to cancer immune escape. We found that lysosomal pSAP and its single-saposin cognates mediated disintegration of tumor cell–derived apoptotic bodies to facilitate presentation of membrane-associated antigen and T cell activation. In the tumor microenvironment, transforming growth factor–β (TGF-β) induced hyperglycosylation of pSAP and its subsequent secretion, which ultimately caused depletion of lysosomal saposins. pSAP hyperglycosylation was also observed in tumor-associated DCs from melanoma patients, and reconstitution with pSAP rescued activation of tumor-infiltrating T cells. Targeting DCs with recombinant pSAP triggered tumor protection and enhanced immune checkpoint therapy. Our studies demonstrate a critical function of pSAP in tumor immunity and may support its role in immunotherapy.
DOI: adg1955
Source: https://www.science.org/doi/10.1126/science.adg1955