Besides completing a series of flow-cytometry-based phenotypic analyses, several functional antigen presentation assays were conducted using the SIINFEKL-specific T-cell clone B3Z. Anti-oxidants and electron transport chain inhibitors were also used to decipher UM171a\'s mode of action in MSCs. Finally, the potency of UM171a-treated MSCs was evaluated in the context of therapeutic vaccination using immunocompetent C57BL/6 mice with pre-established syngeneic EG.7T-cell lymphoma.
Treatment of MSCs with UM171a triggered potent increase in H2-Kb cell surface levels along with the acquisition of antigen cross-presentation abilities. Mechanistically, such effects occurred in response to UM171a-mediated production of mitochondrial-derived reactive oxygen species as their neutralization using anti-oxidants or Antimycin-A mitigated MSCs\' ability to cross-present antigens. Processing and presentation of the immunogenic ovalbumin-derived SIINFEKL peptide was caused by de novo expression of the Psmb8 gene in response to UM171a-triggered oxidative stress. When evaluated for their anti-tumoral properties in the context of therapeutic vaccination, UM171a-treated MSC administration to immunocompetent mice with pre-established T-cell lymphoma controlled tumor growth resulting in 40% survival without the need of additional supportive therapy and/or standard-of-care.
Altogether, our findings reveal a new immune-related function for UM171a and clearly allude to a direct link between UM171a-mediated ROS induction and antigen cross-presentation by MSCs. The fact that UM171a treatment modulates MSCs to become antigen-presenting cells without the use of IFN-gamma opens-up a new line of investigation to search for additional agents capable of converting immune-suppressive MSCs to a cellular tool easily adaptable to vaccination.
除了完成一系列基于流式细胞术的表型分析,使用SIINFEKL特异性T细胞克隆B3Z进行了几种功能性抗原呈递测定.抗氧化剂和电子传递链抑制剂也用于破译UM171a在MSCs中的作用模式。最后,使用免疫活性C57BL/6小鼠预先建立的同基因EG.7T细胞淋巴瘤,在治疗性疫苗接种的背景下评估了UM171a治疗的MSCs的效力.
用UM171a处理MSC引发H2-Kb细胞表面水平的有效增加以及抗原交叉呈递能力的获得。机械上,这种效应发生在对UM171a介导的线粒体衍生活性氧产生的反应中,因为它们使用抗氧化剂或抗霉素-A中和作用减轻了MSCs交叉呈递抗原的能力.免疫原性卵清蛋白来源的SIINFEKL肽的加工和呈递是由响应于UM171a触发的氧化应激的Psmb8基因的从头表达引起的。当在治疗性疫苗接种的背景下评估它们的抗肿瘤特性时,UM171a处理的MSC施用至具有预先建立的T细胞淋巴瘤的免疫活性小鼠,控制肿瘤生长,导致40%存活率,而不需要额外的支持疗法和/或标准护理。
总之,我们的发现揭示了UM171a的一种新的免疫相关功能,并清楚地暗示了UM171a介导的ROS诱导与MSCs的抗原交叉呈递之间的直接联系.UM171a处理在不使用IFN-γ的情况下调节MSC成为抗原呈递细胞的事实开辟了一条新的研究路线,以寻找能够将免疫抑制MSC转化为易于适应疫苗接种的细胞工具的其他试剂。