Fluorescein-mediated sonodynamic therapy (FL-SDT) is an extremely promising approach for glioma treatment, resulting from the combination of low-intensity focused ultrasound (FUS) with a sonosensitizer. In the present study, we evaluated the efficacy and immunomodulation of SDT with fluorescein as the sonosensitizer in immunocompetent GL261 glioma mice for the first time. In vitro studies demonstrated that the exposure of GL261 cells to FL-SDT induced immunogenic cell death and relevant upregulation of MHC class I, CD80 and CD86 expression. In vivo studies were then performed to treat GL261 glioma-bearing mice with FL-SDT, fluorescein alone, or FUS alone. Perturbation of the glioma-associated macrophage subset within the immune microenvironment was induced by all the treatments. Notably, a relevant depletion of myeloid-derived suppressor cells (MDSCs) and concomitant robust infiltration of CD8+ T cells were observed in the SDT-FL-treated mice, resulting in a significant radiological delay in glioma progression and a consequent improvement in survival. Tumor control and improved survival were also observed in mice treated with FL alone (median survival 41.5 days,p> 0.0001 compared to untreated mice), reflecting considerable modulation of the immune microenvironment. Interestingly, a high circulating lymphocyte-to-monocyte ratio and a very low proportion of MDSCs were predictive of better survival in FL- and FL-SDT-treated mice than in untreated and FUS-treated mice, in which elevated monocyte and MDSC frequencies correlated with worse survival. The immunostimulatory potential of FL-SDT treatment and the profound modulation of most immunosuppressive components within the microenvironment encouraged the exploration of the combination of FL-SDT with immunotherapeutic strategies.
荧光素介导的声动力疗法（FL-SDT）是一种极具前景的胶质瘤治疗策略，其通过低强度聚焦超声与声敏剂的联合作用实现。本研究首次在免疫健全的GL261胶质瘤小鼠模型中，评估了以荧光素作为声敏剂的SDT疗效及其免疫调节作用。体外实验表明，GL261细胞经FL-SDT处理后可诱导免疫原性细胞死亡，并显著上调MHC I类分子、CD80和CD86的表达水平。随后开展的体内实验对GL261荷瘤小鼠分别给予FL-SDT、单纯荧光素或单纯FUS处理。所有治疗方案均能引起免疫微环境中胶质瘤相关巨噬细胞亚群的改变。值得注意的是，FL-SDT治疗组小鼠体内观察到髓源性抑制细胞（MDSCs）的显著耗竭，同时伴随CD8+ T细胞的强烈浸润，最终导致胶质瘤进展的影像学显著延迟及生存期的明显延长。单纯荧光素治疗组亦观察到肿瘤控制与生存改善（中位生存期41.5天，与未治疗组相比p>0.0001），这反映了免疫微环境的显著调控作用。值得关注的是，与未治疗组和单纯FUS治疗组相比，FL及FL-SDT治疗组中较高的循环淋巴细胞-单核细胞比值与极低的MDSCs比例可预测更优的生存预后；而在后两组中，单核细胞与MDSCs频率的升高与不良生存显著相关。FL-SDT治疗展现的免疫刺激潜能及其对微环境中多数免疫抑制成分的深度调控，为探索FL-SDT与免疫治疗策略的联合应用提供了重要依据。
肿瘤(癌症)患者之家