尽管化学免疫治疗已成为肿瘤免疫治疗时代的关键组成部分，但它面临着肿瘤微环境（TME）的挑战，该环境中充斥着细胞和非细胞免疫抑制成分。本研究旨在设计一种纳米颗粒系统，能够在肿瘤和脾脏中充分积聚以分别介导局部和全身免疫应答。该研究还旨在重塑免疫抑制的TME。出于这些原因，我们用多功能聚乳酸-羟基乳酸（PLGA）纳米颗粒（NPs）开发了一种系统，能够同时通过多柔比星、奥美沙坦和二甲双胍来消除癌细胞、抑制与肿瘤相关的成纤维细胞（TAFs），以及重新教育与肿瘤相关的巨噬细胞（TAMs）。选择这些药物的原因是它们能够使脾脏免疫细胞的平衡倾向于免疫刺激性表型。为了建立TAM和TAF培养，我们将正常巨噬细胞和成纤维细胞与B16F10黑色素瘤细胞（Mel）分泌物共培养。我们制备了含药PLGA纳米颗粒，并在目标细胞类型中对其进行了表征和测试。用荧光素载荷的PLGA纳米颗粒在黑色素瘤小鼠模型中进行了器官分布评估。最后，描述了不同联合治疗方案的局部和全身效果。体外研究表明，载药PLGA纳米颗粒能够显著消除Mel的免疫抑制性，并使TAMs和TAFs倾向于更有利的表型。而体内实验证明，PLGA纳米颗粒具有长时间的血液循环时间，并且在肿瘤和脾脏中具有优先定位性。与单一药物治疗相比，二甲双胍或奥美沙坦与多柔比星的联合治疗在局部和全身上都更优越。然而，三药联合治疗产生了不良效果，包括健康状况恶化、免疫耗竭和转移。这些发现表明，TME重塑有潜力成为肿瘤成功接受化学免疫治疗的手段。此外，它们还揭示了谨慎使用联合治疗和采用减量策略的重要性。D-NPs指多柔比星载药纳米颗粒，M-NPs指二甲双胍载药纳米颗粒，L-NPs指奥美沙坦载药纳米颗粒，TAMs指肿瘤相关巨噬细胞，TAFs指肿瘤相关成纤维细胞，PD-L1指程序性死亡配体1，TNF-α指肿瘤坏死因子α，TGF-β指转化生长因子β，CD206/40/86指相应的免疫细胞表面标志物，α-SMA指α平滑肌肌动蛋白，MMPs指基质金属蛋白酶。©2023. 作者。

Despite the fact that chemoimmunotherapy has emerged as a key component in the era of cancer immunotherapy, it is challenged by the complex tumor microenvironment (TME) that is jam-packed with cellular and non-cellular immunosuppressive components. The aim of this study was to design a nanoparticulate system capable of sufficiently accumulating in the tumor and spleen to mediate local and systemic immune responses, respectively. The study also aimed to remodel the immunosuppressive TME. For such reasons, multi-functional polylactic-co-glycolic acid (PLGA) nanoparticles (NPs) were engineered to simultaneously eradicate the cancer cells, silence the tumor-associated fibroblasts (TAFs), and re-educate the tumor-associated macrophages (TAMs) using doxorubicin, losartan, and metformin, respectively. These agents were also selected for their ability to tip the balance of the splenic immune cells towards immunostimulatory phenotypes. To establish TAM and TAF cultures, normal macrophages and fibroblasts were incubated with B16F10 melanoma cell (Mel)-derived secretome. Drug-loaded PLGA NPs were prepared, characterized, and tested in the target cell types. Organ distribution of fluorescein-loaded PLGA NPs was evaluated in a mouse model of melanoma. Finally, the local and systemic effects of different combination therapy programs were portrayed. The in vitro studies showed that the drug-loaded PLGA NPs could significantly ablate the immunosuppressive nature of Mel and skew TAMs and TAFs towards more favorable phenotypes. While in vivo, PLGA NPs were proven to exhibit long blood circulation time and to localize preferentially in the tumor and the spleen. The combination of either metformin or losartan with doxorubicin was superior to the monotherapy, both locally and systemically. However, the three-agent combo produced detrimental effects in the form of compromised well-being, immune depletion, and metastasis. These findings indicate the potential of TME remodeling as means to prime the tumors for successful chemoimmunotherapy. In addition, they shed light on the importance of the careful use of combination therapies and the necessity of employing dose-reduction strategies. D-NPs doxorubicin-loaded NPs, M-NPs metformin-loaded NPs, L-NPs losartan-loaded NPs, TAMs tumor-associated macrophages, TAFs tumor-associated fibroblasts, PD-L1 programmed death ligand 1, TNF-α tumor necrosis factor alpha, TGF-β transforming growth factor beta, CD206/40/86 cluster of differentiation 206/40/86, α-SMA alpha-smooth muscle actin, MMPs matrix metalloproteases.© 2023. The Author(s).