Multitarget, multiagent PLGA nanoparticles for simultaneous tumor eradication and TME remodeling in a melanoma mouse model.

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-ß transforming growth factor beta, CD206/40/86 cluster of differentiation 206/40/86, α-SMA alpha-smooth muscle actin, MMPs matrix metalloproteases.

Phytochemical-derived tumor-associated macrophage remodeling strategy using Phoenix dactylifera L. boosted photodynamic therapy in melanoma via H19/iNOS/PD-L1 axis.

BACKGROUND: The tumor microenvironment (TME) represents a barrier to PDT efficacy among melanoma patients. The aim of this study is to employ a novel muti-tactic TME-remodeling strategy via repolarization of tumor-associated macrophages (TAMs), the main TME immune cells in melanoma, from the pro-tumor M2 into the antitumor M1 phenotype using Phoenix dactylifera L. (date palm) in combination with PDT. METHODS: Screening of different date cultivars was employed to choose extracts of selective toxicity to melanoma and TAMs, not normal macrophages. Potential extracts were then fractionated and characterized by gas chromatography-mass spectrometry (GC-MS). Finally, the efficacy and the potential molecular mechanism of the co-treatment were portrayed via quantitative real-time polymerase chain reaction (qRT-PCR) analysis. RESULTS: Initial screening resulted in the selection of the two Phoenix dactylifera L. cultivars Safawi and Sukkari methanolic extracts. Sukkari showed superior capacity to revert TAM phenotype into M1 as well as more prominent upregulation of M1 markers and repression of melanoma immunosuppressive markers relative to positive control (resiquimod). Molecularly, it was shown that PDT of melanoma cells in the presence of the secretome of repolarized TAMs surpassed the monotherapy via the modulation of the H19/iNOS/PD-L1immune-regulatory axis. CONCLUSION: This study highlights the potential utilization of nutraceuticals in combination with PDT in the treatment of melanoma to provide a dual activity through alleviating the immune suppressive TME and potentiating the anti-tumor responses.