PERFETTINI, j.-l. | bioRxiv Science

bioRxiv2024

Gadolinium-based nanoparticles AGuIX and their combination with ionizing radiation trigger AMPK-dependent proinflammatory reprogramming of tumor-associated macrophages

BackgroundTumor-associated macrophages (TAMs) are essential components of the inflammatory microenvironment of tumors and are associated with poor clinical outcomes in the majority of cancers. TAMs mainly exhibit anti-inflammatory functions that promote and support the tissue remodeling, the immune suppression and the tumor growth. Regarding their plasticity, the functional reprogramming of anti-inflammatory TAMs into proinflammatory phenotype recently emerged as a therapeutic opportunity to improve the effectiveness of anticancer treatments such as radiotherapy. ResultsHere we show that gadolinium-based nanoparticles AGuIX alone and in combination with ionizing radiation (IR) induce in a dose-dependent manner, the accumulation of DNA double strand breaks, an Ataxia telangiectasia mutated (ATM)-dependent DNA-damage response, an increased expression of the Interferon regulatory factor 5 (IRF5) and the release of proinflammatory cytokines from targeted macrophages, thus directing their proinflammatory reprogramming. This process is associated with the activating phosphorylation of the Adenosine Monophosphate (AMP) activated protein kinase on threonine 172 (AMPKT172*) and the fragmentation of mitochondria. Furthermore, we demonstrate that the inactivation of AMPK reduces the mitochondrial fragmentation and the proinflammatory reprogramming of macrophages detected in response to AGuIX and their combination with IR. These results reveal that the AMPK-dependent regulation of mitochondrial fragmentation plays a central role during the proinflammatory reprogramming of macrophages. Accordingly, a positive correlation between AMPKT172* and proinflammatory activation of TAMs is detected following IR+AGuIX combination in syngeneic mouse model of colorectal cancer. ConclusionsAltogether, our results identify a novel signaling pathway elicited by AGuIX and their combined treatment with IR, that targets macrophage polarization, skews macrophage functions toward the proinflammatory phenotype and may enhance the effectiveness of radiotherapy.

immunology↗

bioRxiv2022

CDKN1A is a target for phagocytosis-mediated cellular immunotherapy in acute leukemia

Most tumor-associated macrophages (TAMs), which are abundant in the tumor microenvironment, demonstrate an immunosuppressive phenotype and contribute to tumor progression, treatment resistance and poor clinical outcomes1,2. Due to their functional plasticity, these cells could be reprogrammed to acquire a pro-inflammatory phenotype and promote tumor clearance1. Several therapeutic approaches targeting TAMs to alleviate their immunosuppressive properties or to harness their tumoricidal capacities have been developed3,4. Inhibition of interactions between phagocytic inhibitor receptors on macrophages and "dont eat me signals" on cancer cells, which promotes cancer cell engulfment, showed therapeutic benefits for several tumor types4-6. Investigating mechanisms involved in macrophage-mediated phagocytosis of tumor cells, we demonstrate here a key role for the cyclin-dependent kinase inhibitor CDKN1A (p21). Through transcriptional repression of SIRP (Signal-Regularity Protein ), which encodes a phagocytic inhibitor, CDKN1A promotes the ability of monocyte-derived macrophages (MDMs) to engulf leukemic cells. In turn, these MDMs acquire a pro-inflammatory phenotype that extends to surrounding MDMs in an Interferon {gamma} (IFN{gamma})-dependent manner. Human monocytes genetically engineered to overexpress p21 (p21TD-Mo) differentiate into anti-inflammatory MDMs that are primed for leukemic cell phagocytosis when transferred into mice xenografted with patient-derived T-cell acute lymphoblastic leukemia (T-ALL) cells. After leukemic cell engulfment, engineered macrophages undergo a pro-inflammatory activation, reducing leukemic burden and substantially prolonging survival of mice. These results reveal p21 as a trigger of phagocytosis-guided pro-inflammatory reprogramming of TAMs and demonstrate the potential for p21TD-Mo-based cell therapy in cancer immunotherapy.

immunology↗