Cao-Pham, T. T. | Search bioRxiv

bioRxiv2024

P2Y2 purinergic receptor and DNA sensor cGAS dictate ionizing radiation-mediated proinflammatory macrophage activation

The reprogramming of tumor-associated macrophages (TAMs) by radiotherapy is associated with cancer patients response and sensitization to immune checkpoint blockade, but the molecular mechanisms involved remain largely unknown. Here, we show that following ionizing radiation (IR), macrophages accumulate single and double strand-DNA breaks and fragmented mitochondria in their cytosol, and stabilize the DNA sensor cyclic GMP-AMP synthase (cGAS). We demonstrate that mitochondrial fragmentation is induced by the activation of the dynamin-related protein 1 (DRP1), and controls the stabilization of cGAS and the proinflammatory activation of irradiated macrophages. Furthermore, pharmacological and genetic inhibitions of cGAS impair the proinflammatory activation of irradiated macrophages, thus revealing that cGAS is a central effector of IR-mediated proinflammatory macrophage activation. Interestingly, we also report that the purinergic receptor P2Y2 acts as an endogenous repressor of the proinflammatory macrophage activation and demonstrate that P2Y2 inactivation enhances the capacity of irradiated macrophages to undergo a proinflammatory activation. Our results thus define a new signaling pathway elicited in macrophages by IR directing mitochondrial dynamics, cytosolic DNA recognition by cGAS and proinflammatory phenotype, which is enhanced following P2Y2 inactivation.

immunology↗

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↗