Investigation of dendritic cells metabolic profile during the efferocytosis of apoptotic tumor cells.

Author(s)

Ludmilla da Silva Pereira

• Document type: Master's Dissertation
• Press: Araraquara. 0000-00-00.
• Institution: Universidade Estadual Paulista (Unesp). Faculdade de Ciências Farmacêuticas. Araraquara
• Defense date: 2022-10-25
• Advisor: Alexandra Ivo de Medeiros

Abstract

In the tumor microenvironment (TME), apoptosis is one of the main cell death pathways through conventional antitumor treatments, such as chemotherapy and radiotherapy. The clearance of these dead cells by phagocytes, termed efferocytosis, becomes a harmful process for the antitumor response because dendritic cells (DCs) and macrophages acquire an immunosuppressive profile after the internalization and digestion of tumor apoptotic cells. Therefore, this project aimed to investigate which metabolic pathways support the tolerogenic profile acquired by DCs after the efferocytosis within the TME. Renca cells (murine renal cortex adenocarcinoma) treated with doxorubicin, an inhibitor of topoisomerases I and II, were used as a source of tumor apoptotic cells, resulting in an apoptosis rate of 75%. Our data demonstrated that efferocytosis of apoptotic Renca cells (Renca-ACs) results in the generation of BMDCs with a tolerogenic profile, observed by the reduction in the co-expression of MHC II and CD86. Furthermore, the internalization and digestion of tumor apoptotic bodies significantly increased the expression of PD-L1, as well as the production of IL-10 and IL-6, compared to the control condition. Deficiency of TIM-4, AXL, and especially MertK, resulted in a reduction of PKH MFI, suggesting that BMDCs lower phagocytic ability. Using pharmacological inhibitors, we observed that the production of IL-10 and IL-6 during efferocytosis of Renca-ACs depends on the activation of glycolysis and glutaminolysis. In addition, IL-6 production also appears to depend on the fatty acid synthesis, and IL-10 production on fatty acid oxidation. After the efferocytosis of Renca-ACs, BMDCs had an increase in the expression of glycolytic enzymes such as Glut1, Pkm2, and Ldha, and we also observed a tendency for an increase in the expression of Cpt1a, suggesting the involvement of oxidative metabolism in the efferocytosis process. Interestingly, after 18 h of co-culture, a decrease in the reserve and the glycolytic capacity of BMDCs was observed, suggesting that the glycolytic demand is earlier and, in later phases, other metabolic pathways may be involved in the maintenance of the tolerogenic profile of these cells. Furthermore, the efferocytosis of Renca-ACs mediated by TIM-4, AXL, and MertK receptors seems to be involved in the activation of glycolytic metabolism, since the absence of these receptors reduced the expression of Glut1 and Ldha, proving that the interaction with efferocytic receptors impacts directly in the activation of metabolic pathways involved in the generation of the tolerogenic profile that BMDCs acquire during efferocytosis of apoptotic tumor cells. Taken together, these findings suggest that the efferocytosis of Renca-ACs generates tolerogenic BMDCs, that are supported mainly by glycolytic metabolism and, to a lesser extent, by oxidative metabolism. (AU)

• FAPESP's process: 20/09327-6 - Investigation of metabolic profile of dendritic cells during efferocytosis of tumor apoptotic cells
• Grantee: Ludmilla da Silva Pereira
• Support Opportunities: Scholarships in Brazil - Master