4-Octyl Itaconate Modulates Dendritic Cells Function and Tumor Immunity via NRF2 Activation.

OBJECTIVE: Dendritic cells (DCs) play a pivotal role in orchestrating anti-tumor immune responses. However, various factors can suppress DCs function and compromise anti-tumor immunity. Itaconate, a metabolite activated during inflammation and infection, has been identified to possess immunomodulatory properties, but its role on DCs remains largely unexplored. In this study, we aimed to investigate the role of itaconate in regulating the maturation and function of DCs and its underlying molecular mechanism. METHODS: Bone marrow-derived dendritic cells (BMDCs) were treated with 4-octyl itaconate (4OI). The expression levels of CD40, CD80, CD86, and MHC-II on BMDCs were analyzed by flow cytometry. The mRNA expression of cytokines was assessed using RT-qPCR. BMDCs with different treatment were adoptively transferred to B16-OVA tumor-bearing mice. The production of IFN-γ, IL-2, and TNF-α in CD4(+) T and CD8(+) T cells were analyzed by flow cytometry. The protein level of NRF2 in BMDCs was analyzed by Western blot. RESULTS: Treatment with 4OI represses DC maturation and function. Specifically, 4OI-treated DCs exhibited impaired phenotypic and functional maturation, characterized by decreased expression of co-stimulatory molecules CD40, CD80, and CD86, as well as lower levels of pro-inflammatory cytokines IL-12, IL-6, TNF-α and IL-1β. Furthermore, these DCs demonstrated a diminished capacity to stimulate T cell responses both in vitro and in vivo. Mechanistically, 4OI inhibits DCs maturation and function through enhancing and activating KEAP1/NRF2 pathway. CONCLUSION: This study reveals that 4OI inhibits DC function through NRF2 activation, elucidating the immunomodulatory mechanisms of itaconate and emphasizing its pivotal role in developing targeted DC-based tumor immunotherapy strategies.