Ripk1 Deficiency or K376R Mutation in Dendritic Cells Promotes Potent Antitumor Immunity

ABSTRACT Dendritic cells (DCs) are critical for initiating adaptive immunity through antigen presentation and T cell priming. While immunogenic cell death (ICD) enhances anti-tumor immunity, how programmed cell death in DCs shapes tumor immune responses remains unclear. Receptor-interacting protein kinase 1 (RIPK1) regulates apoptosis, necroptosis, and inflammation. Here, we show that mice with disrupted RIPK1 ubiquitination on K376 (Ripk1fl/K376R Cd11c-Cre, Ripk1DC-KO/K376R) develop inflammation and autoimmunity, phenocopying DC-specific RIPK1-deficient(Ripk1fl/fl Cd11c-Cre, Ripk1DC-KO) mice. These phenotypes were rescued by the genetic ablation of Ripk3 or Mlkl, establishing that RIPK1 ubiquitination is essential for suppressing DC necroptosis to maintain immune homeostasis. Remarkably, both Ripk1DC-KO and Ripk1DC-KO/K376R mice exhibit robust resistance to tumor growth, characterized by significantly enhanced T cell infiltration and activation. Mechanistically, we show that Ripk1 deficiency or the loss of its K376 ubiquitination augments antigen-presenting capacity of DCs through both necroptosis-dependent and -independent pathways. Furthermore, adoptive transfer of T cells from Ripk1DC-KO mice further amplifies anti-tumor immunity in recipient hosts. These results identify RIPK1 as a critical immunological checkpoint in DCs that constrains their immunogenic potential. Targeting this pathway represents a promising therapeutic strategy to potentiate T cell-mediated cancer immunotherapy.