Deficiency in interleukin-36R (IL-36R) antagonist caused by loss-of-function mutations in IL-36RN leads to DITRA (deficiency of IL-36 receptor antagonist), a rare inflammatory human disease that belongs to a subgroup of generalized pustular psoriasis (GPP). We report a functional genetic mouse model of DITRA with enhanced IL-36R signaling analogous to that observed in patients with DITRA, which provides new insight into our understanding of the IL-36 family of molecules in regulating barrier integrity across multiple tissues. Humanized DITRA-like mice displayed increased skin inflammation in a preclinical model of psoriasis, and in vivo blockade of IL-36R pathway using anti-human IL-36R antibody ameliorated imiquimod-induced skin pathology as both prophylactic and therapeutic treatments. Deeper characterization of the humanized DITRA-like mice revealed that deregulated IL-36R signaling promoted tissue pathology during intestinal injury and led to impairment in mucosal restoration in the repair phase of chronic dextran sulfate sodium (DSS)–induced colitis. Blockade of IL-36R pathway significantly ameliorated DSS-induced intestinal inflammation and rescued the inability of DITRA-like mice to recover from mucosal damage in vivo. Our results indicate a central role for IL-36 in regulating proinflammatory responses in the skin and epithelial barrier function in the intestine, suggesting a new therapeutic potential for targeting the IL-36R axis in psoriasis and at the later stages of intestinal pathology in inflammatory bowel disease.

The endogenous anti-tumor responses are limited in part by the absence of tumor-reactive T cells, an inevitable consequence of thymic central tolerance mechanisms ensuring prevention of autoimmunity. Here we show that tumor rejection induced by immune checkpoint blockade is significantly enhanced in Aire -deficient mice, the epitome of central tolerance breakdown. The observed synergy in tumor rejection extended to different tumor models, was accompanied by increased numbers of activated T cells expressing high levels of Gzma, Gzmb, Perforin, Cxcr3, and increased intratumoural levels of Cxcl9 and Cxcl10 compared to wild-type mice. Consistent with Aire’s central role in T cell repertoire selection, single cell TCR sequencing unveiled expansion of several clones with high tumor reactivity. The data suggest that breakdown in central tolerance synergizes with immune checkpoint blockade in enhancing anti-tumor immunity and may serve as a model to unmask novel anti-tumor therapies including anti-tumor TCRs, normally purged during central tolerance.

Therapeutic targeting of immune checkpoint pathways, which are exploited by tumors to evade the immune system, can result in increased overall survival for some patients with specific types of cancers. The endogenous antitumor response is limited in part by the absence of tumor-reactive T cells, an inevitable consequence of thymic central tolerance mechanisms ensuring their deletion to protect against autoimmunity. In this study, we show that compared to wild-type mice, tumor rejection induced by immune checkpoint blockade is significantly enhanced in Aire-deficient mice, the epitome of central tolerance breakdown. The observed synergy in tumor rejection extended to different tumor models and was accompanied by increased numbers of activated T cells expressing high levels of genes such as Gzma, Gzmb, Perforin, and Cxcr3, and tumors contained high levels of the chemokines Cxcl9 and Cxcl10 compared to wild-type mice. Furthermore, there was an enrichment of T cells expressing markers associated with the potent antitumor tissue-resident memory T cells expressing Cd103. Consistent with Aire’s central role in T cells’ repertoire selection, single-cell TCR sequencing unveiled the expansion of several clones with high tumor reactivity. Together, these results show that a break in central tolerance in combination with immune checkpoint blockade can potently enhance antitumor immunity and serve as a model system to unmask novel antitumor therapies. Citation Format: Asiel A. Benitez, Sara Khalil-Aguero, Anjali Nandakumar, Namita Gupta, Wendy Zhang, Gurinder S. Atwal, Andrew J. Murphy, Matthew A. Sleeman, Sokol Haxhinasto. Absence of central tolerance as a sculpting mechanism of immune-checkpoint therapy [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology and Immunotherapy; 2019 Nov 17-20; Boston, MA. Philadelphia (PA): AACR; Cancer Immunol Res 2020;8(3 Suppl):Abstract nr A41.