Project description:The CD155/TIGIT axis can be co-opted during immune evasion in chronic viral infections and cancer. Pancreatic adenocarcinoma (PDAC) is a highly lethal malignancy, and immune-based strategies to combat this disease have been largely unsuccessful to date. We corroborate prior reports that a substantial portion of PDAC harbors predicted high affinity MHC class I-restricted neoepitopes and extend these findings to advanced/metastatic disease. Using two novel preclinical models of neoantigen-expressing PDAC, we demonstrate that intratumoral neoantigen-specific CD8+ T cells adopt multiple states of dysfunction, which are similar to tumor-infiltrating lymphocytes of human PDAC patients. Mechanistically, genetic and/or pharmacologic modulation of the CD155/TIGIT axis was sufficient to promote immune evasion in autochthonous neoantigen-expressing PDAC. Finally, we demonstrate that the CD155/TIGIT axis is critical to maintain immune evasion in PDAC and uncover a combination immunotherapy (TIGIT/PD-1 co-blockade plus CD40 agonism) that elicits profound anti-tumor responses in preclinical models, now poised for clinical evaluation.
Project description:The CD155/TIGIT axis plays a crucial role in the suppression of anti-tumor responses. The clinical benefit for patients with diverse types of advanced cancers that has been observed upon blockade of the interaction between CD155 and TIGIT has highlighted the need to study the mechanisms by which CD155 is regulated. Here we identify Cyclin C (CCNC) as a novel modulator of CD155 by using a genome-wide CRISPR-Cas9 screen. Notably, CCNC depletion increases the CD155 expression at the transcriptional level in a broad range of cancer cells. We further found that CCNC suppresses the CD155 expression by inhibiting the transcriptional activity of FOSL2. We further found that the stability of CCNC is negatively regulated by the E3 ubiquitin ligase complex component FBXO11. Functionally, CCNC depletion significantly suppresses the anti-tumor activity of natural killer (NK) and T cells both in vitro and in vivo. Clinically, the expression level of CCNC is negatively correlated with CD155 in cancer patient tissues. Together, our findings provide insights into the biology of CD155 regulation, identify a previously unrecognized master regulator of this critical immune checkpoint and highlight a combination immunotherapy (TIGIT/PD-1 co-blockade) as a promising anti-cancer therapeutic strategy to overcome immune evasion by CCNC-deficient tumor cells.
Project description:The goal was to determine the impact of CD155 signaling through CD226 and TIGIT on Tfh differentiation and function based on gene expression.
Project description:TIGIT+ Tregs suppress Th1 and Th17 responses while sparing Th2 responses. Analysis of global gene expression of TIGIT+ vs. TIGIT- Tregs from naive mice reveled that TIGIT+ Tregs display an activated phenotype and are enriched for Treg signature genes including the Treg effector molecule Fgl2 which enables them to selectively spare Th2 responses. TIGIT+ and TIGIT- Tregs were sorted from naïve Foxp3-GFP KI mice (pooled spleen and lymph nodes) TIGIT: T cell immunoreceptor with Ig and ITIM domains
Project description:we have focused T-cell immunoreceptor with Ig and ITIM domains (TIGIT) as a responsible molecule for serial tolansfer if the tolerant state. When naïve T cells were co-cultured with tolerant T cells, stimulated naïve T cells showed higher and earlier TIGIT expression in comparison to that of their single culture without the tolerant T cells. We also showed that TIGIT expression in naïve T cells become high promptly/quickly by cross-linking of TCR and poliovirus receptor (PVR; CD155), a partner/ligand of TIGIT, which is accompanied by reduced IL-2 expression.
Project description:B cell depletion in patients with relapsing remitting multiple sclerosis (RRMS) markedly prevents new MRI lesions and disease activity, suggesting the hypothesis that altered B cell function leads to the activation of T cells driving disease pathogenesis. Here, we performed comprehensive analyses of memory B cells from patients with MS and healthy age-matched controls stimulated with CD40L and IL-21, modeling the help of follicular helper T cells (Tfh cells), and found a differential gene expression signature in multiple B cell pathways. Most striking was impaired TIGIT expression on MS-derived B cells mediated by dysregulation of the transcription factor TCF4. Activated circulating Tfh cells (cTfh cells) expressed CD155, the ligand of TIGIT, and TIGIT on B cells revealed their capacity to suppress the proliferation of IL-17-producing cTfh cells via TIGIT/CD155 axis. Finally, CCR6+ cTfh cells were significantly increased in MS and their frequency was inversely correlated with that of TIGIT+ B cells. Together, these data suggest that the dysregulation of negative feedback loops between TIGIT+ memory B cells and cTfh cells in MS drive the activated immune system in the disease.
Project description:TIGIT+ Tregs suppress Th1 and Th17 responses while sparing Th2 responses. Analysis of global gene expression of TIGIT+ vs. TIGIT- Tregs from naive mice reveled that TIGIT+ Tregs display an activated phenotype and are enriched for Treg signature genes including the Treg effector molecule Fgl2 which enables them to selectively spare Th2 responses.
Project description:We compared the gene expression in wild type CD4+ T cells stimulated with agonistic anti-TIGIT 4D4 antibody to that of isotype and TIGIT-deficient (KO) controls.