Pavelko, Kevin D

Our research uncovers a role for ATR in responding to ECM stiffness and promoting epithelial-to-mesenchymal transition (EMT) and metastasis. ATR, when deubiquitinated and upregulated by USP21 under enhanced ECM stiffness conditions, phosphorylates the nuclear protein SUN2, which promotes β-catenin nuclear translocation and EMT. ATM-mediated EMT promotes polymorphonuclear myeloid-derived suppressor cell recruitment and inhibits CD103 + dendritic cells, fostering an immunosuppressive tumor milieu. ATR inhibition disrupts this malignant cascade by promoting mesenchymal-to-epithelial transition to enhance antitumor immunity and mitigate metastases. Consistently, circulating HLA-DR + dendritic cells were also enhanced following treatment with the ATR inhibitor berzosertib in patients with therapeutically resistant early-stage breast cancer. Our data suggest that ATR-targeted therapy may be optimized by considering both DNA damage–dependent and EMT-inducing effects of ATR ATR promotes metastasis and immunosuppression through EMT process

In metabolic dysfunction–associated steatohepatitis (MASH), liver sinusoidal endothelial cells (LSECs) acquire a proinflammatory phenotype termed lipotoxic endotheliopathy. We previously identified glycogen synthase kinase 3β (GSK3β) as a central signaling hub in LSECs during MASH. To elucidate the molecular mechanisms and functional outcome of lipotoxicity-induced GSK3β activation in LSECs, we utilized endothelial cell–specific Gsk3 β -KO ( Gsk3 β ΔEnd ) mice fed MASH-inducing diets. Endothelial Gsk3 β deletion significantly reduced markers of lipotoxic endotheliopathy, including adhesion molecules and chemokines, alongside liver injury, inflammation, and fibrosis. Immune profiling via flow cytometry and mass cytometry by time of flight (CyTOF) identified decreased hepatic infiltration of proinflammatory myeloid populations, particularly mature DCs in Gsk3 β ΔEnd mice. In a coculture system, GSK3β in lipotoxic LSECs promoted DCs maturation. Mechanistically, GSK3 inhibition restored lipotoxicity-induced alterations in LSEC mitochondrial morphology and respiration by regulating AMP-activated protein kinase and dynamin-related protein 1. This rescue suppressed chemokine and adhesion molecule expression, thereby limiting immune cell recruitment. Collectively, under lipotoxic stress, GSK3β amplifies mitochondrial dysfunction and inflammatory signaling in LSECs, enhancing myeloid cell homing and DC maturation. Targeting LSEC GSK3β may, therefore, represent a promising therapeutic strategy to mitigate LSEC-driven fibroinflammatory response in human MASH.

Abstract Purpose: Tumor-infiltrating lymphocytes are associated with a decreased risk of recurrence in human papillomavirus–associated oropharyngeal squamous cell carcinoma. The composition and spatial distribution of tumor-infiltrating lymphocytes and tumor-infiltrating immune cells are not well characterized. Experimental Design: Formalin-fixed, paraffin-embedded primary and lymph node (LN) tumor tissues from 10 progressors (cases) and 10 matched nonprogressors (controls) were interrogated by imaging mass cytometry. Immune, stromal, and tumor cells were quantified from selected regions of interest using machine learning. Nearest neighbors, cell–cell interactions, and niche analyses were performed. Results: In primary regions of interest, immune cell, lymphocyte, T cell, CD8+ T cell, and innate cell prevalence was significantly greater in controls. High prevalence of immune cells, lymphocytes, innate cells, and CD4+ T cells in primary tissues was significantly associated with increased time to event (TTE). Although primary and LN prevalence of T cells, CD4+ T cells, CD8+ T cells, macrophages, and tumor cells were significantly correlated, differences in LNs were neither significant nor associated with TTE. Average distances between T cells and the nearest B cells and between lymphocytes and the nearest tumor cells were decreased in control primary tissues. Interactions between B and T cells were less organized in primary tissues from cases. A niche predominantly comprising lymphocytes was associated with longer TTE. Conclusions: In human papillomavirus–associated oropharyngeal squamous cell carcinoma, immune cell subset prevalence in primary tumors differs with outcome and is associated with TTE. Interactions between B cells and both T-cell subsets are associated with longer TTE, underscoring the importance of active intratumoral immune responses in outcomes.

Background: NASH is the progressive form of NAFLD characterized by lipotoxicity, hepatocyte injury, tissue inflammation, and fibrosis. Previously, Rho-associated protein kinase (ROCK) 1 has been implicated in lipotoxic signaling in hepatocytes in vitro and high-fat diet-induced lipogenesis in vivo. However, whether ROCK1 plays a role in liver inflammation and fibrosis during NASH is unclear. Here, we hypothesized that pathogenic activation of ROCK1 promotes murine NASH pathogenesis. Methods and Results: Patients with NASH had increased hepatic ROCK1 expression compared with patients with fatty liver. Similarly, hepatic ROCK1 levels and activity were increased in mice with NASH induced by a western-like diet that is high in fat, fructose, and cholesterol (FFC). Hepatocyte-specific ROCK1 knockout mice on the FFC diet displayed a decrease in liver steatosis, hepatic cell death, liver inflammation, and fibrosis compared with littermate FFC-fed controls. Mechanistically, these effects were associated with a significant attenuation of myeloid cell recruitment. Interestingly, myeloid cell-specific ROCK1 deletion did not affect NASH development in FFC-fed mice. To explore the therapeutic opportunities, mice with established NASH received ROCKi, a novel small molecule kinase inhibitor of ROCK1/2, which preferentially accumulates in liver tissue. ROCK inhibitor treatment ameliorated insulin resistance and decreased liver injury, inflammation, and fibrosis. Conclusions: Genetic or pharmacologic inhibition of ROCK1 activity attenuates murine NASH, suggesting that ROCK1 may be a therapeutic target for treating human NASH.

Abstract The intrinsic and acquired resistance to PD-1/PD-L1 immune checkpoint blockade is an important challenge for patients and clinicians because no reliable tool has been developed to predict individualized response to immunotherapy. In this study, we demonstrate the translational relevance of an ex vivo functional assay that measures the tumor cell killing ability of patient-derived CD8 T and NK cells (referred to as “cytotoxic lymphocytes,” or CLs) isolated from the peripheral blood of patients with renal cell carcinoma. Patient-derived PBMCs were isolated before and after nephrectomy from patients with renal cell carcinoma. We compared the efficacy of U.S. Food and Drug Administration (FDA)-approved PD-1/PD-L1 inhibitors (pembrolizumab, nivolumab, atezolizumab) and a newly developed PD-L1 inhibitor (H1A Ab) in eliciting cytotoxic function. CL activity was improved at 3 mo after radical nephrectomy compared with baseline, and it was associated with higher circulating levels of tumor-reactive effector CD8 T cells (CD11ahighCX3CR1+GZMB+). Treatment of PBMCs with FDA-approved PD-1/PD-L1 inhibitors enhanced tumor cell killing activity of CLs, but a differential response was observed at the individual-patient level. H1A demonstrated superior efficacy in promoting CL activity compared with FDA-approved PD-1/PD-L1 inhibitors. PBMC immunophenotyping by mass cytometry revealed enrichment of effector CD8 T and NK cells in H1A-treated PBMCs and immunosuppressive regulatory T cells in atezolizumab-treated samples. Our study lays the ground for future investigation of the therapeutic value of H1A as a next-generation immune checkpoint inhibitor and the potential of measuring CTL activity in PBMCs as a tool to predict individual response to immune checkpoint inhibitors in patients with advanced renal cell carcinoma.

Abstract Seven different anti–PD-1 and PD-L1 mAbs are now widely used in the United States to treat a variety of cancer types, but no clinical trials have compared them directly. Furthermore, because many of these Abs do not cross-react between mouse and human proteins, no preclinical models exist in which to consider these types of questions. Thus, we produced humanized PD-1 and PD-L1 mice in which the extracellular domains of both mouse PD-1 and PD-L1 were replaced with the corresponding human sequences. Using this new model, we sought to compare the strength of the immune response generated by Food and Drug Administration–approved Abs. To do this, we performed an in vivo T cell priming assay in which anti–PD-1/L1 therapies were given at the time of T cell priming against surrogate tumor Ag (OVA), followed by subsequent B16-OVA tumor challenge. Surprisingly, both control and Ab-treated mice formed an equally robust OVA-specific T cell response at the time of priming. Despite this, anti–PD-1/L1-treated mice exhibited significantly better tumor rejection versus controls, with avelumab generating the best protection. To determine what could be mediating this, we identified the increased production of CX3CR1+PD-1+CD8+ cytotoxic T cells in the avelumab-treated mice, the same phenotype of effector T cells known to increase in clinical responders to PD-1/L1 therapy. Thus, our model permits the direct comparison of Food and Drug Administration–approved anti–PD-1/L1 mAbs and further correlates successful tumor rejection with the level of CX3CR1+PD-1+CD8 + T cells, making this model a critical tool for optimizing and better utilizing anti–PD-1/L1 therapeutics.

Neurotropic viruses target the brain and contribute to neurologic diseases. Caspase recruitment domain containing family member 9 (CARD9) controls protective immunity in a variety of infectious disorders. To investigate the effect of CARD9 in neurotropic virus infection, CARD9−/− and corresponding C57BL/6 wild-type control mice were infected with Theiler’s murine encephalomyelitis virus (TMEV). Brain tissue was analyzed by histology, immunohistochemistry and molecular analyses, and spleens by flow cytometry. To determine the impact of CARD9 deficiency on T cell responses in vitro, antigen presentation assays were utilized. Genetic ablation of CARD9 enhanced early pro-inflammatory cytokine responses and accelerated infiltration of T and B cells in the brain, together with a transient increase in TMEV-infected cells in the hippocampus. CARD9−/− mice showed an increased loss of neuronal nuclear protein+ mature neurons and doublecortin+ neuronal precursor cells and an increase in β-amyloid precursor protein+ damaged axons in the hippocampus. No effect of CARD9 deficiency was found on the initiation of CD8+ T cell responses by flow cytometry and co-culture experiments using virus-exposed dendritic cells or microglia-enriched glial cell mixtures, respectively. The present study indicates that CARD9 is dispensable for the initiation of early antiviral responses and TMEV elimination but may contribute to the modulation of neuroinflammation, thereby reducing hippocampal injury following neurotropic virus infection.

Abstract TCF1 is essential for the development and function of T regulatory cells (Tregs). However, how TCF1 regulates Treg function in homeostasis or under pathogenic conditions is poorly understood. Here, we ablated TCF1 in Tregs to elucidate its role in Treg specification in healthy mice and mice with colon cancer. RNAseq revealed that TCF1-deficient Tregs maintain their core transcriptional signature, but promote T-cell receptor, Tgfβ receptor, TH17, and Wnt/β-catenin signaling pathways. Single-cell RNAseq identified central-memory-Tregs with low Klf2 or high Mif expression, which upon downregulation of TCF1 gained TH17 characteristics and matured into Maf expressing effector Tregs. Tcf1-deficient Tregs exhibited enhanced suppression of T-cell proliferation and cytotoxicity but were compromised in controlling CD4+ T-cell polarization and inflammation. In mice with polyposis, Tcf1-deficient Tregs promoted inflammation and tumor growth. Thus, TCF1 differentially regulates Treg control of TH17 inflammation and T-cell cytotoxicity, and its action in Tregs determines colorectal cancer outcome.

Abstract Theiler's murine encephalomyelitis virus (TMEV) infection of the CNS is cleared in C57BL/6 mice by a CD8 T cell response restricted by the MHC class I molecule H-2Db. The identity and function of the APC(s) involved in the priming of this T cell response is (are) poorly defined. To address this gap in knowledge, we developed an H-2Db LoxP-transgenic mouse system using otherwise MHC class I–deficient C57BL/6 mice, thereby conditionally ablating MHC class I–restricted Ag presentation in targeted APC subpopulations. We observed that CD11c+ APCs are critical for early priming of CD8 T cells against the immunodominant TMEV peptide VP2121-130. Loss of H-2Db on CD11c+ APCs mitigates the CD8 T cell response, preventing early viral clearance and immunopathology associated with CD8 T cell activity in the CNS. In contrast, animals with H-2Db–deficient LysM+ APCs retained early priming of Db:VP2121-130 epitope–specific CD8 T cells, although a modest reduction in immune cell entry into the CNS was observed. This work establishes a model enabling the critical dissection of H-2Db–restricted Ag presentation to CD8 T cells, revealing cell-specific and temporal features involved in the generation of CD8 T cell responses. Employing this novel system, we establish CD11c+ cells as pivotal to the establishment of acute antiviral CD8 T cell responses against the TMEV immunodominant epitope VP2121-130, with functional implications both for T cell–mediated viral control and immunopathology.