Project description:Immunotherapies targeting the immune checkpoint receptor programmed cell death protein 1 (PD-1) have shown remarkable efficacy in treating cancer. CD4+CD25hiFoxP3+ Tregs are critical regulators of immune responses in autoimmunity and malignancies, but the functional status of human Tregs expressing PD-1 remains unclear. We examined functional and molecular features of PD-1hi Tregs in healthy subjects and patients with glioblastoma multiforme (GBM), combining functional assays, RNA sequencing, and cytometry by time of flight (CyTOF). In both patients with GBM and healthy subjects, circulating PD-1hi Tregs displayed reduced suppression of CD4+ effector T cells, production of IFN-γ, and molecular signatures of exhaustion. Transcriptional profiling of tumor-resident Tregs revealed that several genes coexpressed with PD-1 and associated with IFN-γ production and exhaustion as well as enrichment in exhaustion signatures compared with circulating PD-1hi Tregs. CyTOF analysis of circulating and tumor-infiltrating Tregs from patients with GBM treated with PD-1-blocking antibodies revealed that treatment shifts the profile of circulating Tregs toward a more exhausted phenotype reminiscent of that of tumor-infiltrating Tregs, further increasing IFN-γ production. Thus, high PD-1 expression on human Tregs identifies dysfunctional, exhausted Tregs secreting IFN-γ that exist in healthy individuals and are enriched in tumor infiltrates, possibly losing function as they attempt to modulate the antitumoral immune responses.
Project description:Obesity is characterized by accumulation of T cells in insulin-sensitive tissues, including the visceral adipose tissue (VAT), that can interfere with the insulin signaling pathway eventually leading to insulin resistance (IR) and type 2 diabetes. Here, we found that PD-1+CD4 conventional T (Tconv) cells, endowed with a transcriptomic and functional profile of partially dysfunctional cells, are diminished in VAT of obese patients with dysglycemia (OB-Dys). These cells showed enhanced capacity to recirculate into the bloodstream and had a non-restricted TCRβ repertoire divergent from that of normoglycemic obese and lean individuals. PD-1+CD4 Tconv were reduced in the circulation of OB-Dys, exhibited an altered migration potential, and were detected in the liver of patients with non-alcoholic steatohepatitis. The findings suggest that dysglycemia in individuals with obesity is associated with recirculation of a heterogeneous population of partially dysfunctional PD-1+CD4 Tconv cells. These changes may contribute to the inter-organ crosstalk underlying IR
Project description:Glioblastoma is the most common primary malignant brain tumor in adults and associated with poor survival. Standard-of-care chemotherapy and radiation confer a median overall survival of under two years. The Ivy Foundation Early Phase Clinical Trials Consortium conducted a randomized, multi institution clinical trial to evaluate immune responses and survival following neoadjuvant and/or adjuvant therapy with pembrolizumab, a programmed cell death protein 1 (PD-1) monoclonal antibody, in 35 patients with recurrent, surgically resectable glioblastoma. Patients who were randomized to receive neoadjuvant pembrolizumab, with continued adjuvant therapy following surgery, had significantly extended overall survival compared to patients that were randomized to receive adjuvant, post-surgical PD-1 blockade alone (hazard ratio = 0.39; P = 0.04, log-rank test). Neoadjuvant PD-1 blockade was associated with upregulation of T cell and interferon-γ-related genes, but downregulation of cell cycle related genes within the tumor, which was not seen in patients that received adjuvant therapy alone. Focal induction of programmed death-ligand 1 (PD-L1) in the tumor microenvironment was observed more frequently in the neoadjuvant group than in tumors obtained from patients treated only in the adjuvant setting. Similarly, neoadjuvant pembrolizumab was associated with clonal T cell expansion and the overlap of T cell receptors between tumor and blood, decreased PD-1 expression in T cells and a decreasing peripheral monocytic population. These findings suggest that the neoadjuvant administration of PD-1 blockade enhances the local and systemic anti-tumor immune response and may represent a more efficacious approach to the treatment of this uniformly lethal brain tumor. This trial was registered with ClinicalTrials.gov under the identifier NCT02852655 (https://clinicaltrials.gov/ct2/show/NCT02852655).
Project description:<p>PD-1 is an important immune checkpoint inhibitor that shows great promise in the clinic, particularly for melanoma and lung cancers. Since PD-1 is also expressed on infiltrating CD4+ Treg and Teffector cells in glioblastoma, we sought to better understand the role of PD-1 on these infiltrating CD4+ Treg and Teffector cells. To this end, we performed functional and transcriptional profiling using CD4+ Treg and Teffector cells isolated from healthy donors and glioblastoma patients (from both tumors and blood).</p>
Project description:The differentiation and effector function of tumor infiltrating lymphocytes and macrophages in the tumor microenvironment is critical for productive anti-tumor immune responses, although direct evidence for this remains poorly characterized in brain cancer patients. Using mass cytometry, single-cell RNA sequencing, and quantitative multiplex immunofluorescence, we comprehensively characterized the phenotype and single-cell transcriptome of myeloid cells and T lymphocytes that infiltrated malignant gliomas, and identified how such populations changed following neoadjuvant PD-1 checkpoint blockade in recurrent glioblastoma patients. Cells of the myelo-monocytic lineage represented approximately three quarters of the immune cell infiltrate, with T lymphocytes representing the next major immune cell subset by density and percentage, but following neoadjuvant PD-1 antibody blockade, the ratio of myeloid cells to T cells significantly decreased. We then used single-cell RNA sequencing to comprehensively define the transcriptional profiles of lymphoid and myeloid populations in these tumors. Recurrent GBM patients treated with neoadjuvant PD-1 checkpoint inhibition possessed a greater fraction of CD8+ T cells with an effector T cell transcriptional program. The increased effector T cell populations were associated with the distinct upregulation of the chemokines, CXCL9 and CXCL10 by an interferon-responsive macrophage cluster. Importantly, we also identified that neoadjuvant PD-1 blockade was associated with significantly increased cellular interactions specifically between CD8+ T cells and tumor associated macrophages within the tumor microenvironment. Together, these findings suggest that effector T cell infiltration and differentiation are increased with neoadjuvant PD-1 blockade but impeded by adaptive resistance and immunosuppression from tumor associated macrophages. Future therapeutic strategies to target this dominant immunosuppressive myeloid cell population may be needed to achieve true, therapeutic interventions in this patient population.