Over-expression of B7-H1 (PD-L1) molecule in the tumor microenvironment (TME) is a major immune evasion mechanism in some cancer patients and antibody blockade of the B7-H1/PD-1 interaction can normalize compromised immunity without excessive side-effects. Using a genomescale T-cell activity array, we identified Siglec-15 as a critical immune suppressor. While only expressed on some myeloid cells normally, Siglec-15 is broadly upregulated on human cancer cells and tumor-infiltrating myeloid cells, and its expression is mutually exclusive to B7-H1, partially due to its induction by M-CSF and downregulation by IFN-γ. We demonstrate that Siglec-15 suppresses antigen-specific T-cell responses in vitro and in vivo. Genetic ablation or antibody blockade of Siglec-15 amplifies anti-tumor immunity in the TME and inhibits tumor Users may view, print, copy, and download text and data-mine the content in such documents, for the purposes of academic research, subject always to the full Conditions of use:
Specific mechanisms by which tumor infiltrating lymphocytes (TIL) become dysfunctional remain poorly understood. Here, we employed a two-pronged approach using single-cell mass cytometry and tissue imaging technologies to dissect TILs from 25 resectable and 35 advanced non-small cell lung cancer (NSCLC) patients. We identified a burned-out CD8 + TIL subset (Ebo) that specifically accumulated within the tumor microenvironment (TME), but not in adjacent non-tumoral tissues. Ebo showed the highest expression of proliferation and activation markers, but produced the lowest amount of IFN and were the most apoptotic CD8 + TIL subset. Using a humanized patient-derived tumor xenograft model, we demonstrated that Ebo expansion occurred within the TME in a PD-1/B7-H1 pathwaydependent manner. Ebo abundance in baseline tumor tissues was associated with resistance to anti-PD therapy in NSCLC patients. Our study identifies a dysfunctional TIL subset, with distinct features from previously described exhausted T cells, and implies strategies to overcome immunotherapy resistance.
Systemic lupus erythematosus (SLE) and discoid lupus erythematosus (DLE) of the skin are autoimmune diseases characterized by inappropriate immune responses against self-proteins; the key elements that determine disease pathogenesis and progression are largely unknown. Here, we show that mice lacking immune inhibitory receptor VISTA or programmed death-1 homolog (PD-1H KO) on a BALB/c background spontaneously develop cutaneous and systemic autoimmune diseases resembling human lupus. Cutaneous lupus lesions of PD-1H KO mice have clustering of plasmacytoid dendritic cells (pDCs) similar to human DLE. Using mass cytometry, we identified proinflammatory neutrophils as critical early immune infiltrating cells within cutaneous lupus lesions of PD-1H KO mice. We also found that PD-1H is highly expressed on immune cells in human SLE, DLE lesions, and cutaneous lesions of MRL/lpr mice. A PD-1H agonistic monoclonal antibody in MRL/lpr mice reduces cutaneous disease, autoantibodies, inflammatory cytokines, chemokines, and immune cell expansion. Furthermore, PD-1H on both T cells and myeloid cells including neutrophils and pDCs could transmit inhibitory signals, resulting in reduced activation and function, establishing PD-1H as an inhibitory receptor on T cells and myeloid cells. On the basis of these findings, we propose that PD-1H is a critical element in the pathogenesis and progression of lupus, and PD-1H activation could be effective for treatment of systemic and cutaneous lupus.
T cell exhaustion caused by mitochondrial dysfunction is the major obstacle of T cells‐based cancer immunotherapy. Besides exhausted T cells, the insufficient major histocompatibility complex class I (MHC I) on tumor cells leads to inefficient T cell recognition of tumor cells, compromising therapeutic efficacy. Therapeutic platform to regulate T cell exhaustion and MHC I expression for boosting T cells‐based cancer immunotherapy has not been realized up to date. Herein, an injectable hydrogel is designed to simultaneously tune T cell exhaustion and MHC I expression for amplified cancer immunotherapy. The hydrogel is in situ constructed in tumor site by utilizing oxidized sodium alginate‐modified tumor cell membrane vesicle (O‐TMV) as a gelator, where axitinib is encapsulated in the lipid bilayer of O‐TMV while 4‐1BB antibody and proprotein convertase subtilisin/kexin type 9 inhibitor PF‐06446846 nanoparticles are present in the cavities of hydrogel. After immune response trigged by O‐TMV antigen, the 4‐1BB antibody‐promoted T cell mitochondrial biogenesis and the axitinib‐lowered hypoxia synergistically reverse T cell exhaustion while the PF‐06446846‐amplified MHC I expression facilitates T cell recognition of tumor cells, demonstrating a powerful immunotherapeutic efficacy. This strategy on reprograming T cell exhaustion and improving T cell potency offers new concept for T cells‐based cancer immunotherapy.
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