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Purpose: We tested whether the translocator protein (TSPO)-targeted positron emission tomography (PET) tracer, N-acetyl-N-(2-[11C]methoxybenzyl)-2-phenoxy-5-pyridinamine ([11C]PBR28), could distinguish macrophage dominant from neutrophilic inflammation better than 2-deoxy-2-[18F]fluoro-D-glucose ([18F]FDG) in mouse models of lung inflammation and assessed TSPO association with macrophages in lung tissue from the mouse models and in patients with chronic obstructive pulmonary disease (COPD). Procedures: MicroPET imaging quantified [11C]PBR28 and [18F]FDG lung uptake in wild-type (Wt) C57BL/6J or heterozygous transgenic monocyte-deficient Wt/opT mice at 49 days after Sendai virus (SeV) infection, during macrophage-dominant inflammation, and in Wt mice at 3 days after SeV infection or 24 h after endotoxin instillation during neutrophilic inflammation. Immunohistochemical staining for TSPO in macrophages and neutrophils was performed using Mac3 and Ly6G for cell identification in mouse lung sections and CD68 and neutrophil elastase (NE) in human lung sections taken from explanted lungs from patients with COPD undergoing lung transplantation and donor lungs rejected for transplantation. Differences in tracer uptake among SeV-infected, endotoxin-treated, and uninfected/untreated control mice and in TSPO staining between neutrophils and macrophage populations in human lung sections were tested using analysis of variance. Results: In Wt mice, [11C]PBR28 uptake (% injected dose/ml lung tissue) increased significantly with macrophage-dominant inflammation at 49 days (D49) after SeV infection compared to controls (p = <0.001) but not at 3 days (D49) after SeV infection (p = 0.167). [11C]PBR28 uptake was unchanged at 24 h after endotoxin instillation (p = 0.958). [18F]FDG uptake increased to a similar degree in D3 and D49 SeV-infected and endotoxin-treated Wt mice compared to controls with no significant difference in the degree of increase among the tested conditions. [11C]PBR28 but not [18F]FDG lung uptake at D49 post-SeV infection was attenuated in Wt/opT mice compared to Wt mice. TSPO localized predominantly to macrophages in mouse lung tissue by immunostaining, and TSPO staining intensity was significantly higher in CD68+ cells compared to neutrophils in the human lung sections. Conclusions: PET imaging with [11C]PBR28 can specifically detect macrophages versus neutrophils during lung inflammation and may be a useful biomarker of macrophage accumulation in lung disease. [ABSTRACT FROM AUTHOR]

TLR agonists are effective at treating superficial cancerous lesions, but their use internally for other types of tumors remains challenging because of toxicity. In this article, we report that murine and human naive CD4+T cells that sequester Pam3Cys4 (CD4+ TPam3) become primed for Th1 differentiation. CD4+ TPam3 cells encoding the OVA-specific TCR OT2, when transferred into mice bearing established TGF-b-OVA-expressing thymomas, produce high amounts of IFN-g and sensitize tumors to PD-1/programmed cell death ligand 1 blockade-induced rejection. In contrast, naive OT2 cells without Pam3Cys4 cargo are prone to TGFb- dependent inducible regulatory Foxp3+ CD4+ T cell conversion and accelerate tumor growth that is largely unaffected by PD-1/programmed cell death ligand 1 blockade. Ex vivo analysis reveals that CD4+ TPam3 cells are resistant to TGF-β-mediated gene expression through Akt activation controlled by inputs from the TCR and a TLR2-MyD88-dependent PI3K signaling pathway. These data show that CD4+ TPam3 cells are capable of Th1 differentiation in the presence of TGF-β, suggesting a novel approach to adoptive cell therapy. [ABSTRACT FROM AUTHOR]

TLR agonists are effective at treating superficial cancerous lesions, but their use internally for other types of tumors remains challenging because of toxicity. In this article, we report that murine and human naive CD4 + T cells that sequester Pam 3 Cys 4 (CD4 + T Pam3 ) become primed for T h 1 differentiation. CD4 + T Pam3 cells encoding the OVA-specific TCR OT2, when transferred into mice bearing established TGF-β-OVA-expressing thymomas, produce high amounts of IFN-γ and sensitize tumors to PD-1/programmed cell death ligand 1 blockade-induced rejection. In contrast, naive OT2 cells without Pam 3 Cys 4 cargo are prone to TGF-β-dependent inducible regulatory Foxp3 + CD4 + T cell conversion and accelerate tumor growth that is largely unaffected by PD-1/programmed cell death ligand 1 blockade. Ex vivo analysis reveals that CD4 + T Pam3 cells are resistant to TGF-β-mediated gene expression through Akt activation controlled by inputs from the TCR and a TLR2-MyD88-dependent PI3K signaling pathway. These data show that CD4 + T Pam3 cells are capable of T h 1 differentiation in the presence of TGF-β, suggesting a novel approach to adoptive cell therapy., (Copyright © 2018 by The American Association of Immunologists, Inc.)