Noninvasive Imaging OX40+ Activated T Cells Provides Early Warning of Rheumatoid Arthritis.

PURPOSE: The goal of this study was to develop an imaging probe-IRDye-680RD-OX40 mAb-that can be used for noninvasive imaging and optical imaging of rheumatoid arthritis (RA). OX40/OX40 ligand (OX40L) interactions have been shown to exert potent costimulatory effects on T cell activation. Detectable change in T cell activation profiles was observed in early RA. METHODS: OX40 expression pattern was analyzed by flow cytometry. N-hydroxysuccinimide (NHS) esters are used to label proteins selectively on free amino groups of OX40 monoclonal antibody (mAb). Characterization of IRDye-680RD-OX40 mAb was measured and a fluorescence spectrum gathered. Cell binding assay was also performed between activated and naïve murine T cells. Longitudinal near-infrared fluorescence (NIRF) imaging of the probe was performed on day 8, day 9, day 10, and day 11 of adjuvant-induced arthritis (AIA) mouse model. Paw thickness and body weight were compared between the OX40 mAb and IgG injection groups. RESULTS: NIRF imaging with IRDye-680RD-OX40 mAb revealed strong OX40-positive responses with high specificity. Flow analysis showed that OX40 was specifically expressed on the surface of T cells in RP and spleen of AIA model. The AIA group was significantly differentiated from the control group at all time points with imaging monitoring. The region of interest (ROI) was in line with ex vivo imaging and biodistribution study. This study highlights the potential utility of the OX40 NIRF imaging as a new strategy for RA prediction and T cell monitoring. CONCLUSION: The results provide evidence that IRDye-680RD-OX40 mAb detects organized T cells activation in early RA. The optical probe was capable of detection of RA pathogenesis. It identified transcriptional responses to RA that mediate its immune functions. Thus, it may be an ideal probe for RA imaging.

Fluorophore-conjugated 4-1BB antibody enables early detection of T-cell responses in inflammatory arthritis via NIRF imaging.

PURPOSE: We first developed a 4-1BB-targeted optical probe, named IRDye-680RD-4-1BB mAb (monoclonal antibody), and evaluated its value for the detection of 4-1BB+ activated T cells in vivo as well as the diagnosis of rheumatoid arthritis (RA) in an adjuvant-induced arthritis (AIA) mouse model. METHODS: The 4-1BB expression pattern was analysed by flow cytometry and immunofluorescence (IF) staining. The 4-1BB mAb was conjugated with IRDye-680RD NHS ester, and characterized via fluorescence spectrum. A cell-binding assay was also performed to assess the interaction of this probe with activated and naïve murine T cells. Longitudinal near-infrared fluorescence (NIRF) imaging of the probe was performed at 6, 24, 48, 72, and 96 h after probe administration. RESULTS: 4-1BB expression was highly upregulated during the pathogenesis of RA. Good colocalization was also observed between CD3 and 4-1BB by IF staining and t-SNE (T-distributed stochastic neighbour embedding) analysis, which indicates that 4-1BB was mainly expressed on T cells. Compared to the control group, a significantly higher signal was observed in the right hind paw (RP) of mice with AIA at all time points. The ex vivo biodistribution study results were consistent with the in vivo NIRF imaging results, which validated the accuracy of the region of interest (ROI) measurements. The sensitivity against 100% specificity observed in the receiver operator characteristic (ROC) curve analysis could distinguish the AIA group from the control group at all time points, indicating the value of IRDye-680RD-4-1BB mAb for RA diagnosis. CONCLUSION: We successfully developed a novel optical imaging probe, named IRDye-680RD-4-1BB mAb, for tracking 4-1BB+ activated T cells in vivo, and 4-1BB NIRF imaging is a promising strategy for noninvasively detecting the pathogenesis of RA.

Hypoxia-responsive nanomaterials for tumor imaging and therapy.

Hypoxia is an important component of tumor microenvironment and plays a pivotal role in cancer progression. With the distinctive physiochemical properties and biological effects, various nanoparticles targeting hypoxia had raised great interest in cancer imaging, drug delivery, and gene therapy during the last decade. In the current review, we provided a comprehensive view on the latest progress of novel stimuli-responsive nanomaterials targeting hypoxia-tumor microenvironment (TME), and their applications in cancer diagnosis and therapy. Future prospect and challenges of nanomaterials are also discussed.

Visualizing T-Cell Responses: The T-Cell PET Imaging Toolbox.

T lymphocytes are key mediators of the adaptive immune response. Inappropriate or imbalanced T-cell responses are underlying factors in cancer progression, allergy, and other immune disorders. Monitoring the spatiotemporal dynamics of T cells and their functional status has the potential to provide unique biologic insights into health and disease. Noninvasive PET imaging represents an ideal whole-body modality for achieving this goal. With the appropriate PET imaging probes, T-cell dynamics can be monitored in vivo with high specificity and sensitivity. Herein, we provide a comprehensive overview of the applications of this state-of-the-art T-cell PET imaging toolbox and the potential it has to improve the clinical management of cancer immunotherapy and T-cell-driven diseases. We also discuss future directions and prospects for clinical translation.