Nanobody against V-set and Ig domain-containing 4 (Vsig4) on tissue macrophages, such as synovial macrophages, could visualize joint inflammation in multiple experimental arthritis models via single-photon emission computed tomography imaging. Here, we further addressed the specificity and assessed the potential for arthritis monitoring using near-infrared fluorescence (NIRF) Cy7-labeled Vsig4 nanobody (Cy7-Nb119). In vivo NIRF-imaging of collagen-induced arthritis (CIA) was performed using Cy7-Nb119. Signals obtained with Cy7-Nb119 or isotope control Cy7-NbBCII10 were compared in joints of naive mice versus CIA mice. In addition, pathological microscopy and fluorescence microscopy were used to validate the arthritis development in CIA. Cy7-Nb119 accumulated in inflamed joints of CIA mice, but not the naive mice. Development of symptoms in CIA was reflected in increased joint accumulation of Cy7-Nb119, which correlated with the conventional measurements of disease. Vsig4 is co-expressed with F4/80, indicating targeting of the increasing number of synovial macrophages associated with the severity of inflammation by the Vsig4 nanobody. NIRF imaging with Cy7-Nb119 allows specific assessment of inflammation in experimental arthritis and provides complementary information to clinical scoring for quantitative, non-invasive and economical monitoring of the pathological process. Nanobody labelled with fluorescence can also be used for ex vivo validation experiments using flow cytometry and fluorescence microscopy.

Original languageEnglish
Article number3347
JournalInternational Journal of Molecular Sciences
Issue number13
Publication statusPublished - 8 Jul 2019

    Research areas

  • Animals, Arthritis, Experimental/diagnosis, Fluorescent Antibody Technique, Fluorescent Dyes/chemistry, Immunohistochemistry, Macrophages/immunology, Male, Mice, Microscopy, Fluorescence, Models, Molecular, Molecular Imaging/methods, Molecular Structure, Receptors, Complement/immunology, Single-Domain Antibodies/chemistry, Spectroscopy, Near-Infrared, Staining and Labeling, Synovial Membrane/immunology

ID: 49967896