Non-Invasive Optical Imaging of Eosinophilia during the Course of an Experimental Allergic Airways Disease Model and in Response to Therapy

Abstract

BackgroundMolecular imaging of lung diseases, including asthma, is limited and either invasive or non-specific. Central to the inflammatory process in asthma is the recruitment of eosinophils to the airways, which release proteases and proinflammatory factors and contribute to airway remodeling. The aim of this study was to establish a new approach to non-invasively assess lung eosinophilia during the course of experimental asthma by combining non-invasive near-infrared fluorescence (NIRF) imaging with the specific detection of Siglec-F, a lectin found predominantly on eosinophils.Methodology/Principal FindingsAn ovalbumin (OVA)-based model was used to induce asthma-like experimental allergic airway disease (EAAD) in BALB/c mice. By means of a NIRF imager, we demonstrate that 48 h–72 h after intravenous (i.v.) application of a NIRF-labeled anti-Siglec-F antibody, mice with EAAD exhibited up to 2 times higher fluorescence intensities compared to lungs of control mice. Furthermore, average lung intensities of dexamethasone-treated as well as beta-escin-treated mice were 1.8 and 2 times lower than those of untreated, EAAD mice, respectively and correlated with the reduction of cell infiltration in the lung. Average fluorescence intensities measured in explanted lungs confirmed the in vivo findings of significantly higher values in inflamed lungs as compared to controls. Fluorescence microscopy of lung cryosections localized the i.v. applied NIRF-labeled anti-Siglec-F antibody predominantly to eosinophils in the peribronchial areas of EAAD lungs as opposed to control lungs.Conclusion/SignificanceWe show that monitoring the occurrence of eosinophils, a prominent feature of allergic asthma, by means of a NIRF-labeled antibody directed against Siglec-F is a novel and powerful non-invasive optical imaging approach to assess EAAD and therapeutic response in mice over time.

In vivo imaging with antibodies and engineered fragments

“…Griessinger et al used the internalization of the T cell receptor complex to their advantage so that they could stably label T cells for PET imaging (Griessinger et al, 2015). In a study of eosinophil recruitment to the airways during asthma, optical imaging with AlexaFluor-labeled anti-Siglec-F antibody showed accumulation of Siglec-F-expressing eosinophils in the lungs of affected mice (Markus et al, 2014). Imaging of B cells was conducted in a huCD20 transgenic mouse model using 64 Cu-labeled rituximab (Natarajan et al, 2012).…”

Functionalized synchrotron in-line phase-contrast computed tomography: a novel approach for simultaneous quantification of structural alterations and localization of barium-labelled alveolar macrophages within mouse lung samples

“…The aim of this study was to develop a functional XPCT imaging approach (fXPCT) by exploiting the capability of alveolar macrophages (MÈ) to migrate to inflammatory sites within the lung using an ovalbumin induced experimental research papers allergic airways disease model (Markus et al, 2014). In order to visualize the biodistribution of cells following intratracheal application, MÈ of the immortalized alveolar macrophage cell line MH-S (Mbawuike & Herscowitz, 1989) were ex vivo labelled by adding a contrast agent suitable for X-ray-based imaging directly to the cell culture media.…”

Cone-beam x-ray phase-contrast tomography for the observation of single cells in whole organs

“…Figure 7.1 shows typical histological slices of lung sections from asthmatic (a,b) and control mice (c,d) [104]. To enable [104].…”

“…Asthma is induced in mice by using ovalbumin (OVA) sensitization and challenges, as described in detail in [104]. Control mice are prepared that receive PBS instead of OVA.…”