title: Dual labeling of lipopolysaccharides for SPECT-CT imaging and fluorescence microscopy.
abstract: Lipopolysaccharides (LPS) or endotoxins are amphipathic, pro-inflammatory components of the outer membrane of Gram-negative bacteria. In the host, LPS can trigger a systemic inflammatory response syndrome. To bring insight into in vivo tissue distribution and cellular uptake of LPS, dual labeling was performed with a bimodal molecular probe designed for fluorescence and nuclear imaging. LPS were labeled with DOTA-Bodipy-NCS, and pro-inflammatory properties were controlled after each labeling step. LPS were then radiolabeled with (111)In and subsequently injected intravenously into wild-type, C57B16 mice, and their in vivo behavior was followed by single photon emission computed tomography coupled with X-ray computed tomography (SPECT-CT) and fluorescence microscopy. Time course of liver uptake of radiolabeled LPS ((111)In-DOTA-Bodipy-LPS) was visualized over a 24-h period in the whole animal by SPECT-CT. In complementary histological analyses with fluorescent microscopy, the bulk of injected (111)In-DOTA-Bodipy-LPS was found to localize early within the liver. Serum kinetics of unlabeled and DOTA-Bodipy-labeled LPS in mouse plasma were similar as ascertained by direct quantitation of β-hydroxymyristate, and DOTA-Bodipy-LPS was found to retain the potent, pro-inflammatory property of the unlabeled molecule as assessed by serum cytokine assays. It is concluded that the dual labeling process, involving the formation of covalent bonds between a DOTA-Bodipy-NCS probe and LPS molecules is relevant for imaging and kinetic analysis of LPS biodistribution, both in vivo and ex vivo. Data of the present study come in direct and visual support of a lipopolysaccharide transport through which pro-inflammatory LPS can be transported from the periphery to the liver for detoxification. The (111)In-DOTA-Bodipy-LPS probe arises here as a relevant tool to identify key components of LPS detoxification in vivo.
authors: Institute of Molecular Chemistry of the University of Burgundy, UMR CNRS 6302, University of Burgundy , 21000 Dijon, France.
authors: Vincent
authors: V
authors: Duheron
authors: Mathieu
authors: M
authors: Moreau
authors: Bertrand
authors: B
authors: Collin
authors: Wahib
authors: W
authors: Sali
authors: Claire
authors: C
authors: Bernhard
authors: Christine
authors: C
authors: Goze
authors: Thomas
authors: T
authors: Gautier
authors: Jean-Paul
authors: JP
authors: Pais de Barros
authors: Valérie
authors: V
authors: Deckert
authors: François
authors: F
authors: Brunotte
authors: Laurent
authors: L
authors: Lagrost
authors: Franck
authors: F
authors: Denat
mesh_terms: D000818:Animals; D056831:Coordination Complexes / Q000493:pharmacokinetics; D005456:Fluorescent Dyes / Q000493:pharmacokinetics; D007205:Indium Radioisotopes; D007553:Isotope Labeling; D008070:Lipopolysaccharides / Q000737:chemistry / Q000493:pharmacokinetics; D051379:Mice; D008810:Mice, Inbred C57BL; D008856:Microscopy, Fluorescence / Q000379:methods*; D015394:Molecular Structure; D014018:Tissue Distribution; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods*
chemical_list: D056831:Coordination Complexes; D005456:Fluorescent Dyes; D007205:Indium Radioisotopes; D008070:Lipopolysaccharides; C482199:lipopolysaccharide, E coli O55-B5