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Blykers A, Schoonooghe S, Xavier C, D'hoe K, Laoui D, D'Huyvetter M, Vaneycken I, Cleeren F, Bormans G, Heemskerk J, Raes G, De Baetselier P, Lahoutte T, Devoogdt N, Van Ginderachter JA, Caveliers V. PET Imaging of Macrophage Mannose Receptor-Expressing Macrophages in Tumor Stroma Using 18F-Radiolabeled Camelid Single-Domain Antibody Fragments. J Nucl Med 2015; 56:1265-71. [PMID: 26069306 DOI: 10.2967/jnumed.115.156828] [Citation(s) in RCA: 121] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2015] [Accepted: 05/29/2015] [Indexed: 12/24/2022] Open
Abstract
UNLABELLED Tumor-associated macrophages constitute a major component of the stroma of solid tumors, encompassing distinct subpopulations with different characteristics and functions. We aimed to identify M2-oriented tumor-supporting macrophages within the tumor microenvironment as indicators of cancer progression and prognosis, using PET imaging. This can be realized by designing (18)F-labeled camelid single-domain antibody fragments (sdAbs) specifically targeting the macrophage mannose receptor (MMR), which has been identified as an important biomarker on this cell population. METHODS Cross-reactive anti-MMR sdAbs were generated after immunization of an alpaca with the extracellular domains of both human and mouse MMR. The lead binder was chosen on the basis of comparisons of binding affinity and in vivo pharmacokinetics. The PET tracer (18)F-fluorobenzoate (FB)-anti-MMR sdAb was developed using the prosthetic group N-succinimidyl-4-(18)F-fluorobenzoate ((18)F-SFB), and its biodistribution, tumor-targeting potential, and specificity in terms of macrophage and MMR targeting were evaluated in mouse tumor models. RESULTS Four sdAbs were selected after affinity screening, but only 2 were found to be cross-reactive for human and mouse MMR. The lead anti-MMR 3.49 sdAb, bearing an affinity of 12 and 1.8 nM for mouse and human MMR, respectively, was chosen for its favorable in vivo biodistribution profile and tumor-targeting capacity. (18)F-FB-anti-MMR 3.49 sdAb was synthesized with a 5%-10% radiochemical yield using an automated and optimized protocol. In vivo biodistribution analyses showed fast clearance via the kidneys and retention in MMR-expressing organs and tumor. The kidney retention of the fluorinated sdAb was 20-fold lower than a (99m)Tc-labeled counterpart. Compared with MMR- and C-C chemokine receptor 2-deficient mice, significantly higher uptake was observed in tumors grown in wild-type mice, demonstrating the specificity of the (18)F tracer for MMR and macrophages, respectively. CONCLUSION Anti-MMR 3.49 was denoted as the lead cross-reactive MMR-targeting sdAb. (18)F radiosynthesis was optimized, providing an optimal probe for PET imaging of the tumor-promoting macrophage subpopulation in the tumor stroma.
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Affiliation(s)
- Anneleen Blykers
- In Vivo Cellular and Molecular Imaging laboratory (ICMI), Vrije Universiteit Brussel, Brussels, Belgium
| | - Steve Schoonooghe
- Laboratory of Cellular and Molecular Immunology (CMIM), Vrije Universiteit Brussel, Brussels, Belgium Laboratory of Myeloid Cell Immunology (MCI), VIB, Brussels, Belgium
| | - Catarina Xavier
- In Vivo Cellular and Molecular Imaging laboratory (ICMI), Vrije Universiteit Brussel, Brussels, Belgium
| | - Kevin D'hoe
- Laboratory of Cellular and Molecular Immunology (CMIM), Vrije Universiteit Brussel, Brussels, Belgium Laboratory of Myeloid Cell Immunology (MCI), VIB, Brussels, Belgium
| | - Damya Laoui
- Laboratory of Cellular and Molecular Immunology (CMIM), Vrije Universiteit Brussel, Brussels, Belgium Laboratory of Myeloid Cell Immunology (MCI), VIB, Brussels, Belgium
| | - Matthias D'Huyvetter
- In Vivo Cellular and Molecular Imaging laboratory (ICMI), Vrije Universiteit Brussel, Brussels, Belgium
| | - Ilse Vaneycken
- In Vivo Cellular and Molecular Imaging laboratory (ICMI), Vrije Universiteit Brussel, Brussels, Belgium Department of Nuclear Medicine, UZ Brussel, Brussels, Belgium; and
| | | | - Guy Bormans
- Laboratory for Radiopharmacy, KU Leuven, Leuven, Belgium
| | - Johannes Heemskerk
- In Vivo Cellular and Molecular Imaging laboratory (ICMI), Vrije Universiteit Brussel, Brussels, Belgium Department of Nuclear Medicine, UZ Brussel, Brussels, Belgium; and
| | - Geert Raes
- Laboratory of Cellular and Molecular Immunology (CMIM), Vrije Universiteit Brussel, Brussels, Belgium Laboratory of Myeloid Cell Immunology (MCI), VIB, Brussels, Belgium
| | - Patrick De Baetselier
- Laboratory of Cellular and Molecular Immunology (CMIM), Vrije Universiteit Brussel, Brussels, Belgium Laboratory of Myeloid Cell Immunology (MCI), VIB, Brussels, Belgium
| | - Tony Lahoutte
- In Vivo Cellular and Molecular Imaging laboratory (ICMI), Vrije Universiteit Brussel, Brussels, Belgium Department of Nuclear Medicine, UZ Brussel, Brussels, Belgium; and
| | - Nick Devoogdt
- In Vivo Cellular and Molecular Imaging laboratory (ICMI), Vrije Universiteit Brussel, Brussels, Belgium Laboratory of Cellular and Molecular Immunology (CMIM), Vrije Universiteit Brussel, Brussels, Belgium
| | - Jo A Van Ginderachter
- Laboratory of Cellular and Molecular Immunology (CMIM), Vrije Universiteit Brussel, Brussels, Belgium Laboratory of Myeloid Cell Immunology (MCI), VIB, Brussels, Belgium
| | - Vicky Caveliers
- In Vivo Cellular and Molecular Imaging laboratory (ICMI), Vrije Universiteit Brussel, Brussels, Belgium Department of Nuclear Medicine, UZ Brussel, Brussels, Belgium; and
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Put S, Schoonooghe S, Devoogdt N, Schurgers E, Avau A, Mitera T, D'Huyvetter M, De Baetselier P, Raes G, Lahoutte T, Matthys P. SPECT imaging of joint inflammation with Nanobodies targeting the macrophage mannose receptor in a mouse model for rheumatoid arthritis. J Nucl Med 2013; 54:807-14. [PMID: 23447654 DOI: 10.2967/jnumed.112.111781] [Citation(s) in RCA: 70] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
UNLABELLED Rheumatoid arthritis (RA) is a chronic autoimmune disease occurring in approximately 1% of the worldwide population. The disease primarily affects the joints, where inflammatory cells, such as macrophages, invade the synovium and cause cartilage and bone destruction. Currently, it is difficult to efficiently diagnose and monitor early-stage RA. In this study, we investigated whether SPECT/micro-CT imaging with (99m)Tc-labeled Nanobodies directed against the macrophage mannose receptor (MMR) is a useful tool for monitoring and quantifying joint inflammation in collagen-induced arthritis (CIA), a mouse model for RA. The expression of MMR was analyzed on macrophages and osteoclasts generated in vitro and in cells obtained from various organs from mice with CIA. METHODS CIA was induced in DBA/1 mice by injection of collagen type II in complete Freund adjuvant, and cell suspensions from the inflamed joints and other organs were obtained. Macrophages and osteoclasts were generated in vitro from bone marrow cells. Expression of MMR was quantified by quantitative polymerase chain reaction and flow cytometry with specific Nanobodies and conventional antibodies. SPECT/micro-CT imaging was performed with (99m)Tc-labeled MMR and control Nanobodies. RESULTS MMR was highly expressed on macrophages and to a lesser extent on osteoclasts generated in vitro. In mice with CIA, MMR expression was detected on cells from the bone marrow, lymph nodes, and spleen. In synovial fluid of arthritic joints, MMR was expressed on CD11b(+)F4/80(+) macrophages. On in vivo SPECT/micro-CT imaging with consecutive injections of MMR and control Nanobodies, a strong MMR signal was seen in the knees, ankles, and toes of arthritic mice. Quantification of the SPECT imaging confirmed the specificity of the MMR signal in inflamed joints as compared with the control Nanobody. Dissection of the paws revealed an additional significant MMR signal in nonarthritic paws of affected mice (i.e., mice displaying symptoms of arthritis in other paws). CONCLUSION Our data show that MMR is expressed on macrophages in vitro and in vivo in synovial fluid of inflamed paws, whereas expression is relatively low in other tissues. The use of Nanobodies against MMR in SPECT/micro-CT imaging generates the possibility to track inflammatory cells in vivo in arthritic joints.
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Affiliation(s)
- Stéphanie Put
- Laboratory of Immunobiology, Rega Institute, Katholieke Universiteit Leuven, Leuven, Belgium
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