Human Antibody Against C Domain of Tenascin-C Visualizes Murine Atherosclerotic Plaques Ex Vivo

Abstract

Targeting proteins that are overexpressed in atherosclerotic plaques may open novel diagnostic applications. The C domain of tenascin-C is absent from normal adult tissues but can be inserted during tumor progression or tissue repair into the molecule by alternative splicing. We tested the ability of the human antibody G11, specific to this antigen, to reveal murine atherosclerotic plaques ex vivo. The antibody directed against the extra domain B of fibronectin (L19) was used as a reference. Methods: We intravenously injected 125 I-labeled G11 or L19 antibodies into apolipoprotein E-deficient (ApoE 2/2 ) mice and harvested the aortae 4 or 24 h later. En face analyses of distal aortae and longitudinal sections of the aortic arch were performed to compare antibody uptake using autoradiography with plaque staining using oil red O. Plaque macrophages were detected by immunohistochemistry (anti-CD68 staining). Biodistribution of injected antibodies was investigated in aortae and blood at 4 and 24 h. Results: En face analyses revealed a significant correlation between radiolabeled G11 and fat-stained areas, increasing from 4 to 24 h, with a correlation coefficient of 0.92 (P , 0.0001) and an average signal-to-noise ratio of 104:1 at 24 h. Plaque imaging using L19 showed similar results (r 5 0.86; P , 0.0001; signal-tonoise ratio, 72:1 at 24 h). Uptake of radiolabeled antibodies in histologic sections colocalized with fat staining and activated macrophages in aortic plaques. Biodistribution analyses confirmed specific accumulation in aortic plaques as well as rapid blood pool clearance of the antibodies 24 h after injection. Immunofluorescence analyses revealed increased expression of tenascin and fibronectin isoforms in macrophage-rich plaques. Conclusion: The antibody G11, specific to the C domain of tenascin-C, visualizes murine atherosclerotic plaques ex vivo. In conjunction with the increased expression of the C domain of tenascin-C in macrophage-rich plaques, the colocalization of G11 uptake with activated macrophages, and the favorable target-to-blood ratio at 24 h, this antibody may be useful for molecular imaging of advanced atherosclerotic plaques in the intact organism.

Human monoclonal antibodies targeting carbonic anhydrase IX for the molecular imaging of hypoxic regions in solid tumours

“…In this study, we have used antibodies in SIP format (Borsi et al, 2002;Villa et al, 2008), as this format and similar mini-antibody formats have extensively been shown to offer distinctive advantages both for imaging applications (Leyton et al, 2009);von Lukowicz et al, 2007;Wei et al, 2008) and for radioimmunotherapy of cancer (Berndorff et al, 2005;Tijink et al, 2006;Kenanova et al, 2007;Sauer et al, 2009). Recent publications suggest that smaller high-affinity ligands (MW o 2000 Da) may enjoy a much more rapid tissue distribution compared with antibodies and antibody fragments (Low et al, 2008).…”

Comparative immunohistochemical staining of atherosclerotic plaques using F16, F8 and L19: Three clinical-grade fully human antibodies

“…Based on the immunohistochemical findings of this study and the extensive researches so far reported in the oncology field, F16 and similar antibodies should be able to selectively localize at sites of atherosclerosis [22][23]. It should thus become possible to investigate whether the antibody-based delivery of bioactive agents (e.g., drugs with cleavable linkers, pro-or anti-inflammatory cytokines, pro-or anti-coagulant agents) is beneficial or detrimental for patients with atherosclerosis.…”

“…A first goal of the study was to learn more about the expression of splice-isoforms of tenascin-C and of fibronectin, following preliminary reports from our group that had indicated antigen expression in atherosclerotic plaques of the ApoE -/-mouse model and in certain pathological specimens [22][23]. This information is important in consideration of the fact I and L19-TNF may have undetected plaques, for which it is reasonable to expect a pharmacological effect from the therapeutic agent.…”

“…Indeed, we have previously shown that monoclonal antibodies to splice isoforms of tenascin-C and fibronectin can selectively localize at atherosclerotic plaques in vivo following intravenous administration, using ApoE knock-out mice fed with a cholesterol-rich diet as animal model [22][23]. A direct comparative immunohistochemical analysis of the F16, F8 and L19 antibodies in human atherosclerotic plaques has not been reported so far.…”

Tenascin-C in cardiovascular remodeling: potential impact for diagnosis, prognosis estimation and targeted therapy

“…This is of certain interest since such antibodies can be used for targeted imaging as well as treatment strategies also in humans. 19,20 Interestingly, higher plasma levels of tenascin-C could be shown to be related with the complexity of coronary lesions after myocardial infarction, especially with total occlusion of the proximal left anterior descending artery and the extent of inflammation after myocardial infarction. 21 A very recent study published by Sakamoto and co-workers could evidence that serum tenascin-C levels are associated with rupture of coronary plaques in patients with acute coronary syndrome.…”