Background and aims: Management of chronic rejection is challenging since there are not sufficient preventive or therapeutic strategies. The rejection process leads to overexpression of ED-A(+) fibronectin (ED-A(+) Fn). The human antibody F8, specific to ED-A(+) Fn, may serve as a vehicle for targeted delivery of bioactive payloads, e.g. interleukin 10 (IL-10). The aim of this study was to investigate the therapeutic effects of the fusion protein F8-interleukin-10 (F8-IL10) in the process of chronic rejection development.
Methods: A heterotopic rat heart transplantation model was used to induce chronic rejection. For therapeutic interventions, the immunocytokines F8-humanIL10 (DEKAVIL), F8-ratIL10 as well as KSF-humanIL10 (irrelevant antigen-specificity) were used. Treatment was performed weekly for 10 weeks starting at day 7 after transplantation (1mg/animal).
Results: In the cardiac allografts, treatment with F8-huIL10 or F8-ratIL10 was associated with increased heart weights, a higher grade of chronic rejection, increased CIF, higher protein expression levels of alpha-smooth muscle actin (α-SMA), an augmented infiltration with inflammatory cells (CD4+, CD8+ and CD68+ cells) and higher serum levels of brain natriuretic peptide (BNP) compared to the control groups.
Conclusions: All observed treatment effects are transplantation-specific since the F8 antibody is specific to ED-A(+) Fn that is not expressed in healthy hearts. A clear targeting effect of F8-huIL10 as well as F8-ratIL10 could be proven. Against that background, a further study is needed to address the question, if F8-IL10 treatment is capable to reduce CAV and CIF starting at a time point when chronic rejection has fully developed (therapeutic approach).
Keywords: Antibody; Cardiac allograft rejection; Cardiac allograft vasculopathy; Cardiac remodelling; ED-A domain containing fibronectin; Interleukin-10; Interstitial fibrosis; Targeted therapy.
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