OP0096 Adeno-associated virus vector-mediated interleukin-10 induction prevents vascular inflammation in a murine model of kawasaki disease
Authors: J Nakamura, S. Watanabe, H. Kimura, H. Mizukami, N. Nagi-Miura, N. Ohno, M. Takahashi, S. Minota
Journal: Annals of the Rheumatic Diseases (2018)

<h3>Background</h3> Kawasaki disease (KD), which is a common paediatric heart disease, is characterised by coronary vasculitis and subsequently aneurysm formation. Although the administration of intravenous immunoglobulin (IVIG) is effective for reducing aneurysm formation, approximately 10%–20% of patients are resistant to this therapy. Therefore, additional therapeutic approaches for treating the IVIG-resistant patients need to be developed. <i>Candida albicans</i> water-soluble fraction (CAWS)-induced vasculitis on coronary arteries and root of aorta is a frequently used murine model of KD. It has been considered that C-type lectin receptor Dectin-2 recognises CAWS. Recent studies showed CAWS-resistant strains of mice have higher serum IL-10 levels, which suggested that IL-10 might negatively regulate the development of CAWS-induced vasculitis. <h3>Objectives</h3> The aim of the study is to investigate the therapeutic effect of IL-10 in CAWS-induced vasculitis and elucidate the underlying pathogenesis of KD. <h3>Methods</h3> To induce the expression of IL-10<i> in vivo</i>, Adeno-associated virus (AAV) vectors encoding IL-10 were injected into DBA/2 mice. After the induction of IL-10, the mice were treated intraperitoneally with CAWS to induce vasculitis. Cardiac functions by echocardiography, inflammation and fibrosis by histological analyses, gene expression of inflammatory cytokines and fibrosis-related factors in the heart, and infiltrating cells by flow cytometry were assessed to evaluate the effects of IL-10. For <i>in vitro</i> study, bone marrow-derived macrophages (BMDM) were stimulated with CAWS in presence or absence of IL-10. TNF-α and IL-6 produced by the BMDM and Dectin-2 expressions on the BMDM were assessed. <h3>Results</h3> AAV-mediated induction of IL-10 significantly attenuated CAWS-induced cardiac functions (%FS and LVEDD). Histological analyses revealed that IL-10 markedly attenuated the vascular inflammation and fibrosis in the aortic root and coronary artery. Accordingly, increased gene expressions of inflammatory cytokines or fibrosis-related factors in the heart of CAWS-treated mice were significantly reduced by IL-10. The predominant infiltrating inflammatory cells in vascular walls were Dectin-2<sup>+</sup>CD11b<sup>+</sup> macrophages, and they were also decreased by IL-10. Furthermore, we showed GM-CSF induced Dectin-2 expression on BMDM, and the GM-CSF-treated BMDM produced TNF-α and IL-6 upon CAWS-stimulation. IL-10 had no effect on the Dectin-2 expression but significantly inhibited the production of the cytokines. Finally, the AAV-mediated induction of IL-10 prevented the expression of TNF-α and IL-6 in the heart of the mice treated with CAWS for 24 hours (at the early phase), but not GM-CSF and Dectin-2. These results suggest that GM-CSF mediates CAWS-induced vasculitis via Dectin-2 upregulation and IL-10 inhibits the downstream of GM-CSF and Dectin-2 signalling. <h3>Conclusions</h3> Our study has shown that IL-10 may have therapeutic application in the prevention of coronary vasculitis and aneurysm formation, and provided new insights into the mechanism underlying the pathogenesis of KD. <h3>Disclosure of Interest</h3> None declared