NEW DRUG FOR VASCULITIS: EFFICACY OF A RECOMBINANT SINGLE-CHAIN FRAGMENT VARIABLE REGION, VASSF

Background: Anti-neutrophil cytoplasmic autoantibodies (ANCA) associated vasculitis is a pauci-immune disease with the inflammation of the small blood vessels. The efficacies of antibody drugs for induction therapies of vasculitis vary among cases. Here, we developed a novel clone of a single chain Fv region (ScFv) with vasculitis-specific therapeutic potential. Materials and methods: The clone, termed VasSF, was selected from our Escherichia coil expression library of recombinant human ScFv based on the therapeutic efficacy in an SCG/Kj mouse model of MPO-ANCA-associated vasculitis (MAAV), such as improvement of the urinary score and decreased crescent formation in glomeruli, granulomatous in lung, MPO-ANCA biomarkers, the anti-moesin antibody, and some cytokine levels. Results: We identified vasculitis-associated apolipoprotein A-II (VA P2) as a target molecule of the clone and confirmed the independently-established VAP2 antibodies were also therapeutic in SCG/Kj mice. In MAAV, MPO-ANCA and cytokines stimulate neutrophils by facilitating heterodimer formation of VAP2 with apolipoprotein A-I in HDL. Conclusion: VasSF would constitute a novel antibody drug for vasculitis by suppressing the heterodimer formation of the apolipoproteins.