Johannes Wedel1, Patrick A M Jansen, Peter N M Botman, Floris P J T Rutjes, Joost Schalkwijk, Jan-Luuk Hillebrands. 1. 1 Pathology Section, Department of Pathology and Medical Biology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.2 Radboud Institute for Molecular Life Sciences, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands.3 Chiralix B.V., Nijmegen, The Netherlands.4 Institute for Molecules and Materials, Radboud University Nijmegen, Nijmegen, The Netherlands.
Abstract
BACKGROUND: Development of transplant vasculopathy is a major cause of graft loss and mortality in solid organ transplant recipients. Previous studies in mice have indicated that vanin-1, a member of the vanin protein family with pantetheinase activity, is possibly involved in neointima formation. Here, we investigated if RR6, a recently developed vanin inhibitor, could attenuate development of transplant vasculopathy. METHODS: Abdominal allogeneic aorta transplantation from Dark Agouti to Brown Norway rats was performed. Surface neointima was quantified 2 and 4 weeks after transplantation. Systemic vanin activity was measured, and allograft leukocyte infiltration, glutathione-synthesizing capacity, matrix metalloproteinase 9 expression and neointimal smooth muscle cell (SMC) proliferation were assessed by immunohistochemistry. In vitro, the effects of RR6 on SMC proliferation (water-soluble tetrazolium-1 assay) and cytokine-induced apoptosis (flow cytometry) were investigated. RESULTS: RR6 treatment significantly reduced systemic pantetheinase activity during the 4-week follow-up period. RR6 attenuated neointima formation 4 weeks after transplantation. Neointimal SMC proliferation and medial SMC matrix metalloproteinase 9 expression were not altered by RR6. However, RR6 significantly reduced neointimal macrophage influx that was accompanied by increased GCLC messenger RNA expression. In vitro, RR6 inhibited platelet-derived growth factor-induced SMC proliferation and protected SMCs from TNF-α-induced apoptosis. CONCLUSIONS: Pharmacological inhibition of vanin activity attenuates development of transplant vasculopathy. This was accompanied by reduced macrophage infiltration and increased glutathione-synthesizing capacity. In vitro, RR6 reduced SMC proliferation and apoptosis that was not confirmed in vivo. Further in-depth studies are warranted to reveal the underlying mechanism(s) of RR6-induced attenuation of transplant vasculopathy in vivo.
BACKGROUND: Development of transplant vasculopathy is a major cause of graft loss and mortality in solid organ transplant recipients. Previous studies in mice have indicated that vanin-1, a member of the vanin protein family with pantetheinase activity, is possibly involved in neointima formation. Here, we investigated if RR6, a recently developed vanin inhibitor, could attenuate development of transplant vasculopathy. METHODS: Abdominal allogeneic aorta transplantation from Dark Agouti to Brown Norway rats was performed. Surface neointima was quantified 2 and 4 weeks after transplantation. Systemic vanin activity was measured, and allograft leukocyte infiltration, glutathione-synthesizing capacity, matrix metalloproteinase 9 expression and neointimal smooth muscle cell (SMC) proliferation were assessed by immunohistochemistry. In vitro, the effects of RR6 on SMC proliferation (water-soluble tetrazolium-1 assay) and cytokine-induced apoptosis (flow cytometry) were investigated. RESULTS: RR6 treatment significantly reduced systemic pantetheinase activity during the 4-week follow-up period. RR6 attenuated neointima formation 4 weeks after transplantation. Neointimal SMC proliferation and medial SMC matrix metalloproteinase 9 expression were not altered by RR6. However, RR6 significantly reduced neointimal macrophage influx that was accompanied by increased GCLC messenger RNA expression. In vitro, RR6 inhibited platelet-derived growth factor-induced SMC proliferation and protected SMCs from TNF-α-induced apoptosis. CONCLUSIONS: Pharmacological inhibition of vanin activity attenuates development of transplant vasculopathy. This was accompanied by reduced macrophage infiltration and increased glutathione-synthesizing capacity. In vitro, RR6 reduced SMC proliferation and apoptosis that was not confirmed in vivo. Further in-depth studies are warranted to reveal the underlying mechanism(s) of RR6-induced attenuation of transplant vasculopathy in vivo.