Artesunate Antagonizes Myofibroblast Markers and Fibrosis‐Associated Extracellular Matrix Protein Expression in Human Dermal Fibroblasts

Abstract

Artemisia annua, a plant species native to eastern Asia, is the source of a compound known as artemenisin that has been shown to have numerous medicinal effects. Artesunate, artemether and other chemical analogs of artemisinin, initially studied as antimalarial compounds, have also demonstrated cytostatic and cytotoxic effects in bacterial and cancer cells. Recently, artemisinin‐derivative compounds have also been demonstrated to attenuate fibrotic pathologies in various preclinical animal models, including those of hepatic and pulmonary fibrosis, but the mechanisms by which this inhibition of fibrosis occurs is not well‐understood. Given the ability of artemisinin derivatives, artesunate in particular, to antagonize various fibrotic pathologies, we decided to investigate the effects of artesunate on a process common to all fibrotic pathologies: the emergence of the highly secretory, contractile myofibroblast. We demonstrated by Western blot analysis that treatment of human dermal fibroblasts with artesunate results in a dose‐dependent decrease in expression of alpha smooth muscle actin (ɑ‐SMA), the de facto marker of fibroblast activation. Treatment of human dermal fibroblasts with artesunate also inhibited activation of fibroblasts mediated by the profibrotic cytokine TGF‐β1, which is largely responsible for differentiation of fibroblasts into myofibroblasts in vivo, and this antagonistic effect of artesunate towards fibroblast activation was consistent among multiple lines of primary human dermal fibroblasts. Further, immunofluorescent analysis for collagen I and collagen III demonstrated a marked reduction of both basal and TGF‐β1‐induced expression of extracellular matrix‐associated proteins. Understanding that fibrosis is the result of excessive differentiation of fibroblasts to myofibroblasts and accumulation of extracellular matrix proteins secreted by myofibroblasts, our data suggest that the antifibrotic mechanisms of artesunate in vivo may be mediated by their antagonistic effects towards myofibroblast phenotypes. We next plan to determine the direct mechanisms underlying the antagonism of artesunate towards fibroblast activation, paying particular attention to the hypotheses regarding the induction of myofibroblast apoptosis or cell cycle arrest, and the dependence of these phenotypes on the generation and activity of peroxide. With mechanistic data underpinning the effects of artesunate as an antagonist to profibrotic fibroblast activation, we hope that our work will enable progression towards the use of artesunate and other artemenisin‐derived compounds as therapies for fibrotic pathologies.Support or Funding InformationThis research was supported by a National Institutes of Health award to Tanja Dominko (grant # R01GM85456) and a National Science Foundation Integrative Graduate Education and Research Traineeship (grant number DGE 1144804) awarded to David Dolivo.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.