Anti-Malarial Drug Artesunate Attenuates Experimental Allergic Asthma via Inhibition of the Phosphoinositide 3-Kinase/Akt Pathway Chang Cheng1,3, W. Eugene Ho1,3, Fera Y. Goh1,3, Shou Ping Guan1,3, Li Ren Kong 1 , Wen-Qi Lai2, Bernard P. Leung 2 , W. S. Fred Wong1,3* 1 Departments of Pharmacology, Yong Loo Lin School of Medicine, National University Health System, Singapore, Singapore, 2 Departments of Physiology, Yong Loo Lin School of Medicine, National University Health System, Singapore, Singapore, 3 Immunology Program, Life Science Institute; National University of Singapore, Singapore Abstract Background: Phosphoinositide 3-kinase (PI3K)/Akt pathway is linked to the development of asthma. Anti-malarial drug artesunate is a semi-synthetic derivative of artemisinin, the principal active component of a medicinal plant Artemisia annua, and has been shown to inhibit PI3K/Akt activity. We hypothesized that artesunate may attenuate allergic asthma via inhibition of the PI3K/Akt signaling pathway. Methodology/Principal Findings: Female BALB/c mice sensitized and challenged with ovalbumin (OVA) developed airway inflammation. Bronchoalveolar lavage fluid was assessed for total and differential cell counts, and cytokine and chemokine levels. Lung tissues were examined for cell infiltration and mucus hypersecretion, and the expression of inflammatory biomarkers. Airway hyperresponsiveness was monitored by direct airway resistance analysis. Artesunate dose-dependently inhibited OVA-induced increases in total and eosinophil counts, IL-4, IL-5, IL-13 and eotaxin levels in bronchoalveolar lavage fluid. It attenuated OVA-induced lung tissue eosinophilia and airway mucus production, mRNA expression of E-selectin, IL- 17, IL-33 and Muc5ac in lung tissues, and airway hyperresponsiveness to methacholine. In normal human bronchial epithelial cells, artesunate blocked epidermal growth factor-induced phosphorylation of Akt and its downstream substrates tuberin, p70S6 kinase and 4E-binding protein 1, and transactivation of NF-kB. Similarly, artesunate blocked the phosphorylation of Akt and its downstream substrates in lung tissues from OVA-challenged mice. Anti-inflammatory effect of artesunate was further confirmed in a house dust mite mouse asthma model. Conclusion/Significance: Artesunate ameliorates experimental allergic airway inflammation probably via negative regulation of PI3K/Akt pathway and the downstream NF-kB activity. These findings provide a novel therapeutic value for artesunate in the treatment of allergic asthma. Citation: Cheng C, Ho WE, Goh FY, Guan SP, Kong LR, et al. (2011) Anti-Malarial Drug Artesunate Attenuates Experimental Allergic Asthma via Inhibition of the Phosphoinositide 3-Kinase/Akt Pathway. PLoS ONE 6(6): e20932. doi:10.1371/journal.pone.0020932 Editor: Marco Idzko, University Hospital Freiburg, Germany Received January 26, 2011; Accepted May 13, 2011; Published June 9, 2011 Copyright: 2011 Cheng et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Funding: This work was supported in part by an ARF grant R-184-000-130-112 from the National University of Singapore and by BMRC grants 06/1/21/19/443 and 09/1/21/19/595 from the BioMedical Research Council of Singapore (WSFW). The new grant 09/1/21/19/595 supported the authors’ revision experiments of the manuscript. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing Interests: The authors have declared that no competing interests exist. * E-mail: phcwongf@nus.edu.sg Introduction Allergic asthma is a chronic airway disorder characterized by airway inflammation, mucus hypersecretion, and airway hyperre- sponsiveness (AHR) [1]. Cumulative evidence revealed that these inflammatory responses are mediated by T-helper type 2 (Th2) cells together with mast cells, B cells and eosinophils, as well as a number of inflammatory cytokines and chemokines [1,2]. IL-4 is imperative for B cell isotype switching for the synthesis of immunoglobulin (Ig)E. Allergen-induced crosslinking of IgE- bound high affinity IgE receptors (FceRI) on the surface of mast cells leads to degranulation and activation of mast cells, and the release of inflammatory mediators like histamine, leukotrienes and cytokines, and immediate bronchoconstriction [3,4]. IL-5 is vital for the growth, differentiation, recruitment, and survival of eosinophils which contribute to inflammation and even airway remodeling in asthma [5]. IL-13 plays a pivotal role in the effector phase of Th2 responses such as eosinophilic inflammation, mucus hypersecretion, AHR and airway remodeling [6]. In addition, chemokines such as RANTES (regulated on activation, normal T cells expressed and secreted) and eotaxin are crucial to the delivery of eosinophils to the airways [7]. Airway eosinophilia, together with Th2 cytokines IL-4, IL-5 and IL-13, may ultimately contribute to AHR in asthma [8]. Artesunateis a semi-synthetic derivative of artemisinin, a sesquiterpenetrioxane lactone isolated from the herb Artemisia annua. This medicinal plant has been used as a remedy for fevers and chills for centuries in China [9]. Artemisinin derivatives including artesunate are anti-malarial drugs effective for both uncomplicated and severe malaria [9,10]. Besides, they have been shown to possess anti-cancer [11,12], anti-viral [13], and anti-inflammatory [14,15,16,17] activities. Artesunate has been reported to block the PLoS ONE | www.plosone.org 1 June 2011 | Volume 6 | Issue 6 | e20932