1 SCIENTIFIC REPORTS | 7: 9919 | DOI:10.1038/s41598-017-09349-0 www.nature.com/scientificreports Src-dependent EGFR transactivation regulates lung infammation via downstream signaling involving ERK1/2, PI3Kδ/ Akt and NFκB induction in a murine asthma model Ahmed Z. El-Hashim 1 , Maitham A. Khajah 1 , Waleed M. Renno 2 , Rhema S. Babyson 1 , Mohib Uddin 3 , Ibrahim F. Benter 5 , Charles Ezeamuzie 4 & Saghir Akhtar 4 The molecular mechanisms underlying asthma pathogenesis are poorly characterized. In this study, we investigated (1) whether Src mediates epidermal growth factor receptor (EGFR) transactivation; (2) if ERK1/2, PI3Kδ/Akt and NF-κB are signaling efectors downstream of Src/EGFR activation; and (3) if upstream inhibition of Src/EGFR is more efective in downregulating the allergic infammation than selective inhibition of downstream signaling pathways. Allergic infammation resulted in increased phosphorylation of EGFR, Akt, ERK1/2 and IκB in the lung tissues from ovalbumin (OVA)- challenged BALB/c mice. Treatment with inhibitors of Src (SU6656) or EGFR (AG1478) reduced EGFR phosphorylation and downstream signaling which resulted in the inhibition of the OVA-induced infammatory cell infux in bronchoalveolar lavage fuid (BALF), perivascular and peribronchial infammation, fbrosis, goblet cell hyper/metaplasia and airway hyper-responsiveness. Treatment with pathway-selective inhibitors for ERK1/2 (PD89059) and PI3Kδ/Akt (IC-87114) respectively, or an inhibitor of NF-κB (BAY11-7085) also reduced the OVA-induced asthmatic phenotype but to a lesser extent compared to Src/EGFR inhibition. Thus, Src via EGFR transactivation and subsequent downstream activation of multiple pathways regulates the allergic airway infammatory response. Furthermore, a broader upstream inhibition of Src/EGFR ofers an attractive therapeutic alternative in the treatment of asthma relative to selectively targeting the individual downstream signaling efectors. Chronic airways infammation resulting in airway structural remodeling and the functional changes such as airway obstruction and airway hyperresponsivessness (AHR) are pathological hallmarks of asthma 1 . Airway epi- thelial cells (AEC) are increasingly being recognized as important players in the pathogenesis of asthma and are appropriately positioned at the interface between the host mucosal surface and environmental insults 2 . Tey secrete many bioactive mediators that regulate key infammatory responses, such as chemotaxis, cell activation, apoptosis and airway remodeling 2 . Epidermal growth factor (EGF) is an important epithelial-derived mediator that signals through EGF receptor (EGFR) and has been implicated in numerous disease such as cancer, cardio- vascular disease, chronic renal disease, diabetes and allergic diseases such as asthma 3–10 . Accumulating evidence indicates that EGFR-dependent signaling contributes to asthma pathophysiology 11 . For example, asthmatic airways show increased EGF and EGFR immunoreactivity in the bronchial epithe- lium, airway glands, smooth muscle and basement membrane and this correlates with subepithelial basement 1 Department of Pharmacology & Therapeutics, Faculty of Pharmacy, Kuwait City, Kuwait. 2 Department of Anatomy, Faculty of Medicine, Kuwait University, Kuwait City, Kuwait. 3 Respiratory, Infammation & Autoimmunity iMED, AstraZeneca R&D Gothenburg, Mölndal, Sweden. 4 Department of Pharmacology & Toxicology, Faculty of Medicine, Kuwait University, Kuwait City, Kuwait. 5 Faculty of Medicine, Eastern Mediterranean University, Famagusta, Cyprus. Correspondence and requests for materials should be addressed to A.Z.E.-H. (email: ahmed.elhashim@hsc.edu.kw) Received: 10 January 2017 Accepted: 26 July 2017 Published: xx xx xxxx OPEN