Oleuropein Rich Olive Leaf Curtails PM-Induced Allergic Airway Inflammation in Mouse

Abstract

PM is well-known as an asthma aggravating crucial factor frequently existing in air pollutants. Oleuropein rich olive leaf (Olea europea) extract (OLE) has been recog- nized as an effective therapeutic compound to suppress multiple health issues includ- ing inflammatory conditions in respiratory tract. This study was mainly focused on exploring beneficial suppressive abilities of olive leaf for asthma inflammations. Dur- ing this study, we developed a mouse model, by intraperitoneally injecting BALB/c mice with Ovalbumin (OVA) followed by challenge with PM (30mins/day) for 7 days consecutively in a nebulizer. Afterwards, the oral gavage of OLE and the positive con- trol, prednisone was done. As results, we observed that the OLE significantly de- creased eosinophil and basophil infiltration in blood and BALF, further inflammatory cell infiltration and more specifically eosinophil infiltration in both lung and trachea which were aberrantly increased by PM. OLE abated PM-induced TLR4 expression. This proceeds to reduced mRNA expression of pro-inflammatory cytokines by Th1 response (IL-1β, TNF-α and IFN-γ) and inflammatory cytokines by Th2 and Th17 re- sponse (IL-4, IL-10, IL-13, IL-17, and IL-22) resulting reduced mucus secretion in airway epithelia and reduced inflammatory conditions. In conclusion, the Olive leaf extract is proficient in alleviating inflammatory conditions by suppressing Th2 and Th17 cell activation, mast cell degranulation and mucus secretion in PM-induced al- lergic asthma by rectification of TLR4 induced signalling as a substituting conven- tional drug. Key words: Particulate matter, Olive leaf extract, Oleuropein, allergic asthma, Th2 and Th17 response