Onion Bulb Extract Downregulates EGFR/ERK1/2/AKT Signaling Pathway and Synergizes With Steroids to Inhibit Allergic Inflammation

Abstract

The treatment of allergic diseases, such as asthma, with both conventional and novel therapies presents a challenge both in terms of optimal effect and cost. On the other hand, traditional therapies utilizing natural products such as onion have been in use for centuries with demonstrated efficacy and safety but without much knowledge of their mechanims of action. In this study, we investigated if the anti-inflammatory effects of onion bulb extract (OBE) are mediated via the modulation of the EGFR/ERK1/2/AKT signaling pathway, and whether OBE can synergise with steroids to produce greater anti-inflammatory actions. Treatment with OBE inhibited the house dust mite (HDM)-induced increased phosphorylation of EGFR, ERK1/2 and AKT which resulted in the inhibition of HDM-induced increase in airway cellular influx, perivascular and peribronchial inflammation, goblet cell hyper/metaplasia, and also inhibited ex vivo eosinophil chemotaxis. Moreover, treatment with a combination of a low dose OBE and low dose dexamethasone resulted in a significant inhibition of the HDM-induced cellular influx, perivascular and peribronchial inflammation, goblet cell hyper/metaplasia, and increased the pERK1/2 levels, whereas neither treatment, when given alone, had any discernible effects. This study therefore shows that inhibition of the EGFR/ERK1/2/AKT-dependent signaling pathway is one of the key mechanisms by which OBE can mediate its anti-inflammatory effects in diseases such as asthma. Importantly, this study also demonstrates that combining OBE with steroids results in significantly enhanced anti-inflammatory effects. This action may have important potential implications for future asthma therapy.

Treatment with onion bulb extract both prevents and reverses allergic inflammation in a murine model of asthma

“…In the allergic asthma model, our findings showed that OBE, administered 1 h prior to allergen challenge, significantly inhibited the allergen-induced increase in airway cellularity and histopathological changes, and also pro-inflammatory Th2 cytokines such as IL-4 and IL-5 but interestingly enhanced the levels of the anti-inflammatory cytokine IL-10 (El-Hashim et al. 2020 ). We also demonstrated that OBE inhibited the EGFR-dependent signaling pathways (El-Hashim et al.…”

“… 2019 ; El-Hashim et al. 2020 ), and also reverses established bowel inflammation (Khajah et al. 2020 ).…”

Effect of natural products use prior to infection with COVID-19 on disease severity and hospitalization: A self-reported cross-sectional survey study

“…39,47 In several studies, onion and its bioactive components reduced inflammation in the lungs and protected against various respiratory illnesses. [48][49][50] It is suggested that phytochemicals derived from onions can interfere with the function of the main protease of SARS-CoV-2. [51][52][53] In addition, anti-inflammatory diets that incorporate onions were recommended to reduce the severity of COVID-19.…”

Health‐promoting foods and food crops ofWest‐Africaorigin: The bioactive compounds and immunomodulating potential

“…They owe their medicinal properties to the presence of a wide range of bioactive compounds (Teshika et al, 2019). Over the years, studies have demonstrated the outstanding health benefits of onion as well as their bioactive compounds including anticancer (Tsuboki et al, 2016), antidiabetic (Jini & Sharmila, 2020), antimicrobial (Loredana et al, 2019), anti‐inflammatory (Jakaria et al, 2019), antiobesity (Lee et al, 2016), antioxidant (Ouyang et al, 2018), cardiovascular protective (Colina‐Coca et al, 2017), digestive system protective (Khajah et al, 2020), hepatorenal protective (Ahmed et al, 2017), immunomodulatory properties (Alkhedaide et al, 2017), neuroprotective (Salami et al, 2020), respiratory protective (El‐Hashim et al, 2020), and reproductive protective (Table 1) (Shokoohi et al, 2018).…”