Mechanistic perspective of morin protection against ketoprofen-induced gastric mucosal injury: Targeting HMGB1/RAGE/NF-κB, DJ-1/Nrf2/HO-1 and PI3K/mTOR pathways

Ketoprofen is a widely used NSAID which incurs gastric mucosal damage. The high mobility group Box 1 (HMGB1) protein is a DNA-binding protein which exerts robust inflammatory actions, however, its role in ketoprofen-induced gastric damage has not been explored. Additionally, no previous studies have linked HMGB1/RAGE/NF-κB, DJ-1/Nrf2/HO-1 and PI3K/mTOR pathways in ketoprofen-induced gastropathy. The current work aimed to explore the potential of morin, a flavonoid with marked antioxidant/anti-inflammatory actions, to protect against ketoprofen-evoked gastric damage. Moreover, the underlying mechanisms, including the impact of morin on HMGB1/RAGE/NF-κB, DJ-1/Nrf2/HO-1 and PI3K/mTOR pathways were addressed. Immunoblotting and ELISA were used to examine the expression of target signals. Morin (50 mg/kg, p. o.) attenuated the severity of gastric injury via lowering of ulceration/hemorrhage and macroscopic damage scores. Meanwhile, it attenuated the histopathologic aberrations/damage scores. In the context of inflammation, morin suppressed TNF-α and myeloperoxidase levels and enhanced IL-10. Furthermore, it inhibited HMGB1/RAGE/NF-κB pathway through downregulating HMGB1, RAGE and phospho-NF-κBp65 protein expression. Morin successfully inhibited gastric mucosal oxidative stress through lowering of lipid peroxides and boosting of reduced glutathione, glutathione peroxidase and total antioxidant capacity. It also boosted DJ-1/Nrf2/HO-1 pathway via upregulating DJ-1, Nrf2 and HO-1 protein expression. Additionally, morin counteracted the apoptotic events by downregulating the proapoptotic Bax and Bax/Bcl-2 ratio and augmenting the PI3K/mTOR pathway through upregulating PI3Kp110α and phospho-mTOR protein expression. In conclusion, the current study demonstrates, for the first time, that morin shows a promise for the management of ketoprofen-induced mucosal insult through targeting of HMGB1/RAGE/NF-κB, DJ-1/Nrf2/HO-1 and PI3K/mTOR pathways.

Keywords: HMGB1; Ketoprofen; Morin; Nrf2; Oxidative stress; PI3K.