Repair Effects of KGF on Ischemia-Reperfusion–Induced Flap Injury via Activating Nrf2 Signaling

Fibroblast growth factor 7 alleviates myocardial infarction by improving oxidative stress via PI3Kα/AKT-mediated regulation of Nrf2 and HXK2

Acute myocardial infarction (MI) triggers oxidative stress, which worsen cardiac function, eventually leads to remodeling and heart failure. Unfortunately, effective therapeutic approaches are lacking. Fibroblast growth factor 7 (FGF7) is proved with respect to its proliferative effects and high expression level during embryonic heart development. However, the regulatory role of FGF7 in cardiovascular disease, especially MI, remains unclear. FGF7 expression was significantly decreased in a mouse model at 7 days after MI. Further experiments suggested that FGF7 alleviated MI-induced cell apoptosis and improved cardiac function. Mechanistic studies revealed that FGF7 attenuated MI by inhibiting oxidative stress. Overexpression of FGF7 actives nuclear factor erythroid 2-related factor 2 (Nrf2) and scavenging of reactive oxygen species (ROS), and thereby improved oxidative stress, mainly controlled by the phosphatidylinositol-3-kinase α (PI3Kα)/AKT signaling pathway. The effects of FGF7 were partly abrogated in Nrf2 deficiency mice. In addition, overexpression of FGF7 promoted hexokinase2 (HXK2) and mitochondrial membrane translocation and suppressed mitochondrial superoxide production to decrease oxidative stress. The role of HXK2 in FGF7-mediated improvement of mitochondrial superoxide production and protection against MI was verified using a HXK2 inhibitor (3-BrPA) and a HXKII VDAC binding domain (HXK2VBD) peptide, which competitively inhibits localization of HXK2 on mitochondria. Furthermore, inhibition of PI3Kα/AKT signaling abolished regulation of Nrf2 and HXK2 by FGF7 upon MI. Together, these results indicate that the cardio protection of FGF7 under MI injury is mostly attributable to its role in maintaining redox homeostasis via Nrf2 and HXK2, which is mediated by PI3Kα/AKT signaling.

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The expression of FGF7 in cardiomyocytes is decreased upon myocardial infarction (MI).

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Overexpression of FGF7 in the heart protects against cardiomyocytes apoptosis in a rodent model of MI.

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FGF7 attenuates MI-induced cardiac apoptosis via maintaining redox homeostasis.

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FGF7 maintains redox homeostasis by promoting mitochondrial HXK2 localization and Nrf2 nuclear translocation.

Keratinocyte growth factor ameliorates mycophenolate mofetil-induced intestinal barrier disruption in mice

OBJECTIVES

Although mycophenolate mofetil-induced (MMF) effectively improves long-term graft survival, the gastrointestinal (GI) side effects due to MMF-induced GI barrier damage limit its use in clinic. Keratinocyte growth factor (KGF) plays a crucial role in the intestinal protection and repair process. This study is designed to investigate the protective effect of KGF on MMF-induced intestinal mucosal barrier disruption and the potential mechanism.

METHODS

Thirty adult male C57BL/6 mice were assigned to one of the following groups: the MMF group, the MMF + KGF group, and the control group (n = 10 in each group). Animals in the MMF group received MMF (500 mg/kg) by gavage once daily for 15 consecutive days; animals in the MMF + KGF group received MMF (500 mg/kg) by gavage and KGF (5 mg/kg) by intraperitoneal injection once daily for 15 consecutive days; and control mice were given an equal volume of vehicle during the 15-day experimental period. In each group, intestinal paracellular permeability, histopathological changes and shifts in tight junction (TJ) protein were evaluated; further, proliferation and apoptosis of intestinal epithelial cells (IECs) were assessed, and intraepithelial lymphocytes (IELs) were isolated and analyzed by flow cytometry.

RESULTS

MMF caused intestinal mucosal injury, increased intestinal mucosal permeability, and altered expression of TJ protein. Moreover, MMF treatment inhibited IEC proliferation and increased apoptosis. MMF treatment resulted in a lower proportion of γδ⁺ T cells in IELs (γδ⁺ IELs). Conversely, concurrent administration of KGF with MMF effectively alleviated MMF-induced intestinal mucosal disruption, inhibited the increase in intestinal permeability, and maintained TJ protein expression. KGF also reversed the MMF-mediated inhibition of proliferation and promotion of apoptosis in IECs. In addition, KGF significantly enhanced the proportion of γδ⁺ IELs.

CONCLUSION

Our findings suggest that MMF induces intestinal epithelial barrier disruption in mice. KGF may play a protective role to ameliorate the disruption and provide a therapeutic intervention for gastrointestinal disorders induced by MMF.