Background: Ischemia-reperfusion injury (IRI) is one of the major causes of postoperative renal allograft dysfunction, which is mainly the result of proinflammatory reactions including inflammatory responses, oxidative stress, and metabolic disorders. Resveratrol (RSV) plays an important role in protecting various organs in IRI because it reduces oxidative stress, lessens the inflammatory response, and exerts anti-apoptotic effects. The aim of this study was to demonstrate the renoprotective effect of RSV in inhibiting inflammatory responses, reducing oxidative stress, and decreasing cell apoptosis in vivo and in vitro. Methods: RSV was administered before renal ischemia and H2O2 induction. Serum and kidneys were harvested 24 h after reperfusion and NRK-52E cells were collected 4 h after H2O2 stimulation. Serum creatinine and blood urea nitrogen were used to assess renal function. Hematoxylin and eosin staining was performed to assess histological injury. Quantitative real-time PCR and enzyme-linked immunosorbent assay were used to assess proinflammatory cytokine expression. Oxidative stress–related proteins, such as Nrf2 and TLR4, were evaluated by western blot. Terminal deoxynucleotidyl transferase–mediated dUTP-biotin nick end labeling assay was used to detect apoptotic cells in tissues, and western blot was used to evaluate the expression of caspase-3, -8, and -9 in this study. Results: RSV inhibited inflammatory responses and improved renal function after renal IRI. Additionally, RSV decreased oxidative stress and reduced cell apoptosis by upregulating Nrf2 expression, downregulating the TLR4/NF-κB signaling pathway, and by decreasing caspase-3 activity and caspase cascades. Conclusion: Our study demonstrated the mechanisms underlying RSV renoprotection. We found that RSV exerts its greatest effects by blocking inflammatory responses, lowering oxidative stress, and reducing apoptosis via the Nrf2/TLR4/NF-κB pathway.
Erythropoietin (EPO) has been well recognized as a tissue protective agent by inhibiting apoptosis and inflammation. The tissue protective effect of EPO, however, only occurs at a high dosage, which may elicit severe side-effects at the meantime. Helix B surface peptide (HBSP), a novel peptide derived from the non-erythropoietic helix B of EPO, plays a specific role in tissue protection. We investigated effects of HBSP and the expression of its heterodimeric receptor, beta common receptor (βcR)/EPO receptor ( ), in a murine renal ischemia reperfusion (IR) injury model. HBSP significantly ameliorated renal dysfunction and tissue damage, decreased apoptotic cells in the kidney and reduced activation of caspase-9 and -3. The βcR/EPOR in the kidney was up-regulated by IR, but down-regulated by HBSP. Further investigation revealed that the expression and phosphorylation of Akt was dramatically enhanced by HBSP, but strongly reversed by wortmannin, the PI3K inhibitor. Wortmannin intervention improved βcR/EPOR expression, promoted caspase-9 and -3 activation, and increased active caspase-3 positive cells, while renal function and structure, and apoptotic cell counts scarcely changed. This result indicates a significant contribution of PI3K/Akt signaling pathway in the renoprotection of HBSP. The therapeutic effects of HBSP in this study suggest that HBSP could be a better candidate for renal protection.
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