الفهرس 
AcknowledgmentOnly 14 pages are availabe for public view
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Abstract
”Non-steroidal anti-inflammatory drugs (NSAIDs) are commonly prescribed in primary care for their analgesic, antipyretic, and anti-inflammatory effects. Globally, Diclofenac (DCF) is among the most commonly used NSAIDs. Like other NSAIDs, DCF has been reported to decrease the glomerular filtration rate (GFR) and other kidney functions in a dose-dependent manner by inhibiting the biosynthesis of the protective PGs, ultimately leading to renal ischemia and necrosis. DCF-induced acute kidney injury (AKI) is characterized by glomerular dysfunction and acute tubular necrosis; however, the exact mechanisms are not fully investigated yet. Due to limited treatment approaches, effective and safe drug therapy to protect against such AKI is still needed. The overall goal of this study was to explore the potential of repurposing promising FDA-approved drugs to protect against DCF-induced acute nephrotoxicity in rats and investigate in depth the underlying mechanisms of action. The current study was divided into two work studies, where the DCF-induced AKI model was established by injection of DCF (50 mg/kg) for three consecutive days starting from day four and water deprivation from day five. The first study aimed to investigate the potential of the oral antiarthritic drug diacerein (DAR) to protect against DCF-induced AKI and address its targeted pathways, focusing on NLR family pyrin domain containing 3 (NLRP3) inflammasome and silent information regulator sirtuin 1 (SIRT1) signaling pathways as two different protective approaches. During study 1, two DAR-treated groups were adopted. The low-dose treated group involved oral administration of DAR (50 mg/kg) starting from day one to day six and was subjected to the DCF challenge as described above, while the high-dose treated group involved oral administration of DAR (100 mg/kg) starting from day one to day six and was also subjected to the DCF challenge. One day after the last DCF injection, the rats were anesthetized by intraperitoneal injection of thiopental sodium and euthanized by cervical dislocation, and blood samples were collected, and serum samples were isolated for subsequent biochemical analysis. Right kidney tissues were obtained and divided into two parts, one for homogenate preparation for subsequent ELISA and the other for Western blot analysis. Otherwise, the left kidney was isolated and kept in a 10% v/v buffered formalin solution for histopathology and immunohistochemical examination.The results of the first experiment of study 1 showed that DAR (50 and 100 mg/kg) markedly abrogated DCF-induced kidney dysfunction, decreasing serum creatinine (SCr), blood urea nitrogen, serum neutrophil gelatinase-associated lipocalin (NGAL), and serum kidney injury molecule 1 (KIM-1) levels and remarkably suppressing DCF-induced pathological changes in the renal tissue. Moreover, DAR treatment remarkably maintained renal redox balance and reduced the levels of pro-inflammatory biomarkers in the kidney. Mechanistically, DAR boosted nuclear factor erythroid 2-related factor 2 (Nrf2)/heme oxygenase 1 (HO-1) antioxidant and anti-inflammatory response in the kidney while suppressing renal toll like receptor 4 (TLR4)/ nuclear factor kappa B (NF-κB) and NLRP3/caspase-1 inflammatory signaling pathways. In addition, DAR markedly inhibited renal pyroptosis via targeting of gasdermin d (GSDMD) activation. Conclusively, the first experimental set of the study 1 confirmed that the interplay between Nrf2/HO-1 and TLR4/NF-κB/NLRP3/caspase-1 signaling pathways and pyroptotic cell death mediates DCF-induced AKI and reported that DAR has a dose-dependent renoprotective effect on DCF-induced AKI in rats. This effect is due to powerful antioxidant, anti-inflammatory, and anti-pyroptotic activities. On the other hand, the results of the second experimental set of the study 1 further revealed that DAR inhibited kidney dysfunction and suppressed oxidative stress, which were reflected in improved kidney architecture, including less tubular degeneration and necrosis in the renal cortex and medulla. Interestingly, DAR reduced renal hypoxia inducible factor 1alpha (HIF-1), tumor protein p53 (p53), and active caspase-3 expression and NF-κB activation while it increased renal SIRT1 expression. Conclusively, this experimental set addressed, for the first time, that DAR targets SIRT1/HIF-1α/NF-κB and SIRT1/p53 regulatory axes in a dose-dependent manner, showing anti-oxidative, anti-inflammatory, antinecrotic, and anti-apoptotic effects and protecting against DCF-induced AKI in rats.Regarding study 2, the aim was to test the ability of the oral anti-diabetic drug empagliflozin (EMPA) to target the NLRP3 inflammasome and the SIRT1 signaling pathways, protecting against DCF-induced AKI in rats. During this study, two EMPA-treated groups were adopted. The low-dose treated group involved oral administration of EMPA (10 mg/kg) starting from day one to day six and was subjected to the DCF challenge as described before, while the high-dose treated group involved oral administration of EMPA (20 mg/kg) starting from day one to day six and was also subjected to the DCF challenge. This study also involved different analysis methods, including biochemical analysis, histopathological and immunohistochemical analysis, ELISA, and Western blot analysis.EMPA (10 and 20 mg/kg) markedly abrogated DCF-induced kidney dysfunction, decreasing SCr, blood urea nitrogen, serum NGAL, and serum KIM-1 levels and remarkably suppressing DCF-induced pathological changes in the renal tissue and improved kidney architecture, including less tubular degeneration and necrosis in the renal cortex and medulla. Moreover, EMPA treatment remarkably suppressed oxidative stress, maintained renal redox balance and reduced the levels of pro-inflammatory biomarkers in the kidney. Mechanistically, EMPA boosted renal Nrf2/HO-1 response while suppressing renal TLR4/NF-κB and NLRP3/caspase-1 inflammatory signaling pathways. In addition, EMPA markedly inhibited renal pyroptosis via targeting of GSDMD activation. Moreover, EMPA reduced renal HIF-1, p53, and active caspase-3 expression and NF-κB activation as well as it increased renal SIRT1 expression.Conclusively, the results demonstrated that EMPA modulated the SIRT1/HIF-1α/NF-κB and TLR4/NF-κB/NLRP3/Caspase-1/IL-1/GSDMD regulatory axes, showing anti-oxidative, anti-inflammatory, antinecrotic, and anti-pyroptotic activities in DCF-induced AKI in rats.Considering the foregoing, DAR and EMPA are promising multi-target drugs that could be repurposed as protective agents against NSAID-induced AKI. However, further clinical studies are required to confirm their renoprotective potential.