Gentamicin-Induced Acute Kidney Injury in an Animal Model Involves Programmed Necrosis of the Collecting Duct

Renoprotective mechanisms of exercise training against acute and chronic renal diseases - A perspective based on experimental studies

Regular exercise training can lead to several health benefits, reduce mortality risk, and increase life expectancy. On the other hand, a sedentary lifestyle is a known risk factor for chronic diseases and increased mortality. Acute kidney injury (AKI) and chronic kidney disease (CKD) represent a significant global health problem, affecting millions of people worldwide. The progression from AKI to CKD is well-recognized in the literature, and exercise training has emerged as a potential renoprotective strategy. Thus, this article aims to review the main molecular mechanisms underlying the renoprotective actions of exercise training in the context of AKI and CKD, focusing on its antioxidative, anti-inflammatory, anti-apoptotic, anti-fibrotic, and autophagy regulatory effects. For that, bibliographical research was carried out in Medline/PubMed and Scielo databases. Although the pathophysiological mechanisms involved in renal diseases are not fully understood, experimental studies demonstrate that oxidative stress, inflammation, apoptosis, and dysregulation of fibrotic and autophagic processes play central roles in the development of tissue damage. Increasing evidence has suggested that exercise can beneficially modulate these mechanisms, potentially becoming a safe and effective non-pharmacological strategy for kidney health protection and promotion. Thus, the evidence base discussed in this review suggests that an adequate training program emerges as a valuable tool for preserving renal function in experimental animals, mainly through the production of antioxidant enzymes, nitric oxide (NO), irisin, IL-10, and IL-11. Future research can continue to explore these mechanisms to develop specific guidelines for the prescription of exercise training in different populations of patients with kidney diseases.

Nephroprotective Effect of the Leaf Extract of Ajuga remota Benth Against Gentamicin-Induced Nephrotoxicity in Swiss Albino Mice

Background

Drug-induced kidney injury was among the most common renal damages, from which gentamicin occupies around 25% of this injury. Gentamicin-induced renal damage is caused by increased free radicals with subsequent amplified inflammation. Ajuga remota leaf extract has many phytochemicals with antioxidant activities, which may improve gentamicin-induced renal damage. Thus, we aimed to investigate the nephroprotective effect of Ajuga remota leaf methanolic extract on gentamicin-induced nephrotoxicity in Swiss Albino Mice.

Methods

An experimental study design was used on 30 experimental mice randomly allocated in six groups: Group I, II, II, IV, and VI, among which mice were given only distilled water, only gentamicin, 600 mg/kg Ajuga remota leaf extract only, gentamicin along with 200 mg/kg extract, gentamicin with 400 mg/kg extract and gentamicin with 600 mg/kg extract, respectively. At the end of the experiment, the mice were sacrificed after being anaesthetized, and blood samples were collected through a cardiac puncture for renal function tests while the kidneys were removed for histopathological evaluation. The data were entered into Epidata version 4.6 and exported to SPSS version 25 for further analysis using one-way analysis of variance. Statistical significance was set at p < 0.05.

Results

Group II mice had significantly higher levels of serum creatinine and blood urea levels compared to group I and III. The body weight of the mice in group V and group VI showed a significant increase compared with Group II. Serum creatinine and blood urea levels were reduced significantly in the Ajuga remota leaf extract administered group of mice compared to group II. Abnormal kidney architectural changes were seen among group II mice; however, those changes were improved after administration of Ajuga remota leaf methanolic extract.

Conclusion

Methanol extract of Ajuga remota leaf provided effective protection against gentamicin-induced oxidative renal damage through its antioxidant effects.

The Antioxidant, Antibacterial and Cell-Protective Properties of Bioactive Compounds Extracted from Rowanberry (Sorbus aucuparia L.) Fruits In Vitro

Considering that Sorbus aucuparia fruits have been underutilized despite their tremendous potential, this study aimed to correlate the in vitro antioxidant, antibacterial and cell-protective abilities of fruit extracts derived from Sorbus aucuparia Romanian cultivars with their phytochemical composition. Therefore, following the preparation of ethanolic and carotenoid extracts, phytochemical screening was performed using UV-Vis and HPLC-DAD-ESI-MS methods. The antioxidant activity was analyzed using DPPH and FRAP tests. As the results revealed high contents of bioactive compounds (polyphenols 1.11 mg GAE/g DM, flavonoids 430.06 µg QE/g DM and carotenoids 95.68 µg/g DM) and an important antiradical action (DPPH 24.51 mg/mL and FRAP 0.016 µM TE/mL), we chose to further examine the fruits' biological properties. The antibacterial capacity was assessed employing agar well diffusion and broth microdilution techniques, with fruits displaying an intense activity against MSSA, MRSA and Enterococcus faecalis, but also E. coli and Pseudomonas aeruginosa. The cell-protective activity was analyzed on gentamicin-stressed renal cells, through MTT and Annexin V-FITC assays. Importantly, a significant increase in viability was registered on stressed cells following extract administration in low doses; nevertheless, viability was noticed to decline when exposed to elevated concentrations, potentially due to the cumulative actions of the extract and gentamicin. These findings offer novel light on the antibacterial activity of Sorbus aucuparia Romanian cultivars, as well as their cell-protective ability in renal cell injury.

Protective impacts of Artemisia annua against hepatic toxicity induced by gentamicin

The current study aimed to investigate the ameliorative effects of Artemisia annua (RA) extract on hepatic toxicity induced by gentamicin injection mice. Sixteen mice were divided into four groups; the control group received saline, the second group received 1% A. annua (RA) extract, third group injected 80 mg/kg gentamicin (GEN) intraperitoneally. The protective group treated with a combination of GEN and A. annua. All mice were treated for consecutive 15 days. Results confirmed that hepatic biomarkers (GPT, GCT, GOT, IL-6 and IL-1β), all were altered after gentamycin injection. The histological analysis confirmed that gentamycin injected mice showed portal vein congestion, micro and macro steatosis, and nuclear pyknosis of hepatocytes. The protective group showed intact central vein with less microsteatosis of some hepatocytes. Immunochemistry analysis confirmed that the immunoreactivity of COX-2 gene showed negative impact in examined groups. Unlike, NF-κB gene exhibited diffuse positive expression in the gentamicin group. TGF-β1 immunoreactivity was mild positive in control and highly upregulated in gentamicin treated mice, all were normalized after RA administration. In conclusion, RA showed a beneficial impact against gentamycin induced hepatic toxicity at cellular and biochemical levels by regulating proteins and inflammatory markers associated with liver activity.

Monoterpene linalool restrains gentamicin-mediated acute kidney injury in rats by subsiding oxidative stress, apoptosis, and the NF-κB/iNOS/TNF-α/IL-1β pathway and regulating TGF-β

The clinical use of gentamicin (GM) is restricted by its nephrotoxic effects. This study aimed for the first time to elucidate the ameliorative effects of the monoterpene linalool (Lin) against GM-mediated acute kidney injury in rats. A total of thirty-two rats were subdivided into four equal groups: control (saline), Lin (100 mg/kg/day), GM (100 mg/kg/day), and GM + Lin (100 and 100 mg/kg/day). Lin and GM were intraperitoneally administered for 12 days. Our results illustrated that Lin ameliorated GM-mediated renal histopathological abnormalities and reduced serum urea and creatinine levels in rats exposed to GM. Lin treatment mitigated oxidative stress in nephrotoxic animals as manifested by reducing serum and renal levels of malondialdehyde and increasing the activities of serum and renal glutathione peroxidase and renal catalase. Moreover, Lin markedly inhibited GM-triggered inflammation by downregulating NF-κB, iNOS, TNF-α, and IL-1β and reducing renal myeloperoxidase activity and nitric oxide levels. Interestingly, Lin repressed GM-induced apoptosis, as reflected by a marked downregulation of Bax and caspase-3 expression, concurrent with the upregulation of Bcl2 expression. Finally, Lin administration led to a significant downregulation of TGF-β expression in nephrotoxic animals. In summary, Lin ameliorated GM-mediated nephrotoxicity in rats, at least through its antioxidant, anti-inflammatory, and anti-apoptotic activities and by modulating TGF-β.

Lysosomal membrane stabilization by imipramine attenuates gentamicin-induced renal injury: Enhanced LAMP2 expression, down-regulation of cytoplasmic cathepsin D and tBid/cytochrome c/cleaved caspase-3 apoptotic signaling

Nephrotoxicity is a serious complication commonly encountered with gentamicin (GTM) treatment. Permeabilization of lysosomes with subsequent cytoplasmic release of GTM and cathepsins is considered a crucial issue in progression of GTM toxicity. This study was designed to evaluate the prospective defensive effect of lysosomal membrane stabilization by imipramine (IMP) against GTM nephrotoxicity in rats. GTM (30 mg/kg/h) was intraperitoneally administered over 4 h daily (120 mg/kg/day) for 7 days. IMP (30 mg/kg/day) was orally administered for 14 days; starting 7 days before and then concurrently with GTM. On 15th day, samples (urine, blood, kidney) were collected to estimate biomarkers of kidney function, lysosomal stability, apoptosis, and inflammation. IMP administration to GTM-treated rats ameliorated the disruption in lysosomal membrane stability induced by GTM. That was evidenced by enhanced renal protein expressions of LAMP2 and PI3K, but reduced cathepsin D cytoplasmic expression in kidney sections. Besides, IMP guarded against apoptosis in GTM-treated rats by down-regulation of the pro-apoptotic (tBid, Bax, cytochrome c) and the effector cleaved caspase-3 expressions, while the anti-apoptotic Bcl-2 expression was enhanced. Additionally, the inflammatory cascade p38 MAPK/NF-κB/TNF-α was attenuated in GTM + IMP group along with marked improvement in kidney function biomarkers, compared to GTM group. These findings were supported by the obvious improvement in histological architecture. Furthermore, in vitro enhancement of the antibacterial activity of GTM by IMP confers an additional benefit to their combination. Conclusively, lysosomal membrane stabilization by IMP with subsequent suppression of tBid/cytochrome c/cleaved caspase-3 apoptotic signaling could be a promising protective strategy against GTM nephrotoxicity.

Dihydromyricetin protects against gentamicin-induced nephrotoxicity via upregulation of renal SIRT3 and PAX2

AIM

Gentamicin-induced nephrotoxicity limits its widespread use as an effective antibacterial agent. Oxidative stress, inflammatory cytokines and apoptotic cell death are major participants in gentamicin-induced nephrotoxicity. We therefore, investigated whether dihydromyricetin (DHM), the antioxidant and anti-inflammatory flavonoid, could protect against the nephrotoxic effects of gentamicin.

METHODS

Male Wistar rats administrated gentamicin (100 mg/kg/day, i.p.) for 8 days. DHM (400 mg/kg, p.o.) was concurrently given with gentamicin for 8 days. Control group received the vehicle of DHM and gentamicin. Histopathological examinations, biochemical measurements and immunohistochemical analyses were done at the end of the study.

KEY FINDINGS

Treatment with DHM improved the gentamicin induced deterioration of renal functions; serum levels of urea, creatinine and cystatin-C as well as urinary levels of Kim-1 and NGAL, the sensitive indicators for early renal damage, were declined. Additionally, DHM abrogated gentamicin-induced changes in kidney morphology. These nephroprotective effects were possibly mediated via decreasing renal gentamicin buildup, activating the antioxidant enzymes GSH, SOD and CAT and decreasing lipid peroxidation and nitric oxide levels. Further, DHM suppressed renal inflammation and apoptotic cell death by decreasing the expression of nuclear factor-kappa B (NF-κB), TNF-alpha and caspase-3. These effects were correlated to the upregulation of renal SIRT3 expression. Also, DHM activated the regeneration and replacement of injured tubular cells with new ones via enhancing PAX2 expression.

SIGNIFICANCE

DHM is a promising therapeutic target that could prevent acute renal injury induced by gentamicin and help renal tubular cells to recover through its antioxidant, anti-inflammatory and antiapoptotic properties.

Targeting necroptosis in fibrosis

Necroptosis, a type of programmed cell death that resembles necrosis, is now known to depend on a different molecular mechanism from apoptosis, according to several recent studies. Many efforts have reported the possible influence of necroptosis in human disorders and concluded the crucial role in the pathophysiology of various diseases, including liver diseases, renal injuries, cancers, and others. Fibrosis is the most common end-stage pathological cascade of several chronic inflammatory disorders. In this review, we explain the impact of necroptosis and fibrosis, for which necroptosis has been demonstrated to be a contributing factor. We also go over the inhibitors of necroptosis and how they have been applied to fibrosis models. This review helps to clarify the role of necroptosis in fibrosis and will encourage clinical efforts to target this pathway of programmed cell death.

Potential Protective Effects of Ruta Chalepensis L. Extracts Against Gentamicin-Induced Nephrotoxicity via Reduction on Apoptotic, DNA Damage and Oxidative Stress Markers in Mice

In this study, the protective effects of Ruta chalepensis L. extracts on the extent of tissue damage in gentamicin-induced nephrotoxicity have been investigated. Ruta chalepensis L. extracts were prepared by subcritical water and ultrasound-assisted organic solvent extraction methods. Protective activity of Ruta chalepensis L. extracts on Gentamicin-induced nephrotoxicity is investigated by apoptotic, DNA damage, oxidative stress markers and evaluating histopathological in kidney tissue of mice. Gentamicin significantly increased Caspase-3 and -8 activities, NO levels, serum creatinine and BUN, while 8-OHdG and MDA levels were significantly decreased with Ruta chalepensis L. extract treatment. In addition, Ruta chalepensis L. extracts treatment significantly increased CAT and SOD activities. Histopathological alterations in Gentamicin group were significantly diminished by application of Ruta chalepensis L. extracts. These results suggest that treatment with Ruta chalepensis L. extracts may ameliorate renal dysfunction and structural damage through the reduction of oxidative stress and apoptosis in the kidney.

Further insights into the impact of rebamipide on gentamicin-induced nephrotoxicity in rats: modulation of SIRT1 and β-catenin/cyclin D1 pathways

Gentamicin (GM) is an effective antibiotic administered to treat acute Gram-negative infections. Nevertheless, its clinical application is limited due to nephrotoxicity. Therefore, our research aimed to investigate the potential renoprotective impact of rebamipide (RBM), a gastroprotective drug, on GM-induced kidney damage in rats, as well as putative nephroprotective pathways. RBM was orally administered (100 mg/kg/d for 14 d) commencing 7 d before the administration of GM (100 mg/kg/d, intraperitoneally). Nephrotoxicity was elucidated, and the silent information regulator 1 (SIRT1) and β-catenin/cyclin D1 pathways were assessed. GM induced a significant elevation in the serum levels of creatinine, blood urea nitrogen (BUN), and kidney injury molecule-1 (KIM-1), as well as the relative kidney index. In addition, GM increased lipid peroxidation and lowered total antioxidant capacity (TAC) level and superoxide dismutase (SOD) activity. GM administration also demonstrated a significant amplification in tumor necrosis factor-alpha (TNF-α), interleukin-1 beta (IL-1β), nuclear factor-κappa B p65 (NF-κB p65), p38 mitogen-activated protein kinase (p38 MAPK), and caspase-3 kidney levels, as well as B-cell lymphoma 2 (Bcl-2)-associated X protein (Bax)/Bcl-2 ratio. Notably, RBM treatment amended all these changes induced by GM. Furthermore, the potential role of SIRT1 and β-catenin-dependent signaling pathways in GM-induced renal injury was assessed. Our findings showed that GM-treated rats demonstrated a substantial decrease in SIRT1, nuclear factor E2-related factor 2 (Nrf2), and heme oxygenase-1 (HO-1) along with an increase in β-catenin, forkhead box O-3a (FOXO-3a), and cyclin D1 protein expressions. RMB treatment markedly attenuated the deterioration caused by GM on these pathways. Additionally, RBM alleviated the GM-induced deleterious kidney tissue histopathology. In conclusion, our findings have verified that RBM can halt GM-induced renal injury by partly modulating SIRT1 and β-catenin pathways.

From Physiology to Pathology: The Role of Mitochondria in Acute Kidney Injuries and Chronic Kidney Diseases

Background

Renal diseases remain an increasing public health issue affecting millions of people. The kidney is a highly energetic organ that is rich in mitochondria. Numerous studies have demonstrated the important role of mitochondria in maintaining normal kidney function and in the pathogenesis of various renal diseases, including acute kidney injuries (AKIs) and chronic kidney diseases (CKDs).

Summary

Under physiological conditions, fine-tuning mitochondrial energy balance, mitochondrial dynamics (fission and fusion processes), mitophagy, and biogenesis maintain mitochondrial fitness. While under AKI and CKD conditions, disruption of mitochondrial energy metabolism leads to increased oxidative stress. In addition, mitochondrial dynamics shift to excessive mitochondrial fission, mitochondrial autophagy is impaired, and mitochondrial biogenesis is also compromised. These mitochondrial injuries regulate renal cellular functions either directly or indirectly. Mitochondria-targeted approaches, containing genetic (microRNAs) and pharmaceutical methods (mitochondria-targeting antioxidants, mitochondrial permeability pore inhibitors, mitochondrial fission inhibitors, and biogenesis activators), are emerging as important therapeutic strategies for AKIs and CKDs.

Key Messages

Mitochondria play a critical role in the pathogenesis of AKIs and CKDs. This review provides an updated overview of mitochondrial homeostasis under physiological conditions and the involvement of mitochondrial dysfunction in renal diseases. Finally, we summarize the current status of mitochondria-targeted strategies in attenuating renal diseases.

Animal Models of Kidney Disease: Challenges and Perspectives

Kidney disease is highly prevalent and affects approximately 850 million people worldwide. It is also associated with high morbidity and mortality, and current therapies are incurable and often ineffective. Animal models are indispensable for understanding the pathophysiology of various kidney diseases and for preclinically testing novel remedies. In the last two decades, rodents continue to be the most used models for imitating human kidney diseases, largely because of the increasing availability of many unique genetically modified mice. Despite many limitations and pitfalls, animal models play an essential and irreplaceable role in gaining novel insights into the mechanisms, pathologies, and therapeutic targets of kidney disease. In this review, we highlight commonly used animal models of kidney diseases by focusing on experimental AKI, CKD, and diabetic kidney disease. We briefly summarize the pathological characteristics, advantages, and drawbacks of some widely used models. Emerging animal models such as mini pig, salamander, zebrafish, and drosophila, as well as human-derived kidney organoids and kidney-on-a-chip are also discussed. Undoubtedly, careful selection and utilization of appropriate animal models is of vital importance in deciphering the mechanisms underlying nephropathies and evaluating the efficacy of new treatment options. Such studies will provide a solid foundation for future diagnosis, prevention, and treatment of human kidney diseases.

The potential role of upregulated PARP-1/RIPK1 expressions in amikacin-induced oxidative damage and nephrotoxicity in Wistar rats

This study aimed to investigate the gene expression levels associated with nephrotoxic action of amikacin, as well as the post-treatment effect of diuretics on its nephrotoxic effects. Sixty male rats were divided equally into six groups, including the control group receiving saline intra-peritoneally (ip), and the five treated groups including therapeutic and double therapeutic dose groups, injected ip (15 and 30 mg/kg b.wt./day) respectively for seven days, and another two rat groups treated as therapeutic and double therapeutic dose groups then administered the diuretic orally for seven days and the last group received amikacin ip at a rate of 15 mg/kg/day for seven days, then given free access to water without diuretics for another seven days and was kept as a self-recovery group. Amikacin caused kidney injury, which was exacerbated by the double therapeutic dose, as evidenced by abnormal serum renal injury biomarkers, elevated renal MDA levels, inhibition of renal catalase and SOD enzyme activities, with renal degenerative and necrotic changes. Moreover, comet assays also revealed renal DNA damage. Interestingly, amikacin administration markedly elevated expression levels of the PARP-1, RIP1, TNF-α, IL-1β, and iNOS genes as compared to the control group. However, compared to the self-recovery group, post-amikacin diuretic treatment modulates amikacin-induced altered findings and alleviates amikacin nephrotoxic effects more efficiently. Our findings suggested the potential role of PARP-1 and RIPK1 expressions that influence the expression of proinflammatory cytokines such as IL-1β and TNF-α by exaggerating oxidative stress which may contribute to the pathogenesis of amikacin-induced nephrotoxicity.

Vitamin A and retinoid signaling in the kidneys

Vitamin A (VA, retinol) and its metabolites (commonly called retinoids) are required for the proper development of the kidney during embryogenesis, but retinoids also play key roles in the function and repair of the kidney in adults. Kidneys filter 180-200 liters of blood per day and each kidney contains approximately 1 million nephrons, which are often referred to as the 'functional units' of the kidney. Each nephron consists of a glomerulus and a series of tubules (proximal tubule, loop of Henle, distal tubule, and collecting duct) surrounded by a network of capillaries. VA is stored in the liver and converted to active metabolites, most notably retinoic acid (RA), which acts as an agonist for the retinoic acid receptors ((RARs α, β, and γ) to regulate gene transcription. In this review we discuss some of the actions of retinoids in the kidney after injury. For example, in an ischemia-reperfusion model in mice, injury-associated loss of proximal tubule (PT) differentiation markers occurs, followed by re-expression of these differentiation markers during PT repair. Notably, healthy proximal tubules express ALDH1a2, the enzyme that metabolizes retinaldehyde to RA, but transiently lose ALDH1a2 expression after injury, while nearby myofibroblasts transiently acquire RA-producing capabilities after injury. These results indicate that RA is important for renal tubular injury repair and that compensatory mechanisms exist for the generation of endogenous RA by other cell types upon proximal tubule injury. ALDH1a2 levels also increase in podocytes, epithelial cells of the glomeruli, after injury, and RA promotes podocyte differentiation. We also review the ability of exogenous, pharmacological doses of RA and receptor selective retinoids to treat numerous kidney diseases, including kidney cancer and diabetic kidney disease, and the emerging genetic evidence for the importance of retinoids and their receptors in maintaining or restoring kidney function after injury. In general, RA has a protective effect on the kidney after various types of injuries (eg. ischemia, cytotoxic actions of chemicals, hyperglycemia related to diabetes). As more research into the actions of each of the three RARs in the kidney is carried out, a greater understanding of the actions of vitamin A is likely to lead to new insights into the pathology of kidney disorders and the development of new therapies for kidney diseases.

Renal mitochondrial restoration by gymnemic acid in gentamicin-mediated experimental nephrotoxicity: evidence from serum, kidney and histopathological alterations

Background: Nephrotoxicity refers to the toxigenic impact of compounds and medications on kidney function. There are a variety of drug formulations, and some medicines that may affect renal function in multiple ways via nephrotoxins production. Nephrotoxins are substances that are harmful to the kidneys. Purpose: This investigation examines the renoprotective effect of gymnemic acid (GA) on Wistar rats in gentamicin-induced nephrotoxicity by analyzing serum, kidney, and histopathological markers. Study-design/methods: The current study investigated the protective effect of GA at doses of 20, 40, and 60 mg/kg against gentamicin-induced nephrotoxicity in rats. Vitamin E was administered to compare the antioxidant capacity and efficacy of GA. In addition to the treatment groups, 100 mg/kg of gentamicin was administered intraperitoneal for 14 days. At the end of the study protocol, kidney homogenate, blood, and serum were evaluated biochemically. Serum creatinine, blood urea, glomerular filtration rate (GFR), mitochondrial dysfunctions, inflammatory cytokines, and renal oxidative stress were examined to assess gentamicin-induced nephrotoxicity. In addition, the impact of GA on the above-mentioned nephrotoxic markers were evaluated and further confirmed by histological analysis. Results: This study establishes a correlation between antibiotic use, especifically aminoglycosides and acute renal failure. The research demonstrates the nephrotoxic effects of aminoglycosides, inducing mitochondrial ETC-complex dysfunction, and renal tissue inflammation in experimental rats. GA's antioxidant properties restored renal oxidative stress markers, reducing kidney inflammation and injury. Histopathological analysis revealed a significant reduction in renal injury with GA treatment. Additionally, GA demonstrated greater efficacy than Vitamin E in restoring antioxidant potential and mitochondrial enzymes. Conclusion: Consequently, our findings imply that long-term use of GA may be a suitable therapeutic strategy for reducing aminoglycoside toxicity. The current study suggests GA's potential in treating gentamicin-induced nephrotoxicity and acute renal failure, meriting further investigation using advanced techniques.

Gentamicin alleviates cholestatic liver injury by decreasing gut microbiota-associated bile salt hydrolase activity in rats

Intrahepatic cholestasis lacks effective therapeutic drugs. The gut microbiota-associated bile salt hydrolases (BSH) may be a potential therapeutic target. In this study, oral administration of gentamicin (GEN) decreased the serum and hepatic levels of total bile acid in 17α-ethynylestradiol (EE)-induced cholestatic male rats, significantly improved the serum levels of hepatic biomarkers and reversed the histopathological changes in the liver. In healthy male rats, the serum and hepatic levels of total bile acid were also decreased by GEN, the ratio of primary to secondary bile acids, and conjugated to unconjugated bile acids was significantly increased, and the urinary excretion of total bile acid was elevated. 16S rDNA sequencing of the ileal contents revealed that GEN treatment substantially reduced the abundance of Lactobacillus and Bacteroides both of which expressed BSH. Consistently, BSH activity analysis by the generation of d5-chenodeoxycholic acid from d5-taurochenodeoxycholic acid in situ showed BSH was significantly inhibited in the ileal contents of rats treated with GEN. This finding led to an increased proportion of hydrophilic conjugated bile acids and facilitated the urinary excretion of total bile acids, thereby decreasing serum and hepatic total bile acids and reversing liver injury related to cholestasis. Our results provide important evidence that BSH can be a potential drug target for treating cholestasis.

Downregulation of G protein-coupled receptor kinase 4 protects against kidney ischemia-reperfusion injury

Ischemia/reperfusion injury of the kidney is associated with high morbidity and mortality, and treatment of this injury remains a challenge. G protein-coupled receptor kinase 4 (GRK4) plays a vital role in essential hypertension and myocardial infarction, but its function in kidney ischemia/reperfusion injury remains undetermined. Among the GRK subtypes (GRK2-6) expressed in kidneys, the increase in GRK4 expression was much more apparent than that of the other four GRKs 24 hours after injury and was found to accumulate in the nuclei of injured mouse and human renal tubule cells. Gain- and loss-of-function experiments revealed that GRK4 overexpression exacerbated acute kidney ischemia/reperfusion injury, whereas kidney tubule-specific knockout of GRK4 decreased injury-induced kidney dysfunction. Necroptosis was the major type of tubule cell death mediated by GRK4, because GRK4 significantly increased receptor interacting kinase (RIPK)1 expression and phosphorylation, subsequently leading to RIPK3 and mixed lineage kinase domain-like protein (MLKL) phosphorylation after kidney ischemia/reperfusion injury, but was reversed by necrostatin-1 pretreatment (an RIPK1 inhibitor). Using co-immunoprecipitation, mass spectrometry, and siRNA screening studies, we identified signal transducer and activator of transcription (STAT)1 as a GRK4 binding protein, which co-localized with GRK4 in the nuclei of renal tubule cells. Additionally, GRK4 phosphorylated STAT1 at serine 727, whose inactive mutation effectively reversed GRK4-mediated RIPK1 activation and tubule cell death. Kidney-targeted GRK4 silencing with nanoparticle delivery considerably ameliorated kidney ischemia/reperfusion injury. Thus, our findings reveal that GRK4 triggers necroptosis and aggravates kidney ischemia/reperfusion injury, and its downregulation may provide a promising therapeutic strategy for kidney protection.

Parthenolide Phytosomes Attenuated Gentamicin-Induced Nephrotoxicity in Rats via Activation of Sirt-1, Nrf2, OH-1, and NQO1 Axis

Nephrotoxicity is a serious complication that limits the clinical use of gentamicin (GEN). Parthenolide (PTL) is a sesquiterpene lactone derived from feverfew with various therapeutic benefits. However, PTL possesses low oral bioavailability. This study aimed to evaluate the therapeutic protective effects of PTL-phytosomes against GEN-induced nephrotoxicity in rats. The PTL was prepared as phytosomes to improve the pharmacological properties with a particle size of 407.4 nm, and surface morphology showed oval particles with multiple edges. Rats were divided into six groups: control, nano-formulation plain vehicle, PTL-phytosomes (10 mg/kg), GEN (100 mg/kg), GEN + PTL-phytosomes (5 mg/kg), and GEN + PTL-phytosomes (10 mg/kg). The administration of PTL-phytosomes alleviated GEN-induced impairment in kidney functions and histopathological damage, and decreased kidney injury molecule-1 (KIM-1). The anti-oxidative effect of PTL-phytosomes was demonstrated by the reduced malondialdehyde (MDA) concentration and increased superoxide dismutase (SOD) and catalase (CAT) activities. Furthermore, PTL-phytosomes treatment significantly enhanced sirtuin 1 (Sirt-1), nuclear factor erythroid-2-related factor-2 (Nrf2), NAD(P)H quinone dehydrogenase 1 (NQO1), and heme oxygenase-1 (HO-1). Additionally, PTL-phytosomes treatment exhibited anti-inflammatory and anti-apoptotic properties in the kidney tissue. These findings suggest that PTL-phytosomes attenuate renal dysfunction and structural damage by reducing oxidative stress, inflammation, and apoptosis in the kidney.

Low nephron endowment increases susceptibility to renal stress and chronic kidney disease

Preterm birth results in low nephron endowment and increased risk of acute kidney injury (AKI) and chronic kidney disease (CKD). To understand the pathogenesis of AKI and CKD in preterm humans, we generated potentially novel mouse models with a 30%-70% reduction in nephron number by inhibiting or deleting Ret tyrosine kinase in the developing ureteric bud. These mice developed glomerular and tubular hypertrophy, followed by the transition to CKD, recapitulating the renal pathological changes seen in humans born preterm. We injected neonatal mice with gentamicin, a ubiquitous nephrotoxic exposure in preterm infants, and detected more severe proximal tubular injury in mice with low nephron number compared with controls with normal nephron number. Mice with low nephron number had reduced proliferative repair with more rapid development of CKD. Furthermore, mice had more profound inflammation with highly elevated levels of MCP-1 and CXCL10, produced in part by damaged proximal tubules. Our study directly links low nephron endowment with postnatal renal hypertrophy, which in this model is maladaptive and results in CKD. Underdeveloped kidneys are more susceptible to gentamicin-induced AKI, suggesting that AKI in the setting of low nephron number is more severe and further increases the risk of CKD in this vulnerable population.

Low-intensity pulsed ultrasound (LIPUS) switched macrophage into M2 phenotype and mitigated necroptosis and increased HSP 70 in gentamicin-induced nephrotoxicity

BACKGROUND AND AIM

Many attempts to control acute kidney injury (AKI) have failed due to a lack of understanding of its pathophysiological key components. Macrophages are a crucial determinant of AKI, which can be categorized functionally as M1 pro-inflammatory and M2 anti-inflammatory macrophages. Low-intensity pulsed ultrasound (LIPUS) is currently being investigated as an immune modulator. The present study aimed to explore the potential effects of LIPUS on the polarization of renal macrophages, as well as the possible interplay between macrophage polarization and necroptosis in gentamicin-induced acute kidney injury.

METHOD

All rats were randomly allocated into one of four groups: control, LIPUS-treated control, gentamicin acute kidney (GM-AKI), and LIPUS-treated GM-AKI. Renal functions, macrophage polarization, necroptosis, and heat shock protein-70 (HSP70) were analyzed using real-time reverse-transcriptase-polymerase chain reaction (rT-PCR), Western Blot, Enzyme-linked immunosorbent assay (ELISA) as well as immunohistological analysis.

RESULTS

we found that LIPUS markedly inhibited the expressions of M1 macrophage-related genes and promoted significantly the expression of M2 macrophages related genes. This was accompanied by an inhibition of necroptosis and a marked reduction of HSP-70, resulting in a reversal of gentamicin-induced renal alteration.

CONCLUSION

Functional switching of macrophage responses from M1 into M2 seems to be a potential approach to ameliorate necroptosis as well as HSP-70 by low pulsed ultrasound waves in GM-AKI.

Bufalin alleviates acute kidney injury by regulating NLRP3 inflammasome-mediated pyroptosis

BACKGROUND

Recently, there has been an increasing clinical incidence of acute kidney injury (AKI), which rapidly declines renal function and leads to massive tubular cell necrosis. Pyroptosis is an inflammatory process of cell death that is more rapid than apoptosis, which is accompanied by a massive release of inflammasome activation. In the study, we aim to explore whether Bufalin regulates the AKI through the pyroptosis pathway.

METHODS

We have established gentamicin (GM)-induced AKI animal and cell models to simulate the pathological conditions of kidney injury. The expression of renal injury and pyroptosis-related indicators were detected by western blot. PAS staining and IHC staining were used to analyze renal function. CCK-8 assay was performed to detect cell viability after AKI with different treatments. TUNEL staining, flow cytometry and immunofluorescence assays were performed to measure pyroptosis.

RESULTS

After intraperitoneal injection of GM in rats, renal function was significantly decreased, along with a significant increase of damaged and necrotic cells as suggested by renal tubular epithelial tissue sections. In addition, there was an increase in the pyroptosis-related markers expression and pyroptosis-induced cell death. Consistently, studies in vitro found that GM significantly induced pyroptosis and its associated protein expression in NRK52e cells. Whereas, the administration of Bufalin reversed these effects of GM in vivo and in vitro. Further, we found that Nigericin (NLRP3 agonist) could reversed the effects of bufalin on GM-induced pyroptosis.

CONCLUSION

Bufalin attenuates pyroptosis generated AKI by inhibiting NLRP3 inflammasome.

Role of necroptosis in kidney health and disease

Cell death, particularly that of tubule epithelial cells, contributes critically to the pathophysiology of kidney disease. A body of evidence accumulated over the past 15 years has ascribed a central pathophysiological role to a particular form of regulated necrosis, termed necroptosis, to acute tubular necrosis, nephron loss and maladaptive renal fibrogenesis. Unlike apoptosis, which is a non-immunogenic process, necroptosis results in the release of cellular contents and cytokines, which triggers an inflammatory response in neighbouring tissue. This necroinflammatory environment can lead to severe organ dysfunction and cause lasting tissue injury in the kidney. Despite evidence of a link between necroptosis and various kidney diseases, there are no available therapeutic options to target this process. Greater understanding of the molecular mechanisms, triggers and regulators of necroptosis in acute and chronic kidney diseases may identify shortcomings in current approaches to therapeutically target necroptosis regulators and lead to the development of innovative therapeutic approaches.

Expression of ER stress markers (GRP78 and PERK) in experimental nephrotoxicity induced by cisplatin and gentamicin: roles of inflammatory response and oxidative stress

This study aimed to establish the relationship between two endoplasmic reticulum (ER) stress proteins, glucose-regulated protein 78 (GRP78/BiP) and PKR-like endoplasmic reticulum kinase (PERK), and oxidative stress markers in cisplatin (CIS)-induced and gentamicin (GEN)-induced nephrotoxicity.The study consisted of five groups: control (saline solution only), CIS D2 (2.5 mg/kg for 2 days), CIS D7 (2.5 mg/kg for 7 days), GEN D2 (160 mg/kg for 2 days), and GEN D7 (160 mg/kg for 7 days). All rats were sacrificed 24 h after the last injection for standard clinical chemistry, and ultrastructural and histological evaluation of the kidney.CIS and GEN increased blood urea nitrogen (BUN) and serum creatinine (Cr) levels, as well as total oxidant status (TOS), while decreasing total antioxidant status (TAS) level in CIS D7 and GEN D7 groups. Histopathological and ultrastructural findings were also consistent with renal tubular damage. In addition, expression of markers of renal inflammation (tumor necrosis factor-α (TNF-α) and interleukin 1β (IL-1β)) and ER stress markers (GRP78 and PERK) was significantly increased in the kidney tissue of rats treated with CIS and GEN for 7 days.These findings suggest that CIS and GEN administration for 7 days aggravates nephrotoxicity through the enhancement of oxidative stress, inflammation, and ER stress-related markers. As a result, the recommended course of action is to utilize CIS and GEN as an immediate but brief induction therapy, stopping after 3 days and switching to other drugs instead.

Cocktail of isobavachalcone and curcumin enhance eradication of Staphylococcus aureus biofilm from orthopedic implants by gentamicin and alleviate inflammatory osteolysis

Orthopedic device-related infection (ODRI) caused by Staphylococcus aureus, especially methicillin-resistant S. aureus (MRSA) biofilm may lead to persist infection and severe inflammatory osteolysis. Previous studies have demonstrated that both isobavachalcone and curcumin possess antimicrobial activity, recent studies also reveal their antiosteoporosis, anti-inflammation, and immunoregulatory effect. Thus, this study aims to investigate whether the combination of isobavachalcone and curcumin can enhance the anti-S. aureus biofilm activity of gentamicin and alleviate inflammatory osteolysis in vivo. EUCAST and a standardized MBEC assay were used to verify the synergy between isobavachalcone and curcumin with gentamicin against planktonic S. aureus and its biofilm in vitro, then the antimicrobial and immunoregulatory effect of cocktail therapy was demonstrated in a femoral ODRI mouse model in vivo by μCT analysis, histopathology, quantification of bacteria in bone and myeloid-derived suppressor cell (MDSC) in bone marrow. We tested on standard MSSA ATCC25923 and MRSA USA300, 5 clinical isolated MSSA, and 2 clinical isolated MRSA strains and found that gentamicin with curcumin (62.5–250 μg/ml) and gentamicin with isobavachalcone (1.56 μg/ml) are synergistic against planktonic MSSA, while gentamicin (128 μg/ml) with curcumin (31.25–62.5, 250–500 μg/ml) and gentamicin (64–128 μg/ml) with isobavachalcone (1.56–12.5 μg/ml) exhibit synergistic effect against MSSA biofilm. Results of further study revealed that cocktail of 128 μg/ml gentamicin together with 125 μg/ml curcumin +6.25 μg/ml isobavachalcone showed promising biofilm eradication effect with synergy against USA300 biofilm in vitro. Daily intraperitoneal administration of 20 mg/kg/day isobavachalcone, 20 mg/kg/day curcumin, and 20 mg/kg/day gentamicin, can reduce inflammatory osteolysis and maintain microarchitecture of trabecular bone during orthopedic device-related MRSA infection in mice. Cocktail therapy also enhanced reduction of MDSC M1 polarization in peri-implant tissue, suppression of MDSC amplification in bone marrow, and Eradication of USA300 biofilm in vivo. Together, these results suggest that the combination of isobavachalcone and curcumin as adjuvants administrated together with gentamicin significantly enhances its antimicrobial effect against S. aureus biofilm, and can also modify topical inflammation in ODRI and protect bone microstructure in vivo, which may serve as a potential treatment strategy, especially for S. aureus induced ODRI.

Paeoniflorin directly binds to TNFR1 to regulate podocyte necroptosis in diabetic kidney disease

Necroptosis was elevated in both tubulointerstitial and glomerular renal tissue in patients with diabetic kidney disease (DKD), and was most pronounced on glomerulus in the stage with macroalbuminuria. This study further explored whether paeoniflorin (PF) could affect podocyte necroptosis to protect kidney injure in vivo and in vitro. Our study firstly verified that there are obvious necroptosis-related changes in the glomeruli of DKD through bioinformatics analysis combined with clinicopathological data. STZ-induced mouse diabetes model and high-glucose induced podocyte injury model were used to evaluate the renoprotection, podocyte injury protection and necroptosis regulation of PF in DKD. Subsequently, the target protein-TNFR1 that PF acted on podocytes was found by computer target prediction, and then molecular docking and Surface plasmon resonance (SPR) experiments were performed to verify that PF had the ability to directly bind to TNFR1 protein. Finally, knockdown of TNFR1 on podocytes in vitro verified that PF mainly regulated the programmed necrosis of podocytes induced by high glucose through TNFR1. In conclusion, PF can directly bind and promote the degradation of TNFR1 in podocytes and then regulate the RIPK1/RIPK3 signaling pathway to affect necroptosis, thus preventing podocyte injury in DKD. Thus, TNFR1 may be used as a new potential target to treat DKD.

Brassica oleracea L. var. botrytis Leaf Extract Alleviates Gentamicin-Induced Hepatorenal Injury in Rats—Possible Modulation of IL-1β and NF-κB Activity Assisted with Computational Approach

Background: Recently, crop byproducts are considered a hot topic and can be converted into beneficial products. Cauliflower is well-known for its protective effects against oxidative stress-induced damage. The current study aimed to investigate the chemical profile and the ameliorative effects of cauliflower leaf extract (CL) on gentamicin-induced renal and hepatic injuries in rats. Methods: Cauliflower leaf was extracted with methanol to give the total methanol extract (TME) followed by the determination of total phenolic contents (TPC). Rats were divided into five groups; Group I was assigned as the control group, while the other groups were injected with gentamicin for ten days. Group II was given distilled water. Rats in groups III and IV were treated with oral CL (200 mg/kg and 400 mg/kg, respectively). Group V received L-cysteine (as a positive control). The functions of the kidneys and liver; oxidative stress and morphological and apoptotic changes of renal and hepatic tissues were assessed. Results: The TME was subjected to chromatographic techniques to yield ferulic acid, vanillic acid, p-coumaric acid and quercetin. TPC was 72.31 mg GAE/g of dried extract. CL treatment dose-dependently ameliorated gentamicin-induced impaired kidney and liver functions and improved the histopathological appearance of both organs. It also reduced gentamicin-induced oxidative stress. CL demonstrated downregulation of mRNA and protein expressions of IL-1β and NF-κB compared to nontreated rats. In silico interaction of the isolated compounds with amino acid residues of IL-1β and NF-κB might explain the current findings. Conclusion: Taken together, this study raises the waste-to-wealth potential of cauliflower to mitigate gentamicin-induced hepatorenal injury and convert the waste agromaterials into valuable products.

Biochemical interaction of pyrvinium in gentamicin-induced acute kidney injury by modulating calcium dyshomeostasis and mitochondrial dysfunction

Acute kidney injury (AKI) has a poor clinical prognosis and increases the risk of chronic kidney failure (CKD). It is a common complication of organ failure in hospitalised patients (10-15% of all hospitalizations) and in intensive care unit (ICU) patients, with an incidence of up to 50%. Concerning ICU, AKI has a mortality rate ranging from 27% to 35%, rising to 60%-65% when dialysis is needed, with roughly 5%-20% of survivors requiring dialysis on discharge. AKI is believed to cause over 7 million deaths per year worldwide. Currently, there is no treatment for AKI or its progression to CKD. When activated by AKI, numerous pathways have been suggested as possible contributors to CKD progression. Wnt/β-catenin is a crucial regulator of kidney development that increases following the injury. Despite the overwhelming evidence that Wnt/β-catenin promotes AKI, tubulointerstitial fibrosis, a hallmark of CKD progression, is also promoted by this pathway. The therapeutic potential of Wnt/β-catenin in the treatment of AKI and the progression from AKI to CKD is being studied. This hypothesis aims to determine whether the Wnt/β-catenin inhibitor pyrvinium has a beneficial effect on the renal dysfunction and damage caused by Gentamicin.

Therapeutic Implications of Ferroptosis in Renal Fibrosis

Renal fibrosis is a common feature of chronic kidney disease (CKD), and can lead to the destruction of normal renal structure and loss of kidney function. Little progress has been made in reversing fibrosis in recent years. Ferroptosis is more immunogenic than apoptosis due to the release and activation of damage-related molecular patterns (DAMPs) signals. In this paper, the relationship between renal fibrosis and ferroptosis was reviewed from the perspective of iron metabolism and lipid peroxidation, and some pharmaceuticals or chemicals associated with both ferroptosis and renal fibrosis were summarized. Other programmed cell death and ferroptosis in renal fibrosis were also firstly reviewed for comparison and further investigation.

Several Alkaloids in Chinese Herbal Medicine Exert Protection in Acute Kidney Injury: Focus on Mechanism and Target Analysis

Objectives

Acute kidney injury (AKI) is a loose set of kidney diseases accompanied by a variety of syndromes, which is a serious threat to human life and health. Some alkaloids are derived from various Chinese herbs have been widely concerned in the improvement of AKI. This review provides the research progress of alkaloids in AKI experimental models and discusses the related molecular mechanisms. Key Findings. Alkaloids can protect AKI through various mechanisms including antioxidant stress, improvement of mitochondrial damage, reduction of cell death, induction of autophagy, and inhibition of inflammation. These mechanisms are mainly related to the activation of Nrf2/HO-1 signaling pathway, inhibition of ferroptosis and apoptosis, regulation of PINK1/Parkin pathway, inhibition of TLR4/NF-κB pathway and NLRP3 inflammatory bodies, upregulation of Klotho protein level and so on. In addition, there are a few alkaloids that have certain toxicity on the kidney.

Conclusion

Alkaloids have been shown to significantly improve AKI, but only in pharmacological studies. This paper summarizes the main experimental models currently used in AKI research and describes some representative alkaloids based on recent research. Their potential roles in the prevention and treatment of AKI through different mechanisms are highlighted.

Modulation of gentamicin-induced acute kidney injury by myo-inositol oxygenase via the ROS/ALOX-12/12-HETE/GPR31 signaling pathway

In this investigation, a potentially novel signaling pathway in gentamicin-induced acute kidney injury-worsened by overexpression of proximal tubular enzyme, myo-inositol oxygenase (MIOX)-was elucidated. WT, MIOX-transgenic (MIOX-Tg), and MIOX-KO mice were used. Gentamicin was administered to induce tubular injury. MIOX-Tg mice had severe tubular lesions associated with increased serum creatinine and proteinuria. Lesions were relatively mild, with no rise in serum creatinine and no albuminuria in MIOX-KO mice. Transfection of HK-2 cells with MIOX-pcDNA led to increased gentamicin-induced reactive oxygen species (ROS). Marked increase of ROS-mediated lipid hydroperoxidation was noted in MIOX-Tg mice, as assessed by 4-HNE staining. This was associated with increased expression of arachidonate 12-lipoxygenase (ALOX-12) and generation of 12-hydroxyeicosatetraenoic acid (12-HETE). In addition, notable monocyte/macrophage influx, upregulation of NF-κB and inflammatory cytokines, and apoptosis was observed in MIOX-Tg mice. Treatment of cells with ALOX-12 siRNA abolished gentamicin-mediated induction of cytokines and 12-HETE generation. HETE-12 treatment promoted this effect, along with upregulation of various signaling kinases and activation of GPCR31. Similarly, treatment of cells or mice with the ALOX-12 inhibitor ML355 attenuated inflammatory response, kinase signaling cascade, and albuminuria. Collectively, these studies highlight a potentially novel mechanism (i.e., the ROS/ALOX-12/12-HETE/GPR31 signaling axis) relevant to gentamicin-induced nephrotoxicity modulated by MIOX.

Tissue Culture Models of AKI: From Tubule Cells to Human Kidney Organoids

AKI affects approximately 13.3 million people around the world each year, causing CKD and/or mortality. The mammalian kidney cannot generate new nephrons after postnatal renal damage and regenerative therapies for AKI are not available. Human kidney tissue culture systems can complement animal models of AKI and/or address some of their limitations. Donor-derived somatic cells, such as renal tubule epithelial cells or cell lines (RPTEC/hTERT, ciPTEC, HK-2, Nki-2, and CIHP-1), have been used for decades to permit drug toxicity screening and studies into potential AKI mechanisms. However, tubule cell lines do not fully recapitulate tubular epithelial cell properties in situ when grown under classic tissue culture conditions. Improving tissue culture models of AKI would increase our understanding of the mechanisms, leading to new therapeutics. Human pluripotent stem cells (hPSCs) can be differentiated into kidney organoids and various renal cell types. Injury to human kidney organoids results in renal cell-type crosstalk and upregulation of kidney injury biomarkers that are difficult to induce in primary tubule cell cultures. However, current protocols produce kidney organoids that are not mature and contain off-target cell types. Promising bioengineering techniques, such as bioprinting and "kidney-on-a-chip" methods, as applied to kidney nephrotoxicity modeling advantages and limitations are discussed. This review explores the mechanisms and detection of AKI in tissue culture, with an emphasis on bioengineered approaches such as human kidney organoid models.

A Flavonoid-Rich Extract of Sambucus nigra L. Reduced Lipid Peroxidation in a Rat Experimental Model of Gentamicin Nephrotoxicity

The use of gentamicin (GM) is limited due to its nephrotoxicity mediated by oxidative stress. This study aimed to evaluate the capacity of a flavonoid-rich extract of Sambucus nigra L. elderflower (SN) to inhibit lipoperoxidation in GM-induced nephrotoxicity. The HPLC analysis of the SN extract recorded high contents of rutin (463.2 ± 0.0 mg mL−1), epicatechin (9.0 ± 1.1 µg mL−1), and ferulic (1.5 ± 0.3 µg mL−1) and caffeic acid (3.6 ± 0.1 µg mL−1). Thirty-two Wistar male rats were randomized into four groups: a control group (C) (no treatment), GM group (100 mg kg−1 bw day−1 GM), GM+SN group (100 mg kg−1 bw day−1 GM and 1 mL SN extract day−1), and SN group (1 mL SN extract day−1). Lipid peroxidation, evaluated by malondialdehyde (MDA), and antioxidant enzymes activity—superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPX)—were recorded in renal tissue after ten days of experimental treatment. The MDA level was significantly higher in the GM group compared to the control group (p < 0.0001), and was significantly reduced by SN in the GM+SN group compared to the GM group (p = 0.021). SN extract failed to improve SOD, CAT, and GPX activity in the GM+SN group compared to the GM group (p > 0.05), and its action was most probably due to the ability of flavonoids (rutin, epicatechin) and ferulic and caffeic acids to inhibit synthesis and neutralize reactive species, to reduce the redox-active iron pool, and to inhibit lipid peroxidation. In this study, we propose an innovative method for counteracting GM nephrotoxicity with a high efficiency and low cost, but with the disadvantage of the multifactorial environmental variability of the content of SN extracts.

Inhibiting Focal Adhesion Kinase Ameliorates Cyst Development in Polycystin-1-Deficient Polycystic Kidney Disease in Animal Model

BACKGROUND

Autosomal dominant polycystic kidney disease (ADPKD) is characterized by numerous cysts originating from renal tubules and is associated with significant tubular epithelial cell proliferation. Focal adhesion kinase (FAK) promotes tumor growth by regulating multiple proliferative pathways.

METHODS

We established the forskolin (FSK)-induced three-dimensional (3D) Madin-Darby Canine Kidney cystogenesis model and 8-bromoadenosine-3`,5`-cyclic monophosphate-stimulated cyst formation in ex vivo embryonic kidney culture. Cultured human renal cyst-lining cells (OX-161) and normal tubular epithelial cells were treated with FAK inhibitors or transfected with green fluorescent protein-tagged FAK mutant plasmids for proliferation study. Furthermore, we examined the role of FAK in two transgenic ADPKD animal models, the kidney-specific Pkd1 knockout and the collecting duct-specific Pkd1 knockout mouse models.

RESULTS

FAK activity was significantly elevated in OX-161 cells and in two ADPKD mouse models. Inhibiting FAK activity reduced cell proliferation in OX-161 cells and prevented cyst growth in ex vivo and 3D cyst models. In tissue-specific Pkd1 knockout mouse models, FAK inhibitors retarded cyst development and mitigated renal function decline. Mechanically, FSK stimulated FAK activation in tubular epithelial cells, which was blocked by a protein kinase A (PKA) inhibitor. Inhibition of FAK activation by inhibitors or transfected cells with mutant FAK constructs interrupted FSK-mediated Src activation and upregulation of ERK and mTOR pathways.

CONCLUSIONS

Our study demonstrates the critical involvement of FAK in renal cyst development, suggests that FAK is a potential therapeutic target in treating patients with ADPKD, and highlights the role of FAK in cAMP-PKA-regulated proliferation.

Kidney physiology and susceptibility to acute kidney injury: implications for renoprotection

Kidney damage varies according to the primary insult. Different aetiologies of acute kidney injury (AKI), including kidney ischaemia, exposure to nephrotoxins, dehydration or sepsis, are associated with characteristic patterns of damage and changes in gene expression, which can provide insight into the mechanisms that lead to persistent structural and functional damage. Early morphological alterations are driven by a delicate balance between energy demand and oxygen supply, which varies considerably in different regions of the kidney. The functional heterogeneity of the various nephron segments is reflected in their use of different metabolic pathways. AKI is often linked to defects in kidney oxygen supply, and some nephron segments might not be able to shift to anaerobic metabolism under low oxygen conditions or might have remarkably low basal oxygen levels, which enhances their vulnerability to damage. Here, we discuss why specific kidney regions are at particular risk of injury and how this information might help to delineate novel routes for mitigating injury and avoiding permanent damage. We suggest that the physiological heterogeneity of the kidney should be taken into account when exploring novel renoprotective strategies, such as improvement of kidney tissue oxygenation, stimulation of hypoxia signalling pathways and modulation of cellular energy metabolism.

Thymoquinone, but Not Metformin, Protects against Gentamicin-Induced Nephrotoxicity and Renal Dysfunction in Rats

Background: Gentamicin (GM) is an antibiotic that is widely used to treat many Gram-negative bacteria, such as those involved in urinary tract infections. However, being nephrotoxic, GM dose adjustment and reno-protective elements must be concurrently administered with GM to minimize kidney damage. Oxidative stress plays a pivotal role in the pathogenesis of GM-induced nephrotoxicity. Thymoquinone (TQ) is a promising therapeutic substance, that is being extensively studied in many diseases, such as diabetes mellitus, cancer, hypertension, and others. The powerful antioxidant properties of TQ may greatly help in minimizing GM nephrotoxicity. Metformin (MF) is a well-known, clinically approved oral hypoglycaemic drug that has many other actions, including antioxidant properties. The aim of this work was to evaluate the possible antioxidant and reno-protective effects of TQ and metformin in GM-induced nephrotoxicity in the same model (rats) at the same time. In addition, we aimed to further understand the effects underlying GM-induced nephrotoxicity. Methods: Twenty male rats were randomly divided into four equal groups: the first group (control) received distilled water; the second group received GM only; the third group received concurrent oral TQ and GM; and the fourth group received concurrent oral MF and GM. After 4 weeks, renal function and histopathology, as well as levels of the oxidative markers glutathione peroxidase-1 (GLPX1), superoxide dismutase (SOD), and malondialdehyde (MDA) in the kidney tissues, were assessed. Results: Compared with the control group, and as expected, the GM-injected rats showed significant biochemical and histological changes denoting renal damage. Compared with GM-injected rats, the concurrent administration of TQ with GM significantly reduced the levels of serum creatinine, serum urea, and tissue MDA and significantly increased the levels of GLPX1 and SOD. Concurrent metformin administration with GM significantly increased the levels of both GLPX1 and SOD and significantly decreased the levels of tissue MDA but had no significant effect on serum creatinine and urea levels. Compared with GM-injected rats, the addition of either TQ or MF resulted in a reduction in endothelial proliferation and mesangial hypercellularity. Conclusions: Both TQ and MF effectively alleviated the oxidative stress in GM-induced nephrotoxicity in rats, with TQ but not MF producing a complete reno-protective effect. Further studies for evaluation of different reno-protective mechanisms of TQ should be conducted.

Porcine models of acute kidney injury

Pigs represent a potentially attractive model for medical research. Similar body size and physiological patterns of kidney injury that more closely mimic those described in humans make larger animals attractive for experimentation. Using larger animals, including pigs, to investigate the pathogenesis of acute kidney injury (AKI) also serves as an experimental bridge, narrowing the gap between clinical disease and preclinical discoveries. This article compares the advantages and disadvantages of large versus small AKI animal models and provides a comprehensive overview of the development and application of porcine models of AKI induced by clinically relevant insults, including ischemia-reperfusion, sepsis, and nephrotoxin exposure. The primary focus of this review is to evaluate the use of pigs for AKI studies by current investigators, including areas where more information is needed.

Enoxaparin prevents CXCL16/ADAM10-mediated cisplatin renal toxicity: Role of the coagulation system and the transcriptional factor NF-κB

BACKGROUND AND AIMS

C-X-C ligand 16 (CXCL16) is an exceptional chemokine that is expressed as transmembrane and soluble forms. Our aim is to shed lights on the role of CXCL16/ADAM10 (a disintegrin and metalloproteinase) in cisplatin (CP)-induced renal toxicity as well as possible protective effect of enoxaparin.

MAIN METHODS

Male albino mice were injected with CP (30 mg/kg, i.p.) in the presence or absence of enoxaparin (ENOX) (5 mg/kg, i.p.). Renal toxicity markers, serum level of cystatin-c, complete blood count (CBC), prothrombin time (Pt) and tissue expression of CXCL16, ADAM10, cluster of differentiation 3 (CD3), fibrinogen, tissue factor (TF), nuclear factor-κB (NF-κB) and tumour necrosis factor α (TNF-α) were measured. Besides, serum CXCL16 and histopathology were also analyzed.

KEY FINDINGS

CP increased renal toxicity markers, renal expression of CXCL16/ADAM10, fibrinogen, TF and CD3 tissue expression in a time-dependent manner, and elevated serum cystatin-c, CXCL16 and tissue TNF-α, NF-κB. Alternatively, ENOX restored the deteriorated parameters and reduced tissue level of NF-κB.

SIGNIFICANCE

This report, for the first time, showed that soluble CXCL16 resulting from ADAM10 cleavage may recruit T-cells to the renal glomeruli and tubules in CP toxicity. Furthermore, TF and fibrin, have similar expression and location pattern like CXCL16 and ADAM10 suggesting their possible interrelation. ENOX successfully restored the deteriorated parameters suggesting it may be an effective nephroprotective adjuvant therapy.

Collecting duct cells show differential retinoic acid responses to acute versus chronic kidney injury stimuli

Retinoic acid (RA) activates RA receptors (RAR), resulting in RA response element (RARE)-dependent gene expression in renal collecting duct (CD). Emerging evidence supports a protective role for this activity in acute kidney injury (AKI) and chronic kidney disease (CKD). Herein, we examined this activity in RARE-LacZ transgenic mice and by RARE-Luciferase reporter assays in CD cells, and investigated how this activity responds to neurotransmitters and mediators of kidney injury. In RARE-LacZ mice, Adriamycin-induced heavy albuminuria was associated with reduced RA/RAR activity in CD cells. In cultured CD cells, RA/RAR activity was repressed by acetylcholine, albumin, aldosterone, angiotensin II, high glucose, cisplatin and lipopolysaccharide, but was induced by aristolochic acid I, calcitonin gene-related peptide, endothelin-1, gentamicin, norepinephrine and vasopressin. Compared with age-matched normal human CD cells, CD-derived renal cystic epithelial cells from patients with autosomal recessive polycystic kidney disease (ARPKD) had significantly lower RA/RAR activity. Synthetic RAR agonist RA-568 was more potent than RA in rescuing RA/RAR activity repressed by albumin, high glucose, angiotensin II, aldosterone, cisplatin and lipopolysaccharide. Hence, RA/RAR  in CD cells is a convergence point of regulation by neurotransmitters and mediators of kidney injury, and may be a novel therapeutic target.