A nitric oxide-donor furoxan moiety improves the efficacy of edaravone against early renal dysfunction and injury evoked by ischemia/reperfusion

Sephin1 suppresses ER stress-induced cell death by inhibiting the formation of PP2A holoenzyme

Sephin1 was discovered as a protein phosphatase inhibitor, and its efficacy against neurodegenerative diseases has been confirmed. There are conflicting reports on whether inhibition of eIF2α dephosphorylation by PP1 holoenzyme with the protein phosphatase 1 regulatory subunit 15 A is the mechanism of action of Sephin1. In the present study, we found that Sephin1 significantly suppressed renal tubular cell death in an animal model of ER stress administered with tunicamycin. CHOP, which plays a central role in the ER stress-induced cell death pathway, requires nuclear translocation to act as a transcription factor to increase the expression of cell death-related genes. Sephin1 markedly suppressed this nuclear translocation of CHOP. To elucidate the molecular mechanism underlying the cell death suppressive effect of Sephin1, we used human renal tubular epithelial cells under ER stress with tunicamycin. Sephin1 reduced intracellular CHOP levels by promoting CHOP phosphorylation at Ser30, which led to protein degradation in UPS. Phosphorylated CHOP is generated by Thr172-phosphorylated activated AMPK, and Sephin1 increased phosphorylated AMPK. Phosphorylated AMPK is inactivated by PP2A through dephosphorylation of its Thr172, and Sephin1 inhibits the formation of the PP2A holoenzyme with the PP2A subunit B isoform delta. These results indicate that inhibition of PP2A holoenzyme formation is the molecular target of Sephin1 in this experimental system.

The Role of Gasotransmitter-Dependent Signaling Mechanisms in Apoptotic Cell Death in Cardiovascular, Rheumatic, Kidney, and Neurodegenerative Diseases and Mental Disorders

Cardiovascular, rheumatic, kidney, and neurodegenerative diseases and mental disorders are a common cause of deterioration in the quality of life up to severe disability and death worldwide. Many pathological conditions, including this group of diseases, are based on increased cell death through apoptosis. It is known that this process is associated with signaling pathways controlled by a group of gaseous signaling molecules called gasotransmitters. They are unique messengers that can control the process of apoptosis at different stages of its implementation. However, their role in the regulation of apoptotic signaling in these pathological conditions is often controversial and not completely clear. This review analyzes the role of nitric oxide (NO), carbon monoxide (CO), hydrogen sulfide (H₂S), and sulfur dioxide (SO₂) in apoptotic cell death in cardiovascular, rheumatic, kidney, and neurodegenerative diseases. The signaling processes involved in apoptosis in schizophrenia, bipolar, depressive, and anxiety disorders are also considered. The role of gasotransmitters in apoptosis in these diseases is largely determined by cell specificity and concentration. NO has the greatest dualism; scales are more prone to apoptosis. At the same time, CO, H₂S, and SO₂ are more involved in cytoprotective processes.

Potent efficacy of Stachybotrys microspora triprenyl phenol-7, a small molecule having anti-inflammatory and antioxidant activities, in a mouse model of acute kidney injury

Acute kidney injury (AKI) increases the risk of chronic kidney disease (CKD), complicates existing CKD, and can lead to the end-stage renal disease. However, there are no approved effective therapeutics for AKI. Recent studies have suggested that inflammation and oxidative stress are the primary causes of AKI. We previously reported the potential anti-inflammatory and antioxidant activities of Stachybotrys microspora triprenyl phenol-7 (SMTP-7). The aim of the present study was to evaluate the efficacy of SMTP-7 in AKI model mice. AKI was induced in mice by ischemia of the left renal artery and vein for 45 min followed by reperfusion, 2 weeks after the removal of right kidney. The efficacy of SMTP-7 was determined by measuring the renal function using urine and serum samples and morphological assessment. For deciphering the mechanism of action of SMTP-7, inflammatory cytokines and oxidative stress in kidney were detected. SMTP-7 (0.01, 0.1, 1, 10 mg/kg) dose-dependently improved the renal function. In addition, it improved the damage to renal tubules and exhibited anti-inflammatory and antioxidant activities in the kidney of AKI mice. These results indicate the potential of SMTP-7 as a medicinal compound for the treatment of AKI.

Betaine attenuates sodium arsenite-induced renal dysfunction in rats

Exposure to higher levels of arsenic is a serious threat affecting human health worldwide. We investigated the protective role of betaine (N,N,N-trimethylglycine) against sodium arsenite-induced renal dysfunction in rats. Sodium arsenite (5 mg/kg, oral) was given to rats for 4 weeks to induce nephrotoxicity. Betaine (125 and 250 mg/kg, oral) was administered in rats for 4 weeks along with sodium-arsenite feeding. Arsenic-induced renal dysfunction was demonstrated by measuring serum creatinine, creatinine clearance, urea, uric acid, potassium, fractional excretion of sodium, and microproteinuria. Oxidative stress in rat kidneys was determined by assaying thiobarbituric acid reactive substances, superoxide anion generation, and reduced glutathione levels. Furthermore, hydroxyproline assay was done to assess renal fibrosis in arsenic intoxicated rats. Hematoxylin-eosin and picrosirius red staining revealed pathological alterations in rat kidneys. Renal endothelial nitric oxide synthase (eNOS) expression was determined by immuno-histochemistry. Concurrent administration of betaine abrogated arsenic-induced renal biochemical and histological changes in rats. Betaine treatment significantly attenuated arsenic-induced decrease in renal eNOS expression. In conclusion, betaine is protective against sodium arsenite-induced renal dysfunction, which may be attributed to its anti-oxidant activity and modulation of renal eNOS expression in rat kidneys.

A review of the synthesis of nitric oxide donor and donor derivatives with pharmacological activities

Endogenous nitric oxide (NO) is an important effector molecule and signal transduction molecule, which participates in the regulation of multiple functions in organisms, involving a variety of physiological and pathological processes, especially playing a very important role in the cardiovascular, immune, and nervous systems. NO is a gaseous substance with a short half-life in the body and is unstable in aqueous solutions. Therefore, many researchers focus on the release and activity of NO donors and their derivatives. However, NO donors can release free NO or NO analogues under physiological conditions to meet the human need. NO donors can be coupled with the corresponding active basic nucleus, so that they have the biological activity derived from both the basic nucleus and the NO donors, thus performing better bioactivity. This paper reviewed the routes of synthesis and advance activities of NO donor derivatives.

Fenofibrate attenuates ischemia reperfusion-induced acute kidney injury and associated liver dysfunction in rats

Ischemia/reperfusion (I/R) is one of the common reasons for acute kidney injury (AKI) and we need to develop effective therapies for treating AKI. We investigated the role of fenofibrate against I/R-induced AKI and associated hepatic dysfunction in rats. In male wistar albino rats, renal pedicle occlusion for 40 min and 24 h reperfusion resulted in AKI. I/R-induced AKI was demonstrated by measuring serum creatinine, creatinine clearance, urea, uric acid, potassium, fractional excretion of sodium and urinary microproteins. Oxidative stress in rat kidneys was quantified by assaying superoxide anion generation, thiobarbituric acid reactive substances, and reduced glutathione levels. AKI-induced hepatic damage was quantified by assaying serum aminotransferases, alkaline phosphatase and bilirubin levels. Moreover, serum cholesterol, high density lipoprotein and triglycerides were quantified. Hematoxylin-eosin staining of renal and hepatic tissues was done and the kidney and liver injury scores were determined. Immunohistology of endothelial nitric oxide synthase (eNOS) was done in rat kidneys. Fenofibrate was administered for 1 week before subjecting rats to AKI. In separate group, the nitric oxide synthase inhibitor, L-nitroarginine methyl ester (L-NAME) was administered prior to fenofibrate treatment. In I/R group, significant alteration in the serum/urine parameters indicated AKI and hepatic dysfunction along with marked increase in kidney and liver injury scores. Treatment with fenofibrate attenuated AKI and associated hepatic dysfunction. Moreover, I/R-induced decrease in renal eNOS expression was abrogated by fenofibrate. Pre-treatment with L-NAME abolished fenofibrate mediated reno- and hepato-protective effects. In conclusion, fenofibrate attenuates I/R-induced AKI and associated hepatic dysfunction putatively through modulation of eNOS expression.

H2S- and NO-releasing gasotransmitter platform: A crosstalk signaling pathway in the treatment of acute kidney injury

Acute kidney injury (AKI) is a syndrome affecting most patients hospitalized due to kidney disease; it accounts for 15 % of patients hospitalized in intensive care units worldwide. AKI is mainly caused by ischemia and reperfusion (IR) injury, which temporarily obstructs the blood flow, increases inflammation processes and induces oxidative stress. AKI treatments available nowadays present notable disadvantages, mostly for patients with other comorbidities. Thus, it is important to investigate different approaches to help minimizing side effects such as the ones observed in patients subjected to the aforementioned treatments. Therefore, the aim of the current review is to highlight the potential of two endogenous gasotransmitters - hydrogen sulfide (H₂S) and nitric oxide (NO) - and their crosstalk in AKI treatment. Both H₂S and NO are endogenous signalling molecules involved in several physiological and pathophysiological processes, such as the ones taking place in the renal system. Overall, these molecules act by decreasing inflammation, controlling reactive oxygen species (ROS) concentrations, activating/inactivating pro-inflammatory cytokines, as well as promoting vasodilation and decreasing apoptosis, hypertrophy and autophagy. Since these gasotransmitters are found in gaseous state at environmental conditions, they can be directly applied by inhalation, or in combination with H₂S and NO donors, which are compounds capable of releasing these molecules at biological conditions, thus enabling higher stability and slow release of NO and H₂S. Moreover, the combination between these donor compounds and nanomaterials has the potential to enable targeted treatments, reduce side effects and increase the potential of H₂S and NO. Finally, it is essential highlighting challenges to, and perspectives in, pharmacological applications of H₂S and NO to treat AKI, mainly in combination with nanoparticulated delivery platforms.

Edaravone Protects against Pancreatic and Intestinal Injury after Acute Pancreatitis via Nuclear Factor-κB Signaling in Mice

Acute pancreatitis (AP) is one kind of acute surgical abdominal disease in the world. It causes intestinal damage with subsequent bacterial migration, endotoxemia and secondary pancreatic infections. In this investigation, we determined that edaravone (EDA) reduces pancreatic and intestinal injury after AP in mice. This was demonstrated by a reduction in histological score, apoptosis, interleukin (IL)-6, IL-1β and tumor necrosis factor (TNF)-α, along with obstructing activation of Toll-like receptor 4 (TLR4) and nuclear factor-κB (NFκB). Our study results suggested that EDA exerts its protective effects against pancreatic and intestinal injury after AP via regulation of the TLR4/NFκB pathway. Our findings provide the basis for EDA to treat AP-induced pancreatic and intestinal injury, even might develop as a potential therapy for other inflammatory diseases.

Edaravone Ameliorates Renal Warm Ischemia-Reperfusion Injury by Downregulating Endoplasmic Reticulum Stress in a Rat Resuscitation Model

Background

This study was conducted to explore whether the effect of edaravone (5-methyl-2-phenyl-2,4-dihydro-3H-pyrazol3-one, EDR) can ameliorate renal warm ischemia-reperfusion injury (IRI) by modulating endoplasmic reticulum stress (ERS) and its downstream effector after cardiac arrest (CA) and cardiopulmonary resuscitation (CPR) in a rat model.

Methods

The rats (n=10) experienced anaesthesia and intubation followed by no CA inducement were defined as the Sham group. Transoesophageal alternating current stimulation was employed to establish 8 min of CA followed by conventional CPR for a resuscitation model. The rats with successful restoration of spontaneous circulation (ROSC) randomly received EDR (3 mg/kg, EDR group, n=10) or equal volume normal saline solution (the NS group, n=10). At 24 hr after ROSC, serum creatinine (SCR), blood urea nitrogen (BUN) levels, and cystatin-C (Cys-C) levels were determined and the protein level of glucose-regulated protein (GRP78), C/EBP homologous protein (CHOP), extracellular signal-regulated kinase (ERK), phosphorylated extracellular signal-regulated kinase 1/2 (p-ERK1/2), Bax/Bcl-2, and caspase-3 were detected by Western blot method.

Results

At 24 hrs after ROSC, SCR, BUN and Cys-C were obviously increased and the proteins expression, including GRP78, CHOP and p-ERK1/2, cleaved-caspase 3 Bax/Bcl-2 ratio, were significantly upregulated in the NS group compared with the Sham group (p<0.05). The remarkable improvement of these adverse outcomes was observed in the EDR group (p<0.05).

Conclusion

In conclusion, we found that EDR ameliorates renal warm IRI by downregulating ERS and its downstream effectors in a rat AKI model evoked by CA/CPR. These data may provide evidence for future therapeutic benefits of EDR against AKI induced by CA/CPR.

Edaravone attenuates traumatic brain injury through anti-inflammatory and anti-oxidative modulation

Traumatic brain injury (TBI) is among the leading causes of irreversible neurological damage and death worldwide. The aim of the present study was to investigate whether edaravone (EDA) had a neuroprotective effect on TBI as well as to identify the potential mechanism. Results demonstrated that EDA suppressed inflammatory and oxidative responses in mice following TBI. This was evidenced by a reduction in glutathione peroxidase, interleukin 6, tumor necrosis factor-α and hydrogen peroxide levels, in addition to an increase in hemeoxygenase-1, quinone oxidoreductase 1 and superoxide dismutase levels, thereby mitigating neurofunctional deficits, cell apoptosis and structural damage. EDA prevented the transfer of NF-κB protein from the cytoplasm to the nucleus, whilst promoting the expression of nuclear factor erythroid 2-related factor 2 (Nrf2) protein in mice following TBI. These results indicated that EDA exerted neuroprotective effects, including impeding neurofunctional deficits, cell apoptosis and structural damage, in mice with TBI, potentially via suppression of NF-κB-mediated inflammatory activation and promotion of the Nrf2 antioxidant pathway.

Effect of edaravone against cisplatin-induced chronic renal injury

Cisplatin has been widely used as an anticancer agent for a wide range of tumors, but it had nephrotoxicity that was mainly caused by oxidative stress. Edaravone, a free radical scavenger, has reportedly been validated to have a protective effect against renal injury induced by reactive oxygen species. However, most of these reports are against AKI, and few studies have examined the effect of chronic renal injury. In this study, we investigate the effect of edaravone on cisplatin nephropathy in the chronic phase. Twenty-five male Wistar rats were divided into five groups: control, cisplatin, cisplatin + edaravone 1 mg kg^-1, cisplatin + edaravone 10 mg kg^-1, and cisplatin + edaravone 100 mg kg^-1. Edaravone was administrated intraperitoneally every other day for 5 weeks, starting 1 week before cisplatin administration (6 mg kg^-1, i.p.). As a result, proximal tubule injury, interstitial fibrosis, and mononuclear cell infiltration were ameliorated histologically in the group of rats treated with high edaravone dose. In the cisplatin group, the number of α-SMA-, CD68-, and CD3-positive cells increased markedly compared with the Control group, but these numbers were significantly decreased by higher doses of co-administered edaravone. While there was no clear mRNA expression variation in antioxidant enzymes, the apoptosis-promoting factors, caspase8, were markedly reduced in the high-dose edaravone co-administration group compared with the cisplatin group. In conclusion, our results suggested that cisplatin-induced renal injury in the chronic phase was ameliorated by edaravone.

Targeted delivery of nitric oxide via a 'bump-and-hole'-based enzyme-prodrug pair

The spatiotemporal generation of nitric oxide (NO), a versatile endogenous messenger, is precisely controlled. Despite its therapeutic potential for a wide range of diseases, NO-based therapies are limited clinically due to a lack of effective strategies for precisely delivering NO to a specific site. In the present study, we developed a novel NO delivery system via modification of an enzyme-prodrug pair of galactosidase-galactosyl-NONOate using a 'bump-and-hole' strategy. Precise delivery to targeted tissues was clearly demonstrated by an in vivo near-infrared imaging assay. The therapeutic potential was evaluated in both rat hindlimb ischemia and mouse acute kidney injury models. Targeted delivery of NO clearly enhanced its therapeutic efficacy in tissue repair and function recovery and abolished side effects due to the systemic release of NO. The developed protocol holds broad applicability in the targeted delivery of important gaseous signaling molecules and offers a potent tool for the investigation of relevant molecular mechanisms.

Dexmedetomidine Ameliorates Acute Stress-Induced Kidney Injury by Attenuating Oxidative Stress and Apoptosis through Inhibition of the ROS/JNK Signaling Pathway

Acute stress induces tissue damage through excessive oxidative stress. Dexmedetomidine (DEX) reportedly has an antioxidant effect. However, protective roles and related potential molecular mechanisms of DEX against kidney injury induced by acute stress are unknown. Herein, rats were forced to swim 15 min followed by restraint stress for 3 h with/without DEX (30 μg/kg). Successful model establishment was validated by an open-field test. Assessment of renal function (creatinine, urea nitrogen), histopathology, oxidative stress (malondialdehyde, glutathione, and superoxide dismutase), and apoptosis (transferase-mediated dUTP nick end labeling) was performed. Localization of apoptosis was determined by immunohistochemistry of cleaved caspase 3 protein. In addition, key proteins of the death receptor-mediated pathway, mitochondrial pathway, endoplasmic reticulum stress (ERS) pathway, and ROS/JNK signaling pathway were measured by Western blot. We found that DEX significantly improved renal dysfunction, ameliorated kidney injury, reduced oxidative stress, and alleviated apoptosis. DEX also inhibited the release of norepinephrine (NE), decreased the production of reactive oxygen species (ROS), and inhibited JNK phosphorylation. Additionally, DEX downregulated the expression of Bax, cytochrome C, cleaved caspase 9, and cleaved caspase 3 proteins in mitochondria-dependent pathways. In summary, DEX protects against acute stress-induced kidney injury in rats by reducing oxidative stress and apoptosis via inhibition of the ROS/JNK pathway.

Noninvasive evaluation of renal pH homeostasis after ischemia reperfusion injury by CEST-MRI

Acute kidney injury (AKI) in mice caused by sustained ischemia followed by reperfusion is associated with acute tubular necrosis and renal dysfunctional blood flow. Although the principal role of the kidney is the maintenance of acid-base balance, current imaging approaches are unable to assess this important parameter, and clinical biomarkers are not robust enough in evaluating the severity of kidney damage. Therefore, novel noninvasive imaging approaches are needed to assess the acid-base homeostasis in vivo. This study investigates the usefulness of MRI-chemical exchange saturation transfer (CEST) pH imaging (through iopamidol injection) in characterizing moderate and severe AKI in mice following unilateral ischemia reperfusion injury. Moderate (20 min) and severe (40 min) ischemia were induced in Balb/C mice, which were imaged at several time points thereafter (Days 0, 1, 2, 7). A significant increase of renal pH values was observed as early as one day after the ischemia reperfusion damage for both moderate and severe ischemia. MRI-CEST pH imaging distinguished the evolution of moderate from severe AKI. A recovery of normal renal pH values was observed for moderate AKI, whereas a persisting renal pH increase was observed for severe AKI on Day 7. Renal filtration fraction was significantly lower for clamped kidneys (0.54-0.57) in comparison to contralateral kidneys (0.84-0.86) following impairment of glomerular filtration. The severe AKI group showed a reduced filtration fraction even after 7 days (0.38 for the clamped kidneys). Notably, renal pH values were significantly correlated with the histopathological score. In conclusion, MRI-CEST pH mapping is a valid tool for the noninvasive evaluation of both acid-base balance and renal filtration in patients with ischemia reperfusion injury.

Protective Effect of Edaravone Against Cyclosporine-Induced Chronic Nephropathy Through Antioxidant and Nitric Oxide Modulating Pathways in Rats

BACKGROUND

Cyclosporine A (CsA) is an immunosuppressant with therapeutic indications in various immunological diseases; however, its use is associated with chronic nephropathy. Oxidative stress has a crucial role in CsA-induced nephrotoxicity. The present study evaluates the protective effect of edaravone on CsA-induced chronic nephropathy and investigates its antioxidant and nitric oxide modulating property.

METHODS

Male Sprague-Dawley rats (n=66) were distributed into nine groups, including a control (group 1) (n=7). Eight groups received CsA (15 mg/kg) for 28 days while being treated. The groups were categorized as: Group 2: Vehicle (n=10)Groups 3, 4, and 5: Edaravone (1, 5, and 10 mg/kg) (n=7 each)Group 6: Diphenyliodonium chloride, a specific endothelial nitric oxide synthase (eNOS) inhibitor (n=7)Group 7: Aminoguanidine, a specific inducible nitric oxide synthase (iNOS) inhibitor (n=7)Group 8: Edaravone (10 mg/kg) plus diphenyliodonium chloride (n=7)Group 9: Edaravone (10 mg/kg) plus aminoguanidine (n=7) Blood urea nitrogen and serum creatinine levels, malondialdehyde, superoxide dismutase, and glutathione reductase enzyme activities were measured using standard kits. Renal histopathological evaluations and measurements of eNOS and iNOS gene expressions by RT-PCR were also performed. Data were analyzed using one-way analysis of variance (ANOVA) followed by Tukey's test (SPSS software version 18.0).

RESULTS

Edaravone (10 mg/kg) significantly attenuated CsA-induced oxidative stress, renal dysfunction, and kidney tissue injury. Aminoguanidine improved the renoprotective effect of edaravone. Edaravone reduced the elevated mRNA level of iNOS, but could not alter the level of eNOS mRNA significantly.

CONCLUSION

Edaravone protects against CsA-induced chronic nephropathy using antioxidant property and probably through inhibiting iNOS gene expression.

Dioclea violacea lectin ameliorates oxidative stress and renal dysfunction in an experimental model of acute kidney injury

Acute kidney injury (AKI) is characterized by rapid and potentially reversible decline in renal function; however, the current management for AKI is nonspecific and associated with limited supportive care. Considering the need for more novel therapeutic approaches, we believe that lectins from Dioclea violacea (Dvl), based on their anti-inflammatory properties, could be beneficial for the treatment of AKI induced by renal ischemia/reperfusion (IR). Dvl (1 mg/kg, i.v.) or vehicle (100 µL) was administered to Wistar rats prior to the induction of bilateral renal ischemia (45 min). Following 24 hours of reperfusion, inulin and para-aminohippurate (PAH) clearances were performed to determine glomerular filtration rate (GFR), renal plasma flow (RPF), renal blood flow (RBF) and renal vascular resistance (RVR). Renal inflammation was assessed using myeloperoxidase (MPO) activity. Kidney sections were stained with hematoxylin-eosin to evaluate morphological changes. Intracellular superoxide anions, hydrogen peroxide, peroxynitrite, nitric oxide and apoptosis were analyzed using flow cytometry. IR resulted in diminished GFR, RPF, RBF, and increased RVR; however, these changes were ameliorated in rats receiving Dvl. AKI-induced histomorphological changes, such as tubular dilation, tubular necrosis and proteinaceous casts, were attenuated by Dvl administration. Treatment with Dvl resulted in diminished renal MPO activity, oxidative stress and apoptosis in rats submitted to IR. Our data reveal that Dvl has a protective effect in the kidney, improving renal function after IR injury, probably by reducing neutrophil recruitment and oxidative stress. These results indicate that Dvl can be considered a new therapeutic approach for AKI-induced kidney injury.

Vasorelaxant Effect of a New Hydrogen Sulfide-Nitric Oxide Conjugated Donor in Isolated Rat Aortic Rings through cGMP Pathway

Endothelium-dependent vasorelaxant injury leads to a lot of cardiovascular diseases. Both hydrogen sulfide (H₂S) and nitric oxide (NO) are gasotransmitters, which play a critical role in regulating vascular tone. However, the interaction between H₂S and NO in vasorelaxation is still unclear. ZYZ-803 was a novel H₂S and NO conjugated donor developed by H₂S-releasing moiety (S-propyl-L-cysteine (SPRC)) and NO-releasing moiety (furoxan). ZYZ-803 could time- and dose-dependently relax the sustained contraction induced by PE in rat aortic rings, with potencies of 1.5- to 100-fold greater than that of furoxan and SPRC. Inhibition of the generations of H₂S and NO with respective inhibitors abolished the vasorelaxant effect of ZYZ-803. ZYZ-803 increased cGMP level and the activity of vasodilator stimulated phosphoprotein (VASP) in aortic rings, and those effects could be suppressed by the inhibitory generation of H₂S and NO. Both the inhibitor of protein kinase G (KT5823) and the inhibitor of K_ATP channel (glibenclamide) suppressed the vasorelaxant effect of ZYZ-803. Our results demonstrated that H₂S and NO generation from ZYZ-803 cooperatively regulated vascular tone through cGMP pathway, which indicated that ZYZ-803 had therapeutic potential in cardiovascular diseases.