Glucocorticoid receptor agonist dexamethasone attenuates renal ischemia/reperfusion injury by up-regulating eNOS/iNOS

Nanotherapeutic kidney cell-specific targeting to ameliorate acute kidney injury

Acute kidney injury (AKI) increases the risk of in-hospital death, adds to expense of care, and risk of early chronic kidney disease. AKI often follows an acute event such that timely treatment could ameliorate AKI and potentially reduce the risk of additional disease. Despite therapeutic success of dexamethasone in animal models, clinical trials have not demonstrated broad success. To improve the safety and efficacy of dexamethasone for AKI, we developed and characterized a novel, kidney-specific nanoparticle enabling specific within-kidney targeting to proximal tubular epithelial cells provided by the megalin ligand cilastatin. Cilastatin and dexamethasone were complexed to H-Dot nanoparticles, which were constructed from generally recognized as safe components. Cilastatin/Dexamethasone/H-Dot nanotherapeutics were found to be stable at plasma pH and demonstrated salutary release kinetics at urine pH. In vivo, they were specifically biodistributed to the kidney and bladder, with 75% recovery in the urine and with reduced systemic toxicity compared to native dexamethasone. Cilastatin complexation conferred proximal tubular epithelial cell specificity within the kidney in vivo and enabled dexamethasone delivery to the proximal tubular epithelial cell nucleus in vitro. The Cilastatin/Dexamethasone/H-Dot nanotherapeutic improved kidney function and reduced kidney cellular injury when administered to male C57BL/6 mice in two translational models of AKI (rhabdomyolysis and bilateral ischemia reperfusion). Thus, our design-based targeting and therapeutic loading of a kidney-specific nanoparticle resulted in preservation of the efficacy of dexamethasone, combined with reduced off-target disposition and toxic effects. Hence, our study illustrates a potential strategy to target AKI and other diseases of the kidney.

D-Pinitol mitigates post-traumatic stress disorder-like behaviors induced by single prolonged stress in mice through mineralocorticoid receptor antagonism

Post-traumatic stress disorder (PTSD) is a mental illness that can occur in individuals who have experienced trauma. Current treatments for PTSD, typically serotonin reuptake inhibitors, have limited effectiveness for patients and often cause serious adverse effects. Therefore, a novel class of treatment with better pharmacological profile is necessary. D-Pinitol has been reported to be effective for depression and anxiety disorders, but there are no reports associated with PTSD. In the present study, we investigated the effects of D-pinitol in a mouse model of PTSD induced by a single prolonged stress (SPS) protocol. We examined the therapeutic effects of D-pinitol on emotional and cognitive impairments in the SPS mouse model. We also investigated the effects of D-pinitol on fear memory formation. Mineralocorticoid receptor transactivation assay, Western blot, and quantitative PCR were employed to investigate how D-pinitol exerts its pharmacological activities. D-Pinitol ameliorated PTSD-like behaviors in a SPS mouse model. D-Pinitol also normalized the increased mRNA expression levels and protein levels of the mineralocorticoid receptor in the amygdala. A mineralocorticoid receptor agonist reversed the effects of D-pinitol on fear extinction and recall, and the antagonistic property of D-pinitol against the mineralocorticoid receptor was confirmed in vitro. Our findings suggest that D-pinitol could serve as a potential therapeutic agent for PTSD due to its antagonistic effect on the mineralocorticoid receptor.

hUC-MSC-EV-miR-24 enhances the protective effect of dexmedetomidine preconditioning against myocardial ischemia-reperfusion injury through the KEAP1/Nrf2/HO-1 signaling

The cardioprotective effect of microRNAs (miRNAs) on myocardial ischemic-reperfusion (I/R) injury has been documented. Here, we aim to decipher the mechanism of miR-24 delivered by human umbilical cord mesenchymal stem cell-derived extracellular vesicles (hUC-MSC-EVs) in myocardial I/R injury after dexmedetomidine (DEX) preconditioning. We collected and identified hUC-MSCs and extracted EVs, which were co-cultured with DEX-preconditioned hypoxia/reoxygenation (H/R) cardiomyocyte models or injected into I/R mouse models. The cardiomyocytes and myocardial injury were evaluated by molecular biology experiments. miR-24 was highly expressed in hUC-MSC-EVs. hUC-MSC-EVs could transfer miR-24 into cardiomyocytes where miR-24 augmented cell viability and inhibited cell apoptosis after DEX preconditioning. In the co-culture system of RAW264.7 macrophages with hUC-MSC-EVs, miR-24 promoted M2-type polarization of macrophages and reduced M1-type macrophage polarization. Mechanistically, miR-24 targeted KEAP1 and inhibited its expression, resulting in disruption of the Nrf2/HO-1 signaling. In vivo data confirmed that miR-24 delivered by hUC-MSC-EVs enhanced the suppressing effect of DEX preconditioning on inflammation and apoptosis in rats following myocardial I/R injury. Overall, miR-24 delivered by hUC-MSC-EVs can promote M2 polarization of macrophages and enhance the protective effect of DEX preconditioning on myocardial I/R injury by down-regulating the KEAP1/Nrf2/HO-1 signaling axis.

Epigallocatechin-3-gallate in combination with corticosteroids mitigates heat stress-induced acute kidney injury through modulating heat shock protein 70 and toll-like receptor 4-dependent pathways

Recently, recurrent heat stress (HS) and dehydration have been exhibited to give rise to kidney disease epidemic in hot regions. The current study was carried out to estimate a possible renoprotective effect of dexamethasone (Dexa) and epigallocatechin-3-gallate (EGCG) as a heat shock protein (HSP)-70 inhibitor on HS-induced nephropathy. In total, five groups of rats were used: control group, HS group (exposed to heat for 40 min), Dexa+HS group (rats were injected with Dexa i.p.15 mg/kg/day for 3 days followed by HS), EGCG+HS group (rats received EGCG 100 mg/kg/day, orally, for 7 days followed by HS), and EGCG+ Dexa +HS group (rats received EGCG 100 mg/kg/day, orally, for 7 days and injected Dexa as described along the last 3 days followed by HS). Kidney sections were stained with H&E and scored for tubular injury. A marked increase in creatinine, urea, malondialdehyde (MDA), monocyte chemoattractant protein (MCP)-1, HSP-70, nuclear factor kappa B (NF-κB), toll-like receptor 4 (TLR-4) and Caspase-3 expression was observed after HS induction (p < 0.001). Treatment with EGCG combined with Dexa notably reduced tubular injury, MCP-1, HSP-70, NF-κB, and TLR-4 levels (p < 0.001). Moreover, it increased IL-10, antioxidant capacity and Bcl-2 expression levels in the kidney (p < 0.001). This renoprotective impact might be attributed to anti-inflammatory, antioxidant, and anti-apoptotic mechanisms besides interfering with TLR-4-mediated NF-κB activation pathway.

Quantitative evaluation of dexamethasone treatment effects in renal ischemia-reperfusion injury using contrast enhanced ultrasonography in rats

BACKGROUND

Renal ischemia-reperfusion (I/R) injury often occurs in various clinical events, and its incidence and mortality have been increasing.

OBJECTIVE

To investigate the value of contrast enhanced ultrasonography (CEUS) in the monitoring of dexamethasone in the improvement of renal I/R injury in rats.

METHODS

Eighteen healthy male Sprague-Dawley rats were randomly divided into sham-operated, I/R, and I/R surgery plus dexamethasone treatment (Dexa) groups. In the I/R group 45-minute renal ischemia with 24 h reperfusion period was monitored. Time-intensity curve (TIC)-derived parameters, which included peak value, time to peak (TP), area under the curve (AUC), and mean transit time (MTT) were compared to the blood creatinine, urea, Caspase-1, and NLRP3 levels.

RESULTS

The I/R group showed an increased peak value, prolonged TP and MTT, and greater AUC (P < 0.05). The Dexa group showed shorter TP and MTT, and smaller AUC (P < 0.05). Results show that the associations between (i) TP, AUC, and MTT and (ii) creatinine, urea, Caspase-1, and NLRP3 levels were significant (P < 0.05).

CONCLUSION

Dexamethasone can alleviate renal I/R injury in rats, which may be related to the inhibition of NLRP3 and caspase-1. CEUS can quantitatively measure this change, in which the changes in TP, AUC and MMT values have considerable reference values.

Donepezil protects glycerol-induced acute renal failure through the cholinergic anti-inflammatory and nitric oxide pathway in rats

OBJECTIVES

Inflammation as well as oxygen metabolite play important roles in renal injury during pathogenesis of rhabdomyolysis induced myoglobinuric acute renal failure (ARF). The aim of this study was to investigate the protective effects of donepezil on immune responses in rats with glycerol-induced ARF.

METHODS

Sixty male rats were randomly divided into six groups, the rats were given normal saline (10 ml/kg, i.m.), glycerol (50%, 10 ml/kg, i.m.), glycerol plus dexamethasone (0.1 mg/kg, i.g.), and glycerol plus donepezil (1, 5 and 10 mg/kg, i.g.) respectively. After two weeks of glycerol injections, the kidney tissues and blood samples were harvested for future biochemical and pathology analysis. The levels of creatinine (Cr) and urea nitrogen (BUN) in plasma, the content of malondialdehyde (MDA), glutathione (GSH), and superoxide dismutase (SOD) activity, total nitric oxide synthase (TNOS), inducible nitric oxide synthase (iNOS), endothelial NO synthase (eNOS) were evaluated in renal tissues. In addition, interleukin-6 (IL-6), tumor necrosis factors-α (TNF-α) in renal tissues were also determined.

RESULTS

Donepezil treatment protected rats from renal dysfunction in a dose-dependent manner and through the cholinergic anti-inflammatory pathway. Additionally, donepezil significantly reduced tubular damages, prevented neutrophil infiltration and decreased productions of the IL-6, TNF-α, nitric oxide content and oxidative damage.

CONCLUSIONS

These data indicate that donepezil exerts a protective anti-inflammatory effect during ARF through the cholinergic pathway and Nitric oxide pathway. In addition, this study could provide an opportunity to overcome the effect of surgical cholinergic denervation during kidney transplantation and other injury.

Progress to Improve Oral Bioavailability and Beneficial Effects of Resveratrol

Resveratrol (3,5,4'-trihydroxystilbene; RSV) is a natural nonflavonoid polyphenol present in many species of plants, particularly in grapes, blueberries, and peanuts. Several in vitro and in vivo studies have shown that in addition to antioxidant, anti-inflammatory, cardioprotective and neuroprotective actions, it exhibits antitumor properties. In mammalian models, RSV is extensively metabolized and rapidly eliminated and therefore it shows a poor bioavailability, in spite it of its lipophilic nature. During the past decade, in order to improve RSV low aqueous solubility, absorption, membrane transport, and its poor bioavailability, various methodological approaches and different synthetic derivatives have been developed. In this review, we will describe the strategies used to improve pharmacokinetic characteristics and then beneficial effects of RSV. These methodological approaches include RSV nanoencapsulation in lipid nanocarriers or liposomes, nanoemulsions, micelles, insertion into polymeric particles, solid dispersions, and nanocrystals. Moreover, the biological results obtained on several synthetic derivatives containing different substituents, such as methoxylic, hydroxylic groups, or halogens on the RSV aromatic rings, will be described. Results reported in the literature are encouraging but require additional in vivo studies, to support clinical applications.

Short-term dexamethasone treatment transiently, but not permanently, attenuates fibrosis after acute-to-chronic kidney injury

Background

Acute kidney injury (AKI) is an underestimated, yet important, risk factor for the development of chronic kidney disease (CKD). Persistence of inflammation after a renal ischemic injury has been observed, both in experimental models and patients, and is thought to be an important mechanisms underlying progression of acute-to-chronic renal injury. Temporary suppression of inflammation immediately after AKI might therefore be a good first-line therapeutic strategy towards a better long term outcome.

Methods

Male C57Bl/6 J mice (Charles River, 10–12 weeks of age) underwent warm (36 °C body temperature) unilateral ischemia-reperfusion of the kidney for 21 min, after which treatment with intraperitoneal injection of the corticosteroid dexamethasone (10 mg/kg) was initiated for 3 weeks. Both at that time point and after an additional 3 week post-treatment follow up period, fibrosis was quantified by collagen I gene expression and immunostaining, as well as gene expression analysis of fibrosis-related genes Tgfβ, Ccn2 (Ctgf), Pai-1 and Ccn3. Furthermore, inflammation was evaluated by Tnfα gene expression and protein expression of the F4/80 macrophage marker and the α-SMA fibroblast marker. Lastly, renal histopathology was quantified by a morphometric analysis of the tubulointerstitial area.

Results

Treatment with dexamethasone attenuated development of fibrosis, as evidenced by reduced collagen I gene expression and immunostaining, in combination with reduced gene expression of the pro-fibrotic Ccn2 and increased expression of the anti-fibrotic Ccn3. The effects of dexamethasone on renal fibrosis persisted during the 3 week follow up period, as evidenced by stagnation of collagen I deposition in the ischemic kidney, in contrast to vehicle-treatment, where progression of fibrosis was observed. However, expression levels of the pro-fibrotic genes re-approached those of vehicle-treated injured kidneys suggesting that the effects of dexamethasone on fibrosis beyond the treatment period are temporary.

Conclusion

A short term anti-inflammatory therapy with dexamethasone only transiently attenuates ischemia induced fibrosis. Prolonged or persistent anti-inflammatory treatment seems warranted to achieve long term benefit.

Electronic supplementary material

The online version of this article (10.1186/s12882-018-1151-7) contains supplementary material, which is available to authorized users.

Piceatannol pretreatment alleviates acute cardiac injury via regulating PI3K-Akt-eNOS signaling in H9c2 cells

Piceatannol (3,3',4,5'-trans-trihydroxystilbene) is a natural polyphenols compound that occurs hydroxylated analogue of resveratrol showing widely biological activities. Previous studies have demonstrated its functions on anti-cancer, neuroprotection and cardioprotection. However, few studies have clarified the benefits of piceatannol on cardiomyocytes except its anti-oxidative effect based on the original property of polyphenols. Here we apply H9c2 cardiomyocytes to study the cardioprotective mechanisms of piceatannol in vitro. We firstly verify its anti-peroxidation effect by using H₂O₂-induced in vitro model. Then, flow cytometry results show piceatannol reduce cellular apoptosis by enhancing Bcl-2 expressions in immunoblot analysis. Meantime, piceatannol decreases H₂O₂-induced excessive ROS and calcium overloading, and prevents mitochondrial depolarization. Most importantly, piceatannol pretreatment can regulate PI3K-Akt-eNOS signaling pathway to alleviate peroxidative injury. Immunoblot analysis of PI3K, Akt, p-Akt and eNOS shows H₂O₂ significantly reduces expressions of these proteins. Pretreatment of piceatannol evidently increases their expressions and decreases iNOS expression, implying piceatannol can upregulate PI3K-Akt-eNOS signaling to protect cardiomyocytes from peroxidative injury.

Magnesium isoglycyrrhizinate protects against renal‑ischemia‑reperfusion injury in a rat model via anti‑inflammation, anti‑oxidation and anti‑apoptosis

The present study aimed to investigate whether magnesium isoglycyrrhizinate protects against renal ischemia‑reperfusion injury (RIRI), and to verify the underlying mechanisms. An RIRI rat model was induced by removing the right kidney, and exposing and clamping the left kidney. RIRI model rats were administered 30 mg/kg magnesium isoglycyrrhizinate for 3 days. Blood urea nitrogen (BUN) and serum creatinine levels in the blood of RIRI model rat were examined, compared with sham‑operated controls. Magnesium isoglycyrrhizinate suppressed the activities of tumor necrosis factor‑α, interleukin (IL)‑1β, IL‑6, superoxide dismutase, glutathione peroxidase, inducible nitric oxide synthase (iNOS) and caspase‑3 in RIRI model rats. Renal iNOS, matrix metalloproteinase (MMP)‑2, phosphorylated‑signal transducers and activators of transcription 3 (STAT3) and intercellular adhesion molecule‑1 (ICAM‑1) protein expression levels were suppressed by magnesium isoglycyrrhizinate treatment in RIRI model rats. These findings suggested that magnesium isoglycyrrhizinate protects RIRI via anti‑inflammatory, ‑oxidative and ‑apoptotic mechanisms in an RIRI rat model. These results implicate magnesium isoglycyrrhizinate pretreatment as a potential approach to protect against RIRI via suppression of the iNOS, ICAM‑1, MMP‑2 and STAT3 signaling pathways.

Niclosamide attenuates inflammatory cytokines via the autophagy pathway leading to improved outcomes in renal ischemia/reperfusion injury

Renal ischemia/reperfusion (I/R) injury is a debilitating condition that leads to loss renal function and damage to kidney tissue in the majority of patients with acute kidney disease. Previous studies have indicated that autophagy serves a protective function in renal I/R injury. In the present study, the effect of the anthelmintic niclosamide in the regulation of inflammatory responses in kidney I/R was investigated. A total of 40 Sprague-Dawley rats were randomly divided into the following 5 groups (n=8 in each group): Sham group; renal I/R injury; renal I/R injury plus 3-methyladenine (3-MA) treatment (15 mg/kg); renal I/R injury plus niclosamide (25 mg/kg); and renal I/R injury plus rapamycin (10 mg/kg). The expression levels of autophagy-associated proteins in kidney samples obtained from rats with I/R injury were examined using reverse transcription-quantitative polymerase chain reaction and western blotting techniques. In addition, histopathological alterations, the expression of cytokines and renal function were evaluated. Treatment with niclosamide was associated with induction of autophagy and an overall improvement in renal function. There was an increased expression of autophagosome-associated proteins, suggesting a strong correlation between autophagy and improvement of renal function. The increased levels of anti-inflammatory cytokines and decreased levels of pro-inflammatory cytokines provided additional evidence that niclosamide may be effective for the treatment of renal I/R injury. Clinical studies are required to further validate the results of the present study.

Small interfering RNA targeting TNF-α gene significantly attenuates renal ischemia-reperfusion injury in mice

Tumor necrosis factor-alpha (TNF-α) has been found to be centrally involved in the development of ischemia-reperfusion injury (IRI)-induced inflammation and apoptosis. Knockdown of TNF-α gene using small interfering RNA (siRNA) may protect renal IRI. Renal IRI was induced in mice by clamping the left renal pedicle for 25 or 35 min. TNF-α siRNA was administered intravenously to silence the expression of TNF-α. The therapeutic effects of siRNA were evaluated in terms of renal function, histological examination, and overall survival following lethal IRI. A single systemic injection of TNF-α siRNA resulted in significant knockdown of TNF-α expression in ischemia-reperfusion injured kidney. In comparison with control mice, levels of BUN and serum creatinine were significantly reduced in mice treated with siRNA. Pathological examination demonstrated that tissue damage caused by IRI was markedly reduced as a result of TNF-α siRNA treatment. Furthermore, survival experiments showed that nearly 90% of control mice died from lethal IRI, whereas more than 50% of siRNApretreated mice survived until the end of the eight-day observation period. We have demonstrated for the first time that silencing TNF-α by specific siRNA can significantly reduce renal IRI and protect mice against lethal kidney ischemia, highlighting the potential for siRNA-based clinical therapy.

Honokiol protects against renal ischemia/reperfusion injury via the suppression of oxidative stress, iNOS, inflammation and STAT3 in rats

Honokiol is the predominant active ingredient in the commonly used traditional Chinese medicine, Magnolia, which has been confirmed in previous studies to exhibit anti-oxidation, antimicrobial, antitumor and other pharmacological effects. However, its effects on renal ischemia/reperfusion injury (IRI) remain to be elucidated. The present study aimed to examine the effects of honokiol on renal IRI, and to investigate its potential protective mechanisms in the heart. Male adult Wistar albino rats were induced into a renal IRI model. Subsequently, the levels of serum creatinine, blood urea nitrogen (BUN), alanine aminotransferase (ALT), aspartate aminotransferase (AST) and alkaline phosphatase (ALP), and the levels of serum nitrite and the kidney nitrite were examined in the IRI group. The levels of oxidative stress, inducible nitric oxide synthase (iNOS), inflammatory factors and caspase-3 were evaluated using a series of commercially available kits. The levels of phosphorylated signal transducer and activator of transcription 3 (p-STAT3) and the protein expression levels of STAT3 were determined using western blotting. Pretreatment with honokiol significantly reduced the levels of serum creatinine, BUN, ALT, AST and ALP, and the level of nitrite in the kidney of the IRI group, compared with the control group. The levels of malondialdehyde, the activity of myeloperoxidase, and the gene expression and activity of iNOS were reduced in the IRI rats, compared with the sham-operated rats, whereas the levels of superoxide dismutase and catalase were increased following treatment with honokiol in the IRI rats. In addition, the expression levels of tumor necrosis factor-α and interleukin-6 in the IRI rats were increased by honokiol. Treatment with honokiol suppressed the protein expression levels of p-STAT3 and caspase-3 in the IRI rats. These findings indicated that honokiol protects against renal IRI via the suppression of oxidative stress, iNOS, inflammation and STAT3 in the rat.

Fenofibrate pre-treatment suppressed inflammation by activating phosphoinositide 3 kinase/protein kinase B (PI3K/Akt) signaling in renal ischemia-reperfusion injury

The aim of this study was to investigate the possible beneficial effects of Fenofibrate on renal ischemia-reperfusion injury (IRI) in mice and its potential mechanism. IRI was induced by bilateral renal ischemia for 60 min followed by reperfusion for 24 h. Eighteen male C57BL/6 mice were randomly divided into three groups: sham-operated group (sham), IRI+saline group (IRI group), IRI+Fenofibrate (FEN) group. Normal saline or Fenofibrate (3 mg/kg) was intravenously injected 60 min before renal ischemia in IRI group and FEN group, respectively. Blood samples and renal tissues were collected at the end of reperfusion. The renal function, histopathologic changes, and the expression levels of pro-inflammatory cytokines [interleukin-8 (IL-8), tumor necrosis factor alpha (TNF-α) and IL-6] in serum and renal tissue homogenate were assessed. Moreover, the effects of Fenofibrate on activating phosphoinositide 3 kinase/protein kinase B (PI3K/Akt) signaling and peroxisome proliferator-activated receptor-α (PPAR-α) were also measured in renal IRI. The results showed that plasma levels of blood urea nitrogen and creatinine, histopathologic scores and the expression levels of TNF-α, IL-8 and IL-6 were significantly lower in FEN group than in IRI group. Moreover, Fenofibrate pretreatment could further induce PI3K/Akt signal pathway and PPAR-α activation following renal IRI. These findings indicated PPAR-α activation by Fenofibrate exerts protective effects on renal IRI in mice by suppressing inflammation via PI3K/Akt activation. Thus, Fenofibrate could be a novel therapeutic alternative in renal IRI.