Effect of IGF-1C domain-modified nanoparticles on renal ischemia-reperfusion injury in mice

Renal ischemia–reperfusion injury (IRI) is a common prerequisite of acute renal injury (AKI) that involves the entire system and induces critical illness. The C domain of insulin-like growth factor-1 (IGF-1C) plays an important role in promoting angiogenesis and enhancing the inflammatory response. However, given the shortcomings of its short half-life and poor stability, the application of IGF-1C is restricted. In the present study, IGF-1C nanoparticles (NP-IGF-1C) were constructed by combining 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[maleimide (polye thyleneglycol)](DSPE-PEG-MAL) and IGF-1C through a Michael addition reaction to evaluate the effects of NP-IGF-1C on preventing IRI. In vitro studies have shown that NP-IGF-1C is not cytotoxic and protects cells from oxidative damage. The renal enrichment and biocompatibility of NP-IGF-1C were determined in vivo by connecting fluorescent molecules to NP-IGF-1C for in vivo imaging and pathological staining of important organs. After IRI, renal function decreased, and inflammatory cell infiltration, oxidative stress and apoptosis increased. As expected, NP-IGF-1C reversed these changes, indicating that NP-IGF-1C played a protective role in the process of IRI, which may be mediated by its antioxidant, anti-inflammatory and antiapoptotic activities.

Propofol Reduces Renal Ischemia Reperfusion-mediated Necroptosis by Up-regulation of SIRT1 in Rats

Propofol (Pro) is well known to regulate the asleep-awake-asleep technique. Increasing indication recommends that Pro also has promising properties such as anti-oxidant and anti-inflammation belongings in several disease models. It has been described that Pro has beneficial properties against renal ischemia/reperfusion (rI/R)-mediated acute lung injury (ALI). Nevertheless, pathogenesis underlying the beneficial action of Pro on the remote ALI mediated by rI/R remains unwell unstated. In this research, we displayed that Pro administration remarkably inhibits rI/R-mediated pro-inflammatory cytokines production. Increased levels of oxidative stress were mainly decreased by Pro. Pro administration ameliorated apoptosis-related caspase-3 activation. Furthermore, the levels of crucial necroptosis-associated protein were reduced by Pro. Sirtuin 1 (SIRT1) inhibitor attenuated the aforementioned changes of Pro. In conclusion, these results propose that Pro attenuates rI/R-induced inflammation, oxidative stress, apoptosis, and necroptosis by up-regulation of SIRT1 in rats. Our findings disclose an original pathogenesis underlying the beneficial effect of Pro against rI/R-mediated ALI and reinforce the knowledge that Pro might be a hopeful beneficial agent for the rI/R-mediated ALI.

miR-10a overexpression aggravates renal ischemia-reperfusion injury associated with decreased PIK3CA expression

BACKGROUND

To investigate the effect of miR-10a on renal tissues with ischemia reperfusion (I/R) injury in rats and to explore the underlying mechanisms of the effect of miR-10a on hypoxia-reoxygenation in HK-2 cells.

METHODS

MiR-10a level was measured in the renal tissues of rats with I/R rats using RT-PCR. In order to research the role of miR-10a in renal tissues, an miR-10 agonist and an miR-10a antagonist were used to treat I/R-injured rats. Levels of serum creatinine and blood urea nitrogen, renal histopathology, and levels of cell apoptosis were analyzed separately in renal tissues from the rats. Phosphatidylinositol 3-kinase (PI3K)/Akt pathway related proteins were measured by Western blotting. In addition, HK-2 cells were cultured in order to study the mechanism of action of miR-10a in the hypoxia-reoxygenation model being studied. Finally, the dual luciferase reporter gene assay was used to confirm that the PI3K p100 catalytic subunit α (PIK3CA) gene was targeted by miR-10a.

RESULTS

After renal I/R injury in rats, miR-10a expression increased significantly (p < 0.05). Injection of miR-10a agonist significantly aggravated the renal injury and raised the level of cell apoptosis in the renal tissues of I/R-injured rats (p < 0.05). However, administration of miR-10a antagonist led to obvious improvement of the renal injury, decreased renal cell apoptosis, and inhibited PI3K/Akt pathway activity (p < 0.05). In in vitro experiments, the negative relationship between PIK3CA and miR-10a levels was confirmed. Furthermore, overexpression of miR-10a significantly decreased the proliferation of HK-2 cells, and increased cell apoptosis via up-regulation of the PI3K/Akt pathway (p < 0.05).

CONCLUSION

The aggravation of renal I/R injury by miR-10a was associated with a decrease in the activity of PIK3CA/PI3K/Akt pathway.

Luteolin confers renoprotection against ischemia-reperfusion injury via involving Nrf2 pathway and regulating miR320

This work aims to evaluate the renoprotective effect of luteolin on expression of Nrf2 and miR320 in ischemia-reperfusion (I/R) injury in rats. Thirty rats were randomly divided into five groups; control, Luteolin (50 mg/kg), ischemia-reperfusion (I/R), DMSO (0/1%) + I/R and Luteolin+I/R, (n = 6 each). Administration of luteolin and DMSO was carried out by gavage for 3 days before renal I/R. Then, the rats were subjected to bilateral renal ischemia for 45 min and followed by reperfusion for 2 h. All rats were killed and the renal function, histological changes, oxidative stress degree, in all of groups were evaluated. In addition, the effects of luteolin on renal expression of Nrf2 and miR320 were examined by immunohistochemistry and real time- PCR. Luteolin significantly improved the creatinine (Cr) and blood urea nitrogen (BUN) levels in Luteolin + I/R group compared to I/R group (p < 0.001 and p < 0.001 respectively). Reduction of enzymatic activity of superoxide dismutase, glutathione peroxidase and catalase in I/R and DMSO + I/R groups, was significantly improved by Luteolin (p < 0.05) in Luteolin + I/R group. Pre-treatment with luteolin also resulted in significant reduction in tissue MDA level (p < 0.001), Nrf2 (p < 0.001) and miR320 expression (P < 0.05) that were increased by renal I/R. Also, the rats pretreated with luteolin had nearly normal structure of the kidney. These results indicate that luteolin protects the kidney against I/R injury via reducing oxidative stress, increasing antioxidant enzymes and reducing expression of Nrf2 and miR320.

Dexmedetomidine attenuates lung apoptosis induced by renal ischemia-reperfusion injury through α2AR/PI3K/Akt pathway

Background

Acute lung injury caused by renal ischemia–reperfusion is one of the leading causes of acute kidney injury-related death. Dexmedetomidine, an α₂-adrenergic agonist sedative, has been found to have protective effects against acute kidney injury and remote lung injury. We sought to determine whether dexmedetomidine can exert its anti-apoptotic effects in acute lung injury after acute kidney injury, in addition to its common anti-inflammatory effects, and to determine the underlying mechanisms.

Methods

In vivo, acute kidney injury was induced by 60 min of kidney ischemia (bilateral occlusion of renal pedicles) followed by 24 h of reperfusion. Mice received dexmedetomidine (25 µg/kg, i.p.) in the absence or presence of α₂-adrenergic antagonist atipamezole (250 µg/kg, i.p.) before IR. Histological assessment of the lung was conducted by HE staining and arterial blood gases were measured. Lung apoptosis was assessed by terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling assay. The expression of caspase 3 and p-Akt in lung tissue was detected by western blot. In vitro, C57BL/6J mice pulmonary microvascular endothelial cells were treated with serum from mice obtained following sham or IR. Dexmedetomidine was given before serum stimulation in cells, alone or with atipamezole or LY294002. Cell viability was assessed by CCK 8 assay. Cell apoptosis was examined by Hoechst staining and Annexin V-FITC/PI staining flow cytometry analysis. Mitochondrial membrane potential was measured by flow cytometry. The expression of p-Akt, caspase 3, Bcl-2 and Bax was measured by western blot.

Results

In vivo, dexmedetomidine remarkably mitigated pathohistological changes and apoptosis and significantly increased p-Akt expression in the lung. In addition, dexmedetomidine also slightly improved oxygenation in mice after IR, which can be abolished by atipamezole. In vitro, dexmedetomidine significantly inhibited IR serum-induced loss of viability and apoptosis in PMVECs. Dexmedetomidine increased p-Akt in a time- and dose-dependent manner, and down-regulated the expression of caspase 3 and Bax and up-regulated the Bcl-2 expression in PMVECs. The changes of MMP were also improved by dexmedetomidine. Whilst these effects were abolished by Atipamezole or LY294002.

Conclusion

Our results demonstrated that dexmedetomidine attenuates lung apoptosis induced by IR, at least in part, via α₂AR/PI3K/Akt pathway.

Protective effects of tirofiban on ischemia/reperfusion-induced renal injury in vivo and in vitro

Tirofiban, a glycoprotein IIb/IIIa receptor inhibitor, is widely used in the management of patients with unstable angina or myocardial infarction, and shows protective effects on ischemia/reperfusion (I/R) injured heart. Whether or not it has protective effect on I/R injured kidney is not known. The present in vivo and in vitro study found that serum creatinine (SCR) and blood urea nitrogen (BUN) were significantly increased in I/R rats, accompanied by histopathological damage of the kidney. Apoptotic cells, leukocyte infiltration and ROS production were increased in I/R rats. Pretreatment by intravenous injection of tirofiban (200μg/kg) reduced SCR and BUN levels, ameliorated renal histopathological changes, and decreased ROS production, cell apoptosis and leukocyte infiltration in I/R injured kidney. Our further study showed that the protection of tirofiban might be associated with the restoration of eNOS/iNOS balance, since inhibition of NO production blocked the tirofiban-mediated renal protection on I/R injury. The present in vivo and in vitro study indicated that tirofiban pretreatment exerts a protective effect on I/R injury in kidney through regulation of eNOS/iNOS balance.

The protective effects of prostaglandin E1 on lung injury following renal ischemia-reperfusion in rats

For the purposes of the present study, the protective effect of prostaglandin E1 (PGE1) on lung injury following renal ischemia-reperfusion (RIR) was investigated. Adult male rats were divided into four groups, namely, (I) control rats given physiological saline; (II) rats given PGE1 (20 μg/kg, intravenously); (III) rats subjected to RIR; and (IV) rats subjected to RIR given PGE1 30 min prior to ischemia and just before reperfusion. The right nephrectomy was performed in the RIR model. The left renal pedicle was occluded for 60 min to induce ischemia and then the left kidney was subjected to reperfusion for 60 min. The lungs of rats were used for microscopic and biochemical analyses. Although rats subjected to RIR did not exhibit heavy degenerative alterations in the lung structure, they possessed pulmonary interstitial edema. Lung glutathione levels and catalase, superoxide dismutase, glutathione peroxidase, and tissue factor (TF) activities were decreased in rats subjected to RIR, while lung lipid peroxidation, myeloperoxidase (MPO), xanthine oxidase and serum lactate dehydrogenase (LDH) activities, and blood urea and serum creatinine levels were increased in these rats when compared with the control group. PGE1 treatments resulted in the regression of oxidative stress via induction of antioxidant system, the decreased MPO and LDH activities, the reduced urea and creatinine levels, and the induced TF activity in rats subjected to RIR, while edema still remained permanent. We conclude that PGE1 may be useful in preventing lung injury with the exception of edema that occurred as a result of RIR in rats.

SUMOylation occurs in acute kidney injury and plays a cytoprotective role

SUMOylation is a form of post-translational modification where small ubiquitin-like modifiers (SUMO) are covalently attached to target proteins to regulate their properties. SUMOylation has been demonstrated during cell stress and implicated in cellular stress response. However, it is largely unclear if SUMOylation contributes to the pathogenesis of kidney diseases, such as acute kidney injury (AKI). Here we have demonstrated a dynamic change of protein SUMOylation in ischemic and cisplatin nephrotoxic AKI in mice. In rat kidney proximal tubular cells (RPTC), cisplatin-induced SUMOylation was diminished by two antioxidants (N-acetylcysteine and dimethylurea), supporting a role of oxidative stress in the activation of SUMOylation. In addition, SUMOylation by SUMO-2/3, but not SUMO-1, was partially suppressed by pifithrin-alpha (a pharmacological inhibitor of p53), supporting a role of p53 in SUMOylation by SUMO-2/3. We further examined the role of SUMOylation during cisplatin treatment of RPTC by using ginkgolic acid (GA), a pharmacological inhibitor of SUMOylation. Pretreatment with GA suppressed SUMOylation and importantly, GA enhanced apoptosis during cisplatin incubation. Taken together, the results demonstrate the first evidence of SUMOylation in AKI and suggest that SUMOylation may play a cytoprotective role in kidney tubular cells.

Novel resveratrol analogues attenuate renal ischemic injury in rats

BACKGROUND

Renal ischemia-reperfusion (I/R) is a severe clinical complication with no specific treatment. Resveratrol has been shown as a promising experimental agent in renal I/R due to its effect on cellular energy metabolism, oxidative stress, and inflammation. Recently, we identified two biologically active resveratrol analogues (RSVAs), RSVA405 and RSVA314. We hypothesized that both RSAVs would attenuate I/R-induced renal injury.

METHODS

Adult male rats were subjected to renal I/R through bilateral renal pedicle clamping for 60 min, followed by reperfusion. RSVA405 (3 mg/kg Body Weight), RSVA314 (3 mg/kg Body Weight), or vehicle (10% dimethyl sulfoxide and 33% Solutol in phosphate buffered saline) were administered by intraperitoneal injection 1 h before ischemia. Blood and renal tissues were collected 24 h after I/R for evaluation.

RESULTS

Administration of RSVA405 and RSVA314 significantly reduced the serum levels of renal dysfunction and injury markers, including creatinine, blood urea nitrogen, aspartate aminotransferase, and lactate dehydrogenase, compared with vehicle. The protective effect of RSVA405 and RSVA314 was also reflected on histologic evaluation. Both RSVAs reduced the number of apoptotic cells by more than 60% as determined by transferase dUTP nick end labeling assay, compared with vehicle. The renal adenosine triphosphate levels of the vehicle group was decreased to 52.4% of control, whereas those of the RSVA405 and RSVA314 groups were restored to 72.3% and 79.6% of control, respectively. Both RSVAs significantly reduced the protein expression of inducible nitric oxide synthase and nitrotyrosine and the messenger RNA levels of tumor necrosis factor-α, interleukin-6, and interleukin-1β.

CONCLUSIONS

RSVA405 and RSVA314 attenuate I/R-induced renal injury through the modulation of energy metabolism, oxidative stress, and inflammation.

DNA damage response in renal ischemia-reperfusion and ATP-depletion injury of renal tubular cells

Renal ischemia-reperfusion leads to acute kidney injury (AKI) that is characterized pathologically by tubular damage and cell death, followed by tubular repair, atrophy and interstitial fibrosis. Recent work suggested the possible presence of DNA damage response (DDR) in AKI. However, the evidence is sketchy and the role and regulation of DDR in ischemic AKI remain elusive. In this study, we demonstrated the induction of phosphorylation of ATM, H2AX, Chk2 and p53 during renal ischemia-reperfusion in mice, suggesting DDR in kidney tissues. DDR was also induced in vitro during the recovery or "reperfusion" of renal proximal tubular cells (RPTCs) after ATP depletion. DDR in RPTCs was abrogated by supplying glucose to maintain ATP via glycolysis, indicating that the DDR depends on ATP depletion. The DDR was also suppressed by the general caspase inhibitor z-VAD and the overexpression of Bcl-2, supporting a role of apoptosis-associated DNA damage in the DDR. N-acetylcysteine (NAC), an antioxidant, suppressed the phosphorylation of ATM and p53 and, to a less extent, Chk2, but NAC increased the phosphorylation and nuclear foci formation of H2AX. Interestingly, NAC increased apoptosis, which may account for the observed H2AX activation. Ku55933, an ATM inhibitor, blocked ATM phosphorylation and ameliorated the phosphorylation of Chk2 and p53, but it increased H2AX phosphorylation and nuclear foci formation. Ku55933 also increased apoptosis in RPTCs following ATP depletion. The results suggest that DDR occurs during renal ischemia-reperfusion in vivo and ATP-depletion injury in vitro. The DDR is partially induced by apoptosis and oxidative stress-related DNA damage. ATM, as a sensor in the DDR, may play a cytoprotective role against tubular cell injury and death.

Protective effect of tea polyphenols on renal ischemia/reperfusion injury via suppressing the activation of TLR4/NF-κB p65 signal pathway

Tea polyphenols (TP) was investigated in rats for its protective effect on renal ischemia/reperfusion injury (RIRI). Rats were randomized into groups as follows: (I) sham group (n=10); (II) RIRI group (n=10); (III) RIRI+TP (100mg/kg) group (n=5); (IV) RIRI+TP (200mg/kg) group (n=5); (V) RIRI+TP+ Astragalus mongholicus aqueous extract (AMAE) (300 mg/kg+100mg/kg) group (n=5). For the IRI+TP groups, rats were orally given with tea polyphenols (100, 200 and 300 mg/kg body weight) once daily 10 days before induction of ischemia, followed by renal IRI. For the sham group and RIRI group, rats were orally given with equal volume of saline once daily 10 days before induction of ischemia, followed by renal IRI. Results showed that tea polyphenol pretreatment significantly suppressed ROS level and MDA release. On the other hand, in rats subjected to ischemia-reperfusion, the activities of endogenous antioxidant enzymes including superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR) and glutathione peroxidase (GSH-Px) showed recovery, whereas the levels of urea nitrogen and serum creatinine were reduced by administration of tea polyphenols orally for 10 days prior to ischemia-reperfusion. Moreover, tea polyphenol pretreatment significantly decreased TLR4 and NF-κB p65 protein expression levels in RIRI rats. At the same time, tea polyphenol pretreatment attenuated the increased level of serum IL-1β, IL-6, ICAM-1 and TNF-α, and enhanced IL-10 production in RIRI rats. Furthermore, tea polyphenol pretreatment significantly decreased renal epithelial tubular cell apoptosis induced by renal ischemia/reperfusion, alleviating renal ischemia/reperfusion injury. These results cumulatively indicate that tea polyphenol pretreatment could suppress the TLR4/NF-κB p65 signaling pathway, protecting renal tubular epithelial cells against ischemia/reperfusion-induced apoptosis, which implies that antioxidants may be a potential and effective agent for prevention of the ischemic/reperfusion injury through the suppression extrinsic apoptotic signal pathway induced by TLR4/NF-κB p65 signal pathway. Moreover, supplement of AMAE can increased renal protection effect of TP.

Protective effects of aliskiren on ischemia-reperfusion-induced renal injury in rats

The protective effect of aliskiren on ischemia-reperfusion (I/R) injury in the heart and brain has been reported. Whether or not this protective effect extends into the alleviation of renal I/R injury is not known. Therefore, we investigated the protective effect of aliskiren in the kidney in this study. Sprague-Dawley rats were randomly divided into four groups: sham control group; sham control with aliskiren pretreatment; I/R group and I/R with aliskiren pretreatment. Aliskiren (3mg/kg) or vehicle was administrated intravenously via vena cava. Blood samples and the left kidneys were then collected to check for renal function, angiotensin II (Ang II), apoptosis and oxidative stress levels. Compared with the sham rats, serum creatinine (SCR) and blood urea nitrogen (BUN) were significantly increased in the I/R rats, accompanied by histopathological damage to the kidney, which included tubular cell swelling, desquamation, and cast formation. There were also more apoptotic cells and leukocyte infiltration in the I/R rats than in the sham rats. Pretreatment with aliskiren ameliorated I/R induced renal injury, i.e. reduced SCR and BUN levels, ameliorated renal histopathological changes, and decreased the apoptosis of cells and leukocyte infiltration in kidney. I/R injury also decreased superoxide dismutase (SOD) and glutathione (GSH-reduced form) levels, which were blocked with the aliskiren pretreatment. Aliskiren pretreatment exerts a protective effect on ischemia/reperfusion injury in the kidney, via amelioration of oxidative stress, and reduction in leukocyte infiltration and cellular apoptosis.

Celastrol protects kidney against ischemia-reperfusion-induced injury in rats

BACKGROUND

Ischemia-reperfusion (IR) causes various damages in renal tissues, which is exacerbated by hypoxia-induced excessive inflammation and deteriorates the prognosis of patients after kidney surgery. Celastrol is a potent inflammation inhibitor that has little toxicity. In this report, we investigated whether celastrol protects against IR-induced renal injury in rats.

MATERIALS AND METHODS

Renal IR injury was induced by occlusion of the bilateral renal pedicles for 45 min followed by reperfusion for 6 h. Celastrol or vehicle solution was intraperitoneally injected 30 min before renal ischemia, respectively. Renal histology, function, and pro-inflammatory cytokines and mediators were assessed. The effect of celastrol on nuclear translocation of nuclear factor kappa B (NF-κB) was also measured.

RESULTS

Celastrol significantly suppressed elevation of the renal function markers and the lipid peroxidation level, alleviated renal tubular damage, and decreased the levels of tumor necrosis factor-α, interleukin-1β, and monocyte chemotactic protein-1 (MCP-1) messenger RNA in kidney caused by IR. Moreover, celastrol prevented IR-induced expression of pro-inflammatory mediators, which was associated with suppression of nuclear translocation of NF-κB subunit p65.

CONCLUSIONS

Celastrol ameliorated the acute kidney injury caused by IR, which was associated with inhibiting local NF-κB activation and inflammation. Our findings suggest that celastrol could be useful for preventing IR-induced renal injury.