Protective Effect of Erythropoietin on Renal Injury Induced by Acute Exhaustive Exercise in the Rat

Neutrophil depletion attenuates acute renal injury after exhaustive exercise in mice

Prolonged intense exercise induces acute renal injury; however, the precise mechanism remains unclear. We investigated the effects of neutrophil depletion in male C57BL/6J mice. Male C57BL/6J mice were divided into four groups: sedentary with control antibody; sedentary with antineutrophil antibody; exhaustive exercise with control antibody; and exhaustive exercise with antineutrophil antibody. Antineutrophil (1A8) or control antibody was administered i.p. to the mice before they ran on a treadmill. Plasma levels of creatinine and blood urea nitrogen (BUN) were measured. Renal histology was assessed 24 h after exhaustive exercise, and the concentration of kidney injury molecule (KIM)-1 was measured using an enzyme-linked immunosorbent assay. The expression levels of inflammatory cytokines were measured using qRT-PCR. Furthermore, NADPH oxidase activity and the hydrogen peroxide concentration in the kidney were measured. Immediately after exhaustive exercise, plasma BUN was significantly increased, but creatinine was not. The increase in BUN after exercise was suppressed by 1A8 treatment. The pathological changes manifested as congested and swollen glomeruli and nuclear infiltration after exhaustive exercise. These changes were suppressed by treatment with the 1A8 antibodies. The KIM-1 concentration increased after exhaustive exercise but was reduced by the 1A8 antibodies. Treatment with the 1A8 antibody also decreased exhaustive exercise-induced inflammation and reactive oxygen species levels in the kidney. These results suggest that neutrophils contribute to exercise-induced acute renal injury by regulating inflammation and oxidative stress.

Restoration of autophagy activity by dipsacoside B alleviates exhaustive exercise-induced kidney injury via the AMPK/mTOR pathway

Exhaustive exercise (EE) induces kidney injury, but its concrete mechanism has not been fully elucidated. Hepatoprotective effects of dipsacoside B (DB) have been found previously, involving in autophagy induction. However, whether DB exerts renal protective effect and its potential mechanism are still unknown. The present study aimed to investigate the benefit of DB in EE-induced kidney injury and decipher its underlying mechanism. Here, we found that DB ameliorated EE-induced renal dysfunction and renal histopathological injury in rats. DB possessed anti-inflammatory, anti-oxidative, and anti-apoptotic functions in kidneys of exercise-induced exhausted rats. Besides, DB improved autophagy function in kidneys of EE rats. Mechanically, activation of the adenylate-activating protein kinase (AMPK)/mammalian target of rapamycin (mTOR) pathway was implicated in the kidney injury-relieving effects and autophagy restoration induced by DB. Collectively, these findings provide reference for the clinical application of DB in preventing and managing EE-induced kidney injury.

Macrophage depletion attenuates acute renal damage after exhaustive exercise in mice

Exhaustive exercise is known to induce acute renal damage. However, the precise mechanisms remain unclear. We investigated the effects of macrophage depletion on exhaustive exercise-induced acute renal damage. Male C57BL/6 J mice were divided into four groups: sedentary with control liposome (n=8), sedentary with clodronate liposome (n=8), exhaustive exercise with control liposome (n=8), and exhaustive exercise with clodronate liposome (n=8). Mice were treated with clodronate liposomes or control liposomes intraperitoneally for 48 h before undergoing exhaustive exercise. Renal function and renal histology were tested at 24 h. The expression levels of kidney injury molecule (KIM)-1 and inflammatory cytokines in kidney tissues were measured by quantitative RT-PCR, and KIM-1 concentration was semi-quantified by immunostaining. As a result, exhaustive exercise increased macrophage infiltration into the kidney. However, clodronate reduced it. Although exhaustive exercise resulted in an increase in KIM-1 mRNA expression levels and concentration, injection of clodronate liposome reduced it. In addition, TUNEL positive apoptotic cells were increased after exercise, but significantly reduced by clodronate. Clodronate liposome treatment also decreased the mRNA expression levels of inflammatory cytokines (TNF-α, IL-1β, and IL-6) in the kidney after exhaustive exercise. These results suggest that macrophages play a critical role in increasing renal damage by regulating inflammation.

Bridging Translation by Improving Preclinical Study Design in AKI

Despite extensive research, no therapeutic interventions have been shown to prevent AKI, accelerate recovery of AKI, or reduce progression of AKI to CKD in patients. This failure in translation has led investigators to speculate that the animal models being used do not predict therapeutic responses in humans. Although this issue continues to be debated, an important concern that has not been addressed is whether improvements in preclinical study design can be identified that might also increase the likelihood of translating basic AKI research into clinical practice using the current models. In this review, we have taken an evidence-based approach to identify common weaknesses in study design and reporting in preclinical AKI research that may contribute to the poor translatability of the findings. We focused on use of N-acetylcysteine or sodium bicarbonate for the prevention of contrast-induced AKI and use of erythropoietin for the prevention of AKI, two therapeutic approaches that have been extensively studied in clinical trials. On the basis of our findings, we identified five areas for improvement in preclinical study design and reporting. These suggested and preliminary guidelines may help improve the quality of preclinical research for AKI drug development.

Protective effect of erythropoietin on renal injury induced in rats by four weeks of exhaustive exercise

Background

The protective effect of Erythropoietin (EPO) analogue rHuEPO on acute renal injury induced by exhaustive exercise had been reported. The purpose of this study is to probe into the protective effect of EPO on chronic renal injury induced by repeated exhaustive exercise for four weeks.

Methods

Eighty adult male Sprague–Dawley rats were used in this experiment. The animals were randomly allocated to one of four groups: control (C), exhaustive exercise test (ET), ET plus EPO pre-treatement (ET+EPO) and ET+EPO plus LY294002 pretreatment (ET+EPO+LY).

Results

Compared with the rats in control group, there was considerable damage in kidney cells in rats of ET group as revealed by histological and ultrastructural examinations. However, treatment with EPO during the training, the exhaustive running distance was significant increased (P < 0.01), and the pathological changes of kidney cell were much less compared with those of rats without EPO intervention. When LY294002, a specific inhibitor of phospholipids phthalocyanine inositol 3-kinase, was added to the EPO treated rats, the injury changes of renal cell were becoming more pronounced.

Conclusions

The protective effect of EPO on chronic renal injury induced by repeated exhaustive exercise was demonstrated in the present study. We proposed that the effect could be due to inhibiting the cell apoptosis and blocking the formation of interstitial fibrosis via activation of the PI3K/Akt pathway, thus plays role in the endogenous protection of the kidney injury.

Effects of voluntary wheel running on the kidney at baseline and after ischaemia-reperfusion-induced acute kidney injury: a strain difference comparison

Exercise-induced vascular endothelial adaptations in the kidney are not well understood. Therefore, we investigated the impact of voluntary wheel running (VWR) on the abundance of endothelial nitric oxide synthase (eNOS) and extracellular superoxide dismutase (EC SOD), in kidney and lung, and other SOD isoforms and total antioxidant capacity (TAC), in kidney. We also determined whether VWR influences susceptibility to acute kidney injury (AKI). Male Sprague-Dawley and Fisher 344 rats, VWR or sedentary for 12 weeks, were subjected to AKI (uninephrectomy (UNX) and 35 min of left kidney ischaemia-24 h reperfusion, IR). We measured glomerular filtration rate (GFR) and renal plasma flow (RPF), and analysed renal structural injury. Running was comparable between strains and VWR reduced body weight. In Sprague-Dawley rats, VWR reduced eNOS and EC SOD, but increased Mn SOD in kidney. Similar changes were seen after 6 weeks of VWR in Sprague-Dawley rats. In Fisher 344 rats, VWR increased eNOS, all SOD isoforms and TAC in kidney. Both strains increased eNOS and EC SOD in lung with VWR. Compared to UNX alone, UNX-IR injury markedly reduced renal function for both strains; however, in the Sprague-Dawley rats, VWR exacerbated falls in GFR and RPF due to UNX-IR, whereas in the Fisher 344 rats, GFR was unaffected by VWR. Some indices of renal structural injury due to UNX-IR tended to be worse in SD vs. F344. Our study demonstrates that genetic background influences the effect of exercise on kidney eNOS and EC SOD, which in turn influence the susceptibility to AKI.

Is there any way to protect from tacrolimus-induced renal and pancreas injury?

BACKGROUND

The aim of this study was to explore effects of erythropoietin and pentoxifylline in tacrolimus-induced pancreatic beta cell and renal injury in rats.

METHODS

Rats in group I were given saline; rats in group II were injected with tacrolimus; rats in group III were received erythropoietin (Epo) and tacrolimus; while rats in group IV were injected pentoxifylline (Ptx) plus tacrolimus for nine d. On 10th day, blood and tissue samples were taken for biochemical and pathological evaluations.

RESULTS

Tacrolimus-injected animals exhibited significant elevation in blood urea nitrogen (BUN), and serum BUN levels were improved in rats pretreated with Ptx. Significantly more apoptotic nuclei were observed in kidneys of tacrolimus group. In rats subjected to tacrolimus and pretreated with Epo, there was significant decrease in apoptotic nuclei staining than those in tacrolimus group. Blood trough levels of tacrolimus were significantly higher in erythropoietin-pretreated group, although same amount of tacrolimus was injected with other groups.

CONCLUSION

Results of our study demonstrated significant antiapoptotic effects of erythropoietin on renal tubules, increasing effect of erythropoietin on tacrolimus blood levels, and insignificant antioxidant effects of both erythropoietin and pentoxifylline on renal and pancreas tissues. Study with clinically greater tacrolimus levels may be useful to confirm these findings.

The effect of erythropoietin on anastomotic healing of irradiated rats

AIM

The aim of the present study is to evaluate the possible protective effects of erythropoietin (EPO) on anastomotic wound healing after preoperative radiotherapy according to its pleiotropic mechanism of action.

METHODS

Thirty-two male Wistar albino rats were randomized into four groups containing eight rats each: ANAS group, standard resection plus anastomosis; RT+ANAS group, radiation plus standard resection plus anastomosis; ANAS+EPO group, standard resection plus anastomosis plus EPO; RT+ANAS+EPO, radiation plus standard resection plus anastomosis plus EPO. All animals were sacrificed by cardiac puncture, and anastomotic healing was measured by bursting pressure, hydroxyproline (OHP) levels, myeloperoxidase (MPO) activity and histopathological evaluations. Malondialdehyde (MDA), tumor necrosis factor-alpha (TNF-α), and matrix metalloproteinase-9 (MMP-9) were also measured in serum specimens.

RESULTS

OHP levels in the RT+ANAS + EPO group were significantly increased compared with other groups (p < .05). In contrast, MPO activity in the RT+ANAS+EPO group was significantly decreased compared with other groups (p < .05). Serum MDA levels were found to be decreased in the ANAS+EPO and RT+ANAS+EPO groups (p < .05). Group comparisons demonstrated that bursting pressure was significantly higher in EPO treated rats (p < .05). The histopathology results revealed that EPO treatment improves anastomotic wound healing though decreased necrosis and inflammatory cell infiltration and increased fibroblast activity.

CONCLUSION

The findings of the present study indicate that EPO contributes to wound healing and the strength of colon anastomosis following radiation due to its antioxidant and anti-inflammatory effects, but further studies are needed to explore the significance of these effects.