Effects of Ischemic Preconditioning and Postconditioning in a Renal Ischemia-Reperfusion Injury Model: A Comparative Experimental Study in Rats

Is Renal Ischemic Preconditioning an Alternative to Ameliorate the Short- and Long-Term Consequences of Acute Kidney Injury?

Acute kidney injury (AKI) is a global health problem and has recently been recognized as a risk factor for developing chronic kidney disease (CKD). Unfortunately, there are no effective treatments to reduce or prevent AKI, which results in high morbidity and mortality rates. Ischemic preconditioning (IPC) has emerged as a promising strategy to prevent, to the extent possible, renal tissue from AKI. Several studies have used this strategy, which involves short or long cycles of ischemia/reperfusion (IR) prior to a potential fatal ischemic injury. In most of these studies, IPC was effective at reducing renal damage. Since the first study that showed renoprotection due to IPC, several studies have focused on finding the best strategy to activate correctly and efficiently reparative mechanisms, generating different modalities with promising results. In addition, the studies performing remote IPC, by inducing an ischemic process in distant tissues before a renal IR, are also addressed. Here, we review in detail existing studies on IPC strategies for AKI pathophysiology and the proposed triggering mechanisms that have a positive impact on renal function and structure in animal models of AKI and in humans, as well as the prospects and challenges for its clinical application.

Nephroprotective Efficacy of Sugammadex in Ischemia-Reperfusion Injury: An Experimental Study in a Rat Model

Background: It is known that ischemia-reperfusion damage in the kidney is one of the most common causes of acute kidney failure. It is also known that reduced renal damage has a nephroprotective effect by reducing the release of inflammatory and vasoactive peptides that cause tissue damage. Therefore, we think that reperfusion caused by ischemia in kidney damage may be an important focus for clinical research.

Methods: A total of 21 healthy 230-250 g female rats were used in our experimental study. During the experiment, animals were randomly divided into three groups, each containing seven rats. Group 1: The group that underwent left nephrectomy with a sham operation. Group 2: Left renal ischemia for 60 minutes, then left nephrectomy followed by 45 minutes of reperfusion. Group 3: Left renal ischemia for 60 minutes, then reperfusion for 45 minutes, followed by left nephrectomy. In this group, sugammadex was given intravenously at a dose of 100 mg/kg at the beginning of reperfusion. In the histomorphological examination, damage findings of tubules atrophy, dilation and cast formation, tubular epithelial brush border loss and vacuolization, presence of fibrosis as interstitial structural change, capillary vasodilatation/congestion and neutrophilic cell infiltrates in interstitial spaces, and morphological changes in glomeruli were evaluated.

Results: When evaluated based on tubular brush border, there were no significant differences between Group 2 and Group 1 (P = 0.454), while the damage in Group 3 was less significant than Group 2 (P = 0.017). When evaluated in terms of tubular vacuolization, there was no significant difference between Group 2 and Group 1 (P = 0.902), while the damage in Group 3 was less significant than Group 2 (P = 0.017).

Conclusion: We believe that 100 mg/kg sugammadex given at the beginning of reperfusion after one hour of ischemic condition on rats has a histochemically detectable nephroprotective effect.

Subclinical effects of remote ischaemic conditioning in human kidney transplants revealed by quantitative proteomics

Background

Remote ischaemic conditioning (RIC) is currently being explored as a non-invasive method to attenuate ischaemia/reperfusion injuries in organs. A randomised clinical study (CONTEXT) evaluated the effects of RIC compared to non-RIC controls in human kidney transplants.

Methods

RIC was induced prior to kidney reperfusion by episodes of obstruction to arterial flow in the leg opposite the transplant using a tourniquet (4 × 5 min). Although RIC did not lead to clinical improvement of transplant outcomes, we explored whether RIC induced molecular changes through precision analysis of CONTEXT recipient plasma and kidney tissue samples by high-resolution tandem mass spectrometry (MS/MS).

Results

We observed an accumulation of muscle derived proteins and altered amino acid metabolism in kidney tissue proteomes, likely provoked by RIC, which was not reflected in plasma. In addition, MS/MS analysis demonstrated transient upregulation of several acute phase response proteins (SAA1, SAA2, CRP) in plasma, 1 and 5 days post-transplant in RIC and non-RIC conditions with a variable effect on the magnitude of acute inflammation.

Conclusions

Together, our results indicate sub-clinical systemic and organ-localised effects of RIC.

Resemblance and differences in dietary restriction nephroprotective mechanisms in young and old rats

Dietary restriction (DR) is the strategy ameliorating the morbidity of various pathologies, including age-associated diseases. Acute kidney injury (AKI) remains a problem for the elderly with DR being a promising approach for diminishing its consequences. We evaluated the possible nephroprotective potential of short-term DR in young and old rats. DR in young rats resulted in pronounced beneficial effects normalizing lipid metabolism (triglycerides concentration, adiponectin level) activating autophagic-lysosomal system evaluated by LC3II/LC3I ratio, LAMP1, p62/SQSTM1 levels, and LysoTracker Green staining. DR had a remarkable recovering effect on mitochondrial structure and functions including regaining of mitochondrial membrane potential, the elevation of SIRT-3, PGC-1α, _Bcl-XL levels and partial restoration of ultrastructure. The beneficial effects of DR resulted in the mitigation of oxidative stress including a decrease in levels of protein carbonylation and lipid peroxidation. Aging led to decreased activity of autophagy, elevated oxidative stress and impaired kidney regenerative capacity. Eventually, in old rats, even 8-week DR was not able to ameliorate AKI, but it caused some rejuvenating effects including elevation of mitochondrial membrane potential and Bcl-X_L levels, as well as lowered severity of the oxidative stress. Thus, the age-associated decline of protective signaling demands extended DR to achieve nephroprotective potential in old animals.

Effects of grape seed proanthocyanidin B2 pretreatment on oxidative stress and renal tubular epithelial cell apoptosis after renal ischemia reperfusion in mice

PURPOSE

To investigate the effects of grape seed proanthocyanidin B2 (GSPB2) preconditioning on oxidative stress and apoptosis of renal tubular epithelial cells in mice after renal ischemia-reperfusion (RIR).

METHODS

Forty male ICR mice were randomly divided into 4 groups: Group A: mice were treated with right nephrectomy. Group B: right kidney was resected and the left renal vessel was clamped for 45 minutes. Group C: mice were intraperitoneally injected with GSPB2 before RIR established. Group D: mice were intraperitoneally injected with GSPB2 plus brusatol before RIR established. Creatinine and urea nitrogen of mice were determined. Pathological and morphological changes of kidney were checked. Expressions of Nrf-2, HO-1, cleaved-caspase3 were detected by Western-blot.

RESULTS

Compared to Group B, morphology and pathological damages of renal tissue were less serious in Group C. Western-blot showed that expressions of Nrf-2 and HO-1 in Group C were obviously higher than those in Group B. The expression of cleaved-caspase3 in Group C was significantly lower than that in Group B.

CONCLUSION

GSPB2 preconditioning could attenuate renal oxidative stress injury and renal tubular epithelial cell apoptosis by up-regulating expressions of Nrf-2 and HO-1 and down-regulating the expression of cleaved-caspase-3, but the protective effect could be reversed by brusatol.