Effect of ischemia preconditioning on renal ischemia/reperfusion injury in rats

Determination of Maximum Tolerable Cold Ischemia Time in a Mouse Model of Cervical Heterotopic Uterus Transplantation

BACKGROUND

Uterus transplantation (UTx) is an emerging treatment for uterine factor infertility. Determining the maximum tolerable cold ischemia time is crucial for successful UTx. However, the limit for cold ischemia in the uterus is unclear. This study aimed to examine cold ischemia's effects on mouse uteri and identify the maximum cold ischemia duration that uteri can endure.

METHODS

We systematically assessed the tolerance of mouse uteri to extended cold ischemia, 24 h, 36 h, and 48 h, using the cervical heterotopic UTx model. Multiple indicators were used to evaluate ischemia-reperfusion injury, including reperfusion duration, macroscopic examination, oxidative stress, inflammation, and histopathology. The function of transplants was evaluated through estrous cycle monitoring and embryo transfer.

RESULTS

Mouse uteri subjected to 48 h of cold ischemia exhibited significant delays and insufficiencies in reperfusion, substantial tissue necrosis, and loss of the estrous cycle. Conversely, uteri that underwent cold ischemia within 36 h showed long survival, regular estrous cycles, and fertility.

CONCLUSIONS

Our study demonstrated that mouse uteri can endure at least 36 h of cold ischemia, extending the known limits for cold ischemia and providing a pivotal reference for research on the prevention and treatment of cold ischemic injury in UTx.

The role of non-protein-coding RNAs in ischemic acute kidney injury

Acute kidney injury (AKI) is a condition characterized by a rapid decline in kidney function within a span of 48 hours. It is influenced by various factors including inflammation, oxidative stress, excessive calcium levels within cells, activation of the renin-angiotensin system, and dysfunction in microcirculation. Ischemia-reperfusion injury (IRI) is recognized as a major cause of AKI; however, the precise mechanisms behind this process are not yet fully understood and effective treatments are still needed. To enhance the accuracy of diagnosing AKI during its early stages, the utilization of innovative markers is crucial. Numerous studies suggest that certain noncoding RNAs (ncRNAs), such as long noncoding RNAs (lncRNAs), microRNAs (miRNAs), and circular RNAs (circRNAs), play a central role in regulating gene expression and protein synthesis. These ncRNAs are closely associated with the development and recovery of AKI and have been detected in both kidney tissue and bodily fluids. Furthermore, specific ncRNAs may serve as diagnostic markers and potential targets for therapeutic interventions in AKI. This review aims to summarize the functional roles and changes observed in noncoding RNAs during ischemic AKI, as well as explore their therapeutic potential.

Aloperine: A Potent Modulator of Crucial Biological Mechanisms in Multiple Diseases

Aloperine is an alkaloid found in the seeds and leaves of the medicinal plant Sophora alopecuroides L. It has been used as herbal medicine in China for centuries due to its potent anti-inflammatory, antioxidant, antibacterial, and antiviral properties. Recently, aloperine has been widely investigated for its therapeutic activities. Aloperine is proven to be an effective therapeutic agent against many human pathological conditions, including cancer, viral diseases, and cardiovascular and inflammatory disorders. Aloperine is reported to exert therapeutic effects through triggering various biological processes, including cell cycle arrest, apoptosis, autophagy, suppressing cell migration, and invasion. It has also been found to be associated with the modulation of various signaling pathways in different diseases. In this review, we summarize the most recent knowledge on the modulatory effects of aloperine on various critical biological processes and signaling mechanisms, including the PI3K, Akt, NF-κB, Ras, and Nrf2 pathways. These data demonstrate that aloperine is a promising therapeutic candidate. Being a potent modulator of signaling mechanisms, aloperine can be employed in clinical settings to treat various human disorders in the future.

The creation of unilateral intermittent and unintermittent renal ischemia-reperfusion models in rats

Background and Aim:

This study aims to establish unilateral intermittent and unintermittent partial nephrectomy-like renal ischemia-reperfusion (I-R) model in rats and to compare the results with biochemical findings.

Material and Methods:

The study was conducted on 24 adult 8-week-old male Wistar-Albino rats, each weighing s200–250 g. The rats were divided into three groups. In the Sham group (n = 8), the kidney was surgically exposed and closed. We designed experimental I-R models in the second group (n = 8, a total of 30-min ischemia model in the manner of 3 intermittent sets 8 minutes clamping and 2 min unclamping) and in the third group (n = 8, one session of 30-min unintermittent ischemia). In postoperative day 1, the rats were sacrificed, and the effects of I-R models on the renal tissue were comparatively assessed by evaluating serum Neutrophil Gelatinase-Associated Lipocalin (NGAL), serum kidney injury molecule-1 (KIM-1), urinary NGAL, urinary KIM-1, and serum creatinine levels.

Results:

Urinary NGAL and KIM-1 levels were significantly higher in the continuous ischemia group when compared to those in the sham and intermittent ischemia groups (P < 0.05). In the intermittent ischemia group, urinary NGAL and urinary KIM-1 levels were significantly higher than those in the sham group (P < 0.05). Although the results of serum NGAL, serum KIM-1, and serum creatinine levels seemed to be in parallel to the results of urinary markers, no statistically significant difference was found.

Conclusion:

Renal injury was significantly less in the intermittent I-R model when compared to that in the unintermittent I-R model in our experimental rat study.

Study of the Role of the Tyrosine Kinase Receptor MerTK in the Development of Kidney Ischemia-Reperfusion Injury in RCS Rats

Renal ischaemia reperfusion (I/R) triggers a cascade of events including oxidative stress, apoptotic body and microparticle (MP) formation as well as an acute inflammatory process that may contribute to organ failure. Macrophages are recruited to phagocytose cell debris and MPs. The tyrosine kinase receptor MerTK is a major player in the phagocytosis process. Experimental models of renal I/R events are of major importance for identifying I/R key players and for elaborating novel therapeutical approaches. A major aim of our study was to investigate possible involvement of MerTK in renal I/R. We performed our study on both natural mutant rats for MerTK (referred to as RCS) and on wild type rats referred to as WT. I/R was established by of bilateral clamping of the renal pedicles for 30' followed by three days of reperfusion. Plasma samples were analysed for creatinine, aspartate aminotransferase (ASAT), lactate dehydrogenase (LDH), kidney injury molecule -1 (KIM-1), and neutrophil gelatinase-associated lipocalin (NGAL) levels and for MPs. Kidney tissue damage and CD68-positive cell requirement were analysed by histochemistry. monocyte chemoattractant protein-1 (MCP-1), myeloperoxidase (MPO), inducible nitric oxide synthase (iNOS), and histone 3A (H3A) levels in kidney tissue lysates were analysed by western blotting. The phagocytic activity of blood-isolated monocytes collected from RCS or WT towards annexin-V positive bodies derived from cultured renal cell was assessed by fluorescence-activated single cell sorting (FACS) and confocal microscopy analyses. The renal I/R model for RCS rat described for the first time here paves the way for further investigations of MerTK-dependent events in renal tissue injury and repair mechanisms.

ZNF667 attenuates leukocyte-endothelial adhesion via downregulation of P-selectin in skin flap following remote limb ischemic preconditioning

We assessed the effects and potential mechanism of romote ischemic preconditioning (RIPC) on leukocytes-endothelium cell adhesion in the flap microvessel after ischemia-reperfusion (I/R) injury. Eight hours after reperfusion, edema and intravascular leukocyte aggregation were reduced and microvessels were more obvious in the group with superficial inferior epigastric artery (SIEA) perforator flap (SIEA-flap) subjected to RIPC than in the I/R group. Zinc finger protein 667 (ZNF667) was significantly increased but P-selectin was decreased in the flaps subjected to RIPC, compared to those in the I/R group. The low expression of P-selectin was associated with ZNF667 expression and activation in human dermal microvascular endothelial cells in response to hypoxic preconditioning. ZNF667 bound to the P-selectin promoter region, suppressing its transcription through a special core sequence. The ablation of P-selectin by small interfering RNA effectively prevented the leukocytes-endothelium cell adhesion effect of ZNF667-knockdown. ZNF667 upregulation attenuates leukocyte-endothelial cell adhesion by negatively regulating the expression of P-selectin in SIEA-flap subjected to RIPC.

Cho W, Martins N. Therapeutic Potential of Rosmarinic Acid: A Comprehensive Review

Naturally occurring food-derived active ingredients have received huge attention for their chemopreventive and chemotherapy capabilities in several diseases. Rosmarinic acid (RA) is a caffeic acid ester and a naturally-occurring phenolic compound in a number of plants belonging to the Lamiaceae family, such as Rosmarinus officinalis (rosemary) from which it was formerly isolated. RA intervenes in carcinogenesis through different ways, including in tumor cell proliferation, apoptosis, metastasis, and inflammation. On the other hand, it also exerts powerful antimicrobial, anti-inflammatory, antioxidant and even antidepressant, anti-aging effects. The present review aims to provide an overview on anticancer activities of RA and to deliberate its therapeutic potential against a wide variety of diseases. Given the current evidence, RA may be considered as part of the daily diet in the treatment of several diseases, with pre-determined doses avoiding cytotoxicity.

Hepatorenal protection during renal ischemia by quercetin and remote ischemic perconditioning

BACKGROUND

Pathogenesis of renal ischemia/reperfusion injury (IRI) involves oxidative stress response in the kidney and remote organs. Both quercetin and remote ischemic perconditioning (RIPerC) can protect partially against IRI. This study determined whether combined quercetin and RIPerC could provide an augmented hepatorenal protection against renal IRI.

MATERIALS AND METHODS

I/R was induced by clamping renal arteries for 45 min followed by 24-h reperfusion. RIPerC consisted of four cycles of 2 min of left femoral artery ischemia followed by 3 min of reperfusion administered at the beginning of renal ischemia. Rats were divided into five groups: sham, I/R, RIPerC, quercetin (Q + I/R), and combined quercetin and RIPerC (Q + RIPerC). At the end of reperfusion period, blood, urine, and tissue samples were collected.

RESULTS

I/R caused kidney dysfunction, as proved by significant decrease in creatinine clearance, and a significant increase in liver functional indicators as evidenced by increased plasma alanine aminotransferase and aspartate aminotransferase activity. This was accompanied by a decrease of glutathione peroxidase and catalase activities with an increase of malondialdehyde levels and histological damages in renal and hepatic tissues. Treatment with RIPerC and quercetin reduced all these changes. However, the measure of improvements was enhanced by combined quercetin and RIPerC treatment.

CONCLUSIONS

This study demonstrated protective effects of quercetin and RIPerC strategy on the both kidney and liver after renal I/R. The results suggest that combined quercetin and RIPerC provides an enhanced protection against renal IRI by reduction of lipid peroxidation and augmentation of antioxidant systems.

Conjugated linoleic acid rat pretreatment reduces renal damage in ischemia/reperfusion injury: Unraveling antiapoptotic mechanisms and regulation of phosphorylated mammalian target of rapamycin

SCOPE

Conjugated linoleic acids (CLAs) are dietary components with beneficial effects on human health. The aim of this study was to evaluate the potential benefits of CLA pretreatment in a rat model of renal ischemia/reperfusion injury (IRI).

METHODS AND RESULTS

Animals were treated with CLAs (200 mg/kg/day) or water for two weeks prior to sham surgery or to surgery to induce IRI. Renal function, oxidative stress, apoptosis, and cell proliferation markers, were evaluated. Moreover, kidney sections were submitted to histological evaluation. IRI induced increased serum creatinine, blood urea nitrogen, fractional sodium excretion, malondialdehyde, Bax, and phosphorylated mammalian target of rapamycin (P-mTOR), and decreased clearance of creatine, superoxide dismutase and catalase activities, and Bax in comparison with control groups. CLA prefeeding restored, at least in part, the above reported markers to normal levels, increased the anti-apoptotic protein, B-cell lymphoma 2 (Bcl-2), and reduce the histological damage.

CONCLUSION

The results suggest that the decreased renal tissue damage and improved renal function and oxidative stress, in rats pretreated with CLAs before renal IRI induction, could be associated with downregulation of Bax and P-mTOR, and upregulation of Bcl-2. CLAs pretreatment resulted to protect against IRI through the regulation of signaling pathways involved in apoptosis.

Aloperine Protects Mice against Ischemia-Reperfusion (IR)-Induced Renal Injury by Regulating PI3K/AKT/mTOR Signaling and AP-1 Activity

Aloperine is a quinolizidine alkaloid extracted from the leaves of Sophora plants. It has been recognized with the potential to treat inflammatory and allergic diseases as well as tumors. In this report, we demonstrate that pretreatment with aloperine provided protection for mice against ischemia-reperfusion (IR)-induced acute renal injury as manifested by the attenuated inflammatory infiltration, reduced tubular apoptosis, and well-preserved renal function. Mechanistic studies revealed that aloperine selectively repressed IL-1β and IFN-γ expression by regulating PI3K/Akt/mTOR signaling and NF-κB transcriptional activity. However, aloperine did not show a perceptible impact on IL-6 and TGF-β expression and the related Jak2/Stat3 signaling. It was also noted that aloperine regulates AP-1 activity, through which it not only enhances SOD expression to increase reactive oxygen species (ROS) detoxification but also promotes the expression of antiapoptotic Bcl-2, thereby preventing tubular cells from IR-induced apoptosis. Collectively, our data suggest that administration of aloperine prior to IR insults, such as renal transplantation, could be a viable approach to prevent IR-induced injuries.

Molecular Mechanisms of Renal Ischemic Conditioning Strategies

Ischemia-reperfusion injury is the leading cause of acute kidney injury in a variety of clinical settings such as renal transplantation and hypovolemic and/or septic shock. Strategies to reduce ischemia-reperfusion injury are obviously clinically relevant. Ischemic conditioning is an inherent part of the renal defense mechanism against ischemia and can be triggered by short periods of intermittent ischemia and reperfusion. Understanding the signaling transduction pathways of renal ischemic conditioning can promote further clinical translation and pharmacological advancements in this era. This review summarizes research on the molecular mechanisms underlying both local and remote ischemic pre-, per- and postconditioning of the kidney. The different types of conditioning strategies in the kidney recruit similar powerful pro-survival mechanisms. Likewise, renal ischemic conditioning mobilizes many of the same protective signaling pathways as in other organs, but differences are recognized.

Renal ischemia/reperfusion injury; from pathophysiology to treatment

Ischemia/reperfusion injury (IRI) is caused by a sudden temporary impairment of the blood flow to the particular organ. IRI usually is associated with a robust inflammatory and oxidative stress response to hypoxia and reperfusion which disturbs the organ function. Renal IR induced acute kidney injury (AKI) contributes to high morbidity and mortality rate in a wide range of injuries. Although the pathophysiology of IRI is not completely understood, several important mechanisms resulting in kidney failure have been mentioned. In ischemic kidney and subsequent of re-oxygenation, generation of reactive oxygen species (ROS) at reperfusion phase initiates a cascade of deleterious cellular responses leading to inflammation, cell death, and acute kidney failure. Better understanding of the cellular pathophysiological mechanisms underlying kidney injury will hopefully result in the design of more targeted therapies to prevent and treatment the injury. In this review, we summarize some important potential mechanisms and therapeutic approaches in renal IRI.

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.