Molecular Mechanisms and Pathophysiology of Ischemia-Reperfusion Injury

A novel framework for uncovering the coordinative spectrum-effect correlation of the effective components of Yangyin Tongnao Granules on cerebral ischemia-reperfusion injury in rats

ETHNOPHARMACOLOGICAL RELEVANCE

Ischemic stroke is currently a major public health hazard.Yangyin Tongnao Granules (YYTN), a traditional Chinese medicinal prescription, exerts potential therapeutic effects on subsequent cerebral ischemia-reperfusion injury (CIRI) after ischemic stroke. However, further studies are required to comprehend the underlying mechanism of YYTN for treating CIRI and the associated spectrum-effect mechanisms.

AIM OF THE STUDY

To investigate the coordinated correlation between the fingerprint and the pharmacodynamic indexes of the effective components (total flavonoids, total saponins, total alkaloids, and total phenolic acids) in YYTN for treating CIRI in rats.

METHODS

The fingerprints of five specific components (ligustrazine, puerarin, ferulic acid, calycosin, and formononetin) of YYTN in rats with middle cerebral artery occlusion (MCAO) were established using high-performance liquid chromatography (HPLC), and their peak areas were quantified in plasma samples. The pharmacodynamic indexes of tumor necrosis factor-alpha (TNF-α), cytochrome c (Cyt-C), and total superoxide dismutase (T-SOD) were integrated using the Criteria Importance Through Intercriteria Correlation (CRITIC) method to create a comprehensive evaluation index. Spectrum-effect correlation was analyzed by performing gray relation analysis (GRA), correlation analysis (CA), and partial least squares regression (PLSR). The Borda method was then applied to integrate the obtained results.

RESULTS

In MCAO rats, the effective components of YYTN reduced TNF-α and Cyt-C and increased T-SOD, which indicates their anti-inflammatory, antiapoptotic, and antioxidant effects. Spectrum-effect CA revealed certain associations between the chromatographic peaks of the five main components and the comprehensive pharmacodynamic evaluation index. Of these components, formononetin displayed the highest correlation, whereas ferulic acid exhibited the lowest correlation. All components showed a positive correlation. Using the Borda method, the components were ranked as follows based on correlation: formononetin > calycosin > ligustrazine > puerarin > ferulic acid.

CONCLUSIONS

The effective components of YYTN exhibited synergistic effects in the treatment of MCAO rats, which could potentially be attributed to their multitarget and multipathway mechanisms. The Borda method-based spectrum-effect correlation analysis provides a coordinated approach to investigate the relationship between fingerprint and pharmacodynamics of traditional Chinese medicine (TCM).

Neuroprotective effect of autologous mitochondrial transplantation against global ischemia/reperfusion injury in a rat model of cardiac arrest

BACKGROUND

Mitochondria have emerged as a promising target for ischemic disease. A previous study reported the application of mitochondrial transplantation in focal cerebral ischemia/reperfusion injury, but it is unclear whether exogenous mitochondrial transplantation could be a therapeutic strategy for global ischemia/reperfusion injury induced by cardiac arrest.

METHODS

We hypothesized that transplantation of autologous mitochondria would rescue hippocampal cells and alleviate neurological impairment after cardiac arrest. In this study, we employed a rat cardiac arrest-global cerebral ischemia injury model (CA-GCII) and transplanted isolated mitochondria intravenously. Behavior test was applied to assess neurological deficit. Apoptosis and mitochondria permeability transition pore opening in hippocampus was determined using immunoblotting and swelling assay, respectively.

RESULTS

Transplanted mitochondria distributed throughout hippocampal cells and reduced oxidative stress. An improved neurological outcome was observed in rats receiving autologous mitochondria. In the hippocampus, mitophagy was enhanced while cell apoptosis was induced by ischemia/reperfusion insult was downregulated by mitochondrial transplantation. Mitochondrial permeability transition pore (MPTP) opening in surviving hippocampal cells was also suppressed.

CONCLUSIONS

These results indicated that transplantation of autologous mitochondria rescued hippocampal cells from ischemia/reperfusion injury and ameliorated neurological impairment caused by cardiac arrest.

E-cadherin and NF-κB expression in the vagina after ovarian ischemia and reperfusion

PURPOSE

To investigate inflammation and cell adhesion molecules in the vagina after ovarian ischemia-reperfusion (IR) injury.

METHODS

20 Wistar albino female rats were divided into two groups: control, and IR groups. In IR group, blood flow was restricted for 2 hours for ovarian ischemia. Then, tissues were re-blood 2 hours for reperfusion. Vagina tissues were excised and processed for histopathological analysis. Histopathological and biochemical follow-ups were performed.

RESULTS

Both malondialdehyde and myeloperoxidase values were increased in IR group compared to control group. Glutathione content was decreased in IR group compared to control group. Epithelial degeneration, inflammation, dilatation, and nuclear factor-κB (NF-κB) expression were increased in IR group compared to control group. E-cadherin expression was significantly decreased in IR group. In the IR group, E-cadherin showed a positive reaction in adenomas, gland-like cryptic structures, cellular junctions with clustered inflammatory cells. In the IR group, NF-κB expression was increased in basement membrane, inflammatory cells, in blood vessels.

CONCLUSIONS

Ovarian ischemia caused degeneration of epithelial cells in the vaginal region and disruptions in the cell junction complex, which leads to activation of E-cadherin and NF-κB signaling pathway and alterations in reproductive and embryonal development in the vaginal region.

Recombinant Adenovirus-Mediated HIF-lα Ameliorates Neurological Dysfunction by Improving Energy Metabolism in Ischemic Penumbra After Cerebral Ischemia-Reperfusion in Rats

Background

Hypoxia inducible factor-1α (HIF-1α) regulates glucose metabolism during ischemia. This study investigated the effect of recombinant adenovirus HIF-1ɑ on neurological function and energy metabolism in a rat cerebral ischemia-reperfusion model.

Methods

Rats were divided into four groups: sham-operated (Sham) group, cerebral ischemia-reperfusion (CIR) group, recombinant adenovirus empty vector (Ad) group, and recombinant adenovirus-mediated HIF-1α (AdHIF-1α) group. The AdHIF-1α group and the Ad group were injected with AdHIF-1α and Ad in the lateral ventricle. The mNSS was performed at post-ischemia day 0 (P0) and P1, P14 and P28. At P14, the cerebral infarct volume was compared. At P28, HE staining, Nissl stains and TUNEL staining were performed. The expression of HIF-1α, GLUT1 and PFKFB3 were evaluated by Western Blot and immunohistochemistry. High performance liquid chromatography (HPLC) was used to determine the expression of GLUT1 and PFKFB3, and the level of energy metabolites: ATP, ADP and AMP.

Results

mNSS scores in the AdHIF-1α group were consistently lower than those in the CIR and Ad groups from P14 (P < 0.05) and Ad groups (P < 0.05). The cerebral infarct volume was reduced in the AdHIF-1α group compared with that in CIR group and Ad group (P < 0.05). At P28, HE showed better pathological changes in AdHIF-1α group. The number of Nissl bodies was increased in the AdHIF-1α group compared with the CIR and Ad groups (P < 0.05). The number of apoptotic cells in the AdHIF-1α group was fewer than that in the CIR and Ad groups (P < 0.05). The expression of HIF-1α, GLUT1 and PFKFB3 was significantly higher in the AdHIF-1α group compared with the CIR and Ad groups (P < 0.05). The ATP, ADP and AMP in the ischemic penumbra were also higher in the AdHIF-1α group (P < 0.05).

Conclusion

HIF-lα promoted neurological function recovery and decreased cerebral infarct volume in rats after cerebral ischemia-reperfusion injury by improving energy metabolism.

A Proof-of-Concept Preclinical Study Using a Novel Thermal Insulation Device in a Porcine Kidney Auto-Transplantation Model

Ischemia-reperfusion injury remains a fundamental problem during organ transplantation logistics. One key technical factor is the rapid allograft rewarming during the time of vascular reconstruction in the recipient. In this pilot study, a new thermal insulation bag (TIB) for organ transplantation was used. Insulation capacity, tissue compatibility, and usability were tested initially ex vivo on porcine kidneys (n = 24) followed by the first in vivo usage. Fourteen female German landrace pigs underwent kidney auto-transplantation after 24 h cold storage (4 °C). During the implantation process the kidney was either insulated with the new TIB, or it was not thermo-protected at all, which represents the clinical standard. In this proof-of-concept study, the usability (knife-to-skin-time) and the general thermal capacity (30 min warm storage at 38 °C ex vivo p < 0.001) was shown. The clinical outcome showed significant differences in the determination of CRP and pi-GST levels. Syndecan-1 Antibody staining showed clear significant higher counts in the control group (p < 0.01) indicating epithelial damage. However, the effect on renal outcomes in not severely pre-damaged kidneys does not appear to be conclusively significant. A close follow-up study is warranted, especially in the context of marginal organs or in cases where anastomosis-times are prolonged due to surgical complexity (e.g., multiple vessels and complex reconstructions).

Biomolecular Pathways of Cryoinjuries in Low-Temperature Storage for Mammalian Specimens

Low-temperature preservation could effectively extend in vitro storage of biological materials due to delayed or suspended cellular metabolism and decaying as illustrated by the Arrhenius model. It is widely used as an enabling technology for a variety of biomedical applications such as cell therapeutics, assisted reproductive technologies, organ transplantation, and mRNA medicine. Although the technology to minimize cryoinjuries of mammalian specimens during preservation has been advanced substantially over past decades, mammalian specimens still suffer cryoinjuries under low-temperature conditions. Particularly, the molecular mechanisms underlying cryoinjuries are still evasive, hindering further improvement and development of preservation technologies. In this paper, we systematically recapitulate the molecular cascades of cellular injuries induced by cryopreservation, including apoptosis, necroptosis, ischemia-reperfusion injury (IRI). Therefore, this study not only summarizes the impact of low-temperature preservations on preserved cells and organs on the molecular level, but also provides a molecular basis to reduce cryoinjuries for future exploration of biopreservation methods, materials, and devices.

The Development of Novel Drug Treatments for Stroke Patients: A Review

Acute ischemic stroke is a critical condition that can result in disability and death. The consequences of this medical condition depend on various factors, including the size of the stroke, affected brain region, treatment onset, and the type of treatment. The primary objective of stroke treatment is to restart ischemic penumbra tissue perfusion and reduce infarct volume by sustaining blood flow. Recent research on the condition's pathological pathways and processes has significantly improved treatment options beyond restoring perfusion. Many studies have concentrated on limiting injury severity via the manipulation of molecular mechanisms of ischemia, particularly in animal research. This article reviews completed and ongoing research on the development of acute ischemic stroke drugs. This study focuses on three main categories of antithrombotic drugs, thrombolytic drugs, and neuroprotective agents. The paper outlines findings from animal and clinical trials and explores the working mechanisms of these drugs.

Protective Effect of Adipose-Derived Mesenchymal Stem Cell Secretome against Hepatocyte Apoptosis Induced by Liver Ischemia-Reperfusion with Partial Hepatectomy Injury

Ischemia-reperfusion injury (IRI) is an inevitable complication of liver surgery and liver transplantation. Hepatocyte apoptosis plays a significant role in the pathological process of hepatic IRI. Adipose-derived stem cells (ADSCs) are known to repair and regenerate damaged tissues by producing bioactive factors, including cytokines, exosomes, and extracellular matrix components, which collectively form the secretome of these cells. The aim of this study was to assess the protective effects of the ADSCs secretome after liver ischemia-reperfusion combined with partial hepatectomy in miniature pigs. We successfully established laparoscopic liver ischemia-reperfusion with partial hepatectomy in miniature pigs and injected saline, DMEM, ADSC-secretome, and ADSCs directly into the liver parenchyma immediately afterwards. Both ADSCs and the ADSC-secretome improved the IR-induced ultrastructural changes in hepatocytes and significantly decreased the proportion of TUNEL-positive apoptotic cells along with caspase activity. Consistent with this, P53, Bax, Fas, and Fasl mRNA and protein levels were markedly decreased, while Bcl-2 was significantly increased in the animals treated with ADSCs and ADSC-secretome. Our findings indicate that ADSCs exert therapeutic effects in a paracrine manner through their secretome, which can be a viable alternative to cell-based regenerative therapies.

Assessment of Oxidative Stress Markers in Hypothermic Preservation of Transplanted Kidneys

Ischemia-reperfusion injury (IRI) after renal transplantation is a complex biochemical process. The first component is an ischemic phase during kidney storage. The second is reperfusion, the main source of oxidative stress. This study aimed to analyze the activity of enzymes and concentrations of non-enzymatic compounds involved in the antioxidant defense mechanisms: glutathione (GSH), glutathione peroxidase (GPX), catalase (CAT), superoxide dismutase (SOD), glutathione reductase (GR), glutathione transferase (GST), thiobarbituric acid reactive substances (TBARS), malondialdehyde (MDA), measured in preservation fluid before transplantation of human kidneys (KTx) grafted from brain dead donors. The study group (N = 66) was divided according to the method of kidney storage: Group 1—hypothermic machine perfusion (HMP) in LifePort perfusion pump, n1 = 26, and Group 2—static cold storage (SCS), n2 = 40. The measurements of kidney function parameters, blood count, and adverse events were performed at constant time points during 7-day hospitalization and 3-month follow-up. Kidney perfusate in Group 2 was characterized by significantly more acidic pH (p < 0.0001), higher activity of GPX [U/mgHb] (p < 0.05) and higher concentration of MDA [μmol/L] (p < 0.05). There was a statistically significant improvement of kidney function and specific blood count alterations concerning storage method in repeated measures. There were aggregations of significant correlations (p < 0.05) between kidney function parameters after KTx and oxidative stress markers: diuresis & CAT, Na⁺ & CAT, K⁺ & GPX, urea & GR. There were aggregations of significant correlations (p < 0.05) between recipient blood count and oxidative stress markers: CAT & MON, SOD & WBC, SOD & MON. Study groups demonstrated differences concerning the method of kidney storage. A significant role of recipient’s gender, gender matching, preservation solution, and perfusate pH was not confirmed, however, basing on analyzed data, the well-established long-term beneficial impact of HMP on the outcome of transplanted kidneys might partially depend on the intensity of IRI ischemic phase and oxidative stress, reflected by the examined biomarkers.

Biomarkers and Mechanisms of Oxidative Stress-Last 20 Years of Research with an Emphasis on Kidney Damage and Renal Transplantation

Oxidative stress is an imbalance between pro- and antioxidants that adversely influences the organism in various mechanisms and on many levels. Oxidative damage occurring concomitantly in many cellular structures may cause a deterioration of function, including apoptosis and necrosis. The damage leaves a molecular “footprint”, which can be detected by specific methodology, using certain oxidative stress biomarkers. There is an intimate relationship between oxidative stress, inflammation, and functional impairment, resulting in various diseases affecting the entire human body. In the current narrative review, we strengthen the connection between oxidative stress mechanisms and their active compounds, emphasizing kidney damage and renal transplantation. An analysis of reactive oxygen species (ROS), antioxidants, products of peroxidation, and finally signaling pathways gives a lot of promising data that potentially will modify cell responses on many levels, including gene expression. Oxidative damage, stress, and ROS are still intensively exploited research subjects. We discuss compounds mentioned earlier as biomarkers of oxidative stress and present their role documented during the last 20 years of research. The following keywords and MeSH terms were used in the search: oxidative stress, kidney, transplantation, ischemia-reperfusion injury, IRI, biomarkers, peroxidation, and treatment.

The Role of Endothelins, IL-18, and NGAL in Kidney Hypothermic Machine Perfusion

Ischemia-reperfusion injury (IRI) occurring after renal transplantation is a complex biochemical process that can be monitored by specific biomarkers. The roles of those are not yet fully elucidated. The aim of this study was to analyze the concentrations of endothelins (ET-1, ET-2, and ET-3), interleukin-18 (IL-18), and neutrophil gelatinase-associated lipocalin (NGAL) during the reperfusion of human kidneys grafted from brain dead donors and later transplanted. The study group (n = 44) was analyzed according to the method of kidney storage: Group 1 underwent hypothermic machine perfusion (HMP) in the LifePort perfusion pump (n = 22), and Group 2 underwent static cold storage (SCS) (n = 22). The analysis of kidney function was performed daily during the first seven days after transplantation. The kidneys in Group 1 were characterized by higher absolute concentrations of ET-1, IL-18, and NGAL, as well as a lower concentration of ET-2 (p = 0.017) and ET-3. The relative increase of ET-1 (p = 0.033), ET-2, and ET-3 during reperfusion was lower in this group, while the relative decrease of NGAL was higher. Group 1 was also characterized by significant decrease of IL-18 (p = 0.026) and a tendency for better kidney function based on the higher total diuresis, higher glomerular filtration rate (GFR), higher potassium level, lower serum creatinine, and lower urea concentration during the seven-day postoperative observation period. The long-term beneficial impact of hypothermic machine perfusion on the outcome of transplanted kidneys may rely on the early modified proceedings and intensity of ischemia-reperfusion injury reflected by the dynamics of the concentrations of examined biomarkers.

Dual and Opposite Costimulatory Targeting with a Novel Human Fusion Recombinant Protein Effectively Prevents Renal Warm Ischemia Reperfusion Injury and Allograft Rejection in Murine Models

Many studies have shown both the CD28-D80/86 costimulatory pathway and the PD-1-PD-L1/L2 coinhibitory pathway to be important signals in modulating or decreasing the inflammatory profile in ischemia-reperfusion injury (IRI) or in a solid organ transplant setting. The importance of these two opposing pathways and their potential synergistic effect led our group to design a human fusion recombinant protein with CTLA4 and PD-L2 domains named HYBRI. The objective of our study was to determine the HYBRI binding to the postulated ligands of CTLA4 (CD80) and PD-L2 (PD-1) using the Surface Plasmon Resonance technique and to evaluate the in vivo HYBRI effects on two representative kidney inflammatory models-rat renal IRI and allogeneic kidney transplant. The Surface Plasmon Resonance assay demonstrated the avidity and binding of HYBRI to its targets. HYBRI treatment in the models exerted a high functional and morphological improvement. HYBRI produced a significant amelioration of renal function on day one and two after bilateral warm ischemia and on days seven and nine after transplant, clearly prolonging the animal survival in a life-sustaining renal allograft model. In both models, a significant reduction in histological damage and CD3 and CD68 infiltrating cells was observed. HYBRI decreased the circulating inflammatory cytokines and enriched the FoxP3 peripheral circulating, apart from reducing renal inflammation. In conclusion, the dual and opposite costimulatory targeting with that novel protein offers a good microenvironment profile to protect the ischemic process in the kidney and to prevent the kidney rejection, increasing the animal's chances of survival. HYBRI largely prevents the progression of inflammation in these rat models.

Proxeed plus salvage rat testis from ischemia- reperfused injury by enhancing antioxidant's activities and inhibition of iNOS expression

Testicular torsion is an acute urological emergency condition that occurs due to obstruction of blood flow to the testicles which may result in ischemia and loss of testicular functions. This study examined the protective effects of Proxeed Plus (PP), a dietary supplement on testicular ischemia/reperfusion (I/R) injured rats using oxidative stress markers, hormonal levels, apoptotic parameters, histological and immunohistochemistry analysis at 4 h and after 7 days of reperfusion. The protective treatment of the I/R injured rats with PP at 1000 and 5000 mg/kg body weight (bw) resulted in significant increases in the serum and tissue antioxidative defense capacities (superoxide dismutase, reduced glutathione, catalase, glutathione-s-transferase, and glutathione peroxidase), sex hormones (luteinizing hormone, follicle-stimulating hormone, and testosterone), also reduce pro-oxidative markers (malondialdehyde and hydrogen peroxide), serum iNOS and apoptotic parameters (Caspase -3 and Caspase -9) in comparison to the results detected in the I/R untreated rats. It was also observed that PP ameliorated histological changes of I/R injured rats; increased spermatogenetic activity, seminiferous tubular diameter, Leydig cell mass, and reduced expressions of testicular inducible nitric oxide synthase (iNOS). Therefore, the therapeutic use of Proxeed Plus could be considered a promising approach in averting testicular damage against I/R injury.

Extracellular vesicles for treatment of solid organ ischemia-reperfusion injury

As the incidence of ischemia-reperfusion (I-R) injury has substantially increased, there is a pressing need to develop effective strategies to treat this global health issue. I-R injury can affect all organs and is associated with high morbidity and mortality rates. Pathological settings such as myocardial infarction, stroke, hemorrhagic shock, and solid organ transplant are particularly prone to cause I-R injury. Ischemia (hypoxia) and/or reperfusion (reoxygenation) induces various forms of cellular and structural damage. A major cause of damage is local inflammatory responses, which may spread to produce more advanced systemic inflammation. Management of I-R injury relies primarily on supportive measures, as specific treatment strategies are lacking. Extracellular vesicles (EVs) are cell-secreted nano-scale structures containing various biomolecules involved in cell communication and multiple physiological processes. EVs derived from certain cell types have been shown to exhibit anti-inflammatory, antioxidant, and angiogenic properties. This review provides an overview of EV-based therapeutics for I-R injury in kidneys, liver, heart, lungs, and brain. Additionally, the mechanisms by which EVs protect against I-R injury are discussed. Promising preclinical findings highlight the potential clinical use of EVs for I-R injury.