Clopidogrel protects from cell apoptosis and oxidative damage in a mouse model of renal ischaemia-reperfusion injury

Mortality Risk Analysis of Combination Antiplatelet Therapy in Patients with Ischemic Stroke and Acute Kidney Injury: A Retrospective Cohort Analysis of the MIMIC-IV Database

BACKGROUND

Ischemic stroke (IS), a major cerebrovascular disease, is associated with high disability and mortality rates. Acute kidney injury (AKI) often complicates IS and increases in-hospital mortality. While antiplatelet agents are commonly used for IS treatment, their effectiveness in IS patients with AKI is unclear.

METHODS

This study, using data from the MIMIC-IV database, divided patients into non-combination (clopidogrel or ticagrelor alone) and combination (with aspirin) groups. The primary outcome was 28-day mortality, with secondary outcomes including 90-day, 1-year, and in-hospital mortality. Multivariable Cox and logistic regression models were used to analyze the relationship between antiplatelet regimens and mortality. Subgroup analyses and interaction tests were conducted.

RESULTS

Results showed the combination group had lower 28-day, 90-day, 1-year, and in-hospital mortality risks than the non-combination group (all p < 0.001). Subgroup analysis revealed an interaction effect by AKI stage, with combination therapy not significantly reducing mortality in severe AKI (stages 2 and 3, p = 0.743, p = 0.244).

CONCLUSIONS

This study demonstrates that combination antiplatelet therapy significantly reduces 28-day, 90-day, 1-year, and in-hospital mortality risks of IS patients with AKI, suggesting its potential benefits in improving both short- and long-term clinical outcomes. However, this does not apply to patients with severe AKI, indicating heterogeneous survival benefits of combination therapy across AKI severity. Clinical decision-making should incorporate AKI stage stratification to evaluate the applicability of combination antiplatelet therapy. Further research is needed to explore the impact of AKI staging on antiplatelet therapy in IS patients.

Platelet glycoprotein VI promotes folic acid-induced acute kidney injury through interaction with tubular epithelial cell-derived galectin-3

BACKGROUND

Acute kidney injury (AKI) is defined by a significant reduction in renal function, which subsequently impairs coagulation and activates the inflammatory immune response, ultimately resulting in damage to renal tubular epithelial cells (TECs). Platelets are crucial in mediating both inflammatory and coagulation processes. While it is established that platelet activation contributes to the progression of AKI, the precise mechanisms underlying this relationship remain largely unclear.

METHODS

We investigated platelet function in folic acid-induced acute kidney injury (FA-AKI) and examined the effects of galectin-3, a protein derived from renal tubular epithelial cells (TECs), on its interaction with platelet glycoprotein VI (GPVI). This interaction was assessed through the analysis of monocyte migration, macrophage polarization, and the generation of monocyte-platelet aggregation. Additionally, we utilized platelet GPVI-specific knockout mice in conjunction with TD139, a small-molecule inhibitor of galectin-3, to explore the effects of inhibiting the galectin-3-GPVI interaction on FA-AKI.

RESULTS

In the current study, we observed that mouse platelets displayed hyperactivity in the context of functional acute kidney injury (FA-AKI). This hyperactivity was linked to the interaction between galectin-3, which is derived from damaged renal tubular epithelial cells (TECs), and the glycoprotein VI (GPVI) on platelets. Our findings indicated a heightened interaction between activated platelets and monocytes, along with an increase in monocyte-platelet aggregation (MPA) within the circulation. The increased infiltration of monocytes and platelets in renal tissue was further validated through CD41 and CD68 immunofluorescence techniques. Additionally, the interaction between galectin-3 and platelet GPVI was shown to facilitate monocyte migration, promote M1-type macrophage polarization, and enhance phagocytic activity. The galectin-3 inhibitor TD139 significantly suppressed monocyte-platelet aggregation (MPA), reduced inflammatory responses, and extended the survival of mice with acute kidney injury (AKI).

CONCLUSIONS

These findings suggest that galectin-3, which is released from damaged cells during acute kidney injury (AKI), exacerbates renal inflammation and tissue damage by activating platelets through glycoprotein VI (GPVI). This activation enhances interactions between monocytes and platelets, ultimately leading to the formation of monocyte-platelet aggregates (MPA) and the polarization of M1 macrophages.

Clopidogrel protects against gentamicin-induced nephrotoxicity through targeting oxidative stress, apoptosis, and coagulation pathways

Gentamicin (Genta)-induced nephrotoxicity poses a significant clinical challenge due to its detrimental effects on kidney function. Clopidogrel (Clop), an antiplatelet drug known for its ability to prevent blood clots by inhibiting platelet aggregation, also has potential effects on oxidative stress and cell death. This study investigates Clop's protective role against Genta-induced nephrotoxicity, emphasizing the importance of the coagulation cascade. The 32 adult male albino rats were randomly assigned to four groups of eight (n = 8). The first group received only the vehicle. Genta was injected intraperitoneally at 100 mg/kg/day for 8 days in the second group. Groups 3 and 4 received oral Clop at 10 and 20 mg/kg/day for 1 week before Genta delivery and throughout the experiment. Renal tissue showed renal function tests, oxidative stress, pro-inflammatory cytokines, apoptotic markers, coagulation profile, and fibrin expression. Clop improved Genta-induced kidney function and histopathology. Clop substantially reduced pro-inflammatory cytokines, oxidative stress indicators, pro-apoptotic proteins, and fibrin protein. Clop also significantly boosted renal tissue anti-inflammatory and anti-apoptotic protein expression. Genta-induced nephrotoxicity involves oxidative stress, apoptosis, and coagulation system activation, according to studies. This study underscores that Genta-induced nephrotoxicity is associated with oxidative stress, apoptosis, and activation of the coagulation system. Clop's protective effects on nephrons are attributed to its anticoagulant, antioxidant, anti-inflammatory, and anti-apoptotic properties, presenting it as a promising therapeutic strategy against Genta-induced kidney damage.

Single-Cell Spatial Transcriptomics Unveils Platelet-Fueled Cycling Macrophages for Kidney Fibrosis

With the increasing incidence of kidney diseases, there is an urgent need to develop therapeutic strategies to combat post-injury fibrosis. Immune cells, including platelets, play a pivotal role in this repair process, primarily through their released cytokines. However, the specific role of platelets in kidney injury and subsequent repair remains underexplored. Here, the detrimental role of platelets in renal recovery following ischemia/reperfusion injury and its contribution to acute kidney injury  to chronic kidney disease transition is aimed to investigated. In this study, it is shown that depleting platelets accelerates injury resolution and significantly reduces fibrosis. Employing advanced single-cell and spatial transcriptomic techniques, macrophages as the primary mediators modulated by platelet signals is identified. A novel subset of macrophages, termed "cycling M2", which exhibit an M2 phenotype combined with enhanced proliferative activity is uncovered. This subset emerges in the injured kidney during the resolution phase and is modulated by platelet-derived thrombospondin 1 (THBS1) signaling, acquiring profibrotic characteristics. Conversely, targeted inhibition of THBS1 markedly downregulates the cycling M2 macrophage, thereby mitigating fibrotic progression. Overall, this findings highlight the adverse role of platelet THBS1-boosted cycling M2 macrophages in renal injury repair and suggest platelet THBS1 as a promising therapeutic target for alleviating inflammation and kidney fibrosis.

Assessing the Impact of Morphine on Adverse Outcomes in ACS Patients Treated with P2Y12 Inhibitors: Insights from Multiple Real-World Evidence

Purpose

Mechanistic studies showed that morphine may impair the antiplatelet effect of P2Y12 inhibitors. However, Several clinical studies with cardiovascular events as an outcome are contradictory, and the broader impact of this drug interaction on additional organ systems remains uncertain. With multisource data, this study sought to determine the effects of morphine interaction with P2Y12 inhibitors on major adverse outcomes comprehensively, and identify the warning indicators.

Patients and Methods

Interaction signals were sought in 187,919 safety reports from the FDA Adverse Event Reporting System (FAERS) database, utilizing reporting odds ratios (repOR). In a cohort of 5240 acute coronary syndrome patients, the analyses were validated, and the biological effects of warning indicators were further studied with Mendelian randomization and mediation analysis.

Results

Potential risk of renal system adverse events in patients cotreated with morphine is significantly higher in FAERS (repOR 4.83, 95% CI 4.42-5.28, false discovery rate adjusted-P =3.55*10-209). The analysis of in-house patient cohorts validated these results with an increased risk of acute kidney injury (adjusted OR: 1.65; 95% CI: 1.20 to 2.26), and we also found a risk of myocardial infarction in patients treated with morphine (adjusted OR: 1.55; 95% CI: 1.14 to 2.11). The Morphine group exhibited diminished Plateletcrit (PCT) levels post-surgery and lower PCT levels were associated with an increased risk of AKI.

Conclusion

The administration of morphine in patients treated with P2Y12 receptor inhibitors should be carefully evaluated. PCT may serve as a potential warning indicator for morphine-related renal injury.

Chloroquine Intervenes Nephrotoxicity of Nilotinib through Deubiquitinase USP13-Mediated Stabilization of Bcl-XL

Nephrotoxicity has become prominent due to the increase in the clinical use of nilotinib, a second-generation BCR-ABL1 inhibitor in the first-line treatment of Philadelphia chromosome-positive chronic myeloid leukemia. To date, the mechanism of nilotinib nephrotoxicity is still unknown, leading to a lack of clinical intervention strategies. Here, it is found that nilotinib could induce glomerular atrophy, renal tubular degeneration, and kidney fibrosis in an animal model. Mechanistically, nilotinib induces intrinsic apoptosis by specifically reducing the level of BCL2 like 1 (Bcl-XL) in both vascular endothelial cells and renal tubular epithelial cells, as well as in vivo. It is confirmed that chloroquine (CQ) intervenes with nilotinib-induced apoptosis and improves mitochondrial integrity, reactive oxygen species accumulation, and DNA damage by reversing the decreased Bcl-XL. The intervention effect is dependent on the alleviation of the nilotinib-induced reduction in ubiquitin specific peptidase 13 (USP13) and does not rely on autophagy inhibition. Additionally, it is found that USP13 abrogates cell apoptosis by preventing excessive ubiquitin-proteasome degradation of Bcl-XL. In conclusion, the research reveals the molecular mechanism of nilotinib's nephrotoxicity, highlighting USP13 as an important regulator of Bcl-XL stability in determining cell fate, and provides CQ analogs as a clinical intervention strategy for nilotinib's nephrotoxicity.

Antioxidant Properties of Oral Antithrombotic Therapies in Atherosclerotic Disease and Atrial Fibrillation

The thrombosis-related diseases are one of the leading causes of illness and death in the general population, and despite significant improvements in long-term survival due to remarkable advances in pharmacologic therapy, they continue to pose a tremendous burden on healthcare systems. The oxidative stress plays a role of pivotal importance in thrombosis pathophysiology. The anticoagulant and antiplatelet drugs commonly used in the management of thrombosis-related diseases show several pleiotropic effects, beyond the antithrombotic effects. The present review aims to describe the current evidence about the antioxidant effects of the oral antithrombotic therapies in patients with atherosclerotic disease and atrial fibrillation.

Computational drug repositioning of clopidogrel as a novel therapeutic option for focal segmental glomerulosclerosis

Focal segmental glomerulosclerosis (FSGS) is a glomerular lesion often associated with nephrotic syndrome. It is also associated with a high risk of progression to end-stage kidney disease. Current treatment of FSGS is limited to systemic corticosteroids or calcineurin inhibition, along with inhibitors of the renin-angiotensin-aldosterone system. FSGS is heterogeneous in etiology, and novel therapies targeting specific, dysregulated molecular pathways represent a major unmet medical need. We have generated a network-based molecular model of FSGS pathophysiology using previously established systems biology workflows to allow computational evaluation of compounds for their predicted interference with molecular processes contributing to FSGS. We identified the anti-platelet drug clopidogrel as a therapeutic option to counterbalance dysregulated FSGS pathways. This prediction of our computational screen was validated by testing clopidogrel in the adriamycin FSGS mouse model. Clopidogrel improved key FSGS outcome parameters and significantly reduced urinary albumin to creatinine ratio (p<0.01) and weight loss (p<0.01), and ameliorated histopathological damage (p<0.05). Clopidogrel is used to treat several cardiovascular diseases linked to chronic kidney disease. Clopidogrel's favorable safety profile and its efficacy in the adriamycin mouse FSGS model thus recommend it as an attractive drug repositioning candidate for clinical trial in FSGS.

The Clinical Impact of Platelets on Post-Injury Serum Creatinine Concentration in Multiple Trauma Patients: A Retrospective Cohort Study

Background and objective: Platelets contribute to the immunological response after multiple trauma. To determine the clinical impact, this study analyzes the association between platelets and creatinine concentration as an indicator of kidney function in polytraumatized patients. Methods: We investigated all patients presenting an Injury Severity Score (ISS) ≥16 for a 2-year period at our trauma center. Platelet counts and creatinine concentrations were analyzed, and correlation analysis was performed within 10 days after multiple trauma. Results: 83 patients with a median ISS of 22 were included. Platelet count was decreased on day 3 (p ≤ 0.001) and increased on day 10 (p ≤ 0.001). Platelet count was elevated on day 10 in younger patients and diminished in severely injured patients (ISS ≥35) on day 1 (p = 0.012) and day 3 (p = 0.011). Creatinine concentration was decreased on day 1 (p = 0.003) and day 10 (p ≤ 0.001) in female patients. Age (p = 0.01), male sex (p = 0.004), and injury severity (p = 0.014) were identified as factors for increased creatinine concentration on day 1, whereas platelets (p = 0.046) were associated with decreased creatinine concentrations on day 5 after multiple trauma. Conclusions: Kinetics of platelet count and creatinine concentration are influenced by age, gender, and trauma severity. There was no clear correlation between platelet counts and creatinine concentration. However, platelets seem to have a modulating effect on creatinine concentrations in the vulnerable phase after trauma.

Dexmedetomidine Protects Human Renal Tubular Epithelial HK-2 Cells against Hypoxia/Reoxygenation Injury by Inactivating Endoplasmic Reticulum Stress Pathway

Objective

The study was aimed to investigate the effects and potential mechanisms of Dexmedetomidine (Dex) on hypoxia/reoxygenation (H/R) injury in human renal tubular epithelial HK-2 cells.

Materials and Methods

In this experimental study, HK-2 cells were divided into four groups: control group, Dex group, H/R group, and Dex+H/R group. The cells in control group received no treatment, and cells in Dex group were only treated with 0.1 nmol/L Dex. The cells in H/R group and Dex+H/R group were all treated with H/R (hypoxia for 24 hours and normoxia for 4 hours), and only the cells in Dex+H/R group were pre-administrated with 0.1 nmol/L Dex. Following treatments at 37˚C for 28 hours, cell viability and apoptosis were measured by MTT assay and flow cytometry, respectively. Also, the expressions of hypoxia-inducible factor 1 (HIF-1α), glucose-regulated protein 78 (GRP78), C/EBP homologous protein (CHOP), caspase-12 and cleaved caspase-3 were determined by western blot.

Results

The cell viability was significant decreased in H/R group compared with control group (P<0.05), while was significantly increased in Dex+H/R group compared with that in H/R group (P<0.05). However, the change tendency of the cell apoptosis was opposite to that of cell viability. Compared with H/R group, the expression of HIF-1α was evidently up-regulated, while GRP78, CHOP, capase-12 and cleaved caspase-3 expressions were all obviously down- regulated in Dex+H/R group (P<0.05). In addition, the concentrations of malondialdehyde (MDA) in H/R group and Dex+H/R group were 1.68 ± 0.22 nmol/mgprot and 0.85 ± 0.16 nmol/mgprot, respectively. The superoxide dismutase (SOD) activity was higher in Dex+H/R group (121 ± 11 U/L), which which was more than twice larger than that in H/R group (57 ± 10 U/L).

Conclusion

Dex could promote cell viability and inhibit apoptosis through up-regulating HIF-1α, reducing endoplasmic reticulum (ER) stress and mediating oxidative stress, thus ameliorating the H/R injury.

The inflammatory state is a risk factor for cardiovascular disease and graft fibrosis in kidney transplantation

Several factors, such as donor brain death, ischemia-reperfusion injury, rejection, infection, and chronic allograft dysfunction, may induce an inflammatory state in kidney transplantation. Furthermore, inflammatory cells, cytokines, growth factors, complement and coagulation cascade create an unbalanced interaction with innate and adaptive immunity, which are both heavily involved in atherogenesis. The crosstalk between inflammation and thrombosis may lead to a prothrombotic state and impaired fibrinolysis in kidney transplant recipients increasing the risk of cardiovascular disease. Inflammation is also associated with elevated levels of fibroblast growth factor 23 and low levels of Klotho, which contribute to major adverse cardiovascular events. Hyperuricemia, glucose intolerance, arterial hypertension, dyslipidemia, and physical inactivity may create a condition called metaflammation that concurs in atherogenesis. Another major consequence of the inflammatory state is the development of chronic hypoxia that through the mediation of interleukins 1 and 6, angiotensin II, and transforming growth factor beta can result in excessive accumulation of extracellular matrix, which can disrupt and replace functional parenchyma, leading to interstitial fibrosis and chronic allograft dysfunction. Lifestyle and regular physical activity may reduce inflammation. Several drugs have been proposed to control the graft inflammatory state, including low-dose aspirin, statins, renin-angiotensin inhibitors, xanthine-oxidase inhibitors, vitamin D supplements, and interleukin-6 blockade. However, no prospective controlled trial with these measures has been conducted in kidney transplantation.

Altered renal hemodynamics is associated with glomerular lipid accumulation in obese Dahl salt-sensitive leptin receptor mutant rats

The present study examined whether development of renal injury in the nondiabetic obese Dahl salt-sensitive leptin receptor mutant (SS^LepRmutant) strain is associated with elevations in glomerular filtration rate and renal lipid accumulation. Baseline mean arterial pressure at 6 wk of age was similar between Dahl salt-sensitive wild-type (SS_WT) and SS^LepRmutant rats. However, by 18 wk of age, the SS^LepRmutant strain developed hypertension, while the elevation in mean arterial pressure was not as severe in SS_WT rats (192 ± 4 and 149 ± 6 mmHg, respectively). At baseline, proteinuria was fourfold higher in SS^LepRmutant than SS_WT rats and remained elevated throughout the study. The early development of progressive proteinuria was associated with renal hyperfiltration followed by a decline in renal function over the course of study in the SS^LepRmutant compared with SS_WT rats. Kidneys from the SS^LepRmutant strain displayed more glomerulosclerosis and glomerular lipid accumulation than SS_WT rats. Glomeruli were isolated from the renal cortex of both strains at 6 and 18 wk of age, and RNA sequencing was performed to identify genes and pathways driving glomerular injury. We observed significant increases in expression of the influx lipid transporters, chemokine (C-X-C motif) ligand 16 (Cxcl16) and scavenger receptor and fatty acid translocase (Cd36), respectively, and a significant decrease in expression of the efflux lipid transporter, ATP-binding cassette subfamily A member 2 (Abca2; cholesterol efflux regulatory protein 2), in SS^LepRmutant compared with SS_WT rats at 6 and 18 wk of age, which were validated by RT-PCR analysis. These data suggest an association between glomerular hyperfiltration and glomerular lipid accumulation during the early development of proteinuria associated with obesity.

The role of platelets in acute kidney injury

Acute kidney injury (AKI), a major public health problem associated with high mortality and increased risk of progression towards end-stage renal disease, is characterized by the activation of intra-renal haemostatic and inflammatory processes. Platelets, which are present in high numbers in the circulation and can rapidly release a broad spectrum of bioactive mediators, are important acute modulators of inflammation and haemostasis, as they are the first cells to arrive at sites of acute injury, where they interact with endothelial cells and leukocytes. Diminished control of platelet reactivity by endothelial cells and/or an increased release of platelet-activating mediators can lead to uncontrolled platelet activation in AKI. As increased platelet sequestration and increased expression levels of the markers P-selectin, thromboxane A₂, CC-chemokine ligand 5 and platelet factor 4 on platelets have been reported in kidneys following AKI, platelet activation likely plays a part in AKI pathology. Results from animal models and some clinical studies highlight the potential of antiplatelet therapies in the preservation of renal function in the context of AKI, but as current strategies also affect other cell types and non-platelet-derived mediators, additional studies are required to further elucidate the extent of platelet contribution to the pathology of AKI and to determine the best therapeutic approach by which to specifically target related pathogenic pathways.

Thromboinflammation: challenges of therapeutically targeting coagulation and other host defense mechanisms

Thrombosis with associated inflammation (thromboinflammation) occurs commonly in a broad range of human disorders. It is well recognized clinically in the context of superficial thrombophlebitis (thrombosis and inflammation of superficial veins); however, it is more dangerous when it develops in the microvasculature of injured tissues and organs. Microvascular thrombosis with associated inflammation is well recognized in the context of sepsis and ischemia-reperfusion injury; however, it also occurs in organ transplant rejection, major trauma, severe burns, the antiphospholipid syndrome, preeclampsia, sickle cell disease, and biomaterial-induced thromboinflammation. Central to thromboinflammation is the loss of the normal antithrombotic and anti-inflammatory functions of endothelial cells, leading to dysregulation of coagulation, complement, platelet activation, and leukocyte recruitment in the microvasculature. α-Thrombin plays a critical role in coordinating thrombotic and inflammatory responses and has long been considered an attractive therapeutic target to reduce thromboinflammatory complications. This review focuses on the role of basic aspects of coagulation and α-thrombin in promoting thromboinflammatory responses and discusses insights gained from clinical trials on the effects of various inhibitors of coagulation on thromboinflammatory disorders. Studies in sepsis patients have been particularly informative because, despite using anticoagulant approaches with different pharmacological profiles, which act at distinct points in the coagulation cascade, bleeding complications continue to undermine clinical benefit. Future advances may require the development of therapeutics with primary anti-inflammatory and cytoprotective properties, which have less impact on hemostasis. This may be possible with the growing recognition that components of blood coagulation and platelets have prothrombotic and proinflammatory functions independent of their hemostatic effects.

The Effect of Clopidogrel on the Response to Ischemia Reperfusion

Reperfusion in the setting of acute ischemia is essential in limiting tissue necrosis. However, reperfusion itself is associated with significant adverse effects. There is animal evidence that platelets play a role in the adverse effects of ischemia and reperfusion (IR) injury. We examined whether clopidogrel would have favorable effects on endothelial dysfunction induced by an episode of IR. Using a parallel design, we administered clopidogrel 600 mg or matching placebo to normal volunteers (n = 20) 24 hours before an episode of IR. Flow-mediated dilatation (FMD, radial artery) was assessed before and after 20 minutes of upper arm ischemia. Following IR, there was a highly significant decrease in FMD in the placebo group (7.6% ± 1.3% vs 3.4% ± 0.1%; P < .001). In the clopidogrel group, there was no change in FMD post-IR (8.3% ± 0.8% vs 7.1% ± 1.2%; P = not significant). Following IR, FMD in the placebo group was significantly smaller than that observed in the clopidogrel group ( P < .01). Ischemia and reperfusion caused no change in plasma levels of biomarkers of inflammation (intercellular adhesion molecule 1, chemokine ligand 5, and interleukin 6) in either group. Therefore, a single dose of clopidogrel given 24 hours prior to an episode of IR had protective effects, limiting the adverse effects of ischemia on endothelial function.

Release of extracellular DNA influences renal ischemia reperfusion injury by platelet activation and formation of neutrophil extracellular traps

Acute kidney injury is often the result of ischemia reperfusion injury, which leads to activation of coagulation and inflammation, resulting in necrosis of renal tubular epithelial cells. Platelets play a central role in coagulation and inflammatory processes, and it has been shown that platelet activation exacerbates acute kidney injury. However, the mechanism of platelet activation during ischemia reperfusion injury and how platelet activation leads to tissue injury are largely unknown. Here we found that renal ischemia reperfusion injury in mice leads to increased platelet activation in immediate proximity of necrotic cell casts. Furthermore, platelet inhibition by clopidogrel decreased cell necrosis and inflammation, indicating a link between platelet activation and renal tissue damage. Necrotic tubular epithelial cells were found to release extracellular DNA, which, in turn, activated platelets, leading to platelet-granulocyte interaction and formation of neutrophil extracellular traps ex vivo. Renal ischemia reperfusion injury resulted in increased DNA-platelet and DNA-platelet-granulocyte colocalization in tissue and elevated levels of circulating extracellular DNA and platelet factor 4 in mice. After renal ischemia reperfusion injury, neutrophil extracellular traps were formed within renal tissue, which decreased when mice were treated with the platelet inhibitor clopidogrel. Thus, during renal ischemia reperfusion injury, necrotic cell-derived DNA leads to platelet activation, platelet-granulocyte interaction, and subsequent neutrophil extracellular trap formation, leading to renal inflammation and further increase in tissue injury.

Protective effects of ginseng extracts and common anti-aggregant drugs on ischaemia-reperfusion injury

OBJECTIVE

Ginseng is a traditional herbal medicinal product widely used for various types of diseases because of its cellular protective effects. Possible protective effects of ginseng were investigated in blood, cardiac and renal tissue samples and compared with common anti-aggregant agents in an animal ischaemia-reperfusion (I/R) model.

METHODS

Twenty rats were equally divided into four different groups as follows: control group (I/R-induced group without drug use), group I (acetylsalicylic acid-administered group), group II (clopidogrel bisulfate-administered group), group III (ginsenoside Rb1-administered group). For the groups assigned to a medication, peripheral I/R was induced by clamping the femoral artery one week after initiation of the specified medication. After reperfusion was initiated, cardiac and renal tissues and blood samples were obtained from each rat with subsequent analysis of nitrogen oxide (NOx), malondialdehyde (MDA), paraoxonase 1 (PON1) and prolidase.

RESULTS

NOx levels were similar in each group. Significant decrements were observed in serum PON1 levels in each group when compared with the control (p < 0.05). Serum MDA levels were significantly lower in groups II and III (p < 0.05). Ameliorated renal prolidase levels were detected in study groups (p < 0.05) and recovered cardiac prolidase levels were obtained in groups II and III (p < 0.05).

CONCLUSION

These findings indicate that ginseng extracts may have a potential beneficial effect in I/R injury. However, more comprehensive studies are required to clarify the hypothetical cardiac, renal and systemic protective effects in reperfusion-induced oxidative damage.

New frontiers for platelet CD154

The role of platelets extends beyond hemostasis. The pivotal role of platelets in inflammation has shed new light on the natural history of conditions associated with acute or chronic inflammation. Beyond the preservation of vascular integrity, platelets are essential to tissue homeostasis and platelet-derived products are already used in the clinics. Unanticipated was the role of platelets in the adaptative immune response, allowing a renewed conceptual approach of auto-immune diseases. Platelets are also important players in cancer growth and dissemination. Platelets fulfill most of their functions through the expression of still incompletely characterized membrane-bound or soluble mediators. Among them, CD154 holds a peculiar position, as platelets represent a major source of CD154 and as CD154 contributes to most of these new platelet attributes. Here, we provide an overview of some of the new frontiers that the study of platelet CD154 is opening, in inflammation, tissue homeostasis, immune response, hematopoiesis and cancer.

Investigation of possible prophylactic, renoprotective, and cardioprotective effects of thromboprophylactic drugs against ischemia-reperfusion injury

The aim of this study was to investigate whether anticoagulant and antiaggregant agents have protective effects against oxidative damage induced by peripheral ischemia-reperfusion (I/R). Groups were created as follows: control group, I/R group (sham group), I/R plus acetylsalicylic acid (Group I), I/R+clopidogrel (Group II), I/R+rivaroxaban (Group III), I/R+bemiparin sodium (Group IV), and I/R+enoxaparin sodium (Group V). In Groups I, II, III, IV, and V, drugs were administered daily for 1 week before I/R creation. Peripheral I/R was induced in the I/R groups by clamping the right femoral artery. The rats were sacrificed 1 hour after reperfusion. Nitrogen oxide levels, malondialdehyde (MDA) levels, paraoxonase-1 (PON1) activity, and prolidase activity were evaluated in both cardiac and renal tissues. There was no significant difference in nitrogen oxide levels between the groups. However, cardiac and renal MDA were significantly higher and PON1 activity was markedly lower in the I/R groups compared with the control group (p<0.05). Although elevated prolidase activity was detected in both the cardiac and renal tissue of the I/R groups, only the sham group and Group V had significantly higher renal prolidase activity (p<0.05). Group V had significantly higher cardiac MDA, PON1, prolidase levels, and renal prolidase activity compared with the sham group (p<0.05). Significant improvement in renal MDA levels was only observed in Group III, and marked improvement was observed in the cardiac MDA levels of Group II when compared with the sham group (p<0.05). Thromboprophylactic agents appear to provide partial or prominent protection against I/R injury.

MicroRNA-21 attenuates renal ischemia reperfusion injury via targeting caspase signaling in mice

BACKGROUND

MicroRNAs (miR) have come into focus as powerful regulators of gene expression and potential diagnostic tools during renal ischemia reperfusion injury (IRI). The aim of this study was to investigate the molecular regulation and function of miR-21, and to analyze the relationship between caspases and miR-21 expression levels in an experimental model of renal IRI.

METHODS

IRI was induced by bilateral renal ischemia for 45 min followed by reperfusion. The male BALB/c mice were randomly assigned to the following groups: pre-miR-21 + IRI group, antagomiR-21 + IRI group, PBS + IRI group, pre-miR-21 + sham operation group, antagomiR-21 + sham operation group, PBS + sham operation group. The pre-miR-21 or antagomiR-21 was administered intraperitoneally (200 ng/kg weight) 24 and 6 h before induction of ischemia. Renal function, histological damage, renal cell apoptosis proteins were evaluated at 24 h after reperfusion.

RESULTS

Mice upregulated miR-21 had lower plasma levels of blood urea nitrogen (BUN) and creatinine, lower histopathological scores and a decrease in programmed cell death 4 (PDCD4) mRNA and active caspase-3, caspase-8 proteins expressions.

CONCLUSIONS

miR-21 is endowed with anti-apoptotic properties by suppressing the expression of PDCD4 gene and active caspase 3/8 fragments in the condition of renal IRI. miR-21 exerts significant functional protection in our renal murine model of IRI.

Clopidogrel improves microvascular endothelial function in subjects with stable coronary artery disease

BACKGROUND

Clopidogrel therapy has recently been shown to reduce cardiovascular events in patients with stable vascular disease. This benefit may be due to effects not exclusively related to platelet aggregation. The aim of this study was to evaluate the effect of clopidogrel therapy on microvascular endothelial function in subjects with stable coronary artery disease (CAD).

METHODS AND RESULTS

Forty subjects with stable CAD were randomised to clopidogrel therapy (75mg/day) or control. Blood and endothelial function testing occurred at baseline, one week and three months following randomisation. Microvascular endothelial function was assessed via reactive hyperaemic index (RHI). Platelet function was assessed by adenosine diphosphate (ADP)-induced whole blood aggregation and the VerifyNow™ system. Plasma markers of endothelial function (asymmetric dimethylarginine, ADMA) and oxidative stress (myeloperoxidase, MPO) were also tested. The primary endpoint was endothelial function assessment (RHI) at three months. At one week RHI increased by 20±10% in the clopidogrel group; this effect was maintained at three months (21±9% increase from baseline; P<0.01). A significant decrease in ADP-induced platelet aggregation and P2Y12 reaction units was observed in the clopidogrel therapy group (P<0.01). There was no correlation between endothelial function and platelet function testing in the clopidogrel therapy group.

CONCLUSION

Clopidogrel therapy is associated with improved microvascular endothelial function in patients with stable CAD. This effect is independent of its effects on ADP-induced platelet reactivity.

Renal oxygenation and haemodynamics in acute kidney injury and chronic kidney disease

Acute kidney injury (AKI) is a major burden on health systems and may arise from multiple initiating insults, including ischaemia-reperfusion injury, cardiovascular surgery, radiocontrast administration and sepsis. Similarly, the incidence and prevalence of chronic kidney disease (CKD) continues to increase, with significant morbidity and mortality. Moreover, an increasing number of AKI patients survive to develop CKD and end-stage renal disease. Although the mechanisms for the development of AKI and progression to CKD remain poorly understood, initial impairment of oxygen balance likely constitutes a common pathway, causing renal tissue hypoxia and ATP starvation that, in turn, induce extracellular matrix production, collagen deposition and fibrosis. Thus, possible future strategies for one or both conditions may involve dopamine, loop diuretics, atrial natriuretic peptide and inhibitors of inducible nitric oxide synthase, substances that target kidney oxygen consumption and regulators of renal oxygenation, such as nitric oxide and heme oxygenase-1.

Alpha-lipoic acid ameliorates oxidative stress by increasing aldehyde dehydrogenase-2 activity in patients with acute coronary syndrome

Aldehyde dehydrogenase-2 (ALDH2) is the main enzyme responsible for acetaldehyde oxidation in ethanol metabolism and also provides protection against oxidative stress. Alpha-lipoic acid (α-LA), a natural dithiol compound with antioxidant properties, has been reported to increase ALDH2 activity in cultured cells. We analyzed the therapeutic efficacy of α-LA in 63 patients with confirmed acute coronary syndrome (ACS). These patients (52 men and 11 women, with age range 49-72 years) were randomized into two groups: untreated group (n = 30) and α-LA group (n = 33). Patients in the α-LA group were given an intravenous injection of 600 mg α-LA every day for 5 days while the patients in the untreated group were given saline. An isoprostane, 8-iso-prostaglandin F2α (8-iso-PGF2α), one product of arachidonic acid metabolism, was measured as a marker for oxidative stress. The serum levels of 8-iso-PGF2α and ALDH2 activity were determined at admission to the hospital (time 0), and at 24 hours and 1 week after treatment. At 24 hours and 1 week after treatment, ALDH2 activity was significantly higher in the α-LA group than in the untreated group (P < 0.05), whereas the levels of 8-iso-PGF2α were significantly lower in the α-LA group than in the untreated group (all P < 0.05). Importantly, the decrease of 8-iso-PGF2α levels correlated with the increased ALDH2 activity at both 24 hours (r = 0.6234, P < 0.001) and 1 week after treatment (r = -0.3941, P = 0.0014). α-LA may ameliorate oxidative stress through up-regulating ALDH2 activity in patients with ACS.

Pioglitazone protects against renal ischemia-reperfusion injury by enhancing antioxidant capacity

BACKGROUND

In our previous study, we showed that pioglitazone exerts protective effects on renal ischemia-reperfusion injury (IRI) in mice by abrogating renal cell apoptosis. Oxidative stress due to excessive production of reactive oxygen species and subsequent lipid peroxidation plays a critical role in renal IRI. The purpose of the current study is to demonstrate the effect of pioglitazone on renal IRI by modulation of oxidative stress.

MATERIALS AND METHODS

IRI was induced by bilateral renal ischemia for 45 min followed by reperfusion. Thirty healthy male Balb/c mice were randomly assigned to one of the following groups: phosphate buffer solution (PBS) + IRI, pioglitazone + IRI, PBS + sham IRI, pioglitazone + sham IRI. Kidney function tests and kidney antioxidant activities were determined 24 h after reperfusion.

RESULTS

Pretreatment with pioglitazone produced reduction in serum levels of blood urea nitrogen and creatinine caused by IRI. Pretreatment with pioglitazone before IRI resulted in a higher level of kidney enzymatic activities of superoxide dismutase, glutathione, catalase, and total antioxidant capacity than in the PBS-pretreated IRI group.

CONCLUSIONS

Our results indicate that pioglitazone can provide protection for kidneys against IRI by enhancing antioxidant capacity. Therefore, pioglitazone could be a potential therapeutic approach to prevent renal IRI relevant to various clinical conditions.

Dynamin-related protein-1 controls fusion pore dynamics during platelet granule exocytosis

OBJECTIVE

Platelet granule exocytosis serves a central role in hemostasis and thrombosis. Recently, single-cell amperometry has shown that platelet membrane fusion during granule exocytosis results in the formation of a fusion pore that subsequently expands to enable the extrusion of granule contents. However, the molecular mechanisms that control platelet fusion pore expansion and collapse are not known.

METHODS AND RESULTS

We identified dynamin-related protein-1 (Drp1) in platelets and found that an inhibitor of Drp1, mdivi-1, blocked exocytosis of both platelet dense and α-granules. We used single-cell amperometry to monitor serotonin release from individual dense granules and, thereby, measured the effect of Drp1 inhibition on fusion pore dynamics. Inhibition of Drp1 increased spike width and decreased prespike foot events, indicating that Drp1 influences fusion pore formation and expansion. Platelet-mediated thrombus formation in vivo after laser-induced injury of mouse cremaster arterioles was impaired after infusion of mdivi-1.

CONCLUSIONS

These results demonstrate that inhibition of Drp1 disrupts platelet fusion pore dynamics and indicate that Drp1 can be targeted to control thrombus formation in vivo.

Anti-oxidized low-density lipoprotein antibodies in chronic heart failure

Oxidative stress may play a significant role in the pathogenesis of heart failure (HF). Antibodies to oxidized low-density lipoprotein (oxLDL Abs) reflect an immune response to LDL over a prolonged period and may represent long-term oxidative stress in HF. The oxLDL plasma level is a useful predictor of mortality in HF patients, and measurement of the oxLDL Abs level may allow better management of those patients. Antibodies to oxLDL also significantly correlate with the New York Heart Association score. Hypercholesterolemia, smoking, hypertension, and obesity are risk factors for atherosclerotic coronary heart disease (CHD) leading to HF, but these factors account for only one-half of all cases, and understanding of the pathologic process underlying HF remains incomplete. Nutrients with antioxidant properties can reduce the susceptibility of LDL to oxidation. Antioxidant therapy may be an adjunct to lipid-lowering, angiotensin converting enzyme inhibition and metformin (in diabetes) therapy for the greatest impact on CHD and HF. Observational data suggest a protective effect of antioxidant supplementation on the incidence of HD. This review summarizes the data on oxLDL Abs as a predictor of morbidity and mortality in HF patients.

Protective effects of phosphodiesterase-4-specific inhibitor rolipram on acute ischemia-reperfusion injury in rat kidney

OBJECTIVE

To investigate the effect of Rolipram, a phosphodiesterase-4-inhibitor, on renal ischemia-reperfusion injury (IRI) in rats.

METHODS

Thirty rats were divided into 5 different groups of 6 rats. Nothing was done to the control group. In the second group, the renal pedicle was clamped for 30 minutes. In the third group, 1 mg/kg of Rolipram was given by intraperitoneal injection 30 minutes before clamping. The fourth group received the same injection when the clamp was placed, as did the fifth group 30 minutes after the clamp was opened. Clamping time was set at 30 minutes. Twenty-four hours later, nephrectomy was performed in all the groups. Half of each kidney was examined histopathologically. Levels of biochemical agents, such as malondialdehyde, superoxide dismutase, and catalase, were measured in the other half.

RESULTS

The malondialdehyde (MDA) levels significantly decreased and reached control levels in the group in which Rolipram was administered 30 minutes after reperfusion (P = .07). The catalase and superoxide dismutase activities obtained from renal homogentisates of the ischemia groups were evaluated; there were striking increases in tissue levels of these 2 enzymes in the groups in which Rolipram was administered during ischemia and 30 minutes after ischemia (P < .001). Histopathologically, there was no significant difference in inflammation between the Rolipram-administrated groups compared with group 1 (control) and group 2 (IRI). Tubular necrosis and apoptosis was significantly lower in group 5 than the other groups, except group 1 (P < .001).

CONCLUSION

We suggest that in surgical procedures that can lead to renal IRI, the administration of Rolipram can decrease oxidative renal tissue damage and the severe deterioration of renal function.

Effect of DHA+EPA on oxidative stress and apoptosis induced by ischemia-reperfusion in rat kidneys

Apoptosis, as well as necrosis, has an important role in post-ischemic renal pathology. The effect of pretreatment with Docosahexaenoic acid+Eicosapentaenoic acid (DHA+EPA) on renal injury and apoptotic protein expression was evaluated. Right nephrectomy was completed on male Wistar rats (255-300 g). The rats received DHA+EPA (200 mg/kg/day) of distilled water orally for 14 days before ischemia reperfusion (IR) or sham operation. A total of 81 rats were divided into three main groups with 6, 24 and 48 h of post-operation or reperfusion period. Serum creatinine (SCr), BUN, creatinine clearance (CCr) and fractional excretion of sodium (FEN a ) were measured. Tissue levels of malondialdehyde (MDA), superoxide dismutase (SOD) and catalase (CAT) activities, Bax and Bcl-2 protein expressions and renal histological injury were determined. SCr, BUN and FEN a increased 6-48 h of reperfusion (P < 0.01). Tissue MDA content and Bax expression increased (P < 0.01) and CAT and SOD activities decreased (P < 0.05) in the IR group. DHA+EPA decreased SCr and BUN, FEN a , tissue MDA levels (P < 0.05 vs. IR) and increased CAT and SOD activities and Bcl-2 expression (P < 0.05 vs. IR) for 6-48 h after ischemia. IR induced mild (6 h, P < 0.05) and severe (24-48 h, P < 0.01) tissue damage. Mild-to-moderate tissue damage was observed in DHA+EPA groups from 6 to 48 h of reperfusion period (P < 0.05 vs. IR, 24-48 h). In conclusion, the results suggest that pre-ischemic exposure to DHA+EPA could improve the outcome of early graft function by inhibition of IR-induced oxidative stress and apoptosis.

Combination of cilostazol and clopidogrel attenuates rat critical limb ischemia

BACKGROUND AND AIM

Procedural failure and untoward clinical outcomes after surgery remain problematic in critical limb ischemia (CLI) patients. This study tested a clopidogrel-cilostazol combination treatment compared with either treatment alone in attenuating CLI and improving CLI-region blood flow in rats.

METHODS

Male Sprague-Dawley rats (n = 40) were equally divided into five groups: control, CLI induction only, CL I + cilostazol (12.0 mg/day/kg), CLI + clopidogrel (8.0 mg/kg/day) and CLI + combined cilostazol-clopidogrel. After treatment for 21 days, Laser Doppler imaging was performed.

RESULTS

On day 21, the untreated CLI group had the lowest ratio of ischemic/normal blood flow (p < 0.001). Inflammation measured by VCAM-1 protein expression; oxidative stress; PAI-1, MMP-9 and TNF-α mRNA expressions; and immunofluorescence staining (IF) of CD68+ cells was lower with combined treatment than with the other treatments, and lower in the two single-treatment groups than the untreated CLI group (all p < 0.01). Anti-inflammatory mRNA expression of interleukin-10, and eNOS showed a reverse pattern among these groups. Apoptosis measured by Bax, caspase-3 and PARP; and muscle damage measured by cytosolic cytochrome-C, and serum and muscle micro-RNA-206 were all lowest with combination treatment, and the two single-treatment groups showed lower values than the untreated group (all p < 0.001). Angiogenesis measured by eNOS, IF staining of CD31+ and vWF + cells; and number of vessels in CLI region were highest with combination treatment and higher in the single-treatment groups than the untreated group (all p < 0.001).

CONCLUSION

Combined cilostazol-clopidogrel therapy is superior to either agent alone in improving ischemia in rodent CLI.

Protective effects of pioglitazone on renal ischemia-reperfusion injury in mice

BACKGROUND

Renal ischemia-reperfusion injury (IRI) is a complex pathophysiologic process involving cell apoptosis and oxidant damages that leads to acute renal failure in both native kidneys and renal allografts. Pioglitazone is a novel class of oral antidiabetic agents currently used to treat type 2 diabetes mellitus. Pioglitazone exerts protective effects on acute myocardial ischemia and acute cerebral ischemia. The aim of this study was to investigate the possible beneficial effects of pioglitazone on renal IRI in mice.

METHODS

IRI was induced by bilateral renal ischemia for 45 min followed by reperfusion. Fifty-five healthy male Balb/c mice were randomly assigned to one of the following groups: PBS + IRI, pioglitazone + IRI, PBS + sham IRI, pioglitazone + sham IRI. Kidney function tests, histopathologic examination, renal cell Bcl-2, and Bax expression were determined 24 h after reperfusion. Animals' survival was examined 7 days after operation.

RESULTS

Animals pretreated with pioglitazone had lower plasma levels of blood urea nitrogen and creatinine caused by IRI, lower histopathologic scores, and improved survival rates following IRI. Renal cell apoptosis induced by IRI was abrogated in kidneys of mice pretreated by pioglitazone, with an increase in Bcl-2 expression and a decrease in Bax expression. Furthermore, pioglitazone pretreatment protected against lethal renal IRI.

CONCLUSIONS

Peroxisome proliferator-activated receptor activation by pioglitazone exerts protective effects on renal IRI in mice by abrogating renal cell apoptosis. Thus, pioglitazone could be a novel therapeutic tool in renal IRI.