The caspase-3 inhibitor (peptide Z-DEVD-FMK) affects the survival and function of platelets in platelet concentrate during storage

Dengue Envelope Protein as a Cytotoxic Factor Inducing Hemorrhage and Endothelial Cell Death in Mice

Dengue virus (DENV) infection, prevalent in tropical and subtropical regions, can progress to dengue hemorrhagic fever (DHF), which increases mortality during secondary infections. DHF is characterized by endothelial damage and vascular leakage. Despite its severity, no specific antiviral treatments exist, and the viral factors responsible for endothelial damage remain unclear. This study examines the role of the DENV envelope protein domain III (EIII) in inducing endothelial apoptosis using a mouse model. Additionally, we aim to explore whether cell death-inducing pathways could serve as drug targets to ameliorate EIII-induced endothelial injury and hemorrhage. In vitro experiments using human endothelial HMEC-1 cells demonstrated that both recombinant EIII (rEIII) and DENV markedly induced caspase-3-mediated endothelial cell death, an effect that was attenuated by co-treatment with chondroitin sulfate B (CSB), N-acetyl cysteine (NAC), and the caspase-3 inhibitor z-DEVD-FMK. In vivo, sequential injections of rEIII and anti-platelet immunoglobulin in mice, designed to mimic the clinical phase of DHF with peak viremia followed by an increase in DENV-induced Ig, including autoantibodies, revealed that these dual treatments markedly triggered caspase-3-dependent apoptosis in vascular endothelial cells at hemorrhage sites. Treatments with z-DEVD-FMK effectively reduced DHF-like symptoms such as thrombocytopenia, hemorrhage, inflammation, hypercoagulation, and endothelial damage. Additionally, CSB and NAC alleviated hemorrhagic symptoms in the mice. These results suggest that targeting EIII, reactive oxygen species, and caspase-3-mediated apoptosis could offer potential therapeutic strategies for addressing EIII-induced hemorrhagic pathogenesis.

Oxidative modulations in platelets stored in SSP+, PAS-G and Tyrode's buffer: a comparative analysis

BACKGROUND

Platelet additive solutions (PASs) improve the efficacy of stored platelets. Oxidative stress causes storage lesions and platelet functions deteriorate. Studies assessing the influence of oxidative stress on platelets stored in PASs are limited. This study compares variations in platelets in different storage solutions (SSP+, PAS-G and Tyrode's buffer).

METHODS

Platelets isolated from the blood of Wistar rats were resuspended in SSP+, PAS-G and Tyrode's buffer and stored for seven days at 22 °C. The markers of platelet metabolism, function, oxidative stress, antioxidant status and viability were analyzed on Days 1, 3, 5 and 7 of storage.

MAIN RESULTS

SSP+ is associated with platelet function, viability and antioxidant defenses (SOD, CAT and GSH); it decreased primary lipid peroxidation products and maintained the susceptible protein groups in reduced state. Platelet function, antioxidant defenses such as SOD and GSH improved, and lipids and thiols were protected from oxidation in PAS-G. SOD and GSH increased, and lipids and thiols were preserved in Tyrode's buffer.

CONCLUSION

SSP+ and PAS-G are more effective in maintaining platelet efficacy till Day 7 compared to Tyrode's buffer. Thus, PAS-G and SSP+ are better than Tyrode's buffer in terms of platelet responses to oxidative stress during storage. This is the first comparative account on the influence of PASs (SSP+, PAS-G and Tyrode's buffer) on platelets in altering oxidative stress. It provides a comprehensive view of the differential responses of platelets in PASs.

Working title: Molecular involvement of p53-MDM2 interactome in gastrointestinal cancers

The interaction between murine double minute 2 (MDM2) and p53, marked by transcriptional induction and feedback inhibition, orchestrates a functional loop dictating cellular fate. The functional loop comprising p53-MDM2 axis is made up of an interactome consisting of approximately 81 proteins, which are spatio-temporally regulated and involved in DNA repair mechanisms. Biochemical and genetic alterations of the interactome result in dysregulation of the p53-mdm2 axis that leads to gastrointestinal (GI) cancers. A large subset of interactome is well known and it consists of proteins that either stabilize p53 or MDM2 and proteins that target the p53-MDM2 complex for ubiquitin-mediated destruction. Upstream signaling events brought about by growth factors and chemical messengers invoke a wide variety of posttranslational modifications in p53-MDM2 axis. Biochemical changes in the transactivation domain of p53 impact the energy landscape, induce conformational switching, alter interaction potential and could change solubility of p53 to redefine its co-localization, translocation and activity. A diverse set of chemical compounds mimic physiological effectors and simulate biochemical modifications of the p53-MDM2 interactome. p53-MDM2 interactome plays a crucial role in DNA damage and repair process. Genetic aberrations in the interactome, have resulted in cancers of GI tract (pancreas, liver, colorectal, gastric, biliary, and esophageal). We present in this article a review of the overall changes in the p53-MDM2 interactors and the effectors that form an epicenter for the development of next-generation molecules for understanding and targeting GI cancers.

Cardiopulmonary bypass in a rat model may shorten the lifespan of stored red blood cells by activating caspase-3

BACKGROUND

Red blood cell transfusion is required for many types of surgery against cardiovascular disease, and the function of transfused cells appears to decline over time. The present study examined whether transfusion also reduces red blood cell lifespan in a rat model.

MATERIAL AND METHODS

Bypass in rats were established by connecting a roll pump to the femoral artery and vein. Then FITC-labeled stored red blood cells from rats were transfused in the animals, and the cells in circulation were counted after transfusion. In separate experiments, stored red blood cells were incubated with bypass plasma in vitro, and the effects of incubation were assessed on cell morphology, redox activity, ATP level, caspase-3 activity, and phosphatidylserine exposure on the cell surface. These in vivo and in vitro experiments were also performed after pretreating the stored red blood cells with the caspase-3 inhibitor Z-DEVD-FMK.

RESULTS

Bypass significantly decreased the number of circulating FITC-labeled stored red blood cells and increased the proportions of monocytes, neutrophils and splenic macrophages that had phagocytosed the red blood cells. In vitro, bypass plasma altered the morphology of red blood cells and increased oxidative stress, caspase-3 activity and phosphatidylserine exposure, while decreasing ATP level. Pretreating stored red blood cells with Z-DEVD-FMK attenuated the effects of bypass on caspase-3 activity, but not oxidative stress, in stored red blood cells.

DISCUSSION

Bypass appears to shorten the lifespan of stored red blood cells, at least in part by activating caspase-3 in the cells.

Platelet storage: Progress so far

There is a crucial need for platelet transfusion during an emergency-surgery and treatment of platelet disorders. The unavailability of donors has furthermore increased the demand for platelet storage. Platelets have limited shelf life due to bacterial contamination and storage lesions. Temperature, materials, oxygen availability, media, platelet processing and manufacturing methods influence the platelet quality and viability during storage. The conception of various platelet additive solutions along with the advent of plastic storage during the 1980s led to enormous developments in platelet storage strategies. Cold storage of platelets gained attention despite its inability to contribute to platelet survival post-transfusion as it offers faster haemostasis. Several developments in platelet storage strategies over the years have improved the quality and shelf-life of stored platelets. Despite the progress, the efficacy of platelets during storage beyond a week has not been achieved. Antioxidants as additives have been explored in platelet storage and have proven to enhance the efficacy of platelets during prolonged storage. However, the molecular interactions of antioxidants in platelets can provide a better understanding of their mechanism of action. Optimization of dosage concentrations of antioxidants is also a critical parameter to be considered as they tend to exhibit toxicity at certain levels. This review provides comprehensive insights into the critical factors affecting platelet storage and the evolution of platelet storage. It also emphasizes the role of antioxidants as additives in platelet storage solutions and their future prospects towards better platelet banking.

Divalent magnesium restores cytoskeletal storage lesions in cold-stored platelet concentrates

Cold storage of platelet concentrates (PC) has become attractive due to the reduced risk of bacterial proliferation, but in vivo circulation time of cold-stored platelets is reduced. Ca²⁺ release from storage organelles and higher activity of Ca²⁺ pumps at temperatures < 15 °C triggers cytoskeleton changes. This is suppressed by Mg²⁺ addition, avoiding a shift in Ca²⁺ hemostasis and cytoskeletal alterations. We report on the impact of 2–10 mM Mg²⁺ on cytoskeleton alterations of platelets from PC stored at room temperature (RT) or 4 °C in additive solution (PAS), 30% plasma. Deformation of platelets was assessed by real-time deformability cytometry (RT-DC), a method for biomechanical cell characterization. Deformation was strongly affected by storage at 4 °C and preserved by Mg²⁺ addition ≥ 4 mM Mg²⁺ (mean ± SD of median deformation 4 °C vs. 4 °C + 10 mM Mg²⁺ 0.073 ± 0.021 vs. 0.118 ± 0.023, p < 0.01; n = 6, day 7). These results were confirmed by immunofluorescence microscopy, showing that Mg²⁺  ≥ 4 mM prevents 4 °C storage induced cytoskeletal structure lesion. Standard in vitro platelet function tests showed minor differences between RT and cold-stored platelets. Hypotonic shock response was not significantly different between RT stored (56.38 ± 29.36%) and cold-stored platelets with (55.22 ± 11.16%) or without magnesium (45.65 ± 11.59%; p = 0.042, all n = 6, day 1). CD62P expression and platelet aggregation response were similar between RT and 4 °C stored platelets, with minor changes in the presence of higher Mg²⁺ concentrations. In conclusion, increasing Mg²⁺ up to 10 mM in PAS counteracts 4 °C storage lesions in platelets, maintains platelet cytoskeletal integrity and biomechanical properties comparable to RT stored platelets.

Nanodiamond-Induced Thrombocytopenia in Mice Involve P-Selectin-Dependent Nlrp3 Inflammasome-Mediated Platelet Aggregation, Pyroptosis and Apoptosis

Nanodiamond (ND) has been developed as a carrier to conduct various in vivo diagnostic and therapeutic uses. Safety is one of the major considerations, while the hemocompatibility of ND is not clearly addressed. Here we found that, compared to the other sizes of ND with relatively inert properties, treatments of 50 nm ND induced stronger platelet aggregation, platelet pyroptosis, apoptosis and thrombocytopenia in mice. Blockage treatments of soluble P-selectin, reactive oxygen species (ROS), and Nlrp3 inflammasome inhibitors markedly suppressed such adverse effects, suggesting ND-induced platelet activation and pyroptosis involves surface P-selectin-mediated enhancement of mitochondrial superoxide levels and Nlrp3 inflammasome activation. In addition, challenges of NDs induced less platelet pyroptosis and displayed less thrombocytopenia in P-selectin (Selp^-/-), Nlrp3 (Nlrp3^-/-) and caspase-1 (Casp1^-/-) mutants, as compared to the wild type mice. Blockers of P-selectin, ROS, and Nlrp3 inflammasome pathways could be considered as antidotes for ND induced platelet activation and thrombocytopenia.

Spinal Cord Injury: Pathophysiology, Multimolecular Interactions, and Underlying Recovery Mechanisms

Spinal cord injury (SCI) is a destructive neurological and pathological state that causes major motor, sensory and autonomic dysfunctions. Its pathophysiology comprises acute and chronic phases and incorporates a cascade of destructive events such as ischemia, oxidative stress, inflammatory events, apoptotic pathways and locomotor dysfunctions. Many therapeutic strategies have been proposed to overcome neurodegenerative events and reduce secondary neuronal damage. Efforts have also been devoted in developing neuroprotective and neuro-regenerative therapies that promote neuronal recovery and outcome. Although varying degrees of success have been achieved, curative accomplishment is still elusive probably due to the complex healing and protective mechanisms involved. Thus, current understanding in this area must be assessed to formulate appropriate treatment modalities to improve SCI recovery. This review aims to promote the understanding of SCI pathophysiology, interrelated or interlinked multimolecular interactions and various methods of neuronal recovery i.e., neuroprotective, immunomodulatory and neuro-regenerative pathways and relevant approaches.

Platelets Apoptosis and Clearance in The Presence of Sodium Octanoate during Storage of Platelet Concentrate at 4˚C

Objective

Platelet (PLT) storage at 4˚C has several benefits, however, it is accompanied by increased clearance of PLTs after transfusion. In this study, we evaluated the potential of sodium octanoate (SO) for reducing apoptosis and clearance rate of PLTs after long-term storage in cold.

Materials and Methods

In this experimental study, PLT concentrates (PCs) were stored for 5 days under the following three conditions: 20-24˚C, 4˚C, and 4˚C in the presence of SO. To measure the viability of PLTs, the water-soluble tetrazolium salt (WST-1) assay was performed. Phosphatidylserine (PS) exposure was determined on PLTs using flow cytometry technique. The amount of human active caspase-3 was determined in PLTs using an enzyme-linked immunosorbent assay. Additionally, the amount of PLT ingestion or clearance was determined by using HepG2 cell line.

Results

The viability was higher in the SO-treated PLTs compared to the other groups. The level of PS exposure on PLTs was lower in the SO-treated PLTs compared to the other groups. The amount of active caspase-3 increased in all groups during 5-day storage. The highest increase in the amount of caspase-3 levels was observed at cold temperature. However, PLTs kept at 4˚C in the presence of SO had a lower amount of active caspase-3 compared to PLTs kept at 4˚C. The amount of PLTs removal by HepG2 cells was increased for 4˚C-kept PLTs but it was lower for PLTs kept at 4˚C in the presence of SO but, the differences were not significant (P>0.05).

Conclusion

SO could partially moderate the effects of cold temperature on apoptosis and viability of platelets. It also decreases the ingestion rate of long-time refrigerated PLTs in vitro. Further studies using higher numbers of samples are required to demonstrate the effect of SO on reducing the clearance rate of PLTs.

Targeting Tyrosine Phosphatases by 3-Bromopyruvate Overcomes Hyperactivation of Platelets from Gastrointestinal Cancer Patients

Venous thromboembolism (VTE) is one of the most common causes of cancer related mortality. It has been speculated that hypercoagulation in cancer patients is triggered by direct or indirect contact of platelets with tumor cells, however the underlying molecular mechanisms involved are currently unknown. Unraveling these mechanisms may provide potential avenues for preventing platelet-tumor cell aggregation. Here, we investigated the role of protein tyrosine phosphatases in the functionality of platelets in both healthy individuals and patients with gastrointestinal cancer, and determined their use as a target to inhibit platelet hyperactivity. This is the first study to demonstrate that platelet agonists selectively activate low molecular weight protein tyrosine phosphatase (LMWPTP) and PTP1B, resulting in activation of Src, a tyrosine kinase known to contribute to several platelet functions. Furthermore, we demonstrate that these phosphatases are a target for 3-bromopyruvate (3-BP), a lactic acid analog currently investigated for its use in the treatment of various metabolic tumors. Our data indicate that 3-BP reduces Src activity, platelet aggregation, expression of platelet activation makers and platelet-tumor cell interaction. Thus, in addition to its anti-carcinogenic effects, 3-BP may also be effective in preventing platelet-tumor cell aggregationin cancer patients and therefore may reduce cancer mortality by limiting VTE in patients.

Cold storage of platelets in additive solution: the impact of residual plasma in apheresis platelet concentrates

Platelet transfusion has become essential therapy in modern medicine. Although the clinical advantage of platelet transfusion has been well established, adverse reactions upon transfusion, especially transmission of bacterial infection, still represent a major challenge. While bacterial contamination is favored by the storage of platelets at room temperature, cold storage may represent a solution for this important clinical issue. In this study, we aimed to clarify whether plasma has protective or detrimental effects on cold-stored platelets. We investigated the impact of different residual plasma contents in apheresis-derived platelet concentrates, stored at 4°C or room temperature, on platelet function and survival. We found that platelets stored at 4°C have higher expression of apoptosis marker compared to platelets stored at room temperature, leading to accelerated clearance from the circulation in a humanized animal model. While cold-induced apoptosis was independent of the residual plasma concentration, cold storage was associated with better adhesive properties and higher response to activators. Interestingly, delta (δ) granule-related functions, such as ADP-mediated aggregation and CD63 release, were better preserved at 4°C, especially in 100% plasma. An extended study to assess cold-stored platelet concentrates produced under standard care Good Manufacturing Practice conditions showed that platelet function, metabolism and integrity were better compared to those stored at room temperature. Taken together, our results show that residual plasma concentration does not have a cardinal impact on the cold storage lesions of apheresis-derived platelet concentrates and indicate that the current generation of additive solutions represent suitable substitutes for plasma to store platelets at 4°C.

Mechanisms of platelet clearance and translation to improve platelet storage

Hundreds of billions of platelets are cleared daily from circulation via efficient and highly regulated mechanisms. These mechanisms may be stimulated by exogenous reagents or environmental changes to accelerate platelet clearance, leading to thrombocytopenia. The interplay between antiapoptotic Bcl-x_L and proapoptotic molecules Bax and Bak sets an internal clock for the platelet lifespan, and BH3-only proteins, mitochondrial permeabilization, and phosphatidylserine (PS) exposure may also contribute to apoptosis-induced platelet clearance. Binding of plasma von Willebrand factor or antibodies to the ligand-binding domain of glycoprotein Ibα (GPIbα) on platelets can activate GPIb-IX in a shear-dependent manner by inducing unfolding of the mechanosensory domain therein, and trigger downstream signaling in the platelet including desialylation and PS exposure. Deglycosylated platelets are recognized by the Ashwell-Morell receptor and potentially other scavenger receptors, and are rapidly cleared by hepatocytes and/or macrophages. Inhibitors of platelet clearance pathways, including inhibitors of GPIbα shedding, neuraminidases, and platelet signaling, are efficacious at preserving the viability of platelets during storage and improving their recovery and survival in vivo. Overall, common mechanisms of platelet clearance have begun to emerge, suggesting potential strategies to extend the shelf-life of platelets stored at room temperature or to enable refrigerated storage.

Bcl-xL/Bak interaction and regulation by miRNA let-7b in the intrinsic apoptotic pathway of stored platelets

Bcl-2 family proteins play key roles in the intrinsic apoptosis pathway in platelets, with both pro- and antiapoptotic protein expressions regulating survival during ex vivo storage. We detected a significant decrease in antiapoptotic Bcl-x_L and increase in proapoptotic Bak expression on the third day of storage and as a result the ratio of Bak:Bcl-x_L also decreased. Moreover, we identified an interaction between Bcl-x_L and Bak. These shifts corresponded with activation of the apoptotic pathway, suggesting these proteins might play an important role in platelet survival. We then performed bioinformatic analysis to gain insight into protein expression regulation during storage. This identified a potential binding site of the microRNA (miRNA) let-7b in the 3'-UTR of the Bcl-x_L gene, which we confirmed by a dual-luciferase reporter assay. We also determined that let-7b was upregulated during platelet storage, and let-7b transfection influenced Bcl-x_L and Bak protein, but not mRNA, expression. Together, these data suggest that only posttranscriptional mechanisms are available for regulating gene expression in anucleate platelets.

Lychee Seed Saponins Improve Cognitive Function and Prevent Neuronal Injury via Inhibiting Neuronal Apoptosis in a Rat Model of Alzheimer's Disease

Lychee seed is a traditional Chinese medicine and possesses many activities, including hypoglycemia, liver protection, antioxidation, antivirus, and antitumor. However, its effect on neuroprotection is still unclear. The present study investigated the effects of lychee seed saponins (LSS) on neuroprotection and associated mechanisms. We established a rat model of Alzheimer’s disease (AD) by injecting Aβ_25–35 into the lateral ventricle of rats and evaluated the effect of LSS on spatial learning and memory ability via the Morris water maze. Neuronal apoptosis was analyzed by hematoxylin and eosin stain and terminal deoxynucleotidyl transferase (Tdt)-mediated dUTP nick-end labeling analysis, and mRNA expression of caspase-3 and protein expressions of Bax and Bcl-2 by reverse transcription-polymerase chain reaction (RT-PCR) and Western blotting, respectively. The results showed that LSS remarkably improved cognitive function and alleviated neuronal injury by inhibiting apoptosis in the hippocampus of AD rats. Furthermore, the mRNA expression of caspase-3 and the protein expression of Bax were downregulated, while the protein expression of Bcl-2 and the ratio of Bcl-2/Bax were increased by LSS. We demonstrate that LSS significantly improves cognitive function and prevent neuronal injury in the AD rats via regulation of the apoptosis pathway. Therefore, LSS may be developed as a nutritional supplement and sold as a drug for AD prevention and/or treatment.

p38MAPK is involved in apoptosis development in apheresis platelet concentrates after riboflavin and ultraviolet light treatment

BACKGROUND

Pathogen inactivation (PI) accelerates the platelet (PLT) storage lesion, including apoptotic-like changes. Proteomic studies have shown that phosphorylation levels of several kinases increase in PLTs after riboflavin and UV light (RF-PI) treatment. Inhibition of p38MAPK improved in vitro PLT quality, but the biochemical basis of this kinase's contribution to PLT damage requires further analysis.

STUDY DESIGN AND METHODS

In a pool-and-split design, apheresis PLT concentrates were either treated or kept untreated with or without selected kinase inhibitors. Samples were analyzed throughout 7 days of storage, monitoring in vitro quality variables including phosphatidylserine exposure, degranulation, and glucose metabolism. Changes in the protein expression of Bax, Bak, and Bcl-xL and the activities of caspase-3 and -9 were determined by immunoblot analysis and flow cytometry, respectively.

RESULTS

The expression levels of the proapoptotic proteins Bax and Bak, but not the antiapoptotic protein Bcl-xL, were significantly increased after the RF-PI treatment. This trend was reversed in the presence of p38MAPK inhibitor SB203580. As a result of increasing proapoptotic protein levels, caspase-3 and -9 activities were significantly increased in RF-PI treatment during storage compared with control (p < 0.05). Similarly, p38MAPK inhibition significantly reduced these caspase activities compared with vehicle control after RF-PI treatment (p < 0.05).

CONCLUSION

These findings revealed that p38MAPK is involved in signaling leading to apoptosis triggered by RF-PI. Elucidation of the biochemical processes influenced by PI is a necessary step in the development of strategies to improve the PLT quality and ameliorate the negative effects of PI treatment.