Flipping the dogma - phosphatidylserine in non-apoptotic cell death

Application of biomaterials in the treatment of intracerebral hemorrhage

Although the current surgical hematoma removal treatment saves patients' lives in critical moments of intracerebral hemorrhage (ICH), the lethality and disability rates of ICH are still very high. Due to the individual differences of patients, postoperative functional improvement is still to be confirmed, and the existing drug treatment has limited benefits for ICH. Recent advances in biomaterials may provide new ideas for the therapy of ICH. This review first briefly describes the pathogenic mechanisms of ICH, including primary and secondary injuries such as inflammation and intracerebral edema, and briefly describes the existing therapeutic approaches and their limitations. Secondly, existing nanomaterials and hydrogels for ICH, including exosomes, liposomes, and polymer nanomaterials, are also described. In addition, the potential challenges and application prospects of these biomaterials for clinical translation in ICH treatment are discussed.

Photothermal induction of pyroptosis in malignant glioma spheroids using (16-mercaptohexadecyl)trimethylammonium bromide-modified cationic gold nanorods

Plasmonic photothermal therapy (PPTT) employing plasmonic gold nanorods (GNRs) presents a potent strategy for eradication of tumors including aggressive brain gliomas. Despite its promise, there is a pressing need for a more comprehensive evaluation of PPTT using sophisticated in vitro models that closely resemble tumor tissues, thereby facilitating the elucidation of therapeutic mechanisms. In this study, we exposed 3D glioma spheroids (tumoroids) to (16-mercaptohexadecyl)trimethylammonium bromide-functionalized gold nanorods (MTAB-GNRs) and a near-infrared (NIR) laser. We demonstrate that the photothermal effect can be fine-tuned by adjusting the nanoparticle concentration and laser power. Depending on the selected parameters, the laser can trigger either regulated or non-regulated cell death (necrosis) in both mouse GL261 and human U-87 MG glioma cell lines, accompanied by translocation of phosphatidylserine in the membrane. Our investigation into the mechanism of regulated cell death induced by PPTT revealed an absence of markers associated with classical apoptosis pathways, such as cleaved caspase 3. Instead, we observed the presence of cleaved caspase 1, gasdermin D, and elevated levels of NLRP3 in NIR-irradiated tumoroids, indicating the activation of pyroptosis. This finding correlates with previous observations of lysosomal accumulation of MTAB-GNRs and the known lysosomal pathway of pyroptosis activation. We further confirmed the absence of toxic breakdown products of GNRs using electron microscopy, which showed no melting or fragmentation of gold nanoparticles under the conditions causing regulated cell death. In conclusion, PPTT using coated gold nanorods offers significant potential for glioma cell elimination occurring through the activation of pyroptosis rather than classical apoptosis pathways.

Membrane-localized magnetic hyperthermia promotes intracellular delivery of cell-impermeant probes

In this work, we report the disruptive use of membrane-localized magnetic hyperthermia to promote the internalization of cell-impermeant probes. Under an alternating magnetic field, magnetic nanoparticles (MNPs) immobilized on the cell membrane via bioorthogonal click chemistry act as nanoheaters and lead to the thermal disruption of the plasma membrane, which can be used for internalization of different types of molecules, such as small fluorescent probes and nucleic acids. Noteworthily, no cell death, oxidative stress and alterations of the cell cycle are detected after the thermal stimulus, although cells are able to sense and respond to the thermal stimulus through the expression of different types of heat shock proteins (HSPs). Finally, we demonstrate the utility of this approach for the transfection of cells with a small interference RNA (siRNA), revealing a similar efficacy to a standard transfection method based on the use of cationic lipid-based reagents (such as Lipofectamine), but with lower cell toxicity. These results open the possibility of developing new procedures for "opening and closing" cellular membranes with minimal disturbance of cellular integrity. This on-demand modification of cell membrane permeability could allow the direct intracellular delivery of biologically relevant (bio)molecules, drugs and nanomaterials, thus overcoming traditional endocytosis pathways and avoiding endosomal entrapment.

Vallaris solanacea induces mitochondrial mediated apoptosis in HL-60 human promyelocytic leukemia cells

In the present study, the apoptosis-inducing potential of a chloroform fraction from an alcoholic extract of Vallaris solanacea aerial parts (VS) was examined using human promyelocytic leukemia HL-60 cells. We discovered a concentration and time-dependent decrease in cell growth using MTT assay. Scanning electron micrographs and fluorescence microscopy were used to observe several well-documented morphological and nuclear alterations, such as reduction in cell size, chromatin condensation, fragmentation, and the creation of cell surface blebs. A considerable rise in the Sub-G0 population was revealed by cell cycle analysis. Additionally, a dose-dependent rise in cells positive for Annexin V was observed. DCFH-DA test on VS-treated HL-60 cells showed an increase in endogenous ROS generation of up to 4.3 fold. Additionally, suppression in Bcl-2 levels and increased mitochondrial membrane depolarization in treated cells were also associated with a rise in cytosolic cytochrome-c levels that was consequently followed by the activation of the caspase cascade. Further, the DNA fragmentation assay exhibited a typical ladder formation at 25 μg/ml, which became prominent in a concentration-dependent manner. Our study revealed that VS has apoptosis-inducing potential towards HL-60 cells in vitro and is an effective candidate for further anti-cancer studies.

A Comparison of Common Quantum Dot Alternatives to Cadmium-Based Quantum Dots on the Basis of Liver Cytotoxicity

Fluorescent nanoparticles known as quantum dots (QDs) have unique properties that make them useful in biomedicine. Specifically, CdSe/ZnS QDs, while good at fluorescing, show toxicity. Due to this, safer alternatives have been developed. This study uses a tetrazolium dye (XTT) viability assay, reactive oxygen species (ROS) fluorescent imaging, and apoptosis to investigate the effect of QD alternatives InP/ZnS, CuInS2/ZnS, and nitrogen-doped carbon dots (NCDs) in liver cells. The liver is a possible destination for the accumulation of QDs, making it an appropriate model for testing. A cancerous liver cell line known as HepG2 and an immortalized liver cell line known as THLE-2 were used. At a nanomolar range of 10-150, HepG2 cells demonstrated no reduced cell viability after 24 h. The XTT viability assay demonstrated that CdSe/ZnS and CuInS2/ZnS show reduced cell viability in THLE-2 cells with concentrations between 50 and 150 nM. Furthermore, CdSe/ZnS- and CuInS2/ZnS-treated THLE-2 cells generated ROS as early as 6 h after treatment and elevated apoptosis after 24 h. To further corroborate our results, apoptosis assays revealed an increased percentage of cells in the early stages of apoptosis for CdSe/ZnS-treated (52%) and CuInS2/ZnS-treated (38%) THLE-2. RNA transcriptomics revealed heavy downregulation of cell adhesion pathways such as wnt, cadherin, and integrin in all QDs except NCDs. In conclusion, NCDs show the least toxicity toward these two liver cell lines. While demonstrating less toxicity than CdSe/ZnS, the metallic QDs (InP/ZnS and CuInS2/ZnS) still demonstrate potential concerns in liver cells. This study serves to explore the toxicity of QD alternatives and better understand their cellular interactions.

Hemocompatibility studies in nanotoxicology: Hemolysis or eryptosis? (A review)

Hemocompatibility evaluation is an important step in nanotoxicological studies. It is generally accepted that nanomaterials promote lysis of erythrocytes, blood clotting, alter phagocytosis, and upregulate pro-inflammatory cytokines. However, there are no standardized guidelines for testing nanomaterials hemocompatibility despite the fact that nanomaterials enter the bloodstream and interact with blood cells. In this review, the current knowledge on the ability of nanomaterials to induce distinct cell death modalities of erythrocytes is highlighted primarily focusing on hemolysis and eryptosis. This review aims to summarize the molecular mechanisms underlying erythrotoxicity of nanomaterials and critically compare the sensitivity and efficiency of hemolysis or eryptosis assays for nanomaterials blood compatibility testing. The list of eryptosis-inducing nanomaterials is growing, but it is still difficult to generalize how physico-chemical properties of nanoparticles affect eryptosis degree and molecular mechanisms involved. Thus, another aim of this review is to raise the awareness of eryptosis as a nanotoxicological tool to encourage the corresponding studies. It is worthwhile to consider adding eryptosis to in vitro nanomaterials hemocompatibility testing protocols and guidelines.

Phosphatidylserine and Tyro3-Axl-Mertk Receptor Tyrosine Kinase level detection in plasma and on plasma-derived extracellular vesicle surface in chronic lymphocytic leukemia

Chronic lymphocytic leukemia (CLL) is a chronic lymphoproliferative disorder characterized by monoclonal B cell proliferation. Studies carried out in recent years suggest that extracellular vesicles (EVs) may be a potential biomarker in cancer. Tyro3-Axl-Mertk (TAM) Receptor Tyrosine Kinases (RTKs) and Phosphatidylserine (PS) have crucial roles in macrophage-mediated immune response under normal conditions. In the tumor microenvironment, these molecules contribute to immunosuppressive signals and prevent the formation of local and systemic antitumor immune responses. Based on this, we aimed to evaluate the amount of PS and TAM RTK in plasma and on the surface of EVs in CLL patients and healthy volunteers in this study. In this study, 25 CLL (11 F/14 M) patients in the Rai (O-I) stage, newly diagnosed or followed up without treatment, and 15 healthy volunteers (11 F/4 M) as a control group were included. For all samples, PS and TAM RTK levels were examined first in the plasma and then in the EVs obtained from the plasma. We detected a significant decrease in plasma PS, and TAM RTK levels in CLL patients compared to the control. Besides, we determined a significant increase in TAM RTK levels on the EV surface in CLL, except for PS. In conclusion, these receptor levels measured by ELISA in plasma may not be effective for the preliminary detection of CLL. However, especially TAM RTKs on the surface of EVs may be good biomarkers and potential targets for CLL therapies.

MHC class I-dressing is mediated via phosphatidylserine recognition and is enhanced by polyI:C

In addition to cross-presentation, cross-dressing plays an important role in the induction of CD8+ T cell immunity. In the process of cross-dressing, conventional dendritic cells (DCs) acquire major histocompatibility complex class I (MHCI) from other cells and subsequently prime CD8+ T cells via the pre-formed antigen-MHCI complexes without antigen processing. However, the mechanisms underlying the cross-dressing pathway, as well as the relative contributions of cross-presentation and cross-dressing to CD8+ T cell priming are not fully understood. Here, we demonstrate that DCs rapidly acquire MHCI-containing membrane fragments from dead cells via the phosphatidylserine recognition-dependent mechanism for cross-dressing. The MHCI dressing is enhanced by a TLR3 ligand polyinosinic-polycytidylic acid (polyI:C). Further, polyI:C promotes not only cross-presentation but also cross-dressing in vivo. Taken together, these results suggest that cross-dressing as well as cross-presentation is involved in inflammatory diseases associated with cell death and type I IFN production.

Stain-Free Approach to Determine and Monitor Cell Heath Using Supervised and Unsupervised Image-Based Deep Learning

Cell-based medicinal products (CBMPs) are a growing class of therapeutics that promise new treatments for complex and rare diseases. Given the inherent complexity of the whole human cells comprising CBMPs, there is a need for robust and fast analytical methods for characterization, process monitoring, and quality control (QC) testing during their manufacture. Existing techniques to evaluate and monitor cell quality typically constitute labor-intensive, expensive, and highly specific staining assays. In this work, we combine image-based deep learning with flow imaging microscopy (FIM) to predict cell health metrics using cellular morphology "fingerprints" extracted from images of unstained Jurkat cells (immortalized human T-lymphocyte cells). A supervised (i.e., algorithm trained with human-generated labels for images) fingerprinting algorithm, trained on images of unstained healthy and dead cells, provides a robust stain-free, non-invasive, and non-destructive method for determining cell viability. Results from the stain-free method are in good agreement with traditional stain-based cytometric viability measurements. Additionally, when trained with images of healthy cells, dead cells and cells undergoing chemically induced apoptosis, the supervised fingerprinting algorithm is able to distinguish between the three cell states, and the results are independent of specific treatments or signaling pathways. We then show that an unsupervised variational autoencoder (VAE) algorithm trained on the same images, but without human-generated labels, is able to distinguish between samples of healthy, dead and apoptotic cells along with cellular debris based on learned morphological features and without human input. With this, we demonstrate that VAEs are a powerful exploratory technique that can be used as a process monitoring analytical tool.

A guide to the expanding field of extracellular vesicles and their release in regulated cell death programs

Homeostasis disruption is visible at the molecular and cellular levels and may often lead to cell death. This vital process allows us to maintain the more extensive system's integrity by keeping the different features (genetic, metabolic, physiologic, and individual) intact. Interestingly, while cells can die in different manners, dying cells still communicate with their environment. This communication was, for a long time, perceived as only driven by the release of soluble factors. However, it has now been reconsidered with the increasing interest in extracellular vesicles (EVs), which are discovered to be released during different regulated cell death programs, with the observation of specific effects. EVs are game changers in the paradigm of cell-cell communication with tremendous implications in fundamental research with regard to noncell autonomous functions, as well as in biomarkers research, all of which are geared toward diagnostic and therapeutic purposes. This review is composed of two main parts. The first is a comprehensive presentation of the state of the art of the EV field at large. In the second part, we focus on EVs discovered to be released during different regulated cell death programs, also known as cell death EVs (cdEVs), and EV-associated specific effects on recipient cells in the context of cell death and inflammation/inflammatory responses.

Role of extracellular vesicles in castration-resistant prostate cancer

Prostate cancer (PCa) is a common health threat to men worldwide, and castration-resistant PCa (CRPC) is the leading cause of PCa-related deaths. Extracellular vesicles (EVs) are lipid bilayer compartments secreted by living cells that are important mediators of intercellular communication. EVs regulate the biological processes of recipient cells by transmitting heterogeneous cargoes, contributing to CRPC occurrence, progression, and drug resistance. These EVs originate not only from malignant cells, but also from various cell types within the tumor microenvironment. EVs are widely dispersed throughout diverse biological fluids and are attractive biomarkers derived from noninvasive liquid biopsy techniques. EV quantities and cargoes have been tested as potential biomarkers for CRPC diagnosis, progression, drug resistance, and prognosis; however, technical barriers to their clinical application continue to exist. Furthermore, exogenous EVs may provide tools for new therapies for CRPC. This review summarizes the current evidence on the role of EVs in CRPC.

Programmed death of macrophages in atherosclerosis: mechanisms and therapeutic targets

Atherosclerosis is a progressive inflammatory disorder of the arterial vessel wall characterized by substantial infiltration of macrophages, which exert both favourable and detrimental functions. Early in atherogenesis, macrophages can clear cytotoxic lipoproteins and dead cells, preventing cytotoxicity. Efferocytosis - the efficient clearance of dead cells by macrophages - is crucial for preventing secondary necrosis and stimulating the release of anti-inflammatory cytokines. In addition, macrophages can promote tissue repair and proliferation of vascular smooth muscle cells, thereby increasing plaque stability. However, advanced atherosclerotic plaques contain large numbers of pro-inflammatory macrophages that secrete matrix-degrading enzymes, induce death in surrounding cells and contribute to plaque destabilization and rupture. Importantly, macrophages in the plaque can undergo apoptosis and several forms of regulated necrosis, including necroptosis, pyroptosis and ferroptosis. Regulated necrosis has an important role in the formation and expansion of the necrotic core during plaque progression, and several triggers for necrosis are present within atherosclerotic plaques. This Review focuses on the various forms of programmed macrophage death in atherosclerosis and the pharmacological interventions that target them as a potential means of stabilizing vulnerable plaques and improving the efficacy of currently available anti-atherosclerotic therapies.

Induction of autophagy-dependent and caspase- and microtubule-acetylation-independent cell death by phytochemical-stabilized gold nanopolygons in colorectal adenocarcinoma cells

Collective functionalization of the phytochemicals of medicinal herbs on nanoparticles is emerging as a potential cancer therapeutic strategy. This study presents the facile synthesis of surface-functionalized gold nanoparticles using Bacopa monnieri (Brahmi; Bm) phytochemicals and their therapeutically relevant mechanism of action in the colorectal cancer cell line, HT29. The nanoparticles were characterized using UV-visible spectroscopy, TEM-EDAX, zeta potential analysis, TGA, FTIR and 1H NMR spectroscopy, and HR-LC-MS. The particles (Bm-GNPs) were of polygonal shape and were stable against aggregation. They entered the target cells and inhibited the viability and clonogenicity of the cells with eight times more antiproliferative efficacy (25 ± 1.5 μg mL-1) than Bm extract (Bm-EX). In vitro studies revealed that Bm-GNPs bind tubulin (a protein crucial in cell division and a target of anticancer drugs) and disrupt its helical structure without grossly altering its tertiary conformation. Like other antitubulin agents, Bm-GNPs induced G2/M arrest and ultimately killed the cells, as confirmed using flow cytometry analyses. ZVAD-FMK-mediated global pan-caspase inhibition and the apparent absence of cleaved caspase-3 in treated cells indicated that the death did not involve the classic apoptosis pathway. Cellular ultrastructure analyses, western immunoblots, and in situ immunofluorescence visualization of cellular microtubules revealed microtubule-acetylation-independent induction of autophagy as the facilitator of cell death. Together, the data indicate strong antiproliferative efficacy and a possible mechanism of action for these designer nanoparticles. Bm-GNPs, therefore, merit further investigations, including preclinical evaluations, for their therapeutic potential as inducers of non-apoptotic cell death.

Phosphatidylserine externalization as immune checkpoint in cancer

Cancer is the second leading cause of mortality worldwide. Despite recent advances in cancer treatment including immunotherapy with immune checkpoint inhibitors, new unconventional biomarkers and targets for the detection, prognosis, and treatment of cancer are still in high demand. Tumor cells are characterized by mutations that allow their unlimited growth, program their local microenvironment to support tumor growth, and spread towards distant sites. While a major focus has been on altered tumor genomes and proteomes, crucial signaling molecules such as lipids have been underappreciated. One of these molecules is the membrane phospholipid phosphatidylserine (PS) that is usually found at cytosolic surfaces of cellular membranes but can be rapidly and massively shuttled to the extracellular leaflet of the plasma membrane during apoptosis to serve as a limiting factor for immune responses. These immunosuppressive interactions are exploited by tumor cells to evade the immune system. In this review, we describe mechanisms of immune regulation in tumors, discuss if PS may constitute an inhibitory immune checkpoint, and describe current and future strategies for targeting PS to reactivate the tumor-associated immune system.

Apoptosis and eryptosis: similarities and differences

Eryptosis is a regulated cell death (RCD) of mature erythrocytes initially described as a counterpart of apoptosis for enucleated cells. However, over the recent years, a growing number of studies have emphasized certain differences between both cell death modalities. In this review paper, we underline the hallmarks of eryptosis and apoptosis and highlight resemblances and dissimilarities between both RCDs. We summarize and critically discuss differences in the impact of caspase-3, Ca2+ signaling, ROS signaling pathways, opposing roles of casein kinase 1α, protein kinase C, Janus kinase 3, cyclin-dependent kinase 4, and AMP-activated protein kinase to highlight a certain degree of divergence between apoptosis and eryptosis. This review emphasizes the crucial importance of further studies that focus on deepening our knowledge of cell death machinery and identifying novel differences between cell death of nucleated and enucleated cells. This might provide evidence that erythrocytes can be defined as viable entities capable of programmed cell destruction. Additionally, the revealed cell type-specific patterns in cell death can facilitate the development of cell death-modulating therapeutic agents.

The cytotoxic effects of prazosin, chlorpromazine, and haloperidol on hepatocellular carcinoma and immortalized non-tumor liver cells

Liver cancer annually accounts for over 800,000 cases and 700,000 deaths worldwide. Hepatocellular carcinoma is responsible for over 80% of liver cancer cases. Due to ineffective treatment options and limited surgical interventions, hepatocellular carcinoma is notoriously difficult to treat. Nonetheless, drugs utilized for other medical conditions, such as the antihypertensive medication prazosin, the neuroleptic medication chlorpromazine, and the neuroleptic medication haloperidol, have gained attention for their potential anti-cancer effects. Therefore, this study used these medications for investigating toxicity to hepatocellular carcinoma while testing the adverse effects on a noncancerous liver cell line model THLE-2. After treatment, an XTT cell viability assay, cell apoptosis assay, reactive oxygen species (ROS) assay, apoptotic proteome profile, and western blot were performed. We calculated IC50 values for chlorpromazine and prazosin to have a molar range of 35-65 µM. Our main findings suggest the capability of both of these treatments to reduce cell viability and generate oxidative stress in HepG2 and THLE-2 cells (p value < 0.05). Haloperidol, however, failed to demonstrate any reduction in cell viability revealing no antitumor effect up to 100 µM. Based on our findings, a mechanism of cell death was not able to be established due to lack of cleaved caspase-3 expression. Capable of bypassing many aspects of the lengthy, costly, and difficult cancer drug approval process, chlorpromazine and prazosin deserve further investigation for use in conjunction with traditional chemotherapeutics.

Differential antiangiogenic and anticancer activities of the active metabolites of ginsenoside Rg3

Background

Epimers of ginsenoside Rg3 (Rg3) have a low bioavailability and are prone to deglycosylation, which produces epimers of ginsenoside Rh2 (S-Rh2 and R-Rh2) and protopanaxadiol (S-PPD and R-PPD). The aim of this study was to compare the efficacy and potency of these molecules as anti-cancer agents.

Methods

Crystal violet staining was used to study the anti-proliferatory action of the molecules on a human epithelial breast cancer cell line, MDA-MB-231, and human umbilical vein endothelial cells (HUVEC) and compare their potency. Cell death and cell cycle were studied using flow cytometry and mode of cell death was studied using live cell imaging. Anti-angiogenic effects of the drug were studied using loop formation assay. Molecular docking showed the interaction of these molecules with vascular endothelial growth factor receptor-2 (VEGFR2) and aquaporin (AQP) water channels. VEGF bioassay was used to study the interaction of Rh2 with VEGFR2, in vitro.

Results

HUVEC was the more sensitive cell line to the anti-proliferative effects of S-Rh2, S-PPD and R-PPD. The molecules induced necroptosis/necrosis in MDA-MB-231 and apoptosis in HUVEC. S-Rh2 was the most potent inhibitor of loop formation. In silico molecular docking predicted a good binding score between Rh2 or PPD and the ATP-binding pocket of VEGFR2. VEGF bioassay showed that Rh2 was an allosteric modulator of VEGFR2. In addition, SRh2 and PPD had good binding scores with AQP1 and AQP5, both of which play roles in cell migration and proliferation.

Conclusion

The combination of these molecules might be responsible for the anti-cancer effects observed by Rg3.

Cleaved caspase-3 is present in the majority of glial cells in the intact rat spinal cord during postnatal life

Cell death is an essential process that occurs during the development of the central nervous system. Despite the availability of a wide range of commercially produced antibodies against various apoptotic markers, data regarding apoptosis in intact spinal cord during postnatal development and adulthood are mostly missing. We investigated apoptosis in rat spinal cord at different stages of ontogenesis (postnatal days 8, 29, and 90). For this purpose, we applied immunofluorescent detection of two widely used apoptotic markers, cleaved caspase-3 (cC3) and cleaved poly(ADP-ribose) polymerase (cPARP). Surprisingly, we found significant discrepancy between the number of cC3+ cells and PARP+ cells, with a ratio between 500:1 and 5000:1 in rat spinal cord at all postnatal time points. The majority of cC3+ cells were glial cells and did not exhibit an apoptotic phenotype. In contrast with in vivo results, in vitro analysis of primary cell cultures derived from neonatal rat spinal cord and treated with the apoptotic inductor staurosporine revealed a similar onset of occurrence of both cC3 and cPARP in cells subjected to apoptosis. Gene expression analysis of spinal cord revealed elevated expression of the Birc4 (XIAP), Birc2, and Birc5 (Survivin) genes, which are known potent inhibitors of apoptosis. Our data indicate that cC3 is not an exclusive marker of apoptosis, especially in glial cells, owing its possible presence in inhibited forms and/or its participation in other non-apoptotic roles. Therefore, cPARP appears to be a more appropriate marker to detect apoptosis.

Apoptosis-mediated ADAM10 activation removes a mucin barrier promoting T cell efferocytosis

Efferocytic clearance of apoptotic cells in general, and T cells in particular, is required for tissue and immune homeostasis. Transmembrane mucins are extended glycoproteins highly expressed in the cell glycocalyx that function as a barrier to phagocytosis. Whether and how mucins may be regulated during cell death to facilitate efferocytic corpse clearance is not well understood. Here we show that normal and transformed human T cells express a subset of mucins which are rapidly and selectively removed from the cell surface during apoptosis. This process is mediated by the ADAM10 sheddase, the activity of which is associated with XKR8-catalyzed flipping of phosphatidylserine to the outer leaflet of the plasma membrane. Mucin clearance enhances uptake of apoptotic T cells by macrophages, confirming mucins as an enzymatically-modulatable barrier to efferocytosis. Together these findings demonstrate a glycocalyx regulatory pathway with implications for therapeutic intervention in the clearance of normal and transformed apoptotic T cells.

Laser-induced vapor nanobubbles for B16-F10 melanoma cell killing and intracellular delivery of chemotherapeutics

The most lethal form of skin cancer is cutaneous melanoma, a tumor that develops in the melanocytes, which are found in the epidermis. The treatment strategy of melanoma is dependent on the stage of the disease and often requires combined local and systemic treatment. Over the years, systemic treatment of melanoma has been revolutionized and shifted toward immunotherapeutic approaches. Phototherapies like photothermal therapy (PTT) have gained considerable attention in the field, mainly because of their straightforward applicability in melanoma skin cancer, combined with the fact that these strategies are able to induce immunogenic cell death (ICD), linked with a specific antitumor immune response. However, PTT comes with the risk of uncontrolled heating of the surrounding healthy tissue due to heat dissipation. Here, we used pulsed laser irradiation of endogenous melanin-containing melanosomes to induce cell killing of B16-F10 murine melanoma cells in a non-thermal manner. Pulsed laser irradiation of the B16-F10 cells resulted in the formation of water vapor nanobubbles (VNBs) around endogenous melanin-containing melanosomes, causing mechanical cell damage. We demonstrated that laser-induced VNBs are able to kill B16-F10 cells with high spatial resolution. When looking more deeply into the cell death mechanism, we found that a large part of the B16-F10 cells succumbed rapidly after pulsed laser irradiation, reaching maximum cell death already after 4 h. Practically all necrotic cells demonstrated exposure of phosphatidylserine on the plasma membrane and caspase-3/7 activity, indicative of regulated cell death. Furthermore, calreticulin, adenosine triphosphate (ATP) and high-mobility group box 1 (HMGB1), three key damage-associated molecular patterns (DAMPs) in ICD, were found to be exposed from B16-F10 cells upon pulsed laser irradiation to an extent that exceeded or was comparable to the bona fide ICD-inducer, doxorubicin. Finally, we could demonstrate that VNB formation from melanosomes induced plasma membrane permeabilization. This allowed for enhanced intracellular delivery of bleomycin, an ICD-inducing chemotherapeutic, which further boosted cell death with the potential to improve the systemic antitumor immune response.

Kaempferol induces apoptosis through the MAPK pathway and regulates JNK-mediated autophagy in MC-3 cells

This study sought to determine the anticancer effect of kaempferol, a glycone-type flavonoid glycoside with various pharmacological benefits, on human oral cancer MC-3 cells. In vitro studies comprised a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, annexin V and propidium iodide staining, western blotting analysis, and acridine orange staining, while the in vivo studies entailed a xenograft model, hematoxylin and eosin staining, and TdT-mediated dUTP-biotin nick end labelling. In vitro, kaempferol reduced the rate of survival of MC-3 cells, mediated intrinsic apoptosis, increased the number of acidic vesicular organelles, and altered the expression of autophagy-related proteins. Further, treatment with the autophagy inhibitors revealed that the induced autophagy had a cytoprotective effect on apoptosis in kaempferol-treated MC-3 cells. Kaempferol also decreased the expression of phosphorylated extracellular signal-regulated kinase and increased that of phosphorylated c-Jun N-terminal kinase (p-JNK) and phosphorylated p38 kinase in MC-3 cells, suggesting the occurrence of mitogen-activated protein kinase-mediated apoptosis and JNK-mediated autophagy. In vivo, kaempferol reduced tumor growth inducing apoptosis and autophagy. These results showed that kaempferol has the potential use as an adjunctive agent in treating oral cancer.

Ferroptosis of Endothelial Cells Triggered by Erythrophagocytosis Contributes to Thrombogenesis in Uremia

BACKGROUND

Although thrombosis events are the leading complication of uremia, their mechanism is largely unknown. The interaction between endothelial cells (ECs) and red blood cells (RBCs) in uremic solutes and its prothrombotic role need to be investigated.

METHODS AND RESULTS

Here, we established an in vitro co-incubation model of uremic RBC and EC as well as a uremic rat model induced by adenine. Using flow cytometry, confocal microscopy, and electron microscopy, we found increased erythrophagocytosis by EC accompanied by increased reactive oxygen species, lipid peroxidation, and impairment of mitochondria, indicating that ECs undergo ferroptosis. Further investigations showed increased proteins' expression of heme oxygenase-1 and ferritin and labile iron pool accumulation in EC, which could be suppressed by deferoxamine (DFO). The ferroptosis-negative regulators glutathione peroxidase 4 and SLC7A11 were decreased in our erythrophagocytosis model and could be enhanced by ferrostatin-1 or DFO. In vivo, we observed that vascular EC phagocytosed RBC and underwent ferroptosis in the kidney of the uremic rat, which could be inhibited by blocking the phagocytic pathway or inhibiting ferroptosis. Next, we found that the high tendency of thrombus formation was accompanied by erythrophagocytosis-induced ferroptosis in vitro and in vivo. Importantly, we further revealed that upregulated TMEM16F expression mediated phosphatidylserine externalization on ferroptotic EC, which contributed to a uremia-associated hypercoagulable state.

CONCLUSION

Our results indicate that erythrophagocytosis-triggered ferroptosis followed by phosphatidylserine exposure of EC may play a key role in uremic thrombotic complications, which may be a promising target to prevent thrombogenesis of uremia.

Ebola Virus Infection Induces HCAR2 Expression Leading to Cell Death

Ebola virus (EBOV) induces cell death not only in infected permissive cells but also in nonpermissive, bystander cells by employing different mechanisms. Hydroxycarboxylic acid receptor 2 (HCAR2) has been reported to be involved in apoptotic cell death. We previously reported an increase in the expression of HCAR2-specific mRNA in EBOV-infected individuals with fatal outcomes. Here, we report that infection with an EBOV lacking the VP30 gene (EBOVΔVP30) results in the upregulation of HCAR2 mRNA expression in human hepatocyte Huh7.0 cells stably expressing VP30. Transient overexpression of HCAR2 reduced the viability of Huh7.0 cells and human embryonic kidney cells. Phosphatidylserine externalization and cell membrane permeabilization by HCAR2 overexpression was also observed. Interestingly, coexpression of HCAR2 with EBOV VP40 further reduced cell viability in transfected cells compared to HCAR2 coexpression with other viral proteins. Our data suggest that HCAR2 may contribute to EBOV-induced cell death.

Large extracellular vesicles derived from human regulatory macrophages (L-EVMreg) attenuate CD3/CD28-induced T-cell activation in vitro

Macrophages belong to the innate immune system, and we have recently shown that in vitro differentiated human regulatory macrophages (Mreg) release large extracellular vesicles (L-EVMreg) with an average size of 7.5 μm which regulate wound healing and angiogenesis in vitro. The aim of this study was to investigate whether L-EVMreg also affect the CD3/CD28-mediated activation of T-cells. Mreg were differentiated using blood monocytes and L-EVMreg were isolated from culture supernatants by differential centrifugation. Activation of human T-cells was induced by CD3/CD28-coated beads in the absence or presence of Mreg or different concentrations of L-EVMreg. Inhibition of T-cell activation was quantified by flow cytometry and antibodies directed against the T-cell marker granzyme B. Phosphatidylserine (PS) exposure on the surface of Mreg and L-EVMreg was analyzed by fluorescence microscopy. Incubation of human lymphocytes with CD3/CD28 beads resulted in an increase of cell size, cell granularity, and number of granzyme B-positive cells (P < 0.05) which is indicative of T-cell activation. The presence of Mreg (0.5 × 106 Mreg/ml) led to a reduction of T-cell activation (number of granzyme B-positive cells; P < 0.001), and a similar but less pronounced effect was also observed when incubating activated T-cells with L-EVMreg (P < 0.05 for 3.2 × 106 L-EVMreg/ml). A differential analysis of the effects of Mreg and L-EVMreg on CD4+ and CD8+ T-cells showed an inhibition of CD4+ T-cells by Mreg (P < 0.01) and L-EVMreg (P < 0.05 for 1.6 × 106 L-EVMreg/ml; P < 0.01 for 3.2 × 106 L-EVMreg/ml). A moderate inhibition of CD8+ T-cells was observed by Mreg (P < 0.05) and by L-EVMreg (P < 0.01 for 1.6 × 106 L-EVMreg/ml and 3.2 × 106 L-EVMreg/ml). PS was restricted to confined regions of the Mreg surface, while L-EVMreg showed strong signals for PS in the exoplasmic leaflet. L-EVMreg attenuate CD3/CD28-mediated activation of CD4+ and CD8+ T-cells. L-EVMreg may have clinical relevance, particularly in the treatment of diseases associated with increased T-cell activity. KEY MESSAGES: Mreg release large extracellular vesicles (L-EVMreg) with an average size of 7.5 µm L-EVMreg exhibit phosphatidylserine positivity L-EVMreg suppress CD4+ and CD8+ T-cells L-EVMreg hold clinical potential in T-cell-related diseases.

Current trends in luminescence-based assessment of apoptosis

Apoptosis, the most extensively studied type of cell death, is known to play a crucial role in numerous processes such as elimination of unwanted cells or cellular debris, growth, control of the immune system, and prevention of malignancies. Defective regulation of apoptosis can trigger various diseases and disorders including cancer, neurological conditions, autoimmune diseases and developmental disorders. Knowing the nuances of the cell death type induced by a compound can help decipher which therapy is more effective for specific diseases. The detection of apoptotic cells using classic methods has brought significant contribution over the years, but innovative methods are quickly emerging and allow more in-depth understanding of the mechanisms, aside from a simple quantification. Due to increased sensitivity, time efficiency, pathway specificity and negligible cytotoxicity, these innovative approaches have great potential for both in vitro and in vivo studies. This review aims to shed light on the importance of developing and using novel nanoscale methods as an alternative to the classic apoptosis detection techniques.

Don't eat me/eat me signals as a novel strategy in cancer immunotherapy

Cancer stands as one of the prominent global causes of death, with its incidence burden continuously increasing, leading to a substantial rise in mortality rates. Cancer treatment has seen the development of various strategies, each carrying its drawbacks that can negatively impact the quality of life for cancer patients. The challenge remains significant within the medical field to establish a definitive cancer treatment that minimizes complications and limitations. In the forthcoming years, exploring new strategies to surmount the failures in cancer treatment appears to be an unavoidable pursuit. Among these strategies, immunology-based ones hold substantial promise in combatting cancer and immune-related disorders. A particular subset of this approach identifies "eat me" and "Don't eat me" signals in cancer cells, contrasting them with their counterparts in non-cancerous cells. This distinction could potentially mark a significant breakthrough in treating diverse cancers. By delving into signal transduction and engineering novel technologies that utilize distinct "eat me" and "Don't eat me" signals, a valuable avenue may emerge for advancing cancer treatment methodologies. Macrophages, functioning as vital components of the immune system, regulate metabolic equilibrium, manage inflammatory disorders, oversee fibrosis, and aid in the repair of injuries. However, in the context of tumor cells, the overexpression of "Don't eat me" signals like CD47, PD-L1, and beta-2 microglobulin (B2M), an anti-phagocytic subunit of the primary histocompatibility complex class I, enables these cells to evade macrophages and proliferate uncontrollably. Conversely, the presentation of an "eat me" signal, such as Phosphatidylserine (PS), along with alterations in charge and glycosylation patterns on the cellular surface, modifications in intercellular adhesion molecule-1 (ICAM-1) epitopes, and the exposure of Calreticulin and PS on the outer layer of the plasma membrane represent universally observed changes on the surface of apoptotic cells, preventing phagocytosis from causing harm to adjacent non-tumoral cells. The current review provides insight into how signaling pathways and immune cells either stimulate or obstruct these signals, aiming to address challenges that may arise in future immunotherapy research. A potential solution lies in combination therapies targeting the "eat me" and "Don't eat me" signals in conjunction with other targeted therapeutic approaches. This innovative strategy holds promise as a novel avenue for the future treatment of cancer.

Improving outcomes in intracerebral hemorrhage through microglia/macrophage-targeted IL-10 delivery with phosphatidylserine liposomes

Intracerebral hemorrhage (ICH) remains the most lethal type of stroke, and effective clinical therapies that can speed up hematoma resolution after ICH are still lacking. While the beneficial effects of IL-10 on ICH recovery have been demonstrated, the clinical translation of IL-10 requires effective delivery methods by which sufficient IL-10 can be delivered to ICH-affected regions in the brain. Here we report the use of a phosphatidylserine (PS) liposome (PSL)-based nanoparticle system for microglia/macrophage-targeted delivery of IL-10 in ICH. We first prepared IL-10-conjugated PSL (PSL-IL10) and characterized their immunomodulating effects in vitro. Then we evaluated the therapeutic effects, including hematoma absorption, short-term outcomes, and neuroinflammation, of intranasally administered PSL-IL10 (3 μg IL-10 per mouse, 2 h post-ICH) in a collagenase-induced ICH mouse model. We also isolated microglia/macrophages from the mouse brains with ICH to analyze their morphology, phagocytosis ability, and polarization. Our study reveals that, 1) PSL-IL10 treatment resulted in significantly improved outcomes and accelerated hematoma resolution in the acute phase of ICH; 2) PSL-IL10 inhibited glial activation and down-regulated pro-inflammatory cytokine production; 3) PSL-IL10 induced Iba1+ cells with a stronger phagocytosis ability; 4) PSL-IL10 activated STAT3 and upregulated CD36 expression in microglia/macrophage. These findings collectively show that PSL-IL10 is a promising nanotherapeutic for effectively ameliorating ICH.

Short-term assays for mesenchymal stromal cell immunosuppression of T-lymphocytes

Introduction

Trauma patients are susceptible to coagulopathy and dysfunctional immune responses. Mesenchymal stromal cells (MSCs) are at the forefront of the cellular therapy revolution with profound immunomodulatory, regenerative, and therapeutic potential. Routine assays to assess immunomodulation activity examine MSC effects on proliferation of peripheral blood mononuclear cells (PBMCs) and take 3-7 days. Assays that could be done in a shorter period of time would be beneficial to allow more rapid comparison of different MSC donors. The studies presented here focused on assays for MSC suppression of mitogen-stimulated PBMC activation in time frames of 24 h or less.

Methods

Three potential assays were examined-assays of apoptosis focusing on caspase activation, assays of phosphatidyl serine externalization (PS+) on PBMCs, and measurement of tumor necrosis factor alpha (TNFα) levels using rapid ELISA methods. All assays used the same initial experimental conditions: cryopreserved PBMCs from 8 to 10 pooled donors, co-culture with and without MSCs in 96-well plates, and PBMC stimulation with mitogen for 2-72 h.

Results

Suppression of caspase activity in activated PBMCs by incubation with MSCs was not robust and was only significant at times after 24 h. Monitoring PS+ of live CD3+ or live CD4+/CD3+ mitogen-activated PBMCs was dose dependent, reproducible, robust, and evident at the earliest time point taken, 2 h, although no increase in the percentage of PS+ cells was seen with time. The ability of MSC in co-culture to suppress PBMC PS+ externalization compared favorably to two concomitant assays for MSC co-culture suppression of PBMC proliferation, at 72 h by ATP assay, or at 96 h by fluorescently labeled protein signal dilution. TNFα release by mitogen-activated PBMCs was dose dependent, reproducible, robust, and evident at the earliest time point taken, with accumulating signal over time. However, suppression levels with MSC co-culture was reliably seen only after 24 h.

Discussion

Takeaways from these studies are as follows: (1) while early measures of PBMC activation is evident at 2-6 h, immunosuppression was only reliably detected at 24 h; (2) PS externalization at 24 h is a surrogate assay for MSC immunomodulation; and (3) rapid ELISA assay detection of TNFα release by PBMCs is a robust and sensitive assay for MSC immunomodulation at 24 h.

Cancer-Associated Gangliosides as a Therapeutic Target for Host Defense Peptide Mimics

Aberrant levels of glycolipids expressed on cellular surfaces are characteristic of different types of cancers. The oligomer of acylated lysine (OAK) mimicking antimicrobial peptides displays in vitro activity against human and murine melanoma cell lines with upregulated GD3 and GM3 gangliosides. Herein, we demonstrate the capability of OAK to intercalate into the sialo-oligosaccharides of DPPC/GD3 and DPPC/GM3 lipid monolayers using X-ray scattering. The lack of insertion into monolayers containing phosphatidylserine suggests that the mechanism of action by OAKs against glycosylated lipid membranes is not merely driven by charge effects. The fluorescence microscopy data demonstrates the membrane-lytic activity of OAK. Understanding the molecular basis for selectivity toward GD3 and GM3 gangliosides by antimicrobial lipopeptides will contribute to the development of novel therapies to cure melanoma and other malignancies.

Imaging of cell death in malignancy: Targeting pathways or phenotypes?

Cell death is fundamental in health and disease and resisting cell death is a hallmark of cancer. Treatment of malignancy aims to cause cancer cell death, however current clinical imaging of treatment response does not specifically image cancer cell death but assesses this indirectly either by changes in tumor size (using x-ray computed tomography) or metabolic activity (using 2-[18F]fluoro-2-deoxy-glucose positron emission tomography). The ability to directly image tumor cell death soon after commencement of therapy would enable personalised response adapted approaches to cancer treatment that is presently not possible with current imaging, which is in many circumstances neither sufficiently accurate nor timely. Several cell death pathways have now been identified and characterised that present multiple potential targets for imaging cell death including externalisation of phosphatidylserine and phosphatidylethanolamine, caspase activation and La autoantigen redistribution. However, targeting one specific cell death pathway carries the risk of not detecting cell death by other pathways and it is now understood that cancer treatment induces cell death by different and sometimes multiple pathways. An alternative approach is targeting the cell death phenotype that is "agnostic" of the death pathway. Cell death phenotypes that have been targeted for cell death imaging include loss of plasma membrane integrity and dissipation of the mitochondrial membrane potential. Targeting the cell death phenotype may have the advantage of being a more sensitive and generalisable approach to cancer cell death imaging. This review describes and summarises the approaches and radiopharmaceuticals investigated for imaging cell death by targeting cell death pathways or cell death phenotype.

Cannabidiol and Cannabigerol Modify the Composition and Physicochemical Properties of Keratinocyte Membranes Exposed to UVA

The action of UVA radiation (both that derived from solar radiation and that used in the treatment of skin diseases) modifies the function and composition of keratinocyte membranes. Therefore, this study aimed to assess the effects of phytocannabinoids (CBD and CBG), used singly and in combination, on the contents of phospholipids, ceramides, lipid rafts and sialic acid in keratinocyte membranes exposed to UVA radiation, together with their structure and functionality. The phytocannabinoids, especially in combination (CBD+CBG), partially prevented increased levels of phosphatidylinositols and sialic acid from occurring and sphingomyelinase activity after the UVA exposure of keratinocytes. This was accompanied by a reduction in the formation of lipid rafts and malondialdehyde, which correlated with the parameters responsible for the integrity and functionality of the keratinocyte membrane (membrane fluidity and permeability and the activity of transmembrane transporters), compared to UVA-irradiated cells. This suggests that the simultaneous use of two phytocannabinoids may have a protective effect on healthy cells, without significantly reducing the therapeutic effect of UV radiation used to treat skin diseases such as psoriasis.

Red Blood Cells and Endothelium Derived Circulating Extracellular Vesicles in Health and Chronic Heart Failure: A Focus on Phosphatidylserine Dynamics in Vesiculation

Circulating extracellular microvesicles (cEVs) are characterised by presenting surface antigens of parental cells. Since their biogenesis involves the translocation of phosphatidylserine (PS) from the inner to the outer leaflet of the plasma membrane, exposed PS has been considered as a recognition hallmark of cEVs. However, not all cEVs externalise PS. In this study, we have phenotypically and quantitatively characterised cEVs by flow cytometry, paying special attention to the proportions of PS in chronic heart failure patients (cHF; n = 119) and a reference non-HF group (n = 21). PS^--cEVs were predominantly found in both groups. Parental markers showed differential pattern depending on the PS exposure. Endothelium-derived and connexin 43-rich cEVs were mainly PS^--cEVs and significantly increased in cHF. On the contrary, platelet-derived cEVs were mostly PS⁺ and were increased in the non-HF group. We observed similar levels of PS⁺- and PS^--cEVs in non-HF subjects when analysing immune cell-derived Evs, but there was a subset-specific difference in cHF patients. Indeed, those cEVs carrying CD45⁺, CD29⁺, CD11b⁺, and CD15⁺ were mainly PS⁺-cEVs, while those carrying CD14⁺, CD3⁺, and CD56⁺ were mainly PS^--cEVs. In conclusion, endothelial and red blood cells are stressed in cHF patients, as detected by a high shedding of cEVs. Despite PS⁺-cEVs and PS^--cEVs representing two distinct cEV populations, their release and potential function as both biomarkers and shuttles for cell communication seem unrelated to their PS content.

Structural Characterization and Anticancer Activity of a New Anthraquinone from Senna velutina (Fabaceae)

In this study, a novel compound was isolated, identified, and its chemical structure was determined from the extract of the roots of Senna velutina. In addition, we sought to evaluate the anticancer potential of this molecule against melanoma and leukemic cell lines and identify the pathways of cell death involved. To this end, a novel anthraquinone was isolated from the barks of the roots of S. velutina, analyzed by HPLC-DAD, and its molecular structure was determined by nuclear magnetic resonance (NMR). Subsequently, their cytotoxic activity was evaluated by the (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) method against non-cancerous, melanoma, and leukemic cells. The migration of melanoma cells was evaluated by the scratch assay. The apoptosis process, caspase-3 activation, analysis of mitochondrial membrane potential, and measurement of ROS were evaluated by flow cytometry technique. In addition, the pharmacological cell death inhibitors NEC-1, RIP-1, BAPTA, Z-VAD, and Z-DEVD were used to confirm the related cell death mechanisms. With the results, it was possible to elucidate the novel compound characterized as 2'-OH-Torosaol I. In normal cells, the compound showed no cytotoxicity in PBMC but reduced the cell viability of all melanoma and leukemic cell lines evaluated. 2'-OH-Torosaol I inhibited chemotaxis of B16F10-Nex2, SK-Mel-19, SK-Mel-28 and SK-Mel-103. The cytotoxicity of the compound was induced by apoptosis via the intrinsic pathway with reduced mitochondrial membrane potential, increased levels of reactive oxygen species, and activation of caspase-3. In addition, the inhibitors demonstrated the involvement of necroptosis and Ca²⁺ in the death process and confirmed caspase-dependent apoptosis death as one of the main programmed cell death pathways induced by 2'-OH-Torosaol I. Taken together, the data characterize the novel anthraquinone 2'-OH-Torosaol I, demonstrating its anticancer activity and potential application in cancer therapy.

Pyrazolo[4,3-e]tetrazolo[1,5-b][1,2,4]triazine Sulfonamides as an Important Scaffold for Anticancer Drug Discovery-In Vitro and In Silico Evaluation

Pyrazolo[4,3-e]tetrazolo[1,5-b][1,2,4]triazine sulfonamides (MM-compounds) are a relatively new class of heterocyclic compounds that exhibit a wide variety of biological actions, including anticancer properties. Here, we used caspase enzyme activity assays, flow cytometry analysis of propidium iodide (PI)-stained cells, and a DNA laddering assay to investigate the mechanisms of cell death triggered by the MM-compounds (MM134, -6, -7, and -9). Due to inconsistent results in caspase activity assays, we have performed a bromodeoxyuridine (BrdU) incorporation assay, colony formation assay, and gene expression profiling. The compounds' cytotoxic and pro-oxidative properties were also assessed. Additionally, computational studies were performed to demonstrate the potential of the scaffold for future drug discovery endeavors. MM-compounds exhibited strong micromolar (0.06-0.35 µM) anti-proliferative and pro-oxidative activity in two cancer cell lines (BxPC-3 and PC-3). Activation of caspase 3/7 was observed following a 24-h treatment of BxPC-3 cells with IC₅₀ concentrations of MM134, -6, and -9 compounds. However, no DNA fragmentation characteristics for apoptosis were observed in the flow cytometry and DNA laddering analysis. Gene expression data indicated up-regulation of BCL10, GADD45A, RIPK2, TNF, TNFRSF10B, and TNFRSF1A (TNF-R1) following treatment of cells with the MM134 compound. Moreover, in silico studies indicated AKT2 kinase as the primary target of compounds. MM-compounds exhibit strong cytotoxic activity with pro-oxidative, pro-apoptotic, and possibly pro-necroptotic properties that could be employed for further drug discovery approaches.

Polydopamine conjugated SiO2 nanoparticles as potential drug carriers for melanoma treatment

Silica nanoparticles (SiO₂) are increasingly investigated for biomedical applications. Aim: This study aimed to analyze the potential use of a SiO₂ nanoparticles coated with biocompatible polydopamine (SiO₂@PDA) as a potential chemotherapeutic drug carrier. Materials & methods: SiO₂ morphology and PDA adhesion was analyzed by dynamic light scattering, electron microscopy and nuclear magnetic resonance. Cytotoxicity studies and morphology analyses (immunofluorescence, scanning and transmission electron microscopy) were used to assess the cellular reaction to the SiO₂@PDA nanoparticles and to identify a biocompatible (safe use) window. Results & conclusion: Concentrations above 10 μg/ml and up to 100 μg/ml SiO₂@PDA showed the best biocompatibility on human melanoma cells at 24 h and represent a potential drug carrier template for targeted melanoma cancer treatment.

Multiple Forms of Neural Cell Death in the Cyclical Brain Degeneration of A Colonial Chordate

Human neuronal loss occurs through different cellular mechanisms, mainly studied in vitro. Here, we characterized neuronal death in B. schlosseri, a marine colonial tunicate that shares substantial genomic homology with mammals and has a life history in which controlled neurodegeneration happens simultaneously in the brains of adult zooids during a cyclical phase named takeover. Using an ultrastructural and transcriptomic approach, we described neuronal death forms in adult zooids before and during the takeover phase while comparing adult zooids in takeover with their buds where brains are refining their structure. At takeover, we found in neurons clear morphologic signs of apoptosis (i.e., chromatin condensation, lobed nuclei), necrosis (swollen cytoplasm) and autophagy (autophagosomes, autolysosomes and degradative multilamellar bodies). These results were confirmed by transcriptomic analyses that highlighted the specific genes involved in these cell death pathways. Moreover, the presence of tubulovesicular structures in the brain medulla alongside the over-expression of prion disease genes in late cycle suggested a cell-to-cell, prion-like propagation recalling the conformational disorders typical of some human neurodegenerative diseases. We suggest that improved understanding of how neuronal alterations are regulated in the repeated degeneration-regeneration program of B. schlosseri may yield mechanistic insights relevant to the study of human neurodegenerative diseases.

Novel Insights in the Potential of Halogenated Polyketide–Peptide Molecules as Lead Compounds in Cancer Drug Discovery

In this interdisciplinary study, we selected two compounds, namely, smenamide A, a peptide–polyketide, and smenolactone D, a polyketide, as models because they are representative of two different classes of molecules isolated from the marine sponge Smenospongia aurea. The organic extract of Smenospongia aurea was analyzed using a combination of high-resolution LC-MS/MS and molecular networking, a recently developed method for automated LC-MS data analysis. The analyses were targeted to highlight clusters made by chlorinated compounds present in the extracts. Then, the two model compounds were analyzed for their bioactivity. Data reported here show that smenamide A did not exhibit a cytotoxic effect, while smenolactone D was cytotoxic on different tumor cell lines and was able to induce different types of cell death, including ferroptosis and apoptosis.

Cigarette smoke depletes alveolar macrophages and delays clearance of Legionella pneumophila

Legionella pneumophila is the main etiological agent of Legionnaires' disease, a severe bacterial pneumonia. L. pneumophila is initially engulfed by alveolar macrophages (AMs) and subvert normal cellular functions to establish a replicative vacuole. Cigarette smokers are particularly susceptible to developing Legionnaires' disease and other pulmonary infections; however, little is known about the cellular mechanisms underlying this susceptibility. To investigate this, we used a mouse model of acute cigarette smoke exposure to examine the immune response to cigarette smoke and subsequent L. pneumophila infection. Contrary to previous reports, we show that cigarette smoke exposure alone causes a significant depletion of AMs using enzymatic digestion to extract cells, or via imaging intact lung lobes by light-sheet microscopy. Furthermore, treatment of mice deficient in specific types of cell death with smoke suggests that NLRP3-driven pyroptosis is a contributor to smoke-induced death of AMs. After infection, smoke-exposed mice displayed increased pulmonary L. pneumophila loads and developed more severe disease compared with air-exposed controls. We tested if depletion of AMs was related to this phenotype by directly depleting them with clodronate liposomes and found that this also resulted in increased L. pneumophila loads. In summary, our results showed that cigarette smoke depleted AMs from the lung and that this likely contributed to more severe Legionnaires' disease. Furthermore, the role of AMs in L. pneumophila infection is more nuanced than simply providing a replicative niche, and our studies suggest they play a major role in bacterial clearance.

Granulosa cells undergo BPA-induced apoptosis in a miR-21-independent manner

Bisphenol A (BPA) is a harmful endocrine disrupting compound that alters not only classical cellular mechanisms but also epigenetic mechanisms. Evidence suggests that BPA-induced changes in microRNA expression can explain, in part, the changes observed at both the molecular and cellular levels. BPA is toxic to granulosa cells (GCs) as it can activate apoptosis, which is known to contribute to increased follicular atresia. miR-21 is a crucial antiapoptotic regulator in GCs, yet the exact function in a BPA toxicity model remains unclear. BPA was found to induce bovine GC apoptosis through the activation of several intrinsic factors. BPA reduced live cells counts, increased late apoptosis/necrosis, increased apoptotic transcripts (BAX, BAD, BCL-2, CASP-9, HSP70), increased the BAX/Bcl-2 ratio and HSP70 at the protein level, and induced caspase-9 activity at 12 h post-exposure. miR-21 inhibition increased early apoptosis and, while it did not influence transcript levels or caspase-9 activity, it did elevate the BAX/Bcl-2 protein ratio and HSP70 in the same manner as BPA. Overall, this study shows that miR-21 plays a molecular role in regulating intrinsic mitochondrial apoptosis; however, miR-21 inhibition did not make the cells more sensitive to BPA. Therefore, apoptosis induced by BPA in bovine GCs is miR-21 independent.

Electric Fields Regulate In Vitro Surface Phosphatidylserine Exposure of Cancer Cells via a Calcium-Dependent Pathway

Cancer is the second leading cause of death worldwide after heart disease. The current treatment options to fight cancer are limited, and there is a critical need for better treatment strategies. During the last several decades, several electric field (EF)-based approaches for anti-cancer therapies have been introduced, such as electroporation and tumor-treating fields; still, they are far from optimal due to their invasive nature, limited efficacy and significant side effects. In this study, we developed a non-contact EF stimulation system to investigate the in vitro effects of a novel EF modality on cancer biomarkers in normal (human astrocytes, human pancreatic ductal epithelial -HDPE-cells) and cancer cell lines (glioblastoma U87-GBM, human pancreatic cancer cfPac-1, and MiaPaCa-2). Our results demonstrate that this EF modality can successfully modulate an important cancer cell biomarker-cell surface phosphatidylserine (PS). Our results further suggest that moderate, but not low, amplitude EF induces p38 mitogen-activated protein kinase (MAPK), actin polymerization, and cell cycle arrest in cancer cell lines. Based on our results, we propose a mechanism for EF-mediated PS exposure in cancer cells, where the magnitude of induced EF on the cell surface can differentially regulate intracellular calcium (Ca²⁺) levels, thereby modulating surface PS exposure.

Tyrosine kinase inhibitors can activate the NLRP3 inflammasome in myeloid cells through lysosomal damage and cell lysis

Inflammasomes are intracellular protein complexes that promote an inflammatory host defense in response to pathogens and damaged or neoplastic tissues and are implicated in inflammatory disorders and therapeutic-induced toxicity. We investigated the mechanisms of activation for inflammasomes nucleated by NOD-like receptor (NLR) protiens. A screen of a small-molecule library revealed that several tyrosine kinase inhibitors (TKIs)-including those that are clinically approved (such as imatinib and crizotinib) or are in clinical trials (such as masitinib)-activated the NLRP3 inflammasome. Furthermore, imatinib and masitinib caused lysosomal swelling and damage independently of their kinase target, leading to cathepsin-mediated destabilization of myeloid cell membranes and, ultimately, cell lysis that was accompanied by potassium (K⁺) efflux, which activated NLRP3. This effect was specific to primary myeloid cells (such as peripheral blood mononuclear cells and mouse bone marrow-derived dendritic cells) and did not occur in other primary cell types or various cell lines. TKI-induced lytic cell death and NLRP3 activation, but not lysosomal damage, were prevented by stabilizing cell membranes. Our findings reveal a potential immunological off-target of some TKIs that may contribute to their clinical efficacy or to their adverse effects.

Antibacterial Mode of Action of β-Amyrin Promotes Apoptosis-Like Death in Escherichia coli by Producing Reactive Oxygen Species

β-Amyrin is a pentacyclic triterpene widely distributed in leaves and stems worldwide. The ability of β-amyrin to induce the production of reactive oxygen species (ROS) in microorganisms suggests its potential as an antimicrobial agent. Thus, this study aimed to elucidate the antibacterial mode of action of β-amyrin. We treated Escherichia coli cells with β-amyrin and found that it triggered ROS accumulation. Excessive stress caused by ROS, particularly hydroxyl radicals, induces glutathione (GSH) dysfunction. GSH protects cells from oxidative and osmotic stresses; thus, its dysfunction leads to membrane depolarization. The resultant change in membrane potential leads to the release of apoptotic proteins, such as caspases. The activated caspases-like protein promotes the cleavage of DNA into single strands, which is a hallmark of apoptosis-like death in bacteria. Apoptotic cells usually undergo events such as DNA fragmentation and phosphatidylserine exposure, differentiating them from necrotic cells, and the cells treated with β-amyrin in this study were positive for annexin V and negative for propidium iodide, indicating apoptosis-like death. In conclusion, our findings suggest that the antibacterial mode of action of β-amyrin involves the induction of ROS, which resulted in apoptosis-like death in E. coli.

Mechanisms of Myofibre Death in Muscular Dystrophies: The Emergence of the Regulated Forms of Necrosis in Myology

Myofibre necrosis is a central pathogenic process in muscular dystrophies (MD). As post-lesional regeneration cannot fully compensate for chronic myofibre loss, interstitial tissue accumulates and impairs muscle function. Muscle regeneration has been extensively studied over the last decades, however, the pathway(s) controlling muscle necrosis remains largely unknown. The recent discovery of several regulated cell death (RCD) pathways with necrotic morphology challenged the dogma of necrosis as an uncontrolled process, opening interesting perspectives for many degenerative disorders. In this review, we focus on how cell death affects myofibres in MDs, integrating the latest research in the cell death field, with specific emphasis on Duchenne muscular dystrophy, the best-known and most common hereditary MD. The role of regulated forms of necrosis in myology is still in its infancy but there is increasing evidence that necroptosis, a genetically programmed form of necrosis, is involved in muscle degenerating disorders. The existence of apoptosis in myofibre demise will be questioned, while other forms of non-apoptotic RCDs may also have a role in myonecrosis, illustrating the complexity and possibly the heterogeneity of the cell death pathways in muscle degenerating conditions.

Novel Platinum(II) and Platinum(IV) Antitumor Agents that Exhibit Potent Cytotoxicity and Selectivity

A novel platinum(II) complex 47OMESS(II) and its platinum(IV) derivative 47OMESS(IV) were synthesized and characterized. Cytotoxicity studies against mesenchymal cells (MCs) and lung (A549), breast (MDA-MB-231), and melanoma (A375) cancer cells demonstrated 7-20-fold superior activity for both complexes relative to cisplatin. Remarkably, 47OMESS(IV) demonstrated 17-22-fold greater selectivity toward the cancerous cells compared to the non-cancerous MCs. Western blot analysis on A549 cells showed the involvement of the intrinsic apoptotic pathway. Cellular fractionation and uptake experiments in A549 cells using ICP-mass spectrometry (MS) indicated that 47OMESS(II) and 47OMESS(IV) cross the cellular membrane predominantly via active transport mechanisms. The significant improvement in selectivity that is exhibited by 47OMESS(IV) is reported for the first time for this class of complexes.

U5 snRNP Core Proteins Are Key Components of the Defense Response against Viral Infection through Their Roles in Programmed Cell Death and Interferon Induction

The spliceosome is a massive ribonucleoprotein structure composed of five small nuclear ribonucleoprotein (snRNP) complexes that catalyze the removal of introns from pre-mature RNA during constitutive and alternative splicing. EFTUD2, PRPF8, and SNRNP200 are core components of the U5 snRNP, which is crucial for spliceosome function as it coordinates and performs the last steps of the splicing reaction. Several studies have demonstrated U5 snRNP proteins as targeted during viral infection, with a limited understanding of their involvement in virus-host interactions. In the present study, we deciphered the respective impact of EFTUD2, PRPF8, and SNRNP200 on viral replication using mammalian reovirus as a model. Using a combination of RNA silencing, real-time cell analysis, cell death and viral replication assays, we discovered distinct and partially overlapping novel roles for EFTUD2, PRPF8, and SNRNP200 in cell survival, apoptosis, necroptosis, and the induction of the interferon response pathway. For instance, we demonstrated that EFTUD2 and SNRNP200 are required for both apoptosis and necroptosis, whereas EFTUD2 and PRPF8 are required for optimal interferon response against viral infection. Moreover, we demonstrated that EFTUD2 restricts viral replication, both in a single cycle and multiple cycles of viral replication. Altogether, these results establish U5 snRNP core components as key elements of the cellular antiviral response.

Endoplasmic Reticulum Stress Signaling and Neuronal Cell Death

Besides protein processing, the endoplasmic reticulum (ER) has several other functions such as lipid synthesis, the transfer of molecules to other cellular compartments, and the regulation of Ca²⁺ homeostasis. Before leaving the organelle, proteins must be folded and post-translationally modified. Protein folding and revision require molecular chaperones and a favorable ER environment. When in stressful situations, ER luminal conditions or chaperone capacity are altered, and the cell activates signaling cascades to restore a favorable folding environment triggering the so-called unfolded protein response (UPR) that can lead to autophagy to preserve cell integrity. However, when the UPR is disrupted or insufficient, cell death occurs. This review examines the links between UPR signaling, cell-protective responses, and death following ER stress with a particular focus on those mechanisms that operate in neurons.

Methodological advances in necroptosis research: from challenges to solutions

Necroptosis is currently attracting the attention of the scientific community for its broad implications in inflammatory diseases and cancer. However, detecting ongoing necroptosis in vivo under both experimental and clinical disease conditions remains challenging. The technical barrier lies in four aspects, namely tissue sampling, real-time in vivo monitoring, specific markers, and distinction between different types of cell death. In this review, we presented the latest methodological advances for in vivo necroptosis identification. The advances highlighted the multi-parameter flow cytometry, sA5-YFP tool, radiolabeled Annexin V/Duramycin, Gallium-68-labeled IRDye800CW contrast agent, and SMART platform in vivo. We also discussed the up-to-date research models in studying necroptosis, particularly the mice models for manipulating and monitoring necroptosis. Based on these recent advances, this review aims to provide some advice on current necroptosis techniques and approaches.

Co-Treatment of Caco-2 Cells with Doxorubicin and Gold Nanoparticles Produced from Cyclopia intermedia Extracts or Mangiferin Enhances Drug Effects

Mangiferin (MGF) is a natural and valuable polyphenol found in significant levels in many plant species, including Cyclopia intermedia (C. intermedia). In a previous study, we synthesized gold nanoparticles (AuNPs) using MGF and a water extract of C. intermedia and reported that these AuNPs have very low cytotoxicity toward a human colon cancer (Caco-2) cell line. Although the study also showed that these biogenic AuNPs in combination with doxorubic (DOX) significantly augmented the cytotoxic effects of DOX in Caco-2 cells, the mechanism of the enhanced effect was not fully understood, and it was also not known if other cell lines would be sensitive to this co-treatment. In the present study, we examined the cytotoxicity of the co-treatment in Caski, HeLa, HT-29, KMST-6 and MDA-321 cell lines. Additionally, we investigated the mechanistic effects of this co-treatment in Caco-2 cells using several assays, including the adenosine triphosphate (ATP), the oxidative stress, the mitochondrial depolarization, the colony formation, the APOPercentage and the DNA fragmentation assays. We also assessed the intracellular uptake of the biogenic AuNPs. The study showed that the biogenic AuNPs were effectively taken up by the cancer cells, which, in turn, may have enhanced the sensitivity of Caco-2 cells to DOX. Moreover, the combination of the biogenic AuNPs and DOX caused a rapid depletion of ATP levels, increased mitochondrial depolarization, induced apoptosis, reduced the production of reactive oxygen species (ROS) and inhibited the long-term survival of Caco-2 cells. Although the study provided some insight into the mechanism of cytotoxicity induced by the co-treatment, further mechanistic and molecular studies are required to fully elucidate the enhanced anticancer effect of the co-treatment.