Gamma irradiation induces a pro-apoptotic state in longer stored platelets, without progressing to an overt apoptosis by day 7 of storage

BACKGROUND

Although gamma-irradiation to platelet products is a standard method to prevent the risk of TA-GVHD in vulnerable recipients, it induces some proteomic and redox changes, of which irradiation-induced ROS increments may potentiate platelet mitochondrial dysfunction. However, whether these changes cause platelet apoptosis, or affect their viability during storage, is the main subject of this study.

METHODS

PLT-rich plasma PC was split into two bags, one kept as control while other was subjected to gamma-irradiation. Within 7-days storage, cytosolic and mitochondrial levels of cytochrome c and pro-apoptotic molecules of Bak and Bax were evaluated by western-blotting. Intraplatelet active caspase (using FAM-DEVD-FMK) and PS-exposure were detected by flowcytometry. Caspase activity in platelet lysate was also confirmed by immunofluorescence detection of Caspase-3/7 Substrate N-Ac-DEVD-N'-MC-R110 while platelet viability was evaluated with MTT assays.

RESULTS

Cytosolic cytochrome c gradually increased while its mitochondrial content steadily declined during 7 days of storage. In a contrary trend, reverse patterns were observed for Bak and Bax expressions. Gamma-irradiated platelets showed higher release of mitochondrial cytochrome c that reflected by higher cytosolic cytochrome c levels on day 7 of storage. Concurrently mitochondrial pro-apoptotic Bak and Bax proteins increased on day 7 in irradiated products. However, gamma-irradiation didn't significantly increase caspase activity or PS-exposure, nor did it decrease platelet viability.

CONCLUSION

Here, consistent with studies on "gamma-irradiation-induced oxidative stress", we showed that gamma-ray also increases platelet pro-apoptotic signals during storage, although not strongly enough to affect platelet viability by overt apoptosis induction. Conclusively, whether supplementing ROS scavengers or antioxidants to irradiated platelets can improve their quality during storage may be of interest for future research.

Rosmarinic acid decreases viability, inhibits migration and modulates expression of apoptosis-related CASP8/CASP3/NLRP3 genes in human metastatic melanoma cells

Cutaneous melanoma is the most aggressive type of skin cancer; it is difficult to treat, and has been highlighted in recent years due to increasing numbers of cases worldwide. The use of antitumoral therapeutics for this neoplasm has been associated with severe side effects, low quality of life, and resistance. We aimed in this study to explore the effect of the phenolic compound rosmarinic acid (RA) on human metastatic melanoma cells. SK-MEL-28 melanoma cells were treated for 24 h with different concentrations of RA. In parallel, peripheral blood mononuclear cells (PBMCs) also were treated with RA under the same experimental conditions to verify the cytotoxic effect on non-tumoral cells. Then, we assessed cell viability and migration, levels of intracellular and extracellular reactive oxygen species (ROS), as well as nitric oxide (NOx), non-protein thiols (NPSH), and total thiol (PSH). Gene expression of the caspase 8, caspase 3 and NLRP3 inflammasome was evaluated by RT-qPCR. The enzymatic activity of the caspase 3 protein was assessed by a sensitive fluorescent assay. Fluorescence microscopy was employed to corroborate the effects of RA on melanoma cell viability, mitochondria transmembrane potential and apoptotic bodies formation. We found that RA potently reduces melanoma cell viability and migration after 24 h of treatment. On the other hand, it has no cytotoxic effect on non-tumoral cells. The fluorescence micrographics indicated that RA reduces transmembrane potential of mitochondria and induces apoptotic bodies formation. Moreover, RA significantly decreases intracellular and extracellular ROS levels, and increases the antioxidant defenders NPSH and PSH. A remarkable feature found in our study was that RA strongly upregulates the gene expression of the caspase 8 and caspase 3, and downregulates NLRP3 inflammasome expression. Similar to gene expression, RA greatly increases the enzymatic activity of caspase 3 protein. Taken together, we have shown for the first time that RA reduces cell viability and migration of human metastatic melanoma cells, in addition to modulates apoptosis-related gene expression. We suggest that RA may have the potential to be used in a therapeutic perspective, particularly for CM cell treatment.

Higher replication potential of West Nile virus governs apoptosis induction in human neuroblastoma cells

The extent of neuronal cell damage caused by West Nile virus (WNV) infection governs the disease severity ranging from mild, febrile illness to fatal encephalitis. Availability of naturally occurring genetic variants is helpful to study viral factors governing differential pathogenesis. During WNV infection, apoptosis serves as a virulence determinant positively contributing to viral pathogenesis. We investigated the levels of apoptosis induced by a low neurovirulent WNV lineage 5 strain 804994 and a high neurovirulent lineage 1 strain 68856 in human neuroblastoma cells, IMR-32. Our investigations clearly show the correlation between higher multiplication capacities of 68856 with higher levels of cytopathology induced by apoptosis. We observed activation of both the extrinsic and intrinsic apoptotic pathways during WNV infection. Infection with higher neurovirulent strain resulted in higher upregulation of pro-apoptotic proteins including death receptors (DR), adaptor protein, BH3-only regulatory proteins and higher cleavage of initiator caspases of both pathways. These results suggest that the virulence of a WNV strain may correlate with its higher replication fitness and ability to cause more cellular damage.

Allosteric Tuning of Caspase-7: Establishing the Nexus of Structure and Catalytic Power

Caspase-7 (C7), a cysteine protease involved in apoptosis, is a valuable drug target for its role in human diseases (e.g. Parkinson's, Alzheimer's, sepsis). The C7 allosteric site has great potential for small molecule targeting, but numerous drug discovery efforts have identified precious few allosteric inhibitors. Here we present the first selective, drug-like inhibitor of C7 along with several other improved inhibitors based on our previous fragment hit. We also provide a rational basis for the impact of allosteric binding on the C7 catalytic cycle using an integrated approach including X-ray crystallography, stopped-flow kinetics, and molecular dynamics simulations. Our findings suggest allosteric binding disrupts C7 pre-acylation via neutralization of the catalytic dyad, displacement of substrate from the oxyanion hole, and altered dynamics of substrate binding loops. This work advances drug targeting efforts and bolsters our understanding of allosteric structure activity relationships (ASARs).

Anticancer Effect of Fluorouracil and Gum-Based Cerium Oxide Nanoparticles on Human Malignant Colon Carcinoma Cell Line (Caco2)

OBJECTIVE

We investigated whether co-incubation of 5-FU and gum-based cerium oxide nanoparticles (CeO₂ NPs) would improve half-maximal inhibitory concentration (IC₅₀) and apoptosis in the Caco-2 cancer cell line Materials and Methods: In this experimental study, we synthesized Ceo-2-XG by the nano perception method. X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), dynamic light scattering (DLS) and vibrating sample magnetometer (VSM) techniques were employed to characterize the synthesized nanoparticles. The Caco-2 cancer cells were cultured and treated with Ceo-2- XG and 5-FU. Cytotoxicity analysis was carried out using MTT assay on Caco-2 cancer cells. CXCR1, CXCR2, CXCL8, BAX, BCL-2, P53, CASPASE-3, CASPASE-8 and CASPASE-9 gene expression changes were assessed by quantitative reverse-transcriptase polymerase chain reaction (qRT-PCR). The Caco-2 cancer cell mortality mechanism was analyzed using Annexin V-FITC/PI flow cytometry. Using the inverted microscope morphology changes of the Caco-2 cancer cells was observed.

RESULTS

With a sample size of roughly 11 nm, TEM analysis revealed spherical structures. Interestingly, after 72 hours, 400 μg/ml nanoparticles significantly lowered the ₅₀ of 5-FU from 101 to 71 μg/ml (P<000.1). Furthermore, qRT-PCR analysis showed that BCL-2, CXCR1, CXCR2 and CXCR8 expressions were significantly decreased in the 5-FU and Ceo-2-XG nanoparticles co-incubated group, compared to the 5-FU alone (P<0.001). Notably, gene expressions of BAX, P53, CASPASE-3, CASPASE-8 and CASPASE-9 were significantly higher in the 5-FU and Ceo- 2-XG nanoparticles co-incubated group, compared to the 5-FU alone (P<0.001). The findings revealed that dead cells owing to apoptosis were more than two times higher in 5-FU and Ceo-2-XG nanoparticles cancer cells than in 5-FU alone treated cancer cells.

CONCLUSION

Co-incubation of 5-FU and Ceo-2-XG nanoparticles significantly increased apoptosis in the Caco-2 cancer cells. The antiproliferative activity of co-incubated 5-FU and Ceo-2-XG nanoparticles on Caco-2 cancer cells was substantially higher than that of 5-FU alone.

LACTB induces cancer cell death through the activation of the intrinsic caspase-independent pathway in breast cancer

BACKGROUND

LACTB was recently identified as a mitochondrial tumour suppressor that negatively affects cancer cell proliferation by inducing cell death and/or differentiation, depending on the cell type and tissue. However, the detailed mechanism underlying the LACTB-induced cancer cell death is largely unknown.

METHODS

We used cell-based, either in 2D or 3D conditions, and in vivo experiments to understand the LACTB mechanisms. In this regard, protein array followed by an enrichment analysis, cell proliferation assays using different compounds, western blot analysis, flow cytometry and immunofluorescence were performed. Differences between quantitative variables following normal distribution were valuated using Student t test for paired or no-paired samples according to the experiment. For in vivo experiments differences in tumour growth were analyzed by 2-way ANOVA.

RESULTS

We show, that LACTB expression leads to cell cycle arrest in G1 phase and increase of DNA oxidation that leads to activation of intrinsic caspase-independent cell death pathway. This is achieved by an increase of mitochondrial reactive oxygen species since early time points of LACTB induction.

CONCLUSION

Our work provides a deeper mechanistic insight into LACTB-mediated cancer-cell death and shows the dynamics of the cellular responses a particular tumor suppressive stimulus might evoke under different genetic landscapes.

Pyroptosis in Antiviral Immunity

Pyroptosis is a form of lytic, programmed cell death that functions as an innate immune effector mechanism to facilitate host defense against pathogenic microorganisms, including viruses. This type of proinflammatory cell death is orchestrated by proteolytic activation of human or mouse caspase-1, mouse caspase-11 and human caspase-4 and caspase-5 in response to infectious and inflammatory stimuli. Induction of pyroptosis requires either a canonical inflammasome responsible for caspase-1 activation or a noncanonical complex composed of caspase-11 in mice or caspase-4 or caspase-5 in humans. Recent studies have identified the pore-forming protein gasdermin D, a substrate of these inflammatory caspases, as an executioner of pyroptosis. The membrane pores formed by gasdermin D facilitate release of proinflammatory cytokines IL-1β and IL-18 and consequent biologic effects of these cytokines together with other released components. Pyroptosis, like other forms of programmed cell death, helps eliminate infected cells and thereby restricts the replicative niche, undermining survival and proliferation of intracellular pathogens. This includes viruses as well as bacteria, where ample evidence supports a critical role for inflammasome effector functions and cell death in host defense. Viruses have evolved their own mechanisms to modulate inflammasome signaling and pyroptosis. Here, we review the current literature regarding the role of pyroptosis in antiviral immune responses.

Interlacing the relevance of caspase activation in the onset and progression of Alzheimer's disease

Caspases, a family of cysteine proteases is a renowned regulator of apoptosis. Members of this family are responsible for the proteolytic dismantling of numerous cellular structures. Apart from apoptosis, caspases remarkably contribute to a diverse range of molecular processes. Being the imperative members of several cellular cascades their abnormal activation/deactivation has severe implications and also leads to various diseased conditions. Similar aberrant activation of caspases is one of the several causes of neuropathologies associated with Alzheimer's disease (AD), a form of dementia severely affecting neuropsychiatric and cognitive functions. Emerging studies are providing deeper insights into the mechanisms of caspase action in the progression of AD. Current article is an attempt to review these studies and present the action mechanisms of different mammalian caspases in the advancement of AD associated neuropathologies.

Research progress on pyroptosis-mediated immune-inflammatory response in ischemic stroke and the role of natural plant components as regulator of pyroptosis: A review

Ischemic stroke (IS) is one of the leading causes of death and disability. Its pathogenesis is not completely clear, and inflammatory cascade is one of its main pathological processes. The current clinical practice of IS is to restore the blood supply to the ischemic area after IS as soon as possible through thrombolytic therapy to protect the vitality and function of neurons. However, blood reperfusion further accelerates ischemic damage and cause ischemia-reperfusion injury. The pathological process of cerebral ischemia-reperfusion injury involves multiple mechanisms, and the exact mechanism has not been fully elucidated. Pyroptosis, a newly discovered form of inflammatory programmed cell death, plays an important role in the initiation and progression of inflammation. It is a pro-inflammatory programmed death mediated by caspase Caspase-1/4/5/11, which can lead to cell swelling and rupture, release inflammatory factors IL-1β and IL-18, and induce an inflammatory cascade. Recent studies have shown that pyroptosis and its mediated inflammatory response are important factors in aggravating ischemic brain injury, and inhibition of pyroptosis may alleviate the ischemic brain injury. Furthermore, studies have found that natural plant components may have a regulatory effect on pyroptosis. Therefore, this review not only summarizes the molecular mechanism of pyroptosis and its role in ischemic stroke, but also the role of natural plant components as regulator of pyroptosis, in order to provide reference information on pyroptosis for the treatment of IS in the future.

Photosensitization of human skin fibroblasts by vemurafenib promotes pleiotropic effects on membrane-enclosed organelles and apoptosis

Vemurafenib (VB), a BRAF inhibitor and a first-line treatment for unresectable or metastatic melanoma, is strongly phototoxic towards normal skin cells. Herein, we show that in cultured HS 68 human diploid dermal fibroblasts, low concentrations of VB suffice to promote photosensitization to low doses of UVA (∼ 5 J/cm²), as evidenced by a significant decrease in cell viability. In contrast to data obtained in chemico our results support a role for ROS (reactive oxygen species). Indeed, peroxidation of cellular lipids was observed which could be alleviated by the lipophilic antioxidant BHT (2,6-di-tert-butyl-4-methylphenol). Using in vivo confocal laser scanning microscopy and vital fluorescent probes it was shown at the single cell level that the plasma membrane and lipid-rich organelles, namely mitochondria, endoplasmic reticulum, and lysosomes, as well as actin filaments, were severely damaged by the UVA-induced VB-photosensitization. Finally, we showed that mitochondrial impairment was concurrent with caspase 3/7 activation and cell death by apoptosis.

Upconversion nanoparticles as an immunocomplexing agent for selective detection of caspases via sandwich-like supracomplexes

In this study, a nanoparticle-based sandwich-like immunoassay was designed in dispersion medium to precisely detect apoptosis over caspase antibodies in order to overcome the disadvantages of traditional apoptosis determination methods such as high cost, large sampling requirement, and appropriate laboratory and equipment conditions. For this purpose, a complementary particulate system including magnetic (MNPs) and upconversion silica (UC-SiNPs) nanoparticles while immobilizing antibodies (primary antibody to MNPs, secondary antibody to UC-SiNPs) were synthesized and characterized. Optimization and selectivity studies of the complex formed by primary antibody immobilized MNPs with standard caspase proteins were examined by the HPLC system. Within the scope of optimization studies, protein concentrations, optimal duration, and temperature parameters were evaluated. Optimal conditions were determined for pH, initial concentration, time, and temperature as 7.4, 5.6 μg/mL, 45 min, and room temperature, respectively. Furthermore, the adsorption of competitive proteins was investigated in selectivity studies as well. Moreover, the primary antibody immobilized MNPs were treated with standard caspase proteins under optimal conditions; subsequently, they were interacted with secondary antibody immobilized UC-SiNPs to demonstrate the supracomplex formation meanwhile zeta potential/size measurements and fluorescence emission spectrometry analyses were performed. As a result of these analyses, it was observed that the sandwich-like supracomplexes were successfully formed that significantly varied upconversion emission intensities of UC-SiNPs in dependence on the amounts of caspase proteins. Because this approach enabled a quantitative result, the nanoparticle-based sandwich-like immunoassay should be classified as an easy-to-handled, fast, and promising alternative to benchmark apoptosis assays.

Influence of furan and lead co-exposure at environmentally relevant concentrations on neurobehavioral performance, redox-regulatory system and apoptotic responses in rats

Furan and lead are contaminants of global concern due to the potential public health threat associated with their exposure. Herein, the neurobehavioral performance, biochemical effects and histological alterations associated with co-exposure to furan (8 mg/kg) and lead acetate at low, environmentally realistic concentrations (1, 10 and 100 µg PbAc/L) for 28 uninterrupted days were investigated in rats. The results demonstrated that locomotor, motor and exploratory deficits associated with separate exposure to furan and lead was exacerbated in the co-exposed rats. Furan and lead co-exposure aggravated the marked decrease in acetylcholinesterase activity and antioxidant status, elevation in oxido-inflammatory stress indices and caspases activation in the cerebrum and cerebellum of exposed rats compared with control. Furan and lead co-exposure worsened neuronal degeneration as verified by histomorphometry and histochemical staining. Collectively, furan and lead acts together to exacerbate neurotoxicity via inhibition of cholinergic system, induction of oxido-inflammatory stress and caspases activation in rats.

Gold(III) Complexes with Phenanthroline-derivatives Ligands Induce Apoptosis in Human Colorectal and Breast Cancer Cell Lines

Due to their promising effects, gold(III) complexes recently drew increasing attention in the design of new metal-based anticancer therapeutics. Two gold(III) complexes, square-planar [Au(DPP)Cl2]+ - Complex 1 and distorted square-pyramidal [Au(DMP)Cl3] - Complex 2 (where DPP=4,7-diphenyl-1,10-phenanthroline and DMP=2,9-dimethyl-1,10-phenanthroline) were previously synthetized, described and approved as complexes with pronounced cytotoxic effects on colorectal HCT-116 and breast MDA-MB-231 cancer cells. This study investigated the type of cell death by AO/EB double staining, and identification of possible targets responsible for their cytotoxicity, monitored by immunofluorescence and qPCR methods. Both complexes induced apoptosis in all applied concentrations. In the HCT-116 cells apoptosis was activated by external apoptotic pathway, via increase of Fas receptor protein expression and Caspase 8 gene expression. Also, the mitochondrial pathway was triggered by affecting the Bcl-2 members of regulatory proteins and increased caspase 9 protein expression. In MDA-MB-231 cells, apoptosis was initiated from the mitochondria, due to disbalance between expressions of pro- and anti-apoptotic Bcl-2 family members and caspase 9 activation. Complex 1 shows better activity compared to Complex 2, which is in accordance with its structural characteristics. The results deal weighty data about proapoptotic activity of gold(III) complexes and highlighted potential targets for cancer therapy.

Role of Lactiplantibacillus plantarum strain RD1 (Lpb RD1) in mitochondria-mediated apoptosis: an in vitro analysis

The purpose of this study was to determine the cytotoxicity of Lactiplantibacillus plantarum strain RD1 (Lpb RD1), which was isolated and identified from the curd by 16 S rRNA sequencing. The probiotic properties of the isolated strain were studied by bile and NaCl tolerance and the ethyl acetate extract of Ea-LpRD1, was used to determine the toxicity against human breast cancer (MCF-7) cell lines and human embryonic kidney (HEK-293) cell lines by MTT assay. DNA fragmentation assay was carried out to study apoptosis induction. Flow cytometry analysis was done to determine the % of a cell population using the FTIC-Annexin V staining method. RT-PCR was used to assess gene expression levels in both cell lines. The IC₅₀ concentration of the Ea-LpRD1 in MCF-7 cells was 0.30 mg/ml and in HEK-293 was 0.47 mg/ml. The expression levels of the BCL-2 gene anti-apoptotic genes in humans were reduced and BAX, caspase-8, caspase-3, and caspase-9 were an increased expression in MCF-7 cell lines.

Modeled microgravity alters apoptotic gene expression and caspase activity in the squid-vibrio symbiosis

Background

Spaceflight is a novel and profoundly stressful environment for life. One aspect of spaceflight, microgravity, has been shown to perturb animal physiology thereby posing numerous health risks, including dysregulation of normal developmental pathways. Microgravity can also negatively impact the interactions between animals and their microbiomes. However, the effects of microgravity on developmental processes influenced by beneficial microbes, such as apoptosis, remains poorly understood. Here, the binary mutualism between the bobtail squid, Euprymna scolopes, and the gram-negative bacterium, Vibrio fischeri, was studied under modeled microgravity conditions to elucidate how this unique stressor alters apoptotic cell death induced by beneficial microbes.

Results

Analysis of the host genome and transcriptome revealed a complex network of apoptosis genes affiliated with extrinsic/receptor-mediated and intrinsic/stress-induced apoptosis. Expression of apoptosis genes under modeled microgravity conditions occurred earlier and at high levels compared to gravity controls, in particular the expression of genes encoding initiator and executioner caspases. Functional assays of these apoptotic proteases revealed heightened activity under modeled microgravity; however, these increases could be mitigated using caspase inhibitors.

Conclusions

The outcomes of this study indicated that modeled microgravity alters the expression of both extrinsic and intrinsic apoptosis gene expression and that this process is mediated in part by caspases. Modeled microgravity-associated increases of caspase activity can be pharmacologically inhibited suggesting that perturbations to the normal apoptosis signaling cascade can be mitigated, which may have broader implications for maintaining animal-microbial homeostasis in spaceflight.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12866-022-02614-x.

Clostridioides difficile toxin B alone and with pro-inflammatory cytokines induces apoptosis in enteric glial cells by activating three different signalling pathways mediated by caspases, calpains and cathepsin B

Clostridioides difficile infection (CDI) causes nosocomial/antibiotic-associated gastrointestinal diseases with dramatically increasing global incidence and mortality rates. The main C. difficile virulence factors, toxins A and B (TcdA/TcdB), cause cytopathic/cytotoxic effects and inflammation. We demonstrated that TcdB induces caspase-dependent, mitochondria-independent enteric glial cell (EGC) apoptosis that is enhanced by the pro-inflammatory cytokines TNF-α and IFN-γ (CKs) by increasing caspase-3/7/9 and PARP activation. Because this cytotoxic synergism is important for CDI pathogenesis, we investigated the apoptotic pathways involved in TcdB- and TcdB + CK-induced apoptosis indepth. EGCs were pre-treated with the inhibitors BAF or Q-VD-OPh (pan-caspase), Z-DEVD-fmk (caspase-3/7), Z-IETD-fmk (caspase-8), PD150606 (calpains), and CA-074Me (cathepsin B) 1 h before TcdB exposure, while CKs were given 1.5 h after TcdB exposure, and assays were performed at 24 h. TcdB and TcdB + CKs induced apoptosis through three signalling pathways activated by calpains, caspases and cathepsins, which all are involved both in induction and execution apoptotic signalling under both conditions but to different degrees in TcdB and TcdB + CKs especially as regards to signal transduction mediated by these proteases towards downstream effects (apoptosis). Calpain activation by Ca²⁺ influx is the first pro-apoptotic event in TcdB- and TcdB + CK-induced EGC apoptosis and causes caspase-3, caspase-7 and PARP activation. PARP is also directly activated by calpains which are responsible of about 75% of apoptosis in TcdB and 62% in TcdB + CK which is both effector caspase-dependent and -independent. Initiator caspase-8 activation mediated by TcdB contributes to caspase-3/caspase-7 and PARP activation and is responsible of about 28% of apoptosis in both conditions. Caspase-3/caspase-7 activation is weakly responsible of apoptosis, indeed we found that it mediates 27% of apoptosis only in TcdB. Cathepsin B contributes to triggering pro-apoptotic signal and is responsible in both conditions of about 35% of apoptosis by a caspase-independent manner, and seems to regulate the caspase-3 and caspase-7 cleaved fragment levels, highlighting the complex interaction between these cysteine protease families activated during TcdB-induced apoptosis. Further a relevant difference between TcdB- and TcdB + CK-induced apoptosis is that TcdB-induced apoptosis increased slowly reaching at 72 h the value of 18.7%, while TcdB + CK-induced apoptosis increased strongly reaching at 72 h the value of 60.6%. Apoptotic signalling activation by TcdB + CKs is enriched by TNF-α-induced NF-κB signalling, inhibition of JNK activation and activation of AKT. In conclusion, the ability of C. difficile to activate three apoptotic pathways represents an important strategy to overcome resistance against its cytotoxic activity.

Caspase-mediated regulation of the distinct signaling pathways and mechanisms in neuronal survival

Caspases are intimately associated with altering various signaling pathways, resulting in programmed cell death or apoptosis. Apoptosis is necessary for the normal homeostasis of cells and their development. The untoward activation of apoptotic pathways indirectly or directly results in pathologies of various diseases. Identifying different caspases in apoptotic pathways directed the research to develop caspase inhibitors as therapeutic agents. However, no drug is available in the market that targets caspase inhibition and produces a therapeutic effect. Here, we will shed light on the role of caspases in the number of neuronal disorders and neurodegenerative diseases. The article reviews the findings about the activation of various upstream mechanisms associated with caspases in neurodegenerative disorders along with the recent progress in the generation of caspase inhibitors and the challenge faced in their development as therapeutic agents for neurological indications.

Sesquiterpene from Polygonum barbatum disrupts mitochondrial membrane potential to induce apoptosis and inhibits metastasis by downregulating matrix metalloproteinase and osteopontin in NCI-H460 cells

Globally, lung cancer accounts for 18% of cancer-associated mortalities. Among the subtypes, non-small cell lung cancer (NSCLC) is the most prevalent. The increased resistance and poor survival rates signify disease aggressiveness and thus require a search for an alternative anticancer molecule. Earlier, the sesquiterpene, i.e., compound 3 ((E)-methyl 6-acetoxy-7-methoxy-1-(2-methylpropylidene)-1H-indene-3-carboxylate) from Polygonum barbatum, was isolated, characterized by us, and reported for preliminary anticancer activity. Therefore, based on these results, this study was designed to explore the underlying molecular mechanism of apoptosis and metastasis against NCI-H460 cells. The molecular mechanism of compound 3 inducing apoptosis and inhibiting metastasis was elucidated by analyzing mitochondrial membrane potential, DNA fragmentation, clonogenic assay, invasion assay, and expression of apoptotic (caspases 3, 6, 8, 9, and BAK) and metastatic markers (MMP 2, MMP 9, and osteopontin). Compound 3 significantly inhibited cell proliferation and induced apoptosis via the intrinsic route, i.e., the mitochondrial pathway, by disrupting mitochondrial membrane potential. The enhanced expression of caspases 6, 9, BAK, and HRK with downregulation of Bcl-2L1 and Ki67 further confirmed the involvement of the intrinsic apoptotic pathway. Moreover, compound 3 restricted the invasive nature of NCI-H460 cells evinced by reduced cell invasion in Boyden chamber invasion assay and downregulating the expression of metastatic markers, i.e., matrix metalloproteinase 2/9 and VEGF. It was also found to block osteopontin by negatively regulating its expression, a marker protein in cancer management. Conclusively, this sesquiterpene exhibited potent anticancer and antimetastatic activity and can be explored further as possible pharmacophores.

Ars moriendi: Proteases as sculptors of cellular suicide

The Ars moriendi, which translates to "The Art of Dying," encompasses two Latin texts that gave advice on how to die well and without fear according to the Christian precepts of the late Middle Ages. Given that ten to hundred billion cells die in our bodies every day, it is obvious that the concept of a well and orderly ("regulated") death is also paramount at the cellular level. In apoptosis, as the most well-studied form of regulated cell death, proteases of the caspase family are the central mediators. However, caspases are not the only proteases that act as sculptors of cellular suicide, and therefore, we here provide an overview of the impact of proteases in apoptosis and other forms of regulated cell death.

Pharmacological, Biochemical and Immunological Studies on Protective Effect of Mangiferin in 6-Hydroxydopamine (6-OHDA)-Induced Parkinson's Disease in Rats

Background:

Parkinson’s disease is a neurodegenerative disorder and is marked by inflammation and death of neurons in the striatum region of the midbrain. It has been reported that expression of NF-κB increases during Parkinson’s disease, which promotes oxidative stress, stimulates release of proinflammatory cytokines, and induces expression of nitric oxide. Therefore, in this study, we have used mangiferin a specific NF-κB inhibitor. Mangiferin is a polyphenolic compound traditionally used for its antioxidant and anti-inflammatory properties.

Methods:

The study utilized male Wistar rats weighing 200–250 g (56 rats; n = 8/group). On day “0,” stereotaxic surgery of rats was done to induce 6-hydroxydopamine lesioning in rats. Coordinates for substantia nigra were anteroposterior-2 mm, mediolateral-5 mm and dorsoventral-8.2 mm. After 14 days, those rats which show at least 210 contralateral rotations after administration of apomorphine (0.5 mg/kg S.C.) were selected for the study and were given treatment for 28 days. On day 28 of treatment, rats were subjected to behavioral studies to evaluate the effect of mangiferin and their brains were taken out after euthanasia to perform biochemical, molecular and immunological studies.

Results:

Treatment with mangiferin significantly improves the key parameters of locomotor activity and oxidative stress and reduces the parameters of inflammatory stress. Also, the activity of caspases was reduced. Significant decrease in activity of both cyclooxygenase 1 and 2 was also observed. Maximum improvement in all parameters was observed in rats treated with grouping of mangiferin 45 µg/kg and levodopa 10 mg/kg. Treatment with levodopa alone has no significant effect on biochemical and molecular parameters though it significantly improves behavioral parameters.

Conclusion:

Current treatment of Parkinson’s disease does not target progression of Parkinson’s disease. Results of this study suggest that mangiferin has protective effect in hemi-Parkinsonian rats. Therefore, the combination therapy of mangiferin and levodopa can be helpful in management of Parkinson’s disease.

Caspase Inhibition Restores NEP Expression and Rescues Olfactory Deficit in Rats Caused by Prenatal Hypoxia

Development of the olfactory system begins early in embryogenesis and is important for the survival of new-borns in postnatal life. Olfactory malfunction in early life disrupts development of behavioural patterns while with ageing manifests development of neurodegenerative disorders. Previously, we have shown that prenatal hypoxia in rats leads to impaired olfaction in the offspring and correlates with reduced expression of a neuropeptidase neprilysin (NEP) in the brain structures involved in processing of the olfactory stimuli. Prenatal hypoxia also resulted in an increased activity of caspases in rat brain and its inhibition restored NEP content in the brain tissue and improved rat memory. In this study, we have analysed effects of intraventricular administration of a caspase inhibitor Ac-DEVD-CHO on NEP mRNA expression, the number of dendritic spines and olfactory function of rats subjected to prenatal hypoxia on E14. The data obtained demonstrated that a single injection of the inhibitor on P20 restored NEP mRNA levels and number of dendritic spines in the entorhinal and parietal cortices, hippocampus and rescued rat olfactory function in food search and odour preference tests. The data obtained suggest that caspase activation caused by prenatal hypoxia contributes to the olfactory dysfunction in developing animals and that caspase inhibition restores the olfactory deficit via upregulating NEP expression and neuronal networking. Because NEP is a major amyloid-degrading enzyme, any decrease in its expression and activity not only impairs brain functions but also predisposes to accumulation of the amyloid-β peptide and development of neurodegeneration characteristic of Alzheimer's disease.

Guanylate Binding Protein 1 (GBP1): A Key Protein in Inflammatory Pyroptosis

Scientists recently made a significant breakthrough in the recognition of pathogens via guanylate binding protein 1 (GBP1). Wandel et al. [1] in Nature Immunology described their findings where GBP1 acts as a pattern recognition receptor that directly connects to lipopolysaccharide (LPS). GBP1 identifies gram-negative bacteria such as the enteric pathogen, Salmonella enterica serovar Typhimurium, that enter the cytoplasm of the host cell. GBP1 then quickly connects to LPS and stimulates the assembly of more GBPs in the order of GBP2, GBP3, and GBP4. Subsequently, inflammatory caspase-4 arrives at the GBP1-4 activation platform. Next, the activated caspase-4 drives the cleavage of Gasdermin D, triggering the release of the pro-inflammatory cytokine, interleukin-18 (IL-18) leading to inflammatory pyroptosis and cell death. Not only do these remarkable results expand our current understanding of GBP1, but they also carry the potential to develop therapeutic targets for inflammasome-mediated human disorders.

EPEC-induced activation of the Ca2+ transporter TRPV2 leads to pyroptotic cell death

The enteropathogenic Escherichia coli (EPEC) type III secretion system effector Tir, which mediates intimate bacterial attachment to epithelial cells, also triggers Ca2+ influx followed by LPS entry and caspase-4-dependent pyroptosis, which could be antagonized by the effector NleF. Here we reveal the mechanism by which EPEC induces Ca2+ influx. We show that in the intestinal epithelial cell line SNU-C5, Tir activates the mechano/osmosensitive cation channel TRPV2 which triggers extracellular Ca2+ influx. Tir-induced Ca2+ influx could be blocked by siRNA silencing of TRPV2, pre-treatment with the TRPV2 inhibitor SET2 or by growing cells in low osmolality medium. Pharmacological activation of TRPV2 in the absence of Tir failed to initiate caspase-4-dependent cell death, confirming the necessity of Tir. Consistent with the model implicating activation on translocation of TRPV2 from the ER to plasma membrane, inhibition of protein trafficking by either brefeldin A or the effector NleA prevented TRPV2 activation and cell death. While infection with EPECΔnleA triggered pyroptotic cell death, this could be prevented by NleF. Taken together this study shows that while integration of Tir into the plasma membrane activates TRPV2, EPEC uses NleA to inhibit TRPV2 trafficking and NleF to inhibit caspase-4 and pyroptosis.

NSAIDs and Kelleni's protocol as potential early COVID-19 treatment game changer: could it be the final countdown?

We have previously published several papers illustrating numerous immunomodulatory and anti-inflammatory potential benefits when we repurposed safe, generic non-steroidal anti-inflammatory drugs (NSAIDs)/nitazoxanide/azithromycin (Kelleni's protocol), to early manage our COVID-19 pediatric, adult, and pregnant patients. In this manuscript, we discuss some recently published meta-analysis and clinical studies supporting our practice and discuss a molecular study that might be interpreted as an academic proof that our protocol might also prevent SARS-CoV-2 replication. Moreover, after aspirin has been suggested to be independently associated with reduced risk of mechanical ventilation, ICU admission and in-hospital mortality of COVID-19, we claim that the molecular interpretation of the results that led to this suggestion was not scientifically accurate, and we provide our academic interpretation confirming that low-dose aspirin is least likely to improve COVID-19 mortality through anticoagulation as was suggested. Furthermore, we describe other potential benefits related to aspirin-triggered lipoxins and resolvins while illustrating how NSAIDs interfere with COX-1, COX-2, SARS-CoV-2/ SARS-CoV-2 ORF protein-dependent activation of caspases and their subsequent mitochondrial dysfunction, endoplasmic reticulum stress, apoptosis and necroptosis which were associated with COVID-19 complications. Similarly, NSAIDs are known caspase inhibitors and thus they might independently inhibit other caspase-related COVID-19-associated downstream pathological signaling mechanisms. Finally, we postulated that CARD-14, a caspase recruitment domain-containing protein, polymorphisms might play a role in the development of severe and critical COVID-19 and confirmed our old call to early adopt NSAIDs, as an integral part of Kelleni's protocol, as of choice in its management aiming to end this pandemic.

Exploring the MEN1 dependent modulation of caspase 8 and caspase 3 in human pancreatic and murine embryo fibroblast cells

MEN1 mutation causes pancreatic neuroendocrine neoplasia and benign malignancies of the parathyroid, the adrenal cortex and pituitary gland. The transcriptional activity of its product menin promotes the expression of genes deputed to several cellular mechanism including cell death. Here, we focused on its implication in the activation of the initiator and executioner caspases after staurosporine mediated cell death in 2D and 3D human and murine cell models. The administration of staurosporine, a well-known inducer of apoptotic cell death, caused a significant reduction of BON1, QGP1 and HPSC2.2 cell viability. The transient knockdown of MEN1, performed by using a specific siRNA, caused a significant down-regulation of CDKN1A and TP53 transcripts. The treatment with 1 µM of staurosporine caused also a significant down-regulation of MEN1 and was able to restore the basal expression of TP53 only in QGP1 cells. Transient or permanent MEN1 inactivation caused a decrease of caspase 8 activity in BON1, HPSC2.2 cells and MEN1^-/- MEFs treated with staurosporine. Caspase 3/7 activity was suppressed after administration of staurosporine in MEN1 knocked down HPSC2.2 and MEN1^-/- MEFs as well. The cleaved caspase 8 and caspase 3 decreased in human cells after MEN1 knockdown and in MEN1^-/- MEFs. The treatment with staurosporine caused a reduction of the size of MEN1^+/+ MEFs spheroids. Instead, MEN1^-/- MEFs spheroids did not show any significant reduction of their size. In conclusion, MEN1 controls the activity of the initiator caspase 8 and the executioner caspase 3 in human and murine cells. Restoring of a functional MEN1 and interfering with the apoptotic mechanism could represent a future strategy for the treatment of MEN1-related malignancies.