Mitochondria as regulators of apoptosis: doubt no more

EFHD1 promotes osteosarcoma proliferation and drug resistance by inhibiting the opening of the mitochondrial membrane permeability transition pore (mPTP) by binding to ANT3

Chemoresistance is the main obstacle in the clinical treatment of osteosarcoma (OS). In this study, we investigated the role of EF-hand domain-containing protein 1 (EFHD1) in OS chemotherapy resistance. We found that the expression of EFHD1 was highly correlated with the clinical outcome after chemotherapy. We overexpressed EFHD1 in 143B cells and found that it increased their resistance to cell death after drug treatment. Conversely, knockdown of EFHD1 in 143BR cells (a cisplatin-less-sensitive OS cell line derived from 143B cells) increased their sensitivity to treatment. Mechanistically, EFHD1 bound to adenine nucleotide translocase-3 (ANT3) and inhibited its conformational change, thereby inhibiting the opening of the mitochondrial membrane permeability transition pore (mPTP). This effect could maintain mitochondrial function, thereby favoring OS cell survival. The ANT3 conformational inhibitor carboxyatractyloside (CATR), which can promote mPTP opening, enhanced the chemosensitivity of EFHD1-overexpressing cells when combined with cisplatin. The ANT3 conformational inhibitor bongkrekic acid (BKA), which can inhibit mPTP opening, restored the resistance of EFHD1 knockdown cells. In conclusion, our results suggest that EFHD1-ANT3-mPTP might be a promising target for OS therapy in the future.

The neuroprotective potential of phytochemicals in traumatic brain injury: mechanistic insights and pharmacological implications

Traumatic brain injury (TBI) leads to brain damage, comprising both immediate primary damage and a subsequent cascade of secondary injury mechanisms. The primary injury results in localized brain damage, while the secondary damage initiates inflammatory responses, followed by the disruption of the blood-brain barrier, infiltration of peripheral blood cells, brain edema, and the release of various immune mediators, including chemotactic factors and interleukins. TBI disrupts molecular signaling, cell structures, and functions. In addition to physical tissue damage, such as axonal injuries, contusions, and haemorrhages, TBI interferes with brain functioning, impacting cognition, decision-making, memory, attention, and speech capabilities. Despite a deep understanding of the pathophysiology of TBI, an intensive effort to evaluate the underlying mechanisms with effective therapeutic interventions is imperative to manage the repercussions of TBI. Studies have commenced to explore the potential of employing natural compounds as therapeutic interventions for TBI. These compounds are characterized by their low toxicity and limited interactions with conventional drugs. Moreover, many natural compounds demonstrate the capacity to target various aspects of the secondary injury process. While our understanding of the pathophysiology of TBI, there is an urgent need for effective therapeutic interventions to mitigate its consequences. Here, we aimed to summarize the mechanism of action and the role of phytochemicals against TBI progression. This review discusses the therapeutic implications of various phytonutrients and addresses primary and secondary consequences of TBI. In addition, we highlighted the roles of emerging phytochemicals as promising candidates for therapeutic intervention of TBI. The review highlights the neuroprotective roles of phytochemicals against TBI and the mechanistic approach. Furthermore, our efforts focused on the underlying mechanisms, providing a better understanding of the therapeutic potential of phytochemicals in TBI therapeutics.

The conditional mitochondrial protein complexome in the Arabidopsis thaliana root and shoot

Protein complexes are important for almost all biological processes. Hence, to fully understand how cells work, it is also necessary to characterize protein complexes and their dynamics in response to various cellular cues. Moreover, the dynamics of protein interaction play crucial roles in regulating the (dis)association of protein complexes and, in turn, regulating biological processes such as metabolism. Here, mitochondrial protein complexes were investigated by blue native PAGE and size-exclusion chromatography under conditions of oxidative stress in order to monitor their dynamic (dis)associations. Rearrangements of enzyme interactions and changes in protein complex abundance were observed in response to oxidative stress induced by menadione treatment. These included changes in enzymatic protein complexes involving γ-amino butyric acid transaminase (GABA-T), Δ-ornithine aminotransferase (Δ-OAT), or proline dehydrogenase 1 (POX1) that are expected to affect proline metabolism. Menadione treatment also affected interactions between several enzymes of the tricarboxylic acid (TCA) cycle and the abundance of complexes of the oxidative phosphorylation pathway. In addition, we compared the mitochondrial complexes of roots and shoots. Considerable differences between the two tissues were observed in the mitochondrial import/export apparatus, the formation of super-complexes in the oxidative phosphorylation pathway, and specific interactions between enzymes of the TCA cycle that we postulate may be related to the metabolic/energetic requirements of roots and shoots.

Synergetic effect of high dose rate radiations (10× FFF/2400 MU/min/10 MV x-rays) and paclitaxel selectively eliminates melanoma cells

BACKGROUND

Melanoma is one of the most aggressive cancers, with 1.6% of total cancer deaths in the United States. In recent years treatment options for metastatic melanoma have been improved by the FDA approval of new therapeutic agents. However, these inhibitors-based therapies are non-specific and have severe toxicities, including hyperkeratosis, photosensitivity, hepatitis, arthralgia, and fatigue.

AIMS

The aim of this study is to determine the synthetic lethal effect (paclitaxel and radiations) on melanoma cells and reduce the total radiation doses by increasing the dose rates up to 2400 MU/min.

METHODS AND RESULTS

We previously reported a radiation treatment (10 MV x-rays, 10X-FFF, dose rate 2400MU/min, low total dose 0.5 Gy) that kills melanoma cells with 80% survival of normal HEM in vitro. In this study, we extended the radiation cycle up to four and included paclitaxel treatment to study the synthetic lethal effect on melanoma and two other normal primary cells, HDF and HEK. Cells were treated with paclitaxel prior to the radiation at a dose rate of 400 and 2400 MU/min with a total radiation dose of only 0.5 Gy. Mitochondrial respiration assay, DNA damage assay, and colony formation assays were performed to study apoptosis and cell death induction. Four days of consequent radiation treatment with paclitaxel significantly reduces the survival of melanoma cells by inducing apoptosis and mitochondrial damage. After treatment, excessive DNA damage in melanoma cells leads to an increase in the expression of pro-apoptotic genes (Caspase-3) and a decrease in the expression of DNA repair gene (PARP1) and anti-apoptotic gene (Bcl-2) to activate the apoptosis pathway. The combination of paclitaxel and radiation reduces the survival of melanoma cells colonies compared to radiation alone.

CONCLUSION

Our study indicates that radiations with paclitaxel have a potential synthetic lethal effect on melanoma cells and can be developed as a melanoma therapy without toxicities or harmful effects on normal primary skin cells.

Synergic Effect of Honey with Other Natural Agents in Developing Efficient Wound Dressings

Honey has been used for therapeutic and nutritional purposes since ancient times. It was considered one of the essential medical assets in wound healing. According to research, honeybees have significant antibacterial, antioxidant, anti-inflammatory, antitumor, and wound-healing properties. Lately, scientific researchers have focused on apitherapy, using bee products to protect and strengthen the immune system. Since honey is the most important natural product rich in minerals, proteins, and vitamins, it has been intensively used in such therapies. Honey has gained significant consideration because of the beneficial role of its antioxidant compounds, such as enzymes, proteins, amino and organic acids, polyphenols, and carotenoids, but mainly due to flavonoids and phenolic acids. It has been proven that phenolic compounds are responsible for honey's biological activity and that its physicochemical properties, antioxidants, and antimicrobial potential are significant for human health. The review also presents some mechanisms of action and the medical applications of honey, such as wound healing dressings, skin grafts, honey-based nanofibers, and cochlear implants, as the most promising wound healing tools. This extensive review has been written to highlight honey's applications in medicine; its composition with the most important bioactive compounds also illustrates its synergistic effect with other natural products having remarkable therapeutic properties in wound healing.

Developmentally regulated mitochondrial biogenesis and cell death competence in maize pollen

BACKGROUND

Cytoplasmic male sterility (CMS) is a maternally inherited failure to produce functional pollen that most commonly results from expression of novel, chimeric mitochondrial genes. In Zea mays, cytoplasmic male sterility type S (CMS-S) is characterized by the collapse of immature, bi-cellular pollen. Molecular and cellular features of developing CMS-S and normal (N) cytoplasm pollen were compared to determine the role of mitochondria in these differing developmental fates.

RESULTS

Terminal deoxynucleotidyl transferase dUTP nick end labeling revealed both chromatin and nuclear fragmentation in the collapsed CMS-S pollen, demonstrating a programmed cell death (PCD) event sharing morphological features with mitochondria-signaled apoptosis in animals. Maize plants expressing mitochondria-targeted green fluorescent protein (GFP) demonstrated dynamic changes in mitochondrial morphology and association with actin filaments through the course of N-cytoplasm pollen development, whereas mitochondrial targeting of GFP was lost and actin filaments were disorganized in developing CMS-S pollen. Immunoblotting revealed significant developmental regulation of mitochondrial biogenesis in both CMS-S and N mito-types. Nuclear and mitochondrial genome encoded components of the cytochrome respiratory pathway and ATP synthase were of low abundance at the microspore stage, but microspores accumulated abundant nuclear-encoded alternative oxidase (AOX). Cytochrome pathway and ATP synthase components accumulated whereas AOX levels declined during the maturation of N bi-cellular pollen. Increased abundance of cytochrome pathway components and declining AOX also characterized collapsed CMS-S pollen. The accumulation and robust RNA editing of mitochondrial transcripts implicated translational or post-translational control for the developmentally regulated accumulation of mitochondria-encoded proteins in both mito-types.

CONCLUSIONS

CMS-S pollen collapse is a PCD event coincident with developmentally programmed mitochondrial events including the accumulation of mitochondrial respiratory proteins and declining protection against mitochondrial generation of reactive oxygen species.

Theoretical approaches used in the modelling of reversible and irreversible mitochondrial swelling in vitro

Existing theoretical approaches were considered that allow modelling of mitochondrial swelling (MS) dynamics. Simple phenomenological kinetic models were reviewed. Simple and extended biophysical and bioenergetic models that ignore mechanical properties of inner mitochondrial membrane (IMM), and similar models that include these mechanical properties were also reviewed. Limitations of these models we considered, as regards correct modelling of MS dynamics. It was found that simple phenomenological kinetic models have significant limitations, due to dependence of the kinetic parameter values estimated by fitting of the experimental data on the experimental conditions. Additionally, such simple models provide no understanding of the detailed mechanisms behind the MS dynamics, nor of the dynamics of various system parameters during MS. Thus, biophysical and bioenergetic models ignoring IMM mechanical properties can't be used to model the transition between reversible and irreversible MS. However, simple and extended biophysical models that include IMM mechanical properties allow modelling the transition to irreversible swelling. These latter models are still limited due to significantly simplified description of biochemistry, compared to those of bioenergetic models. Finally, a strategy of model development is proposed, towards correct interpretation of the mitochondrial life cycle, including the effects of MS dynamics.

Oxidative stress and mitochondrial dysfunction following traumatic brain injury: From mechanistic view to targeted therapeutic opportunities

Traumatic brain injury (TBI) is one of the most prevalent causes of permanent physical and cognitive disabilities. TBI pathology results from primary insults and a multi-mechanistic biochemical process, termed as secondary brain injury. Currently, there are no pharmacological agents for definitive treatment of patients with TBI. This article is presented with the purpose of reviewing molecular mechanisms of TBI pathology, as well as potential strategies and agents against pathological pathways. In this review article, materials were obtained by searching PubMed, Scopus, Elsevier, Web of Science, and Google Scholar. This search was considered without time limitation. Evidence indicates that oxidative stress and mitochondrial dysfunction are two key mediators of the secondary injury cascade in TBI pathology. TBI-induced oxidative damage results in the structural and functional impairments of cellular and subcellular components, such as mitochondria. Impairments of mitochondrial electron transfer chain and mitochondrial membrane potential result in a vicious cycle of free radical formation and cell apoptosis. The results of some preclinical and clinical studies, evaluating mitochondria-targeted therapies, such as mitochondria-targeted antioxidants and compounds with pleiotropic effects after TBI, are promising. As a proposed strategy in recent years, mitochondria-targeted multipotential therapy is a new hope, waiting to be confirmed. Moreover, based on the available findings, biologics, such as stem cell-based therapy and transplantation of mitochondria are novel potential strategies for the treatment of TBI; however, more studies are needed to clearly confirm the safety and efficacy of these strategies.

Neonicotinoids: mechanisms of systemic toxicity based on oxidative stress-mitochondrial damage

Neonicotinoids are the most widely used pesticides in the world. However, research studies have shown that it can affect the cognitive abilities and health of non-target bees and other wild pollinators by inducing DNA damage, apoptosis and mitochondrial damage, injure to its central nervous system, and it is even developmentally neurotoxic to mammals and humans, with mitochondria being an important target of neonicotinoids. Therefore, this article reviews the role of mitochondrial morphology, calcium ions (Ca²⁺) homeostasis, respiratory function, apoptosis, and DNA damage in neonicotinoids-induced systemic toxicity. Additionally, it evaluates the protective effects of various active substances including vitamin C, N-acetylcysteine (NAC), curcumin (CUR), glutathione reduced (GSH), caffeic acid phenethyl ester (CAPE), resveratrol, and thymoquinone (TQ) on neonicotinoids-induced toxicity. This review manuscript found that mitochondria are important targets to neonicotinoids. Neonicotinoids can cause DNA damage, apoptosis, protein oxidation, and lipid peroxidation in non-target organisms by altering mitochondrial Ca²⁺ homeostasis, inhibiting mitochondrial respiration, and inducing reactive oxygen species (ROS) production. Several active substances (vitamin C, NAC, CUR, GSH, resveratrol, CAPE, and TQ) play a protective role against neonicotinoid-induced systemic toxicity by inhibiting ROS signaling pathways, apoptosis, and lipid peroxidation. This review manuscript emphasizes the importance and urgency of the development of neonicotinoid antidotes, emphasizes the prospect of the application of targeted mitochondrial antidotes, and prospects the development of neonicotinoid antidotes in order to provide some strategies for the prevention of neonicotinoid toxicity.

PINK1/Parkin-mediated mitophagy is activated to protect against AFB1-induced kidney damage in mice

Aflatoxin B₁ (AFB₁) is a toxic food pollutant that has extensive deleterious impacts on the kidney. Oxidative stress represents the primary mechanism of AFB₁ nephrotoxicity and can also cause mitochondrial damage. Damaged mitochondria can trigger apoptosis leading to kidney injury. PINK1/Parkin-mediated mitophagy can alleviate mitochondrial injury to maintain cellular homeostasis, however, its role in AFB₁-induced kidney damage is unknown. To investigate the effect of PINK1/Parkin-mediated mitophagy on kidney impairment triggered by AFB₁, 40 male wild-type (WT) C57BL/6N mice were first assigned to 4 groups and orally exposed to AFB₁ at 0, 0.5, 0.75, and 1 mg/kg body weight (BW) for 28 days. The results revealed that AFB₁ induced kidney damage, oxidative stress, mitochondrial damage, apoptosis and activated PINK1/Parkin-mediated mitophagy with a dose-dependent effect. Then, 20 male WT C57BL/6N mice and 20 male Parkin knockout (Parkin^-/-) C57BL/6N mice were assigned to 4 groups and orally exposed to AFB₁ at 0, 1, 0, and 1 mg/kg BW for 28 days. The results revealed that Parkin^-/- suppressed mitophagy and exacerbated kidney damage, oxidative stress, mitochondrial damage, and apoptosis under AFB₁ exposure. The aforementioned evidences demonstrate that PINK1/Parkin-mediated mitophagy is activated by AFB₁ and protects against kidney damage in mice.

Whole and Purified Aqueous Extracts of Nigella sativa L. Seeds Attenuate Apoptosis and the Overproduction of Reactive Oxygen Species Triggered by p53 Over-Expression in the Yeast Saccharomyces cerevisiae

Plants are an important source of pharmacologically active compounds. In the present work, we characterize the impact of black cumin (Nigella sativa L.) aqueous extracts on a yeast model of p53-dependent apoptosis. To this end, the Saccharomyces cerevisiae recombinant strain over-expressing p53 was used. The over-expression of p53 triggers the expression of apoptotic markers: the externalization of phosphatidylserine, mitochondrial defect associated with cytochrome-c release and the induction of DNA strand breaks. These different effects were attenuated by Nigella sativa L. aqueous extracts, whereas these extracts have no effect on the level of p53 expression. Thus, we focus on the anti-apoptotic molecules present in the aqueous extract of Nigella sativa L. These extracts were purified and characterized by complementary chromatographic methods. Specific fluorescent probes were used to determine the effect of the extracts on yeast apoptosis. Yeast cells over-expressing p53 decrease in relative size and have lower mitochondrial content. The decrease in cell size was proportional to the decrease in mitochondrial content and of mitochondrial membrane potential (ΔΨm). These effects were prevented by the purified aqueous fraction obtained by fractionation with different columns, named C4 fraction. Yeast cell death was also characterized by reactive oxygen species (ROS) overproduction. In the presence of the C4 fraction, ROS overproduction was strongly reduced. We also noted that the C4 fraction promotes the cell growth of control yeast cells, which do not express p53, supporting the fact that this purified extract acts on cellular mediators activating cell proliferation independently of p53. Altogether, our data obtained on yeast cells over-expressing p53 demonstrate that anti-apoptotic molecules targeting p53-induced apoptosis associated with mitochondrial dysfunction and ROS overproduction are present in the aqueous extracts of Nigella seeds and in the purified aqueous C4 fraction.

Photo-activation of mitochondrial ATP synthesis

ATP production by mitochondria isolated from Saccharomyces cerevisiae cells was accelerated upon both direct and indirect mitochondrial photo-activation (MPA). The extent of direct MPA was dependent on the wavelength of excitation light. Direct MPA was created by light in cytochrome c spectral absorption bands (440, 520 and 550 nm), this light was absorbed producing electronically excited cytochrome c, and the excitation energy of the latter was used in the ATP production chain. The activity of cytochrome c was tested with 600 nm light, where cytochrome c does not absorb, and thus ATP production rate remained the same as in darkness. Note that ATP production rates were significantly larger under light at 550, 520 and 440 nm. Therefore, photo-activation of cytochrome c was the first step of MPA synthesis of ATP. Indirect MPA of ATP production also proceeded via electronically excited cytochrome c, by energy transfer from electronically excited Co/BN film to cytochrome c located in the inner mitochondrial membrane (IMM). Co/BN excitons were generated by photons absorbed by the Co/BN film, which was not in contact with the mitochondrial sample. Next, these excitons propagated along the Co/BN film to the part of the film that was in contact with the mitochondrial sample. There the exciton energy was transferred to cytochrome c located in the IMM, producing electronically excited cytochrome c. Thus, excited cytochrome c was generated in a way different from that of direct MPA. Next, the energy of excited cytochrome c was used in activated ATP synthesis, with virtually the same effect for 519 and 427 nm excitation. Thus, the first step of ATP synthesis in indirect MPA was the exciton energy transfer from Co/BN film to cytochrome c located in the IMM, producing an electronically excited cytochrome c molecule. A phenomenological mechanism of direct and indirect MPA was proposed, and the model parameters were obtained by fitting the model to the experimental data. However, more information is needed before the detailed mechanism of ATP synthesis activation by electronically excited cytochrome c could be understood. The present results support the earlier proposed hypothesis of indirect MPA of ATP production in vertebrate retina in daylight.

Contribution of the Mitochondrial Carbonic Anhydrase (MoCA1) to Conidiogenesis and Pathogenesis in Magnaporthe oryzae

The interconversion of CO₂ and HCO₃⁻ catalyzed by carbonic anhydrases (CAs) is a fundamental biochemical process in organisms. During mammalian–pathogen interaction, both host and pathogen CAs play vital roles in resistance and pathogenesis; during planta–pathogen interaction, however, plant CAs function in host resistance but whether pathogen CAs are involved in pathogenesis is unknown. Here, we biologically characterized the Magnaporthe oryzae CA (MoCA1). Through detecting the DsRED-tagged proteins, we observed the fusion MoCA1 in the mitochondria of M. oryzae. Together with the measurement of CA activity, we confirmed that MoCA1 is a mitochondrial zinc-binding CA. MoCA1 expression, upregulated with H₂O₂ or NaHCO₃ treatment, also showed a drastic upregulation during conidiogenesis and pathogenesis. When MoCA1 was deleted, the mutant ΔMoCA1 was defective in conidiophore development and pathogenicity. 3,3′-Diaminobenzidine (DAB) staining indicated that more H₂O₂ accumulated in ΔMoCA1; accordingly, ATPase genes were downregulated and ATP content decreased in ΔMoCA1. Summarily, our data proved the involvement of the mitochondrial MoCA1 in conidiogenesis and pathogenesis in the rice blast fungus. Considering the previously reported HCO₃⁻ transporter MoAE4, we propose that MoCA1 in cooperation with MoAE4 constitutes a HCO₃⁻ homeostasis-mediated disease pathway, in which MoCA1 and MoAE4 can be a drug target for disease control.

Iridium(III) complexes entrapped in liposomes trigger mitochondria-mediated apoptosis and GSDME-mediated pyroptosis

In this report, a new ligand TFBIP (TFBIP = 2-(4'-trifluoromethyl)-[1,1'-biphenyl]-4-yl)-1H-imidazo[4,5-f][1,10]phenanthroline) and its three iridium (III) complexes [Ir(ppy)₂(TFBIP)](PF₆) (Ir1, ppy = 2-phenylpyridine), [Ir(bzq)₂(TFBIP)](PF₆) (Ir2, bzq = benzo[h]quinolone) and [Ir(piq)₂(TFBIP)](PF₆) (Ir3, piq = 1-phenylisoquinoline) were synthesized and characterized. The cytotoxicity in vitro of the complexes toward several cancer cells was evaluated by 3-(4,5-dimethylthiazole-2-yl)-2,5-biphenyl tetrazolium bromide (MTT) methods. The complexes show no cytotoxicity (IC₅₀ > 100 μM) against these cancer cells. To enhance anticancer activity, these complexes were trapped in liposomes to form Ir1Lipo, Ir2Lipo and Ir3Lipo. The liposomes Ir1Lipo, Ir2Lipo and Ir3Lipo exhibit high or moderate cytotoxic activity. In particular, Ir1Lipo can effectively inhibit the cell growth with a low IC₅₀ value (< 10 μM) toward A549, HepG2, BEL-7402, B16, HeLa and SGC-7901 cells. Surprisingly, Ir1Lipo has no cytotoxic activity against the normal cell LO2 (IC₅₀ > 100 μM). The apoptosis and pyroptosis were investigated. Ir3Lipo induces apoptosis with a high early apoptotic number of 37%. The reactive oxygen species (ROS) levels, mitochondrial permeability transition pore open and mitochondrial membrane potential were detected. The intracellular Ca²⁺ concentration and release of cytochrome c were investigated. The expression of Bcl-2 (B-cell lymphoma-2) family proteins was explored by western blot. The antitumor activity in vivo of Ir1Lipo was evaluated with an inhibitory rate of 53%.

Total saponins from Tupistra chinensis baker inhibits growth of human gastric cancer cells in vitro and in vivo

ETHNOPHARMACOLOGICAL RELEVANCE

Tupistra chinensis Baker (syn. Rohdea chinensis), an antitumor folk herb mainly distributed in China, its rhizome has been historically used to treat gastric cancer. Studies showed that the steroidal saponins were the main bioactive components in the rhizome of T. chinensis. Our previous studies have confirmed that the steroidal saponins have a variety of anti-tumor activities. However, the underlying anti-tumor mechanism of the total steroidal saponins of T. chinensis (TCS) remains to be revealed.

AIM OF THE STUDY

In the present study, we studied the potential anti-proliferative activity and anti-tumor mechanism of TCS on gastric cancer in vitro and in vivo.

METHODS

In vitro, 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay was used to detect the proliferation ability of TCS on SGC-7901 cells and AGS cells. Flow cytometry were performed to analyze cell apoptosis, cell cycle, mitochondrial membrane potential and reactive oxygen species expression level. Western blotting was performed to validate the expression of proteins in related pathways. In vivo, a xenograft model was established by injecting SGC-7901 cells into nude mice.

RESULTS

In vitro, TCS inhibited the proliferation of gastric cancer cells. TCS effectively induced apoptosis by PI3K/Akt/mTOR signaling pathway in SGC-7901 cells, and promoted apoptosis via p53-mediated pathway in AGS cells. TCS also exhibited inhibitory activity in blocking the migration of gastric cancer cells. In vivo, TCS significantly inhibited the growth of xenograft tumor.

CONCLUSION

These results indicated that TCS exhibited significant anti-gastric cancer effects in vitro and in vivo.

Reversible and irreversible mitochondrial swelling in vitro

Mitochondrial activity as regards ATP production strongly depends on mitochondrial swelling (MS) mode. Therefore, this work analyzes reversible and irreversible MS using a detailed biophysical model. The reported model includes mechanical properties of the inner mitochondrial membrane (IMM). The model describes MS dynamics for spherically symmetric, axisymmetric ellipsoidal and general ellipsoidal mitochondria. Mechanical stretching properties of the IMM were described by a second-rank rigidity tensor. The tensor components were estimated by fitting to the earlier reported results of in vitro experiments. The IMM rigidity constant of ca. 0.008 dyn/nm was obtained for linear deformations. The model also included membrane bending effects, which were small compared to those of membrane stretching. The model was also tested by simulation of the earlier reported experimental data and of the system dynamics at different initial conditions, predicting the system behavior. The transition criteria from reversible to irreversible swelling were determined and tested. The presently developed model is applicable directly to the analysis of in vitro experimental data, while additional improvements are necessary before it could be used to describe mitochondrial swelling in vivo. The reported theoretical model also provides an idea of physically consistent mechanism for the permeability transport pore (PTP) opening, which depends on the IMM stretching stress. In the current study, this idea is discussed briefly, but a detailed theoretical analysis of these ideas will be performed later. The currently developed model provides new understanding of the detailed MS mechanism and of the conditions for the transition between reversible and irreversible MS modes. On the other hand, the current model provides useful mathematical tools, that may be successfully used in mitochondrial biophysics research, and also in other applications, predicting the behavior of mitochondria in different conditions of the surrounding media in vitro or cellular cyto(sarco)plasm in vivo. These mathematical tools are based on real biophysical processes occurring in mitochondria. Thus, we note a significant progress in the theoretical approach, which may be used in real biological systems, compared to the earlier reported models. Significance of this study derives from inclusion of IMM mechanical properties, which directly impact the reversible and irreversible mitochondrial swelling dynamics. Reversible swelling corresponds to reversible IMM deformations, while irreversible swelling corresponds to irreversible deformations, with eventual membrane disruption. The IMM mechanical properties are directly dependent on the membrane biochemical composition and structure. The IMM deformationas are induced by osmotic pressure created by the ionic/neutral solute imbalance between the mitochondrial matrix media and the bulk solution in vitro, or cyto(sarco)plasm in vivo. The novelty of the reported model is in the biophysical mechanism detailing ionic and neutral solute transport for a large number of solutes, which were not taken into account in the earlier reported biophysical models of MS. Therefore, the reported model allows understanding response of mitochondria to the changes of initial concentration(s) of any of the solute(s) included in the model. Note that the values of all of the model parameters and kinetic constants have been estimated and the resulting complete model may be used for quantitative analysis of mitochondrial swelling dynamics in conditions of real in vitro experiments.

Stretching tension effects in permeability transition pores of inner mitochondrial membrane

Presently a mechanism of permeability transition pore (PTP) opening was proposed and discussed. This mechanism is based on mechanical stretching of inner mitochondrial membrane (IMM) caused by mitochondrial swelling (MS). The latter is induced by osmotic pressure generated by solute imbalance between the matrix and the surrounding cyto(sarco)plasm. Modelled by the Monte-Carlo method, an IMM fragment of 350 simulated biological molecules exhibited formation of micro-domains containing two protein and seven phospholipid molecules. The energies (-0.191 eV per molecule) in these micro-domains were significantly larger than those (-0.375 eV per molecule) of other parts of the IMM fragment. Stretching forces applied to such domains expanded them much more than other parts of the IMM fragment. We identify these micro-domains as the PTPs. Both linear and nonlinear functions were used for the strain-stress relation of the IMM fragment, with nonlinear effects more important at large IMM stretching strains. Thus, two main factors are incorporated into the PTP opening mechanism: (1) presence of micro-domains in the IMM structure and (2) IMM stretching stress caused by MS. Taking into account both of these factors, the equation for the probability of PTP opening was deduced, with matrix Ca²⁺ and H⁺ ionic concentrations as its parameters. Note that the equation deduced was similar to an earlier reported empirical equation describing PTP opening dynamics. This correspondence provides support to the presently proposed mechanism. Thus, a new look at the PTP opening mechanism is provided, of interest to various research areas related to mitochondrial biophysics.

Cadmium cytotoxicity and possible mechanisms in human trophoblast HTR-8/SVneo cells

The accumulation of cadmium (Cd) in the human body through food chain can lead to adverse pregnancy outcomes. In this study, Cd cytotoxicity and its mechanisms in HTR-8/SVneo cells were investigated. Cd disrupted the cellular submicrostructure and inhibited the cell viability in a time- and dose-dependent manner. The levels of reactive oxygen species, malondialdehyde content, and the activities of glutathione peroxidase (GSH-Px) and total superoxode dismutase (T-SOD) were concentration-dependently increased by Cd. In addition, Cd dose-dependently inducedcell apoptosis and decreased cell migration and invasion capacities. Finally, Cd significantly upregulated all the genes related to oxidative stress (SOD1, ROS1, and HSPA6), inflammatory response, cell cycle, apoptosis, and migration and invasion. This study will provide insights into the prevention and treatment of pregnancy-related diseases caused by Cd intoxication.

Traumatic Brain Injury: Mechanistic Insight on Pathophysiology and Potential Therapeutic Targets

Traumatic brain injury (TBI) causes brain damage, which involves primary and secondary injury mechanisms. Primary injury causes local brain damage, while secondary damage begins with inflammatory activity followed by disruption of the blood-brain barrier (BBB), peripheral blood cells infiltration, brain edema, and the discharge of numerous immune mediators including chemotactic factors and interleukins. TBI alters molecular signaling, cell structures, and functions. Besides tissue damage such as axonal damage, contusions, and hemorrhage, TBI in general interrupts brain physiology including cognition, decision-making, memory, attention, and speech capability. Regardless of the deep understanding of the pathophysiology of TBI, the underlying mechanisms still need to be assessed with a desired therapeutic agent to control the consequences of TBI. The current review gives a brief outline of the pathophysiological mechanism of TBI and various biochemical pathways involved in brain injury, pharmacological treatment approaches, and novel targets for therapy.

In vitro renal toxicity evaluation of copper-based metal-organic framework HKUST-1 on human embryonic kidney cells

HKUST-1 is currently studied for a very diverse range of applications. Despite its exciting potential, significant concerns remain regarding the safety of HKUST-1. Therefore, human embryonic kidney 293 (HEK293) cells were used to verify the renal toxicity of HKUST-1. In this study, HKUST-1 induced concentration-dependent cytotoxic effects in HEK293 cells. The depolarization of mitochondrial membrane potential and formation of apoptotic bodies and autophagic vesicles were observed in HKUST-1-treated HEK293 cells. Oxidative (oxidative stress and haem oxygenase-1 activation) and inflammatory responses (NF-κB and NLRP3 activation) in HEK293 cells were induced by HKUST-1 exposure. In addition, the observed reduction in NAD(P)H levels in HKUST-1-treated HEK293 cells may be attributable to PARP-1 activation following DNA single- and double-strand breaks. The HKUST-1-induced depletion of zonula occludens proteins in HEK293 cells might lead to altered renal barrier integrity. The variations of α1-antitrypsin, oxidised α1-antitrypsin and NLRP3 protein expression in HEK293 cells suggested that HKUST-1 increases the risk of chronic kidney diseases. However, most of these adverse effects were significantly induced only by high HKUST-1 concentration (100 μg/mL), which do not reflect the actual exposure. Thus, the toxic risk of HKUST-1 appears to be negligible.

Effect of antioxidants on preimplantation embryo development in vitro: a review

In vitro culture of the embryo is a useful method to treat infertility that shows embryo potential for selecting the best one to transfer and successfully implantation. However, embryo development in vitro is affected by oxidative stresses such as reactive oxygen species that may damage embryo development. Antioxidants are molecules found in fruits, vegetables, and fish that play an important role in reducing oxidative processes. In the natural environment, there is a physiological antioxidant system that protects embryos against oxidative damage. This antioxidant system does not exist in vitro. Antioxidants act as free radical scavengers and protect cells or repair damage done by free radicals. Various studies have shown that adding antioxidants into embryo culture medium improves embryo development in vitro. This review article emphasizes different aspects of various antioxidants, including types, functions and mechanisms, on the growth improvement of different species of embryos in vitro.

Antimicrobial Photoinactivation of In Situ Oral Biofilms by Visible Light Plus Water-Filtered Infrared A and Tetrahydroporphyrin-tetratosylate (THPTS)

The aim of this study was to examine the effect of aPDT with visual light (VIS) + water-filtered infrared A (wIRA) as a light source, and tetrahydroporphyrin-tetratosylate (THPTS) as a photosensitizer on in situ initial and mature oral biofilms. The samples were incubated, ex situ, with THPTS for two minutes, followed by irradiation with 200 mW cm − 2 VIS + wIRA for five minutes at 37 °C. The adherent microorganisms were quantified, and the biofilm samples were visualized using live/dead staining and confocal laser scanning microscopy (CLSM). The THPTS-mediated aPDT resulted in significant decreases in both the initially adherent microorganisms and the microorganisms in the mature oral biofilms, in comparison to the untreated control samples (>99.99% each; p = 0.018 and p = 0.0066, respectively). The remaining vital bacteria significantly decreased in the aPDT-treated biofilms during initial adhesion (vitality rate 9.4% vs. 71.2% untreated control, 17.28% CHX). Of the mature biofilms, 25.67% remained vital after aPDT treatment (81.97% untreated control, 16.44% CHX). High permeability of THPTS into deep layers could be shown. The present results indicate that the microbial reduction in oral initial and mature oral biofilms resulting from aPDT with VIS + wIRA in combination with THPTS has significant potential for the treatment of oral biofilm-associated diseases.

Cellular and Molecular Events that Occur in the Oocyte during Prolonged Ovarian Storage in Sheep

Simple Summary

Establishing efficient in vitro embryo production (IVP) protocols in sheep usually requires prolonged transportation of post-mortem ovaries since adult animals are often slaughtered in abattoirs far from laboratories. In this study, different analyses were carried out to investigate important cellular and molecular aspects of hypoxic injury on excised ovaries over time in order to understand the factors jeopardizing the development of competent oocytes during prolonged transport times. We observed that, when ovaries were stored for more than 7 h, the quality and developmental potential of oocytes and cumulus cells were greatly reduced. Moreover, the use of medium TCM199 over saline solution also had deleterious effects. Beyond transport time, strategies aimed at reducing these damages may improve oocyte quality and developmental competence.

Abstract

For the past two decades, there has been a growing interest in the application of in vitro embryo production (IVP) in small ruminants such as sheep. To improve efficiency, a large number abattoir-derived ovaries must be used, and long distances from the laboratory are usually inevitable when adult animals are used. In that scenario, prolonged sheep ovary transportation may negatively affect oocyte developmental competence. Here, we evaluated the effect of ovary storage time (3, 5, 7, 9, 11 and 13 h) and the medium in which they were transported (TCM199 and saline solution) on oocyte quality. Thus, live/dead status, early apoptosis, DNA fragmentation, reduced glutathione (GSH) and reactive oxygen species (ROS) content, caspase-3 activity, mitochondrial membrane potential and distribution, and relative abundance of mRNA transcript levels were assessed in oocytes. After in vitro maturation (IVM), cumulus cell viability and quality, meiotic and fertilization competence, embryo rates and blastocyst quality were also evaluated. The results revealed that, after 7 h of storage, oocyte quality and developmental potential were significantly impaired since higher rates of dead oocytes and DNA fragmentation and lower rates of viable, matured and fertilized oocytes were observed. The percentage of cleavage, blastocyst rates and cumulus cell parameters (viability, active mitochondria and GSH/ROS ratio) were also decreased. Moreover, the preservation of ovaries in medium TCM199 had a detrimental effect on cumulus cells and oocyte competence. In conclusion, ovary transport times up to 5 h in saline solution are the most adequate storage conditions to maintain oocyte quality as well as developmental capacity in sheep. A strategy to rescue the poor developmental potential of stored oocytes will be necessary for successful production of high-quality embryos when longer ovarian preservation times are necessary.

Platinum nanoparticles induced genotoxicity and apoptotic activity in human normal and cancer hepatic cells via oxidative stress-mediated Bax/Bcl-2 and caspase-3 expression

Platinum nanoparticles (PtNPs) attract much attention due to their excellent biocompatibility and catalytic properties, but their toxic effects on normal (CHANG) and cancerous (HuH-7) human liver cells are meagre. The cytotoxic and apoptotic effects of PtNPs (average size, 3 nm) were determined in CHANG and HuH-7 cells. After treating these cells were with PtNPs (10, 50, 100, 200, and 300 μg/mL) for 24 and 48 hours, we observed dose- and time-dependent cytotoxicity, as evaluated by using (3-[4, 5-dimethylthiazol-2-yl]-2, 5-diphenyltetrazolium bromide, a tetrazole) (MTT) and neutral red uptake (NRU) assays. The production of reactive oxygen species (ROS) was increased in both cells after treatment with the above dose of PtNPs for 24 and 48 hours. Determination of morphological changes of cells, chromosome condensation, mitochondrial membrane potential, and caspase-3 assays showed that PtNPs induce cytotoxicity and apoptosis in CHANG and HuH-7 cells by altering the cell morphology and density, increasing cell population in apoptosis, and causing chromosome condensation. Furthermore, we have studied fragmentation of DNA using alkaline single cell gel electrophoresis and expression of apoptotic genes by real-time PCR (RT-PCR). The percentage of DNA fragmentation was more at 300 μg/mL for 48 hours in both cells, but slightly more fragmentation was found in HuH-7 relative to CHANG cells. Considering all of the above parameters, PtNPs elicited cytotoxicity on CHANG and HuH-7 cells by blocking cell proliferation and inducing apoptosis. Thus this study may be useful in in vitro laboratory studies using cell lines for screening the genotoxic and apoptotic potential of nanoparticles.

Protective potency of ascorbic acid supplementation against cytotoxicity and DNA fragmentation induced by triphenyltin on human liver carcinoma cells

Agrochemicals are one the most significant sources of environmental pollution. Cytotoxicity and genotoxicity are the serious side effects of fungicide. In the current study, I have evaluated acute cytotoxicity and genotoxicity of triphenyltin (TPT) on human hepatic carcinoma (HepG2) cells and the ameliorating effect of ascorbic acid for 24 h. In this experiment, I have exposed HepG2 cells to ascorbic acids (50, 100, and 200 μM) simultaneously and 24 h prior triphenyltin (TPT, 400 ng/ml) exposure for 24 h to determine the protective effect of ascorbic acid by using MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) and NRU (neutral red uptake) assays. Oxidative stress, such as intracellular reactive oxygen species and glutathione levels, was measured in HepG2 cells. The intracellular reactive oxygen species was evaluated using fluorescent probe DCFDA (6-carboxy-2',7' dichloro-dihydrofluorescein diacetate). Apoptosis and genotoxicity effects of TPT in HepG2 cells were determined using flow cytometry and comet assay. The result of these experiments showed that the TPT compound (400 ng/ml) induced cytotoxicity, oxidative stress and apoptosis, and DNA damage in HepG2 cells.Ascorbic acid reduced cytotoxicity, oxidative stress, apoptosis, and genotoxicity induced by TPT. Thus, ascorbic acid is a potent antioxidant, and it showed a significant protective effect against toxicity induced by TPT in HepG2 cells.

Particulate Matter Induces Tissue OxInflammation: From Mechanism to Damage

Significance: Oxidative stress and oxidative damage are central hypothetical mechanisms for the adverse effects of airborne particulate matter (PM). Activation of inflammatory cells capable of generating reactive oxygen and nitrogen species is another proposed damage pathway. Understanding the interplay between these responses can help us understand the adverse health effects attributed to breathing polluted air. Recent Advances: The consequences of PM exposure on different organs are oxidative damage, decreased function, and inflammation, which can lead to the development/exacerbation of proinflammatory disorders. Mitochondrial damage is also an important event in PM-induced cytotoxicity. Critical Issues: Reactive oxygen species (ROS) are generated during phagocytosis of the particles, leading to enhancement of oxidative stress and triggering the inflammatory response. The activation of inflammatory signaling pathways results in the release of cytokines and other mediators, which can further induce ROS production by activating endogenous enzymes, leading to a positive feedback loop, which can aggravate the effects triggered by PM exposure. Future Directions: Further research is required to elucidate the exact mechanisms by which PM exposure results in adverse health effects, in terms of the relationship between the redox responses triggered by the presence of the particles and the inflammation observed in the different organs, so the development/exacerbation of PM-associated health problems can be prevented.

Protective effect assessment of Moringa oleifera against cadmium-induced toxicity in HCT116 and HEK293 cell lines

The cadmium (Cd) is considered one of the widespread toxic metals in the aquatic and terrestrial environments, which is due to its long half-life, non-degradable characteristic, and toxicity. Aqueous extract of freeze-dried Moringa oleifera (Moringaceae family) leaves was examined for protective effect and antioxidant power against Cd toxicity. The results revealed that Moringa aqueous extract (MAE) has contents of total polyphenols and flavonoids about 30.14 mg GAE/g and 18.35 mg QE/g respectively. Furthermore, phenolic compounds in leaves of Moringa were studied using a high-performance liquid chromatography coupled with mass spectrometry (HPLC-MS). Results showed that the largest number of phenolic compounds determined in leaves of Moringa belongs to flavonoids. Moreover, biological properties were determined by radical scavenging capacity (DPPH) and ferric-reducing power (FRAP). Cytoprotective effect and antioxidant power of Moringa extract were assessed using the mitochondrial activity testing method (MTT test), malondialdehyde (MDA), and reactive oxygen species (ROS) production. Results indicate that Moringa aqueous extract have a significant (i) proliferative, (ii) antioxidant, and (iii) cytoprotective effect on HCT116 and HEK293 cells against metal toxicity.

The implication of ROS production on triflumuron-induced oxidative stress and genotoxicity in human colon carcinoma (HCT-116) cells

The aim of this study is to evaluate the cytotoxic and the genotoxic effects of triflumuron (TFM) on human colon carcinoma cells (HCT-116). Indeed, TFM is used to protect vegetables, fruits, and domestic animals against a large spectrum of parasites causing animal and human disorders. However, studies revealing its toxicity and its mode of action in mammalian systems remain very limited. We monitored our work with the cytotoxicity assay starting with the cell viability test, the ROS generation, the malondialdehyde (MDA) production, the DNA fragmentation, and the measurement of some antioxidant enzymes activities such as catalase, superoxide dismutase, and the glutathione S-transferase. Also, we measured the mitochondrial transmembrane potential. We showed that TFM induced a dose-dependent cell death. This decrease in cell viability was accompanied by a significant reduction in the mitochondrial membrane potential. We also have shown that TFM induced oxidative stress as revealed by the generation of reactive oxygen species, the increase of the MDA levels, and the activation of the antioxidant enzymes. Moreover, our results indicated that TFM induced DNA damage in HCT-116 cells as monitored by the comet assay. We demonstrate, for the first time, the cytotoxic and the genotoxic potentials of TFM on human cultured cells.

MFP-FePt-GO Nanocomposites Promote Radiosensitivity of Non-Small Cell Lung Cancer Via Activating Mitochondrial-Mediated Apoptosis and Impairing DNA Damage Repair

Background: Recent advances in nanomedicine provided promising alternatives for tumor treatment to improve the survival and life quality of cancer patients. This study was designed to explore the insight mechanisms of the anti-tumor effects of the novel nanocomposites (NCs) MFP-FePt-GO with non-small cell lung cancer (NSCLC).

Methods: A chemical co-reduction method was applied to the synthesis process of MFP-FePt-GO NCs. The chemical synthesis efficiency and morphology of the NCs were measured with spectroscope and transmission electron microscope. Colony formation assay and cell apoptosis were conducted to assess the radiosensitivity effect of NCs with radiation. Then, we detected cell mitochondrial membrane potential and reactive oxygen species (ROS) level by flow cytometry to further explore the cause of cell death. Immunofluorescence staining and Confocal were carried out to determine the DNA damage repair. A Lewis lung carcinoma animal model was used to measure safety and anti-tumor efficiency in vivo.

Results: The novel NCs MFP-FePt-GO designed on a lamellar-structure magnetic graphene oxide and polyethylene glycol drug delivery system was synthesized and functionalized for co-delivery of metronidazole and 5-fluorouracil. While no severe allergies, liver and kidney damage, or drug-related deaths were observed, MFP-FePt-GO NCs promoted radiosensitivity of NSCLC cells both in vivo and in vitro. It improved the effects of radiation via activating intrinsic mitochondrial-mediated apoptosis and impairing DNA damage repair. This NCs also induced a ROS burst, which suppressed the antioxidant protein expression and induced cell apoptosis. Furthermore, MFP-FePt-GO NCs prevented NSCLC cell migration and invasion.

Conclusion: MFP-FePt-GO NCs showed a synergistic anti-tumor effect with radiation to eliminate tumors. With good safety and efficacy, this novel NCs could be a potential radiosensitive agent for NSCLC patients.

Triflumuron induces cytotoxic effects on hepatic and renal human cell lines

Insect growth regulator insecticides are a new class of pesticides, commonly used around the world to control insect damages. Among those compounds, we focused our interest on triflumuron (TFM), which is less toxic than other conventional insecticides. However, not much is known about its toxic effects on mammalian systems. Therefore, our study aimed toward evaluating the cytotoxic and genotoxic effects of TFM using two different cell lines, the human renal embryonic cells (HEK 293) and hepatocytes (Hep G2). We showed, according to the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, that TFM reduced significantly the cell viability and increased the reactive oxygen species generation, malondialdehyde levels, and mitochondrial membrane potential in both cell lines. The antioxidant system was disturbed as assessed by the increased activities in both catalase and superoxide dismutase. We demonstrated also, that TFM is an inductor of DNA damages quantified by the comet assay. Moreover, we showed an overexpression of proapoptotic Bax and a decrease in antiapoptotic Bcl-2 expression. As a conclusion, we demonstrate that the liver presents the major target organ to TFM, in which the cytotoxicity and the genotoxic effects were significantly higher in hepatic cells than in renal cells and by consequence its uses must be controlled.

GPR119 Is a Potent Regulator of Human Sebocyte Biology

We have shown previously that endocannabinoids promote sebaceous lipogenesis, and sebocytes are involved in the metabolism of the endocannabinoid-like substance oleoylethanolamide (OEA). OEA is an endogenous activator of GPR119, a recently deorphanized receptor, which currently is being investigated as a promising antidiabetic drug target. In this study, we investigated the effects of OEA as well as the expression and role of GPR119 in human sebocytes. We found that OEA promoted differentiation of human SZ95 sebocytes (elevated lipogenesis, enhanced granulation, and the induction of early apoptotic events), and it switched the cells to a proinflammatory phenotype (increased expression and release of several proinflammatory cytokines). Moreover, we could also demonstrate that GPR119 was expressed in human sebocytes, and its small interfering RNA-mediated gene silencing suppressed OEA-induced sebaceous lipogenesis, which was mediated via c-Jun N-terminal kinase, extracellular signal-regulated kinase 1/2, protein kinase B, and CRE-binding protein activation. Finally, our pilot data demonstrated that GPR119 was downregulated in the sebaceous glands of patients with acne, arguing that GPR119 signaling may indeed be disturbed in acne. Collectively, our findings introduce the OEA/GPR119 signaling as a positive regulator of sebocyte differentiation and highlight the possibility that dysregulation of this pathway may contribute to the development of seborrhea and acne.

A cascade-reaction enabled synergistic cancer starvation/ROS-mediated/chemo-therapy with an enzyme modified Fe-based MOF

Synergistic cancer starvation/ROS-mediated/chemo-therapy is developed through a cascade reaction with enzyme glucose oxidase (GOX) modified on the surface of an Fe-based metal organic framework (MOF(Fe)) and drug camptothecin (CPT) loaded into the cavities of MOF(Fe). Once internalized by tumor cells, GOX catalyzes endogenous glucose into hydrogen peroxide (H2O2) and gluconic acid (H+) enabling starvation therapy through choking off energy (glucose) supply. Meanwhile, the acidic micro-environment of tumor enhanced by the generated H+ degrades the MOF(Fe) simultaneously releasing CPT for chemotherapy and Fe3+, catalyzing H2O2 into one of the strongest reactive oxygen species (ROS) ˙OH enabling ROS-mediated therapy. Both in vitro and in vivo results show remarkable tri-modal synergistic anticancer effects. This work may shed some light on the development of novel multi-modal cancer therapies without any external intervention.

Plumbagin attenuated oxygen-glucose deprivation/reoxygenation-induced injury in human SH-SY5Y cells by inhibiting NOX4-derived ROS-activated NLRP3 inflammasome

Plumbagin (PLB), an alkaloid obtained from the roots of the plants of Plumbago genus, is an inhibitor of NADPH oxidase 4 (NOX4). This study aimed to investigate the beneficial effect of PLB against oxygen-glucose deprivation/reoxygenation (OGDR)-induced neuroinjury in human SH-SY5Y neuronal cultures. Our results showed that OGD/R stimulated NOX4 protein expression and reactive oxygen species (ROS) production in SH-SY5Y cells, whereas increased 4-hydroxynonenal (4-HNE) and malondialdehyde (MDA) production, resulting in the activation of the NLRP3 inflammasome. And PLB pretreatment reduced the ROS production by regulating the expression of NOX4 and downregulated NF-κB signaling which was induced by OGDR. Furthermore, PLB inhibited OGDR induced NLRP3 inflammasome activation but not PARP1. Overall, PLB improved OGDR induced neuroinjury by inhibiting NOX4-derived ROS-activated NLRP3 inflammasome.

Traumatic Brain Injuries: Pathophysiology and Potential Therapeutic Targets

Traumatic brain injury (TBI) remains one of the leading causes of morbidity and mortality amongst civilians and military personnel globally. Despite advances in our knowledge of the complex pathophysiology of TBI, the underlying mechanisms are yet to be fully elucidated. While initial brain insult involves acute and irreversible primary damage to the parenchyma, the ensuing secondary brain injuries often progress slowly over months to years, hence providing a window for therapeutic interventions. To date, hallmark events during delayed secondary CNS damage include Wallerian degeneration of axons, mitochondrial dysfunction, excitotoxicity, oxidative stress and apoptotic cell death of neurons and glia. Extensive research has been directed to the identification of druggable targets associated with these processes. Furthermore, tremendous effort has been put forth to improve the bioavailability of therapeutics to CNS by devising strategies for efficient, specific and controlled delivery of bioactive agents to cellular targets. Here, we give an overview of the pathophysiology of TBI and the underlying molecular mechanisms, followed by an update on novel therapeutic targets and agents. Recent development of various approaches of drug delivery to the CNS is also discussed.

Apoptosis and Cell Death (Mechanisms, Pharmacology and Promise for the Future)

Rapidly growing body of evidence on cell death mechanisms and its disorders during last five years has replaced old paradigms and opened new horizons in medicine. Identification of different morphological and signaling aspects, as well as variances in requirement for energy enabled us to construct a theory of three main types of cell death: necrosis, apoptosis, and lysosomal cell death. Mitochondria, certain oncoproteins such as Bcl-2 family, and special catabolic enzymes participating in cellular demise might serve as targets for pharmacological manipulation. Upregulation or downregulation of programmed cell death has been implicated in ischemic, neurodegenerative, and autoimmune disorders, as well as in oncology and chronic inflammation. This minireview brings a short overview of genesis and development of theories on programmed cell death and apoptosis, summarizes basic relevant facts on apoptotic mechanisms and draws a new hypothesis on possible implication in medicine and surgery.

Enforced lysosomal biogenesis rescues erythromycin- and clindamycin-induced mitochondria-mediated cell death in human cells

Antibiotics are the front-line treatment against many bacterial infectious diseases in human. The excessive and long-term use of antibiotics in human cause several side effects. It is important to understand the underlying molecular mechanisms of action of antibiotics in the host cell to avoid the side effects due to the prevalent uses. In the current study, we investigated the crosstalk between mitochondria and lysosomes in the presence of widely used antibiotics: erythromycin (ERM) and clindamycin (CLDM), which target the 50S subunit of bacterial ribosomes. We report here that both ERM and CLDM induced caspase activation and cell death in several different human cell lines. The activity of the mitochondrial respiratory chain was compromised in the presence of ERM and CLDM leading to bioenergetic crisis and generation of reactive oxygen species. Antibiotics treatment impaired autophagy flux and lysosome numbers, resulting in decreased removal of damaged mitochondria through mitophagy, hence accumulation of defective mitochondria. We further show that over-expression of transcription factor EB (TFEB) increased the lysosome number, restored mitochondrial function and rescued ERM- and CLDM-induced cell death. These studies indicate that antibiotics alter mitochondria and lysosome interactions leading to apoptotsis and may develop a novel approach for targeting inter-organelle crosstalk to limit deleterious antibiotic-induced side effects.

Inhibition of the mitochondrial complex-1 protects against carbon tetrachloride-induced acute liver injury

Mitochondrial dysfunction has been documented to play a crucial role in the pathogenesis of liver injury. In the present study, we investigated the role of rotenone, a mitochondrial complex-1 inhibitor, in carbon tetrachloride (CCl₄) -induced acute liver injury, as well as the underlying mechanisms. Before CCl₄ administration, the mice were pretreated with rotenone at a dose of 250 ppm in food for three days. Then CCl₄ was administered to the mice for 16 h by intraperitoneal injection. The liver injury, mitochondrial status, oxidative stress, and inflammation were examined. Strikingly, CCl₄ treatment markedly induced liver injury as shown by enhanced serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) and morphological lesions (HE stating), which was significantly attenuated by rotenone treatment in line with the reduced activity of mitochondrial complex-1. Meanwhile, oxidative stress markers of malondialdehyde (MDA), 4-hydroxynonenal (HNE), and dihydroethidium (DHE) and the inflammatory markers of IL-1β, MCP-1, TNF-α, TLR-4, and IL-6 were also significantly suppressed by rotenone. More importantly, the mitochondrial abnormalities shown by the reduction of SOD2, mitochondrial transcription factor A (TFAM), mitochondrial NADH dehydrogenase subunit 1 (mtND1), and Cytb were significantly restored, indicating that rotenone protected against mitochondrial damage induced by CCl₄ in liver. Moreover, rotenone treatment alone did not significantly alter liver morphology and liver enzymes ALT and AST. CYP2E1, a metabolic enzyme of CCl₄, was also not significantly affected by rotenone. In conclusion, rotenone protected the liver from CCl₄-induced damage possibly by inhibiting the mitochondrial oxidative stress and inflammation.

Apoptosis-promoting effect of rituximab-conjugated magnetic nanoprobes on malignant lymphoma cells with CD20 overexpression

Background

Cancer targeting nanoprobes with precisely designed physicochemical properties may show enhanced pharmacological targeting and therapeutic efficacy. As a widely used commercialized antibody, rituximab has been in clinical use for three decades and has lengthened or even saved thousands of lives. However, many people cannot benefit from rituximab treatment because of drug resistance or side effects.

Methods

In this study, a 13-nm rituximab-conjugated magnetic nanoparticle was developed as a therapeutic nanoprobe targeting CD20 overexpressing malignant lymphoma cells to enhance the treatment effects of rituximab. The magnetic cores (2,3-dimercaptosuccinicacid modified Fe₃O₄ nanoparticles, Fe₃O₄@DMSA) of the nanoprobes with an average diameter of 6.5 nm were synthesized using a co-precipitation method. Rituximab was then conjugated on the surface of Fe₃O₄@DMSA using a cross-linking agent (carbodiimide/N-hydroxysulfosuccinimide sodium salt). Based on theoretical calculations, approximately one antibody was coupled with one nanoparticle, excluding the multivalent antibody effect.

Results

Cell targeting experiments and magnetic resonance (MR) signal and T2 measurements showed that the Fe₃O₄@DMSA@Ab nanoprobes have specific binding affinity for CD20-positive cells. Compared to rituximab and Fe₃O₄@DMSA, Fe₃O₄@DMSA@Ab nanoprobes significantly reduced cell viability and promoted Raji cell apoptosis. Initiating events of apoptosis, including increased intracellular calcium and reactive oxygen species, were observed in nanoprobe-treated Raji cells. Nanoprobe-treated Raji cells also showed the most drastic decrease in mitochondrial membrane potential and Bcl-2 expression, compared to rituximab and Fe₃O₄@DMSA-treated Raji cells.

Conclusion

These results indicate that Fe₃O₄@DMSA@Ab nanoprobes have the potential to serve as MRI tracers and therapeutic agents for CD20-positive cells.

Swertiamarin ameliorates carbon tetrachloride-induced hepatic apoptosis via blocking the PI3K/Akt pathway in rats

Swertiamarin (STM) is an iridoid compound that is present in the Gentianaceae swertia genus. Here we investigated antiapoptotic effects of STM on carbon tetrachloride (CCl₄)-induced liver injury and its possible mechanisms. Adult male Sprague Dawley rats were randomly divided into a control group, an STM 200 mg/kg group, a CCl₄ group, a CCl₄+STM 100 mg/kg group, and a CCl₄+STM 200 mg/kg group. Rats in experimental groups were subcutaneously injected with 40% CCl₄ twice weekly for 8 weeks. STM (100 and 200 mg/kg per day) was orally given to experimental rats by gavage for 8 consecutive weeks. Hepatocyte apoptosis was determined by TUNEL assay and the expression levels of Bcl-2, Bax, and cleaved caspase-3 proteins were evaluated by western blot analysis. The expression of TGF-β1, collagen I, collagen III, CTGF and fibronectin mRNA were estimated by qRT-PCR. The results showed that STM significantly reduced the number of TUNEL-positive cells compared with the CCl₄ group. The levels of Bax and cleaved caspase-3 proteins, and TGF-β1, collagen I, collagen III, CTGF, and fibronectin mRNA were significantly reduced by STM compared with the CCl₄ group. In addition, STM markedly abrogated the repression of Bcl-2 by CCl₄. STM also attenuated the activation of the PI3K/Akt pathway in the liver. These results suggested that STM ameliorated CCl₄-induced hepatocyte apoptosis in rats.

Green Platinum Nanoparticles Interaction With HEK293 Cells: Cellular Toxicity, Apoptosis, and Genetic Damage

Metal nanoparticles are widely used in industry, agriculture, textiles, drugs, and so on. The adverse effect of green platinum nanoparticles on human embryonic kidney (HEK293) cells is not well established. In the current study, green platinum nanoparticles were synthesized using leaf extract of Azadirachta indica L. Green platinum nanoparticles were characterized by dynamic light scattering and transmission electron microscope. The cytotoxicity of green platinum nanoparticle was observed in HEK293 cells by applying 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) and Neutral red uptake (NRU) assays. Cell viability of the cells was decreased in a concentration and duration-dependent manner. Generation of reactive oxygen species (ROS) in HEK293 cells due to green platinum nanoparticles was examined using fluorescent dye 2,7-dichlorofluorescein diacetate (DCFDA), and ROS was increased according to exposure pattern. The cytotoxicity of HEK293 cells was correlated with increased caspase 3, depolarization of mitochondrial membrane potential, and DNA fragmentation. The abovementioned finding confirmed that mitochondria play an important role in genotoxicity and cytotoxicity induced by nanoparticles in HEK293 cells. Further, we determined other oxidative stress biomarkers, lipid peroxide (LPO) and glutathione (GSH); LPO was increased and GSH was decreased in HEK293 cells. It is also important to indicate that HEK293 cells appear to be more susceptible to green platinum nanoparticles exposure after 24 hours. This result provides a dose- and time-dependent apoptosis and genotoxicity of green nanoparticles on HEK293 cells.

Dibenzoxanthenes induce apoptosis and autophagy in HeLa cells by modeling the PI3K/Akt pathway

A new series of dibenzoxanthene derivatives 4a-4d (4a: 1-oxo-5-bromo-11-cyano-13c-methoxy-1,13c-dihydroxyl-dibenzo[a,kl]xanthene, 4b: 1-oxo-5-bromo-11-cyano-13c-ethoxy-1,13c-dihydroxyl-dibenzo[a,kl]xanthene, 4c: 1-oxo-5-bromo-11-cyano-13c-propoxy-1,13c-dihydroxyl-dibenzo[a,kl]xanthene and 4d: 1-oxo-5-bromo-11-cyano-13c-butoxy-1,13c-dihydroxyl-dibenzo[a,kl]xanthene) were synthesized and the molecular mechanisms of anti-cancer activities were investigated. These compounds showed excellent anti-tumor activity against A549, Eca-109, HeLa, HepG2 and SGC-7901 cell lines. Compounds 4a-4d could effectively inhibit the migration and invasion of HeLa cells in wound healing and transwell assays. Compounds induced the DNA damage and arrested in cell cycle distribution at G0/G1 phase. Apoptosis induced by compounds was detected using morphological observation of nuclear changes and FITC-Annexin V/PI staining. Additionally, compounds also induced the autophagy of HeLa cells through observing AO staining and upregulated the expression of LC3II and Beclin-1 proteins. Furthermore, treatment with autophagy inhibitor 3-methyladenine induced an obvious decrease in apoptotic rate in HeLa cells. This indicated that autophagy further promoted the HeLa cells apoptosis. Compounds 4a-4d enhanced the intracellular Ca²⁺ and ROS. Then the mitochondrial membrane potential of HeLa cells was depolarized and the cytochrome C was released from mitochondria into cytoplasm. Activities of the apoptotic factors Bcl-2, Bax, caspase-3 were measured using western blotting. After HeLa cells were exposed to compounds, the expressions of PI3K and Akt protein were decreased. Compounds exhibit anti-cancer activity via apoptosis and autophagy through inhibition of PI3K/Akt signaling pathway in HeLa cells.

Apoptotic Mechanisms in Neurodegeneration: Possible Relevance to Glaucoma

Deprenyl, a monoamine oxidase inhibitor used in the treatment of Parkinson's disease, along with its primary metabolite desmethyldeprenyl (DES) have been shown to reduce neuronal apoptosis by a mechanism that requires gene transcription and involves the maintenance of mitochondrial membrane potential. This review article explores the mechanisms by which DES maintains mitochondrial membrane potential. Mediated by GAPDH binding, DES increases mitochondrial BCL-2 and BCL-xL levels and decreases BAX levels thereby preventing the permeability transition pore (PTP) form opening and preventing apoptotic degradation. The favorable effects of deprenyl on neuronal apoptosis suggests the therapeutic potential of designing compounds with the capacity to alter the configurations of pro-apoptosis or anti-apoptotic proteins.

Single-walled carbon nanohorn aggregates promotes mitochondrial dysfunction-induced apoptosis in hepatoblastoma cells by targeting SIRT3

Single-walled carbon nanohorns (SWNHs) can accumulate in a variety of cell types or tissues and exert biological effects, which have been demonstrated to induce apoptosis in hepatoblastoma cells. However, the role and molecular mechanisms of SWNHs remain unclear. The mitochondrion is an important subcellular structure and may contribute to apoptosis that is induced by SWNHs in hepatoblastoma cells. To address this question, the mitochondrial function of HepG2 or L02 cells that were treated with SWNHs was examined. The results indicated that SWNHs were able to decrease the mitochondrial membrane potential and suppress the activity of the Na⁺/K⁺-ATPase. Secondly, HepG2 cells and L02 cells were treated with SWNHs in vivo and in vitro. The expression of mitochondrial-associated proteins [acyl-CoA synthetase short chain family member 1, Bax, cytochrome C (CYT-C), sodium channel epithelial 1α subunit, sirtuin 3 (SIRT3) and voltage-dependent anion channel 1] was analyzed by western blotting and immunohistochemical staining. The results revealed that SWNH treatment was able to alter the expression of multiple mitochondrial apoptotic pathway-associated proteins in HepG2 cells. SWNH treatment was able upregulate the expression of SIRT3, CYT-C and VDAC1 and downregulate the expression of AceCS2, but it had a more stable effect on SIRT3. However, similar findings were not observed in L02 cells. Therefore, the data from the present study indicated that SWNHs might be used as a safe anticancer agent, where it is able to trigger mitochondrial dysfunction-induced apoptosis by upregulating SIRT3 expression in HepG2 cells.

The antioxidant, aged garlic extract, exerts cytotoxic effects on wild-type and multidrug-resistant human cancer cells by altering mitochondrial permeability

Aged garlic extract (AGE) has been shown to possess therapeutic properties in cancer; however its mechanisms of action are unclear. In this study, we demonstrate by MTT assay that AGE exerts an anti-proliferative effect on a panel of both sensitive and multidrug-resistant (MDR) human cancer cell lines and enhances the effects of hyperthermia (42˚C) on M14 melanoma cells. The evaluation of the mitochondrial activity in whole cancer cells treated with AGE, performed by cytofluorimetric analysis in the presence of the lipophilic cationic fluorochrome JC-1, revealed the occurrence of dose-dependent mitochondrial membrane depolarization. Membrane potential was measured by the TPP+ selective electrode. In order to shed light on its mechanisms of action, the effects of AGE on isolated rat liver mitochondria were also examined. In this regard, AGE induced a mitochondrial membrane hyperpolarization of approximately 15 mV through a mechanism that was similar to that observed with the ionophores, nigericin or salinomycin, by activating an exchange between endogenous K+ with exogenous H+. The prolonged incubation of the mitochondria with AGE induced depolarization and matrix swelling, indicative of mitochondrial permeability transition induction that, however, occurs through a different mechanism from the well-known one. In particular, the transition pore opening induced by AGE was due to the rearrangement of the mitochondrial membranes following the increased activity of the K+/H+ exchanger. On the whole, the findings of this study indicate that AGE exerts cytotoxic effects on cancer cells by altering mitochondrial permeability. In particular, AGE in the mitochondria activates K+/H+ exchanger, causes oxidative stress and induces mitochondrial permeability transition (MPT).