Homocysteine and cytosolic GSH depletion induce apoptosis and oxidative toxicity through cytosolic calcium overload in the hippocampus of aged mice: involvement of TRPM2 and TRPV1 channels

Silver nanoparticles stimulate 5-Fluorouracil-induced colorectal cancer cells to kill through the upregulation TRPV1-mediated calcium signaling pathways

The involvement of the TRP vanilloid 1 (TRPV1) cation channel on the 5-Fluorouracil (5-FU)-caused Ca2+ signals through the activation of the apoptotic signaling pathway and stimulating the mitochondrial Ca2+ and Zn2+ accumulation-induced reactive oxygen species (ROS) productions in several cancer cells, except the colorectal cancer (HT-29) cell line, was recently reported. I aimed to investigate the action of silver nanoparticles (SiNPs) and 5-FU incubations through the activation of TRPV1 on ROS, apoptosis, and cell death in the HT-29 cell line. The cells were divided into four groups: control, SiNP (100 µM for 48 h), 5-FU (25 μM for 24 h), and 5-FU + SiNP. SiNP treatment through TRPV1 activation (via capsaicin) stimulated the oxidant and apoptotic actions of 5-FU in the cells, whereas they were diminished in the cells by the TRPV1 antagonist (capsazepine) treatment. The apoptotic and cell death actions of 5-FU were determined by increasing the propidium iodide/Hoechst rate, caspase-3, -8, and -9 activations, mitochondrial membrane depolarization, lipid peroxidation, and ROS, but decreasing the glutathione and glutathione peroxidase. The increase of cytosolic free Ca2+ and Zn2+ into mitochondria via the stimulation of TRPV1 current density increased oxidant and apoptotic properties of 5-FU in the cells. For the therapy of HT-29 tumor cells, I found that the combination of SiNPs and 5-FU was synergistic via TRPV1 activation.

Synergic actions of botulinum neurotoxin A and oxaliplatin on colorectal tumour cell death through the upregulation of TRPM2 channel-mediated oxidative stress

Botulinum neurotoxin A (BoNT) is being shown to have anticancer action as a potential adjuvant treatment. The transient receptor potential (TRP) melastatin 2 (TRPM2) stimulator action of BoNT was reported in glioblastoma cells, but not in colorectal cancer (HT29) cells. By activating TRPM2, we evaluated the impacts of BoNT and oxaliplatin (OXA) incubations on oxidant and apoptotic values within the HT29 cells. Control, BoNT (5 IU for 24 h), OXA (50 μM for 24 h) and their combinations were induced. We found that TRPM2 protein is upregulated and mediates enhanced BoNT and OXA-induced Ca2+ entry in cells as compared to control cells. The increase of free reactive oxygen species (ROS), but the decrease of glutathione is the main ROS responsible for TRPM2 activation on H29 exposure to oxidative stress. BoNT and OXA-mediated Ca2+ entry through TRPM2 stimulation in response to H2 O2 results in mitochondrial Ca2+ overload, followed by mitochondrial membrane depolarization, apoptosis and caspase-3/-8/-9, although they were diminished in the TRPM2 antagonist groups (N-(p-amylcinnamoyl)anthranilic acid and carvacrol). In conclusion, by increasing the susceptibility of HT29 tumour cells to oxidative stress and apoptosis, the combined administration of BoNT and OXA via the targeting of TRPM2 may offer a different approach to kill the tumour cells.

Investigation the effects of 2-aminoethoxydiphenyl borate (2-APB) on aminoglycoside nephrotoxicity

Investigation the protective effect of transient receptor potential channel modulator 2-Aminoethoxydiphenyl Borate (2-APB) on aminoglycoside nephrotoxicity caused by reactive oxygen species, calcium-induced apoptosis and inflammation was aimed. Forty Wistar rats were divided (n=8) as follows: Control group; DMSO group; 2-APB group; Gentamicin group (injected 100 mg/kg gentamicin intramuscularly for 10 days); Gentamicin+ 2-APB group (injected 2 mg/kg 2-APB intraperitoneally, then after 30 minutes 100 mg/kg gentamicin was injected intramuscularly for 10 days). Blood samples were collected for biochemical analyses, kidney tissue samples were collected for light, electron microscopic and immunohistochemical investigations. In gentamicin group glomerular degeneration, tubular dilatation, vacuolization, desquamation of tubular cells and hyaline cast formation in luminal space and leukocyte infiltration were seen. Disorganization of microvilli of tubular cells, apical cytoplasmic blebbing, lipid accumulation, myelin figure like structure formation, increased lysosomes, mitochondrial swelling and disorganization of cristae structures, apoptotic changes and widening of intercellular space were found. TNF-α, IL-6 and caspase 3 expressions were increased. BUN and creatinine concentrations were increased. Increase in MDA levels and decrease in SOD activities were determined. Even though degeneration still continues in gentamicin+2-APB treatment group, severity and the area it occupied were decreased and the glomerular and tubule structures were generally preserved. TNF-α, IL-6, caspase 3 immunoreactivities and BUN, creatinine, MDA concentrations were reduced and SOD activities were increased markedly compared to gentamicin group. In conclusion, it has been considered that 2-APB can prevent gentamicin mediated nephrotoxicity with its anti-oxidant, anti-apoptotic and anti-inflammatory effects.

The rare-earth yttrium induces cell apoptosis and autophagy in the male reproductive system through ROS-Ca2+-CamkII/Ampk axis

China has the world's largest reserves of rare earth elements (REEs), but widespread mining and application of REEs has led to an increased risk of potential pollution. Yttrium (Y), the first heavy REEs to be discovered, poses a substantial threat to human health. Unfortunately, little attention has been given to the impact of Y on human reproductive health. In this study, we investigated the toxic effects of YCl3 on mouse testes and four types of testicular cells, including Sertoli, Leydig, spermatogonial and spermatocyte cells. The results showed that YCl3 exposure causes substantial damage to mouse testes and induces apoptosis and autophagy, but not pyroptosis or necrosis, in testicular cells. Genome-wide gene expression analysis revealed that YCl3 induced significant changes in gene expression, with Ca2+ and mitochondria-related genes being the most significantly altered. Mechanistically, YCl3 exposure induced mitochondrial dysfunction in testicular cells, triggering the overproduction of reactive oxygen species (ROS) by impairing the Nrf2 pathway, regulating downstream Ho-1 target protein expression, and increasing Ca2+ levels to activate the CamkII/Ampk signaling pathway. Blocking ROS production or Ca2+ signaling significantly attenuates apoptosis and autophagy, while supplementation with Ca2+ reverses the suppression of apoptosis and autophagy by ROS blockade in testicular cells. Notably, apoptosis and autophagy induced by YCl3 treatment are independent of each other. Thus, our study suggests that YCl3 may impair the antioxidant stress signaling pathway and activate the calcium pathway through the ROS-Ca2+ axis, which promotes testicular cell apoptosis and autophagy independently, thus inducing testicular damage and impairing male reproductive function.

Ca2+ Influx through TRPC Channels Is Regulated by Homocysteine-Copper Complexes

An elevated level of circulating homocysteine (Hcy) has been regarded as an independent risk factor for cardiovascular disease; however, the clinical benefit of Hcy lowering-therapy is not satisfying. To explore potential unrevealed mechanisms, we investigated the roles of Ca²⁺ influx through TRPC channels and regulation by Hcy-copper complexes. Using primary cultured human aortic endothelial cells and HEK-293 T-REx cells with inducible TRPC gene expression, we found that Hcy increased the Ca²⁺ influx in vascular endothelial cells through the activation of TRPC4 and TRPC5. The activity of TRPC4 and TRPC5 was regulated by extracellular divalent copper (Cu²⁺) and Hcy. Hcy prevented channel activation by divalent copper, but monovalent copper (Cu⁺) had no effect on the TRPC channels. The glutamic acids (E542/E543) and the cysteine residue (C554) in the extracellular pore region of the TRPC4 channel mediated the effect of Hcy-copper complexes. The interaction of Hcy-copper significantly regulated endothelial proliferation, migration, and angiogenesis. Our results suggest that Hcy-copper complexes function as a new pair of endogenous regulators for TRPC channel activity. This finding gives a new understanding of the pathogenesis of hyperhomocysteinemia and may explain the unsatisfying clinical outcome of Hcy-lowering therapy and the potential benefit of copper-chelating therapy.

TRPM2 Channel Inhibition Attenuates Amyloid β42-Induced Apoptosis and Oxidative Stress in the Hippocampus of Mice

Alzheimer's disease (AD) is characterized by the increase of hippocampal Ca²⁺ influx-induced apoptosis and mitochondrial oxidative stress (OS). The OS is a stimulator of TRPM2, although N-(p-amylcinnamoyl)anthranilic acid (ACA), 2-aminoethyl diphenylborinate (2/APB), and glutathione (GSH) are non-specific antagonists of TRPM2. In the present study, we investigated the protective roles of GSH and TRPM2 antagonist treatments on the amyloid β42 peptide (Aβ)-caused oxidative neurotoxicity and apoptosis in the hippocampus of mice with AD model. After the isolation of hippocampal neurons from the newborn mice, they were divided into five incubation groups as follows: control, ACA, Aβ, Aβ+ACA, and Aβ+GSH. The levels of apoptosis, hippocampus death, cytosolic ROS, cytosolic Zn²⁺, mitochondrial ROS, caspase-3, caspase-9, lipid peroxidation, and cytosolic Ca²⁺ were increased in the primary hippocampus cultures by treatments of Aβ, although their levels were decreased in the neurons by the treatments of GSH, PARP-1 inhibitors (PJ34 and DPQ), and TRPM2 blockers (ACA and 2/APB). The Aβ-induced decreases of cell viability, cytosolic GSH, reduced GSH, and GSH peroxidase levels were also increased in the groups of Aβ+ACA and Aβ+GSH by the treatments of ACA and GSH. However, the Aβ-caused changes were not observed in the hippocampus of TRPM2-knockout mice. In conclusion, the present data demonstrate that maintaining the activation of TRPM2 is not only important for the quenching OS and neurotoxicity in the hippocampal neurons of mice with experimental AD but also equally critical to the modulation of Aβ-induced apoptosis. The possible positive effects of GSH and TRPM2 antagonist treatments on the amyloid-beta (Aβ)-induced oxidative toxicity in the hippocampus of mice. The ADP-ribose (ADPR) is produced via the stimulation of PARP-1 in the nucleus of neurons. The NUT9 in the C terminus of TRPM2 channel acts as a key role for the activation of TRPM2. The antagonists of TRPM2 are glutathione (GSH), ACA, and 2/APB in the hippocampus. The Aβ incubation-mediated TRPM2 stimulation increases the concentration of cytosolic-free Ca²⁺ and Zn²⁺ in the hippocampus. In turn, the increased concentration causes the increase of mitochondrial membrane potential (ΔΨm), which causes the excessive generations of mitochondria ROS and the decrease of cytosolic GSH and GSH peroxidase (GSH-Px). The ROS production and GSH depletion are two main causes in the neurobiology of Alzheimer's disease. However, the effect of Aβ was not shown in the hippocampus of TRPM2-knockout mice. The Aβ and TRPM2 stimulation-caused overload Ca²⁺ entry cause apoptosis and cell death via the activations of caspase-3 (Casp/3) and caspase-9 (Casp/9) in the hippocampus. The actions of Aβ-induced oxidative toxicity were modulated in the primary hippocampus by the incubations of ACA, GSH, 2/APB, and PARP-1 inhibitors (PJ34 and DPQ). (↑) Increase. (↓) Decrease.

Transient receptor potential channel stimulation induced oxidative stress and apoptosis in the colon of mice with colitis-associated colon cancer: modulator role of Sambucus ebulus L

BACKGROUND

Increased Ca²⁺ entry causes an increase in tumor cell proliferation, apoptosis, cytosolic reactive free oxygen species (cyROS), and mitochondrial ROS (miROS) in tumor cells. The cyROS and miROS stimulate the cation channels, including the TRPA1, TRPM2, and TRPV1. Sambucus ebulus L (SEB) (Dwarf Elder) induced both antioxidant and anticancer effects in the human hepatocarcinoma and human colon carcinoma cancer cell lines. We investigated the etiology of colorectal cancer and the impact of three channels, as well as the protective effects of SEB on apoptosis, cyROS, and miROS in the colon of mice with colitis-associated colon cancer (AOM/DSS).

METHODS

A total 28 mice were equally divided into four groups as control, SEB (100 mg/kg/day for 14 days), AOM/DSS, and SEB + AOM/DSS. Azoxymethane/dextran sulfate sodium-induced colon cancer associated with colitis was induced in the AOM/DSS groups within 10 weeks. At the end of the experiments, the colon samples were removed from the mice.

RESULTS

The protein bands of caspase - 3, TRPA1, TRPM2, and TRPV1 were increased by the treatments of AOM/DSS. The levels of apoptosis, cyROS, cleaved caspase - 3, and cleaved caspase - 9, as well as the depolarization of the mitochondrial membrane, all increased in the AOM/DSS group. Although they were reduced in the SEB and AOM/DSS + SEB groups by the treatments of SEB, TRPA1 (AP18), TRPM2 (ACA), and TRPV1 (capsazepine) antagonists, the apoptotic and oxidant values were further elevated in the AOM/DSS group by the treatments of TRPA1 (cinnamaldehyde), TRPM2 (H₂O₂), and TRPV1 (capsaicin) agonists.

CONCLUSION

The activations of TRPA1, TRPM2, and TRPV1 channels induced the increase of apoptotic and oxidant actions in the colon cancer cells, although their inhibition via SEB treatment decreased the actions. Hence, TRPA1, TRPM2, and TRPV1 activations could be used as effective agents in the treatment of colon tumors.

Cysteine-Rich Whey Protein Isolate (CR-WPI) Ameliorates Erectile Dysfunction by Diminishing Oxidative Stress via DDAH/ADMA/NOS Pathway

Nitric oxide synthase- (NOS-) dependent endothelial dysfunction induced by oxidative stress (OS) is assumed to play a pivotal role in the pathogenesis and progression of diabetes mellitus-related erectile dysfunction (DMED). Cysteine-rich whey protein isolate (CR-WPI) is a widely used protein supplement and has been confirmed to reduce reactive oxygen species (ROS) by increasing cellular antioxidant glutathione (GSH). However, it is currently unknown whether CR-WPI elicits therapeutic effects in DMED. Here, we provide diabetic rats with CR-WPI to determine its effect on DMED and the underlying mechanisms. The results suggest that CR-WPI supplementation increased GSH biosynthesis and reduced ROS content and simultaneously upregulated the dimethylarginine dimethylaminohydrolase (DDAH)/asymmetrical dimethylarginine (ADMA)/nitric oxide synthase (NOS) metabolic pathway. Evaluation of intracavernous pressure (ICP) also showed an improvement of penile erectile function in CR-WPI-treated rats. The results of the vitro cell culture showed that glutathione pretreatment protected corpus cavernosum smooth muscle cells (CCSMC) from H₂O₂-induced apoptosis by decreasing Caspase 9 and Caspase 3 expressions. These results augur well for the potential therapeutic application of dietary CR-WPI supplementation for treating diabetic erectile dysfunction.

The involvement of TRPM2 on the MPP+-induced oxidative neurotoxicity and apoptosis in hippocampal neurons from neonatal mice: protective role of resveratrol

Parkinson's disease (PD) is an age-related chronic neurodegenerative disease. Although PD is known to be a result of damage to hippocampal neurons, its molecular mechanism has yet to be completely clarified. The neurodegeneration in hippocampal neurons has been suggested to include excessive production of reactive oxygen species (ROS). Mitochondrial dysfunction and disruption of intracellular Ca²⁺ homeostasis play the most important role in the increase in ROS production for the cells. Remarkably, it is stated in the literature that especially the change of Ca²⁺ homeostasis triggers neuronal degeneration. TRPM2 is a unique calcium-permeable nonselective cation channel, and densest in the numberless neuronal population. The current study aims to elucidate the effect of antioxidant resveratrol (Resv) on TRPM2-mediated oxidative stress (OS) induced by 1-methyl-4-phenylpyridinium (MPP) exposure in the primary mouse hippocampal neurons. The neurons were divided into four groups as Control, Resv , MPP, and MPP+ Resv. In the current results, the activation of TRPM2 was observed in primary hippocampal neurons with MPP incubation. TRPM2 channel expression levels in the MPP group increased in hippocampal neurons after MPP exposure. In addition, intracellular free Ca²⁺ concentration and TRPM2 channel currents were highest in MPP groups, although they were decreased by the Resv treatment. In addition, mitochondrial membrane depolarization, ROS, caspase-3, caspase-9, and apoptosis values induced by MPP decreased with resveratrol treatment. In conclusion, in our study, we observed that the dysregulation of OS-induced TRPM2 channel activation in hippocampal neurons exposed to MPP caused apoptotic cell death in neurons, while the use of resveratrol had a protective effect by reducing OS resources in the environment.

One-Carbon Metabolism: Pulling the Strings behind Aging and Neurodegeneration

One-carbon metabolism (OCM) is a network of biochemical reactions delivering one-carbon units to various biosynthetic pathways. The folate cycle and methionine cycle are the two key modules of this network that regulate purine and thymidine synthesis, amino acid homeostasis, and epigenetic mechanisms. Intersection with the transsulfuration pathway supports glutathione production and regulation of the cellular redox state. Dietary intake of micronutrients, such as folates and amino acids, directly contributes to OCM, thereby adapting the cellular metabolic state to environmental inputs. The contribution of OCM to cellular proliferation during development and in adult proliferative tissues is well established. Nevertheless, accumulating evidence reveals the pivotal role of OCM in cellular homeostasis of non-proliferative tissues and in coordination of signaling cascades that regulate energy homeostasis and longevity. In this review, we summarize the current knowledge on OCM and related pathways and discuss how this metabolic network may impact longevity and neurodegeneration across species.

Toxic Peptide From Palythoa caribaeorum Acting on the TRPV1 Channel Prevents Pentylenetetrazol-Induced Epilepsy in Zebrafish Larvae

PcActx peptide, identified from the transcriptome of zoantharian Palythoa caribaeorum, was clustered into the phylogeny of analgesic polypeptides from sea anemone Heteractis crispa (known as APHC peptides). APHC peptides were considered as inhibitors of transient receptor potential cation channel subfamily V member 1 (TRPV1). TRPV1 is a calcium-permeable channel expressed in epileptic brain areas, serving as a potential target for preventing epileptic seizures. Through in silico and in vitro analysis, PcActx peptide was shown to be a potential TRPV1 channel blocker. In vivo studies showed that the linear and oxidized PcActx peptides caused concentration-dependent increases in mortality of zebrafish larvae. However, monotreatment with PcActx peptides below the maximum tolerated doses (MTD) did not affect locomotor behavior. Moreover, PcActx peptides (both linear and oxidized forms) could effectively reverse pentylenetetrazol (PTZ)-induced seizure-related behavior in zebrafish larvae and prevent overexpression of c-fos and npas4a at the mRNA level. The excessive production of ROS induced by PTZ was markedly attenuated by both linear and oxidized PcActx peptides. It was also verified that the oxidized PcActx peptide was more effective than the linear one. In particular, oxidized PcActx peptide notably modulated the mRNA expression of genes involved in calcium signaling and γ-aminobutyric acid (GABA)ergic-glutamatergic signaling, including calb1, calb2, gabra1, grm1, gria1b, grin2b, gat1, slc1a2b, gad1b, and glsa. Taken together, PcActx peptide, as a novel neuroactive peptide, exhibits prominent anti-epileptic activity, probably through modulating calcium signaling and GABAergic-glutamatergic signaling, and is a promising candidate for epilepsy management.

Ion channels alterations in the forebrain of high-fat diet fed rats

Evidence suggests that transient receptor potential (TRP) ion channels dysfunction significantly contributes to the physiopathology of metabolic and neurological disorders. Dysregulation in functions and expression in genes encoding the TRP channels cause several inherited diseases in humans (the so-called 'TRP channelopathies'), which affect the cardiovascular, renal, skeletal, and nervous systems. This study aimed to evaluate the expression of ion channels in the forebrain of rats with diet-induced obesity (DIO). DIO rats were studied after 17 weeks under a hypercaloric diet (high-fat diet, HFD) and were compared to the control rats with a standard diet (CHOW). To determine the systemic effects of HFD exposure, we examined food intake, fat mass content, fasting glycemia, insulin levels, cholesterol, and triglycerides. qRT-PCR, Western blot, and immunochemistry analysis were performed in the frontal cortex (FC) and hippocampus (HIP). After 17 weeks of HFD, DIO rats increased their body weight significantly compared to the CHOW rats. In DIO rats, TRPC1 and TRPC6 were upregulated in the HIP, while they were downregulated in the FC. In the case of TRPM2 expression, instead was increased both in the HIP and in the FC. These could be related to the increase of proteins and nucleic acid oxidation. TRPV1 and TRPV2 gene expression showed no differences both in the FC and HIP. In general, qRT-PCR analyses were confirmed by Western blot analysis. Immunohistochemical procedures highlighted the expression of the channels in the cell body of neurons and axons, particularly for the TRPC1 and TRPC6. The alterations of TRP channel expression could be related to the activation of glial cells or the neurodegenerative process presented in the brain of the DIO rat highlighted with post synaptic protein (PSD 95) alterations. The availability of suitable animal models may be useful for studying possible pharmacological treatments to counter obesity-induced brain injury. The identified changes in DIO rats may represent the first insight to characterize the neuronal alterations occurring in obesity. Further investigations are necessary to characterize the role of TRP channels in the regulation of synaptic plasticity and obesity-related cognitive decline.

All roads lead to Rome - a review of the potential mechanisms by which exerkines exhibit neuroprotective effects in Alzheimer's disease

Age-related neurodegenerative disorders such as Alzheimer’s disease (AD) have become a critical public health issue due to the significantly extended human lifespan, leading to considerable economic and social burdens. Traditional therapies for AD such as medicine and surgery remain ineffective, impractical, and expensive. Many studies have shown that a variety of bioactive substances released by physical exercise (called “exerkines”) help to maintain and improve the normal functions of the brain in terms of cognition, emotion, and psychomotor coordination. Increasing evidence suggests that exerkines may exert beneficial effects in AD as well. This review summarizes the neuroprotective effects of exerkines in AD, focusing on the underlying molecular mechanism and the dynamic expression of exerkines after physical exercise. The findings described in this review will help direct research into novel targets for the treatment of AD and develop customized exercise therapy for individuals of different ages, genders, and health conditions.

Hydroxychloroquine Attenuates Acute Inflammation (LPS)-Induced Apoptosis via Inhibiting TRPV1 Channel/ROS Signaling Pathways in Human Monocytes

Simple Summary

LPS is a well-known agent in cell line models, including U937 monocytes, for inducing acute inflammation (INF). It is not known whether antioxidant HCQ, through the inhibition of TRPV1 in U937, can decrease oxidative monocyte toxicity and cell death. We investigated the modulator action of HCQ treatment through the modulation of TRPV1 on the levels of mROS, INF, and apoptosis in an LPS-stimulated U937 monocyte model. Acute INF activates apoptotic, inflammatory, and oxidant action through acute INF-dependent excessive cROS, MDA, cytokine generation, and Ca²⁺ influx in U937 human monocyte cells. Furthermore, treatment with acute INF increases TRPV1 and apoptotic marker (CAS3, CAS9, Bax, and Bcl-2) concentrations via downregulation of glutathione level and glutathione peroxidase activity in U937 monocytes. The acute INF-caused U937 oxidative stress and cytotoxicity is diminished by the treatment of HCQ and TRPV1 inhibitor (CPZ). In summary, treatment with HCQ and CPZ induced anti-inflammatory, anti-apoptotic, and antioxidant action via the inhibition of cROS, cytokine generation, and caspase activation.

Abstract

Acute inflammation (INF) and apoptosis are induced in monocytes by the generation of several factors, including the products of cytosolic oxygen free radicals (cROS) and the excessive influx of Ca²⁺ via the stimulation of TRPV1. These are main factors in the etiology of monocyte activation-induced inflammatory and neurodegenerative diseases. Importantly, the protective action of hydroxychloroquine (HCQ) treatment via the inhibition of TRPV1 on the levels of inflammatory factors, cROS, and apoptosis in acute INF (lipopolysaccharide, LPS)-exposed neuronal cells was recently reported. However, the relationships between acute INF via TRPV1 activation and HCQ in monocytes have not been fully clarified yet. The cell membrane of U937 human monocytes contains natural TRPV1. In the study plan, we used U937 cells in four main groups, namely control, HCQ (60 μM for 48 h), INF (1 μg/mL LPS for 16 h), and HCQ + INF. The current data indicate that LPS-induced acute INF caused the upregulation of excessive cytosolic Ca²⁺ accumulation via the stimulation of TRPV1 in the cells. The treatment of INF additionally upregulated the levels of apoptosis and cytokines (IL6, IL1β, and TNFα), due to upregulated cROS and lipid peroxidation levels as well as upregulated generation of caspase -3 (CAS3) and -9 (CAS9) but a decrease in glutathione and glutathione peroxidase. The expression levels of TRPV1, Bax, CAS3, and CAS9 were also upregulated by the treatment of LPS. However, treatment with HCQ and TRPV1 blocker (capsazepine) modulated the levels of cytokines, caspases, cROS, Ca²⁺ influx, and apoptosis through the modulation of TRPV1 in the U937 that were stimulated with LPS. In summary, the present data suggest TRPV1 activation through the acute INF (LPS)-induced inflammatory, oxidant, and apoptotic adverse actions in monocyte cells, whereas HCQ prevented adverse actions via the modulation of TRPV1. The results may be significant in the modulation of monocyte activation-caused inflammatory and neurodegenerative diseases.

Involvement of TRPM2 in the Neurobiology of Experimental Migraine: Focus on Oxidative Stress and Apoptosis

Excessive Ca²⁺ influx and mitochondrial oxidative stress (OS) of trigeminal ganglia (TG) have essential roles in the etiology of migraine headache and aura. The stimulation of TRPM2 channel via the generation of OS and ADP-ribose (ADPR) induces pain, inflammatory, and oxidative neurotoxicity, although its inhibition reduces the intensity of pain and neurotoxicity in several neurons. However, the cellular and molecular effects of TRPM2 in the TG of migraine model (glyceryl trinitrate, GTN) on the induction of pain, OS, apoptosis, and inflammation remain elusive. GTN-mediated increases of pain intensity, apoptosis, death, cytosolic reactive oxygen species (ROS), mitochondrial ROS, caspase -3, caspase -9, cytosolic Ca²⁺ levels, and cytokine generations (TNF-α, IL-1β, and IL-6) in the TG of TRPM2 wild-type mouse were further increased by the TRPM2 activation, although they were modulated by the treatments of GSH, PARP-1 inhibitors (PJ34 and DPQ), and TRPM2 blockers (ACA and 2APB). However, the effects of GTN were not observed in the TG of TRPM2 knockout mice. The current data indicate that the maintaining activation of TRPM2 is not only important for the quenching OS, inflammation, and neurotoxicity in the TG neurons of mice with experimental migraine but also equally critical to the modulation of GTN-induced pain.

Age-Dependent Association Between Elevated Homocysteine and Cognitive Impairment in a Post-stroke Population: A Prospective Study

Background and Purpose: The results regarding the independent association between homocysteine (Hcy) levels and post-stroke cognitive impairment (PSCI) were inconsistent. The effect of age on this association has yet to be explored. This study aims to determine the relationship between Hcy levels, age, and cognitive impairment in a post-stroke population.

Methods: A total of 592 patients with acute ischemic stroke (AIS) completed follow-up. Serum Hcy levels were measured enzymatically by spectrophotometry within 24 h of admission. Cognitive function was evaluated by the Mini-Mental State Examination (MMSE) 1 month after stroke, and the scores ≤ 24 were considered as cognitive impairment. Our study was dichotomized into two groups by a cut-off of 65 years. Multivariate logistic regression models were used to determine the association between baseline Hcy levels and cognitive impairment.

Results: According to the MMSE score, 317 (53.5%) patients had cognitive impairment. Patients with higher levels of Hcy were more prone to have cognitive impairment 1 month after stroke than patients with lower levels of Hcy (p < 0.001). The optimal cut-off points of Hcy level (μmol/L) were (T1) ≤ 8, (T2) 8–12, and (T3) ≥ 12. After adjusting for confounding factors, the multivariate regression analysis showed that the third Hcy tertile was independently associated with cognitive impairment [odds ratio (OR) = 2.057, 95% confidence interval (CI) = 1.133–3.735, p = 0.018). A stronger association [T2 (OR = 2.266, 95% CI = 1.042–4.926, p = 0.039); T3 (OR =3.583, 95% CI = 1.456–8.818, p = 0.005)] was found in the younger group. However, the independent association was not confirmed in the older group.

Conclusions: Elevated Hcy levels in the acute phase of ischemic stroke were independently associated with cognitive impairment in a post-stroke population. Furthermore, the association was age-dependent and more meaningful in a younger population aged below 65. So, Hcy levels in patients with stroke should be well-monitored, especially in younger patients.

Proteomic analysis of bone marrow-derived mesenchymal stem cell extracellular vesicles from healthy donors: implications for proliferation, angiogenesis, Wnt signaling, and the basement membrane

Background

Bone marrow-derived mesenchymal stem cells (BM-MSCs) have shown therapeutic potential in various in vitro and in vivo studies in cutaneous wound healing. Furthermore, there are ubiquitous studies highlighting the pro-regenerative effects of BM-MSC extracellular vesicles (BM-MSC EVs). The similarities and differences in BM-MSC EV cargo among potential healthy donors are not well understood. Variation in EV protein cargo is important to understand, as it may be useful in identifying potential therapeutic applications in clinical trials. We hypothesized that the donors would share both important similarities and differences in cargo relating to cell proliferation, angiogenesis, Wnt signaling, and basement membrane formation—processes shown to be critical for effective cutaneous wound healing.

Methods

We harvested BM-MSC EVs from four healthy human donors who underwent strict screening for whole bone marrow donation and further Good Manufacturing Practices-grade cell culture expansion for candidate usage in clinical trials. BM-MSC EV protein cargo was determined via mass spectrometry and Proteome Discoverer software. Corresponding proteomic networks were analyzed via the UniProt Consortium and STRING consortium databases.

Results

More than 3000 proteins were identified in each of the donors, sharing > 600 proteins among all donors. Despite inter-donor variation in protein identities, there were striking similarities in numbers of proteins per biological functional category. In terms of biologic function, the proteins were most associated with transport of ions and proteins, transcription, and the cell cycle, relating to cell proliferation. The donors shared essential cargo relating to angiogenesis, Wnt signaling, and basement membrane formation—essential processes in modulating cutaneous wound repair.

Conclusions

Healthy donors of BM-MSC EVs contain important similarities and differences among protein cargo that may play important roles in their pro-regenerative functions. Further studies are needed to correlate proteomic signatures to functional outcomes in cutaneous repair.

The Antibody Receptor Fc Gamma Receptor IIIb Induces Calcium Entry via Transient Receptor Potential Melastatin 2 in Human Neutrophils

Human neutrophils express two unique antibody receptors for IgG, the FcγRIIa and the FcγRIIIb. FcγRIIa contains an immunoreceptor tyrosine-based activation motif (ITAM) sequence within its cytoplasmic tail, which is important for initiating signaling. In contrast, FcγRIIIb is a glycosylphosphatidylinositol (GPI)-linked receptor with no cytoplasmic tail. Although, the initial signaling mechanism for FcγRIIIb remains unknown, it is clear that both receptors are capable of initiating distinct neutrophil cellular functions. For example, FcγRIIa is known to induce an increase in L-selectin expression and efficient phagocytosis, while FcγRIIIb does not promote these responses. In contrast, FcγRIIIb has been reported to induce actin polymerization, activation of β1 integrins, and formation of neutrophils extracellular traps (NET) much more efficiently than FcγRIIa. Another function where these receptors seem to act differently is the increase of cytoplasmic calcium concentration. It has been known for a long time that FcγRIIa induces production of inositol triphosphate (IP₃) to release calcium from intracellular stores, while FcγRIIIb does not use this phospholipid. Thus, the mechanism for FcγRIIIb-mediated calcium rise remains unknown. Transient Receptor Potential Melastatin 2 (TRPM2) is a calcium permeable channel expressed in many cell types including vascular smooth cells, endothelial cells and leukocytes. TRPM2 can be activated by protein kinase C (PKC) and by oxidative stress. Because we previously found that FcγRIIIb stimulation leading to NET formation involves PKC activation and reactive oxygen species (ROS) production, in this report we explored whether TRPM2 is activated via FcγRIIIb and mediates calcium rise in human neutrophils. Calcium rise was monitored after Fcγ receptors were stimulated by specific monoclonal antibodies in Fura-2-loaded neutrophils. The bacterial peptide fMLF and FcγRIIa induced a calcium rise coming initially from internal pools. In contrast, FcγRIIIb caused a calcium rise by inducing calcium entry from the extracellular medium. In addition, in the presence of 2-aminoethoxydiphenyl borate (2-APB) or of clotrimazole, two inhibitors of TRPM2, FcγRIIIb-induced calcium rise was blocked. fMLF- or FcγRIIa-induced calcium rise was not affected by these inhibitors. These data suggest for the first time that FcγRIIIb aggregation activates TRPM2, to induce an increase in cytoplasmic calcium concentration through calcium internalization in human neutrophils.

Mildronate protects heart mtDNA from oxidative stress toxicity induced by exhaustive physical exercise

Exhaustive physical exercises are potentially dangerous for human's physical health and may lead to chronic heart disease. Therefore, individuals involved in such activity require effective and safe cardioprotectors. The goal of this research was to study Mildronate (a cardioprotective drug) effect on the level of oxidative stress markers in hearts of mice under conditions of exhausting physical exercise, such as forced swimming for 1 h per day for 7 days. Forced swimming lead to mtDNA damage accumulation, increase in diene conjugates level and loss of reduced glutathione despite an increase in antioxidant genes expression and activation of mitochondrial biogenesis. Mildronate treatment reduced oxidative stress, probably due to the inhibition of fatty acids transport to mitochondria and an increase in the intensity of glucose oxidation, which in part confirms by increase in glucose transporter expression. Thus, we can assume that Mildronate is an effective cardioprotector in exhaustive physical exercises.

Bevacizumab induces oxidative cytotoxicity and apoptosis via TRPM2 channel activation in retinal pigment epithelial cells: Protective role of glutathione

PURPOSE

Bevacizumab (BEV) is a blocker of circulating VEGF A generation. However, BEV has adverse apoptotic and cytotoxic effects via upregulation of mitochondrial reactive oxygen species (ROS) and TRPM2 activation, and downregulation of cytosolic glutathione (GSH) in neuronal cells. We investigated the possible protective effects of GSH treatment on BEV-induced oxidant and apoptotic adverse actions in the TRPM2 expressing adult retinal pigment epithelial-19 (ARPE-19) and SH-SY5Y neuronal cells.

MATERIAL AND METHODS

The ARPE-19 and SH-SY5Y cells were divided into five main groups: Control, GSH (10 mM for 2 h), BEV (0.25 mg/ml for 24 h), BEV+GSH, and BEV+TRPM2 channel blockers (ACA or 2-APB). In the SH-SY5Y cells, the Ca²⁺ analyses (Fluo-3) were performed only, although Fluo-3 and the remaining analyses were performed in the ARPE-19 cells.

RESULTS

The levels of apoptosis, cell death, mitochondrial ROS, lipid peroxidation, caspase-3, caspase-9, ADP-ribose-induced TRPM2 current density, cytosolic-free Zn²⁺, and Ca²⁺ were increased by BEV, although their levels were diminished by the treatments of GSH and TRPM2 blockers. The BEV-induced decreases of cell viability, GSH levels, and glutathione peroxidase activities were increased by the treatment of GSH. BEV-induced increase of TRPM2 expression was decreased by the treatment of GSH, although BEV-induced decrease of VEGF A expression was further decreased by the treatment of GSH.

CONCLUSION

Our data confirmed that BEV-induced mitochondrial ROS and apoptosis in the human retinal epithelial cells were modulated by GSH and TRPM2 inhibition. The treatment of GSH may be considered as a therapeutic approach to BEV-induced ARPE-19 cell injury.

The impact of glutathione metabolism in autism spectrum disorder

This paper reviews the potential role of glutathione (GSH) in autism spectrum disorder (ASD). GSH plays a key role in the detoxification of xenobiotics and maintenance of balance in intracellular redox pathways. Recent data showed that imbalances in the GSH redox system are an important factor in the pathophysiology of ASD. Furthermore, ASD is accompanied by decreased concentrations of reduced GSH in part caused by oxidation of GSH into glutathione disulfide (GSSG). GSSG can react with protein sulfhydryl (SH) groups, thereby causing proteotoxic stress and other abnormalities in SH-containing enzymes in the brain and blood. Moreover, alterations in the GSH metabolism via its effects on redox-independent mechanisms are other processes associated with the pathophysiology of ASD. GSH-related regulation of glutamate receptors such as the N-methyl-D-aspartate receptor can contribute to glutamate excitotoxicity. Synergistic and antagonistic interactions between glutamate and GSH can result in neuronal dysfunction. These interactions can involve transcription factors of the immune pathway, such as activator protein 1 and nuclear factor (NF)-κB, thereby interacting with neuroinflammatory mechanisms, ultimately leading to neuronal damage. Neuronal apoptosis and mitochondrial dysfunction are recently outlined as significant factors linking GSH impairments with the pathophysiology of ASD. Moreover, GSH regulates the methylation of DNA and modulates epigenetics. Existing data support a protective role of the GSH system in ASD development. Future research should focus on the effects of GSH redox signaling in ASD and should explore new therapeutic approaches by targeting the GSH system.

Glutathione depletion induces oxidative injury and apoptosis via TRPM2 channel activation in renal collecting duct cells

Oxidative stress (OS)-induced glutathione (GSH) depletion plays an essential role in several kidney diseases such as chronic kidney disease and nephrotoxicity. The OS-dependent activation of TRPM2 cation channel in several neurons and cells were modulated by the concentration of intracellular GSH. However, the effects of GSH alteration on TRPM2 activation, OS, and apoptosis in the cortical collecting duct (mpkCCD_c14) cells still remain elusive. We investigated the effects of GSH supplementation on OS-induced TRPM2 activation, mitochondrial oxidative stress, and apoptosis in the human embryonic kidney 293 (HEK293) and mpkCCD_c14 cells treated with buthionine-sulfoximine (BSO), a GSH synthase inhibitor. The HEK293 and mpkCCD_c14 cells were divided into five groups as control, GSH (10 mM for 2 h), BSO (0.5 mM for 6 h), BSO + GSH, and BSO + TRPM2 channel blockers. Apoptosis, cell death, mitochondrial OS, caspase -3, caspase -9, cytosolic free Zn²⁺, and Ca²⁺ concentrations were increased in the BSO group of the TRPM2 expressing mpkCCD_c14 cells, although they were diminished by the treatments of GSH, PARP-1 inhibitors (PJ34 and DPQ), and TRPM2 blockers (ACA and 2-APB). The BSO-induced decreases in the levels of cell viability and cytosolic GSH were increased by the treatments of GSH, ACA, and 2-APB. However, the effects of BSO and GSH were not observed in the non-TRPM2 expressing HEK293 cells. Current results show that maintaining GSH homeostasis is not only important for quenching OS in the cortical collecting duct cells but equally critical to modulate TRPM2 activation. Thus, suppressing apoptosis and mitochondrial OS responses elicited by oxidant action of GSH depletion.

Effect of di(2-ethylhexyl) phthalate on Nrf2-regulated glutathione homeostasis in mouse kidney

Environmental toxicants such as phthalate have been involved in multiple health disorders including renal diseases. Oxidative damage is implicated in many alterations caused by phthalate especially the di(2-ethylhexyl) phthalate (DEHP), which is the most useful phthalate. However, information regarding its mechanism of renal damage is lacking. The transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2) regulates gene expression implicated in free radical scavenging and cytoprotection including the antioxidant glutathione (GSH) pathway. The aim of this study was to assess whether DEHP affects the Nrf2 pathway and the GSH concentration. Mice were divided into four groups: a control group and three groups treated with DEHP at different concentrations (5, 50, and 200 mg/kg body weight) for 30 days. Our results showed that DEHP altered the normal levels of serum biochemical parameters creatinine (CREA), urea, and lactate dehydrogenase (LDH). This phthalate caused oxidative damage through the induction of lipid peroxidation and protein oxidation as marked by increase of protein carbonyl (PC) and loss of protein-bound sulfhydryls (PSH). Simultaneously, DEHP treatment decreased the protein level of Nrf-2, HO-1, and GCLC (responsible of GSH synthesis) and decreased the GSH level. Inhibition of the Nrf2 pathway is related to the activation of the mitochondrial pathway of apoptosis. This apoptotic process is evidenced by an upregulation of p53 and Bax protein levels in addition to a downregulation of Bcl-2. Collectively, our data demonstrated that depletion of Nrf2 and GSH was associated with the elevation of oxidative stress and the activation of intrinsic apoptosis in mouse kidney treated with DEHP.

Redox and mTOR-dependent regulation of plasma lamellar calcium influx controls the senescence-associated secretory phenotype

IMPACT STATEMENT

Through its ability to evoke responses from cells in a paracrine fashion, the senescence-associated secretory phenotype (SASP) has been linked to numerous age-associated disease pathologies including tumor invasion, cardiovascular dysfunction, neuroinflammation, osteoarthritis, and renal disease. Strategies which limit the amplitude and duration of SASP serve to delay age-related degenerative decline. Here we demonstrate that the SASP regulation is linked to shifts in intracellular Ca2+ homeostasis and strategies which rescue redox-dependent calcium entry including enzymatic H2O2 scavenging, TRP modulation, or mTOR inhibition block SASP and TRPC6 gene expression. As Ca2+ is indispensable for secretion from both secretory and non-secretory cells, it is exciting to speculate that the expression of plasma lamellar TRP channels critical for the maintenance of intracellular Ca2+ homeostasis may be coordinately regulated with the SASP.

Alprostadil Injection Attenuates Coronary Microembolization-Induced Myocardial Injury Through GSK-3β/Nrf2/HO-1 Signaling-Mediated Apoptosis Inhibition

Objective

Coronary microembolization (CME) results in progressive contractile dysfunction associated with cardiomyocyte apoptosis. Alprostadil injection improves microcirculation, which is effective in treating various cardiovascular disorders. However, the therapeutic effects of alprostadil in CME-induced myocardia injury remain unknown. Therefore, we evaluated the effects of alprostadil injection on cardiac protection in a rat model of CME and explored the underlying mechanisms.

Methods

A rat model of CME was established by injecting polyethylene microspheres into the left ventricle. After injection of microspheres, rats in the alprostadil group received alprostadil via tail vein within 2 minutes. Cardiac function, histological alterations in myocardium, serum c-troponin I (cTnI) levels, myocardium adenosine triphosphate (ATP) concentrations, the activity of superoxide dismutase (SOD) and malondialdehyde (MDA) content in myocardium, and myocardial apoptosis-related proteins were detected 12 hours after CME modeling.

Results

Compared with the Sham group, ATP concentrations, SOD activity in the myocardium, and cardiac function were significantly decreased in a rat model of CME. In addition, serum cTnI levels, MDA content, expression levels of pro-apoptotic proteins, and the number of TUNEL-positive nuclei were remarkably higher in CME group than those in the Sham group. However, alprostadil treatment notably reduced serum cTnI levels and expression levels of pro-apoptotic proteins, while noticeably improved cardiac function, and accelerated SOD activity in the myocardium following CME. Additionally, it was unveiled that the protective effects of alprostadil injection inhibit CME-induced myocardial apoptosis in the myocardium potentially through regulation of the GSK-3β/Nrf2/HO-1 signaling pathway.

Conclusion

Alprostadil injection seems to significantly suppress oxidative stress, alleviate myocardial apoptosis in the myocardium, and improve cardiac systolic and diastolic functions following CME by regulating the GSK-3β/Nrf2/HO-1 signaling pathway.

Homocysteine is Associated with the Development of Cerebral Small Vessel Disease: Retrospective Analyses from Neuroimaging and Cognitive Outcomes

OBJECTIVE

As the population ages, a growing burden of cerebral small vessel disease (cSVD) has sparked extensive concerns recently. Homocysteine (Hcy), as a traditional risk factor for atherosclerosis, may also participate in the development of cSVD. By comprehensively assessing Hcy's correlation with different MRI markers of cSVD and cognitive outcomes in a homogeneous population with cSVD, this study aims to explore the value of Hcy in the clinical management of cSVD.

METHODS

231 inpatients with MRI-confirmed cSVD were enrolled in this retrospective study (mean age 66.4±10.0 years, male sex 47.6%). Along with brain MRI and plasma total Hcy (tHcy) examination, Mini-Mental State Examination (MMSE) and Montreal Cognitive Assessment (MoCA) were also performed to assess their global cognitive function. Burdens of cSVD neuroimaging features encompassing white matter hyperintensity (WMH), lacunes of presumed vascular origin, cerebral microbleeds (CMBs), and enlarged perivascular spaces (EPVS) were evaluated based on brain MRI demonstrations.

RESULTS

After adjusting for possible confounders, statistical analyses showed that plasma tHcy levels were not only correlated with burdens of deep/periventricular WMH (P < 0.001, P for trend < 0.001; P < 0.001, P for trend < 0.001), lacunes (P < 0.001, P for trend < 0.001), lobar CMBs (P = 0.002), and EPVS in the basal ganglia (P < 0.001, P for trend = 0.002) but also remained an independent predictor of cognitive impairment (B=-0.159, 95%CI -0.269--0.049, P = 0.005, P for trend < 0.001) in the patients with cSVD.

CONCLUSIONS

Plasma tHcy levels are associated with the development of cSVD in a dose-independent manner and may predict the cognitive outcomes in cSVD patients. These findings provide a potential clue to cSVD's physiopathology and future disease management.

Ursolic acid protects against cisplatin‑induced ototoxicity by inhibiting oxidative stress and TRPV1‑mediated Ca2+‑signaling

Cisplatin (CDDP) is widely used in clinical settings for the treatment of various cancers. However, ototoxicity is a major side effect of CDDP, and there is an associated risk of irreversible hearing loss. We previously demonstrated that CDDP could induce ototoxicity via activation of the transient receptor potential vanilloid receptor 1 (TRPV1) pathway and subsequent induction of oxidative stress. The present study investigated whether ursolic acid (UA) treatment could protect against CDDP‑induced ototoxicity. UA is a triterpenoid with strong antioxidant activity widely used in China for the treatment of liver diseases. This traditional Chinese medicine is mainly isolated from bearberry, a Chinese herb. The present results showed that CDDP increased auditory brainstem response threshold shifts in frequencies associated with observed damage to the outer hair cells. Moreover, CDDP increased the expression of TRPV1, calpain 2 and caspase‑3 in the cochlea, and the levels of Ca2+ and 4‑hydroxynonenal. UA co‑treatment significantly attenuated CDDP‑induced hearing loss and inhibited TRPV1 pathway activation. In addition, UA enhanced CDDP‑induced growth inhibition in the human ovarian cancer cell line SKOV3, suggesting that UA synergizes with CDDP in vitro. Collectively, the present data suggested that UA could effectively attenuate CDDP‑induced hearing loss by inhibiting the TRPV1/Ca²+/calpain‑oxidative stress pathway without impairing the antitumor effects of CDDP.

Probucol enhances the therapeutic efficiency of mesenchymal stem cells in the treatment of erectile dysfunction in diabetic rats by prolonging their survival time via Nrf2 pathway

BACKGROUND

Intracavernous injection of mesenchymal stem cells (MSCs) is a promising method for diabetic mellitus-induced erectile dysfunction (DMED), but short survival time of MSCs in cavernous is a fatal defect for therapy. This study investigated therapeutic efficiency and potential mechanism of probucol combined with MSCs.

METHODS

In vivo study, a total of forty-eight 10-week-old male Sprague-Dawley (SD) rats were used. Twelve rats received intraperitoneal injection of PBS as the sham group; the rest received intraperitoneal injection of 60 mg/kg streptozotocin to establish DM models. DM rats were randomly divided into three groups: received intracavernosal (IC) injection of either PBS (DM group), MSCs (M group), or administrated probucol after intracavernosal injection of MSCs (P + M group). Erectile function was assessed by electrical stimulation of the cavernous nerves with real-time intracavernous pressure measurement. After euthanasia, penile tissue was investigated for histologic examination and Western blotting. In in vitro experiment, H2O2 was used to create oxidative stress environment to detect changes in cell viability. CCK8 was used to measure cell viability of MSCs treated with or without probucol. Intracellular ROS changes were detected by flow cytometry. Autophagy and apoptosis were detected by Western blotting and confocal microscopy.

RESULTS

Recovery of erectile function was observed in the P + M group. The combination therapy decreased fibrosis and increased endothelial function compared with MSC therapy alone. Western blotting results confirmed the increased expression of Nrf2 and HO-1 in cavernous body. H2O2 induced high oxidative stress and reduced cell viability in vitro, which was gradually reversed with increased concentration of probucol. H2O2 reduced Nrf2 expression, which was reversed by probucol's intervention. Furthermore, the expression of Bax, Caspase3, and Cleaved-Caspase3 decreased, and the expression of Bcl-2 increased in a dose-dependent manner because of probucol's intervention. In addition, Beclin1 and LC3II both increased in a dose-dependent manner. Meanwhile, the expression of P62 decreased. In the study of autophagy flux, we found probucol did not block it.

CONCLUSION

Probucol enhanced therapeutic efficiency of MSCs in DMED by prolonging their survival time, which mediated through improving the transplanted microenvironment of MSCs, increasing self-antioxidant ability of MSCs, strengthening protective autophagy, and inhibiting apoptosis of MSCs via Nrf2 pathway. Schematic model showing combined probucol and MSCs to improve DMED. Probucol increases self-antioxidant ability of MSCs, strengthening protective autophagy and inhibiting apoptosis via Nrf2/HO-1 and Nrf2/autophagy pathways.

Glutathione Depletion and Parkinsonian Neurotoxin MPP+-Induced TRPM2 Channel Activation Play Central Roles in Oxidative Cytotoxicity and Inflammation in Microglia

Parkinson's disease (PD) is one of most common neurodegenerative diseases. Environmental stressors such as oxidative stress (OS), calcium ion influx, apoptosis, and inflammation mechanisms are linked to activated microglia in patients with PD. The OS-dependent activated transient receptor potential melastatin 2 (TRPM2) channel is modulated in several neurons by glutathione (GSH). However, the cellular and molecular effects of GSH alteration on TRPM2 activation, OS, apoptosis, and inflammation in the microglia remain elusive. The microglia of TRPM2 wild-type (TRPM2-WT) and knockout (TRPM2-KO) mice were divided into control, PD model (MPP), L-buthionine sulfoximine (BSO), MPP + BSO and MPP + BSO + GSH groups. MPP-induced increases in apoptosis, death, OS, lipid peroxidation, PARP1, caspase-3 and caspase-9, inflammatory cytokines (IL-1β, TNF-α, IL-6), and intracellular free Zn²⁺ and Ca²⁺ levels in the microglia of TRPM2-WT mice were further increased by the BSO treatment, although they were diminished by the GSH treatment. Their levels were further reduced by PARP1 inhibitors (PJ34 and DPQ) and TRPM2 blockers (ACA and 2-APB). However, the effects of MPP and BSO were not observed in the microglia of TRPM2-KO mice. Taken together, our data demonstrate that maintaining GSH homeostasis is not only important for quenching OS in the microglia of patients with PD but also equally critical to modulating TRPM2, thus suppressing inflammatory responses elicited by environmental stressors.

Morphine Induces Apoptosis, Inflammation, and Mitochondrial Oxidative Stress via Activation of TRPM2 Channel and Nitric Oxide Signaling Pathways in the Hippocampus

Morphine as an opioid is an important drug in the treatment of moderate to severe pain. Several stress factors via generation of nitric oxide (NO) and oxidative stress (OS) are responsible for the adverse effects of morphine-induced analgesia, addiction, and antinociceptive tolerance, including altered Ca²⁺ concentration, inflammation, OS, and release of apoptotic factors. TRPM2 is a Ca²⁺-permeable cation channel and it is activated by OS and NO. Hence, adverse effect of morphine addiction may occur via the OS and NO-induced TRPM2 activation. Because of the unclear etiology of morphine-induced adverse effects in the hippocampus, investigating the involvement of TRPM2 and NO synthetase (NOS) activations in the treatment of morphine-induced OS, apoptosis, and neuroinflammation is a major challenge. The hippocampal neuron of TRPM2 wild-type (TRPM2-WT) and knockout (TRPM2-KO) mice were divided into control, morphine, NOS inhibitor (L-NAME) + morphine, and TRPM2 channel blockers (ACA and 2-APB) + morphine. The morphine-induced increases of apoptosis, neuron death, OS, lipid peroxidation, caspase-3 and caspase-9, neuroinflammatory cytokines (IL-1β, TNF-α, IL-6), and Ca²⁺ levels in the hippocampal neuron of TRPM2-WT mouse were decreased by the L-NAME, ACA, and 2-APB treatments, although cell viability, neuron count, and reduced glutathione and glutathione peroxidase levels were increased by the treatments. However, the effects of morphine were not observed in the hippocampus of TRPM2-KO mice. Taken together, our data show that neurodegeneration adverse effects of morphine were induced by activation of TRPM2, and excessive generations of NO and OS. Thus, inhibition of TRPM2 may modulate morphine-induced neurodegeneration in the hippocampus.

TRP Channels as Emerging Therapeutic Targets for Neurodegenerative Diseases

The development of treatment for neurodegenerative diseases (NDs) such as Alzheimer’s disease, Parkinson’s disease, Huntington’s disease, and amyotrophic lateral sclerosis is facing medical challenges due to the increasingly aging population. However, some pharmaceutical companies have ceased the development of therapeutics for NDs, and no new treatments for NDs have been established during the last decade. The relationship between ND pathogenesis and risk factors has not been completely elucidated. Herein, we review the potential involvement of transient receptor potential (TRP) channels in NDs, where oxidative stress and disrupted Ca²⁺ homeostasis consequently lead to neuronal apoptosis. Reactive oxygen species (ROS) -sensitive TRP channels can be key risk factors as polymodal sensors, since progressive late onset with secondary pathological damage after initial toxic insult is one of the typical characteristics of NDs. Recent evidence indicates that the dysregulation of TRP channels is a missing link between disruption of Ca²⁺ homeostasis and neuronal loss in NDs. In this review, we discuss the latest findings regarding TRP channels to provide insights into the research and quests for alternative therapeutic candidates for NDs. As the structures of TRP channels have recently been revealed by cryo-electron microscopy, it is necessary to develop new TRP channel antagonists and reevaluate existing drugs.

Resveratrol attenuates hypoxia-induced neuronal cell death, inflammation and mitochondrial oxidative stress by modulation of TRPM2 channel

Hypoxia (HYPX) induced-overload Ca²⁺ entry results in increase of mitochondrial oxidative stress, inflammation and apoptosis in several neurons. Ca²⁺ permeable TRPM2 channel was gated by ADP-ribose (ADPR) and reactive oxygen species (ROS), although its activity was modulated in HYPX-exposed neurons by resveratrol (RSV). The aim of this study was to evaluate if a therapy of RSV can modulate the effect of HYPX in the TRPM2 expressing SH-SY5Y neuronal and HEK293 (no expression of TRPM2) cell lines. The SH-SY5Y and HEK293 cells were divided into four groups as control, RSV (50 μM and 24 hours), and HYPX and RSV + HYPX. For induction of HYPX in the cells, CoCl₂ (200 μM and 24 hours) incubation was used. HYPX-induced intracellular Ca²⁺ responses to TRPM2 activation were increased in the SH-SY5Y cells but not in the HEK293 cells from coming H₂O₂ and ADPR. RSV treatment improved intracellular Ca²⁺ responses, mitochondrial function, suppressed the generation of cytokine (IL-1β and TNF-α), cytosolic and mitochondrial ROS in the SH-SY5Y cells. Intracellular free Zn²⁺, apoptosis, cell death, PARP-1, TRPM2 expression, caspase −3 and −9 levels are increased through activating TRPM2 in the SH-SY5Y cells exposed to the HYPX. However, the values were decreased in the cells by RSV and TRPM2 blockers (ACA and 2-APB). In SH-SY5Y neuronal cells exposed to HYPX conditions, the neuroprotective effects of RSV were shown to be exerted via modulation of oxidative stress, inflammation, apoptosis and death through modulation of TRPM2 channel. RSV could be used as an effective agent in the treatment of neurodegeneration exposure to HYPX.

Vitamin B12 is neuroprotective in experimental pneumococcal meningitis through modulation of hippocampal DNA methylation

Background

Bacterial meningitis (BM) causes apoptotic damage to the hippocampus and homocysteine (Hcy) accumulation to neurotoxic levels in the cerebrospinal fluid of children. The Hcy pathway controls bioavailability of methyl, and its homeostasis can be modulated by vitamin B₁₂, a cofactor of the methionine synthase enzyme. Herein, the neuroprotective potential and the underlying mode of action of vitamin B₁₂ adjuvant therapy were assessed in an infant rat model of BM.

Methods

Eleven-day old rats were intracysternally infected with Streptococcus pneumoniae serotype 3, or saline, treated with B₁₂ or placebo, and, 24 h after infection, their hippocampi were analyzed for apoptosis in the dentate gyrus, sulfur amino acids content, global DNA methylation, transcription, and proximal promoter methylation of candidate genes. Differences between groups were compared using 2-way ANOVA followed by Bonferroni post hoc test. Correlations were tested with Spearman’s test.

Results

B₁₂ attenuated BM-induced hippocampal apoptosis in a Hcy-dependent manner (r = 0.80, P < 0.05). BM caused global DNA hypomethylation; however, B₁₂ restored this parameter. Accordingly, B₁₂ increased the methylation capacity of hippocampal cells from infected animals, as inferred from the ratio S-adenosylmethionine (SAM):S-adenosylhomocysteine (SAH) in infected animals. BM upregulated selected pro-inflammatory genes, and this effect was counteracted by B₁₂, which also increased methylation of CpGs at the promoter of Ccl3 of infected animals.

Conclusion

Hcy is likely to play a central role in hippocampal damage in the infant rat model of BM, and B₁₂ shows an anti-inflammatory and neuroprotective action through methyl-dependent epigenetic mechanisms.

Hydrogen sulfide attenuates hyperhomocysteinemia-induced mitochondrial dysfunctions in brain

Hyperhomocysteinemia (HHcy) has been implicated in the development of neurodegenerative conditions and mild cognitive disorders. Mitochondrial dysfunctions are the major mechanisms involved in homocysteine (Hcy)-induced neurotoxicity. Although, hydrogen sulfide has been reported as potent antioxidant, its effects on Hcy-induced mitochondrial dysfunctions have not been studied. Therefore, the present study has been designed to evaluate the protective effect of NaHS on Hcy-induced mitochondrial dysfunctions in brain. NaHS supplementation decreased reactive oxygen species and nitrite levels in the cortex and hippocampus of animals with HHcy. NaHS supplementation increased the activity of mitochondrial electron transport chain components; NADH dehydrogenase, cytochrome c oxidase and F0-F1 ATPase in the cortex and hippocampus of HHcy animals along with in-gel activity of complex I - complex V in the mitochondria isolated from the cortex and hippocampus of HHcy animals. Moreover, NaHS supplementation also increased the mitochondrial complex I, II and IV mediated oxygen consumption rate in Hcy treated mitochondria. NaHS administration prevented the Hcy-induced mitochondrial damage as suggested by the decreased mitochondrial swelling in the cortex and hippocampus of HHcy animals. NaHS supplementation decreased the activity of lactate dehydrogenase isozymes (1-5) in the brain regions of HHcy animals. The expression of protein kinase c δ was also decreased in the brain regions of HHcy animals following NaHS supplementation. This was accompanied by reduced activity of caspase-3 indicating anti-apoptotic effect of H₂S. Taken together, the findings suggest that H₂S supplementation ameliorates Hcy-induced oxidative stress and mitochondrial dysfunctions suggesting H₂S releasing drugs may be a novel therapeutic approach to treat HHcy associated neurological disorders.

The effects of diltiazem on growth, reproduction, energy reserves, and calcium-dependent physiology in Daphnia magna

With the growth of both the pharmaceutical industry and the human population and longevity, more drugs are used and processed each day. Inevitably, these pharmaceuticals enter wastewater through human excretion and improper disposal of leftovers. One such medication, diltiazem, a calcium channel blocker, is of importance due to its widespread consumption, and prevalence in aquatic environments. To study the sub-lethal effects of diltiazem on aquatic animals, we investigated its impacts no feeding behaviour, heart rate, respiration, growth, and reproduction of a bioindicator species, Daphnia magna. When exposed to environmentally relevant concentrations, D. magna increased their heart rate by 12% and oxygen consumption by 48%. However, exposure did not have any effects on thoracic limb movement frequency or peristalsis (i.e. feeding behaviour). Individuals exposed to diltiazem for a longer duration (16 days) showed a 44% decrease in lipid reserves and produced between 17 and 28% fewer neonates which were 10-12% larger. Our study demonstrated that exposure to diltiazem creates an energy imbalance in D. magna which could, in the long run, influence their populations.

Modulator role of infliximab and methotrexate through the transient receptor potential melastatin 2 (TRPM2) channel in neutrophils of patients with rheumatoid arthritis: a pilot study

INTRODUCTION

Rheumatoid arthritis (RA) is a chronic, systemic, inflammatory disease causing symmetric polyarthritis. In this study, we aimed to investigate the effects of infliximab (INF) and methotrexate (MTX) on apoptosis, oxidative stress, and calcium signaling in the neutrophils of RA patients.

MATERIAL AND METHODS

Neutrophils were isolated from 10 patients with newly diagnosed RA and 10 healthy controls. They were divided into four groups (control, RA, RA + MTX, RA + INF) and incubated with MTX and INF. In the cell viability (MTT) test, the ideal non-toxic dose and incubation time of MTX were found to be 0.1 mM and 1 h, respectively. The neutrophils were also incubated with the TRPM2 channel blocker N-(p-amylcinnamoyl) anthranilic acid (ACA).

RESULTS

Intracellular free Ca²⁺ concentration, intracellular reactive oxygen species (ROS) production, mitochondrial depolarization, lipid peroxidation, apoptosis, and caspase 3 and caspase 9 activities were found to be significantly higher in the neutrophils of RA patients compared to controls. MTT, reduced glutathione (GSH) level, and glutathione peroxidase (GSHPx) activity were significantly lower in the neutrophils of RA patients. However, MTT, GSH and GSHPx values were detected to be significantly increased with INF and MTX therapies. The Ca²⁺ concentrations were further decreased by the ACA therapy.

CONCLUSIONS

Our results suggest that INF and MTX are useful antagonists in apoptosis and mitochondrial oxidative stress in the neutrophils of RA patients. INF and MTX decreased the Ca²⁺ concentration through inhibition of the TRPM2 channel in the neutrophils of RA patients. It may be a new pathway in the mechanisms of anti-rheumatic drugs.

Albumin evokes Ca2+-induced cell oxidative stress and apoptosis through TRPM2 channel in renal collecting duct cells reduced by curcumin

In proteinuric nephropathies of chronic kidney disease, the epithelial cells of the nephron including the collecting duct are exposed to high concentrations of luminal albumin. Albumin is taken up from collecting duct cells by endocytosis causing excessive reactive oxygen species (ROS) production and a proinflammatory response. Curcumin used in the traditional medicine possesses anti-inflammatory and antioxidant effects. ROS and ADP-ribose (ADPR) activate the cation channel TRPM2. We hypothesize, that albumin-induced cell stress and proinflammatory response are mediated by Ca²⁺ and can be reduced by curcumin. The cortical collecting duct (CCD) cells mpkCCD_c14 exhibit spontaneous and inducible Ca²⁺ oscillations, which can be blocked by pre-treatment with curcumin. Curcumin accumulates in plasma membrane and intracellular vesicles, where it interferes with TRPM2 and decreases the influx of Ca²⁺. Albumin reduces cell viability and increases apoptosis, NF-κB activation, and mitochondrial membrane depolarization via Ca²⁺-dependent signaling, which results in increased ROS production. Albumin-induced cell stress is diminished by the inhibition of TRPM2 after administration of curcumin and ADPR (PARP1) inhibitors. Curcumin did not reduce the Ca2+ elevation induced by thapsigargin in Ca²⁺-free medium, but it reduced the function of store-operated Ca²⁺ channels and ATP-evoked Ca²⁺ response. In conclusion, albumin-induced oxidative stress is mediated by Ca²⁺-dependent signaling via TRPM2 and leads to cell damage and a proinflammatory response, strengthening the role of CCD cells in the progression of chronic kidney disease.

An Adverse Outcome Pathway Linking Organohalogen Exposure to Mitochondrial Disease

Adverse outcome pathways (AOPs) are pragmatic tools in human health hazard characterization and risk assessment. As such, one of the main goals of AOP development is to provide a clear, progressive, and linear mechanistic representation of pertinent toxicological key events (KEs) occurring along the different levels of biological organization. Here, we present an AOP framework that depicts how exposure to organohalogens can lead to mitochondrial disease. Organohalogens are disinfectant by-products (DBPs) found in our drinking water. Chloroform, trichloroacetic acid, and trichlorophenol were selected to represent specific types of organohalogens for the development of this AOP. Although each of these compounds contains chlorine atoms, they differ in aromaticity and solubility, which have a significant impact on their potency. This AOP consists of two main pathways, both of which are triggered by the molecular initiating event (MIE) of excessive reactive oxygen species generation. Pathway 1 details the downstream consequences of oxidative stress, which include mitochondrial DNA damage, protein aggregation, and depolarization of the mitochondrial membrane. Pathway 2 shows the KEs that result from inadequate supply of glutathione, including calcium dysregulation and ATP depletion. Pathways 1 and 2 converge at a common KE: opening of the mitochondrial membrane transition pore (mPTP). This leads to the release of cytochrome c, caspase activation, apoptosis, and mitochondrial disease. This AOP was developed according to the Organisation for Economic Co-operation and Development guidance, including critical consideration of the Bradford Hill criteria for Weight of Evidence assessment and key questions for evaluating confidence. The presented AOP is expected to serve as the basis for designing new toxicological tests as well as the characterization of novel biomarkers for disinfectant by-product exposure and adverse health effects.

ADP-Ribose and oxidative stress activate TRPM8 channel in prostate cancer and kidney cells

Activation of TRPM8 channel through oxidative stress may induce Ca²⁺ and pro-apoptotic signals in prostate cancer and kidney cells. The aim of this study was to evaluate activation of TRPM8 can increase apoptosis and oxidative stress in the prostate cancer (Du145^M8), TRPM8 knock out (Du 145^M8KO), transfected (HEK293^TM8) and non-transfected human kidney (HEK293) cells. Intracellular Ca²⁺ responses to TRPM8 activation were increased in the Du145^M8 and HEK293^TM8 cells from coming cumene hydrogen peroxide (CHPx), menthol, ADP-Ribose (ADPR), but not in the HEK293 and Du 145^M8KO cells. The intracellular Ca²⁺ responses to both ADPR and CHPx were totally inhibited by the thiol cycle antioxidant glutathione, and TRPM8 blockers (N-(p-amylcinnamoyl)anthranilic acid and capsazepine). Apoptosis, Annexin V, mitochondrial membrane depolarization, intracellular ROS, caspase 3 and 9 values were increased through TRPM8 activation in the Du 145^M8 but not in the Du 145^M8KO and non-transfected HEK293 cells by CHPx and hydrogen peroxide. In conclusion, apoptotic and oxidant effects on the cells were increased activation of TRPM8 by oxidative stress and ADPR. Activation of TRPM8 through oxidative stress and ADPR in the cells could be used as an effective strategy in the treatment of prostate cancer cells.

Ligand-displacement-based two-photon fluorogenic probe for visualizing mercapto biomolecules in live cells, Drosophila brains and zebrafish

Investigating the change in expression level of mercapto biomolecules (GSH/Cys/Hcy) necessitates a rapid detection method for a series of physiological and pathological processes. Herein, we present a ligand-displacement-based two-photon fluorogenic probe based on an Fe(iii) complex, TPFeS, which is a GSH/Cys/Hcy rapid detection fluorogenic probe for in vitro analysis and live cell/tissue/in vivo imaging. The "in situ" probe is non-fluorescent and was prepared from a 1 : 2 ratio of Fe(iii) and TPS, a novel two-photon (TP) fluorophore with excellent one-photon (OP) and TP properties under physiological conditions, as a fluorescent ligand. This probe shows a rapid and remarkable fluorescence restoration (OFF-ON) property due to the ligand-displacement reaction of mercapto biomolecules in a recyclable manner in vitro. A significant two-photon action cross-section, good selectivity for biothiols, low cytotoxicity, and insensitivity to pH over the biologically relevant pH range allowed the direct visualization of mercapto biomolecules at different levels between normal/drug-treated live cells, as well as in Drosophila brain tissues/zebrafish based on the use of two-photon fluorescence microscopy.

Docosahexaenoic Acid (DHA) Provides Neuroprotection in Traumatic Brain Injury Models via Activating Nrf2-ARE Signaling

In this study, we explored the neuroprotective effects of docosahexaenoic acid (DHA) in traumatic brain injury (TBI) models. In this study, we first confirmed that DHA was neuroprotective against TBI via the NSS test and Morris water maze experiment. Western blot was conducted to identify the expression of Bax, caspase-3, and Bcl-2. And the cell apoptosis of the TBI models was validated by TUNEL staining. Relationships between nuclear factor erythroid 2-related factor 2-antioxidant response element (Nrf2-ARE) pathway-related genes and DHA were explored by RT-PCR and Western blot. Rats of the DHA group performed remarkably better than those of the TBI group in both NSS test and water maze experiment. DHA conspicuously promoted the expression of Bcl-2 and diminished that of cleaved caspase-3 and Bax, indicating the anti-apoptotic role of DHA. Superoxide dismutase (SOD) activity and cortical malondialdehyde content, glutathione peroxidase (GPx) activity were renovated in rats receiving DHA treatment, implying that the neuroprotective influence of DHA was derived from lightening the oxidative stress caused by TBI. Moreover, immunofluorescence and Western blot experiments revealed that DHA facilitated the translocation of Nrf2 to the nucleus. DHA administration also notably increased the expression of the downstream factors NAD(P)H:quinone oxidoreductase (NQO-1) and heme oxygenase 1(HO-1). DHA exerted neuroprotective influence on the TBI models, potentially through activating the Nrf2- ARE pathway.

TRPM2 in the Brain: Role in Health and Disease

Transient receptor potential (TRP) proteins have been implicated in several cell functions as non-selective cation channels, with about 30 different mammalian TRP channels having been recognized. Among them, TRP-melastatin 2 (TRPM2) is particularly involved in the response to oxidative stress and inflammation, while its activity depends on the presence of intracellular calcium (Ca²⁺). TRPM2 is involved in several physiological and pathological processes in the brain through the modulation of multiple signaling pathways. The aim of the present review is to provide a brief summary of the current insights of TRPM2 role in health and disease to focalize our attention on future potential neuroprotective strategies.