GPx-1-encoded adenoviral vector attenuates dopaminergic impairments induced by methamphetamine in GPx-1 knockout mice through modulation of NF-κB transcription factor

Application of mesenchymal stem cells for neurodegenerative diseases therapy discovery

Neurodegenerative diseases are central or peripheral nervous system disorders associated with progressive brain cell degeneration. Common neurodegenerative diseases such as Alzheimer's disease, Parkinson's disease, Huntington's disease, and amyotrophic lateral sclerosis have been widely studied. However, current therapeutics only reduce the symptoms and do not ameliorate the pathogenesis of these diseases. Recent studies suggested the roles of neuroinflammation, apoptosis, and oxidative stress in neurodegenerative diseases. Mesenchymal stem cells (MSCs) exert anti-apoptotic, anti-inflammatory, and antioxidative effects. Therefore, investigating the effects of MSCs and their applications may lead to the discovery of more effective therapies for neurodegenerative diseases. In this study, we review different approaches used to identify therapies for neurodegenerative diseases using MSCs.

Ginsenoside Re attenuates 8-OH-DPAT-induced serotonergic behaviors in mice via interactive modulation between PKCδ gene and Nrf2

It has been recognized that serotonergic blocker showed serious side effects, and that ginsenoside modulated serotonergic system with the safety. However, the effects of ginsenoside on serotonergic impairments remain to be clarified. Thus, we investigated ginsenoside Re (GRe), a major bioactive component in the mountain-cultivated ginseng on (±)-8-hydroxy-dipropylaminotetralin (8-OH-DPAT), a 5-HT_1A receptor agonist. In the present study, we observed that the treatment with GRe resulted in significant inhibition of protein kinase C δ (PKCδ) phosphorylation induced by the 5-HT_1A receptor agonist (±)-8-hydroxy-dipropylaminotetralin (8-OH-DPAT) in the hypothalamus of the wild-type (WT) mice. The inhibition of GRe was comparable with that of the PKCδ inhibitor rottlerin or the 5-HT_1A receptor antagonist WAY100635 (WAY). 8-OH-DPAT-induced significant reduction in nuclear factor erythroid-2-related factor 2 (Nrf2)-related system (i.e., Nrf2 DNA binding activity, γ-glutamylcysteine ligase modifier (GCLm) and γ-glutamylcysteine ligase catalytic (GCLc) mRNA expression, and glutathione (GSH)/oxidized glutathione (GSSG) ratio) was significantly attenuated by GRe, rottlerin, or WAY in WT mice. However, PKCδ gene knockout significantly protected the Nrf2-dependent system from 8-OH-DPAT insult in mice. Increases in 5-hydroxytryptophan (5-HT) turnover rate, overall serotonergic behavioral score, and hypothermia induced by 8-OH-DPAT were significantly attenuated by GRe, rottlerin, or WAY in WT mice. Consistently, PKCδ gene knockout significantly attenuated these parameters in mice. However, GRe or WAY did not provide any additional positive effects on the serotonergic protective potential mediated by PKCδ gene knockout in mice. Therefore, our results suggest that PKCδ is an important mediator for GRe-mediated protective activity against serotonergic impairments/oxidative burden caused by the 5-HT_1A receptor.

Ginsenoside Re mitigates memory impairments in aged GPx-1 KO mice by inhibiting the interplay between PAFR, NFκB, and microgliosis in the hippocampus

Ginsenoside Re (GRe) upregulates anti-aging klotho by mainly upregulating glutathione peroxidase-1 (GPx-1). However, the anti-aging mechanism of GPx-1 remains elusive. Here we investigated whether the GRe-mediated upregulation of GPx-1 modulates oxidative and proinflammatory insults. GPx-1 gene depletion altered redox homeostasis and platelet-activating factor receptor (PAFR) and nuclear factor kappa B (NFκB) expression, whereas the genetic overexpression of GPx-1 or GRe mitigated this phenomenon in aged mice. Importantly, the NFκB inhibitor pyrrolidine dithiocarbamate (PDTC) did not affect PAFR expression, while PAFR inhibition (i.e., PAFR knockout or ginkgolide B) significantly attenuated NFκB nuclear translocation, suggesting that PAFR could be an upstream molecule for NFκB activation. Iba-1-labeled microgliosis was more underlined in aged GPx-1 KO than in aged WT mice. Triple-labeling immunocytochemistry showed that PAFR and NFκB immunoreactivities were co-localized in Iba-1-positive populations in aged mice, indicating that microglia released these proteins. GRe inhibited triple-labeled immunoreactivity. The microglial inhibitor minocycline attenuated aging-related reduction in phospho-ERK. The effect of minocycline was comparable with that of GRe. GRe, ginkgolide B, PDTC, or minocycline also attenuated aging-evoked memory impairments. Therefore, GRe ameliorated aging-associated memory impairments in the absence of GPx-1 by inactivating oxidative insult, PAFR, NFkB, and microgliosis.

Effect of Administration of an Equal Dose of Selected Dietary Chemicals on Nrf2 Nuclear Translocation in the Mouse Liver

Certain dietary chemicals influenced the expression of chemopreventive genes through the Nrf2-Keap1 pathway. However, the difference in Nrf2 activation potency of these chemicals is not well studied. This study is aimed at determining the difference in the potency of liver Nrf2 nuclear translocation induced by the administration of equal doses of selected dietary chemicals in mice. Male ICR white mice were administered 50 mg/kg of sulforaphane, quercetin, curcumin, butylated hydroxyanisole, and indole-3-carbinol for 14 days. On day 15, the animals were sacrificed, and their livers were isolated. Liver nuclear extracts were prepared, and Nrf2 nuclear translocation was detected through Western blotting. To determine the implication of the Nrf2 nuclear translocation on the expression levels of several Nrf2-regulated genes, liver RNA was extracted for qPCR assay. Equal doses of sulforaphane, quercetin, curcumin, butylated hydroxyanisole, and indole-3-carbinol significantly induced the nuclear translocation of Nrf2 with different intensities and subsequently increased the expression of Nrf2-regulated genes with an almost similar pattern as the Nrf2 nuclear translocation intensities (sulforaphane > butylated hydroxyanisole = indole-3-carbinol > curcumin > quercetin). In conclusion, sulforaphane is the most potent dietary chemical that induces the Nrf2 translocation into the nuclear fraction in the mouse liver.

Machine Learning and Novel Biomarkers Associated with Immune Infiltration for the Diagnosis of Esophageal Squamous Cell Carcinoma

Esophageal squamous cell carcinoma (ESCC) accounts for the main esophageal cancer type, which is related to advanced stage and poor survivals. Therefore, novel diagnostic biomarkers are critically needed. In the current research, we aimed to screen novel diagnostic biomarkers based on machine learning. The expression profiles were obtained from GEO datasets (GSE20347, GSE38129, and GSE75241) and TCGA datasets. Differentially expressed genes (DEGs) were screened between 47 ESCC and 47 nontumor samples. The LASSO regression model and SVM-RFE analysis were carried out for the identification of potential markers. ROC analysis was carried out to assess discriminatory abilities. The expressions and diagnostic values of the candidates in ESCC were demonstrated in the GSE75241 datasets and TCGA datasets. We also explore the correlations between the critical genes and cancer immune infiltrates using CIBERSORT. In this study, we identified 27 DEGs in ESCC: 5 genes were significantly elevated, and 22 genes were significantly decreased. Based on the results of the SVM-RFE and LASSO regression model, we identified five potential diagnostic biomarkers for ESCC, including GPX3, COL11A1, EREG, MMP1, and MMP12. However, the diagnostic values of only GPX3, MMP1, and MMP12 were confirmed in GSE75241 datasets. Moreover, in TCGA datasets, we further confirmed that GPX3 expression was distinctly decreased in ESCC specimens, while the expression of MMP1 and MMP12 was noticeably increased in ESCC specimens. Immune cell infiltration analysis revealed that the expression of GPX3, MMP1, and MMP12 was associated with several immune, such as T cells CD8, macrophages M2, macrophages M0, and dendritic cells activated. Overall, our findings suggested GPX3, MMP1, and MMP12 as novel diagnostic marker and correlated with immune infiltrates in ESCC patients.

Genetic association between circulating selenium level and the risk of schizophrenia in the European population: A two-sample Mendelian randomization study

Background

The association between circulating the selenium level and the risk of schizophrenia remains unclear.

Objective

To determine the relationship between the circulating selenium level and the risk of schizophrenia, using the Mendelian Randomization method in the European population.

Methods

Single nucleotide polymorphisms (SNPs) associated with the circulating selenium level were identified at p < 5 × 10⁻⁸. The inverse variance weighted (IVW) method was used as the principal MR analysis, and MR Egger, weighted median, and MR PRESSO were used to determine the accuracy of IVW results. The Cochran's Q-test and Leave-One-Out sensitivity analysis were performed to evaluate the heterogeneity and stability of genetic variants on schizophrenia.

Results

The circulating selenium level was associated with decreased risk of schizophrenia by the IVW method (OR: 0.906, 95% CI:0.867–0.947). MR Egger, weighted median, and MR PRESSO methods got similar results. No heterogeneity was detected by the Cochran's Q-test, and no single SNP was driving the overall effect by leave-one-out analysis.

Conclusion

Our study provides support for the genetic relationship between the circulating selenium level and schizophrenia; the decreased circulating selenium level was associated with an elevated risk of schizophrenia.

Methamphetamine induced neurotoxic diseases, molecular mechanism, and current treatment strategies

Methamphetamine (MA) is a extremely addictive psychostimulant drug with a significant abuse potential. Long-term MA exposure can induce neurotoxic effects through oxidative stress, mitochondrial functional impairment, endoplasmic reticulum stress, the activation of astrocytes and microglial cells, axonal transport barriers, autophagy, and apoptosis. However, the molecular and cellular mechanisms underlying MA-induced neurotoxicity remain unclear. MA abuse increases the chances of developing neurotoxic conditions such as Parkinson's disease (PD), Alzheimer's disease (AD) and other neurotoxic diseases. MA increases the risk of PD by increasing the expression of alpha-synuclein (ASYN). Furthermore, MA abuse is linked to high chances of developing AD and subsequent neurodegeneration due to biological variations in the brain region or genetic and epigenetic variations. To date, there is no Food and Drug Administration (FDA)-approved therapy for MA-induced neurotoxicity, although many studies are being conducted to develop effective therapeutic strategies. Most current studies are now focused on developing therapies to diminish the neurotoxic effects of MA, based on the underlying mechanism of neurotoxicity. This review article highlights current research on several therapeutic techniques targeting multiple pathways to reduce the neurotoxic effects of MA in the brain, as well as the putative mechanism of MA-induced neurotoxicity.

Ginsenoside Re attenuates memory impairments in aged Klotho deficient mice via interactive modulations of angiotensin II AT1 receptor, Nrf2 and GPx-1 gene

Ginseng is known to possess anti-aging potential. Klotho mutant mice exhibit phenotypes that resemble the phenotype of the human aging process. Similar to Klotho deficient mice, patients with chronic kidney disease (CKD) suffer vascular damage and cognitive impairment, which might upregulate the angiotensin II AT1 receptor. Since AT1 receptor expression was more pronounced than endothelin ET-1 expression in the hippocampus of aged Klotho deficient (±) mice, we focused on the AT1 receptor in this study. Ginsenoside Re (GRe), but not ginsenoside Rb1 (GRb1), significantly attenuated the increase in AT1 receptor expression in aged Klotho deficient mice. Both GRe and the AT1 receptor antagonist losartan failed to attenuate the decrease in phosphorylation of JAK2/STAT3 in aged Klotho deficient (±) mice but significantly activated nuclear factor erythroid 2-related factor 2 (Nrf2)-mediated signaling. Both GRe and losartan attenuated the increased NADPH oxidase (NOX) activity and reactive oxygen species (ROS) in aged Klotho deficient mice. Furthermore, of all the antioxidant enzymes, GRe significantly increased glutathione peroxidase (GPx) activity. GRe significantly attenuated the reduced phosphorylation of ERK and CREB in GPx-1 knockout mice; however, genetic overexpression of GPx-1 did not significantly affect them in aged mice. Klotho-, Nrf2-, and GPx-1-immunoreactivities were co-localized in the same cells of the hippocampus in aged Klotho wild-type mice. Both the GPx inhibitor mercaptosuccinate and Nrf2 inhibitor brusatol counteracted the effects of GRe on all neurobehavioral impairments in aged Klotho deficient (±) mice. Our results suggest that GRe attenuates all alterations, such as AT1 receptor expression, NOX-, ROS-, and GPx-levels, and cognitive dysfunction in aged Klotho deficient (±) mice via upregulation of Nrf2/GPx-1/ERK/CREB signaling.

Glutathione Peroxidase 1 Protects Against Peroxynitrite-Induced Spiral Ganglion Neuron Damage Through Attenuating NF-κB Pathway Activation

Glutathione peroxidase 1 (GPX1) is a crucial antioxidant enzyme that prevented the harmful accumulation of intra-cellular hydrogen peroxide. GPX1 might contribute in limiting cochlear damages associated with aging or acoustic overexposure, but the function of GPX1 in the inner ear remains unclear. The present study was designed to investigate the effect of GPX1 on cochlear spiral ganglion neurons (SGNs) against oxidative stress induced by peroxynitrite, a versatile oxidant generated by the reaction of superoxide anion and nitric oxide. Here, we first found that the expression of GPX1 in cultured SGNs was downregulated after peroxynitrite exposure. Then, the GPX1 mimic ebselen and the gpx1 knockout (gpx1^–/–) mice were used to investigate the role of GPX1 in SGNs treated with peroxynitrite. The pretreatment with ebselen significantly increased the survived SGN numbers, inhibited the apoptosis, and enhanced the expression of 4-HNE in the cultured SGNs of peroxynitrite + ebselen group compared with the peroxynitrite-only group. On the contrary, remarkably less survived SGNs, more apoptotic SGNs, and the higher expression level of 4-HNE were detected in the peroxynitrite + gpx1^–/– group compared with the peroxynitrite-only group. Furthermore, rescue experiments with antioxidant N-acetylcysteine (NAC) showed that the expression of 4-HNE and the apoptosis in SGNs were significantly decreased, while the number of surviving SGNs was increased in peroxynitrite + NAC group compared the peroxynitrite-only group and in peroxynitrite + gpx1^–/– + NAC group vs. peroxynitrite + gpx1^–/– group. Finally, mechanistic studies showed that the activation of nuclear factor-kappa B (NF-κB) was involved in the SGNs damage caused by peroxynitrite and that GPX1 protected SGNs against peroxynitrite-induced damage, at least in part, via blocking the NF-κB pathway activation. Collectively, our findings suggest that GPX1 might serve as a new target for the prevention of nitrogen radical-induced SGNs damage and hearing loss.