Whey protein powder with milk fat globule membrane attenuates Alzheimer's disease pathology in 3×Tg-AD mice by modulating neuroinflammation through the peroxisome proliferator-activated receptor γ signaling pathway.

Whey protein powder (PP), which is mainly derived from bovine milk, is rich in milk fat globule membrane (MFGM). The MGFM has been shown to play a role in promoting neuronal development and cognition in the infant brain. However, its role in Alzheimer's disease (AD) has not been elucidated. Here, we showed that the cognitive ability of 3×Tg-AD mice (a triple-transgenic mouse model of AD) could be improved by feeding PP to mice for 3 mo. In addition, PP ameliorated amyloid peptide deposition and tau hyperphosphorylation in the brains of AD mice. We found that PP could alleviate AD pathology by inhibiting neuroinflammation through the peroxisome proliferator-activated receptor γ (PPARγ)-nuclear factor-κB signaling pathway in the brains of AD mice. Our study revealed an unexpected role of PP in regulating the neuroinflammatory pathology of AD in a mouse model.

Liposome-Based Carriers for CRISPR Genome Editing.

The CRISPR-based genome editing technology, known as clustered regularly interspaced short palindromic repeats (CRISPR), has sparked renewed interest in gene therapy. This interest is accompanied by the development of single-guide RNAs (sgRNAs), which enable the introduction of desired genetic modifications at the targeted site when used alongside the CRISPR components. However, the efficient delivery of CRISPR/Cas remains a challenge. Successful gene editing relies on the development of a delivery strategy that can effectively deliver the CRISPR cargo to the target site. To overcome this obstacle, researchers have extensively explored non-viral, viral, and physical methods for targeted delivery of CRISPR/Cas9 and a guide RNA (gRNA) into cells and tissues. Among those methods, liposomes offer a promising approach to enhance the delivery of CRISPR/Cas and gRNA. Liposomes facilitate endosomal escape and leverage various stimuli such as light, pH, ultrasound, and environmental cues to provide both spatial and temporal control of cargo release. Thus, the combination of the CRISPR-based system with liposome delivery technology enables precise and efficient genetic modifications in cells and tissues. This approach has numerous applications in basic research, biotechnology, and therapeutic interventions. For instance, it can be employed to correct genetic mutations associated with inherited diseases and other disorders or to modify immune cells to enhance their disease-fighting capabilities. In summary, liposome-based CRISPR genome editing provides a valuable tool for achieving precise and efficient genetic modifications. This review discusses future directions and opportunities to further advance this rapidly evolving field.

Gas chromatography/mass spectrometry measurement of xenon in gas-loaded liposomes for neuroprotective applications.

RATIONALE: We have produced a liposomal formulation of xenon (Xe-ELIP) as a neuroprotectant for inhibition of brain damage in stroke patients. This mandates development of a reliable assay to measure the amount of dissolved xenon released from Xe-ELIP in water and blood samples. METHODS: Gas chromatography/mass spectrometry (GC/MS) was used to quantify xenon gas released into the headspace of vials containing Xe-ELIP samples in water or blood. In order to determine blood concentration of xenon in vivo after Xe-ELIP administration, 6 mg of Xe-ELIP lipid was infused intravenously into rats. Blood samples were drawn directly from a catheterized right carotid artery. After introduction of the samples, each vial was allowed to equilibrate to 37°C in a water bath, followed by 20 minutes of sonication prior to headspace sampling. Xenon concentrations were calculated from a gas dose-response curve and normalized using the published xenon water-gas solubility coefficient. RESULTS: The mean corrected percent of xenon from Xe-ELIP released into water was 3.87 ± 0.56% (SD, n = 8), corresponding to 19.3 ± 2.8 µL/mg lipid, which is consistent with previous independent Xe-ELIP measurements. The corresponding xenon content of Xe-ELIP in rat blood was 23.38 ± 7.36 µL/mg lipid (n = 8). Mean rat blood xenon concentration after intravenous administration of Xe-ELIP was 14 ± 10 µM, which is approximately 15% of the estimated neuroprotective level. CONCLUSIONS: Using this approach, we have established a reproducible method for measuring dissolved xenon in fluids. These measurements have established that neuroprotective effects can be elicited by less than 20% of the calculated neuroprotective xenon blood concentration. More work will have to be done to establish the protective xenon pharmacokinetic range. Copyright © 2016 John Wiley & Sons, Ltd.

[Clinical effect of anti-D immunoglobulin in treatment of childhood immune thrombocytopenia: a Meta analysis].

OBJECTIVE: To investigate the clinical effect and safety of anti-D immunoglobulin (anti-D) in the treatment of children with newly diagnosed acute immune thrombocytopenia (ITP) through a Meta analysis. METHODS: PubMed, EMBASE, Cohrane Library, Ovid, CNKI, and Wanfang Data were searched for randomized controlled trials (RCTs) published up to April 2017. Review Manager 5.3 was used for the Meta analysis. RESULTS: Seven RCTs were included. The Meta analysis showed that after 72 hours and 7 days of treatment, the intravenous immunoglobulin (IVIG) group had a significantly higher percentage of children who achieved platelet count >20×109/L than the anti-D group (P<0.05). There were no significant differences in platelet count after 24 hours, 72 hours, and 7 days of treatment between the anti-D (50 µg/kg) group and the IVIG group (P>0.05), and there were also no significant differences in platelet count after 24 hours and 7 days of treatment between the 50 µg/kg and 75 µg/kg anti-D groups (P>0.05). The anti-D group had a significantly greater reduction in the hemoglobin level than the IVIG group after treatment, but did not need transfusion. No children in the anti-D group or the IVIG group experienced serious adverse reactions. CONCLUSIONS: Intravenous injection of anti-D may have a similar effect as IVIG in improving platelet count in children with acute ITP, but it may be slightly inferior to IVIG in the rate of platelet increase after treatment. The anti-D dose of 50 µg/kg may have a similar effect as 75 µg/kg. The recommended dose of anti-D for treatment of ITP is safe.

Ultrasound-enhanced bevacizumab release from echogenic liposomes for inhibition of atheroma progression.

CONTEXT: Bevacizumab (BEV) is a monoclonal antibody to vascular endothelial growth factor (VEGF) that ameliorates atheroma progression by inhibiting neovascularization. OBJECTIVE: We aimed to determine whether BEV release from echogenic liposomes (BEV-ELIP) could be enhanced by color Doppler ultrasound (US) and whether the released BEV inhibits VEGF expression by endothelial cells in vitro. MATERIALS AND METHODS: BEV-ELIP samples were subjected to 6 MHz color Doppler ultrasound (MI = 0.4) for 5 min. We assessed release of BEV with a direct ELISA and with fluoresceinated BEV (FITC-BEV) loaded into ELIP by the same method. Human umbilical vein endothelial cell (HUVEC) cultures were stimulated to express VEGF by 10 nM phorbol-12-myristate 13-acetate (PMA). Cell-associated VEGF levels were determined using a cell-based ELISA. RESULTS: Overall, US caused an additional 100 µg of BEV to be released or exposed per BEV-ELIP aliquot within 60 min BEV-ELIP treated with US inhibited VEGF expression by 90% relative to non-treated controls and by 70% relative to BEV-ELIP without US. Also, US-treated BEV-ELIP inhibited HUVEC proliferation by 64% relative to untreated controls and by 45% relative to BEV-ELIP without US. DISCUSSION AND CONCLUSION: We have demonstrated that BEV-ELIP retains its VEGF-binding activity in a liposomal formulation and that clinical Doppler US can significantly increase that activity, both by releasing free BEV and by enhancing the surface exposure of the immunoreactive antibody.

Impulse response method for characterization of echogenic liposomes.

An optical characterization method is presented based on the use of the impulse response to characterize the damping imparted by the shell of an air-filled ultrasound contrast agent (UCA). The interfacial shell viscosity was estimated based on the unforced decaying response of individual echogenic liposomes (ELIP) exposed to a broadband acoustic impulse excitation. Radius versus time response was measured optically based on recordings acquired using an ultra-high-speed camera. The method provided an efficient approach that enabled statistical measurements on 106 individual ELIP. A decrease in shell viscosity, from 2.1 × 10(-8) to 2.5 × 10(-9) kg/s, was observed with increasing dilatation rate, from 0.5 × 10(6) to 1 × 10(7) s(-1). This nonlinear behavior has been reported in other studies of lipid-shelled UCAs and is consistent with rheological shear-thinning. The measured shell viscosity for the ELIP formulation used in this study [κs = (2.1 ± 1.0) × 10(-8) kg/s] was in quantitative agreement with previously reported values on a population of ELIP and is consistent with other lipid-shelled UCAs. The acoustic response of ELIP therefore is similar to other lipid-shelled UCAs despite loading with air instead of perfluorocarbon gas. The methods described here can provide an accurate estimate of the shell viscosity and damping for individual UCA microbubbles.

Use of thermodynamic coupling between antibody-antigen binding and phospholipid acyl chain phase transition energetics to predict immunoliposome targeting affinity.

Thermodynamic analysis of ligand-target binding has been a useful tool for dissecting the nature of the binding mechanism and, therefore, potentially can provide valuable information regarding the utility of targeted formulations. Based on a consistent coupling of antibody-antigen binding and gel-liquid crystal transition energetics observed for antibody-phosphatidylethanolamine (Ab-PE) conjugates, we hypothesized that the thermodynamic parameters and the affinity for antigen of the Ab-PE conjugates could be effectively predicted once the corresponding information for the unconjugated antibody is determined. This hypothesis has now been tested in nine different antibody-targeted echogenic liposome (ELIP) preparations, where antibody is conjugated to dipalmitoylphosphatidylethanolamine (DPPE) head groups through a thioether linkage. Predictions were satisfactory (affinity not significantly different from the population of values found) in five cases (55.6%), but the affinity of the unconjugated antibody was not significantly different from the population of values found in six cases (66.7%), indicating that the affinities of the conjugated antibody tended not to deviate appreciably from those of the free antibody. While knowledge of the affinities of free antibodies may be sufficient to judge their suitability as targeting agents, thermodynamic analysis may still provide valuable information regarding their usefulness for specific applications.

Efficient Gene Editing for Heart Disease via ELIP-Based CRISPR Delivery System.

Liposomes as carriers for CRISPR/Cas9 complexes represent an attractive approach for cardiovascular gene therapy. A critical barrier to this approach remains the efficient delivery of CRISPR-based genetic materials into cardiomyocytes. Echogenic liposomes (ELIP) containing a fluorescein isothiocyanate-labeled decoy oligodeoxynucleotide against nuclear factor kappa B (ELIP-NF-κB-FITC) were used both in vitro on mouse neonatal ventricular myocytes and in vivo on rat hearts to assess gene delivery efficacy with or without ultrasound. In vitro analysis was then repeated with ELIP containing Cas9-sg-IL1RL1 (interleukin 1 receptor-like 1) RNA to determine the efficiency of gene knockdown. ELIP-NF-κB-FITC without ultrasound showed limited gene delivery in vitro and in vivo, but ultrasound combined with ELIP notably improved penetration into heart cells and tissues. When ELIP was used to deliver Cas9-sg-IL1RL1 RNA, gene editing was successful and enhanced by ultrasound. This innovative approach shows promise for heart disease gene therapy using CRISPR technology.

Co-Delivery of Therapeutics and Bioactive Gas Using a Novel Liposomal Platform for Enhanced Treatment of Acute Arterial Injury.

Atherosclerosis is a complex, multi-stage disease characterized by pathological changes across the vascular wall. Endothelial dysfunction, inflammation, hypoxia, and vascular smooth muscle cell proliferation contribute to its progression. An effective strategy capable of delivering pleiotropic treatment to the vascular wall is essential to limit neointimal formation. Echogenic liposomes (ELIP), which can encapsulate bioactive gases and therapeutic agents, have the potential to deliver enhanced penetration and treatment efficacy for atherosclerosis. In this study, liposomes loaded with nitric oxide (NO) and rosiglitazone, a peroxisome proliferator-activated receptor agonist, were prepared using hydration, sonication, freeze-thawing, and pressurization. The efficacy of this delivery system was evaluated in a rabbit model of acute arterial injury induced by balloon injury to the common carotid artery. Intra-arterial administration of rosiglitazone/NO co-encapsulated liposomes (R/NO-ELIP) immediately following injury resulted in reduced intimal thickening after 14 days. The anti-inflammatory and anti-proliferative effects of the co-delivery system were investigated. These liposomes were echogenic, enabling ultrasound imaging to assess their distribution and delivery. R/NO-ELIP delivery exhibited a greater attenuation (88 ± 15%) of intimal proliferation when compared to NO-ELIP (75 ± 13%) or R-ELIP (51 ± 6%) delivery alone. The study demonstrates the potential of echogenic liposomes as a promising platform for ultrasound imaging and therapeutic delivery.

Storage Stability of Atheroglitatide, an Echogenic Liposomal Formulation of Pioglitazone Targeted to Advanced Atheroma with a Fibrin-Binding Peptide.

We have conducted a stability study of a complex liposomal pharmaceutical product, Atheroglitatide (AGT), stored at three temperatures, 4, 24, and 37 °C, for up to six months. The six parameters measured were functions of liposomal integrity (size and number), drug payload (loading efficiency), targeting peptide integrity (conjugation efficiency and specific avidity), and echogenicity (ultrasound-dependent controlled drug release), which were considered most relevant to the product's intended use. At 4 °C, liposome diameter trended upward, indicative of aggregation, while liposome number per mg lipid and echogenicity trended downward. At 24 °C, peptide conjugation efficiency (CE) and targeting efficiency (TE, specific avidity) trended downward. At 37 °C, CE and drug (pioglitazone) loading efficiency trended downward. At 4 °C, the intended storage temperature, echogenicity, and liposome size reached their practical tolerance limits at 6 months, fixing the product expiration at that point. Arrhenius analysis of targeting peptide CE and drug loading efficiency decay at the higher temperatures indicated complete stability of these characteristics at 4 °C. The results of this study underscore the storage stability challenges presented by complex nanopharmaceutical formulations.

Enhanced Cerebroprotection of Xenon-Loaded Liposomes in Combination with rtPA Thrombolysis for Embolic Ischemic Stroke.

Xenon (Xe) has shown great potential as a stroke treatment due to its exceptional ability to protect brain tissue without inducing side effects. We have previously developed Xe-loaded liposomes for the ultrasound-activated delivery of Xe into the cerebral region and demonstrated their therapeutic efficacy. At present, the sole FDA-approved thrombolytic agent for stroke treatment is recombinant tissue plasminogen activator (rtPA). In this study, we aimed to investigate the potential of combining Xe-liposomes with an intravenous rtPA treatment in a clinically relevant embolic rat stroke model. We evaluated the combinational effect using an in vitro clot lysis model and an in vivo embolic middle cerebral artery occlusion (eMCAO) rat model. The treatment groups received intravenous administration of Xe-liposomes (20 mg/kg) at 2 h post-stroke onset, followed by the administration of rtPA (10 mg/kg) at either 2 or 4 h after the onset. Three days after the stroke, behavioral tests were conducted, and brain sections were collected for triphenyltetrazolium chloride (TTC) and TUNEL staining. Infarct size was determined as normalized infarct volume (%). Both in vitro and in vivo clot lysis experiments demonstrated that Xe-liposomes in combination with rtPA resulted in effective clot lysis comparable to the treatment with free rtPA alone. Animals treated with Xe-liposomes in combination with rtPA showed reduced TUNEL-positive cells and demonstrated improved neurological recovery. Importantly, Xe-liposomes in combination with late rtPA treatment reduced rtPA-induced hemorrhage, attributing to the reduction of MMP9 immunoreactivity. This study demonstrates that the combined therapy of Xe-liposomes and rtPA provides enhanced therapeutic efficacy, leading to decreased neuronal cell death and a potential to mitigate hemorrhagic side effects associated with late rtPA treatment.

An Echogenic Clot Method for Thrombolysis Monitoring in Thrombotic Stroke Models.

To demonstrate thrombolytic efficacy of a tissue plasminogen activator (tPA)-loaded echogenic liposome (TELIP) formulation in a rabbit thrombotic stroke model (the most relevant animal model for evaluation of directed thrombolytic therapy for ischemic stroke), we sought to develop a means of monitoring thrombus dissolution quantitatively by ultrasound imaging methods. We hypothesized that a gas-free ultrasound contrast agent can be incorporated into blood clots at a concentration that does not affect the tPA-mediated clot dissolution rate, while enabling quantitative assessment of the clot dissolution rate. Clots were formed from a mixture of whole rabbit blood, 1 M calcium chloride, human thrombin and varying amounts of microcrystalline cellulose. Washed clots in tubes were weighed at 30, 60 and 90 minutes after addition of recombinant tPA (rtPA) in porcine plasma (100 µg/ml). Clot echogenicity at each time point was assessed using a Philips HDI 5000 ultrasound system using an L12-5 linear array probe. Recorded Images underwent videodensitometric analysis that converted image reflectivity to mean gray scale values (MGSV). We found that 1.12 mg/ml of microcrystalline cellulose in rabbit blood clots (0.2 ml) provided optimal echogenicity without affecting clot dissolution rates (0.3-0.6 mg/min.) caused by rtPA. The clot dissolution rate measured by videodensitometric analysis of the echogenic clots agreed well with that determined by mass loss measurements (0.28% 0-time value/minute). This method will be important for demonstrating in vivo efficacy with potentially decreased hemorrhagic effects provided by directed tPA vehicles relative to systemic administration of the free thrombolytic.

Demonstration of ultrasound-mediated therapeutic delivery of fibrin-targeted pioglitazone-loaded echogenic liposomes into the arterial bed for attenuation of peri-stent restenosis.

Peri-stent restenosis following stent implantation is a major clinical problem. We have previously demonstrated that ultrasound-facilitated liposomal delivery of pioglitazone (PGN) to the arterial wall attenuated in-stent restenosis. To evaluate ultrasound mediated arterial delivery, in Yucatan miniswine, balloon inflations were performed in the carotid and subclavian arteries to simulate stent implantation and induce fibrin formation. The fibrin-binding peptide, GPRPPGGGC, was conjugated to echogenic liposomes (ELIP) containing dinitrophenyl-L-alanine-labelled pioglitazone (DNP-PGN) for targeting purposes. After pre-treating the arteries with nitroglycerine, fibrin-binding peptide-conjugated PGN-loaded ELIP (PAFb-DNP-PGN-ELIP also termed atheroglitatide) were delivered to the injured arteries via an endovascular catheter with an ultrasound core, either with or without ultrasound application (EKOSTM Endovascular System, Boston Scientific). In arteries treated with atheroglitatide, there was substantial delivery of PGN into the superficial layers (5 µm from the lumen) of the arteries with and without ultrasound, [(1951.17 relative fluorescence units (RFU) vs. 1901.17 RFU; P-value = 0.939)]. With ultrasound activation there was increased penetration of PGN into the deeper arterial layers (up to 35 µm from the lumen) [(13195.25 RFU vs. 7681.00 RFU; P-value = 0.005)]. These pre-clinical data demonstrate ultrasound mediated therapeutic vascular delivery to deeper layers of the injured arterial wall. This model has the potential to reduce peri- stent restenosis.

Passive imaging with pulsed ultrasound insonations.

Previously, passive cavitation imaging has been described in the context of continuous-wave high-intensity focused ultrasound thermal ablation. However, the technique has potential use as a feedback mechanism for pulsed-wave therapies, such as ultrasound-mediated drug delivery. In this paper, results of experiments and simulations are reported to demonstrate the feasibility of passive cavitation imaging using pulsed ultrasound insonations and how the images depend on pulsed ultrasound parameters. The passive cavitation images were formed from channel data that was beamformed in the frequency domain. Experiments were performed in an invitro flow phantom with an experimental echo contrast agent, echogenic liposomes, as cavitation nuclei. It was found that the pulse duration and envelope have minimal impact on the image resolution achieved. The passive cavitation image amplitude scales linearly with the cavitation emission energy. Cavitation images for both stable and inertial cavitation can be obtained from the same received data set.

Repetitive xenon treatment improves post-stroke sensorimotor and neuropsychiatric dysfunction.

Stroke is a life-changing event as stroke survivors experience changes in personality, emotions and mood. We investigated the effect of xenon gas encapsulated in liposomes on stroke-generated sensorimotor impairments, and anxiety- and depression-like phenotypes. Ischemic stroke was created by the intraluminal middle cerebral artery occlusion (MCAO) for 6 h followed by reperfusion in rats. Xenon-liposome (6 mg/kg, intravenous) treatment was given multiple times starting at 2 h post-ischemia through 6 h (5X), and once-daily for next 3 days. Rats underwent ischemic injury displayed sensorimotor deficits in the adhesive removal, vibrissae-evoked forelimb placement and rotarod tests. These animals also made lesser entries and spent less time on open arms of the elevated-plus maze and swam more in passive mode in the forced swimming test, indicating anxiety- and depression-like behaviors at 28- and 35-days post-injury, respectively. Repeated intravenous treatment with xenon-liposomes ameliorated these behavioral aberrations (p < 0.05). Gut microbiome analysis (16S ribosomal-RNA gene sequencing) showed a decrease in the Clostridium clusters XI, XIVa, XVIII and Lactobacillus bacterium, and increase of the Prevotella in the xenon-liposome group. No microbiota communities were majorly affected across the treatments. Moreover, xenon treatment group showed augmented plasma levels of IL-6 cytokines (∼5 fold) on day-35 post-ischemia, while no change was noticed in the IL-1ß, IL-4, IL-10, IL-13 and MCP-1 levels. Our data highlights the safety, behavioral recovery and reversal of post-stroke brain injury following xenon-liposome treatment in an extended ischemic model. These results show the potential for this treatment strategy to be translated to patients with stroke.

Reversal of Lipid Metabolism Dysregulation by Selenium and Folic Acid Co-Supplementation to Mitigate Pathology in Alzheimer's Disease.

Aberrant lipid metabolism is reported to be closely related to the pathogenesis of neurodegenerative diseases, such as Alzheimer's disease (AD). Selenium (Se) and folate are two ideal and safe nutritional supplements, whose biological effects include regulating redox and homocysteine (Hcy) homeostasis in vivo. Here, to achieve effective multitarget therapy for AD, we combined Se and folic acid in a co-supplementation regimen (Se-FA) to study the therapeutic potential and exact mechanism in two transgenic mouse models of AD (APP/Tau/PSEN and APP/PS1). In addition to a reduction in Aß generation and tau hyperphosphorylation, a restoration of synaptic plasticity and cognitive ability was observed in AD mice upon Se-FA administration. Importantly, by using untargeted metabolomics, we found that these improvements were dependent on the modulation of brain lipid metabolism, which may be associated with an antioxidant effect and the promotion of Hcy metabolism. Thus, from mechanism to effects, this study systematically investigated Se-FA as an intervention for AD, providing important mechanistic insights to inform its potential use in clinical trials.

In vivo therapeutic gas delivery for neuroprotection with echogenic liposomes.

BACKGROUND: Ischemia-related neurological injury is a primary cause of stroke disability. Studies have demonstrated that xenon (Xe) may have potential as an effective and nontoxic neuroprotectant. Xe delivery is, however, hampered by lack of suitable administration methods. We have developed a pressurization-freeze method to encapsulate Xe into echogenic liposomes (Xe-ELIP) and have modulated local gas release with transvascular ultrasound exposure. METHODS AND RESULTS: Fifteen microliters of Xe were encapsulated into each 1 mg of liposomes (70% Xe and 30% argon). Xe delivery from Xe-ELIP into cells and consequent neuroprotective effects were evaluated with oxygen/glucose-deprived and control neuronal cells in vitro. Xe-ELIP were administered into Sprague-Dawley rats intravenously or intra-arterially after right middle cerebral artery occlusion. One-megahertz low-amplitude (0.18 MPa) continuous wave ultrasound directed onto the internal carotid artery triggered Xe release from circulating Xe-ELIP. Effects of Xe delivery on ischemia-induced neurological injury and disability were evaluated. Xe-ELIP delivery to oxygen/glucose-deprived neuronal cells improved cell viability in vitro and resulted in a 48% infarct volume decrease in vivo. Intravenous Xe-ELIP administration in combination with the ultrasound directed onto the carotid artery enhanced local Xe release from circulating Xe-ELIP and demonstrated 75% infarct volume reduction. This was comparable to the effect after intra-arterial administration. Behavioral tests on limb placement and grid and beam walking correlated with infarct reduction. CONCLUSIONS: This novel methodology may provide a noninvasive strategy for ultrasound-enhanced local therapeutic gas delivery for cerebral ischemia-related injury while minimizing systemic side effects.

Corrigendum: Selenomethionine Improves Mitochondrial Function by Upregulating Mitochondrial Selenoprotein in a Model of Alzheimer's Disease.

[This corrects the article DOI: 10.3389/fnagi.2021.750921.].

Selenomethionine Improves Mitochondrial Function by Upregulating Mitochondrial Selenoprotein in a Model of Alzheimer's Disease.

Alzheimer's disease (AD), the most common neurodegenerative disease in elderly humans, is pathologically characterized by amyloid plaques and neurofibrillary tangles. Mitochondrial dysfunction that occurs in the early stages of AD, which includes dysfunction in mitochondrial generation and energy metabolism, is considered to be closely associated with AD pathology. Selenomethionine (Se-Met) has been reported to improve cognitive impairment and reduce amyloid plaques and neurofibrillary tangles in 3xTg-AD mice. Whether Se-Met can regulate mitochondrial dysfunction in an AD model during this process remains unknown.In this study, the N2a-APP695-Swedish (N2aSW) cell and 8-month-old 3xTg-AD mice were treated with Se-Met in vitro and in vivo. Our study showed that the numbers of mitochondria were increased after treatment with Se-Met. Se-Met treatment also significantly increased the levels of NRF1 and Mfn2, and decreased those of OPA1 and Drp1. In addition, the mitochondrial membrane potential was significantly increased, while the ROS levels and apoptosis rate were significantly decreased, in cells after treatment with Se-Met. The levels of ATP, complex IV, and Cyt c and the activity of complex V were all significantly increased. Furthermore, the expression level of SELENO O was increased after Se-Met treatment. Thus, Se-Met can maintain mitochondrial dynamic balance, promote mitochondrial fusion or division, restore mitochondrial membrane potential, promote mitochondrial energy metabolism, inhibit intracellular ROS generation, and reduce apoptosis. These effects are most likely mediated via upregulation of SELENO O. In summary, Se-Met improves mitochondrial function by upregulating mitochondrial selenoprotein in these AD models.

Selenoprotein K deficiency-induced apoptosis: A role for calpain and the ERS pathway.

Selenoprotein K (SELENOK), an endoplasmic reticulum (ER) resident protein, is regulated by dietary selenium and expressed at a relatively high level in neurons. SELENOK has been shown to participate in oxidation resistance, calcium (Ca2+) flux regulation, and the ER-associated degradation (ERAD) pathway in immune cells. However, its role in neurons has not been elucidated. Here, we demonstrated that SELENOK gene knockout markedly enhanced ER stress (ERS) and increased apoptosis in neurons. SELENOK gene knockout elicited intracellular Ca2+ flux and activated the m-calpain/caspase-12 cascade, thus inducing neuronal apoptosis both in vivo and in vitro. In addition, SELENOK knockout significantly reduced cognitive ability and increased anxiety in 7-month-old mice. Our findings reveal an unexpected role of SELENOK in regulating ERS-induced neuronal apoptosis.