Hypothesis and Theory: Characterizing Abnormalities of Energy Metabolism Using a Cellular Platform as a Personalized Medicine Approach for Alzheimer's Disease

Mitochondrial protective properties exerted by JM-20 in a dementia model induced by intracerebroventricular administration of streptozotocin in mice

BACKGROUND

Mitochondrial dysfunction and brain insulin resistance have been related to Alzheimer's disease (AD) development. Streptozotocin (STZ) is commonly employed to disrupt glucose and insulin metabolism, even causing cognitive impairment in animal models. We aimed at studying the protective effect of JM-20 on STZ-induced memory impairment and brain mitochondrial dysfunction.

METHODS

Male C57Bl6 mice received 3 mg/kg STZ intracerebroventricularly and JM-20 (0.25 mg/kg or 4 mg/kg) was administered daily by gastric gavage. Episodic memory was evaluated through Y-maze, novel object recognition, and Morris water maze. Endogenous antioxidant systems (catalase and superoxide dismutase activities), total sulfhydryl groups, malondialdehyde levels were also studied and acetylcholinesterase (AChE) activity were assessed in the prefrontal cortex (PC) and hippocampus (HO).

RESULTS

demonstrated that STZ injection impaired recognition and spatial learning and memory and oxygen flow in all mitochondrial respiration states. Additionally, STZ increased AChE, superoxide dismutase, and catalase activity in the PC but not in HO tissue. A neuroprotective effect of JM-20 on STZ-induced memory decline, and mitochondrial dysfunction was observed, suggesting an important causal interaction. In addition, JM-20 was able to decreased AChE enzyme hyperactivity, rescued endogenous antioxidant systems, and prevented histologically observed neuronal damage CONCLUSION: Our results indicate that JM-20 protects against STZ-induced impairment in brain bioenergetic metabolism and memory, confirming its potential as a candidate for treating neurodegenerative disorders associated with mitochondrial dysfunction like AD.

Mitochondrial calcium overload contributes to cannabinoid-induced paraptosis in hormone-responsive breast cancer cells

Studies have shown that natural products can induce paraptosis in tumour cell lines. Paraptosis is characterized by cytoplasmic vacuolation arising from the endoplasmic reticulum (ER) and mitochondria. The mechanism of paraptosis is unclear; however, dysregulation of Ca2+ homeostasis is believed to affect paraptosis induction. This study investigated the mechanism of cell death induced by a phytocannabinoid ratio in the MCF7 breast cancer cell line. The crystal violet assay was used to detect changes in viability and morphology changes were investigated using light and transmission electron microscopy. Various inhibitors, fluorescent staining with high-content screening, and Western blot analysis were used to investigate different cell death mechanisms. The phytocannabinoid ratio induced significant cell death and cytoplasmic vacuolation in MCF7 cells; however, no apoptosis, necrosis, autophagy, or ferroptosis was detected. Vacuolation induced by phytocannabinoid treatment was inhibited by cycloheximide, suggesting paraptosis induction. The mechanism of paraptosis induction was investigated, and it was found that treatment (1) induced ER dilation and mitochondrial swelling, (2) induced significant ER stress and mitochondrial Ca2+ overload and dysfunction, which appeared to be mediated by the voltage-dependent anion channel, and (3) significantly impaired all mitochondrial metabolic pathways. The data demonstrated that paraptosis induced by the cannabinoid ratio was mediated by Ca2+ flux from the ER to the mitochondria. These findings highlight a novel mechanism of cannabinoid-induced cell death and emphasize the anti-cancer potential of cannabinoid ratios, which exhibited enhanced effects compared to individual cannabinoids.

Identifying the earliest-occurring clinically targetable precursors of late-onset Alzheimer's disease

Most cases of Alzheimer's disease (AD) are late-onset dementias (LOAD). However, research on AD is predominantly of early-onset disease (EOAD). The determinants of EOAD, gene variants of APP and presenilin proteins, are not the basic precursors of LOAD. Rather, multiple other genes and associated cellular processes underlie risk for LOAD. These determinants could be modified in individuals at risk for LOAD well before signs and symptoms appear. Studying brain cells produced from patient-derived induced-pluripotent-stem-cells (iPSC), in culture, will be instrumental in developing such interventions. This paper summarises evidence accrued from iPSC culture models identifying the earliest occurring clinically targetable determinants of LOAD. Results obtained and replicated, thus far, suggest that abnormalities of bioenergetics, lipid metabolism, digestive organelle function and inflammatory activity are primary processes underlying LOAD. The application of cell culture platforms will become increasingly important in research and also on LOAD detection, assessment, and treatment in the years ahead.

Changes in Metabolism and Mitochondrial Bioenergetics during Polyethylene-Induced Osteoclastogenesis

Changes in mitochondrial bioenergetics are believed to take place during osteoclastogenesis. This study aims to assess changes in mitochondrial bioenergetics and reactive oxygen species (ROS) levels during polyethylene (PE)-induced osteoclastogenesis in vitro. For this purpose, RAW264.7 cells were cultured for nine days and allowed to differentiate into osteoclasts in the presence of PE and RANKL. The total TRAP-positive cells, resorption activity, expression of osteoclast marker genes, ROS level, mitochondrial bioenergetics, glycolysis, and substrate utilization were measured. The effect of tocotrienols-rich fraction (TRF) treatment (50 ng/mL) on those parameters during PE-induced osteoclastogenesis was also studied. During PE-induced osteoclastogenesis, as depicted by an increase in TRAP-positive cells and gene expression of osteoclast-related markers, higher proton leak, higher extracellular acidification rate (ECAR), as well as higher levels of ROS and NADPH oxidases (NOXs) were observed in the differentiated cells. The oxidation level of some substrates in the differentiated group was higher than in other groups. TRF treatment significantly reduced the number of TRAP-positive osteoclasts, bone resorption activity, and ROS levels, as well as modulating the gene expression of antioxidant-related genes and mitochondrial function. In conclusion, changes in mitochondrial bioenergetics and substrate utilization were observed during PE-induced osteoclastogenesis, while TRF treatment modulated these changes.

Nicotinamide riboside and caffeine partially restore diminished NAD availability but not altered energy metabolism in Alzheimer's disease

The redox co-factor nicotinamide adenine dinucleotide (NAD) declines with age, and NAD deficits are specifically associated with dysfunctional energy metabolism in late-onset Alzheimer's disease (LOAD). Nicotinamide riboside (NR), a dietary NAD precursor, has been suggested to ameliorate the aging process or neurodegeneration. We assessed whether NR with or without caffeine, which increases nicotinamide mononucleotide transferase subtype 2 (NMNAT2), an essential enzyme in NAD production, modulates bioenergetic functions in LOAD. In LOAD patients-and young or old control individuals-derived dermal fibroblasts as well as in induced pluripotent stem cell-differentiated neural progenitors and astrocytes, NR and caffeine cell type-specifically increased the NAD pool, transiently enhanced mitochondrial respiration or glycolysis and altered the expression of genes in the NAD synthesis or consumption pathways. However, continued treatment led to reversed bioenergetic effects. Importantly, NR and caffeine did not alter the characteristics of a previously documented inherent LOAD-associated bioenergetic phenotype. Thus, although NR and caffeine can partially restore diminished NAD availability, increasing NAD alone may not be sufficient to boost or restore energy metabolism in brain aging or alter aberrant energy management in LOAD. Nicotinamide riboside might still be of value in combination with other agents in preventive or therapeutic intervention strategies to address the aging process or age-associated dementia.

Ganoderic Acid A To Alleviate Neuroinflammation of Alzheimer's Disease in Mice by Regulating the Imbalance of the Th17/Tregs Axis

Ganoderic acid A (GAA) is a kind of lanostane-type triterpenoid isolated from Ganoderma lucidum. Imbalance of the Th17/Tregs axis exists in the progress of neuroinflammation of Alzheimer's disease (AD). In this study, the alleviating neuroinflammatory effect of GAA on d-galactose mice was studied from the aspect of regulating the imbalance of the Th17/Tregs axis. The Morris water maze test was used to evaluate the cognitive ability of AD mice. Flow cytometry was used to detect the percentages of IL-17A, IL-17F, IL-21, IL-22, and CD4⁺CD25⁺Foxp3⁺ in peripheral blood. Transmission electron microscopy was used to assess the cerebral mitochondrial ultrastructure. Metabolomic analysis based on gas chromatography-mass spectrometry was used to evaluate the mitochondrial dysfunction metabolism. Western blot analysis was used to detect the protein expressions of cytokines secreted by Th17 cells and Treg cells in the brain. As the results show, GAA has an alleviating neuroinflammatory effect on AD mice via regulating the imbalance of the Th17/Tregs axis. The potential mechanism was related to inhibition of the JAK/STAT signaling pathway induced by Th17 cells and enhancement of the mitochondrial oxidative phosphorylation by regulating Treg cells, thereby improving mitochondrial dysfunction of AD mice.