Citations

Abstract Background Alcohol use disorder (AUD) has been associated with the development of neurodegenerative diseases, including Alzheimer's disease (AD). However, recent studies demonstrate that moderate alcohol consumption may be protective against dementia and cognitive decline. Methods We examined astrocyte function, low-density lipoprotein (LDL) receptor-related protein 1 (LRP1), and the NF-κB p65 and IKK-α/β signaling pathways in modulating neuroinflammation and amyloid beta (Aβ) deposition. We assessed apolipoprotein E (ApoE) in the mouse brain using IHC and ELISA in response to moderate ethanol exposure (MEE). First, to confirm the intracerebral distribution of ApoE, we co-stained with GFAP, a marker for astrocytes that biosynthesize ApoE. We sought to investigate whether the ethanol-induced upregulation of LRP1 could potentially inhibit the activity of IL-1β and TNF-α induced IKK-α/β towards NF-κB p65, resulting in a reduction of pro-inflammatory cytokines. To evaluate the actual Aβ load in the brains of APP/PS1 mice, we performed with a specific antibody Aβ (Thioflavin S) on both air- and ethanol-exposed groups, subsequently analyzing Aβ levels. We also measured glucose uptake activity using 18F-FDG in APP/PS1 mice. Finally, we investigated whether MEE induced cognitive and memory changes using the Y maze, noble objective recognition (NOR) test, and Morris water maze (MWM). Results Our findings demonstrate that MEE reduced astrocytic glial fibrillary acidic protein (GFAP) and ApoE levels in the cortex and hippocampus in presymptomatic APP/PS1 mice. Interestingly, increased LRP1 protein expression is accompanied by dampening the IKK-α/β-NF-κB p65 pathway, resulting in decreased IL-1β and TNF-α levels in male mice. Notably, female mice show reduced anti-inflammatory cytokines, IL-4, and IL-10 levels without altering IL-1β and TNF-α concentrations. In both males and females, Aβ plaques, a hallmark of AD, were reduced in the cortex and hippocampus of ethanol-exposed presymptomatic APP/PS1 mice. Consistently, MEE increased fluorodeoxyglucose (FDG)-positron emission tomography (PET)-based brain activities and normalized cognitive and memory deficits in the APP/PS1 mice. Conclusions Our findings suggest that MEE may benefit AD pathology via modulating LRP1 expression, potentially reducing neuroinflammation and attenuating Aβ deposition. Our study implies that reduced astrocyte derived ApoE and LDL cholesterol levels are critical for attenuating AD pathology.

Abstract Mitochondria respond to metabolic demands of the cell and to incremental damage, in part, through dynamic structural changes that include fission (fragmentation), fusion (merging of distinct mitochondria), autophagic degradation (mitophagy), and biogenic interactions with the endoplasmic reticulum (ER). High resolution study of mitochondrial structural and functional relationships requires rapid preservation of specimens to reduce technical artifacts coupled with quantitative assessment of mitochondrial architecture. A practical approach for assessing mitochondrial fine structure using two dimensional and three dimensional high‐resolution electron microscopy is presented, and a systematic approach to measure mitochondrial architecture, including volume, length, hyperbranching, cristae morphology, and the number and extent of interaction with the ER is described. These methods are used to assess mitochondrial architecture in cells and tissue with high energy demand, including skeletal muscle cells, mouse brain tissue, and Drosophila muscles. The accuracy of assessment is validated in cells and tissue with deletion of genes involved in mitochondrial dynamics.

Alzheimer’s disease (AD) has no cure. Earlier, we showed that partial inhibition of mitochondrial complex I (MCI) with the small molecule CP2 induces an adaptive stress response, activating multiple neuroprotective mechanisms. Chronic treatment reduced inflammation, Aβ and pTau accumulation, improved synaptic and mitochondrial functions, and blocked neurodegeneration in symptomatic APP/PS1 mice, a translational model of AD. Here, using serial block-face scanning electron microscopy (SBFSEM) and three-dimensional (3D) EM reconstructions combined with Western blot analysis and next-generation RNA sequencing, we demonstrate that CP2 treatment also restores mitochondrial morphology and mitochondria-endoplasmic reticulum (ER) communication, reducing ER and unfolded protein response (UPR) stress in the APP/PS1 mouse brain. Using 3D EM volume reconstructions, we show that in the hippocampus of APP/PS1 mice, dendritic mitochondria primarily exist as mitochondria-on-a-string (MOAS). Compared to other morphological phenotypes, MOAS have extensive interaction with the ER membranes, forming multiple mitochondria-ER contact sites (MERCS) known to facilitate abnormal lipid and calcium homeostasis, accumulation of Aβ and pTau, abnormal mitochondrial dynamics, and apoptosis. CP2 treatment reduced MOAS formation, consistent with improved energy homeostasis in the brain, with concomitant reductions in MERCS, ER/UPR stress, and improved lipid homeostasis. These data provide novel information on the MOAS-ER interaction in AD and additional support for the further development of partial MCI inhibitors as a disease-modifying strategy for AD.

AbstractBackgroundConsistent failure of clinical trials for Alzheimer Disease (AD) emphasizes the necessity to identify novel therapeutic targets for this debilitating condition. We recently identified the mitochondrial complex I (MCI) as a small molecule druggable therapeutic target for AD.MethodUsing rational design and extensive structure‐activity relationship studies, we developed novel classes of partial MCI inhibitors with high selectivity, specificity, safety, and drug‐like properties. Target engagement, selectivity and specificity of new compounds were established using multiple in vitro assays, including surface plasmon resonance (SPR), competitive and direct binding, proteomics and pull down experiments. Using these techniques, we developed new lead compound C458 that was interrogated in in vivo efficacy studies in APP/PS1 mice.ResultWe demonstrated that the new lead C458 directly binds to MCI. A single dose administration of C458 to mice or treatment of primary mouse neurons activates AMPK‐a, Akt, autophagy, Sirtuins 1 and 3, and upregulates PGC‐1a leading to enhanced mitochondrial biogenesis. C458 has excellent oral bioavailability, blood–brain‐barrier penetrance, and was remarkably clean in the 250 kinase and CEREP 44 safety panels. Chronic administration of C458 (25 mg/kg/day in drinking water ad lib) to APP/PS1 mice for 6 months starting at pre‐symptomatic stage did not cause detectable side effects, and resulted in cognitive protection, improved long‐term potentiation, and decreased oxidative stress and inflammation. Furthermore, APP/PS1 mice treated with C458 showed a significant increase in glucose uptake and utilization in the brain detected with a translational in vivo biomarker FDG‐PET, as well as an enhancement of ATP production measured in vivo using 31P NMR.ConclusionMechanistic studies confirmed that C458 treatment triggered mitochondrial stress response augmenting mitochondrial biogenesis, anti‐oxidant signaling, and cellular energetics that ultimately restored energy brain homeostasis, leading to cognitive protection in a mouse model of AD. Our studies demonstrate that modulation of MCI activity using novel specific MCI inhibitors improves bioenergetics in the brain and averts cognitive decline representing novel therapeutic approach for AD.

AbstractBackgroundNeurons and astrocytes were differentiated separately from human induced pluripotent stem cells (HiPSC) derived from Late‐Onset Alzheimer Disease (LOAD) female patients carrying Apolipoprotein E4 (ApoE4) allele. Cells from age and sex matched healthy subject carrying Apolipoprotein E3 allele were used as control. These neuronal, astrocytic, and their co‐cultures were assessed to investigate cell‐specific AD phenotypes (Figure 1). We recently demonstrated that application of a small molecule partial mitochondrial complex I inhibitor CP2 blocked neurodegeneration and cognitive decline in multiple mouse models of AD. However, the demonstration that this novel therapeutic approach is efficacious in human brain cells has not been done. Here, we aimed to validate neuroprotective mechanisms induced by CP2 using patient‐derived neuronal cells form LOAD patient. Outcomes will further support the development of these compounds for clinical application.MethodAxonal trafficking of MitoTracker Red stained mitochondria in neuron‐astrocyte co‐cultures was captured using live confocal imaging. The Seahorse XFe96 flux analyzer was used to evaluate mitochondrial bioenergetics in co‐cultures and pure neuronal or astrocytic cultures. Cell Viability Assays were used to perform H2O2 challenge. Quantitative polymerase chain reaction (qPCR), immunohistochemistry, and western blot were carried out to assess alterations in the expression of relevant genes and protein products.ResultWe have found that LOAD cells have a significant reduction in the percentage of motile mitochondria in axons, increased accumulation of neuronal phosphorylated Tau, and altered bioenergetics in neurons and astrocytes compared to the control cells. qPCR revealed elevated expression of inflammation related genes in LOAD co‐cultures. CP2 treatment at concentrations found therapeutically relevant in vivo in APP/PS1 and 3xTgAD mice improved cellular bioenergetics, rescued mitochondrial motility, and provided neuroprotection against H2O2 induced oxidative stress.ConclusionLOAD HiPSC‐derived neuronal co‐cultures and individual brain cells recapitulate mechanisms associated with LOAD allowing validation of a novel mitochondria‐targeted therapeutics. Our results support previous observation in AD mice and the hypothesis that partial inhibition of mitochondrial complex I activates neuroprotective compensatory mechanisms improving cellular energetics in LOAD human neurons even in the presence of mitochondria with abnormal dynamics and energetics. Further efforts are focused on the determination of a cell‐specific mechanisms of neuroprotection.

Key Points In heme protein–induced AKI, mitochondrial functional integrity, as reflected by ATP and NAD + content and NAD + /NADH ratio, is impaired. Mitochondrial quality control is compromised as reflected by impaired biogenesis, exaggerated fission, and marked ultrastructural damage. Modern concepts regarding mitochondria and AKI apply to heme protein–induced AKI, with the possibility of novel therapeutic strategies. Background Mitochondrial injury occurs in and underlies acute kidney injury (AKI) caused by ischemia-reperfusion and other forms of renal injury. However, to date, a comprehensive analysis of this issue has not been undertaken in heme protein–induced AKI (HP-AKI). We examined key aspects of mitochondrial function, expression of proteins relevant to mitochondrial quality control, and mitochondrial ultrastructure in HP-AKI, along with responses to heme in renal proximal tubule epithelial cells. Methods The long-established murine glycerol model of HP-AKI was examined at 8 and 24 hours after HP-AKI. Indices of mitochondrial function (ATP and NAD + ), expression of proteins relevant to mitochondrial dynamics, mitochondrial ultrastructure, and relevant gene/protein expression in heme-exposed renal proximal tubule epithelial cells in vitro were examined. Results ATP and NAD + content and the NAD + /NADH ratio were all reduced in HP-AKI. Expression of relevant proteins indicate that mitochondrial biogenesis (PGC-1 α , NRF1, and TFAM) and fusion (MFN2) were impaired, as was expression of key proteins involved in the integrity of outer and inner mitochondrial membranes (VDAC, Tom20, and Tim23). Conversely, marked upregulation of proteins involved in mitochondrial fission (DRP1) occurred. Ultrastructural studies, including novel 3D imaging, indicate profound changes in mitochondrial structure, including mitochondrial fragmentation, mitochondrial swelling, and misshapen mitochondrial cristae; mitophagy was also observed. Exposure of renal proximal tubule epithelial cells to heme in vitro recapitulated suppression of PGC-1 α (mitochondrial biogenesis) and upregulation of p-DRP1 (mitochondrial fission). Conclusions Modern concepts pertaining to AKI apply to HP-AKI. This study validates the investigation of novel, clinically relevant therapies such as NAD + -boosting agents and mitoprotective agents in HP-AKI.

Abstract Introduction Late‐onset Alzheimer's disease (LOAD) is a complex neurodegenerative disease characterized by multiple progressive stages, glucose metabolic dysregulation, Alzheimer's disease (AD) pathology, and inexorable cognitive decline. Discovery of metabolic profiles unique to sex, apolipoprotein E ( APOE ) genotype, and stage of disease progression could provide critical insights for personalized LOAD medicine. Methods Sex‐ and APOE ‐specific metabolic networks were constructed based on changes in 127 metabolites of 656 serum samples from the Alzheimer's Disease Neuroimaging Initiative cohort. Results Application of an advanced analytical platform identified metabolic drivers and signatures clustered with sex and/or APOE ɛ4, establishing patient‐specific biomarkers predictive of disease state that significantly associated with cognitive function. Presence of the APOE ɛ4 shifts metabolic signatures to a phosphatidylcholine‐focused profile overriding sex‐specific differences in serum metabolites of AD patients. Discussion These findings provide an initial but critical step in developing a diagnostic platform for personalized medicine by integrating metabolomic profiling and cognitive assessments to identify targeted precision therapeutics for AD patient subgroups through computational network modeling.

Alzheimer’s disease (AD) is an incurable neurodegenerative disorder and the leading cause of death among older individuals. Available treatment strategies only temporarily mitigate symptoms without modifying disease progression. Recent studies revealed the multifaceted neurobiology of AD and shifted the target of drug development. Established animal models of AD are mostly tailored to yield a subset of disease phenotypes, which do not recapitulate the complexity of sporadic late-onset AD, the most common form of the disease. The use of human induced pluripotent stem cells (HiPSCs) offers unique opportunities to fill these gaps. Emerging technology allows the development of disease models that recapitulate a brain-like microenvironment using patient-derived cells. These models retain the individual’s unraveled genetic background, yielding clinically relevant disease phenotypes and enabling cost-effective, high-throughput studies for drug discovery. Here, we review the development of various HiPSC-based models to study AD mechanisms and their application in drug discovery.

AbstractBackgroundAlzheimer’s disease (AD) is a devastating neuropathological condition where age is the greatest risk factor. There is currently an estimated global prevalence upward of 46.8 million individuals and recent efforts to combat the clinical presentation of AD through late‐stage Amyloid‐beta (Aβ) targeted therapeutic intervention has not been successful, underscoring the need for novel approaches to slow disease progression. Accumulating evidence proposes that mitochondrial and metabolic homoeostasis is an early dysfunction which occurs decades before the presentation of clinical symptoms. Indeed AD has been classified as type‐3 diabetes, suggesting the need to target metabolic modifiers to slow or even abrogate neurodegeneration. We have recently reported that targeting the oxidative phosphorylation (OXPHOS) system through mild inhibition of NADH dehydrogenase (Complex I) with our small molecules partial Complex I inhibitors (MCIi) can halt the development of cognitive and behavioral phenotypes associated with AD. We have also demonstrated that this modulation of mitochondrial complex I, through reversible inhibition at the Flavin Mononucleotide (FMN) domain, serves to enhance mitochondrial bioenergetics and function and protects against oxidative stress. We hypothesize that this mechanism of improved bioenergetics may be due to transformed OXPHOS super‐complex assembly, which can lead to a more efficient bioenergetics system and protect against extrinsic stress.MethodsTo test this hypothesis, we examined bioenergetics and the assembly of mitochondrial OXPHOS complexes and super‐complexes in mitochondria from primary cortical neurons and synaptosomes isolated from the brain tissue of non‐transgenic and 3xTgAD mice treated with MCli using respiratory XF Seahorse analysis, BNPAGE and 2D‐BNPAGE.ResultsOur analyses demonstrates that MCIi can acutely alter the assembly of super‐complexes within the OXPHOS system and protect against stress through enhanced spare respiratory capacity while preserving ATP level, which may aid in the enhancement of mitochondrial bioenergetics and function in AD.ConclusionPartial complex I inhibitors can induce positive bioenergetics through super‐complex assembly