Senescence Markers in Peripheral Blood Mononuclear Cells in Amnestic Mild Cognitive Impairment and Alzheimer's Disease.

Recent studies suggest that cellular senescence plays a role in Alzheimer's Disease (AD) pathogenesis. We hypothesize that cellular senescence markers might be tracked in the peripheral tissues of AD patients. Senescence hallmarks, including altered metabolism, cell-cycle arrest, DNA damage response (DDR) and senescence secretory associated phenotype (SASP), were measured in peripheral blood mononuclear cells (PBMCs) of healthy controls (HC), amnestic mild cognitive impairment (aMCI) and AD patients. Senescence-associated ßeta-galactosidase (SA-ß-Gal) activity, G0-G1 phase cell-cycle arrest, p16 and p53 were analyzed by flow cytometry, while IL-6 and IL-8 mRNA were analyzed by qPCR, and phosphorylated H2A histone family member X (γH2AX) was analyzed by immunofluorescence. Senescent cells in the brain tissue were determined with lipofuscin staining. An increase in the number of senescent cells was observed in the frontal cortex and hippocampus of advanced AD patients. PBMCs of aMCI patients, but not in AD, showed increased SA-ß-Gal compared with HCs. aMCI PBMCs also had increased IL-6 and IL8 mRNA expression and number of cells arrested at G0-G1, which were absent in AD. Instead, AD PBMCs had significantly increased p16 and p53 expression and decreased γH2Ax activity compared with HC. This study reports that several markers of cellular senescence can be measured in PBMCs of aMCI and AD patients.

Consolidated framework for advancing implementation science for the implementation process and adherence assessment of a non-pharmacological delirium prevention program.

OBJECTIVE: To evaluate the contribution of applying the theoretical framework of implementation science for adherence to non-pharmacological interventions to prevent delirium. METHODS: A quasi-experimental prospective design was conducted from March 2017 to October 2018 in a teaching hospital. Participants included 149 healthcare staff and 72 elderly inpatients. A non-pharmacological delirium prevention program was designed, applied and evaluated in accordance with the consolidated framework for advancing implementation research (CFIR). The primary outcome was the global adherence rate to 12 predefined indicators, comparing measurements at baseline (O1), after training (O2) and at a 6-month follow-up (O3) assessed by an external reviewer. Staff knowledge and beliefs about delirium were assessed using a validated tool, and delirium incidence was evaluated using the confusion assessment method. RESULTS: Overall adherence increased from 58.2% (O1) to 77.9% (O2) and 75.6% (O3) (O2 vs. O1: p < 0.001 and O3 vs. O1: p < 0.001). Staff perceptions regarding implementation of non-pharmacological interventions increased from 74.8% to 81.9% (p = 0.004). Delirium incidence was non-significantly reduced from 20% (O1) to 16% (O3) (p = 0.99). CONCLUSIONS: Implementation of a delirium prevention program using a CFIR model was useful in improving adherence to activities included in this program, as well as improving the knowledge and beliefs regarding delirium by healthcare workers. The impact of this implementation strategy on the incidence of delirium should be evaluated in a larger scale multicenter trial.

Analyzing Olfactory Neuron Precursors Non-Invasively Isolated through NADH FLIM as a Potential Tool to Study Oxidative Stress in Alzheimer's Disease.

Among all the proposed pathogenic mechanisms to understand the etiology of Alzheimer's disease (AD), increased oxidative stress seems to be a robust and early disease feature where many of those hypotheses converge. However, despite the significant lines of evidence accumulated, an effective diagnosis and treatment of AD are not yet available. This limitation might be partially explained by the use of cellular and animal models that recapitulate partial aspects of the disease and do not account for the particular biology of patients. As such, cultures of patient-derived cells of peripheral origin may provide a convenient solution for this problem. Peripheral cells of neuronal lineage such as olfactory neuronal precursors (ONPs) can be easily cultured through non-invasive isolation, reproducing AD-related oxidative stress. Interestingly, the autofluorescence of key metabolic cofactors such as reduced nicotinamide adenine dinucleotide (NADH) can be highly correlated with the oxidative state and antioxidant capacity of cells in a non-destructive and label-free manner. In particular, imaging NADH through fluorescence lifetime imaging microscopy (FLIM) has greatly improved the sensitivity in detecting oxidative shifts with minimal intervention to cell physiology. Here, we discuss the translational potential of analyzing patient-derived ONPs non-invasively isolated through NADH FLIM to reveal AD-related oxidative stress. We believe this approach may potentially accelerate the discovery of effective antioxidant therapies and contribute to early diagnosis and personalized monitoring of this devastating disease.

A software to prevent delirium in hospitalised older adults: development and feasibility assessment.

BACKGROUND: non-pharmacological interventions to prevent delirium are useful in hospitalised older adults. However, they are poorly implemented in clinical practice. We aimed to develop a software for bedside use by hospitalised older adults and to improve their access to these interventions. METHODS: a transdisciplinary team composed of healthcare professionals, designers, engineers and older adults participated in the development of the software. Scrum methodology was used to coordinate the work of the team, and the software was evaluated in a feasibility study. RESULTS: a software for touchscreen mobile devices that supports Android 5.0 or later was produced, including modules for time-spatial re-orientation, cognitive stimulation, early mobilisation, sensorial support use promotion, sleep hygiene and pain management optimisation. Horizontal disposition, use of colour contrast and large interaction areas were used to improve accessibility. The software's usability and accessibility were evaluated in 34 older adults (average age 73.2 ± 9.1 years) showing that 91.1% of them got access to all the software functions without previous instructions. The clinical feasibility assessment showed that 83.3% of the 30 enrolled hospitalised patients (76 ± 8 years) completed the 5-day protocol of software usage during hospitalisation. Software use was associated with a decreased trend in delirium incidence of 5 of 32 (15.6%) at baseline to 2 of 30 (6.6%) after its implementation. CONCLUSION: a highly accessible and implementable software, designed to improve access to non-pharmacological interventions to prevent delirium in hospitalised older adults, was developed. The effectiveness of the software will be evaluated in a randomised clinical trial.

Visual-spatial processing impairment in the occipital-frontal connectivity network at early stages of Alzheimer's disease.

Introduction: Alzheimer's disease (AD) is the leading cause of dementia worldwide, but its pathophysiological phenomena are not fully elucidated. Many neurophysiological markers have been suggested to identify early cognitive impairments of AD. However, the diagnosis of this disease remains a challenge for specialists. In the present cross-sectional study, our objective was to evaluate the manifestations and mechanisms underlying visual-spatial deficits at the early stages of AD. Methods: We combined behavioral, electroencephalography (EEG), and eye movement recordings during the performance of a spatial navigation task (a virtual version of the Morris Water Maze adapted to humans). Participants (69-88 years old) with amnesic mild cognitive impairment-Clinical Dementia Rating scale (aMCI-CDR 0.5) were selected as probable early AD (eAD) by a neurologist specialized in dementia. All patients included in this study were evaluated at the CDR 0.5 stage but progressed to probable AD during clinical follow-up. An equal number of matching healthy controls (HCs) were evaluated while performing the navigation task. Data were collected at the Department of Neurology of the Clinical Hospital of the Universidad de Chile and the Department of Neuroscience of the Faculty of Universidad de Chile. Results: Participants with aMCI preceding AD (eAD) showed impaired spatial learning and their visual exploration differed from the control group. eAD group did not clearly prefer regions of interest that could guide solving the task, while controls did. The eAD group showed decreased visual occipital evoked potentials associated with eye fixations, recorded at occipital electrodes. They also showed an alteration of the spatial spread of activity to parietal and frontal regions at the end of the task. The control group presented marked occipital activity in the beta band (15-20 Hz) at early visual processing time. The eAD group showed a reduction in beta band functional connectivity in the prefrontal cortices reflecting poor planning of navigation strategies. Discussion: We found that EEG signals combined with visual-spatial navigation analysis, yielded early and specific features that may underlie the basis for understanding the loss of functional connectivity in AD. Still, our results are clinically promising for early diagnosis required to improve quality of life and decrease healthcare costs.

Non-pharmacological prevention of postoperative delirium by occupational therapy teams: A randomized clinical trial.

Background: Patients who develop postoperative delirium (POD) have several clinical complications, such as increased morbidity, increased hospital stays, higher hospital costs, cognitive and functional impairment, and higher mortality. POD is a clinical condition preventable by standard non-pharmacological measures An intensive Occupational Therapy (OT) intervention has been shown to be highly effective in preventing delirium in critically ill medical patients, but it is unknown the effect in surgical patients. Thus, we designed a prospective clinical study with the aim to determine whether patients undergoing intervention by the OT team have a lower incidence of POD compared to the group treated only with standard measures. Methods: A multicenter, single-blind, randomized clinical trial was conducted between October 2018 and April 2021, in Santiago of Chile, at a university hospital and at a public hospital. Patients older than 75 years undergoing elective major surgery were eligible for the trial inclusion. Patients with cognitive impairment, severe communication disorder and cultural language limitation, delirium at admission or before surgery, and enrolled in another study were excluded. The intervention consisted of OT therapy twice a day plus standard internationally recommended non-pharmacological prevention intervention during 5 days after surgery. Our primary outcome was development of delirium and postoperative subsyndromal delirium. Results: In total 160 patients were studied. In the interventional group, treated with an intensive prevention by OT, nine patients (12.9%) developed delirium after surgery and in the control group four patients (5.5%) [p = 0.125, RR 2.34 CI 95 (0.75-7.27)]. Whereas subsyndromal POD was present in 38 patients in the control group (52.1%) and in 34 (48.6%) in the intervention group [p = 0.4, RR 0.93 CI95 (0.67-1.29)]. A post hoc analysis determined that the patient's comorbidity and cognitive status prior to hospitalization were the main risk factors to develop delirium after surgery. Discussion: Patients undergoing intervention by the OT team did not have a lower incidence of POD compared to the group treated only with standard non-pharmacological measures in adults older than 75 years who went for major surgery. Clinical trial registration: www.ClinicalTrials.gov, identifier NCT03704090.

The autophagy protein Def8 is altered in Alzheimer's disease and Aß42-expressing Drosophila brains.

Alzheimer's disease (AD) is the most common neurodegenerative disorder, characterized by protein accumulation in the brain as a main neuropathological hallmark. Among them, Aß42 peptides tend to aggregate and create oligomers and plaques. Macroautophagy, a form of autophagy characterized by a double-membrane vesicle, plays a crucial role in maintaining neuronal homeostasis by degrading protein aggregates and dysfunctional organelles as a quality control process. Recently, DEF8, a relatively uncharacterized protein, has been proposed as a participant in vesicular traffic and autophagy pathways. We have reported increased DEF8 levels in lymphocytes from mild cognitive impairment (MCI) and early-stage AD patients and a neuronal profile in a murine transgenic AD model. Here, we analyzed DEF8 localization and levels in the postmortem frontal cortex of AD patients, finding increased levels compared to healthy controls. To evaluate the potential function of DEF8 in the nervous system, we performed an in silico assessment of its expression and network profiles, followed by an in vivo evaluation of a neuronal Def8 deficient model using a Drosophila melanogaster model of AD based on Aß42 expression. Our findings show that DEF8 is an essential protein for maintaining cellular homeostasis in the nervous system, and it is upregulated under stress conditions generated by Aß42 aggregation. This study suggests DEF8 as a novel actor in the physiopathology of AD, and its exploration may lead to new treatment avenues.

Cancer History Is Associated with Slower Speed of Cognitive Decline in Patients with Amnestic Cognitive Impairment.

BACKGROUND: Several epidemiological studies report a negative association between Cancer and Alzheimer's disease (AD). OBJECTIVE: To characterize the trajectories of memory loss in individuals with early amnestic cognitive impairment with and without history of previous cancer. METHODS: Cognitive deterioration was assessed using the Montreal Cognitive Assessment (MoCA) or MoCA-Memory Index Score (MoCA-MIS) biannually in subjects with early amnestic cognitive impairment followed-up retrospectively from 2007 to 2021. History of Cancer was obtained from clinical records. Simple linear regressions of MoCA-MIS scores were calculated for each subject and analyzed with K-means cluster analysis to identify subgroups with different cognitive decline trajectories. χ2 and t tests were used for descriptive categorical and continuous variables and mixed multiple linear regressions to determine cognitive decline covariates. RESULTS: Analysis of the trajectory of cognitive decline in 141 subjects with early amnestic cognitive impairment identified two subgroups: Fast (n = 60) and Slow (n = 81) progressors. At baseline Fast progressors had better MoCA-MIS (p < 0.001) and functionality (CDR p = 0.02, AD8 p = 0.05), took less anti-dementia medications (p = 0.005), and had higher depression rates (p = 0.02). Interestingly, Fast progressors slowed their speed of memory decline (from 1.6 to 1.1 MoCA-MIS points/year) and global cognitive decline (from 2.0 to 1.4 total MoCA points/year) when Cancer history was present. CONCLUSION: Two trajectories of amnestic cognitive decline were identified, possibly derived from different neurophysiopathologies or clinical stages. This study suggests that a history of previous Cancer slows down amnestic cognitive decline, specifically in a subgroup of subjects with depression at baseline and accelerated deterioration at follow-up.

Neuronal Rubicon Represses Extracellular APP/Amyloid ß Deposition in Alzheimer's Disease.

Alzheimer's disease (AD) is the most prevalent age-associated neurodegenerative disease. A decrease in autophagy during aging contributes to brain disorders by accumulating potentially toxic substrates in neurons. Rubicon is a well-established inhibitor of autophagy in all cells. However, Rubicon participates in different pathways depending on cell type, and little information is currently available on neuronal Rubicon's role in the AD context. Here, we investigated the cell-specific expression of Rubicon in postmortem brain samples from AD patients and 5xFAD mice and its impact on amyloid ß burden in vivo and neuroblastoma cells. Further, we assessed Rubicon levels in human-induced pluripotent stem cells (hiPSCs), derived from early-to-moderate AD and in postmortem samples from severe AD patients. We found increased Rubicon levels in AD-hiPSCs and postmortem samples and a notable Rubicon localization in neurons. In AD transgenic mice lacking Rubicon, we observed intensified amyloid ß burden in the hippocampus and decreased Pacer and p62 levels. In APP-expressing neuroblastoma cells, increased APP/amyloid ß secretion in the medium was found when Rubicon was absent, which was not observed in cells depleted of Atg5, essential for autophagy, or Rab27a, required for exosome secretion. Our results propose an uncharacterized role of Rubicon on APP/amyloid ß homeostasis, in which neuronal Rubicon is a repressor of APP/amyloid ß secretion, defining a new way to target AD and other similar diseases therapeutically.

Phosphorylation of AKT/PKB by CK2 is necessary for the AKT-dependent up-regulation of ß-catenin transcriptional activity.

ß-Catenin is a key protein in the canonical Wnt signaling pathway and in many cancers alterations in transcriptional activity of its components are observed. This pathway is up-regulated by the protein kinase CK2, but the underlying mechanism of this change is unknown. It has been demonstrated that CK2 hyperactivates AKT/PKB by phosphorylation at Ser129, and AKT phosphorylates ß-catenin at Ser552, which in turn, promotes its nuclear localization and transcriptional activity. However, the consequences of CK2-dependent hyperactivation of AKT on ß-catenin activity and cell viability have not been evaluated. We assessed this regulatory process by manipulating the activity of CK2 and AKT through overexpression of wild-type, constitutively active and dominant negative forms of these proteins as well as analyzing ß-catenin-dependent transcriptional activity, survivin expression and viability in HEK-293T cells. We observed that CK2α overexpression up-regulated the ß-catenin transcriptional activity, which correlated to an increased nuclear localization of ß-catenin as well as survivin expression. Importantly, these effects were strongly reversed when an AKT-S129A mutant was co-expressed in the same cells, followed by a significant decrease in cell viability but no changes in ß-catenin stability. Taken together, the data suggest that the CK2α-dependent up-regulation of ß-catenin activity requires phosphorylation of AKT in human embryonic kidney cells.

Protein kinase CK2 promotes cancer cell viability via up-regulation of cyclooxygenase-2 expression and enhanced prostaglandin E2 production.

Augmented expression of protein kinase CK2 is associated with hyperproliferation and resistance to apoptosis in cancer cells. Effects of CK2 are at least partially linked to signaling via the Wnt/ß-catenin pathway, which is dramatically enhanced in colon cancer. Cyclooxygenase-2 (COX-2), a Wnt/ß-catenin target gene, has been associated with enhanced cancer progression and metastasis. However, the possibility that a connection may exist between CK2 and COX-2 has not been explored previously. Here we investigated changes in COX-2 expression and activity upon CK2 modulation and evaluated how these changes affected cell viability. COX-2 expression and cell viability decreased upon selective inhibition of COX-2 with SC-791 or CK2 with 2-dimethylamino-4,5,6,7-tetrabromo-1H-benzimidazole (DMAT), both in human colon (HT29-ATCC, HT29-US, DLD-1) and breast (ZR-75) cancer cells, as well as in human embryonic kidney (HEK-293T) cells. On the other hand, ectopic CK2α expression promoted up-regulation of COX-2 by activating the Wnt/ß-catenin pathway in HEK-293T cells. Noteworthy, over-expression of either CK2α, ß-catenin or COX-2, as well as supplementation of the medium with prostaglandin E2 (PGE2), all were individually sufficient to overcome limitations in cell viability triggered by CK2 inhibition either upon addition of DMAT or over-expression of a dominant negative CK2α variant. Altogether, these findings provide new insight to the role of CK2 in cancer by up-regulating COX-2 expression and thereby PGE2 production.

CK2 functionally interacts with AKT/PKB to promote the ß-catenin-dependent expression of survivin and enhance cell survival.

ß-Catenin is crucial in the canonical Wnt signaling pathway. This pathway is up-regulated by CK2 which is associated with an enhanced expression of the antiapoptotic protein survivin, although the underlying molecular mechanism is unknown. AKT/PKB kinase phosphorylates and promotes ß-catenin transcriptional activity, whereas CK2 hyperactivates AKT by phosphorylation at Ser129; however, the role of this phosphorylation on ß-catenin transcriptional activity and cell survival is unclear. We studied in HEK-293T cells, the effect of CK2-dependent hyperactivation of AKT on cell viability, as well as analyzed ß-catenin subcellular localization and transcriptional activity and survivin expression. CK2α overexpression led to an augmented ß-catenin-dependent transcription and protein levels of survivin, and consequently an enhanced resistance to apoptosis. However, CK2α-enhancing effects were reversed when an AKT mutant deficient in Ser129 phosphorylation by CK2 was co-expressed. Therefore, our results strongly suggest that CK2α-specific enhancement of ß-catenin transcriptional activity as well as cell survival may depend on AKT hyperactivation by CK2.

Nicotinamide, a Poly [ADP-Ribose] Polymerase 1 (PARP-1) Inhibitor, as an Adjunctive Therapy for the Treatment of Alzheimer's Disease.

Nicotinamide (vitamin B3) is a key component in the cellular production of Nicotinamide Adenine Dinucleotide (NAD) and has long been associated with neuronal development, survival and death. Numerous data suggest that nicotinamide may offer therapeutic benefits in neurodegenerative disorders, including Alzheimer's Disease (AD). Beyond its effect in NAD+ stores, nicotinamide is an inhibitor of Poly [ADP-ribose] polymerase 1 (PARP-1), an enzyme with multiple cellular functions, including regulation of cell death, energy/metabolism and inflammatory response. PARP-1 functions as a DNA repair enzyme but under intense DNA damage depletes the cell of NAD+ and ATP and leads to a non-apoptotic type of cell death called Parthanatos, which has been associated with the pathogenesis of neurodegenerative diseases. Moreover, NAD+ availability might potentially improve mitochondrial function, which is severely impaired in AD. PARP-1 inhibition may also exert a protective effect against neurodegeneration by its action to diminish neuroinflammation and microglial activation which are also implicated in the pathogenesis of AD. Here we discuss the evidence supporting the use of nicotinamide as adjunctive therapy for the treatment of early stages of AD based on the inhibitory effect of nicotinamide on PARP-1 activity. The data support evaluating nicotinamide as an adjunctive treatment for AD at early stages of the disease not only to increase NAD+ stores but as a PARP-1 inhibitor, raising the hypothesis that other PARP-1 inhibitors - drugs that are already approved for breast cancer treatment - might be explored for the treatment of AD.

Inverse Relationship Between Alzheimer's Disease and Cancer: How Immune Checkpoints Might Explain the Mechanisms Underlying Age-Related Diseases.

Alzheimer's disease (AD) is the most prevalent neurodegenerative disease in the adult population. There is evidence of an inverse epidemiological relationship between AD and cancer, another prevalent age-related disease. This has led to hypothesize that there could be a common biological mechanism, deregulated in opposite directions that might explain the phenomenon of mutual protection. The immunological system and its regulatory checkpoints are good candidates to explain why having survived a cancer could protect from developing AD. During cancerous growth, the neoplastic cells induce immune tolerance to block the host's immunity system that would prevent tumor growth. This has led to the development of drugs that block distinct immune checkpoints, such as Programmed Death 1 (PD-1) and its major ligand PD-L1, that have shown great promise in treating diverse types of cancer. We propose that in those individuals who survived a cancer, the immune system is left in a state of diminished tolerance or proinflammatory systemic milieu, after its successful attempt to fight the cancer, that protects them from developing AD.

Local Klotho Enhances Neuronal Progenitor Proliferation in the Adult Hippocampus.

Klotho is an aging-related protein associated with hippocampal cognitive performance in mammals. Klotho regulates progenitor cell proliferation in non-neuronal tissues, but its role in adult hippocampal neurogenesis (AHN) has not been explored. Klotho expression in the adult mouse hippocampus was examined by immunofluorescence and polymerase chain reaction. AHN was evaluated in the hippocampus of klotho knock-out mice (KO), klotho KO/vitamin D-receptor mutant mice, and in a model of local klotho hippocampal knockdown. The recombinant Klotho effect on proliferation was measured in mouse-derived hippocampal neural progenitor cells. Hippocampal-dependent memory was assessed by a dry-land version of the Morris water maze. Klotho was expressed in the granular cell layer of the adult Dentate Gyrus. AHN was increased in klotho KO mice, but not in klotho KO/vitamin D-receptor mutant mice. Inversely, local downregulation of hippocampal Klotho diminished AHN. Recombinant Klotho increased the proliferation rate of neural progenitors. Downregulation of hippocampal Klotho correlated with a decreased performance in hippocampal-dependent memory. These results suggest that Klotho directly participates in regulating AHN. Our observations indicate that Klotho promotes proliferation, AHN and hippocampal-dependent cognition. Increased neurogenesis in klotho KO mice may be secondary to the activation of other pathways altered in the model, such as vitamin D.

Vitamin D Increases Aß140 Plasma Levels and Protects Lymphocytes from Oxidative Death in Mild Cognitive Impairment Patients.

BACKGROUND: Mild cognitive impairment (MCI) has an increased rate of progression to dementia. Alterations of some metabolic factors, such as deficiency of vitamin D, are a risk factor for cognitive deterioration. Vitamin D is involved in the clearance of ß-amyloid (Aß) from the brain. We have reported that lymphocytes from Alzheimer's disease (AD) patients have an increased susceptibility to oxidative death by H2O2 exposure, but currently it is unknown if this characteristic is modifiable in vivo. OBJECTIVE: To determine if correction of low vitamin D levels protects lymphocytes from oxidative death and increases Aß1-40 plasma levels in MCI and very early AD (VEAD) patients. METHOD: Sixteen MCI, 11 VEAD and 25 healthy control (HC) voluntaries were evaluated with the Clinical Dementia Rating (CDR), Montreal Cognitive assessment (MoCA), and Memory Index score (MIS). Lymphocyte death was measured by flow cytometry after 20h exposure to H2O2. In patients with low levels of vitamin D -11 MCI, 9 VEAD and 20 HC- lymphocyte H2O2-death, plasma Aß1-40 levels and cognitive status were evaluated pre- and post-vitamin D supplementation for 6 months. RESULTS: Lymphocytes from MCI and VEAD patients showed increased susceptibility to oxidative death at study entry. In MCI, but not VEAD patients, lymphocyte susceptibility to death and Aß1-40 levels plasma levels improved after 6 months of vitamin D supplementation. In addition, cognitive status on follow-up (18 months) improved in MCI patients after vitamin D supplementation. CONCLUSION: Vitamin D supplementation may be beneficial in MCI. The lack of effect in VEAD may be due to a more advanced stage or different characteristics of the neurodegenerative process.

Mitochondrial permeability transition pore contributes to mitochondrial dysfunction in fibroblasts of patients with sporadic Alzheimer's disease.

In the last few decades, many reports have suggested that mitochondrial function impairment is a hallmark of Alzheimer's disease (AD). Although AD is a neurodegenerative disorder, mitochondrial damage is also present in patients' peripheral tissues, suggesting a target to develop new biomarkers. Our previous findings indicate that AD fibroblasts show specific defects in mitochondrial dynamics and bioenergetics, which affects the generation of adenosine triphosphate (ATP). Therefore, we explored the possible mechanisms involved in this mitochondrial failure. We found that compared with normal fibroblasts, AD fibroblasts had mitochondrial calcium dysregulation. Further, AD fibroblasts showed a persistent activation of the non-specific mitochondrial calcium channel, the mitochondrial permeability transition pore (mPTP). Moreover, the pharmacological blockage of mPTP with Cyclosporine A (CsA) prevented the increase of mitochondrial superoxide levels, and significantly improved mitochondrial and cytosolic calcium dysregulation in AD fibroblasts. Finally, despite the failure of CsA to improve ATP levels, the inhibition of mitochondrial calcium uptake by the mitochondrial calcium uniporter increased ATP production in AD fibroblasts, indicating that these two mechanisms may contribute to mitochondrial failure in AD fibroblasts. These findings suggest that peripheral cells present similar signs of mitochondrial dysfunction observed in the brain of AD patients. Therefore, our work creates possibilities of new targets to study for early diagnosis of the AD.

Cancer Imprints an Increased PARP-1 and p53-Dependent Resistance to Oxidative Stress on Lymphocytes of Patients That Later Develop Alzheimer's Disease.

We have proposed that a common biological mechanism deregulated in opposite directions might explain the inverse epidemiological association observed between Alzheimer's disease (AD) and cancer. Accordingly, we showed that lymphocytes from AD patients have an increased susceptibility, whereas those from survivors of a skin cancer, an increased resistance to oxidative death induced by hydrogen peroxide (H2O2), compared to healthy controls (HC). We investigated the susceptibility to H2O2-induced death of lymphocytes in survivors of any type of cancer and in cancer survivors who later developed AD (Ca&AD). We also explored the involvement of Poly [ADP-ribose] polymerase-1 (PARP-1) and p53 pathways in the process, since both are involved in the increased susceptibility to death of AD lymphocytes. Lymphocytes from 11 cancer and 13 Ca&AD patients, and 12 HC were submitted to increasing concentrations of H2O2 for 20 h. Cell death was determined by flow cytometry, in the presence or absence of PARP-1 inhibition (3-aminobenzamide, 3-ABA), or p53 inhibition (pifithrin-α) or stabilization (Nut-3). PARP-1 and p53 mRNA levels were determined by Real-Time PCR. Lymphocytes from cancer and Ca&AD patients showed increased survival compared to HC, without differences between them, opposite to the increased susceptibility to death previously shown in AD. PARP-1 inhibition provided marked protection from H2O2-induced death in the two groups of patients, significantly greater than in HC. Pharmacological inhibition of p53 increased lymphocyte survival in Ca&AD patients, contrary to the effect previously reported in HC and AD. PARP-1 and p53 mRNA levels were elevated in Ca&AD lymphocytes compared with controls. In all, these results show that cancer imprints an increased resistance to H2O2-induced death in lymphocytes that persists after AD development, and is dependent on both PARP-1 and p53. p53 inhibition showed a differential role in cancer and Ca&AD compared to HC and AD lymphocytes, that could explain the inverse susceptibility to oxidative death in cancer and AD. These results are in agreement with the hypothesis of a common biological mechanism in AD and cancer. The similar cell death susceptibility and cell death pattern observed in cancer and Ca&AD lymphocytes suggests that cancer history leaves long term effects on lymphocyte cell death susceptibility.

Mitochondrial Bioenergetics Is Altered in Fibroblasts from Patients with Sporadic Alzheimer's Disease.

The identification of an early biomarker to diagnose Alzheimer's disease (AD) remains a challenge. Neuropathological studies in animal and AD patients have shown that mitochondrial dysfunction is a hallmark of the development of the disease. Current studies suggest the use of peripheral tissues, like skin fibroblasts as a possibility to detect the early pathological alterations present in the AD brain. In this context, we studied mitochondrial function properties (bioenergetics and morphology) in cultured fibroblasts obtained from AD, aged-match and young healthy patients. We observed that AD fibroblasts presented a significant reduction in mitochondrial length with important changes in the expression of proteins that control mitochondrial fusion. Moreover, AD fibroblasts showed a distinct alteration in proteolytic processing of OPA1, a master regulator of mitochondrial fusion, compared to control fibroblasts. Complementary to these changes AD fibroblasts showed a dysfunctional mitochondrial bioenergetics profile that differentiates these cells from aged-matched and young patient fibroblasts. Our findings suggest that the human skin fibroblasts obtained from AD patients could replicate mitochondrial impairment observed in the AD brain. These promising observations suggest that the analysis of mitochondrial bioenergetics could represent a promising strategy to develop new diagnostic methods in peripheral tissues of AD patients.

PARP-1 and p53 Regulate the Increased Susceptibility to Oxidative Death of Lymphocytes from MCI and AD Patients.

Mild cognitive impairment (MCI) is a clinically detectable initial stage of cognitive deterioration with a high conversion rate to dementia. There is increasing evidence that some of the cerebral alterations present in Alzheimer type dementia can be found in peripheral tissues. We have previously shown that lymphocytes from Alzheimer's disease (AD) patients have increased susceptibility to hydrogen peroxide (H2O2)-induced death that depends on dementia severity. We here investigated whether lymphocytes from MCI patients show increased vulnerability to death, and explored the involvement of Poly [ADP-ribose] polymerase (PARP-1) and p53 in the regulation of this process. Lymphocytes from 16 MCI and 10 AD patients, and 15 healthy controls (HCs) were submitted to increasing concentrations of H2O2 for 20 h. Cell death was determined by flow cytometry, in the presence or absence of PARP-1 inhibitors (3-aminobenzamide (3-ABA) or Nicotinamide (NAM)), or the p53 inhibitor (nutlin-3) or stabilizer (pifithrin-α). PARP-1 and p53 mRNA levels were determined by quantitative PCR (qPCR). Lymphocytes from MCI patients showed increased susceptibility to death, attaining intermediate values between AD and controls. PARP inhibitors -3-ABA and NAM- markedly protected from H2O2-induced death, making the difference between MCI and controls disappear, but not the difference between AD and controls. PARP-1 mRNA expression was increased in MCI lymphocytes. Modulation of p53 with Nutlin-3 or pifithrin-α did not modify the H2O2-induced death of lymphocytes from MCI or AD patients, but augmented the death in control lymphocytes attaining levels similar to MCI and AD. Accordingly, p53 mRNA expression was increased in AD and MCI lymphocytes compared to controls. In all, these results show that increased oxidative death is present in lymphocytes at the MCI stage. PARP-1 has a preponderant role, with complete death protection achieved with PARP inhibition in MCI lymphocytes, but not in AD, suggesting that PARP-1 might have a protective role. In addition, deregulations of the p53 pathway seem to contribute to the H2O2-induced death in MCI and AD lymphocytes, which show increased p53 expression. The results showing a prominent protective role of PARP inhibitors opens the door to study the use of these agents to prevent oxidative death in MCI patients.