Neurodegenerative diseases: insights into pathogenic mechanisms from atherosclerosis

The Brain-Gut Axis, an Important Player in Alzheimer and Parkinson Disease: A Narrative Review

Neurodegenerative diseases, such as Alzheimer's disease (AD) and Parkinson's disease (PD), are severe age-related disorders with complex and multifactorial causes. Recent research suggests a critical link between neurodegeneration and the gut microbiome, via the gut-brain communication pathway. This review examines the role of trimethylamine N-oxide (TMAO), a gut microbiota-derived metabolite, in the development of AD and PD, and investigates its interaction with microRNAs (miRNAs) along this bidirectional pathway. TMAO, which is produced from dietary metabolites like choline and carnitine, has been linked to increased neuroinflammation, protein misfolding, and cognitive decline. In AD, elevated TMAO levels are associated with amyloid-beta and tau pathologies, blood-brain barrier disruption, and neuronal death. TMAO can cross the blood-brain barrier and promote the aggregation of amyloid and tau proteins. Similarly, TMAO affects alpha-synuclein conformation and aggregation, a hallmark of PD. TMAO also activates pro-inflammatory pathways such as NF-kB signaling, exacerbating neuroinflammation further. Moreover, TMAO modulates the expression of various miRNAs that are involved in neurodegenerative processes. Thus, the gut microbiome-miRNA-brain axis represents a newly discovered mechanistic link between gut dysbiosis and neurodegeneration. MiRNAs regulate the key pathways involved in neuroinflammation, oxidative stress, and neuronal death, contributing to disease progression. As a direct consequence, specific miRNA signatures may serve as potential biomarkers for the early detection and monitoring of AD and PD progression. This review aims to elucidate the complex interrelationships between the gut microbiota, trimethylamine-N-oxide (TMAO), microRNAs (miRNAs), and the central nervous system, and the implications of these connections in neurodegenerative diseases. In this context, an overview of the current neuroradiology techniques available for studying neuroinflammation and of the animal models used to investigate these intricate pathologies will also be provided. In summary, a bulk of evidence supports the concept that modulating the gut-brain communication pathway through dietary changes, the manipulation of the microbiome, and/or miRNA-based therapies may offer novel approaches for implementing the treatment of debilitating neurological disorders.

EVs-mediated delivery of CB2 receptor agonist for Alzheimer's disease therapy

Alzheimer's disease (AD) is a typical neurodegenerative disease that leads to irreversible neuronal degeneration, and effective treatment remains elusive due to the unclear mechanism. We utilized biocompatible mesenchymal stem cell-derived extracellular vesicles as carriers loaded with the CB2 target medicine AM1241 (EVs-AM1241) to protect against neurodegenerative progression and neuronal function in AD model mice. According to the results, EVs-AM1241 were successfully constructed and exhibited better bioavailability and therapeutic effects than bare AM1241. The Morris water maze (MWM) and fear conditioning tests revealed that the learning and memory of EVs-AM1241-treated model mice were significantly improved. In vivo electrophysiological recording of CA1 neurons indicated enhanced response to an auditory conditioned stimulus following fear learning. Immunostaining and Western blot analysis showed that amyloid plaque deposition and amyloid β (Aβ)-induced neuronal apoptosis were significantly suppressed by EVs-AM1241. Moreover, EVs-AM1241 increased the number of neurons and restored the neuronal cytoskeleton, indicating that they enhanced neuronal regeneration. RNA sequencing revealed that EVs-AM1241 facilitated Aβ phagocytosis, promoted neurogenesis and ultimately improved learning and memory through the calcium-Erk signaling pathway. Our study showed that EVs-AM1241 efficiently reversed neurodegenerative pathology and enhanced neurogenesis in model mice, indicating that they are very promising particles for treating AD.

Biomedical knowledge graph learning for drug repurposing by extending guilt-by-association to multiple layers

Computational drug repurposing aims to identify new indications for existing drugs by utilizing high-throughput data, often in the form of biomedical knowledge graphs. However, learning on biomedical knowledge graphs can be challenging due to the dominance of genes and a small number of drug and disease entities, resulting in less effective representations. To overcome this challenge, we propose a "semantic multi-layer guilt-by-association" approach that leverages the principle of guilt-by-association - "similar genes share similar functions", at the drug-gene-disease level. Using this approach, our model DREAMwalk: Drug Repurposing through Exploring Associations using Multi-layer random walk uses our semantic information-guided random walk to generate drug and disease-populated node sequences, allowing for effective mapping of both drugs and diseases in a unified embedding space. Compared to state-of-the-art link prediction models, our approach improves drug-disease association prediction accuracy by up to 16.8%. Moreover, exploration of the embedding space reveals a well-aligned harmony between biological and semantic contexts. We demonstrate the effectiveness of our approach through repurposing case studies for breast carcinoma and Alzheimer's disease, highlighting the potential of multi-layer guilt-by-association perspective for drug repurposing on biomedical knowledge graphs.

A functional polymorphism in the promoter region of miR-155 predicts the risk of intracranial hemorrhage caused by rupture intracranial aneurysm

BACKGROUND

This study aimed to study the effect and underlying molecular mechanisms of single-nucleotide polymorphism (SNP) rs767649 during the pathogenesis of intracranial aneurysm (IA) rupture.

METHOD

Real-time PCR and Western blot analysis were performed to detect the differentiated expression of miR-155 and matrix metalloproteinase-2 (MMP-2) among different sample groups. Computational analysis and luciferase assay were conducted to study the effect of SNP rs767649 on the expression of miR-155 as well as the regulatory relationship between miR-155 and MMP-2.

RESULTS

In unruptured IA samples, the expression of miR-155 was upregulated while the expression of MMP-2 was downregulated compared with the ruptured IA samples. Similarly, the expression of miR-155 was upregulated while the expression of MMP-2 was downregulated in samples genotyped as AA/AT compared with samples genotyped as TT. In addition, compared with the negative controls, the luciferase activities of cells treated with rs767649A and rs767649T were both elevated with rs767649A-transfected cells expressing the highest luciferase activity. Furthermore, a negative relationship was established between miR-155 and MMP-2 by measuring the luciferase activity of cells cotransfected with miR-155 and the wild-type 3'-untranslated region of MMP-2.

CONCLUSION

The results of this study showed that the SNP rs767649 in the promoter of miR-155 could reduce the transcription activity of miR-155, while poorly expressed miR-155 could increase the incidence of IA rupture by increasing the expression of MMP-2, especially in subjects carrying the TT genotype of SNP rs767649.

The Association between NOS3 Gene Polymorphisms and Hypoxic-Ischemic Encephalopathy Susceptibility and Symptoms in Chinese Han Population

Endothelial NOS (NOS3) has a potential role in the prevention of neuronal injury in hypoxic-ischemic encephalopathy (HIE). Thus, we aimed to explore the association between NOS3 gene polymorphisms and HIE susceptibility and symptoms in a Chinese Han population. Three single nucleotide polymorphisms (SNPs) in the NOS3 gene, rs1800783, rs1800779, and rs2070744, were detected in 226 children with HIE and 212 healthy children in a Chinese Han population. Apgar scores and magnetic resonance image scans were used to estimate the symptoms and brain damage. The association analyses were conducted by using SNPStats and SPSS 18.0 software. The genotype and allele distributions of rs1800779 and rs1799983 displayed no significant differences between the patients and the controls, while the rs2070744 allele distribution was significantly different (corrected P = 0.009). For clinical characteristics, the rs2070744 genotype distribution was significantly different in patients with different Apgar scores (≤5, TT/TC/CC = 6/7/5; 6~7, TT/TC/CC = 17/0/0; 8~9, TT/TC/CC = 6/2/0; 10, TT/TC/CC = 7/1/0; corrected P = 0.006) in the 1001 to 1449 g birth weight subgroup. The haplotype test did not show any associations with the risk and clinical characteristics of HIE. The results suggest that NOS3 gene SNP rs2070744 was significantly associated with HIE susceptibility and symptom expression in Chinese Han population.

Co-morbidity and systemic inflammation as drivers of cognitive decline: new experimental models adopting a broader paradigm in dementia research

Dementia prevalence increases with age and Alzheimer’s disease (AD) accounts for up to 75% of cases. However, significant variability and overlap exists in the extent of amyloid-β and Tau pathology in AD and non-demented populations and it is clear that other factors must influence progression of cognitive decline, perhaps independent of effects on amyloid pathology. Coupled with the failure of amyloid-clearing strategies to provide benefits for AD patients, it seems necessary to broaden the paradigm in dementia research beyond amyloid deposition and clearance. Evidence has emerged from alternative animal model approaches as well as clinical and population epidemiological studies that co-morbidities contribute significantly to neurodegeneration/cognitive decline and systemic inflammation has been a strong common theme in these approaches. We hypothesise, and discuss in this review, that a disproportionate inflammatory response to infection, injury or chronic peripheral disease is a key determinant of cognitive decline. We propose that detailed study of alternative models, which encompass acute and chronic systemic inflammatory co-morbidities, is an important priority for the field and we examine the cognitive consequences of several of these alternative experimental approaches. Experimental models of severe sepsis in normal animals or moderate acute systemic inflammation in animals with existing neurodegenerative pathology have uncovered roles for inflammatory mediators interleukin-1β, tumour necrosis factor-α, inducible nitric oxide synthase, complement, prostaglandins and NADPH oxidase in inflammation-induced cognitive dysfunction and neuronal death. Moreover, microglia are primed by existing neurodegenerative pathology to produce exaggerated responses to subsequent stimulation with bacterial lipopolysaccharide or other inflammatory stimuli and these insults drive acute dysfunction and negatively affect disease trajectory. Chronic co-morbidities, such as arthritis, atherosclerosis, obesity and diabetes, are risk factors for subsequent dementia and those with high inflammatory status are particularly at risk. Models of chronic co-morbidities, and indeed low grade systemic inflammation in the absence of specific pathology, indicate that interleukin-1β, tumour necrosis factor-α and other inflammatory mediators drive insulin resistance, hypothalamic dysfunction, impaired neurogenesis and cognitive function and impact on functional decline. Detailed study of these pathways will uncover important mechanisms of peripheral inflammation-driven cognitive decline and are already driving clinical initiatives to mitigate AD progression through minimising systemic inflammation.

Pharmacological effects of active compounds on neurodegenerative disease with gastrodia and uncaria decoction, a commonly used poststroke decoction

Neurodegenerative diseases refer to the selective loss of neuronal systems in patients. The diseases cause high morbidity and mortality to approximately 22 million people worldwide and the number is expected to be tripled by 2050. Up to now, there is no effective prevention and treatment for the neurodegenerative diseases. Although some of the clinical therapies target at slowing down the progression of symptoms of the diseases, the general effectiveness of the drugs has been far from satisfactory. Traditional Chinese medicine becomes popular alternative remedies as it has been practiced clinically for more than thousands of years in China. As neurodegenerative diseases are mediated through different pathways, herbal decoction with multiple herbs is used as an effective therapeutic approach to work on multiple targets. Gastrodia and Uncaria Decoction, a popular TCM decoction, has been used to treat stroke in China. The decoction contains compounds including alkaloids, flavonoids, iridoids, carotenoids, and natural phenols, which have been found to possess anti-inflammatory, antioxidative, and antiapoptotic effects. In this review, we will summarize the recent publications of the pharmacological effects of these five groups of compounds. Understanding the mechanisms of action of these compounds may provide new treatment opportunities for the patients with neurodegenerative diseases.

Oxidative stress in aging--matters of the heart and mind

Oxidative damage is considered to be the primary cause of several aging associated disease pathologies. Cumulative oxidative damage tends to be pervasive among cellular macromolecules, impacting proteins, lipids, RNA and DNA of cells. At a systemic level, events subsequent to oxidative damage induce an inflammatory response to sites of oxidative damage, often contributing to additional oxidative stress. At a cellular level, oxidative damage to mitochondria results in acidification of the cytoplasm and release of cytochrome c, causing apoptosis. This review summarizes findings in the literature on oxidative stress and consequent damage on cells and tissues of the cardiovascular system and the central nervous system, with a focus on aging-related diseases that have well-documented evidence of oxidative damage in initiation and/or progression of the disease. The current understanding of the cellular mechanisms with a focus on macromolecular damage, impacted cellular pathways and gross morphological changes associated with oxidative damage is also reviewed. Additionally, the impact of calorific restriction with its profound impact on cardiovascular and neuronal aging is addressed.

The expression of SPARC in human intracranial aneurysms and its relationship with MMP-2/-9

Objective

SPARC is a key determinant of invasion and metastasis in some tumors, such as gliomas, melanomas and prostate tumors. SPARC can change the composition and structure of the matrix and promote angiogenesis; these effects are closely related to clinical stage and the prognosis of tumors such as meningiomas. However, little is known about the expression of SPARC in intracranial aneurysms. The goal of this study was to establish the role of SPARC in human intracranial aneurysms.

Methods

Thirty-one intracranial aneurysms were immunohistochemically stained for SPARC, MMP-2 and MMP-9. As controls, normal Circle of Willis arteries were similarly immunostained. All specimens were retrieved during autopsies and were embedded in paraffin. To evaluate the expression levels of SPARC, MMP-2 and MMP-9, western blotting was also performed in three available intracranial aneurysm specimens. The limited availability of fresh intracranial aneurysm tissue was the result of the majority of patients choosing endovascular embolization.

Results

The results showed that SPARC, MMP-2 and MMP-9 were strongly expressed in intracranial aneurysm tissues; however, these proteins were expressed minimally or not at all in normal Circle of Willis arteries. The western blot results showed that the expression levels of SPARC, MMP-2 and MMP-9 were significantly up-regulated in intracranial aneurysms relative to the expression levels in the normal Circle of Willis arteries. Data analysis showed that SPARC was significantly correlated with MMP-2 and MMP-9, also with age and risk factors but not with the Hunt-Hess grade or with sex.

Conclusion

The results indicate that SPARC is widely expressed in human intracranial aneurysms, and its expression correlates with MMP-2 and MMP-9 expression, age and risk factors but not with the Hunt-Hess grade. The results of this study suggest that SPARC has a pathogenic role in the alteration of the extracellular matrix of intracranial arteries during aneurysm formation.

Bilateral common carotid artery ligation transiently changes brain lipid metabolism in rats

Brain lipid metabolism was studied in rats following permanent bilateral common carotid artery ligation (BCCL), a model for chronic cerebral hypoperfusion. Unesterified (free) fatty acids (uFA) and acyl-CoA concentrations were measured 6 h, 24 h, and 7 days after BCCL or sham surgery, in high energy-microwaved brain. In BCCL compared to sham rats, cytosolic phospholipase A(2) (cPLA(2)) immunoreactivity in piriform cortex, and concentrations of total uFA and arachidonoyl-CoA, an intermediate for arachidonic acid reincorporation into phospholipids, were increased only at 6 h. At 24 h, immunoreactivity for secretory phospholipase A(2) (sPLA(2)), which may regulate blood flow, was increased near cortical and hippocampal blood vessels. BCCL did not affect levels of brain IB(4)+ microglia, glial fibrillary acidic protein (GFAP)+ astrocytes, cyclooxygenase-2 (COX-2) immunoreactivity at any time, but increased cPLA(2) immunoreactivity in one region at 6 h. Thus, BCCL affected brain lipid metabolism transiently, likely because of compensatory sPLA(2)-mediated vasodilation, without producing evidence of neuroinflammation.

Maternal-foetal epigenetic interactions in the beginning of cardiovascular damage

Several studies indicate that impaired foetal growth, and in utero exposure to risk factors, especially maternal hypercholesterolaemia, may be relevant for the early onset of cardiovascular damage. The exact molecular mechanisms of such foetal programming are still unclear. Epigenetics may represent one of the possible scientific explanations of the impact of such intrauterine risk factors for the subsequent development of cardiovascular disease (CVD) during adulthood. Translational studies support this hypothesis; however, a direct causality in humans has not been ascertained. This hypothesis could be investigated in primates and in human post-mortem foetal arteries. Importantly, some studies also suggest the transgenerational transmission of epigenetic risk. The recently launched International Human Epigenome Consortium and the NIH Roadmap Epigenomics Mapping Consortium will provide the rationale for a useful clinical scenario for primary prevention and therapy of CVD. Despite the heritable nature of epigenetic modification, the clinically relevant information shows that it could be reversible through therapeutic approaches, including histone deacetylase inhibitors, histone acetyltransferase inhibitors, and commonly used drugs such as statins.

Predictors for Poststroke Outcomes: The Tel Aviv Brain Acute Stroke Cohort (TABASCO) Study Protocol

Background

Recent studies have demonstrated that even survivors of mild stroke experience residual damage, which persists and in fact increases in subsequent years. About 45% of stroke victims remain with different levels of disability. Identifying factors associated with poststroke cognitive and neurological decline could potentially yield more effective therapeutic opportunities.

Aims and hypothesis

We hypothesize that data based on biochemical, neuroimaging, genetic and psychological measures can, in aggregate, serve as better predictors for subsequent disability, cognitive and neurological deterioration, and suggest possible interventions.

Design

The Tel-Aviv Brain Acute Stroke Cohort (TABASCO) study is an ongoing, prospective cohort study that will recruit approximately 1125 consecutive first-ever mild–moderate stroke patients. It is designed to evaluate the association between predefined demographic, psychological, inflammatory, biochemical, neuroimaging and genetic markers, measured during the acute phase, and long-term outcome: subsequent cognitive deterioration, vascular events (including recurrent strokes), falls, affect changes, functional everyday difficulties and mortality.

Discussion

This study is an attempt to comprehensively investigate the long-term outcome of mild–moderate strokes. Its prospective design will provide quantitative data on stroke recurrence, the incidence of other vascular events and the evaluation of cognitive, affective and functional decline. Identifying the factors associated with poststroke cognitive and functional decline could potentially yield more effective therapeutic approaches.

Integrating health into cognitive aging: toward a preventive cognitive neuroscience of aging

OBJECTIVES

We argue that age is a descriptive, and not explanatory, variable and consequently cannot account for the cognitive changes that often occur with aging. Once age is removed from consideration, other truly causal explanations for "cognitive aging" must be identified. We argue that health and disease represent an important class of explanatory variables for age-related cognitive changes.

METHODS/RESULTS

We make this argument first by reviewing the prevalence of risk factors, disability, and subclinical and frank disease in the elderly population. We emphasize that the complexity of health effects rivals that of age on cognition while noting that most studies of cognitive aging rarely consider this complexity fully. We then consider in more detail the "vascular hypothesis," which proposes that vascular diseases (e.g., stroke, heart disease) and their risk factors (e.g., hypertension) can explain aspects of cognitive decline in aging through their impact on circulatory and brain functions. Clinical implications of this hypothesis suggest that treatment of vascular risk factors might well reduce the incidence or severity of dementia syndromes.

DISCUSSION

We conclude with a brief summary of approaches to further integrate aspects of health and disease into the study of "cognitive aging."

Diet, physical activity and cognitive impairment among elders: the EPIC–Greece cohort (European Prospective Investigation into Cancer and Nutrition)

Objectives

To identify dietary and lifestyle variables that may affect cognitive function in the elderly.

Design

Population-based prospective cohort study.

Setting

General community residing in Athens and the surrounding Attica region of Greece.

Subjects

A total of 732 men and women, 60 years or older, participating in the EPIC–Greece cohort (European Prospective Investigation into Cancer and Nutrition) and residing in the Attica region had sociodemographic, anthropometric, medical, dietary and lifestyle variables ascertained at enrolment (1993–1999). Six to 13 years later, cognitive function was evaluated through the Mini-Mental State Examination (MMSE) score and affective state through the Geriatric Depression Scale (GDS).

Results

MMSE score was positively associated with years of formal education, height and physical activity and inversely with age, diabetes mellitus and GDS score (P < 0·05 for all). Among dietary variables, intake of PUFA was inversely associated with cognitive function and this association was largely accounted for by a similar association with seed oils. Adherence to the Mediterranean diet, as well as intake of olive oil, MUFA and SFA exhibited weakly positive but not significant associations.

Conclusion

Physical activity and early life factors as reflected in height are significant predictors of cognitive function in the elderly. Seed oil consumption may adversely affect cognition, whereas other nutritional factors do not appear to have a quantitatively large effect.

Genes and pathways differentially expressed in the brains of Fxr2 knockout mice

Fragile X syndrome is a common inherited form of mental retardation and originates from the absence of expression of the FMR1 gene. This gene and its two homologues, FXR1 and FXR2, encode for a family of fragile X related (FXR) proteins with similar tissue distribution, together with sequence and functional homology. Based on these characteristics, it has been suggested that these proteins might partly complement one another. To unravel the function of Fxr2 protein, the expression pattern of 12,588 genes was studied in the brains of wild-type and Fxr2 knockout mice, an animal model which shows behavioral abnormalities partly similar to those observed in Fmr1-knockout mice. By genome expression profiling and stringent significance tests we identify genes and gene groups de-regulated in the brains of Fxr2 knockout mice. Differential expression of candidate genes was validated by real-time PCR, in situ hybridization, immunohistochemistry and western blot analysis. A number of differentially expressed genes associated with the Fxr2 phenotype have been previously involved in other memory or cognitive disorders.

Oxidative stress in NPC1 deficient cells: protective effect of allopregnanolone

Niemann-Pick C disease (NPC) is an autosomal recessive neurodegenerative disorder caused by the abnormal function of NPC1 or NPC2 proteins, leading to an accumulation of unesterified cholesterol and glycosphingolipids (GSLs) in the lysosomes. The mechanisms underlying the pathophysiology in NPC disease are not clear. Oxidative damage is implicated in the pathophysiology of different neurological disorders and the effect of GSL accumulation on the intracellular redox state has been documented. Therefore, we determined whether the intracellular redox state might contribute to the NPC disease pathophysiology. Because the treatment of NPC mice with allopregnanolone (ALLO) increases their lifespan and delays the onset of neurological impairment, we analysed the effect of ALLO on the oxidative damage in human NPC fibroblasts. Concentrations of reactive oxygen species (ROS) and lipid peroxidation were higher in fibroblasts from NPC patients than in fibroblasts from normal subjects. Fibroblasts from NPC patients were more susceptible to cell death through apoptosis after an acute oxidative insult. This process is mediated by activation of the NF-κB signalling pathway. Knockdown of NPC1 mRNA both in normal fibroblasts and in human SH-SY5Y neuroblastoma cells caused increased ROS concentrations. ALLO treatment of fibroblasts from NPC patients or NPC1 knockdown cells reduced the levels of ROS and lipid peroxidation and prevented peroxide-induced apoptosis and NF-kB activation. Thus, these findings suggest that oxidative stress might contribute to the NPC disease and ALLO might be beneficial in the treatment of the disease, at least in part, due to its ability to restore the intracellular redox state.

Age and apoE associations with complex pathologic features in Alzheimer's disease

The risk for Alzheimer's disease (AD) is influenced by both age and ApoE status. The present study addresses the associations of age and ApoE status on complex pathologic features in AD (n=81) including coexistent cerebrovascular disease (CVD), argyrophilic grain disease (AGD), and Lewy body disease (LBD). The frequency of coexistent cerebrovascular disease increased with increasing age. Age and ApoE status were differentially associated with atherosclerosis, lacunar infarctions, and microvascular pathology. Coexistent Lewy body pathology was negatively associated with age, dropping off abruptly after age 90. The presence of an ApoE epsilon4 allele was associated with an increased frequency of coexistent LBD. Logistic regression analyses demonstrated both dependent and independent effects of age and ApoE status on the presence of coexistent Lewy body pathology in AD. While the decreasing frequency of LBD in AD after age 90 could be partly accounted for by a lower probability of an ApoE epsilon4 allele, the independent association with age suggests either 1) a survival effect, 2) decreased incidence with advancing age, or 3) both.

Plasma tocopherols and risk of cognitive impairment in an elderly Italian cohort

BACKGROUND

Evidence that vitamin E may preserve cognitive function in elderly subjects is conflicting. The most abundant and most investigated form of vitamin E in humans is alpha-tocopherol, but other antioxidant tocopherols (beta, gamma, and delta) exist in nature.

OBJECTIVE

We aimed to investigate plasma concentrations of the natural tocopherols and the tocopherol oxidation markers alpha-tocopherylquinone (alphaTQ) and 5-nitro-gamma-tocopherol (5NGT) in relation to cognitive function in the elderly.

DESIGN

Baseline plasma tocopherols and their oxidation markers were measured in 761 elderly Italian subjects from a population-based cohort assessed in 1999-2000 for mild cognitive impairment (MCI) and dementia. In 2003-2004, information about cognitive status was collected for 615 of the 666 subjects without baseline cognitive impairment. Tocopherols and oxidation markers were analyzed as plasma absolute values divided by serum total cholesterol because lipids affect their blood availability. Analyses were adjusted for sociodemographic, genetic, lifestyle, and medical confounders.

RESULTS

Compared with the corresponding lowest tertile, the risk of prevalent dementia was higher for the highest tertile of delta-tocopherol/cholesterol [odds ratio (OR): 3.87; 95% CI: 1.46, 10.27] and alphaTQ/cholesterol (4.02; 1.45, 11.14), but the risk of incident dementia was not directly associated with plasma vitamin E metabolites. A U-shaped association, with lower risk for intermediate tertiles, was found for prevalent MCI with 5NGT/cholesterol (0.39; 0.17, 0.91) and for incident dementia with gamma-tocopherol/cholesterol (hazard ratio: 0.42; 95% CI: 0.22, 0.84).

CONCLUSIONS

Plasma concentrations of some non-alpha-tocopherol forms of vitamin E are associated with cognitive impairment in elderly people. However, the associations depend on concurrent cholesterol concentration and need further investigation.

Stroke prediction and stroke prevention with atorvastatin in the Collaborative Atorvastatin Diabetes Study (CARDS)

AIMS

Patients with Type 2 diabetes have an elevated risk of stroke. The role of lipid levels and diabetes-specific factors in risk prediction of stroke is unclear, and estimates of efficacy of lipid-lowering therapy vary between trials. We examined predictors of stroke and the effect of atorvastatin on specific stroke subtypes in Type 2 diabetes in the Collaborative Atorvastatin Diabetes Study (CARDS) [a trial of 2838 participants with mean low-density lipoprotein cholesterol < 4.14 mmol/l, no history of macrovascular disease and randomized to atorvastatin 10 mg daily or placebo].

METHODS

Median follow-up was 3.9 years. Cox regression models were used to estimate the effect of atorvastatin on stroke rate and risk of stroke associated with baseline risk factors. Risk factors that predicted stroke in univariate models were examined in a multivariable model.

RESULTS

Independent risk factors predicting stroke were age [10-year increments; hazard ratio (HR) 2.3, P < 0.001], microalbuminuria (albumin : creatinine ratio > 2.5 mg/mmol; HR 2.0, P = 0.007) and glycaemic control (HbA(1c) > 10%; HR 2.7, P = 0.007). Women were at lower risk of stroke (HR 0.3, P = 0.004). Lipids did not predict stroke. Of 60 first strokes, 47 were non-haemorrhagic, 13 were indeterminate and none was definitely haemorrhagic. Atorvastatin treatment was associated with 50% reduction in non-haemorrhagic stroke (95% confidence interval 9%-72%P = 0.024), similar to the 48% reduction (11%-69%) for all strokes combined.

CONCLUSIONS

Diabetes-specific risk factors are important predictors of stroke in Type 2 diabetes. Despite the lack of association between baseline lipids and first stroke, there was a reduction of 50% of non-haemorrhagic strokes associated with atorvastatin treatment in the CARDS population.

Blood inflammatory markers and risk of dementia: The Conselice Study of Brain Aging

Incidence studies of blood inflammatory markers as predictors of dementia in older age are few and did not take into account hyperhomocysteinemia, although this condition is associated with both inflammation and increased risk of dementia. We investigated the relationships of baseline serum C-reactive protein (CRP), serum interleukin 6 (IL6), plasma alpha-1-antichymotrypsin, and hyperhomocysteinemia (defined as plasma total homocysteine>15 micromol/L) with risk of incident Alzheimer's disease (AD) and vascular dementia (VaD) in a dementia-free Italian population-based elderly cohort (n=804, 53.2% women, mean age 74 years) with 4 years of follow-up. No inflammatory marker, alone or in combination, predicted AD risk whereas the combination of high CRP and high IL6 was associated with risk of VaD (HR, 2.56; 95%CI, 1.21-5.50) independently of socio-demographic confounders, traditional risk factors and hyperhomocysteinemia. By contrast, in the same model, hyperhomocysteinemia was independently associated with AD (HR, 1.91; 95%CI, 1.02-3.56) but not VaD risk. Blood inflammatory markers are associated with increased VaD risk but do not predict AD, which seems selectively associated with hyperhomocysteinemia.

A novel role for connexin hemichannel in oxidative stress and smoking-induced cell injury

Oxidative stress is linked to many pathological conditions, including ischemia, atherosclerosis and neurodegenerative disorders. The molecular mechanisms of oxidative stress induced pathophysiology and cell death are currently poorly understood. Our present work demonstrates that oxidative stress induced by reactive oxygen species and cigarette smoke extract depolarize the cell membrane and open connexin hemichannels. Under oxidative stress, connexin expression and connexin silencing resulted in increased and reduced cell deaths, respectively. Morphological and live/dead assays indicate that cell death is likely through apoptosis. Our studies provide new insights into the mechanistic role of hemichannels in oxidative stress induced cell injury.

Altered intracellular redox status in Gaucher disease fibroblasts and impairment of adaptive response against oxidative stress

Gaucher disease (GD) is a lysosomal storage disorder, due to glucosylceramide (GlcCer) accumulation in several body tissues, which causes cellular failure by yet unidentified mechanisms. Several evidence indicates that GD pathogenesis is associated to an impairment in intracellular redox state. In fibroblast primary cultures, reactive oxygen species (ROS) levels and protein carbonyl content resulted significantly increased in GD patients compared to healthy donors, suggesting that GD cells, facing a condition of chronic oxidative stress, have evolved an adaptive response to survive. The ROS rise is probably due to NAD(P)H oxidase activity, being inhibited by the treatment with diphenylene iodonium chloride. Interestingly, GD cells are more sensitive to H(2)O(2) induced cell death, suggesting a dysregulation in the adaptive response to oxidative stress in which APE1/Ref-1 plays a central role. We found that the cytoplasmic amounts of APE1/Ref-1 protein were significantly higher in GD fibroblasts with respect to controls, and that GD cells failed to upregulate its expression upon H(2)O(2) treatment. Both ROS and APE1/Ref-1 increases are due to GlcCer accumulation, being prevented by treatment of GD fibroblasts with Cerezyme and induced in healthy fibroblasts treated with conduritol-beta-epoxide. These data, suggesting that GD cells display an impairment in the cellular redox state and in the adaptive cellular response to oxidative stress, may open new perspectives in the comprehension of GD pathogenesis.

How do heart disease and stroke become risk factors for Alzheimer's disease?

BACKGROUND

Heart disease and stroke are two of the major leading causes of death and disability in the world. Mainly affecting the elderly population, heart disease and stroke are important risk factors for Alzheimer's disease (AD).

METHODS

This review examines the evidence linking chronic brain hypoperfusion (CBH) produced by several types of heart disease and stroke on the development of AD.

RESULTS

The evidence indicates a strong association between such risk factors as coronary artery bypass surgery (CABG), atrial fibrillation, aortic/mitral valve damage, hypertension, hypotension, congestive heart failure, cerebrovascular-carotid atherosclerosis, and transient ischemic attacks in producing CBH. In people whose cerebral perfusion is already diminished by their advanced age, further cerebral blood flow reductions from heart-brain vascular-related risk factors, seemingly increases the probability of AD. The evidence also suggests that a neuronal energy crisis brought on by a relentless CBH is responsible for protein synthesis defects that later result in the classic AD neurodegenerative lesions such as the formation of excess beta-amyloid plaques and neurofibrillary tangles.

CONCLUSIONS

Knowledge of how heart disease and stroke can progress to AD should provide a better understanding of the physiopathology characteristic of AD and also target more precise therapy in preventing, controlling or reversing this dementia.

Matrix metalloproteinases 2 and 9 in human atherosclerotic and non-atherosclerotic cerebral aneurysms

Matrix metalloproteinases 2 and 9 (MMP 2 and -9) have been implicated in the pathogenesis of atherosclerosis and aneurysm formation. The goal of the study was to establish the role of these metalloproteinases in both human atherosclerotic and non-atherosclerotic cerebral aneurysms. Eleven cerebral aneurysms (four atherosclerotic, seven non-atherosclerotic) were immunohistochemically stained for MMP 2 and -9. As controls, atherosclerotic and normal Circle of Willis arteries were similarly immunostained. All specimens were retrieved at autopsy and were paraffin-embedded. In order to evaluate the real MMP 2 and -9 activities, gelatin zymography was also performed in only two available specimens of non-atherosclerotic intracranial aneurysms, because of the relative unavailability of fresh intracranial aneurysm tissue (i.e. reluctance to excise the aneurysm fundus at surgery). Our data establish that MMP 2 and -9 were expressed minimally or not at all in normal Circle of Willis arteries but were strongly expressed in medial smooth muscle cells of atherosclerotic Circle of Willis arteries. In the aneurysm group, both MMP 2 and -9 were strongly expressed in the atherosclerotic aneurysms, but MMP 2 alone was detected in the non-atherosclerotic aneurysms. Zymography revealed a weak enzyme activity correlating to MMP 9 standard recombinant protein. MMP 2 activity was not demonstrated in either specimen. This study shows that the expression of MMP 2 and -9 is associated with atherosclerosis, be it in aneurysmal or non-aneurysmal cerebral vessels but MMP 2 appears to be specifically expressed in aneurysms devoid of atherosclerosis perhaps suggesting a pathogenic role for MMP 2 in the alteration of the extracellular matrix of cerebral arteries during aneurysm formation.

Therapy Insight: type 2 diabetes mellitus and the risk of late-onset Alzheimer's disease

A number of well-designed epidemiological studies have linked type 2 diabetes mellitus (T2DM) with an increased risk of Alzheimer's disease (AD). Several mechanisms could help to explain this proposed link, including insulin and insulin resistance, inflammatory cytokines, and oxidative stress. Obesity or physical inactivity might also influence AD through effects on hypertension, insulin sensitivity or inflammation. Typical AD pathology, such as amyloid-beta deposits, might be exacerbated by insulin dysregulation, T2DM itself, or microvascular disease that is a consequence of T2DM. T2DM patients are not routinely evaluated for cognitive outcomes, and cognitive impairment in T2DM is rarely treated. Similarly, AD patients are not routinely evaluated for T2DM or hyperinsulinemia. Current treatments for AD have only modest benefits, and several drugs that target metabolic and inflammatory pathways are being evaluated, most notably the statins, which reduce LDL and inflammation but might not influence amyloid- deposition, an important precursor for AD. Although some evidence supports a potentially important role for peroxisome proliferative activated receptor agonists such as glitazones, at present there are no published randomized clinical trials in AD patients of any drugs that target insulin or insulin resistance. Clinical implications of the T2DM-AD link include cognitive evaluations of patients with T2DM, and potential benefits for such patients through treatment with statins or diabetes drugs that target insulin.

Synthesis and pharmacochemical study of novel polyfunctional molecules combining anti-inflammatory, antioxidant, and hypocholesterolemic properties

We have designed and synthesized a series of novel molecules having a residue of a classical NSAID and an antioxidant moiety, both attached through amide bonds to a known nootropic structure, an L-proline, trans-4-hydroxy-L-proline or DL-pipecolinic acid residue. The compounds were found to retain anti-inflammatory and antioxidant activities, to acquire hypocholesterolemic action, and to possess a greatly reduced gastrointestinal toxicity. The novel molecules could find useful applications, among others, in slowing the progression or delaying the onset of neurodegenerative diseases.