Glutathione S-transferase P1 and T1 gene polymorphisms predict longitudinal course and age at onset of Alzheimer disease

Genetic Polymorphisms in Oxidative Stress and Inflammatory Pathways as Potential Biomarkers in Alzheimer's Disease and Dementia

Oxidative stress and neuroinflammation are important processes involved in Alzheimer's disease (AD) and mild cognitive impairment (MCI). Numerous risk factors, including genetic background, can affect the complex interplay between those mechanisms in the aging brain and can also affect typical AD hallmarks: amyloid plaques and neurofibrillary tangles. Our aim was to evaluate the association of polymorphisms in oxidative stress- and inflammation-related genes with cerebrospinal fluid (CSF) biomarker levels and cognitive test results. The study included 54 AD patients, 14 MCI patients with pathological CSF biomarker levels, 20 MCI patients with normal CSF biomarker levels and 62 controls. Carriers of two polymorphic IL1B rs16944 alleles had higher CSF Aβ_1-42 levels (p = 0.025), while carriers of at least one polymorphic NFE2L2 rs35652124 allele had lower CSF Aβ_1-42 levels (p = 0.040). Association with IL1B rs16944 remained significant in the AD group (p = 0.029). Additionally, MIR146A rs2910164 was associated with Aβ_42/40 ratio (p = 0.043) in AD. Significant associations with cognitive test scores were observed for CAT rs1001179 (p = 0.022), GSTP1 rs1138272 (p = 0.005), KEAP1 rs1048290 and rs9676881 (both p = 0.019), as well as NFE2L2 rs35652124 (p = 0.030). In the AD group, IL1B rs1071676 (p = 0.004), KEAP1 rs1048290 and rs9676881 (both p = 0.035) remained associated with cognitive scores. Polymorphisms in antioxidative and inflammation genes might be associated with CSF biomarkers and cognitive test scores and could serve as additional biomarkers contributing to early diagnosis of dementia.

Six genetically linked mutations in the CD36 gene significantly delay the onset of Alzheimer's disease

The risk of Alzheimer’s disease (AD) has a strong genetic component, also in the case of late-onset AD (LOAD). Attempts to sequence whole genome in large populations of subjects have identified only a few mutations common to most of the patients with AD. Targeting smaller well-characterized groups of subjects where specific genetic variations in selected genes could be related to precisely defined psychological traits typical of dementia is needed to better understand the heritability of AD. More than one thousand participants, categorized according to cognitive deficits, were assessed using 14 psychometric tests evaluating performance in five cognitive domains (attention/working memory, memory, language, executive functions, visuospatial functions). CD36 was selected as a gene previously shown to be implicated in the etiology of AD. A total of 174 polymorphisms were tested for associations with cognition-related traits and other AD-relevant data using the next generation sequencing. Several associations between single nucleotide polymorphisms (SNP’s) and the cognitive deficits have been found (rs12667404 with language performance, rs3211827 and rs41272372 with executive functions, rs137984792 with visuospatial performance). The most prominent association was found between a group of genotypes in six genetically linked and the age at which the AD patients presented with, or developed, a full-blown dementia. The identified alleles appear to be associated with a delay in the onset of LOAD. In silico studies suggested that the SNP’s alter the expression of CD36 thus potentially affecting CD36-related neuroinflammation and other molecular and cellular mechanisms known to be involved in the neuronal loss leading to AD. The main outcome of the study is an identification of a set of six new mutations apparently conferring a distinct protection against AD and delaying the onset by about 8 years. Additional mutations in CD36 associated with certain traits characteristic of the cognitive decline in AD have also been found.

[Antioxidant status in patients with paranoid schizophrenia and Alzheimer disease]

OBJECTIVE

To study the antioxidant profile of blood plasma in patients with paranoid schizophrenia and Alzheimer disease (AD).

MATERIAL AND METHODS

Thirty-three patients with paranoid schizophrenia and 18 patients with AD were included in the study. Patients with schizophrenia were stratified into two subgroups by response to therapy. The indicators of the antioxidant profile were determined using methods based on chemiluminometry and spectrofluorimetry.

RESULTS

Systemic oxidative stress due to insufficiency of low molecular weight plasma antioxidants is not determined neither in AD nor in treatment resistant schizophrenia. At the same time, a «thiol» oxidative stress, which indirectly indicates a deficiency of the glutathione system, is present in both groups. In patients with paranoid schizophrenia responsive to treatment, systemic oxidative stress is more pronounced and «thiol» oxidative stress is less significant. Among the antipsychotics studied, haloperidol, zuclopenthixol, risperidone and ziprasidone do not exhibit antioxidant properties, but periciazine, clozapine and especially chlorpromazine exhibit strong antioxidant properties, but they unlikely affect the antioxidant potential of blood plasma.

CONCLUSIONS

The glutathione part of the antioxidant system is mostly affected, but systemic oxidative stress is not significant in patients with treatment resistant paranoid schizophrenia and AD. Oxidative disorders are more pronounced in treatment responsive paranoid schizophrenia.

Role of Glutathione-S-transferases in neurological problems

INTRODUCTION

Role of Glutathione-S-transferases (GSTs) has been well explored in the cellular detoxification process, regulation of redox homeostasis and S-glutothionylation of target proteins like JNK, ASK1 etc. However, altered levels or functions of this enzyme or their subtypes have emerged in the development of several pathologies diseases such as Alzheimer's disease, Parkinson's disease, cancer and related conditions. Oxidative stress is one of the possible pathological events that contributes significantly to activation of degenerating cascades inside neuronal cells. The central nervous system is highly sensitive to oxidative stress because of low levels or capacities of antioxidant enzymes. The brain is highly metabolic in nature making it susceptible to oxidative stress. Areas covered: The present review provides a comprehensive overview of the multiple connections of GSTs within diverse neurological diseases including cancer. Furthermore, the authors have made significant efforts to discuss the regulation of different GST isoforms that have been associated with various pathological processes such as glioblastoma, Alzheimer's disease, Parkinson's disease, stroke and epilepsy. Expert opinion: Though GSTs have been one of the key areas of scientific research over the last few decades, much remains to be elucidated about their physiological functions as well as pathological involvement of GSTs and their polymorphic variants.

Oxidative Stress in Neurodegenerative Diseases

The pathophysiologies of neurodegenerative diseases, including amyotrophic lateral sclerosis (ALS), Parkinson's disease (PD), and Alzheimer's disease (AD), are far from being fully explained. Oxidative stress (OS) has been proposed as one factor that plays a potential role in the pathogenesis of neurodegenerative disorders. Clinical and preclinical studies indicate that neurodegenerative diseases are characterized by higher levels of OS biomarkers and by lower levels of antioxidant defense biomarkers in the brain and peripheral tissues. In this article, we review the current knowledge regarding the involvement of OS in neurodegenerative diseases, based on clinical trials and animal studies. In addition, we analyze the effects of the drug-induced modulation of oxidative balance, and we explore pharmacotherapeutic strategies for OS reduction.

The Genetic Architecture of Murine Glutathione Transferases

Glutathione S-transferase (GST) genes play a protective role against oxidative stress and may influence disease risk and drug pharmacokinetics. In this study, massive multiscalar trait profiling across a large population of mice derived from a cross between C57BL/6J (B6) and DBA2/J (D2)—the BXD family—was combined with linkage and bioinformatic analyses to characterize mechanisms controlling GST expression and to identify downstream consequences of this variation. Similar to humans, mice show a wide range in expression of GST family members. Variation in the expression of Gsta4, Gstt2, Gstz1, Gsto1, and Mgst3 is modulated by local expression QTLs (eQTLs) in several tissues. Higher expression of Gsto1 in brain and liver of BXD strains is strongly associated (P < 0.01) with inheritance of the B6 parental allele whereas higher expression of Gsta4 and Mgst3 in brain and liver, and Gstt2 and Gstz1 in brain is strongly associated with inheritance of the D2 parental allele. Allele-specific assays confirmed that expression of Gsto1, Gsta4, and Mgst3 are modulated by sequence variants within or near each gene locus. We exploited this endogenous variation to identify coexpression networks and downstream targets in mouse and human. Through a combined systems genetics approach, we provide new insight into the biological role of naturally occurring variants in GST genes.

Effects of APOE rs429358, rs7412 and GSTM1/GSTT1 Polymorphism on Plasma and Erythrocyte Antioxidant Parameters and Cognition in Old Chinese Adults

Apolipoprotein E (APOE) and oxidative damage were correlated with the risk of Alzheimer’s disease (AD). Glutathione S-transferase (GST) polymorphism was proved to be associated with body antioxidant capacity and involved in the oxidative damage related chronic diseases. To explore the combined effects of APOE rs429358, rs7412 and GSTM1/T1 polymorphism on antioxidant parameters and cognition in old Chinese adults, a community-based cross-sectional study was carried out in 477 Chinese adults aged from 55 to 75. Information on demography and lifestyle of the participants was collected with a questionnaire. Cognitive function was measured by using a Montreal Cognitive Assessment (MoCA) test. Fasting venous blood samples were collected for APOE rs429358, rs7412 and GSTM1/T1 genotyping, and parameter measurement. No association of APOE rs7412, rs429358 and GSTM1/T1 polymorphisms with cognition was detected in the old Chinese adults. APOE rs429358, rs7412 polymorphism was mainly associated with plasma α-tocopherol, low density lipoprotein cholesterol (LDL-C) and plasma total antioxidant capacity (T-AOC) levels (p < 0.05). Interaction of APOE rs429358 and GSTT1 genotype on the plasma triglyceride (TG) level and erythrocyte catalase (CAT) and GST enzyme activities were detected (p < 0.05). The subjects with APOE rs429358 T/C + C/C and GSTT1− genotype were found to have the highest plasma TG level, erythrocyte CAT enzyme activity, and the lowest GST enzyme activity compared to subjects with other genotypes (p < 0.05). Lowest erythrocyte CAT enzyme activity and highest glutathione peroxidase (GSH-Px) enzyme activity were detected in the subjects with APOE rs7412 T/C + T/T and GSTM1+ genotype as compared with subjects with other genotypes. The levels of plasma and erythrocyte antioxidant parameters were APOE genotype associated. GSTM1 or GSTT1 genotype modified the influence of APOE rs7412, rs429358 polymorphism on antioxidant parameters.

Glutathione transferases and neurodegenerative diseases

There is substantial agreement that the unbalance between oxidant and antioxidant species may affect the onset and/or the course of a number of common diseases including Parkinson's and Alzheimer's diseases. Many studies suggest a crucial role for oxidative stress in the first phase of aging, or in the pathogenesis of various diseases including neurological ones. Particularly, the role exerted by glutathione and glutathione-related enzymes (Glutathione Transferases) in the nervous system appears more relevant, this latter tissue being much more vulnerable to toxins and oxidative stress than other tissues such as liver, kidney or muscle. The present review addresses the question by focusing on the results obtained by specimens from patients or by in vitro studies using cells or animal models related to Parkinson's and Alzheimer's diseases. In general, there is an association between glutathione depletion and Parkinson's or Alzheimer's disease. In addition, a significant decrease of glutathione transferase activity in selected areas of brain and in ventricular cerebrospinal fluid was found. For some glutathione transferase genes there is also a correlation between polymorphisms and onset/outcome of neurodegenerative diseases. Thus, there is a general agreement about the protective effect exerted by glutathione and glutathione transferases but no clear answer about the mechanisms underlying this crucial role in the insurgence of neurodegenerative diseases.

GSTM1 Null Genotype and GSTP1 Ile105Val Polymorphism Are Associated with Alzheimer's Disease: a Meta-Analysis

Published studies on the associations between glutathione S-transferase (GST) polymorphisms and Alzheimer's disease reported controversial findings. A meta-analysis of published studies was performed to assess the associations between polymorphisms of GSTM1, GSTT1 and GSTP1, and Alzheimer's disease. PubMed, Embase, and other databases were searched for case-control on the associations between polymorphisms of GSTM1, GSTT1 and GSTP1, and Alzheimer's disease. The odds ratio (OR) and 95% confidence interval (95% CI) were used to assess the associations. Eleven articles were finally included into the meta-analysis, including eight studies on GSTM1 null genotype, six studies on GSTT1 null genotype, and six studies on GSTP1 Ile105Val polymorphism. Overall, GSTM1 null genotype was associated with increased risk of Alzheimer's disease (fixed effect OR = 1.34, 95% CI 1.10-1.64, P = 0.004). GSTT1 null genotype was not associated with risk of Alzheimer's disease (random effect OR = 1.15, 95% CI 0.68-1.92, P = 0.60). Besides, GSTP1 Ile105Val polymorphism was significantly associated with increased risk of Alzheimer's disease (Val vs Ile: OR = 1.45, 95% CI 1.05-1.99, P = 0.023; ValVal vs IleIle: OR = 1.87, 95% CI 1.30-2.69, P = 0.001; ValVal vs IleIle + IleVal: OR = 1.76, 95% CI 1.24-2.51, P = 0.002). No obvious risk of publication bias was observed in the meta-analysis. GSTM1 null genotype and GSTP1 Ile105Val polymorphism are associated with increased risk of Alzheimer's disease. More studies with large sample size are needed to validate the findings in the meta-analysis.

Effects of GSTM1/GSTT1 gene polymorphism and fruit & vegetable consumption on antioxidant biomarkers and cognitive function in the elderly: a community based cross-sectional study

Background

It was reported that Glutathione S-transferase (GST) gene polymorphism and fruit and vegetable (FV) intake were associated with body antioxidant capacity. The oxidative/anti-oxidative imbalance played an important role in the pathogenesis of AD. However, the association of GST genotype, dietary FV consumption with body antioxidant biomarkers and cognitive function in the elderly is not clear.

Objective

The aim of the present study was to determine the association of GST genotype, and dietary FV intake, with antioxidant biomarkers and cognitive function in the elderly.

Methods

Food frequency questionnaire was used to collect data of dietary FV intakes in 504 community dwelling elderly aged from 55 to 75 years old. GSTM1 and GSTT1 genotypes were determined by using multiple-PCR method. Plasma and erythrocyte antioxidant biomarkers were measured. Cognitive function was measured by using Montreal Cognitive Assessment. Statistical analysis was applied for exploring the association of GST genotype and FV intake with antioxidant biomarkers level and cognitive function in the elderly.

Results

Individual GSTM1 or GSTT1 gene deletion affects body antioxidant biomarkers levels, including erythrocyte GST activity, plasma total antioxidant capacity, and glutathione levels. GSTM1and/or GSTT1 gene deletion have no effects on cognitive function in the surveyed participants. The effect of GST genotype on antioxidant biomarkers are FV intake dependent. There is interaction of FV intake and GST genotype on cognitive function in the elderly.

Conclusion

GST genotype or daily FV consumption impact body antioxidant biomarkers, but not cognitive function in the elderly. There were combined effects of GST genotype and FV consumption on cognitive function in the elderly population. Large scale perspective population study is required to explore the association of GST genetic polymorphism, FV consumption and antioxidant biomarkers and cognitive function in the elderly.

Polymorphism in Cytochrome P450 2D6, Glutathione S-Transferases Pi 1 Genes, and Organochlorine Pesticides in Alzheimer Disease: A Case-Control Study in North Indian Population

OBJECTIVES

It has been assumed that the association between Alzheimer disease (AD) and pesticides may be stronger among genetically susceptible individuals. The aim of the study was to examine the genetic polymorphism in cytochrome P450 2D6 (CYP2D6) and glutathione S-transferases pi 1 (GSTP1) with respect to organochlorine pesticides (OCPs) and metals in AD.

METHODS

This study included 100 patients with AD and 100 age-matched controls. The genetic polymorphisms were analyzed by restriction fragment length polymorphism. The OCPs and serum metal levels were determined using gas chromatography and an autoanalyzer, respectively.

RESULTS

We found a statistically significant association between AD and high levels of β-hexachlorocyclohexane (β-HCH; odds ratio [OR] = 2.064, 95% confidence intervals [95% CIs] = 1.373-3.102, dieldrin [OR = 2.086, 95% CI = 1.224-3.555], and copper [OR = 1.038, 95% CI = 1.012-1.064). The significant low level of magnesium (OR = 0.151, 95% CI = 0.047-0.489) even appears to have a protective role against AD. The GSTP1*B (P = .009) and GSTP1*C (P = .011) allelic variants were associated with increase in AD risk.

CONCLUSION

This study demonstrates that the GSTP1*B and *C allelic variants may be considered a candidate gene for AD. It can be suggested that although CYP2D6*4 polymorphism is not a risk of AD, the CYP2D6*4 and GSTP1 polymorphism may interact with β-HCH, dieldrin, and copper to influence the risk of AD.

Impaired glutathione synthesis in neurodegeneration

Glutathione (GSH) was discovered in yeast cells in 1888. Studies of GSH in mammalian cells before the 1980s focused exclusively on its function for the detoxication of xenobiotics or for drug metabolism in the liver, in which GSH is present at its highest concentration in the body. Increasing evidence has demonstrated other important roles of GSH in the brain, not only for the detoxication of xenobiotics but also for antioxidant defense and the regulation of intracellular redox homeostasis. GSH also regulates cell signaling, protein function, gene expression, and cell differentiation/proliferation in the brain. Clinically, inborn errors in GSH-related enzymes are very rare, but disorders of GSH metabolism are common in major neurodegenerative diseases showing GSH depletion and increased levels of oxidative stress in the brain. GSH depletion would precipitate oxidative damage in the brain, leading to neurodegenerative diseases. This review focuses on the significance of GSH function, the synthesis of GSH and its metabolism, and clinical disorders of GSH metabolism. A potential approach to increase brain GSH levels against neurodegeneration is also discussed.

Dysregulation of glutathione homeostasis in neurodegenerative diseases

Dysregulation of glutathione homeostasis and alterations in glutathione-dependent enzyme activities are increasingly implicated in the induction and progression of neurodegenerative diseases, including Alzheimer’s, Parkinson’s and Huntington’s diseases, amyotrophic lateral sclerosis, and Friedreich’s ataxia. In this review background is provided on the steady-state synthesis, regulation, and transport of glutathione, with primary focus on the brain. A brief overview is presented on the distinct but vital roles of glutathione in cellular maintenance and survival, and on the functions of key glutathione-dependent enzymes. Major contributors to initiation and progression of neurodegenerative diseases are considered, including oxidative stress, protein misfolding, and protein aggregation. In each case examples of key regulatory mechanisms are identified that are sensitive to changes in glutathione redox status and/or in the activities of glutathione-dependent enzymes. Mechanisms of dysregulation of glutathione and/or glutathione-dependent enzymes are discussed that are implicated in pathogenesis of each neurodegenerative disease. Limitations in information or interpretation are identified, and possible avenues for further research are described with an aim to elucidating novel targets for therapeutic interventions. The pros and cons of administration of N-acetylcysteine or glutathione as therapeutic agents for neurodegenerative diseases, as well as the potential utility of serum glutathione as a biomarker, are critically evaluated.

Analysis of copy number variation in Alzheimer's disease: the NIALOAD/ NCRAD Family Study

Copy number variants (CNVs) are DNA regions that have gains (duplications) or losses (deletions) of genetic material. CNVs may encompass a single gene or multiple genes and can affect their function. They are hypothesized to play an important role in certain diseases. We previously examined the role of CNVs in late-onset Alzheimer's disease (AD) and mild cognitive impairment (MCI) using participants from the Alzheimer's Disease Neuroimaging Initiative (ADNI) study and identified gene regions overlapped by CNVs only in cases (AD and/or MCI) but not in controls. Using a similar approach as ADNI, we investigated the role of CNVs using 794 AD and 196 neurologically evaluated control non-Hispanic Caucasian NIA-LOAD/NCRAD Family Study participants with DNA derived from blood/brain tissue. The controls had no family history of AD and were unrelated to AD participants. CNV calls were generated and analyzed after detailed quality review. 711 AD cases and 171 controls who passed all quality thresholds were included in case/control association analyses, focusing on candidate gene and genome-wide approaches. We identified genes overlapped by CNV calls only in AD cases but not controls. A trend for lower CNV call rate was observed for deletions as well as duplications in cases compared to controls. Gene-based association analyses confirmed previous findings in the ADNI study (ATXN1, HLA-DPB1, RELN, DOPEY2, GSTT1, CHRFAM7A, ERBB4, NRXN1) and identified a new gene (IMMP2L) that may play a role in AD susceptibility. Replication in independent samples as well as further analyses of these gene regions is warranted.

S-glutathionylation: from molecular mechanisms to health outcomes

Redox homeostasis governs a number of critical cellular processes. In turn, imbalances in pathways that control oxidative and reductive conditions have been linked to a number of human disease pathologies, particularly those associated with aging. Reduced glutathione is the most prevalent biological thiol and plays a crucial role in maintaining a reduced intracellular environment. Exposure to reactive oxygen or nitrogen species is causatively linked to the disease pathologies associated with redox imbalance. In particular, reactive oxygen species can differentially oxidize certain cysteine residues in target proteins and the reversible process of S-glutathionylation may mitigate or mediate the damage. This post-translational modification adds a tripeptide and a net negative charge that can lead to distinct structural and functional changes in the target protein. Because it is reversible, S-glutathionylation has the potential to act as a biological switch and to be integral in a number of critical oxidative signaling events. The present review provides a comprehensive account of how the S-glutathionylation cycle influences protein structure/function and cellular regulatory events, and how these may impact on human diseases. By understanding the components of this cycle, there should be opportunities to intervene in stress- and aging-related pathologies, perhaps through prevention and diagnostic and therapeutic platforms.

Behavioural genetics of Alzheimer's disease: a comprehensive review

Behavioural and psychological symptoms of dementia (BPSD) are present in the course of the illness in up to 90% of patients with Alzheimer's disease (AD). They are the main source of caregiver burden and one of the major factors contributing to early institutionalization. The involvement of a genetic component in BPSD aetiology seems beyond controversy, though the exact significance of particular polymorphisms is uncertain in the majority of cases. Multiple genes have been assessed for their putative influence on BPSD risk. In this paper we review the behavioural genetics of AD, particularly the importance, with respect to BPSD risk, of genes coding for apolipoprotein E and proteins involved in the process of neurotransmission: serotonin receptors, serotonin transporter, COMT, MAO-A, tryptophan hydroxylase and dopamine receptors. A general conclusion is the striking inconsistency of the findings, unsurprising in the field of psychiatric genetics. The potential reasons for such discrepancy are exhaustively discussed.

Microarray analysis on human neuroblastoma cells exposed to aluminum, β(1-42)-amyloid or the β(1-42)-amyloid aluminum complex

Background

A typical pathological feature of Alzheimer's disease (AD) is the appearance in the brain of senile plaques made up of β-amyloid (Aβ) and neurofibrillary tangles. AD is also associated with an abnormal accumulation of some metal ions, and we have recently shown that one of these, aluminum (Al), plays a relevant role in affecting Aβ aggregation and neurotoxicity.

Methodology

In this study, employing a microarray analysis of 35,129 genes, we investigated the effects induced by the exposure to the Aβ_1–42-Al (Aβ-Al) complex on the gene expression profile of the neuronal-like cell line, SH-SY5Y.

Principal Findings

The microarray assay indicated that, compared to Aβ or Al alone, exposure to Aβ-Al complex produced selective changes in gene expression. Some of the genes selectively over or underexpressed are directly related to AD. A further evaluation performed with Ingenuity Pathway analysis revealed that these genes are nodes of networks and pathways that are involved in the modulation of Ca²⁺ homeostasis as well as in the regulation of glutamatergic transmission and synaptic plasticity.

Conclusions and Significance

Aβ-Al appears to be largely involved in the molecular machinery that regulates neuronal as well as synaptic dysfunction and loss. Aβ-Al seems critical in modulating key AD-related pathways such as glutamatergic transmission, Ca²⁺ homeostasis, oxidative stress, inflammation, and neuronal apoptosis.

Polymorphisms in glutathione S-transferase omega-1 gene and increased risk of sporadic Alzheimer disease

Previous studies examining the association between the glutathione S-transferase omega-1 (GSTO1) single-nucleotide polymorphisms (SNPs) and Alzheimer disease (AD) have yielded conflicting results. Furthermore, an effect of GSTO1 rs4925 on the age-at-onset (AAO) of AD was found in different studies on sporadic and familial AD cases, but with contrasting findings. A total sample of 103 AD patients, and 157 age- and sex-matched unrelated caregivers from Apulia, southern Italy, were genotyped for the apolipoprotein E (APOE) polymorphism and the GSTO1 rs4925 and rs1804834 SNPs. Furthermore, we performed a haplotype analysis on these two SNPs on the GSTO1 locus and evaluated the possibility of interaction with APOE. Significant differences were observed in rs4925 genotype distribution between AD patients and age- and sex-matched healthy controls. Both the C/A (odds ratio [OR] = 3.116; 95% confidence interval [CI], 1.749-5.550) and the A/A (OR = 10.802; 95% CI, 3.605-32.128) genotypes resulted in an association with AD. A higher frequency of the allele A was observed in AD patients than in age- and sex-matched controls (OR = 3.789; 95% CI, 2.442-5.878). No significant differences were observed in the rs1804834 genotype or allele frequencies between AD patients and controls. No significant influence of the GSTO1 genotypes on the AAO was observed. No significant interaction was found among the GSTO1 SNPs and APOE. In both AD and controls, no important linkage disequilibrium (LD) was observed among the markers investigated. Whereas the C-A haplotype appeared to be protective against AD (OR = 0.303; 95% CI, 0.204-0.451), the A-A haplotype appeared to be at increased risk for AD (OR = 4.014,; 95% CI, 2.528-6.382). Our findings supported a role of the GSTO1 rs4925 SNP in the risk of sporadic AD in southern Italy, suggesting that this and other variants of the GSTO1 gene could be implicated in AD pathogenesis.

Overexpression of aldehyde dehydrogenase 1A1 reduces oxidation-induced toxicity in SH-SY5Y neuroblastoma cells

Oxidative stress leading to lipid peroxidation is a problem in neurodegenerative diseases, because the brain is rich in polyunsaturated fatty acids and low in endogenous antioxidants. One of the most toxic byproducts of lipid peroxidation, 4-hydroxynonenal (HNE), is implicated in oxidative stress-induced damage in neurodegenerative diseases such as Alzheimer's disease (AD), Parkinson's disease (PD), and amyotrophic lateral sclerosis (ALS). In this study, the human neuroblastoma cell line SH-SY5Y was used to test the protective effects of increasing the detoxification of HNE by overexpressing the HNE-detoxifying enzyme aldehyde dehydrogenase 1A1 (ALDH1). Overexpression of ALDH1 in the SH-SY5Y cells acts to reduce production of protein-HNE adducts and activation of caspase-3. Our data suggest that detoxification of HNE could be therapeutic in preventing some of the toxic disruptions of the brain's redox systems found in many neurodegenerative diseases.

Efficacy of a vitamin/nutriceutical formulation for early-stage Alzheimer's disease: a 1-year, open-label pilot study with an 16-month caregiver extension

We examined the efficacy of a vitamin/nutriceutical formulation (folate, vitamin B6, alpha-tocopherol, S-adenosyl methionine, N-acetyl cysteine, and acetyl-L-carnitine) in a 12-month, open-label trial with 14 community-dwelling individuals with early-stage Alzheimer's disease. Participants improved in the Dementia Rating Scale and Clock-drawing tests (Clox 1 and 2). Family caregivers reported improvement in multiple domains of the Neuropsychiatric Inventory (NPI) and maintenance of performance in the Alzheimer's Disease Cooperative Study-Activities of Daily Living (ADL). Sustained performance was reported by caregivers for those participants who continued in an 16-month extension. Performance on the NPI was equivalent to published findings at 3 to 6 months for donepezil and exceeded that of galantamine and their historical placebos. Participants demonstrated superior performance for more than 12 months in NPI and ADL versus those receiving naproxen and rofecoxib or their placebo group. This formulation holds promise for treatment of early-stage Alzheimer's disease prior to and/or as a supplement for pharmacological approaches. A larger, placebo-controlled trial is warranted.

The role of glutathione-S-transferase polymorphisms on clinical outcome of ALI/ARDS patient treated with N-acetylcysteine

Oxidative stress has a proven role in pathophysiology of acute respiratory distress syndrome. The antioxidant drugs, especially N-acetylcysteine (NAC) have been used for years to overcome oxidative stress effects in patients. In the present study we have investigated the effects of NAC treatment (IV NAC in 150mg/kg at the first day followed by 50mg/kg/day for three days) on 27 ICU patients with ALI/ARDS considering the glutathione-S-transferase genetic variations, as an important enzyme contributing in oxidative stress pathways. The results indicated that NAC improved oxygenation (increase in PaO(2)/FiO(2)) and decreased mortality rate in treated patients compared to control group (p<0.05). Evaluation of three isoforms of glutathione-S-transferase (GST M1, P1 and T1), in these patients have showed an association between GST M1 null, and GST M1 and T1 double null polymorphisms with increased mortality in control group, suggesting antioxidant therapy critical for this group of patients.

Biomarkers in geriatric psychiatry: searching for the holy grail?

PURPOSE OF REVIEW

Biomarkers in clinical medicine are used to detect or diagnose specific illnesses, predict disease progression, and predict the response to treatment. As the proportion of adults over 65 years of age rises, there is a growing need to detect neurodegenerative disease at an earlier stage with the goal of improving treatment for highly prevalent illnesses such as late-life depression and dementia.

RECENT FINDINGS

The search for biomarkers of late-life mental disorders includes the exploration of structural neuroimaging, functional neuroimaging, genomics, proteomics, noninvasive neurophysiology, cerebrospinal fluid, and plasma analysis. Novel structural and functional neuroimaging techniques that have recently been developed show promise as biomarkers of both late-life depression and specific dementia syndromes. The fields of proteomics and genomics are advancing our ability to identify genes and aberrant proteins that detect preclinical dementia. As depression is often a harbinger of dementia in late life, recent studies are beginning to elucidate the relationship between different types of late-life depression and the subsequent emergence of dementia.

SUMMARY

Biomarker research in late-life mental disorders is progressing at a rapid pace. The application of current biomarkers to clinical practice may be on the horizon with further research that refines their sensitivity and specificity.

Stroke genetic research and adults with impaired decision-making capacity: a survey of IRB and investigator practices

BACKGROUND AND PURPOSE

In stroke and other brain disorders, severely affected phenotypes often impair decision-making capacity. Severity is in part under genomic control. Therefore, scientifically valid research into genetic risk may require inclusion of such impaired individuals. U.S. Federal regulations do not detail rules governing enrollment of adults with impaired decision-making capacity into genetic research. Rather, policy and practice are locally determined. This study was conducted to obtain data on how investigators and IRBs handle surrogate authorization to enroll probands into a genetic study where some may lack capacity because of ischemic stroke.

METHODS

Sequential surveys of sites from an ongoing North American study investigating genetic risks for ischemic stroke (2003: 49 sites, response rate=100%; 2007: 53 sites; response rate=91%) assessed whether and how investigators enroll adults with impaired decision-making capacity and determined frequency of IRB approval for enrollment by surrogate authorization.

RESULTS

Approximately 40% of sites report that their IRBs do not approve surrogate authorization to enroll stroke patients-43% (21/49) in 2003 and 35% (17/48) in 2007. Thirty-three percent of sites report evaluating eligible adults who lacked capacity to provide their own informed consent; 18% (9/49) in 2003 and 15% (7/48) in 2007 have enrolled these individuals. Surrogate enrollment is the most common method used. Most sites have not enrolled any individual lacking capacity to give his or her own consent.

CONCLUSIONS

Our study suggests that enrollment by surrogate authorization into stroke genetic research is often not approved by IRBs, and even when allowed is frequently not used. For disorders like stroke, this situation has significant implications for scientific validity.

A GSTM3 polymorphism associated with an etiopathogenetic mechanism in Alzheimer disease

Brain-specific glutathione S-transferase Mu 3 (GSTM3) colocalizes with amyloid-beta plaques in Alzheimer's disease (AD). A functional polymorphism rs7483 in GSTM3 may contribute to the decrease in GSTM3 expression in AD. The association of the rs7483 SNP with late-onset AD and mild cognitive impairment (MCI) was evaluated and the impact of a SNP background on gene expression was analyzed in blood mononuclear cells (BMC). The allelic association of the GSTM3 allele with AD was significant in women and in APOEvarepsilon4-negative stratum. A significant association was also found in both MCI and AD subjects with AD family history. GSTM3 transcript levels in BMC were lower in AD than in normal elderly controls, and the presence of the risk allele was associated with further mRNA reduction. Diminished GSTM3 mRNA levels correlated with decreased minichromosome maintenance deficient 3 (MCM3) mRNA levels in a diagnostic and SNP-dependent fashion. Reduced antioxidant defense and genome maintenance associated with the GSTM3 polymorphism suggest a common hub of regulatory networks which, when impaired, may lead to AD.

Interleukin 18 gene polymorphisms predict risk and outcome of Alzheimer's disease

BACKGROUND AND AIM

Inflammation has been extensively implicated in the pathogenesis of Alzheimer's disease (AD). Although there is evidence of a key role for cytokines in neuroinflammation processes, so far the proinflammatory cytokine interleukin (IL)-18 has not been associated with AD. The aim of this study was to investigate the impact of two polymorphisms of the human IL-18 gene promoter at positions -607 (C/A) and -137 (G/C) on both susceptibility to and progression of AD.

RESULTS

The results revealed that the genotype distribution of the -607 (C/A) polymorphism was different between patients with AD and control subjects (chi2 = 7.99, df = 2, p = 0.0184). In particular, carriers of the CC genotype were at increased risk of developing AD (OR 2.33; 95% CI 1.29 to 4.22; p = 0.0052). The observed genotypes were in Hardy-Weinberg equilibrium, as for the -607 polymorphism, whereas the -137 polymorphism appeared in Hardy-Weinberg disequilibrium only in the patient group (p = 0.0061). Finally, in a 2 year follow-up study, the -137 CC genotype was strongly and specifically associated with a faster cognitive decline (F = 4.024; df = 4,192; p = 0.0037 for time by IL-18 -137 G/C group interaction) with no interaction effect with the apolipoprotein E epsilon4/non-epsilon4 allele presence.

CONCLUSION

As IL-18 cytokine promoter gene polymorphisms have been previously described to have functional consequences on IL-18 expression, it is possible that individuals with a prevalent IL-18 gene variant have a dysregulated immune response, suggesting that IL-18 mediated immune mechanisms may play a crucial role in AD.