Circulating ethanolamine plasmalogen indices in Alzheimer's disease: Relation to diagnosis, cognition, and CSF tau.

INTRODUCTION: Altered lipid metabolism is implicated in Alzheimer's disease (AD), but the mechanisms remain obscure. Aging-related declines in circulating plasmalogens containing omega-3 fatty acids may increase AD risk by reducing plasmalogen availability. METHODS: We measured four ethanolamine plasmalogens (PlsEtns) and four closely related phosphatidylethanolamines (PtdEtns) from the Alzheimer's Disease Neuroimaging Initiative (ADNI; n = 1547 serum) and University of Pennsylvania (UPenn; n = 112 plasma) cohorts, and derived indices reflecting PlsEtn and PtdEtn metabolism: PL-PX (PlsEtns), PL/PE (PlsEtn/PtdEtn ratios), and PBV (plasmalogen biosynthesis value; a composite index). We tested associations with baseline diagnosis, cognition, and cerebrospinal fluid (CSF) AD biomarkers. RESULTS: Results revealed statistically significant negative relationships in ADNI between AD versus CN with PL-PX (P = 0.007) and PBV (P = 0.005), late mild cognitive impairment (LMCI) versus cognitively normal (CN) with PL-PX (P = 2.89 × 10-5 ) and PBV (P = 1.99 × 10-4 ), and AD versus LMCI with PL/PE (P = 1.85 × 10-4 ). In the UPenn cohort, AD versus CN diagnosis associated negatively with PL/PE (P = 0.0191) and PBV (P = 0.0296). In ADNI, cognition was negatively associated with plasmalogen indices, including Alzheimer's Disease Assessment Scale 13-item cognitive subscale (ADAS-Cog13; PL-PX: P = 3.24 × 10-6 ; PBV: P = 6.92 × 10-5 ) and Mini-Mental State Examination (MMSE; PL-PX: P = 1.28 × 10-9 ; PBV: P = 6.50 × 10-9 ). In the UPenn cohort, there was a trend toward a similar relationship of MMSE with PL/PE (P = 0.0949). In ADNI, CSF total-tau was negatively associated with PL-PX (P = 5.55 × 10-6 ) and PBV (P = 7.77 × 10-6 ). Additionally, CSF t-tau/Aß1-42 ratio was negatively associated with these same indices (PL-PX, P = 2.73 × 10-6 ; PBV, P = 4.39 × 10-6 ). In the UPenn cohort, PL/PE was negatively associated with CSF total-tau (P = 0.031) and t-tau/Aß1-42 (P = 0.021). CSF Aß1-42 was not significantly associated with any of these indices in either cohort. DISCUSSION: These data extend previous studies by showing an association of decreased plasmalogen indices with AD, mild cognitive impairment (MCI), cognition, and CSF tau. Future studies are needed to better define mechanistic relationships, and to test the effects of interventions designed to replete serum plasmalogens.

Selenium detoxification is required for cancer-cell survival.

The micronutrient selenium is incorporated via the selenocysteine biosynthesis pathway into the rare amino acid selenocysteine, which is required in selenoproteins such as glutathione peroxidases and thioredoxin reductases1,2. Here, we show that selenophosphate synthetase 2 (SEPHS2), an enzyme in the selenocysteine biosynthesis pathway, is essential for survival of cancer, but not normal, cells. SEPHS2 is required in cancer cells to detoxify selenide, an intermediate that is formed during selenocysteine biosynthesis. Breast and other cancer cells are selenophilic, owing to a secondary function of the cystine/glutamate antiporter SLC7A11 that promotes selenium uptake and selenocysteine biosynthesis, which, by allowing production of selenoproteins such as GPX4, protects cells against ferroptosis. However, this activity also becomes a liability for cancer cells because selenide is poisonous and must be processed by SEPHS2. Accordingly, we find that SEPHS2 protein levels are elevated in samples from people with breast cancer, and that loss of SEPHS2 impairs growth of orthotopic mammary-tumour xenografts in mice. Collectively, our results identify a vulnerability of cancer cells and define the role of selenium metabolism in cancer.

Design of comprehensive Alzheimer's disease centers to address unmet national needs.

The problem of Alzheimer's disease (AD) exemplifies the challenges of dealing with a broad range of aging-related chronic disorders that require long-term, labor-intensive, and expensive care. As the baby boom generation ages and brain diseases become more prevalent, the need to confront the pending health care crisis is more urgent than ever before. Indeed, there is now a critical need to expand significantly the national effort to solve the problem of AD, with special focus on prevention. The Campaign to Prevent Alzheimer's Disease by 2020 (PAD2020) aims to create a new paradigm for planning and supporting the organization of worldwide cooperative research networks to develop new technologies for early detection and treatments of aging-related memory and motor impairments. PAD 2020 is developing an implementation plan to justify (1) increasing the federal budget for research, (2) developing novel national resources to discover new interventions for memory and motor disorders, and (3) creating innovative and streamlined decision-making processes for selecting and supporting new ideas. Since 1978 the National Institute on Aging or National Institute of Health (NIH) established an extensive national network of AD research facilities at academic institutions including AD Centers (ADCs), Consortium to Establish a Registry for AD, AD Cooperative Study (ADCS), AD Drug Discovery Program, National Alzheimer's Coordinating Center, National Cell Repository for AD, and AD Neuroimaging Initiative. However, despite the success of these programs and their critical contributions, they are no longer adequate to meet the challenges presented by AD. PAD 2020 is designed to address these changes by improving the efficiency and effectiveness of these programs. For example, the ADCs (P30s and P50s) can be enhanced by converting some into Comprehensive Alzheimer's Disease Centers (CADCs) to support not only research, but also by being demonstration projects on care/treatment, clinical trials, and education as well as by seamlessly integrating multisite collaborative studies (ADCS, AD Neuroimaging Initiative, Patient Registries, Clinical Data Banks, etc) into a cohesive structure that further enhances the original mission of the National Institute on Aging ADCs. Regional CADCs offer greater efficiency and cost savings while serving as coordinating hubs of existing ADCs, thereby offering greater economies of scale and programmatic integration. The CADCs also broaden the scope of ADC activities to include research on interventions, diagnosis, imaging, prevention trials, and other longitudinal studies that require long-term support. Thus, CADCs can address the urgent need to identify subjects at high risk of AD for prevention trials and very early in the course of AD for clinical trials of disease modification. The enhanced CADCs will allow more flexibility among ADCs by supporting collaborative linkages with other institutions and drawing on a wider expertise from different locations. This perspective article describes the University of Pennsylvania (Penn) CADC Model as an illustrative example of how an existing ADC can be converted into a CADC by better utilization of Penn academic resources to address the wide range of problems concerning AD. The intent of this position paper is to stimulate thinking and foster the development of other or alternative models for a systematic approach to the study of dementia and movement disorders.

The impact of P-glycoprotein and Mrp2 on mycophenolic acid levels in mice.

Considerable variability has been observed in the exposure to mycophenolic acid (MPA) in transplant patients. The objective of this study was to clarify the roles of two important transporters, P-gp and Mrp2, in MPA absorption using an in vivo model. FVB strain wild-type, Mdr1a/1b(-/-) and Mrp2(-/-) mice were subjected to the administration of mycophenolate mofetil (MMF) alone or MMF in combination with cyclosporine (CsA), an immunosuppressive inhibitor of P-gp and Mrp2. At 30 min following treatment, the MPA levels in Mdr1a/1b(-/-) and Mrp2(-/-) mice were markedly increased as compared to wild-type mice. In contrast to the reduced MPA concentrations observed at 60 and 120 min in the CsA-treated groups, CsA produced increased mycophenolate glucuronide (MPAG) plasma levels in CsA-treated mice at each sampling time. Brain concentrations of MPA were elevated in the Mdr1a/1b(-/-) mice at 30 min after MMF in conjunction with increased plasma MPA concentrations, but not in the wild-type or the Mrp2(-/-) mice. This study demonstrated that: a) MPA appears to be a substrate for P-gp, and b) MPA plasma concentrations are influenced by multiple membrane transporters. Drug-transporter interactions must be considered in patients receiving mycophenolic acid products.