SIRT1, miR-132 and miR-212 link human longevity to Alzheimer's Disease.

Alzheimer's Disease (AD) is the most common cause of dementia in the elderly. Centenarians - reaching the age of >100 years while maintaining good cognitive skills - seemingly have unique biological features allowing healthy aging and protection from dementia. Here, we studied the expression of SIRT1 along with miR-132 and miR-212, two microRNAs known to regulate SIRT1, in lymphoblastoid cell lines (LCLs) from 45 healthy donors aged 21 to 105 years and 24 AD patients, and in postmortem olfactory bulb and hippocampus tissues from 14 AD patients and 20 age-matched non-demented individuals. We observed 4.0-fold (P = 0.001) lower expression of SIRT1, and correspondingly higher expression of miR-132 (1.7-fold; P = 0.014) and miR-212 (2.1-fold; P = 0.036), in LCLs from AD patients compared with age-matched healthy controls. Additionally, SIRT1 expression was 2.2-fold (P = 0.001) higher in centenarian LCLs compared with LCLs from individuals aged 56-82 years; while centenarian LCLs miR-132 and miR-212 indicated 7.6-fold and 4.1-fold lower expression, respectively. Correlations of SIRT1, miR-132 and miR-212 expression with cognitive scores were observed for AD patient-derived LCLs and postmortem AD olfactory bulb and hippocampus tissues, suggesting that higher SIRT1 expression, possibly mediated by lower miR-132 and miR-212, may protect aged individuals from dementia and is reflected in their peripheral tissues.

Assessment of pharmacogenetic tests: presenting measures of clinical validity and potential population impact in association studies.

The progressing discovery of genetic variants associated with drug-related adverse events has raised expectations for pharmacogenetic tests to improve drug efficacy and safety. To further the use of pharmacogenetics in health care, tests with sufficient potential to improve efficacy and safety, as reflected by good clinical validity and population impact, need to be identified. The potential benefit of pharmacogenetic tests is often concluded from the strength of the association between the variant and the adverse event; measures of clinical validity are generally not reported. This paper describes measures of clinical validity and potential population health impact that can be calculated from association studies. We explain how these measures are influenced by the strength of the association and by the frequencies of the variant and the adverse event. The measures are illustrated using examples of testing for HLA-B*5701 associated with abacavir-induced hypersensitivity and SLCO1B1 c.521T>C (*5) associated with simvastatin-induced adverse events.

Proliferation rates and gene expression profiles in human lymphoblastoid cell lines from patients with depression characterized in response to antidepressant drug therapy.

The current therapy success of depressive disorders remains in need of improvement due to low response rates and a delay in symptomatic improvement. Reliable functional biomarkers would be necessary to predict the individual treatment outcome. On the basis of the neurotrophic hypothesis of antidepressant's action, effects of antidepressant drugs on proliferation may serve as tentative individual markers for treatment efficacy. We studied individual differences in antidepressant drug effects on cell proliferation and gene expression in lymphoblastoid cell lines (LCLs) derived from patients treated for depression with documented clinical treatment outcome. Cell proliferation was characterized by EdU (5-ethynyl-2'-deoxyuridine) incorporation assays following a 3-week incubation with therapeutic concentrations of fluoxetine. Genome-wide expression profiling was conducted by microarrays, and candidate genes such as betacellulin-a gene involved in neuronal stem cell regeneration-were validated by quantitative real-time PCR. Ex vivo assessment of proliferation revealed large differences in fluoxetine-induced proliferation inhibition between donor LCLs, but no association with clinical response was observed. Genome-wide expression analyses followed by pathway and gene ontology analyses identified genes with different expression before vs after 21-day incubation with fluoxetine. Significant correlations between proliferation and gene expression of WNT2B, FZD7, TCF7L2, SULT4A1 and ABCB1 (all involved in neurogenesis or brain protection) were also found. Basal gene expression of SULT4A1 (P=0.029), and gene expression fold changes of WNT2B by ex vivo fluoxetine (P=0.025) correlated with clinical response and clinical remission, respectively. Thus, we identified potential gene expression biomarkers eventually being useful as baseline predictors or as longitudinal targets in antidepressant therapy.

RGS2 expression predicts amyloid-ß sensitivity, MCI and Alzheimer's disease: genome-wide transcriptomic profiling and bioinformatics data mining.

Alzheimer's disease (AD) is the most frequent cause of dementia. Misfolded protein pathological hallmarks of AD are brain deposits of amyloid-ß (Aß) plaques and phosphorylated tau neurofibrillary tangles. However, doubts about the role of Aß in AD pathology have been raised as Aß is a common component of extracellular brain deposits found, also by in vivo imaging, in non-demented aged individuals. It has been suggested that some individuals are more prone to Aß neurotoxicity and hence more likely to develop AD when aging brains start accumulating Aß plaques. Here, we applied genome-wide transcriptomic profiling of lymphoblastoid cells lines (LCLs) from healthy individuals and AD patients for identifying genes that predict sensitivity to Aß. Real-time PCR validation identified 3.78-fold lower expression of RGS2 (regulator of G-protein signaling 2; P=0.0085) in LCLs from healthy individuals exhibiting high vs low Aß sensitivity. Furthermore, RGS2 showed 3.3-fold lower expression (P=0.0008) in AD LCLs compared with controls. Notably, RGS2 expression in AD LCLs correlated with the patients' cognitive function. Lower RGS2 expression levels were also discovered in published expression data sets from postmortem AD brain tissues as well as in mild cognitive impairment and AD blood samples compared with controls. In conclusion, Aß sensitivity phenotyping followed by transcriptomic profiling and published patient data mining identified reduced peripheral and brain expression levels of RGS2, a key regulator of G-protein-coupled receptor signaling and neuronal plasticity. RGS2 is suggested as a novel AD biomarker (alongside other genes) toward early AD detection and future disease modifying therapeutics.

Decreased sensitivity to paroxetine-induced inhibition of peripheral blood mononuclear cell growth in depressed and antidepressant treatment-resistant patients.

Major depression disorder (MDD) is the most widespread mental disorder. Selective serotonin reuptake inhibitors (SSRIs) are used as first-line MDD treatment but are effective in <70% of patients. Thus, biomarkers for the early identification of treatment-resistant (TR) MDD patients are needed for prioritizing them for alternative therapeutics. SSRI-induced inhibition of the growth of peripheral blood mononuclear cells (PBMCs) is mediated via their target, the serotonin transporter (SERT). Here, we examined whether antidepressant drug-induced inhibition of the growth of PBMCs differed between MDD patients and healthy controls. PBMCs from well-characterized 33 treatment-sensitive (TS) and 33 TR MDD patients, and 24 healthy volunteers were studied. Dose-dependent inhibition of PBMCs growth was observed for both the non-SSRI antidepressant mirtazapine and the SSRI antidepressant paroxetine. Significantly lower sensitivities to 20 µm paroxetine were observed in MDD compared with control PBMCs prior to treatment onset (13% and 46%, respectively; P<0.05). Following antidepressant drug treatment for 4 or 7 weeks, the ex vivo paroxetine sensitivity increased to control levels in PBMCs from TS but not from TR MDD patients. This suggests that the low ex vivo paroxetine sensitivity phenotype reflects a state marker of depression. A significantly lower expression of integrin beta-3 (ITGB3), a co-factor of the SERT, was observed in the PBMCs of MDD patients prior to treatment onset compared with healthy controls, and may explain their lower paroxetine sensitivity. Further studies with larger cohorts are required for clarifying the potential of reduced PBMCs paroxetine sensitivity and lower ITGB3 expression as MDD biomarkers.

Neuronal cell adhesion genes and antidepressant response in three independent samples.

Drug-effect phenotypes in human lymphoblastoid cell lines recently allowed to identify CHL1 (cell adhesion molecule with homology to L1CAM), GAP43 (growth-associated protein 43) and ITGB3 (integrin beta 3) as new candidates for involvement in the antidepressant effect. CHL1 and ITGB3 code for adhesion molecules, while GAP43 codes for a neuron-specific cytosolic protein expressed in neuronal growth cones; all the three gene products are involved in synaptic plasticity. Sixteen polymorphisms in these genes were genotyped in two samples (n=369 and 90) with diagnosis of major depressive episode who were treated with antidepressants in a naturalistic setting. Phenotypes were response, remission and treatment-resistant depression. Logistic regression including appropriate covariates was performed. Genes associated with outcomes were investigated in the Sequenced Treatment Alternatives to Relieve Depression (STAR*D) genome-wide study (n=1861) as both individual genes and through a pathway analysis (Reactome and String databases). Gene-based analysis suggested CHL1 rs4003413, GAP43 rs283393 and rs9860828, ITGB3 rs3809865 as the top candidates due to their replication across the largest original sample and the STAR*D cohort. GAP43 molecular pathway was associated with both response and remission in the STAR*D, with ELAVL4 representing the gene with the highest percentage of single nucleotide polymorphisms (SNPs) associated with outcomes. Other promising genes emerging from the pathway analysis were ITGB1 and NRP1. The present study was the first to analyze cell adhesion genes and their molecular pathways in antidepressant response. Genes and biomarkers involved in neuronal adhesion should be considered by further studies aimed to identify predictors of antidepressant response.

Genome-wide expression profiling of human lymphoblastoid cell lines implicates integrin beta-3 in the mode of action of antidepressants.

Selective serotonin reuptake inhibitors (SSRIs) are the first-line treatment for major depression. However, the link between inhibition of serotonin reuptake and remission from depression remains controversial: in spite of the rapid onset of serotonin reuptake inhibition, remission from depression takes several weeks, presumably reflecting synaptogenesis/neurogenesis and neuronal rewiring. We compared genome-wide expression profiles of human lymphoblastoid cell lines from unrelated individuals following treatment with 1 µM paroxetine for 21 days with untreated control cells and examined which genes and microRNAs (miRNAs) showed the most profound and consistent expression changes. ITGB3, coding for integrin beta-3, showed the most consistent altered expression (1.92-fold increase, P=7.5 × 10(-8)) following chronic paroxetine exposure. Using genome-wide miRNA arrays, we observed a corresponding decrease in the expression of two miRNAs, miR-221 and miR-222, both predicted to target ITGB3. ITGB3 is crucial for the activity of the serotonin transporter (SERT), the drug target of SSRIs. Moreover, it is presumably required for the neuronal guidance activity of CHL1, whose expression was formerly identified as a tentative SSRI response biomarker. Further genes whose expression was significantly modulated by chronic paroxetine are also implicated in neurogenesis. Surprisingly, the expression of SERT or serotonin receptors was not modified. Our findings implicate ITGB3 in the mode of action of SSRI antidepressants and provide a novel link between CHL1 and the SERT. Our observations suggest that SSRIs may relieve depression primarily by promoting neuronal synaptogenesis/neurogenesis rather than by modulating serotonin neurotransmission per se.

Pharmacogenomic testing: knowing more, doing better.

The clinical uptake of pharmacogenomic (PGx) testing and genotype-based prescribing has been disappointingly slow even though research on PGx is thriving. A recent survey on the adoption of PGx testing by US physicians suggests that this trend may start changing for the better. Acquiring more knowledge of PGx tests and their clinical significance during graduate and postgraduate education will enable physicians to make better use of the available and upcoming PGx diagnostics in clinical practice.

Pharmacogenetics in Europe: barriers and opportunities.

This paper reviews the current situation in the field of pharmacogenetics/pharmacogenomics (PGx) in Europe. High expectations surrounding the clinical application of PGx remain largely unmet, as only a limited number of such applications have actually reached the market and clinical practice. Thus, the potential impact of PGx-based diagnostics on healthcare and its socio-economic implications are still unclear. With the aim of shedding some light on these uncertainties, the Institute for Prospective Technological Studies (IPTS) of the European Commission's Joint Research Centre (JRC) has conducted a review of the 'state of the art' and a further analysis on the use of pharmacogenetics diagnostics for preventing toxic drug reactions and improving drug efficacy in Europe. The paper presents highlights from the JRC-IPTS studies and discusses possibilities for improving translation of PGx research in Europe by comparing some experiences in the USA. We also illustrate the related barriers for the clinical uptake of PGx in Europe with specific case-studies. Most of the barriers identified extend beyond the European context. This reflects the global problems of scarcity of data demonstrating proven clinical validity or utility and favorable cost-effectiveness studies to support the clinical application of PGx diagnostic tests in the clinical setting. Another key barrier is the lack of incentives for the private sector to invest in the development and licensing of PGx diagnostic tests for improving the safety and efficacy of out-of-patent drugs. It therefore seems that one key aspect where policy can affect the clinical uptake of PGx is via sustaining large-scale industry-academia collaborations for developing and proving the utility of PGx diagnostics.

Pharmacogenomics education: International Society of Pharmacogenomics recommendations for medical, pharmaceutical, and health schools deans of education.

Pharmacogenomics would be instrumental for the realization of personalized medicine in coming decades. Efforts are evident to clarify the potential bioethical, societal, and legal implications of key pharmacogenomics-based technologies projected to be soon introduced into the core practice of medicine. In sharp contrast, a lack of sufficient attention to educational aspects of pharmacogenomics, both for professionals and for society at large, is evident. In order to contribute to this discussion, a 'Pharmacogenomics Education Forum' was held on October 2, 2004 during the 3rd Annual Meeting of the International Society of Pharmacogenomics (ISP) at Santorini, Greece. The participants, members of the ISP Pharmacogenomics Education Forum, after deliberate discussions, proposed a document of 'Background Statement' and 'Recommendations and Call for Action' addressed to Deans of Education at Medical, Pharmaceutical, and Health Schools globally. This document has been considered by the education committee of the International Society of Pharmacogenomics and the result is presented here. We hope that this call would be listened to, and soon followed by beneficial action, ultimately leading to enhanced implementation of personalized medicine into core medical education and practice.

Quantitative measurements of mouse brain thrombin-like and thrombin inhibition activities.

Thrombin-like enzymatic activity was measured in mouse brain homogenates and slices by cleavage of a peptide substrate, N-p-Tosyl-Gly-Pro-Arg-7-amido-4-methylcoumarin. The activity was localized mainly to white matter. However, it was not affected by specific thrombin inhibitors, and was found to represent the sum of at least two enzyme activities, a prolyl endopeptidase and an aminopeptidase. By specifically inhibiting this endogenous activity in combination with exogenously added thrombin, mouse brain tissue was shown to express a capacity of thrombin inhibitory activity equivalent to 0.2 mU thrombin/mg brain tissue. The present study offers a simple and reliable method for measuring total thrombin inhibitory activity in brain.