Does the imbalance in the apolipoprotein E isoforms underlie the pathophysiological process of sporadic Alzheimer's disease?

Human apolipoprotein E (apoE) is a 299-amino acid secreted glycoprotein binding cholesterol and phospholipids, and with three common isoforms (APOE ε2, APOE ε3, and APOE ε4). The exact mechanism by which APOE gene variants increase/decrease Alzheimer's disease (AD) risk is not fully understood, but APOE isoforms differently affect brain homeostasis and neuroinflammation, blood-brain barrier (BBB) permeability, glial function, synaptogenesis, oral/gut microbiota, neural networks, amyloid beta (Aß) deposition, and tau-mediated neurodegeneration. In this perspective, we propose a comprehensive interpretation of APOE-mediated effects within AD pathophysiology, describing some specific cellular, biochemical, and epigenetic mechanisms and updating the different APOE-targeting approaches being developed as potential AD therapies. Intracisternal adeno-associated viral-mediated delivery of APOE ε2 is being tested in AD APOE ε4/ε4 carriers, while APOE mimetics are being used in subjects with perioperative neurocognitive disorders. Other approaches including APOE ε4 antisense oligonucleotides, anti-APOE ε4 monoclonal antibodies, APOE ε4 structure correctors, and APOE-Aß interaction inhibitors produced positive results in transgenic AD mouse models.

Italian Case Report with a Double Mutation in PSEN1 (K311R and E318G).

Alzheimer's disease (AD) is the most common cause of dementia worldwide. The clinical spectrum of suspected AD has been extended from mild cognitive impairment (MCI) to preclinical AD which includes people who have typical cognitive function but harbor the underlying biological features of AD. We report the first case of an Italian patient affected by MCI (MMSE 24\30), characterized by a double mutation p.Lys311Arg (K311R) and p.Glu318Gly (E318G) in Presenilin-1 but with the absence of abnormal accumulation of amyloid beta.

Are apolipoprotein E fragments a promising new therapeutic target for Alzheimer's disease?

Human apolipoprotein E (ApoE) is a 299-amino acid secreted glycoprotein that binds cholesterol and phospholipids. ApoE exists as three common isoforms (ApoE2, ApoE3, and ApoE4) and heterozygous carriers of the ε4 allele of the gene encoding ApoE (APOE) have a fourfold greater risk of developing Alzheimer's disease (AD). The enzymes thrombin, cathepsin D, α-chymotrypsin-like serine protease, and high-temperature requirement serine protease A1 are responsible for ApoE proteolytic processing resulting in bioactive C-terminal-truncated fragments that vary depending on ApoE isoforms, brain region, aging, and neural injury. The objectives of the present narrative review were to describe ApoE processing, discussing current hypotheses about the potential role of various ApoE fragments in AD pathophysiology, and reviewing the current development status of different anti-ApoE drugs. The exact mechanism by which APOE gene variants increase/decrease AD risk and the role of ApoE fragments in the deposition are not fully understood, but APOE is known to directly affect tau-mediated neurodegeneration. ApoE fragments co-localize with neurofibrillary tangles and amyloid ß (Aß) plaques, and may cause neurodegeneration. Among anti-ApoE approaches, a fascinating strategy may be to therapeutically overexpress ApoE2 in APOE ε4/ε4 carriers through vector administration or liposomal delivery systems. Another approach involves reducing ApoE4 expression by intracerebroventricular antisense oligonucleotides that significantly decreased Aß pathology in transgenic mice. Differences in the proteolytic processing of distinct ApoE isoforms and the use of ApoE fragments as mimetic peptides in AD treatment are also under investigation. Treatment with peptides that mimic the structural and biological properties of native ApoE may reduce Aß deposition, tau hyperphosphorylation, and glial activation in mouse models of Aß pathology. Alternative strategies involve the use of ApoE4 structure correctors, passive immunization to target a certain form of ApoE, conversion of the ApoE4 aminoacid sequence into that of ApoE3 or ApoE2, and inhibition of the ApoE-Aß interaction.

A New Presenilin 1 (Psen1) Mutation (p.Cys263Trp) as a Cause of Both Early and Late-Onset Alzheimer's Disease in a Large Italian Family.

Mutations in the PSEN1 gene are the most common cause of autosomal dominant Alzheimer's disease, and are characterized by a high phenotype variability. This study describes a five-generation family, with a prevalent late-onset of the disease and a high frequency of depression, in which a new missense mutation (c.789T > G, p.Cys263Trp) in exon 8 of the PSEN1 gene was found. Only the proband presented an early onset at the age of 45 with attention deficit, followed by spatial disorientation, psychiatric symptoms and parkinsonian signs. The other two cases had a late onset of the disease and a typical presentation with memory loss. Both were characterized by a high level of anxiety and depression. The disease course was different with signs of Lewy body dementia for the proband's mother, and pyramidal involvement and a shorter disease duration for the proband's maternal aunt. The other eight cases with late-onset dementia and three cases with a long history of depression have been reported in the family pedigree, underlying the high phenotype variability of PSEN1 mutations.

A 14-Year Italian Experience in DM2 Genetic Testing: Frequency and Distribution of Normal and Premutated CNBP Alleles.

Myotonic dystrophy type 2 (DM2) is a multisystemic disorder caused by a (CCTG) n in intron 1 of the CNBP gene. The CCTG repeat tract is part of a complex (TG) v (TCTG) w (CCTG) x (NCTG) y (CCTG) z motif generally interrupted in CNBP healthy range alleles. Here we report our 14-year experience of DM2 postnatal genetic testing in a total of 570 individuals. The DM2 locus has been analyzed by a combination of SR-PCR, TP-PCR, LR-PCR, and Sanger sequencing of CNBP alleles. DM2 molecular diagnosis has been confirmed in 187/570 samples analyzed (32.8%) and is mainly associated with the presence of myotonia in patients. This set of CNBP alleles showed unimodal distribution with 25 different alleles ranging from 108 to 168 bp, in accordance with previous studies on European populations. The most frequent CNBP alleles consisted of 138, 134, 140, and 136 bps with an overall locus heterozygosity of 90%. Sequencing of 103 unexpanded CNBP alleles in DM2-positive patients revealed that (CCTG)5(NCTG)3(CCTG)7 and (CCTG)6(NCTG)3(CCTG)7 are the most common interruption motifs. We also characterized five CNBP premutated alleles with (CCTG) n repetitions from n = 36 to n = 53. However, the molecular and clinical consequences in our cohort of samples are not unequivocal. Data that emerged from this study are representative of the Italian population and are useful tools for National and European centers offering DM2 genetic testing and counseling.

Pharmacogenetics in the clinical analysis laboratory: clinical practice, research, and drug development pipeline.

Introduction: Over the last decade, the spread of next-generation sequencing technology along with the rising cost in health management in national health systems has led to widespread use/abuse of pharmacogenetic tests (PGx) in the practice of many clinical disciplines. However, given their clinical significance, it is important to standardize these tests for having an interaction with the clinical analysis laboratory (CAL), in which a PGx service can meet these requirements. Areas covered: A diagnostic test must meet the criteria of reproducibility and validity for its utility in the clinical routine. This present review mainly describes the utility of introducing PGx tests in the CAL routine to produce correct results useful for setting up personalized drug treatments. Expert opinion: With a PGx service, CALs can provide the right tool to help clinicians to make better choices about different categories of drugs and their dosage and to manage the economic impact both in hospital-based settings and in National Health Services, throughout electronic health records. Advances in PGx also allow a new approach for pharmaceutical companies in order to improve drug development and clinical trials. As a result, CALs can achieve a powerful source of epidemiological, clinical, and research findings from PGx tests.

Understanding the Amyloid Hypothesis in Alzheimer's Disease.

The amyloid hypothesis (AH) is still the most accepted model to explain the pathogenesis of inherited Alzheimer's disease (IAD). However, despite the neuropathological overlapping with the non-inherited form (NIAD), AH waver in explaining NIAD. Thus, 30 years after its first statement several questions are still open, mainly regarding the role of amyloid plaques (AP) and apolipoprotein E (APOE). Accordingly, a pathogenetic model including the role of AP and APOE unifying IAD and NIAD pathogenesis is still missing. In the present understanding of the AH, we suggested that amyloid-ß (Aß) peptides production and AP formation is a physiological aging process resulting from a systemic age-related decrease in the efficiency of the proteins catabolism/clearance machinery. In this pathogenetic model Aß peptides act as neurotoxic molecules, but only above a critical concentration [Aß]c. A threshold mechanism triggers IAD/NIAD onset only when [Aß]≥[Aß]c. In this process, APOE modifies [Aß]c threshold in an isoform-specific way. Consequently, all factors influencing Aß anabolism, such as amyloid beta precursor protein (APP), presenilin 1 (PSEN1), and presenilin 2 (PSEN2) gene mutations, and/or Aß catabolism/clearance could contribute to exceed the threshold [Aß]c, being characteristic of each individual. In this model, AP formation does not depend on [Aß]c. The present interpretation of the AH, unifying the pathogenetic theories for IAD and NIAD, will explain why AP and APOE4 may be observed in healthy aging and why they are not the cause of AD. It is clear that further studies are needed to confirm our pathogenetic model. Nevertheless, our suggestion may be useful to better understand the pathogenesis of AD.

Hydroxytryptamine transporter gene-linked polymorphic region (5HTTLPR) is associated with delusions in Alzheimer's disease.

BACKGROUND: Serotoninergic pathways underlying delusion symptoms in Alzheimer's disease (AD) have not been fully clarified. 5-Hydroxytryptamine transporter gene-linked polymorphic region (5-HTTLPR) is a variable number tandem repeats in the promoter region of serotonin transporter encoding-gene affecting transcription. METHODS: We investigated the association of 5-HTTLPR with delusions in a total of 257 consecutive patients clinically diagnosed as AD according to the National Institute on Aging-Alzheimer's Association criteria. All participants underwent a comprehensive evaluation with a standardized comprehensive geriatric assessment and Neuropsychiatric Inventory. RESULTS: Delusion symptoms were observed in 171 patients (66.54%). In respect to AD patients without delusions, AD patients with delusions showed a low prevalence of S-plus carriers (5-HTTLPR-L/S + 5-HTTLPR-S/S genotypes) [p < 0.001; odds ratio (OR) = 0.240, 95% confidence interval (CI) = 0.121-0.471]. Logistic regression analysis adjusted for the apolipoprotein E polymorphism showed that in AD patients with delusions the presence of an 5-HTTLPR-S allele may reduce disease duration (p = 0.005; OR = 0.680, 95% CI = 0.522-0.886) and increase aberrant motor activity (p = 0.013; OR = 2.257, 95% CI = 1.195-4.260). The present findings suggested that 5-HTTLPR might be associated with delusions in AD. S-plus carriers might be associated with protective effect against delusions in AD. CONCLUSIONS: More studies on wider samples of high selected demented patients are needed to confirm our results. However, the present findings suggested that a genetic factor related to serotonin metabolism might exert a protective role on the clinical expression of neuropsychiatric clusters in AD with important implications regarding mechanisms underlying delusions and their possible treatment across the AD and dementia spectrum.

Standardization of red flags for referral to rheumatologists and ophthalmologists in patients with rheumatic diseases and ocular involvement: a consensus statement.

Ocular involvement is a common manifestation of inflammatory rheumatic diseases, often requiring a multidisciplinary collaboration between rheumatologists and ophthalmologists. The aim of this study was to standardize "red flags" for referral for rheumatologists and ophthalmologists using a Delphi consensus for the management of rheumatic diseases with ocular involvement. The scientific board comprised 11 Italian hospital-based rheumatologists (N = 6) and ophthalmologists (N = 5). A systematic review identified potential red flags for referral. The panel developed 19 statements consisting of (a) referral from ophthalmologist to rheumatologist (b) referral from rheumatologist to ophthalmologist and (c) overarching principles relating to multidisciplinary roles/goals and management. Voting was performed anonymously using an online Delphi method. Each participant expressed a level of agreement on each statement using a 5-point scale (1="strongly disagree"; 5="strongly agree"). Total cumulative agreement was defined as the sum of the percentage of response to items 4 ("agree") and 5 ("absolutely agree"), consensus defined as ≥ 80% cumulative agreement for each statement. Positive consensus among 11 participants was reached for 15/19 (78.9%) statements. Statements not reaching consensus were discussed in a face-to-face meeting prior to the second vote (10 participants). Positive consensus was reached for all 19 statements, with final total cumulative agreement of 90-100%. This is the first Delphi consensus undertaken to standardize red flags for referral to rheumatologists and ophthalmologists for patients with rheumatic diseases and ocular involvement.

The potential of solanezumab and gantenerumab to prevent Alzheimer's disease in people with inherited mutations that cause its early onset.

INTRODUCTION: The recent failure of several clinical trials on anti-ß-amyloid (Aß) drugs in Alzheimer's disease (AD) suggested earlier intervention in the disease course. Secondary prevention trials have been started in autosomal-dominant AD (ADAD) individuals without cognitive dysfunction and in cognitively healthy subjects at risk of developing sporadic AD (SAD). AREAS COVERED: Herein, the authors discuss prevention trials in ADAD and SAD, with a focus on the anti-Aß monoclonal antibodies solanezumab and gantenerumab presently in Phase III clinical development. These therapies are also being tested in the Dominantly Inherited Alzheimer's Network Trials Unit (DIAN-TU). EXPERT OPINION: Anti-Aß monoclonal antibodies are being tested in subjects at the preclinical stage of ADAD and even in symptom-free subjects at risk of developing SAD. The subsequent DIAN-TU Adaptive Prevention Trial is a 4-year study that will assess whether such biomarker effects may stop the progress of the AD process, preventing cognitive symptoms. The hope is to interfere in the disease course when it is not too late. A clinical success of these prevention trials would represent the proof of the Aß hypothesis of AD.

Role of CLU, PICALM, and TNK1 Genotypes in Aging With and Without Alzheimer's Disease.

Healthy and impaired cognitive aging may be associated to different prevalences of single-nucleotide polymorphisms (SNPs). In a multicenter case-control association study, we studied the SNPs rs11136000 (clusterin, CLU), rs541458 (phosphatidylinositol binding clatrin assembly protein, PICALM), and rs1554948 (transcription factor A, and tyrosine kinase, non-receptor, 1, TNK1) according to the three age groups 50-65 years (group 1), 66-80 years (group 2), and 80+ years (group 3) in 569 older subjects without cognitive impairment (NoCI) and 520 Alzheimer's disease (AD) patients. In NoCI subjects, a regression analysis suggested a relationship between age and TNK1 genotypes, with the TNK1-A/A genotype frequency that increased with higher age, and resulting in a different distribution of the TNK1-A allele. In AD patients, a regression analysis suggested a relationship between age and PICALM genotypes and TNK1 genotypes, with the PICALM-T/C and TNK1-A/A genotype frequencies that decreased with increasing age. A resulting difference in the distribution of PICALM-C allele and TNK1-A allele was also observed. The TNK1-A allele was overrepresented in NoCI subjects than in AD patients in age groups 2 and 3. These results confirmed after adjustment for apolipoprotein E polymorphism, which suggested a different role of PICALM and TNK1 in healthy and impaired cognitive aging. More studies, however, are needed to confirm the observed associations.

Psychotropic drugs and CYP2D6 in late-life psychiatric and neurological disorders. What do we know?

INTRODUCTION: Late-life psychiatric and neurological disorders (LLPND) are interesting models to understand the potential role of pharmacogenetics in drug management, since several pharmacological approaches for treating LLPND have proven to be ineffective or deleterious, thus resulting in therapeutic failures (TF) and adverse drug reactions (ADR). Common variants in the genes encoding the cytochrome P450 (CYP) enzyme system, the 'engine room' of drug metabolism, together with well-known age-related increased polypharmacy also contributed to the prevalence of TF and ADR observed in these patients, also rising number and time of hospital readmissions and rate of institutionalizations. Areas covered: The genetics of CYP and how it may be used for the management of the outcomes of the most frequent drugs (antidepressants, antipsychotics, anticholinesterase inhibitors, and anxiolytics) used in LLPND. Expert opinion: Tailored CYP-based pharmacological treatments of LLPND will reduce TFs and ADRs, improving patient's life, reducing number and dosage of administered drugs, and the number and duration of hospital readmissions, saving costs for clinical management of LLPND. Pharmacokinetic interactions are less predictable than pharmacodynamic ones and several requests are made to regulatory organisms for the pharmacological management of frail older patients affected by LLPND.

Innovative biomarkers in psychiatric disorders: a major clinical challenge in psychiatry.

INTRODUCTION: Currently, the diagnosis of psychiatric illnesses is based upon DSM-5 criteria. Although endophenotype-specificity for a particular disorder is discussed, the identification of objective biomarkers is ongoing for aiding diagnosis, prognosis, or clinical response to treatment. We need to improve the understanding of the biological abnormalities in psychiatric illnesses across conventional diagnostic boundaries. The present review investigates the innovative post-genomic knowledge used for psychiatric illness diagnostics and treatment response, with a particular focus on proteomics. Areas covered: This review underlines the contribution that psychiatric innovative biomarkers have reached in relation to diagnosis and theragnosis of psychiatric illnesses. Furthermore, it encompasses a reliable representation of their involvement in disease through proteomics, metabolomics/pharmacometabolomics and lipidomics techniques, including the possible role that gut microbiota and CYP2D6 polimorphisms may play in psychiatric illnesses. Expert opinion: Etiologic heterogeneity, variable expressivity, and epigenetics may impact clinical manifestations, making it difficult for a single measurement to be pathognomonic for multifaceted psychiatric disorders. Academic, industry, or government's partnerships may successfully identify and validate new biomarkers so that unfailing clinical tests can be developed. Proteomics, metabolomics, and lipidomics techniques are considered to be helpful tools beyond neuroimaging and neuropsychology for the phenotypic characterization of brain diseases.

Pharmacogenetics of neurological and psychiatric diseases at older age: has the time come?

INTRODUCTION: In recent years, a number of pharmacological approaches for treating neuropsychiatric conditions at older age have proven to be inadequate. The resulting increased prevalence of therapeutic failures (TF) and a worsening of clinical symptoms often linked to adverse reactions (ADRs), are perhaps among the major causes of the increasing rate of hospitalizations and institutionalizations observed in these patients. Areas covered: This review underlines the importance of pharmacogenetic data to fingerprint the pharmacological treatment of neuropsychiatric late-life conditions throughout the analysis of metabolizing enzymes and transporters of psychotropic drugs, mainly those of the cytochrome P450 (CYP) family. Pharmacodynamic response measures as treatment effects mediated through targets (i.e., receptors in the brain) may also contribute to this image. Expert opinion: CYP genetics is the basis of a continuum on which environmental and physiological factors act, modeling the phenotype observed in clinical practice with advancing age. Furthermore, other specific polymorphic genes influence drug response through differential effects of their functional genetic variants. The known genotypes associated with an altered metabolizer status and drug transporters may help clinical decision-making to avoid concomitant treatments, reduce therapeutic attempts and increase drug safety in neuropsychiatric conditions in older age, after controlling for other clinical variables.

Emerging drugs to reduce abnormal ß-amyloid protein in Alzheimer's disease patients.

INTRODUCTION: Currently available drugs against Alzheimer's disease (AD) target cholinergic and glutamatergic neurotransmissions without affecting the underlying disease process. Putative disease-modifying drugs are in development and target ß-amyloid (Aß) peptide and tau protein, the principal neurophatological hallmarks of the disease. Areas covered: Phase III clinical studies of emerging anti-Aß drugs for the treatment of AD were searched in US and EU clinical trial registries and in the medical literature until May 2016. Expert opinion: Drugs in Phase III clinical development for AD include one inhibitor of the ß-secretase cleaving enzyme (BACE) (verubecestat), three anti-Aß monoclonal antibodies (solanezumab, gantenerumab, and aducanumab), an inhibitor of receptor for advanced glycation end products (RAGE) (azeliragon) and the combination of cromolyn sodium and ibuprofen (ALZT-OP1). These drugs are mainly being tested in subjects during early phases of AD or in subjects at preclinical stage of familial AD or even in asymptomatic subjects at high risk of developing AD. The hope is to intervene in the disease process when it is not too late. However, previous clinical failures with anti-Aß drugs and the lack of fully understanding of the pathophysiological role of Aß in the development of AD, put the new drugs at substantial risk of failure.