Graphical abstract

Environmental enrichment (EE) is a non-pharmacological intervention reported to counteract pathological signs in models of Alzheimer's disease (AD). We developed EE protocols in APP23 mice and evaluated how they influenced cognitive decline and brain amyloid-β (Aβ) burden. We also investigated the involvement of sirtuins (SIRTs) as a possible molecular mediator of EE, by assessing hippocampal and cortical mRNA and protein levels of the SIRT family members (SIRT1 to SIRT7). APP23 transgenic mice were moved to EE cages (TG-EEs) starting from 3 months of age. TG-EEs were compared to transgenic mice housed in standard cages (TG-SHs) and to wild-type littermates in the two housing conditions (WT-EEs and WT-SHs). At 7 months of age, all mice were tested for behavioral performance with Morris Water Maze (MWM) and visual novel Object Recognition Test (vORT). After a month, a group underwent biochemical analyses, while another group continued in the EE environment till 18 months of age, when Aβ plaque load was assessed. At 7 months, TG-SHs had impaired behavioral performance in MWM and vORT. In contrast, TG-EE mice had restored behavioral performance. At 8 months, EE did not affect AβPP expression or processing, Aβ40/42, pGlu-Aβ3-40/3-42, or Aβ oligomer level. The expression of two Aβ degrading enzymes (insulin degrading enzyme and neprilysin) was not modulated by EE. Brain sirtuin mRNA and protein levels were unchanged, while brain-derived neurotrophic factor expression increased after EE. Aβ deposition was attenuated in 18-month-old TG-EE mice, without apparent reduction of neuroinflammatory signs. We suggest that EE had a beneficial effect on cognitive performance and lessened long-term Aβ accumulation, but brain sirtuin expression was not modulated when cognitive impairment was restored.

Among the several genes associated with late-onset Alzheimer's disease (LOAD), recently, Sirtuin genes have roused a growing interest because of their involvement in metabolic homeostasis and in brain aging. Particularly SIRT2 gene has been associated with Alzheimer's disease (AD) as well as with mood disorders. The aim of this study is to investigate the possible associations between Sirtuin 2 gene (SIRT2) rs10410544 polymorphism and AD as well as depression in AD. In addition, we performed some exploratory analyses to investigate possible associations between the rs10410544 genotype and clinical features. We investigated these associations in two independent samples: the first one was composed of 275 Greek inhabitants and 117 patients; the second sample counted 181 Italian people and 43 patients. All patients were affected by LOAD. We failed to find any association between rs10410544 genotype and AD in the two samples. On the other hand, we found an association between the single nucleotide polymorphism (SNP) and depressive symptomatology (in the total sample p = 0.002), which was modulated by the tumor necrosis factor (TNF) values. Particularly, TT genotype seems to be protective versus depression. Finally, in the exploratory analyses, we found that the TT genotype was associated with earlier AD onset and a longer duration of the illness. In conclusion, we confirmed the association between SIRT2 gene and mood disturbances, although in AD patients. Further, we provided evidence that the TT genotype may be protective versus depressive symptoms, allowing an easier and thus earlier diagnosis of AD. This awareness may lead to a more detailed approach to these patients concerning diagnosis and therapy.

Antidepressant pharmacogenetics represents a stimulating, but often discouraging field. The present study proposes a combination of several methodologies across three independent samples. Genes belonging to monoamine, neuroplasticity, circadian rhythm and transcription factor pathways were investigated in two samples (n=369 and 88) with diagnosis of major depression who were treated with antidepressants. Phenotypes were response, remission and treatment-resistant depression. Logistic regression including appropriate covariates was performed. Genes associated with outcomes were investigated in the STAR*D (Sequenced Treatment Alternatives to Relieve Depression) genome-wide study (n=1861). Top genes were further studied through a pathway analysis. In both original samples, markers associated with outcomes were concentrated in the PPP3CC gene. Other interesting findings were particularly in the HTR2A gene in one original sample and the STAR*D. The B-cell receptor signaling pathway proved to be the putative mediator of PPP3CC's effect on antidepressant response (P=0.03). Among innovative candidates, PPP3CC, involved in the regulation of immune system and synaptic plasticity, seems promising for further investigation.

Mucopolysaccharidoses (MPSs) are lysosomal storage diseases (LSDs) caused by defects in lysosomal enzymes involved in the catabolism of glycosaminoglycans. The pathogenesis of these disorders is still not completely known, although inflammation and oxidative stress appear to be common mechanisms, as in all LSDs. Recently, it was hypothesized that endoplasmic reticulum (ER) stress followed by an unfolded protein response (UPR) could be another common pathogenetic mechanism in LSDs. The aim of the present study was to verify if the UPR was elicited in the mucopolysaccharidoses and if the mechanism was MPS type- and mutation-dependent. To this end, we analyzed the UPR in vitro, in fibroblasts from patients with different types of mucopolysaccharidoses (MPS I, II, IIIA, IIIB, IVA) and in vivo, in the murine MPS IIIB model. In both cases we found no changes in mRNA levels of several UPR-related genes, such as the spliced or unspliced form of Xbp-1, Bip, Chop, Edem1, Edem2, Edem3. Therefore, we report here that the unfolded protein response of the ER is not triggered either in vitro or in vivo; accordingly, cytotoxicity assays indicated that affected fibroblasts are no more sensitive to apoptosis induction than normal cells. However, our results show that in most of the analyzed MPS fibroblasts the expression of a poorly known protein belonging to the family of the protein disulfide isomerases, namely Pdia5, is upregulated; here we discuss if its upregulation could be an early event of ER stress possibly related to the severity of the damage induced in the mutant proteins.

Apparent homozygosity for the mutation p.R315X present on exon 5 of the arylsulfatase B (ARSB) gene in a mucopolysaccharidosis type VI patient was solved in this study by further testing for a second mutation. Patient cDNA analysis revealed that the entire exon 5 of the ARSB gene was lacking; this new mutation was identified as c.899-1142del. As the genomic DNA sequencing excluded the presence of splicing mutations, polymerase chain reaction analysis was performed for polymorphisms listed in the NCBI SNP database for the ARSB gene. This allowed the mutation at the genomic DNA level to be identified as g.99367-102002del; this gross deletion, involving the entire exon 5 of the gene and parts of introns 4 and 5 led to a frameshift starting at amino acid 300 and resulting in a protein with 39% amino acids different from the normal enzyme. We stress that extensive DNA analysis needs to be performed in case of apparent homozygosity to avoid potential errors in genetic counseling.

Amyotrophic lateral sclerosis (ALS) is a multifactorial disease, possibly with contributions from genetics and lifestyle. We examined variants in genes relevant to energy metabolism and physical activity in a case-control association study, with the aim of assessing genetics and physical activity as contributors to ALS risk. A well-characterized sample of Italian ALS patients (101) and controls (101) from the EURALS Consortium underwent a questionnaire interview on demographic, physical and other lifestyle habits, and venipuncture for DNA extraction. The genes selected were sirtuin 3 (SIRT3), peroxisome proliferator-activated receptor-γ coactivator-1α (PPARGC1A) and apolipoprotein E (APOE). Genetic studies suggested, for the first time, a protective role of the SIRT3 single-nucleotide polymorphism rs4980329 in ALS risk, and a contribution of the APOE-ε2 allele, which was more frequent in ALS patients than in controls. A joint analysis coupling genetic data and sporting activity revealed opposite roles of APOE-ε2 and SIRT3 rs3825075, the former being more frequent in physically active ALS patients and the latter more frequent in physically inactive patients. These findings suggest a contribution to ALS risk of genetic and environmental factors involved in energy metabolism, and stress the importance of a multifactorial analysis for evaluating this risk.

The treatment of bipolar disorder (BD) usually requires combination therapies, with the critical issue of the emergence of adverse drug reactions (ADRs) and the possibility of low treatment adherence. Genetic polymorphisms are hypothesized to modulate the pharmacodynamics of psychotropic drugs, representing potential biological markers of ADRs. This study investigated genes involved in the regulation of neuroplasticity (BDNF, ST8SIA2), second messenger cascades (GSK3B, MAPK1, and CREB1), circadian rhythms (RORA), transcription (SP4, ZNF804A), and monoaminergic system (HTR2A and COMT) in the risk of neurological, psychic, autonomic, and other ADRs. Two independent samples of BD patients naturalistically treated were included (COPE-BD n = 147; STEP-BD n = 659). In the COPE-BD 34 SNPs were genotyped, while in the STEP-BD polymorphisms in the selected genes were extracted from the genome-wide dataset. Each ADRs group was categorized as absent-mild or moderate-severe and logistic regression with appropriate covariates was applied to identify possible risk genotypes/alleles. 58.5 and 93.5 % of patients were treated with mood stabilizers, 44.2 and 50.7 % were treated with antipsychotics, and 69.4 and 46.1 % were treated with antidepressants in the COPE-BD and STEP-BD, respectively. Our findings suggested that ST8SIA2 may be associated with psychic ADRs, as shown in the COPE-BD (rs4777989 p = 0.0017) and STEP-BD (rs56027313, rs13379489 and rs10852173). A cluster of RORA SNPs around rs2083074 showed an effect on psychic ADRs in the STEP-BD. Trends supporting the association between HTR2A and autonomic ADRs were found in both samples. Confirmations are needed particularly for ST8SIA2 and RORA since the few available data regarding their role in relation to psychotropic ADRs.