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Gianluigi Forloni

Publications and source records attributed to Gianluigi Forloni.

At least 19 recordsLinked to original sources
PubMed2006

The urokinase-type plasminogen activator polymorphism PLAU_1 is a risk factor for APOE-epsilon4 non-carriers in the Italian Alzheimer's disease population and does not affect the plasma Abeta(1-42) level.

Sporadic Alzheimer's disease (AD) is the most frequent form of dementia in the elderly. A non-conservative polymorphism in the urokinase-type plasminogen activator gene (PLAU_1=RS2227564) has been analyzed, but data are conflicting on whether it is a risk factor for AD. To clarify whether this genetic variant modifies AD risk in the Italian population, we ran a case-control association study on 192 AD and 126 age-matched controls. We did not find any association between PLAU_1 genotype and AD in the whole AD population, but when we stratified our sample by APOE-epsilon4 status, we found a significant association between PLAU_1 genotype (C/T+T/T) and APOE-epsilon4 negative AD subjects (p=0.02, chi(2)-test). The PLAU_1 genotype did not appear to affect the plasma Abeta42 concentration. Our data support a role for PLAU_1 as an independent genetic risk factor for AD in the Italian population for those subjects who do not have the APOE-epsilon4 allele.

Aged↗
PubMed2006

Absence of TREM2 polymorphisms in patients with Alzheimer's disease and Frontotemporal Lobar Degeneration.

Triggering Receptor Expressed on Myeloid cells (TREM)2 deficiency originates a genetic syndrome characterized by bone cysts and presenile dementia, named Nasu-Hakola disease (NHD). Early onset dementia and marked involvement of frontal regions are features characterizing both NHD and other kinds of neurodegenerative disorders, such as Frontotemporal Lobar Degeneration (FTLD), and, in some cases, Alzheimer's disease (AD). Three Single Nucleotide Polymorphisms (SNPs) in TREM2 coding region were screened by allelic discrimination in a population of probable AD patients as well as FTLD patients as compared with age-matched controls. In addition, mutation scanning of the coding region of TREM2 gene was carried out in 7 patients with early onset AD (EOAD), 16 FTLD, and 20 controls. None of the SNPs analyzed was present, either in patients or controls. Moreover, mutation scanning of the five exons of TREM2 failed to detect the presence of novel polymorphisms. These data demonstrate that TREM2 coding region is highly conserved, implying a crucial role of this receptor. Further studies, including a functional analysis, are certainly required to clarify the role of TREM2 in neurodegenerative processes.

Aged↗
PubMed2006

Presenilin-1 mutation E318G and familial Alzheimer's disease in the Italian population.

Presenilin-1 (PSEN-1) is a component of the gamma-secretase complex involved in beta-amyloid precursor protein (betaAPP) processing. To date about 140 pathogenic mutations in the PSEN-1 gene have been identified and their main biochemical effect is to increase the production of the fibrillogenic peptide Abeta(1-42). An exception is the PSEN-1 [E318G] mutation that does not alter Abeta(1-42) generation and is generally considered a non-pathogenic polymorphism. Nevertheless, this mutation was reported to be a genetic risk factor for familial Alzheimer's disease (FAD) in the Australian population. To independently confirm this indication, we performed a case-control association study in the Italian population. We found a significant association (p<0.05, Fisher's exact test) between the presence of PSEN-1 [E318G] and FAD. In addition, on measuring the Abeta(1-42) and Abeta(1-40) concentrations in fibroblast-conditioned media cultured from PSEN-1 [E318G] carriers and PSEN-1 [wild type] controls we noted a significant decrease (p<0.05, Mann-Whitney test) in the Abeta(1-42)/Abeta(1-40) ratio in PSEN-1 [E318G] carriers, suggesting a peculiar biochemical effect of this mutation.

Aged↗
PubMed2006

Interleukin-1 alpha and beta, TNF-alpha and HTTLPR gene variants study on alcohol toxicity and detoxification outcome.

Genetic factors may influence the liability to treatment outcome and medical complications in alcoholism. In the present study we investigated the IL-1A rs1800587, IL-1B rs3087258, TNF-alpha rs1799724 and the HTTLPR variants in a sample of 64 alcohol dependents and 47 relatives versus a set of clinical parameters and outcome measures. Alcohol dependents had a less favorable clinical profile compared to relatives (higher cholesterol, triglycerides, glucose, glutamic oxaloacetic transaminase, glutamic pyruvic transaminase, gamma-glutamyltransferase). After detoxification, all clinical indexes improved and hepatic enzyme levels were similar in alcohol dependents and relatives, except for the GGT that remained significantly higher in alcohol dependents. Alcoholic depressive and anxiety scores were significantly reduced after detoxification. IL-1A, IL-1B, TNF-alpha and HTTLPR variants were not associated with any baseline clinical index or change after detoxification. In our sample IL-1A, IL-1B, TNF-alpha and HTTLPR do not appear as liability factors for alcohol toxicity or detoxification outcome, however the small sample size may influence the observed results.

Adult↗
PubMed2006

Candidate gene analysis of IP-10 gene in patients with Alzheimer's disease.

Interferon-gamma-inducible Protein-10 (IP-10) is supposed to play a role in Alzheimer's disease (AD) development, as demonstrated by increased levels in cerebrospinal fluid from patients with AD. A mutation scanning of IP-10 exonic region was carried out in 10 patients with AD and 10 age-matched controls, demonstrating the presence of two previously reported single nucleotide polymorphisms (SNPs) in exon 4 (G-->C and T-->C) as well as a novel SNP in exon 2 (C-->T). Exon 4 G-->C and T-->C allelic variants were next evaluated in a population of 279 AD patients and 251 controls, in order to determine whether their presence could influence the susceptibility towards the development of the disease. These two SNPs were in complete linkage disequilibrium. No differences in haplotype frequencies were found in AD patients as compared with controls, even stratifying according to the presence of Apolipoprotein E varepsilon4 allele, gender or age at onset. A new protocol was developed to easily determine the C-->T SNP in exon 2. A preliminary analysis revealed a very low frequency of this allelic variant (1%). Therefore, the complete association study was not carried out because the size of our population was not sufficient to draw reliable conclusions. According to these results, IP-10 does not seem to be a risk factor for AD. However, a novel rare polymorphism has been identified, which could exert a role in AD susceptibility. Thus, further studies on larger populations are needed before confidently excluding IP-10 as a susceptibility gene for AD.

Age of Onset↗
PubMed2006

Aggregation/fibrillogenesis of recombinant human prion protein and Gerstmann-Sträussler-Scheinker disease peptides in the presence of metal ions.

In this study we investigated the role of Cu(2+), Mn(2+), Zn(2+), and Al(3+) in inducing defective conformational rearrangements of the recombinant human prion protein (hPrP), which trigger aggregation and fibrillogenesis. The research was extended to the fragment of hPrP spanning residues 82-146, which was identified as a major component of the amyloid deposits in the brain of patients affected by Gerstmann-Sträussler-Scheinker (GSS) disease. Variants of the 82-146 wild-type subunit [PrP-(82-146)(wt)] were also examined, including entirely, [PrP-(82-146)(scr)], and partially scrambled, [PrP-(82-146)(106)(-)(126scr)] and [PrP-(82-146)(127)(-)(146scr)], peptides. Al(3+) strongly stimulated the conversion of native hPrP into the altered conformation, and its potency in inducing aggregation was very high. Despite a lower rate and extent of prion protein conversion into altered isoforms, however, Zn(2+) was more efficient than Al(3+) in promoting organization of hPrP aggregates into well-structured, amyloid-like fibrillar filaments, whereas Mn(2+) delayed and Cu(2+) prevented the process. GSS peptides underwent the fibrillogenesis process much faster than the full-length protein. The intrinsic ability of PrP-(82-146)(wt) to form fibrillar aggregates was exalted in the presence of Zn(2+) and, to a lesser extent, of Al(3+), whereas Cu(2+) and Mn(2+) inhibited the conversion of the peptide into amyloid fibrils. Amino acid substitution in the neurotoxic core (sequence 106-126) of the 82-146 fragment reduced its amyloidogenic potential. In this case, the stimulatory effect of Zn(2+) was lower as compared to the wild-type peptide; on the contrary Al(3+) and Mn(2+) induced a higher propensity to fibrillation, which was ascribed to different binding modalities to GSS peptides. In all cases, alteration of the 127-146 sequence strongly inhibited the fibrillogenesis process, thus suggesting that integrity of the C-terminal region was essential both to confer amyloidogenic properties on GSS peptides and to activate the stimulatory potential of the metal ions.

Amino Acid Sequence↗
PubMed2006

Plasma levels of beta-amyloid (1-42) in Alzheimer's disease and mild cognitive impairment.

We compared plasma levels of beta-amyloid 1-42 (pg/ml) found for 146 sporadic Alzheimer (AD) patients, 89 subjects with mild cognitive impairment (MCI) and 89 age-matched controls (CT). AD patients had significantly lower levels (38, 54, 52; p<0.01), unrelated to severity of the disease as assessed by MMSE score, age, sex or APOE4 status. Twenty cases investigated at two time points 18 months apart did not demonstrate further decreases. Thus, the reduction in beta-amyloid 1-42 may be a marker for AD status, specifically, a transition from normal status or MCI to AD, rather than a marker for neurodegenerative processes occurring in the disease.

Adult↗
PubMed2006

Analysis of the cerebellar proteome in a transgenic mouse model of inherited prion disease reveals preclinical alteration of calcineurin activity.

Inherited prion diseases are linked to insertional and point mutations in the prion protein (PrP) gene, which favor conversion of PrP into a conformationally altered, pathogenic isoform. The cellular mechanism by which this process causes neurological dysfunction is unknown. Transgenic (Tg) (PG14) mice express a mouse PrP homolog of a nine-octapeptide insertion associated with an inherited prion disorder. These mice develop a progressive neurological syndrome characterized by ataxia and cerebellar atrophy due to synaptic degeneration in the molecular layer and massive apoptosis of granule neurons. To investigate the molecular events that may contribute to neurological dysfunction, we carried out a differential proteomic analysis of cerebella from Tg(PG14) mice at the preclinical, onset, and symptomatic phases of their neurological illness. 2-D maps of cerebellar proteins from Tg(PG14) mice were compared to those obtained from age-matched Tg(WT) mice that express wild-type PrP and remain healthy. Proteins whose levels were significantly modified in at least one stage of the Tg(PG14) disease were identified by PMF. Analysis detected a preclinical decrease of the calcium/calmodulin-dependent phosphatase calcineurin (CaN) in granule neurons, suggesting that dysregulation of CaN activity induced by mutant PrP may be responsible for the cerebellar dysfunction in Tg(PG14) mice.

Animals↗
PubMed2006

A positron emission tomography microdosing study with a potential antiamyloid drug in healthy volunteers and patients with Alzheimer's disease.

This work describes a microdosing study with an investigational, carbon 11-labeled antiamyloid drug, 1,1'-methylene-di-(2-naphthol) (ST1859), and positron emission tomography (PET) in healthy volunteers (n = 3) and patients with Alzheimer's disease (n = 6). The study aimed to assess the distribution and local tissue pharmacokinetics of the study drug in its target organ, the human brain. Before PET studies were performed in humans, the toxicologic characteristics of ST1859 were investigated by an extended single-dose toxicity study according to guidelines of the Food and Drug Administration and European Medicines Agency, which are relevant for clinical trials with a single microdose. After intravenous bolus injection of 341 +/- 21 MBq [(11)C]ST1859 (containing <11.4 nmol of unlabeled ST1859), peripheral metabolism was rapid, with less than 20% of total plasma radioactivity being in the form of unchanged parent drug at 10 minutes after administration. In both the control and patient groups, uptake of radioactivity into the brain was relatively fast (time to reach maximum concentration, 9-17 minutes) and pronounced (maximum concentration [standardized uptake value], 1.3-2.2). In both healthy volunteers and patients, there was a rather uniform distribution of radioactivity in the brain, including both amyloid-beta-rich and -poor regions, with slow washout of radioactivity (half-life, 82-185 minutes). In conclusion, these data provide important information on the blood-brain barrier penetration and metabolism of an investigational antiamyloid drug and suggest that the PET microdosing approach is a useful method to describe the target-organ pharmacokinetics of radiolabeled drugs in humans.

Adult↗
PubMed2006

Prion diseases: current understanding of epidemiology and pathogenesis, and therapeutic advances.

The bovine spongiform encephalopathy (BSE) epidemic, along with the related threat to human health posed by the transmission of the BSE agent to humans, has highlighted the importance of prion diseases. These fatal neurodegenerative diseases are characterised by spongiform changes in the CNS, and comprise a wide spectrum of clinicopathological entities in humans and animals, such as Creutzfeldt-Jakob disease (CJD) and its emerging new variant (vCJD) in humans, and BSE and scrapie in animals. This article reviews the geographical distribution and the temporal trends of CJD and vCJD; the major events in the pathogenesis of prion diseases; the risk factors for sporadic CJD and vCJD; and the possible strategies for treating them. Worldwide statistics indicate that sporadic CJD has a stable incidence of one case per million people per year; in contrast, the incidence of vCJD appears to have increased exponentially from its characterisation in 1994 to a peak in 2000. As of December 2005, 183 definite or probable cases of vCJD had been reported worldwide. The crucial event in the pathogenesis of prion diseases is the conversion of the normally occurring cellular prion protein (PrP(c)) into a pathogenic form, called protease-resistant PrP (PrP(res)) or scrapie PrP (PrP(sc)). Pathogenetic studies in rodent models have shown that PrP(sc) is found in the enteric nervous system and in the gut-associated lymphoid tissue following oral scrapie ingestion. The role of the lymphoreticular system in the pathogenesis of TSE seems to be related to the strains of agents and the host genotype. Therapeutic approaches to vCJD are mainly based on the inhibition or prevention of the pathological change that creates PrP(sc). Derivatives of acridine (such as mepacrine [quinacrine]) and the phenothiazine psychotropics have been proposed as possible therapies because of their activity in cellular models; however, neither class was able to affect the protease resistance of preexisting PrP fibrils. More encouragingly, in animal models of prion disease, tetracyclines were found to reduce prion infectivity by direct inactivation of PrP(sc). While these findings are promising, the suitability of these compounds for clinical use is still limited by their low efficacy once symptoms are apparent. Treatments based on the vaccination approach have also produced positive results, but further investigations are necessary to establish their clinical application.

Animals↗
PubMed2005

Gerstmann-Sträussler-Scheinker disease amyloid protein polymerizes according to the "dock-and-lock" model.

Prion protein (PrP) amyloid formation is a central feature of genetic and acquired prion diseases such as Gerstmann-Sträussler-Scheinker disease (GSS) and variant Creutzfeldt-Jakob disease. The major component of GSS amyloid is a PrP fragment spanning residues approximately 82-146, which when synthesized as a peptide, readily forms fibrils featuring GSS amyloid. The present study employed surface plasmon resonance (SPR) to characterize the binding events underlying PrP82-146 oligomerization at the first stages of fibrillization, according to evidence suggesting a pathogenic role of prefibrillar oligomers rather than mature amyloid fibrils. We followed in real time the binding reactions occurring during short term (seconds) addition of PrP82-146 small oligomers (1-5-mers, flowing species) onto soluble prefibrillar PrP82-146 aggregates immobilized on the sensor surface. SPR data confirmed very efficient aggregation/elongation, consistent with the hypothesis of nucleation-dependent polymerization process. Much lower binding was observed when PrP82-146 flowed onto the scrambled sequence of PrP82-146 or onto prefibrillar Abeta42 aggregates. As previously found with Abeta40, SPR data could be adequately fitted by equations modeling the "dock-and-lock" mechanism, in which the "locking" step is due to sequential conformational changes, each increasing the affinity of the monomer for the fibril until a condition of irreversible binding is reached. However, these conformational changes (i.e. the locking steps) appear to be faster and easier with PrP82-146 than with Abeta40. Such differences suggest that PrP82-146 has a greater propensity to polymerize and greater stability of the aggregates.

Amyloid↗
PubMed2005

Genotype-dependent activity of tryptophan hydroxylase-2 determines the response to citalopram in a mouse model of depression.

Polymorphism of tryptophan hydroxylase, the rate-limiting enzyme in the synthesis of brain serotonin (5-HT), is associated with less synthesis of brain 5-HT in DBA/2J and BALB/c than in C57BL/6J and 129/Sv mice. We selected the forced swimming test, a mouse model used to assess the antidepressant potential of drugs, and neurochemical techniques to study strain differences in the response to citalopram, a selective 5-HT reuptake inhibitor. Citalopram reduced immobility time in C57BL/6J and 129/Sv mice but had no such effect in DBA/2J and BALB/c mice. The drug reduced accumulation of 5-hydroxytryptophan (5-HTP), an indicator of 5-HT synthesis, in C57BL/6J and 129/Sv mice but much less in DBA/2J and BALB/c mice. Pretreatment with tryptophan raised 5-HTP accumulation and reinstated the antidepressant-like effect of citalopram in DBA/2J and BALB/c mice, whereas pharmacological inhibition of 5-HT synthesis prevented the effect of citalopram in C57BL/6J and 129/Sv mice. Because there were no strain differences in catecholamine synthesis, locomotor activity, and brain levels of citalopram at the end of the behavioral test, the results suggest that the failure of citalopram to reduce immobility time in DBA/2J and BALB/c mice is attributable to genotype-dependent impairment of 5-HT synthesis. Interstrain comparisons could probably be a useful strategy for understanding the mechanisms underlying the response to selective serotonin reuptake inhibitors.

Animals↗
PubMed2005

The T-786C NOS3 polymorphism in Alzheimer's disease: association and influence on gene expression.

A common single nucleotide polymorphism (SNP), consisting in a T-->C transition (T-786C) in endothelial nitric oxide synthase (NOS3), has been reported to be associated with vascular pathologies, but no information are available on a possible association with AD. T-786C genotype was determined by polymerase chain reaction-restriction fragment length polymorphisms (PCR-RFLP) assay in an Italian population of 432 AD patients compared with 360 healthy controls, matched for ethnic background, age and gender. Peripheral blood mononuclear cells (PBMC) from 22 subjects (11 AD and 11 controls) carrying different genotypes were isolated. Total RNA was extracted and analyzed by real-time PCR. No significant differences either in allelic or genotypic frequencies of the T-786C polymorphism between AD and normal population were observed, even stratifying AD patients by age at onset, gender, or ApoE status. However, expression of NOS3 in PBMC seems to be influenced by the presence of the C mutated allele, as demonstrated by a tendency towards a decrease in mRNA levels in C carriers, assessed by real-time PCR assay. This effect was observed both in patients and controls, independently from the cognitive impairment, and is likely to be dose-dependent, being mostly evident in CC homozygous. In conclusion, the T-786C SNP does not seem to be a risk factor for sporadic AD, but its presence correlates with a trend toward lower NOS3 expression rate, possibly exerting a beneficial effect in AD by contributing to lower oxidative damage.

Alzheimer Disease↗
PubMed2005

Rat nicastrin gene: cDNA isolation, mRNA variants and expression pattern analysis.

Nicastrin is a type 1 transmembrane glycoprotein that interacts with presenilin, Aph-1, and Pen-2 proteins to form a high molecular complex with gamma secretase activity. Then, nicastrin has a central role in presenilin-mediated processing of beta-amyloid precursor protein and in some aspects of Notch/glp-1 signaling in vivo. Here, we isolated a rat nicastrin cDNA and investigated gene expression in embryonic and adult rat tissues. The predicted amino acid sequence is comprised of 708 residues and showed a high degree of identity with other vertebrate orthologs. Besides full-length nicastrin mRNA, we identified an alternative spliced variant lacking the whole exon 3 and predicted to encode a 62-residue-long truncated protein. Full-length nicastrin mRNA was observed to be ubiquitously expressed, while the spliced variant was preferentially transcribed in the nervous system, whether in embryonic or adult neural tissues. Studies performed on primary cell cultures demonstrated that the short isoform was expressed in neurons, but not in astrocyte and microglial cells. Further experiments performed to verify the presence of the variant in neuroblastoma culture failed to show any truncated protein. Treatments by cyclohexamide showed the involvement of a quality control-based surveillance mechanism, which selectively degrades the exon 3-skipped isoform. In summary, this is the first report describing a novel skipped isoform of nicastrin which may suggest a new possible control mechanism based on the alternative splicing and nonsense-mediated mRNA decay to regulate brain protein expression and provide newer insights into potential implication in Alzheimer's disease.

Amyloid Precursor Protein Secretases↗
PubMed2005

Cytosolic prion protein (PrP) is not toxic in N2a cells and primary neurons expressing pathogenic PrP mutations.

Inherited prion diseases are linked to mutations in the prion protein (PrP) gene, which favor conversion of PrP into a conformationally altered, pathogenic isoform. The cellular mechanism by which this process causes neurological dysfunction is unknown. It has been proposed that neuronal death can be triggered by accumulation of PrP in the cytosol because of impairment of proteasomal degradation of misfolded PrP molecules retrotranslocated from the endoplasmic reticulum (Ma, J., Wollmann, R., and Lindquist, S. (2002) Science 298, 1781-1785). To test whether this neurotoxic mechanism is operative in inherited prion diseases, we evaluated the effect of proteasome inhibitors on the viability of transfected N2a cells and primary neurons expressing mouse PrP homologues of the D178N and nine octapeptide mutations. We found that the inhibitors caused accumulation of an unglycosylated, aggregated form of PrP exclusively in transfected N2a expressing PrP from the cytomegalovirus promoter. This form contained an uncleaved signal peptide, indicating that it represented polypeptide chains that had failed to translocate into the ER lumen during synthesis, rather than retrogradely translocated PrP. Quantification of N2a viability in the presence of proteasome inhibitors demonstrated that accumulation of this form was not toxic. No evidence of cytosolic PrP was found in cerebellar granule neurons from transgenic mice expressing wild-type or mutant PrPs from the endogenous promoter, nor were these neurons more susceptible to proteasome inhibitor toxicity than neurons from PrP knock-out mice. Our analysis fails to confirm the previous observation that mislocation of PrP in the cytosol is neurotoxic, and argues against the hypothesis that perturbation of PrP metabolism through the proteasomal pathway plays a pathogenic role in prion diseases.

Animals↗
PubMed2005

The neurotoxicity of prion protein (PrP) peptide 106-126 is independent of the expression level of PrP and is not mediated by abnormal PrP species.

A synthetic peptide homologous to region 106-126 of the prion protein (PrP) is toxic to cells expressing PrP, but not to PrP knockout neurons, arguing for a specific role of PrP in mediating the peptide's activity. Whether this is related to a gain of toxicity or a loss of function of PrP is not clear. We explored the possibility that PrP106-126 triggered formation of PrP(Sc) or other neurotoxic PrP species. We found that PrP106-126 did not induce detergent-insoluble and protease-resistant PrP, nor did it alter its membrane topology or cellular distribution. We also found that neurons expressing endogenous or higher level of either wild-type PrP or a nine-octapeptide insertional mutant were equally susceptible to PrP106-126, and that sub-physiological PrP expression was sufficient to restore vulnerability to the peptide. These results indicate that PrP106-126 interferes with a PrP function that requires only low protein levels, and is not impaired by a pathogenic insertion in the octapeptide region.

Animals↗
PubMed2005

Influence of the Glu298Asp polymorphism of NOS3 on age at onset and homocysteine levels in AD patients.

The distribution of the Glu298Asp polymorphism in NOS3 gene was determined in 405 Italian patients with "probable" Alzheimer's disease (AD) compared with 253 age-matched controls. Total plasma homocysteine (tHcy) levels were evaluated in 97 patients and 23 controls, and were correlated with the Glu298Asp genotype. A significantly increased frequency of the Glu/Glu genotype in late onset AD (LOAD) patients was found. tHcy levels were significantly increased in patients compared with controls and, notably, higher in LOAD than in early onset AD (EOAD). Stratifying by the Glu298Asp genotype, a trend toward an increase of tHcy was present in Glu/Glu homozygous. This wild type genotype seems to be associated with LOAD. tHcy levels are significantly increased in AD compared with controls and, moreover, higher in LOAD than in EOAD, possibly in correlation with the microvascular disease occurring with aging. Besides, a contribution of the Glu/Glu genotype in increasing tHcy levels has been observed.

Age Distribution↗