Profiling of ubiquitination pathway genes in peripheral cells from patients with frontotemporal dementia due to C9ORF72 and GRN mutations.

We analysed the expression levels of 84 key genes involved in the regulated degradation of cellular protein by the ubiquitin-proteasome system in peripheral cells from patients with frontotemporal dementia (FTD) due to C9ORF72 and GRN mutations, as compared with sporadic FTD and age-matched controls. A SABiosciences PCR array was used to investigate the transcription profile in a discovery population consisting of six patients each in C9ORF72, GRN, sporadic FTD and age-matched control groups. A generalized down-regulation of gene expression compared with controls was observed in C9ORF72 expansion carriers and sporadic FTD patients. In particular, in both groups, four genes, UBE2I, UBE2Q1, UBE2E1 and UBE2N, were down-regulated at a statistically significant (p < 0.05) level. All of them encode for members of the E2 ubiquitin-conjugating enzyme family. In GRN mutation carriers, no statistically significant deregulation of ubiquitination pathway genes was observed, except for the UBE2Z gene, which displays E2 ubiquitin conjugating enzyme activity, and was found to be statistically significant up-regulated (p = 0.006). These preliminary results suggest that the proteasomal degradation pathway plays a role in the pathogenesis of FTD associated with TDP-43 pathology, although different proteins are altered in carriers of GRN mutations as compared with carriers of the C9ORF72 expansion.

Transmembrane protein 106B gene (TMEM106B) variability and influence on progranulin plasma levels in patients with Alzheimer's disease.

We carried out an association study of transmembrane protein 106B gene (TMEM106B) rs1020004 A/G, rs6966915C/T, and rs1990622 A/G in a population of 656 patients with Alzheimer's disease (AD) and 619 controls, and tested whether the rs1990622 influences plasma progranulin levels. No differences in allele and genotype distribution were observed between cases and controls, even stratifying according to APOE status (p > 0.05). No differences in progranulin plasma levels were found between carriers of the rs1990622 and non-carriers. TMEM106b variability does not influence AD risk or plasma levels. Replication, preferably in a population with pathological confirmation, is required to confirm these results.

Innate immune system and inflammation in Alzheimer's disease: from pathogenesis to treatment.

Immune activation and inflammation, likely triggered by amyloid-beta (Aß) deposition, play a remarkable role in the pathogenesis of Alzheimer's disease (AD), which is the most frequent cause of dementia in the elderly. The principal cellular elements of the brain innate immune system likely to be involved in such processes are microglia. In an attempt to search for new disease-modifying drugs, the immune system has been addressed, with the aim of removing deposition of Aß or tau by developing vaccines and humanized monoclonal antibodies. The aim of this review is to summarize the current evidence regarding the role played by microglia and inflammatory molecules in the pathogenesis of AD. In addition, we will discuss the main active and passive immunotherapeutic approaches.

Incomplete penetrance of the C9ORF72 hexanucleotide repeat expansions: frequency in a cohort of geriatric non-demented subjects.

We genotyped for the C9ORF72 hexanucleotide repeat expansion a population of 156 non-demented elderly subjects, recruited in a geriatric unit as control group for association studies in patients with Alzheimer's disease (AD), and found two carriers (1.2%). The first was referred for subjective memory complaints, at age 81. He was followed up until age 84 and did not develop dementia. The second was an 80-year old volunteer (spouse and caregiver of a patient with AD), non-demented at time of recruitment. We have not had information on her condition since that time. These results suggest that the penetrance of the mutation is definitely incomplete.

C9ORF72 repeat expansion not detected in patients with multiple sclerosis.

A hexanucleotide repeat expansion in the chromosome 9 Open Reading Frame 72 gene (C9ORF72) has recently been reported to be cause of familial amyotrophic lateral sclerosis and frontotemporal lobar degeneration. Nevertheless, in the last few years this mutation has been found to be associated with heterogeneous phenotypes, including multiple sclerosis (MS) in concurrence with amyotrophic lateral sclerosis. In this study, we sought to evaluate the presence of the C9ORF72 repeat expansion in a cohort consisting of 314 patients with MS and 222 control subjects. No pathogenic expansion was found in MS and control populations, suggesting that C9ORF72 does not play a major role in MS pathogenesis.

Decreased circulating miRNA levels in patients with primary progressive multiple sclerosis.

Emerging evidence underlines the importance of micro(mi)RNAs in the pathogenesis of multiple sclerosis (MS). Free-circulating miRNAs were investigated in serum from MS patients compared to controls. Statistically significant decreased levels of miR-15b, miR-23a and miR-223 were observed in MS patients (p < 0.05). Results were validated and replicated in two further independent MS populations. A direct correlation between miRNA levels and the EDSS score was determined in PPMS (p < 0.007). The generalized trend toward miRNA down-regulation could result in over-expression of target genes involved in disease pathogenesis. Circulating miRNA profiling could thus represent a new avenue to identify easily detectable disease biomarkers.

Autosomal dominant frontotemporal lobar degeneration due to the C9ORF72 hexanucleotide repeat expansion: late-onset psychotic clinical presentation.

BACKGROUND: A hexanucleotide repeat expansion in the first intron of C9ORF72 has been shown to be responsible for a high number of familial cases of amyotrophic lateral sclerosis or frontotemporal lobar degeneration (FTLD). Atypical presentations have been described, particularly psychosis. METHODS: We determined the frequency of the hexanucleotide repeat expansions in a population of 651 FTLD patients and compared the clinical characteristics of carriers and noncarriers. In addition, we genotyped 21 patients with corticobasal syndrome, 31 patients with progressive supranuclear palsy, and 222 control subjects. RESULTS: The pathogenic repeat expansion was detected in 39 (6%) patients with FTLD (17 male and 22 female subjects); however, it was not detected in any corticobasal syndrome and progressive supranuclear palsy patients or controls. Twenty-four of 39 carriers had positive family history for dementia and/or amyotrophic lateral sclerosis (61.5%), whereas only 145 of 612 noncarriers had positive family history (23.7%; p<.000001). Clinical phenotypes of carriers included 29 patients with the behavioral variant frontotemporal dementia (bvFTD; 5.2% of all bvFTD cases), 8 with bvFTD/motor neuron disease (32% bvFTD/motor neuron disease cases), 2 with semantic dementia (5.9% of patients with semantic dementia), and none with progressive nonfluent aphasia. The presentation with late-onset psychosis (median age = 63 years) was more frequent in carriers than noncarriers (10/33 vs. 3/37, p = .029), as well as the presence of cognitive impairment at onset (15/33 vs. 5/37; p = .0039). CONCLUSIONS: The repeat expansion in C9ORF72 is a common cause of FTLD and often presents with late-onset psychosis or memory impairment.

Expression and Genetic Analysis of MicroRNAs Involved in Multiple Sclerosis.

Evidence underlines the importance of microRNAs (miRNAs) in the pathogenesis of multiple sclerosis (MS). Based on the fact that miRNAs are present in human biological fluids, we previously showed that miR-223, miR-23a and miR-15b levels were downregulated in the sera of MS patients versus controls. Here, the expression levels of these candidate miRNAs were determined in peripheral blood mononuclear cells (PBMCs) and the serum of MS patients, in addition to three genotyped single nucleotide polymorphisms (SNPs). Mapping in the genomic regions of miR-223, miR-23a and miR-15b genes, 399 cases and 420 controls were tested. Expression levels of miR-223 and miR-23a were altered in PBMCs from MS patients versus controls. Conversely, there were no differences in the expression levels of miR-15b. A significantly decreased genotypic frequency of miR-223 rs1044165 T/T genotype was observed in MS patients. Moreover, the allelic frequency of miR-23a rs3745453 C allele was significantly increased in patients versus controls. In contrast, there were no differences in the distribution of miR-15b SNP. In conclusion, our results suggest that miR-223 and miR-23a could play a role in the pathogenesis of MS. Moreover, miR-223 rs1044165 polymorphism likely acts as a protective factor, while miR-23a rs3745453 variant seems to act as a risk factor for MS.

Expression of the transcription factor Sp1 and its regulatory hsa-miR-29b in peripheral blood mononuclear cells from patients with Alzheimer's disease.

Altered gene expression occurs in central nervous system disorders, including Alzheimer's disease (AD). Transcription factor Sp1 (specificity protein 1) can regulate the expression of several AD-related proteins, including amyloid-ß protein precursor and tau. Sp1 is regulated by oxidative stress, and Sp1 mRNA was found to be upregulated in AD cortex and hippocampus. The distribution of three single nucleotide polymorphisms (SNPs), including rs7300593, rs17695156, and rs12821290, covering 100% Sp1 genetic variability, has been determined in a population of 393 AD patients as compared with 412 controls. In addition, expression analysis of Sp1 and its regulatory microRNAs (hsa-miR-29b and hsa-miR-375) has been performed in peripheral blood mononuclear cells (PBMCs), together with Sp1 protein analysis. No differences in all three SNP distributions were observed in AD patients as compared with controls. Stratifying according to gender, a significantly decreased frequency of Sp1 rs17695156 T allele was observed in male patients versus male controls. Significantly increased Sp1 relative expression levels were observed in PBMCs from AD patients as compared with controls. Western blot analysis paralleled mRNA increase in AD patients versus controls and correlated positively with Sp1 mRNA levels. Significantly decreased relative expression levels of hsa-miR-29b, but not of hsa-miR-375, were observed in AD patients versus controls and correlated negatively with Sp1 mRNA levels. According to these results, Sp1 and its regulatory hsa-miR-29b are deregulated in AD patients, possibly leading to aberrant production of downstream target genes involved in the pathogenesis. Moreover, Sp1 rs176951056 T allele is likely a protective factor in the male population.

Early onset behavioral variant frontotemporal dementia due to the C9ORF72 hexanucleotide repeat expansion: psychiatric clinical presentations.

A hexanucleotide repeat expansion in the first intron of C9ORF72 has been shown to be responsible for a high number of familial cases of amyotrophic lateral sclerosis or frontotemporal lobar degeneration with or without concomitant motor neuron disease phenotype and TDP-43 based pathology. Here, we report on three cases carrying the hexanucleotide repeat expansion with an atypical presentation consisting in the development of psychiatric symptoms. Patient #1, a 53 year old man with positive family history for dementia, presented with mood deflection, characterized by apathy, social withdraw, and irritability in the last two years. He was diagnosed with "mild cognitive impairment due to depressive syndrome" six months later and subsequently with Alzheimer's disease. Patient #2, a woman with positive family history for dementia, developed behavioral disturbances, aggressiveness, and swearing at 57 years of age. Patient #3 presented, in the absence of brain atrophy, with mystical delirium with auditory hallucinations at 44 years of age, and did not present neurological symptoms over a 7-year follow up. The description of these cases underlines that the hexanucleotide repeat expansion in chromosome 9 could be associated with early onset psychiatric presentations.

Genetics and expression analysis of the specificity protein 4 gene (SP4) in patients with Alzheimer's disease and frontotemporal lobar degeneration.

Transcription factor Sp4 (Specificity protein 4) levels are increased in the brain of patients with Alzheimer's disease (AD), and Sp4 colocalizes with neurofibrillary tangles. Moreover, SP4 is a susceptibility gene for bipolar disorder and schizophrenia, which share many clinical features with frontotemporal lobar degeneration (FTLD). The distribution of three tagging single nucleotide polymorphisms(SNPs)-rs9639379, rs10272006, and rs6461569-has been determined in a population of 352 patients diagnosed clinically with AD, 290 patients with FTLD, and 341 age-matched controls. Expression analysis of SP4 was performed in peripheral blood mononuclear cells (PBMC). No significant differences in either allelic or genotypic frequency of the three SNPs were found (p > 0.05), even stratifying according to gender and to the apolipoprotein E status. Significantly increased SP4 relative expression levels were observed in PBMC from patients with AD as compared with controls (7.132 ± 1.301 versus 3.396 ± 0.829, p < 0.050) and a similar trend was shown in patients with FTLD compared with controls (6.525 ± 1.500 versus 3.396 ± 0.829, p = 0.073). According to these results, SP4 gene does not act as a susceptibility factor either for AD or FTLD. However, Sp4 mRNA levels are upregulated in patients, possibly resulting in an aberrant expression of downstream target genes involved in the pathogenesis of both diseases.