Maria Serpente

Expression and genetic analysis of miRNAs involved in CD4+cell activation in patients with multiple sclerosis

MicroRNA (miRNA)-mediate RNA interference has been identified as a novel mechanism that regulates protein expression. It is recognised that miRNAs play essential roles in the immune system and for correct function in the brain. Moreover, it is now clear that abnormal miRNA expression is a common feature of several diseases involving the immune system including multiple sclerosis (MS). Expression analysis for miR-21, miR-146a and -b, miR-150, miR-155 was carried out in peripheral mononuclear cells (PBMC) from a cohort of 29 MS patients and 19 controls. Subsequently, a case control study for miR-146 rs2910164 variant was performed in an overall population of 346 MS cases and 339 controls. A statistically significant increased expression of miR-21, miR-146a and -b was observed in relapsing remitting (RR)MS patients as compared with controls (1.44±0.13 vs 0.79±0.06, P=0.036; 1.50±0.12 vs 0.84±0.08, P=0.039; 1.54±0.15 vs 0.72±0.08, P=0.001 respectively). On the contrary, no differences were found in the expression levels of both miR-150 and miR-155 in patients as compared with controls (P>0.05). The genetic association study failed to find any differences in the frequencies of rs2910164 between patients and controls. miRNA dysregulation may contribute to the pathogenesis of MS and highlights the possibility to define different disease entities with specific miRNAs profile.

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.

Circulating miRNAs as Potential Biomarkers in Alzheimer's Disease

Several micro(mi)RNA are deregulated in brain, cerebrospinal fluid (CSF), and serum/plasma from patients with Alzheimers disease (AD). The aim of the study was to profile circulating miRNAs in serum as non-invasive biomarkers for AD, correlating them with those identified in CSF, the biological fluid which better reflects biochemical changes occurring during pathological processes in the brain and may provide a robust indicator of AD-related disease pathogenesis thanks to the evidence of low amyloid and high levels of tau and hyperphosphorylated tau. Using a two-step analysis (array and validation through real-time PCR), a down-regulation (mean fold change ± SEM) of miR-125b (0.415 ± 0.11 versus 1.381 ± 0.36, p = 0.009), miR-23a (0.111 ± 0.03 versus 0.732 ± 0.14, p < 0.001), and miR-26b (0.414 ± 0.11 versus 1.353 ± 0.39, p < 0.01), out of 84 tested, was shown in serum from 22 AD patients compared with 18 non-inflammatory and 8 inflammatory neurological controls (NINDCs and INDCs) and 10 patients with frontotemporal dementia. Significant down-regulation of miR-125b and miR-26b was also confirmed in CSF from AD patients versus NINDCs (miR-125b: 0.089 ± 0.03 versus 0.230 ± 0.08, p < 0.001; miR-26b: 0.217 ± 0.06 versus 1.255 ± 0.29, p < 0.001, mean fold change ± SEM, respectively), whereas data were not replicated for miR-23a. In serum, miR-125b had an AUC of 0.82 to distinguish AD from NINDCs (95% CI: 0.65-0.98, p = 0.005). In conclusion, we demonstrated that cell-free miR-125b serum levels are decreased in serum from patients with AD as compared with NINDC and distinguish between AD and NINDCs with an accuracy of 82%.

MicroRNA and mRNA expression profile screening in multiple sclerosis patients to unravel novel pathogenic steps and identify potential biomarkers

Identification of novel targets and biomarkers, such as microRNAs, is extremely helpful to understand the pathogenetic mechanisms in a disease like multiple sclerosis (MS). We tested the expression profile of 1145 microRNAs in peripheral blood mononuclear cells (PBMCs) of 19 MS patients and 14 controls, and we further explored their function by performing a whole-genome mRNA profiling in same subjects and using bioinformatic prediction tool. A total of 104 miRNAs have been identified as deregulated in MS patients; 2/10 which ranked highest (let-7g and miR-150) have been validated in a replication sample, leading to the identification of putative target genes.

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.

Phenotypic Heterogeneity of the GRN Asp22fs Mutation in a Large Italian Kindred

The Asp22fs(g.63_64insC) mutation in progranulin gene (GRN) has been so far reported in one patient who developed frontotemporal dementia (FTD) at the age of 65. Here, we describe the clinical heterogeneity associated with the GRN Asp22fs mutation in a large Italian family. Clinical and instrumental workup of two symptomatic carriers in two generations has been carried out, together with genetic analysis of probands and of nine asymptomatic family members. The first proband was a 47-year old male clinically diagnosed with FTD. Family history was positive and suggestive of an autosomal dominant pattern of inheritance. Evaluation of plasma GRN levels was consistent with the presence of a mutation in its encoding gene, that was demonstrated by sequencing [Asp22fs(g.63_64insC)]. Brain MRI showed multiple T2 and FLAIR hyperintense areas in the frontal lobe white matter and right hemisphere cortical atrophy. The second proband was his 79 year old uncle, presenting with mild cognitive impairment. Brain MRI showed small T2 hyperintense lesions and widespread cortical atrophy. Cerebrospinal fluid amyloid-β, tau, and phosphotau protein levels were in both cases in the range of normality. Additional nine asymptomatic family members were studied. This familys description expands the spectrum of clinical presentations of frontotemporal lobar degeneration caused by GRN mutations, suggesting that the diagnosis could be missed in some individuals with an atypical presentation, and points up the importance of GRN plasma level evaluation.

The C9ORF72 hexanucleotide repeat expansion is a rare cause of schizophrenia

A hexanucleotide repeat expansions in the first intron of C9ORF72 has been shown to be responsible for a high number of familial cases of amyotrophic lateral sclerosis and/or frontotemporal lobar degeneration. The same mutation has been described in a patient with bipolar disorder, but up to now, not in patients suffering from schizophrenia. We determined the frequency of the C9ORF72 hexanucleotide repeat expansions in a population of 298 patients with schizophrenia or schizoaffective disorder. The pathogenic repeat expansion was detected in 2 patients (0.67%). Both of them presented with auditory hallucinations and had comorbid alcohol abuse. In addition, a positive family history for psychiatric and/or neurodegenerative diseases was present. The repeat expansion in the C9ORF72 gene is a rare, but possible, cause of schizophrenic spectrum disorders. We cannot rule out however whether the number of repeats influence the phenotype.

Role of hnRNP-A1 and miR-590-3p in neuronal death: genetics and expression analysis in patients with Alzheimer disease and frontotemporal lobar degeneration

An association study of heterogeneous nuclear ribonucleoprotein (hnRNP)-A1 was carried out in a population of 274 patients with frontotemporal lobar degeneration (FTLD) and 287 with Alzheimer disease (AD) as compared with 344 age- and gender-matched controls. In addition, we evaluated expression levels of hnRNP-A1 and its regulatory microRNA (miR)-590-3p in blood cells from patients and controls. A statistically significant increased frequency of the hnRNP-A1 rs7967622 C/C genotype was observed in FTLD, but not in AD, in patients as compared to controls (23.0 versus 15.4%; p = 0.022, odds ratio [OR] 1.64, confidence interval [CI] 1.09-2.46). Stratifying according to gender, a statistically significant increased frequency of the hnRNP-A1 rs7967622 C/C genotype was observed in male patients as compared to male controls (23.1 versus 11.3%; p = 0.015, OR 2.36, CI 1.22-4.58 but not in females. Considering the rs4016671 single-nucleotide polymorphism (SNP), all patients and controls were wild type. Significantly increased hnRNP-A1 relative expression levels in peripheral blood mononuclear cells (PBMCs) was observed in patients with AD, but not with FTLD, as compared to controls (2.724 ± 0.570 versus 1.076 ± 0.187, p = 0.021). Decreased relative expression levels of hsa-miR-590-3p was observed in patients with AD versus controls (0.685 ± 0.080 versus 0.931 ± 0.111, p = 0.079), and correlated negatively with hnRNP-A1 mRNA levels (r = -0.615, p = 0.0237). According to these findings, hnRNP-A1 and its transcription regulatory factor miR-590-3p are disregulated in patients with AD, and the hnRNP-A1 rs7967622 C/C genotype is likely a risk factor for FTLD in male populations.

Rs5848 Variant Influences GRN mRNA Levels in Brain and Peripheral Mononuclear Cells in Patients with Alzheimer's Disease

Mutations in the progranulin gene (GRN), causative for Frontotemporal Lobar Degeneration with ubiquitin-immunoreactive neuronal inclusions (FTLD-U), could also be associated with Alzheimers disease (AD). The influence of GRN genetic variability on susceptibility to AD and on expression levels in a series of neuropathologically-confirmed AD patients as well as in peripheral mononuclear cells (PBMC) and in cells isolated from cerebrospinal fluid (CSF) was investigated. An association study of rs9897526 and rs5848 was carried out in an Italian population and in a replication population of European American patients and controls. None of the variants tested act as unequivocal susceptibility factor in both populations although rs9897526 anticipated the onset of the disease in the Italian population. GRN expression in the parietal lobe of AD cases showed a 0.76-fold decrease compared with controls (1.31 +/- 0.07 versus 1.73 +/- 0.12, P = 0.0025). Patients carrying the rs5848 TT genotype had the lowest GRN expression levels (0.96 +/- 0.12, P = 0.014). Despite no significant differences were found in the relative PBMC and CSF GRN expression in patients compared to controls, stratifying patients according to the presence of rs5848 T allele, a 0.57-fold decrease in GRN mRNA levels over C carriers was found in PBMC (1.22 +/- 0.23 versus 0.70 +/- 0.12, P = 0.04). Similarly to data obtained in brain samples, patients carrying the TT genotype showed the lowest GRN mRNA levels (TT = 0.46 +/- 0.14, CC = 1.22 +/- 0.23; P = 0.013). These data argue against a direct role of GRN as a susceptibility factor for sporadic AD but support a role of GRN as a disease-modifying gene, possibly contributing to the failure of neuronal survival.

Cerebrospinal Fluid Biomarkers in Progranulin Mutations Carriers

Cerebrospinal fluid (CSF) biomarkers (Aβ₁₋₄₂, total tau, P-181 tau) are currently used to support a clinical diagnosis of Alzheimers disease (AD). The CSF profile in frontotemporal lobar degeneration (FTLD) caused by Progranulin (GRN) mutation is unknown. We assessed CSF biomarkers in 145 AD, 140 FTLD (20 GRN positive, 120 GRN negative) patients, and 38 controls. Taking into account the reference values used in clinical practice, GRN mutation carriers and controls did not differ significantly for any biomarker, whereas GRN negative FTLD patients had higher tau levels than controls (p < 0.001) and patients carrying GRN Thr272fs mutation (p = 0.033, Chi-Square test). Comparing CSF biomarkers mean values among groups, total tau was significantly increased in GRN negative FTLD and in mutation carriers compared with controls (p < 0.001). P-181 tau CSF was increased in AD patients and in GRN negative FTLD compared with controls (p < 0.001), but not in 17 patients carrying the Thr272fs mutation. 88.2% of mutation carriers had normal CSF tau, despite the neurodegenerative nature of FTLD. Our results suggest that GRN mutation carriers have normal or borderline CSF biomarkers. In patients with an AD-like phenotype but normal or borderline CSF biomarkers, a diagnosis of FTLD-U caused by GRN mutations should be considered.