Eliana Venturelli

Oxidative imbalance in patients with mild cognitive impairment and Alzheimer's disease

Increasing evidence supports a role of oxidative imbalance, characterized by impaired antioxidant enzymatic activity and increased reactive oxygen species (ROS) production, in mild cognitive impairment (MCI) and Alzheimers disease (AD) pathogenesis. Hyperhomocysteinemia, another risk factor for AD, also contributes to oxidative damage. Plasma total homocysteine (tHcy) and ROS levels, and total antioxidant capacity (TAC) were determined in 71 AD, 36 MCI and 28 vascular dementia (VaD) patients as well as in 44 age-matched controls. tHcy levels were significantly increased in patients with AD and VaD an a trend towards an increase in multiple domain MCI was observed. TAC was significantly decreased in AD as well as MCI, but not in VaD patients. In AD patients, a negative correlation was found between TAC and disease duration. ROS levels did not differ among groups, but were correlated with age. In conclusion, a pattern characterized by increased tHcy levels and decreased TAC is present in AD as well as MCI patients. While increased tHcy levels were also found in VaD, TAC modifications occur specifically in AD. ROS levels appear to be correlated with age rather than with a specific dementing disorder, thus leading to the hypothesis that oxidative imbalance observed in AD could be due to a decreased TAC.

Serum MCP-1 levels are increased in mild cognitive impairment and mild Alzheimer's disease.

Upregulation of a number of chemokines, including monocyte chemotactic protein-1 (MCP-1), is associated with Alzheimers disease (AD) pathological changes. Emerging evidence suggests that inflammatory events precede the clinical development of AD, as cytokine disregulation has been observed also in patients with mild cognitive impairment (MCI). MCP-1 levels were evaluated in serum samples from 48 subjects with MCI, 94 AD patients and 24 age-matched controls. Significantly increased MCP-1 levels were found in MCI and mild AD, but not in severe AD patients as compared with controls. mRNA levels in peripheral blood mononuclear cells (PBMC), evaluated by quantitative RT-PCR analysis, paralleled serum MCP-1 levels. Moreover, a progressive MCP-1 decrease was observed over a 1-year follow up in a subgroup of MCI subjects converted to AD. MCP-1 upregulation is likely to be a very early event in AD pathogenesis, by far preceding the clinical onset of the disease. Nevertheless, as MCP-1 is likely to play a role in several pathologies with an inflammatory component, a possible usefulness as an early AD biomarker would be possible only in combination with other molecules.

Progranulin plasma levels as potential biomarker for the identification of GRN deletion carriers. A case with atypical onset as clinical amnestic Mild Cognitive Impairment converted to Alzheimer's disease.

Progranulin (GRN) mutations are associated with different clinical phenotypes, including Frontotemporal Lobar Degeneration (FTLD), Corticobasal Degeneration and Alzheimers disease (AD). In addition, the range of age at onset is very wide and patients presenting initial symptoms around eighty years have been described. Previous studies demonstrated that progranulin plasma levels determination may be a reliable method to identify GRN deletion carriers. We thus evaluated progranulin plasma levels in all patients followed at our Alzheimers Centre whose plasma was available (n=176) and found four patients displaying low values. Three of them carried the CACT deletion in exon 7 and their clinical diagnosis was behavioral variant Frontotemporal Dementia. We also identified a patient carrying a previously reported CAGT deletion in exon 5. Here, we report on this case. The onset of symptoms was at 77 years and the initial diagnosis was of amnestic Mild Cognitive Impairment (aMCI), which converted to AD six months later. In the following years, the patient also developed behavioral disturbances, gait apraxia and parkinsonian symptoms. At present, she is 84 years old and is still followed-up periodically. This case confirms progranulin plasma levels as a reliable biomarker to identify GRN deletion carriers and discriminate between FTLD and other dementias which may mimic it. We thus encourage the inclusion of this non-invasive and easy test in clinical practice.

Intrathecal chemokine levels in Alzheimer disease and frontotemporal lobar degeneration

Amyloid beta (Aβ)1–42 deposition into the brain is considered a crucial pathogenetic step during Alzheimer disease (AD) development, as it originates a cascade of events leading to irreversible neuronal damage.1 Conversely, frontotemporal lobar degeneration (FTLD) is characterized by intracellular deposition of abnormally phosphorylated tau protein responsible for neuronal death.2 Immunoreactivity for a number of chemokines and for their related receptors has been demonstrated in resident cells of the CNS.3 Some of them have been proposed as candidate genes for AD,4 and increased levels have been found in CSF from patients with AD,5 whereas no information on chemokines in FTLD is available at present. Interferon-γ-inducible protein-10 (IP-10), monocyte chemotactic protein-1 (MCP-1), and interleukin-8 (IL-8) levels were evaluated in CSF from 32 patients with probable AD (11 men and 21 women; mean age at onset: 62.1 ± 8.0 years), 24 with FTLD (frontotemporal dementia [FTD] = 17; progressive aphasia [PA] = 5; semantic dementia [SD] = 2; 9 men and 15 women; mean age at onset: 61.5 ± 1.6 years). …

Intrathecal levels of IL-6, IL-11 and LIF in Alzheimer's disease and frontotemporal lobar degeneration

Cerebrospinal fluid (CSF) levels of interleukin (IL)-6, IL-11 and leukaemia inhibitory factor (LIF) were evaluated in 43 patients with Alzheimers disease (AD) and 24 patients with frontotemporal lobar degeneration (FTLD) as compared with 30 agematched controls (CON), and correlated with clinical and demographic data and with CSF biomarkers amyloid beta (Aβ)42, total tau and tau phosphorylated at position 181 (P-tau). CSF IL-11 mean levels were significantly increased in AD and FTLD as compared with CON (6.5 ± 4.6 and 6.6 ± 5.1 versus 3.1 ± 3.3 pg/ml, P = 0.009). IL-6 mean levels did not differ between patients and CON (P > 0.05),whereas LIF levels were not detectable in patients or in CON. In AD patients, a significantly positive correlation between MMSE scores and IL-11 CSF concentration was observed (r = 0.344, P = 0.028). No correlations with CSF Aβ42, total tau and P-tau were found. IL-11, but not IL-6 levels are increased in AD and FTLD, and the highest peaks were observed in patients with a less severe degree of cognitive deterioration, therefore suggesting a role of this cytokine in early phases of neurodegeneration.

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.

Novel exon 1 progranulin gene variant in Alzheimer's disease

Background and purpose:  Progranulin (PGRN) expression is increased in activated microglia in Alzheimers disease (AD) brain, suggesting a potential role in this pathology.

CCR2-64I polymorphism and CCR5Δ32 deletion in patients with Alzheimer's disease

Monocyte chemoattractant protein-1 (MCP-1) and RANTES, as well as their related receptors, have been shown to be involved in Alzheimers disease (AD) pathogenesis. Genes for their related receptors, CCR2 and CCR5, respectively, are characterized by the presence of two polymorphisms: a conservative change of a valine with an isoleucine at codon 64 of CCR2 (CCR2-64I) and a 32-bp deletion in the coding region of CCR5 (CCR5Δ32), which leads to the expression of a nonfunctional receptor. The distribution of the CCR2-64I and CCR5Δ32 polymorphisms was determined in 290 AD patients and in 222 controls. A decreased frequency and an absence of homozygous for the polymorphism CCR2-64I were found, thus suggesting a protective effect of the mutated allele on the occurrence of AD. However, these findings must be cautiously interpreted as the overall significance was found without adjustment for multiple comparisons and is coming from the complete absence of the genotype 64I/64I in AD patients. Conversely, no different distribution of the CCR5Δ32 deletion in the two populations was shown. Stratifying by the presence of ApoE ɛ4 allele, gender or age at onset, no differences in either allele frequencies were observed.

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, Alzheimers 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.

GRN Variability Contributes to Sporadic Frontotemporal Lobar Degeneration

Mutations in the progranulin gene (GRN) are responsible for familial FTLD with ubiquitin pathology (FTLD-U). However, there are controversial data regarding the contribution of GRN variability to sporadic FTLD. We carried out an association study in 265 patients, who did not carry a GRN causal mutation, and 375 age-matched controls. Four tagging Single Nucleotide Polymorphisms (SNPs) were chosen generate 80% power to detect an allelic association with P < or = 0.01. In addition, a known functional SNP (rs5848) was included. An increased frequency of the rs4792938 CC genotype in cases compared with controls was observed (17.4 versus 10.4%, P=0.01, OR: 1.81, 95%CI: 1.15-2.85). Stratifying for gender, no differences were observed for all polymorphisms. Haplotype analysis failed to detect haplotypes associated with the disease. Our findings indicate that the GRN rs4792938 CC genotype represents a susceptibility factor for the development of FTLD in individuals who do not carry GRN causal mutations. This SNP is likely located in a regulatory region, thus an effect on GRN mRNA levels may be of mechanistic importance.