Diego Scalabrini

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.

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.

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.

The NOS3 G894T (Glu298Asp) polymorphism is a risk factor for frontotemporal lobar degeneration

Background and aims:  Neuronal nitric oxide synthase (NOS)1 C276T polymorphism was shown to increase the risk for frontotemporal lobar degeneration (FTLD). In the brain, both NOS1 and NOS3 (endothelial isoform) have been detected. The distribution of NOS3 G894T (Glu298Asp) and T‐786C single nucleotide polymorphisms (SNPs) was analyzed in a population of 222 patients with FTLD compared with 218 age‐matched controls to determine whether they could influence the susceptibility to develop the disease.

Association of a NOS1 promoter repeat with Alzheimer's disease.

The gene encoding NOS-I (NOS1) displays a complex transcriptional regulation, with nine alternative first exons. Exon 1c and 1f are the most abundant forms in the brain. A functional single nucleotide polymorphism (SNP) in exon 1c and a polymorphism in exon 1f, consisting of a variable number of tandem repeats (VNTR) originating short (S) and long (L) alleles, were studied in 184 patients with Alzheimers disease (AD) and 144 gender- and age-matched controls. No differences were found for the Ex1c G-84A. The Ex1f-VNTR S allele was significantly more common in AD (55% versus 44%, P=0.009, OR=1.52) as was the S/S genotype (28% versus 14%, P=0.008; OR=2.37). The S allele showed a highly significant interaction with the ApoE epsilon 4 allele (OR: 10.83). Therefore, short alleles of the NOS1 exon 1f-VNTR are likely to be susceptibility factors for AD, and interact with the epsilon 4 allele to markedly increase the AD risk.

Gender-specific influence of the chromosome 16 chemokine gene cluster on the susceptibility to Multiple Sclerosis.

Macrophage-derived chemokine (MDC/CCL22) plays a role in Experimental Autoimmune Encephalomyelitis (EAE), the animal model of Multiple Sclerosis (MS). MDC/CCL22 gene is part of a chemokine cluster, which includes also thymus and Activation-Regulated Chemokine (TARC/CCL17). The frequency of the C/T and C/A Single Nucleotide Polymorphisms (SNPs) in the promoter and coding sequence of CCL22 as well as the C/T SNP in the promoter of CCL17 were determined in 370 patients with Multiple Sclerosis (MS) compared with 380 controls. A trend towards a decreased allelic frequency of the A allele of the CCL22 C/A SNP as well as of the T allele of the CCL17 C/T SNP was found in patients compared with controls. The frequency of the AT haplotype was significantly decreased in MS patients (P=0.017, OR: 0.49, CI: 0.28-0.87). Stratifying patients according to gender, the observed association was even more pronounced in male patients compared with male controls (P=0.004, OR=0.18, 95% CI: 0.06-0.50), whereas no significant differences were observed in females. Therefore, the presence of the AT haplotype in chromosome 16 chemokine cluster is likely to confer a decreased risk of developing MS, particularly in males.

MDC/CCL22 intrathecal levels in patients with multiple sclerosis.

MDC/CCL22 has been detected in the brain of mice with experimental autoimmune encephalomyelitis. MDC/CCL22 cerebrospinal fluid levels were evaluated in 56 patients with multiple sclerosis (MS) and in 17 controls. No significant differences were found, even when stratifying patients according to the disease subtype. Stratifying by gender, significantly increased MDC/CCL22 levels were observed in female patients when compared with female controls and male patients (109.03 versus 98.54 and 99.37 pg/mL, P = 0.034 and 0.018, respectively). Therefore, MDC/CCL22 is likely to play a role in the development of MS in females only, possibly influencing the intracerebral recruitment of Th2 cells, which produce anti-inflammatory cytokines. Multiple Sclerosis 2008; 14: 547—549. http://msj.sagepub.com