Particulate matter exposure is associated with inflammatory gene methylation in obese subjects.

BACKGROUND: Overweight and obesity are becoming more widespread with alarming projections for the coming years. Obesity may increase susceptibility to the adverse effects of PM exposure, exacerbating the effects on cardiovascular diseases and altering the biomarkers of vascular inflammation. The associated biological mechanisms have not been fully understood yet; the common denominator in the pathogenesis of the co-morbidities of obesity is the presence of an active, low-grade inflammatory process. DNA methylation has been shown to regulate inflammatory pathways that are responsible for the development of cardiovascular diseases. OBJECTIVES: The aim of the study was to investigate, in a population of overweight/obese subjects, the effects of PM on blood DNA methylation in genes associated to inflammatory response. METHODS: Using bisulfite pyrosequencing, we measured DNA methylation in peripheral blood mononuclear cells from 186 overweighted/obese subjects. In particular, we quantified DNA methylation in a set of 3 candidate genes, including CD14, TLR4 and TNF-α, because of the important roles that these genes play in the inflammatory pathway. Personal exposure to PM10 was estimated for each subject based on the local PM10 concentrations, measured by monitoring stations at residential address. Repeated measure models were used to evaluate the association of PM10 with each genes, accounting for possible correlations among the genes that regulate the same inflammatory pathway. RESULTS: We found an inverse association between the daily PM10 exposure and the DNA methylation of inflammatory genes, measured in peripheral blood of healthy overweight/obese subjects. Considering different exposure time-windows, the effect on CD14 and TLR4 methylation was observed, respectively, in days 4-5-6, and days 6-7-8. TNF-α methylation was not associated to PM10. CONCLUSIONS: Our findings support a picture in which PM10 exposure and transcriptional regulation of inflammatory gene pathway in obese subjects are associated.

MCP-1 A-2518G polymorphism: effect on susceptibility for frontotemporal lobar degeneration and on cerebrospinal fluid MCP-1 levels.

The distribution of the MCP-1 A-2518G single nucleotide polymorphisms (SNP) was analyzed in a population of 212 patients with frontotemporal lobar degeneration (FTLD) compared with 203 age-matched controls. A significantly decreased allelic frequency of the G allele in patients compared with controls was observed (21.1 versus 29.3%, P = 0.011, OR: 0.59, CI: 0.40-0.87). Stratifying according to gender, the association was maintained in male patients versus male controls (17.8 versus 29.4%, P = 0.016, OR = 0.46, 95% CI: 0.25-0.84), but not in female patients compared with female controls (23.5 versus 29.2%, P > 0.05). The frequency of apolipoprotein E epsilon4 carriers was increased in patients (26.4 versus 13.8%, P = 0.0015, OR: 2.24, 95% CI: 1.37-3.67). Apolipoprotein E status did not influence the distribution of the A-2518G SNP. Monocyte chemotactic protein (MCP)-1 levels were determined in cerebrospinal fluid (CSF) collected from 23 patients and 17 controls. MCP-1 CSF levels were increased in patients compared with controls (449.01 +/- 27.57 versus 364.19 +/- 23.75 pg/ml, P = 0.011). Stratifying patients according to the presence of the polymorphic allele, significantly increased CSF MCP-1 levels were observed in carriers of the G allele compared with non-carriers (502.21 +/- 44.57 versus 395.87 +/- 21.92 pg/ml, P = 0.045). The MCP-1 A-2518G SNP acts as protective factor for sporadic FTLD, possibly by influencing MCP-1 production.

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 serotonin transporter promoter polymorphic region is not a risk factor for Alzheimer's disease related behavioral disturbances.

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by memory loss and often accompanied during its progression by behavioral and psychological symptoms of dementia (BPSD). We decided to evaluate the association between AD-related behavioral disturbances and the short/long (S/L) polymorphism of the promoter region of the 5-hydroxytryptamine (5-HT) transporter gene (SLC6A4). This functional polymorphism modulates SLC6A4 transcription rate, with the S-allele having a 2-fold reduced efficiency, leading to a diminished availability of 5-HT that might in turn trigger behavioral and cognitive alterations. The SLC6A4 promoter functional single nucleotide polymorphism rs25531 (A-->G) was genotyped as well. We collected 235 sporadic AD subjects that were classified as AD with (n = 122) or without (n = 113) behavioral alterations, assessed with the Spontaneous Behavior Interview scale, section Behavioral Problems (SBI-BP). Comparing the genotypic and allelic frequencies of AD without and with BPSD, we did not find a difference for the 5-HTTLPR or the rs25531, even after stratification according to single SBI-BP item. We conclude that 5-HTTLPR and rs25531 are not major genetic modulators of BPSD development in AD.

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 Alzheimer's 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 Alzheimer's 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.