Estrogen receptor beta polymorphisms and cognitive performance in women: associations and modifications by genetic and environmental influences.

Genetic and environmental risk factors contribute to the pathogenesis of Alzheimer's dementia. Besides known genetic risk factors like the apolipoprotein (APO) Eε4 allele, single nuclear polymorphisms (SNPs) of the estrogen receptors (ESRs) are candidate genetic risk factors, while air pollution represents an environmental risk factor for dementia. Effects of these risk factors and their interaction were investigated in the SALIA cohort of 834 non-demented elderly women. Cognitive function was assessed by the CERAD-plus test battery. Air pollution was estimated by land use regression (LUR) models. Genotyping was carried out for nine ESR1 and ESR2 SNPs and two ApoE SNPs. Carriers of minor ESR2 alleles showed significantly reduced cognitive performance in the CERAD total score with most pronounced deficits in semantic memory (rs1256062, rs10144225, and rs2274705) and executive function (rs1256062). The minor allele effects of ESR2 were stronger in carriers of APOEε4 for the cognitive domain 'executive function' (p value of interaction 0.023 for rs1256062). The investigated ESR1 SNPs were not associated with cognition. Furthermore, we found a significant gene-environment interaction between the ESR2 SNP rs1256062 and air pollution on cognition. Carriers of two major alleles of rs1256062 were more susceptible for an air pollution-induced decrease in performance of 'figure copying' than carriers of minor alleles (p value of interaction, e.g., 0.031 for PM2.5). In conclusion, ESR2 but not ESR1 minor alleles were associated with lower cognitive performance in elderly women with an indication of a gene-gene interaction with APOEε4. We also found indications for gene-environment interactions of ESR2 with traffic-related air pollution exposure on cognitive performance.

Association of air pollution with cognitive functions and its modification by APOE gene variants in elderly women.

BACKGROUND: Epidemiological studies have shown effects of long-term exposure to air pollution on cardiovascular and respiratory health. However, studies investigating the effects of air pollution on cognition and brain function are limited. We investigated if neurocognitive functions are associated with air pollution exposure and whether apolipoprotein E (ApoE) alleles modify the association of air pollution exposure with cognition. METHODS: We investigated 789 women from the SALIA cohort during the 22-year follow-up examination (2008-2009). Exposure to particulate matter (PM) size fractions and nitrogen oxides (NOx) were assigned to home addresses. Traffic indicators were used to assess residential proximity to high traffic load. Level of cognitive performance was assessed using the CERAD-Plus test. Air pollution effects on cognitive functioning were estimated cross-sectionally using adjusted linear regression models. RESULTS: Air pollution was negatively associated with cognitive function and cognitive performance in the subtests for semantic memory and visuo-construction. Significant associations could be observed for figure copying with an interquartile range increase of NO2 (ß=-0.28 (95%CI:-0.44;-0.12)), NOx (ß=-0.25 (95%CI:-0.40;-0.09)), PM10 (ß=-0.14 (95%CI:-0.26;-0.02)) and PM2.5 (ß=-0.19 (95%CI:-0.36;-0.02)). The association with traffic load was significant in carriers of one or two ApoE ɛ4 risk alleles. CONCLUSION: In this study of elderly women, markers of air pollution were associated with cognitive impairment in the visuospatial domain. The association of traffic exposure is significant in participants carrying the ApoE ε4 risk allele.

Investigating the spill-over hypothesis: analysis of the association between local inflammatory markers in sputum and systemic inflammatory mediators in plasma.

Exposure to air pollutants represents a risk factor not only for respiratory diseases and lung cancer, but also for cardiometabolic diseases. It has been hypothesised that local inflammation in the lung and systemic subclinical inflammation are linked by impaired lung function and the spill-over of proinflammatory factors from the lung into the circulation which could act as intermediaries between environmental exposures and disease risk. We wanted to investigate whether local and systemic inflammatory markers are associated, which would support the spill-over hypothesis. Sputum and plasma samples were obtained from 257 women of the German SALIA cohort. We performed immunoassays to measure multiple biomarkers of airway inflammation in sputum as well as cytokines, chemokines and soluble adhesion molecules in plasma. Correlations were calculated and adjusted for potentially confounding variables. Even though several significant associations were detected between inflammatory mediators in sputum and plasma, correlation coefficients were rather low ranging from r≥-0.20 to r≤0.20. Comparatively stronger associations were observed between nitrite, eosinophil cationic protein, leukotrienes C/D/E4 and interleukin-8 in sputum. Notably, correlations were positive with all proinflammatory biomarkers and interleukin-1 receptor antagonist in plasma, whereas negative correlations were observed with the anti-inflammatory adipokine adiponectin. In conclusion, local inflammation in the lung and systemic subclinical inflammation appear mainly independently regulated in elderly women from the general population. Although we found multiple significant correlations between inflammatory biomarkers in sputum and plasma, our results do not provide clear support for the spill-over hypothesis.

Air pollution and subclinical airway inflammation in the SALIA cohort study.

BACKGROUND: The association between long-term exposure to air pollution and local inflammation in the lung has rarely been investigated in the general population of elderly subjects before. We investigated this association in a population-based cohort of elderly women from Germany. METHODS: In a follow-up examination of the SALIA cohort study in 2008/2009, 402 women aged 68 to 79 years from the Ruhr Area and Borken (Germany) were clinically examined. Inflammatory markers were determined in exhaled breath condensate (EBC) and in induced sputum (IS). We used traffic indicators and measured air pollutants at single monitoring stations in the study area to assess individual traffic exposure and long-term air pollution background exposure. Additionally long-term residential exposure to air pollution was estimated using land-use regression (LUR) models. We applied multiple logistic and linear regression analyses adjusted for age, indoor mould, smoking, passive smoking and socio-economic status and additionally conducted sensitivity analyses. RESULTS: Inflammatory markers showed a high variability between the individuals and were higher with higher exposure to air pollution. NO derivatives, leukotriene (LT) B4 and tumour necrosis factor-α (TNF-α) showed the strongest associations. An increase of 9.42 µg/m3 (interquartile range) in LUR modelled NO2 was associated with measureable LTB4 level (level with values above the detection limit) in EBC (odds ratio: 1.38, 95% CI: 1.02 -1.86) as well as with LTB4 in IS (%-change: 19%, 95% CI: 7% - 32%). The results remained consistent after exclusion of subpopulations with risk factors for inflammation (smoking, respiratory diseases, mould infestation) and after extension of models with additional adjustment for season of examination, mass of IS and urban/rural living as sensitivity analyses. CONCLUSIONS: In this analysis of the SALIA study we found that long-term exposure to air pollutants from traffic and industrial sources was associated with an increase of several inflammatory markers in EBC and in IS. We conclude that long-term exposure to air pollution might lead to changes in the inflammatory marker profile in the lower airways in an elderly female population.

Serum Chemerin Concentrations Associate with Beta-Cell Function, but Not with Insulin Resistance in Individuals with Non-Alcoholic Fatty Liver Disease (NAFLD).

The novel adipokine chemerin has been related to insulin-resistant states such as obesity and non alcoholic fatty liver disease (NAFLD). However, its association with insulin resistance and beta cell function remains controversial. The main objective was to examine whether serum chemerin levels associate with insulin sensitivity and beta cell function independently of body mass index (BMI), by studying consecutive outpatients of the hepatology clinics of a European university hospital. Individuals (n=196) with NAFLD were stratified into persons with normal glucose tolerance (NGT; n=110), impaired glucose tolerance (IGT; n=51) and type 2 diabetes (T2D; n=35) and the association between serum chemerin and measures of insulin sensitivity and beta cell function as assessed during fasting and during oral glucose tolerance test (OGTT) was measured. Our results showed that serum chemerin positively associated with BMI (P=0.0007) and C peptide during OGTT (P<0.004), but not with circulating glucose, insulin, lipids or liver enzymes (all P>0.18). No BMI independent relationships of chemerin with fasting and OGTT derived measures of insulin sensitivity were found (P>0.5). Chemerin associated positively with fasting beta cell function as well as the OGTT derived insulinogenic index IGI_cp and the adaptation index after adjustment for age, sex and BMI (P=0.002-0.007), and inversely with the insulin/C peptide ratio (P=0.007). Serum chemerin neither related to the insulinogenic index IGI_ins nor the disposition index. In conclusion, circulating chemerin is likely linked to enhanced beta cell function but not to insulin sensitivity in patients with NAFLD.

Association between Advanced Glycation End Products and Impaired Fasting Glucose: Results from the SALIA Study.

Advanced glycation end products (AGEs) may contribute to the development of type 2 diabetes and related complications, whereas their role in the early deterioration of glycaemia is unknown. While previous studies used antibody-based methods to quantify AGEs, data from tandem mass spectrometry coupled liquid chromatography (LC-MS/MS)-based measurements are limited to patients with known diabetes. Here, we used the LC-MS/MS method to test the hypothesis that plasma AGE levels are higher in individuals with impaired fasting glucose (IFG) than in those with normal fasting glucose (NFG). Secondary aims were to assess correlations of plasma AGEs with quantitative markers of glucose metabolism and biomarkers of subclinical inflammation. This study included on 60 women with NFG or IFG (n = 30 each, mean age 74 years) from the German SALIA cohort. Plasma levels of free metabolites (3-deoxyfructose, 3-deoxypentosone, 3-deoxypentulose), two hydroimidazolones, oxidised adducts (carboxymethyllysine, carboxyethyllysine, methionine sulfoxide) and Nε-fructosyllysine were measured using LC-MS/MS. Plasma concentrations of all tested AGEs did not differ between the NFG and IFG groups (all p>0.05). Associations between plasma levels of AGEs and fasting glucose, insulin and HOMA-IR as a measure of insulin resistance were weak (r between -0.2 and 0.2, all p>0.05). The association between 3-deoxyglucosone-derived hydroimidazolone with several proinflammatory biomarkers disappeared upon adjustment for multiple testing. In conclusion, plasma AGEs assessed by LC-MS/MS were neither increased in IFG nor associated with parameters of glucose metabolism and subclinical inflammation in our study. Thus, these data argue against strong effects of AGEs in the early stages of deterioration of glucose metabolism.

Association between traffic-related air pollution, subclinical inflammation and impaired glucose metabolism: results from the SALIA study.

BACKGROUND: Environmental and lifestyle factors regulate the expression and release of immune mediators. It has been hypothesised that ambient air pollution may be such an external factor and that the association between air pollution and impaired glucose metabolism may be attributable to inflammatory processes. Therefore, we assessed the associations between air pollution, circulating immune mediators and impaired glucose metabolism. METHODS: We analysed concentrations of 14 pro- and anti-inflammatory immune mediators as well as fasting glucose and insulin levels in plasma of 363 women from the Study on the influence of Air pollution on Lung function, Inflammation and Aging (SALIA, Germany). Exposure data for a group of pollutants such as nitrogen oxides (NO2, NOx) and different fractions of particulate matter were available for the participants' residences. We calculated the association between the pollutants and impaired glucose metabolism by multiple regression models. RESULTS: The study participants had a mean age of 74.1 (SD 2.6) years and 48% showed impaired glucose metabolism based on impaired fasting glucose or previously diagnosed type 2 diabetes. Only long-term exposure NO2 and NOx concentrations showed positive associations (NO2: OR 1.465, 95% CI 1.049-2.046, NOx: OR 1.409, 95% CI 1.010-1.967) per increased interquartile range of NO2 (14.65 µg/m(3)) or NOx (43.16 µg/m(3)), respectively, but statistical significance was lost after correction for multiple comparisons. Additional adjustment for circulating immune mediators or the use of anti-inflammatory medication had hardly any impact on the observed ORs. CONCLUSIONS: Our results suggest that exposure to nitrogen oxides may contribute to impaired glucose metabolism, but the associations did not reach statistical significance so that further studies with larger sample sizes are required to substantiate our findings. Our data do not preclude a role of inflammatory mechanisms in adipose or other tissues which may not be reflected by immune mediators in plasma.