Airborne Benzo[a]Pyrene may contribute to divergent Pheno-Endotypes in children.

BACKGROUND: Asthma represents a syndrome for which our understanding of the molecular processes underlying discrete sub-diseases (i.e., endotypes), beyond atopic asthma, is limited. The public health needs to characterize etiology-associated endotype risks is becoming urgent. In particular, the roles of polyaromatic hydrocarbon (PAH), globally distributed combustion by-products, toward the two known endotypes - T helper 2 cell high (Th2) or T helper 2 cell low (non-Th2) - warrants clarification. OBJECTIVES: To explain ambient B[a]P association with non-atopic asthma (i.e., a proxy of non-Th2 endotype) is markedly different from that with atopic asthma (i.e., a proxy for Th2-high endotype). METHODS: In a case-control study, we compare the non-atopic as well as atopic asthmatic boys and girls against their respective controls in terms of the ambient Benzo[a]pyrene concentration nearest to their home, plasma 15-Ft2-isoprostane (15-Ft2-isoP), urinary 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG), and lung function deficit. We repeated the analysis for i) dichotomous asthma outcome and ii) multinomial asthma-overweight/obese (OV/OB) combined outcomes. RESULTS: The non-atopic asthma cases are associated with a significantly higher median B[a]P (11.16 ng/m3) compared to that in the non-atopic controls (3.83 ng/m3; P-value < 0.001). In asthma-OV/OB stratified analysis, the non-atopic girls with lean and OV/OB asthma are associated with a step-wisely elevated B[a]P (median,11.16 and 18.00 ng/m3, respectively), compared to the non-atopic lean control girls (median, 4.28 ng/m3, P-value < 0.001). In contrast, atopic asthmatic children (2.73 ng/m3) are not associated with a significantly elevated median B[a]P, compared to the atopic control children (2.60 ng/m3; P-value > 0.05). Based on the logistic regression model, on ln-unit increate in B[a]P is associated with 4.7-times greater odds (95% CI, 1.9-11.5, P = 0.001) of asthma among the non-atopic boys. The same unit increase in B[a]P is associated with 44.8-times greater odds (95% CI, 4.7-428.2, P = 0.001) among the non-atopic girls after adjusting for urinary Cotinine, lung function deficit, 15-Ft2-isoP, and 8-oxodG. CONCLUSIONS: Ambient B[a]P is robustly associated with non-atopic asthma, while it has no clear associations with atopic asthma among lean children. Furthermore, lung function deficit, 15-Ft2-isoP, and 8-oxodG are associated with profound alteration of B[a]P-asthma associations among the non-atopic children.

Greater susceptibility of girls to airborne Benzo[a]pyrene for obesity-associated childhood asthma.

BACKGROUND: Sexually dimorphic risk of obesity-associated asthma is posited to accelerate around puberty. Yet, the role of air pollution on the lean and obese asthmatic children has never been examined. OBJECTIVE: To compare whether a unit exposure to airborne benzo[a]pyrene (B[a]P) is associated with altered risks of asthma across the overweight/obese (OV/OB) control, lean asthmatic, and OV/OB asthmatic children, respectively, compared to the lean controls, before and after adjusting for oxidant stress markers (i.e. 15­F2t­IsoP, 8­oxo­dG, and Carbonyl). METHODS: Asthmatic and healthy control children, recruited from polluted urban and rural areas, were matched to ambient concentration of B[a]P. A unit increase in B[a]P and multinomial logistic regression on OV/OB control, lean asthmatic, and OV/OB asthma were compared across the sex- and age-groups. RESULTS: The median B[a]P was associated with a linear increase among the female children, according to OV/OB and asthma, respectively, and together, compared to the lean control girls (p = 0.001). While B[a]P was associated with positive relationship with 15­F2t­IsoP level among the OV/OB boys, the same exposure-outcome association was inverse among the OV/OB girls. One natural log-unit increase in ambient B[a]P was associated with 10.5-times greater odds (95% CI, 2.6-39.6; p = 0.001) the adolescent OV/OB boys, compared to the unit odds among the lean controls. In contrast, the adolescent OV/OB girls were associated with highest adjusted odds of the asthma (aOR = 15.4; 95% CI, 2.9-29.1; p < 0.001) compared to the lean control girls. An adjustment for 15­F2t­IsoP, and Carbonyls was associated with greater odds of asthma per unit exposure for the adolescent OV/OB girls (aOR = 16.2; 95% CI, 1.4-181.8; p = 0.024). CONCLUSIONS: B[a]P exposure was associated with a leap in the odds of asthma among the OV/OB adolescents, particularly the girls, after adjusting for 15­F2t­IsoP and Carbonyls.

Modeling Unobserved Heterogeneity in Susceptibility to Ambient Benzo[a]pyrene Concentration among Children with Allergic Asthma Using an Unsupervised Learning Algorithm.

Current studies of gene × air pollution interaction typically seek to identify unknown heritability of common complex illnesses arising from variability in the host's susceptibility to environmental pollutants of interest. Accordingly, a single component generalized linear models are often used to model the risk posed by an environmental exposure variable of interest in relation to a priori determined DNA variants. However, reducing the phenotypic heterogeneity may further optimize such approach, primarily represented by the modeled DNA variants. Here, we reduce phenotypic heterogeneity of asthma severity, and also identify single nucleotide polymorphisms (SNP) associated with phenotype subgroups. Specifically, we first apply an unsupervised learning algorithm method and a non-parametric regression to find a biclustering structure of children according to their allergy and asthma severity. We then identify a set of SNPs most closely correlated with each sub-group. We subsequently fit a logistic regression model for each group against the healthy controls using benzo[a]pyrene (B[a]P) as a representative airborne carcinogen. Application of such approach in a case-control data set shows that SNP clustering may help to partly explain heterogeneity in children's asthma susceptibility in relation to ambient B[a]P concentration with greater efficiency.

Altered vulnerability to asthma at various levels of ambient Benzo[a]Pyrene by CTLA4, STAT4 and CYP2E1 polymorphisms.

BACKGROUND: Within fossil- and solid-fuel dependent geographic locations, mechanisms of air pollution-induced asthma remains unknown. In particular, sources of greater genetic susceptibility to airborne carcinogen, namely, benzo[a]pyrene (B[a]P) has never been investigated beyond that of a few well known genes. OBJECTIVES: To deepen our understanding on how the genotypic variations within the candidate genes contribute to the variability in the children's susceptibility to ambient B[a]P on doctor-diagnosed asthma. METHODS: Clinically confirmed asthmatic versus healthy control children (aged, 7-15) were enrolled from historically polluted and rural background regions in Czech Republic. Contemporaneous ambient B[a]P concentration was obtained from the routine monitoring network. The sputum DNA was genotyped for 95 genes. B[a]P interaction with SNPs was studied by two-stage, semi-agnostic screening of 621 SNPs. RESULTS: The median B[a]P within the highly polluted urban center was 8-times higher than that in the background region (7.8 vs. 1.1 ng/m3) during the period of investigation. Within the baseline model, which considered B[a]P exposure-only, the second tertile range was associated with a significantly reduced odds (aOR = 0.28) of asthma (95% CI, 0.16 to 0.50) compared to those at the lowest range. However, the highest range of B[a]P was associated with 3.18-times greater odds of the outcome (95% CI, 1.77 to 5.71). Within the gene-environment interaction models, joint occurrence of a high B[a]P exposure range and having a high-risk genotype at CTLA4 gene (rs11571316) was associated with 9-times greater odds (95% CI, 4.56-18.36) of the asthma diagnosis. Similarly, rs11571319 at CTLA4 and a high B[a]P exposure range was associated with a 8-times greater odds (95% CI, 3.95-14.27) of asthma diagnosis. Furthermore, having TG + GG genotypes on rs1031509 near STAT4 was associated with 5-times (95% CI, 3.03-8.55) greater odds of asthma diagnosis at the highest B[a]P range, compared to the odds at the reference range. Also CYP2E1 AT + TT genotypes (rs2070673) was associated with 5-times (95% CI, 3.1-8.8) greater odds of asthma diagnosis at the highest B[a]P exposure. CONCLUSIONS: The children, who jointly experience a high B[a]P exposure (6.3-8.5 ng/m3) as well as susceptible genotypes in CTLA4 (rs11571316 and rs11571319), STAT4 (rs1031509), and CYP2E1 (rs2070673), respectively, are associated with a significantly greater odds of having doctor-diagnosed asthma, compared to those with neither risk factors.

Ultrafine and Fine Particles and Hospital Admissions in Central Europe. Results from the UFIREG Study.

RATIONALE: Evidence of short-term effects of ultrafine particles (UFP) on health is still inconsistent and few multicenter studies have been conducted so far especially in Europe. OBJECTIVES: Within the UFIREG project, we investigated the short-term effects of UFP and fine particulate matter (particulate matter with an aerodynamic diameter less than 2.5 µm [PM2.5]) on daily cause-specific hospital admissions in five Central and Eastern European cities using harmonized protocols for measurements and analyses. METHODS: Daily counts of cause-specific hospital admissions focusing on cardiovascular and respiratory diseases were obtained for Augsburg and Dresden (Germany), 2011-2012; Chernivtsi (Ukraine), 2013 to March 2014; and Ljubljana (Slovenia) and Prague (Czech Republic), 2012-2013. Air pollution and meteorologic data were measured at fixed monitoring sites in all cities. We analyzed city-specific associations using confounder-adjusted Poisson regression models and pooled the city-specific effect estimates using metaanalysis methods. MEASUREMENTS AND MAIN RESULTS: A 2,750 particles/cm3 increase (average interquartile range across all cities) in the 6-day average of UFP indicated a delayed and prolonged increase in the pooled relative risk of respiratory hospital admissions (3.4% [95% confidence interval, -1.7 to 8.8%]). We also found increases in the pooled relative risk of cardiovascular (exposure average of lag 2-5, 1.8% [0.1-3.4%]) and respiratory (6-d average exposure, 7.5% [4.9-10.2%]) admissions per 12.4 µg/m3 increase (average interquartile range) in PM2.5. CONCLUSIONS: Our findings indicated delayed and prolonged effects of UFP exposure on respiratory hospital admissions in Central and Eastern Europe. Cardiovascular and respiratory hospital admissions increased in association with an increase in PM2.5. Further multicenter studies are needed using harmonized UFP measurements to draw definite conclusions on health effects of UFP.

Impact of Air Pollution to Genome of Newborns.

The Northern Moravia Region is the most polluted region in the Czech Republic by particulate matter (PM2.5) and carcinogenic polycyclic aromatic hydrocarbons (c-PAHs) as benzo[a]pyrene (B[a]P) by heavy industry and local heating. This specific situation was used to study the impact of air pollution on newborns in the exposed Karviná district and control district of Ceské Budejovice. Biological material from newborns and mothers was collected in summer and winter seasons. This project is highly detailed, analyzing the concentrations of PAHs in ambient air and diet, in human breast milk, in the urine of mothers and newborns, using biomarkers of genetic damage as DNA adducts and gene expression analysis, biomarkers of oxidative stress as 8-oxodG adducts and lipid peroxidation (15-F2t-isoprostane immunoassay). All 400 children, for whom the biomarker data at delivery were obtained, will be followed for morbidity up to 2 years of age. The Northern Moravia Region seems to be to be a model area for studying the long-term impact of human health exposure to c-PAHs. Our observations will indicate possible genetic and oxidative damage in newborns, which may significantly affect their morbidity.

Air pollution and childhood bronchitis: Interaction with xenobiotic, immune regulatory and DNA repair genes.

BACKGROUND: Gene-environment interactions have been investigated for diseases such as asthma, chronic obstructive pulmonary disease, cancer etc. but acute disease like bronchitis has rarely been studied. We investigated interactions between air pollution (polycyclic aromatic hydrocarbons (PAH) and particulate matter <2.5 µm (PM2.5)) and single nucleotide polymorphisms (SNP) in EPHX1, IL10, STAT4 and XPC genes in relation to bronchitis in children aged 0-2 years. METHODS: A stratified random sample of 1133 Czech children, born between 1994 and 1998 in two districts, were followed since birth, of which 626 were genotyped. Pediatrician-diagnosed bronchitis episodes were obtained from the medical records. Central-site monitors measured air pollution exposure. We used multivariable logistic regression and estimated coefficients using generalized estimating equations. Interaction was assessed between pollutants and genes and associations in genotype-specific strata were presented. False discovery rate was used to adjust for multiple comparisons. RESULTS: There were 803 episodes of bronchitis with an incidence rate of 56 per 1000 child-months. We found significant gene-environment interaction between PAH and four SNPs (EPHX1, (rs2854461), STAT4 (rs16833215), XPC (rs2228001 and rs2733532)), which became non-significant after adjusting for multiple comparisons. PM2.5 interactions with two XPC SNPs (rs2228001 and rs2733532) remained significant after accounting for multiple comparisons and those with CC alleles had a more than doubling of odds, OR=2.65 (95% CI: 1.91, 3.69) and 2.72 (95% CI: 1.95, 3.78), respectively, per 25 µg/m(3) increase in exposure. CONCLUSION: The findings suggest that the DNA repair gene XPC may play an important role in the air pollution-induced pathogenesis of the inflammatory disease bronchitis.

Associations between ultrafine and fine particles and mortality in five central European cities - Results from the UFIREG study.

BACKGROUND: Evidence on health effects of ultrafine particles (UFP) is still limited as they are usually not monitored routinely. The few epidemiological studies on UFP and (cause-specific) mortality so far have reported inconsistent results. OBJECTIVES: The main objective of the UFIREG project was to investigate the short-term associations between UFP and fine particulate matter (PM)<2.5µm (PM2.5) and daily (cause-specific) mortality in five European Cities. We also examined the effects of PM<10µm (PM10) and coarse particles (PM2.5-10). METHODS: UFP (20-100nm), PM and meteorological data were measured in Dresden and Augsburg (Germany), Prague (Czech Republic), Ljubljana (Slovenia) and Chernivtsi (Ukraine). Daily counts of natural and cardio-respiratory mortality were collected for all five cities. Depending on data availability, the following study periods were chosen: Augsburg and Dresden 2011-2012, Ljubljana and Prague 2012-2013, Chernivtsi 2013-March 2014. The associations between air pollutants and health outcomes were assessed using confounder-adjusted Poisson regression models examining single (lag 0-lag 5) and cumulative lags (lag 0-1, lag 2-5, and lag 0-5). City-specific estimates were pooled using meta-analyses methods. RESULTS: Results indicated a delayed and prolonged association between UFP and respiratory mortality (9.9% [95%-confidence interval: -6.3%; 28.8%] increase in association with a 6-day average increase of 2750particles/cm(3) (average interquartile range across all cities)). Cardiovascular mortality increased by 3.0% [-2.7%; 9.1%] and 4.1% [0.4%; 8.0%] in association with a 12.4µg/m(3) and 4.7µg/m(3) increase in the PM2.5- and PM2.5-10-averages of lag 2-5. CONCLUSIONS: We observed positive but not statistically significant associations between prolonged exposures to UFP and respiratory mortality, which were independent of particle mass exposures. Further multi-centre studies are needed investigating several years to produce more precise estimates on health effects of UFP.

Oxidative stress in newborns by different modes of delivery.

OBJECTIVES: The aim of our study is to investigate the impact of the type of delivery - vaginal vs. cesarean section on oxidative damage determined as the lipid peroxidation (15-F2t-isoprostane (15-F2t-IsoP) in the cord blood of newborns and venous blood from mothers in two localities with different levels of air pollution: Ceske Budejovice (CB), a locality with a clean air, and Karvina, a locality with high air pollution. RESUTLS: In Karvina, the concentration of PM2.5 was higher than in CB in the summer 2013 (mean±SD: 20.41±6.28 vs. 9.45±3.62 µg/m3, p<0.001) and in the winter 2014 (mean±SD: 53.67±19.76 vs. 27.96±12.34 µg/m3, p<0.001). Similarly, the concentration of B[a]P was higher in Karvina than in CB in the summer 2013 (mean±SD: 1.16±0.91 vs. 0.16±0.26 ng/m3, p<0.001) and in the winter 2014 (5.36±3.64 vs. 1.45±1.19 ng/m3, p<0.001). Delivery procedures differed by the type of anesthesia; at the Cesarean section in CB was used general anesthesia in 73.8% vs. 20.8% in Karvina (p<0.001), epidural anesthesia in CB in 26.2% vs. 77.1% in Karvina (p<0.001), at vaginal delivery was local anesthesia used in CB in 58.9% vs. 14.1% in Karvina (p<0.001). In CB was oxidative stress higher after vaginal delivery (101.7±31.0 pg 15-F2t-isoP/ml plasma) vs. Cesarean section (83.9±26.9 pg 15-F2t-isoP/ml plasma, p<0.001), no difference between the type of delivery was observed in Karvina. CONCLUSION: No difference between the types of delivery was observed in mothers in CB as well as in Karvina. Oxidative stress in newborns in Karvina was significantly affected by the concentrations of PM2.5 and B[a]P in the polluted air.

[Health effects of ambient ultrafine particles--the project UFIREG]. / Vliv ultrajemných prachových cástic na zdraví--projekt UFIREG.

BACKGROUND: The project "Ultrafine particles--an evidence based contribution to the development of regional and European environmental and health policy" (UFIREG) started in July 2011 and ended in December 2014. It was implemented through the Central Europe Programme and co-financed by the European Regional Development Fund. Five cities in four Central European countries participated in the study: Augsburg (Germany), Chernivtsi (Ukraine), Dresden (Germany), Ljubljana (Slovenia) and Prague (Czech Republic). The aim of the UFIREG project was to improve the knowledge base on possible health effects of ambient ultrafine particles (UFP) and to raise overall awareness of environmental and health care authorities and the population. METHODS: Epidemiological studies in the frame of the UFIREG project have assessed the short-term effects of UFP on human mortality and morbidity, especially in relation to cardiovascular and respiratory diseases. Official statistics were used to determine the association between air pollution concentration and daily (cause-specific: respiratory and cardiovascular) hospital admissions and mortality. Associations of UFP levels and health effects were analysed for each city by use of Poisson regression models adjusting for a number of confounding factors. RESULTS: Results on morbidity and mortality effects of UFP were heterogeneous across the five European cities investigated. Overall, an increase in respiratory hospital admissions and mortality could be detected for increases in UFP concentrations. Results on cardiovascular health were less conclusive. CONCLUSION: Further multi-centre studies such as UFIREG are needed preferably investigating several years in order to produce powerful results.

Differences between the spectra of respiratory illnesses in children living in urban and rural environments.

A longitudinal study launched in 1994 within the framework of the Teplice Programme aimed at comparing the respiratory morbidity in children born (1994-1998) and living in the districts of Teplice (TE) and Prachatice (PRA) in the Czech Republic. Lists of all illnesses of 960 children from birth to 10 years of age were obtained from paediatric medical records. From 26,471 diagnoses (in ICD-10 codes), 34.7% were diagnoses of upper respiratory infections (URI, J00-02, J06), 11.3% of tonsillitis, 10.2% of influenza, 9.4% of bronchitis, 8.9% of laryngitis/tracheitis (J04), 2.7% of otitis media, and 0.5% of pneumonia. The more polluted district of Teplice was divided into two parts: the town itself (TE-town) and the rest of the district (TE-district). The cumulative incidence rates of the above respiratory illnesses per 100 children per 10 years were 2,212 in TE-town, 2,192 in PRA and 1,985 in TE-district. In the first two years of life, the children from TE-town had a significantly higher incidence of laryngitis/tracheitis, influenza, otitis media, and pneumonia and significantly lower incidence of bronchitis and tonsillitis than children living in PRA. The incidence rates of laryngitis/tracheitis and influenza in TE-town persisted as the highest among the three regions till the age of 10 years. The incidence rates of bronchitis (from the 1st to 5th year) and URI (from 4th to 10th year) were highest in children living in PRA. When compared to TE-town, children in TE-district had a higher incidence of upper respiratory infections (1-8 years) and lower incidence of bronchitis (6-8 years). Children in the district of Prachatice had a significantly higher prevalence of allergic rhinitis and a lower prevalence of wheezing than children in the district of Teplice. Thus, the three regions differed by the spectra of respiratory illnesses rather than by overall morbidity and, hypothetically, the effects of air pollution were obscurred by differences in the degree of urbanization.

Preterm birth, infant weight gain, and childhood asthma risk: a meta-analysis of 147,000 European children.

BACKGROUND: Preterm birth, low birth weight, and infant catch-up growth seem associated with an increased risk of respiratory diseases in later life, but individual studies showed conflicting results. OBJECTIVES: We performed an individual participant data meta-analysis for 147,252 children of 31 birth cohort studies to determine the associations of birth and infant growth characteristics with the risks of preschool wheezing (1-4 years) and school-age asthma (5-10 years). METHODS: First, we performed an adjusted 1-stage random-effect meta-analysis to assess the combined associations of gestational age, birth weight, and infant weight gain with childhood asthma. Second, we performed an adjusted 2-stage random-effect meta-analysis to assess the associations of preterm birth (gestational age <37 weeks) and low birth weight (<2500 g) with childhood asthma outcomes. RESULTS: Younger gestational age at birth and higher infant weight gain were independently associated with higher risks of preschool wheezing and school-age asthma (P < .05). The inverse associations of birth weight with childhood asthma were explained by gestational age at birth. Compared with term-born children with normal infant weight gain, we observed the highest risks of school-age asthma in children born preterm with high infant weight gain (odds ratio [OR], 4.47; 95% CI, 2.58-7.76). Preterm birth was positively associated with an increased risk of preschool wheezing (pooled odds ratio [pOR], 1.34; 95% CI, 1.25-1.43) and school-age asthma (pOR, 1.40; 95% CI, 1.18-1.67) independent of birth weight. Weaker effect estimates were observed for the associations of low birth weight adjusted for gestational age at birth with preschool wheezing (pOR, 1.10; 95% CI, 1.00-1.21) and school-age asthma (pOR, 1.13; 95% CI, 1.01-1.27). CONCLUSION: Younger gestational age at birth and higher infant weight gain were associated with childhood asthma outcomes. The associations of lower birth weight with childhood asthma were largely explained by gestational age at birth.

Comparison of child morbidity in regions of Ostrava, Czech Republic, with different degrees of pollution: a retrospective cohort study.

BACKGROUND: To confirm or refute the hypothesis that the morbidity of children (since birth to age 5) born and living in the heavily polluted (PM10, benzo[a]pyrene) eastern part of Ostrava, Czech Republic, was higher than the morbidity of children living in other parts of the city. METHODS: Ten pediatricians in 5 districts of Ostrava abstracted the medical records of 1878 children born in 2001-2004 to list all illnesses of each child in ICD-10 codes. The children were divided into four groups according to their residence at birth and thereafter. Most of the children in the eastern area were living in the city district Radvanice and Bartovice. RESULTS: We report on the incidence of acute illnesses in 1535 children of Czech ethnicity in the first 5 years of life. The most frequent acute illnesses (over 45% of all diagnoses) were upper respiratory infections (URI: J00-J02, J06). In the first year of life, the incidence of URI in 183 children in the eastern area - 372 illnesses/100 children/year - was more than twice as high as in the other 3 areas with a total number of 1352 children. From birth to the age of 5 years, the incidences of pneumonia, tonsillitis, viral infections (ICD-10 code B34) and intestinal infectious diseases were also several times higher in children living in the eastern part of Ostrava. The lowest morbidity was found in children living in the less polluted western part of the city. CONCLUSIONS: The children born and living in the eastern part of the city of Ostrava had from birth through 5 years significantly higher incidence rates of acute illnesses than children in other parts of Ostrava. They also had a higher prevalence of wheezing, atopic dermatitis and allergic rhinitis.

Air pollutants, genes and early childhood acute bronchitis.

BACKGROUND: Studies have reported gene-by-environment interaction for chronic respiratory conditions but none on acute illnesses in children. We investigated, longitudinally, whether genotype modifies the relationship of environmental exposures (second-hand tobacco smoke, polycyclic aromatic hydrocarbons, particulate matter <2.5µm (PM2.5)) with acute bronchitis in children below two years. METHODS: A random sample of 1133 children, born between 1994 and 1998, in two districts of the Czech Republic, was followed-up from birth, of which 793 were genotyped. Pediatric records were abstracted for respiratory illnesses. Second-hand tobacco smoke exposure from household members was obtained through questionnaires and verified using urine cotinine. Air monitoring provided estimates of ambient polycyclic aromatic hydrocarbons and PM2.5. Additionally, we collected information on a range of potential confounders including breastfeeding history, indoor fuel use, other children in household, maternal characteristics, ambient temperature etc. DNA was extracted from tissues taken from the middle of the placenta, opposite the umbilical cord. We examined six single nucleotide polymorphisms (GSTM1, GSTP1, GSTT1, CYP1A1 MspI, EPHX1 exon 3 and 4) and one (EPHX1) diplotype. To investigate effect measure modification we constructed logistic regression models using generalized estimating equations (for repeated observations) stratified by genotypes. RESULTS: The EPHX1 low activity diplotype consistently imparts greater susceptibility to bronchitis from second-hand tobacco smoke, polyclic aromatic hydrocarbons (PAH) and PM2.5. Each of these three classes of exposure also showed elevated risk for bronchitis in the presence of either one or two histidines at exon 3 and exon 4 of EPHX1. Additional effect modifiers include CYP1A1 and GSTT1. CONCLUSION: Several xenobiotic metabolizing genes may modify the impact of second-hand tobacco smoke and ambient air pollutants, polycyclic aromatic hydrocarbons and PM2.5, on acute bronchitis in preschool children.

Factors affecting the 27K DNA methylation pattern in asthmatic and healthy children from locations with various environments.

Gene expression levels are significantly regulated by DNA methylation. Differences in gene expression profiles in the populations from various locations with different environmental conditions were repeatedly observed. In this study we compare the methylation profiles in 200 blood samples of children (aged 7-15 years) with and without bronchial asthma from two regions in the Czech Republic with different levels of air pollution (a highly polluted Ostrava region and a control Prachatice region). Samples were collected in March 2010 when the mean concentrations of benzo[a]pyrene (B[a]P) measured by stationary monitoring were 10.1±2.4ng/m(3) in Ostrava Bartovice (5.6 times higher than in the control region). Significantly higher concentrations of other pollutants (benzene, NO2, respirable air particles and metals) were also found in Ostrava. We applied the Infinium Methylation Assay, using the Human Methylation 27K BeadChip with 27,578 CpG loci for identification of the DNA methylation pattern in studied groups. Results demonstrate a significant impact of different environmental conditions on the DNA methylation patterns of children from the two regions. We found 9916 CpG sites with significantly different methylation (beta value) between children from Ostrava vs. Prachatice from which 58 CpG sites had differences >10%. The methylation of all these 58 CpG sites was lower in children from polluted Ostrava, which indicates a higher gene expression in comparison with the control Prachatice region. We did not find a difference in DNA methylation patterns between children with and without bronchial asthma in individual locations, but patterns in both asthmatics and healthy children differed between Ostrava and Prachatice. Further, we show differences in DNA methylation pattern depending on gender and urinary cotinine levels. Other factors including length of gestation, birth weight and length of full breastfeeding are suggested as possible factors that can impact the DNA methylation pattern in future life.

Health impact of air pollution to children.

Health impact of air pollution to children was studied over the last twenty years in heavily polluted parts of the Czech Republic during. The research program (Teplice Program) analyzed these effects in the polluted district Teplice (North Bohemia) and control district Prachatice (Southern Bohemia). Study of pregnancy outcomes for newborns delivered between 1994 and 1998 demonstrated that increase in intrauterine growth retardation (IUGR) was associated with PM10 and c-PAHs exposure (carcinogenic polycyclic aromatic hydrocarbons) in the first month of gestation. Morbidity was followed in the cohort of newborns (N=1492) up to the age of 10years. Coal combustion in homes was associated with increased incidence of lower respiratory track illness and impaired early childhood skeletal growth up to the age of 3years. In preschool children, we observed the effect of increased concentrations of PM2.5 and PAHs on development of bronchitis. The Northern Moravia Region (Silesia) is characterized by high concentrations of c-PAHs due to industrial air pollution. Exposure to B[a]P (benzo[a]pyrene) in Ostrava-Radvanice is the highest in the EU. Children from this part of the city of Ostrava suffered higher incidence of acute respiratory diseases in the first year of life. Gene expression profiles in leukocytes of asthmatic children compared to children without asthma were evaluated in groups from Ostrava-Radvanice and Prachatice. The results suggest the distinct molecular phenotype of asthma bronchiale in children living in polluted Ostrava region compared to children living in Prachatice. The effect of exposure to air pollution to biomarkers in newborns was analyzed in Prague vs. Ceske Budejovice, two locations with different levels of pollution in winter season. B[a]P concentrations were higher in Ceske Budejovice. DNA adducts and micronuclei were also elevated in cord blood in Ceske Budejovice in comparison to Prague. Study of gene expression profiles in the cord blood showed differential expression of 104 genes. Specifically, biological processes related to immune and defense response were down-regulated in Ceske Budejovice. Our studies demonstrate that air pollution significantly affect child health. Especially noticeable is the increase of respiratory morbidity. With the development of molecular epidemiology, we can further evaluate the health risk of air pollution using biomarkers.

Ambient nitrogen oxides exposure and early childhood respiratory illnesses.

Acute respiratory infections are common in children below 5 years and recent studies suggest a possible link with air pollution. In this study, we investigated the association between ambient nitrogen oxides (NO(x)) and bronchitis or upper airway inflammation. This longitudinal study was conducted in Teplice and Prachatice districts, Czech Republic. Children were followed from birth to 4.5 years of age. Data were compiled from medical records at delivery and at follow up, and from self-administered questionnaires from the same two time points. Air pollution monitoring data were used to estimate exposure over five different averaging periods ranging from three to 45 days prior to an episode. To quantify the association between exposure and outcome, while accounting for repeated measure correlation we conducted logistic regression analysis using generalized estimating equations. During the first 2 years of life, the adjusted rate ratio for bronchitis associated with interquartile increase in the 30-day average NO(x) was 1.31 [95% confidence interval (CI): 1.07, 1.61] and for two to 4.5 year olds, it was 1.23 (95% CI: 1.01, 1.49). The 14-day exposure also had stable association across both age groups: below 2 years it was 1.25 (95% CI: 1.06, 1.47) and for two to 4.5 years it was 1.21 (95% CI: 1.06, 1.39). The association between bronchitis and NO(x) increased with child's age in the under 2 years group, which is a relatively novel finding. The results demonstrate an association between NO(x) and respiratory infections that are sufficiently severe to come to medical attention. The evidence, if causal, can be of public health concern because acute respiratory illnesses are common in preschool children.