Assessing secondhand and thirdhand tobacco smoke exposure in Canadian infants using questionnaires, biomarkers, and machine learning.

BACKGROUND: As smoking prevalence has decreased in Canada, particularly during pregnancy and around children, and technological improvements have lowered detection limits, the use of traditional tobacco smoke biomarkers in infant populations requires re-evaluation. OBJECTIVE: We evaluated concentrations of urinary nicotine biomarkers, cotinine and trans-3'-hydroxycotinine (3HC), and questionnaire responses. We used machine learning and prediction modeling to understand sources of tobacco smoke exposure for infants from the CHILD Cohort Study. METHODS: Multivariable linear regression models, chosen through a combination of conceptual and data-driven strategies including random forest regression, assessed the ability of questionnaires to predict variation in urinary cotinine and 3HC concentrations of 2017 3-month-old infants. RESULTS: Although only 2% of mothers reported smoking prior to and throughout their pregnancy, cotinine and 3HC were detected in 76 and 89% of the infants' urine (n = 2017). Questionnaire-based models explained 31 and 41% of the variance in cotinine and 3HC levels, respectively. Observed concentrations suggest 0.25 and 0.50 ng/mL as cut-points in cotinine and 3HC to characterize SHS exposure. This cut-point suggests that 23.5% of infants had moderate or regular smoke exposure. SIGNIFICANCE: Though most people make efforts to reduce exposure to their infants, parents do not appear to consider the pervasiveness and persistence of secondhand and thirdhand smoke. More than half of the variation in urinary cotinine and 3HC in infants could not be predicted with modeling. The pervasiveness of thirdhand smoke, the potential for dermal and oral routes of nicotine exposure, along with changes in public perceptions of smoking exposure and risk warrant further exploration.

Factors associated with breast-feeding initiation and continuation in Canadian-born and non-Canadian-born women: a multi-centre study.

OBJECTIVE: To identify factors associated with breast-feeding initiation and continuation in Canadian-born and non-Canadian-born women. DESIGN: Prospective cohort of mothers and infants born from 2008 to 2012: the Canadian Healthy Infant Longitudinal Development (CHILD) Cohort Study. SETTING: General community setting in four Canadian provinces. PARTICIPANTS: In total, 3455 pregnant women from Vancouver, Edmonton, Winnipeg and Toronto between 2008 and 2012. RESULTS: Of 3010 participants included in the current study, the majority were Canadian-born (75·5 %). Breast-feeding initiation rates were high in both non-Canadian-born (95·5 %) and Canadian-born participants (92·7 %). The median breast-feeding duration was 10 months in Canadian-born participants and 11 months in non-Canadian-born participants. Among Canadian-born participants, factors associated with breast-feeding initiation and continuation were older maternal age, higher maternal education, living with their partner and recruitment site. Rooming-in during the hospital stay was also associated with higher rates of breast-feeding initiation, but not continuation at 6-month postpartum. Factors associated with non-initiation of breast-feeding and cessation at 6-month postpartum were maternal smoking, living with a current smoker, caesarean birth and early-term birth. Among non-Canadian-born participants, maternal smoking during pregnancy was associated with lower odds of breast-feeding initiation and lower odds of breast-feeding continuation at 6 months, and older maternal age and recruitment site were associated with breast-feeding continuation at 6 months. CONCLUSIONS: Although Canadian-born and non-Canadian-born women in the CHILD cohort have similar breast-feeding initiation rates, breast-feeding initiation and continuation are more strongly associated with socio-demographic characteristics in Canadian-born participants. Recruitment site was strongly associated with breast-feeding continuation in both groups and may indicate geographic disparities in breast-feeding rates nationally.

Quantifying Human Innate Cytokine and Chemokine Responses Ex Vivo via Pattern Recognition Receptor Stimulation.

Linkages between human innate immune capacity, the environment in which we live, and the development of clinical tolerance versus a spectrum of disease phenotypes are a major focus of inflammatory disease research. While extensive epidemiologic evidence indicates key roles for the microbiome and other environmental factors, the underlying mechanisms that explain how these stimuli lead to a given clinical phenotype remain speculative. Here we review strategies for characterizing human cytokine production ex vivo in response to innate immune receptor stimulation with defined ligands. Human cytokine and chemokine biomarker data provides a tool to test hypotheses on the relationship between innate immune capacity in vivo and expression of current or future clinical phenotypes. The most important limitations of experimental strategies that have been used to date are reviewed. Detailed experimental protocols are provided for characterization of pattern recognition receptor (PRR)-driven stimulation with a panel of bacterial (TLR4, TLR5) and viral (TLR3, TLR7/8, RIG-I/MDA5) ligands to assess the role played by human pro-inflammatory, anti-inflammatory, Th1-like, and Th2-like responses. The importance of characterizing human innate immune phenotypes extends beyond discovery-based research to development of improved strategies for prevention or inhibition of chronic inflammatory diseases, improved design of immunization programs, and more effective cancer immunotherapy.

Maternal Metabolic Complications in Pregnancy and Offspring Behavior Problems at 2 Years of Age.

Objectives Prenatal maternal metabolic problems such as pre-pregnancy adiposity, excess gestational weight gain, and gestational diabetes mellitus (GDM) are associated with an increased risk of psychopathology in offspring. We examined whether these exposures were linked to symptoms of emotional and behavioral problems in offspring at 2 years of age, or if associations were due to confounding variables. Methods Data from 815 mother-child pairs enrolled at the Edmonton site of the Canadian Healthy Infant Longitudinal Development cohort were used to examine associations between gestational metabolic complications and scores on the externalizing and internalizing scales of the Child Behavior Checklist (CBCL-1½ to 5) at age two. Associations between maternal metabolic complications and offspring psychopathology were assessed before and after adjustment for gestational diet, socioeconomic status (SES), postpartum depression (PPD), prenatal smoking and breastfeeding. Results Pre-pregnancy body mass index and GDM, but not gestational weight gain, predicted more offspring externalizing and internalizing problems. However, after adjustment for confounding variables, these associations were no longer statistically significant. Post-hoc analyses revealed that gestational diet accounted for unique variance in both externalizing (semi-partial rdiet = - 0.20, p < 0.001) and internalizing (semi-partial rdiet = - 0.16, p = 0.01) problems. PPD and SES also accounted for a similar amount of variance for both externalizing (semi-partial rPPD = 0.17, p < 0.001; rses = - 0.11, p = 0.03) and internalizing problems (semi-partial rPPD = 0.21, p < 0.001; rses = - 0.14, p = 0.004). Conclusions for Practice Since the confounding effect of gestational diet persisted after adjustment for, and was similar in magnitude to, SES and PPD, future research should consider the impact of unhealthy prenatal diets on offspring neurodevelopment.

Phenotypes of sleep-disordered breathing symptoms to two years of age based on age of onset and duration of symptoms.

OBJECTIVE: Childhood sleep-disordered breathing (SDB) symptoms may comprise multiple phenotypes depending on craniofacial anatomy, tonsil and adenoid growth, body habitus, and rhinitis symptoms. The primary objective of this study is to identify and characterize the different SDB phenotypes to two years of age. METHODS: Data from 770 infants in the Edmonton sub-cohort of the Canadian Healthy Infant Longitudinal Study (CHILD) were analyzed to identify SDB phenotypes based on age of onset and duration of symptoms. Parents completed the 22-item sleep-related breathing disorder (SRBD) scale. Children with a SRBD ratio greater than 0.33 were considered positive for SDB at each quarterly assessment between three months and two years. The STATA Proc trajectory extension identified SDB phenotypes based on their age of onset and duration of symptoms and attributed the percentage chance of a participant being assigned to each phenotype. Multivariate linear regression identified factors associated with increased risk of being assigned to each SDB phenotype. RESULTS: Trajectory analysis identified four phenotypes: no SDB (65.7%), early-onset SDB (15.7%) with peak symptoms at nine months, late-onset SDB (14.2%) with peak symptoms at 18 months, and persistent SDB (5.3%) with symptoms from 3 to 24 months. Rhinitis was associated with all three SDB symptom trajectories (p < 0.05). Children with gastroesophageal reflux disease presented with early (p = 0.03) and late SDB (p < 0.001). Maternal obstructive sleep apnea syndrome (OSAS) was associated with persistent (p = 0.01) and late SDB (p < 0.001). Atopy (positive skin prick test at one year) was associated with persistent SDB (p = 0.04). Infants born prior to 36.5 weeks gestational age were more likely to present with late SDB (p = 0.03). CONCLUSION: Childhood SDB symptoms, rather than being a homogenous disorder, may comprise multiple overlapping phenotypes each with unique risk factors.

Ventilation inhomogeneity in infants with recurrent wheezing.

BACKGROUND: The care of infants with recurrent wheezing relies largely on clinical assessment. The lung clearance index (LCI), a measure of ventilation inhomogeneity, is a sensitive marker of early airway disease in children with cystic fibrosis, but its utility has not been explored in infants with recurrent wheezing. OBJECTIVE: To assess ventilation inhomogeneity using LCI among infants with a history of recurrent wheezing compared with healthy controls. METHODS: This is a case-control study, including 37 infants with recurrent wheezing recruited from outpatient clinics, and 113 healthy infants from a longitudinal birth cohort, the Canadian Healthy Infant Longitudinal Development study. All infants, at a time of clinical stability, underwent functional assessment including multiple breath washout, forced expiratory flows and body plethysmography. RESULTS: LCI z-score values among infants with recurrent wheeze were 0.84 units (95% CI 0.41 to 1.26) higher than healthy infants (mean (95% CI): 0.26 (-0.11 to 0.63) vs -0.58 (-0.79 to 0.36), p<0.001)). Nineteen percent of recurrently wheezing infants had LCI values that were above the upper limit of normal (>1.64 z-scores). Elevated exhaled nitric oxide, but not symptoms, was associated with abnormal LCI values in infants with recurrent wheeze (p=0.05). CONCLUSIONS: Ventilation inhomogeneity is present in clinically stable infants with recurrent wheezing.

Breastfeeding, maternal asthma and wheezing in the first year of life: a longitudinal birth cohort study.

The impact of breastfeeding on respiratory health is uncertain, particularly when the mother has asthma. We examined the association of breastfeeding and wheezing in the first year of life.We studied 2773 infants from the Canadian Healthy Infant Longitudinal Development (CHILD) birth cohort. Caregivers reported on infant feeding and wheezing episodes at 3, 6 and 12 months. Breastfeeding was classified as exclusive, partial (supplemented with formula or complementary foods) or none.Overall, 21% of mothers had asthma, 46% breastfed for at least 12 months and 21% of infants experienced wheezing. Among mothers with asthma, breastfeeding was inversely associated with infant wheezing, independent of maternal smoking, education and other risk factors (adjusted rate ratio (aRR) 0.52; 95% CI 0.35-0.77 for ≥12 versus <6 months breastfeeding). Compared with no breastfeeding at 6 months, wheezing was reduced by 62% with exclusive breastfeeding (aRR 0.38; 95% CI 0.20-0.71) and by 37% with partial breastfeeding supplemented with complementary foods (aRR 0.63; 95% CI 0.43-0.93); however, breastfeeding was not significantly protective when supplemented with formula (aRR 0.89; 95% CI 0.61-1.30). Associations were not significant in the absence of maternal asthma (p-value for interaction <0.01).Breastfeeding appears to confer protection against wheezing in a dose-dependent manner among infants born to mothers with asthma.

Harmonization of Food-Frequency Questionnaires and Dietary Pattern Analysis in 4 Ethnically Diverse Birth Cohorts.

BACKGROUND: Canada is an ethnically diverse nation, which introduces challenges for health care providers tasked with providing evidence-based dietary advice. OBJECTIVES: We aimed to harmonize food-frequency questionnaires (FFQs) across 4 birth cohorts of ethnically diverse pregnant women to derive robust dietary patterns to investigate maternal and newborn outcomes. METHODS: The NutriGen Alliance comprises 4 prospective birth cohorts and includes 4880 Canadian mother-infant pairs of predominantly white European [CHILD (Canadian Healthy Infant Longitudinal Development) and FAMILY (Family Atherosclerosis Monitoring In earLY life)], South Asian [START (SouTh Asian birth cohoRT)-Canada], or Aboriginal [ABC (Aboriginal Birth Cohort)] origins. CHILD used a multiethnic FFQ based on a previously validated instrument designed by the Fred Hutchinson Cancer Research Center, whereas FAMILY, START, and ABC used questionnaires specifically designed for use in white European, South Asian, and Aboriginal people, respectively. The serving sizes and consumption frequencies of individual food items within the 4 FFQs were harmonized and aggregated into 36 common food groups. Principal components analysis was used to identify dietary patterns that were internally validated against self-reported vegetarian status and externally validated against a modified Alternative Healthy Eating Index (mAHEI). RESULTS: Three maternal dietary patterns were identified-"plant-based," "Western," and "health-conscious"-which collectively explained 29% of the total variability in eating habits observed in the NutriGen Alliance. These patterns were strongly associated with self-reported vegetarian status (OR: 3.85; 95% CI: 3.47, 4.29; r2 = 0.30, P < 0.001; for a plant-based diet), and average adherence to the plant-based diet was higher in participants in the fourth quartile of the mAHEI than in the first quartile (mean difference: 46.1%; r2 = 0.81, P < 0.001). CONCLUSION: Dietary data collected by using FFQs from ethnically diverse pregnant women can be harmonized to identify common dietary patterns to investigate associations between maternal dietary intake and health outcomes.

Cognitive Enhancement in Infants Associated with Increased Maternal Fruit Intake During Pregnancy: Results from a Birth Cohort Study with Validation in an Animal Model.

In-utero nutrition is an under-studied aspect of cognitive development. Fruit has been an important dietary constituent for early hominins and humans. Among 808 eligible CHILD-Edmonton sub-cohort subjects, 688 (85%) had 1-year cognitive outcome data. We found that each maternal daily serving of fruit (sum of fruit plus 100% fruit juice) consumed during pregnancy was associated with a 2.38 point increase in 1-year cognitive development (95% CI 0.39, 4.37; p<0.05). Consistent with this, we found 30% higher learning Performance index (PI) scores in Drosophila offspring from parents who consumed 30% fruit juice supplementation prenatally (PI: 85.7; SE 1.8; p<0.05) compared to the offspring of standard diet parents (PI: 65.0 SE 3.4). Using the Drosophila model, we also show that the cyclic adenylate monophosphate (cAMP) pathway may be a major regulator of this effect, as prenatal fruit associated cognitive enhancement was blocked in Drosophila rutabaga mutants with reduced Ca(2+)-Calmodulin-dependent adenylyl cyclase. Moreover, gestation is a critical time for this effect as postnatal fruit intake did not enhance cognitive performance in either humans or Drosophila. Our study supports increased fruit consumption during pregnancy with significant increases in infant cognitive performance. Validation in Drosophila helps control for potential participant bias or unmeasured confounders.

Association of maternal diabetes and child asthma.

BACKGROUND: Perinatal programming is an emerging theory for the fetal origins of chronic disease. Maternal asthma and environmental tobacco smoke (ETS) are two of the best-known triggers for the perinatal programming of asthma, while the potential role of maternal diabetes has not been widely studied. OBJECTIVE: To determine if maternal diabetes is associated with child asthma, and if so, whether it modifies the effects of ETS exposure and maternal asthma. METHODS: We studied 3,574 Canadian children, aged 7-8 years, enrolled in a population-based birth cohort. Standardized questionnaires were completed by the children's parents, and data were analyzed by multivariable logistic regression. RESULTS: Asthma was reported in 442 children (12.4%). Compared to those without asthma, asthmatic children were more likely to have mothers (P = 0.003), but not fathers (P = 0.89), with diabetes. Among children without maternal history of diabetes, the likelihood of child asthma was 1.4-fold higher in those exposed to ETS (adjusted odds ratio, 1.40; 95% confidence interval, 1.13-1.73), and 3.6-fold higher in those with maternal asthma (3.59; 2.71-4.76). Among children born to diabetic mothers, these risks were amplified to 5.7-fold (5.68; 1.18-27.37) and 11.3-fold (11.30; 2.26-56.38), respectively. In the absence of maternal asthma or ETS, maternal diabetes was not associated with child asthma (0.65, 0.16-2.56). CONCLUSION: Our findings suggest that maternal diabetes may contribute to the perinatal programming of child asthma by amplifying the detrimental effects of ETS exposure and maternal asthma.

Cotinine versus questionnaire: early-life environmental tobacco smoke exposure and incident asthma.

BACKGROUND: The use of biomarkers has expanded considerably, as an alternative to questionnaire-based metrics of environmental tobacco smoke (ETS); few studies have assessed the affect of such alternative metrics on diverse respiratory outcomes in children, and we aimed to do so. METHODS: We evaluated various measures of birth-year ETS, in association with multiple respiratory endpoints early years of life, in the novel context of a birth cohort at high risk for asthma. We administered questionnaires to parents, both at the end of pregnancy and at one year of life, and measured cotinine in cord blood (CCot; in 275 children) and in urine (UCot; obtained at 12 months in 365 children), each by radioimmunoassay. Multiple logistic regression was used to assess the association of the various metrics with recurrent wheeze at age 2 and with bronchial hyperresponsiveness (BHR) and asthma at age 7. RESULTS: Self-reported 3rd trimester maternal smoking was associated with significantly increased risk for recurrent wheeze at age 2 (odds ratio 3.5 [95% confidence interval = 1.2,10.7]); the risks associated with CCot and 3rd trimester smoking in any family member were similar (OR 2.9 [1.2,7.0] and 2.6 [1.0,6.5], respectively). No metric of maternal smoking at 12 months appeared to significantly influence the risk of recurrent wheeze at age 2, and no metric of ETS at any time appeared to significantly influence risk of asthma or BHR at age 7. CONCLUSIONS: Biomarker- and questionnaire-based assessment of ETS in early life lead to similar estimates of ETS-associated risk of recurrent wheeze and asthma.

Influence of socioeconomic status trajectories on innate immune responsiveness in children.

OBJECTIVES: Lower socioeconomic status (SES) is consistently associated with poor health, yet little is known about the biological mechanisms underlying this inequality. In children, we examined the impact of early-life SES trajectories on the intensity of global innate immune activation, recognizing that excessive activation can be a precursor to inflammation and chronic disease. METHODS: Stimulated interleukin-6 production, a measure of immune responsiveness, was analyzed ex vivo for 267 Canadian schoolchildren from a 1995 birth cohort in Manitoba, Canada. Childhood SES trajectories were determined from parent-reported housing data using a longitudinal latent-class modeling technique. Multivariate regression was conducted with adjustment for potential confounders. RESULTS: SES was inversely associated with innate immune responsiveness (p=0.003), with persistently low-SES children exhibiting responses more than twice as intense as their high-SES counterparts. Despite initially lower SES, responses from children experiencing increasing SES trajectories throughout childhood were indistinguishable from high-SES children. Low-SES effects were strongest among overweight children (p<0.01). Independent of SES trajectories, immune responsiveness was increased in First Nations children (p<0.05) and urban children with atopic asthma (p<0.01). CONCLUSIONS: These results implicate differential immune activation in the association between SES and clinical outcomes, and broadly imply that SES interventions during childhood could limit or reverse the damaging biological effects of exposure to poverty during the preschool years.

Disparate geographic prevalences of asthma, allergic rhinoconjunctivitis and atopic eczema among adolescents in five Canadian cities.

To assess concordance of prevalence rates of asthma, allergic rhinoconjunctivitis and atopic eczema symptoms among adolescents in five Canadian cities. The International Study of Asthma and Allergies in Childhood Phase 3 written questionnaires were answered by 8334 adolescents aged 13 to 14 in Vancouver, Saskatoon, Winnipeg, Hamilton and Halifax, Canada. Prevalence rates of current symptoms ranged from 13.7-33.0% for wheezing, 14.6-22.6% for allergic rhinoconjunctivitis and 8.2-10.4% for atopic eczema. Using Hamilton as reference, the prevalence of wheezing was significantly higher in Halifax (OR = 1.58; 95% CI 1.36-1.84) and Saskatoon (1.27; 1.07-1.50) and significantly lower in Vancouver (0.51; 0.44-0.59). In contrast, allergic rhinoconjunctivitis was significantly more prevalent in Winnipeg (1.39; 1.16-1.68) and Halifax (1.36; 1.14-1.61) and trended lower in Saskatoon (0.81; 0.66-1.00). Atopic eczema was significantly more prevalent in Winnipeg (1.31; 1.01-1.69) and Vancouver (1.28; 1.04-1.58). Multivariable logistic regression analyses showed the region of residence, being born in Canada, recent use of acetaminophen and heavy exposure to traffic exhaust were significantly associated with all three allergic conditions, while obesity and having two or more smokers at home was only associated with increased risk for wheezing. Chinese ethnicity decreased that risk. Among five Canadian centres, the highest prevalence rates of allergic rhinoconjunctivitis or atopic eczema were not observed in the same regions as the highest prevalence rates of wheezing. This disparity in regional variations in the prevalence rates suggests dissimilar risk factors for the development or expression of wheezing (asthma), allergic rhinoconjunctivitis and atopic eczema.

Small-group, interactive education and the effect on asthma control by children and their families.

BACKGROUND: Effective approaches to education about asthma need to be identified. We evaluated the impact on asthma control by children and their caregivers of an intervention involving small-group, interactive education about asthma. METHODS: We randomly assigned children who visited an emergency department for an exacerbation of asthma (n = 398) to either of 2 groups. Children assigned to the control group followed the usual care recommended by their primary care physician. Those assigned to the intervention group participated in a small-group, interactive program of education about asthma. We examined changes in the number of visits to the emergency department during the year after the intervention. RESULTS: During the year after enrolment, children in the intervention group made significantly fewer visits to the emergency department (0.45 visits per child) compared with those in the control group (0.75 visits per child) (p = 0.004). The likelihood of a child in the intervention group requiring emergency care was reduced by 38% (relative risk [RR] 0.62, 95% confidence interval CI 0.48-0.81, p = 0.004). Fewer courses of oral corticosteroids (0.63 per child) were required by children in the intervention group than by those in the control group (0.85 per child) (p = 0.006). We observed significant improvements in the symptom domain of the questionnaire on pediatric asthma quality-of-life (p = 0.03) and the activity domain of the questionnaire on caregivers' quality of life (p = 0.05). Parents of children in the intervention group missed less work because of their child's asthma after participating in the educational program (p = 0.04). No impact on hospital admissions was observed. INTERPRETATION: Education about asthma, especially in a small-group, interactive format, improved clinically important outcomes and overall care of children with asthma.

Asthma is not enough: continuation of smoking among parents with an asthmatic child.

BACKGROUND: Ideally, on diagnosis of asthma in a child, parents are counselled to decrease environmental tobacco smoke exposure to their children. OBJECTIVE: To determine whether a diagnosis of asthma in children altered parental smoking behaviour toward a reduction in environmental tobacco smoke exposure. METHODS: In 2002/2003, a survey was sent to 12,556 households with children born in 1995 in Manitoba. Parents were asked whether their seven-year-old child had asthma, and whether smokers were present in the home in 1995 and/or currently. The likelihood (OR) of a change in parental smoking behaviour was determined according to the presence of asthma in their child, a family history of asthma, the location of residence (rural or urban) and their socioeconomic status. RESULTS: A total of 3580 surveys (28.5%) were returned. The overall prevalence of parental smoking in 1995 and 2002/2003 was 32.2% and 23.4%, respectively (31.9%/23.2% and 32.3%/23.6% in rural and urban environments, respectively). In 2002/2003, the prevalence of parental smoking in homes with asthmatic children was 29.8%. Parents were not more likely to quit smoking (OR=1.01, 95% CI 0.66 to 1.54) or smoke outside (OR=1.02, 95% CI 0.56 to 1.83) if their child developed asthma. Parental smoking behaviour (quit smoking or smoked outside) did not change if there was a positive family history of asthma (OR=1.04, 95% CI 0.78 to 1.37), if they lived in a rural or urban location (OR=0.94, 95% CI 0.71 to 1.23), or if they were from a low- or high-income household (OR=1.12, 95% CI 0.85 to 1.47). CONCLUSIONS: The likelihood of altering parental smoking behaviour occurred independently of a diagnosis of asthma in their child, a family history of asthma, the location of residence and their socioeconomic status.

Level of Toll-like receptor agonist exposure differentially determines chemokine production in humans.

Toll-like receptor (TLR) agonists, ubiquitously present in the environment, are key players in activating synthesis of cytokines and chemokines that control normal and pathophysiological processes, including multiple inflammatory diseases. TLR2 and TLR4 respond to bacterial cell wall products. We examined the impact of TLR activation on human immune capacity using stimuli ranging from the low levels seen in most environments to the high concentrations widely used for in vitro studies. Peripheral blood mononuclear cells from 117 healthy children were activated with lipopolysaccharide (TLR4 ligand) or peptidoglycan (TLR2 ligand) over a million-fold range of concentrations. Resulting interleukin-6, CCL2, and CCL22 production were quantified by ELISA. The intensity of cytokine production elicited was linearly related to the intensity of the stimulus up to maximal responses. In marked contrast, chemokine production was not linearly related to agonist concentration. Responses rose with increasing stimulation, and then were markedly reduced (40%-100%, p < 0.0001) in response to the high levels of TLR stimulation most commonly cited. Thus, the levels of TLR4 and TLR2 agonists typically used for in vitro interrogation of immune capacity yield results clearly distinct from those obtained using commonly occurring environmental levels of TLR ligands. These findings demonstrate the importance of utilizing TLR ligands at concentrations more closely mimicking environmental levels when assessing immune capacity.

The relationship of breast-feeding, overweight, and asthma in preadolescents.

BACKGROUND: Breast-feeding is suggested to be associated with overweight or asthma in children. Overweight and asthma may share common environmental influences of which breast-feeding may be one. OBJECTIVE: We evaluated whether short duration of exclusive breast-feeding and subsequent overweight were associated with asthma. METHODS: A nested case-control study included 246 children with pediatric allergist-diagnosed asthma and 477 controls without asthma at age 8 to 10 years. Information on exclusive breast-feeding was obtained from questionnaire data. Overweight at 8 to 10 years of age was defined as body mass index >/=85th percentile of age and sex-specific growth charts. The association between asthma and exclusive breast-feeding <12 weeks plus overweight, adjusted for sex, parental asthma, aboriginal origin, passive smoking at birth, residence location, and family income, was determined in logistic regression analyses. RESULTS: Exclusive breast-feeding <12 weeks was closely associated with overweight at age 8 to 10 years (P < .001). Exclusive breast-feeding <12 weeks plus overweight was significantly associated with asthma (adjusted OR, 1.81; 95% CI, 1.11-2.95; P = .018). This association appeared to be strong in children whose mothers had asthma (adjusted OR, 3.93; 95% CI, 1.17-13.2) and also in boys (adjusted OR, 2.22; 95% CI, 1.14-4.34). Asthma was not associated with either exclusive breast-feeding <12 weeks or overweight in the absence of the other. CONCLUSION: Short duration of exclusive breast-feeding and subsequent overweight are associated with asthma in susceptible children, suggesting a common pathway. CLINICAL IMPLICATIONS: This finding adds to the importance of promoting prolonged breast-feeding for the prevention of overweight and asthma.