TNF-308 modifies the effect of second-hand smoke on respiratory illness-related school absences

Health effects associated with exposure to secondhand smoke: a Burden of Proof study

Despite a gradual decline in smoking rates over time, exposure to secondhand smoke (SHS) continues to cause harm to nonsmokers, who are disproportionately children and women living in low- and middle-income countries. We comprehensively reviewed the literature published by July 2022 concerning the adverse impacts of SHS exposure on nine health outcomes. Following, we quantified each exposure-response association accounting for various sources of uncertainty and evaluated the strength of the evidence supporting our analyses using the Burden of Proof Risk Function methodology. We found all nine health outcomes to be associated with SHS exposure. We conservatively estimated that SHS increases the risk of ischemic heart disease, stroke, type 2 diabetes and lung cancer by at least around 8%, 5%, 1% and 1%, respectively, with the evidence supporting these harmful associations rated as weak (two stars). The evidence supporting the harmful associations between SHS and otitis media, asthma, lower respiratory infections, breast cancer and chronic obstructive pulmonary disease was weaker (one star). Despite the weak underlying evidence for these associations, our results reinforce the harmful effects of SHS on health and the need to prioritize advancing efforts to reduce active and passive smoking through a combination of public health policies and education initiatives.

Risk of illness-related school absenteeism for elementary students with exposure to PM2.5 and O3

Air pollution addresses short-term health effects on morbidity, especially for children. Assessing the impacts of air pollution on elementary students is critical for developing preparedness response strategies for this sensitive group. In the 2016-17 academic year, up to 687,748 groups of illness-related absence records and the information on whether the absentee had gone to a hospital or not were collected from 2564 elementary schools across Jiangsu Province China. We explored the associations between air pollution and illness-related records using a time-stratified case-crossover analysis with distributed lag non-linear design. An increase of 10 μg/m³ in the current-day concentration of PM_2.5 and O₃ was positively associated with illness-related absenteeism overall. The excess risk of absenteeism was 4.52 % (95%CI 4.37-4.67 %) for PM_2.5 and 0.25 % (95%CI 0.01-0.36 %) for O₃. The risk associated with O₃ was boosted for the frequent absentees who tended to have basic diseases or were more vulnerable to infectious diseases. Students in 43.1 % illness-related absenteeism, mainly due to highly infectious diseases, only received home nursing without going to a hospital. The increase in the number of illness cases associated with PM_2.5 and O₃ estimated based on the illness-related absence data was 41.5 % and 18.6 % higher than that evaluated based on hospital visit records. Such underestimations persisted in sensitivity analyses and persisted in subgroups classified by gender or grade. Together, the performance of illness-related absence records far outweighed that of hospital visit data regarding the thorough evaluation of air pollution-related illness cases for elementary students. Improvement in air quality and home health care education are warranted as well for the health benefits of children.

Influence of Second-Hand Smoke and Prenatal Tobacco Smoke Exposure on Biomarkers, Genetics and Physiological Processes in Children-An Overview in Research Insights of the Last Few Years

Children are commonly exposed to second-hand smoke (SHS) in the domestic environment or inside vehicles of smokers. Unfortunately, prenatal tobacco smoke (PTS) exposure is still common, too. SHS is hazardous to the health of smokers and non-smokers, but especially to that of children. SHS and PTS increase the risk for children to develop cancers and can trigger or worsen asthma and allergies, modulate the immune status, and is harmful to lung, heart and blood vessels. Smoking during pregnancy can cause pregnancy complications and poor birth outcomes as well as changes in the development of the foetus. Lately, some of the molecular and genetic mechanisms that cause adverse health effects in children have been identified. In this review, some of the current insights are discussed. In this regard, it has been found in children that SHS and PTS exposure is associated with changes in levels of enzymes, hormones, and expression of genes, micro RNAs, and proteins. PTS and SHS exposure are major elicitors of mechanisms of oxidative stress. Genetic predisposition can compound the health effects of PTS and SHS exposure. Epigenetic effects might influence in utero gene expression and disease susceptibility. Hence, the limitation of domestic and public exposure to SHS as well as PTS exposure has to be in the focus of policymakers and the public in order to save the health of children at an early age. Global substantial smoke-free policies, health communication campaigns, and behavioural interventions are useful and should be mandatory.

Chronic effects of air pollution on respiratory health in Southern California children: findings from the Southern California Children's Health Study

Outdoor air pollution is one of the leading contributors to adverse respiratory health outcomes in urban areas around the world. Children are highly sensitive to the adverse effects of air pollution due to their rapidly growing lungs, incomplete immune and metabolic functions, patterns of ventilation and high levels of outdoor activity. The Children's Health Study (CHS) is a continuing series of longitudinal studies that first began in 1993 and has focused on demonstrating the chronic impacts of air pollution on respiratory illnesses from early childhood through adolescence. A large body of evidence from the CHS has documented that exposures to both regional ambient air and traffic-related pollutants are associated with increased asthma prevalence, new-onset asthma, risk of bronchitis and wheezing, deficits of lung function growth, and airway inflammation. These associations may be modulated by key genes involved in oxidative-nitrosative stress pathways via gene-environment interactions. Despite successful efforts to reduce pollution over the past 40 years, air pollution at the current levels still brings many challenges to public health. To further ameliorate adverse health effects attributable to air pollution, many more toxic pollutants may require regulation and control of motor vehicle emissions and other combustion sources may need to be strengthened. Individual interventions based on personal susceptibility may be needed to protect children's health while control measures are being implemented.

Impact of single nucleotide polymorphism in tumor necrosis factor-α gene 308G/A in Egyptian asthmatic children and wheezing infants

Bronchial asthma is a common disease with multiple determinants that include genetic variation. Although tumor necrosis factor alpha (TNF-α) is a major pro-inflammatory cytokine, the functions of genetic polymorphisms in this cytokine has not been thoroughly examined in the context of asthma pathology. Therefore, we aimed to investigate whether single nucleotide polymorphism (SNP) in TNF-α is associated with asthma and wheezing and whether the association is related to the severity of the disease and other epidemiological factors. Frequencies of TNF-α-308G/A polymorphism were compared in 100 asthmatic children, 100 wheezy infants and 100 age and gender matched controls. Genotype frequencies for TNF-α-308G/A were significantly higher in asthmatic children (60%) and wheezy infants (68%) than the control group (30%). Higher serum levels of TNF-α were observed in genotypes G/A and G/G of asthmatic children and wheezy infants than in controls. No association was found between the G/A polymorphism and the severity of the disease, the total eosinophil count and IgE levels in both groups. We can conclude that genetic variation in TNF-α-308G/A may contribute to childhood asthma and wheezing. These findings could be helpful for future early intervention studies which may have a potential impact on family counseling and management.

Interaction between early maternal smoking and variants in TNF and GSTP1 in childhood wheezing

BACKGROUND

Children exposed to tobacco smoke early in life have a higher risk of wheeze. Individual susceptibility may depend on genetic factors.

OBJECTIVE

We studied whether variations in single nucleotide polymorphisms (SNPs) in the TNF, glutathione S transferase P1 (GSTP1) and beta2-adrenoreceptor (ADRB2) genes modify the effect of early maternal smoking on the development of childhood asthma, wheeze and allergic sensitization.

METHODS

In the Swedish prospective birth cohort BAMSE (Children, Allergy, Milieu, Stockholm, Epidemiological Survey) (n=4089), data collection included questionnaires to measure tobacco smoke exposure and clinical outcomes up to age 4 and medical examinations with blood sampling for specific IgE measurements and genotyping. We defined early maternal smoking as daily smoking by the mother during pregnancy and/or postnatally. We investigated five TNF, six GSTP1 and three ADRB2 SNPs in 982 selected wheezers and non-wheezers.

RESULTS

An interaction with early maternal smoking was found for three TNF SNPs (-857C/T, Intron 1, Intron 3) with respect to early wheeze (up to 2 years of age). For example, the odds ratio (OR) for developing early wheeze related to early maternal smoking was 2.4 [95% confidence interval (CI) 1.6-3.7] in children with a wild-type CC homozygote genotype of the TNF-857 SNP, while no tobacco-related risk was seen in children carrying the rare T allele. A clear dose response was observed in children with the CC genotype, with an OR of 1.3 (95% CI 1.1-1.5) per each additional pack per week smoked by the mother during pregnancy. A suggestive interaction with early maternal smoking was also seen for three GSTP1 SNPs (Intron 5, Intron 6 and Ile105Val) with respect to transient wheeze, but not for ADRB2 and wheeze phenotypes. No effect modifications were observed for allergic sensitization.

CONCLUSION

Our results suggest that the risk of early childhood wheeze associated with early maternal smoking may be modified by TNF and GSTP1 polymorphisms.

In utero smoke exposure, glutathione S-transferase P1 haplotypes, and respiratory illness-related absence among schoolchildren

BACKGROUND

The GSTP1 Ile105Val variant and secondhand tobacco smoke exposure have been independently associated with acute respiratory illness; however, susceptibility to in utero and secondhand tobacco smoke has yet to be examined in relation to variation across the GSTP1 locus.

OBJECTIVE

The purpose of this work was to determine whether variation across the GSTP1 locus is associated with respiratory illness-related school absences and to determine whether this relationship varies by in utero and secondhand tobacco smoke exposure.

METHODS

Tobacco smoke exposure status, incident respiratory-related school absence records, and DNA samples was ascertained for 1132 Hispanic and non-Hispanic white elementary school children as part of the Children's Health Study.

RESULTS

Four GSTP1 single-nucleotide polymorphisms were selected that accounted for 93% of the variation across the locus. Individual single-nucleotide polymorphism analyses showed a protective effect for the minor alleles in single-nucleotide polymorphisms 1 (rs6591255), 3 (GSTP1 Ile105Val: rs1695), and 4 (rs749174) for respiratory illness. The haplotype, which includes a minor allele for single-nucleotide polymorphisms 1, 3, and 4 (h1011), was associated with a decreased risk of respiratory illness. The protective effect of GSTP1 variants was lost among individuals exposed to in utero and secondhand tobacco smoke.

CONCLUSIONS

A common GSTP1 haplotype, which includes the functional Ile105Val polymorphism, was associated with respiratory-related school absences. The protection afforded by this haplotype was lost in children exposed to involuntary tobacco smoke. The paradigm of loss of genetic protection among those exposed to tobacco smoke has clinical and public health implications that warrant broader consideration in research and practice.

Interactions between glutathione S-transferase P1, tumor necrosis factor, and traffic-related air pollution for development of childhood allergic disease

BACKGROUND

Air pollutants may induce airway inflammation and sensitization due to generation of reactive oxygen species. The genetic background to these mechanisms could be important effect modifiers.

OBJECTIVE

Our goal was to assess interactions between exposure to air pollution and single nucleotide polymorphisms (SNPs) in the beta2-adrenergic receptor (ADRB2), glutathione S-transferase P1 (GSTP1), and tumor necrosis factor (TNF) genes for development of childhood allergic disease.

METHODS

In a birth cohort originally of 4,089 children, we assessed air pollution from local traffic using nitrogen oxides (traffic NO(x)) as an indicator based on emission databases and dispersion modeling and estimated individual exposure through geocoding of home addresses. We measured peak expiratory flow rates and specific IgE for inhalant and food allergens at 4 years of age, and selected children with asthma symptoms up to 4 years of age (n = 542) and controls (n = 542) for genotyping.

RESULTS

Interaction effects on allergic sensitization were indicated between several GSTP1 SNPs and traffic NO(x) exposure during the first year of life (p(nominal) < 0.001-0.06). Children with Ile105Val/Val105Val genotypes were at increased risk of sensitization to any allergen when exposed to elevated levels of traffic NO(x) (for a difference between the 5th and 95th percentile of exposure: odds ratio = 2.4; 95% confidence interval, 1.0-5.3). In children with TNF-308 GA/AA genotypes, the GSTP1-NO(x) interaction effect was even more pronounced. We observed no conclusive interaction effects for ADRB2.

CONCLUSION

The effect of air pollution from traffic on childhood allergy appears to be modified by GSTP1 and TNF variants, supporting a role of genes controlling the antioxidative system and inflammatory response in allergy.

Gene-air pollution interactions in asthma

Genetic and environmental factors interact to cause asthma. However, genetic studies have generally ignored environmental factors and environmental studies have generally ignored genetics. Thus, there are few examples from the literature of specific gene-environment interactions in relation to asthma. The clearest examples of genetic interactions for inhaled pollutants exist for endotoxin, environmental tobacco smoke, and ozone. Endotoxin-genetic interactions in asthma are the focus of two other manuscripts from this conference, so this review focuses on environmental tobacco smoke and ozone. In the sparse literature, there is evidence for the role of specific genes involved in oxidative stress, notably GSTM1 and TNF, in the respiratory responses to ozone and environmental tobacco smoke. There are few data on genes involved in innate immune pathways, which are crucial in response to endotoxin and may play a role in response to ozone and environmental tobacco smoke. Genes involved in oxidative stress may interact with both air pollutants and diet in relation to asthma phenotypes. Future directions to advance the field include whole genome association studies, better assessment of exposure and phenotypes, and consideration of joint interactions with diet and other co-factors that influence individual susceptibility.

Parental smoking modifies the relation between genetic variation in tumor necrosis factor-alpha (TNF) and childhood asthma

BACKGROUND

Polymorphisms in the proinflammatory cytokine genes tumor necrosis factor-alpha (TNF) and lymphotoxin-alpha (LTA, also called TNF-beta) have been associated with asthma and atopy in some studies. Parental smoking is a consistent risk factor for childhood asthma. Secondhand smoke and ozone both stimulate TNF production.

OBJECTIVES

Our goal was to investigate whether genetic variation in TNF and LTA is associated with asthma and atopy and whether the association is modified by parental smoking in a Mexican population with high ozone exposure.

METHODS

We genotyped six tagging single nucleotide polymorphisms (SNPs) in TNF and LTA, including functional variants, in 596 nuclear families consisting of asthmatics 4-17 years of age and their parents in Mexico City. Atopy was determined by skin prick tests.

RESULTS

The A allele of the TNF-308 SNP was associated with increased risk of asthma [relative risk (RR) = 1.54; 95% confidence interval (CI), 1.04-2.28], especially among children of non-smoking parents (RR = 2.06; 95% CI, 1.19-3.55; p for interaction = 0.09). Similarly, the A allele of the TNF-238 SNP was associated with increased asthma risk among children of nonsmoking parents (RR = 2.21; 95% CI, 1.14-4.30; p for interaction = 0.01). LTA SNPs were not associated with asthma. Haplotype analyses reflected the single SNP findings in magnitude and direction. TNF and LTA SNPs were not associated with the degree of atopy.

CONCLUSIONS

Our results suggest that genetic variation in TNF may contribute to childhood asthma and that associations may be modified by parental smoking.

The early-life origins of asthma

PURPOSE OF REVIEW

Inflammatory mediators produced from activated mast cells and T helper type 2 cells drive allergic inflammation. The pathways required for mast and T helper type 2 cell activation and the effects of their products are being defined in order to identify new therapeutics. We focus on recent findings on the chief inducer of mast cell activation, the IgE receptor-signaling cascade, and the development of new inhibitors of this pathway. We also summarize work that examines the molecular mechanisms utilized by the interleukin IL-4/13 receptors and characterizes therapeutic compounds that target these pathways.

RECENT FINDINGS

The tyrosine kinases Lyn, Fyn and Syk have complex roles in IgE receptor signaling. Biochemical analysis and gene expression profiling have shed light on both the positive and negative functions of these proteins and establish additional connections with downstream pathways. Syk inhibitors were identified that may prove useful as antiinflammatory agents. Progress has been made in characterizing how IL-4/13 interact with their cognate receptors that will aid in the design of inhibitors of these interactions.

SUMMARY

Recent studies have advanced our understanding of how the IgE receptor and IL-4/13 receptors function. This new knowledge may lead to the development of novel and highly specific inhibitors of allergic inflammation.

Variations in genetic influences on the development of asthma throughout childhood, adolescence and early adult life

PURPOSE OF REVIEW

Asthma is likely to be due to many aetiological factors, the effect of each varying considerably with age. Now that there are well established candidate genes for asthma, using genetics to examine age-related susceptibility to asthma offers a new approach to understanding the basic underlying mechanisms.

RECENT FINDINGS

Since few long-term, longitudinal asthma studies exist, opportunities to examine age-related genetic susceptibility have been limited, but have produced some specific findings. The CCR5Delta32 polymorphism renders the chemokine receptor nonfunctional and is associated with reduced asthma susceptibility in children but not adults. In CD14 C-159T, the -159C allele has been associated with increased atopy in mid-childhood, but not in young adults. IL-12beta is a promoter polymorphism associated with reduced lung function in girls but not boys in mid-childhood only. Regarding the beta(2)adrenoceptor, results from three studies suggest that Arg16 can be associated with impaired airway function in infancy and Gly16 with asthma and wheeze in mid-childhood.

SUMMARY

Age-related genetic susceptibility studies are likely to make a major contribution to understanding basic mechanisms in asthma, but the limited number of suitable cohorts has meant that to date few studies have been reported.

Parental smoking and lung function in children: an international study

RATIONALE

Both prenatal and postnatal passive smoking have been linked with respiratory symptoms and asthma in childhood. Their differential contributions to lung function growth in the general children's population are less clear.

OBJECTIVE

To study the relative impact of pre- and postnatal exposure on respiratory functions of primary school children in a wide range of geographic settings, we analyzed flow and volume data of more than 20,000 children (aged 6-12 yr) from nine countries in Europe and North America.

METHODS

Exposure information had been obtained by comparable questionnaires, and spirometry followed a protocol of the American Thoracic Society/European Respiratory Society. Linear and logistic regressions were used, controlling for individual risk factors and study area. Heterogeneity between study-specific results and mean effects were estimated using meta-analytic tools.

MAIN RESULTS

Smoking during pregnancy was associated with decreases in lung function parameters between -1% (FEV1) and -6% maximal expiratory flow at 25% of vital capacity left (MEF25). A 4% lower maximal midexpiratory flow (MMEF) corresponded to a 40% increase in the risk of poor lung function (MMEF < 75% of expected). Associations with current passive smoking were weaker though still measurable, with effects ranging from -0.5% (FEV1) to -2% maximal expiratory flow (MEF50).

CONCLUSIONS

Considering the high number of children exposed to maternal smoking in utero and the even higher number exposed to passive smoking after birth, this risk factor for reduced lung function growth remains a serious pediatric and public health issue.