Do Glutathione S-Transferase Genes Modify the Link between Indoor Air Pollution and Asthma, Allergies, and Lung Function? A Systematic Review

Gene-Air Pollution Interaction and Diversity of Genetic Sampling: The Southern California Children's Health Study

Gene-environment interactions have been observed for childhood asthma, however few have been assessed in ethnically diverse populations. Thus, we examined how polygenic risk score (PRS) modifies the association between ambient air pollution exposure (nitrogen dioxide [NO2], ozone, particulate matter < 2.5 and < 10 μm) and childhood asthma incidence in a diverse cohort. Participants (n = 1794) were drawn from the Southern California Children's Health Study, a multi-wave prospective cohort followed from 4th to 12th grade. PRS was developed using single nucleotide polymorphisms previously associated with childhood asthma. PRS-asthma associations and PRS-air pollutant interactions were estimated using Poisson regression. An interquartile range PRS increase was associated with 36% (95% CI: 9%, 70%) higher asthma incidence among non-Hispanic children, but not associated with asthma among Hispanic children (rate ratio: 0.81 [95% CI: 0.62, 1.04]). NO2-PRS interaction was borderline significant in the overall sample (coefficient: 0.23 [95% CI: -0.03, 0.49]). Limited evidence was observed for a positive interaction between PRS and NO2 exposure associated with asthma incidence; however, the literature-based PRS was not associated with asthma among Hispanic participants. Equitable, diverse genetic sampling approaches are needed to better identify clinically relevant SNPs in this population.

Indoor air pollution and airway health

Because of the disproportionate amount of time that people spend indoors and the complexities of air pollutant exposures found there, indoor air pollution is a growing concern for airway health. Both infiltration of outdoor air pollution into the indoor space and indoor sources (such as smoke from tobacco products, cooking or heating practices and combustion of associated fuels, and household materials) contribute to unique exposure mixtures. Although there is substantial literature on the chemistry of indoor air pollution, research focused on health effects is only beginning to emerge and remains an important area of need to protect public health. We provide a review of emerging literature spanning the past 3 years and relating indoor air exposures to airway health, with a specific focus on the impact of either individual pollutant exposures or common combustion sources on the lower airways. Factors defining susceptibility and/or vulnerability are reviewed with consideration for priority populations and modifiable risk factors that may be targeted to advance health equity.

Air pollution associated acute respiratory inflammation and modification by GSTM1 and GSTT1 gene polymorphisms: a panel study of healthy undergraduates

Epidemiological evidence has linked air pollution with adverse respiratory outcomes, but the mechanisms underlying susceptibility to air pollution remain unclear. This study aimed to investigate the role of glutathione S-transferase (GST) polymorphism in the association between air pollution and lung function levels. A total of 75 healthy young volunteers aged 18-20 years old were recruited for six follow-up visits and examinations. Spirometry was conducted to obtain lung function parameters such as forced vital capacity (FVC), and forced expiratory volume in 1 s (FEV₁). Nasal fluid concentrations of interleukin-6 (IL-6), interleukin-8 (IL-8), tumor necrosis factor-α (TNF-α), and 8-epi-prostaglandin F2α (8-epi-PGF2a) were measured using ELISA kits. Linear mixed-effect models were used to evaluate the association of air pollutants with respiratory outcomes. Additionally, polymorphisms of glutathione S-transferase mu 1 (GSTM1) and glutathione S-transferase theta 1 (GSTT1) were estimated to explore its role in the association between air pollutants and lung function. We found that short-term exposure to atmospheric particulates such as PM_2.5 and PM₁₀ can cause an increase in nasal biomarkers of inflammation, oxidative stress, and lung function, while air gaseous pollutant exposure is linked with decreased lung function, except for CO. Stratification analyses showed that an increase in nasal inflammatory cytokines caused by exposure to atmospheric particulates is more obvious in subjects with GSTM1-sufficient (GSTM1⁺) than GSTM1-null (GSTM1^-), while elevated lung function levels due to air particles are more significant in subjects with the genotype of GSTM1^- when compared to GSTM1⁺. As for air gaseous pollutants, decreased lung function levels caused by O₃, SO₂, and NO₂ exposure is more manifest in subjects with the genotype of GSTM1^- compared to GSTM1⁺. Taken together, short-term exposure to air pollutants is associated with alterations in nasal biomarkers and lung function levels in young healthy adults, and susceptible genotypes play an important mediation role in the association between exposure to air pollutants and inflammation, oxidative stress, and lung function levels.

Acute effects of ambient nitrogen dioxide exposure on serum biomarkers of nervous system damage in healthy older adults

Ambient nitrogen dioxide (NO₂)-induced adverse health effects have been studied, but documented evidence on neural systems is limited. This study aimed to determine the acute effect of NO₂ exposure on nervous system damage biomarker levels in healthy older adults. Five rounds of follow-up among 34 healthy retired people were scheduled from December 2018 to April 2019 in Xinxiang, China. The real-time NO₂ concentrations were measured using a fixed site monitor. Serum samples were acquired during each round to measure nervous system damage biomarker levels: brain-derived neurotrophic factor (BDNF), neurofilament light chain (NfL), neuron-specific enolase (NSE), protein gene product 9.5 (PGP9.5), and S100 calcium-binding protein B (S100B). A linear mixed-effect model was incorporated to analyze the association between short-term NO₂ exposure and serum concentrations of the above-mentioned biomarkers. Stratification analysis based on sex, educational attainment, glutathione S-transferase theta 1 gene (GSTT1) polymorphism, and physical activity intensity was conducted to explore their potential modification effect. The NO₂ concentration ranged from 34.7 to 59.0 µg/m³ during the study period. Acute exposure to ambient NO₂ was significantly associated with elevated serum levels of NfL, PGP9.5, and BDNF. In response to a 10 µg/m³ increase in NO₂ concentration, NfL and PGP9.5 levels increased by 76 % (95 % confidence interval [CI]: 12-140 %) and 54 % (95 % CI: 1-107 %) on the lag0 day, respectively, while BDNF levels increased by 49 % (95 % CI: 2-96 %) at lag4 day. The estimated effect of NO₂ on NSE levels in GSTT1-sufficient participants was significantly higher than that in GSTT1-null participants. Intriguingly, the estimation of NO₂ on PGP9.5 levels in females was significantly higher than that in males. Most two-pollutant models showed robust results, except for O₃, which might have had confounding effects on NO₂-induced BDNF stimulation. In summary, acute exposure to NO₂ was associated with increased levels of serum nervous system damage biomarker levels including NFL, PGP9.5, and BDNF. The present study provided insights into NO₂ exposure-induced adverse neural effects.

The role of gene-ambient air pollution interactions in paediatric asthma

Globally, asthma prevention and treatment remain a challenge. Ambient air pollution (AAP) is an environmental risk factor of special interest in asthma research. AAP is poorly defined and has been subdivided either by the origin of the air pollution or by the specific bioactive compounds. The link between AAP exposure and asthma exacerbations is well established and has been extensively reviewed. In this narrative review, we discuss the specific genetic variants that have been associated with increased AAP sensitivity and impact in paediatric asthma. We highlight the relative importance of variants associated with genes with a role in oxidant defences and the nuclear factor-κB pathway supporting a potential central role for these pathways in AAP sensitivity.

Interactions between glutathione S-transferase genes and household air pollution on asthma and lung function

Oxidative stress is one of the main pathophysiological mechanisms for chronic respiratory disease. Glutathione S-transferase (GST) genes play important roles in antioxidant defences and may influence respiratory health. Although there is not consistent evidence that the three commonly studied genes of GSTM1, GSTT1 and GSTP1 are associated directly with respiratory outcomes, they seem to be related to disease susceptibility if exposure interactions are taken into account. Exposure to household air pollution may be particularly important in increasing lung oxidative stress. This review summarizes the relationships between GST genes, household air pollution and asthma and impaired lung function. Our findings support a role for GST polymorphisms in susceptibility to asthma and impaired lung function via oxidative stress pathways. Future research should additionally consider the role of gene-gene interactions, multiple environmental exposures, and gender in these complex associations, that are involved in maintaining antioxidant defences and lung health.

Health and Clinical Impacts of Air Pollution and Linkages with Climate Change

Air Pollution Impacts and Climate Change LinksAs part of the NEJM Group series on climate change, Keswani and colleagues review the linkages between climate change and air pollution and suggest strategies that clinicians may use to mitigate the adverse health impacts of air pollution.

Associations of short-term PM2.5 exposures with nasal oxidative stress, inflammation and lung function impairment and modification by GSTT1-null genotype: A panel study of the retired adults

PM_2.5 (particulate matter ≤2.5 μm in aerodynamic diameter) is a major urban air pollutant worldwide. Its effects on the respiratory system of the susceptible population have been less characterized. This study aimed to estimate the association of short-term PM_2.5 exposure with respiratory outcomes of the retired adults, and to examine whether these associations were stronger among the subjects with GSTT-null genotype. 32 healthy subjects (55-77 years) were recruited for five follow-up examinations. Ambient concentrations of PM_2.5 were monitored consecutively for 7 days prior to physical examination. Pulmonary outcomes including forced vital capacity (FVC), forced expiratory volume in 1 s (FEV₁), peak expiratory flow (PEF), and fractional exhaled nitric oxide (FeNO), and nasal fluid concentrations of 8-epi-prostaglandin F2 alpha (8-epi-PGF2α), tumor necrosis factor-α (TNF-α), interleukin-8 (IL-8) and IL-1β were measured. A linear mixed-effect model was introduced to evaluate the associations of PM_2.5 concentrations with respiratory outcomes. Additionally, GSTT1 genotype-based stratification was performed to characterize modification on PM_2.5-related respiratory outcomes. We found that a 10 μg/m³ increase in PM_2.5 was associated with decreases of 0.52 L (95% confidence interval [CI]: -1.04, -0.002), 0.64 L (95% CI: -1.13, -0.16), 0.1 (95% CI: -0.23, 0.04) and 2.87 L/s (95% CI: -5.09, -0.64) in FVC, FEV₁, FEV₁/FVC ratio and PEF at lag 2, respectively. Meanwhile, marked increases of 80.82% (95% CI: 5.13%, 156.50%) in IL-8, 77.14% (95% CI: 1.88%, 152.40%) in IL-1β and 67.87% (95% CI: 14.85%, 120.88%) in 8-epi-PGF2α were observed as PM_2.5 concentration increased by 10 μg/m³ at lag 2. Notably, PM_2.5-associated decreases in FVC and PEF and increase in FeNO were stronger among the subjects with GSTT1-null genotype. In summary, short-term exposure to PM_2.5 is associated with nasal inflammation, oxidative stress and lung function reduction in the retired subjects. Lung function reduction and inflammation are stronger among the subjects with GSTT1-null genotype.

Glutathione S-Transferase Gene Associations and Gene-Environment Interactions for Asthma

PURPOSE OF REVIEW

Asthma is one of the most common chronic inflammatory airway diseases. Airway oxidative stress is defined as an imbalance between oxidative and antioxidative processes in the airways. There is evidence that chronic damage caused by oxidative stress may be involved in asthmatic inflammation and reduced lung function. Given their biological antioxidant function, the antioxidant genes in the glutathione S-transferase (GST) family are believed to be associated with development and progression of asthma. This review aims to summarize evidence on the relationship between GST gene polymorphisms and asthma and interactions with environmental exposures.

RECENT FINDINGS

The current evidence on the association between GST genes and asthma is still weak or inconsistent. Failure to account for environmental exposures may explain the lack of consistency. It is highly likely that environmental exposures interact with GST genes involved in the antioxidant pathway. According to current knowledge, carriers of GSTM1(rs366631)/T1(rs17856199) null genotypes and GSTP1 Val105 (rs1695) genotypes are more susceptible to environmental oxidative exposures and have a higher risk of asthma. Some doubt remains regarding the presence or absence of interactions with different environmental exposures in different study scenarios. The GST-environment interaction may depend on exposure type, asthma phenotype or endotype, ethnics, and other complex gene-gene interaction. Future studies could be improved by defining precise asthma endotypes, involving multiple gene-gene interactions, and increasing sample size and power. Although there is evidence for an interaction between GST genes, and environmental exposures in relation to asthma, results are not concordant. Further investigations are needed to explore the reasons behind the inconsistency.

Lifetime Risk Factors for Pre- and Post-Bronchodilator Lung Function Decline. A Population-based Study

Rationale: Interactions between early life and adult insults on lung function decline are not well understood, with most studies investigating prebronchodilator (pre-BD) FEV₁ decline.Objectives: To investigate relationships between adult risk factors and pre- and post-BD lung function decline and their potential effect modification by early life and genetic factors.Methods: Multiple regression was used to examine associations between adult exposures (asthma, smoking, occupational exposures, traffic pollution, and obesity) and decline in both pre- and post-BD spirometry (forced expiratory volume in 1 s [FEV₁], forced vital capacity [FVC], and FEV₁/FVC) between ages 45 and 53 years in the Tasmanian Longitudinal Health Study (n = 857). Effect modification of these relationships by childhood respiratory risk factors, including low childhood lung function and GST (glutathione S-transferase) gene polymorphisms, was investigated.Results: Baseline asthma, smoking, occupational exposure to vapors/gases/dusts/fumes, and living close to traffic were associated with accelerated decline in both pre- and post-BD FEV₁. These factors were also associated with FEV₁/FVC decline. Occupational exposure to aromatic solvents was associated with pre-BD but not post-BD FEV₁ decline. Maternal smoking accentuated the effect of personal smoking on pre- and post-BD FEV₁ decline. Lower childhood lung function and having the GSTM1 null allele accentuated the effect of occupational exposure to vapors/gases/dusts/fumes and personal smoking on post-BD FEV₁ decline. Incident obesity was associated with accelerated decline in FEV₁ and more pronounced in FVC.Conclusions: This study provides new evidence for accentuation of individual susceptibility to adult risk factors by low childhood lung function, GSTM1 genotype, and maternal smoking.

Adverse Environmental Exposure and Respiratory Health in Children

The burden imposed by pollution falls more on those living in low-income and middle-income countries, affecting children more than adults. Most air pollution results from incomplete combustion and contains a mixture of particulate matter and gases. Air pollution exposure has negative impacts on respiratory health. This article concentrates on air pollution in 2 settings, the child's home and the ambient environment. There is an inextricable 2-way link between air pollution and climate change, and the effects of climate change on childhood respiratory health also are discussed.

Air pollution and indoor settings

Indoor environments contribute significantly to total human exposure to air pollutants, as people spend most of their time indoors. Household air pollution (HAP) resulting from cooking with polluting ("dirty") fuels, which include coal, kerosene, and biomass (wood, charcoal, crop residues, and animal manure) is a global environmental health problem. Indoor pollutants are gases, particulates, toxins, and microorganisms among others, that can have an impact especially on the health of children and adults through a combination of different mechanisms on oxidative stress and gene activation, epigenetic, cellular, and immunological systems. Air pollution is a major risk factor and contributor to morbidity and mortality from major chronic diseases. Children are significantly affected by the impact of the environment due to biological immaturity, prenatal and postnatal lung development. Poor air quality has been related to an increased prevalence of clinical manifestations of allergic asthma and rhinitis. Health professionals should increase their role in managing the exposure of children and adults to air pollution with better methods of care, prevention, and collective action. Interventions to reduce household pollutants may promote health and can be achieved with education, community, and health professional involvement.

The Respiratory Risks of Ambient/Outdoor Air Pollution

Globally, exposure to ambient air pollutants is responsible for premature mortality and is implicated in the development and exacerbation of several acute and chronic lung disease across all ages. In this article, we discuss the source apportionment of ambient pollutants and the respiratory health effects in humans. We specifically discuss the evidence supporting ambient pollution in the development of asthma and chronic obstructive pulmonary disease and acute exacerbations of each condition. Practical advice is given to health care providers in how to promote a healthy environment and advise patients with chronic conditions to avoid unsafe air quality.

Exposure to traffic-related particle matter and effects on lung function and potential interactions in a cross-sectional analysis of a cohort study in west Sweden

OBJECTIVES

To investigate the long-term effects of source-specific particle matter (PM) on lung function, effects of Surfactant Protein A (SP-A) and glutathione S-transferase (GST) genes GSTP1 and GSTT1 gene variants and effect modification by single-nucleotide polymorphism (SNP) genotype.

DESIGN

Cohort study with address-based annual PM exposure assigned from annual estimates of size (PM₁₀, PM_2.5 and PM_BC) and source-specific (traffic, industry, marine traffic and wood burning) dispersion modelling.

SETTING

Gothenburg, Sweden.

PARTICIPANTS

The ADult-Onset asthma and NItric oXide Study had 6685 participants recruited from the general population, of which 5216 (78%) were included in the current study with information on all variables of interest. Mean age at the time of enrolment was 51.4 years (range 24-76) and 2427 (46.5%) were men.

PRIMARY AND SECONDARY OUTCOME MEASURES

The primary outcome was forced vital capacity (FVC) and forced expiratory volume in 1 s (FEV₁). Secondary outcome measures were effects and gene-environment interactions of SP-A and GSTT1 and GSTP1 genotypes.

RESULTS

Exposure to traffic-related PM₁₀ and PM_2.5 was associated with decreases in percent-predicted (% predicted) FEV₁ by -0.48% (95% CI -0.89% to -0.07%) and -0.47% (95% CI -0.88% to -0.07%) per IQR 3.05 and 2.47 µg/m³, respectively, and with decreases in % predicted FVC by -0.46% (95% CI -0.83% to -0.08%) and -0.47% (95% CI -0.83% to -0.10%). Total and traffic-related PM_BC was strongly associated with both FEV₁ and FVC by -0.53 (95% CI -0.94 to -0.13%) and -0.43% (95% CI -0.77 to -0.09%) per IQR, respectively, for FVC, and similarly for FEV₁. Minor allele carrier status for two GSTP1 SNPs and the GSTT1 null genotype were associated with decreases in % predicted lung function. Three SP-A SNPs showed effect modification with exposure to PM_2.5 from industry and marine traffic.

CONCLUSIONS

PM exposure, specifically traffic related, was associated with FVC and FEV₁ reductions and not modified by genotype. Genetic effect modification was suggested for industry and marine traffic PM_2.5.

Early life acetaminophen exposure, glutathione S-transferase genes, and development of adolescent asthma in a high-risk birth cohort

BACKGROUND

Although the impact of early life acetaminophen on asthma risk is still not clear, potential interactions with glutathione S-transferase (GST) genes due to reduced antioxidant function in particular polymorphisms, and possible impact on lung function, have never been investigated in adolescents.

OBJECTIVE

We aimed to investigate associations between early life acetaminophen use and adolescent asthma and lung function and to assess potential interactions by GST polymorphisms.

METHODS

Acetaminophen use was recorded 18 times up to age 2 years (n = 575 [92.7%]). Participants were genotyped for GST polymorphisms (GSTM1/T1/P1) (n = 429 [69.2%]). Asthma and lung function were measured at 12 (n = 365 [58.9%]) and 18 years (n = 413 [66.6%]). Regression models assessed associations and interactions.

RESULTS

Doubling of days of acetaminophen use was associated with reduced prebronchodilator FEV₁/forced vital capacity (β coefficient, -0.10; 95% CI, -0.19 to -0.01) and midexpiratory flow (-0.09; 95% CI, -0.18 to 0) at 18 years, but this association was not found when restricted for nonrespiratory reasons, suggesting confounding by indication. However, in children with GSTM1 null and GSTT1 present, increasing acetaminophen use for nonrespiratory reasons was associated with reduced FEV₁ and midexpiratory flow at 18 years (interaction between GSTM1/T1 and acetaminophen P < .05). Increased acetaminophen use was associated with asthma at 18 years for children with GSTP1 Ile/Ile (odds ratio, 1.66; 95% CI, 1.07 to 2.57), but not other GSTP1 genotypes.

CONCLUSIONS

These novel findings need to be investigated for consistency in other studies but suggest that children carrying risk genotypes may be susceptible to respiratory consequences from acetaminophen use.

Short time exposure to ambient ozone and associated cardiovascular effects: A panel study of healthy young adults

The evidence that exposure to ambient ozone (O₃) causes acute cardiovascular effects appears inconsistent. A repeated-measure study with 61 healthy young volunteers was conducted in Xinxiang, Central China. Real-time concentrations of O₃ were monitored. Cardiovascular outcomes including blood pressure (BP), heart rate (HR), serum levels of high sensitivity C-reactive protein (hs-CRP), 8-hydroxy-2'-deoxyguanosine (8-OHdG), tissue-type plasminogen activator (t-PA), and platelet-monocyte aggregation (PMA) were repeated measured. Linear mixed-effect models were used to analyze the association of ambient O₃ with these cardiovascular outcomes. Additionally, the modifying effects of glutathione S-transferase mu 1 (GSTM1) and glutathione S-transferase theta 1 (GSTT1) polymorphisms were estimated to explore the potential mechanisms and role of the association between O₃ exposure and the above cardiovascular outcomes. A 10 μg/m³ increase in O₃ was associated with increases of 9.2 mmHg (95% confidence interval [CI]: 2.5, 15.9), 7.2 mmHg (95% CI: 0.8, 13.6), and 21.2 bpm (95% CI: 5.8, 36.6) in diastolic BP (DBP, lag1), mean arterial BP (MABP, lag1), and HR (lag01), respectively. Meanwhile, the serum concentrations of hs-CRP, 8-OHdG, and t-PA were all increased by O₃ exposure, but the PMA level was decreased. Stratification analyses showed that the estimated effects of O₃ on DBP, MABP, and HR in GSTM1-sufficient subjects were significantly higher than in GSTM1-null subjects. Moreover, GSTM1-null genotype enhanced O₃-induced increases, albeit insignificant, in levels of serum hs-CRP, 8-OHdG, and t-PA compared with GSTM1-sufficient genotype. Insignificant increases in hs-CRP and t-PA were also detected in GSTT1-null subjects. Taken together, our findings indicate that acute exposure to ambient O₃ induces autonomic alterations, systemic inflammation, oxidative stress, and fibrinolysis in healthy young subjects. GSTM1 genotype presents the trend of modifying O₃-induced cardiovascular effects.

Systems biology and big data in asthma and allergy: recent discoveries and emerging challenges

Asthma is a common condition caused by immune and respiratory dysfunction, and it is often linked to allergy. A systems perspective may prove helpful in unravelling the complexity of asthma and allergy. Our aim is to give an overview of systems biology approaches used in allergy and asthma research. Specifically, we describe recent "omic"-level findings, and examine how these findings have been systematically integrated to generate further insight.Current research suggests that allergy is driven by genetic and epigenetic factors, in concert with environmental factors such as microbiome and diet, leading to early-life disturbance in immunological development and disruption of balance within key immuno-inflammatory pathways. Variation in inherited susceptibility and exposures causes heterogeneity in manifestations of asthma and other allergic diseases. Machine learning approaches are being used to explore this heterogeneity, and to probe the pathophysiological patterns or "endotypes" that correlate with subphenotypes of asthma and allergy. Mathematical models are being built based on genomic, transcriptomic and proteomic data to predict or discriminate disease phenotypes, and to describe the biomolecular networks behind asthma.The use of systems biology in allergy and asthma research is rapidly growing, and has so far yielded fruitful results. However, the scale and multidisciplinary nature of this research means that it is accompanied by new challenges. Ultimately, it is hoped that systems medicine, with its integration of omics data into clinical practice, can pave the way to more precise, personalised and effective management of asthma.

Dysregulation of the glutaredoxin/S-glutathionylation redox axis in lung diseases

Glutathione is a major redox buffer, reaching millimolar concentrations within cells and high micromolar concentrations in airways. While glutathione has been traditionally known as an antioxidant defense mechanism that protects the lung tissue from oxidative stress, glutathione more recently has become recognized for its ability to become covalently conjugated to reactive cysteines within proteins, a modification known as S-glutathionylation (or S-glutathiolation or protein mixed disulfide). S-glutathionylation has the potential to change the structure and function of the target protein, owing to its size (the addition of three amino acids) and charge (glutamic acid). S-glutathionylation also protects proteins from irreversible oxidation, allowing them to be enzymatically regenerated. Numerous enzymes have been identified to catalyze the glutathionylation/deglutathionylation reactions, including glutathione S-transferases and glutaredoxins. Although protein S-glutathionylation has been implicated in numerous biological processes, S-glutathionylated proteomes have largely remained unknown. In this paper, we focus on the pathways that regulate GSH homeostasis, S-glutathionylated proteins, and glutaredoxins, and we review methods required toward identification of glutathionylated proteomes. Finally, we present the latest findings on the role of glutathionylation/glutaredoxins in various lung diseases: idiopathic pulmonary fibrosis, asthma, and chronic obstructive pulmonary disease.

Interactions between environmental pollutants and genetic susceptibility in asthma risk

Exposure to air pollution is associated with enhanced risk of developing asthma, notably in the presence of genetic risk factors. Interaction analyses have shown that both outdoor and indoor air pollution interact with genetic variability to increase the incidence of asthma. In this review, we summarize recent progress in candidate gene-based studies, as well as genome-wide gene-air pollution interaction studies. Advances in epigenetics have provided evidence for DNA methylation as a mediator in gene-air pollution interactions. Emerging strategies for study design and statistical analyses may improve power in future studies. Improved air pollution exposure assessment methods and asthma endo-typing can also be expected to increase the ability to detect biologically driven gene-air pollution interaction effects.

Glutathione Transferase P1-1 an Enzyme Useful in Biomedicine and as Biomarker in Clinical Practice and in Environmental Pollution

Glutathione transferase P1-1 (GSTP1-1) is expressed in some human tissues and is abundant in mammalian erythrocytes (here termed e-GST). This enzyme is able to detoxify the cell from endogenous and exogenous toxic compounds by using glutathione (GSH) or by acting as a ligandin. This review collects studies that propose GSTP1-1 as a useful biomarker in different fields of application. The most relevant studies are focused on GSTP1-1 as a biosensor to detect blood toxicity in patients affected by kidney diseases. In fact, this detoxifying enzyme is over-expressed in erythrocytes when unusual amounts of toxins are present in the body. Here we review articles concerning the level of GST in chronic kidney disease patients, in maintenance hemodialysis patients and to assess dialysis adequacy. GST is also over-expressed in autoimmune disease like scleroderma, and in kidney transplant patients and it may be used to check the efficiency of transplanted kidneys. The involvement of GSTP in the oxidative stress and in other human pathologies like cancer, liver and neurodegenerative diseases, and psychiatric disorders is also reported. Promising applications of e-GST discussed in the present review are its use for monitoring human subjects living in polluted areas and mammals for veterinary purpose.

Human glutathione-S-transferase pi potentiates the cysteine-protease activity of the Der p 1 allergen from house dust mite through a cysteine redox mechanism

Environmental proteases have been widely associated to the pathogenesis of allergic disorders. Der p 1, a cysteine-protease from house dust mite (HDM) Dermatophagoides pteronyssinus, constitutes one of the most clinically relevant indoor aeroallergens worldwide. Der p 1 protease activity depends on the redox status of its catalytic cysteine residue, which has to be in the reduced state to be active. So far, it is unknown whether Der p 1-protease activity could be regulated by host redox microenvironment once it reaches the lung epithelial lining fluid in addition to endogenous mite components. In this sense, Glutathione-S-transferase pi (GSTpi), an enzyme traditionally linked to phase II detoxification, is highly expressed in human lung epithelial cells, which represent the first line of defence against aeroallergens. Moreover, GSTpi is a generalist catalyst of protein S-glutathionylation reactions, and some polymorphic variants of this enzyme has been associated to the development of allergic asthma. Here, we showed that human GSTpi increased the cysteine-protease activity of Der p 1, while GSTmu (the isoenzyme produced by the mite) did not alter it. GSTpi induces the reduction of Cys residues in Der p 1, probably by rearranging its disulphide bridges. Furthermore, GSTpi was detected in the apical medium collected from human bronchial epithelial cell cultures, and more interesting, it increased cysteine-protease activity of Der p 1. Our findings support the role of human GSTpi from airways in modulating of Der p 1 cysteine-protease activity, which may have important clinical implications for immune response to this aeroallergen in genetically susceptible individuals.