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Oxidative stress is associated with atopic indices in relation to childhood rhinitis and asthma
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Journal of Microbiology, Immunology and Infection xxx (xxxx) xxx
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Original Article
Oxidative stress is associated with atopic indices in relation to childhood rhinitis and asthma Cheryn Yu Wei Choo a,1, Kuo-Wei Yeh b,c,1, Jing-Long Huang b,c, Kuan-Wen Su c,d, Ming-Han Tsai c,d, Man-Chin Hua c,d, Sui-Ling Liao c,d, Shen-Hao Lai e, Li-Chen Chen b,c, Chih-Yung Chiu c,e,* a
College of Medicine, Chang Gung University, Taoyuan, Taiwan Division of Allergy, Asthma, and Rheumatology, Department of Pediatrics, Chang Gung Memorial Hospital, and Chang Gung University College of Medicine, Taoyuan, Taiwan c Community Medicine Research Centre, Chang Gung Memorial Hospital, Keelung, Taiwan d Department of Pediatrics, Chang Gung Memorial Hospital at Keelung, and Chang Gung University College of Medicine, Taoyuan, Taiwan e Division of Pediatric Pulmonology, Chang Gung Memorial Hospital at Linkou, College of Medicine, Chang Gung University, Taoyuan, Taiwan b
Received 11 September 2019; received in revised form 18 November 2019; accepted 20 January 2020
Available online - - -
KEYWORDS Asthma; Atopic indices; Children; Oxidative stress; Rhinitis
Abstract Background: The association between oxidative stress and atopic diseases is uncertain. Several risk factors for atopic diseases have been identified, however, a comprehensive investigation of the relationship between oxidative stress markers and atopic indices related to atopic diseases is currently lacking. Methods: We investigated 132 children who completed a 7-years follow-up in a birth cohort. Oxidative stress markers including plasma glutathione peroxidase (GPx), myeloperoxidase (MPO), total anti-oxidant capacity (TAC), and urine 8-hydroxy-20 -deoxyguanosine (8-OHdG) levels were measured. Allergen-specific IgE levels, FeNO levels, and pulmonary function tests were also obtained. Results: The activity of GPx and levels of MPO were inversely correlated to food (shrimp and crab) and house dust mite sensitization respectively. The 8-OHdG levels were strongly negatively correlated with FeNO levels (p < 0.01). A significant positive correlation was found between TAC levels and pre-and post-bronchodilator FVC % and FEV1% predicted (p < 0.05). All
* Corresponding author. Division of Pediatric Pulmonology, Chang Gung Memorial Hospital at Linkou, College of Medicine, Chang Gung University, Taoyuan, Taiwan. Fax: þ886 3 3288957. E-mail address: [email protected] (C.-Y. Chiu). 1 Cheryn Yu Wei Choo and Kuo-Wei Yeh contributed equally as co-first authors. https://doi.org/10.1016/j.jmii.2020.01.009 1684-1182/Copyright ª 2020, Taiwan Society of Microbiology. Published by Elsevier Taiwan LLC. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). Please cite this article as: Wei Choo CY et al., Oxidative stress is associated with atopic indices in relation to childhood rhinitis and asthma, Journal of Microbiology, Immunology and Infection, https://doi.org/10.1016/j.jmii.2020.01.009
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C.Y. Wei Choo et al. oxidative stress markers were not associated with the risk of atopic diseases. However, GPxrelated crab sensitization and 8-OHdG related FeNO levels were significantly associated with increased risk of allergic rhinitis, while MPO-related mite sensitization and TAC-related pulmonary function parameters were strongly associated with risk of asthma (p < 0.01). Conclusion: Oxidative stress is strongly correlated with allergic indices, potentially playing a role in the modulation of allergic responses contributing to atopic diseases. Copyright ª 2020, Taiwan Society of Microbiology. Published by Elsevier Taiwan LLC. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/bync-nd/4.0/).
Introduction Oxidative stress is the result of an imbalance between the production of reactive oxygen species (ROS) and antioxidant defense. This imbalance may worsen inflammatory conditions by enhancing the release of pro-inflammatory cytokines and altering enzymatic functions.1 Hence, it has been suggested to be implicated in various human diseases, including cancer, diabetes, and cardiovascular, neurodegenerative and respiratory diseases.2 Although oxidative stress was proposed to be associated with allergic conditions, its role in the regulation of atopic diseases is not well documented.3,4 A plethora of markers are applied to examine oxidative stress on various human diseases. However, the trace amount and short half-life of these markers confounds their measurement in the circulation of complex biological system. Glutathione peroxidase (GPx) and total anti-oxidant capacity (TAC) which represent the antioxidant defenses, and myeloperoxidase (MPO) and 8-hydroxy-20 -deoxyguanosine (8-OHdG) which signify ROS generation and ROSinduced modification respectively, are essentially stable in the circulatory system and commonly used as markers of oxidative stress.2,5 Clinically, numerous risk factors for atopic diseases including food and aeroallergen sensitization, fractional exhaled nitric oxide (FeNO), and pulmonary function parameters have been identified.6,7 However, a comprehensive approach in examining the relationship between these atopic indices and oxidative stress markers is still lacking. This major aim of this study was to determine the levels of four oxidative stress markers, GPx, MPO, 8-OHdG, and TAC, at age 7 in children from a birth cohort in the Prediction of Allergies in Taiwanese Chinese (PATCH) study. The relationship between oxidative stress markers and atopic indices were assessed, and their relevance to the risk of atopic diseases was also examined.
Methods Study population and data collection The PATCH study is a population-based joint study initiated in 2007 to investigate the epidemiology and predictive factors of allergies in Taiwanese children.8 Newborn infants delivered at Keelung Chang Gung Memorial Hospital (CGMH) recruited in one birth cohort in PATCH study who completed
a 7-year follow-up were enrolled into this study. Demographic data and detailed information on potential confounding variables for atopic diseases, including family history of atopy, exposure to passive smoking and household income, were collected and analyzed. The childhood atopic diseases consisted of eczema, allergic rhinitis, and asthma, which were diagnosed by a pediatric pulmonologist according to the criteria as described in our previous study.9 This study was approved by the Ethics Committee of Chang Gung Memorial Hospital (No. 104e8925C). All experiments in this study were performed in accordance with the relevant guidelines and regulations and written informed consent was obtained from a parent and/or legal guardian of all study subjects.
Measurement of serum total and allergen-specific immunoglobin E (IgE) The serum level of total IgE was measured by ImmunoCAP (Phadia Uppsala, Sweden) following the manufacturer’s instructions. Allergen-specific IgE in serum was determined by a commercial assay for IgE (ImmunoCAP Phadiatop Infant, Phadia) against food and inhalant allergens, which included crab, shrimp, Dermatophagoides pteronyssinus and Dermatophagoides farinae.10 The level of allergenspecific IgE in serum ranged from 0.10 to 100 kU/L and any measurement above the upper limit of the range was assigned the value of 100 kU/L. Allergen-specific IgE level greater than 0.35 kU/L was defined as positive and indicative of allergic sensitization.11
Measurement of oxidative stress markers The activity of GPx in blood plasma was determined using a commercially available reagent kit (Randox Laboratories LTDA) and was quantified using an automatic chemical analyzer, Thermo Indiko (ABX, Montpellier, France), by measuring the rate of oxidation of NADPH to NADPþ at 340 nm. Plasma levels of MPO were measured using Bioxytech MPO enzyme-linked immunosorbent assay (ELISA) (Oxis International Inc., Portland, OR, USA) according to the manufacturer’s instructions. The amount of MPO was enzymatically measured upon addition of 4nitrophenylphosphate. MPO levels less than 48.4 ng/mL were given the value of 48.4 ng/mL due to limit of detection.
Please cite this article as: Wei Choo CY et al., Oxidative stress is associated with atopic indices in relation to childhood rhinitis and asthma, Journal of Microbiology, Immunology and Infection, https://doi.org/10.1016/j.jmii.2020.01.009
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Oxidative stress and childhood allergies Urinary levels of 8-OHdG were measured using the 8OHdG ELISA kit (Japan Institute for the Control of Aging, Fukuroi, Japan) according to the manufacturer’s instructions. The kit is a competitive in vitro ELISA assay system used to quantify 8-OHdG, an oxidative DNA product. Total anti-oxidant capacity (TAC) of blood plasma was analyzed by a ferric reducing antioxidant power (FRAP) assay using the automatic chemical analyzer, Thermo Indiko (ABX, Montpellier, France). The antioxidant capacity was assessed by the ability to reduce ferric (Fe3þ) to ferrous (Fe2þ) ion in the presence of a (Fe2þ) stabilizing legend. The levels of oxidative stress markers were divided into four quartiles in increasing order, with the first quartile used as the reference. The MPO concentrations were analyzed as categorical variables by division into two groups because of the limit of detection of the assay. The first quartile (57.7 ng/mL) was defined as low MPO levels representing low inflammatory status while the second to fourth quartiles (>57.7 ng/mL) were defined as high MPO levels with high inflammatory status.
Measurement of FeNO FeNO levels in the expiratory volume were obtained using an electrochemical analyzer with the portable hand-held device NIOX MINO (Aerocrine AB, Sweden) according to the European Respiratory Society (ERS) and the American Thoracic Society (ATS) recommendations.12 All measurements of FeNO were performed prior to spirometry and reversibility testing. A FeNO level <20 parts per billion (ppb) was considered as normal and 20 ppb as increased, which signified the presence of eosinophilic inflammation.13
Measurement of pulmonary function test A pre- and post-bronchodilator spirometry (Spirolab II, Medical International Research, Roma, Italy) was performed according to the ERS/ATS standards.14 At least three acceptable forced vital capacity maneuvers were recorded. The data obtained included forced vital capacity (FVC), forced expiratory volume in the first second (FEV1) and FEV1/FVC ratio. For every parameter measured, actual and predicted values for age, sex, height and weight were obtained, and percentages (%) of the predicted values were calculated. Actual values of the parameters were analyzed separately based on sex to adjust for their differences.
Statistical analysis Demographic data of population characteristics by questionnaire and prevalence of physician-diagnosed atopic diseases were collected and analyzed. The Student t test or ManneWhitney U test were used to compare continuous variables, while the chi-square test or Fisher’s exact test were used to compare categorical variables between two groups. Spearman’s correlation tests were used to determine the correlation of oxidative stress markers with allergen-specific IgE levels and pulmonary function parameters. The associations of atopic diseases measured as a binary outcome with oxidative stress markers and their
3 related atopic indices were calculated by the odds ratio (OR), using multiple logistic regression analysis by adjusting for confounding factors. All statistical analyses were performed using the Statistical Package for the Social Sciences (IBM SPSS Statistics for Windows, Version 20.0. Armonk, NY: IBM) and graphs were drawn using GraphPad Prism Version 5.01 software (GraphPad Software Inc, California, USA). All statistical hypothesis tests were two tailed and a p-value of less than 0.05 was considered to be significant.
Results Population characteristics A total of 258 children were initially recruited, of which 155 (60.1%) children who completed 7 years of clinical followup were enrolled in this study. Twenty-three children who present with a combination of eczema, asthma or rhinitis when diagnosed at age 7 were excluded. Atopic diseases including eczema, allergic rhinitis and asthma alone were predominantly diagnosed in 9, 59 and 10 children, respectively, at 7 years of age. The comparisons of baseline characteristics between children with atopic diseases and healthy controls were therefore analyzed (Table 1). Total IgE levels and the prevalence of sensitization to house dust mites were significantly higher in children with atopic diseases as compared to the healthy controls (p < 0.001). There was no statistically significant difference in sex, maternal atopy, passive smoking exposure, household income and oxidative stress markers.
Oxidative stress markers and allergen sensitization At the age of 7 years, the activity of GPx was significantly lower in children with crab or shrimp sensitization as compared to those without sensitization (Fig. 1A). A statistically significant negative correlation was seen between GPx activity and crab-specific IgE levels (r Z 0.274, p < 0.01) as well as shrimp-specific IgE level (r Z 0.239, p Z 0.013) (Fig. 1B). In children with low MPO levels in the first quartile, allergen-specific IgE levels of D. pteronyssinus and D. farinae were significantly higher compared to those of with high MPO levels in the second to fourth quartile (Fig. 1C). Furthermore, there was a significant negative correlation between MPO levels and D. pteronyssinus-specific IgE levels (r Z 0.224, p Z 0.019) as well as D. farinae-specific IgE levels (r Z 0.244, p Z 0.011) (Fig. 1D).
Oxidative stress markers and pulmonary function tests The 8-OHdG levels were significantly higher in children with FeNO levels <20 ppb (n Z 90) as compared to those with FeNO levels 20 ppb (n Z 29). A statistically significant negative correlation was also found between 8-OHdG levels and FeNO levels (r Z 0.356, p < 0.01) (Fig. 2A). The level of TAC had a significant positive correlation with both pre-bronchodilator FVC % predicted (r Z 0.287, p < 0.01) and post-bronchodilator FVC % predicted
Please cite this article as: Wei Choo CY et al., Oxidative stress is associated with atopic indices in relation to childhood rhinitis and asthma, Journal of Microbiology, Immunology and Infection, https://doi.org/10.1016/j.jmii.2020.01.009
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C.Y. Wei Choo et al. Table 1
Epidemiologic characteristics of the 132 children investigated in this study.
Characteristics
Age (yr) Sex, male Maternal age (yr) Maternal atopy Passive smoking Household income Low, 500,000 NTD Medium, 500,000e1,000,000 NTD High, > 1,000,000 NTD Total IgE, kU/L Allergen-specific IgE, kU/L Crab Shrimp D. pteronyssinus D. farinae Oxidative stress markers GPx, U/g MPO, ng/mL 8-OHdG, ng/mg TAC, umol/L
Controls
Eczema
Rhinitis
Asthma
(n Z 54)
(n Z 9)
(n Z 59)
(n Z 10)
7.19 0.2 26 (48.1%) 31.4 4.0 22 (40.7%) 18 (33.3%)
7.12 0.2 5 (55.6%) 30 3.8 2 (22.2%) 5 (55.6%)
7.23 0.3 34 (57.6%) 31.3 4.1 28 (47.5%) 27 (45.8%)
7.27 0.3 7 (70.0%) 31.2 4.04 5 (50.0%) 5 (50.0%)
20 (38.5%) 23 (44.2%) 9 (17.3%) 165.1 348.7
1 (11.1%) 5 (55.6%) 3 (33.3%) 621.6 516.9
22 (37.9%) 27 (46.6%) 9 (15.5%) 499.0 842.1
2 (28.6%) 4 (57.1%) 1 (14.3%) 657.9 675.9
<0.001
1.1 2.5 1.4 3.2 66.3 36.1 44.1 32.8
0.7 2.4 0.8 2.9 35.1 37.0 27.5 32.7
0.3 0.9 0.4 1.0 59.5 45.5 50.3 44.3
0.397 0.646 <0.001 <0.001
39.6 9.0 55.7 25.6 60.0 18.8 438.1 42.5
38.2 10.4 66.7 47.0 61.9 16.2 433.2 64.5
38.0 5.4 48.0 0.0 72.8 18.2 439.8 75.7
0.784 0.253 0.344 0.927
0.8 0.9 9.0 6.0
3.5 3.9 23.2 16.7
38.7 15.4 65.1 35.4 67.3 21.1 426.4 69.6
p-value
0.280 0.555 0.834 0.499 0.399 0.722
Data shown are mean SD or number (%) of patients as appropriate. yr, year; NTD, New Taiwan Dollar; IgE, immunoglobulin E; GPx, glutathione peroxidase; MPO, myeloperoxidase; 8-OHdG, 8-hydroxy-20 -deoxyguanosine; TAC, total anti-oxidant capacity.
Figure 1. The relationship between oxidative stress markers (GPx and MPO) with allergen sensitization. Comparisons of GPx activity between children with and without crab or shrimp sensitization (A). Correlations between GPx activity and crab- or shrimpspecific IgE levels (B). Comparisons of D. pteronyssinus- and D. farinae-specific IgE levels between children with low MPO levels in the first quartile and those with high MPO levels in the second to fourth quartile (C). Correlations between MPO levels and D. pteronyssinus-specific IgE levels as well as D. farinae-specific IgE levels (D). *p < 0.05.
(r Z 0.214, p Z 0.027) (Fig. 2B). A significant positive correlation was also seen between TAC levels and pre- and post-bronchodilator FEV1% predicted (p < 0.05) (Fig. 2C).
Furthermore, TAC levels had a significant positive correlation with pre-bronchodilator FEV1 (r Z 0.337, p Z 0.017) in girls, but not in boys.
Please cite this article as: Wei Choo CY et al., Oxidative stress is associated with atopic indices in relation to childhood rhinitis and asthma, Journal of Microbiology, Immunology and Infection, https://doi.org/10.1016/j.jmii.2020.01.009
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Oxidative stress and childhood allergies
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Figure 2. The relationship between oxidative stress markers (8-OHdG and TAC) and pulmonary function tests. Comparison and correlation between 8-OHdG levels and FeNO levels (A). Correlations between TAC levels and pre- and post-bronchodilator FVC % predicted (B). Correlations between TAC levels and pre- and post-bronchodilator FEV1% predicted (C). *p < 0.05.
Association of oxidative stress markers with atopic indices and atopic diseases Table 2 presents the logistic regression analysis to calculate the odds ratio of oxidative stress markers and their related atopic indices for risk of atopic diseases. There were no associations of all oxidative stress markers with the risk of atopic diseases. However, GPx-related crab sensitization (OR 3.03; 95% CI 1.006e8.614; p Z 0.038) and 8-OHdG related FeNO levels (OR 4.34; 95% CI 1.435e12.532; p Z 0.009) were significantly associated with an increased risk of allergic rhinitis. Both MPO related D. pteronyssinusand D. farinae-specific IgE levels were significantly associated with an increased risk of all atopic diseases. Furthermore, TAC-related pulmonary function tests including FVC% and FEV1% predicted were significantly associated with asthma (p < 0.01).
Discussion Oxidative stress has been widely implicated in a variety of human diseases and their causes. However, its role in the allergic responses relevant to atopic diseases remains unclear, especially in early childhood. This study provides a comprehensive overview of oxidative stress markers (GPx, MPO, 8-OHdG and TAC) with various atopic indices related to atopic diseases. Despite the fact that there is no association between oxidative stress and atopic diseases, a strong association of oxidative stress with allergic sensitization and pulmonary function suggests that oxidative
stress plays a role in the modulation of allergy relevant reactions for childhood atopic diseases. GPx is a selenium-dependent anti-oxidative enzyme that catalyses the reduction of hydrogen peroxides at the expense of glutathione (GSH).15,16 Selenium is an essential micronutrient for humans and can be obtained from dietary intake of fish and shellfish, including crab and shrimp.17,18 Children with food allergy appear to have lower blood concentrations of selenium, suggesting that food allergic reactions tend to have negative effects on the absorption of dietary selenium.19 In this study, we have demonstrated a significantly lower activity of GPx in children with sensitization to crab or shrimp. As shellfish is one of the major sources of selenium,18,20,21 it can be postulated that the low GPx activity may be due to the sensitization to crab or shrimp with potentially decreased selenium absorption. MPO is stored primarily in neutrophils and monocytes, where it is released in response to local inflammation.22 MPO plays an essential part in the innate immune system by catalyzing the production of HOCl from H2O2 to generate reactive oxygen species (ROS), hence participating in host antimicrobial defense.23,24 In our study, there was an inverse correlation between MPO levels and allergic sensitization to house dust mites. Recent studies have reported that house dust mites may act as carriers of IgE-reactive bacterial antigens, inducing the production of ROS leading to oxidative damage in the lungs.6,25 A low MPO level in children with high mite sensitization may be due to an increase in its consumption from processing ROS, which were derived from bacterial antigens carried by house dust mites.
Please cite this article as: Wei Choo CY et al., Oxidative stress is associated with atopic indices in relation to childhood rhinitis and asthma, Journal of Microbiology, Immunology and Infection, https://doi.org/10.1016/j.jmii.2020.01.009
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OR, odds ratio; CI, confidence interval; GPx, glutathione peroxidase; MPO, myeloperoxidase; 8-OHdG, 8-hydroxy-20 -deoxyguanosine; FeNO, fractional exhaled nitric oxide; TAC, total antioxidant capacity; FVC, forced vital capacity; FEV1, forced expiratory volume in the first second; % pred, percentage of predicted; pre-bd, pre-bronchodilator; post-bd, post-bronchodilator. *Adjusted p-values for sex, maternal atopy, passive smoking, and household income. All p-values < 0.05, which is in bold, are significant.
(0.916e1.091) (0.072e6.084) (0.315e10.786) (0.876e1.070) (1.003e1.045) (1.004e1.047) (0.974e1.110) (0.060e5.558) (0.969e1.012) (0.831e0.974) (0.902e1.046) (0.813e0.963) (0.897e1.040) 1.00 0.66 1.84 0.97 1.02 1.03 1.04 0.58 0.99 0.90 0.97 0.89 0.97
Adjusted OR (95% CI) p-value*
0.980 0.038 0.052 0.916 <0.001 <0.001 0.231 0.009 0.513 0.562 0.861 0.828 0.828 (0.969e1.033) (1.006e8.614) (0.990e8.021) (0.989e1.010) (1.018e1.050) (1.022e1.072) (0.964e1.009) (1.435e12.532) (0.996e1.008) (0.962e1.021) (0.966e1.029) (0.967e1.027) (0.971e1.035) 1.00 3.03 2.82 1.00 1.03 1.05 0.99 4.34 1.00 0.99 1.00 1.00 1.00
Adjusted OR (95% CI) p-value*
0.817 0.138 0.553 0.439 0.007 0.028 0.594 0.472 0.667 0.435 0.658 0.342 0.266 (0.953e1.064) (0.672e17.763) (0.295e9.784) (0.957e1.019) (1.009e1.055) (1.003e1.049) (0.938e1.037) (0.380e8.046) (0.989e1.017) (0.966e1.084) (0.952e1.080) (0.969e1.094) (0.973e1.105)
Adjusted OR (95% CI)
1.01 3.46 1.70 0.99 1.03 1.03 0.99 1.75 1.00 1.02 1.01 1.03 1.04 GPx, U/g Crab, kU/L Shrimp, kU/L MPO, ng/mL D. pteronyssinus D. farinae 8-OHdG, ng/mg FeNO, ppb TAC, mmol/L FVC % pred (pre-bd) FVC % pred (post-bd) FEV1% pred (pre-bd) FEV1% pred (post-bd)
Allergic rhinitis Eczema Atopic indices
Table 2
Relationships of oxidative stress markers and their related atopic indices with risk of atopic diseases at age 7 years.
Asthma
p-value*
C.Y. Wei Choo et al.
0.991 0.714 0.497 0.526 0.025 0.021 0.241 0.636 0.371 0.009 0.444 0.005 0.358
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Urinary 8-OHdG is often used as an indicator of cellular DNA oxidative stress. ROS causes hydroxylation of guanine, which triggers DNA repair enzymes and excretion of 8-OHdG in urine.26,27 Our study observed a negative correlation between 8-OHdG and fractional exhaled nitric oxide, a biomarker of airway inflammation. Nitric oxide reacts with superoxide to form peroxynitrite, initiating cellular degenerative changes and inflammation.28 Thus, the decrease in nitric oxide leads to the accumulation of superoxide and hydrogen peroxide for DNA damage, as reflected from an increase in urinary 8-OHdG. TAC determination is an analyte commonly used to assess the free radical-antioxidant balance in biological systems. In our study, the level of TAC was positively correlated with FVC % predicted and FEV1% predicted which strongly associated with risk of asthma. This finding is consistent with previous studies showing that asthmatic patients with higher TAC levels tend to have an increase in pulmonary functions.29,30 TAC levels therefore provide an important link to pulmonary function, potentially using as a biomarker for monitoring therapeutic efficacy and prognosis in children with asthma. Despite the fact that some studies had been reported on the relationship between oxidative stress markers and atopic diseases, the results were inconsistent.3,4,31 Although oxidative stress markers were not associated with atopic diseases in this study, their related atopic indices including food and aeroallergen sensitization, FeNO, and lung function parameters were strongly related to atopic diseases as described in previous studies.6,7 Thus, oxidative stress markers may potentially play a role in the modulation of allergic responses contributing to atopic diseases. Furthermore, dietary antioxidant intake such as vitamins A, C and E, and b-carotene have linked to improved pulmonary function and decreased risk of asthma.32 Clinically, antioxidant supplements may serve as a complementary treatment for more effective therapeutic approach towards atopic diseases. Limitations of this study include a relatively small sample size of 132 children and a limited power to detect a statistically significant association of subanalyses. Subphenotypes of early-onset atopic diseases including transient wheeze, asthmatic, or eczema may underestimate the extent of atopic diseases. Potential confounders of sex, passive smoking, diet, and testing technique may influence the measurement of oxidative stress markers and pulmonary function parameters. However, a standardized measurement method has used to ensure more consistent results in this study. Most importantly, the strength of this study lies in its longitudinal follow-up in children from a birth cohort with accurate diagnostic evaluations for atopic diseases at outpatient clinics. A comprehensive survey of serial atopic indices related to atopic diseases with oxidative stress markers makes the results demonstrated here valid and potentially important. In conclusion, oxidative stress appears to be associated with atopic indices, but not with atopic diseases. A decrease in the activity of GPx and levels of MPO is correlated with an increase in allergen-specific IgE levels. Furthermore, a decrease in urinary 8-OHdG levels is correlated with an increase in FeNO levels. Moreover,
Please cite this article as: Wei Choo CY et al., Oxidative stress is associated with atopic indices in relation to childhood rhinitis and asthma, Journal of Microbiology, Immunology and Infection, https://doi.org/10.1016/j.jmii.2020.01.009
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Oxidative stress and childhood allergies decreased TAC levels are correlated with decreased pulmonary function tests. Although oxidative stress appears to have no associations with atopic diseases, their related atopic indices are strongly associated with increased risk of atopic diseases. These findings suggest that oxidative stress potentially plays a role in the modulation of allergic responses contributing to atopic diseases. However, more research should be carried out to clarify its role in the pathogenesis of these diseases.
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10. 11.
12.
Funding
13.
This study was supported by research grant of CMRPG3E1191-5 from the Chang Gung Medical Foundation, Taiwan.
14.
Declaration of Competing Interest
15. 16.
All the authors declare no conflicts of interest in relation to the present study.
17.
Acknowledgment
18.
We are extremely grateful to all the families who took part in this study, all pediatricians for their help in recruiting them and the whole PATCH team, which includes interviewers, nurses, computer and laboratory technicians and research assistants.
19.
References
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sensitization in early childhood. Pediatr Allergy Immunol 2014; 25:767e72. Lee AJ, Thalayasingam M, Lee BW. Food allergy in Asia: how does it compare? Asia Pac Allergy 2013;3:3e14. Sunyer J, Anto JM, Castellsague J, Soriano JB, Roca J. Total serum IgE is associated with asthma independently of specific IgE levels. The Spanish Group of the European Study of Asthma. Eur Respir J 1996;9:1880e4. Dweik RA, Boggs PB, Erzurum SC, Irvin CG, Leigh MW, Lundberg JO, et al. An official ATS clinical practice guideline: interpretation of exhaled nitric oxide levels (FENO) for clinical applications. Am J Respir Crit Care Med 2011;184:602e15. Deykin A, Massaro AF, Coulston E, Drazen JM, Israel E. Exhaled nitric oxide following repeated spirometry or repeated plethysmography in healthy individuals. Am J Respir Crit Care Med 2000;161:1237e40. Miller MR, Hankinson J, Brusasco V, Burgos F, Casaburi R, Coates A, et al. Standardisation of spirometry. Eur Respir J 2005;26:319e38. Mates JM, Perez-Gomez C, Nunez de Castro I. Antioxidant enzymes and human diseases. Clin Biochem 1999;32:595e603. Li C, Deng X, Xie X, Liu Y, Friedmann Angeli JP, Lai L. Activation of glutathione peroxidase 4 as a novel anti-inflammatory strategy. Front Pharmacol 2018;9:1120. Rayma MP. The importance of selenium to human health. Lancet 2000;356:233e41. Olmedo P, Hernandez AF, Pla A, Femia P, Navas-Acien A, Gil F. Determination of essential elements (copper, manganese, selenium and zinc) in fish and shellfish samples. Risk and nutritional assessment and mercury-selenium balance. Food Chem Toxicol 2013;62:299e307. Kamer B, Wasowicz W, Pyziak K, Kamer-Bartosinska A, Gromadzinska J, Pasowska R. Role of selenium and zinc in the pathogenesis of food allergy in infants and young children. Arch Med Sci 2012;8:1083e8. Yamashita Y, Yamashita M, Iida H. Selenium content in seafood in Japan. Nutrients 2013;5:388e95. Calatayud M, Devesa V, Virseda JR, Barbera R, Montoro R, Velez D. Mercury and selenium in fish and shellfish: occurrence, bioaccessibility and uptake by Caco-2 cells. Food Chem Toxicol 2012;50:2696e702. Anatoliotakis N, Deftereos S, Bouras G, Giannopoulos G, Tsounis D, Angelidis C, et al. Myeloperoxidase: expressing inflammation and oxidative stress in cardiovascular disease. Curr Top Med Chem 2013;13:115e38. Bjornsdottir H, Welin A, Michaelsson E, Osla V, Berg S, Christenson K, et al. Neutrophil NET formation is regulated from the inside by myeloperoxidase-processed reactive oxygen species. Free Radic Biol Med 2015;89:1024e35. Segal AW. How neutrophils kill microbes. Annu Rev Immunol 2005;23:197e223. Dzoro S, Mittermann I, Resch-Marat Y, Vrtala S, Nehr M, Hirschl AM, et al. House dust mites as potential carriers for IgE sensitization to bacterial antigens. Allergy 2018;73: 115e24. Helbock HJ, Beckman KB, Ames BN. 8-Hydroxydeoxyguanosine and 8-hydroxyguanine as biomarkers of oxidative DNA damage. Methods Enzymol 1999;300:156e66. Chiou CC, Chang PY, Chan EC, Wu TL, Tsao KC, Wu JT. Urinary 8-hydroxydeoxyguanosine and its analogs as DNA marker of oxidative stress: development of an ELISA and measurement in both bladder and prostate cancers. Clin Chim Acta 2003;334: 87e94. Salvemini D, Doyle TM, Cuzzocrea S. Superoxide, peroxynitrite and oxidative/nitrative stress in inflammation. Biochem Soc Trans 2006;34:965e70. Yoon SY, Kim TB, Baek S, Kim S, Kwon HS, Lee YS, et al. The impact of total antioxidant capacity on pulmonary function
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8 in asthma patients. Int J Tubercul Lung Dis 2012;16: 1544e50. 30. Fatani SH. Biomarkers of oxidative stress in acute and chronic bronchial asthma. J Asthma 2014;51:578e84. 31. Kristjansson S, Shimizu T, Strannegard IL, Wennergren G. Eosinophil cationic protein, myeloperoxidase and tryptase in
C.Y. Wei Choo et al. children with asthma and atopic dermatitis. Pediatr Allergy Immunol 1994;5:223e9. 32. Garcia-Larsen V, Amigo H, Bustos P, Bakolis I, Rona RJ. Ventilatory function in young adults and dietary antioxidant intake. Nutrients 2015;7:2879e96.
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Journal of Microbiology, Immunology and Infection xxx (xxxx) xxx
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Original Article
Oxidative stress is associated with atopic indices in relation to childhood rhinitis and asthma Cheryn Yu Wei Choo a,1, Kuo-Wei Yeh b,c,1, Jing-Long Huang b,c, Kuan-Wen Su c,d, Ming-Han Tsai c,d, Man-Chin Hua c,d, Sui-Ling Liao c,d, Shen-Hao Lai e, Li-Chen Chen b,c, Chih-Yung Chiu c,e,* a
College of Medicine, Chang Gung University, Taoyuan, Taiwan Division of Allergy, Asthma, and Rheumatology, Department of Pediatrics, Chang Gung Memorial Hospital, and Chang Gung University College of Medicine, Taoyuan, Taiwan c Community Medicine Research Centre, Chang Gung Memorial Hospital, Keelung, Taiwan d Department of Pediatrics, Chang Gung Memorial Hospital at Keelung, and Chang Gung University College of Medicine, Taoyuan, Taiwan e Division of Pediatric Pulmonology, Chang Gung Memorial Hospital at Linkou, College of Medicine, Chang Gung University, Taoyuan, Taiwan b
Received 11 September 2019; received in revised form 18 November 2019; accepted 20 January 2020
Available online - - -
KEYWORDS Asthma; Atopic indices; Children; Oxidative stress; Rhinitis
Abstract Background: The association between oxidative stress and atopic diseases is uncertain. Several risk factors for atopic diseases have been identified, however, a comprehensive investigation of the relationship between oxidative stress markers and atopic indices related to atopic diseases is currently lacking. Methods: We investigated 132 children who completed a 7-years follow-up in a birth cohort. Oxidative stress markers including plasma glutathione peroxidase (GPx), myeloperoxidase (MPO), total anti-oxidant capacity (TAC), and urine 8-hydroxy-20 -deoxyguanosine (8-OHdG) levels were measured. Allergen-specific IgE levels, FeNO levels, and pulmonary function tests were also obtained. Results: The activity of GPx and levels of MPO were inversely correlated to food (shrimp and crab) and house dust mite sensitization respectively. The 8-OHdG levels were strongly negatively correlated with FeNO levels (p < 0.01). A significant positive correlation was found between TAC levels and pre-and post-bronchodilator FVC % and FEV1% predicted (p < 0.05). All
* Corresponding author. Division of Pediatric Pulmonology, Chang Gung Memorial Hospital at Linkou, College of Medicine, Chang Gung University, Taoyuan, Taiwan. Fax: þ886 3 3288957. E-mail address: [email protected] (C.-Y. Chiu). 1 Cheryn Yu Wei Choo and Kuo-Wei Yeh contributed equally as co-first authors. https://doi.org/10.1016/j.jmii.2020.01.009 1684-1182/Copyright ª 2020, Taiwan Society of Microbiology. Published by Elsevier Taiwan LLC. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). Please cite this article as: Wei Choo CY et al., Oxidative stress is associated with atopic indices in relation to childhood rhinitis and asthma, Journal of Microbiology, Immunology and Infection, https://doi.org/10.1016/j.jmii.2020.01.009
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C.Y. Wei Choo et al. oxidative stress markers were not associated with the risk of atopic diseases. However, GPxrelated crab sensitization and 8-OHdG related FeNO levels were significantly associated with increased risk of allergic rhinitis, while MPO-related mite sensitization and TAC-related pulmonary function parameters were strongly associated with risk of asthma (p < 0.01). Conclusion: Oxidative stress is strongly correlated with allergic indices, potentially playing a role in the modulation of allergic responses contributing to atopic diseases. Copyright ª 2020, Taiwan Society of Microbiology. Published by Elsevier Taiwan LLC. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/bync-nd/4.0/).
Introduction Oxidative stress is the result of an imbalance between the production of reactive oxygen species (ROS) and antioxidant defense. This imbalance may worsen inflammatory conditions by enhancing the release of pro-inflammatory cytokines and altering enzymatic functions.1 Hence, it has been suggested to be implicated in various human diseases, including cancer, diabetes, and cardiovascular, neurodegenerative and respiratory diseases.2 Although oxidative stress was proposed to be associated with allergic conditions, its role in the regulation of atopic diseases is not well documented.3,4 A plethora of markers are applied to examine oxidative stress on various human diseases. However, the trace amount and short half-life of these markers confounds their measurement in the circulation of complex biological system. Glutathione peroxidase (GPx) and total anti-oxidant capacity (TAC) which represent the antioxidant defenses, and myeloperoxidase (MPO) and 8-hydroxy-20 -deoxyguanosine (8-OHdG) which signify ROS generation and ROSinduced modification respectively, are essentially stable in the circulatory system and commonly used as markers of oxidative stress.2,5 Clinically, numerous risk factors for atopic diseases including food and aeroallergen sensitization, fractional exhaled nitric oxide (FeNO), and pulmonary function parameters have been identified.6,7 However, a comprehensive approach in examining the relationship between these atopic indices and oxidative stress markers is still lacking. This major aim of this study was to determine the levels of four oxidative stress markers, GPx, MPO, 8-OHdG, and TAC, at age 7 in children from a birth cohort in the Prediction of Allergies in Taiwanese Chinese (PATCH) study. The relationship between oxidative stress markers and atopic indices were assessed, and their relevance to the risk of atopic diseases was also examined.
Methods Study population and data collection The PATCH study is a population-based joint study initiated in 2007 to investigate the epidemiology and predictive factors of allergies in Taiwanese children.8 Newborn infants delivered at Keelung Chang Gung Memorial Hospital (CGMH) recruited in one birth cohort in PATCH study who completed
a 7-year follow-up were enrolled into this study. Demographic data and detailed information on potential confounding variables for atopic diseases, including family history of atopy, exposure to passive smoking and household income, were collected and analyzed. The childhood atopic diseases consisted of eczema, allergic rhinitis, and asthma, which were diagnosed by a pediatric pulmonologist according to the criteria as described in our previous study.9 This study was approved by the Ethics Committee of Chang Gung Memorial Hospital (No. 104e8925C). All experiments in this study were performed in accordance with the relevant guidelines and regulations and written informed consent was obtained from a parent and/or legal guardian of all study subjects.
Measurement of serum total and allergen-specific immunoglobin E (IgE) The serum level of total IgE was measured by ImmunoCAP (Phadia Uppsala, Sweden) following the manufacturer’s instructions. Allergen-specific IgE in serum was determined by a commercial assay for IgE (ImmunoCAP Phadiatop Infant, Phadia) against food and inhalant allergens, which included crab, shrimp, Dermatophagoides pteronyssinus and Dermatophagoides farinae.10 The level of allergenspecific IgE in serum ranged from 0.10 to 100 kU/L and any measurement above the upper limit of the range was assigned the value of 100 kU/L. Allergen-specific IgE level greater than 0.35 kU/L was defined as positive and indicative of allergic sensitization.11
Measurement of oxidative stress markers The activity of GPx in blood plasma was determined using a commercially available reagent kit (Randox Laboratories LTDA) and was quantified using an automatic chemical analyzer, Thermo Indiko (ABX, Montpellier, France), by measuring the rate of oxidation of NADPH to NADPþ at 340 nm. Plasma levels of MPO were measured using Bioxytech MPO enzyme-linked immunosorbent assay (ELISA) (Oxis International Inc., Portland, OR, USA) according to the manufacturer’s instructions. The amount of MPO was enzymatically measured upon addition of 4nitrophenylphosphate. MPO levels less than 48.4 ng/mL were given the value of 48.4 ng/mL due to limit of detection.
Please cite this article as: Wei Choo CY et al., Oxidative stress is associated with atopic indices in relation to childhood rhinitis and asthma, Journal of Microbiology, Immunology and Infection, https://doi.org/10.1016/j.jmii.2020.01.009
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Oxidative stress and childhood allergies Urinary levels of 8-OHdG were measured using the 8OHdG ELISA kit (Japan Institute for the Control of Aging, Fukuroi, Japan) according to the manufacturer’s instructions. The kit is a competitive in vitro ELISA assay system used to quantify 8-OHdG, an oxidative DNA product. Total anti-oxidant capacity (TAC) of blood plasma was analyzed by a ferric reducing antioxidant power (FRAP) assay using the automatic chemical analyzer, Thermo Indiko (ABX, Montpellier, France). The antioxidant capacity was assessed by the ability to reduce ferric (Fe3þ) to ferrous (Fe2þ) ion in the presence of a (Fe2þ) stabilizing legend. The levels of oxidative stress markers were divided into four quartiles in increasing order, with the first quartile used as the reference. The MPO concentrations were analyzed as categorical variables by division into two groups because of the limit of detection of the assay. The first quartile (57.7 ng/mL) was defined as low MPO levels representing low inflammatory status while the second to fourth quartiles (>57.7 ng/mL) were defined as high MPO levels with high inflammatory status.
Measurement of FeNO FeNO levels in the expiratory volume were obtained using an electrochemical analyzer with the portable hand-held device NIOX MINO (Aerocrine AB, Sweden) according to the European Respiratory Society (ERS) and the American Thoracic Society (ATS) recommendations.12 All measurements of FeNO were performed prior to spirometry and reversibility testing. A FeNO level <20 parts per billion (ppb) was considered as normal and 20 ppb as increased, which signified the presence of eosinophilic inflammation.13
Measurement of pulmonary function test A pre- and post-bronchodilator spirometry (Spirolab II, Medical International Research, Roma, Italy) was performed according to the ERS/ATS standards.14 At least three acceptable forced vital capacity maneuvers were recorded. The data obtained included forced vital capacity (FVC), forced expiratory volume in the first second (FEV1) and FEV1/FVC ratio. For every parameter measured, actual and predicted values for age, sex, height and weight were obtained, and percentages (%) of the predicted values were calculated. Actual values of the parameters were analyzed separately based on sex to adjust for their differences.
Statistical analysis Demographic data of population characteristics by questionnaire and prevalence of physician-diagnosed atopic diseases were collected and analyzed. The Student t test or ManneWhitney U test were used to compare continuous variables, while the chi-square test or Fisher’s exact test were used to compare categorical variables between two groups. Spearman’s correlation tests were used to determine the correlation of oxidative stress markers with allergen-specific IgE levels and pulmonary function parameters. The associations of atopic diseases measured as a binary outcome with oxidative stress markers and their
3 related atopic indices were calculated by the odds ratio (OR), using multiple logistic regression analysis by adjusting for confounding factors. All statistical analyses were performed using the Statistical Package for the Social Sciences (IBM SPSS Statistics for Windows, Version 20.0. Armonk, NY: IBM) and graphs were drawn using GraphPad Prism Version 5.01 software (GraphPad Software Inc, California, USA). All statistical hypothesis tests were two tailed and a p-value of less than 0.05 was considered to be significant.
Results Population characteristics A total of 258 children were initially recruited, of which 155 (60.1%) children who completed 7 years of clinical followup were enrolled in this study. Twenty-three children who present with a combination of eczema, asthma or rhinitis when diagnosed at age 7 were excluded. Atopic diseases including eczema, allergic rhinitis and asthma alone were predominantly diagnosed in 9, 59 and 10 children, respectively, at 7 years of age. The comparisons of baseline characteristics between children with atopic diseases and healthy controls were therefore analyzed (Table 1). Total IgE levels and the prevalence of sensitization to house dust mites were significantly higher in children with atopic diseases as compared to the healthy controls (p < 0.001). There was no statistically significant difference in sex, maternal atopy, passive smoking exposure, household income and oxidative stress markers.
Oxidative stress markers and allergen sensitization At the age of 7 years, the activity of GPx was significantly lower in children with crab or shrimp sensitization as compared to those without sensitization (Fig. 1A). A statistically significant negative correlation was seen between GPx activity and crab-specific IgE levels (r Z 0.274, p < 0.01) as well as shrimp-specific IgE level (r Z 0.239, p Z 0.013) (Fig. 1B). In children with low MPO levels in the first quartile, allergen-specific IgE levels of D. pteronyssinus and D. farinae were significantly higher compared to those of with high MPO levels in the second to fourth quartile (Fig. 1C). Furthermore, there was a significant negative correlation between MPO levels and D. pteronyssinus-specific IgE levels (r Z 0.224, p Z 0.019) as well as D. farinae-specific IgE levels (r Z 0.244, p Z 0.011) (Fig. 1D).
Oxidative stress markers and pulmonary function tests The 8-OHdG levels were significantly higher in children with FeNO levels <20 ppb (n Z 90) as compared to those with FeNO levels 20 ppb (n Z 29). A statistically significant negative correlation was also found between 8-OHdG levels and FeNO levels (r Z 0.356, p < 0.01) (Fig. 2A). The level of TAC had a significant positive correlation with both pre-bronchodilator FVC % predicted (r Z 0.287, p < 0.01) and post-bronchodilator FVC % predicted
Please cite this article as: Wei Choo CY et al., Oxidative stress is associated with atopic indices in relation to childhood rhinitis and asthma, Journal of Microbiology, Immunology and Infection, https://doi.org/10.1016/j.jmii.2020.01.009
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C.Y. Wei Choo et al. Table 1
Epidemiologic characteristics of the 132 children investigated in this study.
Characteristics
Age (yr) Sex, male Maternal age (yr) Maternal atopy Passive smoking Household income Low, 500,000 NTD Medium, 500,000e1,000,000 NTD High, > 1,000,000 NTD Total IgE, kU/L Allergen-specific IgE, kU/L Crab Shrimp D. pteronyssinus D. farinae Oxidative stress markers GPx, U/g MPO, ng/mL 8-OHdG, ng/mg TAC, umol/L
Controls
Eczema
Rhinitis
Asthma
(n Z 54)
(n Z 9)
(n Z 59)
(n Z 10)
7.19 0.2 26 (48.1%) 31.4 4.0 22 (40.7%) 18 (33.3%)
7.12 0.2 5 (55.6%) 30 3.8 2 (22.2%) 5 (55.6%)
7.23 0.3 34 (57.6%) 31.3 4.1 28 (47.5%) 27 (45.8%)
7.27 0.3 7 (70.0%) 31.2 4.04 5 (50.0%) 5 (50.0%)
20 (38.5%) 23 (44.2%) 9 (17.3%) 165.1 348.7
1 (11.1%) 5 (55.6%) 3 (33.3%) 621.6 516.9
22 (37.9%) 27 (46.6%) 9 (15.5%) 499.0 842.1
2 (28.6%) 4 (57.1%) 1 (14.3%) 657.9 675.9
<0.001
1.1 2.5 1.4 3.2 66.3 36.1 44.1 32.8
0.7 2.4 0.8 2.9 35.1 37.0 27.5 32.7
0.3 0.9 0.4 1.0 59.5 45.5 50.3 44.3
0.397 0.646 <0.001 <0.001
39.6 9.0 55.7 25.6 60.0 18.8 438.1 42.5
38.2 10.4 66.7 47.0 61.9 16.2 433.2 64.5
38.0 5.4 48.0 0.0 72.8 18.2 439.8 75.7
0.784 0.253 0.344 0.927
0.8 0.9 9.0 6.0
3.5 3.9 23.2 16.7
38.7 15.4 65.1 35.4 67.3 21.1 426.4 69.6
p-value
0.280 0.555 0.834 0.499 0.399 0.722
Data shown are mean SD or number (%) of patients as appropriate. yr, year; NTD, New Taiwan Dollar; IgE, immunoglobulin E; GPx, glutathione peroxidase; MPO, myeloperoxidase; 8-OHdG, 8-hydroxy-20 -deoxyguanosine; TAC, total anti-oxidant capacity.
Figure 1. The relationship between oxidative stress markers (GPx and MPO) with allergen sensitization. Comparisons of GPx activity between children with and without crab or shrimp sensitization (A). Correlations between GPx activity and crab- or shrimpspecific IgE levels (B). Comparisons of D. pteronyssinus- and D. farinae-specific IgE levels between children with low MPO levels in the first quartile and those with high MPO levels in the second to fourth quartile (C). Correlations between MPO levels and D. pteronyssinus-specific IgE levels as well as D. farinae-specific IgE levels (D). *p < 0.05.
(r Z 0.214, p Z 0.027) (Fig. 2B). A significant positive correlation was also seen between TAC levels and pre- and post-bronchodilator FEV1% predicted (p < 0.05) (Fig. 2C).
Furthermore, TAC levels had a significant positive correlation with pre-bronchodilator FEV1 (r Z 0.337, p Z 0.017) in girls, but not in boys.
Please cite this article as: Wei Choo CY et al., Oxidative stress is associated with atopic indices in relation to childhood rhinitis and asthma, Journal of Microbiology, Immunology and Infection, https://doi.org/10.1016/j.jmii.2020.01.009
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Oxidative stress and childhood allergies
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Figure 2. The relationship between oxidative stress markers (8-OHdG and TAC) and pulmonary function tests. Comparison and correlation between 8-OHdG levels and FeNO levels (A). Correlations between TAC levels and pre- and post-bronchodilator FVC % predicted (B). Correlations between TAC levels and pre- and post-bronchodilator FEV1% predicted (C). *p < 0.05.
Association of oxidative stress markers with atopic indices and atopic diseases Table 2 presents the logistic regression analysis to calculate the odds ratio of oxidative stress markers and their related atopic indices for risk of atopic diseases. There were no associations of all oxidative stress markers with the risk of atopic diseases. However, GPx-related crab sensitization (OR 3.03; 95% CI 1.006e8.614; p Z 0.038) and 8-OHdG related FeNO levels (OR 4.34; 95% CI 1.435e12.532; p Z 0.009) were significantly associated with an increased risk of allergic rhinitis. Both MPO related D. pteronyssinusand D. farinae-specific IgE levels were significantly associated with an increased risk of all atopic diseases. Furthermore, TAC-related pulmonary function tests including FVC% and FEV1% predicted were significantly associated with asthma (p < 0.01).
Discussion Oxidative stress has been widely implicated in a variety of human diseases and their causes. However, its role in the allergic responses relevant to atopic diseases remains unclear, especially in early childhood. This study provides a comprehensive overview of oxidative stress markers (GPx, MPO, 8-OHdG and TAC) with various atopic indices related to atopic diseases. Despite the fact that there is no association between oxidative stress and atopic diseases, a strong association of oxidative stress with allergic sensitization and pulmonary function suggests that oxidative
stress plays a role in the modulation of allergy relevant reactions for childhood atopic diseases. GPx is a selenium-dependent anti-oxidative enzyme that catalyses the reduction of hydrogen peroxides at the expense of glutathione (GSH).15,16 Selenium is an essential micronutrient for humans and can be obtained from dietary intake of fish and shellfish, including crab and shrimp.17,18 Children with food allergy appear to have lower blood concentrations of selenium, suggesting that food allergic reactions tend to have negative effects on the absorption of dietary selenium.19 In this study, we have demonstrated a significantly lower activity of GPx in children with sensitization to crab or shrimp. As shellfish is one of the major sources of selenium,18,20,21 it can be postulated that the low GPx activity may be due to the sensitization to crab or shrimp with potentially decreased selenium absorption. MPO is stored primarily in neutrophils and monocytes, where it is released in response to local inflammation.22 MPO plays an essential part in the innate immune system by catalyzing the production of HOCl from H2O2 to generate reactive oxygen species (ROS), hence participating in host antimicrobial defense.23,24 In our study, there was an inverse correlation between MPO levels and allergic sensitization to house dust mites. Recent studies have reported that house dust mites may act as carriers of IgE-reactive bacterial antigens, inducing the production of ROS leading to oxidative damage in the lungs.6,25 A low MPO level in children with high mite sensitization may be due to an increase in its consumption from processing ROS, which were derived from bacterial antigens carried by house dust mites.
Please cite this article as: Wei Choo CY et al., Oxidative stress is associated with atopic indices in relation to childhood rhinitis and asthma, Journal of Microbiology, Immunology and Infection, https://doi.org/10.1016/j.jmii.2020.01.009
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OR, odds ratio; CI, confidence interval; GPx, glutathione peroxidase; MPO, myeloperoxidase; 8-OHdG, 8-hydroxy-20 -deoxyguanosine; FeNO, fractional exhaled nitric oxide; TAC, total antioxidant capacity; FVC, forced vital capacity; FEV1, forced expiratory volume in the first second; % pred, percentage of predicted; pre-bd, pre-bronchodilator; post-bd, post-bronchodilator. *Adjusted p-values for sex, maternal atopy, passive smoking, and household income. All p-values < 0.05, which is in bold, are significant.
(0.916e1.091) (0.072e6.084) (0.315e10.786) (0.876e1.070) (1.003e1.045) (1.004e1.047) (0.974e1.110) (0.060e5.558) (0.969e1.012) (0.831e0.974) (0.902e1.046) (0.813e0.963) (0.897e1.040) 1.00 0.66 1.84 0.97 1.02 1.03 1.04 0.58 0.99 0.90 0.97 0.89 0.97
Adjusted OR (95% CI) p-value*
0.980 0.038 0.052 0.916 <0.001 <0.001 0.231 0.009 0.513 0.562 0.861 0.828 0.828 (0.969e1.033) (1.006e8.614) (0.990e8.021) (0.989e1.010) (1.018e1.050) (1.022e1.072) (0.964e1.009) (1.435e12.532) (0.996e1.008) (0.962e1.021) (0.966e1.029) (0.967e1.027) (0.971e1.035) 1.00 3.03 2.82 1.00 1.03 1.05 0.99 4.34 1.00 0.99 1.00 1.00 1.00
Adjusted OR (95% CI) p-value*
0.817 0.138 0.553 0.439 0.007 0.028 0.594 0.472 0.667 0.435 0.658 0.342 0.266 (0.953e1.064) (0.672e17.763) (0.295e9.784) (0.957e1.019) (1.009e1.055) (1.003e1.049) (0.938e1.037) (0.380e8.046) (0.989e1.017) (0.966e1.084) (0.952e1.080) (0.969e1.094) (0.973e1.105)
Adjusted OR (95% CI)
1.01 3.46 1.70 0.99 1.03 1.03 0.99 1.75 1.00 1.02 1.01 1.03 1.04 GPx, U/g Crab, kU/L Shrimp, kU/L MPO, ng/mL D. pteronyssinus D. farinae 8-OHdG, ng/mg FeNO, ppb TAC, mmol/L FVC % pred (pre-bd) FVC % pred (post-bd) FEV1% pred (pre-bd) FEV1% pred (post-bd)
Allergic rhinitis Eczema Atopic indices
Table 2
Relationships of oxidative stress markers and their related atopic indices with risk of atopic diseases at age 7 years.
Asthma
p-value*
C.Y. Wei Choo et al.
0.991 0.714 0.497 0.526 0.025 0.021 0.241 0.636 0.371 0.009 0.444 0.005 0.358
6
Urinary 8-OHdG is often used as an indicator of cellular DNA oxidative stress. ROS causes hydroxylation of guanine, which triggers DNA repair enzymes and excretion of 8-OHdG in urine.26,27 Our study observed a negative correlation between 8-OHdG and fractional exhaled nitric oxide, a biomarker of airway inflammation. Nitric oxide reacts with superoxide to form peroxynitrite, initiating cellular degenerative changes and inflammation.28 Thus, the decrease in nitric oxide leads to the accumulation of superoxide and hydrogen peroxide for DNA damage, as reflected from an increase in urinary 8-OHdG. TAC determination is an analyte commonly used to assess the free radical-antioxidant balance in biological systems. In our study, the level of TAC was positively correlated with FVC % predicted and FEV1% predicted which strongly associated with risk of asthma. This finding is consistent with previous studies showing that asthmatic patients with higher TAC levels tend to have an increase in pulmonary functions.29,30 TAC levels therefore provide an important link to pulmonary function, potentially using as a biomarker for monitoring therapeutic efficacy and prognosis in children with asthma. Despite the fact that some studies had been reported on the relationship between oxidative stress markers and atopic diseases, the results were inconsistent.3,4,31 Although oxidative stress markers were not associated with atopic diseases in this study, their related atopic indices including food and aeroallergen sensitization, FeNO, and lung function parameters were strongly related to atopic diseases as described in previous studies.6,7 Thus, oxidative stress markers may potentially play a role in the modulation of allergic responses contributing to atopic diseases. Furthermore, dietary antioxidant intake such as vitamins A, C and E, and b-carotene have linked to improved pulmonary function and decreased risk of asthma.32 Clinically, antioxidant supplements may serve as a complementary treatment for more effective therapeutic approach towards atopic diseases. Limitations of this study include a relatively small sample size of 132 children and a limited power to detect a statistically significant association of subanalyses. Subphenotypes of early-onset atopic diseases including transient wheeze, asthmatic, or eczema may underestimate the extent of atopic diseases. Potential confounders of sex, passive smoking, diet, and testing technique may influence the measurement of oxidative stress markers and pulmonary function parameters. However, a standardized measurement method has used to ensure more consistent results in this study. Most importantly, the strength of this study lies in its longitudinal follow-up in children from a birth cohort with accurate diagnostic evaluations for atopic diseases at outpatient clinics. A comprehensive survey of serial atopic indices related to atopic diseases with oxidative stress markers makes the results demonstrated here valid and potentially important. In conclusion, oxidative stress appears to be associated with atopic indices, but not with atopic diseases. A decrease in the activity of GPx and levels of MPO is correlated with an increase in allergen-specific IgE levels. Furthermore, a decrease in urinary 8-OHdG levels is correlated with an increase in FeNO levels. Moreover,
Please cite this article as: Wei Choo CY et al., Oxidative stress is associated with atopic indices in relation to childhood rhinitis and asthma, Journal of Microbiology, Immunology and Infection, https://doi.org/10.1016/j.jmii.2020.01.009
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Oxidative stress and childhood allergies decreased TAC levels are correlated with decreased pulmonary function tests. Although oxidative stress appears to have no associations with atopic diseases, their related atopic indices are strongly associated with increased risk of atopic diseases. These findings suggest that oxidative stress potentially plays a role in the modulation of allergic responses contributing to atopic diseases. However, more research should be carried out to clarify its role in the pathogenesis of these diseases.
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10. 11.
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Funding
13.
This study was supported by research grant of CMRPG3E1191-5 from the Chang Gung Medical Foundation, Taiwan.
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Declaration of Competing Interest
15. 16.
All the authors declare no conflicts of interest in relation to the present study.
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Acknowledgment
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We are extremely grateful to all the families who took part in this study, all pediatricians for their help in recruiting them and the whole PATCH team, which includes interviewers, nurses, computer and laboratory technicians and research assistants.
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References
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