Glutathione S-Transferase Genotype Protects against In Utero Tobacco-linked Lung Function Deficits

A meta-analysis of the effects of vitamin C supplementation for pregnant smokers on the pulmonary function of their offspring

BACKGROUND

At present, the need for vitamin C supplementation for pregnant smokers has not been fully studied. This study is aimed at investigating whether vitamin C supplementation for pregnant smoking women can improve the pulmonary function of their offspring.

METHODS

Four databases were searched from inception to April 1, 2023 for studies on the effect of vitamin C supplementation to pregnant smokers on the pulmonary function of their offspring. Meanwhile, the reference lists of relevant studies were manually searched. The risk of bias in the included studies was assessed using the Cochrane Collaboration tool, and the data was analyzed using STATA/SE 17.0.

RESULTS

Four randomized controlled trials (RCTs), all of high quality, were enrolled in this meta-analysis, including 787 pregnant women. The offspring of pregnant smokers who received vitamin C supplementation exhibited improved Forced Expiratory Flow between 25 and 75% (FEF25-75), FEF50, FEF75, and Forced Vital Capacity (FVC) compared to those who did not receive vitamin C supplementation. However, there was no statistically significant difference in Forced Expiratory Volume at 0.5 s (FEV0.5) and the ratio of FEV0.5 to FVC between the offspring of pregnant smokers who received vitamin C and the control group.

CONCLUSION

Vitamin C supplementation for smoking pregnant women may enhance the pulmonary function of their offspring, particularly in FEF25-75, FEF50, FEF75, and FVC. Nevertheless, there are no significant differences in FEV0.5 and the FEV0.5/FVC ratio. These findings suggest that vitamin C supplementation has potential benefits for specific pulmonary function. Further studies are needed to comprehensively assess the effects of vitamin C on pulmonary function in the context of maternal smoking during pregnancy.

Potential role of glutathione S‑transferase M1 gene polymorphism in kidney calcium oxalate stone formation

BACKGROUND

The purpose of this study was to look into the effects of glutathione S-transferase M1 (GSTM1) gene polymorphism on the formation of kidney calcium oxalate stones.

METHODS

A total of 159 patients with kidney calcium oxalate stones were included in this study as a case group. One hundred and three healthy individuals were included in the control group. The age, gender, and levels of calcium (Ca), uric acid (UA), creatinine (Cr), and urinary creatinine (Ucr) are tracked. Peripheral blood samples are used to perform a polymerase chain reaction to identify the glutathione S-transferase (GST) gene polymorphism (PCR). A commercial kit was used in this study to measure the levels of malondialdehyde (MDA), nitric oxide (NO), total antioxidant capacity (T-AOC), and 8-hydroxydeoxyguanosine (8-OHdG) in peripheral blood.

RESULTS

There was no difference in age or gender distribution between the case and control groups (P > 0.05). The Cr, Ucr, Ca, UA, 8-OHdG, MDA, NO, and T-AOC in the case group were significantly higher than those in the control group (P < 0.001). The Hardy-Weinberg genetic equilibrium test showed no difference between the case group (P = 0.23) and the control group (P = 0.09). In the case group, the 8-OHdG and NO in GSTM1 null genotype were significantly higher than those in GSTM1 genotype (P < 0.05), but there was no significant difference in MDA and T-AOC (P > 0.05). Multivariate regression analysis showed that the GSTM1 null genotype was positively correlated with 8-OHdG (P < 0.001) and NO (P < 0.001).

CONCLUSIONS

GSTM1 gene polymorphism might be a detecting risk factor for kidney calcium oxalate stone formation.

TRIAL REGISTRATION

ChiCTR2100051300.

The Role of Lung Function in Determining Which Children Develop Asthma

Longitudinal studies have demonstrated that altered indices of airway function, assessed shortly after birth, are a risk factor for the subsequent development of wheezing illnesses and asthma, and that these indices predict airway size and airway wall thickness in adult life. Pre- and postnatal factors that directly alter early airway function, such as extreme prematurity and cigarette smoke, may continue to affect airway function and, hence, the risks for wheeze and asthma. Early airway function and an associated asthma risk may also be indirectly influenced by immune system responses, respiratory viruses, the airway microbiome, genetics, and epigenetics, especially if they affect airway epithelial dysfunction. Few if any interventions, apart from smoking avoidance, have been proven to alter the risks of developing asthma, but vitamin C supplementation to pregnant smokers may help decrease the effects of in utero smoke on offspring lung function. We conclude that airway size and the factors influencing this play an important role in determining the risk for asthma across the lifetime. Progress in asthma prevention is long overdue and this may benefit from carefully designed interventions in well-phenotyped longitudinal birth cohorts with early airway function assessments monitored through to adulthood.

Maternal vitamin D status modifies the effects of early life tobacco exposure on child lung function

BACKGROUND

Prior studies suggest that vitamin D may modify the effects of environmental exposures; however, none have investigated gestational vitamin D and cumulative tobacco smoke exposure (TSE) throughout pregnancy and early life.

OBJECTIVES

This study investigated the effects of early life TSE on child lung function and the modulatory effects of gestational vitamin D on this association.

METHODS

The VDAART (Vitamin D Antenatal Asthma Reduction Trial) recruited nonsmoking pregnant women and followed the mother-child pairs to age 6 years. TSE was assessed with questionnaires and plasma cotinine measurements in the mothers (10-18 and 32-38 gestational weeks) and children (1, 3, and 6 years). Cumulative TSE was calculated from the repeated cotinine measurements. 25-hydroxyvitamin D (25[OH]D) levels were measured at 10-18 and 32-38 gestational weeks. Lung function was assessed at 6 years with spirometry and impulse oscillometry.

RESULTS

Of the 476 mother-child pairs, 205 (43%) had increased cotinine levels at ≥1 time point. Cumulative TSE was associated with decreased FEV1 (β = -0.043 L, P = .018) and increased respiratory resistance at 5 Hz (R5; β = 0.060 kPa/L/s, P = .002). This association persisted in subjects with insufficient (<30 ng/mL) 25(OH)D levels throughout pregnancy (β = 0.077 kPa/L/s, P = .016 for R5) but not among those with sufficient levels throughout pregnancy.

CONCLUSIONS

Cumulative TSE from pregnancy to childhood is associated with dose- and duration-dependent decreases in child lung function at 6 years even in the absence of reported maternal smoking. Gestational vitamin D may modulate this effect and have therapeutic potential for minimizing the adverse effect of TSE on lung throughout early life.

RANDOMIZED TRIAL

Maternal Vitamin D Supplementation to Prevent Childhood Asthma (VDAART); clinicaltrials.gov identifier: NCT00920621.

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.

Addressing Race in Pulmonary Function Testing by Aligning Intent and Evidence With Practice and Perception

The practice of using race or ethnicity in medicine to explain differences between individuals is being called into question because it may contribute to biased medical care and research that perpetuates health disparities and structural racism. A commonly cited example is the use of race or ethnicity in the interpretation of pulmonary function test (PFT) results, yet the perspectives of practicing pulmonologists and physiologists are missing from this discussion. This discussion has global relevance for increasingly multicultural communities in which the range of values that represent normal lung function is uncertain. We review the underlying sources of differences in lung function, including those that may be captured by race or ethnicity, and demonstrate how the current practice of PFT measurement and interpretation is imperfect in its ability to describe accurately the relationship between function and health outcomes. We summarize the arguments against using race-specific equations as well as address concerns about removing race from the interpretation of PFT results. Further, we outline knowledge gaps and critical questions that need to be answered to change the current approach of including race or ethnicity in PFT results interpretation thoughtfully. Finally, we propose changes in interpretation strategies and future research to reduce health disparities.

Exposure to environmental tobacco smoke during pregnancy and infancy increased the risk of upper respiratory tract infections in infants: A birth cohort study in Wuhan, China

We aimed to evaluate the association of the exposure to environmental tobacco smoke (ETS) during pregnancy and infancy with the risk of upper respiratory tract infections (URTI) in infants based on a Chinese birth cohort study. Among 4178 infants who constituted the final study population, 46.8% experienced URTI in their first year of life. The hazard ratios (HR) and 95% confidence intervals (CI) for the risk of URTI were assessed using Cox regression models. Compared with no ETS during pregnancy, continued ETS during pregnancy was independently associated with a higher risk of URTI (HR: 1.36, 95% CI: 1.13, 1.63) after adjustment for potential confounders and also associated with earlier occurrence of URTI (log-rank P = .002). The association remained consistent across the strata defined according to maternal age, number of siblings, sex, and breastfeeding. Exposure to ETS during infancy was associated with URTI only among infants who were breastfed for less than 12 months (P for interaction < 0.05).Furthermore, infants exposed to ETS during both pregnancy and infancy showed the highest HR of 1.46 (95% CI: 1.16, 1.85) for URTI. Efforts should be made to protect pregnant women and infants from the adverse effects of indoor and outdoor ETS.

The time window of pet ownership exposure modifies the relationship of Environmental Tobacco Smoke with lung function: A large population-based cohort study

There is a large body of evidence linking Environmental Tobacco Smoke (ETS) exposure with impaired lung function. However, it is not known whether exposure to pets modifies this relationship. To investigate if pet ownership changes the association between ETS exposure and lung function, a population-based sample of 7326 children, 7-14 years old, were randomly recruited from 24 districts in northeast China. Lung function including forced vital capacity (FVC), forced expiratory volume in 1 s (FEV₁), peak expiratory flow (PEF), and maximal mid-expiratory flow (MMEF) was measured by spirometry, while pet ownership time periods and ETS exposure were collected by questionnaire. Two-level regression analysis was done, with covariates controlled for. The results showed pet exposure in certain early lifetime windows modified the associations of ETS exposure on decreased lung function in children. Among children exposed to current ETS, those exposed to pets in utero had greater reductions in lung function (for instance: OR for reduced FVC (<85% predicted) = 10.86; 95% CI: 3.80-30.97) than those not exposed to pets in utero (OR = 2.32; 95% CI: 1.76-3.05) (p_interaction = 0.005). While, children exposed to current pet ownership reduced the lung function impairment induced by ETS exposure during the first 2 years of life and/or ETS exposure during pregnancy, especially for FVC impairment. For instance, OR (95%CI) for reduced FVC (<85% predicted) was 0.81 (0.56, 1.18) and 1.42 (1.15, 1.74), respectively, for children with or without current pet ownership exposed to ETS during the first 2 years of life (p_interaction = 0.010). Furthermore, pet type or number of pets did not significantly modify associations between ETS exposure and lung function. In conclusion, the timing of pet ownership modified associations between ETS exposure and lung function, pet ownership in utero and during the first 2 years of life significantly worsened the adverse impacts of passive smoking on lung function.

A Mitochondrial Specific Antioxidant Reverses Metabolic Dysfunction and Fatty Liver Induced by Maternal Cigarette Smoke in Mice

Maternal smoking leads to glucose and lipid metabolic disorders and hepatic damage in the offspring, potentially due to mitochondrial oxidative stress. Mitoquinone mesylate (MitoQ) is a mitochondrial targeted antioxidant with high bioavailability. This study aimed to examine the impact of maternal cigarette smoke exposure (SE) on offspring’s metabolic profile and hepatic damage, and whether maternal MitoQ supplementation during gestation can affect these changes. Female Balb/c mice (eight weeks) were either exposed to air or SE for six weeks prior to mating and throughout gestation and lactation. A subset of the SE dams were supplied with MitoQ in the drinking water (500 µmol/L) during gestation and lactation. Intraperitoneal glucose tolerance test was performed in the male offspring at 12 weeks and the livers and plasma were collected at 13 weeks. Maternal SE induced glucose intolerance, hepatic steatosis, mitochondrial oxidative stress and related damage in the adult offspring. Maternal MitoQ supplementation reduced hepatic mitochondrial oxidative stress and improved markers of mitophagy and mitochondrial biogenesis. This may restore hepatic mitochondrial health and was associated with an amelioration of glucose intolerance, hepatic steatosis and pathological changes induced by maternal SE. MitoQ supplementation may potentially prevent metabolic dysfunction and hepatic pathology induced by intrauterine SE.