Maternal body mass index before pregnancy is associated with increased bronchodilator dispensing in early childhood: A cross-sectional study

Maternal high-fat diet programs offspring airway hyperinnervation and hyperresponsiveness

The impact of diet-induced maternal obesity on offspring airway hyperresponsiveness was studied in a diversity outbred mouse model that mirrors human genetic diversity. Female mice were started on high-fat or regular diet 8 weeks before breeding and throughout pregnancy and lactation. After weaning, all offspring were fed a regular diet. By 12 weeks, body weight and fat were increased in offspring of high-fat diet-fed dams, which was accompanied by metabolic dysfunction and hyperinsulinemia. This was followed by increased epithelial sensory innervation and increased bronchoconstriction to inhaled 5-hydroxytryptamine at 16 weeks. Bronchoconstriction was nerve mediated and blocked by vagotomy or atropine. A high-fat diet before pregnancy exerted the most influence on offspring airway physiology. Maternal obesity induced metabolic dysfunction and hyperinsulinemia, resulting in hyperinnervation and subsequent increased reflex-mediated hyperresponsiveness in their offspring. This is relevant to our understanding of asthma inheritance, considering the genetic diversity of humans.

Prenatal Origins of Obstructive Airway Disease: Starting on the Wrong Trajectory?

From the results of well-performed population health studies, we now have excellent data demonstrating that deficits in adult lung function may be present early in life, possibly as a result of developmental disorders, incurring a lifelong risk of obstructive airway diseases such as asthma and chronic obstructive pulmonary disease. Suboptimal fetal development results in intrauterine growth restriction and low birth weight at term (an outcome distinct from preterm complications), which are associated with subsequent obstructive disease. Numerous prenatal exposures and disorders compromise fetal development and these are summarized herein. Various physiological, structural, and mechanical abnormalities may result from prenatal disruption, including changes to airway smooth muscle structure-function, goblet cell biology, airway stiffness, geometry of the bronchial tree, lung parenchymal structure and mechanics, respiratory skeletal muscle contraction, and pulmonary inflammation. The literature therefore supports the need for early life intervention to prevent or correct growth defects, which may include simple nutritional or antioxidant therapy. © 2024 American Physiological Society. Compr Physiol 14:5729-5762, 2024.

A Scoping Review of the Relationship Between Maternal BMI and Offspring Incidence of Respiratory Infection: Where Do We Go From Here?

Introduction

Pregnancy complications, including high maternal BMI, are associated with altered early development and child health outcomes. A growing body of work links the prenatal environment, specifically maternal BMI, with respiratory infections in offspring. In this rapid review, the authors review the literature supporting the hypothesis that high maternal BMI during pregnancy is associated with childhood respiratory infection incidence.

Methods

The authors employed systematic search criteria in known databases-EMBASE, EMCARE, MEDLINE, CINAHL, and PsychINFO-searching from inception to January 2023. Included were primary research studies that involved (1) human pregnancy, (2) pregravid or gestational overweight or obesity, and (3) childhood respiratory infection with or without hospitalization.

Results

Only 7 population-based cohort studies met the criteria, investigating maternal BMI as an exposure and childhood respiratory infection as an outcome (age 6 months to 18 years). Therefore, the authors conducted a qualitative analysis, and outcomes were reported. The authors found that >85% of the albeit few published studies support the hypothesis that maternal BMI may have independent and profound consequences on respiratory infection risk across childhood.

Discussion

This area of research needs large-scale, well-controlled studies to better understand the relationship between maternal BMI and childhood respiratory infection. Possible resources such as cohort catalogs and combined databases are discussed. These findings add to the growing evidence that early environmental factors influence lifelong respiratory health. By incorporating a life course approach to infectious disease risk, policy makers can put this research to work and target health vulnerabilities before they arise.

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.

Perinatal origins of chronic lung disease: mechanisms-prevention-therapy-sphingolipid metabolism and the genetic and perinatal origins of childhood asthma

Childhood asthma derives from complex host-environment interactions occurring in the perinatal and infant period, a critical time for lung development. Sphingolipids are bioactive molecules consistently implicated in the pathogenesis of childhood asthma. Genome wide association studies (GWAS) initially identified a link between alleles within the 17q21 asthma-susceptibility locus, childhood asthma, and overexpression of the ORMDL sphingolipid biosynthesis regulator 3 (ORMDL3), an inhibitor of de novo sphingolipid synthesis. Subsequent studies of pediatric asthma offer strong evidence that these asthma-risk alleles correlate with early-life aberrancies of sphingolipid homeostasis and asthma. Relationships between sphingolipid metabolism and asthma-related risk factors, including maternal obesity and respiratory viral infections, are currently under investigation. This review will summarize how these perinatal and early life exposures can synergize with 17q21 asthma risk alleles to exacerbate disruptions of sphingolipid homeostasis and drive asthma pathogenesis.

Evaluation of rescue oral glucocorticoid therapy during inpatient cystic fibrosis exacerbations

An acute pulmonary exacerbation (APE) in cystic fibrosis (CF) is characterized by increased pulmonary symptoms attributed to bacterial colonization, neutrophil recruitment, and inflammation. Antimicrobials, airway clearance, and nutrition are the mainstay of therapy. However, when patients fail to improve, corticosteroids have been added to therapy. We retrospectively examined the use of rescue steroids in a children's hospital from 2013 to 2017 during CF APE treatment following at least 1 week of inpatient therapy without expected clinical improvement. In total, 106 encounters of 53 unique patients, aged 6-20 years, who had FEV1 percent predicted (FEV1pp) data at baseline, admission, midpoint, and discharge, and had admission duration of at least 12 days were studied. Encounters treated with steroids had less improvement at midpoint percent change from admission in FEV1pp (4.9 ± 11.3) than nonsteroid group change in FEV1pp (20.1 ± 24.6; p < .001). Failure to improve as expected was the rationale for steroid use. At discharge, there was no difference in mean FEV1pp (p = .76). Delays in steroid therapy by waiting until the end of the second week increased the total length of stay (LOS). Propensity matching, comparing outcomes in patients without midpoint improvement in FEV1pp, was also evaluated. There was no difference in admission or discharge FEV1pp between groups. Equally, no difference in FEV1pp at follow-up visit or in time until the next APE was detected. Secondary analysis for associations including gender, genotype, fungal colonization, or inhaled antimicrobials was nonsignificant. These data suggest rescue use of corticosteroids during APE does not predictably impact important outcome measures during CF APE treatment.

Vitamin C to pregnant smokers persistently improves infant airway function to 12 months of age: a randomised trial

BACKGROUND

Vitamin C (500 mg·day-1) supplementation for pregnant smokers has been reported to increase newborn pulmonary function and infant forced expiratory flows (FEFs) at 3 months of age. Its effect on airway function through 12 months of age has not been reported.

OBJECTIVE

To assess whether vitamin C supplementation to pregnant smokers is associated with a sustained increased airway function in their infants through 12 months of age.

METHODS

This is a pre-specified secondary outcome of a randomised, double-blind, placebo-controlled trial that randomised 251 pregnant smokers between 13 and 23 weeks of gestation: 125 to 500 mg·day-1 vitamin C and 126 to placebo. Smoking cessation counselling was provided. FEFs performed at 3 and 12 months of age were analysed by repeated-measures analysis of covariance.

RESULTS

FEFs were performed in 222 infants at 3 months and 202 infants at 12 months of age. The infants allocated to vitamin C had significantly increased FEFs over the first year of life compared to those allocated to placebo. The overall increased flows were 40.2 mL·s-1 for at FEF75 (75% of forced vital capacity (FVC)) (adjusted 95% CI for difference 6.6-73.8; p=0.025); 58.3 mL·s-1 for FEF50 (10.9-105.8; p=0.0081); and 55.1 mL·s-1 for FEF25-75 (9.7-100.5; p=0.013).

CONCLUSIONS

In offspring of pregnant smokers randomised to vitamin C versus placebo, vitamin C during pregnancy was associated with a small but significantly increased airway function at 3 and 12 months of age, suggesting a potential shift to a higher airway function trajectory curve. Continued follow-up is underway.

Maternal high-fat diet alters lung development and function in the offspring

The effects of maternal obesity on lung development have been recognized, and speculation is that these diseases are not simply because of accelerated pulmonary decline with aging but with a failure to achieve optimal lung development during early life. These studies tested the hypothesis that maternal obesity alters signaling pathways during the course of lung development that may affect life-long pulmonary health. Adult female mice were fed 60% fat [high-fat diet (HFD)] or 10% fat [control diet (CD)] for 8 wk before mating and through weaning. Pup lung tissues were collected at postnatal days (PN) 7, 21, and 90 (after receiving HFD or CD as adults). At PN7, body weights from HFD were greater than CD but lung weight-to-body weight ratios were lower. In lung tissues, NFκB-mediated inflammation was greater in HFD pups at PN21 and phospho-/total STAT3, phospho-/total VEGF receptor 2, and total AKT protein levels were lower with maternal HFD and protein tyrosine phosphatase B1 levels were increased. Decreased platelet endothelial cell adhesion molecule levels were observed at PN21 and at PN90 in the pups exposed to maternal HFD. Morphometry indicated that the pups exposed to maternal or adult HFD had fewer alveoli, and the effect was additive. Decreases in pulmonary resistance, elastance, and compliance were observed because of adult HFD diet and decreases in airway resistance and increases in inspiratory capacity because of maternal HFD. In conclusion, maternal HFD disrupts signaling pathways in the early developing lung and may contribute to deficiencies in lung function and increased susceptibility in adults.

Maternal high-fat diet in mice leads to innate airway hyperresponsiveness in the adult offspring

Maternal obesity prior to and during pregnancy has been associated with an increased incidence of childhood asthma. As diets rich in saturated fat are linked to obesity and inflammation, we created a murine model to investigate the effect of maternal high-fat diet (HFD) on adult offspring airway hyperreactivity (AHR), a cardinal feature of asthma. Balb/cByJ dams were fed a HFD (60% fat Calories) or normal-fat diet (NFD) (10% fat Calories) from 8 weeks prior to first breeding through their pregnancies. Pups were weaned to either a HFD or NFD (at 4 weeks of age). AHR was measured in the 10-week-old offspring following inhaled methacholine challenge by end-inflation technique. Bronchial alveolar lavage fluid (BALF) was analyzed for cell count, total protein, and IL-6. Offspring of HFD dams weaned to NFD had increased AHR compared to offspring of NFD dams weaned to NFD Offspring of HFD dams that remained on HFDs had increased AHR compared to offspring of NFD dams weaned to HFDs. Offspring of HFD dams had higher BALF cell counts, higher neutrophil percentage, greater total protein, and IL-6 in the BALF These results demonstrate that a maternal diet high in saturated fat through pregnancy and lactation plays a key role in programming adult offspring AHR.