Epigenetics of hyper-responsiveness to allergen challenge following intrauterine growth retardation rat

Decreased ubiquitin modifying enzyme A20 associated with hyper-responsiveness to ovalbumin challenge following intrauterine growth restriction

BACKGROUND

Intrauterine growth restriction (IUGR) is strongly correlated with an increased risk of asthma later in life. Farm dust protects mice from developing house dust mite-induced asthma, and loss of ubiquitin modifying enzyme A20 in lung epithelium would abolish this protective effect. However, the mechanisms of A20 in the development of asthma following IUGR remains unknown.

METHODS

An IUGR rat model induced by maternal nutrient restriction was used for investigating the role of A20 in the response characteristics of IUGR rats to ovalbumin (OVA) challenge. The ubiquitination of proteins and N6-methyladenosine (m6A) modifications were used to further assess the potential mechanism of A20.

RESULTS

IUGR can reduce the expression of A20 protein in lung tissue of newborn rats and continue until 10 weeks after birth. OVA challenging can increase the expression of A20 protein in lung tissue of IUGR rats, but its level was still significantly lower than the control OVA group. The differentially ubiquitinated proteins in lung tissues were also observed in IUGR and normal newborn rats. Furthermore, this ubiquitination phenomenon continued from the newborn to adulthood. In the detected RNA methylations, m6A abundance of the motif GGACA was the highest. The higher abundances of m6A modification of A20 mRNA from IUGR were negatively correlated with the trend of A20 protein levels.

CONCLUSION

These findings indicate A20 as a key regulator during the development of asthma following IUGR, providing further insight into the prevention of asthma induced by environmental factors.

Network exploration of gene signatures underlying low birth weight induced metabolic alterations

BACKGROUND

This study explored underlying gene signatures of low birth weight (LBW) by analyzing differentially expressed genes (DEGs) between LBW and normal birth weight (NBW) subjects.

METHODS

Subjects with different birth weight was collected from GEO database. P < .05 and | logFC | ≥ 1.0 were used for screening DEGs. David (2021 Update) was used to perform GO annotation and KEGG signaling pathway enrichment analysis. The protein-protein interaction network of DEGs was constructed using the STRING database, in which hub genes were mined through Cytoscape software.

RESULTS

A total of 326 DEGs were identified, including 287 up-regulated genes and 39 down-regulated genes. The GO biological processes enriched by DEGs mainly involved epidermal growth, keratinization and intermediate fibrous tissue. The DEGs were significantly enriched in intracellular insoluble membranes, desmosomes and extracellular space. Their molecular functions mainly focused on structural molecular activity, structural components of epidermis and structural components of cytoskeleton. PI3K/AKT signaling pathway and tight junction were highlighted as critical pathways enriched by DEGs. Ten hub genes which included KRT14, EGF, DSP, DSG1, KRT16, KRT6A, EPCAM, SPRR1B, PKP1, and PPL were identified from the constructed protein-protein interaction network.

CONCLUSION

A total of 326 DEGs and 10 hub genes were identified as candidates for metabolic disorders in LBW individuals. Our results indicated PI3K/AKT signaling pathway as an intrauterine adaptive mechanism for LBW individuals. We observed activated PI3K/AKT pathway in LBW individuals, which would promote growth and development at the early stage of life, but adversely introduce extra metabolic stress and thereby potentially induce metabolic disorders in adulthood.

Metabolomics of bronchoalveolar lavage in children with persistent wheezing

Background

Recent studies have demonstrated the important role of metabolomics in the pathogenesis of asthma. However, the role of lung metabolomics in childhood persistent wheezing (PW) or wheezing recurrence remains poorly understood.

Methods

In this prospective observational study, we performed a liquid chromatography/mass spectrometry-based metabolomic survey on bronchoalveolar lavage samples collected from 30 children with PW and 30 age-matched infants (control group). A 2-year follow-up study on these PW children was conducted.

Results

Children with PW showed a distinct characterization of respiratory metabolome compared with control group. Children with PW had higher abundances of choline, oleamide, nepetalactam, butyrylcarnitine, l-palmitoylcarnitine, palmitoylethanolamide, and various phosphatidylcholines. The glycerophospholipid metabolism pathway was the most relevant pathway involving in PW pathophysiologic process. Additionally, different gender, prematurity, and systemic corticoids use demonstrated a greater impact in airway metabolite compositions. Furthermore, for PW children with recurrence during the follow-up period, children who were born prematurely had an increased abundance of butyrylcarnitine relative to those who were carried to term.

Conclusions

This study suggests that the alterations of lung metabolites could be associated with the development of wheezing, and this early alteration could also be correlated with wheezing recurrence later in life.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12931-022-02087-6.

Intrauterine growth restriction neonates present with increased angiogenesis through the Notch1 signaling pathway

Intrauterine growth restriction (IUGR) is associated with increased perinatal mortality and morbidity, and plays an important role in the development of adult cardiovascular diseases. This study brings forward a hypothesis that Human umbilical vein endothelial cells (HUVECs) from IUGR newborns present dysfunctions and varying changes of signaling pathways as compared to the Control group. Similar pathways may also be present in pulmonary or systemic vasculatures. HUVECs were derived from newborns. There were three groups according to the different fetal origins: normal newborns (Control), IUGR from poor maternal nutrition (IUGR1), and pregnancy-induced hypertension (IUGR2). We found that IUGR-derived HUVECs showed a proliferative phenotype compared to those from normal subjects. Interestingly, two types IUGR could cause varying degrees of cellular dysfunction. Meanwhile, the Notch1 signaling pathway showed enhanced activation in the two IUGR-induced HUVECs, with subsequent activation of Akt or extracellular signal regulated protein kinases1/2 (ERK1/2). Pharmacological inhibition or gene silencing of Notch1 impeded the proliferative phenotype of IUGR-induced HUVECs and reduced the activation of ERK1/2 and AKT. In summary, elevated Notch1 levels might play a crucial role in IUGR-induced HUVECs disorders through the activation of ERK1/2 and AKT. These pathways could be potential therapeutic targets for prevention of the progression of IUGR associated diseases later in life.

Effect of electro-acupuncture at ST 36 on maternal food restriction-induced lung phenotype in rat offspring

Maternal food restriction (MFR) during pregnancy leads to pulmonary dysplasia in the newborn period and increases susceptibility to diseases, such as asthma and chronic lung disease, later in life. Previous studies have shown that maternal electro-acupuncture (EA) applied to "Zusanli" (ST 36) could prevent the abnormal expression of key lung developmental signaling pathways and improve the lung morphology and function in perinatal nicotine exposed offspring. There is a significant overlap in lung developmental signaling pathways affected by perinatal nicotine exposure and MFR during pregnancy; however, whether maternal EA at ST 36 also blocks the MFR-induced lung phenotype is unknown. Here, we examined the effects of EA applied to maternal ST 36 on lung morphology and function and the expression of key lung developmental signaling pathways, and the hypercorticoid state associated with MFR during pregnancy. These effects were compared with those of metyrapone, an intervention known to block MFR-induced offspring hypercorticoid state and the resultant pulmonary pathology. Like metyrapone, maternal EA at ST 36 blocked the MFR-induced changes in key developmental signaling pathways and protected the MFR-induced changes in lung morphology and function. These results offer a novel and safe, nonpharmacologic approach to prevent MFR-induced pulmonary dysplasia in offspring.

Follow-up study of airway microbiota in children with persistent wheezing

Background

Increasing evidence revealed that airway microbial dysbiosis was associated with increased risk of asthma, or persistent wheezing (PW). However, the role of lung microbiota in PW or wheezing recurrence remains poorly understood.

Methods

In this prospective observational study, we performed a longitudinal 16S rRNA-based microbiome survey on bronchoalveolar lavage (BAL) samples collected from 35 infants with PW and 28 age-matched infants (control group). A 2-year follow-up study on these PW patients was conducted. The compositions of lower airway microbiota were analyzed at the phylum and genus levels.

Results

Our study showed a clear difference in lower airway microbiota between PW children and the control group. Children with PW had a higher abundance of Elizabethkingia and Rothia, and lower abundance of Fusobacterium compared with the control group. At the end of the 2-year follow-up, 20 children with PW (57.1%) experienced at least one episode of wheezing, and 15 (42.9%) did not suffer from wheezing episodes. Furthermore, PW children with recurrence also had increased abundances of Elizabethkingia and Rothia relative to those who had no recurrence. Additionally, wheezing history, different gender, and caesarean section demonstrated a greater impact in airway microbiota compositions.

Conclusion

This study suggests that the alterations of lower airway microbiota could be strongly associated with the development of wheezing, and early airway microbial changes could also be associated with wheezing recurrence later in life.

Fetal Growth Restriction and Asthma: Is the Damage Done?

Trajectories of airway remodeling and functional impairment in asthma are consistent with the notion that airway pathology precedes or coincides with the onset of asthma symptoms and may be present at birth. An association between intrauterine growth restriction (IUGR) and asthma development has also been established, and there is value in understanding the underlying mechanism. This review considers airway pathophysiology as a consequence of IUGR that increases susceptibility to asthma.

Intrauterine Growth Restriction Promotes Postnatal Airway Hyperresponsiveness Independent of Allergic Disease

Introduction: Intrauterine growth restriction (IUGR) is associated with asthma. Murine models of IUGR have altered airway responsiveness in the absence of any inflammatory exposure. Given that a primary feature of asthma is airway inflammation, IUGR-affected individuals may develop more substantial respiratory impairment if subsequently exposed to an allergen. This study used a maternal hypoxia-induced mouse model of IUGR to determine the combined effects of IUGR and allergy on airway responsiveness.

Methods: Pregnant BALB/c mice were housed under hypoxic conditions (10.5% O₂) from gestational day (GD) 11-GD 17.5 (IUGR group; term = GD 21). Following hypoxic exposure, mice were returned to a normoxic environment (21% O₂). A second group of pregnant mice were housed under normoxic conditions throughout pregnancy (Control). All offspring were sensitized to ovalbumin (OVA) and assigned to one of four treatment groups: Control – normoxic and saline challenge; IUGR – hypoxic and saline challenge; Allergy – normoxic and OVA challenge; and IUGR + Allergy – hypoxic and OVA challenge. At 8 weeks of age, and 24 h post-aerosol challenge, mice were tracheostomised for methacholine challenge and assessment of lung mechanics by the forced oscillation technique, and lungs subsequently fixed for morphometry.

Results: IUGR offspring were lighter than Control at birth and in adulthood. Both Allergy and IUGR independently increased airway resistance after methacholine challenge. The IUGR group also exhibited an exaggerated increase in tissue damping and elastance after methacholine challenge compared with Control. However, there was no incremental effect on airway responsiveness in the combined IUGR + Allergy group. There was no impact of IUGR or Allergy on airway structure and no effect of sex on any outcome.

Conclusion: IUGR and aeroallergen independently increased bronchoconstrictor response, but when combined the pathophysiology was not worsened. Findings suggest that an association between IUGR and asthma is mediated by baseline airway responsiveness rather than susceptibility to allergen.

Genome‑wide analysis of DNA methylation and gene expression changes in an ovalbumin‑induced asthma mouse model

The aim of the present study was to establish an integrated network of DNA methylation and RNA expression in an ovalbumin (OVA)-induced asthma model, and to investigate the epigenetically-regulated genes involved in asthma development. Genome-wide CpG-DNA methylation profiling was conducted through the use of a methylated DNA immunoprecipitation microarray and RNA sequencing was performed using three lung samples from mice with OVA-induced asthma. A total of 35,401 differentially methylated regions (DMRs) were identified between mice with OVA-induced asthma and control mice. Of these, 3,060 were located in promoter regions and 370 of the genes containing these DMRs demonstrated an inverse correlation between methylation and gene expression. Kyoto Encyclopedia of Genes and Genomes pathway analysis identified that 368 genes were upregulated or downregulated in OVA-induced asthma samples, including genes involved in ‘chemokine signalling pathway’, ‘focal adhesion’, ‘leukocyte transendothelial migration’ and ‘vascular smooth muscle contraction signaling’ pathways. Integrated network analysis identified four hub genes, consisting of three upregulated genes [forkhead box O1 (FOXO1), SP1 transcription factor (SP1) and amyloid β precursor protein (APP)], and one downregulated gene [RUNX family transcription factor 1 (RUNX1)], all of which demonstrated an association between DNA methylation and gene expression. These genes were highly interconnected nodes in the Ingenuity Pathway Analysis module and were functionally significant. A total of four interconnected hub genes, FOXO1, RUNX1, SP1 and APP, were identified from the integrated DNA methylation and gene expression networks involved in asthma development. These results suggested that modulating these four genes could effectively control the development of asthma.

Identification of differentially methylated candidate genes and their biological significance in IUGR neonates by methylation EPIC array

Background: Intrauterine growth restriction (IUGR) is a pregnancy-associated disease manifested by decreased growth rate of fetus than the normal genetic growth potential. It is associated with increased susceptibility to metabolic diseases later in life. Although the mechanisms underlying the origin of metabolic diseases are poorly understood, DNA methylation is a crucial investigation for the identification of epigenetic changes.Objectives: To assess the degree of change of DNA methylation in IUGR neonates and compare with that of appropriate for gestational age (AGA) neonates and to explore the differentially methylated candidate genes and their biological significance.Methods: This cohort study was conducted in the Neonatology Department of JIPMER during the period of November 2017 to December 2018. Forty each of IUGR and gestation matched AGA neonates were recruited. Umbilical cord blood samples were collected at birth. DNA was separated from the blood samples; and, using 5-mC DNA ELISA method, the percentage of genomic DNA methylated in these neonates was established. Data were expressed as mean ± standard deviation. Methylation EPIC array was performed to identify the differentially methylated candidate genes. David analysis was used to find out the functional annotation chart by KEGG pathway.Results: Genomic DNA methylation varied significantly between IUGR and AGA neonates (IUGR: 3.12 ± 1.24; AGA: 4.40 ± 2.03; p value: <.01). A global shift toward hypomethylation was seen in IUGR compared with AGA, targeted to regulatory regions of the genome, and specifically promoters. Pathway analysis identified deregulation of pathways involved in metabolic diseases. Altered methylation of PTPRN2 & HLADQB1 genes leads to dysregulation of T-cells and reactive oxygen species (ROS). These changes may lead to complications later among these neonates subjected to IUGR.Conclusion: Our findings show significant changes in the methylation pattern of genes among IUGR and AGA babies. Steps for correcting the changes may help in reducing later complications among IUGR babies.

Early-life undernutrition reprograms CD4+ T-cell glycolysis and epigenetics to facilitate asthma

BACKGROUND

Exposure to early-life undernutrition is closely related to higher risks of adverse immunologic outcomes in adulthood. Although it has been suggested that asthma has its origins in early life, its underlying mechanisms remain largely unknown.

OBJECTIVE

We characterized the effects of early-life undernutrition on T lymphocytes, which play a pivotal role in immune diseases, and we investigated whether this contributes to susceptibility to asthma in adulthood.

METHODS

Pregnant mice were fed a protein restriction diet (PRD) to establish an early-life undernutrition model. Naive CD4⁺ T cells (CD4⁺CD62L^hiCD44^-) from offspring were used throughout the study. T_H2 differentiation was examined by using fluorescence-activated cell sorting and ELISA under T_H2-polarized conditions in vitro and through ovalbumin-induced experimental asthma in vivo. T-cell metabolism was measured with a Seahorse XF96 Analyzer. DNA methylation levels were measured by using bisulfite sequencing.

RESULTS

PRD CD4⁺ T cells displayed increased activation and proliferation and were prone to differentiate into T_H2 cells both in vitro and in vivo, leading to susceptibility to experimental asthma. Mechanistically, early-life undernutrition upregulated mechanistic target of rapamycin 1-dependent glycolysis and induced conserved noncoding DNA sequence 1 DNA hypomethylation in the T_H2 cytokine locus of CD4⁺ T cells. Glycolysis blockades undermined increased T_H2 skewing and alleviated experimental asthma in PRD mice.

CONCLUSION

Early-life undernutrition induced mechanistic target of rapamycin 1-dependent glycolysis upregulation and T_H2 cytokine locus hypomethylation in CD4⁺ T cells, resulting in increased T-cell activation, proliferation, and T_H2 skewing and further susceptibility to experimental asthma.

Relationship between birth weight or fetal growth rate and postnatal allergy: a systematic review protocol

REVIEW QUESTION/OBJECTIVE

The objective of this systematic review is to synthesize the best available evidence on the relationship between size at birth or fetal growth and postnatal allergy. Specifically, this review aims to assess evidence regarding relationships between absolute birth weight at term, birth weight corrected for gestational age, expressed as relative to population or customized growth data, or fetal growth measures and physician-diagnosed or parent- and self-reported postnatal clinical allergic disease (eczema/atopic dermatitis, hay fever/rhinitis, allergic asthma or anaphylaxis).The specific review question is: what is the association between the absolute birth weight at full-term or birth weight relative to population or customized data and corrected for gestational age or direct measures of fetal growth, and physician-diagnosed or parent- and self-reported clinical allergic disease (eczema/atopic dermatitis, hay fever/rhinitis, allergic asthma or anaphylaxis)?

Maternal Glucocorticoid Elevation and Associated Fetal Thymocyte Apoptosis are Involved in Immune Disorders of Prenatal Caffeine Exposed Offspring Mice

Our previous study showed that prenatal caffeine exposure (PCE) could induce intrauterine growth retardation (IUGR) and glucocorticoid elevation in the fetus. Researchers suggested that IUGR is a risk factor for T helper cell (Th)1/Th2 deviation. However, whether PCE can induce these immune disorders and the underlying mechanisms of that induction remain unknown. This study aimed to observe the effects of PCE on the Th1/Th2 balance in offspring and further explore the developmental origin mechanisms from the perspective of glucocorticoid overexposure-induced thymocyte apoptosis. An IUGR model was established by caffeine administration from gestational day (GD) 9 to GD 18, and the offspring were immunized on postnatal day (PND) 42. The results show that maternal glucocorticoid overexposure increased fetal thymocyte apoptosis by activating both the Fas-mediated and the Bim-regulated apoptotic pathways. After birth, accelerated thymocyte apoptosis and Th1 suppression were also found in the PCE offspring at PND 14 and PND 49. Moreover, the PCE offspring showed immune disorders after immunization, manifesting as increased IgG1/IgG2a ratio and IL-4 production in the serum. In conclusion, PCE could induce fetal overexposure to maternal glucocorticoids and increase thymocyte apoptosis, which could persist into postnatal life and be implicated in Th1 inhibition and further immune disorders.

Pre-birth origins of allergy and asthma

Allergy is a chronic disease that can develop as early as infancy, suggesting that early life factors are important in its aetiology. Variable associations between size at birth, a crude marker of the fetal environment, and allergy have been reported in humans and require comprehensive review. Associations between birth weight and allergy are however confounded in humans, and we and others have therefore begun exploring the effects of early life events on allergy in experimental models. In particular, we are using ovine models to investigate whether and how a restricted environment before birth protects against allergy, whether methyl donor availability contributes to allergic protection in IUGR, and why maternal asthma during pregnancy is associated with increased risks of allergic disease in children. We found that experimental intrauterine growth restriction (IUGR) in sheep reduced cutaneous responses to antigens in progeny, despite normal or elevated IgE responses. Furthermore, maternal methyl donor supplementation in late pregnancy partially reversed effects of experimental IUGR, consistent with the proposal that epigenetic pathways underlie some but not all effects of IUGR on allergic susceptibility. Ovine experimental allergic asthma with exacerbations reduces relative fetal size in late gestation, with some changes in immune populations in fetal thymus suggestive of increased activation. Maternal allergic asthma in mice also predisposes progeny to allergy development. In conclusion, these findings in experimental models provide direct evidence that a perturbed environment before birth alters immune system development and postnatal function, and provide opportunities to investigate underlying mechanisms and develop and evaluate interventions.

Epigenetic changes in peripheral leucocytes as biomarkers in intrauterine growth retardation rat

Epigenetics plays an important role in the fetal origins of adult disease. Intrauterine growth retardation (IUGR) can cause increased histone acetylation of the endothelin-1 (ET-1) gene from pulmonary vascular endothelial cells or the whole lung tissue and persist into later life, likely resulting in increased risk of pulmonary hypertension or asthma later in life. However, little is known regarding the correlation of epigenetic changes between specific tissue and peripheral leucocytes. In the present study, an IUGR rat model was established by maternal nutrient restriction. Peripheral blood leucocytes were isolated to detect the ET-1 expression level. Chromatin immunoprecipitation was used to analyze histone modification of the ET-1 gene promoter. The ET-1 protein expression of leucocytes from the 1-week IUGR group was similar to that from the 1-week control group. ET-1 protein expression of leucocytes from 10-week IUGR rats was obviously higher than that of the other groups (P<0.05). The levels of acetylated histone H3 in the ET-1 promoter of leucocytes from the 1-week IUGR rats were significantly higher than those from the age-matched control group (P=0.004). Furthermore, the trends continued ≤10 weeks after birth. In conclusion, epigenetic modifications of leucocytes can in part reflect the epigenetic changes of lung tissue in IUGR rats. Epigenetics of peripheral leucocytes may be used as a biomarker for predicting the risk of the development of disease, and may be used as a surrogate to investigate the subsequent development of pulmonary vascular disease or asthma.

Intrauterine growth restriction perturbs nucleosome depletion at a growth hormone-responsive element in the mouse IGF-1 gene

Intrauterine growth restriction (IUGR) is a common human pregnancy complication. IUGR offspring carry significant postnatal risk for early-onset metabolic syndrome, which is associated with persistent reduction in IGF-1 protein expression. We have previously shown that preadolescent IUGR male mice have decreased hepatic IGF-1 mRNA and circulating IGF-1 protein at postnatal day 21, the age when growth hormone (GH) normally upregulates hepatic IGF-1 expression. Here we studied nucleosome occupancy and CpG methylation at a putative growth hormone-responsive element in intron 2 (in2GHRE) of the hepatic IGF-1 gene in normal, sham-operated, and IUGR mice. Nucleosome occupancy and CpG methylation were determined in embryonic stem cells (ESCs) and in liver at postnatal days 14, 21, and 42. For CpG methylation, additional time points out to 2 yr were analyzed. We confirmed the putative mouse in2GHRE was GH-responsive, and in normal mice, a single nucleosome was displaced from the hepatic in2GHRE by postnatal day 21, which exposed two STAT5b DNA binding sites. Nucleosome displacement correlated with developmentally programmed CpG demethylation. Finally, IUGR significantly altered the nucleosome-depleted region (NDR) at the in2GHRE of IGF-1 on postnatal day 21, with either complete absence of the NDR or with a shifted NDR exposing only one of two STAT5b DNA binding sites. An NDR shift was also seen in offspring of sham-operated mothers. We conclude that prenatal insult such as IUGR or anesthesia/surgery could perturb the proper formation of a well-positioned NDR at the mouse hepatic IGF-1 in2GHRE necessary for transitioning to an open chromatin state.