Influence of age on the development of immunological lung response in intrauterine undernourishment

Intrauterine food restriction impairs the lipogenesis process in the mesenteric adipocytes from low-birth-weight rats into adulthood

Background

Intrauterine food restriction (IFR) during pregnancy is associated with low birth weight (LBW) and obesity in adulthood. It is known that white adipose tissue (WAT) plays critical metabolic and endocrine functions; however, this tissue's behavior before weight gain and obesity into adulthood is poorly studied. Thus, we evaluated the repercussions of IFR on the lipogenesis and lipolysis processes in the offspring and described the effects on WAT inflammatory cytokine production and secretion.

Methods

We induced IFR by providing gestating rats with 50% of the necessary chow daily amount during all gestational periods. After birth, we monitored the offspring for 12 weeks. The capacity of isolated fat cells from mesenteric white adipose tissue (meWAT) to perform lipogenesis (14C-labeled glucose incorporation into lipids) and lipolysis (with or without isoproterenol) was assessed. The expression levels of genes linked to these processes were measured by real-time PCR. In parallel, Multiplex assays were conducted to analyze pro-inflammatory markers, such as IL-1, IL-6, and TNF-α, in the meWAT.

Results

Twelve-week-old LBW rats presented elevated serum triacylglycerol (TAG) content and attenuated lipogenesis and lipolysis compared to control animals. Inflammatory cytokine levels were increased in the meWAT of LBW rats, evidenced by augmented secretion by adipocytes and upregulated gene and protein expression by the tissue. However, there were no significant alterations in the serum cytokines content from the LBW group. Additionally, liver weight, TAG content in the hepatocytes and serum glucocorticoid levels were increased in the LBW group.

Conclusion

The results demonstrate that IFR throughout pregnancy yields LBW offspring characterized by inhibited lipogenesis and lipolysis and reduced meWAT lipid storage at 12 weeks. The increased serum TAG content may contribute to the augmented synthesis and secretion of pro-inflammatory markers detected in the LBW group.

Intrauterine growth restriction leads to a high-corticosterone producing offspring: An implication for pulmonary infection susceptibility

AIMS

Although intrauterine growth restriction (IUGR) impairs immune system homeostasis and lung development, its relationship with the susceptibility to pulmonary infections remains unclear. Thus, this study aimed to investigate the impact of IUGR on acute lung inflammatory response induced by bacterial stimulus.

MATERIALS AND METHODS

Pregnant female Wistar rats were subjected to 50% caloric-protein food restriction during gestation. To mimic bacterial lung infection, adult male offspring (12 weeks old) were challenged with a single lipopolysaccharide (LPS) intranasal instillation, and 6 h later, we assessed the acute inflammatory response. Normal birth weight (NBW) animals represent the control group.

KEY FINDINGS

LPS instillation increased the protein levels in the airways of both the NBW and low birth weight (LBW) groups, indicating vascular leakage. LBW animals exhibited a lower number of neutrophils, reduced production of interleukin-6 and macrophage-inflammatory protein-2 and decreased upregulation of intercellular adhesion molecule-1 gene expression in lung tissues. Further analysis revealed that the LBW group produced lower levels of prostaglandin-E₂ and failed to secrete leukotriene-B₄ upon LPS stimulation, which correlated with impaired cyclooxygenase-2 and 5-lipoxygenase expression. These results were probably associated with their inability to upregulate the expression of Toll-like receptor-4 and downstream signaling proteins, such as nuclear factor kappa-B, in the lungs. The LBW group also exhibited abnormal airway thickening and high corticosterone levels under basal conditions.

SIGNIFICANCE

This study suggests that IUGR-induced foetal programming in LBW offspring threatens HPA axis physiology and corticosterone biodisponibility, and impairs the innate response to bacterial antigens, increasing future susceptibility to pulmonary infection.

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.

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

BACKGROUND

Individual susceptibility to allergic diseases is developmentally programmed by early-life exposures. Evidence from preclinical studies suggests that intrauterine growth restriction is protective against later inflammatory responses to allergens.

OBJECTIVE

We sought to evaluate whether prenatal growth affects susceptibility to allergy in human subjects.

METHODS

We systematically searched for relevant studies in 11 databases, including Web of Science, ProQuest, EMBASE, and PubMed. We included only studies that corrected for gestational age or were restricted to full-term infants to separate effects of fetal growth from those of prematurity.

RESULTS

The 42 eligible studies included prospective and retrospective cohort, cross-sectional, and case-control studies. Only 2 studies reported allergic asthma. A birth weight increase of 1 kg was associated with a 44% greater risk of food allergy in children (odds ratio [OR], 1.44; 95% CI, 1.04-1.99; P = .001), a 17% greater risk of ever allergic dermatitis in children (OR, 1.17; 95% CI, 1.04-1.32; P = .008), and a 34% greater risk of ever or current allergic dermatitis in infants up to 2 years of age (OR, 1.34; 95% CI, 1.08-1.68; P = .009). Risks of allergic rhinitis were not associated with birth weight.

CONCLUSIONS

The results of these meta-analyses suggest that intrauterine growth restriction protects against allergic diseases in human subjects consistent with preclinical evidence but that effects might differ between allergic diseases. The strongest evidence is available for infancy and early childhood, and additional studies in older children and adults are needed to determine whether the effects of prenatal growth on each allergic disease persist or differ between those with severe and mild phenotypes.

Intrauterine Malnutrition Reduced Long Leptin Receptor Isoform Expression and Proinflammatory Cytokine Production in Male Rat Pulmonary Endothelial Cells Stimulated by Lipopolysaccharide

Background/Aims

We have previously shown that low birth weight (LBW) rats exposed to intrauterine malnutrition have an impaired lung inflammatory response and reduced levels of inflammatory mediators; however, circulating leptin levels were not increased. We evaluated long leptin receptor isoform (ObRb) expression in lung endothelial cells from low birth weight rats and examined its role in the production of lipid mediators and cytokines.

Methods

Lung endothelial cells were obtained from normal birth weight (NBW) rats or LBW rats subjected to intrauterine malnutrition. These cells were stimulated with leptin (10 ng/mL), LPS (lipopolysaccharide, 1 μg/mL), or leptin plus LPS. Six hours after stimulation, the production of inflammatory mediators (PGE₂, LTB₄, IL-1β, and IL-6) was evaluated using commercial ELISA kits, and Western blotting was performed to investigate p38MAPK, NF-κB, and ObRb expression.

Results

Leptin increased IL-1β levels in only cells from the NBW group, whereas LPS increased PGE₂ and LTB₄ levels in cells from both groups; leptin addition potentiated lipid mediator production induced by LPS in the NBW group. LPS enhanced the production of IL-1β and IL-6 in only endothelial cells from NBW rats. Leptin receptor expression was decreased (63%) in endothelial cells from LBW rats. None of the stimuli increased NF-κB or p38 signaling pathway expression in cells from LBW rats.

Conclusion

These results suggest that intrauterine malnutrition compromises leptin receptor expression and cytokine production in pulmonary endothelial cells stimulated by LPS; these effects seem to involve the NF-κB and p38MAPK signaling pathways.

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)?

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.

Intrauterine Growth Restriction Programs the Hypothalamus of Adult Male Rats: Integrated Analysis of Proteomic and Metabolomic Data

Programming of hypothalamic functions regulating energy homeostasis may play a role in intrauterine growth restriction (IUGR)-induced adulthood obesity. The present study investigated the effects of IUGR on the hypothalamus proteome and metabolome of adult rats submitted to 50% protein-energy restriction throughout pregnancy. Proteomic and metabolomic analyzes were performed by data independent acquisition mass spectrometry and multiple reaction monitoring, respectively. At age 4 months, the restricted rats showed elevated adiposity, increased leptin and signs of insulin resistance. 1356 proteins were identified and 348 quantified while 127 metabolites were quantified. The restricted hypothalamus showed down-regulation of 36 proteins and 5 metabolites and up-regulation of 21 proteins and 9 metabolites. Integrated pathway analysis of the proteomics and metabolomics data indicated impairment of hypothalamic glucose metabolism, increased flux through the hexosamine pathway, deregulation of TCA cycle and the respiratory chain, and alterations in glutathione metabolism. The data suggest IUGR modulation of energy metabolism and redox homeostasis in the hypothalamus of male adult rats. The present results indicated deleterious consequences of IUGR on hypothalamic pathways involved in pivotal physiological functions. These results provide guidance for future mechanistic studies assessing the role of intrauterine malnutrition in the development of metabolic diseases later in life.

Protective effect of soybean oil- or fish oil-rich diets on allergic airway inflammation

BACKGROUND

The increased prevalence of asthma and allergic diseases in westernized societies has been associated with increased intake of diets rich in n-6 fatty acids (FAs) and poor in n-3 FAs. This study aimed to analyze the prophylactic effects of treatment with a soybean oil-rich diet (rich in n-6) or fish oil (rich in n-3) in an allergic airway inflammation model on lung inflammation score, leukocyte migration, T-helper cell (Th)-2 (interleukin [IL]-4, IL-5) and Th1 (interferon [IFN]-γ, tumor necrosis factor-α) cytokines, lipoxin A4, nitric oxide, bradykinin, and corticosterone levels in bronchoalveolar lavage (BAL) or lungs.

METHODS

Male Wistar rats fed with soybean oil- or fish oil-rich diet or standard rat chow were sensitized twice with ovalbumin-alumen and challenged twice with ovalbumin aerosol. The BAL and lungs were examined 24 hours later.

RESULTS

Both diets, rich in n-6 or n-3 FAs, impaired the allergic lung inflammation and reduced leukocyte migration, eosinophil and neutrophil percentages, and IL-4/IL-5/bradykinin levels in BAL and/or lungs, as well as increased the nitric oxide levels in BAL. The soybean oil-rich diet additionally increased the levels of lipoxin A4 and corticosterone in the lungs.

CONCLUSION

Data presented demonstrated that the n-6 FA-rich diet had protective effect upon allergic airway inflammation and was as anti-inflammatory as the n-3 FA-rich diet, although through different mechanisms, suggesting that both diets could be considered as complementary therapy or a prophylactic alternative for allergic airway inflammation.

In utero Programming of Allergic Susceptibility

BACKGROUND

Around 30-40% of the world's population will experience allergy, the most common and earliest-onset noncommunicable disease. With a steady rise in the incidence of allergic disease over recent decades, up to 18% of children will suffer a respiratory, food or skin allergy before their 18th birthday. There is compelling evidence that the risk of developing allergy is influenced by early life events and particularly in utero exposures.

METHODS

A comprehensive literature review was undertaken which outlines prenatal risk factors and potential mechanisms underlying the development of allergy in childhood.

RESULTS

Exposures including maternal cigarette smoking, preterm birth and Caesarean delivery are implicated in predisposing infants to the later development of allergy. In contrast, restricted growth in utero, a healthy maternal diet and a larger family size are protective, but the mechanisms here are unclear and require further investigation.

CONCLUSION

To ameliorate the allergy pandemic in young children, we must define prenatal mechanisms that alter the programming of the fetal immune system and also identify specific targets for antenatal interventions.