Cord blood immune status: predicting health or allergy?

Egg-sensitised infants have elevated CD4+ effector memory T regulatory cells from birth

BACKGROUND

IgE-mediated sensitisation to egg is common in infants. In some cases, the processes leading to egg sensitisation are established in early life, even before introduction to solid foods. The underlying mechanisms remain poorly understood.

METHODS

We performed detailed immune cell phenotyping of peripheral blood mononuclear cells and determined in vitro cytokine responses following allergen specific and non-specific immune stimulation. To determine if unique immune profiles were linked to early-life egg sensitisation, we compared 92 infants at 4-6 months of age, with (EggCAP+, n = 41) and without (EggCAP-, n = 51) early egg sensitisation. Additionally, 47 cord blood samples were analysed. For a subset of participants (n = 39), matching cord blood mononuclear cells were assessed by flow cytometry to establish the impact of IgE sensitisation on immune developmental trajectories.

RESULTS

EggCAP+ infants were found to exhibit a unique immune phenotype characterised by increased levels of circulating CD4+ T regulatory cells (Treg), CD4+ effector memory (EM) Treg and increased expression of the IgE receptor, FcεR1, on basophils. The increased CD4+ EM Treg profiles were already present in cord blood samples from EggCAP+ infants. A general Th2-skewing of the immune system was observed based on increased IL-13 production following phytohemagglutinin stimulation and by comparing immune developmental trajectories, EggCAP+ infants displayed an expansion of basophils and reduced levels of CD4- T cells compared to EggCAP- infants.

CONCLUSIONS

Immunological profiles associated with egg sensitisation are detectable in infant circulation at 4-6 months of age and at birth. Understanding the immune mechanisms underlying early-life sensitisation could provide important insights for future food allergy prevention strategies.

Cord blood group 2 innate lymphoid cells are associated with lung function at 6 weeks of age

Objective

Offspring born to mothers with asthma in pregnancy are known to have lower lung function which tracks with age. Human group 2 innate lymphoid cells (ILC2) accumulate in foetal lungs, at 10‐fold higher levels compared to adult lungs. However, there are no data on foetal ILC2 numbers and the association with respiratory health outcomes such as lung function in early life. We aimed to investigate cord blood immune cell populations from babies born to mothers with asthma in pregnancy.

Methods

Cord blood from babies born to asthmatic mothers was collected, and cells were stained in whole cord blood. Analyses were done using traditional gating approaches and computational methodologies (t‐distributed stochastic neighbour embedding and PhenoGraph algorithms). At 6 weeks of age, the time to peak tidal expiratory flow as a percentage of total expiratory flow time (tPTEF/tE%) was determined as well as Lung Clearance Index (LCI), during quiet natural sleep.

Results

Of 110 eligible infants (March 2017 to November 2019), 91 were successfully immunophenotyped (82.7%). Lung function was attempted in 61 infants (67.0%), and 43 of those infants (70.5% of attempted) had technically acceptable tPTEF/tE% measurements. Thirty‐four infants (55.7% of attempted) had acceptable LCI measurements. Foetal ILC2 numbers with increased expression of chemoattractant receptor‐homologous molecule (CRTh2), characterised by two distinct analysis methodologies, were associated with poorer infant lung function at 6 weeks of age.”

Conclusion

Foetal immune responses may be a surrogate variable for or directly influence lung function outcomes in early life.

Environmental Air Pollutants Inhaled during Pregnancy Are Associated with Altered Cord Blood Immune Cell Profiles

Air pollution exposure during pregnancy may be a risk factor for altered immune maturation in the offspring. We investigated the association between ambient air pollutants during pregnancy and cell populations in cord blood from babies born to mothers with asthma enrolled in the Breathing for Life Trial. For each patient (n = 91), daily mean ambient air pollutant levels were extracted during their entire pregnancy for sulfur dioxide (SO₂), nitric oxide, nitrogen dioxide, carbon monoxide, ozone, particulate matter <10 μm (PM₁₀) or <2.5 μm (PM_2.5), humidity, and temperature. Ninety-one cord blood samples were collected, stained, and assessed using fluorescence-activated cell sorting (FACS). Principal Component (PC) analyses of both air pollutants and cell types with linear regression were employed to define associations. Considering risk factors and correlations between PCs, only one PC from air pollutants and two from cell types were statistically significant. PCs from air pollutants were characterized by higher PM_2.5 and lower SO₂ levels. PCs from cell types were characterized by high numbers of CD8 T cells, low numbers of CD4 T cells, and by high numbers of plasmacytoid dendritic cells (pDC) and low numbers of myeloid DCs (mDCs). PM_2.5 levels during pregnancy were significantly associated with high numbers of pDCs (p = 0.006), and SO₂ with high numbers of CD8 T cells (p = 0.002) and low numbers of CD4 T cells (p = 0.011) and mDCs (p = 4.43 × 10⁻⁶) in cord blood. These data suggest that ambient SO₂ and PM_2.5 exposure are associated with shifts in cord blood cell types that are known to play significant roles in inflammatory respiratory disease in childhood.

The LINA cohort: Cord blood eosinophil/basophil progenitors predict respiratory outcomes in early infancy

RATIONALE

Cord blood eosinophil/basophil progenitor cells (Eo/B) of high risk infants have been shown to predict respiratory illnesses in infancy. Here we investigated this association in a population-based cohort. Furthermore, we analysed whether newborns Th1/Th2 balance and prenatal environmental exposure impact Eo/B recruitment.

METHODS

In a sub-cohort of the LINA study cord blood mononuclear cells were used for methylcellulose assays to assess Eo/B differentiation. Questionnaires were recorded during pregnancy and annually thereafter. Volatile organic compounds were measured during pregnancy and cord blood cytokines after ex vivo stimulation.

RESULTS

Cord blood IL-4 and IL-13 positively correlated with Eo/B. Tobacco smoke related benzene was also positively associated with Eo/B. Enhanced Eo/B numbers increased the risk for wheezing within the first 24 months.

CONCLUSIONS

The association between cord blood Eo/B and respiratory illnesses is not restricted to high-risk children. Prenatal environmental exposure and a Th2 milieu at birth contribute to Eo/B recruitment.

STAT6 polymorphisms are associated with neonatal regulatory T cells and cytokines and atopic diseases at 3 years

BACKGROUND

The transcription factor STAT6 is crucial for activation of the interleukin (IL)-4/IL-13 pathway and has been linked to regulatory T cells (Tregs). Associations of STAT6 polymorphisms with IgE levels were described; however, their impact on neonatal immune responses and early disease development is unknown.

METHODS

STAT6 polymorphisms were genotyped in cord blood mononuclear cells by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS). Gene expression was assessed by real-time polymerase chain reaction (PCR) and cytokines by Multiplex. At age 3 years, atopic diseases were assessed by questionnaires.

RESULTS

STAT6 rs324011 but not rs1059513 polymorphism was associated with significant or borderline significant decreased mRNA expression of Treg-associated genes (FOXP3, GITR, LAG3). Heterozygotes and minor allele homozygotes of rs324011 had low levels of tumor necrosis factor alpha (TNF-α) and increased interferon gamma (IFN-γ) (P ≤ 0.04), while heterozygotes and minor allele homozygotes of rs1059513 had increased TNF-α and Granulocyte-macrophage colony-stimulating factor (GM-CSF) (P ≤ 0.05). In minor allele homozygotes of rs324011, expression of Treg-associated genes was strongly inverse correlated with IFN-γ (unstimulated, r = -0.7, P = 0.111; LpA stimulation, r = -0.8, P = 0.011), but not in heterozygotes or major allele homozygotes. Heterozygotes and minor allele homozygotes of rs324011 presented a lower risk of atopic dermatitis and obstructive bronchitis until age 3 years.

CONCLUSIONS

Two STAT6 polymorphisms were associated with altered immune responses already at birth. STAT6 rs324011 was associated with lower neonatal Treg and increased Th1 response. Those neonates had a lower risk of atopic dermatitis and obstructive bronchitis until 3 years. Our data suggest a role for STAT6 polymorphisms in early immune regulation and implications on early atopic disease development.

Association between prenatal exposure to cadmium and atopic dermatitis in infancy

Our objective was to evaluate the relationship between intrauterine exposure to cadmium and the presence of atopic dermatitis in infants 6 months of age, adjusted for covariates including exposure to other heavy metals. The present research is a component of the Mothers' and Children's Environmental Health (MOCEH) study, a multi-center birth cohort project conducted in Korea. Study subjects were restricted to pregnant women in whom cadmium and lead levels were measured at delivery and whose infants were assessed for the presence of atopic disease at 6 months of age. The odds ratio (OR) for the presence of atopic dermatitis in 6-month-old infants whose cord blood had elevated cadmium levels, after adjustment for other covariates, was 2.350 (95% CI, 1.126-4.906). The OR for the presence of atopic dermatitis in infants whose cord blood had elevated lead levels was not significant. In the present study, the cord blood cadmium level was significantly associated with the presence of atopic dermatitis in 6-month-old infants; this was not true of the cord blood lead level. To the best of our knowledge, this is the first prospective study to show a relationship between prenatal exposure to cadmium and atopic dermatitis in infancy.