Effects of nongenetic factors on immune cell dynamics in early childhood: The Generation R Study

Cross-tissue, age-specific flow cytometry reference for immune cells in airway and blood of children

BACKGROUND

Respiratory diseases are a common cause of morbidity and hospitalization for children. Despite this, treatment options are limited and are often ineffective. The development of curative or disease-modifying treatments for children relies on a better understanding of underlying immunity in the early airway.

OBJECTIVE

To establish a flow cytometry dataset for immune cells in the pediatric airway, we analyzed 180 samples from 68 children aged between 1 and 15 years. This included 5 tissues of the upper (nasal brushings, palatine tonsils, adenotonsil) and lower (bronchial brushings, bronchoalveolar lavage) airway, as well as whole blood for paired analysis of local and systemic immune response.

METHODS

Nasal, bronchial, and alveolar samples were analyzed using a 17-plex antibody panel that captures cells of immune and epithelial lineage, while tonsil, adenoid, and blood samples were analyzed using a 31-plex antibody panel that extensively phenotypes mononuclear immune cells. All protocols, panels, and data are openly available to facilitate implementation in pediatric clinical laboratories.

RESULTS

We provide age-specific airway cell data for infancy (0-2 years), preschool (3-5 years), childhood (6-10 years) and adolescence (11-15 years) for 37 cell populations. We show tissue-specific maturation of the airway immune system across childhood, further highlighting the importance of developing age-specific references of the pediatric airway. Intraindividual, cross-tissue analysis of paired samples revealed marked correlation in immune cell proportions between paired nasal-bronchial samples, paired tonsil-adenoid samples, and paired adenoid-blood samples, which may have implications for clinical testing.

CONCLUSION

Our study advances knowledge of airway immunity from infancy through to adolescence and provides an openly available control dataset to aid in interpretation of clinical findings in samples obtained from children with respiratory diseases.

Bone Marrow-Suppressive Treatment in Children Is Associated with Diminished IFN-γ Response from T Cells upon Polyclonal and Varicella Zoster Virus Peptide Stimulation

Severe haematological diseases and lymphoid malignancies require bone marrow (BM)-suppressive treatments. Knowledge regarding the impact of BM-suppressive treatments on children's memory T cells is very limited. Memory T cells play a crucial role in defending against herpesviruses, which is particularly relevant in paediatric cancer care. We studied 53 children in total; 34 with cancer and 2 with severe haematological disorders, with some receiving BM-suppressive treatment with or without allogeneic-haematopoietic stem cell transplantation (allo-HSCT), alongside 17 healthy controls. We focused on peripheral blood proportions of memory T-cell subsets using flow cytometry and analysed cytokine-secreting T cells with a four-parameter FluoroSpot assay in response to T-cell mitogen and varicella zoster virus (VZV) peptides. Patients on BM-suppressive treatment showed increased clusters of differentiation (CD)4+ and CD8+ effector memory (TEM)/terminally differentiated effector (TEFF) T cells compared to the healthy controls. They also exhibited, amongst other things, when compared to the healthy controls, a reduced total number of cytokine-secreting cells, by means of interferon (IFN)-γ, interleukin (IL)-17A, IL-10, and IL-22, following mitogen activation. A diminished IFN-γ response among the children with BM-suppressive treatment was observed upon VZV-peptide stimulation, compared to the healthy children. Collectively, the findings herein indicate that the children who are undergoing or have finished BM-suppressive treatment display qualitative differences in their T-cell memory compartment, potentially increasing their susceptibility to severe viral infections and impacting their immunotherapy, which relies on the functional ability of autologous T cells.

Multiple sclerosis risk variants influence the peripheral B-cell compartment early in life in the general population

BACKGROUND AND PURPOSE

Multiple sclerosis (MS) is associated with abnormal B-cell function, and MS genetic risk alleles affect multiple genes that are expressed in B cells. However, how these genetic variants impact the B-cell compartment in early childhood is unclear. In the current study, we aim to assess whether polygenic risk scores (PRSs) for MS are associated with changes in the blood B-cell compartment in children from the general population.

METHODS

Six-year-old children from the population-based Generation R Study were included. Genotype data were used to calculate MS-PRSs and B-cell subset-enriched MS-PRSs, established by designating risk loci based on expression and function. Analyses of variance were performed to examine the effect of MS-PRSs on total B-cell numbers (n = 1261) as well as naive and memory subsets (n = 675).

RESULTS

After correction for multiple testing, no significant associations were observed between MS-PRSs and total B-cell numbers and frequencies of subsets therein. A naive B-cell-MS-PRS (n = 26 variants) was significantly associated with lower relative, but not absolute, naive B-cell numbers (p = 1.03 × 10^-4 and p = 0.82, respectively), and higher frequencies and absolute numbers of CD27⁺ memory B cells (p = 8.83 × 10^-4 and p = 4.89 × 10^-3 , respectively). These associations remained significant after adjustment for Epstein-Barr virus seropositivity and the HLA-DRB1*15:01 genotype.

CONCLUSIONS

The composition of the blood B-cell compartment is associated with specific naive B-cell-associated MS risk variants during childhood, possibly contributing to MS pathophysiology later in life. Cell subset-specific PRSs may offer a more sensitive tool to define the impact of genetic risk on the immune system in diseases such as MS.

Four-Parameter FluoroSpot Assay Reveals That the Varicella Zoster Virus Elicits a Robust Memory T Cell IL-10 Response throughout Childhood

During childhood, the composition and function of the T cell compartment undergoes significant changes. In healthy individuals, primary infection with herpesviruses is followed by latency, and occasional subclinical reactivation ensures transmission and contributes to an emerging pool of memory T cells. In immunocompromised individuals, herpesviruses can be life threatening. However, knowledge about the spectrum of virus-specific cytokine responses is limited. Here, we investigated peripheral blood mononuclear cells (PBMCs) from children with differential carrier statuses for cytomegalovirus (CMV), Epstein-Barr virus (EBV), and varicella zoster virus (VZV) (n = 32, age 1 to 17 years). We examined memory T cell subsets as well as IFN-γ-, IL-10-, IL-17A-, and IL-22-producing T cells after polyclonal activation or stimulation with viral peptides using flow cytometry and a 4-parameter FluoroSpot assay. Age and herpesvirus carriage influenced the size of the memory T cell subsets. A positive association between age and the number of IFN-γ-, IL-17A- and IL-22-producing T cells was found following polyclonal activation. For CMV, age was positively associated with IL-17A spot-forming cells (SFC), while for VZV, age was negatively associated with IL-22 and positively associated with IFN-γ SFC. Upon activation with CMV, VZV, and EBV peptides, IFN-γ SFCs dominated. Notably, VZV responses were characterized by a higher IL-10 SFC population compared to both CMV and EBV. Our findings suggest that cytokine responses vary across herpesvirus-type-specific memory T cells and may more adequately reflect their composition. An observed deviation between polyclonal and herpesvirus-specific T cell cytokine responses in children needs to be considered when interpreting the associations between herpesvirus carrier status and bulk T cell reactivity. In summary, these findings may have implications for the treatment of immunocompromised patients. IMPORTANCE Infection with herpesviruses accounts for 35 to 40 billion human cases worldwide. Despite this, little is known about how herpesviruses shape the immune system in the asymptomatic carrier. Particularly in children, primary infection is connected to no or mild symptoms ahead of latency for life. Most research on cellular responses against herpesviruses focuses on inflammatory cytokines associated with antiproliferative and antitumor mechanisms and not the spectrum of cytokine responses in healthy humans. This study investigated four divergent cytokine-producing T cell responses to herpesviruses, reflecting different immunological functions. Three common childhood herpesviruses were selected: Epstein-Barr virus, cytomegalovirus, and varicella-zoster virus. Curiously, not all viruses induced the same pattern of cytokines. Varicella-zoster responses were characterized by IL-10, which is considered regulatory. Besides broadening understanding of responses to herpesviruses, our results raise the possibility that reactivation of varicella-zoster may be counterproductive in cancer treatment through the action of IL-10-producing T-cells.

Advances in allergen-specific immune cell measurements for improved detection of allergic sensitization and immunotherapy responses

Over the past two decades, precision medicine has advanced diagnostics and treatment of allergic diseases. Component-resolved analysis of allergen sensitization facilitates stratification of patients. Furthermore, new formulations of allergen immunotherapy (AIT) products can more effectively deliver the relevant components. Molecular insights from the identification of allergen component sensitization and clinical outcomes of treatment with new AIT formulations can now be utilized for a deeper understanding of the nature of the pathogenic immune response in allergy and how this can be corrected by AIT. Fundamental in these processes are the allergen-specific B and T cells. Within the large B- and T-cell compartments, only those that specifically recognize the allergen with their immunoglobulin (Ig) or T-cell receptor (TCR), respectively, are of clinical relevance. With peripheral blood allergen-specific B- and T-cell frequencies below 1%, bulk cell analysis is typically insufficiently sensitive. We here review the latest technologies to detect allergen-specific B and T cells, as well as new developments in utilizing these tools for diagnostics and therapy monitoring to advance precision medicine for allergic diseases.

Associations between T cells and attention problems in the general pediatric population: The Generation R study

Objective

The pathogenesis of attention-deficit/hyperactivity disorder (ADHD) is currently unclear. We hypothesized that chronic immune activation, as indexed by T and B cells, plays a role in the pathophysiology of attention problems. Therefore, we examined T and B cell subsets in a general pediatric population with information on attention problems.

Methods

We included 756 10-year-old children from the Generation R population-based cohort. Eleven-color flow cytometry was performed on peripheral blood samples to determine T and B cell subsets. The Child Behavior Checklist rated by parents was used to measure attention problems. Data were analyzed using linear regression analyses, adjusting for maternal and child covariates and co-occurring childhood psychopathology.

Results

For T helper 1 (Th1) cells, one standard deviation (SD) increase was associated with 5.3% (95%CI 0.3; 10.5) higher attention problem scores. Furthermore, 1SD increase in CD8+ T cells was associated with 7.5% (95%CI 2.4; 12.7) higher attention problem scores. Within total CD8+ T cells, 1SD increase in naive or central memory cells was associated with 6.9% (95%CI 2.0; 12.1) and 6.4% (95%CI 1.5; 11.6) higher attention problem scores, respectively. No associations between Th2, Treg or B memory cells and attention problem scores were observed.

Conclusion

Higher Th1 and cytotoxic T cell numbers are associated with higher attention problem scores independent of co-occurring psychopathology. This might indicate a possible role of a pro-inflammatory immune profile in childhood attention problems.

Childhood Adiposity Associated With Expanded Effector Memory CD8+ and Vδ2+Vγ9+ T Cells

CONTEXT

Adult obesity is associated with chronic low-grade inflammation and may give rise to future chronic disease. However, it is unclear whether adiposity-related inflammation is already apparent in childhood.

OBJECTIVE

To study associations between child adiposity measures with circulating monocytes and naive and memory subsets in CD4, CD8, and γδ T cell lineages.

METHODS

Ten-year-old children (n = 890) from the Generation R Cohort underwent dual-energy x-ray absorptiometry and magnetic resonance imaging for body composition (body mass index [BMI], fat mass index [FMI], android-to-gynoid fat mass ratio, visceral fat index, liver fat fraction). Blood samples were taken for detailed immunophenotyping of leukocytes by 11-color flow cytometry.

RESULTS

Several statistically significant associations were observed. A 1-SD increase in total FMI was associated with +8.4% (95% CI 2.0, 15.2) Vδ2+Vγ9+ and +7.4% (95% CI 2.4, 12.5) CD8+TEMRO cell numbers. A 1-SD increase in visceral fat index was associated with +10.7% (95% CI 3.3, 18.7) Vδ2+Vγ9+ and +8.3% (95% CI 2.6, 14.4) CD8+TEMRO cell numbers. Higher android-to-gynoid fat mass ratio was only associated with higher Vδ2+Vγ9+ T cells. Liver fat was associated with higher CD8+TEMRO cells but not with Vδ2+Vγ9+ T cells. Only liver fat was associated with lower Th17 cell numbers: a 1-SD increase was associated with -8.9% (95% CI -13.7, -3.7) Th17 cells. No associations for total CD8+, CD4+ T cells, or monocytes were observed. BMI was not associated with immune cells.

CONCLUSION

Higher Vδ2+Vγ9+ and CD8+TEMRO cell numbers in children with higher visceral fat index could reflect presence of adiposity-related inflammation in children with adiposity of a general population.

Impact of Early Versus Late Antiretroviral Treatment Initiation on Naive T Lymphocytes in HIV-1-Infected Children and Adolescents - The-ANRS-EP59-CLEAC Study

Background

The early initiation of antiretroviral therapy (ART) in HIV-1-infected infants reduces mortality and prevents early CD4 T-cell loss. However, the impact of early ART on the immune system has not been thoroughly investigated in children over five years of age or adolescents. Here, we describe the levels of naive CD4 and CD8 T lymphocytes (CD4/CD8TN), reflecting the quality of immune reconstitution, as a function of the timing of ART initiation (early (<6 months) versus late (≥24 months of age)).

Methods

The ANRS-EP59-CLEAC study enrolled 27 children (5-12 years of age) and nine adolescents (13-17 years of age) in the early-treatment group, and 19 children (L-Ch) and 21 adolescents (L-Ado) in the late-treatment group. T lymphocytes were analyzed by flow cytometry and plasma markers were analyzed by ELISA. Linear regression analysis was performed with univariate and multivariate models.

Results

At the time of evaluation, all patients were on ART and had a good immunovirological status: 83% had HIV RNA loads below 50 copies/mL and the median CD4 T-cell count was 856 cells/µL (interquartile range: 685-1236 cells/µL). In children, early ART was associated with higher CD8TN percentages (medians: 48.7% vs. 31.0%, P = 0.001), and a marginally higher CD4TN (61.2% vs. 53.1%, P = 0.33). In adolescents, early ART was associated with low CD4TN percentages and less differentiated memory CD8 T cells. CD4TN and CD8TN levels were inversely related to cellular activation and gut permeability.

Conclusion

In children and adolescents, the benefits of early ART for CD8TN were clear after long-term ART. The impact of early ART on CD4TN appears to be modest, because pediatric patients treated late respond to HIV-driven CD4 T-lymphocyte loss by the de novo production of TN cells in the thymus. Our data also suggest that current immune activation and/or gut permeability has a negative impact on TN levels.

Clinical Trial Registration

ClinicalTrials.gov, identifier NCT02674867.

Biological stratification of clinical disease courses in childhood immune thrombocytopenia

BACKGROUND

In childhood immune thrombocytopenia (ITP), an autoimmune bleeding disorder, there is a need for better prediction of individual disease courses and treatment outcomes.

OBJECTIVE

To predict the response to intravenous immunoglobulins (IVIg) and ITP disease course using genetic and immune markers.

METHODS

Children aged younger than 7 years with newly diagnosed ITP (N = 147) from the Treatment With or Without IVIG for Kids with ITP study were included, which randomized children to an IVIg or observation group. A total of 46 variables were available: clinical characteristics, targeted genotyping, lymphocyte immune phenotyping, and platelet autoantibodies.

RESULTS

In the treatment arm, 48/80 children (60%) showed a complete response (platelets ≥100 × 109 /L) that lasted for at least 1 month (complete sustained response [CSR]) and 32 exhibited no or a temporary response (absence of a sustained response [ASR]). For a biological risk score, five variables were selected by regularized logistic regression that predicted ASR vs CSR: (1) hemoglobin; (2) platelet count; (3) genetic polymorphisms of Fc-receptor (FcγR) IIc; (4) the presence of immunoglobulin G (IgG) anti-platelet antibodies; and (5) preceding vaccination. The ASR sensitivity was 0.91 (95% confidence interval, 0.80-1.00) and specificity was 0.67 (95% confidence interval, 0.53-0.80). In the 67 patients of the observation arm, this biological score was also associated with recovery during 1 year of follow-up. The addition of the biological score to a predefined clinical score further improved the discrimination of favorable ITP disease courses.

CONCLUSIONS

The prediction of disease courses and IVIg treatment responses in ITP is improved by using both clinical and biological stratification.

Early clinical predictors for the prognosis of invasive pneumococcal disease

Background

Risk factors related to mortality due to invasive pneumococcal disease (IPD) have been unveiled previously, but early clinical manifestations of IPD based on prognosis remain uncovered.

Methods

The demographic characteristics, clinical features, serotype, antibiotic susceptibility, and outcomes of 97 hospitalized children with laboratory-confirmed IPD from Suzhou, China, were collected and analyzed retrospectively.

Results

The median age was 0.69 (0.49–1.55) years in the non-survivor group compared with 2.39 (0.90–3.81) years in the survivor group. The mortality of 97 children with laboratory-confirmed IPD was 17.5% (17/97), and 53.6% of them were aged less than 2 years. Pathogens were mainly from the blood and cerebrospinal fluid, and sepsis was the most frequent type. Statistically significant differences were found in hyperpyrexia, vomiting, anorexia, lethargy, poor perfusion of extremities, Hb level, and Plt count between the nonsurvival and survival groups. Further, the multivariate regression analysis showed that early signs, including hyperpyrexia, vomiting, anorexia, lethargy, and poor perfusion of extremities, were independent risk factors for the in-hospital mortality of children with laboratory-confirmed IPD. The mortality was also associated with antimicrobial sensitivity in pneumococcal isolates. The microbes in 1/17 (5.9%) children who were prescribed an antibiotic showed antimicrobial sensitivity in the nonsurvival group, compared with 21/80 (26.3%) children who survived. The most common serotypes identified were 6B (35.3%, 6/17), 14 (23.5%, 4/17), 19F (23.5%, 4/17), 19A (5.9%, 1/17), 23F (5.9%, 1/17), and 20 (5.9%, 1/17) in the nonsurvival group. The coverage of IPD serotypes of the 7-valent pneumococcal conjugate vaccine (PCV7) was 88.2% (15/17), while that of the 13-valent S. pneumoniae vaccine (PCV13) was 94.1% (16/17) of the coverage in the nonsurvival group.

Conclusions

Recurrent hyperpyrexia, vomiting, anorexia, lethargy, and poor perfusion of extremities in the early stage were independent predictors for the in-hospital mortality of children with laboratory-confirmed IPD. Appropriate use of antibiotics and PCV immunization were the keys to improve the outcome of IPD.

Fetal public Vγ9Vδ2 T cells expand and gain potent cytotoxic functions early after birth

Vγ9Vδ2 T cells are a major human blood γδ T cell population that respond in a T cell receptor (TCR)-dependent manner to phosphoantigens which are generated by a variety of microorganisms. It is not clear how Vγ9Vδ2 T cells react toward the sudden microbial exposure early after birth. We found that human Vγ9Vδ2 T cells with a public/shared fetal-derived TCR repertoire expanded within 10 wk postpartum. Such an expansion was not observed in non-Vγ9Vδ2 γδ T cells, which possessed a private TCR repertoire. Furthermore, only the Vγ9Vδ2 T cells differentiated into potent cytotoxic effector cells by 10 wk of age, despite their fetal origin. Both the expansion of public fetal Vγ9Vδ2 T cells and their functional differentiation were not affected by newborn vaccination with the phosphoantigen-containing bacillus Calmette-Guérin (BCG) vaccine. These findings suggest a strong and early priming of the public fetal-derived Vγ9Vδ2 T cells promptly after birth, likely upon environmental phosphoantigen exposure.

In-depth immune cellular profiling reveals sex-specific associations with frailty

Background

With advancing age, the composition of leukocyte subpopulations in peripheral blood is known to change, but how this change differs between men and women and how it relates to frailty is poorly understood. Our aim in this exploratory study was to investigate whether frailty is associated with changes in immune cell subpopulations and whether this differs between men and women. Therefore, we performed in-depth immune cellular profiling by enumerating a total of 37 subpopulations of T cells, B cells, NK cells, monocytes, and neutrophils in peripheral blood of 289 elderly people between 60-87 years of age. Associations between frailty and each immune cell subpopulation were tested separately in men and women and were adjusted for age and CMV serostatus. In addition, a random forest algorithm was used to predict a participant’s frailty score based on enumeration of immune cell subpopulations.

Results

In the association study, frailty was found to be associated with increased numbers of neutrophils in both men and in women. Frailer women, but not men, showed higher numbers of total and CD16^- monocytes, and lower numbers of both CD56⁺ T cells and late differentiated CD4⁺ TemRA cells. The random forest algorithm confirmed all the findings of the association studies in men and women. In men, the predictive accuracy of the algorithm was too low (5.5%) to warrant additional conclusions on top of the ones derived from the association study. In women however, the predictive accuracy was higher (23.1%), additionally revealing that total T cell numbers and total lymphocyte numbers also contribute in predicting frailty.

Conclusions

In-depth immune cellular profiling revealed consistent associations of frailty with elevated numbers of myeloid cell subpopulations in both men and women. Furthermore, additional associations were found between frailty and lower numbers of some T cell subpopulations, in women only. Thus, our study indicates sex-specific associations of immune subpopulations with frailty. We hope that our study will prompt further investigation into the sex-specific immune mechanisms associated with the development of frailty.

The influence of Epstein-Barr virus and cytomegalovirus on childhood respiratory health: A population-based prospective cohort study

Background

Epstein‐Barr virus (EBV) and cytomegalovirus (CMV) infection are common in early childhood. CMV infection favours a T‐helper‐1 and EBV infection a T‐helper‐2 cell response, possibly leading to disbalanced T‐helper cell response, and subsequent risk of asthma or atopy.

Objective

To study the associations of EBV and CMV with lung function, asthma and inhalant allergic sensitization at school age.

Methods

This study among 3546 children was embedded in a population‐based prospective cohort. At age 6 years, serum IgG levels against EBV and CMV were measured by ELISA. At age 10 years, lung function was measured by spirometry, asthma by questionnaire and inhalant allergic sensitization by skin prick test.

Results

Unadjusted models showed that seropositivity for EBV was associated with a higher FEV₁ and FEF₇₅ (Z‐score difference (95% CI): 0.09 (0.02, 0.16) and 0.09 (0.02, 0.15)), while seropositivity for CMV was not. Specific combinations of viruses showed that seropositivity for EBV was only associated with FEV₁ and FEF₇₅ in the presence of seropositivity for CMV (0.12 (0.04, 0.20)) and 0.08 (0.01, 0.15)). Seropositivity for CMV in the absence of seropositivity for EBV was associated with an increased risk of inhalant allergic sensitization (OR (95% CI): 1.31 (1.02, 1.68)). All effect estimates attenuated into non‐significant mainly after adjustment for child's ethnicity. Seropositivity for EBV or CMV was not associated with asthma.

Conclusions and Clinical Relevance

Associations of EBV and CMV infections in early childhood with school‐age lung function and inhalant allergic sensitization are explained by ethnicity, or sociodemographic and lifestyle‐related factors.

Immune system development varies according to age, location, and anemia in African children

Children from low- and middle-income countries, where there is a high incidence of infectious disease, have the greatest need for the protection afforded by vaccination, but vaccines often show reduced efficacy in these populations. An improved understanding of how age, infection, nutrition, and genetics influence immune ontogeny and function is key to informing vaccine design for this at-risk population. We sought to identify factors that shape immune development in children under 5 years of age from Tanzania and Mozambique by detailed immunophenotyping of longitudinal blood samples collected during the RTS,S malaria vaccine phase 3 trial. In these cohorts, the composition of the immune system is dynamically transformed during the first years of life, and this was further influenced by geographical location, with some immune cell types showing an altered rate of development in Tanzanian children compared to Dutch children enrolled in the Generation R population-based cohort study. High-titer antibody responses to the RTS,S/AS01E vaccine were associated with an activated immune profile at the time of vaccination, including an increased frequency of antibody-secreting plasmablasts and follicular helper T cells. Anemic children had lower frequencies of recent thymic emigrant T cells, isotype-switched memory B cells, and plasmablasts; modulating iron bioavailability in vitro could recapitulate the B cell defects observed in anemic children. Our findings demonstrate that the composition of the immune system in children varies according to age, geographical location, and anemia status.

Characterization of the γδ T-cell compartment during infancy reveals clear differences between the early neonatal period and 2 years of age

γδ T cells are unconventional T cells that function on the border of innate and adaptive immunity. They are suggested to play important roles in neonatal and infant immunity, although their phenotype and function are not fully characterized in early childhood. We aimed to investigate γδ T cells in relation to age, prematurity and cytomegalovirus (CMV) infection. Therefore, we used flow cytometry to characterize the γδ T-cell compartment in cord blood and peripheral blood cells from 14-day-, 2-year- and 5-year-old children, as well as in peripheral blood samples collected at several time points during the first months of life from extremely premature neonates. γδ T cells were phenotypically similar at 2 and 5 years of age, whereas cord blood was divergent and showed close proximity to γδ T cells from 14-day-old neonates. Interestingly, 2-year-old children and adults showed comparable Vδ2+ γδ T-cell functionality toward both microbial and polyclonal stimulations. Importantly, extreme preterm birth compromised the frequencies of Vδ1+ cells and affected the functionality of Vδ2+ γδ T cells shortly after birth. In addition, CMV infection was associated with terminal differentiation of the Vδ1+ compartment at 2 years of age. Our results show an adult-like functionality of the γδ T-cell compartment already at 2 years of age. In addition, we demonstrate an altered γδ T-cell phenotype early after birth in extremely premature neonates, something which could possible contribute to the enhanced risk for infections in this vulnerable group of children.

Associations of Th2, Th17, Treg cells, and IgA+ memory B cells with atopic disease in children: The Generation R Study

BACKGROUND

New insights into immune cells could contribute to treatment and monitoring of atopic disease. Because nongenetic factors shape the human immune system, we here studied these immune cells in a large cohort with atopic children with adjustment for prenatal and postnatal confounders.

METHODS

Information on atopic dermatitis, inhalant- and food-allergic sensitization, asthma lung function scores was obtained from 855 10-year-old children within the Generation R cohort. 11-color flow cytometry was performed to determine CD27⁺ and CD27^- IgG⁺ , IgE⁺ and IgA⁺ memory B cells, Th1, Th2, Th17, and Treg-memory cells from venous blood. Associations between any atopic disease, the individual atopic diseases, and immune cell numbers were determined.

RESULTS

Children with any atopic disease had higher Th2, Treg, Treg-memory, and CD27⁺ IgA⁺ memory B-cell numbers compared to children without atopic disease. When studying the individual diseases compared to children without the individual diseases, children with atopic dermatitis, inhalant-, and food-allergic sensitization had higher memory Treg cell numbers 12.3% (95% CI 4.2; 21.0), (11.1% (95% CI 3.0; 19.8), (23.7% (95% CI 7.9; 41.8), respectively. Children with food-allergic sensitization had higher total B and CD27⁺ IgA⁺ memory B-cell numbers (15.2% [95% CI 3.2; 28.7], 22.5% [95% CI 3.9; 44.3], respectively). No associations were observed between asthma and B- or T-cell numbers.

CONCLUSION

Children with any atopic disease and children with inhalant- and food-allergic sensitization or atopic dermatitis had higher circulating memory Treg cells, but not higher IgE⁺ B-cell numbers. The associations of higher Treg and CD27⁺ IgA⁺ B-cell numbers in children with food-allergic sensitization are suggestive of TGF-β-mediated compensation for chronic inflammation.

Age at cytomegalovirus, Epstein Barr virus and varicella zoster virus infection and risk of atopy: The Born in Bradford cohort, UK

BACKGROUND

The prevalence of allergic diseases has increased in recent decades, but the causes remain unclear. Changes in the epidemiology of childhood infections could have contributed, but the current evidence is inconclusive. This study aims to investigate whether age at cytomegalovirus (CMV), Epstein-Barr virus (EBV) or varicella zoster virus (VZV) infection is associated with the development of atopy.

METHODS

A total of 2559 children were enrolled in the Born in Bradford Allergy and Infection Study. Serum samples collected at 12 and 24 months were tested for CMV-IgG, EBV-IgG and VZV-IgG for 1000 children to establish age at infection. Skin prick testing (SPT) was conducted at age 4 years.

RESULTS

Serology and SPT results were available for 740 children. Of these, 135 (18%) were atopic. In girls, there was a strong association of CMV infection in the second year with increased odds of atopy (adjusted OR 4.38, 95% CI 1.87-10.29) but this was not observed in boys. Age at EBV or VZV infection was not associated with risk of atopy in unadjusted analysis, but there was effect modification by sex; girls infected with VZV in the second year of life had increased odds of atopy (adjusted OR 2.85, 95% CI 1.29-6.30).

CONCLUSIONS

Our results highlight potential sex-specific effects of age at CMV infection and age at VZV infection on risk of atopy, which provide insight into the mechanisms involved in the development of atopy.

Systematic evaluation and validation of reference and library selection methods for deconvolution of cord blood DNA methylation data

BACKGROUND

Umbilical cord blood (UCB) is commonly used in epigenome-wide association studies of prenatal exposures. Accounting for cell type composition is critical in such studies as it reduces confounding due to the cell specificity of DNA methylation (DNAm). In the absence of cell sorting information, statistical methods can be applied to deconvolve heterogeneous cell mixtures. Among these methods, reference-based approaches leverage age-appropriate cell-specific DNAm profiles to estimate cellular composition. In UCB, four reference datasets comprising DNAm signatures profiled in purified cell populations have been published using the Illumina 450 K and EPIC arrays. These datasets are biologically and technically different, and currently, there is no consensus on how to best apply them. Here, we systematically evaluate and compare these datasets and provide recommendations for reference-based UCB deconvolution.

RESULTS

We first evaluated the four reference datasets to ascertain both the purity of the samples and the potential cell cross-contamination. We filtered samples and combined datasets to obtain a joint UCB reference. We selected deconvolution libraries using two different approaches: automatic selection using the top differentially methylated probes from the function pickCompProbes in minfi and a standardized library selected using the IDOL (Identifying Optimal Libraries) iterative algorithm. We compared the performance of each reference separately and in combination, using the two approaches for reference library selection, and validated the results in an independent cohort (Generation R Study, n = 191) with matched Fluorescence-Activated Cell Sorting measured cell counts. Strict filtering and combination of the references significantly improved the accuracy and efficiency of cell type estimates. Ultimately, the IDOL library outperformed the library from the automatic selection method implemented in pickCompProbes.

CONCLUSION

These results have important implications for epigenetic studies in UCB as implementing this method will optimally reduce confounding due to cellular heterogeneity. This work provides guidelines for future reference-based UCB deconvolution and establishes a framework for combining reference datasets in other tissues.

[Clinical characteristics and drug sensitivity in children with invasive pneumococcal disease: a multicenter study]

OBJECTIVE

To study the clinical characteristics, drug sensitivity of isolated strains, and risk factors of drug resistance in children with invasive pneumococcal disease (IPD).

METHODS

The clinical characteristics and drug sensitivity of the isolated strains of 246 hospitalized children with IPD in nine grade A tertiary children's hospitals from January 2016 to June 2018 were analyzed.

RESULTS

Of the 246 children with IPD, there were 122 males and 124 females. Their ages ranged from 1 day to 14 years, and among them, 68 (27.6%) patients were less than 1 year old, 54 (22.0%) patients were 1 to 2 years old, 97 (39.4%) patients were 2 to 5 years old, and 27 (11.0%) patients were 5 to 14 years old. Pneumonia with sepsis was the most common infection type (58.5%, 144/246), followed by bloodstream infection without focus (19.9%, 49/246) and meningitis (15.0%, 37/246). Forty-nine (19.9%) patients had underlying diseases, and 160 (65.0%) had various risk factors for drug resistance. The isolated Streptococcus pneumoniae strains were 100% sensitive to vancomycin, linezolid, moxifloxacin, and levofloxacin, 90% sensitive to ertapenem, ofloxacin, and ceftriaxone, but had a low sensitivity to erythromycin (4.2%), clindamycin (7.9%), and tetracycline (6.3%).

CONCLUSIONS

IPD is more common in children under 5 years old, especially in those under 2 years old. Some children with IPD have underlying diseases, and most of the patients have various risk factors for drug resistance. Pneumonia with sepsis is the most common infection type. The isolated Streptococcus pneumoniae strains are highly sensitive to vancomycin, linezolid, moxifloxacin, levofloxacin, ertapenem, and ceftriaxone in children with IPD.

Defects in memory B-cell and plasma cell subsets expressing different immunoglobulin-subclasses in patients with CVID and immunoglobulin subclass deficiencies

BACKGROUND

Predominantly antibody deficiencies (PADs) are the most prevalent primary immunodeficiencies, but their B-cell defects and underlying genetic alterations remain largely unknown.

OBJECTIVE

We investigated patients with PADs for the distribution of 41 blood B-cell and plasma cell (PC) subsets, including subsets defined by expression of distinct immunoglobulin heavy chain subclasses.

METHODS

Blood samples from 139 patients with PADs, 61 patients with common variable immunodeficiency (CVID), 68 patients with selective IgA deficiency (IgAdef), 10 patients with IgG subclass deficiency with IgA deficiency, and 223 age-matched control subjects were studied by using flow cytometry with EuroFlow immunoglobulin isotype staining. Patients were classified according to their B-cell and PC immune profile, and the obtained patient clusters were correlated with clinical manifestations of PADs.

RESULTS

Decreased counts of blood PCs, memory B cells (MBCs), or both expressing distinct IgA and IgG subclasses were identified in all patients with PADs. In patients with IgAdef, B-cell defects were mainly restricted to surface membrane (sm)IgA⁺ PCs and MBCs, with 2 clear subgroups showing strongly decreased numbers of smIgA⁺ PCs with mild versus severe smIgA⁺ MBC defects and higher frequencies of nonrespiratory tract infections, autoimmunity, and affected family members. Patients with IgG subclass deficiency with IgA deficiency and those with CVID showed defects in both smIgA⁺ and smIgG⁺ MBCs and PCs. Reduced numbers of switched PCs were systematically found in patients with CVID (absent in 98%), with 6 different defective MBC (and clinical) profiles: (1) profound decrease in MBC numbers; (2) defective CD27⁺ MBCs with almost normal IgG₃⁺ MBCs; (3) absence of switched MBCs; and (4) presence of both unswitched and switched MBCs without and; (5) with IgG₂⁺ MBCs; and (6) with IgA₁⁺ MBCs.

CONCLUSION

Distinct PAD defective B-cell patterns were identified that are associated with unique clinical profiles.

Early childhood CMV infection may decelerate the progression to clinical type 1 diabetes

AIMS/HYPOTHESIS

Evidence of the role of cytomegalovirus (CMV) infection in the pathogenesis of type 1 diabetes (T1D) has remained inconclusive. Our aim was to elucidate the possible role of CMV infection in the initiation of islet autoimmunity and in the progression to clinical T1D among children with human leukocyte antigen (HLA)-conferred T1D risk.

METHODS

A total of 1402 children from the prospective Type 1 Diabetes Prediction and Prevention (DIPP) study were analyzed for CMV-specific IgG antibodies during early childhood. All the children carried HLA-DQ genotypes associated with increased risk for T1D. The effect of CMV infection on the appearance of T1D-associated autoantibodies (insulin autoantibodies [IAA], glutamic acid decarboxylase [GADA], and insulinoma antigen-2 [IA-2A], n = 356) and on the progression rate to clinical T1D (n = 233) were analyzed with Kaplan-Meier survival analysis and Log-rank test.

RESULTS

Early childhood CMV infection was inversely associated with the development of T1D during childhood. Cumulative progression to T1D was decreased in subjects with an early CMV infection (P = 0.035). In further analyses, the effect of early CMV infection on the initiation of islet autoimmunity and progression to clinical T1D were examined separately. Interestingly, early CMV infection did not affect the appearance of T1D-associated autoantibodies but a decelerating effect was observed on the progression rate from islet autoimmunity to clinical T1D (P = 0.015).

CONCLUSION

Our results suggest that an early childhood CMV infection may decelerate the progression from islet autoimmunity to clinical T1D among at-risk children and may thus protect these children from progressing to T1D during childhood.

Elevated CD3low double negative T lymphocyte is associated with pneumonia and its severity in pediatric patients

Background

Previous studies have shown that the adaptive immunity function of T cells in disease states correlates with CD3 surface expression closely. During routine assessment of TBNK subsets in peripheral blood of pediatric patients by flow cytometry, we noticed that variable expression levels of CD3 on CD3⁺CD4⁻CD8⁻ double-negative T (DNT) lymphocytes in different patients. The objective of this study was to assess the relationship of CD3 expression levels on DNT cells with disease severity.

Methods

In this prospective study, we investigated the frequencies of circulating CD4⁻CD8⁻ DNT cell subsets with CD3^low or CD3^high phenotype by flow cytometry in 76 pediatric patients with pneumonia, 55 patients with severe pneumonia (SP), and 29 healthy controls (Con).

Results

The numbers of circulating DNT cells were similar in all groups; however, the frequency of CD3^low DNT cell subsets was significantly increased in patients with pneumonia (p < 0.001) and SP (p < 0.001). The elevated CD3^low DNT cell frequency showed a positive correlation with the clinical severity of pneumonia. On sub-group analysis, the frequency of CD3^low DNT cells was only elevated in children with pneumonia aged <5 years, while no association was observed with the causative pathogen of pneumonia.

Conclusions

These findings suggest that CD3 expression levels on DNT cell subsets of peripheral lymphocytes may be a valuable biomarker for evaluation of immune response in pediatric infectious disease. CD3^low DNT cells were elevated in children with pneumonia aged <5 years, which indicates that it may be an important research target in pediatric infectious diseases.

An Explorative Biomarker Study for Vaccine Responsiveness after a Primary Meningococcal Vaccination in Middle-Aged Adults

Introduction

Prevention of infectious diseases in the elderly is essential to establish healthy aging. Yet, immunological aging impairs successful vaccination of the elderly. Predictive biomarkers for vaccine responsiveness in middle-aged adults may help to identify responders and non-responders before reaching old age. Therefore, we aimed to determine biomarkers associated with low and high responsiveness toward a primary vaccination in middle-aged adults, for which a tetravalent meningococcal vaccine was used as a model.

Methods

Middle-aged adults (50–65 years of age, N = 100), receiving a tetravalent meningococcal vaccination, were divided into low and high responders using the functional antibody titers at 28 days postvaccination. A total of 48 parameters, including absolute numbers of immune cells and serum levels of cytokines and biochemical markers, were determined prevaccination in all participants. Heat maps and multivariate redundancy analysis (RDA) were used to reveal immune phenotype characteristics and associations of the low and high responders.

Results

Several significant differences in prevaccination immune markers were observed between the low and high vaccine responders. Moreover, RDA analysis revealed a significant association between the prevaccination immune phenotype and vaccine responsiveness. In particular, our analysis pointed at high numbers of CD4 T cells, especially naïve CD4 and regulatory T subsets, to be associated with low vaccine responsiveness. In addition, low responders showed lower prevaccination IL-1Ra levels than high responders.

Conclusion

This explorative biomarker study shows associations between the prevaccination immune phenotype and vaccine responsiveness after a primary meningococcal vaccination in middle-aged adults. Consequently, these results provide a basis for predictive biomarker discovery for vaccine responsiveness that will require validation in larger cohort studies.

Ageing and latent CMV infection impact on maturation, differentiation and exhaustion profiles of T-cell receptor gammadelta T-cells

Ageing is a broad cellular process, largely affecting the immune system, especially T-lymphocytes. Additionally to immunosenescence alone, cytomegalovirus (CMV) infection is thought to have major impacts on T-cell subset composition and exhaustion. These impacts have been studied extensively in TCRαβ+ T-cells, with reduction in naive, increase in effector (memory) subsets and shifts in CD4/CD8-ratios, in conjunction with morbidity and mortality in elderly. Effects of both ageing and CMV on the TCRγδ+ T-cell compartment remain largely elusive. In the current study we investigated Vγ- and Vδ-usage, maturation, differentiation and exhaustion marker profiles of both CD4 and CD8 double-negative (DN) and CD8+TCRγδ+ T-cells in 157 individuals, age range 20–95. We observed a progressive decrease in absolute numbers of total TCRγδ+ T-cells in blood, affecting the predominant Vγ9/Vδ2 population. Aged TCRγδ+ T-cells appeared to shift from naive to more (late-stage) effector phenotypes, which appeared more prominent in case of persistent CMV infections. In addition, we found effects of both ageing and CMV on the absolute counts of exhausted TCRγδ+ T-cells. Collectively, our data show a clear impact of ageing and CMV persistence on DN and CD8+TCRγδ+ T-cells, similar to what has been reported in CD8+TCRαβ+ T-cells, indicating that they undergo similar ageing processes.