Exhaled Volatile Organic Compounds for Asthma Control Classification in Children with Moderate to Severe Asthma: Results from the SysPharmPediA Study.

RATIONALE: Early identification of children with poorly controlled asthma is imperative for optimizing treatment strategies. The analysis of exhaled volatile organic compounds (VOCs) is an emerging approach to identify prognostic and diagnostic biomarkers in pediatric asthma. OBJECTIVES: To assess the accuracy of gas chromatography-mass spectrometry based exhaled metabolite analysis to differentiate between controlled and uncontrolled pediatric asthma. METHODS: This study encompassed a discovery (SysPharmPediA) and validation phase (U-BIOPRED, PANDA). Firstly, exhaled VOCs that discriminated asthma control levels were identified. Subsequently, outcomes were validated in two independent cohorts. Patients were classified as controlled or uncontrolled, based on asthma control test scores and number of severe attacks in the past year. Additionally, potential of VOCs in predicting two or more future severe asthma attacks in SysPharmPediA was evaluated. MEASUREMENTS AND MAIN RESULTS: Complete data were available for 196 children (SysPharmPediA=100, U-BIOPRED=49, PANDA=47). In SysPharmPediA, after randomly splitting the population into training (n=51) and test sets (n=49), three compounds (acetophenone, ethylbenzene, and styrene) distinguished between uncontrolled and controlled asthmatics. The area under the receiver operating characteristic curve (AUROCC) for training and test sets were respectively: 0.83 (95% CI: 0.65-1.00) and 0.77 (95% CI: 0.58-0.96). Combinations of these VOCs resulted in AUROCCs of 0.74 ±0.06 (UBIOPRED) and 0.68 ±0.05 (PANDA). Attacks prediction tests, resulted in AUROCCs of 0.71 (95% CI 0.51-0.91) and 0.71 (95% CI 0.52-0.90) for training and test sets. CONCLUSIONS: Exhaled metabolites analysis might enable asthma control classification in children. This should stimulate further development of exhaled metabolites-based point-of-care tests in asthma.

Classifying asthma control using salivary and fecal bacterial microbiome in children with moderate-to-severe asthma.

BACKGROUND: Uncontrolled asthma can lead to severe exacerbations and reduced quality of life. Research has shown that the microbiome may be linked with asthma characteristics; however, its association with asthma control has not been explored. We aimed to investigate whether the gastrointestinal microbiome can be used to discriminate between uncontrolled and controlled asthma in children. METHODS: 143 and 103 feces samples were obtained from 143 children with moderate-to-severe asthma aged 6 to 17 years from the SysPharmPediA study. Patients were classified as controlled or uncontrolled asthmatics, and their microbiome at species level was compared using global (alpha/beta) diversity, conventional differential abundance analysis (DAA, analysis of compositions of microbiomes with bias correction), and machine learning [Recursive Ensemble Feature Selection (REFS)]. RESULTS: Global diversity and DAA did not find significant differences between controlled and uncontrolled pediatric asthmatics. REFS detected a set of taxa, including Haemophilus and Veillonella, differentiating uncontrolled and controlled asthma with an average classification accuracy of 81% (saliva) and 86% (feces). These taxa showed enrichment in taxa previously associated with inflammatory diseases for both sampling compartments, and with COPD for the saliva samples. CONCLUSION: Controlled and uncontrolled children with asthma can be differentiated based on their gastrointestinal microbiome using machine learning, specifically REFS. Our results show an association between asthma control and the gastrointestinal microbiome. This suggests that the gastrointestinal microbiome may be a potential biomarker for treatment responsiveness and thereby help to improve asthma control in children.

Symptoms and immunoglobulin development in hospital staff exposed to a SARS-CoV-2 outbreak.

BACKGROUND: Worldwide, the number of SARS-CoV-2 infections is increasing. Serological immunoglobulin tests may help to better understand the development of immune mechanisms against SARS-CoV-2 in COVID-19 cases and exposed but asymptomatic individuals. The aim of this study was to investigate exposure to SARS-CoV-2, symptoms, and antibody responses in a large sample of healthcare workers following a COVID-19 outbreak. METHODS: A COVID-19 outbreak among staff members of a major German children's and women's hospital was followed by massive RT-PCR SARS-CoV-2 tests and provided the opportunity to study symptoms, chains of infection, and SARS-CoV-2-specific antibody responses (IgG and IgA) by ELISA. Study participants were classified as COVID-19 cases, and persons with close, moderate, or no exposure to SARS-CoV-2 in the clinical setting, respectively. RESULTS: Out of 201 study participants, 31 were COVID-19 cases. While most study participants experienced many symptoms indicative for SARS-CoV-2 infection, anosmia and coughing were remarkably more frequent in COVID-19 cases. Approximately 80% of COVID-19 cases developed some specific antibody response (IgA and IgG) approximately 3 weeks after onset of symptoms. Subjects in the non-COVID-19 groups had also elevated IgG (1.8%) and IgA values (7.6%) irrespective of contact history with cases. CONCLUSION: We found that a significant number of diseased did not develop relevant antibody responses three weeks after symptom onset. Our data also suggest that exposure to COVID-19 positive co-workers in a hospital setting is not leading to the development of measurable immune responses in a significant proportion of asymptomatic contact persons.

6q12 and 11p14 variants are associated with postnatal exhaled nitric oxide levels and respiratory symptoms.

BACKGROUND: Exhaled nitric oxide (eNO) is a biomarker of airway inflammation and seems to precede respiratory symptoms, such as asthma, in childhood. Identifying genetic determinants of postnatal eNO levels might aid in unraveling the role of eNO in epithelial function or airway inflammation and disease. OBJECTIVE: We sought to identify genetic determinants of early postnatal eNO levels and subsequent respiratory symptoms during the first year of life. METHODS: Within a population-based birth cohort, eNO levels were measured in healthy term infants aged 5 weeks during quiet tidal breathing in unsedated sleep. We assessed associations of single nucleotide polymorphisms with eNO levels in a genome-wide association study and subsequent symptoms of lower respiratory tract infections during the first year of life and asked whether this was modified by prenatal and early-life environmental factors. RESULTS: We identified thus far unknown determinants of infant eNO levels: rs208515 (P = 3.3 × 10-8), which is located at 6q12, probably acting in "trans" and explaining 10.3% of eNO level variance, and rs1441519 (P = 1.6 × 10-6), which is located at 11p14, potentially affecting nitric oxide synthase 3 (NOS3) expression, as shown by means of in vitro functional analyses. Moreover, the 6q12 locus was inversely associated with subsequent respiratory symptoms (P < .05) and time to recovery after first respiratory symptoms during the first year of life (P < .05). CONCLUSION: The identification of novel genetic determinants of infant eNO levels might implicate that postnatal eNO metabolism in healthy infants before first viral infections and sensitization is related to mechanisms other than those associated with asthma, atopy, or increased risk thereof later in life.

Doublesex and mab-3 related transcription factor 1 (DMRT1) is a sex-specific genetic determinant of childhood-onset asthma and is expressed in testis and macrophages.

BACKGROUND: Asthma is a disease affecting more boys than girls in childhood and more women than men in adulthood. The mechanisms behind these sex-specific differences are not yet understood. OBJECTIVE: We analyzed whether and how genetic factors contribute to sex-specific predisposition to childhood-onset asthma. METHODS: Interactions between sex and polymorphisms on childhood asthma risk were evaluated in the Multicentre Asthma Genetics in Childhood Study (MAGICS)/Phase II International Study of Asthma and Allergies in Childhood (ISAAC II) population on a genome-wide level, and findings were validated in independent populations. Genetic fine mapping of sex-specific asthma association signals was performed, and putatively causal polymorphisms were characterized in vitro by using electrophoretic mobility shift and luciferase activity assays. Gene and protein expression of the identified gene doublesex and mab-3 related transcription factor 1 (DMRT1) were measured in different human tissues by using quantitative real-time PCR and immunohistochemistry. RESULTS: Polymorphisms in the testis-associated gene DMRT1 displayed interactions with sex on asthma status in a population of primarily clinically defined asthmatic children and nonasthmatic control subjects (lowest P = 5.21 × 10(-6)). Replication of this interaction was successful in 2 childhood populations clinically assessed for asthma but showed heterogeneous results in other population-based samples. Polymorphism rs3812523 located in the putative DMRT1 promoter was associated with allele-specific changes in transcription factor binding and promoter activity in vitro. DMRT1 expression was observed not only in the testis but also in lung macrophages. CONCLUSION: DMRT1 might influence sex-specific patterns of childhood asthma, and its expression in testis tissue and lung macrophages suggests a potential involvement in hormone or immune cell regulation.

Polymorphisms related to ORMDL3 are associated with asthma susceptibility, alterations in transcriptional regulation of ORMDL3, and changes in TH2 cytokine levels.

BACKGROUND: Chromosome 17q21, harboring the orosomucoid 1-like 3 (ORMDL3) gene, has been consistently associated with childhood asthma in genome-wide association studies. OBJECTIVE: We investigated genetic variants in and around ORMDL3 that can change the function of ORMDL3 and thus contribute to asthma susceptibility. METHODS: We performed haplotype analyses and fine mapping of the ORMDL3 locus in a cross-sectional (International Study of Asthma and Allergies in Childhood Phase II, n = 3557 total subjects, n = 281 asthmatic patients) and case-control (Multicenter Asthma Genetics in Childhood Study/International Study of Asthma and Allergies in Childhood Phase II, n = 1446 total subjects, n = 763 asthmatic patients) data set to identify putative causal single nucleotide polymorphisms (SNPs) in the locus. Top asthma-associated polymorphisms were analyzed for allele-specific effects on transcription factor binding and promoter activity in vitro and gene expression in PBMCs after stimulation ex vivo. RESULTS: Two haplotypes (H1 and H2) were significantly associated with asthma in the cross-sectional (P = 9.9 × 10(-5) and P = .0035, respectively) and case-control (P = 3.15 × 10(-8) and P = .0021, respectively) populations. Polymorphisms rs8076131 and rs4065275 were identified to drive these effects. For rs4065275, a quantitative difference in transcription factor binding was found, whereas for rs8076131, changes in upstream stimulatory factor 1 and 2 transcription factor binding were observed in vitro by using different cell lines and PBMCs. This might contribute to detected alterations in luciferase activity paralleled with changes in ORMDL3 gene expression and IL-4 and IL-13 cytokine levels ex vivo in response to innate and adaptive stimuli in an allele-specific manner. Both SNPs were in strong linkage disequilibrium with asthma-associated 17q21 SNPs previously related to altered ORMDL3 gene expression. CONCLUSION: Polymorphisms in a putative promoter region of ORMDL3, which are associated with childhood asthma, alter transcriptional regulation of ORMDL3, correlate with changes in TH2 cytokines levels, and therefore might contribute to the childhood asthma susceptibility signal from 17q21.

Epigenome-Wide Association Studies of the Fractional Exhaled Nitric Oxide and Bronchodilator Drug Response in Moderate-to-Severe Pediatric Asthma.

Asthma is the most prevalent pediatric chronic disease. Bronchodilator drug response (BDR) and fractional exhaled nitric oxide (FeNO) are clinical biomarkers of asthma. Although DNA methylation (DNAm) contributes to asthma pathogenesis, the influence of DNAm on BDR and FeNO is scarcely investigated. This study aims to identify DNAm markers in whole blood associated either with BDR or FeNO in pediatric asthma. We analyzed 121 samples from children with moderate-to-severe asthma. The association of genome-wide DNAm with BDR and FeNO has been assessed using regression models, adjusting for age, sex, ancestry, and tissue heterogeneity. Cross-tissue validation was assessed in 50 nasal samples. Differentially methylated regions (DMRs) and enrichment in traits and biological pathways were assessed. A false discovery rate (FDR) < 0.1 and a genome-wide significance threshold of p < 9 × 10-8 were used to control for false-positive results. The CpG cg12835256 (PLA2G12A) was genome-wide associated with FeNO in blood samples (coefficient= -0.015, p = 2.53 × 10-9) and nominally associated in nasal samples (coefficient = -0.015, p = 0.045). Additionally, three CpGs were suggestively associated with BDR (FDR < 0.1). We identified 12 and four DMRs associated with FeNO and BDR (FDR < 0.05), respectively. An enrichment in allergic and inflammatory processes, smoking, and aging was observed. We reported novel associations of DNAm markers associated with BDR and FeNO enriched in asthma-related processes.

Genetic variants in Protocadherin-1, bronchial hyper-responsiveness, and asthma subphenotypes in German children.

BACKGROUND: Recently, Protocadherin-1 (PCDH1) was reported as a novel susceptibility gene for bronchial hyper-responsiveness (BHR) and asthma. PCDH1 is located on chromosome 5q31-33, in the vicinity of several known candidate genes for asthma and allergy. To exclude that the associations observed for PCDH1 originate from the nearby cytokine cluster, an extensive linkage disequilibrium (LD) analysis was performed. Effects of polymorphisms in PCDH1 on asthma, BHR, and related phenotypes were studied comprehensively. METHODS: Genotype information was acquired from Illumina HumanHap300Chip genotyping, MALDI-TOF MS genotyping, and imputation. LD was assessed by Haploview 4.2 software. Associations were investigated in a population of 1454 individuals (763 asthmatics) from two German study populations [MAGICS and International Study of Asthma and Allergies in Childhood phase II (ISAAC II)] using logistic regression to model additive effects. RESULTS: No relevant LD between PCDH1 tagging polymorphisms and 98 single nucleotide polymorphisms within the cytokine cluster was detected. While BHR was not associated with PCDH1 polymorphisms, significant associations with subphenotypes of asthma were observed. CONCLUSION: Protocadherin-1 polymorphisms may specifically affect the development of non-atopic asthma in children. Functional studies are needed to further investigate the role of PCDH1 in BHR and asthma development.

Vaginal Delivery Is Associated with Neurochemical Evidence of Increased Neuroaxonal Remodelling in Infants from the KUNO-Kids Health Study: Cross-Sectional Analysis.

AIM: Little is known about neonatal brain plasticity or the impact of birth mode on neurointegrity. As a reflection of neuroaxonal damage, the neuronal structural protein neurofilament light chain (NfL) has emerged as a highly specific biomarker. Our purpose was to test the hypothesis that vaginal delivery is associated with increased NfL in neonates. METHODS: NfL concentrations were measured using single-molecule array immunoassay in umbilical cord serum from healthy term neonates enrolled in the prospective KUNO-Kids Health Study. NfL values were investigated for independent influencing factors using linear and logistic models, followed by post hoc propensity score-matching. RESULTS: Of 665 neonates, n = 470 (70.7%) were delivered vaginally and n = 195 (29.3%) by cesarean section. Median serum NfL was significantly higher after vaginal delivery 14.4 pg/mL (11.6-18.5) compared to primary 7.5 pg/mL (6.1-8.9) and secondary cesarean delivery 9.3 pg/mL (7.5-12.0). Multivariable logistic regression models showed delivery mode and gestational age to be independently associated with NfL. Propensity score-matching analysis confirmed that assisted vaginal delivery generated higher NfL compared to vaginal (non-assisted), while lowest levels were associated with cesarean section. INTERPRETATION: Our data confirm the significant impact of birth mode on neonatal NfL levels. The persistence of these differences and their potential long-term impact have yet to be investigated.

Serum neurofilament light chain (sNfL) values in a large cross-sectional population of children with asymptomatic to moderate COVID-19.

BACKGROUND: Serum neurofilament light chain (sNfL) is an established biomarker of neuro-axonal damage in multiple neurological disorders. Raised sNfL levels have been reported in adults infected with pandemic coronavirus disease 2019 (COVID-19). Levels in children infected with COVID-19 have not as yet been reported. OBJECTIVE: To evaluate whether sNfL is elevated in children contracting COVID-19. METHODS: Between May 22 and July 22, 2020, a network of outpatient pediatricians in Bavaria, Germany, the Coronavirus antibody screening in children from Bavaria study network (CoKiBa), recruited healthy children into a cross-sectional study from two sources: an ongoing prevention program for 1-14 years, and referrals of 1-17 years consulting a pediatrician for possible infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). We determined sNfL levels by single molecule array immunoassay and SARS-CoV-2 antibody status by two independent quantitative methods. RESULTS: Of the 2652 included children, 148 (5.6%) were SARS-CoV-2 antibody positive with asymptomatic to moderate COVID-19 infection. Neurological symptoms-headache, dizziness, muscle aches, or loss of smell and taste-were present in 47/148 cases (31.8%). Mean sNfL levels were 5.5 pg/ml (SD 2.9) in the total cohort, 5.1 (SD 2.1) pg/ml in the children with SARS-CoV-2 antibodies, and 5.5 (SD 3.0) pg/ml in those without. Multivariate regression analysis revealed age-but neither antibody status, antibody levels, nor clinical severity-as an independent predictor of sNfL. Follow-up of children with pediatric multisystem inflammatory syndrome (n = 14) showed no association with sNfL. CONCLUSIONS: In this population study, children with asymptomatic to moderate COVID-19 showed no neurochemical evidence of neuronal damage.

Human ß-Defensin 2 Mutations Are Associated With Asthma and Atopy in Children and Its Application Prevents Atopic Asthma in a Mouse Model.

Asthma and allergies are complex, chronic inflammatory diseases in which genetic and environmental factors are crucial. Protection against asthma and allergy development in the context of farming environment is established by early animal contact, unpasteurized milk consumption and gut microbiota maturation. The human ß-defensin 2 (hBD-2) is a host defense peptide present almost exclusively in epithelial tissues, with pronounced immunomodulatory properties, which has recently been shown to ameliorate asthma and IBD in animal models. We hypothesized that adequate hBD-2 secretion plays a role in the protection against asthma and allergy development and that genetic variations in the complex gene locus coding for hBD-2 may be a risk factor for developing these diseases, if as a consequence, hBD-2 is insufficiently produced. We used MALDI-TOF MS genotyping, sequencing and a RFLP assay to study the genetic variation including mutations, polymorphisms and copy number variations in the locus harboring both genes coding for hBD-2 (DEFB4A and DEFB4B). We administered hBD-2 orally in a mouse model of house dust mite (HDM)-asthma before allergy challenge to explore its prophylactic potential, thereby mimicking a protective farm effect. Despite the high complexity of the region harboring DEFB4A and DEFB4B we identified numerous genetic variants to be associated with asthma and allergy in the GABRIELA Ulm population of 1,238 children living in rural areas, including rare mutations, polymorphisms and a lack of the DEFB4A. Furthermore, we found that prophylactic oral administration of hBD-2 significantly curbed lung resistance and pulmonary inflammation in our HDM mouse model. These data indicate that inadequate genetic capacity for hBD-2 is associated with increased asthma and allergy risk while adequate and early hBD-2 administration (in a mouse model) prevents atopic asthma. This suggests that hBD-2 could be involved in the protective farm effect and may be an excellent candidate to confer protection against asthma development.

A System Pharmacology Multi-Omics Approach toward Uncontrolled Pediatric Asthma.

There is a clinical need to identify children with poor asthma control as early as possible, to optimize treatment and/or to find therapeutic alternatives. Here, we present the "Systems Pharmacology Approach to Uncontrolled Pediatric Asthma" (SysPharmPediA) study, which aims to establish a pediatric cohort of moderate-to-severe uncontrolled and controlled patients with asthma, to investigate pathophysiological mechanisms underlying uncontrolled moderate-to-severe asthma in children on maintenance treatment, using a multi-omics systems medicine approach. In this multicenter observational case-control study, moderate-to-severe asthmatic children (age; 6-17 years) were included from four European countries (Netherlands, Germany, Spain, and Slovenia). Subjects were classified based on asthma control and number of exacerbations. Demographics, current and past patient/family history, and clinical characteristics were collected. In addition, systems-wide omics layers, including epi(genomics), transcriptomics, microbiome, proteomics, and metabolomics were evaluated from multiple samples. In all, 145 children were included in this cohort, 91 with uncontrolled (median age = 12 years, 43% females) and 54 with controlled asthma (median age = 11.7 years, 37% females). The two groups did not show statistically significant differences in age, sex, and body mass index z-score distribution. Comprehensive information and diverse noninvasive biosampling procedures for various omics analyses will provide the opportunity to delineate underlying pathophysiological mechanisms of moderate-to-severe uncontrolled pediatric asthma. This eventually might reveal novel biomarkers, which could potentially be used for noninvasive personalized diagnostics and/or treatment.

Symptoms, SARS-CoV-2 Antibodies, and Neutralization Capacity in a Cross Sectional-Population of German Children.

Background: Children and youth are affected rather mildly in the acute phase of COVID-19 and thus, SARS-CoV-2 infection infection may easily be overlooked. In the light of current discussions on the vaccinations of children it seems necessary to better identify children who are immune against SARS-CoV-2 due to a previous infection and to better understand COVID-19 related immune reactions in children. Methods: In a cross-sectional design, children aged 1-17 were recruited through primary care pediatricians for the study (a) randomly, if they had an appointment for a regular health check-up or (b) if parents and children volunteered and actively wanted to participate in the study. Symptoms were recorded and two antibody tests were performed in parallel directed against S (in house test) and N (Roche Elecsys) viral proteins. In children with antibody response in either test, neutralization activity was determined. Results: We identified antibodies against SARS-CoV-2 in 162 of 2,832 eligible children (5.7%) between end of May and end of July 2020 in three, in part strongly affected regions of Bavaria in the first wave of the pandemic. Approximately 60% of antibody positive children (n = 97) showed high levels (>97th percentile) of antibodies against N-protein, and for the S-protein, similar results were found. Sufficient neutralizing activity was detected for only 135 antibody positive children (86%), irrespective of age and sex. Initial COVID-19 symptoms were unspecific in children except for the loss of smell and taste and unrelated to antibody responses or neutralization capacity. Approximately 30% of PCR positive children did not show seroconversion in our small subsample in which PCR tests were performed. Conclusions: Symptoms of SARS-CoV-2 infections are unspecific in children and antibody responses show a dichotomous structure with strong responses in many and no detectable antibodies in PCR positive children and missing neutralization activity in a relevant proportion of the young population.

Gingival disease and secretory immunoglobulin a in non-stimulated saliva in children.

AIM: To find the relationship of secretory immunoglobulin A (SIgA) to gingival diseases in childhood and adolescence by quantitative study of these antibodies in non-stimulated saliva. PATIENTS AND METHODS: The survey included 30 somatically healthy children (mean age 15.37 +/- 1.06 yrs) with clinically healthy gingiva and another 30 children (somatically healthy) (mean age 15.07 +/- 0.69 yrs) with manifested plaque-induced gingivitis. The diagnosis of periodontal status was made on the basis of clinical criteria, the oral-hygiene index of Silness & Loe, the papilla bleeding index (PBI) of Saxer & Mulheman and the periodontal screening index for evaluation--Periodontal Screening and Registration (PSR, after ADA--American Dental Association). SIgA in saliva was quantified by ELISA with salivary secretory IgA kit of SalimetricsLLC--USA. RESULTS: In children with gingivitis the mean SIgA was 41.07 +/- 32.14 microg/ml; it was higher in healthy children - 48.3 +/- 32.41 microg/ml. A correlation was found between SIgA and the oral-hygiene index of Silness & Loe, (P < 0.05) and lack of dependence on the degree of gingival bleeding. CONCLUSIONS: SIgA is a factor characterizing the local specific immunity which depends on local antigenic stimuli (plaque biofilm), but it does not affects the gingival pathology directly. SIgA can be considered an important part of an integrated assessment of oral risk environments.

Immune response to SARS-CoV-2 in health care workers following a COVID-19 outbreak: A prospective longitudinal study.

OBJECTIVE: Currently, little is known about the progression of an immune response against SARSCoV- 2 upon infection or sub-infection-exposure over time. We examined the serologic response in healthcare workers up to 12 weeks after a well-documented and contained outbreak and compared results with findings from earlier serologic testing in the same population. METHODS: This study followed 166 health care workers of the University Perinatal Care Center, Regensburg, Germany, for up to 12 weeks. 27 of the subjects had previously tested positive for the presence of SARS-CoV-2 by PCR testing and developed COVID-19. Serologic responses were tested with two independent commercially available test kits. RESULTS: 77.8 % of COVID-19 study subjects developed a specific IgG-response over the course of the 12-week study, while none of the COVID-19 contact groups had a detectable IgG response. Amongst most COVID-19 patients the values of detectable IgG-responses significantly increased over time as confirmed with both tests, while that of positive IgA responses decreased. Between the number of reported symptoms and antibody responses in COVID-19 patients no correlation was found and no new cases of seroconversion were identified in asymptomatic coworkers with negative PCR during the outbreak. CONCLUSIONS: Immune response after COVID-19 increases significantly over time but still approximately 22 % of COVID-19 patients did not mount a measurable serologic immune response within 60 days. Exposed co-workers did not develop any relevant antibody levels at all. We conclude that immunity after infection increases over time, but the antibody response does not develop reliably in all infected people.

KUNO-Kids birth cohort study: rationale, design, and cohort description.

BACKGROUND: Birth cohort studies can contribute substantially to the understanding of health and disease - in childhood and over the life course. The KUNO-Kids birth cohort study was established to investigate various aspects of child health, using novel omics technologies in a systems medicine approach. RESULTS: After 3 years of recruitment, 2515 infants and their families have joined the study. Parents with higher education are overrepresented as in many other birth cohorts and are more likely to complete follow-up assessments via self-report questionnaires. The vast majority of participants consented to clinical examinations of their child and to the non-invasive collection of diverse biosamples, which were processed specifically for their integrated use in omics technology covering genomics, epigenomics, transcriptomics, metabolomics, and microbiome analyses of the skin, oral cavity, and stool. CONCLUSIONS: The data and diverse biomaterial collected in the KUNO-Kids birth cohort study will provide extensive opportunities for investigating child health and its determinants in a holistic approach. The combination of a broad range of research questions in one study will allow for a cost-effective use of biomaterial and omics results and for a comprehensive analysis of biological and social determinants of health and disease. Aiming for low attrition and ensuring participants' long-term commitment will be crucial to fully exploit the potential of the study.