Detection of immunoglobulin isotypes from dried blood spots

Examination of newborn DNA methylation among women with polycystic ovary syndrome/hirsutism

Research suggests that polycystic ovary syndrome (PCOS) traits (e.g., hyperandrogenism) may create a suboptimal intrauterine environment and induce epigenetic modifications. Therefore, we assessed the associations of PCOS traits with neonatal DNA methylation (DNAm) using two independent cohorts. DNAm was measured in both cohorts using the Infinium MethylationEPIC array. Multivariable robust linear regression was used to determine associations of maternal PCOS exposure or preconception testosterone with methylation β-values at each CpG probe and corrected for multiple testing by false-discovery rate (FDR). In the birth cohort, 12% (102/849) had a PCOS diagnosis (8.1% PCOS without hirsutism; 3.9% PCOS with hirsutism). Infants exposed to maternal PCOS with hirsutism compared to no PCOS had differential DNAm at cg02372539 [β(SE): -0.080 (0.010); FDR p = 0.009], cg08471713 [β(SE):0.077 (0.014); FDR p = 0.016] and cg17897916 [β(SE):0.050 (0.009); FDR p = 0.009] with adjustment for maternal characteristics including pre-pregnancy BMI. PCOS with hirsutism was also associated with 8 differentially methylated regions (DMRs). PCOS without hirsutism was not associated with individual CpGs. In an independent preconception cohort, total testosterone concentrations were associated with 3 DMRs but not with individual CpGs, though the top quartile of testosterone compared to the lowest was marginally associated with increased DNAm at cg21472377 near an uncharacterized locus (FDR p = 0.09). Examination of these probes and DMRs indicate they may be under foetal genetic control. Overall, we found several associations among newborns exposed to PCOS, specifically when hirsutism was reported, and among newborns of women with relatively higher testosterone around conception.

Associations of SARS-CoV-2 antibodies with birth outcomes: Results from three urban birth cohorts in the NIH environmental influences on child health outcomes program

Studies suggest perinatal infection with SARS-CoV-2 can induce adverse birth outcomes, but studies published to date have substantial limitations. We therefore conducted an observational study of 211 births occurring between January 2020-September 2021 in three urban cohorts participating in the Environmental Influences on Child Health Outcomes Program. Serology was assessed for IgG, IgM and IgA antibodies to nucleocapsid, S1 spike, S2 spike, and receptor-binding domain. There were no differences in gestational age (GA), birth weight, preterm birth (PTB) or low birth weight (LBW) among seropositive mothers. However, the few (n = 9) IgM seropositive mothers had children with lower BW (434g, 95% CI: 116-752), BW Z score-for-GA (0.73 SD, 95% CI 0.10-1.36) and were more likely to deliver preterm (OR 8.75, 95% CI 1.22-62.4). Though there are limits to interpretation, the data support efforts to prevent SARS-CoV-2 infections in pregnancy.

Epigenetic gestational age and the relationship with developmental milestones in early childhood

Shorter gestational age (GA) is a risk factor of developmental delay. GA is usually estimated clinically from last menstrual period and ultrasound. DNA methylation (DNAm) estimates GA using sets of cytosine-guanine-sites coupled with a clock algorithm. Therefore, DNAm-estimated GA may better reflect biological maturation. A DNAm GA greater than clinical GA, known as gestational age acceleration (GAA), may indicate epigenetic maturity and holds potential as an early biomarker for developmental delay risk. We used data from the Upstate KIDS Study to examine associations of DNAm GA and developmental delay within the first 3 years based on the Ages & Stages Questionnaire® (n = 1010). We estimated DNAm GA using two clocks specific to the Illumina Methylation EPIC 850K, the Haftorn clock and one developed from the Effects of Aspirin in Gestation and Reproduction study, in which women were followed to detect pregnancy at the earliest time possible. Among singletons, each week increase in DNAm GA was protective for overall delay (odds ratio:0.74; 95% confidence interval:0.61-0.90) and delay in all domains except for problem-solving skills. Among twins, we observed similar point estimates but lower precision. Results were similar for clinical GA. GAA was largely not associated with developmental delays. In summary, either DNAm GA or clinical GA at birth, but not epigenetic maturity (i.e. GAA), was associated with decreased odds of developmental delay in early childhood. Our study does not support using DNAm GA or GAA as separate risk factors for future risk of developmental delay within the first 3 years of age.

Effects on neonatal immunoglobulin concentrations by infant mode of delivery in the upstate KIDS study (2008-2010)

PROBLEM

Previous studies document an association between mode of delivery (MOD) and allergic conditions in children. Immunoglobulin (Ig) concentrations at birth may play a role. The goal of this study is to assess the impact of MOD on Ig concentrations at delivery from newborn dried blood spots (DBS).

METHOD OF STUDY

The Upstate KIDS Study (2008-2010) is a prospective cohort of mother-child pairs recruited from New York State, excluding New York City. Ig subtypes IgA, IgE, IgG1 , IgG2 , IgG3 , IgG4 , and IgM were measured in residual NDBS from the Newborn Screening Program (N = 3274 infants). MOD was categorized as vaginal delivery (VD), emergency cesarean delivery (ECD) or planned cesarean delivery (PCD). Associations between MOD and Ig levels were assessed using ANOVA and multiple regression, with models adjusted for gestational age, birth weight, maternal race, plurality, and smoking status.

RESULTS

IgA, and the IgG subtypes IgG3 and IgG4 were found to be significantly lower in PCD neonates relative to VD neonates in adjusted regression models: 3.57 mg/ml, (95% CI: 3.51, 3.63) compared to 3.64 mg/ml (95% CI: 3.59, 3.69); 8.95 ng/ml (95% CI: 8.88,9.03) compared to 9.03 ng/ml (95% CI: 8.98, 9.08) and 8.05 ng/ml (95% CI: 7.91, 8.20) compared to 8.22 ng/ml (95% CI: 7.91,8.20), respectively.

CONCLUSIONS

MOD may thus be related to neonatal immune profile. Results were found to be robust to sensitivity testing based on maternal complications and indication for CD. Clinical implications are unclear given the small levels of association found in newborns, but the result suggests greater susceptibility to infection, and further study is warranted.

Immunoglobulin adsorption and film formation on mechanically wrinkled and crumpled surfaces at submonolayer coverage

Understanding protein adsorption behavior on rough and wrinkled surfaces is vital to applications including biosensors and flexible biomedical devices. Despite this, there is a dearth of study on protein interaction with regularly undulating surface topographies, particularly in regions of negative curvature. Here we report nanoscale adsorption behavior of immunoglobulin M (IgM) and immunoglobulin G (IgG) on wrinkled and crumpled surfaces via atomic force microscopy (AFM). Hydrophilic plasma treated poly(dimethylsiloxane) (PDMS) wrinkles with varying dimensions exhibit higher surface coverage of IgM on wrinkle peaks over valleys. Negative curvature in the valleys is determined to reduce protein surface coverage based both on an increase in geometric hindrance on concave surfaces, and reduced binding energy as calculated in coarse-grained molecular dynamics simulations. The smaller IgG molecule in contrast shows no observable effects on coverage from this degree of curvature. The same wrinkles with an overlayer of monolayer graphene show hydrophobic spreading and network formation, and inhomogeneous coverage across wrinkle peaks and valleys attributed to filament wetting and drying effects in the valleys. Additionally, adsorption onto uniaxial buckle delaminated graphene shows that when wrinkle features are on the length scale of the protein diameter, hydrophobic deformation and spreading do not occur and both IgM and IgG molecules retain their dimensions. These results demonstrate that undulating wrinkled surfaces characteristic of flexible substrates can have significant effects on protein surface distribution with potential implications for design of materials for biological applications.

A Toolkit for Monitoring Immunoglobulin G Levels from Dried Blood Spots of Patients with Primary Immunodeficiencies

PURPOSE

This study assessed whether measuring immunoglobulin G (IgG) from dried blood spots (DBSs) using nephelometry is a suitable remote monitoring method for patients with primary immunodeficiencies (PID).

METHODS

Patients receiving immunoglobulin replacement therapy for PID were included in this non-interventional single-arm study (DRKS-ID: DRKS00020522) conducted in Germany from December 4, 2019, to December 22, 2020. Three blood samples, two capillary DBSs (one mail-transferred and the other direct-transferred to the laboratory), and one intravenous were collected from each patient. IgG levels were determined using nephelometry. IgG levels were summarized descriptively, and significant differences were assessed using Wilcoxon matched-pairs signed-rank tests. Correlation and agreement between IgG levels were assessed using Spearman correlation and Bland-Altman analyses, respectively.

RESULTS

Among 135 included patients, IgG levels measured from DBS samples were lower than those measured in serum (p < 0.0001). There was no significant difference between IgG levels in direct- and mail-transferred DBS samples. There was a high degree of correlation between IgG levels in serum samples and DBS samples (r = 0.94-0.95). Although there was a bias for higher levels of IgG in serum than in DBS samples, most samples were within the 95% interval of agreement. There was a high degree of correlation between IgG levels measured in direct- and mail-transferred DBS samples (r = 0.96) with no bias based on the shipment process and most samples within the 95% interval of agreement.

CONCLUSION

Monitoring IgG levels from DBS samples is a suitable alternative to the standard method, and results are not substantially affected by mailing DBS cards.

Ecoimmunology in the field: Measuring multiple dimensions of immune function with minimally invasive, field-adapted techniques

OBJECTIVE

Immune function is multifaceted and characterizations based on single biomarkers may be uninformative or misleading, particularly when considered across ecological contexts. However, measuring the many facets of immunity in the field can be challenging, since many measures cannot be obtained on-site, necessitating sample preservation and transport. Here we assess state-of-the-art methods for measuring immunity, focusing on measures that require a minimal blood sample obtained from a finger prick, which can be: (1) dried on filter paper, (2) frozen in liquid nitrogen, or (3) stabilized with chemical reagents.

RESULTS

We review immune measures that can be obtained from point-of-care devices or from immunoassays of dried blood spots (DBSs), field methods for flow cytometry, the use of RNA or DNA sequencing and quantification, and the application of immune activation assays under field conditions.

CONCLUSIONS

Stable protein products, such as immunoglobulins and C-reactive protein are reliably measured in DBSs. Because less stable proteins, such as cytokines, may be problematic to measure even in fresh blood, mRNA from stabilized blood may provide a cleaner measure of cytokine and broader immune-related gene expression. Gene methylation assays or mRNA sequencing also allow for the quantification of many other parameters, including the inference of leukocyte subsets, though with less accuracy than with flow cytometry. Combining these techniques provides an improvement over single-marker studies, allowing for a more nuanced understanding of how social and ecological variables are linked to immune measures and disease risk in diverse populations and settings.

Exposure to perfluoroalkyl substances and neonatal immunoglobulin profiles in the upstate KIDS study (2008-2010)

Infant exposure to per/polyfluoroalkyl compounds is associated with immune disruption. We examined associations between neonatal concentrations of perflurooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) and immunoglobulin (Ig) isotype profiles in a prospective cohort of infants. We measured Ig isotypes, including IgA, IgE, IgM and the IgG subclasses IgG1, IgG2, IgG3, and IgG4, and PFOA and PFOS in newborn dried bloodspots from N = 3175 infants in the Upstate KIDS Study (2008-2010). We examined the association between newborn Ig isotype levels and individual PFOS and PFOA concentrations using mixed effects regression models with a random intercept to account for twins among study participants. We assessed the joint effect PFOA and PFOS with quantile-based g-computation on all singletons and one randomly selected twin (N = 2901), with Ig categorized as above or below median value. Models were adjusted for infant sex, and maternal pre-pregnancy body mass index, race, parity, age and infertility treatment. In adjusted models, PFOA was inversely associated with IgE (coefficient = -0.12 per unit increase in PFOA, 95% CI: -0.065, -0.17), whereas IgG2, IgM, and IgA were positively associated with PFOA (coefficient for IgG2 = 0.22, 95% CI: 0.15, 0.27; coefficient for IgM = 0.11, 95% CI: 0.08, 0.15; and coefficient for IgA = 0.15, 95% CI: 0.07, 0.18). There was no relation between PFOS and Ig isotypes. Analysis of the joint effect of PFOA and PFOS showed an OR of 1.2 (95% CI: 1.04, 1.36) for IgA and OR of 1.12 (95% CI: 1.00, 1.24) for IgG2 levels above the median for every quartile increase. PFOA levels were significantly associated with elevated IgA, IgM, IgG2, and reduced levels of IgE in single-pollutant models. A small but significant joint effect of PFOA and PFOS was observed. Our results suggest that early exposure to PFOA and PFOS may disrupt neonatal immunoglobulin levels.

Immunoglobulin G passive transfer from mothers to infants: total IgG, IgG subclasses and specific antipneumococcal IgG in 6-week Malawian infants exposed or unexposed to HIV

Background

The impaired transplacental passage of IgG from mothers living with HIV to their infants could be one of the causes of the high vulnerability to infections of HIV-exposed uninfected (HEU) infants, but controversial results have been obtained in different settings. The aim of this study was to assess in 6-week old HEU and HIV-unexposed, uninfected (HUU) Malawian infants the total IgG levels, the subclasses profile and the concentrations of global anti-pneumococcal capsular polysaccharide (anti-PCP) IgG and IgG2.

Methods

Dried blood spots were collected from 80 infants (40 HEU, 40 HUU) and antibodies concentrations determined by nephelometric method (total IgG and subclasses), or using ELISA (anti-PCP total IgG and IgG2). Results are expressed as median levels with IQR, while the proportions of each subclass out of the total IgG are used to describe the subclasses profile.

Results

At 6 weeks HEU infants had higher median levels of total IgG and IgG1 and a significantly lower level of IgG2 [0.376 (0.344–0.523) g/l vs 0.485 (0.374–0.781) g/l, p = 0.037] compared to the HUU counterparts. The IgG subclasses distribution confirmed the underrepresentation of IgG2 (IgG2 represented 5.82% of total IgG in HEU and 8.87% in HUU). The anti-PCP IgG and IgG2 levels were significantly lower in HEU infants [8.9 (5.4–15.1) mg/l vs 16.2 (9.61–25.8) mg/l in HUU, p < 0.001, and 2.69 (1.90–4.29) mg/l vs 4.47 (2.96–5.71) mg/l in HUU, p = 0.001, respectively].

Conclusion

Compared to HUU infants, HEU infants have IgG abnormalities mainly represented by low IgG2 levels, suggesting that despite maternal antiretroviral therapy, the mechanisms of IgG transplacental passage continue to be impaired in women living with HIV. HEU infants also showed a significantly lower level of specific anti-PCP IgG, possibly favouring a high vulnerability to S. pneumoniae infection at an age when protection is mostly depending on maternal IgG.

Conception by fertility treatment and offspring deoxyribonucleic acid methylation

OBJECTIVE

To investigate whether deoxyribonucleic acid (DNA) methylation at birth and in childhood differ by conception using assisted reproductive technologies (ART) or ovulation induction compared with those in children conceived without fertility treatment.

DESIGN

Upstate KIDS is a matched exposure cohort which oversampled on newborns conceived by treatment.

SETTING

New York State (excluding New York City).

PATIENT(S)

This analysis included 855 newborns and 152 children at approximately 9 years of age.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

DNA methylation levels were measured using the Illumina EPIC platform. Single CpG and regional analyses at imprinting genes were conducted.

RESULT(S)

Compared to no fertility treatment, ART was associated with lower mean DNA methylation levels at birth in 11 CpGs (located in/near SYCE1, SPRN, KIAA2013, MYO1D, GET1/WRB-SH4BGR, IGF1R, SORD, NECAB3/ACTL10, and GET1) and higher mean methylation level in 1 CpG (KLK4; all false discovery rate P<.05). The strongest association (cg17676129) was located at SYCE1, which codes for a synaptonemal complex that plays a role in meiosis and therefore infertility. This CpG remained associated with newborn hypomethylation when the analysis was limited to those conceived with ICSI, but this may be because of underlying male infertility. In addition, nine regions in maternally imprinted genes (IGF1R, PPIEL, SVOPL GNAS, L3MBTL, BLCAP, HYMAI/PLAGL1, SNU13, and MEST) were observed to have decreased mean DNA methylation levels among newborns conceived by ART. In childhood, hypomethylation of the maternally imprinted gene, GNAS, persisted. No CpGs or regions were associated with ovulation induction.

CONCLUSION(S)

ART but not ovulation induction was associated with hypomethylation at birth, but only one difference at an imprinting region appeared to persist in childhood.

Microsampling: A role to play in Covid-19 diagnosis, surveillance, treatment and clinical trials

The outbreak of the new coronavirus disease changed the world upside down. Every day, millions of people were subjected to diagnostic testing for Covid-19, all over the world. Molecular tests helped in the diagnosis of current infection by detecting the presence of viral genome whereas serological tests helped in detecting the presence of antibody in blood as well as contributed to vaccine development. This testing helped in understanding the immunogenicity, community prevalence, geographical spread and conditions post-infection. However, with the contagious nature of the virus, biological specimen sampling involved the risk of transmission and spread of infection. Clinic or pathology visit was the most concerning part. Trained personnel and resources was another barrier. In this scenario, microsampling played an important role due to its most important advantage of remote, contactless, small volume and self-sampling. Minimum requirements for sample storage and ease of shipment added value in this situation. The highly sensitive instruments and validated assay formats assured the accuracy of results and stability of samples. Microsampling techniques are contributing effectively to the Covid-19 pandemic by reducing the demand for clinical staff in population-level testing. The validated and established applications supported the use of microsampling in diagnosis, therapeutic drug monitoring, development of treatment or vaccines and clinical trials for Covid-19.

Dried blood spots for the quantitative evaluation of IgG isotypes and correlation with serum samples in HIV-exposed uninfected (HEU) infants

BACKGROUND

The determination of IgG levels and their subclasses can provide clinically relevant information on the status of the immune system. Here we determined the sensitivity and reproducibility of the quantification of IgG subclasses from Dried Blood Spots (DBS) in Malawian uninfected infants exposed to HIV (HEU).

METHODS

Sixty paired samples of serum and DBS from HEU infants were used. Samples were collected from 1, 6, and 24-month old infants. IgGs concentrations from both serum and DBS were analyzed by BN ProSpec Siemens assay, using a different setting for sample dilutions. The reproducibility of the DBS method was tested on 10 samples run twice, starting from the DBS extraction process. To assess the systematic, proportional, and random differences, we computed the Passing-Bablok regression, and the Bland-Altman analysis to estimate the total mean bias between the two tests.

RESULTS

The IgG isotypes concentrations from serum and DBS showed significant differences in all the comparisons. Generally, the DBS method underestimated IgG subclasses' values showing a recovery range between 51.2% and 77.6%. Passing Bablok regression on age-based groups showed agreement for IgG, IgG1, and IgG2, but not for IgG3 and IgG4. The mean bias obtained with the Bland Altman test varied largely depending on IgG isotypes (-0.02-2.21 g/l) Coefficient of variation <7.0% was found in the repeated tests for IgG, IgG1, IgG3, and IgG4, while it was 12.4% for IgG2.

CONCLUSIONS

Varying degrees of differences were seen in the IgGs measurement in the two different matrices. In IgGs analysis, the DBS method offers promise for population-based research, but the results should be carefully evaluated and considered as a relative value since they are not equivalent to the serum concentrations.

Adaptation of Elecsys® anti-severe acute respiratory syndrome coronavirus-2 immunoassay to dried blood spots: proof of concept

Aim: Several automated immunoassays have been validated on serum/plasma to evaluate the presence of significant levels of anti-severe acute respiratory syndrome coronavirus 2 (anti-SARS-CoV-2) antibodies, signs of a present or past infection, but the use of dried blood spots (DBS) would facilitate sampling, shipping and storage. Objective: The aim of this project was to give proof of concept of the possibility to use of the automatized Elecsys^® anti-SARS-CoV-2 immunoassay with a volumetric DBS device. Results: Linearity and correlation were satisfactory between volumetric DBS and plasma. A cut-off value was suggested and should be validated with more samples. Conclusion: this study strongly support the possibility to work with volumetric DBS instead of serum/plasma to test for anti-SARS-CoV-2 antibodies.

Evaluation of Circulating Cardiovascular Biomarker Levels for Early Detection of Congenital Heart Disease in Newborns in Sweden

IMPORTANCE

Congenital heart disease (CHD) is the most common congenital malformation in humans worldwide. Circulating cardiovascular biomarkers could potentially improve the early detection of CHD, even in asymptomatic newborns.

OBJECTIVES

To assess the performance of a dried blood spot (DBS) test to measure the cardiovascular biomarker amino terminal fragment of the prohormone brain-type natriuretic peptide (NT-proBNP) levels in newborns and to compare DBS with standard EDTA analysis in control newborns during the first week of life.

DESIGN, SETTING, AND PARTICIPANTS

This diagnostic study was conducted in a single regional pediatric service in southern Sweden. Healthy, term neonates born between July 1, 2018, and May 31, 2019, were prospectively enrolled and compared against retrospectively identified newborns with CHD born between September 1, 2003, and September 30, 2019. Neonates who required inpatient treatment beyond the standard postnatal care were excluded.

EXPOSURE

New DBS test for NT-proBNP quantification in newborns that used 3 μL of blood vs the current screening standard.

MAIN OUTCOMES AND MEASURES

Performance of the new test and when combined with pulse oximetry screening was measured by receiver operating characteristic curve analysis. Performance of the new test and EDTA screening was compared using Pearson linear correlation analysis.

RESULTS

The DBS samples of 115 neonates (81 control newborns and 34 newborns with CHD, of whom 63 were boys [55%] and the mean [SD] gestational age was 39.6 [1.4] weeks) were analyzed. The new NT-proBNP test alone identified 71% (n = 24 of 34) of all CHD cases and 68% (n = 13 of 19) of critical CHD cases as soon as 2 days after birth. Detection of any CHD type improved to 82% (n = 28 of 34 newborns) and detection of critical CHD improved to 89% (n = 17 of 19 newborns) when combined pulse oximetry screening and NT-proBNP test results were used. Performance of the NT-proBNP test was excellent when control newborns were matched to newborns with CHD born between July 1, 2018, and May 31, 2019 (area under the curve, 0.96; SE, 0.027; 95% CI, 0.908-1.0; asymptotic P < .05).

CONCLUSIONS AND RELEVANCE

This study found that NT-proBNP assay using minimal DBS samples appears to be timely and accurate in detecting CHD in newborns and to discriminate well between healthy newborns and newborns with various types of CHD. This finding warrants further studies in larger cohorts and highlights the potential of NT-proBNP to improve neonatal CHD screening.

Dengue in Western Uganda: a prospective cohort of children presenting with undifferentiated febrile illness

BACKGROUND

The spatial distribution and burden of dengue in sub-Saharan Africa remains highly uncertain, despite high levels of ecological suitability. The goal of this study was to describe the epidemiology of dengue among a cohort of febrile children presenting to outpatient facilities located in areas of western Uganda with differing levels of urbanicity and malaria transmission intensity.

METHODS

Eligible children were first screened for malaria using rapid diagnostic tests. Children with a negative malaria result were tested for dengue using a combination NS1/IgM/IgG rapid test (SD Bioline Dengue Duo). Confirmatory testing by RT-PCR was performed in a subset of participants. Antigen-capture ELISA was performed to estimate seroprevalence.

RESULTS

Only 6 of 1416 (0.42%) children had a positive dengue rapid test, while none of the RT-PCR results were positive. ELISA testing demonstrated reactive IgG antibodies in 28 (2.2%) participants with the highest prevalence seen at the urban site in Mbarara (19 of 392, 4.9%, p < 0.001).

CONCLUSIONS

Overall, these findings suggest that dengue, while present, is an uncommon cause of non-malarial, pediatric febrile illness in western Uganda. Further investigation into the eocological factors that sustain low-level transmission in urban settings are urgently needed to reduce the risk of epidemics.

Dried Blood Spot in Laboratory: Directions and Prospects

Over the past few years, dried blood spot (DBS) technology has become a convenient tool in both qualitative and quantitative biological analysis. DBS technology consists of a membrane carrier (MC) on the surface of which a biomaterial sample becomes absorbed. Modern analytical, immunological or genomic methods can be employed for analysis after drying the sample. DBS has been described as the most appropriate method for biomaterial sampling due to specific associated inherent advantages, including the small volumes of biomaterials required, the absence of a need for special conditions for samples’ storage and transportation, improved stability of analytes and reduced risk of infection resulting from contaminated samples. This review illustrates information on the current state of DBS technology, which can be useful and helpful for biomedical researchers. The prospects of using this technology to assess the metabolomic profile, assessment, diagnosis of communicable diseases are demonstrated.

Serologic Tools and Strategies to Support Intervention Trials to Combat Zika Virus Infection and Disease

Zika virus is an emerging mosquito-borne flavivirus that recently caused a large epidemic in Latin America characterized by novel disease phenotypes, including Guillain-Barré syndrome, sexual transmission, and congenital anomalies, such as microcephaly. This epidemic, which was declared an international public health emergency by the World Health Organization, has highlighted shortcomings in our current understanding of, and preparation for, emerging infectious diseases in general, as well as challenges that are specific to Zika virus infection. Vaccine development for Zika virus has been a high priority of the public health response, and several candidates have shown promise in pre-clinical and early phase clinical trials. The optimal selection and implementation of imperfect serologic assays are among the crucial issues that must be addressed in order to advance Zika vaccine development. Here, I review key considerations for how best to incorporate into Zika vaccine trials the existing serologic tools, as well as those on the horizon. Beyond that, this discussion is relevant to other intervention strategies to combat Zika and likely other emerging infectious diseases.

Concentrations of endocrine disrupting chemicals in newborn blood spots and infant outcomes in the upstate KIDS study

BACKGROUND

Novel methodologies to quantify infant exposures to endocrine disrupting chemicals (EDCs) for population-based studies are needed.

OBJECTIVES

We used newborn dried blood spots to quantify three EDCs and their associations with infant outcomes in the Upstate KIDS Cohort.

METHODS

We measured bisphenol A (BPA), perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) in 2071 singleton and 1040 twin infants born to mothers in New York State. We log transformed concentrations after rescaling by their standard deviations and modeled each in relation to gestational age, birthweight, length, head circumference and Ponderal Index (PI) using linear regression techniques. All models were adjusted for maternal age, body mass index, education, infertility treatment and parity. Generalized estimating equations with robust standard errors were used to assess the associations for twins.

RESULTS

Chemicals were largely quantified above the limits of detection (>99% for PFOS and PFOA; 90% for BPA). Overall, we observed no significant associations between PFASs and birth size irrespective of plurality of birth. However, among twins, BPA was associated with decreases in gestational age (adjusted β = -0.09 weeks; 95% Confidence Interval (CI): -0.16, -0.02) and birthweight (adjusted β = -32.52 g; 95% CI: -60.99, -4.05), head circumference (adjusted β = -0.18 cm; 95% CI: -0.38, -0.02) and increased PI in singletons (adjusted β = 0.02 cm; 95% CI: 0.004, 0.04).

CONCLUSION

We observed negative associations between BPA and birth size in twins. Our findings demonstrate the feasibility of newborn dried blood spots for quantifying neonatal exposure at the population level.

Multiplex Assay for Quantification of Acute Phase Proteins and Immunoglobulin A in Dried Blood Spots

Inflammation is the first line defense mechanism against infection, tissue damage, or cancer development. However, inappropriate inflammatory response may also trigger diseases. The quantification of inflammatory proteins is essential to distinguish between harmful and beneficial immune response. Currently used immunoanalytical assays may suffer specificity issues due to antigen-antibody interaction and possible cross-reactivity of antibody with other protein species. In addition, immunoanalytical assays typically require invasive blood sampling and additional logistics; they are relatively costly and highly challenging to multiplex. We present a multiplex assay based on selected reaction monitoring (SRM) for quantification of seven acute-phase proteins (i.e., SAA1, SAA2-isoform1, SAA4, CRP, A1AT-isoform1, A1AG1, A1AG2) and the adaptive immunity effector IGHA1 in dried blood spots. This type of sample is readily available from all human subjects including newborns. The study utilizes proteotypic isotopically labeled peptides with trypsin-cleavable tag and presents optimized and reproducible workflow and several important practical remarks regarding quantitative SRM assays development. The panel of inflammatory proteins was quantified with sequence specificity capable to differentiate protein isoforms with intra- and interday precision (<16.4% coefficient of variation (CV) and <14.3% CV, respectively). Quantitative results were correlated with immuno-nephelometric assay (typically greater than 0.9 Pearson's R).

Newborn adipokines and early childhood growth

BACKGROUND

While adipokines can regulate satiety and energy metabolism, whether they are associated with childhood growth is unclear.

OBJECTIVE

To evaluate whether adipokine levels at birth are associated with growth.

METHODS

A total of 2264 singletons and 1144 twins from Upstate KIDS (born 2008-2010) had adiponectin, leptin, resistin and complement factor D measured in newborn blood spots. Parents reported anthropometry from paediatric visits via questionnaires every 4-6 months. Generalized linear mixed effects models were used to estimate growth trajectories through 3 years of age.

RESULTS

Among singletons, resistin and leptin were associated with greater weight-for-age (0.12 z-score units (95%CI: 0.04, 0.20) [p = 0.003] and 0.15 (0.06, 0.24) [p = 0.001], respectively) and BMI z-score (0.11; 0.02, 0.20 [p = 0.02] and 0.18; 0.07, 0.28 [p = 0.002], respectively). After adjusting for birthweight, resistin and a ratio of resistin-to-adiponectin remained associated with weight through 3 years of age and odds of being overweight at 3 years of age in a subgroup of singletons. Among twins, adiponectin was associated with increased weight-for-age and length-for-age z-scores even after adjusting for birthweight (0.18; 0.08, 0.28 [p = 0.0006]; 0.20; 0.07, 0.33 [p = 0.003], respectively).

CONCLUSIONS

Levels of adipokines were associated with early childhood growth in small magnitudes. Resistin may be relevant for further examination in paediatric obesity.

Maternal Smoking and Newborn Cytokine and Immunoglobulin Levels

INTRODUCTION

Prenatal smoking exposure may lead to permanent changes in neonatal inflammation and immune response that have lifelong implications, including increased risks for atopy and respiratory disorders.

METHODS

The effect of maternal smoking on neonatal biomarkers of inflammation and immune response was assessed among 3459 singletons and twins in the Upstate KIDS Study. The following inflammatory biomarkers were measured using newborn dried blood spots (DBSs): interleukin (IL)-1α, IL-1 receptor antagonist, IL-6, IL-8, C-reactive protein, and tumor necrosis factor alpha. Immunoglobulins (IgE, IgA, IgM, and IgG subclasses) were also assessed. We used generalized estimating equations to calculate mean differences (β) in biomarker levels by timing of pregnancy smoking, cigarette load, and secondhand smoke exposure after adjusting for sociodemographic and lifestyle factors including maternal body mass index.

RESULTS

Of the 344 (12%) women reporting smoking during pregnancy, about 40% continued throughout pregnancy and 13% reported smoking more than 1 pack per day. After covariate adjustment and Bonferroni correction for multiple comparisons, maternal smoking throughout pregnancy remained significantly associated with increased levels of IL-8 (β = 0.20, 95% confidence interval: 0.07, 0.32; p < .003). No significant associations were found with cigarette load or secondhand smoke exposure. Higher IgG3 levels were also associated with maternal smoking throughout pregnancy, although the association became nominally significant after adjustment for covariates (β = 0.09; 95% confidence interval: 0.0007, 0.17; p < .05).

CONCLUSIONS

Maternal smoking throughout pregnancy was independently associated with increased IL-8 levels in newborns. Importantly, neonates of women who stopped smoking anytime in pregnancy did not have increased IL-8 levels.

IMPLICATIONS

This study evaluated a range of inflammatory biomarkers and immunoglobulins in association with maternal smoking and timing/duration of smoking along with secondhand smoke exposure. By using DBSs, we present data from a large cohort of children born in Upstate New York. Our findings suggest that early differences in immunoregulation of neonates exposed to maternal smoking for full duration in utero may already be detected at birth.

Impact of parental obesity on neonatal markers of inflammation and immune response

Background/Objectives

Maternal obesity may influence neonatal and childhood morbidities through increased inflammation and/or altered immune response. Less is known about paternal obesity. We hypothesized that excessive parental weight contributes to elevated inflammation and altered immunoglobulin (Ig) profiles in neonates.

Subjects/Methods

In the Upstate KIDS Study maternal pre-pregnancy body mass index (BMI) was obtained from vital records and paternal BMI from maternal report. Biomarkers were measured from newborn dried blood spots (DBS) among neonates whose parents provided consent. Inflammatory scores were calculated by assigning one point for each of 5 pro-inflammatory biomarkers above the median and one point for an anti-inflammatory cytokine below the median. Linear regression models and generalized estimating equations were used to estimate mean differences (β) and 95% confidence intervals (CI) in the inflammatory score and Ig levels by parental overweight/obesity status compared to normal weight.

Results

Among 2974 pregnancies, 51% were complicated by excessive maternal weight (BMI>25), 73% by excessive paternal weight, and 28% by excessive gestational weight gain. Maternal BMI categories of overweight (BMI 25.0-29.9) and obese class II/III (BMI≥35) were associated with increased neonatal inflammation scores (β=0.12, 95% CI: 0.02, 0.21; p=0.02, and β=0.13, CI: −0.002, 0.26; p=0.05, respectively) but no increase was observed in the obese class I group (BMI 30-34.9). Mothers with class I and class II/III obesity had newborns with increased IgM levels (β=0.11, CI: 0.04, 0.17; p=0.001 and β=0.12, CI: 0.05, 0.19); p<0.001, respectively). Paternal groups of overweight, obese class I and obese class II/III had decreased neonatal IgM levels (β=−0.08, CI: −0.13,-0.03, p=0.001; β=−0.07, CI: −0.13, −0.01, p=0.029 and β=−0.11, CI:−0.19,-0.04, p=0.003, respectively).

Conclusions

Excessive maternal weight was generally associated with increased inflammation and IgM supporting previous observations of maternal obesity and immune dysregulation in offspring. The role of paternal obesity requires further study.

Determination of Recent Growth Hormone Abuse Using a Single Dried Blood Spot

BACKGROUND

Although it is being increasingly applied, blood collection for drug testing in sport presents some logistic issues that complicate full applicability on a large scale. The use of dried blood spots (DBS) could benefit compliant blood testing considerably owing to its simplicity, minimal invasiveness, analyte stability, and reduced costs. The aim of this study was to evaluate the applicability of DBS to the methodology approved by the World Anti-Doping Agency (WADA) for detection of doping by recombinant human growth hormone (rhGH) in serum.

METHODS

A protocol for a single DBS analysis using the hGH isoforms differential immunoassays (kit 1 and kit 2) was developed and validated. A clinical study with healthy volunteers injected for 3 consecutive days with a low subcutaneous dose (0.027 mg · kg−1 · day−1 · person−1) of rhGH was conducted. Finger prick DBS and paired-time serum samples from arm venipuncture were compared.

RESULTS

The analysis of the DBS-based protocol indicated that with only a single blood spot it was possible to detect positivity for growth hormone abuse. In spite of the low rhGH dose administered and independently of the kit used, the window of detection for DBS was confirmed in all analyzed samples up to 8 h after rhGH administration and extended up to 12 h in 50% of the cases. Serum positivity was detected in all studied samples for 12 h after administration.

CONCLUSIONS

These results support the usefulness of DBS as a biological matrix for testing recent growth hormone abuse.

Immunoglobulin Concentrations in Plasma and Saliva During the Neonatal Period

BACKGROUND

Screening for infectious diseases in newborns using immunoglobulin (Ig)A-, IgM-, and IgE-specific antibodies is expensive and impractical. To determine if total levels of these Igs can be used for screening purposes, thus simplifying the process, their basic levels in the 1(st) month of extrauterine life need to be determined. Additionally, the ability to simplify screening by using saliva also needs to be determined. The aim of this study was to determine IgA, IgM, and IgE concentrations in plasma and saliva in newborns, correlation between the samples, and relationship between Ig levels and newborn age.

METHODS

We enrolled 53 apparently healthy newborns, paired samples of plasma and saliva were collected, and total IgA, IgM, and IgE concentrations determined by capture enzyme-linked immunosorbent assay. The correlation between plasma and saliva values was calculated by Spearman's rank correlation coefficient and the IgA, IgM, and IgE distributions were analyzed by the Shapiro-Wilk test. We also determined the level of each Ig concentration according to age.

RESULTS

IgA and IgM levels in plasma and IgA levels in saliva increased significantly during 1(st) month of life, especially in the 2(nd) week and 3(rd) week, with a good correlation of IgA between plasma and saliva. IgE levels in both plasma and saliva and IgM levels in saliva were very low or absent.

CONCLUSION

These results suggest that Igs in saliva could be good biomarkers for newborn screening programs during the 1(st) week of life. This study established reference values for Igs according to age in the neonatal period.

Eliciting parental support for the use of newborn blood spots for pediatric research

Background

Biomarkers of exposures such as infection or environmental chemicals can be measured in small volumes of blood extracted from newborn dried blood spots (DBS) underscoring their potential utility for population-based research. However, few studies have evaluated the feasibility and utility of this resource; particularly the factors associated with parental consent, and the ability to retrieve banked samples with sufficient remaining volume for epidemiologic research.

Methods

At 8 months postpartum, 5,034 mothers of infants born (2008–2010) in New York (57 counties excluding New York City) were asked to consent for the use of residual DBS for the quantification of cytokines and environmental chemicals. Mothers were part of the Upstate KIDS study, a longitudinal birth cohort designed to evaluate child development through 3 years of age. Information on parental and infant characteristics was obtained from birth certificates and maternal report at 4 months postpartum. Multivariate logistic regression was used to identify factors associated with parental consent and with successful retrieval of DBS.

Results

Sixty-two percent (n = 3125) of parents consented. Factors significantly associated with consent included non-Hispanic ethnicity (odds ratio 2.04; 95 % CI: 1.43–2.94), parity (1.29; 1.05–1.57), maternal obesity (1.42; 1.11–1.80) and reported alcohol use during pregnancy (1.51; 1.12–2.06). However, these associations corresponded to small absolute differences in proportions (4 to 8 %), suggesting that the two groups remained comparable. Infant characteristics such as preterm delivery did not significantly differ by consent status among singletons and only ventilator use (OR 2.39; 95 % CI: 1.06–5.41) remained borderline significant among twins in adjusted analyses. Among consented infants, 99 % had at least one 3.2 mm punch successfully retrieved for biomarker analyses and 84 % had a full DBS circle available.

Conclusion

Parental characteristics varied slightly by consent, and the availability of samples for research purposes was high, demonstrating the feasibility of this resource for population based research.

Multiplex immunoassay for in vitro characterization of acellular pertussis antigens in combination vaccines

Vaccines characterization is required to ensure physical, chemical, and biological integrity of antigens and adjuvants. Current analytical methods mostly require complete antigen desorption from aluminum-based adjuvants and are not always suitable to distinguish individual antigens in multivalent formulations. Here, Luminex technology is proposed to improve the analytics of vaccine characterization. As proof of concept, TdaP (tetanus, diphtheria and acellular pertussis) combination, adjuvanted with aluminum hydroxide, was chosen as model formulation to quantify and determine the level of adsorption of acellular pertussis (aP) antigens onto adjuvant surface at the same time. The assay used specific antibodies bound to magnetic microspheres presenting unique digital signatures for each pertussis antigen, allowing the simultaneous recognition of respective antigens in the whole vaccine, avoiding laborious procedures for adjuvant separation. Accurate and reproducible quantification of aP antigens in TdaP vaccine has been achieved in the range 0.78-50 ng/mL, providing simultaneously information on antigen identity, quantity, and degree of adsorption to aluminum hydroxide. The current study could further be considered as a model to set up in vitro potency assays thus supporting the replacement of animal tests accordingly to the 3Rs concept.

Newborn Adipokines and Birth Outcomes

BACKGROUND

Adipokines can serve as a measure of adipose tissue activity. Although birthweight correlates with neonatal adiposity, findings for cord blood levels of adipokines and birth outcomes have been conflicted. Therefore, we determined the cross-sectional associations between adipokines measured in newborn dried blood spots (DBS) and birth outcomes.

METHODS

The Upstate KIDS study enrolled mothers and infants from 2008 to 2010. Among infants whose parents consented to the use of residual DBS from newborn screening, 2397 singletons and 1240 twins had adipokine measurements from the Human Obesity Panel (R&D Systems) by Luminex. Odds ratios were estimated by multivariable logistic regression for risk of birth outcomes of preterm delivery (<37 weeks for singletons, <32 for twins) and small-for-gestational age (SGA <10th for singletons and <3rd for twins age- and sex-specific percentiles) by adipokine quintiles. Generalised estimating equations were applied to account for correlations between twins.

RESULTS

Singletons in the lowest compared with the highest quintile of adiponectin were more likely preterm (adjusted odds ratio 3.26; 95% confidence interval [CI] 1.99, 5.34) and SGA (1.81; [95% CI 1.18, 2.77]). Similar associations were observed among twins. Resistin was associated with preterm birth (Q1 vs. Q5: 2.08; [95% CI 1.20, 3.62]) only among singletons. Adipsin had inconsistent associations after adjustment.

CONCLUSIONS

This large population-based study demonstrates that newborn DBS-measured adipokines are associated with birth outcomes, particularly preterm birth and SGA among those with lower adiponectin levels regardless of plurality.

Disparate detection outcomes for anti-HCV IgG and HCV RNA in dried blood spots

Dried blood spots (DBS) expedite the collection, storage and shipping of blood samples, thereby facilitating large-scale serologic studies. We evaluated the sensitivity of anti-HCV IgG testing and HCV-RNA quantitation using freshly prepared and stored DBS derived from HCV-infected patients. Protocols for elution were optimized using DBS prepared from plasma of 52 HCV-infected persons and 51 uninfected persons (control DBS), then applied to DBS from 33 chronic hepatitis C patients that had been stored at -20°C for 5 years (stored DBS). Control and stored DBS, and their corresponding plasma, were processed for anti-HCV IgG testing using the VITROS chemiluminescence assay (CIA) and the HCV 3.0 enzyme immunoassay (EIA) (Ortho-Clinical Diagnostics), and for HCV RNA quantitation by quantitative (q) RT-PCR. HCV genotyping was conducted by nucleotide sequencing. The sensitivity of CIA and EIA in control DBS was 92% and 90%, respectively, compared to 100% and 97%, respectively, in stored DBS. The sensitivity of HCV RNA detection was 88% in control DBS, compared to 36% in stored DBS. Specificity was 100% for all the assays in both control and stored DBS. Genotypes 1, 2 and 3 were detected in 16 (62%), 6 (23.1%), and 4 (15.3%) samples, respectively. Sequences generated from DBS and their corresponding plasma samples were identical. Whereas the sensitivity of anti-HCV IgG detection in stored DBS was equivalent to that in recently prepared DBS, the sensitivity of HCV RNA detection was markedly lower in stored DBS compared to recently prepared DBS. Stored DBS may be reliably used for anti-HCV detection but for HCV-RNA-based testing freshly prepared DBS is preferable to stored DBS.