Stability of Proteins in Dried Blood Spot Biobanks

Comparative evaluation of the diagnostic accuracies of four different malaria rapid diagnostic test kits available in Ghana

Malaria rapid diagnostic test (mRDT) kit is one of the techniques for diagnosing malaria. Due to its inherent advantages over the microscopy technique, several brands of the kit have flooded malaria endemic countries, without prior in-country evaluation. Two of such mRDT kits are Oscar (India) and Standard Q (Korea Republic). In this study, the performance of Oscar and Standard Q mRDT kits were compared to First Response (India) and CareStart (USA) mRDTs, which have been evaluated and deployed for use approved by the Ministry of Health (MOH). In this comparative study, whole blood samples were collected from patients suspected of malaria. Plasmodium falciparum was detected in each sample using nested polymerase chain reaction (nPCR), microscopy and the four mRDTs. The sensitivities, specificities, accuracies, positive and negative predictive values and accuracies of the mRDTs were determined using nPCR as a reference technique. Kappa statistic was used to determine the level of agreement among the techniques. Two hundred (200) blood samples were analyzed in this study. The overall detection rates of P. falciparum by microscopy, First Response, CareStart, Oscar-PfHRP2, Standard Q mRDT kits and nPCR were 31.5%, 34.5%, 33.5%, 32%, 31% and 43% (x2 = 6.1, p = 0.046), respectively. The accuracies of CareStart and First Response were comparable (90.5% vs. 89.5%). Further, comparing their sensitivities, Oscar-PfHRP2 was 74.4% (95% confidence interval (CI): 63.9-83.2) while that of Standard Q was 72.1% (95% CI: 61.4-81.2), with comparable accuracies (Oscar-PfHRP2-89% and Standard Q -88%). Apart from First Response that was 98.3% specific, the others were 100% specific. Kappa test revealed perfect diagnostic agreement (κ = 0.90-0.98) among the four mRDTs. That notwithstanding, Oscar-PfHRP2 agreed better with CareStart (κ = 0.94) and First Response (κ = 0.92) compared to the agreement between Standard Q and, CareStart (κ = 0.92) and First Response (κ = 0.90). Taken together, the diagnostic performance of the four mRDT kits were statistically similar. That notwithstanding, new mRDT kits should be evaluated prior to deployment for use.

Use of dried blood spots for monitoring inflammatory and nutritional biomarkers in the elderly

OBJECTIVES

Blood microsampling, particularly dried blood spots (DBSs), is an attractive minimally-invasive approach that is well suited for home sampling and predictive medicine associated with longitudinal follow-up of the elderly. However, in vitro diagnostic quantification of biomarkers from DBS poses a major challenge. Clinical mass spectrometry can reliably quantify blood proteins in various research projects. Our goal here was to use mass spectrometry of DBS in a real-world clinical setting and compared it to the standard immunoassay method. We also sought to correlate DBS mass spectrometry measurements with clinical indices.

METHODS

A clinical trial of diagnostic equivalence was conducted to compare conventional venous samples quantified by immunoassay and DBSs quantified by mass spectrometry in an elderly population. We assayed three protein biomarkers of nutritional and inflammatory status: prealbumin (transthyretin), C-reactive protein, and transferrin.

RESULTS

The analysis of DBSs showed satisfactory variability and low detection limits. Statistical analysis confirmed that the two methods give comparable results at clinical levels of accuracy. In conclusion, we demonstrated, in a real-life setting, that DBSs can be used to measure prealbumin, CRP and transferrin, which are commonly used markers of nutritional status and inflammation in the elderly. However, there was no correlation with patient frailty for these proteins.

CONCLUSIONS

Early detection and regular monitoring of nutritional and inflammatory problems using DBS appear to be clinically feasible. This could help resolve major public health challenges in the elderly for whom frailty leads to serious risks of health complications.

Proteome profiling of home-sampled dried blood spots reveals proteins of SARS-CoV-2 infections

BACKGROUND

Self-sampling of dried blood spots (DBS) offers new routes to gather valuable health-related information from the general population. Yet, the utility of using deep proteome profiling from home-sampled DBS to obtain clinically relevant insights about SARS-CoV-2 infections remains largely unexplored.

METHODS

Our study involved 228 individuals from the general Swedish population who used a volumetric DBS sampling device and completed questionnaires at home during spring 2020 and summer 2021. Using multi-analyte COVID-19 serology, we stratified the donors by their response phenotypes, divided them into three study sets, and analyzed 276 proteins by proximity extension assays (PEA). After normalizing the data to account for variances in layman-collected samples, we investigated the association of DBS proteomes with serology and self-reported information.

RESULTS

Our three studies display highly consistent variance of protein levels and share associations of proteins with sex (e.g., MMP3) and age (e.g., GDF-15). Studying seropositive (IgG+) and seronegative (IgG-) donors from the first pandemic wave reveals a network of proteins reflecting immunity, inflammation, coagulation, and stress response. A comparison of the early-infection phase (IgM+IgG-) with the post-infection phase (IgM-IgG+) indicates several proteins from the respiratory system. In DBS from the later pandemic wave, we find that levels of a virus receptor on B-cells differ between seropositive (IgG+) and seronegative (IgG-) donors.

CONCLUSIONS

Proteome analysis of volumetric self-sampled DBS facilitates precise analysis of clinically relevant proteins, including those secreted into the circulation or found on blood cells, augmenting previous COVID-19 reports with clinical blood collections. Our population surveys support the usefulness of DBS, underscoring the role of timing the sample collection to complement clinical and precision health monitoring initiatives.

Mass spectrometry-based proteomic analysis of biological stains identifies body fluids specific markers

The identification of biological stains and their tissue resource is an important part of forensic research. Current methods suffer from several limitations including poor sensitivity and specificity, trace samples, and sample destruction. In this study, we profiled the proteomes of menstrual blood, peripheral blood, saliva, semen, and vaginal fluid with mass spectrometry technology. Tissue-enhanced and tissue-specific proteins of each group have been proposed as potential biomarkers. These candidate proteins were further annotated and screened through the combination with the Human Protein Atlas database. Our data not only validates the protein biomarkers reported in previous studies but also identifies novel candidate biomarkers for human body fluids. These candidates lay the foundation for the development of rapid and specific forensic examination methods.

Insight into Increased Recovery and Simplification of Genomic DNA Extraction Methods from Dried Blood Spots

There is no consensus on how to perform the manual extraction of nucleic acids from dried blood spots (DBSs). Current methods typically involve agitation of the DBSs in a solution for varying amounts of time with or without heat, and then purification of the eluted nucleic acids with a purification protocol. We explored several characteristics of genomic DNA (gDNA) DBS extraction such as extraction efficiency, the role of red blood cells (RBCs) in extraction and critical kinetic factors to understand if these protocols can be simplified while maintaining sufficient gDNA recovery. We found that agitation in a RBC lysis buffer before performing a DBS gDNA extraction protocol increases yield 1.5 to 5-fold, depending upon the anticoagulant used. The use of an alkaline lysing agent along with either heat or agitation was sufficient to elute quantitative polymerase chain reaction (qPCR) amplifiable gDNA in 5 minutes. This work adds insight into the extraction of gDNA from DBSs with the intention of informing a simple, standardized manual protocol for extraction.

A Systematic Literature Review on the Use of Dried Biofluid Microsampling in Patients With Kidney Disease

BACKGROUND

Kidney disease is fairly unique due to the lack of symptoms associated with disease activity, and it is therefore dependent on biological monitoring. Dried biofluids, particularly dried capillary blood spots, are an accessible, easy-to-use technology that have seen increased utility in basic science research over the past decade. However, their use is yet to reach the kidney patient population clinically or in large-scale discovery science initiatives. The aim of this study was to systematically evaluate the existing literature surrounding the use of dried biofluids in kidney research.

METHODS

A systematic literature review was conducted using three search engines and a predefined search term strategy. Results were summarised according to the collection method, type of biofluid, application to kidney disease, cost, sample stability and patient acceptability.

RESULTS

In total, 404 studies were identified and 67 were eligible. In total, 34,739 patients were recruited to these studies with a skew towards male participants (> 73%). The majority of samples were blood, which was used either for monitoring anti-rejection immunosuppressive drug concentrations or for kidney function. Dried biofluids offered significant cost savings to the patient and healthcare service. The majority of patients preferred home microsampling when compared to conventional monitoring.

CONCLUSION

There is an unmet need in bringing dried microsampling technology to advance kidney disease despite its advantages. This technology provides an opportunity to upscale patient recruitment and longitudinal sampling, enhance vein preservation and overcome participation bias in research.

Exploring Natural Immune Responses to Shigella Exposure Using Multiplex Bead Assays on Dried Blood Spots in High-Burden Countries: Protocol From a Multisite Diarrhea Surveillance Study

Background

Molecular diagnostics on human fecal samples have identified a larger burden of shigellosis than previously appreciated by culture. Evidence of fold changes in immunoglobulin G (IgG) to conserved and type-specific Shigella antigens could be used to validate the molecular assignment of type-specific Shigella as the etiology of acute diarrhea and support polymerase chain reaction (PCR)-based microbiologic end points for vaccine trials.

Methods

We will test dried blood spots collected at enrollment and 4 weeks later using bead-based immunoassays for IgG to invasion plasmid antigen B and type-specific lipopolysaccharide O-antigen for Shigella flexneri 1b, 2a, 3a, and 6 and Shigella sonnei in Shigella-positive cases and age-, site-, and season-matched test-negative controls from all sites in the Enterics for Global Health (EFGH) Shigella surveillance study. Fold antibody responses will be compared between culture-positive, culture-negative but PCR-attributable, and PCR-positive but not attributable cases and test-negative controls. Age- and site-specific seroprevalence distributions will be identified, and the association between baseline antibodies and Shigella attribution will be estimated.

Conclusions

The integration of these assays into the EFGH study will help support PCR-based attribution of acute diarrhea to type-specific Shigella, describe the baseline seroprevalence of conserved and type-specific Shigella antibodies, and support correlates of protection for immunity to Shigella diarrhea. These insights can help support the development and evaluation of Shigella vaccine candidates.

Toward ovarian cancer screening with protein biomarkers using dried, self-sampled cervico-vaginal fluid

Early detection is key for increased survival in ovarian cancer, but no general screening program exists today due to lack of biomarkers and overall cost versus benefit over traditional clinical methods. Here, we used dried cervico-vaginal fluid (CVF) as sampling matrix coupled with mass spectrometry for detection of protein biomarkers. We find that self-collected CVF on paper cards yields robust results and is suitable for high-throughput proteomics. Artificial intelligence-based methods were used to identify an 11-protein panel that separates cases from controls. In validation data, the panel achieved a sensitivity of 0.97 (95% CI 0.91-1.00) at a specificity of 0.67 (0.40-0.87). Analyses of samples collected prior to development of symptoms indicate that the panel is informative also of future risk of disease. Dried CVF is used in cervical cancer screening, and our results opens the possibility for a screening program also for ovarian cancer, based on self-collected CVF samples.

Is the stability of folates in dried blood microsamples sufficient to perform home-sampling studies?

Dried blood microsampling is increasingly used for home-sampling and epidemiological studies because of its multiple advantages, including an often greatly improved analyte stability. However, a critical assessment of the stability under realistic conditions should always be performed as part of the validation, especially for unstable molecules like folates (vitamin B9). Here, the objective was to determine whether folate stability in dried blood microsamples is sufficient to allow the set-up of home-sampling studies for the monitoring of folate status in e.g., women of reproductive age. An extensive set of stability experiments was performed to evaluate the stability of the main folate vitamer 5-methyltetrahydrofolate (5MTHF), its oxidation product MeFOX and the minor non-methyl folate vitamers 10-formylfolic acid (10FoFA), 5,10-methenyltetrahydrofolate (5,10CH+THF) and tetrahydrofolate (THF) in dried blood microsamples using volumetric absorptive microsampling (VAMS) or regular dried blood spots (DBS). The evaluations included (EDTA-anticoagulated blood was collected from a single donor measured in four replicates per condition and time point): (i) the effect of temperature (-20 °C, 4 °C, ambient temperature and 37 °C), (ii) the effect of light (during drying and storage) and humidity, and (iii) the effect of storage under vacuum and pretreatment of the microsamples with stabilizing agents on folate stability. At -20 °C and 4 °C, all folate levels were within 85 to 115% of the baseline value up till two weeks of storage in both VAMS samples and DBS. However, at room temperature the stability of the analyzed folates was only consistently observed up till three days in VAMS samples, and for none of the folates at 37 °C. Humidity had a major impact on 5,10CH+THF stability, but this could be easily improved by using desiccant. Both vacuum treatment and pretreatment of microsamples with 0.1% DL-dithiothreitol and 5% butylated hydroxytoluene improved the stability at room temperature in VAMS samples, but these effects were limited at 37 °C and in DBS. Overall, the stability of the individual folate vitamers proved to be challenging and strongly temperature- and time-dependent. Nonetheless, if controlled transport (temperature and duration) can be assured, the set-up of home-sampling studies to evaluate the folate status using dried blood microsamples can still be beneficial.

One-step functionalization of paper and simplified antibody immobilization for on-the-spot immunocapture from dried serum in liquid chromatography-tandem mass spectrometry based targeted protein determination

This work aimed to simplify and improve the process of binding monoclonal antibodies (mAbs) covalently to filter paper for use in dried blood spot sampling, enabling instant capture of protein biomarkers for targeted protein determination. Incorporating the necessary immunocapture sample preparation step in the initial sampling stage saves time and reduces the workload. The biomarker human chorionic gonadotropin (hCG) was used as the model analyte. The antibody-based paper samplers were prepared by functionalizing paper discs (6 mm) through a simple reaction using divinyl sulfone (DVS). After DVS activation, the paper discs were incubated with E27 hCG mAbs, followed by 0.05% tween/phosphate buffer saline to block the surface. After sample application and drying, the discs only needed to be washed before tryptic digestion and finally analysed on a nanoliquid chromatography-tandem mass spectrometry system. The finished DVS-mAbs samplers could selectively capture hCG (100 ng/mL) from human serum, with a recovery of 50%. Sample clean-up reduced the number of identified proteins from 132 to 82 before and after wash, respectively, with a 70% reduction in serum albumin signal while still retaining hCG on the sampler during the washing protocol. An evaluation of the samplers revealed excellent linearity (R2  = 0.9995) for hCG in serum with relative standard deviations below 15%. This work has presented the first ever reported paper samplers immobilized with antibodies utilizing DVS chemistry, showing promise in the future of paper-based sampling.

Contemporary blood doping-Performance, mechanism, and detection

Blood doping is prohibited for athletes but has been a well-described practice within endurance sports throughout the years. With improved direct and indirect detection methods, the practice has allegedly moved towards micro-dosing, that is, reducing the blood doping regime amplitude. This narrative review evaluates whether blood doping, specifically recombinant human erythropoietin (rhEpo) treatment and blood transfusions are performance-enhancing, the responsible mechanism as well as detection possibilities with a special emphasis on micro-dosing. In general, studies evaluating micro-doses of blood doping are limited. However, in randomized, double-blinded, placebo-controlled trials, three studies find that infusing as little as 130 ml red blood cells or injecting 9 IU × kg bw-1 rhEpo three times per week for 4 weeks improve endurance performance ~4%-6%. The responsible mechanism for a performance-enhancing effect following rhEpo or blood transfusions appear to be increased O2 -carrying capacity, which is accompanied by an increased muscular O2 extraction and likely increased blood flow to the working muscles, enabling the ability to sustain a higher exercise intensity for a given period. Blood doping in micro-doses challenges indirect detection by the Athlete Biological Passport, albeit it can identify ~20%-60% of the individuals depending on the sample timing. However, novel biomarkers are emerging, and some may provide additive value for detection of micro blood doping such as the immature reticulocytes or the iron regulatory hormones hepcidin and erythroferrone. Future studies should attempt to validate these biomarkers for implementation in real-world anti-doping efforts and continue the biomarker discovery.

Changes in inflammatory proteins following platelet transfusion in a neonatal population

BACKGROUND

Studies have demonstrated increased morbidity and mortality with platelet transfusions in the neonatal period. Platelets are as important for host immunity and inflammation as for hemostasis. Increased inflammation may explain the dose-associated increase in mortality, bleeding, and lung disease.

OBJECTIVE

This study aims to assess if there are any changes in inflammatory cytokines post-platelet transfusion in babies in NICU.

METHODS

This prospective observational study recruited babies due to receive a non-emergency platelet transfusion. Dried whole blood samples were collected prior to and 2 h post-transfusion. Samples were processed using multiplex immunoassay to enable analysis of tiny blood volumes. Statistical analysis was performed using R.

RESULTS

Seventeen babies underwent 26 platelet transfusions across two centers. Median birthweight was 1545 g (535-3960 g) and median birth gestation was 31 weeks and 1 day (23 + 1 to 40 + 5). Median pre-transfusion platelet count was 19.5 × 109/l. There was a significant increase in levels of CXCL5 (p < 0.001), CD40 (p = 0.001), and TGF-β (p = 0.001) in neonatal blood samples post-platelet transfusion in the study group.

CONCLUSION

The increase in the cytokines CXCL5, CD40 and TGF-β after platelet transfusion in babies in NICU could potentiate existing inflammation, NEC, lung, or white matter injury. This could potentially explain long-term harm from platelet transfusion in babies.

IMPACT

There is a change in levels of immunomodulatory proteins CXCL5, CD40, and TGF-β after platelet transfusion in babies in NICU. Murine neonatal models have demonstrated an increase in cytokine levels after platelet transfusions. This is the first time that this has been demonstrated in human neonates. The increase in proinflammatory cytokines could potentially explain the long-term harm from platelet transfusion in babies, as they could potentiate existing inflammation, NEC, lung injury, or white matter injury.

Development and validation of a quantitative Proximity Extension Assay instrument with 21 proteins associated with cardiovascular risk (CVD-21)

BACKGROUND

Treatment of cardiovascular diseases (CVD) is a substantial burden to healthcare systems worldwide. New tools are needed to improve precision of treatment by optimizing the balance between efficacy, safety, and cost. We developed a high-throughput multi-marker decision support instrument which simultaneously quantifies proteins associated with CVD.

METHODS AND FINDINGS

Candidate proteins independently associated with different clinical outcomes were selected from clinical studies by the screening of 368 circulating biomarkers. We then custom-designed a quantitative PEA-panel with 21 proteins (CVD-21) by including recombinant antigens as calibrator samples for normalization and absolute quantification of the proteins. The utility of the CVD-21 tool was evaluated in plasma samples from a case-control cohort of 4224 patients with chronic coronary syndrome (CCS) using multivariable Cox regression analyses and machine learning techniques. The assays in the CVD-21 tool gave good precision and high sensitivity with lower level of determination (LOD) between 0.03-0.7 pg/ml for five of the biomarkers. The dynamic range for the assays was sufficient to accurately quantify the biomarkers in the validation study except for troponin I, which in the modeling was replaced by high-sensitive cardiac troponin T (hs-TnT). We created seven different multimarker models, including a reference model with NT-proBNP, hs-TnT, GDF-15, IL-6, and cystatin C and one model with only clinical variables, for the comparison of the discriminative value of the CVD-21 tool. All models with biomarkers including hs-TnT provided similar discrimination for all outcomes, e.g. c-index between 0.68-0.86 and outperformed models using only clinical variables. Most important prognostic biomarkers were MMP-12, U-PAR, REN, VEGF-D, FGF-23, TFF3, ADM, and SCF.

CONCLUSIONS

The CVD-21 tool is the very first instrument which with PEA simultaneously quantifies 21 proteins with associations to different CVD. Novel pathophysiologic and prognostic information beyond that of established biomarkers were identified by a number of proteins.

Stability of inflammation markers in human blood collected using volumetric absorptive microsampling (VAMS) under typical laboratory storage temperatures

Dried blood spots (DBS) collected on filter paper such as Guthrie cards are stored for years at room temperature. The assumption is that once dried, the samples remain stable and quantifiable indefinitely since the metabolites these were initially designed to measure, are known for their extended stability. The concentration of other blood proteins such as cytokines, however, are known to vary with storage even in liquid samples stored at -80 °C for extended periods of time. We sought to determine if cytokines are stable for up to 5 months when stored as a dried blood sample using volumetric absorptive microsampling (VAMS) devices. To test this, blood was collected from 4 healthy participants, spiked with recombinant cytokines, and collected into 30 µL VAMS devices. These prepared VAMS devices were stored at room temperature, 4 °C, or -20 °C for up to 5 months and matching VAMS liquid extracts were stored at -80 °C for the same period of time. At each timepoint, the samples were extracted from the VAMS devices and the extracts were analysed by Luminex® for quantification of up to 31 cytokines. These methods were also tested in a remote clinical study over a period of up to 8 months. Cytokine analysis revealed that room temperature, the current standard for DBS and VAMS storage, performed the poorest out of all storage temperatures with significant losses in 13/21 analytes compared to 4 °C at 5 months. Storage at 4 °C or colder performed well for the majority of analytes tested, however out of those, the optimal storage temperature differed for each analyte. There were a small number of analytes that performed poorly regardless of storage conditions and for fractalkine, this was found to be caused by inefficient recovery during extraction. Cytokine concentrations from finger-prick samples were also found to be much more variable that those in venous blood samples. Our results highlight the need to understand the stability of analytes of interest before committing to longitudinal collection and storage of samples in VAMS devices. These data give confidence that storage at 4 °C or colder was beneficial for cytokine stability. Wherein 25/31 cytokines were quantifiably stable at -20 °C when stored for 3 months and 17/21 were quantifiably stable after 5 months when stored at 4 °C.

Long COVID manifests with T cell dysregulation, inflammation, and an uncoordinated adaptive immune response to SARS-CoV-2

Long COVID (LC), a type of post-acute sequelae of SARS-CoV-2 infection (PASC), occurs after at least 10% of SARS-CoV-2 infections, yet its etiology remains poorly understood. Here, we used multiple "omics" assays (CyTOF, RNAseq/scRNAseq, Olink) and serology to deeply characterize both global and SARS-CoV-2-specific immunity from blood of individuals with clear LC and non-LC clinical trajectories, 8 months following infection and prior to receipt of any SARS-CoV-2 vaccine. Our analysis focused on deep phenotyping of T cells, which play important roles in immunity against SARS-CoV-2 yet may also contribute to COVID-19 pathogenesis. Our findings demonstrate that individuals with LC exhibit systemic inflammation and immune dysregulation. This is evidenced by global differences in T cell subset distribution in ways that imply ongoing immune responses, as well as by sex-specific perturbations in cytolytic subsets. Individuals with LC harbored increased frequencies of CD4+ T cells poised to migrate to inflamed tissues, and exhausted SARS-CoV-2-specific CD8+ T cells. They also harbored significantly higher levels of SARS-CoV-2 antibodies, and in contrast to non-LC individuals, exhibited a mis-coordination between their SARS-CoV-2-specific T and B cell responses. RNAseq/scRNAseq and Olink analyses similarly revealed immune dysregulatory mechanisms, along with non-immune associated perturbations, in individuals with LC. Collectively, our data suggest that proper crosstalk between the humoral and cellular arms of adaptive immunity has broken down in LC, and that this, perhaps in the context of persistent virus, leads to the immune dysregulation, inflammation, and clinical symptoms associated with this debilitating condition.

Circulating tumour cells for early detection of clinically relevant cancer

Given that cancer mortality is usually a result of late diagnosis, efforts in the field of early detection are paramount to reducing cancer-related deaths and improving patient outcomes. Increasing evidence indicates that metastasis is an early event in patients with aggressive cancers, often occurring even before primary lesions are clinically detectable. Metastases are usually formed from cancer cells that spread to distant non-malignant tissues via the blood circulation, termed circulating tumour cells (CTCs). CTCs have been detected in patients with early stage cancers and, owing to their association with metastasis, might indicate the presence of aggressive disease, thus providing a possible means to expedite diagnosis and treatment initiation for such patients while avoiding overdiagnosis and overtreatment of those with slow-growing, indolent tumours. The utility of CTCs as an early diagnostic tool has been investigated, although further improvements in the efficiency of CTC detection are required. In this Perspective, we discuss the clinical significance of early haematogenous dissemination of cancer cells, the potential of CTCs to facilitate early detection of clinically relevant cancers, and the technological advances that might improve CTC capture and, thus, diagnostic performance in this setting.

Forensic prediction of sex, age, height, body mass index, hip-to-waist ratio, smoking status and lipid lowering drugs using epigenetic markers and plasma proteins

The prediction of human characteristics from blood using molecular markers would be very helpful in forensic science. Such information can be particularly important in providing investigative leads in police casework from, for example, blood found at crime scenes in cases without a suspect. Here, we investigated the possibilities and limitations of predicting seven phenotypic traits (sex, age, height, body mass index [BMI], hip-to-waist [WTH] ratio, smoking status and lipid-lowering drug use) using either DNA methylation or plasma proteins separately or in combination. We developed a prediction pipeline starting with the prediction of sex followed by sex-specific, stepwise, individual age, sex-specific anthropometric traits and, finally, lifestyle-related traits. Our data revealed that age, sex and smoking status can be accurately predicted from DNA methylation alone, while the use of plasma proteins was highly accurate for prediction of the WTH ratio, and a combined analysis of the best predictions for BMI and lipid-lowering drug use. In unseen individuals, age was predicted with a standard error of 3.3 years for women and 6.5 years for men, while the accuracy in smoking prediction across both men and women was 0.86. In conclusion, we have developed a stepwise approach for the de-novo prediction of individual characteristics from plasma proteins and DNA methylation markers. These models are accurate and may provide valuable information and investigative leads in future forensic casework.

A Pilot Study of Biliary Atresia Newborn Screening Using Dried Blood Spot Matrix Metalloproteinase-7

OBJECTIVES

Timely diagnosis is a critical challenge and is associated with improved survival of biliary atresia (BA) patients. We aimed to measure matrix metalloproteinase-7 (MMP-7) levels in BA patients within 3 days of birth using the dried blood spot (DBS) method and evaluate its potential as a screening tool.

METHODS

The study enrolled 132 patients, including 25 patients diagnosed with BA and 107 non-BA patients with other congenital or perinatal conditions from the National Taiwan University Children Hospital. The stored DBS samples collected from 48 to 72 hours of life were retrieved from newborn screening centers. MMP-7 on the DBS was quantified using a sensitive sandwich enzyme-linked immunosorbent assay (ELISA).

RESULTS

The MMP-7 levels of BA patients on the DBS were significantly higher than those of non-BA patients (19.2 ± 10.4 vs 5.6 ± 2.7 ng/mL, P value < 0.0001). MMP-7 levels in non-BA patients, including 5 patients with hepatobiliary structural anomaly, 9 patients with intrahepatic cholestasis, and 93 patients with other perinatal diseases, were 11.6 ± 4.2 ng/mL, 6.9 ± 3.0 ng/mL, and 5.2 ± 2.1 ng/mL, respectively. The DBS MMP-7 level showed good accuracy for identifying BA, with an area under the curve of 93.7% [95% confidence interval (CI): 87.7%-99.7%]. The MMP-7 cutoff at 8.0 ng/mL showed a sensitivity of 92.0% (95% CI: 75.0%-98.6%) and specificity of 92.5% (95% CI: 85.9%-96.1%) for detecting BA from other congenital or perinatal diseases.

CONCLUSIONS

MMP-7 DBS analysis can be used to distinguish BA from other conditions as early as 3 days of age.

Evaluation of pre-processing methods for tear fluid proteomics using proximity extension assays

Tear fluid forms a potential source for biomarker identification, and can be minimal invasively collected via Schirmer strips. The lack of knowledge on the processing of Schirmer strips however complicates the analysis and between-study comparisons. We studied two different pre-processing methods, specifically the use of punches of the strip versus elution of the strip in a buffer. Tear fluid filled Schirmer strips were collected from 5 healthy participants, and divided into two halves over the length of the strip. In either part, punches or eluates were obtained from 4 different locations, from the first part touching the eye (head) to the end, to assess the protein distribution along the strips. The levels of 92 inflammatory proteins were measured in the punches/eluates using proximity extension assays. The punch method yielded higher protein detectability compared to the elution method (76% vs 66%; p ≤ 0.001). Protein expression level was found to be slightly higher in the head of the strip, however, 3 out of 5 punches from the head failed quality control. Protein expression levels over the remaining parts of the strips were similar. Our study showed beneficial use of punches of any part of the strip except the head in future biomarker research.

Microsampling tools for collecting, processing, and storing blood at the point-of-care

In the wake of the COVID-19 global pandemic, self-administered microsampling tools have reemerged as an effective means to maintain routine healthcare assessments without inundating hospitals or clinics. Finger-stick collection of blood is easily performed at home, in the workplace, or at the point-of-care, obviating the need for a trained phlebotomist. While the initial collection of blood is facile, the diagnostic or clinical utility of the sample is dependent on how the sample is processed and stored prior to transport to an analytical laboratory. The past decade has seen incredible innovation for the development of new materials and technologies to collect low-volume samples of blood with excellent precision that operate independently of the hematocrit effect. The final application of that blood (i.e., the test to be performed) ultimately dictates the collection and storage approach as certain materials or chemical reagents can render a sample diagnostically useless. Consequently, there is not a single microsampling tool that is capable of addressing every clinical need at this time. In this review, we highlight technologies designed for patient-centric microsampling blood at the point-of-care and discuss their utility for quantitative sampling as a function of collection material and technique. In addition to surveying methods for collecting and storing whole blood, we emphasize the need for direct separation of the cellular and liquid components of blood to produce cell-free plasma to expand clinical utility. Integrating advanced functionality while maintaining simple user operation presents a viable means of revolutionizing self-administered microsampling, establishing new avenues for innovation in materials science, and expanding access to healthcare.

Seroprevalence of SARS-CoV-2 antibodies in Italy in newborn dried blood spots

OBEJCTIVES

Serosurveys can be used to monitor COVID-19 seroprevalence and conduct surveillance. Dried blood spot (DBS), used increasingly as a valuable sample to assay severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) antibodies (Ab), has several advantages, particularly in infants, due to the limited amount of blood required and its utility in testing a large number of samples in a limited time-frame. We evaluated SARS-CoV-2 IgG Ab prevalence in newborn DBS in the Trentino region of Italy, during the time period January 2020 - December 2021.

METHODS

Anti-SARS-CoV-2 IgG levels were determined in DBS by means of Anti-SARS-CoV-2 QuantiVac IgG ELISA assay (Euroimmun, Lubeck, Germany).

RESULTS

Analyses included 2,400 DBS from newborns (54% M, 46% F), samples being collected 2-3 days after birth. The first DBS that tested positive for anti-SARS-CoV-2 IgG antibodies was found in March 2020 and, up to May 2020, only 4 positive results were detected overall. Starting from June 2020, the positivity thresholds increased according to the epidemiological waves of the COVID-19 pandemic in Italy, with a robust increment in the winters of 2020 and 2021. The percentage of positive DBS rose from 0 to 6% to 10-47%, in 2020 and 2021, respectively.

CONCLUSIONS

This study demonstrates DBS is a suitable tool for both epidemiological purposes and surveillance in the SARS-CoV-2 pandemic, particularly in newborns and pregnant women, saving blood waste and sparing patients any discomfort.

Detection of SARS-CoV-2 antibodies in serum and dried blood spot samples of vaccinated individuals using a sensitive homogeneous proximity extension assay

A homogeneous PCR-based assay for sensitive and specific detection of antibodies in serum or dried blood spots (DBS) is presented and the method is used to monitor individuals infected with or vaccinated against SARS-CoV-2. Detection probes were prepared by conjugating the recombinant spike protein subunit 1 (S1), containing the receptor binding domain (RBD) of SARS-CoV-2, to each of a pair of specific oligonucleotides. The same was done for the nucleocapsid protein (NP). Upon incubation with serum or DBS samples, the bi- or multivalency of the antibodies (IgG, IgA or IgM) brings pairs of viral proteins with their conjugated oligonucleotides in proximity, allowing the antibodies to be detected by a modified proximity extension assay (PEA). Anti-S1 and anti-NP antibodies could be detected simultaneously from one incubation reaction. This Antibody PEA (AbPEA) test uses only 1 µl of neat or up to 100,000-fold diluted serum or one ø1.2 mm disc cut from a DBS. All 100 investigated sera and 21 DBS collected prior to the COVID-19 outbreak were negative, demonstrating a 100% specificity. The area under the curve, as evaluated by Receiver Operating Characteristic (ROC) analysis reached 0.998 (95%CI: 0.993-1) for samples taken from 11 days after symptoms onset. The kinetics of antibody responses were monitored after a first and second vaccination using serially collected DBS from 14 individuals. AbPEA offers highly specific and sensitive solution-phase antibody detection without requirement for secondary antibodies, no elution step when using DBS sample in a simple procedure that lends itself to multiplex survey of antibody responses.

Direct Processing and Storage of Cell-Free Plasma Using Dried Plasma Spot Cards

Plasma separation cards represent a viable approach for expanding testing capabilities away from clinical settings by generating cell-free plasma with minimal user intervention. These devices typically comprise a basic structure of the plasma separation membrane, unconstrained porous collection pad, and utilize either (i) lateral or (ii) vertical fluidic pathways for separating plasma. Unfortunately, these configurations are highly susceptible to (i) inconsistent sampling volume due to differences in the patient hematocrit or (ii) severe contamination due to leakage of red blood cells or release of hemoglobin (i.e., hemolysis). Herein, we combine the enhanced sampling of our previously reported patterned dried blood spot cards with an assembly of porous separation materials to produce a patterned dried plasma spot card for direct processing and storage of cell-free plasma. Linking both vertical separation and lateral distribution of plasma yields discrete plasma collection zones that are spatially protected from potential contamination due to hemolysis and an inlet zone enriched with blood cells for additional testing. We evaluate the versatility of this card by quantitation of three classes of analytes and techniques including (i) the soluble transferrin receptor by enzyme-linked immunosorbent assay, (ii) potassium by inductively coupled plasma atomic emission spectroscopy, and (iii) 18S rRNA by reverse transcriptase quantitative polymerase chain reaction. We achieve quantitative recovery of each class of analyte with no statistically significant difference between dried and liquid reference samples. We anticipate that this sampling approach can be applied broadly to improve access to critical blood testing in resource-limited settings or at the point-of-care.

Volumetric Absorptive Microsampling (VAMS) for Targeted LC-MS/MS Determination of Tryptophan-Related Biomarkers

L-Tryptophan (TRP) metabolites and related biomarkers play crucial roles in physiological functions, and their imbalances are implicated in central nervous system pathologies and neurodegenerative diseases such as amyotrophic lateral sclerosis (ALS), Alzheimer’s disease, Parkinson’s disease, schizophrenia and depression. The measurement of TRP metabolites and related biomarkers possesses great potential to elucidate the disease mechanisms, aid preclinical drug development, highlight potential therapeutic targets and evaluate the outcomes of therapeutic interventions. An effective, straightforward, sensitive and selective liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed for the simultaneous determination of 24 TRP-related compounds in miniaturised murine whole blood samples. Sampling and sample pretreatment miniaturisation were achieved thanks to the development of a volumetric dried blood microsampling approach. Volumetric absorptive microsampling (VAMS) allows the accurate sampling of microvolumes of blood with advantages including, but not limited to, minimal sampling invasiveness, logistical improvements, method sustainability in terms of solvents and energy consumption, and improvement of animal studies in the framework of the 3Rs (Replacement, Reduction and Refinement) principles on animal welfare. The VAMS-LC-MS/MS method exhibited good selectivity, and correlation coefficient values for the calibration curves of each analyte were >0.9987. The limits of quantitation ranged from 0.1 to 25 ng/mL. The intra- and inter-day precisions in terms of RSD were <9.6%. All analytes were stable in whole blood VAMS samples stored at room temperature for at least 30 days with analyte losses < 14%. The developed method was successfully applied to the analysis of biological samples from mice, leading to the unambiguous determination of all the considered target analytes. This method can therefore be applied to analyse TRP metabolites and related biomarkers levels to monitor disease states, perform mechanistic studies and investigate the outcomes of therapeutic interventions.

Comparative performance data for multiplex SARS-CoV-2 serological assays from a large panel of dried blood spot specimens

The extent of the COVID-19 pandemic will be better understood through serosurveys and SARS-CoV-2 antibody testing. Dried blood spot (DBS) samples will play a central role in large scale serosurveillance by simplifying biological specimen collection and transportation, especially in Canada. Direct comparative performance data on multiplex SARS-CoV-2 assays resulting from identical DBS samples are currently lacking. In our study, we aimed to provide performance data for the BioPlex 2200 SARS-CoV-2 IgG (Bio-Rad), V-PLEX SARS-CoV-2 Panel 2 IgG (MSD), and Elecsys Anti-SARS-CoV-2 (Roche) commercial assays, as well as for two highly scalable in-house assays (University of Ottawa and Mount Sinai Hospital protocols) to assess their suitability for DBS-based SARS-CoV-2 DBS serosurveillance. These assays were evaluated against identical panels of DBS samples collected from convalescent COVID-19 patients (n = 97) and individuals undergoing routine sexually transmitted and bloodborne infection (STBBI) testing prior to the COVID-19 pandemic (n = 90). Our findings suggest that several assays are suitable for serosurveillance (sensitivity >97% and specificity >98%). In contrast to other reports, we did not observe an improvement in performance using multiple antigen consensus-based rules to establish overall seropositivity. This may be due to our DBS panel which consisted of samples collected from convalescent COVID-19 patients with significant anti-spike, -receptor binding domain (RBD), and -nucleocapsid antibody titers. This study demonstrates that biological specimens collected as DBS coupled with one of several readily available assays are useful for large-scale COVID-19 serosurveillance.

Determination of the Time since Deposition of Blood Traces Utilizing a Liquid Chromatography-Mass Spectrometry-Based Proteomics Approach

Knowledge about when a bloodstain was deposited at a crime scene can be of critical value in forensic investigation. A donor of a genetically identified bloodstain could be linked to a suspected time frame and the crime scene itself. Determination of the time since deposition (TsD) has been extensively studied before but has yet to reach maturity. We therefore conducted a proof-of-principle study to study time- and storage-dependent changes of the proteomes of dried blood stains. A bottom-up proteomics approach was employed, and high-resolution liquid-chromatography-mass-spectrometry (HR-LC-MS) and data-independent acquisition (DIA) were used to analyze samples aged over a 2 month period and two different storage conditions. In multivariate analysis, samples showed distinct clustering according to their TsD in both principal component analysis (PCA) and in partial least square discriminant analysis (PLS DA). The storage condition alters sample aging and yields different separation-driving peptides in hierarchical clustering and in TsD marker peptide selection. Certain peptides and amino acid modifications were identified and further assessed for their applicability in assessing passed TsD. A prediction model based on data resampling (Jackknife) was applied, and prediction values for selected peptide ratios were created. Depending on storage conditions and actual sample age, mean prediction performances ranges in between 70 and 130% for the majority of peptides and time points. This places this study as a first in investigating LC-MS based bottom-up proteomics approaches for TsD determination.

Plasma protein biomarkers for the detection of pancreatic neuroendocrine tumors and differentiation from small intestinal neuroendocrine tumors

There is an unmet need for novel biomarkers to diagnose and monitor patients with neuroendocrine neoplasms. The EXPLAIN study explores a multi-plasma protein and supervised machine learning strategy to improve the diagnosis of pancreatic neuroendocrine tumors (PanNET) and differentiate them from small intestinal neuroendocrine tumors (SI-NET). At time of diagnosis, blood samples were collected and analyzed from 39 patients with PanNET, 135 with SI-NET (World Health Organization Grade 1-2) and 144 controls. Exclusion criteria were other malignant diseases, chronic inflammatory diseases, reduced kidney or liver function. Prosed Oncology-II (i.e., OLink) was used to measure 92 cancer related plasma proteins. Chromogranin A was analyzed separately. Median age in all groups was 65-67 years and with a similar sex distribution (females: PanNET, 51%; SI-NET, 42%; controls, 42%). Tumor grade (G1/G2): PanNET, 39/61%; SI-NET, 46/54%. Patients with liver metastases: PanNET, 78%; SI-NET, 63%. The classification model of PanNET versus controls provided a sensitivity (SEN) of 0.84, specificity (SPE) 0.98, positive predictive value (PPV) of 0.92 and negative predictive value (NPV) of 0.95, and area under the receiver operating characteristic curve (AUROC) of 0.99; the model for the discrimination of PanNET versus SI-NET providing a SEN 0.61, SPE 0.96, PPV 0.83, NPV 0.90 and AUROC 0.98. These results suggest that a multi-plasma protein strategy can significantly improve diagnostic accuracy of PanNET and SI-NET.

Proteomics of Human Biological Fluids for Biomarker Discoveries: Technical Advances and Recent Applications

INTRODUCTION

Biological fluids are routine samples for diagnostic testing and monitoring. Blood samples are typically measured because of their moderate collection invasiveness and high information content on health and disease. Several body fluids, such as cerebrospinal fluid (CSF), are also studied and suited to specific pathologies. Over the last two decades proteomics has quested to identify protein biomarkers but with limited success. Recent technologies and refined pipelines have accelerated the profiling of human biological fluids.

AREAS COVERED

We review proteomic technologies for the identification of biomarkers. Those are based on antibodies/aptamers arrays or mass spectrometry (MS), but new ones are emerging. Advances in scalability and throughput have allowed to better design studies and cope with the limited sample size that had until now prevailed due to technological constraints. With these enablers, plasma/serum, CSF, saliva, tears, urine, and milk proteomes have been further profiled; we provide a non-exhaustive picture of some recent highlights (mainly covering literature from last five years in the Scopus database) using MS-based proteomics.

EXPERT OPINION

While proteomics has been in the shadow of genomics for years, proteomic tools and methodologies have reached a certain maturity. They are better suited to discover innovative and robust biofluid biomarkers.

Non-Lethal Blood Sampling of Fish in the lab and Field With Methods for Dried Blood Plasma Spot Omic Analyses

There is global acknowledgment that humane methods in animal research are a priority, but few environmental effects monitoring programs use nonlethal methods for fish. The goal of the present study was to determine the impacts of sampling small volumes of blood in larger-bodied fish on survival and healing. In addition to evaluating survival following blood sampling, we evaluated the utility of dried blood spots as an alternative for sample processing and storage in the field. In our approach, we housed 80 rainbow trout (Oncorhynchus mykiss) in our flow-through aquatic facility. We then anaesthetized using MS-222 and sampled 1 μl/g bw of blood via puncture of the caudal vasculature. We tested four different post-blood sampling treatments on the puncture wound: 1. application of liquid bandage; 2. a swab of betadine; 3. a swab of fish mucous; and 4. compared survival outcomes to a group where no post-treatment was performed (negative control). Overall, we observed 90% survival among all treatments, with the most effective approach being the negative control (100% survival). Based upon these results, we repeated the blood sampling with no-post treatment by housing 20 rainbow trout (not previously tested upon) in cages at a nearby creek and monitored survival for 2 weeks post sampling. The survival rate was 95% with full healing of the puncture site in all subjects. In addition to this, we tested the efficacy of dry blood spotting on proteomic, lipidomic and amino acid analysis as an alternative method for blood sample processing and storage. It was found that dried plasma spotting using parafilm in conjunction with a modified Bligh-Dyer extraction offered the best balance for good recovery of protein, lipid and amino acids relative to wet plasma and Noviplex dried plasma spot cards. In this article, we will present the detailed results of these combined studies and describe what we have determined to be the safest non-lethal blood sampling protocol.

Optimization, validation and initial clinical implications of a Luminex-based immunoassay for the quantification of Fragile X Protein from dried blood spots

Fragile X Syndrome (FXS) is caused by a trinucleotide expansion leading to silencing of the FMR1 gene and lack of expression of Fragile X Protein (FXP, formerly known as Fragile X Mental Retardation Protein, FMRP). Phenotypic presentation of FXS is highly variable, and the lack of reproducible, sensitive assays to detect FXP makes evaluation of peripheral FXP as a source of clinical variability challenging. We optimized a Luminex-based assay to detect FXP in dried blot spots for increased reproducibility and sensitivity by improving reagent concentrations and buffer conditions. The optimized assay was used to quantify FXP in 187 individuals. We show that the optimized assay is highly reproducible and detects a wide range of FXP levels. Mosaic individuals had, on average, higher FXP levels than fully methylated individuals, and trace amounts of FXP were consistently detectable in a subset of individuals with full mutation FXS. IQ scores were positively correlated with FXP levels in males and females with full mutation FXS demonstrating the clinical utility of this method. Our data suggest trace amounts of FXP detectable in dried blood spots of individuals with FXS could be clinically relevant and may be used to stratify individuals with FXS for optimized treatment.

Next Generation Plasma Proteomics Identifies High-Precision Biomarker Candidates for Ovarian Cancer

Simple Summary

Ovarian cancer is the eighth most common cancer among women and has a 5-year survival of only 30–50%. The survival is close to 90% for patients in stage I but only 20% for patients in stage IV. The presently available biomarkers have insufficient sensitivity and specificity for early detection and there is an urgent need to identify novel biomarkers. The aim of our study was to broadly measure protein biomarkers to find tests for the early detection of ovarian cancer. We found that combinations of 4–7 protein biomarkers can provide highly accurate detection of early- and late-stage ovarian cancer compared to benign conditions. The performance of the tests was then validated in a second independent cohort.

Abstract

Background: Ovarian cancer is the eighth most common cancer among women and has a 5-year survival of only 30–50%. The survival is close to 90% for patients in stage I but only 20% for patients in stage IV. The presently available biomarkers have insufficient sensitivity and specificity for early detection and there is an urgent need to identify novel biomarkers. Methods: We employed the Explore PEA technology for high-precision analysis of 1463 plasma proteins and conducted a discovery and replication study using two clinical cohorts of previously untreated patients with benign or malignant ovarian tumours (N = 111 and N = 37). Results: The discovery analysis identified 32 proteins that had significantly higher levels in malignant cases as compared to benign diagnoses, and for 28 of these, the association was replicated in the second cohort. Multivariate modelling identified three highly accurate models based on 4 to 7 proteins each for separating benign tumours from early-stage and/or late-stage ovarian cancers, all with AUCs above 0.96 in the replication cohort. We also developed a model for separating the early-stage from the late-stage achieving an AUC of 0.81 in the replication cohort. These models were based on eleven proteins in total (ALPP, CXCL8, DPY30, IL6, IL12, KRT19, PAEP, TSPAN1, SIGLEC5, VTCN1, and WFDC2), notably without MUCIN-16. The majority of the associated proteins have been connected to ovarian cancer but not identified as potential biomarkers. Conclusions: The results show the ability of using high-precision proteomics for the identification of novel plasma protein biomarker candidates for the early detection of ovarian cancer.

Proximity Extension Assay in Combination with Next-Generation Sequencing for High-throughput Proteome-wide Analysis

Understanding the dynamics of the human proteome is crucial for developing biomarkers to be used as measurable indicators for disease severity and progression, patient stratification, and drug development. The Proximity Extension Assay (PEA) is a technology that translates protein information into actionable knowledge by linking protein-specific antibodies to DNA-encoded tags. In this report we demonstrate how we have combined the unique PEA technology with an innovative and automated sample preparation and high-throughput sequencing readout enabling parallel measurement of nearly 1500 proteins in 96 samples generating close to 150,000 data points per run. This advancement will have a major impact on the discovery of new biomarkers for disease prediction and prognosis and contribute to the development of the rapidly evolving fields of wellness monitoring and precision medicine.

The polarity protein Par3 coordinates positively self-renewal and negatively invasiveness in glioblastoma

Glioblastoma (GBM) is a brain malignancy characterized by invasiveness to the surrounding brain tissue and by stem-like cells, which propagate the tumor and may also regulate invasiveness. During brain development, polarity proteins, such as Par3, regulate asymmetric cell division of neuro-glial progenitors and neurite motility. We, therefore, studied the role of the Par3 protein (encoded by PARD3) in GBM. GBM patient transcriptomic data and patient-derived culture analysis indicated diverse levels of expression of PARD3 across and independent from subtypes. Multiplex immunolocalization in GBM tumors identified Par3 protein enrichment in SOX2-, CD133-, and NESTIN-positive (stem-like) cells. Analysis of GBM cultures of the three subtypes (proneural, classical, mesenchymal), revealed decreased gliomasphere forming capacity and enhanced invasiveness upon silencing Par3. GBM cultures with suppressed Par3 showed low expression of stemness (SOX2 and NESTIN) but higher expression of differentiation (GFAP) genes. Moreover, Par3 silencing reduced the expression of a set of genes encoding mitochondrial enzymes that generate ATP. Accordingly, silencing Par3 reduced ATP production and concomitantly increased reactive oxygen species. The latter was required for the enhanced migration observed upon silencing of Par3 as anti-oxidants blocked the enhanced migration. These findings support the notion that Par3 exerts homeostatic redox control, which could limit the tumor cell-derived pool of oxygen radicals, and thereby the tumorigenicity of GBM.

Long-term effect of hematopoietic cell transplantation on systemic inflammation in patients with mucopolysaccharidoses

Mucopolysaccharidoses (MPS) are devastating inherited diseases treated with hematopoietic cell transplantation (HCT). However, disease progression, especially skeletal, still occurs in all patients. Secondary inflammation has been hypothesized to be a cause. To investigate whether systemic inflammation is present in untreated patients and to evaluate the effect of HCT on systemic inflammation, dried blood spots (n = 66) of patients with MPS (n = 33) treated with HCT between 2003 and 2019 were included. Time points consisted of pre-HCT and, for patients with MPS type I (MPS I), also at 1, 3, and 10 years of follow-up. Ninety-two markers of the OLINK inflammation panel were measured and compared with those of age-matched control subjects (n = 31) by using principal component analysis and Wilcoxon rank sum tests with correction. Median age at transplantation was 1.3 years (range, 0.2-4.8 years), and median time of pre-HCT sample to transplantation was 0.1 year. Normal leukocyte enzyme activity levels were achieved in 93% of patients post-HCT. Pretransplant samples showed clear separation of patients and control subjects. Markers that differentiated pre-HCT between control subjects and patients were mainly pro-inflammatory (50%) or related to bone homeostasis and extracellular matrix degradation (33%). After 10 years' follow-up, only 5 markers (receptor activator of nuclear factor kappa-Β ligand, osteoprotegerin, axis inhibition protein 1 [AXIN1], stem cell factor, and Fms-related tyrosine kinase 3 ligand) remained significantly increased, with a large fold change difference between patients with MPS I and control subjects. In conclusion, systemic inflammation is present in untreated MPS patients and is reduced upon treatment with HCT. Markers related to bone homeostasis remain elevated up to 10 years after HCT and possibly reflect the ongoing skeletal disease, making them potential biomarkers for the evaluation of new therapies.

Toward proteome-wide exploration of proteins in dried blood spots using liquid chromatography-coupled mass spectrometry

Dried blood spot (DBS) sampling is a method with advantages over conventional blood sampling in relation to collection, cost, storage, and transportation. Such advantages have led to its wide use in newborn screening (NBS). Although target analysis of various biomolecules is conducted in NBS, protein quantification-based NBS is still in its infancy. Thus, it is important to clarify how many proteins could be quantitatively detected in DBS samples using advanced liquid chromatography-mass spectrometry (LC-MS/MS) technologies; a catalog of proteins detectable in DBSs by LC-MS/MS will enable us to judge which causative proteins in genetic diseases can be monitored at the protein level in NBS. In this review, we outline conventional proteome analyses of DBSs with a distinction between target and nontarget approaches. Additionally, we discuss the future perspectives for proteome analysis of DBSs in NBS of genetic diseases. This article is protected by copyright. All rights reserved.

Maternal antibodies to gliadin and autism spectrum disorders in offspring-A population-based case-control study in Sweden

While individuals diagnosed with autism spectrum disorders (ASD) have higher levels of antibodies directed towards gliadin, a component of wheat gluten, no study has examined anti-gliadin antibodies (AGA) in etiologically relevant periods before diagnosis. The objective of this study was to investigate if maternal levels of AGA, during pregnancy and at the time of birth, are associated with ASD in offspring. We analyzed AGA in archived neonatal dried blood spots (NDBS) for 921 ASD cases and 1090 controls, and in paired maternal sera collected earlier in pregnancy for a subset of 547 cases and 428 controls. We examined associations with ASD diagnoses as a group and considering common comorbidities (intellectual disability [ID] and attention-deficit/hyperactivity disorder). We compared 206 cases to their unaffected siblings to examine the potential for confounding by shared familial factors. Odds of ASD tended to be lower among those with the highest levels (≥90th percentile) of AGA compared to those with low levels (<80th percentile; OR 0.78, 95% CI 0.56-1.09, measured in NDBS). This pattern was more apparent for ASD with comorbid ID when measured in NDBS (0.51, 0.30-0.87), with a similar trend in maternal sera (0.55, 0.24-1.29). High levels of AGA were similarly associated with lower odds of ASD in the sibling comparison. In summary, we found little association between maternal antibodies raised against components of gluten and risk of ASD in general. Exposure to high levels of AGA in the pre- and perinatal periods may be protective in terms of risk for ASD with ID. LAY SUMMARY: There is a debate among both scientists and community members as to whether an immune reaction to gluten exposure could be considered a cause of autism. We examined antibodies that are directed against gliadin, a part of gluten, in samples collected from pregnant mothers and their newborn babies. We did not see any major differences in the antibody level among those children diagnosed with ASD or their mothers compared to children who were not diagnosed with ASD. High levels of the antibodies were in fact associated with a somewhat lower risk of ASD with co-occurring intellectual disabilities, though we cannot tell from this study why that might be the case.

Validation of a combined ELISA to detect IgG, IgA and IgM antibody responses to SARS-CoV-2 in mild or moderate non-hospitalised patients

BACKGROUND

Frequently SARS-CoV-2 results in mild or moderate disease with potentially lower concentrations of antibodies compared to those that are hospitalised. Here, we validated an ELISA using SARS-CoV-2 trimeric spike glycoprotein, with targeted detection of IgG, IgA and IgM (IgGAM) using serum and dried blood spots (DBS) from adults with mild or moderate disease.

METHODS

Targeting the SARS-CoV-2 trimeric spike, a combined anti-IgG, IgA and IgM serology ELISA assay was developed using 62 PCR-confirmed non-hospitalised, mild or moderate COVID-19 samples, ≥14 days post symptom onset and 624 COVID-19 negative samples. The assay was validated using 73 PCR-confirmed non-hospitalised, mild or moderate COVID-19 samples, ≥14 days post symptom onset and 359 COVID-19 negative serum samples with an additional 81 DBSs. The assay was further validated in 226 PCR-confirmed non-hospitalised, mild or moderate COVID-19 samples, ≥14 days post symptom onset and 426 COVID-19 negative clinical samples.

RESULTS

A sensitivity and specificity of 98.6% (95% CI, 92.6-100.0), 98.3% (95% CI, 96.4-99.4), respectively, was observed following validation of the SARS-CoV-2 ELISA. No cross-reactivities with endemic coronaviruses or other human viruses were observed, and no change in results were recorded for interfering substances. The assay was stable at temperature extremes and components were stable for 15 days once opened. A matrix comparison showed DBS to correlate with serum results. Clinical validation of the assay reported a sensitivity of 94.7% (95% CI, 90.9-97.2%) and a specificity of 98.4% (95% CI, 96.6-99.3%).

CONCLUSIONS

The human anti-IgGAM SARS-CoV-2 ELISA provides accurate and sensitive detection of SARS-CoV-2 antibodies in non-hospitalised adults with mild or moderate disease. The use of dried blood spots makes the assay accessible to the wider community.

Cancer diagnostics based on plasma protein biomarkers: hard times but great expectations

Cancer diagnostics based on the detection of protein biomarkers in blood has promising potential for early detection and continuous monitoring of disease. However, the currently available protein biomarkers and assay formats largely fail to live up to expectations, mainly due to insufficient diagnostic specificity. Here, we discuss what kinds of plasma proteins might prove useful as biomarkers of malignant processes in specific organs. We consider the need to search for biomarkers deep down in the lowest reaches of the proteome, below current detection levels. In this regard, we comment on the poor molecular detection sensitivity of current protein assays compared to nucleic acid detection reactions, and we discuss requirements for achieving detection of vanishingly small amounts of proteins, to ensure detection of early stages of malignant growth through liquid biopsy.

Clinical Validation of a Dried Blood Spot Assay for 8 Antihypertensive Drugs and 4 Active Metabolites

BACKGROUND

Drug nonadherence is one of the major challenges faced by resistant hypertension patients, and identification of this problem is needed for optimizing pharmacotherapy. Dried blood spot (DBS) sampling is a minimally invasive method designed to detect and determine the degree of nonadherence. In this study, a DBS method for qualifying 8 antihypertensive drugs (AHDs) and 4 active metabolites was developed and validated using ultra high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS).

METHOD

The DBS assay was validated analytically and clinically, in accordance with FDA requirements. Analytical validation was accomplished using UHPLC-MS/MS. For clinical validation, paired peak and trough levels of DBS and plasma samples were simultaneously collected and comparatively analyzed using Deming regression and Bland-Altman analyses. All concentrations below the set lower limit were excluded. Deming regression analysis was used to predict comparison bias between the collected plasma and DBS samples, with DBS concentrations corrected accordingly.

RESULTS

The UHPLC-MS/MS method for simultaneously measuring 8 AHDs and their metabolites in DBS, was successfully validated. With Deming regression no bias was observed in N = 1; constant bias was seen in N = 6 and proportional bias in N = 11 of the AHDs and metabolites. After correction for bias, only one metabolite (canrenone) met the 20% acceptance limit for quantification, after Bland-Altman analyses. In addition, amlodipine, valsartan, and [enalaprilate] met the 25% acceptance limit.

CONCLUSIONS

A novel DBS assay for simultaneously qualifying and quantifying 8 AHDs and their metabolites, has been successfully developed and validated. The DBS assay is therefore a suitable method to detect drug nonadherence. However, with the exception of canrenone, the interchangeable use of plasma and DBS sampling to interpret drug quantities should be avoided.

Evaluation of 92 cardiovascular proteins in dried blood spots collected under field-conditions: Off-the-shelf affinity-based multiplexed assays work well, allowing for simplified sample collection

Workplace-collected blood spots deposited on filter paper were analysed with multiplexed affinity-based protein assays and found to be suitable for proteomics analysis. The protein extension assay (PEA) was used to characterize 92 proteins using 1.2 mm punches in repeated samples collected from 20 workers. Overall, 97.8% of the samples and 91.3% of the analysed proteins passed quality control. Both within and between spot correlations using six replicates from the same individual were above 0.99, suggesting that comparable levels are obtained from multiple punches from the same spot and from consecutive spots. Protein levels from dried blood and wet serum from the same individuals were compared and the majority of the analysed proteins were found to be significantly correlated. These results open up for simplified sample collection of blood in field conditions for proteomic analysis, but also highlight that not all proteins can be robustly measured from dried whole blood.

Mind the Quality Gap When Banking on Dry Blood Spots

Dry blood spots (DBS) offer many advantages over other blood banking protocols due to the reduction of time and equipment needed for collection and the ease of processing, storage, and shipment. In addition, the sample size makes it a very attractive method when considering the banking of small pediatric samples. On that note, the Centers for Disease Control and Prevention (CDC) preanalytical standards for DBS are commonly used in the worldwide mass spectrometry-based inborn errors of metabolism screening programs. However, these guidelines may not apply for analytes and protocols not included in these programs. In fact, the availability of leftover samples and the ongoing interest in protocols outside this scenario are providing us with new DBS biobanking insights. Herein, we review the literature for indicators that should be considered in the design of prospective fit for purpose DBS biobanks, especially for those focused mostly on pediatric and OMIC platforms.

Volumetric Absorptive Microsampling of Blood for Untargeted Lipidomics

In the present, proof-of-concept paper, we explore the potential of one common solid support for blood microsampling (dried blood spot, DBS) and a device (volumetric absorptive microsampling, VAMS) developed for the untargeted lipidomic profiling of human whole blood, performed by high-resolution LC-MS/MS. Dried blood microsamples obtained by means of DBS and VAMS were extracted with different solvent compositions and compared with fluid blood to evaluate their efficiency in profiling the lipid chemical space in the most broad way. Although more effort is needed to better characterize this approach, our results indicate that VAMS is a viable option for untargeted studies and its use will bring all the corresponding known advantages in the field of lipidomics, such as haematocrit independence.

Collection and storage of DNA-containing biomaterial and isolated DNA

The advances of biomedicine include the new technologies, diagnosis and treatment techniques, as well as the practical use of new types of biological targets, in particular, nucleic acids. Genomic deoxyribonucleic acid (DNA), extracellular DNA (exDNA) and microbiome DNA obtained from different types of samples (tissues, blood and its derivatives, feces, etc.) are used as objects of genetic research. The use of new technologies for DNA analysis required the development of standardized methods for processing biological samples in order to obtain high-quality DNA samples. The research uses various methods for collecting, preparing samples and storing various DNA-containing biomaterials and isolated DNA, as well as methods for assessing the quality of samples and biobank standards. It is obvious that the use of uniform standards will allow large-scale genetic research on the basis of biobanks and research laboratories. Specialists from professional organizations such as International Society for Biological and Environmental Repositories (ISBER), Biobanking and BioMolecular Resources Research Infrastructure-European Research Infrastructure Consortium (BBMRI-ERIC), European, Middle Eastern & African Society for Biopreservationa and Biobanking (ESBB) and the Russian National Association of Biobanks and Biobanking Professionals.

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.

Newborn Dried Blood Spots for Serologic Surveys of COVID-19

There is an urgent need for inexpensive, population-wide surveillance testing for COVID-19. We tested newborn dried blood spot (DBS) anti-SARS-CoV-2 antibodies for all infants born at Yale from March to May 2020, and found that newborn DBS serologies reflect maternal and population-wide infection rates during the study period. This suggests a role for DBS in COVID-19 surveillance in areas where viral testing is limited.

On the road of dried blood spot sampling for antidoping tests: Detection of GHRP-2 abuse

Dried blood spots (DBSs) sampling is gaining support by the antidoping community because of simplicity and cost-effective characteristics, especially in collection, transport, and storage. Nevertheless, DBS applicability demands specific studies for each of the analytes proposed for testing. Here, GHRP-2 has been selected as a representing member of the growth hormone-releasing peptides (GHRPs) family to provide further evidence of DBS suitability for GHRPs abuse detection in sport testing. An analytical procedure to extract GHRP-2 and its main metabolite (AA-3) from DBS and to detect them by liquid chromatography-tandem mass spectrometry (LC-MS/MS) has been developed. The method has been validated for the detection of GHRP-2. Specificity and identification capabilities have been assessed in agreement with antidoping guidelines. The low AA-3 levels found in DBS samples prevented its effective application for the determination of this metabolite. The limit of detection (LoD) for GHRP-2 has been established at 50 pg/ml. Long-term stability (>2 years) has been confirmed. The procedure has been successfully applied to actual DBS samples from an administration study with a single intravenous dose of GHRP-2 (100 μg) being detected up to 4 h after drug injection. GHRP-2 concentrations have been higher in venous blood DBS than in capillary blood DBS. Despite the observed differences, a similar detection window has been achieved independently of the type of blood used. In summary, this study provides specific evidence supporting DBS usefulness to detect GHRP-2, and potentially other GHRPs family members, for antidoping tests.

Fully automated dried blood spot sample handling and extraction for serological testing of SARS-CoV-2 antibodies

At the beginning of 2020, an outbreak of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) reached pandemic dimensions. Throughout the event, diagnostic tests function as an essential tool for understanding, mitigating, and implement strategies to curb and reduce infections. Here, we present a novel method for the fully automated dried blood spot (DBS) sample handling and extraction for serological testing of human IgG antibodies against SARS-CoV-2 using a commercial enzyme-linked immunosorbent assay (ELISA) testing kit. This proof-of-principle pilot study successfully demonstrates the recovery of antibodies in their intact form from DBS using automated, direct sample elution within 100 μl of extraction buffer. The use of minimally invasive DBS sampling provides an alternative to existing analytical procedures such as sampling by venipuncture or nasal swabs. Due to the ease of DBS collection, no third party need be involved, making at-home sampling possible (e.g., during quarantine).

The preventive strategy for pandemics in the elderly is to collect in advance samples & data to counteract chronic inflammation (inflammaging)

Fighting the current COVID-19 pandemic, we must not forget to prepare for the next. Since elderly and frail people are at high risk, we wish to predict their vulnerability, and intervene if possible. For example, it would take little effort to take additional swabs or dried blood spots. Such minimally-invasive sampling, exemplified here during screening for potential COVID-19 infection, can yield the data to discover biomarkers to better handle this and the next respiratory disease pandemic. Longitudinal outcome data can then be combined with other epidemics and old-age health data, to discover the best biomarkers to predict (i) coping with infection & inflammation and thus hospitalization or intensive care, (ii) long-term health challenges, e.g. deterioration of lung function after intensive care, and (iii) treatment & vaccination response. Further, there are universal triggers of old-age morbidity & mortality, and the elimination of senescent cells improved health in pilot studies in idiopathic lung fibrosis & osteoarthritis patients alike. Biomarker studies are needed to test the hypothesis that resilience of the elderly during a pandemic can be improved by countering chronic inflammation and/or removing senescent cells. Our review suggests that more samples should be taken and saved systematically, following minimum standards, and data be made available, to maximize healthspan & minimize frailty, leading to savings in health care, gains in quality of life, and preparing us better for the next pandemic, all at the same time.

Untargeted metabolomics profiling and hemoglobin normalization for archived newborn dried blood spots from a refrigerated biorepository

Archived dried blood spots (DBS) following newborn screening are an attractive resource for interrogating early-life biology using untargeted metabolomics. Therefore, they have the potential to substantially aid etiological studies, particularly for rare and low-frequency childhood diseases and disorders. However, metabolite quantification in DBS is hindered by variation sources not present in serum and plasma samples such as the hematocrit effect and unknown initial blood volumes. Hemoglobin (Hb) is an appropriate correlate for hematocrit in experimentally-generated DBS punches. However, since many biorepositories worldwide archive DBS at 4-5 °C, there is a need to validate the utility of Hb for DBS archived under refrigeration. We evaluated two simple spectroscopic methods for measuring Hb in DBS stored at 4 +/- 2 °C for up to 21 years, obtained from the newborn screening program at the Karolinska University Hospital, Sweden. Spearman correlation analysis and Akaike Information Criterion model selection found that measurement of a Hb sodium lauryl sulfate complex at 540 nm better described nuisance variation than Hb measured at 404 nm, or using age of spot alone. This is the first study to profile metabolites and to propose a normalization factor for metabolite measurements from DBS archived for decades at 4 °C.