Pooled Human Plasma Research Articles

Unified calibration of D-dimer can improve the uniformity of different detection systems

BackgroundD-dimer at a low level is important evidence for excluding the onset and progression of thrombosis. It is readily detectable and yields rapid results, although significant variability exists among different detection systems. Our study aims to enhance the consistency across various detection systems. MethodsTwelve detection systems were included in our study. We sought to address this inconsistency by using various calibrators (two supplied by manufacturers and two comprising pooled human plasma diluted with different diluents) to standardize D-dimer measurements. We categorized the data into three groups according to D-dimer concentration levels: low (≤0.5 mg/L), medium (>0.5 mg/L - <3 mg/L), and high (≥3 mg/L). We then analyzed the data focusing on range, consistency, comparability, negative coincidence rate, and false negative rate. ResultsCalibrating with pooled human plasma led to narrower result ranges in the low and medium groups (P < 0.05). In the low group, consistency improved from weak to strong (ICC 0.4–0.7, P﹤0.05), while it remained excellent in the other groups and overall (ICC﹥0.75, P﹤0.05). The percentage of pairwise comparability increased in both the low and high groups. Additionally, there was an increase in the negative coincidence rate. ConclusionThese findings demonstrate that uniform calibration of D-dimer can significantly enhance the consistency of results across different detection systems.

Comparison of reversed-phase, hydrophilic interaction, and porous graphitic carbon chromatography columns for an untargeted toxicometabolomics study in pooled human liver microsomes, rat urine, and rat plasma

IntroductionUntargeted metabolomics studies are expected to cover a wide range of compound classes with high chemical diversity and complexity. Thus, optimizing (pre-)analytical parameters such as the analytical liquid chromatography (LC) column is crucial and the selection of the column depends primarily on the study purpose.ObjectivesThe current investigation aimed to compare six different analytical columns. First, by comparing the chromatographic resolution of selected compounds. Second, on the outcome of an untargeted toxicometabolomics study using pooled human liver microsomes (pHLM), rat plasma, and rat urine as matrices.MethodsSeparation and analysis were performed using three different reversed-phase (Phenyl-Hexyl, BEH C18, and Gold C18), two hydrophilic interaction chromatography (HILIC) (ammonium-sulfonic acid and sulfobetaine), and one porous graphitic carbon (PGC) columns coupled to high-resolution mass spectrometry (HRMS). Their impact was evaluated based on the column performance and the size of feature count, amongst others.ResultsAll three reversed-phase columns showed a similar performance, whereas the PGC column was superior to both HILIC columns at least for polar compounds. Comparing the size of feature count across all datasets, most features were detected using the Phenyl-Hexyl or sulfobetaine column. Considering the matrices, most significant features were detected in urine and pHLM after using the sulfobetaine and in plasma after using the ammonium-sulfonic acid column.ConclusionThe results underline that the outcome of this untargeted toxicometabolomic study LC-HRMS metabolomic study was highly influenced by the analytical column, with the Phenyl-Hexyl or sulfobetaine column being the most suitable. However, column selection may also depend on the investigated compounds as well as on the investigated matrix.Graphical abstract

Gold-nanoparticle-embedded membrane (GEM) for highly sensitive multiplexed sandwich immunoassays

For early disease diagnostics, highly sensitive biosensing methods are required to detect disease-related biomolecules in biofluids at low concentrations. Further, for complex diseases such as cancer, multiplexed detection is required to simultaneously measure multiple analytes in a single assay. Current technologies either lack sensitivity, multiplexing capabilities, or require complicated micro/nano-fabrication processes and specialized instrumentation, limiting their broader use in the biomedical research community as well as in clinical diagnostic applications. In this work, we have developed a gold-nanoparticle-embedded membrane (GEM) platform that consists of 3D nitrocellulose membranes preloaded with gold nanoparticles in microliter compartments for highly sensitive, multiplexed metal enhanced fluorescence (MEF)-based detection. After the development of the compartmentalized GEM and the optimization of size, shape, and concentration of the gold nanoparticles to achieve optimal MEF, we demonstrated its application for scalable multiplexed sandwich immunoassays in a microarray format for the quantification of three cancer-related proteins in blood plasma. In PBS buffer solution, the limit of detection for GM-CSF, TNF-α, and EGFR were improved by 287-folds, 949-folds, and 9.8-folds, respectively, when using the GEM compared to conventional ELISA. When spiked in pooled human plasma, low pg/mL sensitivity was also achieved for each protein, demonstrating its application for complex samples. Long-term storage was demonstrated for potential distribution of the GEM for wide availability among the biomedical and clinical community, facilitating technology dissemination. This technology offers simple, highly sensitive, and multiplexed detection capabilities with low reagent and sample consumption, suitable for accurate and early disease diagnostics.

In-house RT-PCR detection of hepatitis A virus in human plasma pools used for the manufacture of medicinal products

Hepatitis A virus (HAV) is the most frequent cause of viral hepatitis worldwide and is transmitted through the fecal-oral route. However, HAV can also be transmitted by blood-derived products. This is due to the fact that viremia occurs during the asymptomatic phase of HAV infection, enabling infected blood or plasma donations to occur. Viral inactivation/removal steps are included during manufacturing of plasmaderived products. However, HAV is a small non-enveloped virus very difficult to remove with traditional viral inactivation procedures. To accomplish European guidelines for pooled human plasma (treated for virus inactivation), plasma manufacturers have been implementing HAV nucleic acid test (NAT) screening on plasma pools. In this study, we validate an in-house multiplex reverse-transcription real-time PCR (RT-PCR) assay targeting HAV RNA and an internal control with hydrolysis probes for amplicon detection. The HAV RNA test was validated by assessing limit of detection, robustness, sensitivity and specificity according to European Pharmacopoeia (Ph. Eur.) guidelines. Our assay is able to detect 100 IU/mL of all human HAV genotypes that have been described so far. The multiplex assay shows remarkable sensitivity with a 95% lower limit of detection of 5.2 IU/mL. Also, our HAV test shows good robustness, precision, and specificity. We conclude that our assay broadly meets the requirements for its purpose. The implementation of this test in the production process of plasma-derived products will increase their safety.

Certification and long-term stability monitoring of low-content folic acid and 5-methyltetrahydrofolate in human plasma certified reference material by isotope dilution ultra-high performance liquid chromatography/tandem mass spectrometry.

A reliable measurement of blood folate levels is necessary in the clinical field to prevent serious diseases such as cognitive impairment and neural tube defects. Herein, the certification of the low-content folic acid (FA) and 5-methyltetrahydrofolate (5-Me-THF) in human plasma certified reference material (KRISS CRM 111-01-018) was performed. A human plasma pool obtained from the Korean Red Cross was used as a CRM candidate. The certification of the human plasma CRM was performed by isotope dilution ultra-performance liquid chromatography/tandem mass spectrometry. Two-dimensional liquid chromatography was employed to confirm the validity of the analytical method for FA due to the susceptibility of FA to matrix effects because of its limited quantity. The CRM stability was evaluated at -20 °C for 2 months and at -70 °C for up to 12 months to determine the certified value of the CRM. The certified value of the CRM was (84.6 ± 4.3) ng kg-1 and (5.80 ± 0.47) μg kg-1 for FA and 5-Me-THF, respectively. The homogeneity of the CRM was 1.64% and 3.10% for FA and 5-Me-THF, respectively. Further long-term stability assessments were conducted, indicating that the CRM remains valid for at least 58 months at -70 °C for FA and 48 months for 5-Me-THF. Compared to other blood-based CRMs, this CRM has lower folate levels, making it helpful in establishing analytical methods for a broader range of folate levels.

Blood‐derived extracellular vesicles phosphoproteome as a resource of biomarker candidates for Alzheimer’s disease

AbstractBackgroundProtein phosphorylation plays a crucial role in cell communication, signaling and by extension is relevant to Alzheimer´s disease (AD) pathogenesis. Extracellular vesicles (EVs) are recognized as important mediators in intercellular communication and can be isolated from peripheral biofluids, where the content reflects the cellular origin. EVs’ role in AD pathophysiology and their value as biomarker resources is being unraveled. However, little is known regarding EVs’ phosphoproteome in AD and it has still to be determined if blood‐derived EVs are suitable for phosphoproteome profiling. Hence, this work aimed to characterize plasma‐derived EVs (pdEVs) and plasma supernatant EVs free (plasma‐depleted EVs) phosphoproteomes, to potential unravel disease mechanisms and/or new biomarker candidates for AD.MethodA pool of human plasma was used for pdEVs isolation using a precipitation‐based methodology. Both pdEVs and plasma‐depleted EVs samples were analyzed using an antibody‐based phosphospecific microarray. Characterization of the phosphoproteomes obtained was achieved by Gene Ontology enrichment analysis and the most relevant Reactome pathways associated, using ClueGo and CluePedia plugins from Cytoscape v3.9.1. In addition, protein‐protein interaction network of the pdEVs phosphoproteome was retrieved from STRING database and analyzed using Cytoscape “Network Analyzer”, employing the betweenness centrality option to highlight central nodes. Further, the pdEVs phosphoproteome (corresponding gene names) was overlapped with a list of genes associated with AD, collated from DisGenet database.ResultsMore than 70 proteins were enriched ≥40% in bdEVs when compared to plasma‐depleted. Top biological processes were mainly related to cell proliferation/division, apoptosis and phosphorylation. Reactome pathways analysis revealed terms associated to toll like receptor cascade and MAPK signaling. In the network constructed for the pdEVs enriched proteins, PTEN appeared as a central node. Additionally, overlap with AD gene list from DisGenet revealed that 60% of the pdEVs phosphoproteome is AD‐related. Among these, several kinases already described in senile plaques and/or neurofibrillary tangles were identified.ConclusionIn sum, bdEVs phosphoproteome is enriched in AD‐related targets, exhibiting potential as a biomarker candidate resource for AD diagnosis.This work was funded by the Alzheimer’s Association under Grant 2019‐AARG‐644347, supported by iBiMED‐UIDB/04501/2020,iBiMED‐UIDB/04501/2020,ADPro‐SAICT‐45‐2021‐02 and TSM individual PhD grant SFRH/BD/145979/2019. Health Ethics Committee ARS Centro(No.012804‐04.04.2012) and CNPD(No.369/2012).

Recovery of 400 Chemicals with Three Extraction Methods for Low Volumes of Human Plasma Quantified by Instrumental Analysis and In Vitro Bioassays.

Human biomonitoring studies are important for understanding adverse health outcomes caused by exposure to chemicals. Complex mixtures of chemicals detected in blood - the blood exposome - may serve as proxies for systemic exposure. Ideally, several analytical methods are combined with in vitro bioassays to capture chemical mixtures as diverse as possible. How many and which (bio)analyses can be performed is limited by the sample volume and compatibility of extraction and (bio)analytical methods. We compared the extraction efficacy of three extraction methods using pooled human plasma spiked with >400 organic chemicals. Passive equilibrium sampling (PES) with polydimethylsiloxane (PDMS) followed by solid phase extraction (PES + SPE), SPE alone (SPE), and solvent precipitation (SolvPrec) were compared for chemical recovery in LC-HRMS and GC-HRMS as well as effect recovery in four mammalian cell lines (AhR-CALUX, SH-SY5Y, AREc32, PPARγ-BLA). The mean chemical recoveries were 38% for PES + SPE, 27% for SPE, and 61% for SolvPrec. PES + SPE enhanced the mean chemical recovery compared to SPE, especially for neutral hydrophobic chemicals. PES + SPE and SolvPrec had effect recoveries of 100-200% in all four cell lines, outperforming SPE, which had 30-100% effect recovery. Although SolvPrec has the best chemical recoveries, it does not remove matrix like inorganics or lipids, which might pose problems for some (bio)analytical methods. PES + SPE is the most promising method for sample preparation in human biomonitoring as it combines good recoveries with cleanup, enrichment, and potential for high throughput.

Quality Control in Targeted GC-MS for Amino Acid-OMICS.

Gas chromatography-mass spectrometry (GC-MS) is suitable for the analysis of non-polar analytes. Free amino acids (AA) are polar, zwitterionic, non-volatile and thermally labile analytes. Chemical derivatization of AA is indispensable for their measurement by GC-MS. Specific conversion of AA to their unlabeled methyl esters (d0Me) using 2 M HCl in methanol (CH3OH) is a suitable derivatization procedure (60 min, 80 °C). Performance of this reaction in 2 M HCl in tetradeutero-methanol (CD3OD) generates deuterated methyl esters (d3Me) of AA, which can be used as internal standards in GC-MS. d0Me-AA and d3Me-AA require subsequent conversion to their pentafluoropropionyl (PFP) derivatives for GC-MS analysis using pentafluoropropionic anhydride (PFPA) in ethyl acetate (30 min, 65 °C). d0Me-AA-PFP and d3Me-AA-PFP derivatives of AA are readily extractable into water-immiscible, GC-compatible organic solvents such as toluene. d0Me-AA-PFP and d3Me-AA-PFP derivatives are stable in toluene extracts for several weeks, thus enabling high throughput quantitative measurement of biological AA by GC-MS using in situ prepared d3Me-AA as internal standards in OMICS format. Here, we describe the development of a novel OMICS-compatible QC system and demonstrate its utility for the quality control of quantitative analysis of 21 free AA and metabolites in human plasma samples by GC-MS as Me-PFP derivatives. The QC system involves cross-standardization of the concentrations of the AA in their aqueous solutions at four concentration levels and a quantitative control of AA at the same four concentration levels in pooled human plasma samples. The retention time (tR)-based isotope effects (IE) and the difference (δ(H/D) of the retention times of the d0Me-AA-PFP derivatives (tR(H)) and the d3Me-AA-PFP derivatives (tR(D)) were determined in study human plasma samples of a nutritional study (n = 353) and in co-processed QC human plasma samples (n = 64). In total, more than 400 plasma samples were measured in eight runs in seven working days performed by a single person. The proposed QC system provides information about the quantitative performance of the GC-MS analysis of AA in human plasma. IE, δ(H/D) and a massive drop of the peak area values of the d3Me-AA-PFP derivatives may be suitable as additional parameters of qualitative analysis in targeted GC-MS amino acid-OMICS.

Abstract P3167: Identification Of Macrophage-specific Markers On Extracellular Vesicles In A Transgenic Mouse Model And Humans

Extracellular Vesicles (EVs) are key mediators of intercellular communication. Macrophages, a prominent type of immune cells, are known to release EVs with distinct contents and functions. The ExoMap mice model provides a platform to investigate tissue-specific EV subpopulations and the complexity of EV heterogeneity. CD169 and CD68 markers are specific to macrophages and have been associated with immune diseases, including Sarcoidosis. Double Transgenic vav-cre/ExoMap mice and appropriate controls were used to assay for immune cell derived EVs. Expression of cre in the vav-expressing cells, leads to expression of humanized CD81 (hsCD81) and mNeonGreen in the immune cells and in their EVs. Size Exclusion Column and immuno-pulldown (IP) with anti-hsCD81 or anti-CD169/CD68 antibodies were used to isolate macrophage-specific EVs. 3 miRNAs (mir223, mir374c, mir412) specific to macrophages were tested using Droplet Digital PCR (ddPCR). To design our human pilot study, we chose patients with active sarcoidosis (n=10), latent sarcoidosis (n=10), healthy controls (n=10) to compare the level of expression of specific immune markers in their blood. Bone marrow cells prepared from vav-cre/ExoMap mice were found to express mNeon Green and hsCD81. IP combined with vesicle flow cytometry defined the presence of hsCD81/mNeonGreen EVs in the plasma of double transgenic mice. Expression of CD68 and CD169 was robust on the EVs isolated using IP with hsCD81 antibodies from Double Transgenic mice. These results are consistent with the immune specificity of the vav-cre expression. Using human pooled plasma, we detected expression of CD68 on the EVs isolated using IP with CD169 antibody, suggesting the presence of both markers on macrophage specific EVs. Our findings support these markers as conserved between mouse and human samples, indicating their potential as universal markers of macrophage-derived EVs. Ongoing experiments aim to comprehensively characterize individual macrophage-derived EVs using the quantitative single molecule localization microscopy (qSMLM). Together, our findings provide a valuable resource for future studies of macrophage-EV communication and could serve in the development of EV-based diagnostic and therapeutic strategies.

Commutability assessment of candidate reference materials for plasma renin activity measurement: current challenges.

This study aims to evaluate the commutability of external quality assessment (EQA) materials and candidate reference materials (RMs) for plasma renin activity (PRA) assay. Commutabilities of 16 candidate RMs were measured along with 40 clinical samples by the four different routine PRA assays, including three LC‒MS/MS assays and onechemiluminescence immunoassay. Sixteen candidate RMs included native/spiked human plasma pools (small-scale pools with <50 individuals) and current EQA materials (large-scale pools with >1,000 individuals). Difference inbias approach and linear regression with prediction interval approach were adopted to determine the commutability. Two-way variance analysis was used to estimate the effects of spiked and pool size on the commutability. Stability and homogeneity studies were performed. Precision and correlation performance of all assays was acceptable. In the difference in bias approach, thecommutability results were not satisfactory (noncommutability: 14/16) and significant sample-specific effects were detected in assay pairs using different incubation buffers. For the prediction interval approach, no commutability was observed in the spiked small-scale pools; EQA materials (4/9) had more satisfactory commutability among all assays than the small-scale pools (2/7); RMs of large-scale pools tend to have better commutability no matter spiked ornot. Commutable RMs were obtainable but challenging. Current EQA materials with relatively good commutability, stability, and homogeneity were appropriate RMs. Large-scale pools are tending to be commutable. Spiking in small-scale pools was not suggested to prepare RMs. MPs adopting a uniform incubation buffer would be preferable for further commutability research.

Solvent/detergent treated pooled human plasma can decrease the recurrence of allergic transfusion reactions in pediatric, adolescent, and young adult patients.

Octaplas is a solvent/detergent (S/D)-treated pooled human plasma indicated for the treatment of thrombotic thrombocytopenic purpura (TTP) as well as multiple coagulation factor deficiency in patients with liver disease or undergoing liver transplantation or cardiac surgery. We aimed at providing pediatric, adolescent, and young adult evidence for the decrease in allergic transfusion reactions (ATRs) with S/D-treated plasma. A single-center retrospective review of patient records was performed from January 2018 through July 2022 for patients who received S/D treated plasma (Octaplas™; Octapharma). A total of 1415 units of S/D-treated plasma were transfused to nine patients at our institution. Patient ages ranged from 13 months to 25 years old. The reason to initiate transfusion with S/D treated plasma in six patients was mild to severe ATR to plasma-containing products and the need for therapeutic plasma exchange (TPE) or plasma transfusions (PTs). TPE or PT was performed for various clinical indications. Average S/D treated plasma volume per TPE or PT ranged from 200 to 1800 mL per event. During the study period, since initiating transfusions with S/D treated plasma, there have been no allergic or other transfusion reactions reported among these patients. We have successfully utilized S/D treated plasma over the last 4.5 years for pediatric, adolescent, and young adult patients who otherwise would have suffered ATR due to necessary TPE or PT. S/D treated plasma is an additional tool that can be utilized by transfusion services, including pediatrics, to safely transfuse their patients.

Expert Consensus on the Use of Human Serum Albumin in Adult Cardiac Surgery.

Expert Consensus on the Use of Human Serum Albumin in Adult Cardiac Surgery.

Ultra-stable silver nanoplates: efficient and versatile colorimetric reporters for dipstick assays.

Noble metal anisotropic nanostructures, such as silver nanoplates (AgNPls), are interesting because they possess enhanced plasmonic properties compared to their spherical counterparts: increased extinction coefficient and tunable maximum of absorption wavelength. However, their use for biosensing application is limited as these structures are intrinsically unstable and, to maintain the anisotropic structure, a coating protecting the metallic surface is required. In this work, we report on the capacity of a thin but robust coating based on calixarene-diazonium salts to maintain the structure anisotropy of silver nanoplates in conditions in which traditionally used coatings fail. We synthesized AgNPls of various sizes and coated them with two different calixarenes, differing by the functional groups attached to their small rim. After characterization of the efficiency of the ligand exchange process between the initial citrate anions and the calixarenes, the chemical and colloidal stabilities of the resulting calixarene-coated AgNPls were compared to citrate-capped AgNPls. A radical improvement of the lifetime of the material from 1 day for AgNPls coated with citrate to more than 900 days for calixarene-coated AgNPls, as well as the stability in acidic conditions, phosphate saline buffer (PBS) or biofluid, were observed. Benefiting from this exceptional robustness, calixarene-coated AgNPls were exploited to design dipstick assays. Rabbit immunoglobulin G (IgG) detection was developed first as proof-of-concept. The optimal system was then used for the detection of Anti-SARS-CoV-2 IgG. In both cases, a picomolar limit of detection (LOD) was achieved as well as the detection in 100% of pooled human plasma. This sensitivity competes with that of ELISA and is better than the one previously obtained with gold or even silver nanospheres for the same target and in similar conditions. Finally, the wide range of colors provided by the AgNPls allowed the design of a multicolor multiplex assay for the simultaneous detection of multiple analytes.

DP-Filter, a Rapid and Ergonomic Device to Remove Direct Thrombin Inhibitor Argatroban from Plasma for Routine Hemostasis Tests

Argatroban is a direct thrombin inhibitor (DTI) used as an effective alternative anticoagulation therapy in patients suffering from heparin-induced thrombocytopenia (HIT), a serious and potentially life-threatening condition. One of its limitations is its need to be administered intravenously in a continuous manner because of its short half-life in patients without hepatic dysfunction. Thus, a transition towards another long-term anticoagulation therapy, for instance with anti-vitamin K drugs, is usually recommended once HIT is no longer acute and platelet count is stabilized. However, during the transition, remaining plasma levels of argatroban may interfere with hemostasis testing used to monitor the patient response to new anticoagulation drug dosage. The DP-Filter is a functional and user-friendly device used for plasma preparation. This device was already proven effective to substitute the second centrifugation step for platelet poor plasma preparation and to remove direct oral anticoagulants from citrated plasma. We aimed to assess the efficacy of the DP-Filter to remove argatroban from human plasma samples in a fast, practical, and ergonomic way. Argatroban was spiked in human normal pooled plasma (NPP) samples at six concentrations (0.0 [Hepes buffer], 0.1, 0.25, 0.5, 1.0 and 2.0 µg/mL). NPP samples were provided by NAB-X biobank from the University of Namur (Belgium) and were collected on March 23rd, 2022. NPP samples were collected from 8 men and 24 women, with mean age of 22 years old (min = 19 ; max = 48) and mean BMI of 23 (min = 19 ; max = 29). Blood samples were collected in accordance with the Declaration of Helsinki following approval by the Ethical Committee of the CHU UCL Namur (Yvoir, Belgium) under the approval number B03920096633. Argatroban levels were assessed in duplicates in spiked NPP samples before and after filtration with DP-Filter using argatroban-calibrated STA-ECAII testing (Argatroban Plasma Calibrator from Hyphen BioMed). Increasing concentrations of argatroban were measured in non-filtered spiked NPP samples while filtration through DP-Filter reduced argatroban levels close to 0.0 µg/mL, even when spiked concentration was as high as 2.0 µg/mL (Figure 1). Among routine coagulation tests, the activated partial thromboplastin time (aPTT) can be used to assess the anticoagulant effect of DTI. Thus, aPTT was used as a sensitive clotting test to assess the performance of the DP-filter to restore the baseline (i.e. in absence of argatroban) clotting capacity of the plasma. This was determined in duplicates using STA-PTT A5 testing with silica as activator. Filtration through DP-Filter was able to restore normal aPTT values, even at the highest tested argatroban concentration (i.e. 2.0 µg/mL). Similar results were obtained on filtered and non-filtered NPP samples spiked with 0.0 µg/mL of argatroban, confirming the absence of impact of DP-Filter on aPTT testing itself (Figure 2). Altogether, our results show that DP-Filter is an effective, rapid and ergonomic tool to remove argatroban from plasma. It can be used in clinical routine to remove the interference of argatroban with hemostasis tests and therefore avoid false positive or false negative results and unnecessary testing. It also emerges as a solution to ease the monitoring of the transition from patient anticoagulation with argatroban to another anticoagulation therapy such as anti-vitamin K drugs. This might be of particular importance in patients suffering from HIT. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

The influence of proteoforms: assessing the accuracy of total vitamin D-binding protein quantification by proteolysis and LC-MS/MS.

Vitamin D-binding protein (VDBP), a serum transport protein for 25-hydroxyvitamin D [25(OH)D], has three common proteoforms which have co-localized amino acid variations and glycosylation. A monoclonal immunoassay was found to differentially detect VDBP proteoforms and methods using liquid chromatography-tandem mass spectrometry (LC-MS/MS) might be able to overcome this limitation. Previously developed multiple reaction monitoring LC-MS/MS methods for total VDBP quantification represent an opportunity to probe the potential effects of proteoforms on proteolysis, instrument response and quantification accuracy. VDBP was purified from homozygous human donors and quantified using proteolysis or acid hydrolysis and LC-MS/MS. An interlaboratory comparison was performed using pooled human plasma [Standard Reference Material® 1950 (SRM 1950) Metabolites in Frozen Human Plasma] and analyses with different LC-MS/MS methods in two laboratories. Several shared peptides from purified proteoforms were found to give reproducible concentrations [≤2.7% coefficient of variation (CV)] and linear instrument responses (R2≥0.9971) when added to human serum. Total VDBP concentrations from proteolysis or amino acid analysis (AAA) of purified proteoforms had≤1.92% CV. SRM 1950, containing multiple proteoforms, quantified in two laboratories resulted in total VDBP concentrations with 7.05% CV. VDBP proteoforms were not found to cause bias during quantification by LC-MS/MS, thus demonstrating that a family of proteins can be accurately quantified using shared peptides. A reference value was assigned for total VDBP in SRM 1950, which may be used to standardize methods and improve the accuracy of VDBP quantification in research and clinical samples.

Apolipoprotein E mimetic peptide COG1410 combats pandrug-resistant Acinetobacter baumannii.

The emergence of pandrug-resistant bacteria breaks through the last line of defense and raises fear among people of incurable infections. In the post-antibiotic era, the pharmaceutical field turns to seek non-conventional anti-infective agents. Antimicrobial peptides are considered a prospective solution to the crisis of antimicrobial resistance. In this study, we evaluated the antimicrobial efficiency of an ApoE mimetic peptide, COG1410, which has been confirmed to exhibit strong neural protective activity and immunomodulatory function. COG1410 showed potent antimicrobial activity against pandrug-resistant Acinetobacter baumannii, even eliminating large inocula (108 CFU/ml) within 30 min. LC99.9 in PBS and 50% pooled human plasma was 2 μg/ml (1.4 μM) and 8 μg/ml (5.6 μM), respectively. Moreover, COG1410 exhibited biofilm inhibition and eradication activity, excellent stability in human plasma, and a low propensity to induce resistance. Although COG1410 easily entered bacterial cytoplasm and bound to DNA nonspecifically, the major mechanism of COG1410 killing was to disrupt the integrity of cell membrane and lead to leakage of cytoplasmic contents, without causing obvious pores on the cell surface or cell lysis. Additionally, transcriptome analysis showed that treatment with COG1410-enriched genes involved a series of oxidation–reduction processes. DCFH-DA probe detected an increased ROS level in the presence of COG1410, indicating ROS was another hit of this AMP. Furthermore, the action of COG1410 did not depend on the electronic interaction with the LPS layer, in contrast to polymyxin B. The strong synergistic interaction between COG1410 and polymyxin B dramatically reduced the working concentration of COG1410, expanding the safety window of the application. C. elegans infection model showed that combined therapy of COG1410 and polymyxin B was capable of significantly rescuing the infected nematodes. Taken together, our study demonstrates that COG1410 is a promising drug candidate in the battle against pandrug-resistant A. baumannii.

Effects of clot contraction on clot degradation: A mathematical and experimental approach

Thrombosis, resulting in occlusive blood clots, blocks blood flow to downstream organs and causes life-threatening conditions such as heart attacks and strokes. The administration of tissue plasminogen activator (t-PA), which drives the enzymatic degradation (fibrinolysis) of these blood clots, is a treatment for thrombotic conditions, but the use of these therapeutics is often limited due to the time-dependent nature of treatment and their limited success. We have shown that clot contraction, which is altered in prothrombotic conditions, influences the efficacy of fibrinolysis. Clot contraction results in the volume shrinkage of blood clots, with the redistribution and densification of fibrin and platelets on the exterior of the clot and red blood cells in the interior. Understanding how these key structural changes influence fibrinolysis can lead to improved diagnostics and patient care. We used a combination of mathematical modeling and experimental methodologies to characterize the process of exogenous delivery of t-PA (external fibrinolysis). A three-dimensional (3D) stochastic, multiscale model of external fibrinolysis was used to determine how the structural changes that occur during the process of clot contraction influence the mechanism(s) of fibrinolysis. Experiments were performed based on modeling predictions using pooled human plasma and the external delivery of t-PA to initiate lysis. Analysis of fibrinolysis simulations and experiments indicate that fibrin densification makes the most significant contribution to the rate of fibrinolysis compared with the distribution of components and degree of compaction (p < 0.0001). This result suggests the possibility of a certain fibrin density threshold above which t-PA effective diffusion is limited. From a clinical perspective, this information can be used to improve on current therapeutics by optimizing timing and delivery of lysis agents.

Complement-Mediated Neutralisation Identified in Ebola Virus Disease Survivor Plasma: Implications for Protection and Pathogenesis.

The 2013–2016 Ebola virus (EBOV) epidemic in West Africa was unprecedented in case numbers and fatalities, and sporadic outbreaks continue to arise. Antibodies to the EBOV glycoprotein (GP) are strongly associated with survival and their use in immunotherapy is often initially based on their performance in neutralisation assays. Other immune effector functions also contribute to EBOV protection but are more complex to measure. Their interactions with the complement system in particular are comparatively under-researched and commonly excluded from cellular immunoassays. Using EBOV convalescent plasma samples from the 2013–2016 epidemic, we investigated antibody and complement-mediated neutralisation and how these interactions can influence immunity in response to EBOV-GP and its secreted form (EBOV-sGP). We defined two cohorts: one with low-neutralising titres in relation to EBOV-GP IgG titres (LN cohort) and the other with a direct linear relationship between neutralisation and EBOV-GP IgG titres (N cohort). Using flow cytometry antibody-dependent complement deposition (ADCD) assays, we found that the LN cohort was equally efficient at mediating ADCD in response to the EBOV-GP but was significantly lower in response to the EBOV-sGP, compared to the N cohort. Using wild-type EBOV neutralisation assays with a cohort of the LN plasma, we observed a significant increase in neutralisation associated with the addition of pooled human plasma as a source of complement. Flow cytometry ADCD was also applied using the GP of the highly virulent Sudan virus (SUDV) of the Sudan ebolavirus species. There are no licensed vaccines or therapeutics against SUDV and it overlaps in endemicity with EBOV. We found that the LN plasma was significantly less efficient at cross-reacting and mediating ADCD. Overall, we found a differential response in ADCD between LN and N plasma in response to various Ebolavirus glycoproteins, and that these interactions could significantly improve EBOV neutralisation for selected LN plasma samples. Preservation of the complement system in immunoassays could augment our understanding of neutralisation and thus protection against infection

44 Endothelial Monolayers Treated with Burn Patient Plasma Exhibit Differential Gene Expression Linked to Cytoskeletal Rearrangement

IntroductionBurn shock is one of the most serious and complex complications suffered by patients following thermal injury. Endothelial dysfunction may play a role in the pathogenesis of burn shock. However, the mechanisms underlying the contribution to pathophysiology are still largely unknown. Previous studies have shown a connection between the rearrangement of cytoskeletal elements leading to increased vascular permeability. The aim of this study was to examine the differential expression of genes involved in cytoskeletal arrangement in endothelial cell monolayers treated with plasma from burn patients.MethodsHuman umbilical vein endothelial cells (HUVECs) were seeded into transwell plates to form confluent monolayers. Plasma was collected from burn patients 4 hours post-admission. HUVEC cells were exposed to 10% multi-donor pooled healthy human plasma (HHP) or burn patient plasma. Monolayers were subsequently incubated with FIT-C Dextran (40,000 kD) for 2 hours. Monolayer permeability was measured with indices calculated by normalizing values to blank wells (transwell inserts) and HHP-treated monolayer FIT-C diffusion. RNA was isolated from these same cells that had increased monolayer permeability and PCR analysis was carried out using an 84 gene array of human cytoskeletal regulators (Qiagen). A Ct value of 35 was used to indicate expression and a fold change of 1.5 to indicate differential expression in the control vs. injured groups.ResultsFour burn patient plasma samples were utilized to create injuries. Patients were mostly male (75%) with a mean age of 50±20 years and mean %TBSA burn of 37±34%. Differential gene expression in burn vs. HHP was compared. Ten genes showed significant upregulation (ARHGDIB, AURKA, AURKB, CCNB2, CIT, IQGAP2, VASP, SSH2, MYLK and DIAPH1). Four genes showed significant downregulation in (FSCN2, ARHGAP6, CYFIP2, CCNA1). Monolayer permeability indices showed statistically significant increases when compared to controls ranging from 3-13.33% (p < .05).ConclusionsThe interplay of burn shock and endothelial dysfunction remains a complex process of which much is unknown. However, RNA analyses of burn patient plasma reveals involvement of multiple cytoskeletal regulators. Furthermore, all these samples show a concurrent increase in permeability indices when compared to controls, further strengthening the association between cytoskeletal rearrangement and endotheliopathy. Future research to better understand the specifics of these pathways could help aid in the development of more targeted treatments of endotheliopathy and burn shock. Cytoskeletal rearrangement may be an interesting target for future work to understand this mechanistic interplay.

Multicenter performance evaluation and reference range determination of a new one-stage factor VIII assay.

IntroductionWe conducted a multicenter evaluation of a new one‐stage factor VIII (FVIII) assay (Roche Diagnostics), intended for the quantitative assessment of FVIII activity. We evaluated the analytical performance of the FVIII assay on the cobas t 711 analyzer.MethodsExperiments performed at three laboratories used 3.2% citrated residual or commercially purchased plasma samples. Five human plasma pools and two controls were used to determine assay within‐run and within‐laboratory precision, and total reproducibility; coefficients of variation (CVs) and/or standard deviations (SDs) were calculated. Lot‐to‐lot variability and method comparison (vs Coagulation FVIII Deficient Plasma/Dade Actin FS Activated PTT reagent/Standard Human Plasma Calibrator on the Sysmex CS‐5100 analyzer; Siemens Healthineers) were evaluated by Passing–Bablok and Deming regression, respectively, and Pearson's r calculated. Assay‐specific reference range was determined using 199 fresh plasma samples from healthy adults, not receiving anticoagulants.ResultsAcross sites, SDs for repeatability were 0.016–0.046 for samples with ≤1.0 international units (IU)/dL FVIII activity; CVs were 0.9%–3.8% for samples with >1.0 IU/dl activity. Among samples with mean FVIII activity 0.344–133 IU/dl, good intermediate precision (SD 0.020 for samples with 0.344 IU/dl activity; CV 1.8%–4.7%) and good total reproducibility (CV 2.0%–13.3%) were observed. The FVIII assay showed excellent lot‐to‐lot variability (Pearson's r = .999) and good correlation with the comparator assay (Pearson's r = .993–.996). The reference range for FVIII activity was 82.2−218.0 IU/dl.ConclusionThe one‐stage FVIII assay demonstrated robust analytical performance on the cobas t 711 analyzer, supporting its use in routine laboratory practice.