The Distinct Role of the HDL Receptor SR-BI in Cholesterol Homeostasis of Human Placental Arterial and Venous Endothelial Cells.

As opposed to adults, high-density lipoprotein (HDL) is the main cholesterol carrying lipoprotein in fetal circulation. The major HDL receptor, scavenger receptor class B type I (SR-BI), contributes to local cholesterol homeostasis. Arterial endothelial cells (ECA) from human placenta are enriched with cholesterol compared to venous endothelial cells (ECV). Moreover, umbilical venous and arterial plasma cholesterol levels differ markedly. We tested the hypothesis that the uptake of HDL-cholesteryl esters differs between ECA and ECV because of the differential expression of SR-BI. We aimed to identify the key regulators underlying these differences and the functional consequences. Immunohistochemistry was used for visualization of SR-BI in situ. ECA and ECV were isolated from the chorionic plate of human placenta and used for RT-qPCR, Western Blot, and HDL uptake assays with 3H- and 125I-labeled HDL. DNA was extracted for the methylation profiling of the SR-BI promoter. SR-BI regulation was studied by exposing ECA and ECV to differential oxygen concentrations or shear stress. Our results show elevated SR-BI expression and protein abundance in ECA compared to ECV in situ and in vitro. Immunohistochemistry demonstrated that SR-BI is mainly expressed on the apical side of placental endothelial cells in situ, allowing interaction with mature HDL circulating in the fetal blood. This was functionally linked to a higher increase of selective cholesterol ester uptake from fetal HDL in ECA than in ECV, and resulted in increased cholesterol availability in ECA. SR-BI expression on ECV tended to decrease with shear stress, which, together with heterogeneous immunostaining, suggests that SR-BI expression is locally regulated in the placental vasculature. In addition, hypomethylation of several CpG sites within the SR-BI promoter region might contribute to differential expression of SR-BI between chorionic arteries and veins. Therefore, SR-BI contributes to a local cholesterol homeostasis in ECA and ECV of the human feto-placental vasculature.

Longitudinal Comparison of Automated SARS-CoV-2 Serology Assays in Assessing Virus Neutralization Capacity in COVID-19 Convalescent Sera.

CONTEXT.­: Serologic tests on automated immunology analyzers are increasingly used to monitor acquired immunity against SARS-CoV-2. The heterogeneity of assays raises concerns about their diagnostic performance and comparability. OBJECTIVE.­: To test sera from formerly infected individuals for SARS-CoV-2 antibodies by using 6 automated serology assays and a pseudoneutralization test (PNT). DESIGN.­: Six SARS-CoV-2 serology assays were used to assess 954 samples collected during a 12-month period from 315 COVID-19 convalescents. The tests determined either antibodies against the viral nucleocapsid (anti-NC) or spike protein (anti-S). Two assays did not distinguish between antibody classes, whereas the others selectively measured immunoglobulin G (IgG) antibodies. PNT was used to detect the presence of neutralizing antibodies. RESULTS.­: Comparison of qualitative results showed only slight to moderate concordance between the assays (Cohen κ < 0.57). Significant correlations (P < .001) were observed between the antibody titers from all quantitative assays. However, titer changes were not detected equally. A total anti-S assay measured an increase in 128 of 172 cases (74%) of a suitable subset, whereas all IgG anti-S tests reported decreases in at least 118 (69%). Regarding the PNT results, diagnostic sensitivities of 89% or greater were achieved with positive predictive values of at least 93%. In contrast, specificity changed substantially over time, varying from 20% to 100%. CONCLUSIONS.­: Comparability of serologic SARS-CoV-2 antibody tests is rather poor. Owing to different diagnostic specificities, the tested assays were not equally capable of capturing changes in antibody titers. However, with thoroughly validated cutoffs, IgG-selective anti-S assays are a reliable surrogate test for SARS-CoV-2 neutralizing antibodies in former COVID-19 patients.

Sustainability in Biobanking: Model of Biobank Graz.

Research infrastructures remain the key for state-of-the-art and successful research. In the last few decades, biobanks have become increasingly important in this field through standardization of biospecimen processing, sample storage, and standardized data management. Research infrastructure in cohort studies and other sample collection activities are currently experiencing a lack of long-term funding. In this article, the Biobank Graz discusses these aspects of sustainability including the definition of sustainability and necessity of a business plan, as well as cost calculation model in the field of biobanking. The economic state, critical success factors, and important operational issues are reviewed and described by the authors, using the example of the Biobank Graz. Sustainability in the field of biobanking is a globally important matter of necessity, starting from policy making and ending with security and documentation on each operational level.