Accurate measurement of extended half-life and unmodified factor VIII low levels with one-stage FVIII assays is dependent on the matrix of calibration curves

INTRODUCTION: The monitoring of factor VIII (FVIII) replacement therapy relies on the accurate measurement of FVIII activity over a large concentration range. However, unexplained overestimation of low FVIII levels has recently been reported with extended half-life recombinant FVIIIs. AIM: The objective of this study was to confirm previous publications indicating that the reagents used to generate the calibration curves determine the accuracy of the measurement of low FVIII levels. METHODS: We generated FVIII calibration curves with FVIII-deficient plasmas or a commercial diluent buffer. We then measured FVIII levels in FVIII-deficient plasma spiked with plasma FVIII, a full-length recombinant FVIII (Advate® , Shire, Brussels, Belgium) and two extended half-life recombinant FVIIIs (Elocta® , Swedish Orphan Biovitrum, Woluwe Saint-Lambert, Belgium and Afstyla® , CSL Behring, Mechelen, Belgium). FVIII levels were also analyzed in spiked samples prediluted two- and fourfold, either in diluent buffer or in FVIII-deficient plasma to evaluate parallelism. RESULTS: Coagulation times of calibration curves generated with diluent buffer were longer than those with FVIII-deficient plasmas. This resulted in an overestimation of FVIII levels lower than 25 IU/dL in spiked samples and in detection of FVIII activity (≥1 IU/dL) in FVIII-deficient plasma. Predilution of samples with diluent buffer rather than with FVIII-deficient plasma also led to discordant results. CONCLUSION: Our data confirm that the generation of calibration curves by dilution in FVIII-deficient plasma is crucial for the accurate measurement of low FVIII levels. When serial dilutions of samples are analyzed, predilution in FVIII-deficient plasma is required to respect the parallelism criteria. These methods should be more generally implemented for coagulation instruments.status: publishe

Nuclear Receptor Nur77 Limits the Macrophage Inflammatory Response through Transcriptional Reprogramming of Mitochondrial Metabolism

Activation of macrophages by inflammatory stimuli induces reprogramming of mitochondrial metabolism to support the production of pro-inflammatory cytokines and nitric oxide. Hallmarks of this metabolic rewiring are downregulation of α-ketoglutarate formation by isocitrate dehydrogenase (IDH) and accumulation of glutamine-derived succinate, which enhances the inflammatory response via the activity of succinate dehydrogenase (SDH). Here, we identify the nuclear receptor Nur77 (Nr4a1) as a key upstream transcriptional regulator of this pro-inflammatory metabolic switch in macrophages. Nur77-deficient macrophages fail to downregulate IDH expression and accumulate higher levels of succinate and other TCA cycle-derived metabolites in response to inflammatory stimulation in a glutamine-independent manner. Consequently, these macrophages produce more nitric oxide and pro-inflammatory cytokines in an SDH-dependent manner. In vivo, bone marrow Nur77 deficiency exacerbates atherosclerosis development and leads to increased circulating succinate levels. In summary, Nur77 induces an anti-inflammatory metabolic state in macrophages that protects against chronic inflammatory diseases such as atherosclerosis. Koenis et al. show that nuclear receptor Nur77 regulates the reprogramming of mitochondrial metabolism in inflammatory macrophages. Nur77-deficient macrophages accumulate higher levels of succinate and produce more pro-inflammatory cytokines and nitric oxide in a succinate dehydrogenase-dependent manner. In vivo, bone marrow Nur77 deficiency exacerbates atherosclerosis and increases circulating succinate levels

Immunohistochemical staining for different proteins in liver samples from dogs with or without extrahepatic (EPHSS) or intrahepatic (IPHSS) portosystemic shunts.

<p>The mean of the specific protein intensity is listed in the table based on semi-quantitative evaluation of immunohistochemically stained liver biopsies. The corresponding P-value compared to the control group is noticed.</p

Heatmap EHPSS vs IHPSS.

<p>107 annotated probes (listed in rows) were expressed significantly differently in the 32 dogs with extrahepatic portosystemic shunts (EHPSS; red columns) and 15 dogs with intrahepatic portosystemic shunts (IHPSS; yellow columns) compared with control dogs.</p

Samples from dogs with extrahepatic portosystemic shunts (EHPSS) or intrahepatic portosystemic shunts (IHPSS) used for microarray or qualitative PCR analysis.

<p>Samples from dogs with extrahepatic portosystemic shunts (EHPSS) or intrahepatic portosystemic shunts (IHPSS) used for microarray or qualitative PCR analysis.</p