Cellular Differentiation of Human Monocytes Is Regulated by Time-Dependent Interleukin-4 Signaling and the Transcriptional Regulator NCOR2

Human in vitro generated monocyte-derived dendritic cells (moDCs) and macrophages are used clinically, e.g., to induce immunity against cancer. However, their physiological counterparts, ontogeny, transcriptional regulation, and heterogeneity remains largely unknown, hampering their clinical use. High-dimensional techniques were used to elucidate transcriptional, phenotypic, and functional differences between human in vivo and in vitro generated mononuclear phagocytes to facilitate their full potential in the clinic. We demonstrate that monocytes differentiated by macrophage colony-stimulating factor (M-CSF) or granulocyte macrophage colony-stimulating factor (GM-CSF) resembled in vivo inflammatory macrophages, while moDCs resembled in vivo inflammatory DCs. Moreover, differentiated monocytes presented with profound transcriptomic, phenotypic, and functional differences. Monocytes integrated GM-CSF and IL-4 stimulation combinatorically and temporally, resulting in a mode- and time-dependent differentiation relying on NCOR2. Finally, moDCs are phenotypically heterogeneous and therefore necessitate the use of high-dimensional phenotyping to open new possibilities for better clinical tailoring of these cellular therapies.

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In vitro monocyte cultures model in vivo inflammatory dendritic cells and macrophages

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Monocyte-derived dendritic cells integrate interleukin-4 signaling time dependently

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NCOR2 controls differentiation of in vitro generated monocyte-derived dendritic cells

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In vitro generated monocyte-derived cells are phenotypically heterogeneous

The transcriptional regulator network of human inflammatory macrophages is defined by open chromatin

Differentiation of inflammatory macrophages from monocytes is characterized by an orderly integration of epigenetic and transcriptional regulatory mechanisms guided by lineage-determining transcription factors such as PU.1. Further activation of macrophages leads to a stimulus- or microenvironment-specific signal integration with subsequent transcriptional control established by the action of tissue- or signal-associated transcription factors. Here, we assess four histone modifications during human macrophage activation and integrate this information with the gene expression data from 28 different macrophage activation conditions in combination with GM-CSF. Bioinformatically, for inflammatory macrophages we define a unique network of transcriptional and epigenetic regulators (TRs), which was characterized by accessible promoters independent of the activation signal. In contrast to the general accessibility of promoters of TRs, mRNA expression of central TRs belonging to the TR network displayed stimulus-specific expression patterns, indicating a second level of transcriptional regulation beyond epigenetic chromatin changes. In contrast, stringent integration of epigenetic and transcriptional regulation was observed in networks of TRs established from somatic tissues and tissue macrophages. In these networks, clusters of TRs with permissive histone marks were associated with high gene expression whereas clusters with repressive chromatin marks were associated with absent gene expression. Collectively, these results support that macrophage activation during inflammation in contrast to lineage determination is mainly regulated transcriptionally by a pre-defined TR network.

Low copy number detection of human bocavirus DNA in bronchoalveolar lavage of asymptomatic adult patients

ABSTRACT 

Aim: The aim of this study was to investigate the percentage of such asymptomatic human bocavirus (HBoV) DNA-shedding patients with a sensitive commercial method. Materials & methods: Bronchoalveolar lavage fluids were analyzed with the xTag® respiratory viral panel (RVP) assay (Luminex, The Netherlands), the RespiFinder® SMART assay (PathoFinder, Maastricht, The Netherlands) and an in-house real-time PCR protocol. Results: While replacing the Luminex xTag RVP assay with the RespiFinder SMART assay for routine diagnostics, surprisingly, more than 50% of bronchoalveolar lavage fluid samples from asymptomatic patients previously tested with negative Luminex xTag RVP tested positive for HBoV. Conclusion: As the RespiFinder SMART assay has a higher sensitivity in the present study, this supports the theory that HBoV persists and is capable of shedding low copy numbers of viral genomes at very low numbers, even in asymptomatic people.

Utility of the QIAGEN/artus PCR assays and Meningofinder™ for the detection of human herpes virus genomes in formalin-fixed paraffin-embedded clinical samples

ABSTRACT: 

Aim: The aim of the study was to analyze whether human herpes viruses can be detected from formalin-fixed paraffin-embedded (FFPE) tissues with two commercial methods. Materials & methods: In total, 91 clinical FFPE samples were analyzed with QIAGEN/artus (Hilden, Germany) qPCRs and the Meningofinder™ assay from PathoFinder (Maastricht, The Netherlands). Results: A total of 27 out of 91 samples were tested for HSV-1 and HSV-2. Three of these 27 samples (11.1%) were positive for HSV-1 and one sample was positive for HSV-2. Out of 91 samples, 50 were tested for CMV, of which six samples were positive (12%). In total, 12 out of 91 samples were tested for the presence of Varizella zoster virus DNA, revealing one as positive (8%). Finally, two samples were tested negative for EBV. Conclusion: Minor differences were identified between both assays, making them a reliable tool for detection of herpes viruses from FFPE material, although this is an off-label use for both assays.