Biology subjects

Bormann, D.

Publications and source records attributed to Bormann, D..

3 recordsLinked to original sources

bioRxiv2022

Antithymocyte globulin inhibits CD8+ T cell effector functions via the paracrine induction of PDL-1 on monocytes

Antithymocyte globulins (ATG) are T cell depleting antibodies used in solid organ transplantation for induction therapy in sensitized patients with high risk of graft rejection. Previously described effects besides depletion of T cells suggest additional modes of action and identified further cellular targets. Here, we examined the transcriptional changes arising in immune cells from human blood after ex vivo stimulation with ATG on a single cell level to uncover additional mechanisms by which ATG regulates T cell activity and effector functions. Analysis of the paracrine factors present in plasma of ATG-treated whole blood revealed high levels of chemokines and cytokines including Interferon-{gamma} (IFN-{gamma}). Furthermore, we identify an increase of surface expression of programmed cell death 1 ligand 1 (PDL-1) on monocytes mediated by the released paracrine factors. In addition, we show that this induction is dependent on activation of JAK/STAT signaling via binding of IFN-{gamma} to Interferon-{gamma} receptor 1 (IFN-{gamma}R1). Lastly, we demonstrate that the modulation of the immune-regulatory axis of Programmed cell death protein 1 (PD1) on activated CD8+ T cells with PDL-1 found on monocytes mediated by ATG potently inhibits effector functions including proliferation and granzyme B release of activated T cells. Together our findings represent a novel mode of action by which ATG exerts its immunosuppressive effects. One Sentence SummaryATG increases PDL-1 on CD14+-monocytes and inhibits T cell effector functions.

immunology↗

bioRxiv2022

The effect of paracrine factors released by irradiated peripheral blood mononuclear cells on neutrophil extracellular trap formation

Neutrophil extracellular trap (NET)-formation represents an important defence mechanism for rapid clearance of infections. However, exaggerated NET formation has been shown to negatively affect tissue-regeneration after injury. As our previous studies revealed strong tissue-protective and regenerative properties of the secretome of stressed peripheral blood mononuclear cells (PBMCsec), we here investigated the influence of PBMCsec on the formation of NETs. The effect of PBMCsec on NET formation was assessed ex vivo in ionomycin stimulated neutrophils derived from healthy donors using flow cytometry, image stream analysis and quantification of released extracellular DNA. Molecular mechanisms involved in NET formation that were potentially impaired by PBMCsec treatment, including protein kinase C activity, reactive oxygen species production and peptidyl arginine deiminase 4 activity were analysed. Our results showed that PBMCsec significantly inhibited NET formation. Investigation of the different biological substance classes found in PBMCsec revealed only partial reduction of NET formation, suggesting a synergistic effect. Mechanistically, PBMCsec treatment did not interfere with calcium signalling and PKC-activation, but exerted anti-oxidant activity, as evidenced by reduced levels of reactive oxygen species and upregulation of heme oxygenase 1, hypoxia inducible-factor 1 as well as heat shock protein 27 in PBMCsec-treated neutrophils. In addition, PBMCsec strongly inhibited the activation of peptidyl arginine deiminase 4 (PAD4), ultimately leading to the inhibition of NET formation. As therapeutics antagonizing excessive NET formation are currently not available, our study provides a promising novel treatment option for a variety of conditions resulting from exaggerated NET formation.

immunology↗

bioRxiv2022

Paracrine factors of stressed peripheral blood mononuclear cells activate pro-angiogenic and anti- proteolytic processes in whole blood cells and protect the endothelial barrier

Tissue regenerative properties have been attributed to secreted paracrine factors derived from stem cells and other cell types. Especially, the secretome of {gamma}-irradiated peripheral blood mononuclear cells (PBMCsec) has been shown to possess high tissue-regenerative and pro-angiogenic capacities in a variety of preclinical studies. In the light of future therapeutic intravenous applications of PBMCsec, we investigated possible effects of PBMCsec on circulating white blood cells and endothelial cells lining the vasculature. MethodsTo identify changes in the transcriptional profile of white blood cells treated with PBMCSec, whole blood was drawn from healthy individuals and stimulated with PBMCsec for 8 hours ex vivo before further processing for single cell RNA sequencing (scRNAseq). In addition, we performed in vitro assay to confirm findings arising from the transcriptional profiling. ResultsAddition of PBMCsec to whole blood significantly altered the gene signature of granulocytes (17 genes), T-cells (45 genes), B-cells (72 genes) and most prominently monocytes (322 genes). We detected a strong upregulation of several tissue-regenerative and pro-angiogenic cyto- and chemokines in monocytes, including VEGFA, CXCL1 and CXCL5. Intriguingly, inhibitors of endopeptidase activity, such as SERPINB2, were also strongly induced. Measurement of the trans-endothelial electrical resistance of primary human microvascular endothelial cells revealed a strong barrier-protective effect of PBMCsec after barrier disruption. ConclusionTogether, we show that PBMCsec induces angiogenic and proteolytic processes in the blood and is able to attenuate endothelial barrier damage. These regenerative properties suggest that systemic application of PBMCsec might be a promising novel strategy to restore damaged organs.

cell biology↗