Ohl, K. | Search bioRxiv

bioRxiv2024

CREB determines the expression of ST2 in Tregs and mediates the balance between type 1 and type 2 immune responses

Regulatory T cells (Tregs) are gatekeepers of immune homeostasis and characterized by expression of Foxp3, which maintains Treg identity. Here we demonstrate that in mice with a Foxp3-specific knockout of CREB, enhanced numbers of Tregs are found in vivo in spleen, lung and colon. These Tregs display a reduced Foxp3 expression, but enhanced expression of the IL-33 receptor (ST-2), IL-10, IL-13, and CREM. CREB deficient Tregs were highly suppressive in vitro and prevented disease activity in CD4 T cell mediated transfer colitis in an IL-10 dependent way. Mechanistically CREB fulfils dual roles in Tregs. First it downregulates Foxp3 expression, however in cooperation with CREM, CREB expression in Tregs alters chromatin accessibility to the ST-2 region and thereby influences T cell specific immune responses mediated by IL-10. Brief summary: Mice with a Foxp3-specific knockout of CREB display enhanced expression of IL-13, IL-10, ST-2 and CREM, which prevents gut inflammation GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=140 SRC="FIGDIR/small/601312v2_ufig1.gif" ALT="Figure 1"> View larger version (22K): org.highwire.dtl.DTLVardef@a2d341org.highwire.dtl.DTLVardef@1db6852org.highwire.dtl.DTLVardef@19e024borg.highwire.dtl.DTLVardef@a8c84d_HPS_FORMAT_FIGEXP M_FIG C_FIG Created by Biorender

immunology↗

bioRxiv2023

Towards Biohybrid Lung Development? Inflammatory Conditions Disrupt Endothelial Layer Integrity on Gas Exchange Membranes

Systemic inflammation presents a significant challenge to the long-term function of biohybrid implants. While endothelialisation of biohybrid implants has been shown to improve device hemocompatibility, its feasibility under the influence of patients inflammatory status remains largely unexplored. To investigate this, we developed a controlled in vitro model which allows to study endothelial dysfunction under inflammatory stress. Endothelial cells were cultured on polydimethylsiloxane under physiological shear stress and exposed to lipopolysaccharide (LPS)-activated peripheral blood mononuclear cells (PBMCs), simulating inflammatory conditions. Endothelial morphology and confluence was assessed using immunohistochemistry and scanning electron microscopy. Leukocyte adhesion was evaluated directly as well as indirectly, using flow cytometry to analyse cell adhesion molecules. Quantitative PCR was used for gene expression analysis of inflammatory mediators. Notably, neither LPS nor PBMCs alone induced endothelial disruption, whereas their combination significantly impaired endothelial confluence: Inflammatory activation led to substantial loss of endothelial confluence, increased leukocyte adhesion, and elevated expression of adhesion molecules ICAM-1, VCAM-1, and E-selectin. Gene expression analysis highlights the upregulation of inflammatory mediators, such as IL-6, IL-8, IL-10, and MCP-1. This study underscores the challenges of implementing endothelialisation in biohybrid devices, particularly in patients with systemic inflammation. By considering translational hurdles, this work contributes to the development of clinically viable biohybrid constructs and highlights the importance of considering inflammatory dynamics when designing next-generation implants.

bioengineering↗