Research

Basic mechanisms and dysregulated pathways of resolution of inflammation (Auflösung von Entzündungsreaktionen – AVE) are characterized by complex interactions between immune cells and biochemically diverse mediators. The resolution phase of inflammation involves the elimination of inflammatory cells and their mediators from sites of infection and injury to restore tissue homeostasis.
The overarching hypothesis of the research linked to the RTG is based on evidence that active and inducible processes are involved in resolution of inflammation (Auflösung von Entzündungsreaktionen – AVE). Basic mechanisms and dysregulated pathways of resolution of inflammation are characterized by complex interactions between immune cells and biochemically diverse mediators. The resolution phase of inflammation involves the elimination of inflammatory cells and their mediators from sites of infection and injury to restore tissue homeostasis. Within the RTG, research projects study the cells and mediators involved in resolution-associated processes as well as the signaling cascades and target structures involved - with the aim of identifying alterations linked to dysregulated resolution of inflammation.
Synergy and added value between the individual research projects are guaranteed by the focus on signals derived from dying cells ➔ Cluster 1, polarization of immune cells ➔ Cluster 2, and restoration of barrier function ➔ Cluster 3. Projects make use of primary human material, preclinically relevant animal models and cellular systems combined with biochemical, molecular biology, pharmacological and systems biology approaches.

Phases resolution of inflammation

Cluster 1:

Signals derived from dying cells

Cell Death is central during inflammation. Immune cells die after activation by pathogen-derived mediators, while other cells loose viability in response to exogenous (paracetamol and other drugs) or endogenous noxes (Fas/FasL, hypoxia). Different modes of cell death are known, including apoptosis, necrosis, or necroptosis. It is not understood how the resolution of inflammation is differentially influenced by these types of cell death. Cluster 1aims to answer this question and comprises three projects:

Project 1:Mechanisms of IL-38 signaling that promote the resolution of inflammation

IL-1 family proteins are critical regulators of inflammation. The new IL-1 family receptor antagonist IL-38, which is released from apoptotic cells, promotes the resolution of inflammation partly due to its impact on pathogenic T cells such as γδ T cells. The project explores other mechanisms of the pro-resolving nature of IL-38, including its impact on the generation of auto-antibodies, and investigates the so-far elusive molecular mechanisms of IL-38 signaling. To achieve these goals in vitro models of immune cell activation, in vivo inflammation models, and patient material will be employed.

Principle Investigators:
Prof. Dr. Andreas Weigert

Institute of Biochemistry 1
Goethe-University Frankfurt

Website

Project 3:Non-hepatic organ-to-liver cross communication in the pathophysiology and resolution of acetaminophen-induced liver injury

Acetaminophen (APAP)-induced acute liver injury (ALI) not only is a continual clinical problem but as experimental protocol a well-established paradigmatic model of drug-induced necroinflammation. Recent studies imply that inter-organ communication may affect course and resolution of APAP-induced ALI, though contributing mechanisms remain elusive. In this PhD project we aim to identify crucial biological signals (e.g. TLR ligands, (bacterial) metabolites, cytokines, hormones) that are derived from non-hepatic sources (e.g. intestine, lung, spleen, adrenal glands) during the acute phase of APAP-induced ALI and potentially feedback on the resolution phase of the intoxication.

Principle Investigator:
Prof. Dr. Heiko Mühl

Institute of General Pharmacology and Toxicology
Goethe-University Frankfurt

Website

Project 13 (associated):Role of TAM receptors in responding to proinflammatory forms of cell death

Recognition and clearance of phosphatidylserine (PS)-expressing apoptotic cells by efferocytosis alters phagocytes activation and promotes the resolution of inflammation (ROI) thereby leading to the establishment of an immune suppressive environment. In acute leukemia, we found that targeting PS-recognition receptors on phagocytes, promotes protective inflammation and elicits anti-leukemic immunity. Because impairment of apoptosis frequently occurs in therapy resistant leukemia, in this project we will (1) evaluate the immunological consequences of necroptosis, a pro-inflammatory form of cell death in which PS is also reported to be exposed, and (2) explore the in vivo therapeutic potential of combined blockade of PS-recognition receptors on phagocytes and necroptosis induction using pre-clinical models of highly aggressive leukemia.

Principle Investigator:
Dr. Hind Medyouf

Georg- Speyer-Haus

Website

Cluster 2:

Polarization of immune cells

Phagocytosis of dying cells, cell debris or pathogens by macrophages and mast cells, is an important process during resolution of inflammation. The projects within cluster 2 deal with polarization of phagocytes induced by endogenous and exogenous signals and explore signal transduction pathways activated or inhibited during phagocyte-induced resolution of inflammation. Cluster 2 comprises five projects:

Project 4:Transcellular biosynthesis of pro-resolving lipid mediators (SPM) in co-incubations of macrophages with dying neutrophils.

Biosynthesis of pro-resolving lipid mediators such as lipoxins and resolvins is dependent on the interplay of macrophage/granulocyte-derived 5- and 15-lipoxygenases (LO). Efferocytosis of dying neutrophils by 15-LO positive macrophages plays a central role in the resolution of inflammation. This projects aims to investigate the mechanism of SPM biosynthesis in co-incubations of human monocyte-derived macrophages with dying neutrophils. For this, monocytes will be isolated from human leukocyte concentrates, in vitro differentiated and co-incubated with neutrophils. Subsequently, expression and interplay of lipoxygenases and other enzymes involved in SPM biosynthesis as well as SPM formation will be investigated.

Principle Investigator:
Prof. Dr. Dieter Steinhilber

Institute of Pharmaceutical Chemistry
Goethe-University Frankfurt

Website

Dr. Astrid Kahnt

Institute of Pharmaceutical Chemistry
Goethe-University Frankfurt

Website

Project 5:Role of soluble epoxide hydroxylase (sHE) in macrophage polarization and resolution of Inflammation

The expression/activity of the soluble epoxide hydrolase (sEH) is important for optimal progenitor cell proliferation and long-term sEH inhibition is detrimental to progenitor cell proliferation, mobilization and vascular repair. We hypothesize that the sEH plays an important role in the regulation of myeloid cell function and aim to determine the role of the sEH in regulating macrophage polarization, lipid storage and foam cell development in the frame of atherosclerosis. Use will be made of available proteomic and metabolomic approaches, pharmacological tools as well as siRNA/CRISPR approaches and genetic mouse models e.g. the myeloid-specific deletion of the sEH.

Principle Investigator:
Prof. Dr. Ingrid Fleming

Institute for Vascular Signalling
Goethe University Frankfurt

Website

Project 6:Translational regulation of the resolution of inflammation in macrophages

Gene expression changes during the course of inflammation and its resolution are rather well established. There is ample evidence that especially during the resolution phase RNA expression changes are strongly controlled on a post-trancriptional level. In the present project, we aim to elucidate the translational changes in macrophages during the resolution of inflammation and characterize the functional impact of translational changes on the course of the resolution phase.

Principle Investigators:
Prof. Dr. Bernhard Brüne

Institute of Biochemistry 1
Goethe-University Frankfurt

Website

PD Dr. Tobias Schmid

Institute of Biochemistry 1
Goethe-University Frankfurt

Website

Project 7:Pro-resolving mediators in mast cells

Mast cells are known for their proinflammatory properties i.e. in promoting allergies. However, they have also the power to suppress immune answers and to promote resolution of inflammation. Here, we aim to identify signals that induce the selective release of antiinflammatory and pro-resolving mediators from mast cells as well as the downstream effector cells targeted by these mediators.

Principle Investigator:
Prof. Dr. Klaus Scholich

Institute of Clinical Pharmacology
Goethe-University Frankfurt

Website

Project 8:The impact of IKKe inhibition on the velocity of atherosclerosis progression: Do T-cells play a role?

In a running PhD project of the graduate school, we investigate the role of IKKe in inflammatory processes of peritonitis and atherosclerosis in mice. Our current results indicate that a deletion of IKKe ameliorates the inflammatory symptoms and leads to an improved health status. Interestingly, by examining immune cells in IKKe knock-out and wild type mice we detected a significantly increased level of specialized T-cells in several tissues of IKKe-depleted mice. In a follow-up project, we now intend to investigate 1. if the effects of IKKε deletion can be mimicked by the specific IKKe inhibitor drug amlexanox and if this drug can enhance the resolution of inflammation, 2. if IKKe deletion in mice slows down the progression of atherosclerosis and 3. if T-cell subsets play a role in IKKe-mediated effects on inflammatory processes.

Principle Investigator:
Prof. Dr. Ellen Niedernberger

Institute of Clinical Pharmacology
Goethe-University Frankfurt

Website

Project 12:SARS-CoV-2 infections in monocytes/macrophages: inflammatory patterns and resolution of inflammation

Systemic and local inflammation associated with organ damage are critical determinants of morbidity and mortality in COVID-19. Several types of immune cells have been proposed as drivers of site-specific inflammation, however, the SARS-CoV-2-induced inflammation patterns in these cells are yet to be determined. This project aims to investigate mechanism of inflammation and its resolution in SARS-CoV-2 infected monocytes/ macrophages and determine if these pathways may prove as a therapeutic target to treat COVID-19 by resolving locally induced inflammation.

Principle Investigator:
Prof. Dr. Denisa Bojkova

Institute of Virology
University Hospital Frankfurt

Website

Cluster 3:

Restoration of barrier function

A key process during inflammation is the loss of epithelial and endothelial barrier function. This enables immune cells to invade the subendothelial space or allows noxious substances to enter the body and trigger immune reactions. Restoration of barrier function is a fundamental principle during the resolution of inflammation. Regeneration of biological barriers requires a crosstalk between cells of the barrier and (anti-inflammatory) immune cells. Underlying signalling pathways are analysed within the three projects of cluster 3:

Project 9:Exploitation of the carbazole-derived kinase inhibitor C81 to promote the resolution of inflammation

Chronic inflammatory diseases are characterized by an impaired resolution of inflammation. This project aims to make use of a natural product-derived kinase inhibitor (synthetic carbazole derivative C81) to promote the resolution of inflammation. The pharmacological action of C81 will primarily be investigated in vitro in human leukocytes: In particular, the influence of C81 on cell functions of macrophages and neutrophils as well as on macrophage polarization processes will be analyzed in detail. Moreover, we will focus on the underlying mechanisms of action with a special emphasis on the kinase signaling network involved.

Principle Investigator:
Prof. Dr. Robert Fürst

Institute of Pharmaceutical Biology
Goethe-University Frankfurt

Website

Project 10:Role of nuclear repressors in the resolution of vascular inflammation

We have identified that some lipid mediators elicit anti-inflammatory responses by the activation of nuclear receptors. Preliminary data suggest that subsequent recruitment of nuclear repressors to segments of the DNA eventually mediate the resolution response. In the project, vascular nuclear repressors will be studied for their function in inflammation resolution in cultured vascular cells and mouse models of the cardiovascular system.

Principle Investigator:
Prof. Dr. Ralf P. Brandes

Institute of Cardiovascular Physiology
Goethe University Frankfurt

Website

Project 11:Reg3b in regeneration and cellular transformation

Using a new transgenic model of Reg3b overexpression in the intestine, we could observe a profound effect of Reg3b in wound healing in an acute model of colitis. Current efforts aim to characterize the exact molecular mechanisms that are controlled by Reg3b with a particular focus on changes in the tumor microenvironment. Moreover, we will elucidate the impact of Reg3b on sporadic intestinal tumorigenesis.

Principle Investigator:
Prof. Dr. Florian Greten

Georg-Speyer-Haus

Website