Research Area B – Inflammation & fibrosis

Non-alcoholic fatty liver disease (NAFLD) is the most common chronic liver disease worldwide, affecting a staggering 25% of the general population. Its prevalence is expected to rise further with an ageing and more obese world population. NAFLD constitutes a major cause of life-threatening sequelae such as liver cirrhosis or hepatocellular carcinoma. While lifestyle interventions have demonstrated some efficacy, no liver-targeted therapy is currently approved. The Transregio-CRC (CRC/TR) on NAFLD will focus on understanding, preventing and treating NAFLD before the development of late stage complications such as decompensated liver cirrhosis or hepatocellular carcinoma. Our consortium seeks to leverage innovative technologies including single-cell and spatial transcriptomics, lipidomics, and organoid modelling, together with outstanding immunological, clinical and translational expertise, to provide yet unprecedented insight into NAFLD-driving cell interactions and pathomechanisms in patients, followed by subsequent functional validation as well as testing of new therapies in experimental models. Taking advantage of these advances, our interdisciplinary research consortium will focus on a bidirectional bedside-to-bench and bench-to-bedside approach defining and targeting mechanisms that drive the transition from a solely metabolic risk to a disease with liver-specific sequelae and grave prognostic relevance. 

The overarching aim is to gain a holistic understanding of the disease-defining, liver-specific molecular and cellular events in non-alcoholic fatty liver disease.  

Projects in two interrelated research areas (A – metabolic injury, B – inflammation and fibrosis) will aim at understanding heterogeneity in mechanisms of hepatocyte metabolic injury, subsequent inflammatory and fibrogenic responses as well as the underlying cell-cell crosstalk in order to develop novel therapeutic concepts. Central projects will provide relevant cross-sectional technologies such as access to extensively phenotyped patient material, transcriptomics, bioinformatics, science data management and an integrated research training group. Together, we will define the events that govern the transition from benign steatosis to non-alcoholic steatohepatitis (NASH) and the involved key players; understand key drivers of hepatic inflammation and fibrogenesis in NAFLD; elucidate the cross-talk between different cell-types and metabolism – inflammation – fibrosis as well as interrelated feed-forward mechanisms in NAFLD; and apply the above concepts to develop novel therapeutic approaches and concepts of multi-modal combination therapy in NAFLD.  

The CRC/TR 362 in Berlin and Dresden will open prospects for a new generation of rationally designed and personalized treatment approaches that might prevent the liver of at risk individuals progress from metabolic risk to disease. 

Portal zonation is a common histologic feature of pediatric NASH and is associated with a progressive disease course. At this time, the mechanisms defining zonal NASH phenotypes are not resolved yet. We will analyze the metabolic, inflammatory and fibrogenic signatures associated with portal and centrilobular disease phenotypes in a comprehensively characterized cohort of children and adolescents with NAFLD, applying multiplex immunostaining, single-nucleus sequencing and spatial transcriptomics. Mechanistic studies will be performed in patient-derived iPSC lines and organoids of the very same cohort to further validate newly identified therapeutic strategies. 

PI: Christian Hudert / Philip Bufler

Liver macrophages are central in the pathogenesis of non-alcoholic fatty liver disease (NAFLD). We will characterize the phenotypic, spatial and functional heterogeneity of macrophages including cell-cell interactions and identify targetable ligand-receptor pairs by state-of-the-art technologies on human liver, particularly single-cell RNA sequencing and spatial transcriptomics, in conjunction with functional studies in NAFLD mouse models and co-culture systems (‘liver-on-a-chip’). Our findings will provide a comprehensive picture of how hepatic macrophage subsets contribute to altered metabolism, inflammation and fibrosis in NAFLD and opportunities for novel therapeutic strategies.

PI: Frank Tacke

The close crosstalk between hepatocytes and macrophages within the lipid-rich liver microenvironment is a central hub in pathogenesis of non-alcoholic fatty liver disease (NAFLD) as well as its resolution. Here we will focus on phospholipid phosphatase 3 (PLPP3), which regulates lipid metabolism by dephosphorylation of several lipid substrates. We will study the role of PLPP3 in hepatocytes and macrophages in the context of NAFLD pathogenesis and resolution, by using appropriate genetically modified mice and state-of-the-art tools. 

PI: Triantafyllos Chavakis

Kupffer cells are thought to be driving inflammation at the switch from steatosis to non-alcoholic steatohepatitis (NASH). Project B04 will employ dynamic multiparametric intravital microscopy and imaging mass cytometry to delineate critical determinants of altered Kupffer cell identity and functionality in NAFLD progression and regression, including their ontogeny, their response to microbial and nutritional stimuli, and their crosstalk to immune and parenchymal cells. Unraveling Kupffer cell identity will help in identifying novel angles for therapeutic intervention in order to resolve the dichotomy of immune function (beneficial to the host) and disease propagation (harmful to the host) by differentiating KC subsets originating from phenotype switch (plasticity) or ontogenically different subsets (heterogeneity).

PI: Moritz Peiseler / Leke Wiering

Macrophage cellular therapy is emerging as a promising new approach for liver metabolic diseases. We will generate autologous macrophages with defined activation and use state-of-the art technologies, particularly single-cell RNA sequencing, high end imaging and multiparametric flow cytometry, to characterize the transplanted macrophages and their interaction with other cells at different stages of NAFLD. Our work will thoroughly characterize the phenotype and mode of action of transplanted macrophages within the inflamed and fibrotic hepatic microenvironment, and hence their therapeutic potential in NAFLD.

PI: Michael Sieweke / Efstathios Stamatiades

Sensing hepatic cellular stress is a central event in the progression of non-alcoholic fatty liver disease (NAFLD). However, the role of lymphocyte innate sensors in mediating this process remains unclear. By using a combination of multi-omics analyses along with genetic mouse models, we will assess the molecular mechanisms driving the upregulation of stress ligands, define the function of lymphocyte innate sensors and evaluate their impact on modulating NAFLD. Our findings will provide a comprehensive picture of how lymphocyte sensors contribute to NAFLD inflammation and progression and how this might provide novel opportunities for therapeutic interventions.

PI: Christina Stehle / Chiara Romagnani

Innate lymphoid cells (ILC) are involved in tissue homeostasis. Their activity is modulated by microbiota and nutrients. ILC3-derived IL-22 acts on hepatocytes and plays an important role in liver regeneration, while the roles of ILC3 and IL-22 in NAFLD remain poorly studied. Using state-of-the-art in vivo models and gnotobiology techniques, we will explore how intestinal microbiota impacts on hepatic and intestinal ILC3 and on the role of IL-22 in regulating hepatocyte function, during NAFLD and disease regression. Our results will reveal molecular pathways of how ILC3 and IL-22 control tissue recovery from NAFLD in a diet-microbiota dependent manner and might become targets for novel therapies.

PI: Francesca Ronchi / Andreas Diefenbach

Hepatic-MBOAT7 downregulation in obese humans and mice is associated with the development of liver fibrosis. We hypothesise that bioactive lipids secreted by MBOAT7-deficient hepatocytes mediate pro-fibrotic crosstalk with hepatic stellate cells (HSCs) via specific lipid signaling pathways. Using in vitro experiments with mouse/human primary cells and mass spectrometry based lipidomics we will identify molecular players of the proposed signaling mechanism and validate it in vivo using various transgenic mouse models and pharmacological inhibitors. Our findings will identify druggable pathways that drive the MBOAT7-dependent cellular crosstalk and fibrosis.

PI: Pallavi Subramanian / Maria Fedorova

Hepatic stellate cells (HSC) play a central role in the pathogenesis of non-alcoholic steatohepatitis (NASH). Here, we seek to deeply characterize interactions of HSC with infiltrating immune and epithelial cells in NASH. Leveraging state-of-the-art single cell, imaging and spatial transcriptomics, we will characterize ligand-receptor pairs and cell-cell interactions and their spatial context, followed by functional studies of candidates whose expression is conserved between human and murine NASH. We anticipate to uncover disease-promoting and protective ligand-receptor pairs that link distinct HSC subpopulations to immune and epithelial cells and can serve as therapeutic targets in NASH.. 

PI: Linda Hammerich