Sugimito, Saito et al, Nature 2025
In this paper, we demonstrate homeostatic and fibrosis-independent functions of HSCs. We uncovered similar effects of HSC depletion and HSC-specific ko of R-spondin 3 on liver size, zonation, regeneration, injury and metabolism. Overall, these data demonstrate a hitherto unknown function of HSCs in regulating hepatocytes and liver functions. Moreover, in the course of chronic liver disease, HSCs lose their protective properties, in particular the expression of Rspo3, both in mice and in patients. Absence or loss of Rspo3 is associated with worsened steatotic liver disease (MASLD and ALD) in mice and associated with worsened outcomes in patients. Together, these findings suggest that restoration of HSCs balance towards a protective and homeostatic phenotype may represent a novel therapeutic approach for chronic liver disease.
A great collaboration with the Augustin lab at DKFZ, Heidelberg!
Saito et al, Gastroenterology. 2023 Jun;164(7):1279-1292
Here we showed that the majority of human HCCs have high expression of TAZ, YAP or both and that TAZ is a key driver of HCC growth in mice (sufficient to induce HCC; its inhibition blocks HCC in multiple models). Moreover, multiple TEADs have a key role in driving HCC growth and determining survival in mice and patients. Together, these findings suggests the TAZ-TEAD pathway as a novel therapeutic target for the treatment of HCC. This pathway is partially inhibited by statins, but newly developed TEAD inhibitors exert stronger effects.
A great collaboration with the Wangensteen lab @ Mayo Clinic.
Filliol et al, Nature. 2022 Oct;610(7931):356-365.
Here we demonstrated an overall tumor-promoting role of hepatic stellate cells (HSC) in the development of hepatocellular carcinoma (HCC), which resulted from a progressive imbalance between protective quiescent hepatic stellate cells (cyHSCs) and activated myofibroblastic HSCs (myHSCs). Importantly, myHSCs accumulated outside tumors/prior to tumor development and appeared to promote the development of tumors rather than the progression of already established larger tumors. Protection by cyHSC depended on hepatocyte growth factor (HGF) whereas tumor promotion by myHSC was largely mediated by type I collagen. In summary, our results suggest that restoring the dysbalance between protective cyHSC and tumor-promoting myHSC may reduce the risk for HCC development.
Mederacke, Filliol, Affo et al, Sci Transl Med . 2022 Apr 6;14(639):eabe5795.
Hepatocyte death is closely associated with the development of liver fibrosis in patients and sufficient to trigger fibrosis in mice. Here, we hypothesized that damage-associated molecular patterns (DAMPs) may link epithelial cell death to fibrogenesis in the injured liver. We identified purinergic receptor P2Y14 among several candidates as highly enriched in hepatic stellate cells (HSCs), the main fibrogenic cell type of the liver. Conversely, P2Y14 ligands UDP-glucose and UDP-galactose were enriched in hepatocytes and were released upon different modes of cell death. Ligand-receptor interaction analysis, in vitro experiments with P2Y14 ligands and dead hepatocytes as well as in vivo studies in knockout mice demonstrated that P2Y14 ligands and their receptor constitute a profibrogenic DAMP pathway that directly links cell death to fibrogenesis in the liver.
Affo et al, Cancer Cell. 2021 Jun 14;39(6):866-882
Here we showed a strong tumor-promoting role of cancer-associated fibroblasts (CAF). Genetic tracing and single cell RNA-seq analyses revealed hepatic stellate cells (HSC) as main source of CAF and hub of cell-cell communication in murine and human CCA. Depletion of CAF reduced tumor growth as did HSC-selective deletion of Hgf and Has2. Surprisingly, deletion of type I collagen did not affect the growth of this highly desmoplastic tumor. Our results suggest HSC-derived CAF as therapeutic target for this deadly tumor
Bhattacharjee et al . J Clin Invest. 2021 Jun 1;131(11):e146987.
Here we investigated the role of cancer-associated fibroblasts (CAF) and type I collagen in desmoplastic colorectal and pancreatic liver metastasis. We demonstrated that - similar to cholangiocarcinoma - CAF were derived from hepatic stellate cells (HSC). ScRNA-seq demonstrated that HSC were a hub of cell-cell communication and intensely interacted with tumor cells. Depletion and HSC-selective knockout reveated that HSC promoted tumor growth and lethality, mediated by Hgf and Has2. However, CAF also restricted tumor growth through type I collagen. The tumor-restricting mechanical barrier provided by type I collagen overrides its tumor-promoting effects via induction of stiffness-induced mechanosignaling, e.g. YAP/TAZ.
This rapidly evolving area has become a main focus of the Schwabe lab. We are using single cell and single nucleus RNA-seq and spatial transcriptomics data to understand mechanisms of cell-cell comunication and transcriptional regulation in health and disease. Our main focus lies in analyzing liver fibrosis, non-alcoholic fatty liver disease and hepatocellular carcinoma in patients - as these approaches for the first time allow a deep understanding of the underlying biology and pathobiology. We are combining analyses of transcriptional master regulators and cell-cell interactions by ARACNe, VIPER and CellPhoneDB in patients with genetic forward screens and state-of-the-art mouse models.
Our lab has made key contributions for the understanding of hepatic stellate cell (HSC) functions. We have developed transgenic mice (LratCre) that efficiently label and delete in HSC and demonstrated that HSC are the key contributors to the myofibroblast pool and liver fibrosis (Mederacke et al, Nat Comm 2013); that they can revert to a nearly quiescent state (Troger et al, Gastroenterology 2012); that they promote desmoplastic tumor growth (Affo et al, Cancer Cell 2021; Bhattacharjee et al, J Clin Invest 2021); and have established highly efficient and pure isolation protocols (Mederacke et al, Nature Protocols 2015).
Despite increasing understand of their function, there are many UNSOLVED QUESTIONS. What is their function in the normal liver besides the storage of retinoids? What benefits do HSC activation and fibrosis confer? We do not believe that HSC activation and fibrosis would have evolved without conferring benefits to the host, at last in the short term. Thus, a major goal of our lab is to understand both PROTECTIVE and DISEASE-PROMOTING roles of HSC in mice and men.
A major focus hereby is the understanding of hepatic stellate cell biology in METABOLIC DYSFUNCTION-ASSOCIATED STEATOTIC LIVER DISEASE (MASLD - formerly NAFLD or "fatty liver"). With MASLD affecting about 2 billion people world-wide and fibrosis representing the main determinant of outcomes in MASLD, understanding metabolic HSC functions is essential. We propose that shifting the balance from HSC-mediated disease promotion to HSC-mediated protection can serve as therapy for NASH (please see Sugmito, Saito et al Nature 2025; Schwabe and Brenner, Nat Rev Gastro Hepatol 2025 in press). Likewise, we also apply this concept to HEPATOCELLULAR CARCINOMA (HCC) and have demonstrated that shifting the balance between disease-promoting and protective functions of HSC can prevent the development of HCC (Filliol et al, Nature 2022).
Liver cancer is the third leading cause of cancer death world-wide - the majority of deaths (about 800,000/year) due to hepatocellular carcinoma (HCC). We have witnessed significant advances in the medical therapy of HCC, but nearly all medical therapies (checkpoint inhibitors; anti-angiogenic drugs; multi-kinase inhibitors) act largely or exclusively through the tumor microenvironment.
A recent goal of the Schwabe lab is to discover therapeutic vulnerabilities of HCC tumor cells - using above-described bioinformatic analyses from patients - and to combine this with genetic forward screens and mouse models to find drugs that directly target key pathway in HCC. The ultimate goal is to combine tumor cell-targeted therapies with the existing efficient TME-targeted therapies for highly efficient medical therapy of HCC (similar the amazing advances in the therapy of other solid tumors).
Even the best current therapies extend median survival by only 1-2 months and the great majority of patients with cholangiocarcinoma die within the first 2 years.
The Schwabe lab seeks to develop novel combination therapies that prolong survival significantly longer than current therapies. With a combination of newly developed CRISPRi tools/screens and high throughput drug screening, we have uncovered therapies that can lead to a 5-fold increase in media survival in preclinical mouse models of cholangiocarcinoma. Further studies seek to combine these therapies with existing therapies and to characterize therapy-resistant persister cells.
While the three above areas are our main focus, we have developed expertise in many additional areas in liver research - which is often needed to understand the interconnected and complex biology of liver disease. As such, we have strong expertise in liver regeneration, e.g. induced by partial hepatectomy; primary cell isolation and culture of nearly every liver cell type; genetic tagging and tracing of various liver cell types; induction of cholangiocarcinoma by hydrodynamic tail vein injection; induction of liver metastasis; the microbiome in liver fibrosis (Seki et al, Nat Med 2007) and HCC (Dapito et al, Cancer Cell 2012; Schwabe et al Nat Rev Cancer 2013).
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