ECM1 Prevents Activation of Transforming Growth Factor β, Hepatic Stellate Cells, and Fibrogenesis in Mice

Abstract

BACKGROUND & AIMS: Activation of TGFB (transforming growth factor b) promotes liver fibrosis by activating hepatic stellate cells (HSCs), but the mechanisms of TGFB activation are not clear. We investigated the role of ECM1 (extracellular matrix protein 1), which interacts with extracellular and structural proteins, in TGFB activation in mouse livers. METHODS:We performed studies with C57BL/6J mice (controls), ECM1-knockout (ECM1-KO) mice, and mice with hepatocyte-specific knockout of EMC1 (ECM1 Dhep ). ECM1 or soluble TGFBR2 (TGFB receptor 2) were expressed in livers of mice after injection of an adeno-associated virus vector. Liver fibrosis was induced by carbon tetrachloride (CCl 4 ) administration. Livers were collected from mice and analyzed by histology, immunohistochemistry, in situ hybridization, and immunofluorescence analyses. Hepatocytes and HSCs were isolated from livers of mice and incubated with ECM1; production of cytokines and activation of reporter genes were quantified. Liver tissues from patients with viral or alcohol-induced hepatitis (with different stages of fibrosis) and individuals with healthy livers were analyzed by immunohistochemistry and in situ hybridization. RESULTS: ECM1-KO mice spontaneously developed liver fibrosis and died by 2 months of age without significant hepatocyte damage or inflammation. In liver tissues of mice, we found that ECM1 stabilized extracellular matrix-deposited TGFB in its inactive form by interacting with av integrins Gastroenterology 2019;157:1352-1367 BASIC AND TRANSLATIONAL LIVER * Authors share co-first authorship.Abbreviations used in this paper: AAV, adeno-associated virus; CLD, chronic liver disease; CCl 4 , carbon tetrachloride; ECM1, extracellular matrix protein 1; ECM1 D;hep , hepatocyte-specific deletion of extracellular matrix protein 1; GAPDH, glyceraldehyde 3-phosphate dehydrogenase;

Quantitative Comparative Proteomics Reveals Candidate Biomarkers for the Early Prediction of Gestational Diabetes Mellitus: A Preliminary Study

“…They hypothesized that this increase in ECM1 protein expression levels results in higher rigidity in the adipose tissue, promoting fibrosis. This hypothesis is supported by a recent study by Fan et al, who demonstrated that high expression levels of ECM1 inhibit transforming growth factor beta (TGFB) activation to prevent liver fibrosis (32). Lee et al investigated the functional role of ECM1 and concluded that it interacts with the epidermal growth factor (EGF) domain of various proteins, including HSPG2, and induce heparin-binding growth factor responses (33).…”

Immunomodulatory Role of the Extracellular Matrix Within the Liver Disease Microenvironment

“…Furthermore, ECM-1 inhibits latent TGF-b1 activation during homeostasis preventing spontaneous fibrogenesis. In fact, ECM-1 supplementation can reverse fibrosis when ECM-1knockout mice are exposed to liver damage (86).…”

“…IL-6 and IL-21 induce ECM-1 expression, which is a positive regulator of TFH cell differentiation in humoral immunity, germinal centre formation and antigen-specific antibody production by antagonising IL-2 signaling (217). Fan et al described ECM-1 as a key mediator of liver tissue homeostasis (86). Depletion of ECM-1 severely affected liver architecture in mice, promoting liver fibrosis development, but without significant inflammation or hepatocyte damage (86).…”

“…Fan et al described ECM-1 as a key mediator of liver tissue homeostasis (86). Depletion of ECM-1 severely affected liver architecture in mice, promoting liver fibrosis development, but without significant inflammation or hepatocyte damage (86). The authors found that ECM-1 was down-regulated in hepatocytes (and potentially other hepatic cell types) after liver damage, which activated TGF-b, probably via interacting with an integrins, and releasing it from deposited latent TGF-b complexes to initiate HSC activation and fibrogenesis.…”

Hepatic Stellate Cells and Hepatocarcinogenesis

“…Furthermore, TET3 was shown to upregulate the TGFB pathway genes TSP1 and TGFBR2, suggesting a positive feedback loop between TET3 and TGFB1 to promote HSC activation and hepatic fibrosis (Xu et al, 2020). In addition to TGFB signaling influencing HSC activation, hepatocyte produced extracellular matrix protein 1 (ECM1) has been shown to suppress TGFB levels and prevent HSC activation in an in vivo ECM1 knockout mouse model (Fan et al, 2019). Although TGFB remains a strong mediator of HSC activation and fibrogenesis, additional profibrogenic cytokines contribute to this process as well.…”