Cytoplasmic domain of tissue factor promotes liver fibrosis in mice

Abstract

AIMTo evaluate the role of tissue factor (TF) and protease activated receptor (PAR)-2 in liver fibrosis.METHODSUsing CCl4 administration for eight weeks, we induced hepatic fibrosis in wild-type C57BL/6 mice and in mice with deletion of the cytoplasmic signalling domain of TF (TF§CT/§CT), deletion of PAR-2 (PAR-2-/-) and combined deletion of TF signalling domain and PAR-2 (TF§CT/§CT/PAR-2-/-). Hepatic fibrosis area was assessed by quantitative imaging of picrosirius red staining. Hepatic collagen content was assessed by hydroxyproline levels. Hepatic stellate cells (αSMA positive) and hepatic macrophages (CD68 positive) were identified by immunohistochemistry. Hepatic gene expression was determined by PCR and liver TGFβ1 content by ELISA.RESULTSCCl4 treated mice with deletion of the PAR-2 gene (PAR-2-/-) and the cytoplasmic domain of TF (TF§CT/§CT) developed significantly less hepatic fibrosis, characterised by reduced liver fibrosis area and hydroxyproline content, compared to control wildtype mice treated with CCl4. The observed reduction in histological fibrosis was accompanied by a significant decrease in the hepatic content of TGFβ, the prototypic fibrogenic cytokine, as well as fewer activated hepatic stellate cells and hepatic macrophages. Deletion of the TF cytoplasmic signalling domain reduced hepatic fibrosis to levels similar to those observed in mice lacking PAR-2 signalling but combined deletion provided no added protection against fibrosis indicating a lack of mutual modulating effects that have been observed in other contexts such as angiogenic responses.CONCLUSIONTissue factor cytoplasmic domain is involved in TF-PAR-2 signalling initiating hepatic fibrosis and is a potential therapeutic target, as its deletion would not impact coagulation.

Coagulation, Microenvironment and Liver Fibrosis

“…This increase was prevented in mice lacking in TF. However, this anti-coagulant phenotype was not associated with a significant reduction of fibrosis [ 37 ], in contrast to other studies [ 30 ].…”

“…In line with this theory, experimental inhibition of PARs prevents the fibrogenic response of HSCs and the progression of fibrosis as demonstrated in pre-clinical studies with animal models of liver disease and cell cultures [ 26 , 28 ]. In addition to PAR-1, PAR-2 showed similar pro-fibrotic effects by inducing HSC contraction, collagen production and MMP-2 expression, this last promoting liver fibrosis due to extracellular matrix remodeling [ 25 , 29 , 30 , 31 ]. Furthermore, studies with PAR −/− transgenic mice confirmed the importance of this receptor in several models of liver fibrosis (xenobiotics, carbon-tetrachloride, CCL 4 , and thioacetamide, TAA) [ 30 , 32 , 33 ] and, recently, even in a model fatty liver disease [ 34 ].…”

“…In addition to PAR-1, PAR-2 showed similar pro-fibrotic effects by inducing HSC contraction, collagen production and MMP-2 expression, this last promoting liver fibrosis due to extracellular matrix remodeling [ 25 , 29 , 30 , 31 ]. Furthermore, studies with PAR −/− transgenic mice confirmed the importance of this receptor in several models of liver fibrosis (xenobiotics, carbon-tetrachloride, CCL 4 , and thioacetamide, TAA) [ 30 , 32 , 33 ] and, recently, even in a model fatty liver disease [ 34 ]. To our knowledge, just one study explored PAR-1 genotype and liver fibrosis in patients with chronic HCV infection.…”

GPCR-induced YAP activation sensitizes fibroblasts to profibrotic activity of TGFβ1

“…Interestingly, all 7 genes that were classified as synergistic were YAP/TAZ targets (Fig 1F, S2 Table) and 9/13 of the genes classified as additive (Fig 1F, S2 Table) were also shown to be regulated by YAP/TAZ [13,[46][47][48][49][50]. Among these genes, CTGF [51,52], IL11 [53], EDN1 [54], SERPINE1/PAI-1 [55], F3/tissue factor [56], CYR61 [57], KLF10 [58], ATF3 [59], FZD8/Frizzled-8 [59] and RUNX1 [60] have been shown to be important profibrotic mediators. Gene expression profiles of these genes are shown in Fig 1G. These results suggested that LPA and TGFβ1 signalling converges on YAP/TAZ and that YAP/TAZ could represent a central node to regulate fibrotic responses.…”

Gli3 is a novel downstream target of miR‑200a with an anti‑fibrotic role for progression of liver fibrosis in�vivo and in�vitro

“…Since hydroxyproline is a basic constituent of collagen structure, its content can serve as indicator of collagen synthesis (23). Hydroxyproline analysis was performed to assess the amount of collagen in liver tissues (24). In brief, the samples were hydrolyzed with 6 M HCl at 130˚C for 12 h. Then, 1 ml hydroxyproline developer (β-dimethylaminobenzaldehyde solution) was added to the samples and standards.…”