To evaluate the role of tissue factor (TF) and protease activated receptor (PAR)-2 in liver fibrosis. METHODSUsing CCl<sub>4</sub> administration for eight weeks, we induced hepatic fibrosis in wild-type C...To evaluate the role of tissue factor (TF) and protease activated receptor (PAR)-2 in liver fibrosis. METHODSUsing CCl<sub>4</sub> 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<sup>§CT/§CT</sup>), deletion of PAR-2 (PAR-2<sup>-/-</sup>) and combined deletion of TF signalling domain and PAR-2 (TF<sup>§CT/§CT</sup>/PAR-2<sup>-/-</sup>). 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. RESULTSCCl<sub>4</sub> treated mice with deletion of the PAR-2 gene (PAR-2<sup>-/-</sup>) and the cytoplasmic domain of TF (TF<sup>§CT/§CT</sup>) developed significantly less hepatic fibrosis, characterised by reduced liver fibrosis area and hydroxyproline content, compared to control wildtype mice treated with CCl<sub>4</sub>. 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.展开更多
T-cell regulation by CD52-expressing CD4 T cells appears to operate by two different and possibly synergistic mechanisms. The first is by its release from the cell surface of CD4 T cells that express high levels of CD...T-cell regulation by CD52-expressing CD4 T cells appears to operate by two different and possibly synergistic mechanisms. The first is by its release from the cell surface of CD4 T cells that express high levels of CD52 that then binds to the inhibitory sialic acid-binding immunoglobulin-like lectins-lO （Siglec-lO） receptor to attenuate effector T-cell activation by impairing phosphorylation of T-cell receptor associated Ick and zap-70. The second mechanism appears to be by crosslinkage of the CD52 molecules by an as yet unidentified endogenous ligand that is mimicked by a bivalent anti-CD52 antibody that results in their expansion.展开更多
文摘To evaluate the role of tissue factor (TF) and protease activated receptor (PAR)-2 in liver fibrosis. METHODSUsing CCl<sub>4</sub> 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<sup>§CT/§CT</sup>), deletion of PAR-2 (PAR-2<sup>-/-</sup>) and combined deletion of TF signalling domain and PAR-2 (TF<sup>§CT/§CT</sup>/PAR-2<sup>-/-</sup>). 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. RESULTSCCl<sub>4</sub> treated mice with deletion of the PAR-2 gene (PAR-2<sup>-/-</sup>) and the cytoplasmic domain of TF (TF<sup>§CT/§CT</sup>) developed significantly less hepatic fibrosis, characterised by reduced liver fibrosis area and hydroxyproline content, compared to control wildtype mice treated with CCl<sub>4</sub>. 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.
文摘T-cell regulation by CD52-expressing CD4 T cells appears to operate by two different and possibly synergistic mechanisms. The first is by its release from the cell surface of CD4 T cells that express high levels of CD52 that then binds to the inhibitory sialic acid-binding immunoglobulin-like lectins-lO （Siglec-lO） receptor to attenuate effector T-cell activation by impairing phosphorylation of T-cell receptor associated Ick and zap-70. The second mechanism appears to be by crosslinkage of the CD52 molecules by an as yet unidentified endogenous ligand that is mimicked by a bivalent anti-CD52 antibody that results in their expansion.
