ABSTRACT
Left ventricular pseudoaneurysm (PsA) is a rare complication of radiofrequency ablation (RFA) of cardiac arrhythmias. Presentation can vary widely in terms of timeline, signs, and symptoms. Idioventricular rhythm is a rare presentation of PsA post-ablation. No cases of post-ablation PsA presenting with idioventricular rhythm have been reported in the literature to date. A 72-year-old male presented with symptomatic idioventricular rhythm 34 days post RFA for premature ventricular complexes (PVCs). A PsA involving the distal anterolateral of his left ventricle wall was identified on transthoracic echo and computed tomography (CT). This patient underwent surgical patch repair which resolved his ventricular arrhythmia.
ABSTRACT
Secretin receptor (SR), only expressed by cholangiocytes, plays a key role in the regulation of biliary damage and liver fibrosis. The aim of this study was to determine the effects of genetic depletion of SR in Mdr2-/- mice on intrahepatic biliary mass, liver fibrosis, senescence, and angiogenesis. 12 wk SR-/-, Mdr2-/-, and SR-/-/Mdr2-/- mice with corresponding wild-type mice were used for the in vivo studies. Immunohistochemistry or immunofluorescence was performed in liver sections for (i) biliary expression of SR; (ii) hematoxylin and eosin; (iii) intrahepatic biliary mass by CK-19; (iv) fibrosis by Col1a1 and α-SMA; (v) senescence by SA-ß-gal and p16; and (vi) angiogenesis by VEGF-A and CD31. Secretin (Sct) and TGF-ß1 levels were measured in serum and cholangiocyte supernatant by ELISA. In total liver, isolated cholangiocytes or HSCs, we evaluated the expression of fibrosis markers (FN-1 and Col1a1); senescence markers (p16 and CCL2); microRNA 125b and angiogenesis markers (VEGF-A, VEGFR-2, CD31, and vWF) by immunoblots and/or qPCR. In vitro, we measured the paracrine effect of cholangiocyte supernatant on the expression of senescent and fibrosis markers in human hepatic stellate cells (HHSteCs). The increased level of ductular reaction, fibrosis, and angiogenesis in Mdr2-/- mice was reduced in SR-/-/Mdr2-/- mice. Enhanced senescence levels in cholangiocytes from Mdr2-/- mice were reversed to normal in SR-/-/Mdr2-/- mice. However, senescence was decreased in HSCs from Mdr2-/- mice but returned to normal values in SR-/-/Mdr2-/- mice. In vitro treatment of HHSteCs with supernatant from cholangiocyte lacking SR (containing lower biliary levels of Sct-dependent TGF-ß1) have decreased fibrotic reaction and increased cellular senescence. Sct-induced TGF-ß1 secretion was mediated by microRNA 125b. Our data suggest that differential modulation of angiogenesis-dependent senescence of cholangiocytes and HSCs may be important for the treatment of liver fibrosis in cholangiopathies.
Subject(s)
Cellular Senescence , Cholangitis, Sclerosing/metabolism , Liver Cirrhosis/metabolism , Receptors, G-Protein-Coupled/metabolism , Receptors, Gastrointestinal Hormone/metabolism , Secretin/metabolism , ATP Binding Cassette Transporter, Subfamily B/genetics , Animals , Disease Models, Animal , Hepatic Stellate Cells/metabolism , Humans , Liver/pathology , Male , Mice, Knockout , MicroRNAs/metabolism , Neovascularization, Physiologic , Paracrine Communication , Receptors, G-Protein-Coupled/genetics , Receptors, Gastrointestinal Hormone/genetics , Transforming Growth Factor beta1/metabolism , ATP-Binding Cassette Sub-Family B Member 4ABSTRACT
Activation of the secretin (Sct)/secretin receptor (SR) axis stimulates ductular reaction and liver fibrosis, which are hallmarks of cholangiopathies. Our aim was to define the role of Sct-regulated cellular senescence, and we demonstrated that both ductular reaction and liver fibrosis are significantly reduced in Sct-/-, SR-/-, and Sct-/-/SR-/- bile duct ligated (BDL) mice compared with BDL wild-type mice. The reduction in hepatic fibrosis in Sct-/-, SR-/-, and Sct-/-/SR-/- BDL mice was accompanied by reduced transforming growth factor-ß1 levels in serum and cholangiocyte supernatant, as well as decreased expression of markers of cellular senescence in cholangiocytes in contrast to enhanced cellular senescence in hepatic stellate cells compared with BDL wild-type mice. Secretin directly stimulated the senescence of cholangiocytes and regulated, by a paracrine mechanism, the senescence of hepatic stellate cells and liver fibrosis via modulation of transforming growth factor-ß1 biliary secretion. Targeting senescent cholangiocytes may represent a novel therapeutic approach for ameliorating hepatic fibrosis during cholestatic liver injury.
