Abstract
Considerable evidence has demonstrated that transforming growth factor β (TGF-β) plays a key role in hepatic fibrosis, the final common pathway for a variety of chronic liver diseases leading to liver insufficiency. Although a few studies have reported that blocking TGF-β with soluble receptors or siRNA can prevent the progression of hepatic fibrosis, as yet no evidence has been provided that TGF-β antagonism can improve pre-existing hepatic fibrosis. The aim of this study was to examine the effects of a murine neutralizing TGF-β monoclonal antibody (1D11), in a rat model of thioacetamide (TAA)-induced hepatic fibrosis. TAA administration for 8 weeks induced extensive hepatic fibrosis, whereupon 1D11 dosing was initiated and maintained for 8 additional weeks. Comparing the extent of fibrosis at two time points, pre- and post-1D11 dosing, we observed a profound regression of tissue injury and fibrosis upon treatment, as reflected by a reduction of collagen deposition to a level significantly less than that observed before 1D11 dosing. Hepatic TGF-β1 mRNA, tissue hydroxyproline, and plasminogen activator inhibitor 1 (PAI-1) levels were significantly elevated at the end of the 8 week TAA treatment. Vehicle and antibody control groups demonstrated progressive injury through 16 weeks, whereas those animals treated for 8 weeks with 1D11 showed striking improvement in histologic and molecular endpoints. During the course of tissue injury, TAA also induced cholangiocarcinomas. At the end of study, the number and area of cholangiocarcinomas were significantly diminished in rats receiving 1D11 as compared to control groups, presumably by the marked reduction of supporting fibrosis/stroma. The present study demonstrates that 1D11 can reverse pre-existing hepatic fibrosis induced by extended dosing of TAA. The regression of fibrosis was accompanied by a marked reduction in concomitantly developed cholangiocarcinomas. These data provide evidence that therapeutic dosing of a TGF-β antagonist can diminish and potentially reverse hepatic fibrosis and also reduce the number and size of attendant cholangiocarcinomas.
Highlights
Liver cirrhosis is a common end consequence of a variety of chronic liver diseases
Numerous experimental and clinical studies have demonstrated a central role of Transforming growth factor b (TGF-b), and in particular b1, in liver fibrosis [7,8,9]
Studies using engineered TGF-b soluble receptors or siRNA interference technique have directly confirmed a causative role of this cytokine in liver fibrosis [16,17,18,19]
Summary
Liver cirrhosis is a common end consequence of a variety of chronic liver diseases. Its underlying pathology, fibrosis, represents the common response of the liver to toxic, infectious, or metabolic agents [1,2,3]. Considerable evidence has accumulated showing that excess expression of TGFb induces and orchestrates intracellular signaling events leading to increased matrix protein deposition and liver fibrosis [7,8,9]. TGF-b1 is the main isoform mediating liver fibrosis through autocrine and paracrine effects on various hepatic and infiltrating cell types [7,8,9]. This pathological process involves major changes in the regulation of matrix degradation, in which plasminogen activator inhibitor 1 (PAI-1), a downstream effector of TGF-b signaling, may be a key player [10,11]. The role of TGF-b in this context is complex as this molecule promotes epithelial mesenchymal transdifferentiation (EMT), cell invasiveness and metastasis [12,13], whereas in other settings TGF-b functions as a tumor suppressor [14,15]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
