Hk Drescher

The Anti-Microbial Peptide LL-37/CRAMP Is Elevated in Patients with Liver Diseases and Acts as a Protective Factor during Mouse Liver Injury

Background: Antimicrobial peptides (AMP) are an important defense mechanism of the innate immune system and can modulate the course of various diseases. However, their significance during liver pathogenesis is currently not well defined. Methods: Patients with liver diseases were analyzed for LL-37/CRAMP, human beta-defensin-2 (hBD2), and complement 5a (C5a) serum levels. Mice deficient in CRAMP (Cathelicidin-related Antimicrobial Peptide), the mouse homolog for human LL-37, were fed with a methionine- and choline-deficient diet (MCD) and underwent bile-duct ligation (BDL). Results: First, serum samples from patients with chronic liver diseases were investigated. Therefore, significantly enhanced levels for LL-37, hBD2, and complement C5a were detected, all of which comprise antimicrobial properties. Next, CRAMP-knockout (CRAMP-KO) mice were investigated, to better define a functional role of LL-37/CRAMP in animal models of liver diseases. MCD feeding and bile-duct ligation of CRAMP-KO mice resulted in an enhanced degree of liver injury during the early treatment phase. MCD feeding in CRAMP-KO mice led to stronger intrahepatic fat accumulation and significantly enhanced matrix remodeling, whereas BDL caused more extensive liver necrosis. At the late 28 days time point, MCD-fed CRAMP-KO mice displayed a higher intrahepatic fat load. Long-term changes in bile-duct-ligated mice included higher collagen content as a sign of enhanced fibrosis progression if CRAMP was absent. Conclusion: The study shows a clear correlation of antimicrobial peptide serum levels in patients with chronic liver diseases. Furthermore, we were able to demonstrate protective functions of LL-37/CRAMP in two independent mouse models of chronic liver injury.

Genetic Nrf2 Overactivation Inhibits the Deleterious Effects Induced by Hepatocyte-Specific c-met Deletion during the Progression of NASH

We have recently shown that hepatocyte-specific c-met deficiency accelerates the progression of nonalcoholic steatohepatitis in experimental murine models resulting in augmented production of reactive oxygen species and accelerated development of fibrosis. The aim of this study focuses on the elucidation of the underlying cellular mechanisms driven by Nrf2 overactivation in hepatocytes lacking c-met receptor characterized by a severe unbalance between pro-oxidant and antioxidant functions. Control mice (c-metfx/fx), single c-met knockouts (c-metΔhepa), and double c-met/Keap1 knockouts (met/Keap1Δhepa) were then fed a chow or a methionine-choline-deficient (MCD) diet, respectively, for 4 weeks to reproduce the features of nonalcoholic steatohepatitis. Upon MCD feeding, met/Keap1Δhepa mice displayed increased liver mass albeit decreased triglyceride accumulation. The marked increase of oxidative stress observed in c-metΔhepa was restored in the double mutants as assessed by 4-HNE immunostaining and by the expression of genes responsible for the generation of free radicals. Moreover, double knockout mice presented a reduced amount of liver-infiltrating cells and the exacerbation of fibrosis progression observed in c-metΔhepa livers was significantly inhibited in met/Keap1Δhepa. Therefore, genetic activation of the antioxidant transcription factor Nrf2 improves liver damage and repair in hepatocyte-specific c-met-deficient mice mainly through restoring a balance in the cellular redox homeostasis.

β7-Integrin and MAdCAM-1 play opposing roles during the development of non-alcoholic steatohepatitis

BACKGROUND & AIMS Non-alcoholic steatohepatitis (NASH) is a leading cause of chronic liver disease in Western countries. It is unclear how infiltrating leukocytes affect NASH-development. Our study aims to investigate the role of the homing/receptor, pair mucosal addressin cell adhesion molecule-1 (MAdCAM-1)/β7-Integrin, on immune cell recruitment and disease progression in a steatohepatitis model. METHODS Constitutive β7-Integrin deficient (β7-/-) and MAdCAM-1 deficient (MAdCAM-1-/-) mice were fed a high fat diet (HFD) for 26weeks or methionine-choline-deficient-diet (MCD) for 4weeks. RESULTS β7-/- mice displayed earlier and more progressive steatohepatitis during HFD- and MCD-treatment, while MAdCAM-1-/- mice showed less histomorphological changes. The anti-oxidative stress response was significantly weaker in β7-/- mice as reflected by a significant downregulation of the transcription factors nuclear-factor(erythroid-derived 2)-like 2 (Nrf2) and heme-oxigenase-1 (HO-1). Additionally, stronger dihydroethidium-staining revealed an increased oxidative stress response in β7-/- animals. In contrast, MAdCAM-1-/- mice showed an upregulation of the anti-oxidative stress response. β7-/- animals exhibited stronger hepatic infiltration of inflammatory cells, especially neutrophils, reflecting earlier steatohepatitis initiation. Expression of regulatory T cell (TReg) markers as well as numbers of anti-inflammatory macrophages was significantly enhanced in MAdCAM-1-/- mice. Those changes finally resulted in earlier and stronger collagen accumulation in β7-/- mice, whereas MAdCAM-1-/- mice were protected from fibrosis initiation. CONCLUSIONS Adhesion molecule mediated effector cell migration contributes to the outcome of steatohepatitis in the HFD- and the MCD model. While MAdCAM-1 promotes steatohepatitis, β7-Integrin unexpectedly exerts protective effects. β7-/- mice show earlier steatohepatitis initiation and significantly stronger fibrosis progression. Accordingly, the interaction of β7-Integrins and their receptor MAdCAM-1 provide novel targets for therapeutic interventions in steatohepatitis. LAY SUMMARY The mucosal addressin cell adhesion molecule 1 (MAdCAM-1) is expressed in livers upon diet-induced non-alcoholic steatohepatitis (NASH). Loss of MAdCAM-1 has beneficial effects regarding the development of NASH - manifested by reduced hepatic oxidative stress and decreased inflammation. In contrast, β7-Integrin-deficiency results in increased steatohepatitis.

Contents Vol. 91, 2015

Founded as ‘Archiv für Verdauungskrankheiten’ 1895 by I. Boas Continued as ‘Gastroenterologia’ 1939–1967 Former Editors: P. Morawitz (1934–1936), R. Staehelin (1937–1943), A. Hurst (1940–1945), W. Löffler (1943–1961), T.C. Hunt (1947–1967), N. Henning (1953–1962), B. Ihre (1953–1967), H. Bartelheimer (1963–1967), M. Demole (1963–1971), H. Kapp (1968–1970), R. Lambert (1972–1978), W. Creutzfeldt (1979–1992), R. Arnold (1993–2003), C. Beglinger (2004–2011), B. Göke (2004–2014)

O28 β7-INTEGRINS AND MADCAM-1 PLAY AN OPPOSING ROLE DURING THE DEVELOPMENT OF NON-ALCOHOLIC STEATOHEPATITIS (NASH)

euglycemic insulin clamp combined with (3-H)-glucose, and suppression of hepatic glucose production (HGP), in 117 subjects. Results: PNPLA3 relative to b-actin expression was 2.0 (1.6–2.8)-fold higher (p < 0.001) in AT than the liver. When related to total adipose and liver tissue masses, PNPLA3 expression was 5.9 (5.1–8.9)-fold higher in AT than the liver (p < 0.001). In the in vivo study, for a given LFAT, insulin sensitivity of AT lipolysis (p < 0.05) and of HGP (p < 0.05) were significantly higher in I148M carriers than noncarriers.