NLRP3 inflammasome activation is required for fibrosis development in NAFLD

NLR inflammasomes, caspase 1 activation platforms critical for processing key pro-inflammatory cytokines, have been implicated in the development of nonalcoholic fatty liver disease (NAFLD). As the direct role of the NLRP3 inflammasome remains unclear, we tested effects of persistent NLRP3 activation as a contributor to NAFLD development and, in particular, as a modulator of progression from benign hepatic steatosis to steatohepatitis during diet-induced NAFLD. Gain of function tamoxifen-inducible Nlrp3 knock-in mice allowing for in vivo temporal control of NLRP3 activation and loss of function Nlrp3 knockout mice were placed on short-term choline-deficient amino acid-defined (CDAA) diet, to induce isolated hepatic steatosis or long-term CDAA exposure, to induce severe steatohepatitis and fibrosis, respectively. Expression of NLRP3 associated proteins was assessed in liver biopsies of a well-characterized group of patients with the full spectrum of NAFLD. Nlrp3−/− mice were protected from long-term feeding CDAA-induced hepatomegaly, liver injury, and infiltration of activated macrophages. More importantly, Nlrp3−/− mice showed marked protection from CDAA-induced liver fibrosis. After 4 weeks on CDAA diet, wild-type (WT) animals showed isolated hepatic steatosis while Nlrp3 knock-in mice showed severe liver inflammation, with increased infiltration of activated macrophages and early signs of liver fibrosis. In the liver samples of patients with NAFLD, inflammasome components were significantly increased in those patients with nonalcoholic steatohepatitis (NASH) when compared to those with non-NASH NAFLD with mRNA levels of pro-IL1 beta correlated to levels of COL1A1. Our study uncovers a crucial role for the NLRP3 inflammasome in the development of NAFLD. These findings may lead to novel therapeutic strategies aimed at halting the progression of hepatic steatosis to the more severe forms of this disease.Fil: Wree, Alexander. University of California at San Diego; Estados Unidos. University Hospital Essen; AlemaniaFil: McGeough, Matthew D.. University of California at San Diego; Estados UnidosFil: Peña, Carla A.. University of California at San Diego; Estados UnidosFil: Schlattjan, Martin. University Hospital Essen; AlemaniaFil: Li, Hongying. University of California at San Diego; Estados UnidosFil: Inzaugarat, Maria Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Inmunología, Genética y Metabolismo. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Inmunología, Genética y Metabolismo; ArgentinaFil: Messer, Karen. University of California at San Diego; Estados UnidosFil: Canbay, Ali. University Hospital Essen; AlemaniaFil: Hoffman, Hal M.. University of California at San Diego; Estados Unidos. Ludwig Institute of Cancer Research; Estados UnidosFil: Feldstein, Ariel E.. University of California at San Diego; Estados Unido

Major histocompatibility complex class I-related chains A and B (MIC A/B): A novel role in nonalcoholic steatohepatitis

PubMedID: 19998387Stress-induced soluble major histocompatibility complex class I-related chains A/B (MIC A/B) are increased in chronic liver diseases and hepatocellular malignancy.Weinvestigated the impact of these molecules on liver injury, apoptosis, and fibrosis in nonalcoholic steatohepatitis (NASH). Blood and liver tissue were obtained from 40 patients with NASH undergoing bariatric surgery for obesity. The control group consisted of 10 healthy individuals. We also investigated 10 patients with nonalcoholic fatty liver (NAFL). Polymerase chain reaction was used to measure messenger RNA (mRNA) transcripts of MIC A/B, natural killer cell receptor G2D (NKG2D), CD95/Fas, and tumor necrosis factor-related apoptosis-inducing ligand(TRAIL)-death receptor5(DR5). Apoptosis was quantified by way of terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) (intrahepatic) and M30/M65 (systemic). Liver injury was assessed histopathologically and serologically (alanine aminotransferase/ aspartate aminotransferase). Fibrosis was identified by Sirius red staining, quantitative morphometry, and ?-smooth muscle actin and collagen 1? transcripts. Compared with controls, patients with NASH revealed significant increases in (1) NKG2D mRNA (13.1-fold) and MIC A/B mRNA (3.6-fold and 15.8-fold, respectively); (2) TRAIL-DR5 and CD95/Fas mRNA (2.7-fold and 3.6-fold, respectively); (3) TUNEL-positive hepatocytes (4.0-fold); and (4) M30 and M65 levels (4.6-fold and 3.4-fold, respectively). We found relevant correlations between MIC protein expression rates and NAS and fibrosis stages. In contrast, NKG2D and MIC A/B transcripts were attenuated in patients with NAFL compared with NASH. Histopathologically, NASH patients revealed increased NAS scores, an accumulation of natural killer cells, and 2.7-fold increased hepatic fibrosis by quantitative morphometry. Conclusion: Our findings suggest an important role for MIC A/Bin liver injury. Therapeutic intervention aimed at reducing MICA/B levels may beneficially affect the progression of NASH. Copyright © 2009 by the American Association for the Study of Liver Diseases

Expression of apoptosis- and vitamin D pathway-related genes in hepatocellular carcinoma

PubMedID: 23635474Background/Aims: Hepatocellular carcinoma (HCC) is the sixth most common malignancy worldwide and therapeutic options are scarce. As they might represent future targets for cancer therapy, the expression of apoptosis-related genes in HCC is of particular interest. In this pilot study, we further examined apoptosis-related genes in human HCC and also focused on vitamin D signaling as this might be a regulator of HCC cell apoptosis. Methods: We employed tumor tissue and serum samples from 62 HCC patients as well as 62 healthy controls for these studies. Tissue and serum specimens were analyzed by quantitative RT-PCR, immunohistochemistry and ELISA. Results: In HCC patients the apoptosis marker M30 was found to be elevated and several pro-apoptotic (TRAIL, FasL and FasR) as well as anti-apoptotic genes (Mcl-1 and Bcl-2) were simultaneously upregulated in tumor tissue and especially tumor-surrounding tissue as compared to healthy control livers. Moreover, vitamin D serum levels were decreased in HCC patients whereas vitamin D receptor mRNA expression was increased in tumor tissue and tumor-surrounding tissue as compared to healthy livers. Conclusions: In human HCC, M30 serum levels are elevated indicating an increased cell turnover. Modulation of the vitamin D pathway might be a supportive, pro-apoptotic HCC therapy. Copyright © 2013 S. Karger AG, Basel

Supplementary Material for: Mini-Laparoscopy Guided Liver Biopsy Increases Diagnostic Accuracy in Acute Liver Failure

<p><b><i>Background/Aims:</i></b> For diagnosis, prognosis, and treatment of acute liver failure (ALF), macroscopic evaluation and histological assessment of the liver are important. Due to impaired coagulation in ALF, the risk of bleeding is high after a percutaneous liver biopsy. Our aims were to assess (i) safety and benefit of mini laparoscopy (ML) in patients with ALF and (ii) the potential utility of histological markers in ALF prognosis. <b><i>Methods:</i></b> ML was performed in 39 patients with ALF to assess liver surface and to obtain a liver biopsy. Serological markers of liver injury and immunohistochemical detection of cell death and proliferation were compared to a non-ALF group (n = 10). <b><i>Results:</i></b> Liver biopsies were successfully performed in all patients with no significant complications. All patients had markedly elevated M30 and M65 levels in the serum. In the liver, M30 and Ki67 immune-reactive cells were more abundant in those with ALF. Importantly, there were significantly more Ki67-positive cells but fewer M30-positive cells in livers of ALF patients who recovered spontaneously. <b><i>Conclusion:</i></b> ML with liver biopsy in patients with ALF and severe coagulopathy is safe. Immunohistochemical detection of liver cell death and regeneration may identify individuals who would recover spontaneously or who would need a liver transplant.</p