Pro-Inflammatory Cytokines but Not Endotoxin-Related Parameters Associate with Disease Severity in Patients with NAFLD

PLoS One. 2016 Dec 19;11(12):e0166048. doi: 10.1371/journal.pone.0166048. eCollection 2016.

Abstract

Intestinal dysbiosis and elevated lipopolysaccharides (LPS) levels have been implicated in the development of obesity, insulin resistance and non-alcoholic steatohepatitis (NASH). In order to determine if LPS levels are elevated in patients with NASH compared to patients with non-alcoholic fatty liver (NAFL) and, if elevated LPS levels correlated with histological severity of non-alcoholic fatty liver disease (NAFLD) we compared LPS, markers of LPS bioactivity and pro-inflammatory cytokines/chemokines in patients undergoing bariatric surgery. At the time of surgery a liver biopsy was taken allowing the stratification into well-delineated subgroups including: No NAFL/NAFL; NASH; NASH with fibrosis and NASH cirrhotics, using the NAFLD Activity Score (NAS). Anthropometric data and plasma were collected for assessment of LPS, lipopolysaccharide binding protein (LBP), soluble CD14 (sCD14), intestinal-type fatty acid binding protein (iFABP), Toll-like receptors 2 and 4 (TLR2, 4) and a panel of cytokines/chemokines. Similar analysis was performed on plasma from a cohort of healthy controls. Our data indicate elevated levels of LPS, LBP, sCD14, iFABP and TLR2,4 in obese patients compared to healthy controls, however, these parameters remained unaltered within patients with limited liver disease (NAFL) compared to NASH/NASH with fibrosis subgroups. Hierarchic cluster analysis using endotoxin-related parameters failed to discriminate between lean controls, NAFLD. While similar cluster analysis implementing inflammation-related parameters clearly distinguished lean controls, NALFD subgroups and NASH cirrhotics. In addition, LPS levels was not associated with disease severity while TNFα, IL8, and CCL3 featured a clear correlation with transaminase levels and the histological severity of NALFD. In conclusion our data indicate a stronger correlation for circulating inflammatory- rather than endotoxin-related parameters in progression of NAFLD and highlights the need for additional larger studies in unravelling further mechanistic insights.

MeSH terms

  • Acute-Phase Proteins
  • Adult
  • Bariatric Surgery
  • Carrier Proteins / blood*
  • Chemokines / blood*
  • Cluster Analysis
  • Cytokines / blood*
  • Endotoxins / metabolism
  • Female
  • Humans
  • Lipopolysaccharides / blood*
  • Male
  • Membrane Glycoproteins / blood*
  • Middle Aged
  • Non-alcoholic Fatty Liver Disease / immunology
  • Non-alcoholic Fatty Liver Disease / metabolism
  • Non-alcoholic Fatty Liver Disease / pathology*
  • Obesity / immunology
  • Obesity / metabolism
  • Obesity / surgery*
  • Prospective Studies

Substances

  • Acute-Phase Proteins
  • Carrier Proteins
  • Chemokines
  • Cytokines
  • Endotoxins
  • Lipopolysaccharides
  • Membrane Glycoproteins
  • lipopolysaccharide-binding protein

Grants and funding

Schalk van der Merwe, Frederik Nevens, David Cassiman and Sven Francque are recipients of Flanders fund for scientific research (FWO klinisch mandaat). Hannelie Korf is a recipient of FWO post-doctoral mandate. Research at the department of Endocrinology, Diabetology and Metabolism and the department of Gastroenterology and Hepatology of the Antwerp University Hospital (Belgium) was supported by the European Union: FP6 (HEPADIP Contract LSHM-CT-2005-018734) and FP7-HEALTH (RESOLVE nr. 305707). Johannie du Plessis is a recipient of an European Association for the Study of the Liver (EASL) scholarship.