The CCR2 Inhibitor Propagermanium Attenuates Diet-Induced Insulin Resistance, Adipose Tissue Inflammation and Non-Alcoholic Steatohepatitis

PLoS One. 2017 Jan 11;12(1):e0169740. doi: 10.1371/journal.pone.0169740. eCollection 2017.

Abstract

Background and aim: Obese patients with chronic inflammation in white adipose tissue (WAT) have an increased risk of developing non-alcoholic steatohepatitis (NASH). The C-C chemokine receptor-2 (CCR2) has a crucial role in the recruitment of immune cells to WAT and liver, thereby promoting the inflammatory component of the disease. Herein, we examined whether intervention with propagermanium, an inhibitor of CCR2, would attenuate tissue inflammation and NASH development.

Methods: Male C57BL/6J mice received a high-fat diet (HFD) for 0, 6, 12 and 24 weeks to characterize the development of early disease symptoms of NASH, i.e. insulin resistance and WAT inflammation (by hyperinsulinemic-euglycemic clamp and histology, respectively) and to define the optimal time point for intervention. In a separate study, mice were pretreated with HFD followed by propagermanium treatment (0.05% w/w) after 6 weeks (early intervention) or 12 weeks (late intervention). NASH was analyzed after 24 weeks of diet feeding.

Results: Insulin resistance in WAT developed after 6 weeks of HFD, which was paralleled by modest WAT inflammation. Insulin resistance and inflammation in WAT intensified after 12 weeks of HFD, and preceded NASH development. The subsequent CCR2 intervention experiment showed that early, but not late, propagermanium treatment attenuated insulin resistance. Only the early treatment significantly decreased Mcp-1 and CD11c gene expression in WAT, indicating reduced WAT inflammation. Histopathological analysis of liver demonstrated that propagermanium treatment decreased macrovesicular steatosis and tended to reduce lobular inflammation, with more pronounced effects in the early intervention group. Propagermanium improved the ratio between pro-inflammatory (M1) and anti-inflammatory (M2) macrophages, quantified by CD11c and Arginase-1 gene expression in both intervention groups.

Conclusions: Overall, early propagermanium administration was more effective to improve insulin resistance, WAT inflammation and NASH compared to late intervention. These data suggest that therapeutic interventions for NASH directed at the MCP-1/CCR2 pathway should be initiated early.

MeSH terms

  • Adipose Tissue / drug effects*
  • Adipose Tissue / metabolism
  • Adipose Tissue / pathology
  • Animals
  • Anti-Inflammatory Agents / pharmacology
  • Anti-Inflammatory Agents / therapeutic use*
  • Arginase / genetics
  • Arginase / metabolism
  • CD11 Antigens / genetics
  • CD11 Antigens / metabolism
  • Chemokine CCL2 / genetics
  • Chemokine CCL2 / metabolism
  • Diet, High-Fat / adverse effects
  • Insulin Resistance*
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Non-alcoholic Fatty Liver Disease / drug therapy*
  • Non-alcoholic Fatty Liver Disease / etiology
  • Non-alcoholic Fatty Liver Disease / metabolism
  • Organometallic Compounds / pharmacology
  • Organometallic Compounds / therapeutic use*
  • Receptors, CCR2 / antagonists & inhibitors
  • Receptors, CCR2 / metabolism

Substances

  • Anti-Inflammatory Agents
  • CD11 Antigens
  • Ccl2 protein, mouse
  • Chemokine CCL2
  • Organometallic Compounds
  • Receptors, CCR2
  • proxigermanium
  • Arginase

Grant support

This study was supported by the TNO research programs ‘Predictive Health Technologies’ and ‘Enabling Technology Systems Biology’. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.