Background: Nonalcoholic steatohepatitis (NASH) is characterized by an increase in the number of hepatic macrophages with a pro-inflammatory phenotype. To preserve macrophage integrity but reduce inflammatory activation in NASH we have developed liposomes with anti-inflammatory drug curcumin and ovalbumin antigen entrapped and injected these nanoparticles together with ovalbumin-specific regulatory Tcells (Tregs) into mice fed methionine and choline deficient (MCD)-diet and tested their capacity to target inflammatory macrophages, reduce inflammation and treat disease.
Methods: C57BL/6 mice were fed MCD-diet for 2 weeks and then intravenously injected with 100 µL of DiI-labelled curcumin-ovalbumin liposomes and 24 hours later adoptively transferred with 8x105 ovalbumin-specific Tregs. Serum and livers were harvested 1-week post treatment, immune cells were isolated and analysed using flow cytometry. Stage of disease and severity was assessed by measuring serum ALT levels, and by H&E staining.
Results: Mice fed MCD-diet for 3 weeks developed severe steatohepatitis with cellular recruitment of pro-inflammatory cells including F4/80+ macrophages and dendritic cells compared to mice on control diet. Curcumin-ovalbumin liposomes targeted hepatic macrophages and DCs. The outcome on targeting hepatic APCs with curcumin-ovalbumin liposomes was reduced macrophage activation and reduced proportion of inflammatory DCs which prevented MCD-diet induced liver damage as measured by serum ALT and severity of disease as measured by NAFLD assessing score. Addition of ovalbumin-specific Tregs with curcumin liposomes containing ovalbumin further reduced hepatocyte damage and reduced neutrophil proportions in the liver.
Conclusion: Targeting curcumin and regulatory T cells to hepatic inflammatory APC is a novel approach to prevent NASH progression.