Format

Send to

Choose Destination
Immunology. 2014 Feb;141(2):203-10. doi: 10.1111/imm.12180.

Probiotic antigens stimulate hepatic natural killer T cells.

Author information

1
Department of Medicine, Johns Hopkins University, Baltimore, MD, USA.

Abstract

Increasing evidence suggests that gut flora play an important role in the pathogenesis of non-alcoholic fatty liver disease (NAFLD). Our previous studies show that hepatic natural killer T (NKT) cells play a significant role in the pathogenesis of NAFLD. In this study, we explore the mechanism by which modification of gut flora leads to the alteration of hepatic NKT cells and improvement of steatosis. Mice were fed a high-fat (HF) diet to induce NAFLD. Some of them also received different doses of mixed-strain probiotics (VSL#3); single-strain probiotic (Bifidobacterium infantis) or antibiotics. Animal weight, glucose tolerance, liver steatosis and hepatic NKT cells were assessed. Lipid extracts from probiotics were tested for their ability to activate NKT cells. Toll-like receptor 4 (TLR4) knockout mice were also evaluated for their responses to HF diet. High-dose VSL#3 was more effective than low-dose VSL#3 and B. infantis for the improvement of hepatic NKT cell depletion and steatosis. The lipids extracted from VSL#3 stimulated NKT cells both in vivo and in vitro. In contrast, lipids from B. infantis decreased α-GalCer-mediated NKT cell activation in vitro, but were able to stimulate NKT cells. TLR4 knockout mice have a similar response to HF-diet-induced NKT cell depletion and obesity. These results suggest that alterations in the gut flora have profound effects on hepatic NKT cells and steatosis, which are both strain-specific and dose-dependent, but not through TLR4 signalling. Furthermore, these data suggest that probiotics may contain bacterial glycolipid antigens that directly modulate the effector functions of hepatic NKT cells.

KEYWORDS:

interleukin-2; natural killer T cells; non-alcoholic fatty liver disease; probiotics; steatosis

PMID:
24400795
PMCID:
PMC3904241
DOI:
10.1111/imm.12180
[Indexed for MEDLINE]
Free PMC Article

Supplemental Content

Full text links

Icon for Wiley Icon for PubMed Central
Loading ...
Support Center