Exosomes derived from alcohol-treated hepatocytes horizontally transfer liver specific miRNA-122 and sensitize monocytes to LPS.

Fatemeh Momen-Heravi,Karen Kodys,Shashi Bala,Gyongyi Szabo

doi:10.1038/srep09991

Fatemeh Momen-Heravi, Karen Kodys + Show 2 more

Open Access

https://doi.org/10.1038/srep09991

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Abstract

Hepatocyte damage and inflammation in monocytes/macrophages are central to the pathogenesis of alcoholic hepatitis (AH). MicroRNAs (miRNAs) regulate all of these processes. MiRNA-122 is abundantly expressed in hepatocytes while monocytes/macrophages have low levels. The role of exosomes in AH and possible cross talk between hepatocyte-derived exosomes and immune cells is not explored yet. Here, we show that the number of exosomes significantly increases in the sera of healthy individuals after alcohol binge drinking and in mice after binge or chronic alcohol consumption. Exosomes isolated from sera after alcohol consumption or from in vitro ethanol-treated hepatocytes contained miRNA-122. Exosomes derived from ethanol-treated Huh7.5 cells were taken up by the recipients THP1 monocytes and horizontally transferred a mature form of liver-specific miRNA-122. In vivo, liver mononuclear cells and Kupffer cells from alcohol-fed mice had increased miRNA-122 levels. In monocytes, miRNA-122 transferred via exosomes inhibited the HO-1 pathway and sensitized to LPS stimulation and increased levels of pro-inflammatory cytokines. Finally, inflammatory effects of exosomes from ethanol-treated hepatocytes were prevented by using RNA interference via exosome-mediated delivery of a miRNA-122 inhibitor. These results demonstrate that first, exosomes mediate communication between hepatocytes and monocytes/macrophages and second, hepatocyte-derived miRNA-122 can reprogram monocytes inducing sensitization to LPS.

Highlights

Is elevated in various diseases including malaria[12], melanoma[13], ovarian cancer[14], renal cancer[15], diabetes mellitus[16], and chronic renal failure[17]
We present the novel finding that the number of exosomes is increased in the circulation after binge alcohol consumption in healthy human subjects and mice and after chronic alcohol feeding in mice
After isolating exosomes from healthy human subjects following binge alcohol drinking, we found elevated levels of miRNA-122 as early as 4 h after alcohol consumption that may indicate liver damage associated with acute alcohol binge

Summary

Result

Acute alcohol binge increases the number of circulating exosomes in healthy human subjects and in mice. This mimicked the sensitizing effect that we observed in the presence of exosomes derived from ethanol-treated hepatocytes, which abundantly harbor the mature form of miRNA-122. The RAW 264.7 macrophages transfection of a miRNA-122 mimic using Lipofectamine, significantly decreased the expression level of HO-1 mRNA (p < 0.05) and increased TNFα protein level (p < 0.05), compared to the control group transfected with negative control miRNA (Fig. 7D,E) These results suggest the concept that exosomes derived from ethanol-treated hepatocytes horizontally transfer miRNA122 to immune cells and modulate their function in pro-inflammatory cytokine production through affecting the HO-1 pathway. This was demonstrated by decreased levels of TNFα production in THP-1 monocytes that received the “therapeutic” exosomes containing a miR-122 inhibitor prior to exposure to exosomes from ethanol-treated hepatocytes (p < 0.05) (Fig. 7F)

Discussion

Findings

Materials and Methods