Mitochondrial Double‐Stranded RNA in Exosome Promotes Interleukin‐17 Production Through Toll‐Like Receptor 3 in Alcohol‐associated Liver Injury

Abstract

R 3 (TLR3) in Kupffer cells through the exosome (Exo) to enhance interleukin (IL)‐17A (IL‐17A) production in ALD. Approach and Results Following binge ethanol (EtOH) drinking, IL‐17A production primarily increased in γδ T cells of wild‐type (WT) mice, whereas the production of IL‐17A was mainly facilitated by CD4+ T cells in acute‐on‐chronic EtOH consumption. These were not observed in TLR3 knockout (KO) or Kupffer cell–depleted WT mice. The expression of polynucleotide phosphorylase, an mtdsRNA‐restricting enzyme, was significantly decreased in EtOH‐exposed livers and hepatocytes of WT mice. Immunostaining revealed that mtdsRNA colocalized with the mitochondria in EtOH‐treated hepatocytes from WT mice and healthy humans. Bioanalyzer analysis revealed that small‐sized RNAs were enriched in EtOH‐treated Exos (EtOH‐Exos) rather than EtOH‐treated microvesicles in hepatocytes of WT mice and humans. Quantitative real‐time PCR and RNA sequencing analyses indicated that mRNA expression of mitochondrial genes encoded by heavy and light strands was robustly increased in EtOH‐Exos from mice and humans. After direct treatment with EtOH‐Exos, IL‐1β expression was significantly increased in WT Kupffer cells but not in TLR3 KO Kupffer cells, augmenting IL‐17A production of γδ T cells in mice and humans. Conclusions EtOH‐mediated generation of mtdsRNA contributes to TLR3 activation in Kupffer cells through exosomal delivery. Consequently, increased IL‐1β expression in Kupffer cells triggers IL‐17A production in γδ T cells at the early stage that may accelerate IL‐17A expression in CD4+ T cells in the later stage of ALD. Therefore, mtdsRNA and TLR3 may function as therapeutic targets in ALD....