Small specific-sized hyaluronic acid 35 normalizes TLR4 signaling in Kupffer cells from ethanol-fed via microRNA291b-3 and its target Tollip

TLR4 signaling in hepatic macrophages is increased after chronic ethanol feeding; treatment of hepatic macrophges with small-specific sized hyaluronic acid 35 (HA35) normalizes TLR4 signaling. Here we used next generation... [ view full abstract ]

TLR4 signaling in hepatic macrophages is increased after chronic ethanol feeding; treatment of hepatic macrophges with small-specific sized hyaluronic acid 35 (HA35) normalizes TLR4 signaling. Here we used next generation sequencing of microRNAs to identify negative regulators of TLR4 signaling reciprocally modulated by ethanol and HA35.   Of the 11 microRNAs up-regulated by ethanol, expression of miR291b-3p was robustly increased more than 4-fold.  Importantly, ex vivo treatment of hepatic macrophages with HA35 normalized expression of miR291b-3p.  Bioinformatics analysis identified Tollip, a negative regulator of TLR4, as a target of miR291b-3p. Tollip expression was decreased in hepatic macrophages from ethanol-fed rats, but treatment with HA35 or transfection with a miR291b-3p mimic restored Tollip expression and normalized TLR4-stimulated TNFα expression.  In peripheral monocytes isolated from patients with alcoholic hepatitis, expression of TNFα mRNA was robustly in response to challenge with lipopolysaccharide.  Importantly, pre-treatment with HA35 reduced TNFα expression by more than 50%.  Taken together, we have identified miR291b-3p as a critical miRNA up-regulated by ethanol; miR291bp-3p contributed to sensitization of TLR4 signaling via down-regulation of Tollip.  Normalization of this miR291b-3p →Tollip pathway by HA35 also normalized TLR4 signaling, suggesting that HA35 may be a novel therapeutic agent in the treatment of ALD.