Hepatic mitochondrial DNA/Toll-like receptor 9/MicroRNA-223 forms a negative feedback loop to limit neutrophil overactivation and acetaminophen hepatotoxicity in mice

  • Hepatology. 2017 Jul;66(1):220-234. doi: 10.1002/hep.29153.
Yong He  1  2  3 ,  Dechun Feng  2 ,  Man Li  2 ,  Yanhang Gao  2 ,  Teresa Ramirez  2 ,  Haixia Cao  2 ,  Seung-Jin Kim  2 ,  Yang Yang  1  3 ,  Yan Cai  2 ,  Cynthia Ju  4 ,  Hua Wang  2  3 ,  Jun Li  1  3 ,  Bin Gao  2
Affiliations
  • 1. School of Pharmacy, Anhui Medical University, Hefei, China.
  • 2. Laboratory of Liver Diseases, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD.
  • 3. Institute for Liver Diseases, Anhui Medical University, Hefei, China.
  • 4. Skaggs School of Pharmacy and Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus, Aurora, CO.
PMID: 28295449 DOI: 10.1002/hep.29153
Abstract

Acetaminophen (APAP) overdose is a leading cause of acute liver failure worldwide, in which mitochondrial DNA (mtDNA) released by damaged hepatocytes activates neutrophils through binding of Toll-like Receptor 9 (TLR9), further aggravating liver injury. Here, we demonstrated that mtDNA/TLR9 also activates a negative feedback pathway through induction of microRNA-223 (miR-223) to limit neutrophil overactivation and liver injury. After injection of APAP in mice, levels of miR-223, the most abundant miRNAs in neutrophils, were highly elevated in neutrophils. Disruption of the miR-223 gene exacerbated APAP-induced hepatic neutrophil infiltration, oxidative stress, and injury and enhanced TLR9 ligand-mediated activation of proinflammatory mediators in neutrophils. An additional deletion of the intercellular adhesion molecule 1 (ICAM-1) gene ameliorated APAP-induced neutrophil infiltration and liver injury in miR-223 knockout mice. In vitro experiments revealed that miR-223-deficient neutrophils were more susceptible to TLR9 agonist-mediated induction of proinflammatory mediators and nuclear factor kappa B (NF-κB) signaling, whereas overexpression of miR-223 attenuated these effects in neutrophils. Moreover, inhibition of TLR9 signaling by either treatment with a TLR9 Inhibitor or by disruption of TLR9 gene partially, but significantly, suppressed miR-223 expression in neutrophils post-APAP injection. In contrast, activation of TLR9 up-regulated miR-223 expression in neutrophils in vivo and in vitro. Mechanistically, activation of TLR9 up-regulated miR-223 by enhancing NF-κB binding on miR-223 promoter, whereas miR-223 attenuated TLR9/NF-κB-mediated inflammation by targeting IκB kinase α expression. Collectively, up-regulation of miR-223 plays a key role in terminating the acute neutrophilic response and is a therapeutic target for treatment of APAP-induced liver failure. (Hepatology 2017;66:220-234).

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