Cell Reports (Jul 2024)

Hepatocyte-macrophage crosstalk via the PGRN-EGFR axis modulates ADAR1-mediated immunity in the liver

  • Wei Liang Gan,
  • Xi Ren,
  • Vanessa Hui En Ng,
  • Larry Ng,
  • Yangyang Song,
  • Vincent Tano,
  • Jian Han,
  • Omer An,
  • Jinghe Xie,
  • Bryan Y.L. Ng,
  • Daryl Jin Tai Tay,
  • Sze Jing Tang,
  • Haoqing Shen,
  • Shruti Khare,
  • Kelvin Han Chung Chong,
  • Dan Yock Young,
  • Bin Wu,
  • Ramanuj DasGupta,
  • Leilei Chen

Journal volume & issue
Vol. 43, no. 7
p. 114400

Abstract

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Summary: ADAR1-mediated RNA editing establishes immune tolerance to endogenous double-stranded RNA (dsRNA) by preventing its sensing, primarily by MDA5. Although deleting Ifih1 (encoding MDA5) rescues embryonic lethality in ADAR1-deficient mice, they still experience early postnatal death, and removing other MDA5 signaling proteins does not yield the same rescue. Here, we show that ablation of MDA5 in a liver-specific Adar knockout (KO) murine model fails to rescue hepatic abnormalities caused by ADAR1 loss. Ifih1;Adar double KO (dKO) hepatocytes accumulate endogenous dsRNAs, leading to aberrant transition to a highly inflammatory state and recruitment of macrophages into dKO livers. Mechanistically, progranulin (PGRN) appears to mediate ADAR1 deficiency-induced liver pathology, promoting interferon signaling and attracting epidermal growth factor receptor (EGFR)+ macrophages into dKO liver, exacerbating hepatic inflammation. Notably, the PGRN-EGFR crosstalk communication and consequent immune responses are significantly repressed in ADAR1high tumors, revealing that pre-neoplastic or neoplastic cells can exploit ADAR1-dependent immune tolerance to facilitate immune evasion.

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