LL-37 transports immunoreactive cGAMP to activate STING signaling and enhance interferon-mediated host antiviral immunity

Cell Rep. 2022 May 31;39(9):110880. doi: 10.1016/j.celrep.2022.110880.

Abstract

Cyclic 2',3'-GMP-AMP (cGAMP) binds to and activates stimulator of interferon genes (STING), which then induces interferons to drive immune responses against tumors and pathogens. Exogenous cGAMP produced by infected and malignant cells and synthetic cGAMP used in immunotherapy must traverse the cell membrane to activate STING in target cells. However, as an anionic hydrophilic molecule, cGAMP is not inherently membrane permeable. Here, we show that LL-37, a human host defense peptide, can function as a transporter of cGAMP. LL-37 specifically binds cGAMP and efficiently delivers cGAMP into target cells. cGAMP transferred by LL-37 activates robust interferon responses and host antiviral immunity in a STING-dependent manner. Furthermore, we report that LL-37 inducers vitamin D3 and sodium butyrate promote host immunity by enhancing endogenous LL-37 expression and its mediated cGAMP immune response. Collectively, our data uncover an essential role of LL-37 in innate immune activation and suggest new strategies for immunotherapy.

Keywords: CP: Immunology; antibacterial peptide; cGAMP; cGAS-STING signaling pathway; innate immunity; type I interferon.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antiviral Restriction Factors* / immunology
  • Cathelicidins* / immunology
  • Humans
  • Immunity, Innate*
  • Interferons* / immunology
  • Membrane Proteins / metabolism
  • Nucleotides, Cyclic

Substances

  • Antiviral Restriction Factors
  • CAMP protein, human
  • Cathelicidins
  • Membrane Proteins
  • Nucleotides, Cyclic
  • cyclic guanosine monophosphate-adenosine monophosphate
  • Interferons