c-di-GMP Induces COX-2 Expression in Macrophages in a STING-Independent Manner

ACS Chem Biol. 2021 Sep 17;16(9):1663-1670. doi: 10.1021/acschembio.1c00342. Epub 2021 Sep 3.

Abstract

Many pathogen-associated molecular patterns (PAMPs), such as lipopolysaccharide (LPS) and lipoteichoic acid, are potent immunostimulatory molecules and promote the expression of cyclooxygenase 2 (COX-2). While the production of COX-2, and ultimately prostaglandin E2, could be protective, persistent induction of COX-2 leads to inflamed environments that can result in septic shock and death. Bacterial derived cyclic dinucleotides (CDNs), c-di-GMP and c-di-AMP, are also PAMPs and have been shown to produce inflamed environments via the production of pro-inflammatory cytokines such as type I interferons. The well-characterized CDN immunostimulatory mechanism involves binding to stimulator of interferon genes (STING), which ultimately results in the phosphorylation of IRF3 or release of NF-κB to promote expression of type I IFN or pro-inflammatory cytokines. In this study, we sought to investigate if CDNs promote COX-2 expression. Using RAW macrophages as a model system, we reveal that c-di-GMP, but not c-di-AMP or the host-derived 2',3'-cGAMP, promotes COX-2 expression. Using analogues of CDNs, we show that the presence of two guanines and two 3',5'-phosphodiester linkages are requirements for the promotion of COX-2 expression by cyclic dinucleotides. Both c-di-GMP and LPS inductions of COX-2 expression in RAW macrophages are STING-independent and are regulated by Tpl2-MEK-ERK-CREB signaling; inhibitors of Tpl2, MEK, and ERK could attenuate COX-2 expression promoted by c-di-GMP. This work adds to the growing body of evidence that cyclic dinucleotides regulate pathways other than the STING-TBK1-IRF3 axis. Additionally, the differential COX-2 induction by c-di-GMP but not c-di-AMP or cGAMP suggests that the type and level of inflammation could be dictated by the nucleotide signature of the invading pathogen.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animals
  • Beclin-1 / metabolism
  • Cell Line
  • Cyclic GMP / analogs & derivatives*
  • Cyclic GMP / metabolism
  • Cyclooxygenase 2 / genetics*
  • Cyclooxygenase 2 / metabolism*
  • Dinucleoside Phosphates / metabolism
  • Gene Expression Regulation
  • Guanine / metabolism
  • Immunity, Innate
  • Interferon Regulatory Factor-3 / metabolism
  • Interferon Type I / metabolism
  • Macrophages / metabolism*
  • Mice
  • NF-kappa B / metabolism
  • Oligonucleotides / metabolism
  • Phosphorylation
  • Prostaglandins / metabolism
  • Signal Transduction

Substances

  • Beclin-1
  • Dinucleoside Phosphates
  • Interferon Regulatory Factor-3
  • Interferon Type I
  • NF-kappa B
  • Oligonucleotides
  • Prostaglandins
  • cyclic diadenosine phosphate
  • Guanine
  • bis(3',5')-cyclic diguanylic acid
  • Cyclooxygenase 2
  • Cyclic GMP