Endothelial expression of fractalkine (CX3CL1) is induced by Toll-like receptor 3 signaling in cultured human glomerular endothelial cells

Mod Rheumatol. 2020 Nov;30(6):1074-1081. doi: 10.1080/14397595.2019.1682768. Epub 2019 Nov 5.


Background: Endothelial expression of membrane-bound fractalkine/CX3CL1 (Fkn) reportedly acts as a strong mediator of inflammation. Toll-like receptor 3 (TLR3) axes are thought to play some roles in the development of chronic glomerulonephritis (CGN) including lupus nephritis (LN). However, detailed mechanism of TLR3-mediated Fkn expression in glomerular endothelial cells (GECs) remains to be elucidated.Methods: We examined the effect of polyinosinic-polycytidylic acid (poly IC) on Fkn expression in cultured human GECs. Fkn mRNA and protein levels were quantified by real-time PCR and enzyme-linked immunosorbent assay, respectively. To further elucidate the effects of poly IC on this signaling pathway, we used small-interfering RNA (siRNA) to knockdown expression of TLR3, nuclear factor (NF)-κB p65, interferon (IFN)-β, and IFN regulatory factor 3 (IRF3). We then analyzed whether pretreatment of chloroquine or dexamethasone (DEX) inhibits poly IC-induced Fkn expression.Results: We found that poly IC-induced Fkn expression in GECs, and that this involved NF-κB, IFN-β, and IRF3. Pretreating cells with chloroquine, but not DEX attenuated poly IC-induced Fkn expression in GECs.Conclusion: Since the activation of TLR3/NF-κB/IFN-β/Fkn and TLR3/IRF3/Fkn axes is involved in inflammatory reactions in GECs, intervention of glomerular TLR3 signaling may be a suitable therapeutic strategy for treating CGN especially LN.

Keywords: Chloroquine; Toll-like receptor 3; fractalkine (CX3CL1); glomerular endothelial cells; lupus nephritis.

MeSH terms

  • Cells, Cultured
  • Chemokine CX3CL1 / genetics
  • Chemokine CX3CL1 / metabolism*
  • Chloroquine / pharmacology
  • Endothelial Cells / drug effects
  • Endothelial Cells / metabolism*
  • Humans
  • Interferon-beta / metabolism
  • Kidney Glomerulus / cytology
  • Kidney Glomerulus / metabolism
  • NF-kappa B / metabolism
  • Poly I-C / pharmacology
  • Signal Transduction*
  • Toll-Like Receptor 3 / metabolism*


  • CX3CL1 protein, human
  • Chemokine CX3CL1
  • NF-kappa B
  • TLR3 protein, human
  • Toll-Like Receptor 3
  • Interferon-beta
  • Chloroquine
  • Poly I-C