Thymoquinone-induced Neu4 sialidase activates NFκB in macrophage cells and pro-inflammatory cytokines in vivo

Glycoconj J. 2010 Aug;27(6):583-600. doi: 10.1007/s10719-010-9302-5. Epub 2010 Aug 10.

Abstract

Thymoquinone (TQ) derived from the nutraceutical black cumin oil has been reported to be a novel agonist of Neu4 sialidase activity in live cells (Glycoconj J DOI 10.1007/s10719-010-9281-6). The activation of Neu4 sialidase on the cell surface by TQ was found to involve GPCR-signaling via membrane targeting of Gαi subunit proteins and matrix metalloproteinase-9 activation. Contrary to other reports, TQ had no anti-inflammatory effects in vitro. Here, we show that MyD88/TLR4 complex formation and subsequent NFκB activation are induced by the Neu4 activity associated with TQ-stimulated live primary bone marrow (BM) macrophage cells from WT and Neu1-deficient mice, HEK-TLR4/MD2 cells and BMC-2 macrophage cell line but not with primary macrophage cells from Neu4-knockout mice. Tamiflu (oseltamivir phosphate), pertussis toxin (PTX), a specific inhibitor of Gαi proteins of G-protein coupled receptor (GPCR) and the broad range inhibitor of matrix metalloproteinase (MMP) galardin applied to live primary BM macrophage cells completely block TQ-induced MyD88/TLR4 complex formation. Using immunocytochemistry and western blot analyses, Tamiflu, galardin and PTX inhibit NFκB activation induced by Neu4 activity associated with TQ-stimulated BMC-2 cells, HEK-TLR4/MD2 cells and primary BM macrophages from WT mice. EMSA analyses on HEK-TLR4/MD2 nuclear cell extracts confirm the nuclear localization and DNA binding of TQ-induced NFκB activation in a biphasic manner within 30 min. Co-immunoprecipitation experiments reveal for the first time that MMP-9 may be an important intermediate link in the TQ-induced Neu4 activity circuitously targeting TLR4 receptors. Central to this process is that Neu4 forms a complex with MMP-9, which is already bound to TLR4 receptors. Fluorescence spectrophotometer analyses of live CD14-THP1 cells treated with TQ show Neu4 sialidase activity over 5 min. Using flow cytometry analyses, CD14-THP1 cells treated with TQ express stable protein levels of Neu4, TLR4 and MMP9 on the cell surface over 30 min except for a marked diminution of MMP9 at 15 min. Using cytokine array profiling analyses of serum, Neu4-knockout mice respond poorly to TQ in producing pro-inflammatory cytokines and chemokines after 5-h treatment compared to the wild-type or hypomorphic cathepsin A mice with a secondary 90% Neu1 deficient mice. Our findings establish an unprecedented signaling paradigm for TQ-induced Neu4 sialidase activity. It signifies that MMP-9 forms an important molecular signaling platform in complex with TLR4 receptors at the ectodomain and acts as the intermediate link for TQ-induced Neu4 sialidase in generating a functional receptor with subsequent NFκB activation and pro-inflammatory cytokine production in vivo.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Benzoquinones / pharmacology*
  • Bone Marrow Cells / cytology
  • Cells, Cultured
  • Cytokines / blood
  • Dipeptides / pharmacology
  • Enzyme Activation / drug effects
  • Enzyme Induction / drug effects
  • Humans
  • Inflammation Mediators / metabolism*
  • Lymphocyte Antigen 96 / metabolism
  • Macrophages / drug effects*
  • Macrophages / enzymology*
  • Matrix Metalloproteinase 9 / metabolism
  • Mice
  • Myeloid Differentiation Factor 88 / metabolism
  • NF-kappa B / metabolism*
  • Neuraminidase / antagonists & inhibitors
  • Neuraminidase / biosynthesis*
  • Oseltamivir / pharmacology
  • Pertussis Toxin / pharmacology
  • Phosphorylation / drug effects
  • Protein Binding / drug effects
  • Protein Transport / drug effects
  • Receptors, G-Protein-Coupled / metabolism
  • Time Factors
  • Toll-Like Receptor 4 / metabolism

Substances

  • Benzoquinones
  • Cytokines
  • Dipeptides
  • Inflammation Mediators
  • LY96 protein, human
  • Lymphocyte Antigen 96
  • Myeloid Differentiation Factor 88
  • N-(2(R)-2-(hydroxamidocarbonylmethyl)-4-methylpentanoyl)-L-tryptophan methylamide
  • NF-kappa B
  • Receptors, G-Protein-Coupled
  • Toll-Like Receptor 4
  • Oseltamivir
  • Pertussis Toxin
  • Neu4 protein, mouse
  • Neuraminidase
  • Matrix Metalloproteinase 9
  • thymoquinone