Effect of herbal melanin on IL-8: a possible role of Toll-like receptor 4 (TLR4)

Biochem Biophys Res Commun. 2006 Jun 16;344(4):1200-6. doi: 10.1016/j.bbrc.2006.04.035. Epub 2006 May 2.

Abstract

The production of IL-8 can be induced by LPS via TLR4 signaling pathway. In this study, we tested the effect of a herbal melanin (HM) extract, from black cumin seeds (Nigella sativa L.), on IL-8 production. We used HM and LPS in parallel to induce IL-8 production by THP-I, PBMCs, and TLR4-transfected HEK293 cells. Both HM and LPS induced IL-8 mRNA expression and protein production in THP-1 and PBMCs. On applying similar treatment to HEK293 cells that express TLR4, MD2, and CD14, both HM and LPS significantly induced IL-8 protein production. We have also demonstrated that HM and LPS had identical effects in terms of IL-8 stimulation by HEK293 transfected with either TLR4 or MD2-CD14. Melanin extracted from N. sativa L. mimics the action of LPS in the induction of IL-8 by PBMC and the other used cell lines. Our results suggest that HM may share a signaling pathway with LPS that involves TLR4.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cells, Cultured
  • Humans
  • Interleukin-8 / biosynthesis*
  • Interleukin-8 / genetics
  • Leukocytes, Mononuclear / drug effects
  • Leukocytes, Mononuclear / metabolism
  • Lipopolysaccharides / pharmacology
  • Melanins / pharmacology*
  • Plant Extracts / pharmacology*
  • RNA, Messenger / biosynthesis
  • Signal Transduction / drug effects
  • Toll-Like Receptor 4 / genetics
  • Toll-Like Receptor 4 / metabolism*

Substances

  • Interleukin-8
  • Lipopolysaccharides
  • Melanins
  • Plant Extracts
  • RNA, Messenger
  • TLR4 protein, human
  • Toll-Like Receptor 4