Effect of herbal melanin on IL-8: a possible role of Toll-like receptor 4 (TLR4).
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.
El-Obeid
Adila
A
Department of Genetics and Pathology, Rudbeck Laboratory, Uppsala University Hospital, SE-751 85 Uppsala, Sweden. adila.elobeid@genpat.uu.se
Hassib
Adil
A
Pontén
Fredrik
F
Westermark
Bengt
B
D002478:Cells, Cultured; D006801:Humans; D016209:Interleukin-8 / Q000096:biosynthesis* / Q000235:genetics; D007963:Leukocytes, Mononuclear / Q000187:drug effects / Q000378:metabolism; D008070:Lipopolysaccharides / Q000494:pharmacology; D008543:Melanins / Q000494:pharmacology*; D010936:Plant Extracts / Q000494:pharmacology*; D012333:RNA, Messenger / Q000096:biosynthesis; D015398:Signal Transduction / Q000187:drug effects; D051197:Toll-Like Receptor 4 / Q000235:genetics / Q000378:metabolism*
D016209:Interleukin-8; D008070:Lipopolysaccharides; D008543:Melanins; D010936:Plant Extracts; D012333:RNA, Messenger; C495345:TLR4 protein, human; D051197:Toll-Like Receptor 4