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Suppression of LPS ‐induced transcription and cytokine secretion by the dietary isothiocyanate sulforaphane
Author(s) -
Folkard Danielle L.,
Melchini Antonietta,
Traka Maria H.,
AlBakheit Ala'a,
Saha Shikha,
Mulholland Francis,
Watson Andrew,
Mithen Richard F.
Publication year - 2014
Publication title -
molecular nutrition and food research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.495
H-Index - 131
eISSN - 1613-4133
pISSN - 1613-4125
DOI - 10.1002/mnfr.201400550
Subject(s) - sulforaphane , tlr4 , inflammation , isothiocyanate , cytokine , chemistry , peripheral blood mononuclear cell , cruciferous vegetables , secretion , phenethyl isothiocyanate , in vivo , receptor , immunology , biochemistry , pharmacology , biology , medicine , in vitro , microbiology and biotechnology , cancer
Scope Diets rich in cruciferous vegetables are associated with lower levels of pro‐inflammatory cytokines, which may contribute to potential health‐promoting properties of these vegetables. We investigate whether sulforaphane (SF), an isothiocyanate (ITC) obtained from broccoli, could suppress LPS‐induced transcription and subsequent pro‐inflammatory cytokine secretion at a physiologically relevant concentration using in vitro models of chronic inflammation. Methods and results We find that exposure of the LPS receptor Toll‐like receptor‐4 (TLR4) to physiologically appropriate concentrations of SF under non‐reducing conditions results in covalent modification of cysteine residues 246 and 609. We further demonstrate that the changes in expression of 1210 genes ( p ≤ 0.01) in THP‐1 monocytes and the secretion of pro‐inflammatory cytokines in both human peripheral blood mononuclear cells (PBMCs) and THP‐1 monocytes induced by LPS exposure can be completely suppressed through exposure with physiologically appropriate concentrations of SF. Finally, we show that in vivo exposure of human PBMCs to ITCs within human circulation reduces secretion of pro‐inflammatory cytokines following subsequent ex vivo LPS challenge ( p < 0.001). Conclusion Covalent modification of TLR4 by ITCs and resultant suppression of LPS‐induced cell signalling could lead to reductions in levels of pro‐inflammatory cytokines in people with chronic diseases who consume diets rich in cruciferous vegetables.