The present study shows for the first time that the polyphenol resveratrol (RESV) blocks processing of tumour necrosis factor-alpha (TNF-alpha) pre-mRNA in mature mRNA. This study was carried out in turbot (Psetta maxima (L.)), a fish species that we are using to evaluate the effects of RESV on the inflammatory response in vertebrates. Treatment of turbot head kidney leucocytes with polysaccharides from the seaweed Ulva rigida (ulvan) resulted in an increase in TNF-alpha expression. RESV did not inhibit transcription but almost completely inhibited the production of mRNA in ulvan-induced cells and caused a notable increase in the level of unspliced TNF-alpha pre-mRNA. RESV also induced accumulation of IL-1beta pre-mRNA at the expense of mature mRNA, although the effects on IL-1beta were less evident than those on TNF-alpha. However, the housekeeping gene was not affected by RESV. We also evaluated the effects of RESV in vivo under an inflammatory stimulus and found an inhibitory effect on TNF-alpha and IL-1beta pre-mRNA splicing in turbot head kidney at 24 and 48h post-injection. In addition, RESV also reduced migration of cells to the peritoneal cavity under the same inflammatory stimulus. The results show that this fish species may be a useful model for analysing the effects of RESV on TNF-alpha and IL-1beta expression, and suggest that RESV could be used to decrease the levels of pro-inflammatory cytokines in vivo and to reduce inflammatory reactions in certain inflammatory diseases.
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