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Open Access Highly Accessed Research article

LPS-induced IL-8 activation in human intestinal epithelial cells is accompanied by specific histone H3 acetylation and methylation changes

Tiziana Angrisano1, Raffaela Pero1, Silvia Peluso1, Simona Keller12, Silvana Sacchetti12, Carmelo B Bruni1, Lorenzo Chiariotti123* and Francesca Lembo13*

Author Affiliations

1 Dipartimento di Biologia e Patologia Cellulare e Molecolare "L. Califano", Facoltà di Farmacia e Facoltà di Scienze Biotecnologiche, Università degli Studi di Napoli "Federico II", Via S. Pansini 5, Naples, 80131, Italy

2 Naples Oncogenomic Center, CEINGE Biotecnologie Avanzate, Università degli Studi di Napoli "Federico II", Via Comunale Margherita 482, Naples, 80145, Italy

3 Dipartimento di Chimica Farmaceutica e Tossicologica, Facoltà di Farmacia, Università degli Studi di Napoli "Federico II", Via D. Montesano 47, Naples, 80131, Italy

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BMC Microbiology 2010, 10:172  doi:10.1186/1471-2180-10-172

Published: 14 June 2010

Abstract

Background

The release of LPS by bacteria stimulates both immune and specific epithelial cell types to release inflammatory mediators. It is known that LPS induces the release of IL-8 by intestinal mucosal cells. Because it is now emerging that bacteria may induce alteration of epigenetic patterns in host cells, we have investigated whether LPS-induced IL-8 activation in human intestinal epithelial cells involves changes of histone modifications and/or DNA methylation at IL-8 gene regulatory region.

Results

RT-PCR analysis showed that IL-8 mRNA levels rapidly increase after exposure of HT-29 cells to LPS. DNA demethylating agents had no effects on IL-8 expression, suggesting that DNA methylation was not involved in IL-8 gene regulation. Consistently we found that 5 CpG sites located around IL-8 transcription start site (-83, -7, +73, +119, +191) were unmethylated on both lower and upper strand either in LPS treated or in untreated HT-29 cells, as well as in normal intestinal mucosa.

Conversely, pretreatment of HT-29 cells with deacetylase inhibitors strengthened the LPS-mediated IL-8 activation. Inhibitors of histone deacetylases could induce IL-8 mRNA expression also in the absence of LPS, suggesting that chromatin modifications could be involved in IL-8 gene regulation. Chromatin immunoprecipitation analyses showed that, concurrently with IL-8 activation, transient specific changes in H3 acetylation and H3K4, H3K9 and H3K27 methylation occurred at IL-8 gene promoter during LPS stimulation. Changes of H3-acetyl, H3K4me2 and H3K9me2 levels occurred early, transiently and corresponded to transcriptional activity, while changes of H3K27me3 levels at IL-8 gene occurred later and were long lasting.

Conclusion

The results showed that specific chromatin modifications occurring at IL-8 gene, including histone H3 acetylation and methylation, mark LPS-mediated IL-8 activation in intestinal epithelial cells while it is unlikely that DNA methylation of IL-8 promoter is directly involved in IL-8 gene regulation in these cells.