title: Human neutrophil peptides induce interleukin-8 in intestinal epithelial cells through the P2 receptor and ERK1/2 signaling pathways.
abstract: Human neutrophil peptides (HNPs) are antimicrobial peptides produced predominantly by neutrophils. We have previously reported that HNP 1-3 levels are increased in the sera and plasma of patients with active ulcerative colitis. The increased expression of interleukin-8 (IL-8) has also been demonstrated in the colonic mucosa of patients with active ulcerative colitis. HNPs induce IL-8 in lung epithelial cells and monocytes through the P2Y6 signaling pathway. However, the association between HNPs and IL-8 in the intestinal mucosa has not yet been investigated. In the present study, we investigated the effects of HNP-1 on the production of IL-8 by human intestinal epithelial cells and the underlying signaling mechanisms. We observed a significant increase in IL-8 expression in the human colon carcinoma cell line, Caco-2, following treatment with HNP-1. The non-selective P2 receptor antagonists, suramin and pyridoxal phosphate-6-azo (benzene-2,4-disulfonic acid) tetrasodium salt hydrate (PPADS), significantly blocked the HNP-1-induced expression of IL-8 in the Caco-2 cells. The P2Y6-specific antagonist, MRS2578, led to a significant but partial decrease in IL-8 expression, suggesting that P2 receptors in addition to P2Y6 are involved in the HNP-1-induced production of IL-8 by Caco-2 cells. In agreement with this finding, HNP-1 also significantly increased IL-8 production in the P2Y6-negative human colon cancer cell line, HT-29, and this increase was blocked by treatment with suramin and PPADS. HNP-1 significantly increased the phosphorylation of extracellular signal-regulated kinase 1/2 (ERK1/2) and p38 mitogen-activated protein kinase (MAPK) in the HT-29 cells. However, the HNP-1-induced production of IL-8 was suppressed by the ERK1/2 inhibitor, U0126, but not by the p38 MAPK inhibitor, SB203580. In conclusion, our data demonstrate that HNP-1 induces IL-8 production not only through P2Y6, but also through additional P2 receptors via an ERK1/2-dependent mechanism in intestinal epithelial cells.
authors: Digestive and Lifestyle Diseases, Department of Human and Environmental Sciences, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima 890-8544, Japan.
authors: Kazunari
authors: K
authors: Ibusuki
authors: Digestive and Lifestyle Diseases, Department of Human and Environmental Sciences, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima 890-8544, Japan.
authors: Toshio
authors: T
authors: Sakiyama
authors: Digestive and Lifestyle Diseases, Department of Human and Environmental Sciences, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima 890-8544, Japan.
authors: Shuji
authors: S
authors: Kanmura
authors: Digestive and Lifestyle Diseases, Department of Human and Environmental Sciences, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima 890-8544, Japan.
authors: Takuro
authors: T
authors: Maeda
authors: Digestive and Lifestyle Diseases, Department of Human and Environmental Sciences, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima 890-8544, Japan.
authors: Yuji
authors: Y
authors: Iwashita
authors: Digestive and Lifestyle Diseases, Department of Human and Environmental Sciences, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima 890-8544, Japan.
authors: Yuichiro
authors: Y
authors: Nasu
authors: Digestive and Lifestyle Diseases, Department of Human and Environmental Sciences, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima 890-8544, Japan.
authors: Fumisato
authors: F
authors: Sasaki
authors: Digestive and Lifestyle Diseases, Department of Human and Environmental Sciences, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima 890-8544, Japan.
authors: Hiroki
authors: H
authors: Taguchi
authors: Digestive and Lifestyle Diseases, Department of Human and Environmental Sciences, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima 890-8544, Japan.
authors: Shinichi
authors: S
authors: Hashimoto
authors: Digestive and Lifestyle Diseases, Department of Human and Environmental Sciences, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima 890-8544, Japan.
authors: Masatsugu
authors: M
authors: Numata
authors: Digestive and Lifestyle Diseases, Department of Human and Environmental Sciences, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima 890-8544, Japan.
authors: Hirofumi
authors: H
authors: Uto
authors: Digestive and Lifestyle Diseases, Department of Human and Environmental Sciences, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima 890-8544, Japan.
authors: Hirohito
authors: H
authors: Tsubouchi
authors: Digestive and Lifestyle Diseases, Department of Human and Environmental Sciences, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima 890-8544, Japan.
authors: Akio
authors: A
authors: Ido
mesh_terms: D018938:Caco-2 Cells; D006801:Humans; D016209:Interleukin-8 / Q000096:biosynthesis*; D007413:Intestinal Mucosa / Q000378:metabolism*; D017879:Isothiocyanates / Q000494:pharmacology; D020935:MAP Kinase Signaling System / Q000187:drug effects*; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism*; D018048:Receptors, Purinergic P2 / Q000378:metabolism*; D013890:Thiourea / Q000031:analogs & derivatives / Q000494:pharmacology; D023084:alpha-Defensins / Q000494:pharmacology*
chemical_list: C508606:CXCL8 protein, human; D016209:Interleukin-8; D017879:Isothiocyanates; C541384:N,N''-1,4-butanediylbis(N'-(3-isothiocyanatophenyl))thiourea; D018048:Receptors, Purinergic P2; D023084:alpha-Defensins; C406413:human neutrophil peptide 1; C099845:purinoceptor P2Y6; C535150:MAPK1 protein, human; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D013890:Thiourea