Human neutrophil peptides induce interleukin-8 in intestinal epithelial cells through the P2 receptor and ERK1/2 signaling pathways

• Published in: International journal of molecular medicine Vol. 35; no. 6; pp. 1603 - 1609
• Main Authors: IBUSUKI, KAZUNARI, SAKIYAMA, TOSHIO, KANMURA, SHUJI, MAEDA, TAKURO, IWASHITA, YUJI, NASU, YUICHIRO, SASAKI, FUMISATO, TAGUCHI, HIROKI, HASHIMOTO, SHINICHI, NUMATA, MASATSUGU, UTO, HIROFUMI, TSUBOUCHI, HIROHITO, IDO, AKIO
• Format: Journal Article
• Language: English
• Published: Greece D.A. Spandidos 01.06.2015; Spandidos Publications; Spandidos Publications UK Ltd
• Subjects: alpha-Defensins - pharmacology; Antimicrobial peptides; Caco-2 Cells; Colon; Cytokines; Epithelial cells; extracellular signal-regulated kinase 1/2; Gene expression; Health aspects; human neutrophil peptide; Humans; Inflammatory bowel disease; interleukin-8; Interleukin-8 - biosynthesis; Interleukins; intestinal epithelial cell; Intestinal Mucosa - metabolism; Isothiocyanates - pharmacology; Kinases; MAP Kinase Signaling System - drug effects; Mitogen-Activated Protein Kinase 1 - metabolism; Mitogen-Activated Protein Kinase 3 - metabolism; Neutrophils; P2 receptor; Pathogenesis; Penicillin; Phosphotransferases; Proteins; Receptors, Purinergic P2 - metabolism; Thiourea - analogs & derivatives; Thiourea - pharmacology; Tumor necrosis factor-TNF; Japan
• ISSN: 1107-3756; 1791-244X
• DOI: 10.3892/ijmm.2015.2156

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.