Expression of Beta-Defensin 131 Promotes an Innate Immune Response in Human Prostate Epithelial Cells.

Jung Hoon Kim,Hae Jong Kim,Soon Chul Myung,Jaehyouk Lee,Kyeoung-Hwa Kim

doi:10.1371/journal.pone.0144776

Jung Hoon Kim, Hae Jong Kim + Show 3 more

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https://doi.org/10.1371/journal.pone.0144776

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Abstract

Previously, using the Illumina HumanHT-12 microarray we found that β-defensin 131 (DEFB131), an antimicrobial peptide, is upregulated in the human prostate epithelial cell line RWPE-1 upon stimulation with lipoteichoic acid (LTA; a gram-positive bacterial component), than that in the untreated RWPE-1 cells. In the current study, we aimed to investigate the role of DEFB131 in RWPE-1 cells during bacterial infection. We examined the intracellular signaling pathways and nuclear responses in RWPE-1 cells that contribute to DEFB131 gene induction upon stimulation with LTA. Chromatin immunoprecipitation was performed to determine whether NF-κB directly binds to the DEFB131 promoter after LTA stimulation in RWPE-1 cells. We found that DEFB131 expression was induced by LTA stimulation through TLR2 and p38MAPK/NF-κB activation, which was evident in the phosphorylation of both p38MAPK and IκBα. We also found that SB203580 and Bay11-7082, inhibitors of p38MAPK and NF-κB, respectively, suppressed LTA-induced DEFB131 expression. The chromatin immunoprecipitation assay showed that NF-κB directly binds to the DEFB131 promoter, suggesting that NF-κB is a direct regulator, and is necessary for LTA-induced DEFB131 expression in RWPE-1 cells. Interestingly, with DEFB131 overexpression in RWPE-1 cells, the accumulation of mRNA and protein secretion of cytokines (IL-1α, IL-1β, IL-6, and IL-12α) and chemokines (CCL20, CCL22, and CXCL8) were significantly enhanced. In addition, DEFB131-transfected RWPE-1 cells markedly induced chemotactic activity in THP-1 monocytes. We concluded that DEFB131 induces cytokine and chemokine upregulation through the TLR2/NF-κB signaling pathway in RWPE-1 cells during bacterial infection and promotes an innate immune response.

Highlights

Innate immunity is regarded as a primitive and universal host defense system
DEFB131 expression was strongly upregulated in DU145 cells, only weakly expressed in RWPE-1 cells, and it was undetectable in PC-3 cells (Fig 1A)
To determine whether lipoteichoic acid (LTA) treatment led to the production of DEFB131 through TLR2, RWPE-1 cells were transfected with TLR2 shRNA to knock down TLR2

Summary

Introduction

Innate immunity is regarded as a primitive and universal host defense system. It is the first line of defense against invading pathogens and conserved products of microbial metabolism, such as peptidoglycan (PGN), lipoteichoic acid (LTA), lipopolysaccharides (LPS), zymosan, flagellin, lipoprotein, CpG-DNA, and nucleic acids [1]. Human β-defensins are cationic antimicrobial peptides with six conserved cysteine residues stabilized by three disulfide bonds. These peptides contribute to innate immune responses [3]. Unlike α-defensins, which are expressed in neutrophils and Paneth cells, β-defensins are expressed in epithelial cells. They exhibit bactericidal, fungicidal, and antiviral activity. RWPE1 cells, a human prostate epithelial cell line, produce β-defensins when stimulated with various bacterial components, indicating that β-defensins may be an important immunomodulatory factor in prostatic function [4,5]. Β-defensins act as chemokines for immature dendritic cells and memory T cells, and, they may serve as an important bridge between innate and adaptive immunity [11]. β-defensins are antimicrobial peptides of key interest to researchers because of this role [12]

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