Stimulation of Proliferation and Migration of Mouse Macrophages by Type B CpG-ODNs Is F-Spondin and IL-1Ra Dependent.

Tai-An Chen,Shu-Mei Liang,Yen-Po Chen,Chi-Ming Liang,Yi-Fan Hsu,Yung-Chih Cheng,Chiao-Chun Liao,Pranela Rameshwar

doi:10.1371/journal.pone.0128926

Abstract

Macrophage proliferation and migration are important for many facets of immune response. Here we showed that stimulation of macrophages with type B CpG oligodeoxynucleotides (CpG-B ODNs) such as CpG-ODN 1668 increased the production of anti-inflammatory cytokine interleukin 1 receptor antagonist (IL-1Ra) in a TLR9- and MyD88-dependent manner. The CpG-B ODNs-induced IL-1Ra increased macrophage migration and promoted macrophage proliferation by down-regulating the expression of a cell cycle negative regulator, p27 to increase cell population in the S phase. The induction of IL-1Ra by CpG-B ODNs was F-spondin dependent. Knockdown of F-spondin and IL-1Ra decreased CpG-B ODNs-induced macrophage migration whereas overexpression of IL-1Ra increased migration of those cells. These findings demonstrated novel roles for F-spondin and IL-1Ra in CpG-B ODNs-mediated cell proliferation and migration of macrophages.

Highlights

Unmethylated CpG dinucleotides present in bacterial DNA are recognized by pattern recognition receptor Toll-like receptor 9 (TLR9) which triggers downstream signaling to activate target genes [1,2]
Since CpG ODNs are well-known ligands for TLR9 [1,2], we examined whether TLR9 is essential for CpG-B ODNs-induced interleukin 1 receptor antagonist (IL-1Ra) expression
IL-1Ra expression was first found to increase gradually within 24 h of CpG-B ODN treatment in wild-type THP-1 cells (Fig 1D). Both RT-PCR and western blotting analyses showed that CpG-B ODNs-induced IL-1Ra expression was attenuated in Myeloid differentiation protein-88 (MyD88) deficient THP-1 cells (Fig 1E and 1F). These results indicate that CpG-B but not CpG-A ODNs increase the expression of IL-1Ra via a TLR9/MyD88 signaling pathway

Summary

Introduction

Unmethylated CpG dinucleotides present in bacterial DNA are recognized by pattern recognition receptor Toll-like receptor 9 (TLR9) which triggers downstream signaling to activate target genes [1,2]. Like the unmethylated CpG motif in bacterial DNAs, synthetic oligodeoxynucleotides bearing CpG motifs (CpG ODNs) can bind to TLR9 and activate immune responses [3]. CpG-A ODNs activate NK cells and stimulate plasmacytoid dendritic cells (pDCs) and macrophages to produce high levels of interferon-α [5,6]. CpG-B ODNs induce maturation and activation of pDCs and macrophages [6,7], and protect B cells, pDCs and macrophages from apoptosis [8,9,10]. CpG-B ODNs have been shown to induce macrophage migration by NF-κB activation and MMP-9 expression [11]

Methods

Results

Conclusion