A palindromic CpG-containing phosphodiester oligodeoxynucleotide as a mucosal adjuvant stimulates plasmacytoid dendritic cell-mediated T(H)1 immunity.

Jun-Ichi Maeyama,Saburo Yamamoto,Fumiko Suzuki,Harukazu Kitagawa,Masanori Isaka,Hisakazu Takatsuka,Takasumi Matsuki,Ichiroh Shimada,Ayumi Kubota,Takako Komiya,Eri Murata,Satomi Horiguchi,Youko Osawa,Sumiko Iho,Mauricio Martins Rodrigues

doi:10.1371/journal.pone.0088846

Abstract

BackgroundCpG oligodeoxynucleotides (ODNs), resembling bacterial DNA, are currently tested in clinical trials as vaccine adjuvants. They have the nuclease-resistant phosphorothioate bond; the immune responses elicited differ according to the CpG ODN sequence and vaccination method. To develop a CpG ODN that can induce plasmacytoid dendritic cell (pDC)-mediated TH1 immunity through the mucosa, we constructed phosphodiester G9.1 comprising one palindromic CpG motif with unique polyguanosine-runs that allows degradation similar to naturally occurring bacterial DNA.MethodsTH1 and TH2 immunity activation was evaluated by cytokine production pattern and T-bet/GATA-3 ratio in human peripheral blood mononuclear cells and mouse bone marrow cells. Adjuvanticity was evaluated in mice administered G9.1 with diphtheria toxoid (DT) through nasal vaccination.ResultsG9.1 exhibited stronger IFN-α-inducing activity than A-class CpG ODN2216 and increased T-bet/GATA-3 ratio by enhancing T-bet expression. Nasally administered G9.1 plus DT induced DT-specific mucosal IgA and serum IgG, but not IgE, responses with antitoxin activity in C57BL/6 and BALB/c mice, possibly due to IFN/BAFF production. Induction of TH1, but not TH2, -type Abs depended completely on pDCs, the first in vivo demonstration by CpG ODNs.ConclusionsG9.1 is a promising mucosal adjuvant for induction of pDC-mediated TH1 immunity.

Highlights

Mucosal immunization has several distinct advantages over injection, including the stimulation of systemic immunity and mucosal immunity at the application site and other mucosa, including the lung and gastrointestinal tract mucosa [1,2,3]
Based on our previous studies [17,18], we recently developed a large series of PO-type CpG ODNs including G9.1 (GACGATCGTC linked in a unique manner by G9- and 1-mers at its 59 and 39 ends; Patent US7,718,623B2, May 2010)
We previously demonstrated that CpG ODNs longer than 18mer are required to stimulate IFN-a production [25]

Summary

Introduction

Mucosal immunization has several distinct advantages over injection, including the stimulation of systemic immunity and mucosal immunity at the application site and other mucosa, including the lung and gastrointestinal tract mucosa [1,2,3]. The effects of CpG ODNs, primarily B class with a phosphorothioate (PS) backbone, were reported to differ with the administration route, schedule and sequence In some cases, they may even cause lymphoid follicle destruction or immunosuppression in a pDC-independent manner [12,13,14,15,16]. They may even cause lymphoid follicle destruction or immunosuppression in a pDC-independent manner [12,13,14,15,16] In this regard, CpG ODNs with a phosphodiester (PO) backbone similar to bacterial DNA instead of PS, and capable of inducing IFN-a production, could be advantageous as adjuvants. To develop a CpG ODN that can induce plasmacytoid dendritic cell (pDC)mediated TH1 immunity through the mucosa, we constructed phosphodiester G9.1 comprising one palindromic CpG motif with unique polyguanosine-runs that allows degradation similar to naturally occurring bacterial DNA

Methods

Results

Discussion

Conclusion