Original Article

Intranasal co-delivery of IL-6 gene enhances the immunogenicity of anti-caries DNA vaccine

Authors: Ling-kai Su, Fei Yu, Zhao-fei Li, Chang Zeng, Qing-an Xu, Ming-wen Fan
DOI: 10.1038/aps.2013.184

Abstract

Ling-kai SU1, #, Fei YU2, #, Zhao-fei LI1, Chang ZENG1, Qing-an XU1, *, Ming-wen FAN1, *
1The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) & Key Laboratory of Oral Biomedicine of Ministry of Education (KLOBM), School & Hospital of Stomatology, Wuhan University, Wuhan 430079, China; 2Center of Stomatology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China

Aim: To investigate the effects of co-delivering IL-6 expressing plasmid pCI-IL-6 on the immunogenicity of the anti-caries DNA vaccine pCIA-P, which encodes the surface protein antigen PAc of Streptococcus mutans.

Methods: Plasmid pCI-IL-6 was constructed by inserting the murine IL-6 gene into the pCI vector. Expression of IL-6 in vitro was assessed using Western blot analysis. BALB/c mice were intranasally co-immunized with pCIA-P plus pCI-IL-6 on d 0 and 14. Anti-PAc IgG and secretory IgA (sIgA) were assessed by ELISA. Splenocytes from the mice were re-stimulated with the PAc protein, and IFN-γ and IL-4 production was measured using ELISA. Splenocyte proliferation was analyzed with flow cytometry. Rats were similarly immunized, and dental caries scores were determined using the Keyes method.

Results: Marked expression of IL-6 was found in COS-7 cells transfected with pCI-IL-6. In the pCI-IL-6 co-immunized mice, the specific IgG antibodies in serum and sIgA antibodies in saliva were significantly higher than those in the control mice at weeks 4 and 8. Moreover, the secretion of IFN-γ from splenocytes in response to re-stimulation with PAc protein was significantly higher in the pCI-IL-6 co-immunized mice than that in the control mice, whereas the secretion of IL-4 had no significant difference. The proliferation of splenocytes from the pCI-IL-6 co-immunized mice was significantly higher than that from the mice immunized with pCIA-P and pCI vector. In the rat caries model, the pCI-IL-6 co-immunization rats displayed lower caries scores than the control rats.

Conclusion: Intranasal co-delivery of IL-6 gene significantly enhances the immunogenicity of the anti-caries DNA vaccine.

Keywords: DNA vaccine; vaccine adjuvant; dental caries; Streptococcus mutans; IL-6; cytokine; immunogenicity; stomatology

This work was supported by National Natural Science Foundation of China (No 81000435 and 81271129).
# These authors contributed equally to this work.
* To whom correspondence should be addressed.
E-mail xuqingan1977@163.com (Qing-an XU); fmw@whuss.com (Ming-wen FAN)
Received 2013-08-20 Accepted 2013-11-26
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