Production and delivery of Helicobacter pylori NapA in Lactococcus lactis and its protective efficacy and immune modulatory activity

Xiaoyan Peng,Shuaiyin Chen,Yuanlin Xi,Chen Wang,Qingtang Fan,Linghan Zhang,Nan Sun,Rongguang Zhang,Guangcai Duan

doi:10.1038/s41598-018-24879-x

Xiaoyan Peng, Shuaiyin Chen + Show 7 more

Open Access

https://doi.org/10.1038/s41598-018-24879-x

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Abstract

Helicobacter pylori neutrophil-activating protein A subunit (NapA) has been identified as a virulence factor, a protective antigen and a potent immunomodulator. NapA shows unique application potentials for anti-H. pylori vaccines and treatment strategies of certain allergic diseases and carcinomas. However, appropriate production and utilization modes of NapA still remain uncertain to date. This work has established a novel efficient production and utilization mode of NapA by using L. lactis as an expression host and delivery vector, and demonstrated immune protective efficacy and immune modulatory activity of the engineered L. lactis by oral vaccination of mice. It was observed for the first time that H. pylori NapA promotes both polarized Th17 and Th1 responses, which may greatly affect the clinical application of NapA. This report offers a promising anti-H. pylori oral vaccine candidate and a potent mucosal immune modulatory agent. Meanwhile, it uncovers a way to produce and deliver the oral vaccine and immunomodulator by fermentation of food like milk, which might have striking effects on control of H. pylori infection, gastrointestinal cancers, and Th2 bias allergic diseases, including many food allergies.

Highlights

In two days post challenge with H. pylori, as an innate immune response, infiltration of macrophages and neutrophils occurs in gastric glandular tissues[7]
It was confirmed by restrictive enzyme digestion and gene sequencing that the napA gene was exactly cloned in L. lactis, downstream of the nisin controlled promoter (Pnis) within the expression vector pNZ8110lysM, generating pNZ8110-napA-lysM (Genbank No KY385374)
These findings demonstrated efficient expression of neutrophil-activating protein A subunit (NapA) in the engineered L. lactis and the antigenicity of the recombinant NapA

Summary

Introduction

In two days post challenge with H. pylori, as an innate immune response, infiltration of macrophages and neutrophils occurs in gastric glandular tissues[7]. Stimulation of human neutrophils and monocytes with NapA can induce expression of IL-12 and IL-23, and thereby shift antigen-specific T cell responses from a Th2 to a Th1 phenotype, which is characterized by high levels of interferon-gamma (IFN-γ) and tumor necrosis factor-alpha (TNF-α) production[13]. NapA neither has toxic effect on monocytes and neutrophils nor reduces their viability or lifespan, it can enhance production of nitric oxide[17,18]. These data warrant approaches on application of NapA as a vaccine candidate or immunotherapy agent[17]. The immune efficacy is compromised when using only NapA in immunization, this protein is still considered as a major antigen candidate for anti-H. pylori vaccines[11,20]

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