1 College of Animal Science and Technology, Jilin Provincial Engineering Research Center of Animal Probiotics, Key Laboratory of animal production and product quality safety of Ministry of Education, Jilin Agricultural University, 130118 Changchun, China P.R.
2 Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, 78350 Jouy-en-Josas, France.
Benef Microbes. 2019 May 28;10(5):589-604. doi: 10.3920/BM2018.0157. Epub 2019 May 15.
Recombinant lactic acid bacteria (LAB), especially , have been genetically engineered to express heterogeneous invasion proteins, such as the fibronectin binding protein A (FnBPA) from , to increase the invasion ability of the host strains, indicating a promising approach for DNA vaccine delivery. The presence of FnBPA has been also shown to be an adjuvant for co-delivered antigens, however, the underlying mechanisms are still not clear. To explore the above underlying mechanisms, in this study, we constructed a novel strain with surface displayed FnBPA, which could significantly improve the adhesion and invasion ratios of strain on a porcine intestinal epithelial cell line (IPEC-J2) about two-fold compared with the empty vector. At the same time, the presence of FnBPA significantly stimulated the differentiation of bone marrow-derived dendritic cells (DCs) and increased the secretion of interleukin (IL)-6 and mRNA level of IL-6 gene, which were proved by flow cytometry, enzyme-linked immunosorbent assay (ELISA) and quantitative reverse transcription PCR (qRT-PCR). With regard to study, the presence of FnBPA significantly stimulated the differentiation of DCs in the Peyer's patch (PP) and the percentages of IL-4 and IL-17A T helper (Th) cells of splenocytes in flow cytometry assay. In consistent with these results, the levels of IL-4 and IL-17A in serum as measured via ELISA also increased in mice treated with FnBPA . Finally, the FnBPA strain increased the production of B220 B cells in mesenteric lymph node (MLN) and PP and the levels of FnBPA-specific IgG and sIgA antibodies, indicating the its possible application in vaccine field. This study demonstrated that the invasive with surface displayed FnBPA could modulate host immune response by stimulating the differentiation of DCs and Th cells which could possibly be responsive for the adjuvant effects of FnBPA.
重组乳杆菌（LAB），特别是 ，已被基因工程改造为表达异源入侵蛋白，如来自 的纤维连接蛋白结合蛋白 A（FnBPA），以提高宿主菌株的入侵能力，这表明 DNA 疫苗传递是一种很有前途的方法。FnBPA 的存在也被证明是共递呈抗原的佐剂，然而，其潜在机制尚不清楚。为了探索上述潜在机制，在本研究中，我们构建了一种新型的表面展示 FnBPA 的 菌株，与空载体相比，该菌株能显著提高 菌株在猪肠上皮细胞系（IPEC-J2）上的黏附和侵袭比率，约增加两倍。同时，FnBPA 的存在显著刺激了骨髓来源树突状细胞（DC）的分化，并增加了白细胞介素（IL）-6 的分泌和 IL-6 基因的 mRNA 水平，这一点通过流式细胞术、酶联免疫吸附试验（ELISA）和定量逆转录聚合酶链反应（qRT-PCR）得到了证实。就 研究而言，FnBPA 的存在显著刺激了派氏结（PP）中 DC 的分化，以及脾细胞中白细胞介素 4（IL-4）和白细胞介素 17A（IL-17A）T 辅助（Th）细胞的百分比在流式细胞术分析中。与这些结果一致，用 ELISA 测量的血清中 IL-4 和 IL-17A 的水平在 FnBPA 处理的小鼠中也增加了。最后，FnBPA 菌株增加了肠系膜淋巴结（MLN）和 PP 中 B220 B 细胞的产生以及 FnBPA 特异性 IgG 和 sIgA 抗体的水平，表明其在疫苗领域的可能应用。本研究表明，表面展示 FnBPA 的侵袭性 能够通过刺激 DC 和 Th 细胞的分化来调节宿主免疫反应，这可能是 FnBPA 佐剂作用的原因。
