Immunomodulatory Properties of Lactobacillus plantarum NC8 Expressing an Anti-CD11c Single-Chain Fv Fragment

Abstract

The lactic acid bacteria species Lactobacillus plantarum (L. plantarum) has been used extensively for vaccine delivery. Considering to the critical role of dendritic cells in stimulating host immune response, in this study, we constructed a novel CD11c-targeting L. plantarum strain with surface-displayed variable fragments of anti-CD11c, single-chain antibody (scFv-CD11c). The newly designed L. plantarum strain, named 409-aCD11c, could adhere and invade more efficiently to bone marrow-derived DCs (BMDCs) in vitro due to the specific interaction between scFv-CD11c and CD11c located on the surface of BMDCs. After incubation with BMDCs, the 409-aCD11c strain harboring a eukaryotic vector pValac-GFP could lead to more efficient expression of GFP compared with wild-type strains shown by flow cytometry analysis, indicating the enhanced translocation of pValac-GFP from L. plantarum to BMDCs. Similar results were also observed in an in vivo study, which showed that oral administration resulted in efficient expression of GFP in both Peyer's patches (PP) and mesenteric lymph nodes (MLNs) within 7 days after the last administration. In addition, the CD11c-targeting strain significantly promoted the differentiation and maturation of DCs, the differentiation of IL-4 + and IL-17A + T helper (Th) cells in MLNs, as well as production of B220 + IgA + B cells in the PP. In conclusion, this study developed a novel DC-targeting L. plantarum strain which could increase the ability to deliver eukaryotic expression plasmid to host cells, indicating a promising approach for vaccine study.

Dendritic Cells TargetingLactobacillus plantarumStrain NC8 with a Surface-Displayed Single-Chain Variable Fragment of CD11c Induce an Antigen-Specific Protective Cellular Immune Response

“…A single-chain variable fragment against CD11c (scFv-CD11c) fused to the immunodominant peptide of a retrovirus induces a virus-specific T cell response (16). In addition, we confirmed that the expression of scFv-CD11c in L. plantarum NC8 clearly enhanced the cellular uptake of L. plantarum strains into DCs and improved the delivery efficiency of the plasmid to host cells, demonstrating a prospective strategy for vaccine research (17).…”

“…The HA strains promote the activation and maturation of DCs. The aCD11c strain promotes the activation and maturation of DCs according to previous research (17). Mice were immunized as outlined in the protocol schematic (Fig.…”

“…The empty strain named 409p= was used as a negative control. The recombinant strains were established and cultivated, and then protein samples were collected by extracting cell membrane and cell wall fractions, as previously described (17,31). Western blotting was performed using an anti-rabbit H1N1 HA monoclonal antibody (GenScript, China) and a rabbit anti-His monoclonal antibody (Abbkine) as the primary antibodies, followed by goat anti-rabbit IgG-horseradish peroxidase (HRP) as the secondary antibody (Abbkine).…”

“…Flow cytometry assay. Single-cell suspensions were collected from the spleen cells, MLNs, and PPs and adjusted to 1.0 ϫ 10 6 cells/100 l or 2.0 ϫ 10 6 cells/100 l. Anti-CD11c, anti-CD80, and anti-CD83 antibodies were then used in the FCM analysis of DC phenotypes in the spleen (1.0 ϫ 10 6 /100 l) as previously described (17).…”

A novel “prime and pull” strategy mediated by the combination of two dendritic cell-targeting designs induced protective lung tissue-resident memory T cells against H1N1 influenza virus challenge

“…To date, monoclonal antibodies [ 28 ], single chain variable fragments (scFvs) [ 23 ], nanobodies [ 29 ] and DC-targeting peptides (DCpep) [ 30 ] have been employed in the design of DC-targeting vaccines. For example, we constructed a novel Lactobacillus plantarum strain with surface displayed scFv targeting the CD11c marker of mouse DCs (scFv-CD11c) [ 31 ] previously using a truncated poly-γ-glutamic acid synthetase A (pgsA’) anchoring sequence [ 32 ], the surface anchored scFv-CD11c significantly increased the cellular uptake of bacteria in mouse BMDCs [ 33 ] and stimulated elevated humoral immune responses against influenza virus H1N1 strain using an HA coexpressed model antigen, especially the cellular immune response [ 23 ]. On the other hand, DCpep is a series of short peptides that can mediate the specific interaction between DCpep-fused antigen and DCs in swine [ 34 ], mice [ 35 ] or chickens [ 36 ], resulting in increased specific humoral and cellular immune responses.…”