Immune response elicited by DNA vaccination using Lactococcus lactis is modified by the production of surface exposed pathogenic protein.

In this study, we compared immune responses elicited by DNA immunization using Lactococcus lactis or L. lactis expressing the Staphylococcus aureus invasin Fibronectin Binding Protein A (FnBPA) at its surface. Both strains carried pValac:BLG, a plasmid containing the cDNA of Beta-Lactoglobulin (BLG), and were designated LL-BLG and LL-FnBPA+ BLG respectively.

Identification of one novel candidate probiotic Lactobacillus plantarum strain active against influenza virus infection in mice by a large-scale screening.

In this study, we developed a large-scale screening of bacterial strains in order to identify novel candidate probiotics with immunomodulatory properties. For this, 158 strains, including a majority of lactic acid bacteria (LAB), were screened by two different cellular models: tumor necrosis factor alpha (TNF-α)-activated HT-29 cells and peripheral blood mononuclear cells (PBMCs). Different strains responsive to both models (pro- and anti-inflammatory strains) were selected, and their protective effects were tested in vivo in a murine model of influenza virus infection.

Production of Fibronectin Binding Protein A at the surface of Lactococcus lactis increases plasmid transfer in vitro and in vivo.

Lactococci are noninvasive lactic acid bacteria frequently used as protein delivery vectors and, more recently, as DNA delivery vehicles. We previously showed that Lactococcus lactis (LL) expressing the Fibronectin-Binding Protein A of Staphylococcus aureus (LL-FnBPA+) showed higher internalization rates in vitro in Caco-2 cells than the native (wt) lactococci and were able to deliver a eukaryotic Green Fluorescent Protein (GFP) expression plasmid in 1% of human Caco-2 cells. Here, using the bovine beta-lactoglobulin (BLG), one of the major cow's milk allergen, and GFP we characterized the potential of LL-FnBPA+ as an in vivo DNA vaccine delivery vehicle.

Inactivation of the ybdD gene in Lactococcus lactis increases the amounts of exported proteins.

Random insertional mutagenesis performed on a Lactococcus lactis reporter strain led us to identify L. lactis ybdD as a protein-overproducing mutant. In different expression contexts, the ybdD mutant shows increased levels of exported proteins and therefore constitutes a new and attractive heterologous protein production host.

Proteomic analysis of spontaneous mutants of Lactococcus lactis: Involvement of GAPDH and arginine deiminase pathway in H2O2 resistance.

Lactococcus lactis, one of the most commonly used dairy starters, is often subjected to oxidative stress in cheese manufacturing. A comparative proteomic analysis was performed to identify the molecular modifications responsible for the robustness of three spontaneous H(2)O(2)-resistant (SpOx) strains. In the parental strain, glyceraldehyde-3-phosphate deshydrogenase (GAPDH) activity is ensured by GapB and the second GAPDH GapA is not produced in standard growth conditions.

Mucosal co-immunization of mice with recombinant lactococci secreting VapA antigen and leptin elicits a protective immune response against Rhodococcus equi infection.

Rhodococcus equi causes severe pneumonia in foals and has recently gained attention as a significant opportunistic pathogen in immunocompromised humans. However, no effective vaccine to prevent rhodococcosis is currently available. In this study, we have engineered the food-grade bacterium Lactococcus lactis to secrete the virulence-associated protein A from R.

Anti-inflammatory properties of dairy lactobacilli.

Background: The intestinal microbiota plays an important role in human health through the modulation of innate immune responses. While selected commensal bacteria are marketed in specific probiotic products to control these responses, relatively little is known about the immune modulation potential of dairy bacteria that have principally been selected for their fermentation properties. The modulation of innate immune responses may reduce chronic inflammation in inflammatory bowel diseases like ulcerative colitis.

Variations of N-acetylation level of peptidoglycan do not influence persistence of Lactococcus lactis in the gastrointestinal tract.

The food-grade Gram-positive bacterium, Lactococcus lactis, is recognized as a potential candidate to deliver proteins of medical interest by mucosal routes. The ability of carrier bacteria to persist and/or to lyse in the gastrointestinal tract needs to be considered to design optimal carrier strains to deliver proteins of interest at the mucosal level. Meyrand et al.

Intragastric administration of a superoxide dismutase-producing recombinant Lactobacillus casei BL23 strain attenuates DSS colitis in mice.

Human immune cells release large amounts of reactive oxygen species (ROS) such as superoxide radical and hydrogen peroxide via respiratory burst. In inflammatory bowel diseases, a sustained and abnormal activation of the immune response results in oxidative stress of the digestive tract and in a loss of intestinal homeostasis. We previously reported that heterologous production of the Lactobacillus plantarum manganese catalase (MnKat) enhances the survival of Lb.

Behavior of the meat-borne bacterium Lactobacillus sakei during its transit through the gastrointestinal tracts of axenic and conventional mice.

A Lactobacillus sakei strain named FLEC01 was isolated from human feces and characterized genotypically. Comparison of the genetic features of this strain with those of both the meat-borne L. sakei strain 23K and another human isolate, LTH5590, showed that they belong to different but closely related clusters.

Faecalibacterium prausnitzii is an anti-inflammatory commensal bacterium identified by gut microbiota analysis of Crohn disease patients.

A decrease in the abundance and biodiversity of intestinal bacteria within the dominant phylum Firmicutes has been observed repeatedly in Crohn disease (CD) patients. In this study, we determined the composition of the mucosa-associated microbiota of CD patients at the time of surgical resection and 6 months later using FISH analysis. We found that a reduction of a major member of Firmicutes, Faecalibacterium prausnitzii, is associated with a higher risk of postoperative recurrence of ileal CD.