IgA-enhancing effects of membrane vesicles derived from <i>Lactobacillus sakei</i> subsp. <i>sakei</i> NBRC15893

Abstract

Immunoglobulin (Ig) A in the mucus of the intestinal tract plays an important role in preventing the invasion of pathogenic microorganisms and regulating the composition of the gut microbiota. Several strains of probiotic lactic acid bacteria (LAB) are known to promote intestinal IgA production. Bacteria are also known to naturally release spherical membrane vesicles (MVs) that are involved in various biological functions such as quorum sensing, pathogenesis, and host immunomodulation. However, the production of MVs by LAB and their effects on host immunity remain poorly understood. In this study, we investigated the MV production by Lactobacillus sakei subsp. sakei NBRC15893 isolated from kimoto, the traditional seed mash used for brewing sake. MVs were separated from the culture broth of L. sakei NBRC15893 through filtration and density gradient ultracentrifugation and were observed by transmission electron microscopy. The MVs showed a spherical morphology, with a diameter of 30–400 nm, and contained proteins and nucleic acids. In addition, both the LAB cells and purified MVs promoted IgA production by murine Peyer’s patch cells. This MV- and cell-induced IgA production was suppressed by neutralization of Toll-like receptor (TLR) 2, which recognizes cell wall components of gram-positive bacteria, using an anti-TLR2 antibody. Collectively, our results indicate that MVs released from L. sakei NBRC15893 enhance IgA production by activating host TLR2 signaling through its cell wall components. Thus, it is important to consider novel interactions between gut microbiota and hosts via MVs, and MVs derived from probiotic bacteria could have promising applications as safe adjuvants.

Probiomimetics—Novel Lactobacillus‐Mimicking Microparticles Show Anti‐Inflammatory and Barrier‐Protecting Effects in Gastrointestinal Models

“…[ 21–23 ] They possess various biological functions, including mediation of bacteria–bacteria communication and bacteria–host modulation. [ 24–28 ]…”

Differences in Immune Response and Biochemical Parameters of Mice Fed by Kefir Milk and Lacticaseibacillus paracasei Isolated from the Kefir Grains

“…In another study, Carasi et al [ 31 ] demonstrated an increase in IgA production along with inducing mucin, decreased expression of pro-inflammatory mediators and increased anti-inflammatory molecules following administration of L. kefiri CIDCA 8348 in healthy mice. Several authors observed that LAB significantly induces IgA secretion in the intestine [ 32 , 33 , 34 ] through an increase in the number of IgA + B cells in mice [ 35 ]. This is consistent with our current results, in which L. paracasei Ž2 alone significantly increased the level of IgA gene expression in all parts of the intestine.…”

Extracellular Membrane Vesicles from Lactobacilli Dampen IFN-γ Responses in a Monocyte-Dependent Manner

“…MVs isolated from Bifidobacterium longum is internalized by mast cells in a phagocytosis-independent mechanism 64 , while MVs isolated from L. sakei subsp. sakei enhance IgA production by activation of Toll-like receptor 2 signalling 65 . Whether or not the MVs are taken up by the monocytes or interact solely with surface receptors, in our settings, remains to be investigated.…”