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

Abstract

Secreted factors derived from Lactobacillus are able to dampen pro-inflammatory cytokine responses. Still, the nature of these components and the underlying mechanisms remain elusive. Here, we aimed to identify the components and the mechanism involved in the Lactobacillus-mediated modulation of immune cell activation. PBMC were stimulated in the presence of the cell free supernatants (CFS) of cultured Lactobacillus rhamnosus GG and Lactobacillus reuteri DSM 17938, followed by evaluation of cytokine responses. We show that lactobacilli-CFS effectively dampen induced IFN-γ and IL-17A responses from T- and NK cells in a monocyte dependent manner by a soluble factor. A proteomic array analysis highlighted Lactobacillus-induced IL-1 receptor antagonist (ra) as a potential candidate responsible for the IFN-γ dampening activity. Indeed, addition of recombinant IL-1ra to stimulated PBMC resulted in reduced IFN-γ production. Further characterization of the lactobacilli-CFS revealed the presence of extracellular membrane vesicles with a similar immune regulatory activity to that observed with the lactobacilli-CFS. In conclusion, we have shown that lactobacilli produce extracellular MVs, which are able to dampen pro-inflammatory cytokine responses in a monocyte-dependent manner.

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

“…[ 48 ] This effect has been proven to be linked to the innate immune system, which is also consistent with the effects seen on the dTHP‐1 cells. [ 49 ]…”

“…[48] This effect has been proven to be linked to the innate immune system, which is also consistent with the effects seen on the dTHP-1 cells. [49] Other Lactobacillus strains, such as Lactobacillus kefir, have anti-inflammatory effects on Caco-2 cells and they ameliorated colitis in a mouse model. [50] According to a recent study by Choi et al these effects seem to be related to multiple mechanisms, such as the reduction of NO-production and the amelioration of endoplasmic reticulum stress.…”

Lactobacillus reuteri-derived extracellular vesicles maintain intestinal immune homeostasis against lipopolysaccharide-induced inflammatory responses in broilers

“…To remove vesicular nucleic acids and proteins, 1 mg/mL of native LrEVs were treated with 10 U/mL of DNase I (Thermo Scientific, #EN0521), 10 U/mL of RNase I (Solarbio, #R8021), and 1 mg/mL of proteinase K-agarose (Sigma, #P9290), respectively, as described previously [ 16 , 31 ]. The native LrEVs were incubated with DNase I and RNase I at 37 °C for 30 min, and with proteinase K-agarose at 37 °C for 2 h. The enzymes were inactivated at 75 °C for 1 h. Proteinase K-agarose was additionally removed by centrifugation (12,000× g , 1 min).…”

Proteomic profile of extracellular vesicles released by Lactiplantibacillus plantarum BGAN8 and their internalization by non-polarized HT29 cell line

“…When comparing with other bacterial EVs, it is worth noting that the size calculation is highly dependent on the measurement method. In any case, variable size distribution of extracellular vesicles have been reported for Gram-positive bacterial EVs other than lactobacilli 40 , but also for a number of Lactobacillus species 16 , 24 – 27 , 29 , 41 , 42 . Given the scarce literature, it cannot be postulated if the size distribution of lactobacilli EVs could be a strain-specific or a species-associated characteristic and whether culturing or environmental conditions could influence the release of these structures.…”