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

Abstract

Background Lactobacillus reuteri strains are widely used as probiotics to prevent and treat inflammatory bowel disease by modulating the host’s immune system. However, the underlying mechanisms by which they communicate with the host have not been clearly understood. Bacterial extracellular vesicles (EVs) have been considered as important mediators of host-pathogen interactions, but their potential role in commensals-host crosstalk has not been widely studied. Here, we investigated the regulatory actions of EVs produced by L. reuteri BBC3, a gut-associated commensal bacterium of Black-Bone chicken, in the development of lipopolysaccharide (LPS)-induced intestinal inflammation in a chicken model using both in vivo and in vitro experiments. Results L. reuteri BBC3 produced nano-scale membrane vesicles with the size range of 60–250 nm. Biochemical and proteomic analyses showed that L. reuteri BBC3-derived EVs (LrEVs) carried DNA, RNA and several bioactive proteins previously described as mediators of other probiotics’ beneficial effects such as glucosyltransferase, serine protease and elongation factor Tu. In vivo broiler experiments showed that administration of LrEVs exerted similar effects as L. reuteri BBC3 in attenuating LPS-induced inflammation by improving growth performance, reducing mortality and decreasing intestinal injury. LrEVs suppressed the LPS-induced expression of pro-inflammatory genes (TNF-α, IL-1β, IL-6, IL-17 and IL-8), and improved the expression of anti-inflammatory genes (IL-10 and TGF-β) in the jejunum. LrEVs could be internalized by chicken macrophages. In vitro pretreatment with LrEVs reduced the gene expression of TNF-α, IL-1β and IL-6 by suppressing the NF-κB activity, and enhanced the gene expression of IL-10 and TGF-β in LPS-activated chicken macrophages. Additionally, LrEVs could inhibit Th1- and Th17-mediated inflammatory responses and enhance the immunoregulatory cells-mediated immunosuppression in splenic lymphocytes of LPS-challenged chickens through the activation of macrophages. Finally, we revealed that the reduced content of both vesicular proteins and nucleic acids attenuated the suppression of LrEVs on LPS-induced inflammatory responses in ex vivo experiments, suggesting that they are essential for the LrEVs-mediated immunoregulation. Conclusions We revealed that LrEVs participated in maintaining intestinal immune homeostasis against LPS-induced inflammatory responses in a chicken model. Our findings provide mechanistic insight into how commensal and probiotic Lactobacillus species modulate the host’s immune system in pathogens-induced inflammation.

Effect of Extracellular Vesicles Derived From Lactobacillus plantarum Q7 on Gut Microbiota and Ulcerative Colitis in Mice

“…Probiotics can protect the intestinal mucosal barrier, inhibit intestinal inflammation, and maintain the balance of the gut microbiota structure ( 31 ), which may offer an alternative or adjuvant strategy to UC therapy ( 35 ). Probiotics-derived EVs has attracted increasing attention due to the potential for the treatment of multiple diseases, such as inflammation ( 17 , 18 , 22 ), bacterial infection ( 19 ) and obesity ( 36 ). L. plantarum Q7 was isolated from Chinese traditional food in our previous study ( 21 ).…”

“…Lactobacillus rhamnosus GG derived EVs played a role in anti-proliferative on HepG2 cancer cells ( 16 ). Lactobacillus reuteri BBC3 derived EVs inhibited the inflammatory response mediated by activating macrophages, and played an important role in intestinal immune regulation ( 17 ). Lactobacillus plantarum derived EVs could be used as anti-inflammatory and immunomodulatory substances to improve inflammatory skin diseases and had the potential in treating antimicrobial-resistant pathogens ( 18 , 19 ).…”

Effect of Human Periodontal Ligament Stem Cell-Derived Extracellular Vesicles on Macrophage Pyroptosis and Periodontal Inflammatory Injury in Periodontitis

“…EVs from adipose tissue-derived stem cells reduce the contents of pro-inflammatory cytokines including IL-1β in LPS-stimulated macrophages [Bai et al, 2020]. Moreover, EVs from other cell sources such as Lactobacillus reuteri and platelet show an inhibitory effect on LPS-induced IL-1β level [Vats et al, 2020;Hu et al, 2021]. All this indicates that different sources of EVs have different effects on IL-1β level.…”

Association of Probiotic Supplementation with Improvements in the Gut Microbes, Blood Lipid Profile and Caecal Villus Morphology of Broilers

“…L. salivarius isolated from chickens improves the growth performance, increases the weights of immune organs, decreases the concentrations of odor-causing compounds, and alleviates organ injury caused by E. coli O78 challenge and heat stress [18]. L. reuteri maintains the immune homeostasis of the intestine in response to lipopolysaccharide-induced inflammation in broilers [19]. L. salivarius CH24 improves the total LAB in the caecum, increases the body weight and highdensity lipoprotein (HDL) amount, and reduces the level of uric acid in broilers [20].…”