Aflatoxin B1 (AFB1) is a mycotoxin that widely found in the environment and mouldy foods. AFB1 initially targets the intestine, and AFB1-induced intestinal injury cannot be ignored. Lactobacillus amylovorus (LA), a predominant species of Lactobacillus, plays a role in carbohydrate metabolism. Extracellular vesicles (EVs), small lipid membrane vesicles, are widely involved in diverse cellular processes. However, the mechanism by which Lactobacillus amylovorus-QC1H-derived EVs (LA.EVs) protect against AFB1-induced intestinal injury remains unclear. In our study, a new strain named Lactobacillus amylovorus-QC1H (LA-QC1H) was isolated from pig faeces. Then, EVs derived from LA-QC1H were extracted via ultracentrifugation. Our results showed that LA.EVs significantly alleviated AFB1-induced intestinal injury by inhibiting the production of proinflammatory cytokines, decreasing intestinal permeability and increasing the expression of tight junction proteins. Moreover, 16 S rRNA analysis revealed that LA.EVs modulated AFB1-induced gut dysbiosis in mice. However, LA.EVs did not exert beneficial effects in antibiotic-treated mice. LA.EVs treatment increased intestinal levels of indole-3-acetic acid (IAA) and activated intestinal aryl hydrocarbon receptor (AHR)/interleukin-22 (IL-22) signalling in AFB1-exposed mice. Inhibition of intestinal AHR signalling markedly weakened the protective effect of LA.EVs in AFB1-exposed mice. LA.EVs alleviated AFB1-induced intestinal injury by modulating the gut microbiota, activating the intestinal AHR/IL-22 signalling, reducing the inflammatory response and promoting intestinal barrier repair in mice.

Background: Innate lymphoid cells (ILCs), as an important group of innate immunity, could respond rapidly to Mycobacterium tuberculosis (Mtb) infection. In this research, we studied the phenotypic changes of circulatory ILCs in active tuberculosis (TB) disease. Methods: We recruited 40 patients with active Mtb infection (TB group) and 41 healthy subjects (NC group), and collected their clinical information and peripheral blood. Circulating ILCs, ILC subsets, dendritic cells (DCs), macrophages, and the production of cytokines in ILCs were tested by flow cytometry (FCM). Enzyme-linked immunosorbent assay (ELISA) was used to detect plasma IL-23. Results: Compared with healthy control, total ILCs (0.73% vs. 0.42%, P = 0.0019), ILC1 (0.55% vs. 0.31%, P = 0.0024) and CD117⁺ ILC2 (0.02% vs. 0.01%, P = 0.0267) were upregulated in TB group. The total IL-17⁺ lymphocytes were elevated (3.83% vs. 1.76%, P = 0.0006) while the IL-22⁺ lymphocytes remained unchanged. Within ILC subsets, ILC3, CD117⁺ ILC2 and ILC1 in TB group all expressed increased IL-17 (15.15% vs. 4.55%, 19.01% vs. 4.57%, 8.79% vs. 3.87%, P < 0.0001) but similar IL-22 comparing with healthy control. TB group had more plasma IL-23 than NC group (7.551 vs. 5.564 pg/mL, P = 0.0557). Plasma IL-23 in TB group was positively correlated to IL-17⁺ ILC3 (r = 0.4435, P = 0.0141), IL-17⁺CD117⁺ ILC2 (r = 0.5385, P = 0.0021) and IL-17⁺ ILC1(r = 0.3719, P = 0.0430). TB group also had elevated DCs (9.35% vs. 6.49%, P < 0.0001) while macrophages remained unchanged. Within TB group, higher proportion of IL-17⁺ ILCs was related to severer inflammatory status and poorer clinical condition. Conclusions: In active TB disease, circulatory ILCs were upregulated and exhibited IL-17-expressing phenotype. This may expand the understanding of immune reaction to Mtb infection.

Gut-liver axis disturbance is the unifying pathogenesis of cholestatic liver diseases. The purpose of this study was to explore the underlying mechanisms of the probiotic Lactobacillus amylovorus (LA) and its secreted extracellular vesicles (EVs) on liver damage and fibrosis in 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC)-fed and multidrug resistance protein 2 knockout (Mdr2^-/-) mice. Direct replenishment of LA is sufficient to correct the DDC-fed and Mdr2^-/--induced liver damage and fibrosis. Mechanistic studies show that the secretion of EVs is required for the LA-induced liver protective effects. RNA sequencing results demonstrated that the enrichment of differentially expressed genes was associated with glutathione metabolism, microbial metabolism in diverse environments and inflammatory mediator regulation of TRP channels in DDC-fed mice. Our findings revealed that LAEVs reshaped the gut microbiota, which was associated with increased bile acids (BAs) deconjugation and fecal BAs excretion, repaired gut barrier function, activated intestinal Farnesoid X receptor/Fibroblast growth factor 15 (FXR/FGF-15) axis, reduced liver BAs and oxidative stress level, which ultimately mitigated liver damage and fibrosis in both DDC-fed and Mdr2^-/- mice. Notably, LAEVs did not ameliorate DDC-induced liver damage or fibrosis in antibiotic-treated mice. Furthermore, LAEVs provided protection against DDC-induced liver injury and fibrosis in fecal microbiota transplantation mice. LAEVs did not ameliorate DDC-induced liver damage or fibrosis in BSH inhibitor (CAPE)-treated mice. LAEVs also failed to improve liver damage and fibrosis in DDC-induced intestinal epithelial cell-specific FXR knockout (Fxr^△IE) mice. This study revealed that LAEVs mitigated cholestatic liver fibrosis via regulating gut microbiota-bile acid-ROS axis in mice.

Background Aflatoxin B1 (AFB1) is a mycotoxin that widely exists in the environment and mouldy foods. The organ initially targeted by AFB1 is the intestine, and AFB1-induced intestinal injury cannot be ignored. Lactobacillus amylovorus, a predominant species of Lactobacillus, exerts carbohydrate metabolic functions. Extracellular vesicles (EVs), small lipid membrane vesicles, are widely involved in diverse cellular processes. However, the mechanism by which Lactobacillus amylovorus-QC1H-derived EVs (LA.EVs) protects against AFB1-induced intestinal injury remains unclear. Results In our study, a new strain named Lactobacillus amylovorus-QC1H (LA-QC1H)was isolated from pigfaeces. Then, EVs derived from LA-QC1H were prepared by ultracentrifugation. Our study showedthat LA.EVs significantly alleviated AFB1-induced inflammatory intestinal injury by inhibiting the production of proinflammatory cytokines and decreasing intestinal permeability. Meanwhile, 16S rRNA analysis showed that LA.EVs remodelled AFB1-induced gut dysbiosis in mice. However, LA.EVs failed to exert beneficial effects in antibiotic-treated mice. LA.EVs treatment resulted in higher intestinal levels of indole-3-acetic acid(IAA) and activating intestinal aryl hydrocarbon receptor (AHR)/IL-22 signalling in AFB-exposed mice. Inhibition of intestinal AHR signalling markedly weakenedthe protective effect of LA.EVs in AFB-exposed mice. Conclusions LA.EVs alleviated AFB1-induced inflammatory intestinal injury by remodelling the gut microbiota and activating intestinal AHR/IL-22 signalling in mice. Our study provides a new strategy for using LA.EVs as a therapeutic method to prevent AFB1-induced inflammatory intestinal injury.