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Lactobacillus plantarum AR495 is a widely used probiotic for the treatment of various digestive diseases, including irritable bowel syndrome (IBS). However, the specific mechanisms of L. plantarum AR495 in alleviating IBS remain unclear. Abnormal intestinal tryptophan metabolism can cause disordered immune responses, gastrointestinal peristalsis, digestion and sensation, which is closely related to IBS pathogenesis. The aim of this study is to explore the effects and mechanisms of L. plantarum AR495 in regulating tryptophan metabolism. Primarily, tryptophan and its related metabolites in patients with IBS and healthy people were analyzed, and an IBS rat model of acetic acid enema plus restraint stress was established to explore the alleviation pathway of L. plantarum AR495 in tryptophan metabolism. It was found that the 5-HT pathway was significantly changed, and the 5-HTP and 5-HT metabolites were significantly increased in the feces of patients with IBS, which were consistent with the results obtained for the IBS rat model. Maladjusted 5-HT could increase intestinal peristalsis and lead to an increase in the fecal water content and shapeless stool in rats. On the contrary, these two metabolites could be restored to normal levels via intragastric administration of L. plantarum AR495. Further study of the metabolic pathway showed that L. plantarum AR495 could effectively reduce the abundance of 5-HT by inhibiting the expression of enterochromaffin cells rather than promoting its decomposition. In addition, the results showed that L. plantarum AR495 did not affect the expression of SERT. To sum up, L. plantarum AR495 could restore the normal levels of 5-HT by inhibiting the abnormal proliferation of enterochromaffin cells and the excessive activation of TPH1 to inhibit the intestinal peristalsis in IBS. These findings provide insights for the use of probiotics in the treatment of IBS and other diarrheal diseases.

Western diet is thought to increase susceptibility to inflammatory bowel disease (IBD), and probiotics are a potential therapeutic agent for IBD. This study revealed the effects of Lactobacillus plantarum AR113 and L. plantarum AR113Δ bsh 1 on a dextran sulfate sodium (DSS)-induced colitis mouse model under the Western diet (WD). After four weeks of WD and low-sugar and low-fat diet (LD) intervention, induction with 3% DSS, and intragastric administration of probiotics, we found that L. plantarum AR113 could regulate blood glucose and lipid levels and have a certain protective effect on hepatocytes. Our results suggested that the L. plantarum AR113 alleviated DSS-induced colitis under the Western diet by improving dyslipidemia, repairing intestinal barrier dysfunction, and inhibiting the TLR4/Myd88/TRAF-6/NF-κB inflammatory pathway. However, these changes were not demonstrated in the L. plantarum AR113Δ bsh 1, and therefore, we reasoned that the presence of bsh 1 may play a crucial role in the L. plantarum AR113 exerting its anti-inflammatory function. The relationship between bile salt hydrolase (BSH) and colitis was worthy of further exploration.

Lactiplantibacillus plantarum is an important member of the probiotic family and colonization of the host intestinal is essential for its continued probiotic function. The mechanism of L. plantarum intestinal colonization has not been elucidated until now, an important reason being that the colonization process is influenced by a number of factors. In this study, to confirm the influences of adhesion ability and host intestinal environment on L. plantarum intestinal colonization, knockouts of L. plantarum AR113 mucin genes were constructed using CRISPR/Cas9 gene editing technology, and polyethylene glycol was used to reduce the intestinal flora abundance. The knockout of L. plantarum AR113 mucin genes barely altered the strain's tolerance to acid and bile salts. Notably, the adhesion number of AR113ΔLp_1431ΔLp_2233ΔLp_2792 to HT-29 cells was reduced from 175 to 114 per 100 cells. Through in vivo colonization experiments, an increase in the fluorescence intensity of AR113 and AR113ΔLp_1431&2233&2792 was detected the day after the mice were fed, while the deletion of Lp_1431, Lp_2233 and Lp_2792 genes reduced the intestinal tract colonization time from 14 to 11 days. Both AR113 and AR113ΔLp_1431ΔLp_2233ΔLp_2792 were reproduced in the intestine by labeling with 5-(6)-carboxyfluorescein diacetate N-succinimidyl ester. The results showed that the change in fluorescence intensity was closely dependent on the number of adhesions. Finally, compared to the control group, the prolonged intestinal colonization time of AR113ΔLp_1431ΔLp_2233ΔLp_2792 increased mice intestinal flora abundance, with distributions in the duodenum, jejunum, ileum and colon. Collectively, both the intestinal environment and the adhesion ability of L. plantarum AR113 affected intestinal colonization, and the host's intestinal genetic background may be a key factor in the intestinal colonization of L. plantarum., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Background: Adhesion is considered important for Lactiplantibacillus to persist in the human gut and for it to exert probiotic effects. Lactiplantibacillus plantarum contains a considerable number and variety of genes encoding bile salt hydrolases (bsh), but their effects on microbial adhesion remain poorly understood. To clarify the effects of four bsh on adhesion, we tried to knock out bsh (Δbsh) of L. plantarum AR113 using the CRISPR-Cas9 method, and compared the growth, auto-aggregation (R AA ), co-aggregation (R CA ), surface hydrophobicity (A HC ) of AR113 wild-type and Δbsh strains and their adhesion abilities to HT29 cells., Results: We first obtained the AR113 Δbsh1,3,2,4 strain with four bsh knocked out. Their growth was significantly slower than the wild-type strain cultured in De Man, Rogosa, and Sharpe medium (MRS) with 3.0 g L -1 glyco- or tauro-conjugated bile acid. Bsh had no significant effect on the growth of ten strains cultured in MRS, but Δbsh1 inhibited their growth when cultured in MRS containing 3.0 g L -1 sodium glycocholate, whereas Δbsh4 instead promoted their growth in MRS with 3.0 g L -1 sodium glycocholate and sodium taurocholate. R CA and R AA were linearly positive for all strains except AR113 Δbsh2,4, and A HC and R AA were negatively correlated for most strains excluding AR113 Δbsh2, with R AA  = 6.38-25.05%, R CA  = 5.17-9.22%, and A CH  = 3.22-47.71%. The adhesion ability of ten strains cultured in MRS was higher than that of strains cultured in MRS with 3.0 g L -1 bovine bile, and it was related to bsh2., Conclusion: Bsh differentially affected the adhesion of AR113 series strains. This adds to the available information about substrate-gene-performance, and provides new information to enable engineering to regulate the colonization of Lactiplantibacillus. © 2021 Society of Chemical Industry., (© 2021 Society of Chemical Industry.)

The resistance of Lactobacillus plantarum to vancomycin depends on its peptidoglycan composition. Vancomycin has poor binding affinity with peptidoglycan precursors ending in D-alanyl-D-lactate (D-Ala-D-Lac) but binds strongly to peptidoglycan precursors ending in D-alanyl-D-alanine (D-Ala-D-Ala), resulting in resistance and sensitivity, respectively. The ligase Ddl, which generates D-Ala-D-Lac or D-Ala-D-Ala incorporated into the peptidoglycan precursor chain, is responsible for this specificity. To study the effect of peptidoglycan precursors on immunity, we constructed several strains of L. plantarum expressing the ddl gene of Lactococcus lactis to change their peptidoglycan precursors. The change in the termini of the peptidoglycan precursors was determined by the sensitivity of the strains to vancomycin. The overexpression of ddl increased the susceptibility of the strains to vancomycin. We further explored the regulation of the macrophage inflammatory response pathway by the wild-type and constructed strains, and found that these strains induced the MyD88-dependent TRAF6/MAPK pathway, and the increase in D-Ala L. plantarum peptidoglycan precursors increased the secretion of the inflammatory factors IL-6, IL-1β and TNF-α. These results indicate that D-Ala-ended peptidoglycan precursors play a central role in the variable immunomodulatory ability of L. plantarum ., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Song, Li, Zhang, Xia, Ai and Wang.)

Probiotics plays an important role in regulating gut microbiota and maintaining intestinal homeostasis. Extracellular vesicles (EVs) derived from probiotics have emerged as potential mediators of host immune response and anti-inflammatory effect. However, the anti-inflammatory effect and mechanism of probiotics derived EVs on inflammatory bowel disease (IBD) remains unclear. In this study, the effect of Lactobacillus plantarum Q7-derived extracellular vesicles (Q7-EVs) on gut microbiota and intestinal inflammation was investigated in C57BL/6J mice. The results showed that Q7-EVs alleviated DSS-induced colitis symptoms, including colon shortening, bleeding, and body weight loss. Consumption of Q7-EVs reduced the degree of histological damage. DSS-upregulated proinflammatory cytokine levels including IL-6, IL-1β, IL-2 and TNF-α were reduced significantly by Q7-EVs ( p < 0.05). 16S rRNA sequencing results showed that Q7-EVs improved the dysregulation of gut microbiota and promoted the diversity of gut microbiota. It was observed that the pro-inflammatory bacteria (Proteobacteria) were reduced and the anti-inflammatory bacteria ( Bifidobacteria and Muribaculaceae ) were increased. These findings indicated that Q7-EVs might alleviate DSS-induced ulcerative colitis by regulating the gut microbiota., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Hao, Zhang, Tong, Liu, Liang, Bu, Gong, Liu, Zhang, Xia, Ai and Yi.)

The beneficial effects of probiotics on inflammatory bowel disease (IBD) are well known, although an understanding of colonisation by endogenous and exogenous bacterial strains and the effects on intestinal inflammation remains elusive. In this study, the colonisation of endogenous Lactobacillus reuteri R28 and exogenous Lactobacillus plantarum AR17-1 was investigated in healthy or PEG-treated mice using a 5(6)-carboxyfluorescein diacetate N-succinimidyl ester (cFDA-SE) labelling technique. The effects of these strains on mice with colitis induced by DSS and treated with PEG + DSS were also studied. Endogenous L. reuteri R28 and exogenous L. plantarum AR17-1 exhibited no significant differences in colonisation in healthy mice, whereas after PEG treatment, colonisation of the intestinal mucosa by L. reuteri R28 was greatly enhanced. L. reuteri R28 more effectively reduced diarrhoea caused by PEG, and L. plantarum AR17-1 more effectively reduced the colitis induced by PEG + DSS and downregulated the expression of the pro-inflammatory cytokines TNF-α, IL-1β, and IL-6. These results suggest that endogenous L. reuteri R28 may easily adapt to the intestinal environment, leading to better colonisation, whereas L. plantarum AR17-1 has a stronger inhibitory effect on inflammation. This finding is relevant to the selection of probiotics.

It has been reported that Lactobacillus can remove cholesterol and thus might play an important role in lowering cholesterol in humans, but the underlying mechanism is still controversial. To confirm whether different strains have different cholesterol-lowering mechanisms, we explored the cholesterol-lowering abilities of different Lactobacillus plantarum strains, and the factors influencing their abilities. We found that all nine strains reduced the cholesterol concentration to some extent, but there were significant differences among them. In MRS broth, L. plantarum AR113 and AR171 showed the greatest cholesterol-lowering abilities of 27.89% and 19.90%, respectively, but AR501 and AR300 only showed reductions of 0.34% and 0.91%, respectively. Upon addition of 0.1% ox bile, the cholesterol-removal capability of most strains increased. L. plantarum AR511 showed the highest cholesterol removal rate, which increased from 5.8% to 37.14%, i.e., by a factor of approximately 6.4, but there was no significant change in the cholesterol removal rate of AR171. These results suggested that the effect of ox bile on the cholesterol-lowering ability was strain-specific. Except for the strains AR171, AR237 and AR495, the cholesterol-removal ability of the remaining six strains was positively correlated with the amount of free bile acid released. The addition of a bile salt hydrolase inhibitor had some effect on the cholesterol-removal ability of the six strains of bacteria other than AR171, AR237 and AR495, but little influence on the latter three. The effect of BSH was strain-specific. Similarly, the effect of pH was also strain-specific. Taken together, these results suggest that different strains of L. plantarum have different cholesterol-lowering capacities and different influencing factors. Therefore, further research is needed to explore the exact mechanism by which different strains lower cholesterol.

Hypercholesterolemia is closely associated with cardiovascular disease. Supplementation with probiotics has been shown to contribute to improving lipid metabolism. The probiotic mechanisms of cholesterol reduction are complicated and remain unclear. One of the potential probiotic mechanisms for cholesterol reduction is the deconjugation of bile salts. We previously found a high bile salt hydrolase (BSH) activity of Lactobacillus casei pWQH01 (overexpression of bsh1) and Lactobacillus plantarum AR113, but found no BSH activity for Lactobacillus casei LC2W in vitro. Therefore, we decided to investigate whether the high BSH activity of L. plantarum AR113 and L. casei pWQH01 could exert a cholesterol-reducing effect in vivo. Compared to the high-cholesterol diet (HCD) group, AR113 and pWQH01 groups had a significantly lower body weight (BW), serum total cholesterol (TC), low density lipoprotein cholesterol (LDL-C) levels and atherogenic index (AI), whereas the LC2W group had a poor capability to mitigate the blood lipid levels in the hypercholesterolemic mice. In addition, the AR113 and pWQH01 groups decreased the hepatic levels of TC and LDL-C and improved hepatic steatosis compared with the HCD group. To explore their cholesterol-lowering mechanisms of action, we determined the expression levels of these genes on the cholesterol metabolic pathways. AR113 and pWQH01 groups downregulated the expression of farnesoid X receptor (FXR) and small heterodimer partner (SHP) genes, but upregulated the expression of the cholesterol 7α-hydroxylase (CYP7A1) gene in the liver. Simultaneously, the expression of cholesterol liver X receptor (LXR) and low density lipoprotein receptor (LDLR) genes was upregulated in the liver. These results indicated that L. plantarum AR113 and L. casei pWQH01 could inhibit the cholesterol absorption and accelerate the cholesterol transportation. Taken together, these findings suggest that Lactobacillus strain overexpression of bile salt hydrolase has beneficial effects against hypercholesterolemia by reducing cholesterol absorption and increasing cholesterol catabolism.

Lactic acid bacteria (LAB) have been used as ingredients of functional foods to promote health and prevent diseases because of their beneficial effects. This study aimed to investigate the antioxidative effects of LAB on the hepatotoxicity in D-galactose-induced aging mice. LAB were isolated from the traditional Chinese fermented foods and screened by the tolerance of hydrogen peroxide (H 2 O 2 ). Male ICR (Institute of Cancer Research) mice were subcutaneously injected with D-galactose for 5 weeks and then gastric gavage with LAB for 6 weeks. The results showed that Lactobacillus plantarum AR113 and AR501, and Pediococcu pentosaceus AR243 could tolerate up to 1.5 mM H 2 O 2 in vitro, and they could live through simulated gastrointestinal tract (GIT) to colonizing the GIT of host. In vivo, oral administration of L. plantarum AR113 and AR501 improved the antioxidant status of D-galactose-induced oxidative stress mice such as alleviated liver damages and reduced abnormal activities of superoxide dismutase, glutathione peroxidase, and catalase to normal levels. In addition, L. plantarum AR501 markedly elevated the gene expression of nuclear factor erythroid-2-related factor 2 and upregulated the expressions of several antioxidant genes such as glutathione reductase, glutathione S-transferase, glutamate-cysteine ligase catalytic subunit, glutamate-cysteine ligase modifier subunit, and NAD(P)H quinone oxidoreductase 1 in the liver of an aging mice. Therefore, L. plantarum AR501 could be a good candidate for producing antiaging functional foods., (© 2018 Institute of Food Technologists®.)

[Display omitted] • Osteoporosis-related fracture causes morbidity and mortality. • Intestinal health has been linked to osteoporosis prevention. • Probiotics improved intestinal flora and exerted anti-osteoporotic effects. • Probiotics modulated ovariectomy-induced osteoporosis with strain differences. Osteoporosis is a common skeletal disease in which bone resorption exceeds bone formation. Intestinal health has been linked to reduced osteoporosis. The aim of this study was to compare the anti-osteoporotic and intestinal health effects of two strains of Lactobacillus plantarum (AR237 and AR495) in ovariectomized (ovx) C57BL/6 mice. The results showed that AR495 significantly inhibited ovx-induced bone loss, reduced intestinal permeability, increased the expression of tight junction proteins, claudin-family proteins, zonula occludens-1 (ZO-1), and junctional adhesion molecule 3 (JAM-3) in ovx mice. Furthermore, AR495 inhibited bone resorption by modulating the receptor activator for nuclear factor kappa B (RANK)/RANK ligand (RANKL)/osteoprotegerin (OPG) system, and ameliorated ovx-induced intestinal inflammatory responses. AR495 improved intestinal microbial stability, and increased the abundance of short-chain fatty acids (SCFA)-producing bacteria and fecal SCFA content of ovx mice. Overall, the findings of this study showed that AR495 was more effective than AR237 at treating osteoporosis. [ABSTRACT FROM AUTHOR]

• L. plantarum AR113 could alleviate symptoms of colitis and prevent tissue damage effectively. • L. plantarum AR113 could maintains intestinal barrier by recover goblet cell and tight junction. • HO-1 upregulated could inhibit TLR4/MyD88/NF-κB pathway and reduce pro-inflammatory factors. • L. plantarum AR113 could mitigate dysbiosis of gut microbiota induced by DSS. Probiotics are a potential treatment agent for IBD. In this study, the effects of probiotics on intestinal immune responses and gut microbiota in colitis were investigated. The result showed that L. plantarum AR113 and L. casei AR342 were 2–3 times more effective than other strains to alleviate epithelial damage indicators, improve colon length (+10–30%) and maintain the integrity of the epithelial barrier, as compared to DSS-treatment mice. The supplementation downregulated expression of pro-inflammatory cytokines (TNF-α, IL-1β, IL-6) and upregulated that of the colonic anti-inflammatory cytokine (IL-10). The results strongly suggested that anti-inflammatory effect of probiotics is associated with the increase in HO-1 expression and the decrease in TLR4/MyD88/NF-κB pathway expression in mouse colonic tissues. Further, Microbiota analysis and the correlation of microbiota with colitis parameters revealed that the dysbiosis of gut microbiota induced by DSS treatment could be mitigated to a certain extent by supplementation with L. plantarum AR113. [ABSTRACT FROM AUTHOR]

Abstract The optimal cryoprotectants combination, freezing rate and thawing temperature were investigated for preserving Lactobacillus plantarum and Lactobacillus casei during freezing and frozen storage. It is indicated that, among all cryoprotectants applied singly, 150 g/L and 100 g/L sucrose provided the best protective effect for L. plantarum and L. casei , respectively (survival rate = 74.4% and 84.8%, respectively). By using orthogonal experimental design for cryoprotectant mixtures, the mixture of trehalose, sucrose, glycerol and skimmed milk at final concentration of 12.5, 12.5, 37.5 and 25.0 g/L, respectively, appeared to enhance significantly the survival rate of L. plantarum (92.8%) and L. casei (91.2%). Among all freezing and thawing conditions examined, the survival rate of L. plantarum was the highest at a freezing rate of −10 °C/min and thawing temperature of 0 °C; and that of L. casei , at a freezing rate of −1 °C/min and thawing temperature of 0 °C. The cryoprotectant effect exerted by keeping the integrity of cell membrane and therefore maintaining the lactobacilli survival. Highlights • The optimal cryoprotectants combination significantly enhanced the survival rate of L. plantarum and L. casei. • The optimal survival rate and thawing temperature of L. plantarum and L. casei were investigated. • The damage of cell membrane was considered to be an important cause of death during freezing-thawing. [ABSTRACT FROM AUTHOR]

The resistance of probiotics to bile salts is critical to their survive in the intestinal tract. Bile salt hydrolase (BSH) catalyzes the deconjugation of conjugated bile salts and is thought to be involved in bile salt resistance. The aim of this study was to explore the roles of different bsh genes in the bile salt resistance of Lactobacillus plantarum AR113. CRISPR-Cas9 gene editing was used to construct single, double, and triple bsh knockout strains. The functions of the bsh 1, and bsh 3 genes were found to be critical for BSH activity in L. plantarum AR113. Examination of six bile salts revealed that glycine-conjugated bile salts were the preferred substrate of BSH. The growth of strains with bsh1 or bsh3 knockout was significantly inhibited when treated with glycine-conjugated bile salts. However, strains with bsh2 or bsh4 knockout were not affected. These results suggested that bsh 1 and bsh 3 are closely related to bile salt resistance. This result will be useful for the rational, high-throughput selection of strains with high tolerance to bile salts. • bsh 1 and bsh 3 are critical for BSH activity in Lactobacillus plantarum AR113. •glycine-conjugated bile salts are the preferred substrate of BSH. •bsh 1 and bsh 3 are closely related to bile salt resistance. [ABSTRACT FROM AUTHOR]