Lactobacillus plantarum GUANKE modulate anti-viral function of dendritic cells in mice.

GUANKE is a Lactobacillus plantarum isolated from the feces of healthy volunteer. We have previously shown that GUANKE enhances the efficacy of the SARS-CoV-2 vaccine and prolongs the duration of vaccine protection by upregulating the IFN pathway and T and B lymphocyte functions of the host. The purpose of this study was to evaluate the protective effects and mechanism of oral administration of Lactobacillus plantarum GUANKE in the influenza (A virus A/Puerto Rico/8/34) infection mouse model. In our experiment, oral administration of GUANKE significantly decreased viral load and increased tight junction proteins expression in lung tissues of influenza-infected mice. After GUANKE was co-cultured with mBMDCs in vitro, mBMDCs' maturity and antiviral ability were enhanced, and matured mBMDCs induced polarization of naïve CD4+ T cells into T helper (Th) 1 cells. Adoptive transfer of GUANKE-treated mBMDCs could protect mice from influenza infections. This study suggests that oral administration of Lactobacillus plantarum GUANKE could provide protection against influenza infection in mice, and this protective effect may be mediated, at least in part, by dendritic cells.

Lactococcus cremoris D2022 alleviates hyperuricemia and suppresses renal inflammation via potential gut-kidney axis.

Hyperuricemia (HUA) is a widespread metabolic disorder. Probiotics have drawn increasing attention as an adjunctive treatment with fewer side effects. However, thus far the effective strains are limited and the mechanisms for their serum uric acid (SUA)-lowering effect are not well understood. Along this line, we conducted the current study using a hyperuricemia mouse model induced by potassium oxonate and adenine. A novel strain of Lactococcus cremoris named D2022 was identified to have significant SUA-lowering capability. Lactococcus cremoris D2022 significantly reduced SUA levels by inhibiting uric acid synthesis and regulating uric acid transportation. It was also found that Lactococcus cremoris D2022 alleviated HUA-induced renal inflammatory injury involving multiple signaling pathways. By focusing on the expression of NLRP3-related inflammatory genes, we found correlations between the expression levels of these genes and free fatty acid receptors (FFARs). In addition, oral administration of Lactococcus cremoris D2022 increased short-chain fatty acids (SCFAs) in cecal samples, which may be one of the mechanisms by which oral probiotics alleviate renal inflammation. Serum untargeted metabolomics showed changes in a variety of serum metabolites associated with purine metabolism and inflammation after oral administration of Lactococcus cremoris D2022, further confirming its systemic bioactivity. Finally, it was proved that Lactococcus cremoris D2022 improved intestinal barrier function. In conclusion, Lactococcus cremoris D2022 can alleviate HUA and HUA-induced nephropathy by increasing the production of SCFAs in the gut and systemic metabolism.

Pulsatillae radix extract alleviates DSS-induced colitis via modulating gut microbiota and inflammatory signaling pathway in mice.

Ethnopharmacological relevance: Ulcerative colitis (UC) is a chronic relapsing intestinal disease with complex pathogenesis. The increasing morbidity and mortality of UC become a global public health threat. Baitouweng decoction (BD), a formulated prescription of Traditional Chinese Medicine, has been applied to cure UC for many centuries. However, the therapeutic efficacy and working mechanisms of this medicine are not well studied. Aim of study: In this study we determined whether Pulsatillae radix, one of four ingredients in BD, had a therapeutic effect on colitis. And explore the underlying mechanism of Pulsatilla chinensis (Bunge) Regel radix in the improvement of DSS-induced colitis in mice model. Methods: The active compounds of Pulsatilla chinensis was identified by UPLC. The composition of the mice's cecum microbiota was determined by 16S rRNA sequencing. And gene expression profile of colon was detected by transcriptome. Results: The results showed that Pulsatillae radix significantly improved the clinical symptom, prevented the shorten of colon length, and decreased the diseased activity index (DAI) in an 3 % DSS-induced ulcerative colitis mouse model. We found that Pulsatillae radix reversed the dysbiosis of gut microbiota as evidenced by increase in the relative abundance of Bacteroidetes, Deferribacteres, and Proteobacteria phyla and decrease in Firmicutes, as well as by decrease in the genera levels of Bacteroides, Parabacteroides, Prevotella, Mucispirillum, Coprococcus, Oscillospira, and Escherichia. The results of transcriptome showed Pulsatillae radix administration led to 128 genes up-regulation, and 122 genes down-regulation, up-regulate NOD-like receptor signaling pathway, down-regulate Cytokine-cytokine receptor interaction, and TNF and IL-17 signaling pathways. Conclusion: in this study, we demonstrate Pulsatillae radix alleviates DSS-induced colitis probably via modulating gut microbiota and inflammatory signaling pathway in DSS-induced colitis mouse model.

Effects of Lactiplantibacillus plantarum GUANKE on Diphenoxylate-Induced Slow Transit Constipation and Gut Microbiota in Mice.

Slow transit constipation (STC) is a prevalent gastrointestinal condition with slow transit, and some probiotics can effectively relieve constipation, but the exact mechanisms have not been fully understood. In this study, we evaluate the impact of Lactiplantibacillus plantarum GUANKE (GUANKE) on diphenoxylate-induced slow transit constipation and speculate on the underlying mechanisms in a mouse model. Administration of L. plantarum GUANKE alleviated constipation indexes, including defecation time, fecal output and water content, and gastrointestinal transit ratio. In addition, GUANKE restored the protein expression of constipation-related intestinal factors (aquaporins (AQPs) and interstitial Cajal cells (ICCs)) in colon tissues measured using immunofluorescence staining; regulated the neurotransmitters and hormones, such as increased levels of 5-hydroxytryptamine, substance P, and motilin; and decreased levels of vasoactive intestinal peptide and nitric oxide in serum, as measured by an ELISA. 16S rRNA and correlation analysis of feces indicated that GUANKE administration effectively reduced constipation-induced Prevotella enrichment and suggested a potential contribution of Prevotella to diphenoxylate-induced STC in mice. GUANKE had no effect on short-chain fatty acids (SCFAs) in cecum content. This study revealed that GUANKE may alleviate constipation in mice through regulating intestinal neurotransmitter and hormone release and altering specific bacterial taxa, rather than by affecting SCFAs and the diversity of microbiota in the gut. Further research is needed to confirm if the findings observed in this study will be consistent in other animal studies or clinical trials.

Inhibiting virus replication and excessive inflammatory response: Mechanism of combined prescription of Ma-Xing-Shi-Gan decoction and Xiao-Chai-Hu decoction against influenza virus.

ETHNOPHARMACOLOGICAL RELEVANCE: The combined prescription of two classical decoctions (Ma-Xing-Shi-Gan decoction with Xiao-Chai-Hu decoction), named as San-Yang-He-Zhi (SYHZ) decoction, has been widely used for the treatment of influenza virus (IFV) infections for decades. AIM OF THE STUDY: This study aimed to evaluate the anti-influenza effect of SYHZ decoction and explore the underlying mechanism. MATERIALS AND METHODS: The ingredients of SYHZ decoction were analyzed by mass spectrometry. An animal model of IFV infection was established by challenging C57BL/6J mice with PR8 virus. Three groups of mice were infected with lethal or non-lethal doses of IFV, then followed by oral administration of phosphate-buffered saline (PBS), or SYHZ, or oseltamir; blank control mice (without IFV infection) were treated with PBS. Survival rate, Lung index, colon length, body weight loss and IFV viral load were measured 7 days post infection; histology and electron-microscopy examinations of lung tissue were performed; cytokine and chemokine levels in lung and serum were measured; and the intestinal metagenome, the cecum metabolome, and the lung transcriptome were analyzed. RESULTS: SYHZ treatment significantly improved survival rate compared with PBS (40% vs 0%); improved lung index, colon length, and body weight loss; and alleviated lung histological damage and viral load. SYHZ-treated mice had significantly lower levels of IL-1ß, TNF-α, IL-6, CCL2, CXCL10 in lung and serum, and increased levels of multiple bioactive components in cecum. Pro-inflammatory cytokines, Toll- and NOD-like receptors, pro-apoptosis molecules, and lung-injury-related proteins were downregulated in SYHZ mice, whereas surfactant protein and mucin were upregulated. The NOD-like receptor pathway, Toll-like receptor pathway, and NF-κB pathway were downregulated by SYHZ treatment. CONCLUSIONS: SYHZ decoction alleviated IFV infection in a mouse model. Multiple bioactive ingredients of SYHZ may inhibit replication of IFV and suppress excessive immune response.

Lactiplantibacillus pentosus P2020 protects the hyperuricemia and renal inflammation in mice.

Introduction: Hyperuricemia (HUA) is a common metabolic disease, and its prevalence has been increasing worldwide. Pharmaceutical drugs have been used for controlling HUA but they all have certain side effects, which thus calls for discovering alternative options including using treatment of probiotics to prevent the development of HUA. Methods: We established HUA mice model induced by potassium oxonate and adenine and performed in vivo experiments to verify the ability to lower serum uric acid of Lactiplantibacillus pentosus P2020 (LPP), a probiotics stain extracted from Chinese pickle. We also tried to discussed the underlying mechanisms. Results: Oral administration with LPP significantly decreased serum uric acid and reduced renal inflammatory response by downregulating multiple inflammation pathways including NK-kB, MAPK, and TNFα. We also found that LPP administration significantly promoted uric acid excretion by regulating expression of transporters in the kidney and ileum. In addition, LPP intake improved intestinal barrier function and modulated the composition of gut microbiota. Discussion: These results suggest that probiotics LPP may have a promising potential to protect against development of HUA and HUA-related renal damage, and its working mechanisms involve regulation of inflammation pathways and expression of transporters in the kidney and ileum.

Lactobacillus gasseri RW2014 Ameliorates Hyperlipidemia by Modulating Bile Acid Metabolism and Gut Microbiota Composition in Rats.

Hyperlipidemia is a leading risk of cardiovascular and cerebrovascular disease. Dietary supplementation with probiotics has been suggested as an alternative intervention to lower cholesterol. In the current study, we isolated a strain of Lactobacillus gasseri RW2014 (LGA) from the feces of a healthy infant fed with breast milk, and it displayed bile salt hydrolase (BSH) activity. Using this strain we determined its cholesterol-lowering and fatty liver-improving functions. SD rats were randomly divided into four groups. The control rats were fed a commercial chow diet and the other three groups were fed a high-fat diet (HFD) for a 7-week experiment period. After two weeks of feeding, the rats in PBS, simvastin, and LGA group were daily administered through oral gavage with 2 mL PBS, simvastin (1 mg/mL), and 2 × 109 CFU/mouse live LGA in PBS, respectively. After five weeks of such treatment, the rats were euthanized and tissue samples were collected. Blood lipid and inflammatory factors were measured by ELISA, gut microbiota was determined by 16S rRNA sequencing, and bile acids profiles were detected by metabolomics. We found that LGA group had lower levels of blood cholesterol and liver steatosis compared to the simvastin group. LGA also significantly reducedthe levels of inflammatory factors in the serum, including TNFα, IL-1ß, MCP-1, IL-6, and exotoxin (ET), and increased the levels of short-chain fatty acids in feces, including isobutyric acid, butyric acid, isovaleric acid, valeric acid, and hexanoic acid. In addition, LGA altered the compositions of gut microbiota as manifested by the increased ratio of Firmicutes/Bacteroides and the relative abundance of Blautia genus. Targeted metabolomics results showed that bile acids, especially free bile acids and secondary bile acids in feces, were increased in LGA rats compared with the control rats. Accordingly, the rats administrated with LGA also had a higher abundance of serum bile acids, including 23-norcholic acid, 7-ketolithocholic acid, ß-muricholic acid, cholic acid, and deoxycholic acid. Together, this study suggests that LGA may exert a cholesterol-lowering effect by modulating the metabolism of bile acids and the composition of gut microbiota.

Qingfeiyin Decoction Inhibits H1N1 Virus Infection via Modulation of Gut Microbiota and Inflammatory Pathways in a Murine Model.

Influenza virus-caused lung infection and its pandemic outbreaks are a persistent public health challenge. The H1N1 subtype is the most common type of influenza infection observed in humans. Maxingshigantang decoction, a classic formula of Chinese herbal medicine, has been used for the prevention and treatment of respiratory infection for many centuries. Qingfeiyin decoction, based on Maxingshigantang, has been used in the clinic for decades. To explore the underlying mechanisms, according to the traditional Chinese medicine theory "the lung and the large intestine are interior-exterior," which can be translated to the "gut-lung axis" in a contemporary term, the composition of gut microbiota was determined using 16S rRNA and the transcriptome of the colon was determined by RNA sequencing. The results showed that Qingfeiyin decoction decreased the viral load, alleviated the lung injury, increased the survival rate, partly restored the shortening of the colon caused by the H1N1 virus, and downregulated inflammatory pathways including MAPK, TNFα, and JAK-STAT signaling pathways. Qingfeiyin decoction increased the relative abundance of the genera of Coprococcus , Ruminococcus, Lactobacillus, and Prevotella and prevented the H1N1 virus-induced decrease in the abundance of the genera of Escherichia, Parabacteroides, Butyricimonas, and Anacrotruncus. These results will help better understand the mechanisms for Qingfeiyin decoction's protective effect against influenza virus infection.

Latilactobacillus sakei Furu2019 and stachyose as probiotics, prebiotics, and synbiotics alleviate constipation in mice.

Introduction: Slow transit constipation (STC) is a common disorder in the digestive system. This study aimed to evaluate the effects of stachyose (ST) and Latilactobacillus sakei Furu 2019 (L. sakei) alone or combined on diphenoxylate-induced constipation and explore the underlying mechanisms using a mouse model. Methods: ICR mice were randomly divided into five groups. The normal and constipation model groups were intragastrically administrated with PBS. The ST, L. sakei, and synbiotic groups were intragastrically administrated with ST (1.5 g/kg body weight), alive L. sakei (3 × 109 CFU/mouse), or ST + L. sakei (1.5 g/kg plus 3 × 109 CFU/mouse), respectively. After 21 days of intervention, all mice except the normal mice were intragastrically administrated with diphenoxylate (10 mg/kg body weight). Defecation indexes, constipation-related intestinal factors, serum neurotransmitters, hormone levels, short-chain fatty acids (SCFAs), and intestinal microbiota were measured. Results: Our results showed that three interventions with ST, L. sakei, and synbiotic combination (ST + L. sakei) all alleviated constipation, and synbiotic intervention was superior to ST or L. sakei alone in some defecation indicators. The RT-PCR and immunohistochemical experiment showed that all three interventions relieved constipation by affecting aquaporins (AQP4 and AQP8), interstitial cells of Cajal (SCF and c-Kit), glial cell-derived neurotrophic factor (GDNF), and Nitric Oxide Synthase (NOS). The three interventions exhibited a different ability to increase the serum excitatory neurotransmitters and hormones (5-hydroxytryptamine, substance P, motilin), and reduce the serum inhibitory neurotransmitters (vasoactive intestinal peptide, endothelin). The result of 16S rDNA sequencing of feces showed that synbiotic intervention significantly increased the relative abundance of beneficial bacteria such as Akkermansia, and regulated the gut microbes of STC mice. In conclusion, oral administration of ST or L. sakei alone or combined are all effective to relieve constipation and the symbiotic use may have a promising preventive effect on STC.

Stachyose inhibits vancomycin-resistant Enterococcus colonization and affects gut microbiota in mice.

Vancomycin-resistant Enterococcus (VRE) caused nosocomial infections are rising globally. Multiple measures have been investigated to address this issue, altering gut microbiota through dietary intervention represents one of such effort. Stachyose can promote probiotic growth, which makes it a good candidate for potentially inhibiting VRE infection. This study aimed to determine whether stachyose inhibits VRE colonization and investigated the involvement of gut microbiota this effect of stachyose. In VRE-infection experiment, 6-week old female C57/6 J mice pre-treated with vancomycin were infected with 2 × 108 CFU VRE via gavage. These mice then received oral administration of stachyose or PBS as control for 7days. Two groups of uninfected mice were also received daily gavage of stachyose or PBS for 7 days to observe the impact of stachyose treatment on normal mice. Fresh fecal and colon samples were collected, then VRE colonization, gut microbiota and gene expression were respectively assessed using cultivation, 16s rRNA sequencing and RNA-sequencing in two parallel experiment, respectively. In VRE-infected mice, stachyose treatment significantly reduced VRE colonization on days 9 and 10 post-infection. Stachyose treatment increased the relative abundance of Porphyromonadaceae, Parabacteroides, and Parabacteroides distasonis compared to the PBS-treated infection mice (P < 0.01). Uninfected mice treated with stachyose showed a significant increase in Lactobacillaceae and Lactobacillus compared to the PBS-treated uninfected mice(P < 0.05). RNA-sequencing results showed that stachyose treatment in VRE-infected mice increased expression of genes involved in TNF and IL-17 signaling pathways. Stachyose treatment also up-regulated Hsd17b14, Cyp3a44, Arg1, and down-regulated Pnliprp2, Ces1c, Pla2g4c genes involving in metabolic pathway in uninfected mice. In conclusion, stachyose supplementation can effectively inhibit VRE colonization and probably altering composition of the microbiome, which can in turn result in changes in expression of genes. Stachyose may also benefit health by increasing the abundance of Lactobacillus and expression of genes involving in metabolic pathway in normal mice.

A strain of Bacteroides thetaiotaomicron attenuates colonization of Clostridioides difficile and affects intestinal microbiota and bile acids profile in a mouse model.

Clostridioides difficile infection (CDI) is a growing global public health threat. While fecal microbiota transplantation (FMT) is an effective therapy for CDI, a number of challenges limit its application. Studies suggest that probiotics may be a promising alternative therapy. In the current study, we evaluated whether Bacteroides thetaiotaomicron (B. thetaiotaomicron) would inhibit colonization of toxigenic BI/NAP1/027 C. difficile in a mouse model. We found that B. thetaiotaomicron administration decreased the copies of C. difficile and inhibited inflammation in the colon. 16S rRNA sequencing showed that B. thetaiotaomicron administration was associated with a significantly increased relative abundance of Bacteroidetes and decreased level of Proteobacteria, leading to the reversal of the effect of antibiotics treatment and C. difficile infection on microbiota. B. thetaiotaomicron administration was associated with increases in the concentrations of alpha-muricholic acid, beta-muricholic acid, 12 ketolithocholic acid, and deoxycholic acid which are known to inhibit the growth of C. difficile, as well as reductions in the level of taurocholic acid, which promotes germination of C. difficile. Altered profile of major high abundance bile acids by B. thetaiotaomicron administration was similar to that with FMT treatment. Based on these results, we proposed the concept of "the ratio of promotion/inhibition BAs" which would advance our understanding of the relation of C. difficile and BAs.

A Novel Immunobiotics Bacteroides dorei Ameliorates Influenza Virus Infection in Mice.

Objective: Probiotics can modulate immune responses to resist influenza infection. This study aims to evaluate the anti-viral efficacy of B. dorei. Methods: C57BL/6J mice were infected with influenza virus together with treatment of PBS vehicle, B. dorei, or oseltamivir respectively. Anti-influenza potency of B. dorei and the underlying mechanism were determined by measuring survival rate, lung viral load and pathology, gene expression and production of cytokines and chemokines, and analysis of gut microbiota. Results: Administration of B. dorei increased (by 30%) the survival of influenza-infected mice, and improved their weight loss, lung pathology, lung index, and colon length compared to the vehicle control group. B. dorei treatment reduced (by 61%) the viral load of lung tissue and increased expression of type 1 interferon more rapidly at day 3 postinfection. At day 7 postinfection, B. dorei-treated mice showed lower local (lung) and systemic (serum) levels of interferon and several proinflammatory cytokines or chemokines (IL-1ß, IL-6, TNF-α, IL-10, MCP-1 and IP-10) with a efficacy comparable to oseltamivi treatment. B. dorei treatment also altered gut microbiota as indicated by increased levels of Bacteroides, Prevotella, and Lactobacillus and decreased levels of Escherichia, Shigella, and Parabacteroides. Conclusion: B. dorei has anti-influenza effect. Its working mechanisms involve promoting earlier interferon expression and down-regulating both local and systemic inflammatory response. B. dorei changes the composition of gut microbiota, which may also contribute to its beneficial effects.

Citrobacter freundii Activation of NLRP3 Inflammasome via the Type VI Secretion System.

Citrobacter freundii is a significant cause of human infections, responsible for food poisoning, diarrhea, and urinary tract infections. We previously identified a highly cytotoxic and adhesive C. freundii strain CF74 expressing a type VI secretion system (T6SS). In this study, we showed that in mice-derived macrophages, C. freundii CF74 activated the Nucleotide Oligomerization Domain -Like Receptor Family, Pyrin Domain Containing 3(NLRP3) inflammasomes in a T6SS-dependent manner. The C. freundii T6SS activated the inflammasomes mainly through caspase 1 and mediated pyroptosis of macrophages by releasing the cleaved gasdermin-N domain. The CF74 T6SS was required for flagellin-induced interleukin 1ß release by macrophages. We further show that the T6SS tail component and effector, hemolysin co-regulation protein-2 (Hcp-2), was necessary and sufficient to trigger NLRP3 inflammasome activation. In vivo, the T6SS played a key role in mediating interleukin 1ß secretion and the survival of mice during C. freundii infection in mice. These findings provide novel insights into the role of T6SS in the pathogenesis of C. freundii.

[Effects of Lactobacillus paragasseri Y20 on cholesterol-lowering, intestinal microbiota and liver metabolism in rats with hypercholesterolaemia].

OBJECTIVE: To evaluate the cholesterol-lowering effects of Lactobacillus paragasseri Y20 on rats with high cholesterol diet and its effect on the gut microbiota of rats, and to explore the potential mechanism of Lactobacillus paragasseri regulating hypercholesterolemia in rats. METHODS: Thirty rats were randomly divided into three groups and were treated with normal diet, high cholesterol diet+PBS, and high cholesterol diet+Lactobacillus paragasseri Y20, respectively. After five consecutive weeks of treatment, serum lipids were measured by ELISA. Rat feces were collected and DNA was extracted for 16 S rRNA amplicon sequencing analysis. Rat livers were collected and analyzed for non-targeted metabolites using high performance liquid chromatography. RESULTS: Compared with the high-cholesterol model group, Lactobacillus paragasseri Y20 treatment could reduce the serum triglyceride and low-density lipoprotein concentrations and increase the high-density lipoprotein concentration in rats. High-cholesterol diet decreased the intestinal flora diversity and richness of rats, while Y20 intervention can effectively restore the change of intestinal flora of high-cholesterol rats. High cholesterol dietsmainly caused the changes in the relative abundance in phylum of Firmicutes, Deferribacteres, Verrucomicrobia, and Proteobacteria, increasing Akkermansia, Clostridium_III, and Clostridium_XIVbgenera, and decreasing the intestinimonasgenus. However, Y20 intervention restored the diversity of gut microbiota and alteration in relative abundance of these bacteria caused by high-cholesterol diet. Y20 could effectively decrease the higher relative abundance of Akkermansiahigh-cholesterol diet. CONCLUSION: Lactobacillus paragasseri Y20 can alleviate hypercholesterolemia in rats, regulate the gut microbiotadiversity and composition and affect liver metabolism in hypercholesterol rats.

Effect of Lactobacillus plantarum HT121 on serum lipid profile, gut microbiota, and liver transcriptome and metabolomics in a high-cholesterol diet-induced hypercholesterolemia rat model.

OBJECTIVES: The aim of this study was to evaluate effect of Lactobacillus plantarum HT121 on serum lipid profile, gut microbiota, and liver transcriptome and metabolomics. METHODS: L. plantarum HT121 was selected by screening of acid and bile salt tolerance and cholesterol assimilation assay. Sprague Dawley rats were randomly divided into three groups and fed the respective diets for 7 wk: normal chow diet (NCD), high-cholesterol diet (HCD), and high-cholesterol diet plus L. plantarum HT121 (HT121). After 7 wk, blood lipid profile was measured by enzyme-linked immunosorbent assay, gut microbiota was determined by 16 S rRNA sequencing, gene expression, and bile acids in liver were detected by transcriptome and metabolomics, respectively. RESULTS: L. plantarum HT121 feeding decreased serum triacylglycerols (TGs), total cholesterol (TC), and low-density lipoprotein (LDL), and increased serum high-density lipoprotein levels. HT121 treatment increased the α-diversity in the HT121 group to a level close to that in the NCD group, and restored the genera of Adlercreutzia, Mucispirillum, Ruminococcus, Clostridium, Blautia, Roseburia, and Akkermansia to levels similar to those in the NCD group. Furthermore, the high-cholesterol diet decreased taurocholic acid (TCA) and increased taurochenodeoxycholic acid (TCDCA) and glycocholic acid (GCA) in the liver; all these changes were reversed by HT121 treatment, bringing the levels close to those in the NCD group. Finally, HT121 treatment increased expression of bile secretion-related genes Cyp7 a1 in rat liver, which was positively correlated with TG, Clostridium, and GCA. Spearman's correlation analysis showed that TGs, TC, and LDL were positively correlated with the relative abundance of genera of Blautia, Clostridium, and Roseburia, and levels of bile acid glycocholic acid, and inversely correlated with the relative abundance of Ruminococcus and Mucispirillum. CONCLUSIONS: L. plantarum HT121 can improve serum lipid profiles in a high-fat diet-induced rat model, which may be attributed to alteration in gut microbiota and bile acid metabolism.

Contribution of Nlrp3 Inflammasome Activation Mediated by Suilysin to Streptococcal Toxic Shock-like Syndrome.

Objective: The aim of this study was to investigate the molecular mechanism of inflammasome activation in response to Streptococcus suis serotype 2 (SS2) infection and its contribution to the development of streptococcal toxic shock-like syndrome (STSS). Methods: To verify the role of suilysin (SLY) in STSS, we infected bone-marrow-derived macrophages (BMDMs) in vitro and C57BL/6J mice intraperitoneally (IP) with the SS2 wild-type (WT) strain or isogenic sly mutant (∆SLY) to measure the interleukin (IL)-1ß release and survival rate. To determine the role of inflammasome activation and pyroptosis in STSS, we infected BMDMs from WT and various deficient mice, including Nlrp3-deficient (Nlrp3-/-), Nlrc4-deficient (Nlrc4-/-), Asc-deficient (Asc-/-), Aim2-deficient (Aim2-/-), Caspase-1/11-deficient (Caspase-1/11-/-), and Gsdmd-deficient (Gsdmd-/-) ex vivo, and IP injected WT, Nlrp3-/-, Caspase-1/11-/-, and Gsdmd-/- mice with SS2, to compare the IL-1ß releases and survival rate in vivo. Results: The SS2-induced IL-1ß production in mouse macrophages is mediated by SLY ex vivo. The survival rate of WT mice infected with SS2 was significantly lower than that of mice infected with the ∆SLY strain in vivo. Furthermore, SS2-triggered IL-1ß releases, and the cytotoxicity in the BMDMs required the activation of the NOD-Like Receptors Family Pyrin Domain Containing 3 (Nlrp3), Caspase-1/11, and gasdermin D (Gsdmd) inflammasomes, but not the Nlrc4 and Aim2 inflammasomes ex vivo. The IL-1ß production and survival rate of WT mice infected with SS2 were significantly lower than those of the Nlrp3-/-, Caspase-1/11-/-, and Gsdmd-/- mice in vivo. Finally, the inhibitor of the Nlrp3 inflammasome could reduce the IL-1ß release and cytotoxicity of SS2-infected macrophages ex vivo and protect SS2-infected mice from death in vivo. Conclusion: Nlrp3 inflammasome activation triggered by SLY in macrophages played an important role in the pathogenesis of STSS.

Activation of the Nlrp3 Inflammasome Contributes to Shiga Toxin-Induced Hemolytic Uremic Syndrome in a Mouse Model.

Objective: To explore the role of the Nlrp3 inflammasome activation in the development of hemolytic uremic syndrome (HUS) induced by Stx2 and evaluate the efficacy of small molecule Nlrp3 inhibitors in preventing the HUS. Methods: Peritoneal macrophages (PMs) isolated from wild-type (WT) C57BL/6J mice and gene knockout mice (Nlrc4-/-, Aim2-/-, and Nlrp3-/-) were treated with Stx2 in vitro and their IL-1ß releases were measured. WT mice and Nlrp3-/- mice were also treated with Stx2 in vivo by injection, and the biochemical indices (serum IL-1ß, creatinine [CRE] and blood urea nitrogen [BUN]), renal injury, and animal survival were compared. To evaluate the effect of the Nlrp3 inhibitors in preventing HUS, WT mice were pretreated with different Nlrp3 inhibitors (MCC950, CY-09, Oridonin) before Stx2 treatment, and their biochemical indices and survival were compared with the WT mice without inhibitor pretreatment. Results: When PMs were stimulated by Stx2 in vitro, IL-1ß release in Nlrp3-/- PMs was significantly lower compared to the other PMs. The Nlrp3-/- mice treated by Stx2 in vivo, showed lower levels of the biochemical indices, alleviated renal injuries, and increased survival rate. When the WT mice were pretreated with the Nlrp3 inhibitors, both the biochemical indices and survival were significantly improved compared to those without inhibitor pretreatment, with Oridonin being most potent. Conclusion: Nlrp3 inflammasome activation plays a vital role in the HUS development when mice are challenged by Stx2, and Oridonin is effective in preventing HUS.

Two Strains of Lactobacilli Effectively Decrease the Colonization of VRE in a Mouse Model.

Vancomycin-resistant Enterococcus (VRE) infection is a serious challenge for clinical management and there is no effective treatment at present. Fecal microbiota transplantation (FMT) and probiotic intervention have been shown to be promising approaches for reducing the colonization of certain pathogenic bacteria in the gastrointestinal tract, however, no such studies have been done on VRE. In this study, we evaluated the effect of FMT and two Lactobacillus strains (Y74 and HT121) on the colonization of VRE in a VRE-infection mouse model. We found that both Lactobacilli strains reduced VRE colonization rapidly. Fecal microbiota and colon mRNA expression analyses further showed that mice in FMT and the two Lactobacilli treatment groups restored their intestinal microbiota diversity faster than those in the phosphate buffer saline (PBS) treated group. Administration of Lactobacilli restored Firmicutes more quickly to the normal level, compared to FMT or PBS treatment, but restored Bacteroides to their normal level less quickly than FMT did. Furthermore, these treatments also had an impact on the relative abundance of intestinal microbiota composition from phylum to species level. RNA-seq showed that FMT treatment induced the expression of more genes in the colon, compared to the Lactobacilli treatment. Defense-related genes such as defensin α, Apoa1, and RegIII were down-regulated in both FMT and the two Lactobacilli treatment groups. Taken together, our findings indicate that both FMT and Lactobacilli treatments were effective in decreasing the colonization of VRE in the gut.

Consortium of Probiotics Attenuates Colonization of Clostridioides difficile.

Clostridioides difficile infection (CDI) is increasing morbidity and mortality rates globally. Fecal microbiota transplantation (FMT), an effective therapy for eliminating Clostridioides difficile (C. difficile), cannot be used extensive due to a range of challenges. Probiotics thus constitutes a promising alternative therapy. In our study, we evaluated the effect of consortium of probiotics including five Lactobacilli strains and two Bifidobacterium strains on the colonization of toxigenic BI/NAP1/027 C. difficile in a mouse model. The results of 16S rRNA sequencing and targeted metabolomics showed the consortium of probiotics effectively decreased the colonization of C. difficile, changed the α- and ß-diversity of the gut microbiota, decreased the primary bile acids, and increased the secondary bile acids. Spearman's correlation showed that some of the OTUs such as Akkermansia, Bacteroides, Blautia et al. were positively correlated with C. difficile numbers and the primary bile acids, and negatively correlated with the secondary bile acids. However, some of the OTUs, such as Butyricicoccus, Ruminococcus, and Rikenellaceae, were negatively correlated with C. difficile copies and the primary bile acids, and positively correlated with the secondary bile acids. In summary, the consortium of probiotics effectively decreases the colonization of C. difficile, probably via alteration of gut microbiota and bile acids. Our probiotics mixture thus offers a promising FMT alternative.

A critical role for hemolysin in Vibrio fluvialis-induced IL-1ß secretion mediated by the NLRP3 inflammasome in macrophages.

Vibrio fluvialis causes human diarrhea, but the pathogenesis is not well-studied. We hypothesized that V. fluvialis-secreted hemolysin (VFH) may induce IL-1ß secretion through the activation of the NLRP3 inflammasome and contribute to the pathogenicity of V. fluvialis. To examine this possibility, we constructed VFH mutant and complement strains and demonstrated that V. fluvialis-induced IL-1ß production and cytotoxicity in human monocytic THP-1 cells and mouse macrophages is attributed to VFH. To evaluate the role of VFH in vivo, we infected adult C57BL/6 mice intraperitoneally and suckling C57/B6 mice orally with various strains. The mice treated with 10(8) CFU wild-type V. fluvialis or cell-free supernatant containing VFH induced significantly higher IL-1ß production in peritoneal lavage fluid or in colon compared with those infected with the mutant strain, while no effect on TNF and IL-6 production was observed at day 5 or 24 h post-infection. VFH contributed to pathological changes and IL-1ß release independent of colonization of V. fluvialis in the colon. VFH has no effect on the synthesis of pro-IL-1ß, but rather it triggers the processing of pro-IL-1ß into IL-1ß. Furthermore, using deficient mouse strains, we verified that V. fluvialis-induced IL-1ß is mediated through activation of Caspase-1 and the NLRP3 inflammasome ex vivo. Confocal microscopy suggests that VFH contributes to cathepsin B release. Furthermore, V. fluvialis-induced IL-1ß secretion requires potassium (K(+)) efflux and reactive oxygen species production. Our results provide new evidence for the role of VFH in the activation of the NLRP3 inflammasome and pathogenesis in response to V. fluvialis infection. Summary Sentence: Vibrio fluvialis-secreted hemolysin induces IL-1ß secretion through the activation of the NLRP3 inflammasome and contributes to the pathogenicity of V. fluvialis.