Heparin,a glycosaminoglycan,is a stable source of carbon that supports the growth of microorganisms in the human intestine.It is also a commonly used anticoagulant drug in clinical practice,with significant therapeuti...Heparin,a glycosaminoglycan,is a stable source of carbon that supports the growth of microorganisms in the human intestine.It is also a commonly used anticoagulant drug in clinical practice,with significant therapeutic effects.Low molecular weight heparin(LMWH)is a highly active low molecular weight fragment obtained via enzymatic reaction or the chemical degradation of heparin.LMWH has been applied globally in the prevention and treatment of venous thromboembolism in thrombosis patients.Simultaneously,as a potential prebiotic,because of its low molecular weight,LMWH can be well degraded by the gut microbiota to maintain intestinal balance.Enzymatic heparin degradation has recently emerged as a viable disposal method for LMWH preparation;however,only very few benchmark enzymes have been thoroughly described and subjected to protein engineering to improve their properties over the past few years.The commercialization of enzymes will require the development of robustly engineered enzymes that meet the demands of industrial processes.Herein,we report a rational protein engineering strategy that includes molecular dynamic simulations of flexible amino acid mutations and disulfide bond screening.Several Bacteroides thetaiotaomicron heparanase I(Bt-HepI)mutants were obtained and screened for high thermal stability.We obtained the Bt-HepI^(D204C/K208C/H189W/Q198R)variant,which features a stabilized protein surface structure,with a 1.3-fold increase in catalytic constant/michaelis-menten constant(k_(cat)/K_(m)),a 2.44-fold increase in thermal stability at 50℃,and a 1.8-fold decrease in the average molecular weight of LMWH produced at 40℃compared with that seen with Bt-HepI^(WT).Our study establishes a strategy to engineer thermostable HepI to underpin its industrial applications.展开更多
岩溶地下水的微生物污染日益严重,其来源的研究得到国际学术界的广泛关注.本研究以重庆南山老龙洞岩溶地下河系统为对象,采用滤膜法监测地下水中的总细菌、大肠杆菌、粪大肠菌及粪链球菌等微生物指标,以拟杆菌(Bacteriodes)为指示细菌,...岩溶地下水的微生物污染日益严重,其来源的研究得到国际学术界的广泛关注.本研究以重庆南山老龙洞岩溶地下河系统为对象,采用滤膜法监测地下水中的总细菌、大肠杆菌、粪大肠菌及粪链球菌等微生物指标,以拟杆菌(Bacteriodes)为指示细菌,采用PCR-DGGE示踪地下水中大肠杆菌/粪大肠杆菌的来源.结果表明,老龙洞地下河流域各类细菌含量严重超标,总细菌数为10~2.9×10~7CFU·m L^(-1),大肠菌群总数达4.3~4.0×10~5CFU·m L^(-1),其中粪大肠菌群(FC)和粪链球菌(FS)分别最高达到1.1×10~6CFU·(100 m L)^(-1)、1.1×10~5CFU·(100 m L)^(-1);FC/FS多数为2以上,暗示流域地下水受人类粪便影响为主.地下水样和粪便样品的拟杆菌群落的PCR-DGGE比对分析表明地下水与人粪之间相似性为7.1%~69.1%,其中地下河出口处达到69.1%.地下水与猪粪之间相似性为1.1%~53.4%,地下河出口处仅为1.5%.因此,人类粪便为地下河污染的主要来源,猪粪污染为动物粪便污染的一部分,还存在其他动物粪便污染来源.此外,PCR-DGGE产物切胶测序发现大部分Bacteroides为人类肠道或粪便来源的细菌.展开更多
Background:The interaction between nutrition and immunity plays a vital role in nutrient digestion,absorption,and metabolism during poultry production.Recent studies showed that the gut microbiota contributes to the d...Background:The interaction between nutrition and immunity plays a vital role in nutrient digestion,absorption,and metabolism during poultry production.Recent studies showed that the gut microbiota contributes to the development of intestinal mucosal immunity.However,the mechanisms by which gut microbes regulate this process remain unclear.Methods:We compared the intestinal mucosal immunity and gut microbiota of Arbor Acre broilers AA(lower mucosal immunity)and Chinese native Wuliang Mountain Black-bone chickens(WLMB)(higher mucosal immunity)using 16S rDNA sequencing,transcriptomic analysis,and immunoglobulin A(IgA)antibody repertoire sequencing.We then combined 16S rDNA sequencing with transcriptomics to identify the key microbes and found that they were positively correlated with IgA production.Next,we transplanted candidate microbes into 1-day-old broiler to explore their role in intestinal mucosal immunity.Finally,we verified the function of candidate microbial metabolites in regulating the immune function of macrophages and the intestinal-epithelial cells(IECs)using in vitro experiments.Results:WLMB performs stronger mucosal immunity than AA,including higher IgA levels,more diverse IgA antibody repertoire,and higher bacterial affinity.Bacteroides was identified as the key microbes related to the intestinal IgA response.Bacteroides transplantation could increase IgA concentration in the duodenal contents by enhancing the expression of IgA,polymeric immunoglobin receptor(PIgR),B cell-activating factor of the TNF family(BAFF),and activation-induced cytidine deaminase(AID)in the duodenum.Additionally,Bacteroides-derived isovaleric acid promoted M2 macrophage polarization of macrophage via mTOR/PPAR-γ/STAT3 signaling pathways and regulated the immunologic function of IECs to produce cytokines,including interleukin(IL)-10,IL-4,BAFF,and transforming growth factor-beta(TGF-β),thus promoting IgA production in B cells by facilitating AID expression.Conclusion:Our study revealed that Bacteroides modulate the intestinal IgA response and maintain gut health in broilers.Bacteroides may be a promising alternative as an immunomodulatory microbial agent for developing nextgeneration probiotics for broiler production.展开更多
Polysaccharide was a class of macromolecular substance with various bioactive functions.Gut symbiotic microorganisms could utilize the polysaccharides from various sources,thus have important impact on human health.Ba...Polysaccharide was a class of macromolecular substance with various bioactive functions.Gut symbiotic microorganisms could utilize the polysaccharides from various sources,thus have important impact on human health.Bacteroides represented one of the dominant colonizers in the human gut.The utilization of polysaccharide by Bacteroides was important for supporting the function and stability of gut microbiota.After the degradation of polysaccharides by Bacteroides,gut microbes could ferment the monosaccharides and oligosaccharides degraded from polysaccharides into some metabolites,such as short-chain fatty acids(SCFAs),amino acids,etc.Among the metabolites,the SCFAs could have beneficial effects on gut health.This review summarized the niches of Bacteroides among gut microbiota,and also described the gene clusters and membrane proteins involved in the utilization processes of polysaccharide by gut Bacteroides.SCFAs could act as energy substrates for intestinal epithelial cells,inhibit histone deacetylases and activate G protein-coupled receptors.In addition,the future perspectives in investigating new degradation pathways for polysaccharide,and using polysaccharides or their metabolites as therapeutic approaches for diseases mediated by the gut dysbiosis were also provided.展开更多
AIM To evaluate the impact of recombinant Bacteroides fragilis enterotoxin-2 (BFT-2, or Fragilysin) on colorectal tumorigenesis in mice induced by azoxymethane/dextran sulfate sodium (AOM/DSS). METHODS Recombinant pro...AIM To evaluate the impact of recombinant Bacteroides fragilis enterotoxin-2 (BFT-2, or Fragilysin) on colorectal tumorigenesis in mice induced by azoxymethane/dextran sulfate sodium (AOM/DSS). METHODS Recombinant proBFT-2 was expressed in Escherichia coli strain Rosetta (DE3) and BFT-2 was obtained and tested for its biological activity via colorectal adenocarcinoma cell strains SW-480. Seventy C57BL/6J mice were randomly divided into a blank (BC; n = 10), model (AD; n = 20), model + low-dose toxin (ADLT; n = 20, 10 mu g), and a model + high-dose toxin (ADHT; n = 20, 20 mu g) group. Mice weight, tumor formation and pathology were analyzed. Immunohistochemistry determined Ki-67 and Caspase-3 expression in normal and tumor tissues of colorectal mucosa. RESULTS Recombinant BFT-2 was successfully obtained, along with its biological activity. The most obvious weight loss occurred in the AD group compared with the ADLT group (21.82 +/- 0.68 vs 23.23 +/- 0.91, P < 0.05) and the ADHT group (21.82 +/- 0.68 vs 23.57 +/- 1.06, P < 0.05). More tumors were found in the AD group than in the ADLT and ADHT groups (19.75 +/- 3.30 vs 6.50 +/- 1.73, P < 0.05; 19.75 +/- 3.30 vs 6.00 +/- 2.16, P < 0.05). Pathology showed that 12 mice had adenocarcinoma and 6 cases had adenoma in the AD group. Five mice had adenocarcinoma and 15 had adenoma in the ADLT group. Four mice had adenocarcinoma and 16 had adenoma in the ADHT group. The incidence of colorectal adenocarcinoma in both the ADHT group and the ADHT group was reduced compared to that in the AD group (P < 0.05, P < 0.05). The positive rate of Ki-67 in the ADLT group and the ADHT group was 50% and 40%, respectively, both of which were lower than that found in the AD group (94.44%, P < 0.05, P < 0.05). Caspase-3 expression in the ADLT group and the ADHT group was 45% and 55%, both of which were higher than that found in the BC group (16.67%, P < 0.05, P < 0.05). CONCLUSION Oral administration with lower-dose biologically active recombinant BFT-2 inhibited colorectal tumorigenesis in mice.展开更多
BACKGROUND Enterotoxigenic Bacteroides fragilis(ETBF)causes colitis and diarrhea,and is considered a candidate pathogen in inflammatory bowel diseases as well as colorectal cancers.These diseases are dependent on ETBF...BACKGROUND Enterotoxigenic Bacteroides fragilis(ETBF)causes colitis and diarrhea,and is considered a candidate pathogen in inflammatory bowel diseases as well as colorectal cancers.These diseases are dependent on ETBF-secreted toxin(BFT).Dendritic cells(DCs)play an important role in directing the nature of adaptive immune responses to bacterial infection and heme oxygenase-1(HO-1)is involved in the regulation of DC function.AIM To investigate the role of BFT in HO-1 expression in DCs.METHODS Murine DCs were generated from specific pathogen-free C57BL/6 and Nrf2−/−knockout mice.DCs were exposed to BFT,after which HO-1 expression and the related signaling factor activation were measured by quantitative RT-PCR,EMSA,fluorescent microscopy,immunoblot,and ELISA.RESULTS HO-1 expression was upregulated in DCs stimulated with BFT.Although BFT activated transcription factors such as NF-κB,AP-1,and Nrf2,activation of NF-κB and AP-1 was not involved in the induction of HO-1 expression in BFT-exposed DCs.Instead,upregulation of HO-1 expression was dependent on Nrf2 activation in DCs.Moreover,HO-1 expression via Nrf2 in DCs was regulated by mitogenactivated protein kinases such as ERK and p38.Furthermore,BFT enhanced the production of reactive oxygen species(ROS)and inhibition of ROS production resulted in a significant decrease of phospho-ERK,phospho-p38,Nrf2,and HO-1 CONCLUSION These results suggest that signaling pathways involving ROS-mediated ERK and p38 mitogen-activated protein kinases-Nrf2 activation in DCs are required for HO-1 induction during exposure to ETBF-produced BFT.展开更多
The Bacteroides species are important micro-organisms, both in the normal physiology of the intestines and as frequent opportunistic anaerobic pathogens, with a deeply-rooted phylogenetic origin endowing them with som...The Bacteroides species are important micro-organisms, both in the normal physiology of the intestines and as frequent opportunistic anaerobic pathogens, with a deeply-rooted phylogenetic origin endowing them with some interesting biological features. Their prevalence in anaerobic clinical specimens is around 60%-80%, and they display the most numerous and highest rates of antibiotic resistance among all pathogenic anaerobes. In these antibiotic resistance mechanisms there is a noteworthy role for the insertion sequence(IS) elements, which are usually regarded as representatives of ‘selfish' genes; the IS elements of Bacteroides are usually capable of up-regulating the antibiotic resistance genes. These include the cep A(penicillin and cephalosporin), cfx A(cephamycin), cfi A(carbapenem), nim(metronidazole) and erm F(clindamycin) resistance genes. This is achieved by outwardoriented promoter sequences on the ISs. Although some representatives are well characterized, e.g., the resistance gene-IS element pairs in certain resistant strains, open questions remain in this field concerning a better understanding of the molecular biology of theantibiotic resistance mechanisms of Bacteroides, which will have clinical implications.展开更多
Rationale:Endophthalmitis is an uncommon but serious ocular infection often resulting in probable visual loss.Bacteroides fragilis is a rare cause of endophthalmitis.Patient concerns:A 46-year-old male patient complai...Rationale:Endophthalmitis is an uncommon but serious ocular infection often resulting in probable visual loss.Bacteroides fragilis is a rare cause of endophthalmitis.Patient concerns:A 46-year-old male patient complained of eye pain and low vision after pars plana vitrectomy.Diagnosis:Bacteroides fragilis endophthalmitis after pars plana vitrectomy was diagnosed.Interventions:Pars plana vitrectomy and silicone oil implantation were performed.Outcomes:Early treatment and choice of tamponade in endophthalmitis after pars plana vitrectomy may possibly prevent evisceration and progression of endophthalmitis.Lessons:Bacteroides fragilis can be seen in cases of endophthalmitis after pars plana vitrectomy.展开更多
Bacteroides species are nearly half of the fecal flora community and some are host symbionts crucial to host nutrition and systemic immunity. Among Bacteroides species B. fragilis strains are considered to be the oppo...Bacteroides species are nearly half of the fecal flora community and some are host symbionts crucial to host nutrition and systemic immunity. Among Bacteroides species B. fragilis strains are considered to be the opportunistic ones, being the most isolated anaerobic bacteria in clinical samples. Cell-free supernatants of 65 B. fragilis strains were assayed and they were capable of inducing vacuolating phenotype on Vero cells lineage. The supernatant of the Bacteroides fragilis ATCC 23745 strain was elicited to have the strongest vacuolating effect on Vero cells monolayers and peritoneal macrophages. Some drastic cell alterations were observed, such as a general disorganization of cytoplasm and chromatin condensation, evidencing cell death. By transmission electron microscopy it was confirmed that the vacuoles observed were, in fact, swollen mitochondria. An immunocytochemical assay, TUNEL, was used to confirm this hypothesis and showed that Vero cells and peritoneal macrophages were dying by apoptotic process after exposition of B. fragilis cell-free supernatant. Physical analysis of the apoptotic factor has revealed properties similar to short-chain fatty acids. After gas chromatography and mass spectrometry analysis, phenylacetic acid (PA) was characterized as the major compound present in the most purified active fraction. We believe that the PA is responsible for the pro-apoptotic effect elicited by the supernatant of B. fragilis cultures.展开更多
Investigations into the nitrogen-fixing symbiosis between legumes and rhizobia can yield innovative strategies for sustainable agriculture.Legume species of the Inverted Repeat-Lacking Clade(IRLC)and the Dalbergioids,...Investigations into the nitrogen-fixing symbiosis between legumes and rhizobia can yield innovative strategies for sustainable agriculture.Legume species of the Inverted Repeat-Lacking Clade(IRLC)and the Dalbergioids,can utilize nodule cysteine-rich(NCR)peptides,a diverse family of peptides characterized by four or six highly conserved cysteine residues,to communicate with their microbial symbionts.These peptides,many of which exhibit antimicrobial properties,induce profound differentiation of bacteroids(semi-autonomous forms of bacteria)within nodule cells.This terminal differentiation endows the bacteroids with the ability to fix nitrogen,at the expense of their reproductive capacity.Notably,a significant number of NCR peptides is expressed in the nodule fixation zone,where the bacteroids have already reached terminal differentiation.Recent discoveries,through forward genetics approaches,have revealed that the functions of NCR peptides extend beyond antimicrobial effects and the promotion of differentiation.They also play a critical role in sustaining the viability of terminally differentiated bacteroids within nodule cells.These findings underscore the multifaceted functions of NCR peptides and highlight the importance of these peptides in mediating communications between host cells and the terminally differentiated bacteroids.展开更多
In recent decades,the prevalence of hyperuricemia and gout has increased dramatically due to lifestyle changes.The drugs currently recommended for hyperuricemia are associated with adverse reactions that limit their c...In recent decades,the prevalence of hyperuricemia and gout has increased dramatically due to lifestyle changes.The drugs currently recommended for hyperuricemia are associated with adverse reactions that limit their clinical use.In this study,we report that berberine(BBR)is an effective drug candidate for the treatment of hyperuricemia,with its mechanism potentially involving the modulation of gut microbiota and its metabolite,succinic acid.BBR has demonstrated good therapeutic effects in both acute and chronic animal models of hyperuricemia.In a clinical trial,oral administration of BBR for 6 months reduced blood uric acid levels in 22 participants by modulating the gut microbiota,which led to an increase in the abundance of Bacteroides and a decrease in Clostridium sensu stricto_1.Furthermore,Bacteroides fragilis was transplanted into ICR mice,and the results showed that Bacteroides fragilis exerted a therapeutic effect on uric acid similar to that of BBR.Notably,succinic acid,a metabolite of Bacteroides,significantly reduced uric acid levels.Subsequent cell and animal experiments revealed that the intestinal metabolite,succinic acid,regulated the upstream uric acid synthesis pathway in the liver by inhibiting adenosine monophosphate deaminase 2(AMPD2),an enzyme responsible for converting adenosine monophosphate(AMP)to inosine monophosphate(IMP).This inhibition resulted in a decrease in IMP levels and an increase in phosphate levels.The reduction in IMP led to a decreased downstream production of hypoxanthine,xanthine,and uric acid.BBR also demonstrated excellent renoprotective effects,improving nephropathy associated with hyperuricemia.In summary,BBR has the potential to be an effective treatment for hyperuricemia through the gut-liver axis.展开更多
Background and Objectives:To evaluate the potential benefits of Bacteroides fragilis 839(BF839),a nextgeneration probiotics,in reducing myelosuppression and gastrointestinal toxicity associated with chemotherapy in br...Background and Objectives:To evaluate the potential benefits of Bacteroides fragilis 839(BF839),a nextgeneration probiotics,in reducing myelosuppression and gastrointestinal toxicity associated with chemotherapy in breast cancer patient.Methods and Study Design:40 women with early breast cancer were randomly assigned to the BF839(n=20)or placebo(n=20)during the administration of adjuvant chemotherapy(4 cycles of epirubicin 100mg/m^(2) and cyclophosphamide 600mg/m^(2)).Myelosuppression and gastrointestinal adverse effects were monitored in both groups.Results:Throughout the four treatment cycles,the percentage of patients experiencing myelosuppression was 42.5%in the BF839 group,significantly lower than the 66.3%observed in the control group(p=0.003).Two patients in the BF839 group and three patients in the placebo group received recombinant human granulocyte colony-stimulating factor(rhG-CSF)due to leukopenia/neutropenia.When considering an ITT analysis,which included all patients regardless of rhG-CSF treatment,the BF839 group exhibited less reduction from baseline in white blood cells(-0.31±1.19 vs-1.15±0.77,p=0.012)and neutrophils(0.06±1.00 vs-0.84±0.85,p=0.004)compared to the placebo group.The difference became even more significant when excluding the patients who received rhG-CSF injections.Throughout the four treatment cycles,compared to the placebo group,the BF839 group had significantly lower rates of 3-4 grade nausea(35.0%vs 71.3%,p=0.001),vomiting(20.0%vs 45.0%,p=0.001),and diarrhea(15.0%vs 30.0%,p=0.023).Conclusions:These findings suggest that BF839 has the potential to effectively mitigate myelosuppression and gastrointestinal toxicity associated with chemotherapy in breast cancer patients.展开更多
The gut microbiome is a complex community of microorganisms that plays a direct role in the health of both the gastrointestinal tract and the entire body.Numerous factors influence the abundance and diversity of gut m...The gut microbiome is a complex community of microorganisms that plays a direct role in the health of both the gastrointestinal tract and the entire body.Numerous factors influence the abundance and diversity of gut microbiota.Microbial imbalance can contribute to disease development.Probiotics are biologically active supplements with promising properties that have high therapeutic potential.Currently,there is a tendency to switch from classic probiotic microorganisms represented by lactic acid bacteria to next-generation probiotics due to their unique ability to influence the human immune system.New-generation probiotics include bacteria such as Akkermansia muciniphila,Faecalibacterium prausnitzii,Bacteroides sp.,Prevotella sp.,Roseburia sp.,and Eubacterium sp.Nextgeneration probiotics can affect host immune cells by secreting various substances,such as butyrate in F.prausnitzii,or through interaction with Toll-like receptors of intestinal epithelial cells,such as A.muciniphila.Studying the role of next-generation probiotics in immune regulation is a promising area of research.This study describes the interactions of next-generation probiotics with the immune system.Understanding the mechanisms of such interactions will improve the treatment of various diseases.展开更多
Thalidomide(THA)is renowned for its potent anti-inflammatory properties.This study aimed to elucidate its underlying mechanisms in the context of Crohn's disease(CD)development.Mouse colitis models were establishe...Thalidomide(THA)is renowned for its potent anti-inflammatory properties.This study aimed to elucidate its underlying mechanisms in the context of Crohn's disease(CD)development.Mouse colitis models were established by dextran sulfate sodium(DSS)treatment.Fecal microbiota and metabolites were analyzed by metagenomic sequencing and mass spectrometry,respectively.Antibiotic-treated mice served as models for microbiota depletion and transplantation.The expression of forkhead box P3+(FOXP3+)regulatory T cells(Tregs)was measured by flow cytometry and immunohistochemical assay in colitis model and patient cohort.THA inhibited colitis in DSS-treated mice by altering the gut microbiota profile,with an increased abundance of probiotics Bacteroides fragilis,while pathogenic bacteria were depleted.In addition,THA increased beneficial metabolites bile acids and significantly restored gut barrier function.Transcriptomic profiling revealed that THA inhibited interleukin-17(IL-17),IL-1βand cell cycle signaling.Fecal microbiota transplantation from THA-treated mice to microbiota-depleted mice partly recapitulated the effects of THA.Specifically,increased level of gut commensal B.fragilis was observed,correlated with elevated levels of the microbial metabolite 3alpha-hydroxy-7-oxo-5beta-cholanic acid(7-ketolithocholic acid,7-KA)following THA treatment.This microbial metabolite may stable FOXP3 expression by targeting the receptor FMR1 autosomal homolog 1(FXR1)to inhibit autophagy.An interaction between FOXP3 and FXR1 was identified,with binding regions localized to the FOXP3 domain(aa238-335)and the FXR1 domain(aa82-222),respectively.Conclusively,THA modulates the gut microbiota and metabolite profiles towards a more beneficial composition,enhances gut barrier function,promotes the differentiation of FOXP3+Tregs and curbs pro-inflammatory pathways.展开更多
基金supported by the Natural Science Foundation of Jiangsu Province(BE2021623,BK20220155)Natural Science Foundation of Jiangsu Province(BE2021623)+4 种基金National Natural Science Foundation of China(32001665,U1903205,32021005)the National Key Research and Development Program of China(2017YF0400303)the Key Scientific and Technological Research Projects in the Key Areas of the Xinjiang Production and Construction Corps(2018AB010)the Key Research and Development 303 Program of Ningxia(2020BFG02012)Collaborative Innovation Center of Food Safety and Quality Control in Jiangsu Province。
文摘Heparin,a glycosaminoglycan,is a stable source of carbon that supports the growth of microorganisms in the human intestine.It is also a commonly used anticoagulant drug in clinical practice,with significant therapeutic effects.Low molecular weight heparin(LMWH)is a highly active low molecular weight fragment obtained via enzymatic reaction or the chemical degradation of heparin.LMWH has been applied globally in the prevention and treatment of venous thromboembolism in thrombosis patients.Simultaneously,as a potential prebiotic,because of its low molecular weight,LMWH can be well degraded by the gut microbiota to maintain intestinal balance.Enzymatic heparin degradation has recently emerged as a viable disposal method for LMWH preparation;however,only very few benchmark enzymes have been thoroughly described and subjected to protein engineering to improve their properties over the past few years.The commercialization of enzymes will require the development of robustly engineered enzymes that meet the demands of industrial processes.Herein,we report a rational protein engineering strategy that includes molecular dynamic simulations of flexible amino acid mutations and disulfide bond screening.Several Bacteroides thetaiotaomicron heparanase I(Bt-HepI)mutants were obtained and screened for high thermal stability.We obtained the Bt-HepI^(D204C/K208C/H189W/Q198R)variant,which features a stabilized protein surface structure,with a 1.3-fold increase in catalytic constant/michaelis-menten constant(k_(cat)/K_(m)),a 2.44-fold increase in thermal stability at 50℃,and a 1.8-fold decrease in the average molecular weight of LMWH produced at 40℃compared with that seen with Bt-HepI^(WT).Our study establishes a strategy to engineer thermostable HepI to underpin its industrial applications.
文摘岩溶地下水的微生物污染日益严重,其来源的研究得到国际学术界的广泛关注.本研究以重庆南山老龙洞岩溶地下河系统为对象,采用滤膜法监测地下水中的总细菌、大肠杆菌、粪大肠菌及粪链球菌等微生物指标,以拟杆菌(Bacteriodes)为指示细菌,采用PCR-DGGE示踪地下水中大肠杆菌/粪大肠杆菌的来源.结果表明,老龙洞地下河流域各类细菌含量严重超标,总细菌数为10~2.9×10~7CFU·m L^(-1),大肠菌群总数达4.3~4.0×10~5CFU·m L^(-1),其中粪大肠菌群(FC)和粪链球菌(FS)分别最高达到1.1×10~6CFU·(100 m L)^(-1)、1.1×10~5CFU·(100 m L)^(-1);FC/FS多数为2以上,暗示流域地下水受人类粪便影响为主.地下水样和粪便样品的拟杆菌群落的PCR-DGGE比对分析表明地下水与人粪之间相似性为7.1%~69.1%,其中地下河出口处达到69.1%.地下水与猪粪之间相似性为1.1%~53.4%,地下河出口处仅为1.5%.因此,人类粪便为地下河污染的主要来源,猪粪污染为动物粪便污染的一部分,还存在其他动物粪便污染来源.此外,PCR-DGGE产物切胶测序发现大部分Bacteroides为人类肠道或粪便来源的细菌.
基金supported by the National Natural Science Foundation of China (31925037)to XHY。
文摘Background:The interaction between nutrition and immunity plays a vital role in nutrient digestion,absorption,and metabolism during poultry production.Recent studies showed that the gut microbiota contributes to the development of intestinal mucosal immunity.However,the mechanisms by which gut microbes regulate this process remain unclear.Methods:We compared the intestinal mucosal immunity and gut microbiota of Arbor Acre broilers AA(lower mucosal immunity)and Chinese native Wuliang Mountain Black-bone chickens(WLMB)(higher mucosal immunity)using 16S rDNA sequencing,transcriptomic analysis,and immunoglobulin A(IgA)antibody repertoire sequencing.We then combined 16S rDNA sequencing with transcriptomics to identify the key microbes and found that they were positively correlated with IgA production.Next,we transplanted candidate microbes into 1-day-old broiler to explore their role in intestinal mucosal immunity.Finally,we verified the function of candidate microbial metabolites in regulating the immune function of macrophages and the intestinal-epithelial cells(IECs)using in vitro experiments.Results:WLMB performs stronger mucosal immunity than AA,including higher IgA levels,more diverse IgA antibody repertoire,and higher bacterial affinity.Bacteroides was identified as the key microbes related to the intestinal IgA response.Bacteroides transplantation could increase IgA concentration in the duodenal contents by enhancing the expression of IgA,polymeric immunoglobin receptor(PIgR),B cell-activating factor of the TNF family(BAFF),and activation-induced cytidine deaminase(AID)in the duodenum.Additionally,Bacteroides-derived isovaleric acid promoted M2 macrophage polarization of macrophage via mTOR/PPAR-γ/STAT3 signaling pathways and regulated the immunologic function of IECs to produce cytokines,including interleukin(IL)-10,IL-4,BAFF,and transforming growth factor-beta(TGF-β),thus promoting IgA production in B cells by facilitating AID expression.Conclusion:Our study revealed that Bacteroides modulate the intestinal IgA response and maintain gut health in broilers.Bacteroides may be a promising alternative as an immunomodulatory microbial agent for developing nextgeneration probiotics for broiler production.
基金the National Science Fund for Distinguished Young Scholars of China(31825020)。
文摘Polysaccharide was a class of macromolecular substance with various bioactive functions.Gut symbiotic microorganisms could utilize the polysaccharides from various sources,thus have important impact on human health.Bacteroides represented one of the dominant colonizers in the human gut.The utilization of polysaccharide by Bacteroides was important for supporting the function and stability of gut microbiota.After the degradation of polysaccharides by Bacteroides,gut microbes could ferment the monosaccharides and oligosaccharides degraded from polysaccharides into some metabolites,such as short-chain fatty acids(SCFAs),amino acids,etc.Among the metabolites,the SCFAs could have beneficial effects on gut health.This review summarized the niches of Bacteroides among gut microbiota,and also described the gene clusters and membrane proteins involved in the utilization processes of polysaccharide by gut Bacteroides.SCFAs could act as energy substrates for intestinal epithelial cells,inhibit histone deacetylases and activate G protein-coupled receptors.In addition,the future perspectives in investigating new degradation pathways for polysaccharide,and using polysaccharides or their metabolites as therapeutic approaches for diseases mediated by the gut dysbiosis were also provided.
基金Supported by the Scientific Research Project of Shanghai Health and Family Planning,and the Commission and the 5th People’s Hospital of Shanghai,Fudan University under Grant No.201440505
文摘AIM To evaluate the impact of recombinant Bacteroides fragilis enterotoxin-2 (BFT-2, or Fragilysin) on colorectal tumorigenesis in mice induced by azoxymethane/dextran sulfate sodium (AOM/DSS). METHODS Recombinant proBFT-2 was expressed in Escherichia coli strain Rosetta (DE3) and BFT-2 was obtained and tested for its biological activity via colorectal adenocarcinoma cell strains SW-480. Seventy C57BL/6J mice were randomly divided into a blank (BC; n = 10), model (AD; n = 20), model + low-dose toxin (ADLT; n = 20, 10 mu g), and a model + high-dose toxin (ADHT; n = 20, 20 mu g) group. Mice weight, tumor formation and pathology were analyzed. Immunohistochemistry determined Ki-67 and Caspase-3 expression in normal and tumor tissues of colorectal mucosa. RESULTS Recombinant BFT-2 was successfully obtained, along with its biological activity. The most obvious weight loss occurred in the AD group compared with the ADLT group (21.82 +/- 0.68 vs 23.23 +/- 0.91, P < 0.05) and the ADHT group (21.82 +/- 0.68 vs 23.57 +/- 1.06, P < 0.05). More tumors were found in the AD group than in the ADLT and ADHT groups (19.75 +/- 3.30 vs 6.50 +/- 1.73, P < 0.05; 19.75 +/- 3.30 vs 6.00 +/- 2.16, P < 0.05). Pathology showed that 12 mice had adenocarcinoma and 6 cases had adenoma in the AD group. Five mice had adenocarcinoma and 15 had adenoma in the ADLT group. Four mice had adenocarcinoma and 16 had adenoma in the ADHT group. The incidence of colorectal adenocarcinoma in both the ADHT group and the ADHT group was reduced compared to that in the AD group (P < 0.05, P < 0.05). The positive rate of Ki-67 in the ADLT group and the ADHT group was 50% and 40%, respectively, both of which were lower than that found in the AD group (94.44%, P < 0.05, P < 0.05). Caspase-3 expression in the ADLT group and the ADHT group was 45% and 55%, both of which were higher than that found in the BC group (16.67%, P < 0.05, P < 0.05). CONCLUSION Oral administration with lower-dose biologically active recombinant BFT-2 inhibited colorectal tumorigenesis in mice.
基金Supported by the Basic Science Research Program through the National Research Foundation of Korea funded by the Ministry of Education,Science and Technology,South Korea,No.NRF-2018R1D1A1B07043350
文摘BACKGROUND Enterotoxigenic Bacteroides fragilis(ETBF)causes colitis and diarrhea,and is considered a candidate pathogen in inflammatory bowel diseases as well as colorectal cancers.These diseases are dependent on ETBF-secreted toxin(BFT).Dendritic cells(DCs)play an important role in directing the nature of adaptive immune responses to bacterial infection and heme oxygenase-1(HO-1)is involved in the regulation of DC function.AIM To investigate the role of BFT in HO-1 expression in DCs.METHODS Murine DCs were generated from specific pathogen-free C57BL/6 and Nrf2−/−knockout mice.DCs were exposed to BFT,after which HO-1 expression and the related signaling factor activation were measured by quantitative RT-PCR,EMSA,fluorescent microscopy,immunoblot,and ELISA.RESULTS HO-1 expression was upregulated in DCs stimulated with BFT.Although BFT activated transcription factors such as NF-κB,AP-1,and Nrf2,activation of NF-κB and AP-1 was not involved in the induction of HO-1 expression in BFT-exposed DCs.Instead,upregulation of HO-1 expression was dependent on Nrf2 activation in DCs.Moreover,HO-1 expression via Nrf2 in DCs was regulated by mitogenactivated protein kinases such as ERK and p38.Furthermore,BFT enhanced the production of reactive oxygen species(ROS)and inhibition of ROS production resulted in a significant decrease of phospho-ERK,phospho-p38,Nrf2,and HO-1 CONCLUSION These results suggest that signaling pathways involving ROS-mediated ERK and p38 mitogen-activated protein kinases-Nrf2 activation in DCs are required for HO-1 induction during exposure to ETBF-produced BFT.
基金Supported by The Center of Excellence at the University of Szeged(TáMOP-421B)to József Sóki.
文摘The Bacteroides species are important micro-organisms, both in the normal physiology of the intestines and as frequent opportunistic anaerobic pathogens, with a deeply-rooted phylogenetic origin endowing them with some interesting biological features. Their prevalence in anaerobic clinical specimens is around 60%-80%, and they display the most numerous and highest rates of antibiotic resistance among all pathogenic anaerobes. In these antibiotic resistance mechanisms there is a noteworthy role for the insertion sequence(IS) elements, which are usually regarded as representatives of ‘selfish' genes; the IS elements of Bacteroides are usually capable of up-regulating the antibiotic resistance genes. These include the cep A(penicillin and cephalosporin), cfx A(cephamycin), cfi A(carbapenem), nim(metronidazole) and erm F(clindamycin) resistance genes. This is achieved by outwardoriented promoter sequences on the ISs. Although some representatives are well characterized, e.g., the resistance gene-IS element pairs in certain resistant strains, open questions remain in this field concerning a better understanding of the molecular biology of theantibiotic resistance mechanisms of Bacteroides, which will have clinical implications.
文摘Rationale:Endophthalmitis is an uncommon but serious ocular infection often resulting in probable visual loss.Bacteroides fragilis is a rare cause of endophthalmitis.Patient concerns:A 46-year-old male patient complained of eye pain and low vision after pars plana vitrectomy.Diagnosis:Bacteroides fragilis endophthalmitis after pars plana vitrectomy was diagnosed.Interventions:Pars plana vitrectomy and silicone oil implantation were performed.Outcomes:Early treatment and choice of tamponade in endophthalmitis after pars plana vitrectomy may possibly prevent evisceration and progression of endophthalmitis.Lessons:Bacteroides fragilis can be seen in cases of endophthalmitis after pars plana vitrectomy.
基金supported by grants from the following institutions:CAPES,CNPq,Faperj,Pronex and MCT-CNPq.
文摘Bacteroides species are nearly half of the fecal flora community and some are host symbionts crucial to host nutrition and systemic immunity. Among Bacteroides species B. fragilis strains are considered to be the opportunistic ones, being the most isolated anaerobic bacteria in clinical samples. Cell-free supernatants of 65 B. fragilis strains were assayed and they were capable of inducing vacuolating phenotype on Vero cells lineage. The supernatant of the Bacteroides fragilis ATCC 23745 strain was elicited to have the strongest vacuolating effect on Vero cells monolayers and peritoneal macrophages. Some drastic cell alterations were observed, such as a general disorganization of cytoplasm and chromatin condensation, evidencing cell death. By transmission electron microscopy it was confirmed that the vacuoles observed were, in fact, swollen mitochondria. An immunocytochemical assay, TUNEL, was used to confirm this hypothesis and showed that Vero cells and peritoneal macrophages were dying by apoptotic process after exposition of B. fragilis cell-free supernatant. Physical analysis of the apoptotic factor has revealed properties similar to short-chain fatty acids. After gas chromatography and mass spectrometry analysis, phenylacetic acid (PA) was characterized as the major compound present in the most purified active fraction. We believe that the PA is responsible for the pro-apoptotic effect elicited by the supernatant of B. fragilis cultures.
基金funded by the National Natural Science Foundation of China (Grant Nos.32441035, 32470255, 32070271, and 32161133006 to H.P.,32200201 to F.G.)Distinguished Young Scholar Grant of Hunan Province, 2024JJ2014, to H.P.Young Scholar Grant of Natural Science Foundation of Hunan Province,2024JJ6132, to Y.J.
文摘Investigations into the nitrogen-fixing symbiosis between legumes and rhizobia can yield innovative strategies for sustainable agriculture.Legume species of the Inverted Repeat-Lacking Clade(IRLC)and the Dalbergioids,can utilize nodule cysteine-rich(NCR)peptides,a diverse family of peptides characterized by four or six highly conserved cysteine residues,to communicate with their microbial symbionts.These peptides,many of which exhibit antimicrobial properties,induce profound differentiation of bacteroids(semi-autonomous forms of bacteria)within nodule cells.This terminal differentiation endows the bacteroids with the ability to fix nitrogen,at the expense of their reproductive capacity.Notably,a significant number of NCR peptides is expressed in the nodule fixation zone,where the bacteroids have already reached terminal differentiation.Recent discoveries,through forward genetics approaches,have revealed that the functions of NCR peptides extend beyond antimicrobial effects and the promotion of differentiation.They also play a critical role in sustaining the viability of terminally differentiated bacteroids within nodule cells.These findings underscore the multifaceted functions of NCR peptides and highlight the importance of these peptides in mediating communications between host cells and the terminally differentiated bacteroids.
基金Jiandong Jiang,Yan Wang,and Linbin Pan have a patent related to this work(CN201810788495.7).
文摘In recent decades,the prevalence of hyperuricemia and gout has increased dramatically due to lifestyle changes.The drugs currently recommended for hyperuricemia are associated with adverse reactions that limit their clinical use.In this study,we report that berberine(BBR)is an effective drug candidate for the treatment of hyperuricemia,with its mechanism potentially involving the modulation of gut microbiota and its metabolite,succinic acid.BBR has demonstrated good therapeutic effects in both acute and chronic animal models of hyperuricemia.In a clinical trial,oral administration of BBR for 6 months reduced blood uric acid levels in 22 participants by modulating the gut microbiota,which led to an increase in the abundance of Bacteroides and a decrease in Clostridium sensu stricto_1.Furthermore,Bacteroides fragilis was transplanted into ICR mice,and the results showed that Bacteroides fragilis exerted a therapeutic effect on uric acid similar to that of BBR.Notably,succinic acid,a metabolite of Bacteroides,significantly reduced uric acid levels.Subsequent cell and animal experiments revealed that the intestinal metabolite,succinic acid,regulated the upstream uric acid synthesis pathway in the liver by inhibiting adenosine monophosphate deaminase 2(AMPD2),an enzyme responsible for converting adenosine monophosphate(AMP)to inosine monophosphate(IMP).This inhibition resulted in a decrease in IMP levels and an increase in phosphate levels.The reduction in IMP led to a decreased downstream production of hypoxanthine,xanthine,and uric acid.BBR also demonstrated excellent renoprotective effects,improving nephropathy associated with hyperuricemia.In summary,BBR has the potential to be an effective treatment for hyperuricemia through the gut-liver axis.
文摘Background and Objectives:To evaluate the potential benefits of Bacteroides fragilis 839(BF839),a nextgeneration probiotics,in reducing myelosuppression and gastrointestinal toxicity associated with chemotherapy in breast cancer patient.Methods and Study Design:40 women with early breast cancer were randomly assigned to the BF839(n=20)or placebo(n=20)during the administration of adjuvant chemotherapy(4 cycles of epirubicin 100mg/m^(2) and cyclophosphamide 600mg/m^(2)).Myelosuppression and gastrointestinal adverse effects were monitored in both groups.Results:Throughout the four treatment cycles,the percentage of patients experiencing myelosuppression was 42.5%in the BF839 group,significantly lower than the 66.3%observed in the control group(p=0.003).Two patients in the BF839 group and three patients in the placebo group received recombinant human granulocyte colony-stimulating factor(rhG-CSF)due to leukopenia/neutropenia.When considering an ITT analysis,which included all patients regardless of rhG-CSF treatment,the BF839 group exhibited less reduction from baseline in white blood cells(-0.31±1.19 vs-1.15±0.77,p=0.012)and neutrophils(0.06±1.00 vs-0.84±0.85,p=0.004)compared to the placebo group.The difference became even more significant when excluding the patients who received rhG-CSF injections.Throughout the four treatment cycles,compared to the placebo group,the BF839 group had significantly lower rates of 3-4 grade nausea(35.0%vs 71.3%,p=0.001),vomiting(20.0%vs 45.0%,p=0.001),and diarrhea(15.0%vs 30.0%,p=0.023).Conclusions:These findings suggest that BF839 has the potential to effectively mitigate myelosuppression and gastrointestinal toxicity associated with chemotherapy in breast cancer patients.
基金carried out at the expense of a grant from the Russian Science Foundation No.24-24-20036,https://rscf.ru/project/24-24-20036(accessed on 5 June 2025).
文摘The gut microbiome is a complex community of microorganisms that plays a direct role in the health of both the gastrointestinal tract and the entire body.Numerous factors influence the abundance and diversity of gut microbiota.Microbial imbalance can contribute to disease development.Probiotics are biologically active supplements with promising properties that have high therapeutic potential.Currently,there is a tendency to switch from classic probiotic microorganisms represented by lactic acid bacteria to next-generation probiotics due to their unique ability to influence the human immune system.New-generation probiotics include bacteria such as Akkermansia muciniphila,Faecalibacterium prausnitzii,Bacteroides sp.,Prevotella sp.,Roseburia sp.,and Eubacterium sp.Nextgeneration probiotics can affect host immune cells by secreting various substances,such as butyrate in F.prausnitzii,or through interaction with Toll-like receptors of intestinal epithelial cells,such as A.muciniphila.Studying the role of next-generation probiotics in immune regulation is a promising area of research.This study describes the interactions of next-generation probiotics with the immune system.Understanding the mechanisms of such interactions will improve the treatment of various diseases.
基金supported by grants from the National Natural Science Foundation of China(Grant Nos.:82360112)the project supported by Jiangxi Provincial Natural Science Foundation,China(Grant No.:20232BAB216021)+2 种基金China Postdoctoral Science Foundation(Grant No.:2023M741522)the Key Laboratory Project of Digestive Diseases in Jiangxi Province,China(Program No.:2024SSY06101)Jiangxi Clinical Research Center for Gastroenterology,China(Program No.:20223BCG74011).
文摘Thalidomide(THA)is renowned for its potent anti-inflammatory properties.This study aimed to elucidate its underlying mechanisms in the context of Crohn's disease(CD)development.Mouse colitis models were established by dextran sulfate sodium(DSS)treatment.Fecal microbiota and metabolites were analyzed by metagenomic sequencing and mass spectrometry,respectively.Antibiotic-treated mice served as models for microbiota depletion and transplantation.The expression of forkhead box P3+(FOXP3+)regulatory T cells(Tregs)was measured by flow cytometry and immunohistochemical assay in colitis model and patient cohort.THA inhibited colitis in DSS-treated mice by altering the gut microbiota profile,with an increased abundance of probiotics Bacteroides fragilis,while pathogenic bacteria were depleted.In addition,THA increased beneficial metabolites bile acids and significantly restored gut barrier function.Transcriptomic profiling revealed that THA inhibited interleukin-17(IL-17),IL-1βand cell cycle signaling.Fecal microbiota transplantation from THA-treated mice to microbiota-depleted mice partly recapitulated the effects of THA.Specifically,increased level of gut commensal B.fragilis was observed,correlated with elevated levels of the microbial metabolite 3alpha-hydroxy-7-oxo-5beta-cholanic acid(7-ketolithocholic acid,7-KA)following THA treatment.This microbial metabolite may stable FOXP3 expression by targeting the receptor FMR1 autosomal homolog 1(FXR1)to inhibit autophagy.An interaction between FOXP3 and FXR1 was identified,with binding regions localized to the FOXP3 domain(aa238-335)and the FXR1 domain(aa82-222),respectively.Conclusively,THA modulates the gut microbiota and metabolite profiles towards a more beneficial composition,enhances gut barrier function,promotes the differentiation of FOXP3+Tregs and curbs pro-inflammatory pathways.
