Bacteroides-derived isovaleric acid enhances mucosal immunity by facilitating intestinal IgA response in broilers

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.

Suppression of colorectal tumorigenesis by recombinant Bacteroides fragilis enterotoxin-2 in vivo

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.

Bacteroides utilization for dietary polysaccharides and their beneficial effects on gut health

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.

Bacteroides fragilis enterotoxin upregulates heme oxygenase-1 in dendritic cells via reactive oxygen species-,mitogen-activated protein kinase-,and Nrf2-dependent pathway

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.

Bacteroides forsythus ATCC43037菌体蛋白与人类唾液酸性富脯蛋白的相互作用

目的 :探讨福赛类杆菌与人类唾液富脯蛋白相互作用的蛋白分子。方法 :Western -blot方法。将人工合成唾液富脯蛋白用生物素标记 ,福赛类杆菌全菌蛋白凝胶电泳 ,半干转移至纤维膜上 ,观察二者的相互作用。结果 :富脯蛋白能与分子量为 85KD、6 5KD、6 0KD、以及 49KD的福赛类杆菌蛋白发生结合。结论 :福赛类杆菌存在与人类唾液富脯蛋白相互结合的粘附素。

Extended role for insertion sequence elements in the antibiotic resistance of Bacteroides

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.

Endophthalmitis caused by Bacteroides fragilis after pars plana vitrectomy and treatment approach

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.

脆弱拟杆菌(Bacteroides fragilis)产肠毒素菌株和非产肠毒素菌株的抗原特性

从腹泻犊牛(62株)、羔羊(2株)和猪(5株)的粪便中获得脆弱拟杆菌产肠毒素株(44株)和非产肠毒素株(25株)。利用微量全细胞凝集试验和凝胶双扩散试验检测,菌株对13株脆弱拟杆菌产肠毒素菌株制备的非吸收兔抗血清有反应。脆弱拟杆菌有多种抗原。根据凝集反应,44株产肠毒素脆弱拟杆菌(ETBE)中有37株(84%)组成13个血清群、25株非产肠毒素脆弱拟杆菌(non—ETBF)中有14株(56%)组成13个血清群中的4个血清群。与凝胶扩散试验的结果比较,大部分菌株对13株抗血清有不同的凝集试验反应模式,从 non—ETBF 中不能区分ETBF。脆弱拟杆菌抗原的异源性促进了个别菌株的变异,这种能力对将来的流行病学和毒力研究是有益的。从腹泻犊牛、羔羊和猪的粪便中分离的ETBF,属于专性厌氧菌。利用肠结扎试验,证明脆弱拟杆菌在犊牛和羔羊中产生一种肠毒素,当给予新生羔羊口服时,证明 ETBF是腹泻病原。根据凝集和凝胶扩散分析,脆弱拟杆菌人株含有多种抗原,许多人株含有热稳定多糖荚膜抗原,可作为一种肠道外感染的毒力因子,有些脆弱拟杆菌人株也含有纤毛。本研究的目的,是根据抗原的不同,区分腹泻家畜的 ETBF 和 non—ETBF 的血清群,是否能从 non—ETBF 中区分 ETBF。

Bacteroides fragilis Supernatant Extracts Enriched in Phenylacetic Acid Induce a Cytotoxic Effect in Mammalian Cells

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.

感染性腹泻患者肠道菌群失衡特征分析

目的研究不同病原体感染造成的感染性腹泻患者肠道菌群失衡特征,以及拟杆菌属在维持肠道内环境稳态中的作用,为后续感染性腹泻的治疗提供新思路。方法采用三代全长16S rRNA扩增子方法,测定由病毒和细菌等病原感染引起的腹泻患者肠道菌群,同时与健康人群肠道进行对比分析。按照单一细菌感染、单一病毒感染、混合感染以及艰难梭菌感染等对腹泻患者进行分组和分析。结果拟杆菌在健康人群肠道环境中占据绝对的数量和丰度水平,而感染性腹泻患者的拟杆菌门/纲/目/科/属等各分类水平的相对丰度均有下降。α多样性分析结果显示不同组别之间无统计学差异;β多样性中,NMDS和PCoA分析显示健康对照组与感染性腹泻各组中形成了明显的不同聚类群。健康人群肠道菌群的多样性水平高于各感染性腹泻组。物种差异分析表明,由不同病原体感染造成的感染性腹泻患者具有各自不同的优势肠道菌群。单一病毒感染之后以双歧杆菌属作为其优势菌群;单一细菌感染之后以链球菌属为优势菌群;混合感染组中以拉氏梭菌属为优势菌群。艰难梭菌感染组中的埃希菌属和克雷伯菌属是该组中的优势菌群。同时,健康人群肠道中的优势菌群是拟杆菌属。COG功能预测结果显示,健康对照组与各感染组形成了明显不同的聚类群。感染性腹泻各组中的防御机制功能、细胞壁合成、蛋白修饰、细胞分化以及复制和重组等功能均明显降低。结论由不同病原感染造成的感染性腹泻患者出现不同程度的菌群失调特征,肠道菌群的多样性降低,并出现各自的优势菌群。同时,拟杆菌属在维持人体肠道内环境稳态中具有关键作用,为后续感染性腹泻的治疗和研究等领域提供了新的思路。

拟杆菌属临床分离株耐药性及脆弱拟杆菌肠毒素bft基因分型特征分析

目的 分析拟杆菌属临床分布及其耐药特征,并探讨脆弱拟杆菌肠毒素bft基因分型特征。方法收集2016年6月—2019年6月内蒙古医科大学附属医院分离自临床样本的拟杆菌属147株,对其进行菌种鉴定和体外药物敏感性试验。采用聚合酶链反应(PCR)检测脆弱拟杆菌肠毒素bft基因。结果 147株拟杆菌属细菌中,脆弱拟杆菌100株(68.0%)、多形拟杆菌25株(17.0%)、卵形拟杆菌9株(6.1%)。体外药物敏感性试验结果显示,拟杆菌属细菌对克林霉素的耐药率最高(78.9%);脆弱拟杆菌对克林霉素的耐药率为85.0%,高于其他拟杆菌(66.0%)。拟杆菌属细菌对亚胺培南和甲硝唑的耐药率分别为13.6%和4.7%,对其他抗菌药物呈不同程度耐药;脆弱拟杆菌对大部分抗菌药物的耐药率均高于其他类型拟杆菌。脆弱拟杆菌bft基因阳性率为38.0%,以bft-1亚型为主要基因型(28.0%),其次为bft-2亚型(10.0%),未检出bft-3亚型。分离自非腹部临床样本的脆弱拟杆菌bft基因阳性率(55.6%)高于分离自腹部临床样本的脆弱拟杆菌(36.3%)。结论 拟杆菌属临床分离株中脆弱拟杆菌分离率最高,其对临床常用抗菌药物均有一定的耐药性。分离自非腹部临床样本的脆弱拟杆菌产肠毒素的菌株流行率更高,应引起临床重视。

临床感染标本厌氧菌质谱鉴定及临床特征

目的探讨我院厌氧菌感染的种属分布、耐药性和临床特征,为临床治疗提供参考。方法收集2020年1月至2023年6月从临床感染标本中分离的非重复感染部位、非重复株厌氧菌菌株248株。采用MALDI-TOF MS技术鉴定厌氧菌种属,采用天地人微生物检测系统进行药敏试验和β-内酰胺酶实验,并进行临床分析。结果共分离248株厌氧菌,分属13个属,以拟杆菌属(44.4%)、普雷沃菌属(16.1%)和消化链球菌属(15.3%)为主。拟杆菌属中脆弱拟杆菌(74.5%)最多,主要来自分泌物、脓液和静脉血。脆弱拟杆菌对甲硝唑、氯霉素、头孢西丁、头孢三代药物、碳青霉烯类药物和β-内酰胺类复合药药物的敏感率均>85%。青霉素、氨苄西林耐药率为100%。对四环素和克林霉素耐药率>50%。β-内酰胺酶阳性率100%。结论厌氧菌是重要的感染病原体,其耐药性明显增加。实验室应加强对厌氧菌的鉴定和药敏试验指导临床合理用药,提高治疗效果。

Sugarcane leaves-derived polyphenols alleviate metabolic syndrome and modulate gut microbiota of ob/ob mice

Sugarcane leaves-derived polyphenols(SLP)have been demonstrated to have diverse health-promoting benefits,but the mechanism of action has not been fully elucidated.This study aimed to investigate the anti-metabolic disease effects of SLP and the underlying mechanisms in mice.In the current study,we prepared the SLP mainly consisting of three flavonoid glycosides,three phenol derivatives,and two lignans including one new compound,and further demonstrated that SLP reduced body weight gain and fat accumulation,improved glucose and lipid metabolism disorders,ameliorated hepatic steatosis,and regulated short-chain fatty acids(SCFAs)production and secondary bile acids metabolism in ob/ob mice.Notably,SLP largely altered the gut microbiota composition,especially enriching the commensal bacteria Akkermansia muciniphila and Bacteroides acidifaciens.Oral gavage with the above two strains ameliorated metabolic syndrome(MetS),regulated secondary bile acid metabolism,and increased the production of SCFAs in high-fat diet(HFD)-induced obese mice.These results demonstrated that SLP could be used as a prebiotic to attenuate MetS via regulating gut microbiota composition and further activating the secondary bile acids-mediated gut-adipose axis.

Metagenomic next-generation sequencing identified a brain abscess caused by mixed oral anaerobe infection:A case report

Fusobacterium vincentii brain abscesses are relatively rare.Here,we report our treatment of an anaerobic brain abscess caused by a mixed infection of Parvimonas micra,Streptococcus constellatus,Fusobacterium vincentii,and Bacteroides heparinolyticus diagnosed by metagenomic next-generation sequencing(mNGS).This is the first re-ported case of Fusobacterium vincentii in a brain abscess.This case highlights the possibility that oral anaerobic microbes can cause a brain abscess and demonstrates that mNGS has the potential to be deployed to provide rapid infection diagnosis and rationalize antimicrobial therapy for brain abscesses.

内蒙古医科大学附属医院儿童肠道可培养拟杆菌耐药性研究

目的探究呼和浩特地区儿童肠道可培养拟杆菌对抗菌药物的耐药性。方法收集2021年03月—2022年09月期间我院儿科住院儿童的粪便标本及临床资料,采用VITEK-2 Compact全自动微生物鉴定系统及厌氧菌及棒状杆菌(ANC)鉴定卡、MALDI-TOFMS质谱仪鉴定、分离拟杆菌,采用琼脂稀释法测定拟杆菌对多种抗菌药物的敏感性。结果本研究共收集219株拟杆菌分离株,对多种抗菌药物有较高的耐药性,其对青霉素、阿莫西林、克林霉素、替卡西林和哌拉西林高度耐药,耐药率分别为:100%、97.7%、97.3%、70.3%和68.0%;对头孢替坦、头孢西丁、阿莫西林/克拉维酸和亚胺培南中度耐药,耐药率分别为:50.2%、36.1%、17.8%和12.3%;对甲硝唑、替卡西林/克拉维酸、哌拉西林/他唑巴坦、氯霉素轻度耐药,耐药率分别为:9.1%、5.5%、4.6%和0.9%。结论我地区儿童肠道可培养拟杆菌对多种常用抗菌药物耐药性较高,尤以青霉素、阿莫西林、克林霉素、替卡西林和哌拉西林为甚,其中,脆弱拟杆菌对头孢替坦、头孢西丁和亚胺培南的耐药率高于其他拟杆菌。既往有广谱抗生素用药史的儿童中分离获得菌对哌拉西林、头孢替坦、替卡西林、头孢西丁和亚胺培南的耐药率高于无相关用药史的儿童来源菌,且从年长儿肠道分离的拟杆菌对头孢西丁、亚胺培南耐药性高于低龄儿童。我国儿童拟杆菌的耐药性可能被严重低估,应加强不同地区针对儿童拟杆菌的抗微生物药物敏感性试验系统性监测。

拟杆菌对高能低蛋白饲粮诱导的脂肪肝出血综合征蛋鸡肝脏脂质代谢的影响

研究旨在探讨拟杆菌对高能低蛋白饲粮诱导的脂肪肝出血综合征(FLHS)蛋鸡肝脏脂质代谢的影响。选取80只210日龄体重为(1.5±0.2)kg的大午金凤蛋鸡,随机分为4组,每组5个重复,每个重复4只鸡。对照组(C组)饲喂基础饲粮,模型组(M组)饲喂高能低蛋白(HELP)饲粮,拟杆菌低剂量组(BL组)饲喂HELP饲粮+1×10^(9)CFU/mL拟杆菌,拟杆菌高量组(BH组)饲喂HELP饲粮+1×10^(11)CFU/mL拟杆菌。试验期70 d。结果显示:与C组相比,M组蛋鸡肝脏油腻、质脆易碎,出现大量脂肪空泡和红染脂滴;肝脏指数、腹脂率显著上升(P<0.05);血清总甘油三酯(TG)、总胆固醇(TC)、低密度脂蛋白胆固醇(LDL-C)含量及谷草转氨酶(AST)、谷丙转氨酶(ALT)活性显著上升(P<0.05),高密度脂蛋白胆固醇(HDL-C)含量显著下降(P<0.05)。与M组相比,BL组和BH组蛋鸡肝脏脂肪空泡和红染脂滴有明显改善;肝脏指数显著降低(P<0.05);血清TG、TC、LDL-C含量及AST、ALT活性均显著下降(P<0.05),HDL-C含量显著上升(P<0.05)。与BH组相比,BL组蛋鸡血清TG、TC含量及AST活性显著降低(P<0.05),HDL-C含量显著升高(P<0.05)。研究表明,拟杆菌可改善FLHS引起的蛋鸡脂质代谢紊乱和肝功能损伤,添加1×10^(9)CFU/mL拟杆菌对调节FLHS蛋鸡的肝脏脂质代谢效果更佳。

基于PCR-DGGE和拟杆菌(Bacteroides)16S rRNA的岩溶地下水粪便污染来源示踪研究:以重庆南山老龙洞地下河系统为例

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.

Lower abundance of Bacteroides and metabolic dysfunction are highly associated with the post-weaning diarrhea in piglets

Growing evidences show a direct link between diarrhea and disorders of gut microbiota in pigs.However,whether there are microbial markers associated with post-weaning diarrhea remains unknown.In the current study,we compared the microbial community,functions and metabolites between healthy weaned piglets(group H,n=7)and piglets with post-weaning diarrhea(group D,n=7),in order to find out diarrhea associated microbial markers.Each of 7 fecal samples was collected from H and D piglets(weaned at 21 d and sampled at 26 d).The metagenomic and untargeted metabolomic analysis revealed that the microbial composition,function and metabolic profile in D pigs was considerably reshaped,including the reduced abundance and number of Bacteroides,which significantly correlated with the diarrhea status of host.The carbohydrate metabolism,biosynthesis and metabolism,lipid metabolism,amino acid metabolism,and the activity of glycan and carbohydrates digestion related enzymes showed extensively down-regulated in D pigs compared with H pigs.Diarrhea significantly changed the metabolic profiles of fecal microbiota,and most of the altered metabolites were negatively or positively correlated with the change in the abundance of Bacteroides.In conclusion,the lower abundance of Bacteroides and its associated metabolic dysfunction may be regarded as microbial markers of physiological post-weaning diarrhea in piglets.

Bacteroides ovatus-mediated CD27^(−)MAIT cell activation is associated with obesity-related T2D progression

Type 2 diabetes(T2D)is highly associated with obesity.However,the factors that drive the transition from excessive weight gain to glucose metabolism disruption are still uncertain and seem to revolve around systemic immune disorder.Mucosal-associated invariant T(MAIT)cells,which are innate-like T cells that recognize bacterial metabolites,have been reported to be altered in obese people and to lead to metabolic dysfunction during obesity.By studying the immunophenotypes of blood MAIT cells from a cross-sectional cohort of obese participants with/without T2D,we found an elevation in CD27^(-)negative(CD27−)MAIT cells producing a high level of IL-17 under T2D obese conditions,which could be positively correlated with impaired glucose metabolism in obese people.We further explored microbial translocation caused by gut barrier dysfunction in obese people as a triggering factor of MAIT cell abnormalities.Specifically,accumulation of the bacterial strain Bacteroides ovatus in the peripheral blood drove IL-17^(-)producing CD27−MAIT cell expansion and could be associated with T2D risk in obese individuals.Overall,these results suggest that an aberrant gut microbiota–immune axis in obese people may drive or exacerbate T2D.Importantly,CD27−MAIT cell subsets and Bacteroides ovatus could represent targets for novel interventional strategies.Our findings extend current knowledge regarding the clinical relevance of body mass index(BMI)-associated variation in circulating MAIT cells to reveal the role of these cells in obesity-related T2D progression and the underlying cellular mechanisms.

肝硬化患者TIPS术后肠道菌群特征性改变及其与临床指标的相关性研究

目的比较既往行颈静脉肝内门体分流术(transjugular intrahepat portosystemic stent-shunt,TIPS)手术的肝硬化患者与未经TIPS手术的肝硬化患者的肠道菌群,探索在肝硬化患者中,TIPS手术与肠道菌群的关系,为基于肠道菌群干预改善肝硬化TIPS手术预后提供新思路。方法行TIPS手术的肝硬化患者为手术组,未经TIPS手术的肝硬化患者为对照组,收集患者大便标本行16S rRNA测序分析,并分析肠道菌群与临床指标相关性。结果两组患者在性别、年龄、体重指数(BMI)、病因等基线资料上均无显著差异(P>0.05),但临床血清学指标(如HGB,RBC,ALP,ALB,TBIL,PT,INR,APTT,UREA等)有显著差异(P<0.05)。手术组与对照组相比,α多样性无统计学差异(P>0.05),β多样性差异明显(P<0.01),手术组Bacteroides(拟杆菌属)明显增多(P<0.01),而对照组Bifidobacterium(双歧杆菌属)明显增多(P<0.05)。肠道菌群功能预测分析显示,手术组较对照组D-谷氨酰胺和D-谷氨酸代谢显著上升(P<0.05),次级胆汁酸生物合成(P<0.05)也显著上升。临床指标与菌群相关性分析中发现,总胆红素(TBIL)及直接胆红素(DBIL)与Bacteroides(拟杆菌属)、次级胆汁酸代谢通路显著相关。结论肝硬化TIPS术后患者肝硬化对照者相比,肠道菌群存在特征性改变,Bacteroides(拟杆菌属)可能参与胆汁酸代谢调控进而影响TIPS术后血胆红素水平升高。