Ability of lactulose breath test results to accurately identify colorectal polyps through the measurement of small intestine bacterial overgrowth

BACKGROUND While colorectal polyps are not cancerous,some types of polyps,known as adenomas,can develop into colorectal cancer over time.Polyps can often be found and removed by colonoscopy;however,this is an invasive and expensive test.Thus,there is a need for new methods of screening patients at high risk of developing polyps.AIM To identify a potential association between colorectal polyps and small intestine bacteria overgrowth(SIBO)or other relevant factors in a patient cohort with lactulose breath test(LBT)results.METHODS A total of 382 patients who had received an LBT were classified into polyp and non-polyp groups that were confirmed by colonoscopy and pathology.SIBO was diagnosed by measuring LBTderived hydrogen(H)and methane(M)levels according to 2017 North American Consensus recommendations.Logistic regression was used to assess the ability of LBT to predict colorectal polyps.Intestinal barrier function damage(IBFD)was determined by blood assays.RESULTS H and M levels revealed that the prevalence of SIBO was significantly higher in the polyp group than in the non-polyp group(41%vs 23%,P<0.01;71%vs 59%,P<0.05,respectively).Within 90 min of lactulose ingestion,the peak H values in the adenomatous and inflammatory/hyperplastic polyp patients were significantly higher than those in the non-polyp group(P<0.01,and P=0.03,respectively).In 227 patients with SIBO defined by combining H and M values,the rate of IBFD determined by blood lipopolysaccharide levels was significantly higher among patients with polyps than those without(15%vs 5%,P<0.05).In regression analysis with age and gender adjustment,colorectal polyps were most accurately predicted with models using M peak values or combined H and M values limited by North American Consensus recommendations for SIBO.These models had a sensitivity of≥0.67,a specificity of≥0.64,and an accuracy of≥0.66.CONCLUSION The current study made key associations among colorectal polyps,SIBO,and IBFD and demonstrated that LBT has moderate potential as an alternative noninvasive screening tool for colorectal polyps.

Diversity of bacterial lactase genes in intestinal contents of mice with antibiotics-induced diarrhea

AIM To investigate the diversity of bacterial lactase genes in the intestinal contents of mice with antibiotics-induced diarrhea.METHODS Following 2 d of adaptive feeding, 12 specific pathogenfree Kunming mice were randomly divided into the control group and model group. The mouse model of antibiotics-induced diarrhea was established by gastric perfusion with mixed antibiotics(23.33 m L·kg^(-1)·d^(-1)) composed of gentamicin sulfate and cephradine capsules administered for 5 days, and the control group was treated with an equal amount of sterile water. Contents of the jejunum and ileum were then collected and metagenomic DNA was extracted, after which analysis of bacterial lactase genes using operational taxonomic units(OTUs) was carried outafter amplification and sequencing.RESULTS OTUs were 871 and 963 in the model group and control group, respectively, and 690 of these were identical. There were significant differences in Chao1 and ACE indices between the two groups(P < 0.05). Principal component analysis, principal coordination analysis and nonmetric multidimensional scaling analyses showed that OTUs distribution in the control group was relatively intensive, and differences among individuals were small, while in the model group, they were widely dispersed and more diversified. Bacterial lactase genes from the intestinal contents of the control group were related to Proteobacteria, Actinobacteria, Firmicutes and unclassified bacteria. Of these, Proteobacteria was the most abundant phylum. In contrast, the bacterial population was less diverse and abundant in the model group, as the abundance of Bradyrhizobium sp. BTAi1, Agrobacterium sp. H13-3, Acidovorax sp. KKS102, Azoarcus sp. KH32 C and Aeromonas caviae was lower than that in the control group. In addition, of the known species, the control group and model group had their own unique genera, respectively.CONCLUSION Antibiotics reduce the diversity of bacterial lactase genes in the intestinal contents, decrease the abundance of lactase gene, change the lactase gene strains, and transform their structures.

The Influence of Bt-Transgenic Maize Pollen on the Bacterial Diversity in the Midgut of Chinese Honeybees, Apis cerana cerana

Using culture-independent technique polymerase chain reaction-denaturing gradient gel electrophoresis （PCR-DGGE） and conventional culture techniques, ecological risk of transgenic maize pollen on gut bacteria of the Chinese honeybee, Apis cerana cerana, was assessed. Honeybees were fed with Bt-transgenic maize pollen, non-transgenic near isoline pollen, linear crylAh gene （800 ng mL^-1） and supercoiled plasmid DNA （800 ng mL^-1） under laboratory conditions. The DGGE profile showed that the number of DGGE bands varied from 10.7 to 14.7 per sample, and the Shannon＇s index ranged from 0.85 to 1.00. The similarity calculated by PAST was mostly above 92%, indicating no obvious changes among treatments or within replicates. 14 bacterial strains affiliated with Alphaproteobacteria, Gammaproteobacteria, Firmicutes, and Actinobacteria were isolated and characterized on media under aerobic and anaerobic conditions. These results demonstrated that transgenic crylAh maize pollen did not induce significant changes of the honeybee gut bacterial community composition under laboratory conditions.

A Comparative Study on Rat Intestinal Epithelial Cells and Resident Gut Bacteria (ii) Effect of Arsenite

Objective In order to use facultative gut bacteria as an alternate to animals for the initial gastrointestinal toxicity screening of heavy metals, a comparative study on rat intestinal epithelial cells and resident gut bacteria was undertaken. Methods in vitro growth rate of four gut bacteria, dehydrogenase （DHA） and esterase （EA） activity test, intestinal epithelial and bacterial cell membrane enzymes and in situ effect of arsenite were analysed. Results Growth profile of mixed resident population of gut bacteria and pure isolates of Escherichia coli, Pseudomonas sp., Lactobacillus sp., and Staphylococcus sp. revealed an arsenite （2-20 ppm） concentration-dependent inhibition. The viability pattern of epithelial cells also showed similar changes. DHA and EA tests revealed significant inhibition （40%-72%） with arsenite exposure of 5 and 10 ppm in isolated gut bacteria and epithelial cells. Decrease in membrane alkaline phosphatase and Ca^2＋-Mg^2＋-ATPase activities was in the range of 33%-55% in four bacteria at the arsenite exposure of 10 ppm, whereas it was 60%-65% in intestinal epithelial villus cells, in situ incubation of arsenite using intestinal loops also showed more or less similar changes in membrane enzymes of resident gut bacterial population and epithelial cells. Conclusion The results indicate that facultative gut bacteria can be used as suitable in vitro model for the preliminary screening of arsenical gastrointestinal cytotoxic effects.

Effect of different modeling time on intestinal bacteria in letrozole induced PCOS rats

Objective:The differences of ovarian morphology,reproductive hormones,glucose and lipid metabolism and intestinal bacteria in rats with polycystic ovary syndrome(PCOS)induced by triazole were compared.Method:Eighteen 21 SPF female SD rats were randomly divided into group A(3-week group),group B(5-week group)and group D(control group)by random number table.Group A received letrozole+CMC-Na mixture by gavage in the first 3 weeks and CMC-Na solution by gavage in the last 2 weeks,group B received letrozole+CMC-Na mixture by gavage for 5 weeks,and group D received CMC-Na solution by gavage for 5 weeks,and all three groups of rats were fed with normal diet.At the end of gavage,the body weight of rats in each group was observed,the histological changes of ovaries were observed by hematoxylin-eosin(HE)staining,the serum levels of estradiol(E2),follicle stimulating hormone(FSH),luteinizing hormone(LH),testosterone(T),total cholesterol(TC),triglyceride(TG),fasting blood glucose(Glu),fasting insulin(FINS)and lipopolysaccharide(LPS)were measured by enzyme-linked immunosorbent assay(ELISA),and the LH/FSH ratio and insulin resistance index(HOMA IR)were calculated;the intestinal bacteria of rats were detected by 16S rRNA technique.Result:1.Comparison of ovary histomorphology:Under light microscope,multiple luteum and oocytes were observed in mature follicles in group D,and granulosa cells were orderly arranged and multilayered,without cystic dilated follicles.There were no mature follicles in the ovarian tissues of group A and GROUP B.The follicles were irregular in structure and more cystic dilated follicles were visible.The number of granular cells in some follicles decreased or even disappeared.2.Comparison of sex hormone levels:compared with group D,T level in group B was significantly increased(P<0.001),and T level in group A had an upward trend(P>0.05);The LH/FSH levels in group A and B were significantly increased(P<0.001;P<0.001).Compared with group A,E2 in group B was significantly decreased(P<0.05)and T was significantly increased(P<0.01).3.Comparison of glucose and lipid metabolism levels:Compared with group D,TC levels in groups A and B were significantly increased(P<0.01;P<0.01).Compared with group A,TG in group B was significantly increased(P<0.05).There were no significant differences in Glu,FINS and HOMA-IR levels among all groups.4.Comparison of LPS levels:Compared with group D,the serum LPS levels of rats in groups A and B were significantly increased(P<0.001;P<0.01).5.Intestinal flora analysis and comparison:At the phylum level,compared with group D,the abundance of Firmicutes in group B increased(P<0.01),Firmicutes in group A showed an upward trend(P>0.05),and the abundance of Bacteroidetes in groups A and B decreased(P<0.05).At the genus level,compared with group D,Lactobacillus in group B increased(P<0.01).The results of LEfSe analysis showed that there were differences in the composition of various intestinal bacteria among the three groups(LDA>3).Conclusion:The phenotype of PCOS rats was related to the length of modeling,and the phenotypic characteristics of PCOS in rats at 5 weeks of modeling were more typical than those in rats at 3 weeks of modeling;PCOS can cause changes in intestinal flora,and the changes in the structure of intestinal flora between groups are related to different modeling duration.

Washed microbiota transplantation reduces proton pump inhibitor dependency in nonerosive reflux disease

BACKGROUND The pathogenesis of gastroesophageal reflux disease(GERD)is closely associated with the intestinal bacteria composition and their metabolites.AIM To investigate whether washed microbiota transplantation(WMT)improves symptoms of nonerosive reflux disease(NERD)with proton pump inhibitor(PPI)dependency.METHODS Patients with recurrent NERD and PPI dependency at the First Affiliated Hospital of Guangdong Pharmaceutical University from 2017 to 2018 were included and divided into a WMT or PPI group treated with PPI with/without WMT.The endpoint was NERD symptom frequency evaluated 1 mo after WMT using reflux disease questionnaire(RDQ)and GERD questionnaire(GERDQ)scores,remission time,PPI dose,and the examination of intestinal mucosal barrier function.RESULTS In the WMT(n=15)and PPI(n=12)groups,the total remission rate at 1 mo after treatment was 93.3%vs 41.7%.Compared with the PPI group,the WMT group showed better results in GERDQ(P=0.004)and RDQ(P=0.003)and in remission months(8 vs 2,P=0.002).The PPI dose was reduced to some extent for 80%of patients in the WMT group and 33.3%in the PPI group.In 24 patients,intestinal mucosal barrier function was examined before treatment,and changes in the degree of damage were observed in 13 of these patients after treatment.Only one of the 15 patients had minor side effects,including a mushy stool two or three times a day,which resolved on their own after 1 wk.CONCLUSION This study is the first to demonstrate that WMT may be safe and effective for relieving NERD symptoms and reducing PPI dependency and recurrence.

Screening beneficial bacteriostatic lactic acid bacteria in the intestine and studies of bacteriostatic substances

Lactic acid bacteria(LAB)are a representative probiotic.As the dominant flora in the human intestinal tract,LAB can regulate the balance of human intestinal flora and improve host health.The purpose of this study was to isolate and screen LAB that are well suited to the intestinal characteristics of the Chinese population,with excellent probiotics and high antibacterial activity.After 16S ribosomal RNA(rRNA)homology and phylogenetic tree analysis,potential probiotics were tested for their antibacterial activity,resistance to artificial gastrointestinal fluid and drugs,surface hydrophobicity,and safety.Three strains of LAB with acid resistance,bile salt resistance,epithelial cell adhesion,and no multidrug resistance were selected:Lactobacillus salivarius,Leuconostoc lactis,and Lactobacillus paracasei.Analysis of the antibacterial active substances in the three strains and their fermentation broths revealed that the main antibacterial substances of L.lactis were organic acids,whereas those of L.salivarius and L.paracasei were organic acids and bacteriocins with broad-spectrum antibacterial activity.These three strains of probiotic LAB with high antibacterial activity were identified as bacterial resources that could potentially be used to develop probiotic preparations for the prevention and treatment of intestinal diseases caused by intestinal pathogens.

Intestinal Transport and Biotransformation of Resibufogenin and Cinobufagin in Chan Su via HPLC/APCI-MS^n

In vitro models of human colon carcinoma cell line(Caco-2 cell monolayer) and human intestinal bacteria were used to investigate the intestinal transport and biotransformation of resibufogenin and cinobufagin in Chan Su by HPLC/APCI-MSn. The experimental results of Caco-2 cell monolayer demonstrate that the apparent permeability coefficients(Papp) of resibufogenin and cinobufagin are higher than 10–6 cm/s, which indicates that both resibufogenin and cinobufagin have a good absorption in the small intestine. And the biotransformation result of human intestinal bacteria shows that resibufogenin has been transformed to 3-epiresibufogenin and cinobufagin has been transformed to 3-epicinobufagin, deacetylcinobufagin and 3-epideacetycinobufagin, respectively.

Role of regenerating islet-derived proteins in inflammatory bowel disease

Inflammatory bowel disease(IBD)is an inflammatory disorder of the gastrointestinal tract that affects millions of patients worldwide.It has a complex and multifactorial etiology leading to excessive exposure of intestinal epithelium to microbial antigens,inappropriate activation of the immune system and ultimately to the damage of intestinal tissues.Although numerous efforts have been made to improve the disease management,IBD remains persistently recurring and beyond cure.This is due largely to the gaps in our understanding of the pathogenesis of IBD that hamper the development of timely diagnoses and effective treatment.However,some recent discoveries,including the beneficial effects of interleukin-22(IL-22)on the inflamed intestine,have shed light on a self-protective mechanism in IBD.Regenerating islet-derived(REG/Reg)proteins are small secretory proteins which function as IL-22’s downstream effectors.Mounting studies have demonstrated that IBD patients have significantly increased REG expressions in the injured intestine,but with undefined mechanisms and roles.The reported functions of REG/Reg proteins in intestinal homeostasis,such as those of antibacterial,anti-inflammatory and tissue repair,lead us to discuss their potential mechanisms and clinical relevance in IBD in order to advance IBD research and management.

Effects of rhamnolipids on bacterial communities in a dioxin-contaminated soil and the gut of earthworms added to the soil

The biosurfactants rhamnolipids and the “soil ecosystem engineers” earthworms are often used to remediate contaminated soils. However, the effects of rhamnolipids on earthworm intestinal flora and microbial community in soil containing earthworms are not clearly understood. In our study, a 21-d microcosm experiment was carried out to reveal the effects of rhamnolipids on microbial abundance, composition, and metabolism, as well as contaminant degradation capacity. Both rhamnolipids and earthworms had positive effects on soil bacteria. Rhamnolipid-amended soil(RT) showed higher bacterial abundance and metabolic activity than earthworm-amended soil(ET), while the improvement in bacterial composition and contaminant degradation capacity by rhamnolipids was lower than that by earthworms. Notably, these effects were further amplified by the combined treatment of rhamnolipids and earthworms(RET). Specifically, the bacterial abundance(log-transferred) increased from 9.5 copies g-1in the control with no addition to 10.3, 10.6, and 11.1 copies g-1in ET, RT, and RET, respectively. Compared to ET, the relative abundance of the dominant phylum, Proteobacteria, increased from 41.66% to 51.67% in RET,and more pollutant-degrading bacteria were also enriched in RET. Therefore, the increases in bacterial abundance and contaminant-degrading bacteria led to the following ranking of soil dioxin removal rate: RET(77.28%) > ET(59.83%) > RT(24.65%) > control(4.71%). Moreover, the addition of rhamnolipids enhanced the abundance of bacterial functional genes involved in metabolism and environmental information processing. In addition, the composition and diversity of bacteria in the gut of earthworms were conspicuously affected by rhamnolipids, and the relative abundance of Microbacterium and Shewanella increased significantly(P < 0.05). Therefore, this study revealed that rhamnolipids remarkably influenced the abundance, composition, and metabolism of the microbial community in earthworm gut, further promoting the degradation rate of dioxin, providing theoretical support for optimizing the combined application of rhamnolipids and earthworms in soil bioremediation engineering and for the assessment of the ecological impact of rhamnolipids.

Mechanism of Incompatible Herb Pairs, Panax ginseng and Veratrum nigrum L,： Material Basis and Metabolic Profiles of Ginsenosides in Rat Intestinal Bacteria

In traditional Chinese medicine theory, Panax ginseng and Veratrum nigrum L. is an important incompatible herb pair. Studies on the content variation of main components and the influences on the metabolism in rat intestinal bacteria are useful to understand the mechanism of incompatibility of this herb pairs. In this study, the content variation of ginsenosides and their metaboltic profiles in the extracts of P. ginseng and compatibility of P. ginseng with V. nigrum L. （G-V） were investigated using relative quantitative method of electrospray ionization mass spec- trometry （ESI-MS） and UPLC-MSn, respectively. The relative contents of most ginsenosides were reduced in the extract of G-V. Furthermore, ginsenosides Rbt, Rb2, Rc and Rd could be metabolized to Rd, F2 and C-K in rat in- testinal bacteria. The metabolic speeds ofRbl, Rb2 and Re in the G-V extracts at ratios of 10 ： 5, 10 ： 7 and 10 ： 10 and the metabolic rates of ginsenosides Rbb Rb2 and Rc to Rd, Rd to F2 in all compatibility extracts were lower than that in the P ginseng extract. In conclusion, this study illustrated the mechanism of effect-reducing by comparison of the relative contents and metabolic profiles of ginsenosides after compatibility of P ginseng and V. nigrum L.

Study on the Metabolic Characteristics of Aconite Alkaloids in the Extract of Radix aconiti under Intestinal Bacteria of Rat by UPLC/MSn Technique

The extract of Radix aconiti was incubated with rat intestinal bacteria in vitro. Further, aconitine and hypaconitine standard were incubated at the same condition as the extract of Radix aconiti, respectively. Ultra Performance Liquid Chromatography/Multi-Mass Spectrometry （UPLC/MSn） was used for detecting and identifying all the aco- nite alkaloids. Results showed that there were four metabolites which were identified as 8-butyryl-14-benzoylmesa- conine （m/z 660）, 8-propionyl-14-benzoylaconine （m/z 660）, 8-butyryl-14-benzoylaconine （m/z 674） and 8-valeryl-14-benzoylmesaconine （m/z 674） in the metabolized sample of the extract of Radix aconiti. The relative area ratio of them presented increasing trend during 6 d. On the basis of all results, we could concluded that substi- tution at N atom mainly influenced the metabolizing rate of diester-diterpenoid alkaloids （DDAs）, C-8 substitute was active metabolized site, intestinal bacterial metabolites of the aconite alkaloids in the extract of Radix aconiti were mainly the substitute with propionyl group, butyl group or valeryl group at C-8. This paper illustrated holistic metabolizing profile of the extract of Radix aconiti in vitro and possible metabolizing reaction type of main DDAs, which could provide reference for finding out potential bioactive components in the extract and the prescription of Chinese Medicine.

UPLC-Q-TOF/MS-based Metabolic Profiles of Bioactive Components in Rehmannia glutinosa and Cornus officinalis Herb Pair by Rat Intestinal Bacteria

Objective To investigate the metabolic routes and metabolites of Rehmannia glutinosa and Cornus officinalis herb pair produced by gut microbiome from rats.Methods A rapid and sensitive ultra-performance liquid chromatography/quadrupole-time-offlight mass spectrometry（UPLC-Q-TOF/MS） technique combined with Metabolynx？software was established and successfully applied to identify the metabolites of the main bioactive components in the herb pair extract by rat intestinal bacteria.Results Four parent compounds（loganin,morroniside,catalpol,and acteoside） and their eight corresponding metabolites were detected and tentatively identified by the characteristics of their protonated ions.Hydrogenated and demethylated loganetin,dehydroxylated morronisid aglycone,caffeic acid,and its methylated product were the main metabolites.These metabolites suggested that the glycosides were firstly hydrolyzed to their aglycones by hydrolytic enzymes of the enteric microbial flora and subsequently to the other metabolites through hydrogenation,（de）-methylation,and de-hydroxylation.Conclusion The results may be helpful for the further investigation of the pharmacokinetic study of R.glutinosa and C.officinalis herb pair in vivo.

Exercise and gut microbiota: clinical implications for the feasibility of Tai Chi

Recent studies have shown exercise is associated with changes in the gut microbiota in humans as well as in experimental animals. Tai Chi is an exercise that integrates a martial art, deep breathing and mediation, and has various beneficial effects for health. This review summarizes current knowledge and recent literature on the association between exercise and gut microbiota, and explores the feasibility of Tai Chi for improving gut microbiota composition and function. PubMed/MEDLINE was used to search the English literature for the keywords exercise and gut microbiota. Fourteen relevant studies were identified. In humans, exercise increases the gut microbial diversity. However, the evidence for this association is weak, as previous studies were small-scale, non-controlled studies of short duration or cross-sectional design. In animals, exercise alters the composition of gut microbiota, with some studies suggesting exercise increases the Bacteroidetes/ Firmicutes ratio. However, these results are controversial, partly because host genetics and physical fitness also influence gut microbiota. Furthermore, the intensity of exercise may play a key role in how exercise affects gut microbiota. Tai Chi is a moderate-intensity exercise that improves immune function and inflammation of the gut. Tai Chi may also affect gut microbiota through vagal modulation and mediating the hypothalamic-pituitary-adrenal axis. However, no studies have investigated the association between Tai Chi and gut microbiota. Well designed studies exploring the effects of Tai Chi on gut microbiota are needed.

Microbe-based management for colorectal cancer

Colorectal cancer(CRC)is one of the most prevalent,most lethal cancers in the world.Increasing evidence suggests that the intestinal microbiota is closely related to the pathogenesis and prognosis of CRC.The normal microbiota plays an essential role in maintaining gut barrier function and the immune microenvironment.Recent studies have identified carcinogenic bacteria such as enterotoxigenic Bacteroides fragilis(ETBF)and Streptococcus gallolyticus(S.gallolyticus),as well as protective bacterial such as Akkermansia muciniphila(A.muciniphila),as potential targets of CRC treatment.Gut microbiota modulation aims to restore gut dysbiosis,regulate the intestinal immune system and prevent from pathogen invasion,all of which are beneficial for CRC prevention and prognosis.The utility of probiotics,prebiotics,postbiotics,fecal microbiota transplantation and dietary inventions to treat CRC makes them novel microbe-based management tools.In this review,we describe the mechanisms involved in bacteria-derived colorectal carcinogenesis and summarized novel bacteria-related therapies for CRC.In summary,we hope to facilitate clinical applications of intestinal bacteria for preventing and treating CRC.

Effects of a combined infection with Paranosema locustae and Beauveria bassiana on Locusta migratoria and its gut microflora

Even though Paranosema locustae is widely used in China as a biological agent for controlling grasshoppers,the mortality rate is initially quite low.This study sought to determine whether the simultaneous use of P.locustae and Beauveria bassiana would be a more effective control strategy.Additionally,changes in the intestinal microbial communities of migratory locusts infected with the two pathogens were analyzed to investigate the roles of gut microbes in pathogen-host interactions.The mortality rate of locusts inoculated with B.bassiana and P.locustae simultaneously was not significantly higher than expected but the mortality rates of locusts inoculated with B.bassiana 3,6,and 9 days after inoculation with P.locustae were significantly higher than if their effects were additive,indicating synergism.A MiSeq analysis found that Weissella was the most common bacterium,representing 41.48%and 51.62%of the total bacteria in the mid-and hindguts,respectively,and the bacterial declines were greatest during dual infections with B.bassiana and P.locustae.The appropriately timed combined application of P.locustae and B.bassiana was more effective against locusts than either treatment alone.Moreover,the combined inoculation of the two pathogens changed the gut microflora of locusts,indicating the potential relevancy of their synergistic effects on locust control.