Altered fecal microbiota composition in patients with major depressive disorder

Studies using animal models have shown that depression affects the stability of the microbiota, but the actual structure and composition in patients with major depressive disorder (MDD) are not well understood. Here, we analyzed fecal samples from 46 patients with depression (29 active-MDD and 17 responded-MDD) and 30 healthy controls (HCs). High-throughput pyrosequencing showed that, according to the Shannon index, increased fecal bacterial α-diversity was found in the active-MDD (A-MDD) vs. the HC group but not in the responded-MDD (R-MDD) vs. the HC group. Bacteroidetes, Proteobacteria, and Actinobacteria strongly increased in level, whereas that of Firmicutes was significantly reduced in the A-MDD and R-MDD groups compared with the HC group. Despite profound interindividual variability, levels of several predominant genera were significantly different between the MDD and HC groups. Most notably, the MDD groups had increased levels of Enterobacteriaceae and Alistipes but reduced levels of Faecalibacterium. A negative correlation was observed between Faecalibacterium and the severity of depressive symptoms. These findings enable a better understanding of changes in the fecal microbiota composition in such patients, showing either a predominance of some potentially harmful bacterial groups or a reduction in beneficial bacterial genera. Further studies are warranted to elucidate the temporal and causal relationships between gut microbiota and depression and to evaluate the suitability of the microbiome as a biomarker.

Human intestinal lumen and mucosa-associated microbiota in patients with colorectal cancer

Recent reports have suggested the involvement of gut microbiota in the progression of colorectal cancer (CRC). We utilized pyrosequencing based analysis of 16S rRNA genes to determine the overall structure of microbiota in patients with colorectal cancer and healthy controls; we investigated microbiota of the intestinal lumen, the cancerous tissue and matched noncancerous normal tissue. Moreover, we investigated the mucosa-adherent microbial composition using rectal swab samples because the structure of the tissue-adherent bacterial community is potentially altered following bowel cleansing. Our findings indicated that the microbial structure of the intestinal lumen and cancerous tissue differed significantly. Phylotypes that enhance energy harvest from diets or perform metabolic exchange with the host were more abundant in the lumen. There were more abundant Firmicutes and less abundant Bacteroidetes and Proteobacteria in lumen. The overall microbial structures of cancerous tissue and noncancerous tissue were similar; however the tumor microbiota exhibited lower diversity. The structures of the intestinal lumen microbiota and mucosa-adherent microbiota were different in CRC patients compared to matched microbiota in healthy individuals. Lactobacillales was enriched in cancerous tissue, whereas Faecalibacterium was reduced. In the mucosa-adherent microbiota, Bifidobacterium, Faecalibacterium, and Blautia were reduced in CRC patients, whereas Fusobacterium, Porphyromonas, Peptostreptococcus, and Mogibacterium were enriched. In the lumen, predominant phylotypes related to metabolic disorders or metabolic exchange with the host, Erysipelotrichaceae, Prevotellaceae, and Coriobacteriaceae were increased in cancer patients. Coupled with previous reports, these results suggest that the intestinal microbiota is associated with CRC risk and that intestinal lumen microflora potentially influence CRC risk via cometabolism or metabolic exchange with the host. However, mucosa-associated microbiota potentially affects CRC risk primarily through direct interaction with the host.

The Intestinal Microbiota and Colorectal Cancer

The intestinal microbiota, composed of a large population of microorganisms, is often considered a "forgotten organ" in human health and diseases. Increasing evidence indicates that dysbiosis of the intestinal microbiota is closely related to colorectal cancer (CRC). The roles for intestinal microorganisms that initiated and facilitated the CRC process are becoming increasingly clear. Hypothesis models have been proposed to illustrate the complex relationship between the intestinal microbiota and CRC. Recent studies have identified Streptococcus bovis, enterotoxigenic Bacteroides fragilis, Fusobacterium nucleatum, Enterococcus faecalis, Escherichia coli, and Peptostreptococcus anaerobius as CRC candidate pathogens. In this review, we summarized the mechanisms involved in microbiota-related colorectal carcinogenesis, including inflammation, pathogenic bacteria, and their virulence factors, genotoxins, oxidative stress, bacterial metabolites, and biofilm. We also described the clinical values of intestinal microbiota and novel strategies for preventing and treating CRC.

Maternal infection during pregnancy and risk of autism spectrum disorders: A systematic review and meta-analysis

Conflicting evidence exists with regard to the relationship between maternal infection during pregnancy and the risk of autism spectrum disorder (ASD) in offspring. The aim of this meta-analysis was to systematically assess this relationship. To identify relevant studies, we conducted systematic searches in PubMed and Embase of scientific articles published through March 2016. Random-effects models were adopted to estimate overall relative risk. A total of 15 studies (2 cohort and 13 case-control studies) involving more than 40,000 ASD cases were included in our meta-analysis. Our results showed that maternal infection during pregnancy was associated with an increased risk of ASD in offspring (OR=1.13, 95% confidence interval (CI): 1.03-1.23), particularly among those requiring hospitalization (OR=1.30, 95% CI: 1.14-1.50). Subgroup analyses suggested that risk may be modulated by the type of infectious agent, time of infectious exposure, and site of infection. These findings indicate that maternal infection during pregnancy increases the risk of ASD in offspring. Possible mechanisms may include direct effects of pathogens and, more indirectly, the effects of inflammatory responses on the developing brain.

Altered fecal microbiota composition associated with food allergy in infants

Increasing evidence suggests that perturbations in the intestinal microbiota composition of infants are implicated in the pathogenesis of food allergy (FA), while the actual structure and composition of the intestinal microbiota in human beings with FA remain unclear. Microbial diversity and composition were analyzed with parallel barcoded 454 pyrosequencing targeting the 16S rRNA gene hypervariable V1-V3 regions in the feces of 34 infants with FA (17 IgE mediated and 17 non-IgE mediated) and 45 healthy controls. Here, we showed that several key FA-associated bacterial phylotypes, but not the overall microbiota diversity, significantly changed in infancy fecal microbiota with FA and were associated with the development of FA. The proportion of abundant Bacteroidetes, Proteobacteria, and Actinobacteria phyla were significantly reduced, while the Firmicutes phylum was highly enriched in the FA group (P < 0.05). Abundant Clostridiaceae 1 organisms were prevalent in infants with FA at the family level (P = 0.016). FA-enriched phylotypes negatively correlated with interleukin-10, for example, the genera Enterococcus and Staphylococcus. Despite profound interindividual variability, levels of 20 predominant genera were significantly different between the FA and healthy control groups (P < 0.05). Infants with IgE-mediated FA had increased levels of Clostridium sensu stricto and Anaerobacter and decreased levels of Bacteroides and Clostridium XVIII (P < 0.05). A positive correlation was observed between Clostridium sensu stricto and serum-specific IgE (R = 0.655, P < 0.001). The specific microbiota signature could distinguish infants with IgE-mediated FA from non-IgE-mediated ones. Detailed microbiota analysis of a well-characterized cohort of infants with FA showed that dysbiosis of fecal microbiota with several FA-associated key phylotypes may play a pathogenic role in FA.

Molecular analysis of the diversity of vaginal microbiota associated with bacterial vaginosis

BACKGROUND

Bacterial vaginosis (BV) is an ecological disorder of the vaginal microbiota that affects millions of women annually, and is associated with numerous adverse health outcomes including pre-term birth and the acquisition of sexually transmitted infections. However, little is known about the overall structure and composition of vaginal microbial communities; most of the earlier studies focused on predominant vaginal bacteria in the process of BV. In the present study, the diversity and richness of vaginal microbiota in 50 BV positive and 50 healthy women from China were investigated using culture-independent PCR-denaturing gradient gel electrophoresis (DGGE) and barcoded 454 pyrosequencing methods, and validated by quantitative PCR.

RESULTS

Our data demonstrated that there was a profound shift in the absolute and relative abundances of bacterial species present in the vagina when comparing populations associated with healthy and diseased conditions. In spite of significant interpersonal variations, the diversity of vaginal microbiota in the two groups could be clearly divided into two clusters. A total of 246,359 high quality pyrosequencing reads was obtained for evaluating bacterial diversity and 24,298 unique sequences represented all phylotypes. The most predominant phyla of bacteria identified in the vagina belonged to Firmicutes, Bacteroidetes, Actinobacteria and Fusobacteria. The higher number of phylotypes in BV positive women over healthy is consistent with the results of previous studies and a large number of low-abundance taxa which were missed in previous studies were revealed. Although no single bacterium could be identified as a specific marker for healthy over diseased conditions, three phyla - Bacteroidetes, Actinobacteria and Fusobacteria, and eight genera including Gardnerella, Atopobium, Megasphaera, Eggerthella, Aerococcus, Leptotrichia/Sneathia, Prevotella and Papillibacter were strongly associated with BV (p < 0.05). These genera are potentially excellent markers and could be used as targets for clinical BV diagnosis by molecular approaches.

CONCLUSIONS

The data presented here have clearly profiled the overall structure of vaginal communities and clearly demonstrated that BV is associated with a dramatic increase in the taxonomic richness and diversity of vaginal microbiota. The study also provides the most comprehensive picture of the vaginal community structure and the bacterial ecosystem, and significantly contributes to the current understanding of the etiology of BV.

Alterations of gastric mucosal microbiota across different stomach microhabitats in a cohort of 276 patients with gastric cancer

BACKGROUND

As part of the tumor microenvironment, the gastric microbiota play vital roles in tumor initiation, progression and metastasis, but stomach microhabitats are not always uniform. We aimed to characterize differences of gastric microbiota in stomach microhabitats associated with gastric cancer (GC) development.

METHODS

A cohort of 276 GC patients without preoperative chemotherapy was enrolled retrospectively, and 230 normal, 247 peritumoral and 229 tumoral tissues were obtained for gastric microbiota analysis targeting the 16S rRNA gene by MiSeq sequencing. The microbial diversity and composition, bacterial co-occurrence correlations and predictive functional profiles were compared across different microhabitats.

FINDINGS

GC-specific stomach microhabitats, not GC stages or types, determine the composition and diversity of the gastric microbiota. Most notably, bacterial richness was decreased in peritumoral and tumoral microhabitats, and the correlation network of abundant gastric bacteria was simplified in tumoral microhabitat. Helicobacter pylori (HP), Prevotella copri and Bacteroides uniformis were significantly decreased, whereas Prevotella melaninogenica, Streptococcus anginosus and Propionibacterium acnes were increased in tumoral microhabitat. Higher HP colonisation influenced the overall structure of the gastric microbiota in normal and peritumoral microhabitats. PiCRUSt analysis revealed that genes associated with nucleotide transport and metabolism and amino acid transport and metabolism were significantly enriched in tumoral microbiota, while gastric acid secretion was significantly higher in HP positive group of the tumoral microbiota.

INTERPRETATION

Our present study provided new insights into the roles of gastric microbiota in different stomach microhabitats in gastric carcinogenesis, especially the pathogenesis of HP. FUND: National Natural Science Foundation of China.

Probiotic Gastrointestinal Transit and Colonization After Oral Administration: A Long Journey

Orally administered probiotics encounter various challenges on their journey through the mouth, stomach, intestine and colon. The health benefits of probiotics are diminished mainly due to the substantial reduction of viable probiotic bacteria under the harsh conditions in the gastrointestinal tract and the colonization resistance caused by commensal bacteria. In this review, we illustrate the factors affecting probiotic viability and their mucoadhesive properties through their journey in the gastrointestinal tract, including a discussion on various mucosadhesion-related proteins on the probiotic cell surface which facilitate colonization.

Effect of Clostridium butyricum against Microglia-Mediated Neuroinflammation in Alzheimer's Disease via Regulating Gut Microbiota and Metabolites Butyrate

SCOPE

Recent evidences demonstrate that abnormal gut microbiota (GM) might be involved in the pathogenesis of Alzheimer's disease (AD). However, the role of probiotics in preventing AD by regulating GM-gut-brain axis remains unclear. Here, the anti-neuroinflammatory effect and its mechanism of probiotic Clostridium butyricum (CB) against AD is investigated by regulating GM-gut-brain axis.

METHODS AND RESULTS

APPswe/PS1dE9 (APP/PS1) transgenic are treated intragastrically with CB for 4 weeks then cognitively tested. Amyloid-β (Aβ) burden, microglial activation, proinflammatory cytokines production, GM, and metabolites butyrate are analyzed. Moreover, Aβ-induced BV2 microglia are pretreated with butyrate, and the levels of cluster of differentiation 11b (CD11b), cyclooxygenase-2 (COX-2), and NF-κB p65 phosphorylation are determined. The results show that CB treatment prevents cognitive impairment, Aβ deposits, microglia activation, and production of tumor necrosis factor (TNF)-α and interleukin (IL)-1β in the brain of APP/PS1 mice. Meanwhile, abnormal GM and butyrate are reversed after CB treatment. Notably, butyrate treatment reduces the levels of CD11b and COX-2, and suppresses phosphorylation of NF-κB p65 in the Aβ-induced BV2 microglia.

CONCLUSIONS

These findings indicate that CB treatment could attenuate microglia-mediated neuroinflammation via regulating the GM-gut-brain axis, which is mediated by the metabolite butyrate.

Analysis of oral microbiota in children with dental caries by PCR-DGGE and barcoded pyrosequencing

Oral microbiota plays a vital role in maintaining the homeostasis of oral cavity. Dental caries are among the most common oral diseases in children and pathogenic bacteria contribute to the development of the disease. However, the overall structure of bacterial communities in the oral cavity from children with dental caries has not been explored deeply heretofore. We used high-throughput barcoded pyrosequencing and PCR-denaturing gradient gel electrophoresis (DGGE) to examine bacterial diversity of oral microbiota in saliva and supragingival plaques from 60 children aged 3 to 6 years old with and without dental caries from China. The multiplex barcoded pyrosequencing was performed in a single run, with multiple samples tagged uniquely by multiplex identifiers. As PCR-DGGE analysis is a conventional molecular ecological approach, this analysis was also performed on the same samples and the results of both approaches were compared. A total of 186,787 high-quality sequences were obtained for evaluating bacterial diversity and 41,905 unique sequences represented all phylotypes. We found that the oral microbiota in children was far more diverse than previous studies reported, and more than 200 genera belonging to ten phyla were found in the oral cavity. The phylotypes in saliva and supragingival plaques were significantly different and could be divided into two distinct clusters (p < 0.05). The bacterial diversity in oral microbiome analyzed by PCR-DGGE and barcoded pyrosequencing was employed to cross validate the data sets. The genera of Streptococcus, Veillonella, Actinomyces, Granulicatella, Leptotrichia, and Thiomonas in plaques were significantly associated with dental caries (p < 0.05). The results showed that there was no one specific pathogen but rather pathogenic populations in plaque that significantly correlated with dental caries. The enormous diversity of oral microbiota allowed for a better understanding of oral microecosystem, and these pathogenic populations in plaque provide new insights into the etiology of dental caries and suggest new targets for interventions of the disease.

Neuroprotective Effects of Clostridium butyricum against Vascular Dementia in Mice via Metabolic Butyrate

Probiotics actively participate in neuropsychiatric disorders. However, the role of gut microbiota in brain disorders and vascular dementia (VaD) remains unclear. We used a mouse model of VaD induced by a permanent right unilateral common carotid arteries occlusion (rUCCAO) to investigate the neuroprotective effects and possible underlying mechanisms of Clostridium butyricum. Following rUCCAO, C. butyricum was intragastrically administered for 6 successive weeks. Cognitive function was estimated. Morphological examination was performed by electron microscopy and hematoxylin-eosin (H&E) staining. The BDNF-PI3K/Akt pathway-related proteins were assessed by western blot and immunohistochemistry. The diversity of gut microbiota and the levels of butyrate in the feces and the brains were determined. The results showed that C. butyricum significantly attenuated the cognitive dysfunction and histopathological changes in VaD mice. C. butyricum not only increased the levels of BDNF and Bcl-2 and decreased level of Bax but also induced Akt phosphorylation (p-Akt) and ultimately reduced neuronal apoptosis. Moreover, C. butyricum could regulate the gut microbiota and restore the butyrate content in the feces and the brains. These results suggest that C. butyricum might be effective in the treatment of VaD by regulating the gut-brain axis and that it can be considered a new therapeutic strategy against VaD.

Probiotic Clostridium butyricum ameliorated motor deficits in a mouse model of Parkinson's disease via gut microbiota-GLP-1 pathway

A connection between gut microbiota and Parkinson's disease (PD) indicates that dysbiosis of the gut microbiota might represent a risk factor for PD. Microbiota-targeted interventions, including probiotic Clostridium butyricum (Cb), have been recently shown to have favorable effects in PD by regulating microbiota-gut-brain axis. However, the potential beneficial roles and its mechanisms of Cb on PD were still unknown. Male C57BL/6 mice were subjected to a PD model-induced by 1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine (MPTP) and were treated intragastrically with Cb for 4 weeks. The motor functions were assessed by a series of behavioral tests including pole test, beam walking teat, forced swimming test and open field test. The dopaminergic neuron loss, synaptic plasticity and microglia activation, as well as the levels of colonic glucagon-like peptide-1 (GLP-1), colonic G protein-coupled receptors GPR41/43 and cerebral GLP-1 receptors were assessed. Gut microbial composition was assessed by 16S rRNA sequencing analysis. Our results showed that oral administration of Cb could improve motor deficits, dopaminergic neuron loss, synaptic dysfunction and microglia activation in the MPTP-induced mice. Meanwhile, Cb treatment could reverse the dysbiosis of gut microbiota and the decreased levels of colonic GLP-1, colonic GPR41/43 and cerebral GLP-1 receptor in the MPTP-induced mice. These findings indicated that the neuroprotective mechanism of Cb on PD might be related to the improvement of abnormal gut microbiota-gut-brain axis.

Gut microbial dysbiosis may predict diarrhea and fatigue in patients undergoing pelvic cancer radiotherapy: a pilot study

Fatigue and diarrhea are the most frequent adverse effects of pelvic radiotherapy, while their etiologies are largely unknown. The aim of this study is to investigate the correlations between fatigue, diarrhea, and alterations in gut microbiota induced by pelvic radiotherapy. During the 5-week treatment of pelvic radiotherapy in 11 cancer patients, the general fatigue score significantly increased and was more prominent in the patients with diarrhea. The fatigue score was closely correlated with the decrease of serum citrulline (an indicator of the functional enterocyte mass) and the increases of systemic inflammatory proteins, including haptoglobin, orosomuoid, α1-antitrypsin and TNF-α. Serum level of lipopolysaccharide (LPS) was also elevated, especially in the patients with diarrhea indicating epithelial barrier breach and endotoxemia. Pyrosequencing analysis of 16S rRNA gene revealed that microbial diversity, richness, and the Firmicutes/Bacteroidetes ratio were significantly altered prior to radiotherapy in patients who later developed diarrhea. Pelvic radiotherapy induced further changes in fecal microbial ecology, some of which were specific to the patients with or without diarrhea. Our results indicate that gut microbial dysbiosis prior to radiation therapy may be exploited to predict development of diarrhea and to guide preventive treatment options. Radiation-induced dysbiosis may contribute to pelvic radiation disease, including mucositis, diarrhea, systemic inflammatory response, and pelvic radiotherapy-associated fatigue in cancer patients.

A Borondifluoride-Complex-Based Photothermal Agent with an 80 % Photothermal Conversion Efficiency for Photothermal Therapy in the NIR-II Window

Small organic photothermal agents (SOPTAs) that absorb in the second near-infrared (NIR-II, 1000-1700 nm) window are highly desirable in photothermal therapy for their good biocompatibility and deeper tissue penetration. However, the design of NIR-II absorbing SOPTAs remains a great challenge. Herein, we report that molecular engineering of BF2 complex via strengthening the donor-acceptor conjugation and increasing the intramolecular motions is an efficient strategy to achieve NIR-II absorbing SOPTAs with high photothermal performance. Based on this strategy, a BF2 complex, BAF4, was designed and synthesized. BAF4 exhibits an intense absorption maximum at 1000 nm and negligible fluorescence. Notably, the nanoparticles of BAF4 achieve a high photothermal conversion efficiency value of 80 % under 1064 nm laser irradiation (0.75 W cm-2 ). In vitro and in vivo studies reveal the great potential of BAF4 nanoparticles in photoacoustic imaging-guided photothermal therapy in the NIR-II window.

Clostridium butyricum pretreatment attenuates cerebral ischemia/reperfusion injury in mice via anti-oxidation and anti-apoptosis

Probiotics participate actively in the neuropsychiatric disorders. However, their roles on ischemic stroke remain unclear. This study aims to determine whether Clostridium butyricum (C. butyricum) could attenuate cerebral ischemia/reperfusion (I/R) injury and its possible mechanisms. Male ICR mice were intragastrically pretreated with C. butyricum for 2 successive weeks, and then subjected to cerebral I/R injury induced by the bilateral common carotid artery occlusion (BCCAO) for 20min. After 24h of the reperfusion, neurological deficit scores were evaluated. Histopathological changes of the hippocampus neurons were observed using Hematoxylin and eosin (H&E) and TUNEL staining. Malondialdehyde (MDA) contents and superoxide dismutase (SOD) activities in the brain were detected. The expression of Caspase-3, Bax and Bcl-2 were investigated by Western blot and immunohistochemistry analysis. The butyrate contents in the brain were determined. Our results showed that cerebral I/R injury led to neurological deficit, increased levels of Caspase-3 and Bax and decreased Bcl-2/Bax ratio. C. butyricum significantly improved neurological deficit, relieved histopathologic change, decreased MDA contents and increased SOD activities in the I/R injury mice. After C. butyricum pretreatment, the expression of Caspase-3 and Bax were significantly decreased, the Bcl-2/Bax ratio was significantly increased, and butyrate contents in the brain were significantly increased. These findings suggested that C. butyricum is able to exert neuroprotective effects against I/R injury mice through anti-oxidant and anti-apoptotic mechanisms, and reversing decrease of butyrate contents in the brain might be involved in its neuroprotection.

Dysbiosis of Intestinal Microbiota Associated With Inflammation Involved in the Progression of Acute Pancreatitis

OBJECTIVES

To evaluate alterations of the intestinal bacteria and its associations with the inflammation in acute pancreatitis (AP).

METHODS

A multihospital prospective clinical study was conducted, and a total of 108 participants were enrolled in our study, including 44 with severe AP (SAP), 32 with mild AP (MAP), and 32 healthy volunteers. The structure of intestinal microbiota, 10 predominant bacteria, plasma endotoxin, and serum cytokines were investigated by polymerase chain reaction-denaturing gradient gel electrophoresis, real-time quantitative polymerase chain reaction, Limulus amebocyte lysate tests, and enzyme-linked immunosorbent assays, respectively.

RESULTS

Dramatic alterations in the predominant fecal microbiota were observed in most of both MAP and SAP patients. In addition, the rates of the multiorgan failures and infectious complications in the patients with SAP with altered intestinal microbiota were significantly higher than in those whose intestinal microbiota remained unaltered. Enterococcus increased and Bifidobacterium decreased in the patients with SAP compared to the patients with MAP. Serum IL-6 were positively correlated with Enterobacteriaceae and Enterococcus and negatively correlated with Bifidobacterium, whereas plasma endotoxin positively correlated with Enterococcus (P < 0.05).

CONCLUSIONS

The intestinal bacteria most frequently altered in both the patients with MAP and those with SAP significantly correlated with inflammation, which indicated that the intestinal microbiota may be involved in the progression of AP.

Alterations in the Fecal Microbiota of Patients with HIV-1 Infection: An Observational Study in A Chinese Population

The available evidence suggests that alterations in gut microbiota may be tightly linked to the increase in microbial translocation and systemic inflammation in patients with human immunodeficiency virus 1 (HIV-1) infection. We profiled the fecal microbiota as a proxy of gut microbiota by parallel barcoded 454-pyrosequencing in 67 HIV-1-infected patients (32 receiving highly active antiretroviral therapy [HAART] and 35 HAART naïve) and 16 healthy controls from a Chinese population. We showed that α-diversity indices did not differ significantly between the healthy control and HIV-1-infected patients. The ratio of Firmicutes/Bacteroidetes increased significantly in HIV-1-infected patients. Several key bacterial phylotypes, including Prevotella, were prevalent in HIV-1-infected patients; whereas Phascolarctobacterium, Clostridium XIVb, Dialister and Megamonas were significantly correlated with systemic inflammatory cytokines. After short-term, effective HAART, the viral loads of HIV-1 were reduced; however, the diversity and composition of the fecal microbiota were not completely restored. and the dysbiosis remained among HIV-1-infected subjects undergoing HAART. Our detailed analysis demonstrated that dysbiosis of fecal microbiota might play an active role in HIV-1 infection. Thus, new insights may be provided into therapeutics that target the microbiota to attenuate the progression of HIV disease and to reduce the risk of gut-linked disease in HIV-1-infected patients.

Impacts of infection with different toxigenic Clostridium difficile strains on faecal microbiota in children

Increasing evidence suggests that altered intestinal microbial composition and function result in an increased risk of Clostridium difficile-associated diarrhoea (CDAD); however, the specific changes of intestinal microbiota in children suffering from CDAD and their associations with C. difficile strain toxigenicity are poorly understood. High-throughput pyrosequencing showed that reduced faecal bacterial diversity and dramatic shifts of microbial composition were found in children with CDAD. The Firmicutes/Bacteroidetes ratio was increased significantly in patients with CDAD, which indicated that dysbiosis of faecal microbiota was closely associated with CDAD. C. difficile infection resulted in an increase in lactate-producing phylotypes, with a corresponding decrease in butyrate-producing bacteria. The decrease in butyrate and lactate buildup impaired intestinal colonisation resistance, which increased the susceptibility to C. difficile colonisation. Strains of C. difficile which were positive for both toxin A and toxin B reduced faecal bacterial diversity to a greater degree than strains that were only toxin B-positive, and were associated with unusually abundant Enterococcus, which implies that the C. difficile toxins have different impacts on the faecal microbiota of children. Greater understanding of the relationships between disruption of the normal faecal microbiota and colonisation with C. difficile that produces different toxins might lead to improved treatment.

Gut microbiota and aging

Aging is characterized by the functional decline of tissues and organs and increased risk of aging-associated disorders, which pose major societal challenges and are a public health priority. Despite extensive human genetics studies, limited progress has been made linking genetics with aging. There is a growing realization that the altered assembly, structure and dynamics of the gut microbiota actively participate in the aging process. Age-related microbial dysbiosis is involved in reshaping immune responses during aging, which manifest as immunosenescence (insufficiency) and inflammaging (over-reaction) that accompany many age-associated enteric and extraenteric diseases. The gut microbiota can be regulated, suggesting a potential target for aging interventions. This review summarizes recent findings on the physiological succession of gut microbiota across the life-cycle, the roles and mechanisms of gut microbiota in healthy aging, alterations of gut microbiota and aging-associated diseases, and the gut microbiota-targeted anti-aging strategies.

Structural and Functional Dysbiosis of Fecal Microbiota in Chinese Patients With Alzheimer's Disease

Increasing evidence suggests that gut dysbiosis plays vital roles in a variety of gut-brain disorders, such as Alzheimer's disease (AD). However, alterations of the gut microbiota as well as their correlations with cognitive scores and host immunity have remained unclear in well-controlled trials on Chinese AD patients. In this study, samples from 100 AD patients, and 71 age- and gender-matched, cognitively normal controls were obtained to explore the structural and functional alterations of the fecal microbiota targeting the V3-V4 region of the 16S rRNA gene by MiSeq sequencing, and to analyze their associations with clinical characteristics. Our data demonstrated a remarkably reduction in the bacterial diversity and alterations in the taxonomic composition of the fecal microbiota of the AD patients. Interestingly, the abundant butyrate-producing genera such as Faecalibacterium decreased significantly, where this was positively correlated with such clinical indicators as the MMSE, WAIS, and Barthel scores in the AD patients. On the contrary, abundant lactate-producing genera, such as Bifidobacterium, increased prominently, and were inversely correlated with these indicators. This shift in the gut dysbiosis of the microbiota, from being butyrate producers to lactate producers, contributed to immune disturbances in the host that could be used as non-invasive biomarkers to distinguish the controls from the AD patients. Moreover, several predicted functional modules, including the biosynthesis and the metabolism of fatty acids, that were altered in the microbiota of the AD patients could be utilized by the bacteria to produce immunomodulatory metabolites. Our study established the structural and functional dysbiosis of fecal microbiota in AD patients, and the results suggest the potential for use of gut bacteria for the early, non-invasive diagnosis of AD, personalized treatment, and the development of tailor-made probiotics designed for Chinese AD patients.

Contribution of Lactobacillus iners to Vaginal Health and Diseases: A Systematic Review

Lactobacillus iners, first described in 1999, is a prevalent bacterial species of the vaginal microbiome. As L. iners does not easily grow on de Man-Rogosa-Sharpe agar, but can grow anaerobically on blood agar, it has been initially overlooked by traditional culture methods. It was not until the wide application of molecular biology techniques that the function of L. iners in the vaginal microbiome was carefully explored. L. iners has the smallest genome among known Lactobacilli and it has many probiotic characteristics, but is partly different from other major vaginal Lactobacillus species, such as L. crispatus, in contributing to the maintenance of a healthy vaginal microbiome. It is not only commonly present in the healthy vagina but quite often recovered in high numbers in bacterial vaginosis (BV). Increasing evidence suggests that L. iners is a transitional species that colonizes after the vaginal environment is disturbed and offers overall less protection against vaginal dysbiosis and, subsequently, leads to BV, sexually transmitted infections, and adverse pregnancy outcomes. Accordingly, under certain conditions, L. iners is a genuine vaginal symbiont, but it also seems to be an opportunistic pathogen. Further studies are necessary to identify the exact role of this intriguing species in vaginal health and diseases.

Clostridium butyricum attenuates cerebral ischemia/reperfusion injury in diabetic mice via modulation of gut microbiota

Diabetes is known to exacerbate cerebral ischemia/reperfusion (I/R) injury. Here, we investigated the effects of Clostridium butyricum on cerebral I/R injury in the diabetic mice subjected to 30min of bilateral common carotid arteries occlusion (BCCAO). The cognitive impairment, the blood glucose level, neuronal injury, apoptosis, and expressions of Akt, phospho-Akt (p-Akt), and caspase-3 level were assessed. Meanwhile, the changes of gut microbiota in composition and diversity in the colonic feces were evaluated. Our results showed that diabetic mice subjected to BCCAO exhibited worsened cognitive impairment, cell damage and apoptosis. These were all attenuated by C. butyricum. Moreover, C. butyricum reversed cerebral I/R induced decreases in p-Akt expression and increases in caspase-3 expression, leading to inhibiting neuronal apoptosis. C. butyricum partly restored cerebral I/R induced decreases of fecal microbiota diversity, changes of fecal microbiota composition. Together, these findings highlight the important role of bacteria in the bidirectional communication of the gut-brain axis and suggest that certain probiotics might prove to be useful therapeutic adjuncts in cerebral I/R injury with diabetes.

Pyrosequencing analysis of oral microbiota shifting in various caries states in childhood

Dental caries is one of the most prevalent childhood diseases worldwide, but little is known about the dynamic characteristics of oral microbiota in the development of dental caries. To investigate the shifting bacterial profiles in different caries states, 60 children (3-7-year-old) were enrolled in this study, including 30 caries-free subjects and 30 caries-active subjects. Supragingival plaques were collected from caries-active subjects on intact enamel, white spot lesions and carious dentin lesions. Plaques from caries-free subjects were used as a control. All samples were analyzed by 454 pyrosequencing based on 16S rRNA gene V1-V3 hypervariable regions. A total of 572,773 pyrosequencing reads passed the quality control and 25,444 unique phylotypes were identified, which represented 18 phyla and 145 genera. Reduced bacterial diversity in the cavitated dentin was observed as compared with the other groups. Thirteen genera (including Capnocytophaga, Fusobacterium, Porphyromonas, Abiotrophia, Comamonas, Tannerella, Eikenella, Paludibacter, Treponema, Actinobaculum, Stenotrophomonas, Aestuariimicrobium, and Peptococcus) were found to be associated with dental health, and the bacterial profiles differed considerably depending on caries status. Eight genera (including Cryptobacterium, Lactobacillus, Megasphaera, Olsenella, Scardovia, Shuttleworthia, Cryptobacterium, and Streptococcus) were increased significantly in cavitated dentin lesions, and Actinomyces and Corynebacterium were present at significant high levels in white spot lesions (P < 0.05), while Flavobacterium, Neisseria, Bergeyella, and Derxia were enriched in the intact surfaces of caries individuals (P < 0.05). Our results showed that oral bacteria were specific at different stages of caries progression, which contributes to informing the prevention and treatment of childhood dental caries.

Fructooligosaccharides Ameliorating Cognitive Deficits and Neurodegeneration in APP/PS1 Transgenic Mice through Modulating Gut Microbiota

Alzheimer's disease (AD) is closely related to gut microbial alteration. Prebiotic fructooligosaccharides (FOS) play major roles by regulating gut microbiota. The present study aimed to explore the effect and mechanism of FOS protection against AD via regulating gut microbiota. Male Apse/PSEN 1dE9 (APP/PS1) transgenic (Tg) mice were administrated with FOS for 6 weeks. Cognitive deficits and amyloid deposition were evaluated. The levels of synaptic plasticity markers including postsynaptic density protein 95 (PSD-95) and synapsin I, as well as phosphorylation of c-Jun N-terminal kinase (JNK), were determined. The intestinal microbial constituent was detected by 16S rRNA sequencing. Moreover, the levels of glucagon-like peptide-1 (GLP-1) in the gut and GLP-1 receptor (GLP-1R) in the brain were measured. The results indicated that FOS treatment ameliorated cognitive deficits and pathological changes in the Tg mice. FOS significantly upregulated the expression levels of synapsin I and PSD-95, as well as decreased phosphorylated level of JNK. The sequencing results showed that FOS reversed the altered microbial composition. Furthermore, FOS increased the level of GLP-1 and decreased the level of GLP-1R in the Tg mice. These findings indicated that FOS exerted beneficial effects against AD via regulating the gut microbiota-GLP-1/GLP-1R pathway.

Changes of gut bacteria and immune parameters in liver transplant recipients

BACKGROUND

Liver transplantation is one of the most effective therapeutic options for patients with end-stage liver diseases, and gut microbiota is actively involved in potential infections in pretransplant and posttransplant patients. However, the diversity of gut microbiota and its relationship with the immune parameter of liver transplantation recipients are not well understood.

METHODS

We collected fresh feces and blood samples from 190 participants in China from November 2004 to May 2008, including 28 healthy volunteers, 51 cirrhotic patients and 111 liver-transplanted patients. Six interesting gut bacteria, plasma endotoxin, serum cytokines (i.e., tumor necrosis factor alpha and interleukin-6) and fecal secretory IgA (SIgA) were investigated by real-time quantitative PCR, chromogenic limulus amoebocyte assay, sandwich-type enzyme-linked immunosorbent assay and radioimmunoassay, respectively.

RESULTS

All Eubacteria, Bifidobacterium spp., Faecalibacterium prausnitzii and Lactobacillus spp. were significantly lower in the liver transplantation recipients while Enterobacteriaceae and Enterococcus spp. were significantly higher (P<0.05). Except for Enterococcus spp., other bacteria showed a tendency to restore to normal level along with the time after liver transplantation. Plasma endotoxin, interleukin-6 and fecal SIgA in cirrhotic patients increased significantly, but not in liver transplantation recipients. Plasma endotoxin and interleukin-6 were negatively correlated with all Eubacteria and the Bacteroides-Prevotella group, while tumor necrosis factor alpha was not significantly correlated with these six gut bacteria in cirrhotic patients.

CONCLUSIONS

Our study demonstrates that abundant gut bacteria were altered significantly in both cirrhotic and liver transplantation patients, while plasma endotoxin and interleukin-6 increased remarkably in cirrhotic patients, showing significant correlations with gut microbiota. Interestingly, our data show a tendency for these gut bacteria to restore to normal levels in liver transplantation recipients.