The gut microbiota of nonalcoholic fatty liver disease: current methods and their interpretation. Hepatol Int. 2015;9:406-415. [PMID: 26067771 PMCID: PMC4473019 DOI: 10.1007/s12072-015-9640-2]

The Intestinal Microbiota in the Development of Chronic Liver Disease: Current Status

Chronic liver disease (CLD) is a significant global health burden, leading to millions of deaths annually. The gut-liver axis plays a pivotal role in this context, allowing the transport of gut-derived products directly to the liver, as well as biological compounds from the liver to the intestine. The gut microbiota plays a significant role in maintaining the health of the digestive system. A change in gut microbiome composition as seen in dysbiosis is associated with immune dysregulation, altered energy and gut hormone regulation, and increased intestinal permeability, contributing to inflammatory mechanisms and damage to the liver, irrespective of the underlying etiology of CLD. The aim of this review is to present the current knowledge about the composition of the intestinal microbiome in healthy individuals and those with CLD, including the factors that affect this composition, the impact of the altered microbiome on the liver, and the mechanisms by which it occurs. Furthermore, this review analyzes the effects of gut microbiome modulation on the course of CLD, by using pharmacotherapy, nutrition, fecal microbiota transplantation, supplements, and probiotics. This review opens avenues for the translation of knowledge about gut-liver interplay into clinical practice as an additional tool to fight CLD and its complications.

Hypoglycemic effect of astragaloside IV via modulating gut microbiota and regulating AMPK/SIRT1 and PI3K/AKT pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Radix Astragali, the dried root of Astragalus mongholicus Bunge, has long been used in traditional Chinese Medicine to treat diabetes. Astragaloside IV (AS-IV), one of the most active ingredients in the root, has been shown to have anti-diabetes ability; however, its underlying mechanism is still unclear.

MATERIALS AND METHODS

In this study, we evaluated the hypoglycemic effect and possible mechanisms of AS-IV in diabetic mice and insulin resistance-HepG2 cells. The components of the intestinal microflora in mice with type 2 diabetes mellitus (T2DM) were determined using high-throughput 16S rRNA gene sequencing. Moreover, the molecular mechanisms of specific members of insulin signaling pathways were analyzed.

RESULTS

AS-IV significantly reversed the abnormalities in blood lipids, glucose, insulin resistance, as well as oxidative stress levels in T2DM mice. Histological finding showed that AS-IV could protect the cellular architecture of the liver and pancreas. AS-IV also regulated the abundance and diversity of intestinal flora of T2DM mice in a positive direction and increased butyric acid levels. The active role of AS-IV as an anti-diabetic compound by regulating the AMPK/SIRT1 and PI3K/AKT signaling pathways was revealed using a T2DM model and verified through the intervention of inhibitors using insulin-resistance HepG2 cells.

CONCLUSION

Our results suggested that AS-IV may be used as an anti-diabetic drug candidate owing to its effects of regulating gut microbiota and AMPK/SIRT1 and PI3K/AKT signaling pathways.

Metabolic associated fatty liver disease and acute-on-chronic liver failure: common themes for common problems

Metabolic associated fatty liver disease (MAFLD) affects 20-30% of the worldwide population and is becoming the most common cause of chronic liver disease, cirrhosis and hepatocellular carcinoma (HCC). MAFLD is the hepatic expression of metabolic dysfunction correlated with a variety of metabolic comorbidities including obesity, dyslipidemia, hypertension and type 2 diabetes (T2DM). Obesity, altered gut permeability, chronic inflammation and dysbiosis related to MAFLD might predispose patients with cirrhosis to the development of acute-on-chronic liver failure (ACLF); however, this relationship remains unclear. ACLF is a syndrome with high short-term mortality, presenting with acute hepatic decompensation associated with organ failures in patients with underlying chronic liver disease with or without an identifiable precipitating event. While this syndrome can occur in any patient with cirrhosis, the increasing prevalence of cirrhosis due to MAFLD is of great concern because, in a recent analysis, MAFLD was the fastest rising cause of cirrhosis associated with ACLF among patients listed for LT in the US. In this review, we will discuss the current knowledge on MAFLD and the development of ACLF.

Akkermansia muciniphila – obiecujący kandydat na probiotyk nowej generacji

W ostatnich czasach można zaobserwować duży wzrost zainteresowania relacjami między człowiekiem a mikroorganizmami zasiedlającymi jego organizm. Licznie występują w oraz na ciele człowieka, a ich liczba przekracza liczbę komórek ludzkiego organizmu. Udoskonalenie technik badawczych pozwala lepiej zrozumieć molekularne podłoże tych oddziaływań, co być może pozwoli na wykorzystanie w terapiach tych mikroorganizmów, które korzystnie wpływają na organizm człowieka. W artykule podsumowano dotychczasową wiedzę na temat fizjologii licznie występującej w przewodzie pokarmowym bakterii Akkermansia muciniphila i jej wpływu na organizm gospodarza. Opisano właściwości A. muciniphila, jej funkcjonowanie w środowisku przewodu pokarmowego oraz relacje (zarówno antagonistyczne jak i symbiotyczne) z innymi tam bytującymi mikroorganizmami. Przedstawiono także mechanizmy oddziaływania A. muciniphila na barierę jelitową, układ immunologiczny oraz metabolizm energetyczny gospodarza. Ponadto opisano jej rolę w patogenezie i terapii chorób, w tym m.in. cukrzycy typu 2, nieswoistego zapalenia jelit, zaburzeń neurologicznych, astmy, a także jej wpływ na odpowiedź pacjenta na terapie przeciwnowotworowe oparte na działaniu układu odpornościowego. Duże zainteresowanie tą bakterią, a także przytoczone wyniki badań, w tym tych sprawdzających bezpieczeństwo jej stosowania, wskazują, że A. muciniphila może być obiecującym kandydatem na probiotyk nowej generacji. Niewątpliwie jednak przed dopuszczeniem A. muciniphila do powszechnego stosowania konieczne są dalsze badania z udziałem ludzi, a także wnikliwa ocena bezpieczeństwa jej stosowania.

Dietary bile acid supplementation reveals beneficial effects on intestinal healthy status of tongue sole (Cynoglossus semiliaevis)

The aim of this study was to investigate the effects of dietary bile acids (BAs) on intestinal healthy status of tongue sole in terms of immunity, antioxidant status, digestive ability, mucosal barrier-related genes expression and microbiota. Three experimental diets were prepared with BA levels at 0 mg/kg (CT), 300 mg/kg (BA1) and 900 mg/kg (BA2) in a commercial basal diet. Each diet was fed to three replicates with 120 fish (10.87 ± 0.32 g) in each tank. After an 8-week feeding trial, growth parameters were significantly enhanced in both BAs supplementary groups (P < 0.05), and compared with CT group, survival rate in BA2 group was significantly improved (P < 0.05). Intestinal lysozyme activity and contents of immunoglobulin M and complement 3 were significantly increased in both BAs supplementary groups (P < 0.05), suggesting an enhancement effect on the non-specific immune response. BAs inclusion also significantly improved intestinal antioxidant capabilities by increasing antioxidase activities and decreasing malondialdehyde levels. In addition, compared with CT group, intestinal digestive ability was substantially enhanced as indicated by the significantly increased lipase activity in BA2 group (P < 0.05) and significantly increased amylase activity in BA1 and BA2 groups (P < 0.05). Coincidentally, BAs inclusion significantly upregulated the relative expression of intestinal mucosal barrier-related genes (P < 0.05). Further, dietary BAs distinctly remodeled intestinal microbiota by decreased the abundance of some potential pathogenic bacteria. In conclusion, dietary BAs supplementation is an effective way to improve the intestinal healthy status of tongue sole.

Impact of short-term overfeeding of saturated or unsaturated fat or sugars on the gut microbiota in relation to liver fat in obese and overweight adults

BACKGROUNDS & AIMS

Intestinal microbiota may be causally involved in the pathogenesis of non-alcoholic fatty liver disease (NAFLD). We aimed to study the effect of short-term overfeeding on human gut microbiota in relation to baseline and overfeeding-induced liver steatosis. We also asked whether the baseline microbiota composition is associated to the overfeeding-induced increase in liver fat.

METHODS

In a randomized trial, 38 overweight and obese subjects were assigned to consume an excess of 1000 kcal/day of diets rich in either saturated fat, unsaturated fat, or simple sugars for 3 weeks. Fasting blood samples and ¹H-MR spectroscopy were used for extensive clinical phenotyping as previously reported (PMID: 29844096). Fecal samples were collected for the analysis of the gut microbiota using 16S rRNA amplicon sequencing, imputed metagenomics and qPCR. Microbiota results were correlated with dietary intakes and clinical measurements before and during overfeeding.

RESULTS

The overall community structure of the microbiota remained highly stable and personalized during overfeeding based on between-sample Bray-Curtis dissimilarity, but the relative abundances of individual taxa were altered in a diet-specific manner: overfeeding saturated fat increased Proteobacteria, while unsaturated fat increased butyrate producers. Sugar overfeeding increased Lactococcus and Escherichia coli. Imputed functions of the gut microbiota were not affected by overfeeding. Several taxa affected by overfeeding significantly correlated with the changes in host metabolic markers. The baseline levels of proteobacterial family Desulfovibrionaceae, and especially genus Bilophila, were significantly associated to overfeeding-induced liver fat increase independently of the diet arm. In general, limited overlap was observed between the overfeeding-induced microbiota changes and the liver fat-associated microbiota features at baseline.

CONCLUSIONS

Our work indicates that the human gut microbiota is resilient to short-term overfeeding on community level, but specific taxa are altered on diet composition-dependent manner. Generalizable microbiota signatures directly associated with liver steatosis could not be identified. Instead, the carriage of Bilophila was identified as a potential novel risk factor for diet-induced liver steatosis in humans. Clinical trial registry number: NCT02133144 listed on NIH website: ClinicalTrials.gov.

Gut microbiota in non-alcoholic fatty liver disease and alcohol-related liver disease: Current concepts and perspectives

The term, gut-liver axis, is used to highlight the close anatomical and functional relationship between the intestine and the liver. It has been increasingly recognized that the gut-liver axis plays an essential role in the development and progression of liver disease. In particular, in non-alcoholic fatty liver disease and alcohol-related liver disease, the two most common causes of chronic liver disease, a dysbiotic gut microbiota can influence intestinal permeability, allowing some pathogens or bacteria-derived factors from the gut reaching the liver through the enterohepatic circulation contributing to liver injury, steatohepatitis, and fibrosis progression. Pathways involved are multiple, including changes in bile acid metabolism, intestinal ethanol production, generation of short-chain fatty acids, and other by-products. Bile acids act through dedicated bile acid receptors, farnesoid X receptor and TGR5, in both the ileum and the liver, influencing lipid metabolism, inflammation, and fibrogenesis. Currently, both non-alcoholic fatty liver disease and alcohol-related liver disease lack effective therapies, and therapeutic targeting of gut microbiota and bile acids enterohepatic circulation holds promise. In this review, we summarize current knowledge about the role of gut microbiota in the pathogenesis of non-alcoholic fatty liver disease and alcohol-related liver disease, as well as the relevance of microbiota or bile acid-based approaches in the management of those liver diseases.

Function of Akkermansia muciniphila in Obesity: Interactions With Lipid Metabolism, Immune Response and Gut Systems

Obesity and its metabolic syndrome, including liver disorders and type 2 diabetes, are a worldwide epidemic and are intimately linked to diet. The gut microbiota interaction has been pointed to as a hot topic of research in the treatment of obesity and related metabolic diseases by influencing energy metabolism and the immune system. In terms of the novel beneficial microbes identified, Akkermansia muciniphila (A. muciniphila) colonizes the mucosa layer of the gut and modulates basal metabolism. A. muciniphila is consistently correlated with obesity. The causal beneficial impact of A. muciniphila treatment on obesity is coming to light, having been proved by a variety of animal models and human studies. A. muciniphila has been characterized as a beneficial player in body metabolism and has great prospects for treatments of the metabolic disorders associated with obesity, as well as being considered for next-generation therapeutic agents. This paper aimed to investigate the basic mechanism underlying the relation of A. muciniphila to obesity and its host interactions, as identified in recent discoveries, facilitating the establishment of the causal relationship in A. muciniphila-associated therapeutic supplement in humans.

Role of gut microbiota in liver disease

The gut microbiome is the natural intestinal inhabitant that has been recognized recently as a major player in the maintenance of human health and the pathophysiology of many diseases. Those commensals produce metabolites that have various effects on host biological functions. Therefore, alterations in the normal composition or diversity of microbiome have been implicated in various diseases, including liver cirrhosis and nonalcoholic fatty liver disease. Moreover, accumulating evidence suggests that progression of dysbiosis can be associated with worsening of liver disease. Here, we review the possible roles for gut microbiota in the development, progression, and complication of liver disease.

Dietary fiber and chicken microbiome interaction: Where will it lead to?

The last few decades have been marked by a rapid genetic improvement in chicken growth rates. The modern-day chicken is more efficient in converting feed into muscle mass than their predecessors. This enhanced efficiency emanates from better nutrient digestion, absorption, and metabolism. The gut has therefore become a research focus especially after the ban on the use of antibiotics as growth promoters (AGP) in poultry. In pursuance of better gut health in the post-AGP era, many different strategies are being continuously sought and tested. The gut is inhabited by more than 900 bacterial species along with fungi and archaea, and they play an important role to maintain a conducive milieu for the host. A beneficial shift in the microbial ecosystem of the chicken can be promoted by many dietary and non-dietary interventions, however, diet is ranked as one of the most important and potent regulators of gut microbiota composition. Therefore, the constituents of the diet warrant special attention in the modulation of the gut ecosystem. Among dietary constituents, fiber possesses a significant ability to modulate the microbiota. In this review, we will highlight the importance of fiber in poultry nutrition and will also discuss the effects of fiber on gut microbiota and its resultant ramifications on the liver and brain.

Gut Microbiota Profiles in Nonalcoholic Fatty Liver Disease and Its Possible Impact on Disease Progression Evaluated with Transient Elastography: Lesson Learnt from 60 Cases

BACKGROUND

Dysbiosis of the gut microbiota has been considered to have a role in nonalcoholic fatty liver disease (NAFLD) progression. However, there is still lack of studies regarding this phenomenon.

AIM

To find the difference in the proportion of gut microbiota in NAFLD patients based on the stages of liver fibrosis.

PATIENTS AND METHODS

A cross-sectional study was conducted at Dr. Cipto Mangunkusumo Hospital, which is the largest tertiary referral center. Human fecal samples from NAFLD patients who came to the outpatient clinic were collected consecutively. The stool sample examination was performed using an isolation DNA kit (Tiangen) and quantitative real-time polymerase chain reaction (Fast 7500). Clinical and laboratory data were also collected. The stage of fibrosis was diagnosed based on transient elastography (FibroScan® 502 Touch; Echosens, France).

RESULTS

Of 60 NAFLD human fecal samples, 35 patients had nonsignificant fibrosis and 25 patients had significant fibrosis (46.7% male and 53.3% female; median age 56 years). Most patients had diabetes (85%), dyslipidemia (58.3%), obesity (58.3%), and central obesity (90%). The proportion of Bacteroides was higher when compared to Lactobacillus and Bifidobacteria. Of these 3 microbiota, the proportion of Bacteroides was significantly higher in the significant fibrosis group when compared to the nonsignificant fibrosis group.

CONCLUSION

There is a change in the composition of gut microbiota in NAFLD patients. The proportion of Bacteroides is significantly higher in significant liver fibrosis, which may play a role in NAFLD progression.

Digestion under saliva, simulated gastric and small intestinal conditions and fermentation in vitro of polysaccharides from the flowers of Camellia sinensis induced by human gut microbiota

In the present study, digestion under saliva, simulated gastric and small intestinal conditions and fermentation in vitro of polysaccharides from the flowers of Camellia sinensis (TFPS) by human gut microbiota were investigated. The results indicated that human saliva and simulated gastric and intestinal juices had no effect on TFPS, while TFPS could be utilized by human fecal microbiota, which was proved from the decreased molecular weight and lower content of total or reducing sugars after fermentation under anaerobic conditions. It was found that pH in the fermentation system decreased, and the production of short-chain fatty acids was significantly enhanced. Furthermore, in vitro fermentation of TFPS altered the composition of gut microbiota, specifically in elevating the ratio of Bacteroidetes to Firmicutes and enriching Prevotella. The present results suggest that TFPS has the potential to be developed as functional foods to modify gut microbiota.

The Association of Gut Microbiota with Nonalcoholic Steatohepatitis in Thais

Objectives

Nonalcoholic steatohepatitis (NASH) can progress to advanced fibrosis; the link between intestinal bacterial overgrowth and NASH has been proposed. Gut microbiota may promote inflammation and provoke disease progression. We evaluated gut microbiota pattern in NASH and its influencing factors.

Methods

A case-controlled study with sixteen NASH and eight control subjects was done. We performed DNA extraction from stool samples and bacterial 16S rRNA sequencing using MiSeq™. The sequences were clustered into operational taxonomic units using Quantitative Insights Into Microbial Ecology software. We calculated relative abundances, determined alpha diversity, obtained beta diversity by principal coordinate analysis, and conducted the partial least-squares regression model.

Results

The relative abundance of Bacteroidetes tended to be higher in NASH group. The Bacteroidetes/Firmicutes (B/F) ratio was significantly elevated in NASH patients. The pattern of gut microbiota in NASH was clearly separated from that of control subjects. Factors influencing the separation of NASH from control subjects were age, diabetes, body mass index, Bacteroidetes phylum, metformin, Actinobacteria, Verrucomicrobia, Thermotogae, and Caldithrix and Bacteroidetes/Firmicutes ratio.

Conclusions

Bacteroidetes phylum (Bacteroides and Prevotella genus) is abundant in NASH subjects, who exhibited an elevated B/F ratio. NASH patients showed a specific pattern of gut microbiota independent of diabetes or metformin use.

Flos Lonicera Combined with Metformin Ameliorates Hepatosteatosis and Glucose Intolerance in Association with Gut Microbiota Modulation

The gut microbiota is important in energy contribution, metabolism and immune modulation, and compositional disruption of the gut microbiota population is closely associated with chronic metabolic diseases like type 2 diabetes (T2D) and non-alcoholic fatty liver disease (NAFLD). Metformin (MET) and Flos Lonicera (FL) are common treatments for metabolic diseases in Western and Oriental medicinal fields. We evaluated the effect of treatment with FL and MET in combination on hepatosteatosis, glucose tolerance, and gut microbial composition. FL and MET were administered to Otsuka Long-Evans Tokushima Fatty (OLETF) rats, an animal model of genetic T2D and NAFLD. The FL+MET treatment reduced liver weight, serum cholesterol, insulin resistance, and hepatic MDA level and modulated the gut microbial composition. More specifically, the genera of Prevotella and Lactobacillus were negatively associated with the body and liver weights, hepatic TG and TC content, and serum insulin level. However, the relative abundance of these genera decreased in response to the FL+MET treatment. Interestingly, pathway prediction data revealed that the FL+MET treatment attenuated lipopolysaccharide-related pathways, in keeping with the decrease in serum and fecal endotoxin levels. FL and MET in combination exerts a synergistic effect on the improvement of hepatosteatosis and insulin sensitivity in OLETF rats, and modulates gut microbiota in association with the effect.

A synbiotic composed of Lactobacillus fermentum CECT5716 and FOS prevents the development of fatty acid liver and glycemic alterations in rats fed a high fructose diet associated with changes in the microbiota

We investigated the effect of a high fructose diet (HFD) on Sprague Dawley rats and the impact of a synbiotic composed of Lactobacillus fermentum CECT5716 and fructooligosaccharides. Feeding the HFD for 5 weeks resulted in liver steatosis and insulin resistance but not obesity. These changes were associated with increased production of short-chain fatty acids and increased Bacteroidetes in feces, with an augmented Bacteroidetes/Firmicutes ratio, among other changes in the microbiota. In addition, barrier function was weakened, with increased LPS plasma levels. These data are consistent with increased fructose availability in the distal gut due to saturation of absorptive mechanisms, leading to dysbiosis, endotoxemia, hepatic steatosis, and insulin resistance. Treatment with the synbiotic prevented some of the pathological effects, so that treated rats did not develop steatosis or systemic inflammation, while dysbiosis and barrier function were greatly ameliorated. In addition, the synbiotic had hypolipidemic effects. The synbiotic composed by L. fermentum CECT5716 and fructooligosaccharides has beneficial effects in a model of metabolic syndrome induced by a HFD, suggesting it might be clinically useful in this type of condition, particularly considering that high fructose intake has been related to metabolic syndrome in humans.

Gut-liver axis, cirrhosis and portal hypertension: the chicken and the egg

The term gut-liver axis is used to highlight the close anatomical and functional relationship between the intestine and the liver. The intestine has a highly specialized epithelial membrane which regulates transport across the mucosa. Due to dysbiosis, impairment of the intestinal barrier and altered immunity status, bacterial products can reach the liver through the portal vein, where they are recognized by specific receptors, activate the immune system and lead to a proinflammatory response. Gut microbiota and bacterial translocation play an important role in the pathogenesis of chronic liver diseases, including alcoholic and non-alcoholic fatty liver disease, cirrhosis, and its complications, such as portal hypertension, spontaneous bacterial peritonitis and hepatic encephalopaty. The gut microbiota also plays a critical role as a modulator of bile acid metabolism which can also influence intestinal permeability and portal hypertension through the farnesoid-X receptor. On the other hand, cirrhosis and portal hypertension affect the microbiota and increase translocation, leading to a "chicken and egg" situation, where translocation increases portal pressure, and vice versa. A myriad of therapies targeting gut microbiota have been evaluated specifically in patients with chronic liver disease. Further studies targeting intestinal microbiota and its possible hemodynamic and metabolic effects are needed. This review summarizes the current knowledge about the role of gut microbiota in the pathogenesis of chronic liver diseases and portal hypertension.

PBHMDA: Path-Based Human Microbe-Disease Association Prediction

With the advance of sequencing technology and microbiology, the microorganisms have been found to be closely related to various important human diseases. The increasing identification of human microbe-disease associations offers important insights into the underlying disease mechanism understanding from the perspective of human microbes, which are greatly helpful for investigating pathogenesis, promoting early diagnosis and improving precision medicine. However, the current knowledge in this domain is still limited and far from complete. Here, we present the computational model of Path-Based Human Microbe-Disease Association prediction (PBHMDA) based on the integration of known microbe-disease associations and the Gaussian interaction profile kernel similarity for microbes and diseases. A special depth-first search algorithm was implemented to traverse all possible paths between microbes and diseases for inferring the most possible disease-related microbes. As a result, PBHMDA obtained a reliable prediction performance with AUCs (The area under ROC curve) of 0.9169 and 0.8767 in the frameworks of both global and local leave-one-out cross validations, respectively. Based on 5-fold cross validation, average AUCs of 0.9082 ± 0.0061 further demonstrated the efficiency of the proposed model. For the case studies of liver cirrhosis, type 1 diabetes, and asthma, 9, 7, and 9 out of predicted microbes in the top 10 have been confirmed by previously published experimental literatures, respectively. We have publicly released the prioritized microbe-disease associations, which may help to select the most potential pairs for further guiding the experimental confirmation. In conclusion, PBHMDA may have potential to boost the discovery of novel microbe-disease associations and aid future research efforts toward microbe involvement in human disease mechanism. The code and data of PBHMDA is freely available at http://www.escience.cn/system/file?fileId=85214.

Bile acids and nonalcoholic fatty liver disease: Molecular insights and therapeutic perspectives

Nonalcoholic fatty liver disease (NAFLD) is a burgeoning health problem worldwide and an important risk factor for both hepatic and cardiometabolic mortality. The rapidly increasing prevalence of this disease and of its aggressive form nonalcoholic steatohepatitis (NASH) will require novel therapeutic approaches to prevent disease progression to advanced fibrosis or cirrhosis and cancer. In recent years, bile acids have emerged as relevant signaling molecules that act at both hepatic and extrahepatic tissues to regulate lipid and carbohydrate metabolic pathways as well as energy homeostasis. Activation or modulation of bile acid receptors, such as the farnesoid X receptor and TGR5, and transporters, such as the ileal apical sodium-dependent bile acid transporter, appear to affect both insulin sensitivity and NAFLD/NASH pathogenesis at multiple levels, and these approaches hold promise as novel therapies. In the present review, we summarize current available data on the relationships of bile acids to NAFLD and the potential for therapeutically targeting bile-acid-related pathways to address this growing world-wide disease. (Hepatology 2017;65:350-362).

Relationship between gut microbiota and non-alcoholic fatty liver disease

The incidence of non-alcoholic fatty liver disease (NAFLD) has been increasing during these years. As we understand more about gut microbiota, the relationship between gut microbiota and NAFLD has been revealed. Both animal experiments and clinical studies show that gut microbiota can not only act on NAFLD via the gut-liver axis and two-hit theory, but also play an important role in liver inflammation and hepatic fibrosis. Experiments also indicate that using probiotics, prebiotics, berberine and antibiotics to regulate gut microbiota can relieve inflammation, lower body mass index and improve insulin resistance, which can be a new treatment for NAFLD and other metabolic diseases.

Study of enteropathogenic bacteria in children with acute diarrhoea aged from 7 to 10 years in Xuzhou, China

BACKGROUND

Acute diarrhoea is a common infectious disease among children in many countries and it has different kinds of clinical symptoms including vomiting, abdominal cramps, or fever of 38 °C. Some specific intestinal bacteria and their quantities can result in relevant symptoms.

AIM

To analyze the correspondence between enteropathogenic bacteria and acute diarrhoea at family-level using high-throughput sequencing approach.

METHODS

Every 30 children of acute diarrhoea with abdominal cramps, vomiting, and fever of 38 °C was regarded as a group, respectively. Stools samples were collected from each group and the DNA of stool was examined by E.Z.N.A.(®) Stool DNA Kit. The 16S rRNA genes sequencing was performed on an Illumina Miseq platform.

FINDINGS

The sequencing dataset comprised 65,092 valid reads sequences that affiliated to the 18 phylogenetic families. The four dominant taxonomic groups in all three samples were Streptococcaceae, Veillonellaceae, Enterobacteriaceae and Lactobacillaceae. The stools of children with high fever presented higher pathogenic bacterial diversities and more complex community structures than other two groups. Lactobacillaceae was the enteric predominant microflora that could reduce the severity of acute diarrhoea.

CONCLUSION

The reduction of predominant microflora or the aberrant proliferation of sub-dominant microflora can break the intestinal operation mechanism and cause intestinal diseases. What's more, people's living habits are also correlative about acute diarrhoea and parents should prepare light food for their children in order to protect their tender gastrointestinal mucosa.

Gastrointestinal dysbiosis and the use of fecal microbial transplantation in Clostridium difficile infection

The impact of antibiotics on the human gut microbiota is a significant concern. Antibiotic-associated diarrhea has been on the rise for the past few decades with the increasing usage of antibiotics. Clostridium difficile infections (CDI) have become one of the most prominent types of infectious diarrheal disease, with dramatically increased incidence in both the hospital and community setting worldwide. Studies show that variability in the innate host response may in part impact upon CDI severity in patients. That being said, CDI is a disease that shows the most prominent links to alterations to the gut microbiota, in both cause and treatment. With recurrence rates still relatively high, it is important to explore alternative therapies to CDI. Fecal microbiota transplantation (FMT) and other types of bacteriotherapy have become exciting avenues of treatment for CDI. Recent clinical trials have generated excitement for the use of FMT as a therapeutic option for CDI; however, the exact components of the human gut microbiota needed for protection against CDI have remained elusive. Additional investigations on the effects of antibiotics on the human gut microbiota and subsequent CDI will help reduce the socioeconomic burden of CDI and potentially lead to new therapeutic modalities.

Gut Microbiota and Host Reaction in Liver Diseases

Although alcohol feeding produces evident intestinal microbial changes in animals, only some alcoholics show evident intestinal dysbiosis, a decrease in Bacteroidetes and an increase in Proteobacteria. Gut dysbiosis is related to intestinal hyperpermeability and endotoxemia in alcoholic patients. Alcoholics further exhibit reduced numbers of the beneficial Lactobacillus and Bifidobacterium. Large amounts of endotoxins translocated from the gut strongly activate Toll-like receptor 4 in the liver and play an important role in the progression of alcoholic liver disease (ALD), especially in severe alcoholic liver injury. Gut microbiota and bacterial endotoxins are further involved in some of the mechanisms of nonalcoholic fatty liver disease (NAFLD) and its progression to nonalcoholic steatohepatitis (NASH). There is experimental evidence that a high-fat diet causes characteristic dysbiosis of NAFLD, with a decrease in Bacteroidetes and increases in Firmicutes and Proteobacteria, and gut dysbiosis itself can induce hepatic steatosis and metabolic syndrome. Clinical data support the above dysbiosis, but the details are variable. Intestinal dysbiosis and endotoxemia greatly affect the cirrhotics in relation to major complications and prognosis. Metagenomic approaches to dysbiosis may be promising for the analysis of deranged host metabolism in NASH and cirrhosis. Management of dysbiosis may become a cornerstone for the future treatment of liver diseases.

Library preparation methodology can influence genomic and functional predictions in human microbiome research

Observations from human microbiome studies are often conflicting or inconclusive. Many factors likely contribute to these issues including small cohort sizes, sample collection, and handling and processing differences. The field of microbiome research is moving from 16S rDNA gene sequencing to a more comprehensive genomic and functional representation through whole-genome sequencing (WGS) of complete communities. Here we performed quantitative and qualitative analyses comparing WGS metagenomic data from human stool specimens using the Illumina Nextera XT and Illumina TruSeq DNA PCR-free kits, and the KAPA Biosystems Hyper Prep PCR and PCR-free systems. Significant differences in taxonomy are observed among the four different next-generation sequencing library preparations using a DNA mock community and a cell control of known concentration. We also revealed biases in error profiles, duplication rates, and loss of reads representing organisms that have a high %G+C content that can significantly impact results. As with all methods, the use of benchmarking controls has revealed critical differences among methods that impact sequencing results and later would impact study interpretation. We recommend that the community adopt PCR-free-based approaches to reduce PCR bias that affects calculations of abundance and to improve assemblies for accurate taxonomic assignment. Furthermore, the inclusion of a known-input cell spike-in control provides accurate quantitation of organisms in clinical samples.