From role of gut microbiota to microbial-based therapies in type 2-diabetes

Carbohydrate quality, fecal microbiota and cardiometabolic health in older adults: a cohort study

The impact of carbohydrate quality, measured by the carbohydrate quality index (CQI), on gut microbiota and health has been scarcely investigated. The aim of this study was to cross-sectionally and longitudinally explore the relationships between CQI, fecal microbiota, and cardiometabolic risk factors in an elderly Mediterranean population at high cardiovascular risk. At baseline and 1-year, CQI was assessed from food frequency questionnaires data, cardiometabolic risk factors were measured, and fecal microbiota profiled from 16S sequencing. Multivariable-adjusted linear regression models were fitted to assess the associations between tertiles of baseline CQI, fecal microbiota, and cardiometabolic risk factors at baseline, and between tertiles of 1-year change in CQI, 1-year change in fecal microbiota and cardiometabolic risk factors. Cross-sectionally, higher CQI was positively associated with Shannon alpha diversity index, and abundance of genera Faecalibacterium and Christensenellaceae R7 group, and negatively associated with the abundance of Odoribacter, and uncultured Rhodospirillales genera. Some of these genera were associated with higher glycated hemoglobin and lower body mass index. In addition, we observed a positive association between CQI, and some pathways related with the metabolism of butyrate precursors and plants-origin molecules. Longitudinally, 1-year improvement in CQI was associated with a concurrent increase in the abundance of genera Butyrivibrio. Increased abundance of this genera was associated with 1-year improvement in insulin status. These observations suggest that a better quality of carbohydrate intake is associated with improved metabolic health, and this improvement could be modulated by greater alpha diversity and abundance of specific genera linked to beneficial metabolic outcomes.

Enriched Aptamer Libraries in Fluorescence-Based Assays for Rikenella microfusus-Specific Gut Microbiome Analyses

Rikenella microfusus is an essential intestinal probiotic with great potential. The latest research shows that imbalance in the intestinal flora are related to the occurrence of various diseases, such as intestinal diseases, immune diseases, and metabolic diseases. Rikenella may be a target or biomarker for some diseases, providing a new possibility for preventing and treating these diseases by monitoring and optimizing the abundance of Rikenella in the intestine. However, the current monitoring methods have disadvantages, such as long detection times, complicated operations, and high costs, which seriously limit the possibility of clinical application of microbiome-based treatment options. Therefore, the intention of this study was to evolve an enriched aptamer library to be used for specific labeling of R. microfusus, allowing rapid and low-cost detection methods and, ultimately the construction of aptamer-based biosensors. In this study, we used Rikenella as the target bacterium for an in vitro whole Cell-SELEX (Systematic Evolution of Ligands by EXponential Enrichment) to evolve and enrich specific DNA oligonucleotide aptamers. Five other prominent anaerobic gut bacteria were included in this process for counterselection and served as control cells. The aptamer library R.m-R13 was evolved with high specificity and strong affinity (Kd = 9.597 nM after 13 rounds of selection). With this enriched aptamer library, R. microfusus could efficiently be discriminated from the control bacteria in complex mixtures using different analysis techniques, including fluorescence microscopy or fluorometric suspension assays, and even in human stool samples. These preliminary results open new avenues toward the development of aptamer-based microbiome bio-sensing applications for fast and reliable monitoring of R. microfusus.

GLP-1 receptor agonists modulate blood glucose levels in T2DM by affecting Faecalibacterium prausnitzii abundance in the intestine

BACKGROUND

Glucagon-like peptide 1 (GLP-1) receptor agonists are a class of medications used to treat type 2 diabetes, including metformin, which is considered first-line therapy for type 2 diabetes. In recent years, GLP-1 receptor agonists (GLP-1 RAs) have been found to alter the composition and structure of gut flora and also promote the production of gut probiotics. However, there have been few clinical studies regarding the effects of GLP-1 RAs on gut flora. In this study, we investigated changes in the abundance of Lactobacillus delbrueckii (L delbrueckii) and Faecalibacterium prausnitzii (F prausnitzii) 1 week after administration of a GLP-1 RA in the clinical treatment of type 2 diabetes. The association with glycemic and body mass index (BMI) correlations was also explored.

METHODS

Twelve newly diagnosed patients with type 2 diabetes were examined for changes in the abundance of L delbrueckii and F prausnitzii by Fluorescence in Situ Hybridization 1 week after administration of GLP-1 RAs. Subjects BMI was measured and fasting glucose changes were detected using the glucose oxidase method, and Spearman correlation analysis was performed to explore their relevance.

RESULTS

There was no significant change in the abundance of L delbrueckii in the intestine (P = .695) and no significant correlation with BMI and fasting glucose levels (R = 0.134, P = .534) after the use of GLP-1 RA (R = -0.098, P = .647); F prausnitzii on the other hand had a significantly higher abundance (P = .002) and a significant negative correlation with fasting glucose level (R = -0.689, P < .001), but no significant correlation with BMI (R = -0.056, P = .796).

CONCLUSION

F prausnitzii may be one of the pathways through which glucose is regulated in the treatment of type 2 diabetes by GLP-1 RAs.

The Association of Planetary Health Diet with the Risk of Type 2 Diabetes and Related Complications: A Systematic Review

BACKGROUND

Nutritional interventions such as the planetary health diet, which the EAT-Lancet commission proposed, may be an effective strategy for reducing type 2 diabetes risks and its associated complications. The planetary health diet demonstrates the significant role of diet in associating human health with environmental sustainability and the significance of transforming food systems in order to ensure that the UN's Sustainable Development Goals and the Paris Agreement are achieved. Therefore, the aim of this review is to examine the association of the planetary health diet (PHD) with the risk of type 2 diabetes and its related complications.

METHOD

The systematic review was conducted in line with established guidelines. The searches were carried out in health sciences research databases through EBSCOHost. The population, intervention, comparator and outcomes framework was used in order to define the research question and the search terms. The searches were carried out from the inception of the databases to 15 November 2022. Search terms including synonyms and medical subject headings were combined using Boolean operators (OR/AND).

RESULTS

Seven studies were included in the review and four themes were identified, including incidence of diabetes; cardiovascular risk factors and other disease risks; indicators of obesity and indicators of environmental sustainability. Two studies examined the association between the PHD and the incidence of type 2 diabetes and found that high adherence to the reference diet (EAT-Lancet reference diet) was correlated with a lower incidence of type 2 diabetes. High adherence to the PHD was also associated with some cardiovascular risk factors and environmental sustainability.

CONCLUSION

This systematic review has shown that high adherence to the PHD is associated with a reduced risk of type 2 diabetes and may be associated with a lower risk of subarachnoid stroke. In addition, an inverse relationship was found between adherence to the PHD and markers of obesity and environmental sustainability. Adherence to the reference diet was also associated with lower values of some markers of cardiovascular risk. More studies are needed to fully examine the relationship between the planetary health diet, type 2 diabetes and its related conditions.

The roles of dietary lipids and lipidomics in gut-brain axis in type 2 diabetes mellitus

Type 2 diabetes mellitus (T2DM), one of the main types of Noncommunicable diseases (NCDs), is a systemic inflammatory disease characterized by dysfunctional pancreatic β-cells and/or peripheral insulin resistance, resulting in impaired glucose and lipid metabolism. Genetic, metabolic, multiple lifestyle, and sociodemographic factors are known as related to high T2DM risk. Dietary lipids and lipid metabolism are significant metabolic modulators in T2DM and T2DM-related complications. Besides, accumulated evidence suggests that altered gut microbiota which plays an important role in the metabolic health of the host contributes significantly to T2DM involving impaired or improved glucose and lipid metabolism. At this point, dietary lipids may affect host physiology and health via interaction with the gut microbiota. Besides, increasing evidence in the literature suggests that lipidomics as novel parameters detected with holistic analytical techniques have important roles in the pathogenesis and progression of T2DM, through various mechanisms of action including gut-brain axis modulation. A better understanding of the roles of some nutrients and lipidomics in T2DM through gut microbiota interactions will help develop new strategies for the prevention and treatment of T2DM. However, this issue has not yet been entirely discussed in the literature. The present review provides up-to-date knowledge on the roles of dietary lipids and lipidomics in gut-brain axis in T2DM and some nutritional strategies in T2DM considering lipids- lipidomics and gut microbiota interactions are given.

Fecal microbiota composition is related to brown adipose tissue 18F-fluorodeoxyglucose uptake in young adults

OBJECTIVE

Human brown adipose tissue (BAT) has gained considerable attention as a potential therapeutic target for obesity and its related cardiometabolic diseases; however, whether the gut microbiota might be an efficient stimulus to activate BAT metabolism remains to be ascertained. We aimed to investigate the association of fecal microbiota composition with BAT volume and activity and mean radiodensity in young adults.

METHODS

82 young adults (58 women, 21.8 ± 2.2 years old) participated in this cross-sectional study. DNA was extracted from fecal samples and 16S rRNA sequencing was performed to analyse the fecal microbiota composition. BAT was determined via a static ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography-computed tomography scan (PET/CT) after a 2 h personalized cooling protocol. ¹⁸F-FDG uptake was also quantified in white adipose tissue (WAT) and skeletal muscles.

RESULTS

The relative abundance of Akkermansia, Lachnospiraceae sp. and Ruminococcus genera was negatively correlated with BAT volume, BAT SUVmean and BAT SUVpeak (all rho ≤ - 0.232, P ≤ 0.027), whereas the relative abundance of Bifidobacterium genus was positively correlated with BAT SUVmean and BAT SUVpeak (all rho ≥ 0.262, P ≤ 0.012). On the other hand, the relative abundance of Sutterellaceae and Bifidobacteriaceae families was positively correlated with ¹⁸F-FDG uptake by WAT and skeletal muscles (all rho ≥ 0.213, P ≤ 0.042). All the analyses were adjusted for the PET/CT scan date as a proxy of seasonality.

CONCLUSION

Our results suggest that fecal microbiota composition is involved in the regulation of BAT and glucose uptake by other tissues in young adults. Further studies are needed to confirm these findings.

CLINICAL TRIAL INFORMATION

ClinicalTrials.gov no. NCT02365129 (registered 18 February 2015).

The Interplay of Dietary Fibers and Intestinal Microbiota Affects Type 2 Diabetes by Generating Short-Chain Fatty Acids

Foods contain dietary fibers which can be classified into soluble and insoluble forms. The nutritional composition of fast foods is considered unhealthy because it negatively affects the production of short-chain fatty acids (SCFAs). Dietary fiber is resistant to digestive enzymes in the gut, which modulates the anaerobic intestinal microbiota (AIM) and fabricates SCFAs. Acetate, butyrate, and propionate are dominant in the gut and are generated via Wood-Ljungdahl and acrylate pathways. In pancreatic dysfunction, the release of insulin/glucagon is impaired, leading to hyperglycemia. SCFAs enhance insulin sensitivity or secretion, beta-cell function, leptin release, mitochondrial function, and intestinal gluconeogenesis in human organs, which positively affects type 2 diabetes (T2D). Research models have shown that SCFAs either enhance the release of peptide YY (PYY) and glucagon-like peptide-1 (GLP-1) from L-cells (entero-endocrine), or promotes the release of leptin hormone in adipose tissues through G-protein receptors GPR-41 and GPR-43. Dietary fiber is a component that influences the production of SCFAs by AIM, which may have beneficial effects on T2D. This review focuses on the effectiveness of dietary fiber in producing SCFAs in the colon by the AIM as well as the health-promoting effects on T2D.

Akkermansia and its metabolites play key roles in the treatment of campylobacteriosis in mice

Introduction

Campylobacter jejuni (C. jejuni) is a common food-borne bacterial pathogen that can use the host's innate immune response to induce the development of colitis. There has been some research on the role of normal intestinal flora in C. jejuni-induced colitis, but the mechanisms that play a central role in resistance to C. jejuni infection have not been explored.

Methods

We treated Campylobacter jejuni-infected mice with fecal microbiota transplantation (FMT), oral butyric acid and deoxycholic acid in a controlled trial and analyzed the possible mechanisms of treatment by a combination of chromatography, immunohistochemistry, fluorescence in situ hybridization, 16s rRNA gene, proteomics and western blot techniques.

Results

We first investigated the therapeutic effect of FMT on C. jejuni infection. The results showed that FMT significantly reduced the inflammatory response and blocked the invasion of C.jejuni into the colonic tissue. We observed a significant increase in the abundance of Akkermansia in the colon of mice after FMT, as well as a significant increase in the levels of butyric acid and deoxycholic acid. We next demonstrated that oral administration of sodium butyrate or deoxycholic acid had a similar therapeutic effect. Further proteomic analysis showed that C.jejuni induced colitis mainly through activation of the PI3K-AKT signaling pathway and MAPK signaling pathway, whereas Akkermansia, the core flora of FMT, and the gut microbial metabolites butyric acid and deoxycholic acid both inhibited these signaling pathways to counteract the infection of C. jejuni and alleviate colitis. Finally, we verified the above idea by in vitro cellular assays. In conclusion, FMT is highly effective in the treatment of colitis caused by C. jejuni, with which Akkermansia and butyric and deoxycholic acids are closely associated.The present study demonstrates that Akkermansia and butyric and deoxycholic acids are effective in the treatment of colitis caused by C. jejuni.

Discussion

This is the first time that Akkermansia has been found to be effective in fighting pathogens, which provides new ideas and insights into the use of FMT to alleviate colitis caused by C. jejuni and Akkermansia as a treatment for intestinal sexually transmitted diseases caused by various pathogens.

Prebiotic activity of chitooligosaccharides and their ability to alleviate necrotizing enterocolitis in newborn rats

Chitooligosaccharides (COS) have many bioactive functions and favorable prospects in the fields of biomedicine and functional foods. In this study, COS was found to significantly improve the survival rate of neonatal necrotizing enterocolitis (NEC) model rats, alter the composition of the intestinal microbiota, inhibit the expression of inflammatory cytokines, and alleviate intestinal pathological injury. In addition, COS also increased the abundance of Akkermansia, Bacteroides, and Clostridium sensu stricto 1 in the intestines of normal rats (the normal rat model is more universal). The in vitro fermentation results found that COS was degraded by the human gut microbiota to promote the abundance of Clostridium sensu stricto 1 and produced numerous short-chain fatty acids (SCFAs). In vitro metabolomic analysis revealed that COS catabolism was associated with significant increases in 3-hydroxybutyrate acid and γ-aminobutyric acid. This study provides evidence for the potential of COS as a prebiotic in food products and to ameliorate NEC development in neonatal rats.

Christensenella regulated by Huang-Qi-Ling-Hua-San is a key factor by which to improve type 2 diabetes

There is a lot of evidence that oral hypoglycemic drugs work by affecting gut microbes, but the key strains responsible for this effect are not well known. Huang-Qi-Ling-Hua-San (HQLHS), composed of Astragalus Membranaceus, Ganoderma lucidum, Inonotus obliquus, and Momordica charantia L., is a specially designed Chinese medicine formula to treat type 2 diabetes (T2D). In this study, a mouse model of T2D induced by high-fat diet and streptozotocin was used to explore the mechanism of HQLHS in improving hyperglycemia and hyperlipidemia through multiple rounds of animal experiments, such as HQLHS feeding, fecal microbiota transplantation (FMT), and live bacteria feeding, so as to explore the potential target intestinal flora in its hypoglycemic effect. Results show that such specific taxa as Bifidobacterium, Turicibacter, Alistipes, Romboutsia, and Christensenella were identified to be preferably enriched by HQLHS and then assumed to be the target microbes. Herein, FMT was used to test if the upregulated beneficial bacteria by HQLHS play a therapeutic role. The strain Christensenella minuta DSM 22607 and the strain Christensenella timonensis DSM 102800 were selected to test the beneficial effect of Christensenella taxa on T2D. Diabetic animals supplemented with these strains showed the improvement in blood glucose and lipid metabolism, the promotion of GLP-1 secretion, the increase in antioxidant capacity, the inhibition of hepatic gluconeogenesis, the suppression of intestinal glucose absorption, the enhancement of intestinal barrier, reduced LPS-induced inflammation, and the reduction of branched amino acids (BCAAs) content in the liver. Overall, these data demonstrate that Christensenella plays a beneficial role in T2D and is a target for the action of HQLHS therapy.

The gut microbiota and celiac disease: Pathophysiology, current perspective and new therapeutic approaches

Celiac disease (CD) as a chronic gluten-sensitive intestinal condition, mainly affects genetically susceptible hosts. The primary determinants of CD have been identified as environmental and genetic variables. The development of CD is significantly influenced by environmental factors, including the gut microbiome. Therefore, gut microbiome re-programming-based therapies using probiotics, prebiotics, postbiotics, gluten-free diet, and fecal microbiota transplantation have shown promising results in the modification of the gut microbiome. Due to the importance and paucity of information regarding the CD pathophysiology, in this review, we have covered the association between CD development and gut microbiota, the effects of infectious agents, particularly the recent Covid-19 infection in CD patients, and the efficacy of potential therapeutic approaches in the CD have been discussed. Hence, scientific literature indicates that the diverse biological functions of the gut microbiota against immunomodulatory responses have made microbiome-based therapy an alternative therapeutic paradigm to ameliorate the symptoms of CD and quality of life. However, the exact potential of microbiota-based techniques that aims to quantitatively and qualitatively alter the gut microbiota to be used in the treatment and ameliorate the symptoms of CD will be determined with further research in the future.

Specific Localization and Quantification of the Oligo-Mouse-Microbiota (OMM12 ) by Fluorescence In Situ Hybridization (FISH)

The oligo-mouse-microbiota (OMM¹² ) is a widely used syncom that colonizes gnotobiotic mice in a stable manner. It provides several fundamental functions to its murine host, including colonization resistance against enteric pathogens. Here, we designed and validated specific fluorescence in situ hybridization (FISH) probes to detect and quantify OMM¹² strains on intestinal tissue cross sections. 16S rRNA-specific probes were designed, and specificity was validated on fixed pure cultures. A hybridization protocol was optimized for sensitive detection of the individual bacterial cells in cryosections. Using this method, we showed that the intestinal mucosal niche of Akkermansia muciniphila can be influenced by global gut microbial community context. © 2022 The Authors. Current Protocols published by Wiley Periodicals LLC. Basic Protocol: Localization and quantification of OMM¹² single strains in mouse cecum cross section Support Protocol: Establishment of specific FISH probe set for OMM¹² syncom.

Therapeutic potential of non-starch polysaccharides on type 2 diabetes: from hypoglycemic mechanism to clinical trials

Non-starch polysaccharides (NSPs) have been reported to exert therapeutic potential on managing type 2 diabetes mellitus (T2DM). Various mechanisms have been proposed; however, several studies have not considered the correlations between the anti-T2DM activity of NSPs and their molecular structure. Moreover, the current understanding of the role of NSPs in T2DM treatment is mainly based on in vitro and in vivo data, and more human clinical trials are required to verify the actual efficacy in treating T2DM. The related anti-T2DM mechanisms of NSPs, including regulating insulin action, promoting glucose metabolism and regulating postprandial blood glucose level, anti-inflammatory and regulating gut microbiota (GM), are reviewed. The structure-function relationships are summarized, and the relationships between NSPs structure and anti-T2DM activity from clinical trials are highlighted. The development of anti-T2DM medication or dietary supplements of NSPs could be promoted with an in-depth understanding of the multiple regulatory effects in the treatment/intervention of T2DM.

Interaction between Plasma Metabolomics and Intestinal Microbiome in db/db Mouse, an Animal Model for Study of Type 2 Diabetes and Diabetic Kidney Disease

Evidence has demonstrated that either metabolites or intestinal microbiota are involved in the pathogenesis of type 2 diabetes (T2D) and diabetic kidney disease (DKD). To explore the interaction between plasma metabolomics and intestinal microbiome in the progress of T2D-DKD, in the current study, we analyzed metabolomics in the plasma of db/db mice with liquid chromatography–mass spectrometry and also examined intestinal prokaryotes and entire gut microbiome dysbiosis at the genus level with both 16S rDNA and metagenomic sequencing techniques. We found that Negativibacillus and Rikenella were upregulated, while Akkermansia, Candidatus, Erysipelatoclostridium and Ileibacterium were downregulated in the colon of db/db mice compared with non-diabetic controls. In parallel, a total of 91 metabolites were upregulated, while 23 were downregulated in the plasma of db/db mice. The top five upregulated metabolites included D-arabinose 5-phosphate, estrone 3-sulfate, L-theanine, 3′-aenylic acid and adenosine 5′-monophosphate, and the five most significantly downregulated metabolites were aurohyocholic acid sodium salt, calcium phosphorylcholine chloride, tauro-alpha-muricholic acid sodium salt, galactinol and phosphocholine. These plasma metabolites were interacted with intestinal microbiomes, which are mainly involved in the pathways related to the biosynthesis of unsaturated fatty acids, fatty acid elongation, steroid biosynthesis, and D-arginine and D-ornithine metabolism. In the differential metabolites, N-acetyl-L-ornithine, ornithine and L-kyn could be metabolized by the correspondingly differential ontology genes in the intestinal metagenome. The current study thereby provides evidence for a gut–metabolism–kidney axis in the metabolism of db/db mice, in which the gut microbiome and circulating metabolomics interact, and suggests that information from this axis may contribute to our understanding of T2D and DKD pathogenesis.

Synbiotics and Gut Microbiota: New Perspectives in the Treatment of Type 2 Diabetes Mellitus

The number of people with type 2 diabetes mellitus (T2DM) has increased sharply over the past decades. Apart from genetic predisposition, which may cause some of the diagnosed cases, an unhealthy diet and lifestyle are incentive triggers of this global epidemic. Consumption of probiotics and prebiotics to gain health benefits has become increasingly accepted by the public in recent years, and their critical roles in alleviating T2DM symptoms are confirmed by accumulating studies. Microbiome research reveals gut colonization by probiotics and their impacts on the host, while oral intake of prebiotics may stimulate existing metabolisms in the colon. The use of synbiotics (a combination of prebiotics and probiotics) can thus show a synergistic effect on T2DM through modulating the gastrointestinal microenvironment. This review summarizes the research progress in the treatment of T2DM from the perspective of synbiotics and gut microbiota and provides a class of synbiotics which are composed of lactulose, arabinose, and Lactobacillus plantarum, and can effectively adjust the blood glucose, blood lipid, and body weight of T2DM patients to ideal levels.

The Leaves of Cyclocarya paliurus: A Functional Tea with Preventive and Therapeutic Potential of Type 2 Diabetes

Type 2 diabetes mellitus (T2DM) has become a universal and chronic global public health concern and causes multiple complex complications. In order to meet the rapidly growing demand for T2DM treatment, increased research has been focused on hypoglycemic drugs. Cyclocarya paliurus (Batal.) Iljinsk is the only living species of the genus Cyclocarya Iljinskaja, whose leaves have been extensively used as a functional tea to treat obesity and diabetes in China. An enormous amount of very recent pharmacological research on the leaves of C. paliurus has demonstrated that they carry out numerous biological activities, such as hypoglycemic, anti-inflammatory, and intestinal microbiota regulation. Multiple in vitro and in vivo studies have also shown that the extracts of C. paliurus leaves are innocuous and safe. This study aims to provide an up-to-date review of the botany, traditional uses, phytochemistry, pharmacological effects against diabetes, toxicology, and clinical studies of C. paliurus leaves, in hopes of promoting a better understanding of their role in the prevention and treatment of T2DM.

Targeting the gut to prevent and counteract metabolic disorders and pathologies during aging

Impairment of gut function is one of the explanatory mechanisms of health status decline in elderly population. These impairments involve a decline in gut digestive physiology, metabolism and immune status, and associated to that, changes in composition and function of the microbiota it harbors. Continuous deteriorations are generally associated with the development of systemic dysregulations and ultimately pathologies that can worsen the initial health status of individuals. All these alterations observed at the gut level can then constitute a wide range of potential targets for development of nutritional strategies that can impact gut tissue or associated microbiota pattern. This can be key, in a preventive manner, to limit gut functionality decline, or in a curative way to help maintaining optimum nutrients bioavailability in a context on increased requirements, as frequently observed in pathological situations. The aim of this review is to give an overview on the alterations that can occur in the gut during aging and lead to the development of altered function in other tissues and organs, ultimately leading to the development of pathologies. Subsequently is discussed how nutritional strategies that target gut tissue and gut microbiota can help to avoid or delay the occurrence of aging-related pathologies.

Kombucha Reduces Hyperglycemia in Type 2 Diabetes of Mice by Regulating Gut Microbiota and Its Metabolites

Kombucha, which is rich in tea polyphenols and organic acid, is a kind of acidic tea soup beverage fermented by acetic acid bacteria, yeasts, lactic acid bacteria. Kombucha has been reported to possess anti-diabetic activity, but the underlying mechanism was not well understood. In this study, a high-fat, high-sugar diet combined with streptozotocin (STZ) injection was used to induce T2DM model in mice. After four weeks of kombucha intervention, the physiological and biochemical index were measured to determine the diabetes-related indicators. High-throughput sequencing technology was used to analyze the changes in gut microbiota from the feces. The results showed that four weeks of kombucha intervention increased the abundance of SCFAs-producing bacteria and reduced the abundance of gram-negative bacteria and pathogenic bacteria. The improvement in gut microbiota reduced the damage of intestinal barrier, thereby reducing the displacement of lipopolysaccharide (LPS) and inhibiting the occurrence of inflammation and insulin resistance in vivo. In addition, the increased levels of SCFAs-producing bacteria, and thus increasing the SCFAs, improved islet β cell function by promoting the secretion of gastrointestinal hormones (GLP-1/PYY). This study methodically uncovered the hypoglycemic mechanism of kombucha through gut microbiota intervention, and the result suggested that kombucha may be introduced as a new functional drink for T2DM prevention and treatment.

The Gut-Skin Microbiota Axis and Its Role in Diabetic Wound Healing-A Review Based on Current Literature

Diabetic foot ulcers (DFU) are a growing concern worldwide as they pose complications in routine clinical practices such as diagnosis and management. Bacterial interactions on the skin surface are vital to the pathophysiology of DFU and may control delayed wound healing. The microbiota from our skin directly regulates cutaneous health and disease by interacting with the numerous cells involved in the wound healing mechanism. Commensal microbiota, in particular, interact with wound-repairing skin cells to enhance barrier regeneration. The observed microbes in DFU include Staphylococcus, Streptococcus, Corynebacterium, Pseudomonas, and several anaerobes. Skin commensal microbes, namely S. epidermidis, can regulate the gamma delta T cells and induce Perforin-2 expression. The increased expression of Perforin-2 by skin cells destroyed S. aureus within the cells, facilitating wound healing. Possible crosstalk between the human commensal microbiome and different cell types involved in cutaneous wound healing promotes the immune response and helps to maintain the barrier function in humans. Wound healing is a highly well-coordinated, complex mechanism; it can be devastating if interrupted. Skin microbiomes are being studied in relation to the gut-skin axis along with their effects on dermatologic conditions. The gut-skin axis illustrates the connection wherein the gut can impact skin health due to its immunological and metabolic properties. The precise mechanism underlying gut-skin microbial interactions is still unidentified, but the immune and endocrine systems are likely to be involved. Next-generation sequencing and the development of bioinformatics pipelines may considerably improve the understanding of the microbiome-skin axis involved in diabetic wound healing in a much more sophisticated way. We endeavor to shed light on the importance of these pathways in the pathomechanisms of the most prevalent inflammatory conditions including the diabetes wound healing, as well as how probiotics may intervene in the gut-skin axis.

Antidiabetic Effects of Bifidobacterium longum subsp. longum BL21 through Regulating Gut Microbiota Structure in Type 2 Diabetic Mice

Bifidobacterium longum subsp. longum BL21 (BL21) possess hypoglycemic activity, but its anti-diabetic mechanism has rarely been illustrated. In the present work, the effect of BL21 on type 2 diabetes mellitus...

Different approaches to change gut microbiota and its influence on metabolic disorders

Obesity and type 2 diabetes mellitus (T2D) are two non-infectious pandemics of the XXI century. Despite a large number of studies devoted to the development of obesity and T2D, it seems complicated to overcome the ongoing growth in the number of cases. In these situations it is necessary to investigate new approaches for the prevention and treatment of such diseases. One of these approaches is to study the role of gut microbiota in the disturbance of carbohydrate and lipid metabolism. This manuscript describes the role of the microbiota in obesity and T2D. The aim of the review was to describe various approaches to change the composition of the gut microbiota and to determine its impact on metabolic risks. To assess the relationship between T2D development and changes of microbiota composition we considered a number of studies devoted to the consequence of these pathophysiologic mechanisms in various situations: the effect of drug treatment, bariatric surgery and microbiota transplantation. Possible metabolically protective gut microbiota composition is discussed.

Gut microbiota in nonalcoholic fatty liver diseases with and without type-2 diabetes mellitus

BACKGROUND AND AIMS

The association between nonalcoholic fatty liver disease (NAFLD) and type 2 diabetes mellitus (T2DM) is not very well described but gut microbiota composition is mentioned as a risk factor. The present study aimed to characterize the differences of dominant gut microbiota phyla among people with NAFLD as compared to T2DM and control groups.

PATIENTS AND METHODS

The major bacterial phylum of gut microbiota including Bacteroidetes, Firmicutes, Actinobacteria, Proteobacteria, and total bacteria of 15 NAFLD patients with T2DM, 15 NAFLD patients without T2DM, 15 patients with T2DM, and 20 healthy control subjects were assessed by a quantitative PCR (qPCR).

RESULTS

NAFLD patients with T2DM had significantly higher BMI, triglyceride level, and total cholesterol level were compared with controls (Pv < 0.05). Bacteroidetes and Firmicutes phyla were significantly low in NAFLD patients with T2DM (Firmicutes, 2.55 ± 2.25, Pv 0/0002 and Bacteroidetes, 1.55 ± 2.29, Pv 0/0007), while the content of Proteobacteria and Actinobacteria was high in NAFLD patients with T2DM group and there were no significant differences between phyla with NAFLD patients with T2DM group (Pv > 0.05). Furthermore, Firmicutes copy number was lower in the separate groups of NAFLD and T2DM as compared to the healthy controls (Pv < 0.05).

CONCLUSIONS

This study performed gut microbiota for the first time among NAFLD and TDM patients separately and together. This investigation indicated that NAFLD patients with T2DM have a different gut composition in comparison to NAFLD, T2DM alone, which could be associated with disease development.

Fecal microbiota transplantation mitigates bone loss by improving gut microbiome composition and gut barrier function in aged rats

Background

Gut microbiota (GM) dysbiosis is closely related to bone loss and the occurrence of osteoporosis in animals and human. However, little is known about the effect and the mechanisms of fecal microbiota transplantation (FMT) on bone in the treatment of senile osteoporosis.

Methods

Aged female rats were randomly divided into the FMT group and the control group. 3-month-old female rats were used as fecal donors. The rats were sacrificed at 12 and 24 weeks following transplantation and the serum, intestine, bone, and feces were collected for subsequent analyses.

Results

The bone turnover markers of osteocalcin, procollagen type 1 N-terminal propeptide (P1NP), and carboxy-terminal peptide (CTX) decreased significantly at 12 and 24 weeks following FMT (P < 0.05). At 12 weeks following transplantation, histomorphometric parameters including the bone volume (BV), trabecular bone volume fraction (BV/TV), trabecular number (Tb.N), and trabecular thickness (Tb.Th) of the FMT group were comparable to the control group. However, at 24 weeks following transplantation, these parameters of the FMT group were significantly higher than those of the control group (P < 0.05). Besides, the GM aggregated at 12 and 24 weeks following FMT, and the ecological distance was close between the rats in the FMT group and the donor rats. Alpha diversity, shown by the Shannon index and Simpson index, and the Firmicutes/Bacteroidetes ratio decreased significantly after FMT at 24 weeks. Furthermore, FMT restored the GM composition in aged rats at the phylum and family level, and the intestinal microbiota of the aged rats was similar to that of the donor rats. Correlation network analysis indirectly suggested the causality of FMT on alleviating osteoporosis. FMT improved the intestinal structure and up-regulated the expression of tight junction proteins of occludin, claudin, and ZO-1, which might be associated with the protective effects of FMT on bone.

Conclusions

GM transplanted from young rats alleviated bone loss in aged rats with senile osteoporosis by improving gut microbiome composition and intestinal barrier function. These data might provide a scientific basis for future clinical treatment of osteoporosis through FMT.

The Effects of Almonds on Gut Microbiota, Glycometabolism, and Inflammatory Markers in Patients with Type 2 Diabetes: A Systematic Review and Meta-Analysis of Randomised Controlled Trials

The use of nutritional interventions for managing diabetes is one of the effective strategies aimed at reducing the global prevalence of the condition, which is on the rise. Almonds are the most consumed tree nut and they are known to be rich sources of protein, monounsaturated fatty acids, essential minerals, and dietary fibre. Therefore, the aim of this review was to evaluate the effects of almonds on gut microbiota, glycometabolism, and inflammatory parameters in patients with type 2 diabetes.

METHODS

This systematic review and meta-analysis was carried out according to the preferred reporting items for systematic review and meta-analysis (PRISMA). EBSCOhost, which encompasses the Health Sciences Research Databases; Google Scholar; EMBASE; and the reference lists of articles were searched based on population, intervention, control, outcome, and study (PICOS) framework. Searches were carried out from database inception until 1 August 2021 based on medical subject headings (MesH) and synonyms. The meta-analysis was carried out with the Review Manager (RevMan) 5.3 software.

RESULTS

Nine randomised studies were included in the systematic review and eight were used for the meta-analysis. The results would suggest that almond-based diets have significant effects in promoting the growth of short-chain fatty acid (SCFA)-producing gut microbiota. Furthermore, the meta-analysis showed that almond-based diets were effective in significantly lowering (p < 0.05) glycated haemoglobin (HbA1c) levels and body mass index (BMI) in patients with type 2 diabetes. However, it was also found that the effects of almonds were not significant (p > 0.05) in relation to fasting blood glucose, 2 h postprandial blood glucose, inflammatory markers (C-reactive protein and Tumour necrosis factor α, TNF-α), glucagon-like peptide-1 (GLP-1), homeostatic model assessment of insulin resistance (HOMA-IR), and fasting insulin. The biological mechanisms responsible for the outcomes observed in this review in relation to reduction in HbA1c and BMI may be based on the nutrient composition of almonds and the biological effects, including the high fibre content and the low glycaemic index profile.

CONCLUSION

The findings of this systematic review and meta-analysis have shown that almond-based diets may be effective in promoting short-chain fatty acid-producing bacteria and lowering glycated haemoglobin and body mass index in patients with type 2 diabetes compared with control. However, the effects of almonds were not significant (p > 0.05) with respect to fasting blood glucose, 2 h postprandial blood glucose, inflammatory markers (C-reactive protein and TNF-α), GLP-1, HOMA-IR, and fasting insulin.

Gut Bacterial Characteristics of Patients With Type 2 Diabetes Mellitus and the Application Potential

Type 2 diabetes mellitus (T2DM) is a complex disorder comprehensively influenced by genetic and environmental risk, and research increasingly has indicated the role of microbial dysbiosis in T2DM pathogenesis. However, studies comparing the microbiome characteristics between T2DM and healthy controls have reported inconsistent results. To further identify and describe the characteristics of the intestinal flora of T2DM patients, we performed a systematic review and meta-analysis of stool microbial profiles to discern and describe microbial dysbiosis in T2DM and to explore heterogeneity among 7 studies (600 T2DM cases, 543 controls, 1143 samples in total). Using a random effects model and a fixed effects model, we observed significant differences in beta diversity, but not alpha diversity, between individuals with T2DM and controls. We identified various operational taxonomic unit (OTUs) and bacterial genera with significant odds ratios for T2DM. The T2DM signatures derived from a single study by stepwise feature selection could be applied in other studies. By training on multiple studies, we improved the detection accuracy and disease specificity for T2DM. We also discuss the relationship between T2DM-enriched or T2DM-depleted genera and probiotics and provide new ideas for diabetes prevention and improvement.

Lactobacillus casei LC89 exerts antidiabetic effects through regulating hepatic glucagon response and gut microbiota in type 2 diabetic mice

Previous study suggests that Lactobacillus casei exhibits antihyperglycemic activity, however, the molecular mechanism of this has yet to be elucidated. Here, the anti-diabetic effects and underlying mechanisms of Lactobacillus casei LC89 are investigated in type 2 diabetes mellitus (T2DM) mice, which was induced by a high-fat diet (HFD) with streptozotocin (100 mg per kg BW). The results show that LC89 at a dose of 109 CFU day-1 decreases fasting blood glucose (FBG) and insulin levels by 35.12% and 28.37%, respectively, compared to the diabetes control (DC) group. Moreover, LC89 treatment improved the insulin resistance index (HOMA-IR), serum lipid profiles and inflammation cytokines. The real-time polymerase chain reaction indicated that LC89 markedly downregulates the mRNA expression of hepatic glucagon (GCG), glucagon receptor (GCGR), phosphoenolpyruvate carboxykinase (PEPCK) and glucose-6-phosphatase (G6Pase). Meanwhile, LC89 significantly decreases the abundance of Odoribacter, but increases the Alloprevotella, Bacteroides, Parabacteroides and Ruminococcus content. Therefore, LC89 plays a positive role in alleviating T2DM by regulating gut microbiota and glucagon signal pathway-related genes, and it may be a beneficial dietary supplement to regulate glucose metabolism in T2DM.

Nutritional and therapeutic approaches for protecting human gut microbiota from psychotropic treatments

Emerging evidence highlighted the essential role played by the microbiota-gut-brain axis in maintaining human homeostasis, including nutrition, immunity, and metabolism. Much recent work has linked the gut microbiota to many psychiatric and neurodegenerative disorders such as depression, schizophrenia, and Alzheimer's disease. Shared gut microbiota alterations or dysbiotic microbiota have been identified in these separate disorders relative to controls. Much attention has focused on the bidirectional interplay between the gut microbiota and the brain, establishing gut dysbiotic status as a critical factor in psychiatric disorders. Still, the antibiotic-like effect of psychotropic drugs, medications used for the treatment of these disorders, on gut microbiota is largely neglected. In this review, we summarize the current findings on the impact of psychotropics on gut microbiota and how their antimicrobial potency can trigger dysbiosis. We also discuss the potential therapeutic strategies, including probiotics, prebiotics, and fecal transplantation, to attenuate the dysbiosis related to psychotropics intake.

Analysis of jejunum microbiota of HFD/STZ diabetic rats

Currently, several studies propose that the dominant intestinal bacteria are core flora. Besides keeping the homeostasis of the intestinal environment, the intestinal microflora also plays a role in body metabolism, production of some vitamins, and control of barrier function. The study aimed to investigate the jejunum microbiota in diabetic rats as well as it's the relationship with Ceftriaxone sodium-mediated gut dysbiosis, diabetic parameters, and intestinal permeability. Thirty-two Wistar rats (Male) were enrolled and divided into four groups (A, B, C, and D; N = 8). Subsequently, T2DM was induced in C and D groups by HFD/STZ model and then gut dysbiosis in B and D groups via intragastric administration of Ceftriaxone sodium for two weeks. The food-water intake, body weight, fasting blood glucose, plasma insulin, HOMA-IR, intestinal permeability, and jejunum microbiota and it's histology were investigated. In this study, T2DM was associated with a significant decrease in the richness and diversity of jejunum microbiota, elevation in the intestinal permeability, and higher abundance of some opportunistic pathogens. Ceftriaxone sodium-induced gut dysbiosis declined food-water intake, damagedthe villi of jejunum tissue, increased intestinal permeability, and affected the diversity of jejunum microbiota. In diabetic rats, Ceftriaxone sodium-mediated gut dysbiosis also declined the abundance of someSCFAs bacteria and raised the abundant of some opportunistic bacteria such as Staphylococcus_sciuri. Interestingly, we found that several bacteria were negatively correlated with HOMA-IR, fasting blood glucose, body weight, and intestinal permeability. Overall, the study highlighted the jejunum microflora alterations in HFD/STZ diabetic rats and assessed the effect of Ceftriaxone sodium-induced gut dysbiosis on diabetic parameters, jejunum microbiota and histology, and intestinal permeability, which are of potential for further studies.

The Effect of Dietary Fibre on Gut Microbiota, Lipid Profile, and Inflammatory Markers in Patients with Type 2 Diabetes: A Systematic Review and Meta-Analysis of Randomised Controlled Trials

Background: A disequilibrium of the gut microbial community has been closely associated with systemic inflammation and metabolic syndromes including type 2 diabetes. While low fibre and high fat diets may lead to dysbiosis of the gut microbiome as a result of the loss of useful microbes, it has been reported that a high fibre diet may prevent the fermentation of protein and may promote eubiosis of gut microbiota. Aim: This review aims to evaluate the effect of dietary fibre (DF) on gut microbiota, lipid profile, and inflammatory markers in patients with type 2 diabetes. Methods: The PRISMA framework was relied on to conduct this systematic review and meta-analysis. Searches were carried out using electronic databases and reference list of articles. Results: Eleven studies were included in the systematic review, while ten studies were included in the meta-analysis. The findings revealed five distinct areas including the effects of DF on (a) gut microbiota (122 participants); (b) lipopolysaccharides (LPS, 79 participants) and lipopolysaccharides binding protein (LBP, 81 participants); (c) lipid profile; (d) inflammatory markers; and (e) body mass index (BMI, 319 participants). The relative abundance of Bifidobacterium increased by 0.73 (95% CI: 0.57, 0.89) in the DF group in contrast to the control (p < 0.05). With respect to LPS, the level was lower in the DF group than the control and the difference was significant (p < 0.05). The standardised mean difference for LPS was −0.45 (95% CI: −0.90, −0.01) although the difference between the two groups in relation to LBP was not significant (p = 0.08) and the mean difference was 0.92 (95% CI: −0.12, 1.95). While there was a decrease of −1.05 (95% CI: −2.07, −0.02) with respect to total cholesterol (356 participants) in the DF group as compared with the control (p < 0.05), both groups were not significantly different (p > 0.05) in the other lipid parameters. The difference between the groups was significant (p < 0.05) in relation to C-reactive protein, and the mean difference was 0.43 (95% CI: 0.02, 0.84). This could be due to the short duration of the included studies and differences in participants’ diets including the amount of dietary fibre supplements. However, the groups were not significantly different (p > 0.05) with respect to the other inflammatory markers. The meta-analysis of the BMI showed that the DF group decreased by −0.57 (95% CI: −1.02, −0.12) as compared with the control and this was significant (p < 0.01). Conclusion: DF significantly (p < 0.05) increased the relative abundance of Bifidobacterium and significantly decreased (p < 0.05) LPS, total cholesterol, and BMI as compared with the control. However, DF did not seem to have an effect that was significant on LBP, triglyceride, HDL cholesterol, LDL cholesterol, IL-6, TNF-α, adiponectin, and leptin. These findings have implications for public health in relation to the use of dietary fibre in nutritional interventions and as strategies for managing type 2 diabetes.

Whole Alga, Algal Extracts, and Compounds as Ingredients of Functional Foods: Composition and Action Mechanism Relationships in the Prevention and Treatment of Type-2 Diabetes Mellitus

Type-2 diabetes mellitus (T2DM) is a major systemic disease which involves impaired pancreatic function and currently affects half a billion people worldwide. Diet is considered the cornerstone to reduce incidence and prevalence of this disease. Algae contains fiber, polyphenols, ω-3 PUFAs, and bioactive molecules with potential antidiabetic activity. This review delves into the applications of algae and their components in T2DM, as well as to ascertain the mechanism involved (e.g., glucose absorption, lipids metabolism, antioxidant properties, etc.). PubMed, and Google Scholar databases were used. Papers in which whole alga, algal extracts, or their isolated compounds were studied in in vitro conditions, T2DM experimental models, and humans were selected and discussed. This review also focuses on meat matrices or protein concentrate-based products in which different types of alga were included, aimed to modulate carbohydrate digestion and absorption, blood glucose, gastrointestinal neurohormones secretion, glycosylation products, and insulin resistance. As microbiota dysbiosis in T2DM and metabolic alterations in different organs are related, the review also delves on the effects of several bioactive algal compounds on the colon/microbiota-liver-pancreas-brain axis. As the responses to therapeutic diets vary dramatically among individuals due to genetic components, it seems a priority to identify major gene polymorphisms affecting potential positive effects of algal compounds on T2DM treatment.

Role and Mechanism of Gut Microbiota in Human Disease

The human gut microbiome is a huge microbial community that plays an irreplaceable role in human life. With the further development of research, the influence of intestinal flora on human diseases has been gradually excavated. Gut microbiota (GM) dysbiosis has adverse health effects on the human body that will lead to a variety of chronic diseases. The underlying mechanisms of GM on human diseases are incredibly complicated. This review focuses on the regulation and mechanism of GM on neurodegenerative diseases, cardiovascular diseases, metabolic diseases and gastrointestinal diseases, thus providing a potential target for the prevention and treatment of disease.

Unravelling the involvement of gut microbiota in type 2 diabetes mellitus

Type 2 diabetes mellitus is the most prevalent metabolic disorder characterized by hyperglycemia, hyperlipidemia as well as insulin resistance and is affecting the lives of a huge population across the globe. Genetic mutations, obesity and lack of physical activity constitute the possible factors that can lead to onset and progression of this disorder. However, there is another major factor that can be the root cause of type 2 diabetes mellitus and that is an imbalance in the microorganisms that inhabit the gut. The gut microbiome is a vital component that needs to be given significant attention because any "dysbiosis" in the colonic microorganisms can transform the host from a state of health to a state of disease. This transformation is quite obvious since the gut barrier integrity, host metabolism such as sensitivity to insulin and maintaining blood glucose level are carried out by the tiny organisms inhabiting our intestine. In fact, the normal functioning of the human body is accredited to the microbes, particularly the bacteria, because they generate their metabolites that communicate with host cells and maintain normal physiology. Giving importance to gut health is, therefore, necessary to prevent metabolic diseases that can be maintained by the intake of prebiotics, probiotics, synbiotics along with healthy diet. The tiny microorganisms in the gut that keep our body free of disorders such as type 2 diabetes mellitus need to be in a state of 'eubiosis', else the consequences of disturbance in gut microbes can progress to serious complications in the host.

The effect of probiotics, prebiotics or synbiotics on metabolic outcomes in individuals with diabetes: a systematic review and meta-analysis

AIMS/HYPOTHESIS

The aim was to conduct a systematic review and meta-analysis of randomised controlled clinical trials assessing the effect of probiotic, prebiotic or synbiotic supplementation on gut microbiota and glucose control and lipid levels in individuals with diabetes.

METHODS

MEDLINE, EMBASE and the Cochrane Library were searched. The eligibility criteria for the studies was involvement of participants with a diagnosis of type 1 or type 2 diabetes. Metabolic outcomes (glucose control, insulinaemia, and lipid profile) of any probiotic, prebiotic or synbiotic supplementation related to modification of gut microbiota (prebiotics, probiotics and synbiotics) were analysed. We provided a narrative synthesis and meta-analysis of the findings on metabolic outcomes from the studies. Metabolic outcomes were extracted post-intervention and expressed as mean differences (MDs) and 95% CIs between treatment and comparator groups. We pooled the results using a random-effects meta-analysis. The meta-analysis was conducted using Review Manager (RevMan) software.

RESULTS

After the removal of duplicates and ineligible studies, 5219 studies were retained for review of titles and abstracts. The number of articles was reduced to 130 by review, for which the full-text articles were obtained and reassessed, 38 of which were included in the final meta-analysis. Overall, the use of prebiotics, probiotics or synbiotics reduced HbA_1c levels, but did not reach the threshold for significance (-2.17 mmol/mol, 95% CI -4.37, 0.03; p = 0.05, [-0.20%, 95% CI -0.40 to 0.00; p = 0.05, I² = 66%]) and had no effect on LDL-cholesterol levels (-0.05 mmol/l; 95% CI -0.14, 0.05, p = 0.35, I² = 37%). However, their consumption decreased levels of fasting blood glucose (-0.58 mmol/l; 95% CI -0.86, -0.30; p < 0.01, I² = 60%), total cholesterol (-0.14 mmol/l; 95% CI -0.26, -0.02, p = 0.02, I² = 39%), triacylglycerols (-0.11 mmol/l; 95% CI -0.20, -0.02, p = 0.01, I²= 21%) and insulinaemia (-10.51 pmol/l; 95% CI -16.68,-4.33, p < 0.01, I² = 74%), and increased HDL-cholesterol levels (0.04 mmol/l; 95% CI 0.01, 0.07, p < 0.01, I²= 24%).

CONCLUSIONS/INTERPRETATION

In individuals with diabetes mellitus, supplementation with probiotics, prebiotics or synbiotics improved metabolic variables, although the magnitude of this effect is low. Our results suggest that consumption of probiotics, prebiotics or synbiotics may be a potential adjuvant treatment for improving metabolic outcomes.

REGISTRATION

PROSPERO ID CRD42017080071. Graphical abstract.

Coronavirus Disease (COVID-19) Caused by (SARS-CoV-2) Infections: A Real Challenge for Human Gut Microbiota

The current COVID-19 pandemic is a great challenge for worldwide researchers in the human microbiota area because the mechanisms and long-term effects of the infection at the GI level are not yet deeply understood. In the current review, scientific literature including original research articles, clinical studies, epidemiological reports, and review-type articles concerning human intestinal infection with SARS-CoV-2 and the possible consequences on the microbiota were reviewed. Moreover, the following aspects pertaining to COVID-19 have also been discussed: transmission, resistance in the human body, the impact of nutritional status in relation to the intestinal microbiota, and the impact of comorbid metabolic disorders such as inflammatory bowel disease (IBS), obesity, and type two diabetes (T2D). The articles investigated show that health, age, and nutritional status are associated with specific communities of bacterial species in the gut, which could influence the clinical course of COVID-19 infection. Fecal microbiota alterations were associated with fecal concentrations of SARS-CoV-2 and COVID-19 severity. Patients suffering from metabolic and gastrointestinal (GI) disorders are thought to be at a moderate-to-high risk of infection with SARS-CoV-2, indicating the direct implication of gut dysbiosis in COVID-19 severity. However, additional efforts are required to identify the initial GI symptoms of COVID-19 for possible early intervention.

Gut dysbiosis and age-related neurological diseases; an innovative approach for therapeutic interventions

The gut microbiota is a complex ecosystem of bacteria, fungi, and viruses that acts as a critical regulator in microbial, metabolic, and immune responses in the host organism. Imbalances in the gut microbiota, termed "dysbiosis," often induce aberrant immune responses, which in turn disrupt the local and systemic homeostasis of the host. Emerging evidence has highlighted the importance of gut microbiota in intestinal diseases, and more recently, in age-related central nervous systems diseases, for example, stroke and Alzheimer's disease. It is now generally recognized that gut microbiota significantly influences host behaviors and modulates the interaction between microbiota, gut, and brain, via the "microbiota-gut-brain axis." Several approaches have been utilized to reduce age-related dysbiosis in experimental models and in clinical studies. These include strategies to manipulate the microbiome via fecal microbiota transplantation, administration of prebiotics and probiotics, and dietary interventions. In this review, we explore both clinical and preclinical therapies for treating age-related dysbiosis.

Gut Microbiota and Serum Biomarker Analyses in Obese Patients Diagnosed with Diabetes and Hypothyroid Disorder

Background: Variations of serum biomarkers and bacterial diversity of the gastrointestinal tract in obese patients with diabetes or hypothyroid are poorly understood. The aim of this study was to provide recent findings in this regard. Methods: A total of 119 obese patients [17 with diabetes, 23 with hypothyroid, and 79 patients without either diabetes or hypothyroid (control)] were recruited in this study. Serum biomarkers such as biochemical, hormonal (insulin and glucagon), and cytokine levels [interleukin (IL)-6, IL-1β, tumor necrosis factor-alpha, IL-10, and transforming growth factor beta-1 (TGF-β1)] were measured under fasting conditions. Bacterial abundance of gut microbiota was also quantitated by real-time polymerase chain reaction using 16S rRNA gene-based specific primers. Results: Average value of blood sugar (P: 0.0184), hemoglobin A1c, insulin, homeostasis model assessment insulin resistance, TGF-β 1, IL-6, IL-1β, interferon gamma (P_{for each} < 0.001), and phylum Actinobacteria [odds ratio (OR): 1.5, P: 0.032] was significantly higher in diabetic versus control group. In contrast, the levels of IL-10 (P < 0.001), Firmicutes (OR: 0.6, P: 0.058), and Akkermansia muciniphila (OR: 0.4, P: 0.053) were significantly lower in diabetic versus control group. However, there was no statistically significant difference between the values in hypothyroid versus control group either in crude or adjusted models. Conclusion: While there are some relationships between serum biomarkers or bacterial abundance with diabetes prediction in obese patients, this prognostication is less likely in obese patients with hypothyroid. Further investigation is warranted in the application of identified preclinical biomarkers in the diagnosis of diabetes or hypothyroid in obese patients.

A polysaccharide from Fagopyrum esculentum Moench bee pollen alleviates microbiota dysbiosis to improve intestinal barrier function in antibiotic-treated mice

Antibiotics are the most commonly used clinical drugs for anti-infection, but they can also destroy normal microorganisms and cause intestinal barrier dysfunction. To elucidate the effects and mechanism of a water-soluble polysaccharide from Fagopyrum esculentum Moench bee pollen (WFPP) on intestinal barrier integrity in antibiotic-treated mice, BALB/c mice were exposed to a broad-spectrum antibiotic (ceftriaxone) or not (control), and were administered low-, medium- and high-dose WFFP (100 mg kg^-1, 200 mg kg^-1 and 400 mg kg^-1, respectively) daily by oral gavage for 3 weeks. Mice treated with ceftriaxone displayed symptoms of growth retardation, atrophy of immune organs including thymus and spleen, increased gut permeability, and intestinal barrier damage, which were restored after intervention with WFFP at different doses. Moreover, the beneficial effects of WFFP were closely associated with enhanced intestinal sIgA secretion and reduced inflammatory response. Furthermore 16S rDNA gene sequencing revealed that WFPP elevated microbial diversity and richness and changed the community structure, therefore, alleviating microbiota dysbiosis caused by ceftriaxone. Interestingly, WFPP could modulate the abundance of sIgA secretion-related bacteria (e.g. Proteobacteria) and inflammation-related bacteria (e.g. Enterococcus). Therefore, WFPP can relieve antibiotic-induced microbiota dysbiosis to improve intestinal barrier integrity by increasing intestinal sIgA secretion and inhibiting inflammation.

The Role of Dietary Fibre in Modulating Gut Microbiota Dysbiosis in Patients with Type 2 Diabetes: A Systematic Review and Meta-Analysis of Randomised Controlled Trials

Background: The prevalence of type 2 diabetes is on the increase worldwide, and it represents about 90% of adults who are diagnosed with diabetes. Overweight and obesity, lifestyle, genetic predisposition and gut microbiota dysbiosis have been implicated as possible risk factors in the development of type 2 diabetes. In particular, low intake of dietary fibre and consumption of foods high in fat and sugar, which are common in western lifestyle, have been reported to contribute to the depletion of specific bacterial taxa. Therefore, it is possible that intake of high dietary fibre may alter the environment in the gut and provide the needed substrate for microbial bloom. Aim: The current review is a systematic review and meta-analysis which evaluated the role of dietary fibre in modulating gut microbiota dysbiosis in patients with type 2 diabetes. Methods: This is a systematic review and meta-analysis of randomised controlled trials which relied on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) framework. Electronic searches were conducted using EBSCOHost with links to Health Sciences Research Databases, EMBASE and Google Scholar. The reference lists of articles were also searched for relevant studies. Searches were conducted from date of commencement of the database to 5 August 2020. The search strategy was based on the Population, Intervention, Comparator, Outcomes, Studies (PICOS) framework and involved the use of synonyms and medical subject headings (MesH). Search terms were combined with Boolean operators (OR/AND). Results: Nine studies which met the inclusion criteria were selected for the systematic review and meta-analysis, and four distinct areas were identified: the effect of dietary fibre on gut microbiota; the role of dietary fibre on short-chain fatty acids (SCFAs); glycaemic control; and adverse events. There was significant difference (p < 0.01) in the relative abundance of Bifidobacterium with a mean difference of 0.72 (95% CI, 0.56, 0.89) between the dietary fibre group compared with placebo. In relation to the meta-analysis for SCFAs, while there was significant difference (p = 0.02) between the dietary fibre group and placebo with a standardised mean difference of 0.5 (95% CI, 0.08, 0.91) regarding total SCFAs, the differences were not significant (p > 0.05) in relation to acetic acid, propionic acid and butyric acid. There was only significant improvement (p = 0.002) with respect to glycated haemoglobin with a mean difference of −0.18 (95% CI, −0.29, −0.06) between the dietary fibre group and placebo group. Differences between the two groups were not significant (p > 0.05) in relation to fasting blood glucose and homeostatic model assessment of insulin resistance (HOMA-IR). Furthermore, there were no significant differences between the two groups in subjects who reported adverse events. It is possible that the promotion of SCFA producers in greater diversity and abundance by dietary fibre in this review led to improvement in glycated haemoglobin, partly due to increased glucagon-like peptide-1 (GLP-1) production. In addition, Bifidobacterium lactis has been reported to increase glycogen synthesis, decrease expression of hepatic gluconeogenesis genes, improve translocation of glucose transport-4 and promote glucose uptake. It is also possible that the reduction in body weight of participants in the intervention group compared with control may have contributed to the observed improvement in glycated haemoglobin. Conclusion: This systematic review and meta-analysis have demonstrated that dietary fibre can significantly improve (p < 0.05) the relative abundance of Bifidobacterium, total SCFAs and glycated haemoglobin. However, dietary fibre did not appear to have significant effect (p > 0.05) on fasting blood glucose, HOMA-IR, acetic acid, propionic acid, butyric acid and adverse events.

Fecal microbiota transplantation alters the susceptibility of obese rats to type 2 diabetes mellitus

Obesity is one of the susceptibility factors for type 2 diabetes (T2DM), both of which could accelerate the aging of the body and bring many hazards. A causal relationship is present between intestinal microbiota and body metabolism, but how the microbiota play a role in the progression of obesity to T2DM has not been elucidated. In this study, we transplanted healthy or obese-T2DM intestinal microbiota to ZDF and LZ rats, and used 16S rRNA and targeted metabonomics to evaluate the directional effect of the microbiota on the susceptibility of obese rats to T2DM. The glycolipid metabolism phenotype could be changed bidirectionally in obese rats instead of in lean ones. One possible mechanism is that the microbiota and metabolites alter the structure of the intestinal tract, and improve insulin and leptin resistance through JAK2 / IRS / Akt pathway. It is worth noting that 7 genera, such as Lactobacillus, Clostridium and Roche, can regulate 15 metabolites, such as 3-indolpropionic acid, acetic acid and docosahexaenoic acid, and have a significant improvement on glycolipid metabolism phenotype. Attention to intestinal homeostasis may be the key to controlling obesity and preventing T2DM.

Brás N, Mateus N, de Freitas V, Fernandes I. Anthocyanins as Antidiabetic Agents-In Vitro and In Silico Approaches of Preventive and Therapeutic Effects

Many efforts have been made in the past two decades into the search for novel natural and less-toxic anti-diabetic agents. Some clinical trials have assigned this ability to anthocyanins, although different factors like the food source, the amount ingested, the matrix effect and the time of consumption (before or after a meal) seem to result in contradictory conclusions. The possible mechanisms involved in these preventive or therapeutic effects will be discussed-giving emphasis to the latest in vitro and in silico approaches. Therapeutic strategies to counteract metabolic alterations related to hyperglycemia and Type 2 Diabetes Mellitus (T2DM) may include: (a) Inhibition of carbohydrate-metabolizing enzymes; (b) reduction of glucose transporters expression or activity; (c) inhibition of glycogenolysis and (d) modulation of gut microbiota by anthocyanin breakdown products. These strategies may be achieved through administration of individual anthocyanins or by functional foods containing complexes of anthocyanin:carbohydrate:protein.

Management of antibiotic-resistant Helicobacter pylori infection: current perspective in Iran

Helicobacter pylori is a common gastric bacterial pathogen implicated in the pathogenesis of many digestive tract disorders. H. pylori infection prevalence has been reported alarmingly in Iran. A plethora of studies have been conducted to evaluate the efficiency of first-line and second-line eradication attempts in patients diagnosed with H. pylori infections in Iran. The present study, was evaluated the efficacy of first-line and second-line therapy in H. pylori infections in Iran. We aimed to consider the literature review of the various library and electronic databases (Science Direct, PubMed, and Google Scholar) until 2020. The frequency of bacterial resistance to tetracycline, ampicillin, trimethoprim, erythromycin, ofloxacin, and metronidazolewas found to be high in Iran, while the most effective antibiotics were clarithromycin, rifampin, rifampicin, tetracycline, amoxicillin, ciprofloxacin, levofloxacin, moxifloxacin, and azithromycin. The therapeutic choice for H. pylori eradication in Iran could be quadruple therapy using two antibiotics amoxicillin and metronidazole/clarithromycin for the first-line regimen, and a combination of furazolidone plus tetracycline/amoxicillin and bismuth plus proton pump inhibitor for the second-line regimen. Due to increased antibiotic resistance in our region, empirical therapy must be replaced by more targeted treatment based on antimicrobial drug resistance profiles obtained from patients. Although we limited our investigation on the H. pylori eradication regimens in Iran, the results can be generalized to any region as long as the patterns of resistance are the same.

The critical role of Faecalibacterium prausnitzii in human health: An overview

Faecalibacterium prausnitzii (F. prausnitzii) is one of the most abundant bacterial species in the colon of healthy human adults and representing more than 5% of the total bacterial population. Recently, it has been known as a major actor in human intestinal health and a biosensor. Changes in this species population richness and quantity have been observed in many illnesses and several investigations have reported that abundance of F. prausnitzii is reduced in different intestinal disorders. In the current review, we aim to consider literature from various library databases and electronic searches (Science Direct, PubMed, and Google Scholar) which were randomly collected and serve as an overview of different features of F. prausnitzii including metabolites, anti-inflammatory action, and correlation of dysbiosis of this bacterium with various complications in human.

The Beneficial Effects of Lippia Citriodora Extract on Diet-Induced Obesity in Mice Are Associated with Modulation in the Gut Microbiota Composition

SCOPE

Obesity is characterized by a dysfunction in the adipose tissue and an inflammatory subclinical state leading to insulin resistance and increased risk of cardiovascular diseases. It is also associated with intestinal dysbiosis that contributes to inflammation development. Lippia citriodora (LCE) contains high levels of polyphenolpropanoids and has shown promising results in obesity. The aim of this study is to investigate a well-characterized extract of LCE in a model of metabolic syndrome in mice, focusing on its effects on metabolic tissues, endothelial dysfunction, and microbiome.

METHODS

Mice are fed a high fat diet (HFD) for six weeks and treated daily with LCE (1, 10, and 25 mg kg^-1 ). Glucose and lipid metabolism is investigated. The inflammatory state in the metabolic tissues and the intestinal microbiota composition are characterized, as well as the endothelium-dependent vasodilator response to acetylcholine.

RESULTS

LCE reduces fat accumulation and improves plasma glycemic and lipid profiles, as well as the inflammatory process and vascular dysfunction. Moreover, LCE lessens intestinal dysbiosis, as it reduces the Firmicutes/Bacteroidetes ratio and increases Akkermansia abundance in comparison with untreated HFD mice.

CONCLUSION

The antiobesity therapeutic properties of LCE are most probably mediated by the synergic effects of its bioactive compounds.