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CNS Neuroscience & Therapeutics Jan 2023Recent advances have highlighted the relationships between gut dysbiosis and Parkinson's disease (PD). Microbiota transplantation from PD patients to mice can induce... (Review)
Review
INTRODUCTION
Recent advances have highlighted the relationships between gut dysbiosis and Parkinson's disease (PD). Microbiota transplantation from PD patients to mice can induce increased alpha-synuclein-mediated motor deficits. Human studies have identified differences in the gut microbiota of PD patients compared to healthy controls. We undertook a systematic review to evaluate the available evidence for the involvement of gut bacteria in the etiology of PD.
METHODS
The PubMed databank, the China National Knowledge Infrastructure databank, and Wanfang Data were searched from inception until June 2021 to identify human case-control studies that investigated relationships between PD and microbiota quantified from feces. We evaluated the resulting studies focusing on bacterial taxa that were different between PD patients and healthy controls.
RESULTS
Twenty-six studies were found in which 53 microbial families and 98 genera exhibited differences between patients with PD and healthy controls. The genera identified by more than two studies as increased in PD were Bifidobacterium, Alistipes, Christensenella, Enterococcus, Oscillospira, Bilophila, Desulfovibrio, Escherichia/Shigella, and Akkermansia, while Prevotella, Blautia, Faecalibacterium, Fusicatenibacter, and Haemophilus had three or more reports of being lower in PD patients. More than one report demonstrated that Bacteroides, Odoribacter, Parabacteroides, Butyricicoccus, Butyrivibrio, Clostridium, Coprococcus, Lachnospira, Lactobacillus, Megasphaera, Phascolarctobacterium, Roseburia, Ruminococcus, Streptococcus, and Klebsiella were altered in both directions.
CONCLUSION
Our review shows that the involvement of the gut microbiome in the etiology of PD may involve alterations of short-chain fatty acids (SCFAs)-producing bacteria and an increase in putative gut pathobionts. SCFAs-producing bacteria may vary above or below an "optimal range," causing imbalances. Considering that Bifidobacterium, Lactobacillus, and Akkermansia are beneficial for human health, increased Bifidobacterium and Lactobacillus in the PD gut microbiome may be associated with PD medications, especially COMT inhibitors, while a high level of Akkermansia may be associated with aging.
Topics: Humans; Animals; Mice; Parkinson Disease; Gastrointestinal Microbiome; Bacteria; Feces; Fatty Acids, Volatile
PubMed: 36284437
DOI: 10.1111/cns.13990 -
Frontiers in Psychiatry 2019Recently discovered relationships between the gastrointestinal microbiome and the brain have implications for psychiatric disorders, including major depressive disorder...
Recently discovered relationships between the gastrointestinal microbiome and the brain have implications for psychiatric disorders, including major depressive disorder (MDD). Bacterial transplantation from MDD patients to rodents produces depression-like behaviors. In humans, case-control studies have examined the gut microbiome in healthy and affected individuals. We systematically reviewed existing studies comparing gut microbial composition in MDD and healthy volunteers. A PubMed literature search combined the terms "depression," "depressive disorder," "stool," "fecal," "gut," and "microbiome" to identify human case-control studies that investigated relationships between MDD and microbiota quantified from stool. We evaluated the resulting studies, focusing on bacterial taxa that were different between MDD and healthy controls. Six eligible studies were found in which 50 taxa exhibited differences ( < 0.05) between patients with MDD and controls. Patient characteristics and methodologies varied widely between studies. Five phyla-, and -were represented; however, divergent results occurred across studies for all phyla. The largest number of differentiating taxa were within phylum , in which nine families and 12 genera differentiated the diagnostic groups. The majority of these families and genera were found to be statistically different between the two groups in two identified studies. Family differentiated the diagnostic groups in four studies (with an even split in directionality). Across all five phyla, nine genera were higher in MDD (, and ), six were lower (, and ), and six were divergent (, and ). We highlight mechanisms and products of bacterial metabolism as they may relate to the etiology of depression. No consensus has emerged from existing human studies of depression and gut microbiome concerning which bacterial taxa are most relevant to depression. This may in part be due to differences in study design. Given that bacterial functions are conserved across taxonomic groups, we propose that studying microbial functioning may be more productive than a purely taxonomic approach to understanding the gut microbiome in depression.
PubMed: 30804820
DOI: 10.3389/fpsyt.2019.00034 -
Frontiers in Cellular and Infection... 2022Evidence of gut microbiota involvement in regulating glucose metabolism and type 2 diabetes mellitus (T2DM) progression is accumulating. The understanding of microbial... (Review)
Review
Evidence of gut microbiota involvement in regulating glucose metabolism and type 2 diabetes mellitus (T2DM) progression is accumulating. The understanding of microbial dysbiosis and specific alterations of gut microbiota composition that occur during the early stages of glucose intolerance, unperturbed by anti-diabetic medications, is especially essential. Hence, this systematic review was conducted to summarise the existing evidence related to microbiota composition and diversity in individuals with prediabetes (preDM) and individuals newly diagnosed with T2DM (newDM) in comparison to individuals with normal glucose tolerance (nonDM). A systematic search of the PubMed, MEDLINE and CINAHL databases were conducted from inception to February 2021 supplemented with manual searches of the list of references. The primary keywords of "type 2 diabetes", "prediabetes", "newly-diagnosed" and "gut microbiota" were used. Observational studies that conducted analysis of the gut microbiota of respondents with preDM and newDM were included. The quality of the studies was assessed using the modified Newcastle-Ottawa scale by independent reviewers. A total of 18 studies (5,489 participants) were included. Low gut microbial diversity was generally observed in preDM and newDM when compared to nonDM. Differences in gut microbiota composition between the disease groups and nonDM were inconsistent across the included studies. Four out of the 18 studies found increased abundance of phylum along with decreased abundance of in newDM. At the genus/species levels, decreased abundance of , , , and and increased abundance of , a, and were observed in the disease groups in at least two studies. was also found to positively correlate with fasting plasma glucose (FPG), HbA1c and/or homeostatic assessment of insulin resistance (HOMA-IR) in four studies. This renders a need for further investigations on the species/strain-specific role of endogenously present in glucose regulation mechanism and T2DM disease progression. Differences in dietary intake caused significant variation in specific bacterial abundances. More studies are needed to establish more consistent associations, between clinical biomarkers or dietary intake and specific gut bacterial composition in prediabetes and early T2DM.
Topics: Bacteroidetes; Diabetes Mellitus, Type 2; Gastrointestinal Microbiome; Glucose; Humans; Microbiota; Verrucomicrobia
PubMed: 36046745
DOI: 10.3389/fcimb.2022.943427 -
Gut microbiota in patients with Alzheimer's disease spectrum: a systematic review and meta-analysis.Aging Jan 2022Gut dysbiosis has been proposed as one of pathologies in patients with Alzheimer's disease (AD) spectrum. Despite such enthusiasm, the relevant results remain... (Meta-Analysis)
Meta-Analysis
CONTEXT
Gut dysbiosis has been proposed as one of pathologies in patients with Alzheimer's disease (AD) spectrum. Despite such enthusiasm, the relevant results remain substantially controversial.
OBJECTIVE
A systematic review and meta-analysis were performed to investigate the differences of gut microbiota (GM) between patients with AD spectrum (including mild cognitive impairment [MCI] and AD) and healthy controls (HC).
DATA SOURCES
PubMed, MEDLINE, Scopus, and Cochrane Library from January 2000 to August 2021. Eligibility criteria for study selection: Observational trials and pre-intervention data of intervention trials that investigated the abundance of GM in patients with AD spectrum and HC.
DATA EXTRACTION AND SYNTHESIS
Two reviewers independently identified articles, extracted data, and evaluated the risk of bias. The effect sizes were performed by a random-effect, inverse-variance weighted model. The effects of different countries and of clinical stages on GM abundance were also examined.
RESULTS
11 studies consisting of 378 HC and 427 patients with AD spectrum were included in the meta-analysis. Patients with AD, but not MCI, showed significantly reduced GM diversity as compared to HC. We also found more abundance of , and , but less abundance of , , and in patients with AD spectrum as compared with HC. The profiles of abundance of and in HC and AD spectrum were differentially affected by countries. Finally, when considering clinical stage as a moderator, the comparisons of abundance in and showed large effect sizes, with gradient changes from MCI to AD stage.
LIMITATIONS
The inclusion of studies originating only from China and the U.S. was a possible limitation.
CONCLUSIONS
Patients with AD spectrum demonstrated altered GM abundance, which was differentially mediated by countries and clinical stages.
Topics: Aged; Alzheimer Disease; Bacteria; Female; Gastrointestinal Microbiome; Humans; Male; Middle Aged
PubMed: 35027502
DOI: 10.18632/aging.203826 -
Microorganisms Jul 2023Gestational diabetes, affecting about 10% of pregnancies, is characterized by impaired glucose regulation and can lead to complications for health of pregnant women and... (Review)
Review
Gestational diabetes, affecting about 10% of pregnancies, is characterized by impaired glucose regulation and can lead to complications for health of pregnant women and their offspring. The microbiota, the resident microbes within the body, have been linked to the development of several metabolic conditions. This systematic review with meta-analysis aims to summarize the evidence on the differences in microbiota composition in pregnant women with gestational diabetes and their offspring compared to healthy pregnancies. A thorough search was conducted in the PubMed, Scopus, and Web of Science databases, and data from 21 studies were analyzed utilizing 41 meta-analyses. In the gut microbiota, Bifidobacterium and Alistipes were found to be more abundant in healthy pregnancies, while Roseburia appears to be more abundant in gestational diabetes. The heterogeneity among study findings regarding the microbiota in the meconium is considerable. The placental microbiota exhibited almost no heterogeneity, with an increased abundance of Firmicutes in the gestational diabetes group and a higher abundance of Proteobacteria in the control. The role of the microbiota in gestational diabetes is reinforced by these findings, which additionally point to the potential of microbiome-targeted therapies. To completely comprehend the interactions between gestational diabetes and the microbiome, standardizing methodologies and further research is necessary.
PubMed: 37512921
DOI: 10.3390/microorganisms11071749 -
Genes & Nutrition Jan 2022Previous observational studies have demonstrated inconsistent and inconclusive results of changes in the intestinal microbiota in patients with obesity and metabolic... (Review)
Review
BACKGROUND
Previous observational studies have demonstrated inconsistent and inconclusive results of changes in the intestinal microbiota in patients with obesity and metabolic disorders. We performed a systematic review to explore evidence for this association across different geography and populations.
METHODS
We performed a systematic search of MEDLINE (OvidSP) and Embase (OvidSP) of articles published from Sept 1, 2010, to July 10, 2021, for case-control studies comparing intestinal microbiome of individuals with obesity and metabolic disorders with the microbiome of non-obese, metabolically healthy individuals (controls). The primary outcome was bacterial taxonomic changes in patients with obesity and metabolic disorders as compared to controls. Taxa were defined as "lean-associated" if they were depleted in patients with obesity and metabolic disorders or negatively associated with abnormal metabolic parameters. Taxa were defined as "obesity-associated" if they were enriched in patients with obesity and metabolic disorders or positively associated with abnormal metabolic parameters.
RESULTS
Among 2390 reports screened, we identified 110 full-text articles and 60 studies were included. Proteobacteria was the most consistently reported obesity-associated phylum. Thirteen, nine, and ten studies, respectively, reported Faecalibacterium, Akkermansia, and Alistipes as lean-associated genera. Prevotella and Ruminococcus were obesity-associated genera in studies from the West but lean-associated in the East. Roseburia and Bifidobacterium were lean-associated genera only in the East, whereas Lactobacillus was an obesity-associated genus in the West.
CONCLUSIONS
We identified specific bacteria associated with obesity and metabolic disorders in western and eastern populations. Mechanistic studies are required to determine whether these microbes are a cause or product of obesity and metabolic disorders.
PubMed: 35093025
DOI: 10.1186/s12263-021-00703-6 -
Journal of Zhejiang University.... Dec 2022: Osteoporosis (OP) has become a major public health issue, threatening the bone health of middle-aged and elderly people from all around the world. Changes in the gut... (Meta-Analysis)
Meta-Analysis
: Osteoporosis (OP) has become a major public health issue, threatening the bone health of middle-aged and elderly people from all around the world. Changes in the gut microbiota (GM) are correlated with the maintenance of bone mass and bone quality. However, research results in this field remain highly controversial, and no systematic review or meta-analysis of the relationship between GM and OP has been conducted. This paper addresses this shortcoming, focusing on the difference in the GM abundance between OP patients and healthy controls based on previous 16S ribosomal RNA (rRNA) gene sequencing results, in order to provide new clinical reference information for future customized prevention and treatment options of OP. : According to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA), we comprehensively searched the databases of PubMed, Web of Science, Embase, Cochrane Library, and China National Knowledge Infrastructure (CNKI). In addition, we applied the R programming language version 4.0.3 and Stata 15.1 software for data analysis. We also implemented the Newcastle-Ottawa Scale (NOS), funnel plot analysis, sensitivity analysis, Egger's test, and Begg's test to assess the risk of bias. : This research ultimately considered 12 studies, which included the fecal GM data of 2033 people (604 with OP and 1429 healthy controls). In the included research papers, it was observed that the relative abundance of and increased in the OP group, while the relative abundance for of Bacteroidetes increased (except for Ireland). Meanwhile, Firmicutes, , , , and showed reduced relative abundance in Chinese studies. In the linear discriminant analysis Effect Size (LEfSe) analysis, certain bacteria showed statistically significant results consistently across different studies. : This observational meta-analysis revealed that changes in the GM were correlated with OP, and variations in some advantageous GM might involve regional differences.
Topics: Aged; Humans; Middle Aged; Feces; Gastrointestinal Microbiome; Genes, rRNA; Osteoporosis; RNA, Ribosomal, 16S
PubMed: 36518053
DOI: 10.1631/jzus.B2200344 -
Frontiers in Medicine 2023Gut dysbiosis is believed to be one of the several mechanisms that are involved in the pathogenesis of gout. This systematic review aimed to summarize the role of gut...
OBJECTIVES
Gut dysbiosis is believed to be one of the several mechanisms that are involved in the pathogenesis of gout. This systematic review aimed to summarize the role of gut dysbiosis in gout disease and uncover the underlying mechanisms.
METHODS
A comprehensive search was conducted on PubMed, Web of Science, and Scopus databases up to October 2021. Animal studies and human observational studies, including case-control, cross-sectional, and cohort studies assessing the association between gut microbiota composition and gout were included. The quality of included studies has been evaluated using the Newcastle-Ottawa Quality Assessment scale (NOS) and the SYRCLE's risk of bias tool.
RESULTS
Initially, we found 274 studies among which 15 studies were included in this systematic review. Of them, 10 studies were conducted on humans and 5 studies were conducted on animals. Increased abundance of and decreased abundance of alters purine metabolism, thereby aggravating gout condition. Moreover, a higher abundance of and in gout modulates enzymatic activity in purine metabolism. Butyrate-producing bacteria such as , and have higher abundance in healthy controls compared to gout patients, suggesting the anti-inflammatory and anti-microbial role of short-chain fatty acids (SCFAs). Lipopolysaccharides (LPS)-releasing bacteria, such as e, , and , are also involved in the pathogenesis of gout disease by stimulating the innate immune system.
CONCLUSION
Exploring the role of gut dysbiosis in gout and the underlying mechanisms can help develop microbiota-modulating therapies for gout.
PubMed: 37265486
DOI: 10.3389/fmed.2023.1163778 -
Spinal Cord Apr 2022Systematic review. (Review)
Review
STUDY DESIGN
Systematic review.
OBJECTIVES
To investigate the changes in the microbiome among human and animal populations with spinal cord injury (SCI).
METHODS
Four databases (EMBASE, Medline (Ovid), Web of Science, Cochrane Central Register of Trials (CENTRAL)) and Google Scholar were searched. No language restrictions were applied. Data extraction was done in parallel and independently by two reviewers. The search was last conducted on 07 April 2021.
RESULTS
There were 6869 studies retrieved, 43 full-text studies reviewed, and 19 studies included. There were seven animal gut studies, six human gut studies, and six urinary tract studies identified. There were no publications found on other body sites. Among the included studies, we observed a consistent and significant difference in gut microbiome composition between populations with SCI and able-bodied populations. This is characterized by a decrease in beneficial butyrate-producing bacteria (Faecalbacterium, Megamonas, Roseburia) and an increase in inflammation-associated bacteria (Alistipes, Anaerotruncus, and Lachnoclostridium). On the other hand, the urine of individuals with SCI was polymicrobial and members of Enterobacteriaceae (Escherichia coli, Klebsiella pneumoniae) were frequently observed. Probiotics were shown to induce a significant but transient shift in the urinary tract microbiome. The studies had low to moderate risks of bias.
CONCLUSIONS
There are limited studies on the changes in microbiome among SCI populations. The gut microbiome was characterized by bacterial profiles associated with chronic inflammation and metabolic disorder while the studies of the urinary tract microbiome show the dominance of bacterial genera associated with urinary tract infection.
Topics: Animals; Bacteria; Gastrointestinal Microbiome; Humans; Inflammation; Metabolic Diseases; Probiotics; Spinal Cord Injuries
PubMed: 34992210
DOI: 10.1038/s41393-021-00737-y -
Revista Espanola de Enfermedades... Nov 2015The human colonic mucosa is populated by a wide range of microorganisms, usually in a symbiotic relation with the host. Sometimes this balance is lost and a state of... (Meta-Analysis)
Meta-Analysis Review
BACKGROUND AND AIM
The human colonic mucosa is populated by a wide range of microorganisms, usually in a symbiotic relation with the host. Sometimes this balance is lost and a state of dysbiosis arises, exposing the colon to different metabolic and inflammatory stimuli (according to the microbiota's changing profile). Recent findings lead to hypothesize that this unbalance may create a subclinical pro-inflammatory state that increases DNA mutations and, therefore, colorectal carcinogenesis. In this article we aim to systematically review the scientific evidence regarding colonic microbiota and its role in colorectal carcinogenesis.
METHODS
Systematic review of PubMed searching results for original articles studying microbiota and colorectal cancer until November 2014.
RESULTS
Thirty-one original articles studied the role of colon microbiota in colorectal carcinoma including both human and animal studies. Different and heterogeneous methods were used and different bacteria were considered. Nevertheless, some bacteria are consistently augmented (such as Fusobacteria, Alistipes, Porphyromonadaceae, Coriobacteridae, Staphylococcaceae, Akkermansia spp. and Methanobacteriales), while other are constantly diminished in colorectal cancer (such as Bifidobacterium, Lactobacillus, Ruminococcus, Faecalibacterium spp., Roseburia, and Treponema). Moreover, bacteria metabolites amino acids are increased and butyrate is decreased throughout colonic carcinogenesis.
CONCLUSION
Conclusive evidence shows that colorectal carcinogenesis is associated with microbial dysbiosis. This information may be used to create new prophylactic, diagnostic and therapeutic strategies for colorectal cancer.
Topics: Animals; Carcinogenesis; Colon; Colorectal Neoplasms; Dysbiosis; Humans; Microbiota
PubMed: 26541655
DOI: 10.17235/reed.2015.3830/2015