Exploring the role of gut microbiota in autoimmune thyroid disorders: a systematic review and meta-analysis
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SUBMITTER: Alkader D
PROVIDER: S-EPMC10641821 | biostudies-literature | 2023 Jan
REPOSITORIES: biostudies-literature
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Project description:ObjectivesGut 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.MethodsA 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.ResultsInitially, 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 Alistipes and decreased abundance of Enterobacteriaceae alters purine metabolism, thereby aggravating gout condition. Moreover, a higher abundance of Phascolarctobacterium and Bacteroides in gout modulates enzymatic activity in purine metabolism. Butyrate-producing bacteria such as Faecalibacterium, prausnitzii, Oscillibacter, Butyricicoccus, and Bifidobacterium 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 Enterobacteriaceae, Prevotella, and Bacteroides, are also involved in the pathogenesis of gout disease by stimulating the innate immune system.ConclusionExploring the role of gut dysbiosis in gout and the underlying mechanisms can help develop microbiota-modulating therapies for gout.
| S-EPMC10230090 | biostudies-literature
Project description:ObjectiveThis systematic review sought to comprehensively summarize gut microbiota research in psychiatric disorders following PRISMA guidelines.MethodsLiterature searches were performed on databases using keywords involving gut microbiota and psychiatric disorders. Articles in English with human participants up until February 13, 2020, were reviewed. Risk of bias was assessed using a modified Newcastle-Ottawa Scale for microbiota studies.ResultsSixty-nine of 4231 identified studies met the inclusion criteria for extraction. In most studies, gut microbiota composition differed between individuals with psychiatric disorders and healthy controls; however, limited consistency was observed in the taxonomic profiles. At the genus level, the most replicated findings were higher abundance of Bifidobacterium and lower abundance of Roseburia and Faecalibacterium among patients with psychiatric disorders.ConclusionsGut bacteria that produce short-chain fatty acids, such as Roseburia and Faecalibacterium, could be less abundant in patients with psychiatric disorders, whereas commensal genera, for example, Bifidobacterium, might be more abundant compared with healthy controls. However, most included studies were hampered by methodological shortcomings including small sample size, unclear diagnostics, failure to address confounding factors, and inadequate bioinformatic processing, which might contribute to inconsistent results. Based on our findings, we provide recommendations to improve quality and comparability of future microbiota studies in psychiatry.
| S-EPMC8428865 | biostudies-literature
Project description:Studies suggest that gut dysbiosis occurs in autoimmune neurological diseases, but a comprehensive synthesis of the evidence is lacking. Our aim was to systematically review and meta-analyze the correlation between the gut microbiota and autoimmune neurological disorders to inform clinical diagnosis and therapeutic intervention. We searched the databases of PubMed, Embase, Web of Science, and the Cochrane Library until 1 March 2024 for research on the correlation between gut microbiota and autoimmune neurological disorders. A total of 62 studies provided data and were included in the analysis (n = 3,126 patients, n = 2,843 healthy individuals). Among the included studies, 42 studies provided data on α-diversity. Regarding α-diversity, except for Chao1, which showed a consistent small decrease (SMD = -0.26, 95% CI = -0.45 to -0.07, p < 0.01), other indices demonstrated no significant changes. While most studies reported significant differences in β-diversity, consistent differences were only observed in neuromyelitis optica spectrum disorders. A decrease in short-chain fatty acid (SCFA)-producing bacteria, including Faecalibacterium and Roseburia, was observed in individuals with autoimmune encephalitis, neuromyelitis optica spectrum disorders, myasthenia gravis, and multiple sclerosis. Conversely, an increase in pathogenic or opportunistic pathogens, including Streptococcus and Escherichia-Shigella, was observed in these patients. Subgroup analyses assessed the confounding effects of geography and immunotherapy use. These findings suggest that disturbances of the gut flora are associated with autoimmune neurological diseases, primarily manifesting as non-specific and shared microbial alterations, including a reduction in SCFA-producing bacteria and an increase in pathogenic or opportunistic pathogens.Systematic review registrationhttps://www.crd.york.ac.uk/prospero/, identifier CRD42023410215.
| S-EPMC11839609 | biostudies-literature
Project description:IntroductionIn recent years, it has been described that the dysbiosis of the intestinal microbiota plays a transcendental role in several pathologies. In this sense, the importance of the gut microbiota in the gut-brain axis, with a bidirectional communication, has been demonstrated. Furthermore, the gut microbiota has been linked with mood disorders and neuropsychiatric disorders.MethodsA systematic review of two databases - PubMed and Scopus - was carried out following PRISMA guidelines. We included original studies in humans with a control group published in the last 11 years, which were assessed by the Critical Appraisal Skills Program (CASP) to confirm their quality. Eighteen articles met all the selection criteria.ResultsA review of the articles revealed an association between psychiatric disorders and different bacterial phyla. The studies we have reviewed have demonstrated differences between subjects with psychiatric disorders and controls and highlight a clear relationship between depression, stress, autism spectrum disorder (ASD), psychotic episodes, eating disorders, anxiety and brain function and the gut microbiota composition.ConclusionA reduction of fermentative taxa has been observed in different psychiatric disorders, resulting in a decrease in the production of short-chain fatty acids (SCFAs) and an increase in pro-inflammatory taxa, both of which may be consequences of the exacerbation of these pathologies.
| S-EPMC10435258 | biostudies-literature
Project description:BackgroundSome degree of platelet index abnormality has been found clinically in the autoimmune thyroid disease (AITD), but the findings are not uniform.MethodsThe PubMed, Web of Science, Cochrane Library, and Embase databases were searched for relevant articles published up to August 16th, 2022, with no restrictions on the language of the articles. Reference lists of eligible articles were also searched. A random effect model was used to pool the standardized mean difference (SMD) and 95% confidence interval (95% CI) of platelet count (PLT), mean platelet volume (MPV), and platelet distribution width (PDW) between AITD patients and healthy controls, and subgroup analyses were performed.ResultsA total of 19 articles with 6173 people (3824 AITD patients and 2349 healthy people) were included in the meta-analysis. The results showed that PLT and MPV values were significantly increased in AITD patients when compared with healthy people (SMD: 0.164, 95% CI: 0.044 to 0.285; SMD: 0.256, 95% CI: 0.013 to 0.500), while no significant difference was found in PDW between the AITD group and the control group (SMD: 0.060, 95% CI: -0.164 to 0.284). Subgroup analysis according to disease type and thyroid function revealed that for PLT, this difference was only found in the Hashimoto's thyroiditis (HT) and hypothyroid groups, but not in the Graves' disease (GD) and hyperthyroid groups. For MPV, the results were the opposite of those for PLT: MPV was significantly higher in the GD, hyperthyroid, and euthyroid groups than in the control group, but not in the HT and hypothyroid groups. Sensitivity analysis showed that the stability of the pooled MPV was not good. No publication bias was found.ConclusionsPLT and MPV are significantly elevated in patients with AITD, with PLT being more significantly elevated in HT and hypothyroidism, and MPV being more significantly increased in GD and hyperthyroidism. Appropriate clinical attention can be paid to the thyroid function of patients when abnormal platelet indices are found, and conversely, the consequences of abnormal platelet parameters such as elevated MPV lead to an increased occurrence of cardiovascular events, which should also be addressed in the AITD population.Systematic review registrationhttps://www.crd.york.ac.uk/PROSPERO/, identifier CRD42022341823.
| S-EPMC9812954 | biostudies-literature
Project description:The yak (Bos grunniens) is closely related to common cows (Bos taurus), but is clearly a distinct species. Yaks are of substantial importance to food and leather production in certain high-altitude regions of Asia. The animal is increasing elsewhere as well, mainly because of the perceived health benefits of its milk. Like all ruminants, the animal harbors a complex community of microbial cells in its gut, crucial for its physiology. Despite yaks being important domestic animals, the composition of its gut microbiota and how the composition is guided by its specific high-altitude environment remains largely uncategorized. Hence, online databases (Embase, Medline ALL, Web of Science Core Collection, Cochrane Central Register of Controlled Trials, and Google Scholar) were searched for articles on yak intestinal microbiota. The pooled taxonomic abundance was compared between regions, sexes, different age groups, and feeding patterns. The gut microbiota distribution across different yak intestinal segments was established through pooled average taxonomic abundance. A total of 34 studies met the inclusion criteria and yielded information on 982 unique yak gut microbiota samples. An analysis of overall pooled microbiota revealed a segmented microbial community composition of the yak gut. Yak rumen microbiota was significantly influenced by difference in region, sex, and feeding patterns, the latter factor being dominant in this respect. Yak microbiome is shaped by the feeding strategy and provides an obvious avenue for improving health and productivity of the animal. More generally, the current segmental description of physiological gut microbiome provides insight into how the microbiology of this animal has adapted itself to help comping yaks with its high-altitude habitat.
| S-EPMC9274166 | biostudies-literature
Project description:Emerging research indicates the potential involvement of gut bacteria in the etiology of Graves' Disease (GD). However, the evidence regarding this matter is still conflicting. The primary objective of this investigation was to examine the correlation between gut microbiota and GD. A comprehensive search was conducted of the Cochrane Library, Scopus, Europe PMC, and Medline databases up until August 1, 2023, utilizing a combination of relevant keywords. This review incorporates literature that examined the composition of gut microbiota in patients with GD. We employed random-effect models to analyze the standardized mean difference (SMD) and present the outcomes together with their corresponding 95% confidence intervals (CIs). A total of ten studies were incorporated. The results of our meta-analysis indicated that patients with GD have a reduced alpha diversity of gut microbiota as evidence by a significant reduction of Chao1 (std. mean difference -0.58; 95% CI -0.90, -0.26, p=0.0004; I2 =61%), ACE (std. mean difference -0.64; 95% CI -1.09, -0.18, p=0.006; I2 =77%), and Shannon index (std. mean difference -0.71; 95% CI -1.25, -0.17, p=0.01; I2 =90%) when compared with healthy controls. At the phylum level, the abundance of Firmicutes was reduced in GD patients, while that of Bacteroidetes was increased. This study suggests a notable decrease in the richness and variety of gut microbiota among people diagnosed with GD in comparison with healthy controls.
| S-EPMC11444861 | biostudies-literature
Project description:Polycystic ovary syndrome (PCOS) is the most prevalent endocrine disorder affecting women of reproductive age. PCOS has been associated with distinct metabolic and cardiovascular diseases and with autoimmune conditions, predominantly autoimmune thyroid disease (AITD). AITD has been reported in 18-40% of PCOS women, depending on PCOS diagnostic criteria and ethnicity. The aim of this systematic review and meta-analysis was to summarize the available evidence regarding the likelihood of women with PCOS also having AITD in comparison to a reference group of non-PCOS women. We systematically searched EMBASE and MEDLINE for non-interventional case control, cross-sectional, or cohort studies published until August 2017. The Ottawa-Newcastle Scale was used to assess the methodological quality of studies. Statistical meta-analysis was performed with R. Thirteen studies were selected for the present analysis, including 1,210 women diagnosed with PCOS and 987 healthy controls. AITD was observed in 26.03% and 9.72% of PCOS and control groups respectively. A significant association was detected between PCOS and chance of AITD (OR= 3.27, 95%CI 2.32-4.63). Notably, after geographical stratification, the higher risk of AITD in PCOS women persisted for Asians (OR= 4.56, 95%CI 2.47-8.43), Europeans (OR= 3.27, 95%CI 2.07-5.15), and South Americans (OR= 1.86, 95 %CI 1.05-3.29). AIDT is a frequent condition in PCOS patients, and might affect thyroid function. Thus, screening for thyroid function and thyroid-specific autoantibodies should be considered in patients with PCOS even in the absence of overt symptoms. This systematic review and meta-analysis is registered in PROSPERO under number CRD42017079676.
| S-EPMC6215798 | biostudies-literature
Project description:BackgroundPrevious 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.MethodsWe 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.ResultsAmong 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.ConclusionsWe 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.
| S-EPMC8903526 | biostudies-literature
Project description:BackgroundThere is overlap between movement disorders and neuroendocrine abnormalities.Objectives and methodsTo provide a systematic review on the association of thyroid dysfunction and movement disorders. Thyroid physiological function and classical thyroid disorders highlighting typical and atypical manifestations including movement disorders, as well as diagnostic procedures, and treatments are discussed.ResultsHypothyroidism may be associated with hypokinetic and hyperkinetic disorders. There is debate whether their concomitance reflects a causal link, is coincidence, or the result of one unmasking the other. Hypothyroidism-associated parkinsonism may resemble idiopathic Parkinson's disease. Hypothyroidism-associated hyperkinetic disorders mainly occur in the context of steroid-responsive encephalopathy with autoimmune thyroiditis, that is, Hashimoto disease, mostly manifesting with tremor, myoclonus, and ataxia present in 28-80%, 42-65% and 33-65% in larger series. Congenital hypothyroidism manifesting with movement disorders, mostly chorea and dystonia, due to Mendelian genetic disease are rare.Hyperthyroidism on the other hand mostly manifests with hyperkinetic movement disorders, typically tremor (present in three quarters of patients). Chorea (present in about 2% of hyperthyroid patients), dystonia, myoclonus, ataxia and paroxysmal movement disorders, as well as parkinsonism have also been reported, with correlation between movement intensity and thyroid hormone levels.On a group level, studies on the role of thyroid dysfunction as a risk factor for the development of PD remain non-conclusive.ConclusionsIn view of the treatability of movement disorders associated with thyroid disease, accurate diagnosis is important. The pathophysiology remains poorly understood. More detailed case documentation and systematic studies, along with experimental studies are needed.
| S-EPMC10026317 | biostudies-literature