Gut microbiota modulate distal symmetric polyneuropathy in patients with diabetes

Molecular mechanisms of enteric neuropathies in high-fat diet feeding and diabetes

BACKGROUND

Obesity and diabetes are associated with altered gastrointestinal function and with the development of abdominal pain, nausea, diarrhea, and constipation among other symptoms. The enteric nervous system (ENS) regulates gastrointestinal motility. Enteric neuropathies defined as damage or loss of enteric neurons can lead to motility disorders.

PURPOSE

Here, we review the molecular mechanisms that drive enteric neurodegeneration in diabetes and obesity, including signaling pathways leading to neuronal cell death, oxidative stress, and microbiota alteration. We also highlight potential approaches to treat enteric neuropathies including antioxidant therapy to prevent oxidative stress-induced damage and the use of stem cells.

Causal relationships between gut microbiota, gut metabolites, and diabetic neuropathy: A mendelian randomization study

BACKGROUND

Previous studies have shown a strong correlation between gut microbiota and diabetes and its associated complications. We aimed to evaluate the causal relationships between the gut microbiota, gut metabolites, and diabetic neuropathy.

METHODS

Summary statistics of 211 gut microbiota and 12 gut-related metabolites (β-hydroxybutyric acid, betaine, trimethylamine-N-oxide, carnitine, choline, glutamate, kynurenine, phenylalanine, propionic acid, serotonin, tryptophan, and tyrosine) were obtained from previous genome-wide association studies (GWAS). A two-sample Mendelian randomization (MR) design was used to estimate the effects of gut microbiota and gut metabolites on the risk of diabetic neuropathy based on FinnGen GWAS.

RESULTS

Higher levels of Acidaminococcaceae (OR = 0.62; 95%CI = 0.46 to 0.84; P = 0.002), Peptococcaceae (OR = 0.70; 95%CI = 0.54 to 0.90; P = 0.006), and Eubacterium coprostanoligenes group (OR = 0.68; 95%CI = 0.50 to 0.93; P = 0.016) are genetically determined to provide protection against diabetic neuropathy. Conversely, the presence of Alistipes (OR = 1.65; 95%CI = 1.18 to 2.31; P = 0.003), ChristensenellaceaeR7 group (OR = 1.52; 95%CI = 1.03 to 2.23; P = 0.033), Eggerthella (OR = 1.28; 95%CI = 1.05 to 1.55; P = 0.014), RuminococcaceaeUCG013 (OR = 1.35; 95%CI = 1.01 to 1.82; P = 0.046), and Firmicutes (OR = 1.42; 95%CI = 1.05 to 1.93; P = 0.023) increases the risk of diabetic neuropathy. Moreover, a correlation has been identified between diabetic neuropathy and two gut metabolites: betaine (OR = 0.95; 95%CI = 0.90 to 1.00; P = 0.033) and tyrosine (OR = 1.03; 95%CI = 1.01 to 1.06; P = 0.019). Sensitivity analysis indicated robust results with no sign of heterogeneity or pleiotropy.

CONCLUSION

The present study elucidated the impact of specific gut microbiota and gut metabolites on the susceptibility to diabetic neuropathy. Interventions targeting the improvement of the gut microbiota diversity and composition hold considerable promise as a potential strategy.

Effects of gut microbiome on type 1 diabetes susceptibility and complications: A large-scale bidirectional Mendelian randomization and external validation study

AIM

To assess and verify the effect of the gut microbiome on the susceptibility and complications of type 1 diabetes (T1D).

MATERIALS AND METHODS

To achieve this aim, a two-sample and reverse Mendelian randomization (MR) analysis was conducted. In addition, an external validation study was performed using individual microbiome data of patients with T1D from the gutMEGA datasets and the National Clinical Research Center for Metabolic Diseases. The circulating metabolites facilitated two-sample MR analysis, mediation and multivariable MR analysis to evaluate the direct relationship between the gut microbiome and T1D complications.

RESULTS

The MR analysis results from the discovery and validation phases confirmed that Veillonellaceae can potentially reduce the susceptibility of T1D. In the gutMEGA dataset, the average relative abundance of Veillonellaceae in patients with T1D was 0.66%, compared with 1.09% in the controls. Furthermore, the external validation, which included 60 patients with T1D and 30 matched healthy controls, found that the median relative abundance of Veillonellaceae was also lower than controls at 1.10% (95% CI 0.50%-1.80%). Specifically, the Eubacterium coprostanoligenes group, known for its ability to regulate cholesterol, was significantly associated with a lower risk of developing renal, neurological and ophthalmic complications in T1D. Moreover, high cholesterol in small high-density lipoprotein and cholesteryl esters in high-density lipoprotein were associated with a reduced risk of T1D renal and ophthalmic complications. The mediation and multivariable MR analysis combining cholesterol indicated that the E. coprostanoligenes group is the most dominant factor influencing T1D complications.

CONCLUSIONS

Our findings supported the potential causal effect of gut microbiota on the susceptibility and complications of T1D.

Guild-level signature of gut microbiome for diabetic kidney disease

Current microbiome signatures for chronic diseases such as diabetic kidney disease (DKD) are mainly based on low-resolution taxa such as genus or phyla and are often inconsistent among studies. In microbial ecosystems, bacterial functions are strain specific, and taxonomically different bacteria tend to form co-abundance functional groups called guilds. Here, we identified guild-level signatures for DKD by performing in-depth metagenomic sequencing and conducting genome-centric and guild-based analysis on fecal samples from 116 DKD patients and 91 healthy subjects. Redundancy analysis on 1,543 high-quality metagenome-assembled genomes (HQMAGs) identified 54 HQMAGs that were differentially distributed among the young healthy control group, elderly healthy control group, early-stage DKD patients (EDG), and late-stage DKD patients (LDG). Co-abundance network analysis classified the 54 HQMAGs into two guilds. Compared to guild 2, guild 1 contained more short-chain fatty acid biosynthesis genes and fewer genes encoding uremic toxin indole biosynthesis, antibiotic resistance, and virulence factors. Guild indices, derived from the total abundance of guild members and their diversity, delineated DKD patients from healthy subjects and between different severities of DKD. Age-adjusted partial Spearman correlation analysis showed that the guild indices were correlated with DKD disease progression and with risk indicators of poor prognosis. We further validated that the random forest classification model established with the 54 HQMAGs was also applicable for classifying patients with end-stage renal disease and healthy subjects in an independent data set. Therefore, this genome-level, guild-based microbial analysis strategy may identify DKD patients with different severity at an earlier stage to guide clinical interventions.

IMPORTANCE

Traditionally, microbiome research has been constrained by the reliance on taxonomic classifications that may not reflect the functional dynamics or the ecological interactions within microbial communities. By transcending these limitations with a genome-centric and guild-based analysis, our study sheds light on the intricate and specific interactions between microbial strains and diabetic kidney disease (DKD). We have unveiled two distinct microbial guilds with opposite influences on host health, which may redefine our understanding of microbial contributions to disease progression. The implications of our findings extend beyond mere association, providing potential pathways for intervention and opening new avenues for patient stratification in clinical settings. This work paves the way for a paradigm shift in microbiome research in DKD and potentially other chronic kidney diseases, from a focus on taxonomy to a more nuanced view of microbial ecology and function that is more closely aligned with clinical outcomes.

The causal relationship between gut microbiota and diabetic neuropathy: a bi-directional two-sample Mendelian randomization study

Background

Many studies suggest a strong correlation between gut microbiota (GM) and diabetic neuropathy (DN). However, the precise causal relationship between GM and DN has yet to be fully elucidated. Hence, a bi-directional Mendelian randomization (MR) analysis was used to examine the association between GM and DN.

Methods

Widely known genome-wide association study (GWAS) of GM was collected from the MiBio Gen project. Summary-level datasets for DN were taken from the FinnGen project. Inverse variance weighted approach was used for evaluating the causal relationship between GM and DN. Subsequently, pleiotropy and heterogeneity tests were performed to verify the reliability of the data. Furthermore, a bidirectional two-sample MR analysis was done to investigate the directionality of the causal relationships. Gene Ontology analysis was conducted to identify the associations that could indicate biological functions.

Results

We identified potential causal associations between GM and DN (p< 0.05 in all three MR methods). Among them, we found increased levels of Christensenellaceae R-7 (Odds ratio, OR= 1.52; 95% confidence interval, CI = 1.03-2.23; p = 0.03), Ruminococcaceae UCG013 (OR =1.35; 95% CI = 1.00-1.85; p = 0.04), and Eggerthella groups (OR = 1.27; 95% CI = 1.05-1.55; p = 0.01), which may be associated with a higher risk of DN, while increased levels of Peptococcaceae (OR = 0.69; 95% CI = 0.54-0.90; p< 0.01) and Eubacterium coprostanoligenes groups (OR = 0.68; 95% CI = 0.49-0.93; p = 0.01) could be associated with a lower risk. Gene Ontology pathway analysis revealed enrichment of genes regulated by the associated single-nucleotide polymorphisms (SNPs) in the apical plasma membrane, glycosyltransferase activity, hexosyltransferase activity and membrane raft. Reverse MR analyses indicated that DN was associated with five microbial taxa in all three MR methods.

Conclusion

The results of our study validate the possible causative relationship between GM and DN. This discovery gives new perspectives into the mechanism on how GM influences DN, and establishes a theoretical foundation for future investigations into targeted preventive measures.

Characteristics of gut microbiome in patients with pediatric solid tumor

Background

Pediatric solid tumors are a common malignant disease in children, and more and more studies have proved that there is an inseparable relationship between adult tumors and intestinal microbiome, but the changes in the intestinal microbiota of pediatric solid tumor (PST) patients have been scarcely examined. This study aims to examine the differences in the intestinal microbiota features between patients diagnosed with PST and healthy controls (HCs).

Methods

To elucidate the unique characteristics of the gut microbiota in pediatric patients with solid tumors, we recruited 23 PST patients and 20 HCs. A total of 43 stool samples were gathered, and then 16S rRNA sequencing was performed.

Results

We noticed a noticeable pattern of elevated diversity in the gut microbiota within the PST groups. The differences in microbial communities among two groups were remarkable, regarding the analysis at the class level, the abundance of Bacilli was markedly increased in PST patients compared to HCs (P < 0.05), regarding the analysis at the genus level, The presence of Enterococcus was significantly higher in PST cases compared to HCs (P < 0.01), while Lachnospiraceae unclassified, Lachnospira, Haemophilus and Colidextribacter in PST cases, the abundance was significantly reduced. (P < 0.05), 6 genera, including Bacilli, Lactobacillales, Enterococcaceae and Morganella, showed a significant enrichment compared to healthy controls, while 10 genera, including Bilophila, Colidextribacter, Pasteurellales, Haemophilus, Lachnospiraceae unclassified, Lachnospira and Fusobacteriales, were significant reduction in the PST groups.

Conclusion

Our research conducted the characterization analysis of the gut microbiota in PST patients for the first time. More importantly, there are some notable differences in the gut microbiota between PST patients and healthy controls, which we believe is an interesting finding.

Discovery of first-in-class highly selective TRPV1 antagonists with dual analgesic and hypoglycemic effects

Analgesia and blood sugar control are considered as two main unmet clinical needs for diabetes related neuropathic pain patients. Transient receptor potential vanilloid type-1 (TRPV1) channel is a highly validated target for pain perception, while no TRPV1 antagonists have been approved due to hyperthermia side effects. Herein, two series of new TRPV1 antagonists with flavonoid skeleton were designed by the structure-based drug design (SBDD) strategy. After comprehensive evaluation, compound CX-3 was identified as a promising TRPV1 antagonist. CX-3 exhibited equivalent TRPV1 antagonistic activity with classical TRPV1 antagonist BCTC in vitro, and exerted better analgesic activity in vivo than that of BCTC in the formalin induced inflammatory pain model without hyperthermia risk. Moreover, CX-3 exhibited robust glucose-lowering effects and showed high selectivity over other ion channels. Overall, these findings identified a first-in-class highly selective TRPV1 antagonist CX-3, which is a promising candidate to target the pathogenesis of diabetes related neuropathic pain.

Advances in fecal microbiota transplantation for the treatment of diabetes mellitus

Diabetes mellitus (DM) refers to a group of chronic diseases with global prevalence, characterized by persistent hyperglycemia resulting from various etiologies. DM can harm various organ systems and lead to acute or chronic complications, which severely endanger human well-being. Traditional treatment mainly involves controlling blood sugar levels through replacement therapy with drugs and insulin; however, some patients still find a satisfactory curative effect difficult to achieve. Extensive research has demonstrated a close correlation between enteric dysbacteriosis and the pathogenesis of various types of DM, paving the way for novel therapeutic approaches targeting the gut microbiota to manage DM. Fecal microbiota transplantation (FMT), a method for re-establishing the intestinal microbiome balance, offers new possibilities for treating diabetes. This article provides a comprehensive review of the correlation between DM and the gut microbiota, as well as the current advancements in FMT treatment for DM, using FMT as an illustrative example. This study aims to offer novel perspectives and establish a theoretical foundation for the clinical diagnosis and management of DM.

Oral-gut microbial transmission promotes diabetic coronary heart disease

BACKGROUND

Diabetes is a predominant driver of coronary artery disease worldwide. This study aims to unravel the distinct characteristics of oral and gut microbiota in diabetic coronary heart disease (DCHD). Simultaneously, we aim to establish a causal link between the diabetes-driven oral-gut microbiota axis and increased susceptibility to diabetic myocardial ischemia-reperfusion injury (MIRI).

METHODS

We comprehensively investigated the microbial landscape in the oral and gut microbiota in DCHD using a discovery cohort (n = 183) and a validation chohort (n = 68). Systematically obtained oral (tongue-coating) and fecal specimens were subjected to metagenomic sequencing and qPCR analysis, respectively, to holistically characterize the microbial consortia. Next, we induced diabetic MIRI by administering streptozotocin to C57BL/6 mice and subsequently investigated the potential mechanisms of the oral-gut microbiota axis through antibiotic pre-treatment followed by gavage with specific bacterial strains (Fusobacterium nucleatum or fecal microbiota from DCHD patients) to C57BL/6 mice.

RESULTS

Specific microbial signatures such as oral Fusobacterium nucleatum and gut Lactobacillus, Eubacterium, and Roseburia faecis, were identified as potential microbial biomarkers in DCHD. We further validated that oral Fusobacterium nucleatum and gut Lactobacillus are increased in DCHD patients, with a positive correlation between the two. Experimental evidence revealed that in hyperglycemic mice, augmented Fusobacterium nucleatum levels in the oral cavity were accompanied by an imbalance in the oral-gut axis, characterized by an increased coexistence of Fusobacterium nucleatum and Lactobacillus, along with elevated cardiac miRNA-21 and a greater extent of myocardial damage indicated by TTC, HE, TUNEL staining, all of which contributed to exacerbated MIRI.

CONCLUSION

Our findings not only uncover dysregulation of the oral-gut microbiota axis in diabetes patients but also highlight the pivotal intermediary role of the increased abundance of oral F. nucleatum and gut Lactobacillus in exacerbating MIRI. Targeting the oral-gut microbiota axis emerges as a potent strategy for preventing and treating DCHD. Oral-gut microbial transmission constitutes an intermediate mechanism by which diabetes influences myocardial injury, offering new insights into preventing acute events in diabetic patients with coronary heart disease.

Altered gut microbiota in Taiwanese A97S predominant transthyretin amyloidosis with polyneuropathy

Increasing evidence suggests that gut microbiota alterations are related to development and phenotypes of many neuropsychiatric diseases. Here, we evaluated the fecal microbiota and its clinical correlates in patients with hereditary transthyretin amyloidosis (ATTRv) and polyneuropathy. Fecal microbiota from 38 ATTRv patients and 39 age-matched controls was analyzed by sequencing 16S V3-V4 ribosomal RNA, and its relationships with clinical characteristics of polyneuropathy and cardiomyopathy were explored. The familial amyloidotic polyneuropathy stage was stage I, II, and III in 13, 18, and 7 patients. 99mTc-PYP SPECT showed a visual score of 2 in 15 and 3 in 21 patients. The gut microbiota of ATTRv patients showed higher alpha diversity (ASV richness and Shannon effective numbers) and dissimilar beta diversity compared to controls. Relative abundance of microbiota was dominated by Firmicutes and decreased in Bacteroidetes in ATTRv patients than in controls. Patients with more myocardial amyloid deposition were associated with increased alpha diversity, and the abundance of Clostridia was significantly correlated with pathophysiology of polyneuropathy in ATTRv patients. These findings demonstrated alterations in the gut microbiota, especially Firmicutes, in ATTRv. The association between altered microbiota and phenotypes of cardiomyopathy and polyneuropathy might suggest potential contributions of gut microbiota to ATTRv pathogenesis.

Washed microbiota transplantation reduces glycemic variability in unstable diabetes

BACKGROUND

Dysbiosis of gut microbiota is causally linked to impaired host glucose metabolism. We aimed to study effects of the new method of fecal microbiota transplantation, washed microbiota transplantation (WMT), on reducing glycemic variability (GV) in unstable diabetes.

METHODS

Fourteen eligible patients received three allogenic WMTs and were followed up at 1 week, 1 month, and 3 months. Primary outcomes were daily insulin dose, glucose excursions during meal tests, and GV indices calculated from continuous monitoring or self-monitoring glucose values. Secondary outcomes were multiomics data, including 16S rRNA gene sequencing, metagenomics, and metabolomics to explore underlying mechanisms.

RESULTS

Daily insulin dose and glucose excursions markedly dropped, whereas GV indices significantly improved up to 1 month. WMT increased gut microbial alpha diversity, beta diversity, and network complexity. Taxonomic changes featured lower abundance of genera Bacteroides and Escherichia-Shigella, and higher abundance of genus Prevotella. Metagenomics functional annotations revealed enrichment of distinct microbial metabolic pathways, including methane biosynthesis, citrate cycle, amino acid degradation, and butyrate production. Derived metabolites correlated significantly with improved GV indices. WMT did not change circulating inflammatory cytokines, enteroendocrine hormones, or C-peptide.

CONCLUSIONS

WMT showed strong ameliorating effect on GV, raising the possibility of targeting gut microbiota as an effective regimen to reduce GV in diabetes.

Probiotic Clostridium butyricum ameliorates cognitive impairment in obesity via the microbiota-gut-brain axis

Obesity is a risk factor for cognitive dysfunction and neurodegenerative disease, including Alzheimer's disease (AD). The gut microbiota-brain axis is altered in obesity and linked to cognitive impairment and neurodegenerative disorders. Here, we targeted obesity-induced cognitive impairment by testing the impact of the probiotic Clostridium butyricum, which has previously shown beneficial effects on gut homeostasis and brain function. Firstly, we characterized and analyzed the gut microbial profiles of participants with obesity and the correlation between gut microbiota and cognitive scores. Then, using an obese mouse model induced by a Western-style diet (high-fat and fiber-deficient diet), the effects of Clostridium butyricum on the microbiota-gut-brain axis and hippocampal cognitive function were evaluated. Finally, fecal microbiota transplantation was performed to assess the functional link between Clostridium butyricum remodeling gut microbiota and hippocampal synaptic protein and cognitive behaviors. Our results showed that participants with obesity had gut microbiota dysbiosis characterized by an increase in phylum Proteobacteria and a decrease in Clostridium butyricum, which were closely associated with cognitive decline. In diet-induced obese mice, oral Clostridium butyricum supplementation significantly alleviated cognitive impairment, attenuated the deficit of hippocampal neurite outgrowth and synaptic ultrastructure, improved hippocampal transcriptome related to synapses and dendrites; a comparison of the effects of Clostridium butyricum in mice against human AD datasets revealed that many of the genes changes in AD were reversed by Clostridium butyricum; concurrently, Clostridium butyricum also prevented gut microbiota dysbiosis, colonic barrier impairment and inflammation, and attenuated endotoxemia. Importantly, fecal microbiota transplantation from donor-obese mice with Clostridium butyricum supplementation facilitated cognitive variables and colonic integrity compared with from donor obese mice, highlighting that Clostridium butyricum's impact on cognitive function is largely due to its ability to remodel gut microbiota. Our findings provide the first insights into the neuroprotective effects of Clostridium butyricum on obesity-associated cognitive impairments and neurodegeneration via the gut microbiota-gut-brain axis.

The oral microbial odyssey influencing chronic metabolic disease

INTRODUCTION

Since the oral cavity is the gateway to the gut, oral microbes likely hold the potential to influence metabolic disease by affecting the gut microbiota.

METHOD

A thorough review of literature has been performed to link the alterations in oral microbiota with chronic metabolic disease by influencing the gut microbiota.

RESULT

A strong correlation exists between abnormalities in oral microbiota and several systemic disorders, such as cardiovascular disease, diabetes, and obesity, which likely initially manifest as oral diseases. Ensuring adequate oral hygiene practices and cultivating diverse oral microflora are crucial for the preservation of general well-being. Oral bacteria have the ability to establish and endure in the gastrointestinal tract, leading to the development of prolonged inflammation and activation of the immune system. Oral microbe-associated prophylactic strategies could be beneficial in mitigating metabolic diseases.

CONCLUSION

Oral microbiota can have a profound impact on the gut microbiota and influence the pathogenesis of metabolic diseases.

The Next Generation Fecal Microbiota Transplantation: To Transplant Bacteria or Virome

Fecal microbiota transplantation (FMT) has emerged as a promising therapeutic approach for dysbiosis-related diseases. However, the clinical practice of crude fecal transplants presents limitations in terms of acceptability and reproductivity. Consequently, two alternative solutions to FMT are developed: transplanting bacteria communities or virome. Advanced methods for transplanting bacteria mainly include washed microbiota transplantation and bacteria spores treatment. Transplanting the virome is also explored, with the development of fecal virome transplantation, which involves filtering the virome from feces. These approaches provide more palatable options for patients and healthcare providers while minimizing research heterogeneity. In general, the evolution of the next generation of FMT in global trends is fecal microbiota components transplantation which mainly focuses on transplanting bacteria or virome.

The Potential Hypoglycemic Competence of Low Molecular Weight Polysaccharides Obtained from Laminaria japonica

This study aimed to assess the hypoglycemic efficacy of low molecular weight polysaccharides fractions obtained from Laminaria japonica (LJOO) in a model of type 2 diabetes mellitus (T2DM) constructed using mice. Biochemical parameters were measured after 4 weeks of continuous gavage, and fasting blood glucose (FBG) concentrations were analyzed. Pathological changes in tissues were assessed. The intestinal contents were obtained for 16S rDNA high-throughput sequencing analysis and detection of short-chain fatty acids (SCFAs). LJOO lowered FBG and insulin concentrations. It altered the gut microbiota composition, as evidenced by enriched probiotic bacteria, along with an increase in the Bacteroidetes/Firmicutes ratio and a decrease in the population of harmful bacteria. LJOO stimulated the growth of SCFA-producing bacteria, thereby increasing cecal SCFAs levels. LJOO can potentially aid in alleviating T2DM and related gut microbiota dysbiosis. LJOO may be used as a food supplement for patients with T2DM.

Global Trends in Research of Pain-Gut-Microbiota Relationship and How Nutrition Can Modulate This Link

INTRODUCTION

The link between gut microbiota and chronic painful conditions has recently gained attention. Nutrition, as a common intervention in daily life and medical practice, is closely related to microbiota and pain. However, no published bibliometric reports have analyzed the scientific literature concerning the link.

METHODS AND RESULTS

We used bibliometrics to identify the characteristics of the global scientific output over the past 20 years. We also aimed to capture and describe how nutrition can modulate the abovementioned link. Relevant papers were searched in the Web of Science database. All necessary publication and citation data were acquired and exported to Bibliometrix for further analyses. The keywords mentioned were illustrated using visualization maps. In total, 1551 papers shed light on the relationship from 2003 to 2022. However, only 122 papers discussed how nutritional interventions can modulate this link. The citations and attention were concentrated on the gut microbiota, pain, and probiotics in terms of the pain-gut relationship. Nutritional status has gained attention in motor themes of a thematic map.

CONCLUSIONS

This bibliometric analysis was applied to identify the scientific literature linking gut microbiota, chronic painful conditions, and nutrition, revealing the popular research topics and authors, scientific institutions, countries, and journals in this field. This study enriches the evidence moving boundaries of microbiota medicine as a clinical medicine.