Gut Microbiota Dysbiosis Induced by Decreasing Endogenous Melatonin Mediates the Pathogenesis of Alzheimer's Disease and Obesity

Dietary Strategies to Mitigate Alzheimer's Disease: Insights into Antioxidant Vitamin Intake and Supplementation with Microbiota-Gut-Brain Axis Cross-Talk

Alzheimer's disease (AD), which is characterized by deterioration in cognitive function and neuronal death, is the most prevalent age-related progressive neurodegenerative disease. Clinical and experimental research has revealed that gut microbiota dysbiosis may be present in AD patients. The changed gut microbiota affects brain function and behavior through several mechanisms, including tau phosphorylation and increased amyloid deposits, neuroinflammation, metabolic abnormalities, and persistent oxidative stress. The lack of effective treatments to halt or reverse the progression of this disease has prompted a search for non-pharmaceutical tools. Modulation of the gut microbiota may be a promising strategy in this regard. This review aims to determine whether specific dietary interventions, particularly antioxidant vitamins, either obtained from the diet or as supplements, may support the formation of beneficial microbiota in order to prevent AD development by contributing to the systemic reduction of chronic inflammation or by acting locally in the gut. Understanding their roles would be beneficial as it may have the potential to be used as a future therapy option for AD patients.

Mesenchymal stem cells: a novel therapeutic approach for feline inflammatory bowel disease

BACKGROUND

Inflammatory bowel disease (IBD) poses a significant and growing global health challenge, affecting both humans and domestic cats. Research on feline IBD has not kept pace with its widespread prevalence in human populations. This study aimed to develop a model of feline IBD by incorporating dextran sulfate sodium (DSS) to evaluate the therapeutic potential of MSCs and to elucidate the mechanisms that enhance their action.

METHODS

We conducted a comprehensive clinical assessment, including magnetic resonance imaging (MRI), endoscopy, and histopathological examination. Additionally, alterations in intestinal microbiota were characterized by 16 S rDNA sequencing, and the influence of MSCs on IBD-related gene expression was investigated through transcriptome analysis.

RESULTS

According to our findings, MSC treatment significantly mitigated DSS-induced clinical manifestations, reduced inflammatory cell infiltration, decreased the production of inflammatory mediators, and promoted mucosal repair. Regarding the intestinal microbiota, MSC intervention effectively corrected the DSS-induced dysbiosis, increasing the presence of beneficial bacteria and suppressing the proliferation of harmful bacteria. Transcriptome analysis revealed the ability of MSCs to modulate various inflammatory and immune-related signaling pathways, including cytokine-cytokine receptor interactions, TLR signaling pathways, and NF-κB pathways.

CONCLUSION

The collective findings indicate that MSCs exert multifaceted therapeutic effects on IBD, including the regulation of intestinal microbiota balance, suppression of inflammatory responses, enhancement of intestinal barrier repair, and modulation of immune responses. These insights provide a solid scientific foundation for employing MSCs as an innovative therapeutic strategy for IBD and pave the way for future clinical explorations.

Gut microbiota: the indispensable player in neurodegenerative diseases

As one of the most urgent social and health problems in the world, neurodegenerative diseases have always been of interest to researchers. However, the pathological mechanisms and therapeutic approaches are not achieved. In addition to the established roles of oxidative stress, inflammation and immune response, changes of gut microbiota are also closely related to the pathogenesis of neurodegenerative diseases. Gut microbiota is the central player of the gut-brain axis, the dynamic bidirectional communication pathway between gut microbiota and central nervous system, and emerging insights have confirmed its indispensability in the development of neurodegenerative diseases. In this review, we discuss the complex relationship between gut microbiota and the central nervous system from the perspective of the gut-brain axis; review the mechanism of microbiota for the modulation different neurodegenerative diseases and discuss how different dietary patterns affect neurodegenerative diseases via gut microbiota; and prospect the employment of gut microbiota in the therapeutic approach to those diseases. © 2024 Society of Chemical Industry.

Cordycepin Ameliorates High Fat Diet-Induced Obesity by Modulating Endogenous Metabolism and Gut Microbiota Dysbiosis

BACKGROUND

Numerous metabolic illnesses have obesity as a risk factor. The composition of the gut microbiota and endogenous metabolism are important factors in the onset and progression of obesity. Recent research indicates that cordycepin (CRD), derived from fungi, exhibits anti-inflammatory and antioxidant properties, showing potential in combating obesity. However, further investigation is required to delineate its precise impacts on endogenous metabolism and gut microbiota.

METHODS

In this work, male C57BL/6J mice were used as models of obesity caused by a high-fat diet (HFD) and given CRD. Mice's colon, liver, and adipose tissues were stained with H&E. Serum metabolome analysis and 16S rRNA sequencing elucidated the effects of CRD on HFD-induced obese mice and identified potential mediators for its anti-obesity effects.

RESULTS

CRD intervention alleviated HFD-induced intestinal inflammation, improved blood glucose levels, and reduced fat accumulation. Furthermore, CRD supplementation demonstrated the ability to modulate endogenous metabolic disorders by regulating the levels of key metabolites, including DL-2-aminooctanoic acid, inositol, and 6-deoxyfagomine. CRD influenced the abundance of important microbiota such as Parasutterella, Alloprevotella, Prevotellaceae_NK3B31_group, Alistipes, unclassified_Clostridia_vadinBB60_group, and unclassified_Muribaculaceae, ultimately leading to the modulation of endogenous metabolism and the amelioration of gut microbiota disorders.

CONCLUSIONS

According to our research, CRD therapies show promise in regulating fat accumulation and stabilizing blood glucose levels. Furthermore, through the modulation of gut microbiota composition and key metabolites, CRD interventions have the dual capacity to prevent and ameliorate obesity.

Melatonin feeding changed the microbial diversity and metabolism of the broiler cecum

To study the effect of melatonin supplementation on the gut microbes of broilers, 160 healthy 3-week-old Ross 308 broilers with similar body weights were selected and randomly divided into four groups (M0, M20, M40, and M80) supplemented with 0, 20, 40, or 80 mg/kg melatonin. The results showed that the abundance-based coverage estimator (ACE) index of cecum microorganisms was significantly lower in the M80 group. The dominant phyla of intestinal contents in the M0, M20, M40, and M80 groups were Bacteroidetes and Firmicutes. The M40 group showed an increase in the relative abundance of Bacteroidetes spp. in the intestine, while the relative abundance of Ruminococcus spp. in the intestine of the M20, M40, and M80 groups was significantly greater than that of the M0 group. Kyoto Encyclopedia of Genes and Genomes (KEGG) functional analyses revealed that the supplementation of melatonin increases the expression of genes related to cellular processes (cell motility, cell growth and death, and cellular community-eukaryotes), environmental information processing (membrane transport and signal transduction), and genetic information processing (transport and transcription), and Cluster of Orthologous Groups (COG) of proteins functional analyses revealed that the supplementation of melatonin resulted in a significant increase in cellular processes and signaling (cell motility, signal transduction mechanisms, intracellular trafficking, secretion, and vesicular transport), information storage and processing (RNA processing and modification, chromatin structure and dynamics, translation, ribosomal structure, and biogenesis), metabolism (energy production and conversion, lipid transportation and metabolism, inorganic ion transport and metabolism, secondary metabolite biosynthesis, transport, and catabolism), and poorly characterized (general function prediction only). In summary, supplementation of feed with melatonin can increase the diversity of intestinal microorganisms and the relative abundance of Bacteroides and Firmicutes in the cecum, improve digestive ability and nutrient absorption ability, and positively regulate the metabolic ability of broilers.

Gut microbiome and major depressive disorder: insights from two-sample Mendelian randomization

BACKGROUND

Existing evidence suggests that alterations in the gut microbiome are closely associated with major depressive disorder (MDD). We aimed to reveal the causal relationships between MDD and various microbial taxa in the gut.

METHODS

We used the two-sample Mendelian randomization (TSMR) to explore the bidirectional causal effects between gut microbiota and MDD. The genome-wide association studies summary results of gut microbiota were obtained from two large consortia, the MibioGen consortium and the Dutch Microbiome Project, which we analyzed separately.

RESULTS

Our TSMR analysis identified 10 gut bacterial taxa that were protective against MDD, including phylum Actinobacteria, order Clostridiales, and family Bifidobacteriaceae (OR: 0.96 ∼ 0.98). Ten taxa were associated with an increased risk of MDD, including phyla Firmicutes and Proteobacteria, class Actinobacteria, and genus Alistipes (OR: 1.01 ∼ 1.09). On the other hand, MDD may decrease the abundance of 12 taxa, including phyla Actinobacteria and Firmicutes, families Bifidobacteriaceae and Defluviitaleaceae (OR: 0.63 ∼ 0.88). MDD may increase the abundance of 8 taxa, including phylum Bacteroidetes, genera Parabacteroides, and Bacteroides (OR: 1.12 ∼ 1.43).

CONCLUSIONS

Our study supports that there are mutual causal relationships between certain gut microbiota and the development of MDD suggesting that gut microbiota may be targeted in the treatment of MDD.

Establishment of a novel obesity mouse model: the induction of intestinal microbiota dysbiosis

To establish and evaluate an intestinal microbiota dysbiosis-induced obesity mouse model. 50 C57BL/6 J male healthy mice were randomly divided into an obesity model group and the control group. The body weight, body length, and Lee's index of the two groups of mice at week 1 and week 10 were compared. Serum glucose (GLU), total cholesterol (TC) and triglyceride (TG) were measured by enzyme-labeled colorimetric methods. Illumina HiSeq 16S rDNA high-throughput sequencing technology was used to characterize intestinal microbiota in feces. The success rate of model establishment in obese mice was 52%. The body weight, body length, Lee's index, and abdominal fat (wet weight) in the obese model group were all higher than those in the control group, and the differences were statistically significant (P < 0.01). Serum GLU and TC levels in the obesity model group were higher than those in the control group (P < 0.05), and there was no difference in TG levels between the two groups (P > 0.05). The control group contained more abundant intestinal microbiota phyla and genera than did the obesity model group; the differences between the two groups were significant (FDR ≤ 0.05, P ≤ 0.05). Intestinal microbiota dysbiosis can be used to generate an obesity model in mice.

Exploring the Interplay between the Hologenome and Complex Traits in Bovine and Porcine Animals Using Genome-Wide Association Analysis

Genome-wide association studies (GWAS) significantly enhance our ability to identify trait-associated genomic variants by considering the host genome. Moreover, the hologenome refers to the host organism's collective genetic material and its associated microbiome. In this study, we utilized the hologenome framework, called Hologenome-wide association studies (HWAS), to dissect the architecture of complex traits, including milk yield, methane emissions, rumen physiology in cattle, and gut microbial composition in pigs. We employed four statistical models: (1) GWAS, (2) Microbial GWAS (M-GWAS), (3) HWAS-CG (hologenome interaction estimated using COvariance between Random Effects Genome-based restricted maximum likelihood (CORE-GREML)), and (4) HWAS-H (hologenome interaction estimated using the Hadamard product method). We applied Bonferroni correction to interpret the significant associations in the complex traits. The GWAS and M-GWAS detected one and sixteen significant SNPs for milk yield traits, respectively, whereas the HWAS-CG and HWAS-H each identified eight SNPs. Moreover, HWAS-CG revealed four, and the remaining models identified three SNPs each for methane emissions traits. The GWAS and HWAS-CG detected one and three SNPs for rumen physiology traits, respectively. For the pigs' gut microbial composition traits, the GWAS, M-GWAS, HWAS-CG, and HWAS-H identified 14, 16, 13, and 12 SNPs, respectively. We further explored these associations through SNP annotation and by analyzing biological processes and functional pathways. Additionally, we integrated our GWA results with expression quantitative trait locus (eQTL) data using transcriptome-wide association studies (TWAS) and summary-based Mendelian randomization (SMR) methods for a more comprehensive understanding of SNP-trait associations. Our study revealed hologenomic variability in agriculturally important traits, enhancing our understanding of host-microbiome interactions.

Gut-Derived Exosomes Mediate the Microbiota Dysbiosis-Induced Spermatogenesis Impairment by Targeting Meioc in Mice

Diseases like obesity and intestinal inflammation diseases are accompanied by dysbiosis of the gut microbiota (DSGM), which leads to various complications, including systemic metabolic disorders. DSGM reportedly impairs the fertility of male mice; however, the regulatory mechanism is unclear. Exosomes are molecular mediators of intercellular communication, but the regulation of spermatogenesis by non-reproductive tissue-originated exosomes remains unknown. The present study shows that DSGM altered the miRNA expression profile of mouse circulating exosomes and impaired spermatogenesis. Moreover, the single-cell sequencing results indicate that circulating exosomes from mice with DSGM impaired spermatogenesis, while circulating exosomes from wild mice improved spermatogenesis by promoting meiosis. Further study demonstrates that DSGM leads to abnormal upregulation of miR-211-5p in gut-derived circulating exosomes, which inhibited the expression of meiosis-specific with coiled-coil domain (Meioc) in the testes and impaired spermatogenesis by disturbing meiosis process. In summary, this study defines the important role of gut-derived exosomes in connecting the "gut-testis" axis.

Mechanism of Action of Melatonin as a Potential Adjuvant Therapy in Inflammatory Bowel Disease and Colorectal Cancer

Inflammatory bowel disease (IBD), a continuum of chronic inflammatory diseases, is tightly associated with immune system dysregulation and dysbiosis, leading to inflammation in the gastrointestinal tract (GIT) and multiple extraintestinal manifestations. The pathogenesis of IBD is not completely elucidated. However, it is associated with an increased risk of colorectal cancer (CRC), which is one of the most common gastrointestinal malignancies. In both IBD and CRC, a complex interplay occurs between the immune system and gut microbiota (GM), leading to the alteration in GM composition. Melatonin, a neuroendocrine hormone, was found to be involved with this interplay, especially since it is present in high amounts in the gut, leading to some protective effects. Actually, melatonin enhances the integrity of the intestinal mucosal barrier, regulates the immune response, alleviates inflammation, and attenuates oxidative stress. Thereby, the authors summarize the multifactorial interaction of melatonin with IBD and with CRC, focusing on new findings related to the mechanisms of action of this hormone, in addition to its documented positive outcomes on the treatment of these two pathologies and possible future perspectives to use melatonin as an adjuvant therapy.

Gut microbiota and its metabolites in Alzheimer's disease: from pathogenesis to treatment

Introduction

An increasing number of studies have demonstrated that altered microbial diversity and function (such as metabolites), or ecological disorders, regulate bowel-brain axis involvement in the pathophysiologic processes in Alzheimer's disease (AD). The dysregulation of microbes and their metabolites can be a double-edged sword in AD, presenting the possibility of microbiome-based treatment options. This review describes the link between ecological imbalances and AD, the interactions between AD treatment modalities and the microbiota, and the potential of interventions such as prebiotics, probiotics, synbiotics, fecal microbiota transplantation, and dietary interventions as complementary therapeutic strategies targeting AD pathogenesis and progression.

Survey methodology

Articles from PubMed and china.com on intestinal flora and AD were summarized to analyze the data and conclusions carefully to ensure the comprehensiveness, completeness, and accuracy of this review.

Conclusions

Regulating the gut flora ecological balance upregulates neurotrophic factor expression, regulates the microbiota-gut-brain (MGB) axis, and suppresses the inflammatory responses. Based on emerging research, this review explored novel directions for future AD research and clinical interventions, injecting new vitality into microbiota research development.

11-Plex DiLeu Isobaric Labeling Enables Quantitative Assessment of Brain Region Protein Association Networks Impacted by the Gut Microbiome

Gut microbiota can regulate host brain functions and influence various physiological and pathological processes through the brain-gut axis. To systematically elucidate the intervention of different gut environments on different brain regions, we implemented an integrated approach that combines 11-plex DiLeu isobaric tags with a "BRIDGE" normalization strategy to comparatively analyze the proteome of six brain regions in germ-free (GF)- and conventionally raised (ConvR)-mice. A total of 5945 proteins were identified and 5656 were quantifiable, while 1906 of them were significantly changed between GF- and ConvR-mice; 281 proteins were filtered with FC greater than 1.2 in at least one brain region, of which heatmap analysis showed clear protein profile disparities, both between brain regions and gut microbiome conditions. Gut microbiome impact is most overt in the hypothalamus and the least in the thalamus region. Collectively, this approach allows an in-depth investigation of the induced protein changes by multiple gut microbiome environments in a brain region-specific manner. This comprehensive proteomic work improves the understanding of the brain region protein association networks impacted by the gut microbiome and highlights the critical roles of the brain-gut axis.

Causal relationships between gut microbiota and hypothyroidism: a Mendelian randomization study

BACKGROUND

Previous studies have shown that the gut microbiota plays an important role in the maintenance of thyroid homeostasis. We aimed to evaluate the causal relationships between gut microbiota and hypothyroidism.

METHODS

Summary statistics for 211 gut microbiota taxa were obtained from the largest available genome-wide association study (GWAS) meta-analysis conducted by the MiBioGen consortium. Summary statistics for hypothyroidism were obtained from two distinct sources: the FinnGen consortium R9 release data (40,926 cases and 274,069 controls) and the UK Biobank data (22,687 cases and 440,246 controls), respectively. A two-sample Mendelian randomization (MR) design was employed, and thorough sensitivity analyses were carried out to ensure the reliability of the results.

RESULTS

Based on the FinnGen consortium, we found increased levels of Intestinimonas (OR = 1.09; 95%CI = 1.02-1.16; P = 0.01) and Ruminiclostridium5 (OR = 1.11; 95%CI = 1.02-1.22; P = 0.02) may be associated with a higher risk of hypothyroidism, while increased levels of Butyrivibrio (OR = 0.95; 95%CI = 0.92-0.99; P = 0.02), Eggerthella (OR = 0.93; 95%CI = 0.88-0.98; P = 0.01), Lachnospiraceae UCG008 (OR = 0.92; 95%CI = 0.85-0.99; P = 0.02), Ruminococcaceae UCG011 (OR = 0.95; 95%CI = 0.90-0.99; P = 0.02), and Actinobacteria (OR = 0.88; 95%CI = 0.80-0.97; P = 0.01) may be associated with a lower risk. According to the UK Biobank data, Eggerthella and Ruminiclostridium5 remain causally associated with hypothyroidism. The sensitivity analysis demonstrates consistent results without evidence of heterogeneity or pleiotropy.

CONCLUSION

This study highlights the impact of specific gut microbiota on hypothyroidism. Strategies to change composition of gut microbiota may hold promise as potential interventions.

Chronodisruption and Gut Microbiota: Triggering Glycemic Imbalance in People with Type 2 Diabetes

The desynchronization of physiological and behavioral mechanisms influences the gut microbiota and eating behavior in mammals, as shown in both rodents and humans, leading to the development of pathologies such as Type 2 diabetes (T2D), obesity, and metabolic syndrome. Recent studies propose resynchronization as a key input controlling metabolic cycles and contributing to reducing the risk of suffering some chronic diseases such as diabetes, obesity, or metabolic syndrome. In this analytical review, we present an overview of how desynchronization and its implications for the gut microbiome make people vulnerable to intestinal dysbiosis and consequent chronic diseases. In particular, we explore the eubiosis-dysbiosis phenomenon and, finally, propose some topics aimed at addressing chronotherapy as a key strategy in the prevention of chronic diseases.

Serum amyloid beta 42 levels correlated with metabolic syndrome and its components

Introduction

Beta-amyloid accumulation in the brain appears to be a key initiating event in Alzheimer's disease (AD), and factors associated with increased deposition of beta-amyloid are of great interest. Enhanced deposition of amyloid-β peptides is due to an imbalance between their production and elimination. Previous studies show that diminished levels of CSF amyloid beta 42 (Aβ42) is a biomarker in AD; however, the role of serum Aβ42 in AD is contradictory. BMI and obesity have been reported to be related to increased serum Aβ42 levels. Therefore, we aimed to investigate the relation between metabolic syndrome (MetS), its clinical measures (abdominal obesity, high glucose, high triglyceride, low high-density lipoprotein cholesterol level, and hypertension), and serum Aβ42 levels.

Methods

A total of 1261 subjects, aged 18-89 years in Chengdu, China, were enrolled from January 2020 to January 2021 to explore the correlation of serum Aβ42 levels with body mass index (BMI), blood lipids, and blood pressure. Furthermore, as the risk of MetS is closely related to age, 1,212 participants (N = 49 with age ≥ 80 years old were excluded) were analyzed for the correlation of serum Aβ42 level and MetS clinical measures.

Results

The results showed that log-transformed serum Aβ42 level was positively correlated with BMI (R = 0.29; p < 0.001), log-transformed triglyceride (R = 0.14; p < 0.001), and diastolic blood pressure (DBP) (R = 0.12; p < 0.001) and negatively correlated with high-density lipoprotein (HDL-c) (R = -0.18; p < 0.001). After adjusting for age, sex, and other covariates, elevated serum Aβ42 level was correlated with higher values of BMI (βmodel1 = 2.694, βmodel2 = 2.703) and DBP (βmodel1 = 0.541, βmodel2 = 0.546) but a lower level of HDL-c (βmodel2 = -1.741). Furthermore, serum Aβ42 level was positively correlated with MetS and its clinical measures, including BMI and DBP, and negatively correlated with HDL-c level in the Han Chinese population. However, the level of serum Aβ42 did not show a significant correlation with high glucose or high triglyceride.

Discussion

These observations indicate that MetS and its components are associated with higher levels of serum Aβ42 and hence limit the potential of serum Aβ42 as a suitable diagnostic biomarker for AD. As such, we recommend serum Aβ42 serve as a direct risk biomarker for MetS rather than for AD.

Alzheimer's disease, a metabolic disorder: Clinical advances and basic model studies (Review)

Alzheimer's disease (AD) is a type of neurodegenerative disease characterized by cognitive impairment that is aggravated with age. The pathological manifestations include extracellular amyloid deposition, intracellular neurofibrillary tangles and loss of neurons. As the world population ages, the incidence of AD continues to increase, not only posing a significant threat to the well-being and health of individuals but also bringing a heavy burden to the social economy. There is epidemiological evidence suggesting a link between AD and metabolic diseases, which share pathological similarities. This potential link would deserve further consideration; however, the pathogenesis and therapeutic efficacy of AD remain to be further explored. The complex pathogenesis and pathological changes of AD pose a great challenge to the choice of experimental animal models. To understand the role of metabolic diseases in the development of AD and the potential use of drugs for metabolic diseases, the present article reviews the research progress of the comorbidity of AD with diabetes, obesity and hypercholesterolemia, and summarizes the different roles of animal models in the study of AD to provide references for researchers.

Gut microbiota regulates host melatonin production through epithelial cell MyD88

Melatonin has various physiological effects, such as the maintenance of circadian rhythms, anti-inflammatory functions, and regulation of intestinal barriers. The regulatory functions of melatonin in gut microbiota remodeling have also been well clarified; however, the role of gut microbiota in regulating host melatonin production remains poorly understood. To address this, we studied the contribution of gut microbiota to host melatonin production using gut microbiota-perturbed models. We demonstrated that antibiotic-treated and germ-free mice possessed diminished melatonin levels in the serum and elevated melatonin levels in the colon. The influence of the intestinal microbiota on host melatonin production was further confirmed by fecal microbiota transplantation. Notably, Lactobacillus reuteri (L. R) and Escherichia coli (E. coli) recapitulated the effects of gut microbiota on host melatonin production. Mechanistically, L. R and E. coli activated the TLR2/4/MyD88/NF-κB signaling pathway to promote expression of arylalkylamine N-acetyltransferase (AANAT, a rate-limiting enzyme for melatonin production), and MyD88 deficiency in colonic epithelial cells abolished the influence of intestinal microbiota on colonic melatonin production. Collectively, we revealed a specific underlying mechanism of gut microbiota to modulate host melatonin production, which might provide novel therapeutic ideas for melatonin-related diseases.

Melatonin as a Mediator of the Gut Microbiota-Host Interaction: Implications for Health and Disease

In recent years, the role played by melatonin on the gut microbiota has gained increasingly greater attention. Additionally, the gut microbiota has been proposed as an alternative source of melatonin, suggesting that this antioxidant indoleamine could act as a sort of messenger between the gut microbiota and the host. This review analyses the available scientific literature about possible mechanisms involved in this mediating role, highlighting its antioxidant effects and influence on this interaction. In addition, we also review the available knowledge on the effects of melatonin on gut microbiota composition, as well as its ability to alleviate dysbiosis related to sleep deprivation or chronodisruptive conditions. The melatonin-gut microbiota relationship has also been discussed in terms of its role in the development of different disorders, from inflammatory or metabolic disorders to psychiatric and neurological conditions, also considering oxidative stress and the reactive oxygen species-scavenging properties of melatonin as the main factors mediating this relationship.

How is Big Data reshaping preclinical aging research?

The exponential scientific and technological progress during the past 30 years has favored the comprehensive characterization of aging processes with their multivariate nature, leading to the advent of Big Data in preclinical aging research. Spanning from molecular omics to organism-level deep phenotyping, Big Data demands large computational resources for storage and analysis, as well as new analytical tools and conceptual frameworks to gain novel insights leading to discovery. Systems biology has emerged as a paradigm that utilizes Big Data to gain insightful information enabling a better understanding of living organisms, visualized as multilayered networks of interacting molecules, cells, tissues and organs at different spatiotemporal scales. In this framework, where aging, health and disease represent emergent states from an evolving dynamic complex system, context given by, for example, strain, sex and feeding times, becomes paramount for defining the biological trajectory of an organism. Using bioinformatics and artificial intelligence, the systems biology approach is leading to remarkable advances in our understanding of the underlying mechanism of aging biology and assisting in creative experimental study designs in animal models. Future in-depth knowledge acquisition will depend on the ability to fully integrate information from different spatiotemporal scales in organisms, which will probably require the adoption of theories and methods from the field of complex systems. Here we review state-of-the-art approaches in preclinical research, with a focus on rodent models, that are leading to conceptual and/or technical advances in leveraging Big Data to understand basic aging biology and its full translational potential.

A dynamics association study of gut barrier and microbiota in hyperuricemia

Introduction

The intricate interplay between gut microbiota and hyperuricemia remains a subject of growing interest. However, existing studies only provided snapshots of the gut microbiome at single time points, the temporal dynamics of gut microbiota alterations during hyperuricemia progression and the intricate interplay between the gut barrier and microbiota remain underexplored. Our investigation revealed compelling insights into the dynamic changes in both gut microbiota and intestinal barrier function throughout the course of hyperuricemia.

Methods

The hyperuricemia mice (HY) were given intragastric administration of adenine and potassium oxalate. Gut microbiota was analyzed by 16S rRNA sequencing at 3, 7, 14, and 21 days after the start of the modeling process. Intestinal permeability as well as LPS, TNF-α, and IL-1β levels were measured at 3, 7, 14, and 21 days.

Results

We discovered that shifts in microbial community composition occur prior to the onset of hyperuricemia, key bacterial Bacteroidaceae, Bacteroides, and Blautia exhibited reduced levels, potentially fueling microbial dysbiosis as the disease progresses. During the course of hyperuricemia, the dynamic fluctuations in both uric acid levels and intestinal barrier function was accompanied with the depletion of key beneficial bacteria, including Prevotellaceae, Muribaculum, Parabacteroides, Akkermansia, and Bacteroides, and coincided with an increase in pathogenic bacteria such as Oscillibacter and Ruminiclostridium. This microbial community shift likely contributed to elevated lipopolysaccharide (LPS) and pro-inflammatory cytokine levels, ultimately promoting metabolic inflammation. The decline of Burkholderiaceae and Parasutterella was inversely related to uric acid levels, Conversely, key families Ruminococcaceae, Family_XIII, genera Anaeroplasma exhibited positive correlations with uric acid levels. Akkermansiaceae and Bacteroidaceae demonstrating negative correlations, while LPS-containing microbiota such as Desulfovibrio and Enterorhabdus exhibited positive correlations with intestinal permeability.

Conclusion

In summary, this study offers a dynamic perspective on the complex interplay between gut microbiota, uric acid levels, and intestinal barrier function during hyperuricemia progression. Our study suggested that Ruminiclostridium, Bacteroides, Akkermansiaceae, Bilophila, Burkholderiaceae and Parasutterella were the key bacteria that play vital rols in the progress of hyperuricemia and compromised intestinal barrier, which provide a potential avenue for therapeutic interventions in hyperuricemia.

Fecal microbiota transplantation: a novel strategy for treating Alzheimer's disease

Alzheimer's disease is a common neurological disorder, which has become one of the major factors affecting human health due to its serious impact on individuals, families and society. It has been confirmed that gut microbiota can affect the occurrence and development of Alzheimer's disease. Especially, fecal microbiota transplantation plays a positive role in the treatment of Alzheimer's disease. The mechanisms for improving Alzheimer's disease might include anti-inflammation and regulation of amyloid β-protein, synaptic plasticity, short-chain fatty acids, and histone acetylation. In this mini-review, the relationship between fecal microbiota transplantation and Alzheimer's disease was summarized. It is hoped that fecal microbiota transplantation would play a positive role in the prevention and treatment of Alzheimer's disease in the future.

Complex relationship between gut microbiota and thyroid dysfunction: a bidirectional two-sample Mendelian randomization study

Background

Many studies have reported the link between gut microbiota and thyroid dysfunction. However, the causal effect of gut microbiota on thyroid dysfunction and the changes in gut microbiota after the onset of thyroid dysfunction are not clear.

Methods

A two-sample Mendelian randomization (MR) study was used to explore the complex relationship between gut microbiota and thyroid dysfunction. Data on 211 bacterial taxa were obtained from the MiBioGen consortium, and data on thyroid dysfunction, including hypothyroidism, thyroid-stimulating hormone alteration, thyroxine deficiency, and thyroid peroxidase antibodies positivity, were derived from several databases. Inverse variance weighting (IVW), weighted median, MR-Egger, weighted mode, and simple mode were applied to assess the causal effects of gut microbiota on thyroid dysfunction. Comprehensive sensitivity analyses were followed to validate the robustness of the results. Finally, a reverse MR study was conducted to explore the alteration of gut microbiota after hypothyroidism onset.

Results

Our bidirectional two-sample MR study revealed that the genera Intestinimonas, Eubacterium brachy group, Ruminiclostridium5, and Ruminococcaceae UCG004 were the risk factors for decreased thyroid function, whereas the genera Bifidobacterium and Lachnospiraceae UCG008 and phyla Actinobacteria and Verrucomicrobia were protective. The abundance of eight bacterial taxa varied after the onset of hypothyroidism. Sensitivity analysis showed that no heterogeneity or pleiotropy existed in the results of this study.

Conclusion

This novel MR study systematically demonstrated the complex relationship between gut microbiota and thyroid dysfunction, which supports the selection of more targeted probiotics to maintain thyroid-gut axis homeostasis and thus to prevent, control, and reverse the development of thyroid dysfunction.

Role of Bmal1 and Gut Microbiota in Alzheimer's Disease and Parkinson's Disease Pathophysiology: The Probable Effect of Melatonin on Their Association

In recent years, the role of new factors in the pathophysiology of neurodegenerative diseases has been investigated. Alzheimer's disease (AD) and Parkinson's disease (PD) are the most common neurodegenerative diseases worldwide. Although pathological changes such as the accumulation of aggregated proteins in the brain and inflammatory responses are known as the main factors involved in the development of these diseases, new studies show the role of gut microbiota and circadian rhythm in the occurrence of these changes. However, the association between circadian rhythm and gut microbiota in AD and PD has not yet been investigated. Recent results propose that alterations in circadian rhythm regulators, mainly Bmal1, may regulate the abundance of gut microbiota. This correlation has been linked to the regulation of the expression of immune-related genes and Bmal-1 mediated oscillation of IgA and hydrogen peroxide production. These data seem to provide new insight into the molecular mechanism of melatonin inhibiting the progression of AD and PD. Therefore, this manuscript aims to review the role of the gut microbiota and circadian rhythm in health and AD and PD and also presents a hypothesis on the effect of melatonin on their communication.

Metabolic Profile of Alzheimer's Disease: Is 10-Hydroxy-2-decenoic Acid a Pertinent Metabolic Adjuster?

Alzheimer's disease (AD) represents a significant public health concern in modern society. Metabolic syndrome (MetS), which includes diabetes mellitus (DM) and obesity, represents a modifiable risk factor for AD. MetS and AD are interconnected through various mechanisms, such as mitochondrial dysfunction, oxidative stress, insulin resistance (IR), vascular impairment, inflammation, and endoplasmic reticulum (ER) stress. Therefore, it is necessary to seek a multi-targeted and safer approach to intervention. Thus, 10-hydroxy-2-decenoic acid (10-HDA), a unique hydroxy fatty acid in royal jelly, has shown promising anti-neuroinflammatory, blood-brain barrier (BBB)-preserving, and neurogenesis-promoting properties. In this paper, we provide a summary of the relationship between MetS and AD, together with an introduction to 10-HDA as a potential intervention nutrient. In addition, molecular docking is performed to explore the metabolic tuning properties of 10-HDA with associated macromolecules such as GLP-1R, PPARs, GSK-3, and TREM2. In conclusion, there is a close relationship between AD and MetS, and 10-HDA shows potential as a beneficial nutritional intervention for both AD and MetS.

Protective and therapeutic potential of melatonin against intestinal diseases: updated review of current data based on molecular mechanisms

INTRODUCTION

Intestinal diseases, a leading global cause of mortality and morbidity, carry a substantial socioeconomic burden. Small and large intestines play pivotal roles in gastrointestinal physiology and food digestion. Pathological conditions, such as gut dysbiosis, inflammation, cancer, therapy-related complications, ulcers, and ischemia, necessitate the urgent exploration of safe and effective complementary therapeutic strategies for optimal intestinal health.

AREAS COVERED

This article evaluates the potential therapeutic effects of melatonin, a molecule with a wide range of physiological actions, on intestinal diseases including inflammatory bowel disease, irritable bowel syndrome, colon cancer, gastric/duodenal ulcers and other intestinal disorders.

EXPERT OPINION

Due to anti-inflammatory and antioxidant properties as well as various biological actions, melatonin could be a therapeutic option for improving digestive disorders. However, more researches are needed to fully understand the potential benefits and risks of using melatonin for digestive disorders.

Polystyrene micro- and nanoparticles exposure induced anxiety-like behaviors, gut microbiota dysbiosis and metabolism disorder in adult mice

Plastics have been proven to be a potential threat to the ecosystem, and their toxicity mechanism is still uncertain. In the ecological environment, plastics can be degraded into microplastics (MPs) and nanoplastics (NPs), which can be contaminated and ingested through the food chain. MPs and NPs are associated with severe intestinal injury, intestinal microbiota disorder, and neurotoxicity, but it is still unclear whether MPs- and NPs-induced intestinal microbiota dysbiosis will affect the brain through the gut-brain axis. In the current study, we determined the effects of exposure to polystyrene (PS)-MPs and PS-NPs on anxiety-like behaviors and explored the underlying mechanisms. This study explored the behavioral effects of 30-day and 60-day exposure to PS-NPs and PS-MPs using the open field test (OFT) and elevated plus maze (EPM) test. Behavioral tests showed PS-NPs and PS-MPs treatment remarkedly induced anxiety-like behaviors compared with the control group. Using 16 S rRNA gene sequencing and untargeted metabolomics analyses, we observed that PS-MPs and PS-NPs exposure reduced the beneficial gut microbiota expression level, such as Lachnoclostridium and Lactobacillus, and increased the conditionally pathogenic bacteria expressions level, such as Proteobacteria, Actinobacteria, and Desulfovibrio. In addition, PS-NPs and PS-MPs reduce intestinal mucus secretion and increase intestinal permeability. The results of serum metabonomics suggested that the metabolic pathways, such as ABC transporter pathways, aminoacyl-tRNA biosynthesis, biosynthesis of amino acids, and bile secretion were enriched after PS-NPs and PS-MPs treatment. Besides, neurotransmitter metabolites were also altered by PS-NPs and PS-MPs. It is noteworthy that the correlation analysis showed that the disorder of intestinal microbiota was related to anxiety-like behaviors and neurotransmitter metabolites disorder. The regulation of intestinal microbiota may be a promising treatment strategy for PS-MPs- and PS-NPs-induced anxiety disorder.

Anti-Alzheimers molecular mechanism of icariin: insights from gut microbiota, metabolomics, and network pharmacology

BACKGROUND

Icariin (ICA), an active ingredient extracted from Epimedium species, has shown promising results in the treatment of Alzheimer's disease (AD), although its potential therapeutic mechanism remains largely unknown. This study aimed to investigate the therapeutic effects and the underlying mechanisms of ICA on AD by an integrated analysis of gut microbiota, metabolomics, and network pharmacology (NP).

METHODS

The cognitive impairment of mice was measured using the Morris Water Maze test and the pathological changes were assessed using hematoxylin and eosin staining. 16S rRNA sequencing and multi-metabolomics were performed to analyze the alterations in the gut microbiota and fecal/serum metabolism. Meanwhile, NP was used to determine the putative molecular regulation mechanism of ICA in AD treatment.

RESULTS

Our results revealed that ICA intervention significantly improved cognitive dysfunction in APP/PS1 mice and typical AD pathologies in the hippocampus of the APP/PS1 mice. Moreover, the gut microbiota analysis showed that ICA administration reversed AD-induced gut microbiota dysbiosis in APP/PS1 mice by elevating the abundance of Akkermansia and reducing the abundance of Alistipe. Furthermore, the metabolomic analysis revealed that ICA reversed the AD-induced metabolic disorder via regulating the glycerophospholipid and sphingolipid metabolism, and correlation analysis revealed that glycerophospholipid and sphingolipid were closely related to Alistipe and Akkermansia. Moreover, NP indicated that ICA might regulate the sphingolipid signaling pathway via the PRKCA/TNF/TP53/AKT1/RELA/NFKB1 axis for the treatment of AD.

CONCLUSION

These findings indicated that ICA may serve as a promising therapeutic approach for AD and that the ICA-mediated protective effects were associated with the amelioration of microbiota disturbance and metabolic disorder.

Microbiota-gut-brain axis and related therapeutics in Alzheimer's disease: prospects for multitherapy and inflammation control

Alzheimer's disease (AD) is the most common type of dementia in the elderly and causes neurodegeneration, leading to memory loss, behavioral disorder, and psychiatric impairment. One potential mechanism contributing to the pathogenesis of AD may be the imbalance in gut microbiota, local and systemic inflammation, and dysregulation of the microbiota-gut-brain axis (MGBA). Most of the AD drugs approved for clinical use today are symptomatic treatments that do not improve AD pathologic changes. As a result, researchers are exploring novel therapeutic modalities. Treatments involving the MGBA include antibiotics, probiotics, transplantation of fecal microbiota, botanical products, and others. However, single-treatment modalities are not as effective as expected, and a combination therapy is gaining momentum. The purpose of this review is to summarize recent advances in MGBA-related pathological mechanisms and treatment modalities in AD and to propose a new concept of combination therapy. "MGBA-based multitherapy" is an emerging view of treatment in which classic symptomatic treatments and MGBA-based therapeutic modalities are used in combination. Donepezil and memantine are two commonly used drugs in AD treatment. On the basis of the single/combined use of these two drugs, two/more additional drugs and treatment modalities that target the MGBA are chosen based on the characteristics of the patient's condition as an adjuvant treatment, as well as the maintenance of good lifestyle habits. "MGBA-based multitherapy" offers new insights for the treatment of cognitive impairment in AD patients and is expected to show good therapeutic results.

Brain washing and neural health: role of age, sleep, and the cerebrospinal fluid melatonin rhythm

The brain lacks a classic lymphatic drainage system. How it is cleansed of damaged proteins, cellular debris, and molecular by-products has remained a mystery for decades. Recent discoveries have identified a hybrid system that includes cerebrospinal fluid (CSF)-filled perivascular spaces and classic lymph vessels in the dural covering of the brain and spinal cord that functionally cooperate to remove toxic and non-functional trash from the brain. These two components functioning together are referred to as the glymphatic system. We propose that the high levels of melatonin secreted by the pineal gland directly into the CSF play a role in flushing pathological molecules such as amyloid-β peptide (Aβ) from the brain via this network. Melatonin is a sleep-promoting agent, with waste clearance from the CNS being highest especially during slow wave sleep. Melatonin is also a potent and versatile antioxidant that prevents neural accumulation of oxidatively-damaged molecules which contribute to neurological decline. Due to its feedback actions on the suprachiasmatic nucleus, CSF melatonin rhythm functions to maintain optimal circadian rhythmicity, which is also critical for preserving neurocognitive health. Melatonin levels drop dramatically in the frail aged, potentially contributing to neurological failure and dementia. Melatonin supplementation in animal models of Alzheimer's disease (AD) defers Aβ accumulation, enhances its clearance from the CNS, and prolongs animal survival. In AD patients, preliminary data show that melatonin use reduces neurobehavioral signs such as sundowning. Finally, melatonin controls the mitotic activity of neural stem cells in the subventricular zone, suggesting its involvement in neuronal renewal.

The Microbiota-Dependent Worsening Effects of Melatonin on Gut Inflammation

Dysbiosis and disturbances in gut homeostasis may result in dysregulated responses, which are common in inflammatory bowel diseases (IBD). These conditions may be refractory to the usual treatments and novel therapies are still necessary to reach a more successful regulation of intestinal immunity. The hormone melatonin (MLT) has been raised as a therapeutic alternative because of its known interactions with immune responses and gut microbiota. Hence, we evaluated the effects of MLT in experimental colitis that evolves with intestinal dysbiosis, inflammation and bacterial translocation. C57BL/6 mice were exposed to dextran sulfate sodium and treated with MLT. In acute colitis, the hormone led to increased clinical, systemic and intestinal inflammatory parameters. During remission, continued MLT administration delayed recovery, increased TNF, memory effector lymphocytes and diminished spleen regulatory cells. MLT treatment reduced Bacteroidetes and augmented Actinobacteria and Verrucomicrobia phyla in mice feces. Microbiota depletion resulted in a remarkable reversion of the colitis phenotype after MLT administration, including a counter-regulatory immune response, reduction in TNF and colon macrophages. There was a decrease in Actinobacteria, Firmicutes and, most strikingly, Verrucomicrobia phylum in recovering mice. Finally, these results pointed to a gut-microbiota-dependent effect of MLT in the potentiation of intestinal inflammation.

Gut microbiota-derived metabolites mediate the neuroprotective effect of melatonin in cognitive impairment induced by sleep deprivation

Sleep loss is a serious global health concern. Consequences include memory deficits and gastrointestinal dysfunction. Our previous research showed that melatonin can effectively improve cognitive impairment and intestinal microbiota disturbances caused by sleep deprivation (SD). The present study further explored the mechanism by which exogenous melatonin prevents SD-induced cognitive impairments. Here, we established fecal microbiota transplantation, Aeromonas colonization and LPS or butyrate supplementation tests to evaluate the role of the intestinal microbiota and its metabolites in melatonin in alleviating SD-induced memory impairment.  RESULTS: Transplantation of the SD-gut microbiota into normal mice induced microglia overactivation and neuronal apoptosis in the hippocampus, cognitive decline, and colonic microbiota disorder, manifesting as increased levels of Aeromonas and LPS and decreased levels of Lachnospiraceae_NK4A136 and butyrate. All these events were reversed with the transplantation of SD + melatonin-gut microbiota. Colonization with Aeromonas and the addition of LPS produced an inflammatory response in the hippocampus and spatial memory impairment in mice. These changes were reversed by supplementation with melatonin, accompanied by decreased levels of Aeromonas and LPS. Butyrate administration to sleep-deprived mice restored inflammatory responses and memory impairment. In vitro, LPS supplementation caused an inflammatory response in BV2 cells, which was improved by butyrate supplementation. This ameliorative effect of butyrate was blocked by pretreatment with MCT1 inhibitor and HDAC3 agonist but was mimicked by TLR4 and p-P65 antagonists.  CONCLUSIONS: Gut microbes and their metabolites mediate the ameliorative effects of melatonin on SD-induced cognitive impairment. A feasible mechanism is that melatonin downregulates the levels of Aeromonas and constituent LPS and upregulates the levels of Lachnospiraceae_NK4A136 and butyrate in the colon. These changes lessen the inflammatory response and neuronal apoptosis in the hippocampus through crosstalk between the TLR4/NF-κB and MCT1/ HDAC3 signaling pathways. Video Abstract.

Bifico relieves irritable bowel syndrome by regulating gut microbiota dysbiosis and inflammatory cytokines

PURPOSE

Gut microbiota dysbiosis, a core pathophysiology of irritable bowel syndrome (IBS), is closely related to immunological and metabolic functions. Gut microbiota-based therapeutics have been recently explored in several studies. Bifico is a probiotic cocktail widely used in gastrointestinal disorders which relate to the imbalance of gut microbiota. However, the efficacy and potential mechanisms of Bifico treatment in IBS remains incompletely understood.

METHODS

Adopting a wrap restraint stress (WRS) -induced IBS mice model. Protective effect of Bifico in IBS mice was examined through abdominal withdrawal reflex (AWR) scores. 16S rDNA, ¹H nuclear magnetic resonance (¹H-NMR) and western blot assays were performed to analyze alterations of gut microbiota, microbiome metabolites and inflammatory cytokines, respectively.

RESULTS

Bifico could decrease intestinal visceral hypersensitivity. Although gut microbiota diversity did not increase, composition of gut microbiota was changed after treatment of Bifico, which were characterized by an increase of Proteobacteria phylum and Actinobacteria phylum, Muribaculum genus, Bifidobacterium genus and a decrease of Parabacteroides genus, Sutterella genus and Lactobacillus genus. Moreover, Bifico elevated the concentration of short-chain fatty acids (SCFAs) and reduced protein levels of interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α). From further Spearman's correlation analysis, Bifidobacterium genus were positively correlated with SCFAs including propionate, butyrate, valerate and negatively correlated with IL-6 and TNF-α.

CONCLUSION

Bifico could alleviate symptoms of IBS mice through regulation of the gut microbiota, elevating production of SCFAs and reducing the colonic inflammatory response.

Melatonin-Microbiome Two-Sided Interaction in Dysbiosis-Associated Conditions

Melatonin is a pineal indolamine, allegedly known as a circadian rhythm regulator, and an antioxidative and immunomodulatory molecule. In both experimental and clinical trials, melatonin has been shown to have positive effects in various pathologies, as a modulator of important biochemical pathways including inflammation, oxidative stress, cell injury, apoptosis, and energy metabolism. The gut represents one of melatonin's most abundant extra pineal sources, with a 400-times-higher concentration than the pineal gland. The importance of the gut microbial community-namely, the gut microbiota, in multiple critical functions of the organism- has been extensively studied throughout time, and its imbalance has been associated with a variety of human pathologies. Recent studies highlight a possible gut microbiota-modulating role of melatonin, with possible implications for the treatment of these pathologies. Consequently, melatonin might prove to be a valuable and versatile therapeutic agent, as it is well known to elicit positive functions on the microbiota in many dysbiosis-associated conditions, such as inflammatory bowel disease, chronodisruption-induced dysbiosis, obesity, and neuropsychiatric disorders. This review intends to lay the basis for a deeper comprehension of melatonin, gut microbiota, and host-health subtle interactions.

Fecal Microbiota Transplantation Role in the Treatment of Alzheimer's Disease: A Systematic Review

Alzheimer's, a neurodegenerative disease that starts slowly and worsens progressively, is the leading cause of dementia worldwide. Recent studies have linked the brain with the gut and its microbiota through the microbiota-gut-brain axis, opening the door for gut-modifying agents (e.g., prebiotics and probiotics) to influence our brain's cognitive function. This review aims to identify and summarize the effects of fecal microbiota transplantation (FMT) as a gut-microbiota-modifying agent on the progressive symptoms of Alzheimer's disease (AD). This systematic review is based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 guidelines. A systematic search was done using Google Scholar, PubMed, PubMed Central, and ScienceDirect databases in June 2022. The predefined criteria upon which the studies were selected are English language, past 10 years of narrative reviews, observational studies, case reports, and animal studies involving Alzheimer's subjects as no previous meta-analysis or systematic reviews were done on this subject. Later, a quality assessment was done using the available assessment tool based on each study type. The initial search generated 4,302 studies, yielding 13 studies to be included in the final selection: 1 cohort, 2 case reports, 2 animal studies, and 8 narrative reviews. Our results showed that FMT positively affected AD subjects (whether mice or humans). In humans, the FMT effect was measured by the Mini-Mental State Examination (MMSE), showing improvement in Alzheimer's symptoms of mood, memory, and cognition. However, randomized and nonrandomized clinical trials are essential for more conclusive results.

The Microbiota-Gut-Brain Axis in Psychiatric Disorders

Modulating the gut microbiome and its influence on human health is the subject of intense research. The gut microbiota could be associated not only with gastroenterological diseases but also with psychiatric disorders. The importance of factors such as stress, mode of delivery, the role of probiotics, circadian clock system, diet, and occupational and environmental exposure in the relationship between the gut microbiota and brain function through bidirectional communication, described as "the microbiome-gut-brain axis", is especially underlined. In this review, we discuss the link between the intestinal microbiome and the brain and host response involving different pathways between the intestinal microbiota and the nervous system (e.g., neurotransmitters, endocrine system, immunological mechanisms, or bacterial metabolites). We review the microbiota alterations and their results in the development of psychiatric disorders, including major depressive disorder (MDD), schizophrenia (SCZ), bipolar disorder (BD), autism spectrum disorder (ASD), and attention-deficit hyperactivity disorder (ADHD).

Is Melatonin the "Next Vitamin D"?: A Review of Emerging Science, Clinical Uses, Safety, and Dietary Supplements

Melatonin has become a popular dietary supplement, most known as a chronobiotic, and for establishing healthy sleep. Research over the last decade into cancer, Alzheimer's disease, multiple sclerosis, fertility, PCOS, and many other conditions, combined with the COVID-19 pandemic, has led to greater awareness of melatonin because of its ability to act as a potent antioxidant, immune-active agent, and mitochondrial regulator. There are distinct similarities between melatonin and vitamin D in the depth and breadth of their impact on health. Both act as hormones, affect multiple systems through their immune-modulating, anti-inflammatory functions, are found in the skin, and are responsive to sunlight and darkness. In fact, there may be similarities between the widespread concern about vitamin D deficiency as a "sunlight deficiency" and reduced melatonin secretion as a result of "darkness deficiency" from overexposure to artificial blue light. The trend toward greater use of melatonin supplements has resulted in concern about its safety, especially higher doses, long-term use, and application in certain populations (e.g., children). This review aims to evaluate the recent data on melatonin's mechanisms, its clinical uses beyond sleep, safety concerns, and a thorough summary of therapeutic considerations concerning dietary supplementation, including the different formats available (animal, synthetic, and phytomelatonin), dosing, timing, contraindications, and nutrient combinations.

Association between Microbiome-Related Human Genetic Variants and Fasting Plasma Glucose in a High-Cardiovascular-Risk Mediterranean Population

Background and Objectives: The gut microbiota has been increasingly recognized as a relevant factor associated with metabolic diseases. However, directly measuring the microbiota composition is a limiting factor for several studies. Therefore, using genetic variables as proxies for the microbiota composition is an important issue. Landmark microbiome-host genome-wide association studies (mbGWAS) have identified many SNPs associated with gut microbiota. Our aim was to analyze the association between relevant microbiome-related genetic variants (Mi-RSNPs) and fasting glucose and type 2 diabetes in a Mediterranean population, exploring the interaction with Mediterranean diet adherence. Materials and Methods: We performed a cross-sectional study in a high-cardiovascular-risk Mediterranean population (n = 1020), analyzing the association of Mi-RSNPs (from four published mbGWAS) with fasting glucose and type 2 diabetes. A single-variant approach was used for fitting fasting glucose and type 2 diabetes to a multivariable regression model. In addition, a Mendelian randomization analysis with multiple variants was performed as a sub-study. Results: We obtained several associations between Mi-RSNPs and fasting plasma glucose involving gut Gammaproteobacteria_HB, the order Rhizobiales, the genus Rumminococcus torques group, and the genus Tyzzerella as the top ranked. For type 2 diabetes, we also detected significant associations with Mi-RSNPs related to the order Rhizobiales, the family Desulfovibrionaceae, and the genus Romboutsia. In addition, some Mi-RSNPs and adherence to Mediterranean diet interactions were detected. Lastly, the formal Mendelian randomization analysis suggested combined effects. Conclusions: Although the use of Mi-RSNPs as proxies of the microbiome is still in its infancy, and although this is the first study analyzing such associations with fasting plasma glucose and type 2 diabetes in a Mediterranean population, some interesting associations, as well as modulations, with adherence to the Mediterranean diet were detected in these high-cardiovascular-risk subjects, eliciting new hypotheses.