Search Results (929)

Alzheimer’s disease (AD) is a progressive neurodegenerative disorder with a complex etiology whose exact mechanisms are not fully understood. In recent years, there has been growing interest in the role of the gastrointestinal microbiota in the pathogenesis of AD, particularly in the context of the gut–brain axis. The purpose of this review is to discuss the current state of knowledge regarding potential relationships between the composition of the gut microbiota and the development and progression of AD. Preclinical and clinical studies indicating that microbiota imbalances (dysbiosis) may contribute to increased inflammation, increased permeability of the intestinal and blood–brain barriers, and accumulation of pathological proteins such as beta-amyloid and tau are analyzed. The effects of diet, probiotics and microbiota interventions on cognitive function were also discussed. An attempt was also made to evaluate microbiota disruption as a potential early marker of AD development. Although the mechanisms require further study, the role of the gut microbiota appears to be an important and promising direction in understanding the pathophysiology of AD and developing potential therapeutic and diagnostic strategies. Full article

Obsessive–compulsive disorder (OCD) is a multifactorial condition, and interest in gut–brain interactions is increasing. We conducted a systematic two-step review, registered in PROSPERO (CRD420251083936). Step 1 mapped core OCD biology to gut-relevant pathways, including neuroimmune activation, epithelial barrier function, microbial metabolites, and stress circuitry, to clarify plausible mechanisms. Step 2 synthesized evidence from human and preclinical studies that measured or manipulated microbiota. Searches across PubMed, EMBASE, Web of Science, PsycINFO, and Cochrane (September 2025) yielded 357 biological and 20 microbiota-focused studies. Risk of bias was assessed using the Joanna Briggs Institute checklist for human studies and SYRCLE’s tool for animal studies. Although taxonomic findings in human cohorts were heterogeneous, functional patterns converged: reduced short-chain fatty acid capacity, enrichment of pro-inflammatory pathways, and host markers of barrier disruption and inflammation correlating with OCD severity. Transferring patient microbiota to mice induced OCD-like behaviors with neuroinflammatory changes, partly rescued by metabolites or barrier-supporting strains. Mendelian randomization suggested possible causal contributions at higher taxonomic levels. Diet, especially fiber intake, and psychotropic exposure were major sources of heterogeneity. Evidence supports the microbiota as a modifiable co-factor in a subset of OCD, motivating diet-controlled, stratified clinical trials with composite host–microbe endpoints. Full article

Pet humanization, particularly in dogs and cats, has transformed animal healthcare and highlighted the importance of nutrition in promoting human–pet social interaction, pet psychophysical well-being and, possibly, longevity. Nutraceuticals, such as omega-3 fatty acids, prebiotics, probiotics, plant extracts and dietary supplements, are endowed with antioxidant, anti-inflammatory, immune-modulating, cognitive-enhancing and gut-microbiota balancing properties. These effects have been shown to contribute to the possible prevention and management of bone and skin diseases, as well as gastrointestinal and behavioral disturbs. Moreover, the human–animal bond has been shown to play a pivotal role in reducing stress, improving sociability, and modulating pets’ emotional and physiological states. Evidence also suggests that nutrition and social interactions can influence the gut–brain axis, impacting the behavior, cognition, and resilience to stress-related disorders. Besides underlining the value of nutraceutical integration into pet nutrition strategies and offering a comprehensive, evidence-based perspective on their potential in improving animal welfare, literature reports about drawbacks of the use/misuse of such substances have been reported. Full article

Background/Objectives: Polygonatum sibiricum (PS), possessing both medicinal and edible dual functions, boasts a long history of application in Chinese traditional practices. As a component of its effectiveness, Polygonatum sibiricum polysaccharides (PSPs) have been reported to exert neuroprotective effects. However, the protective effects of PS on the cognitive deficits induced by simulated weightlessness remain unclear. This study evaluated the therapeutic potential of PSPs to counteract the cognitive deficits induced by simulated weightlessness using the Hindlimb Unloading (HU) method. Methods: Mice were subjected to HU to establish cognitive impairment, and PSP was administered for four weeks. The Morris water maze test (MWMT) and passive avoidance test (PAT) were used to evaluate the cognitive abilities of mice, followed by an analysis of molecular mechanisms. Results: PSP treatment increased learning and memory in mice. PSP treatment partially restored gut microbial diversity and composition towards beneficial taxa, including Lactobacillus and Firmicutes, while inhibiting proinflammatory genera, including Alistipes and Proteus. At the same time, PSP upregulated Claudin-5 and Zonula Occludens-1 (ZO-1) levels in the colon, suggesting improved intestinal barrier integrity, and decreased neuroinflammatory response by inhibiting NLRP3 inflammasome activation and NF-κB phosphorylation in the hippocampus. It also modulated neurotransmitter homeostasis along the microbiota–gut–brain (MGB) axis by increasing the levels of gamma-aminobutyric acid (GABA) and serotonin (5-HT) while reducing the levels of excitotoxic metabolites, including Glutamate (Glu) and 3-hydroxykynurenine (3-HK). Conclusions: These results indicate that PSP may have beneficial effects on HU-induced cognitive impairment by regulating gut microbiota, enhancing barrier function, suppressing neuroimmune signaling, and restoring neurotransmitter balance. Full article

Bone immunity represents a dynamic interface where skeletal homeostasis intersects with systemic immune regulation. We synthesize emerging paradigms by contrasting two functionally distinct microenvironments: the marrow cavity, a hematopoietic and immune cell reservoir, and cancellous bone, a metabolically active hub orchestrating osteoimmune interactions. The marrow cavity not only generates innate and adaptive immune cells but also preserves long-term immune memory through stromal-derived chemokines and survival factors, while cancellous bone regulates bone remodeling via macrophage-osteoclast crosstalk and cytokine gradients. Breakthroughs in lymphatic vasculature identification challenge traditional views, revealing cortical and lymphatic networks in cancellous bone that mediate immune surveillance and pathological processes such as cancer metastasis. Central to bone immunity is the neuro–immune–endocrine axis, where sympathetic and parasympathetic signaling bidirectionally modulate osteoclastogenesis and macrophage polarization. Gut microbiota-derived metabolites, including short-chain fatty acids and polyamines, reshape bone immunity through epigenetic and receptor-mediated pathways, bridging systemic metabolism with local immune responses. In disease contexts, dysregulated immune dynamics drive osteoporosis via RANKL/IL-17 hyperactivity and promote leukemic evasion through microenvironmental immunosuppression. We further propose the “brain–gut–bone axis” as a systemic regulatory framework, wherein vagus nerve-mediated gut signaling enhances osteogenic pathways, while leptin and adipokine circuits link marrow adiposity to inflammatory bone loss. These insights redefine bone as a multidimensional immunometabolic organ, integrating neural, endocrine, and microbial inputs to maintain homeostasis. By elucidating the mechanisms of immune-driven bone pathologies, this work highlights therapeutic opportunities through biomaterial-mediated immunomodulation and microbiota-targeted interventions, paving the way for next-generation treatments in osteoimmune disorders. Full article

Traumatic brain injury (TBI) remains a major global health problem, contributing significantly to morbidity and mortality worldwide. Despite advances in understanding its complex pathophysiology, current therapeutic strategies are insufficient in addressing the long-term cognitive, emotional, and neurological impairments. While the primary mechanical injury is immediate and unavoidable, the secondary phase involves a cascade of biological processes leading to neuroinflammation, blood–brain barrier (BBB) disruption, and systemic immune activation. The heterogeneity of patient responses underscores the urgent need for reliable biomarkers and targeted interventions. Emerging evidence highlights the gut–brain axis as a critical modulator of the secondary phase, with microbiota-derived extracellular vesicles (MEVs) representing a promising avenue for both diagnosis and therapy. MEVs can cross the intestinal barrier and BBB, carrying biomolecules that influence neuronal survival, synaptic plasticity, and inflammatory signaling. These properties make MEVs promising biomarkers for early detection, severity classification, and prognosis in TBI, while also offering therapeutic potential through modulation of neuroinflammation and promotion of neural repair. MEV-based strategies could enable tailored interventions based on the individual’s microbiome profile, immune status, and injury characteristics. The integration of multi-omics with artificial intelligence is expected to fully unlock the diagnostic and therapeutic potential of MEVs. These approaches can identify molecular subtypes, predict outcomes, and facilitate real-time clinical decision-making. By bridging microbiology, neuroscience, and precision medicine, MEVs hold transformative potential to advance TBI diagnosis, monitoring, and treatment. This review also identifies key research gaps and proposes future directions for MEVs in precision diagnostics and gut microbiota-based therapeutics in neurotrauma care. Full article

Functional bowel disorders (FBDs) are chronic gastrointestinal conditions characterized by recurrent symptoms associated with gut microbiota dysbiosis. Although accumulating evidence suggests that probiotics can improve symptoms in patients with FBD, the underlying mechanisms remain to be fully elucidated. In this randomized, double-blind, placebo-controlled clinical trial, 38 adults meeting the Rome IV diagnostic criteria of functional constipation (FC) and functional diarrhea (FD) received either a multi-strain probiotic complex or placebo for 8 weeks. Clinical outcomes were evaluated using the Irritable Bowel Syndrome Severity Scoring System (IBS-SSS), bowel habits questionnaire, and IBS Quality of Life (IBS-QoL) instrument. Fecal samples were collected at baseline and at week 8 for gut microbiota profiling via 16S rRNA gene sequencing and metabolomic analysis using gas chromatography–mass spectrometry. Probiotic supplementation significantly reduced the severity of abdominal bloating and its interference with quality of life, and improved the body image domain of the IBS-QoL. Beta diversity analysis showed significant temporal shifts in the probiotic group, while 16S rRNA sequencing revealed an increased relative abundance of Faecalibacterium prausnitzii and Blautia stercoris. Fecal metabolomic analysis further indicated elevated levels of metabolites implicated in the gut–brain axis. Multi-strain probiotic supplementation alleviated gastrointestinal symptoms and improved aspects of psychosocial well-being in adults with FBDs, potentially through modulation of the human gut microbiome. Full article

Background: Alterations of the gut microbiota have been increasingly implicated in the pathogenesis of dementia through mechanisms involving systemic inflammation, immune dysregulation, and gut–brain axis disruption. Clinical evidence, however, remains fragmented. Objectives: This systematic review aimed to characterize gut microbiota profiles in individuals with mild cognitive impairment (MCI) or Alzheimer’s dementia (AD), explore mechanistic associations with neurodegeneration, and evaluate the impact of microbiota-targeted interventions on cognitive outcomes. Methods: Following PRISMA 2020 guidelines and a registered protocol (PROSPERO CRD420251074832), PubMed/Medline was searched through May 2025. Eligible studies included randomized controlled trials (RCTs) and cohort and case–control studies assessing microbiota composition or interventions in participants with MCI or AD. Results: Twenty-one studies were included (1 RCT, 20 observational; sample size 22–302). Most used 16S rRNA sequencing; one used shotgun metagenomics. Across cohorts, MCI and AD patients consistently showed reduced short-chain fatty acid-producing bacteria (Faecalibacterium, Ruminococcaceae, Lachnospiraceae) and increased pro-inflammatory taxa (Escherichia/Shigella, Enterobacteriaceae, Bacteroides). Several studies reported reduced microbial diversity. Specific taxa, including Akkermansia muciniphila and Faecalibacterium, were associated with amyloid burden, hippocampal atrophy, and cognitive decline. Environmental and dietary factors influenced microbial composition and cognition. The RCT reported that probiotic supplementation improved inflammatory markers and BDNF levels, although changes in microbiota composition were inconsistent. Conclusions: Gut dysbiosis is strongly associated with cognitive impairment and markers of neurodegeneration. Modulation of the microbiota through diet and probiotics emerges as a promising avenue for dementia prevention and management, though robust longitudinal and interventional studies are needed to confirm causality and therapeutic efficacy. Full article

Background: Amyotrophic lateral sclerosis (ALS) evolution is influenced by many dietary factors, biochemical and hormonal inter-relations and gut microbiota. This study focuses on dynamics by conducting a plasmatic quantitative analysis of six of the main short-chain fatty acids (SCFAs) for ALS patients and the shifts in circulating SCFA profiles during ALS progression as well as their potential responsiveness or change due to dietary modulation. Methods: A 12-month prospective study in parallel with control group determinations was conducted. The patients diagnosed with ALS were evaluated at the start of the study (T0) followed by a six-month observation time frame (T1) and after another six months of a Mediterranean diet intervention (T2). Plasma SCFAs were determined using liquid chromatography coupled to mass spectrometry to showcase the plasmatic profiles. Correlation between plasma levels of SCFAs and patients’ clinical characteristics next to correlations between plasma SCFA levels at T1 and T2 were performed. Results: A significant increase between control group and patients at T0 was observed for acetic, propionic, butyric and hydroxy-butyric acid. Hexanoic acid levels stagnated and 4-methyl-valeric acid concentrations decreased. Evolutions from T1 and T2 impacted acetate, propionate and 4-methyl-valerate. Conclusions: The study offers a better understanding regarding the differences in SCFA levels in ALS patients. The Mediterranean diet may impact the levels of acetic and propionic acid, indicating the modulation of SCFA production by gut microbiota. Full article

Background: An imbalance in the immune system, stress response, and gut microbiota can contribute to the onset and progression of anxiety and depression. This pilot study aimed to explore the effect of Weizmannia coagulans BC99 on anxiety and depression through the gut microbiota–brain axis. Methods: A total of 79 participants with Hamilton Depression Rating Scale (HAMD-17) ≥ 8 or Hamilton Anxiety Rating Scale (HAMA-14) ≥ 7 were included and completed the study. The participants were randomly assigned to either the placebo group or the BC99 intervention group. The intervention lasted 8 weeks, with participants receiving either dextrin (3 g/day) or BC99 probiotics (3 g/day, 5 × 10⁹ CFU) daily. Pre- and post-intervention comparisons were made on HAMD and HAMA scores, inflammatory cytokines, neurotransmitters, gut microbiota, and short-chain fatty acids. Results: Results showed that after 8 weeks, BC99 and placebo intervention were effective in reducing HAMD and HAMA scores, and HAMD and HAMA scores in BC99 group were reduced by 2.40 and 5.53 points compared the placebo group, and the response and remission rates were also higher than that of the placebo, but there was no significant difference. BC99 also could regulate the levels of inflammatory cytokines IL-17 and IL-10, and increase neurotransmitter levels of γ-GABA and NO. Moreover, compared with the placebo group, BC99 also enhanced the abundance of beneficial bacteria such as Faecalibactrium, Megamonas, Dialister, and Agathobacter, which were closely associated with clinical indicators of mental disorders, and increased the production of short-chain fatty acids. Conclusions: These preliminary findings suggested that BC99 might alleviate anxiety and depression symptoms by regulating the level of neurotransmitters or the change of microbiota, which needed further verification in subsequent animal or clinical experiments. Full article

Alzheimer’s disease (AD) is the most common cause of dementia worldwide, and there are still no strategies to slow or prevent its clinical progression. Significant financial and research resources have been invested into studying the pathology of AD. However, its pathogenesis is not fully understood. This review provides a comprehensive analysis of current understanding of AD pathogenesis, including classical hypotheses (amyloid cascade, tau pathology, neuroinflammation, oxidative stress), emerging mechanisms (cellular senescence, endoplasmic reticulum stress, ubiquitin-proteasome system dysfunction), and alternative mechanisms (cholinergic dysfunction, glutamate excitotoxicity, disruption of the microbiota–gut–brain axis, and autophagy). Schematic illustrations summarize the relationships between the hypotheses and their role in the pathogenesis of AD. Particular attention is paid to the systematization of promising biological targets and the analysis of modern ligands of various nature, including small molecules, peptides, antibodies and their fragments, natural compounds, as well as innovative hybrid and multifunctional structures. A separate section is devoted to radiopharmaceuticals for PET imaging (Florbetaben, Flortaucipir, etc.) and promising therapeutic agents. Thus, in this review we (1) systematize modern concepts of AD pathogenesis, including classical, emerging mechanisms and alternative hypotheses; (2) conduct a comparative analysis of ligand classes (small molecules, peptides, antibodies, etc.) and their therapeutic potential; and (3) discuss the clinical prospects of radiopharmaceuticals for PET imaging and targeted therapy. The work provides a comprehensive analysis of modern approaches, which can help in the development of more effective drugs against AD. Full article

In the recent years, the accelerating global demographic shift toward population aging has been accompanied by a marked increase in the prevalence of neurodegenerative disorders, notably Alzheimer’s disease, Parkinson’s disease, amyotrophic lateral sclerosis, and multiple sclerosis. Among emerging approaches, dietary interventions targeting the gut–brain axis have garnered considerable attention, owing to their potential to modulate key pathogenic pathways underlying neurodegenerative processes. This review synthesizes current concepts in precision nutrition and elucidates neurohumoral, immune, and metabolic regulatory mechanisms mediated by the gut microbiota, including the roles of the vagus nerve, cytokines, short-chain fatty acids, vitamins, polyphenols, and microbial metabolites. Emerging evidence underscores that dysbiotic alterations contribute to compromised barrier integrity, the initiation and perpetuation of neuroinflammatory responses, pathological protein aggregations, and the progressive course of neurodegenerative diseases. Collectively, these insights highlight the gut microbiota as a pivotal target for the development of precision-based dietary strategies in the prevention and mitigation of neurodegenerative disorders. Particular attention is devoted to key bioactive components such as prebiotics, probiotics, psychobiotics, dietary fiber, omega-3 fatty acids, and polyphenols that critically participate in regulating the gut–brain axis. Contemporary evidence on the contribution of the gut microbiota to the pathogenesis of Alzheimer’s disease, Parkinson’s disease, and multiple sclerosis is systematically summarized. The review further discusses the prospects of applying nutrigenomics, chrononutrition, and metagenomic analysis to the development of personalized dietary strategies. The presented findings underscore the potential of integrating precision nutrition with targeted modulation of the gut–brain axis as a multifaceted approach to reducing the risk of neurodegenerative diseases and preserving cognitive health. Full article

Aging is the result of the accumulation of a great variety of molecular and cellular damage over time. During aging, the brain undergoes changes and diseases such as depression, dementia, anxiety, Alzheimer’s, delirium, behavioral disorders and aggression, and prolonged mourning, among others, appear. The gut–brain axis suggests that the gut and the brain have a bidirectional communication, so it is important to maintain proper intestinal health to strengthen the neurological changes of this age group. The intestinal microbiota is a dynamic and highly complex ecosystem of microorganisms residing in the gastrointestinal tract. The bidirectional and dynamic communication between the homeostatic systems, such as the endocrine and immune systems, as well as the nervous system, allow us to face problems associated with several diseases. Probiotics are defined as non-pathogenic live microorganisms that provide beneficial effects to the organism and participate in the prevention and treatment of diseases, which is the reason why it is important to promote interventions that keep intestinal microbiota in eubiosis (microbiota balance). The concentration and balance of the intestinal microbiota depend on several conditions, such as diet, antibiotic consumption, and lifestyle, to mentioned a few. However, interventions with probiotics have shown improvements in both cognitive function and processes that promote neurodegeneration. It is such that the research has been directed on designing strategies that improve not only oral bioavailability but also intestinal adhesion and retention, to clarify the frequency and dosage that should be consumed. Full article

Bone health is critically influenced by the oral and gut microbiota, which are among the largest microbial reservoirs in the human body. These microbiota play essential roles in maintaining bone mass through immune modulation, metabolite production, and nutrient resorption. Recent observations have underscored that extracellular vesicles (EVs) derived from oral and gut microbiota may circulate to the brain and bone marrow, suggesting their integral roles in the gut–brain–bone axis and oral–brain–bone axis. This review outlines the current research status of bacterial extracellular vesicles (BEVs), including their biogenesis, classification, structural features, and cargo composition, with emphasis on factors influencing cargo heterogeneity and the consequences of cellular uptake and presentation. Oral-microbiota-derived BEVs and their cargo associated with bone health are highlighted, along with recent evidence linking BEVs to systemic dis-eases and the potential integration into the oral–gut–bone axis. Preclinical animal studies on BEV dosage, routes of administration, and disease models are summarized, together with the limitations of current approaches and strategies for engineering BEVs. Finally, an overview of translational applications and future therapeutic prospects is provided, aiming to advance the understanding of BEVs as innovative tools for the treatment and prevention of bone-related diseases. Full article

Depression is a prevalent and disabling psychiatric disorder, characterized by persistent disturbances in mood, cognition, and physiological processes, which collectively lead to substantial impairments in daily functioning and quality of life. This review provides a comprehensive overview of the biological mechanisms implicated in the pathophysiology of depression, including neurotransmitter dysregulation, oxidative stress, inflammatory processes, hypothalamic-pituitary-adrenal (HPA) axis dysfunction, mitochondrial impairment, and alterations in the gut-brain axis. Furthermore, it explores the role of diet in both the prevention and management of depression, with particular emphasis on Mediterranean, anti-inflammatory, and ketogenic dietary patterns, while contrasting these with the detrimental impact of a Western dietary pattern. Specific nutrients-such as n-3 polyunsaturated fatty acids (PUFAs), B-complex vitamins, vitamins D and E, zinc, selenium, and polyphenols-are highlighted for their potential roles in modulating neurotransmission, attenuating inflammation, and supporting gut microbiota homeostasis. Despite growing scientific interest in nutrition-based interventions, current evidence on the comparative efficacy of different dietary approaches remains limited. Future research is warranted to elucidate the therapeutic potential of dietary strategies as adjuncts to conventional treatments for depression and to facilitate the development of evidence-based nutritional recommendations for clinical practice. Full article