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Diagnostic Value and Limitations of Dermoscopy in Humans and Animals: A Critical Comparative Analysis.

BACKGROUND: Dermoscopy is a noninvasive imaging technique that is well-established in human dermatology, where it enhances the diagnosis of neoplastic, inflammatory, infectious, and alopecic skin disorders. In veterinary dermatology, its use is expanding yet remains heterogeneous and largely descriptive, despite growing evidence of conserved dermoscopic patterns across species. HYPOTHESIS/OBJECTIVES: To review the applications of dermoscopy in veterinary dermatology, and to provide a comparative analysis of dermoscopic features observed in dogs, cats, and horses in relation to corresponding findings in human dermatology. MATERIALS AND METHODS: A systematic review of the literature reporting dermoscopic findings in veterinary dermatology was conducted in accordance with PRISMA guidelines. PubMed, Scopus and Google Scholar were searched for studies published up to 30 July 2025. Eligible studies included original articles describing dermoscopic features in dogs, cats, or horses. Extracted data included species, dermatological condition, dermoscopic findings, device type and histopathological correlation, when available. Levels of evidence were assessed using the Oxford Centre for Evidence-Based Medicine criteria. RESULTS: Thirty studies met the inclusion criteria. Most were descriptive case reports or case series. Dermoscopy was applied to a wide range of conditions, including alopecias, parasitic infestations, dermatophytosis, neoplastic and sebaceous lesions, inflammatory dermatoses, and congenital vascular anomalies. Recurrent dermoscopic features showed strong similarities to those described in human dermatology, although species-specific anatomical differences influenced interpretation. CONCLUSIONS: Dermoscopy represents a valuable adjunct diagnostic tool in veterinary dermatology, with clear translational relevance. Standardisation of terminology and further prospective studies are required to support its broader clinical integration.

Animals

Randomized study of the effects of testosterone administration on severity of asthma in horses.

BACKGROUND: Low testosterone concentrations are associated with poor lung function in human asthmatics, and androgen administration improves airway obstruction in women with asthma. HYPOTHESIS/OBJECTIVES: Testosterone improves clinical scores, lung function, airway neutrophilia, and airway remodeling in horses with severe asthma. ANIMALS: Ten horses affected by severe asthma from a research herd. METHODS: In a randomized, blinded, crossover study, horses received dexamethasone (0.06&#xa0;mg/kg PO q24h for 10&#xa0;days) or a single intramuscular injection of testosterone cypionate (0.35&#xa0;mg/kg), with a 2-week washout period. Clinical respiratory scores were assessed at days 0, 2, 5, and 10; lung function was evaluated at days 0, 5, and 10; and bronchoalveolar lavage fluid cytology and central airway remodeling at days 0 and 10. Mixed linear models were used for analysis. RESULTS: The respiratory clinical scores improved with dexamethasone administration (median [95% CI], from 12 (9-13) to 5 (3-6), P&#xa0;<&#xa0;.001), and remained unchanged with testosterone administration (from 10 [8-12] to 9 [8-11], P&#xa0;=&#xa0;.6). Pulmonary elastance improved with both treatments, but the effect was more pronounced with dexamethasone administration (from 5.1&#xa0;cm H2O/L [2.4-5.8] to 0.5 [0.4-0.8], P&#xa0;<&#xa0;.001) than with testosterone administration (from 4.5&#xa0;cm H2O/L [1.6-8.5] to 3.0 [1.0-4.1], P&#xa0;=&#xa0;.04). Pleural pressure and pulmonary resistance decreased only with dexamethasone. Neither treatment altered airway neutrophilia or bronchial remodeling. CONCLUSIONS AND CLINICAL IMPORTANCE: Testosterone is less effective than dexamethasone and only mildly improves pulmonary elastance in horses with severe asthma.

Animals

Development and validation of a liquid chromatography-tandem mass spectrometry method for the quantification of twenty-five steroids in equine serum.

Steroids are potential biomarkers for monitoring equine pregnancy. However, immunoassays currently used for their quantification suffer from cross-reactivity and limited specificity, thus requiring more accurate methods. This study reports the development and validation of a robust liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for simultaneous quantification of 25 steroids covering the main biosynthetic pathways of progestogens, corticosteroids, androgens, and estrogens. Steroids were extracted by protein precipitation followed by evaporation, derivatization, and reconstitution before LC-MS/MS analysis. A surrogate matrix was used for calibration and validation to avoid endogenous interference. Validation was performed according to and partly adapted from Clinical and Laboratory Standards Institute guidelines (CLSI), including linearity, trueness, precision, limits of detection and quantification, measurement uncertainty, recovery, matrix effects, carryover, selectivity, and stability. Calibration curves were fitted using the best-performing weighted linear or quadratic regression model, yielding excellent linearity (R2&#xa0;>&#xa0;0.990), trueness between -9.0% and 2.3%, and intra- and inter-day precision <6.3%. Lower limits of quantification ranged from 2.07 to 2250&#xa0;pg/mL depending on physiological analytes concentration. Extraction recovery averaged 24.3-114.9%, matrix effects were acceptable, and accuracy ranged from 94.4% to 98.9%. No carryover or interferences were detected. Measurement uncertainty remained <15%. This study presents the first LC-MS/MS method partially validated per CLSI criteria for the quantification of 24 steroids in equine serum. The method offers a sensitive and specific alternative to immunoassays and provides a robust tool for equine steroid profiling with potential applications in pregnancy monitoring, placentitis diagnosis, and fetal sex determination.

Animals

Eltrombopag Added to Standard Immunosuppressive Treatment as Front-Line Therapy for Severe Aplastic Anemia: Long-Term Outcomes of the Phase-3 Randomized Superiority EBMT-SAAWP RACE Study.

The RACE study (NCT02009747) compared horse antithymocyte globulin (hATG) plus cyclosporine A (CsA)&#x2009;&#xb1;&#x2009;eltrombopag as initial immunosuppressive treatment (IST) for severe aplastic anemia. Here we report the final 2-year analysis of this prospective randomized phase III study. One hundred ninety-seven treatment-naive patients were randomized to standard IST (hATG 40&#x2009;mg/kg&#x2009;&#xd7;&#x2009;4&#x2009;days and CsA 5&#x2009;mg/kg/day; arm A; n&#x2009;=&#x2009;101) or standard IST&#x2009;+&#x2009;eltrombopag at the dose of 150&#x2009;mg/day (arm B; n&#x2009;=&#x2009;96) from day +14 until 6&#x2009;months (or 3&#x2009;months, in case of complete response). The median follow-up was 23.2&#x2009;months. The 2-year cumulative incidence of complete response was significantly superior in arm B (62.4% vs. 35.3%; p&#x2009;<&#x2009;0.001). The 2-year overall survival (OS) was 86% in arm A and 91% in arm B (p&#x2009;=&#x2009;0.081), with hazard ratio (HR), adjusted for age and disease severity, of 0.54 (p&#x2009;=&#x2009;0.064). The 2-year disease-free survival (DFS) was 56% vs. 37% (adjusted HR&#x2009;=&#x2009;0.49; p&#x2009;<&#x2009;0.001), while event-free survival (EFS) was 48% vs. 32% (p&#x2009;<&#x2009;0.001), with adjusted HR&#x2009;=&#x2009;0.54 (p&#x2009;<&#x2009;0.001), both significantly superior for arm B. The cumulative incidence of relapse was comparable in the two arms, while evolution to clinical paroxysmal nocturnal hemoglobinuria was 8% in arm A and 1% in arm B (p&#x2009;=&#x2009;0.041). The risk of clonal evolution remained negligible, with one patient in arm A and two in arm B developing karyotypic abnormalities. The initial hematological response benefit of eltrombopag added to IST as front-line treatment of AA is associated with better 2-year OS, DFS, and EFS without increased risk of secondary myeloid malignancies.

Humans

Wildlife forensic DNA evidence links a suspected vehicle to a fatal lowland tapir (Tapirus terrestris) collision in Misiones, Argentina.

Vehicle collisions are recognized as a major driver of biodiversity loss, particularly in road-dense landscapes, exceeding the impact of invasive species and wildlife trafficking. For large-bodied, slow-reproducing, and low-abundance species, such as the lowland tapir (Tapirus terrestris), this threat can have major impacts. Here, we present a wildlife forensic investigation in Misiones, Argentina, involving a tapir, a species afforded the highest level of legal protection as a Provincial Natural Monument. The fatal hit-by-vehicle (HBV) incident occurred in northern Misiones on 31 March 2019 along Provincial Route 19, in a portion that bisects Parque Provincial Urugua-&#xed;, with the driver involved in the collision leaving the scene. The suspect was later located and claimed that the damage to the vehicle resulted from a collision with a horse (Equus caballus) rather than a tapir. To legally resolve the incident, DNA (hair and blood) recovered from the suspected vehicle's bumper (evidence) was compared with tissue samples from the tapir carcass (reference). Genetic confirmation of species identity used a 110-bp region of the mitochondrial cytochrome b gene, and individual identity was assessed using 12 species-specific microsatellite loci. These analyses confirmed that all evidence matched the tapir carcass at both species and individual levels, strongly supporting the association between the suspected vehicle and the HBV tapir, and refuting the alternative explanation proposed by the driver. This case demonstrates the value of using wildlife forensic genetics to reconstruct wildlife-vehicle collisions, supporting environmental law enforcement, and strengthening conservation efforts in the Atlantic Forest of Misiones, Argentina.

Animals

Assessment of Genetic Correlations Between Tobacco or Alcohol Use and Neurodegenerative Diseases Using East Asian Genetic Ancestry Genome-Wide Association Study Results.

Alzheimer's disease (AD) and Parkinson's disease (PD) are the most prevalent late-onset neurodegenerative diseases worldwide. Both are influenced in part by genetic factors and are currently incurable. Tobacco and alcohol, the two most common substances used among the general adult population, are potential AD/PD risk factors and are also heritable. Although important progress has been made, most existing research on the genetics of AD and PD has been carried out in individuals of European genetic ancestry. Investigations in a broad range of groups are crucial to understand disease mechanisms. Given the current availability of ancestry-specific tobacco and alcohol use as well as AD and PD genome-wide association study summary statistics, we performed global and local genetic correlation analyses using East Asian datasets. Genes within the correlated genetic regions were subsequently used to identify potentially enriched biological pathways between substance use and neurodegenerative diseases. We identified a global genetic correlation between smoking cessation and PD, which we confirmed in complementary European genetic ancestry data. Gene set enrichment analyses highlighted potentially shared genetic mechanisms between breast cancer and AD, which warrants further exploration. This work aims to promote further analyses across genetic ancestry groups.

Female

Definition and prevalence of residual disease in inflammatory arthritis: a systematic literature review and meta-analysis.

OBJECTIVE: To assess how residual disease (i.e., clinically relevant signs/symptoms despite achieving treatment targets) is defined in rheumatoid arthritis (RA), psoriatic arthritis (PsA) or axial spondyloarthritis (axSpA), and estimate the prevalence/severity of residual disease in these diseases. METHODS: Systematic review of original research in RA/PsA/axSpA. Two key residual disease components were extracted: (1) the patient's disease state (often remission/low disease activity) and (2) which residual signs/symptoms were measured, e.g. swollen joints or fatigue (indicators of residual disease). Frequencies of the disease states and indicators were described (Objective 1). Prevalence (%) and severity (absolute score on instrument, e.g. fatigue NRS) of residual disease was analysed by indicator, using random effects meta-analysis (&#x2265;4 studies) or descriptively (<4 studies) (Objective 2). RESULTS: Regarding residual disease definitions (59 studies), disease states were almost exclusively disease activity-based (>99%), but with much variation in specific instruments/thresholds. Across diseases, physician-reported (66%) and patient-reported (73%) indicators were used more often than laboratory indicators to define residual disease (46%). Especially peripheral joint counts, pain, physical function and CRP were frequently used (42-56% of studies). The prevalence of residual disease (84 studies) was notable. For example, 5-25% of RA and PsA patients in remission still had swollen joints, and up to one-third reported relevant pain or fatigue. For axSpA, evidence was limited. CONCLUSION: Residual disease definitions in RA/PsA/axSpA are based on various disease activity instruments/thresholds and indicators (signs/symptoms). Residual disease affects up to half of patients. Future research should aim for a consensus-based definition of residual disease.

Humans

Retinoid dynamics in immune cells during age-related diseases.

Retinoids comprise vitamin A and its structurally related natural and synthetic derivatives. Retinoid dynamics involves multiple retinoid forms, carrier proteins, and enzymes that orchestrate the absorption, transport, storage and biotransformation of dietary vitamin A. Beyond their canonical metabolic functions, metabolites and proteins involved in retinoid metabolism also play distinct roles in signal transduction and transcriptome reprogramming, broadening the mechanisms that influence immune cell fate decisions. Age&#x2011;related changes in retinoid bioavailability and signaling intensity alter immune cell polarization and function, thereby contributing to the pathogenesis of chronic inflammation in neurodegenerative diseases, cardiovascular diseases, osteoarthritis, and other age-related diseases. In this review, we focus on age-related alterations in the retinoid metabolic pathway and their impact on inflammation and the progression of age-related diseases. This review highlights the pivotal role of retinoid metabolism in anti-ageing interventions and considers future directions and challenges in this field.

Humans

Mechanistic Insights Into the Association Between Gut Microbiota Diversity and Atherosclerosis, Acute Coronary Syndrome, and Peripheral Arterial Disease Progression.

BACKGROUND: The gut microbiome has emerged as a potential contributor to cardiovascular diseases (CVDs), including atherosclerosis, acute coronary syndrome (ACS), and peripheral arterial disease (PAD). While observational studies link dysbiosis to CVD, causal relationships remain uncertain. METHODS: This narrative review synthesizes evidence from human observational studies, clinical interventions, and experimental models to distinguish association from mechanistic plausibility and clinical causality. Literature was searched through July 2026 in PubMed/MEDLINE, Web of Science, and Scopus. RESULTS: Microbial metabolites-including trimethylamine N-oxide (TMAO), short-chain fatty acids (SCFAs), bile acids, and lipopolysaccharide (LPS)-modulate endothelial function, immune cell programming, platelet activity, and plaque stability through receptor-mediated signaling and epigenetic regulation. SCFAs demonstrate potentially protective effects via GPCR and HDAC pathways, while TMAO is associated with atherothrombotic risk. However, much mechanistic evidence derives from preclinical studies. Heterogeneity from diet, geography, host characteristics, renal function, and medications substantially influences microbiota-CVD associations. CONCLUSION: The gut-vascular connection is biologically plausible, but definitive clinical causality remains unproven. Microbiome-directed therapies (dietary modulation, pre/pro/synbiotics, targeted metabolite inhibition) are investigational. Prospective, standardized, adequately powered human studies with clinically meaningful outcomes are essential before routine cardiovascular application.

Gastrointestinal Microbiome

Proteomics-based analysis of the defense mechanisms of disease-resistant grass carp against Aeromonas veronii.

Sustainable aquaculture of grass carp (Ctenopharyngodon idella, GC) is consistently threatened by bacterial diseases, particularly those caused by Aeromonas veronii. A disease-resistant grass carp (DR-GC) has been developed by backcrossing female gynogenetic GC with normal male GC, exhibiting improved resistance. However, the systemic molecular mechanisms of DR-GC defending against Aeromonas veronii infection remain largely unexplored. Here, a label-free quantitative proteomics approach was employed to systematically compare proteomic profiles across five tissues (intestine, liver, muscle, skin, and kidney) in DR-GC and GC under healthy and infected conditions. The intestine was identified as the central defense tissue, exhibiting the highest number of differentially abundant proteins (DAPs). In DR-GC, A0A3N0YEK7 (small ribosomal subunit protein eS28), A0A3N0YGT8 (ATP synthase-coupling factor 6) and A0A3N0YNS7 (apolipoprotein A-I) were significantly upregulated in intestine, while D5KZW6 (GCHV-induced protein), A0A3N0Z0A1 and Q8JH84 (hemoglobin subunit alpha) were significantly dysregulated across multiple tissues, which playing the critical roles in defense mechanisms at the protein level. Furthermore, cytochrome P450-associated pathways, cytosolic DNA-sensing and RIG-I-like receptor signaling pathways were identified as crucial coordinators mediating immune and metabolic responses. This study provides the first comprehensive proteomic view of multi-tissue defense mechanisms in DR-GC, and identifies key DAPs and pathways for subsequent functional validation.

Animals

Genetic overlap between estimated glomerular filtration rate and cardiovascular disease identifies potential targets for cardiorenal syndrome.

Heart and kidney diseases frequently coexist, but the genetic basis of this relationship remains unclear. We analyzed genetic data from large-scale studies to investigate how kidney function (estimated glomerular filtration rate, eGFR) and six common cardiovascular diseases share genetic risk factors. Using MiXeR method, and conjunctional false discovery rate (conjFDR) to identify overlapping genetic regions, we found 478 shared genomic loci between eGFR and cardiovascular diseases. These shared genes are involved in tissue development and structure. We also identified 29 genes that could be targeted by existing medications approved by the US Food and Drug Administration, such as PRKAG2, PDE1A, and IGF1R. Among these, genetically predicted higher level of IGF1R expression is associated with a higher eGFR, which reflects good kidney function and is protective against cardiorenal diseases, such as atrial fibrillation, and myocardial infarction. These findings reveal genetic overlap between kidney function and cardiovascular diseases, highlighting potential targets for understanding and treating cardiorenal syndrome.

Humans

Soluble CD163 as a Non-Invasive Biomarker in Autoimmune Nephrological and Rheumatological Diseases.

Autoimmune nephrological and rheumatological diseases involve macrophage-driven inflammation, yet disease activity is often assessed using invasive or non-specific measures. Soluble CD163 (sCD163), released from activated monocytes and macrophages, is emerging as a biomarker of macrophage-mediated inflammation in these conditions. This narrative review summarizes current evidence on the diagnostic, prognostic, and disease-monitoring potential of sCD163 measured in blood, urine, and synovial fluid in autoimmune nephrological and rheumatological diseases. This review is based on a narrative analysis of selected publications investigating the clinical utility of sCD163 in autoimmune kidney and rheumatic diseases, with emphasis on correlations with disease activity, histopathological findings, and clinical outcomes. Urinary sCD163 shows excellent diagnostic accuracy for active lupus nephritis (area under the receiver operating characteristic [AUROC] 0.89-0.998), correlates with histological activity index (but not chronicity), and distinguishes ongoing inflammation from chronic damage during treatment. In IgA nephropathy, it predicts remission failure and greater benefit from corticosteroids. In ANCA-associated vasculitis, it identifies active renal involvement (AUROC 0.95 in multicenter cohorts). In rheumatoid arthritis (RA), serum sCD163 correlates with early disease activity, predicts radiographic progression, and detects subclinical macrophage activation in remission. In spondylarthritis, synovial fluid sCD163 reflects a disease-specific M2-polarized macrophage phenotype distinct from RA. Utility is compartmentalized: urinary levels indicate intrarenal macrophage activation, synovial fluid local joint inflammation, and serum systemic activation. sCD163 is a promising macrophage-specific biomarker across autoimmune diseases, but its compartmentalized nature requires context-specific measurement. Before clinical implementation, assay standardization, multicenter validation, and interventional trials showing the benefit of sCD163-guided management are needed.

Humans

Dual-tasking reveals severity-dependent reorganization of cortical beta energy landscapes in Parkinson's disease.

Dual-task impairment is a hallmark of Parkinson's disease (PD), yet the large-scale neural mechanisms underlying postural-motor interference remain poorly understood. In particular, it is unclear how cortical network dynamics reorganize across disease severity when postural control competes with concurrent task demands. This study investigated EEG-derived beta-band cortical energy landscapes in healthy older adults, early-stage PD, and mid-stage PD during single- and dual-task conditions. Dual-task behavioral cost increased with disease severity for concurrent manual performance (p&#xa0;<&#xa0;0.001), whereas a quadratic pattern was observed for postural performance. Energy landscape analysis revealed severity-dependent reconfiguration of cortical beta dynamics. Dual-task-related landscape changes in effective network flexibility (&#x394;Neff), landscape geometry (&#x394;Evar and &#x394;Gmag), and dominant low-energy attractor organization (&#x394;Low mass and &#x394;Low area) showed significant monotonic trends (p&#xa0;<&#xa0;0.05), reflecting progressive constrained cortical network dynamics with advancing PD severity. In addition, dual-task-related landscape alterations were associated with clinical severity, as indexed by Hoehn and Yahr stage (|r|&#xa0;=&#xa0;0.353-0.423, p&#xa0;=&#xa0;0.016-0.048), and showed associations with motor impairment, as measured by MDS-UPDRS part III scores (|r|&#xa0;=&#xa0;0.333-0.455, p&#xa0;=&#xa0;0.009-0.063). These findings demonstrate that dual-task demands induce severity-dependent reconfiguration of cortical beta energy landscapes in PD. Energy landscape geometry may capture systems-level neural constraints associated with dual-task susceptibility in PD, providing a physiologically grounded framework to characterize disease-related functional vulnerability.

Humans

Is There a Difference in Occurrence of Complications Between Adults With Hemoglobin SS and Hemoglobin SC Disease: An Extended Systematic Review.

Sickle cell disease (SCD) is characterized by both acute and chronic complications. The clinical manifestation of these complications differs between genotypes. Given the large amount of research already published, this systematic review aims to offer a complete overview of types of sickle cell complications between adults in the most common genotypes Hemoglobin SS (HbSS) and Hemoglobin SC (HbSC), putting options for further research into perspective. An extensive literature search was performed to study all available evidence on these complications. This review was performed according to the "Preferred Reporting Items for Systematic Reviews and Meta-Analyses" (PRISMA) statement guidelines, and was performed on January 2, 2024. A total of 710 references were identified. After careful screening, 521 records were excluded based on title and abstract and other exclusion criteria. In total, 158 articles were excluded after full-text assessment. Our analysis of 31 studies highlights key differences in complications between HbSS and HbSC genotypes in sickle cell disease (SCD). Vaso-occlusive crises (VOCs) remain the most common acute complication in both genotypes. HbSS patients experience more frequent VOCs, while HbSC patients generally have a milder clinical course when it comes to acute complications. Chronic complications, particularly in the ocular and pulmonary systems, are more prevalent in HbSC patients. However, as acute complications are more common in HbSS and chronic complications more common in HbSC, both genotypes face progressive organ damage due to recurrent ischemic injury and inflammation.

Humans

Multi-omic biomarkers in cardiovascular disease: Discovery to clinical translation.

Cardiovascular disease (CVD) remains the leading cause of mortality worldwide, necessitating improved risk stratification and early detection strategies. Multiomics approaches that integrate genomics, transcriptomics, proteomics, metabolomics, and epigenomics offer unprecedented opportunities for biomarker discovery and precision medicine in cardiovascular care. This narrative review examines the current landscape of multiomics biomarkers for CVD, tracing their evolution from discovery to clinical translation. We synthesize evidence from recent studies evaluating the clinical utility of integrated omics approaches across diverse cardiovascular conditions, including atherosclerotic cardiovascular disease, heart failure, and atrial fibrillation. High-throughput proteomics has identified novel protein signatures that enhance cardiovascular risk prediction beyond traditional risk factors. Metabolomics has revealed pathway-specific biomarkers, including trimethylamine N-oxide and lipid species, associated with atherogenesis. Polygenic risk scores derived from genomic data demonstrate incremental value when combined with clinical risk scores. Multiomics biomarkers represent a transformative approach to cardiovascular risk assessment and disease management.

Humans

How the microbiome shapes epigenetic trained memory in neuroinflammation: Implications for neurodegenerative diseases.

Neurodegenerative diseases are increasingly recognized as disorders involving immune dysregulation. However, the mechanisms underlying this dysfunction remain poorly characterized. Trained immunity has recently emerged as a potential contributor to immune dysregulation, particularly in neuroinflammation and neurodegenerative diseases, where trained immunity is the epigenetic reprogramming of innate immune responses following an initial inflammatory stimulus, which increases responses to subsequent exposures. In parallel, although the brain has traditionally been viewed as an immune-privileged organ, growing evidence indicates that peripheral immune activity exerts significant influence on neuroinflammation in the brain. A major driver of peripheral immunity is the microbiome. Therefore, this perspective aims to present a conceptual framework for a relationship between the microbiome, trained immunity, and neurodegenerative diseases. We first summarize evidence of trained immunity in the brain and its role in neurodegeneration. Next, we highlight the role of the microbiome in peripheral immune modulation and in trained immunity. Finally, we propose potential mechanisms through which the microbiome may induce or modulate trained immunity in the brain. These include: 1) immunogenic microbial metabolites that cross the blood-brain barrier and alter host cell epigenetics; 2) migration of peripherally trained myeloid cells into the brain; 3) viral infection-induced trained immunity that may predispose to neurodegeneration. Together, this perspective suggests that microbiome-induced trained immunity offers a novel mechanism linking peripheral immune regulation with neuroinflammation and neurodegeneration with implications for therapeutic targeting of epigenetic modification as a molecular prevention strategy for progression of neurodegeneration.

Humans

Epigenetic drift and LINE-1 activation in aging brain: Implications for neurodegenerative disease.

Brain aging and age-associated neurological diseases, such as Alzheimer's Disease (AD), Parkinson's Disease (PD), and Amyotrophic Lateral Sclerosis (ALS), are largely attributed to epigenetic drift which is characterized by the gradual accumulation of alterations in neural cell methylation patterns over time. These methylation changes are particularly evident in transposable element (TE)-derived sequences such as Long interspersed element-1 (LINE-1) which comprises approximately 17% of the human genome. During aging, LINE-1 elements gradually lose their methylation, as well as the regulatory safeguard mechanisms that usually keep them inactive. This repression loss can lead to LINE-1 reactivation, contributing to harmful effects including genomic instability, neuroinflammation, and more. Together these findings indicate that impaired epigenetic maintenance, especially in repetitive genome regions, plays a key role in biological aging of neurons and glial cells. In this narrative review, we discuss the methylation dynamics and regulatory mechanisms of LINE-1 retrotransposons, their activation processes during aging, and contribution to age-associated neurological diseases. We also highlight the potential of targeting LINE-1 methylation to restore methylation homeostasis, epigenetic stability and delay brain aging.

Humans