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PubMed2025

S-GMAS: Genome-Wide Mediation Analysis With Brain Subcortical Shape Mediators.

Mediation analysis is widely utilized in neuroscience to investigate the role of brain image phenotypes in the neurological pathways from genetic exposures to clinical outcomes. However, it is still difficult to conduct mediation analyses with whole genome-wide exposures and brain subcortical shape mediators due to several challenges including (i) large-scale genetic exposures, that is, millions of single-nucleotide polymorphisms (SNPs); (ii) nonlinear Hilbert space for shape mediators; and (iii) statistical inference on the direct and indirect effects. To tackle these challenges, this paper proposes a genome-wide mediation analysis framework with brain subcortical shape mediators. First, to address the issue caused by the high dimensionality in genetic exposures, a fast genome-wide association analysis is conducted to discover potential genetic variants with significant genetic effects on the clinical outcome. Second, the square-root velocity function representations are extracted from the brain subcortical shapes, which fall in an unconstrained linear Hilbert subspace. Third, to identify the underlying causal pathways from the detected SNPs to the clinical outcome implicitly through the shape mediators, we utilize a shape mediation analysis framework consisting of a shape-on-scalar model and a scalar-on-shape model. Furthermore, the bootstrap resampling approach is adopted to investigate both global and spatial significant mediation effects. Finally, our framework is applied to the corpus callosum shape data from the Alzheimer's Disease Neuroimaging Initiative.

Humans↗

PubMed2024

Mannose receptor (MRC1) mediates uptake of dextran in macrophages via receptor-mediated endocytosis.

UNLABELLED: Macrophages maintain surveillance of their environment using receptor-mediated endocytosis and pinocytosis. Receptor-mediated endocytosis allows macrophages to recognize and internalize specific ligands whereas macropinocytosis non-selectively internalizes extracellular fluids and solutes. Here, CRISPR/Cas9 whole-genome screens were used to identify genes regulating constitutive and growth factor-stimulated dextran uptake in murine bone-marrow derived macrophages (BMDM). The endocytic mannose receptor c-type 1 ( Mrc1 , also known as CD206) was a top hit in the screen. Targeted gene disruptions of Mrc1 reduced dextran uptake but had little effect on uptake of Lucifer yellow, a fluid-phase marker. Other screen hits also differentially affected the uptake of dextran and Lucifer yellow, indicating the solutes are internalized by different mechanisms. We further deduced that BMDMs take up dextran via MRC1-mediated endocytosis by showing that competition with mannan, a ligand of MRC1, as well as treatment with Dyngo-4a, a dynamin inhibitor, reduced dextran uptake. Finally, we observed that IL4-treated BMDM internalize more dextran than untreated BMDM by upregulating MRC1 expression. These results demonstrate that dextran is not an effective marker for the bulk uptake of fluids and solutes by macropinocytosis since it is internalized by both macropinocytosis and receptor-mediated endocytosis in cells expressing MRC1. This report identifies numerous genes that regulate dextran internalization in primary murine macrophages and predicts cellular pathways and processes regulating MRC1. This work lays the groundwork for identifying specific genes and regulatory networks that regulate MRC1 expression and MRC1-mediated endocytosis in macrophages. SIGNIFICANCE STATEMENT: Macrophages constantly survey and clear tissues by specifically and non-specifically internalizing debris and solutes. However, the molecular mechanisms and modes of regulation of these endocytic and macropinocytic processes are not well understood. Here, CRISPR/Cas9 whole genome screens were used to identify genes regulating uptake of dextran, a sugar polymer that is frequently used as a marker macropinocytosis, and compared with Lucifer yellow, a fluorescent dye with no known receptors. The authors identified the mannose receptor as well as other proteins regulating expression of the mannose receptor as top hits in the screen. Targeted disruption of Mrc1 , the gene that encodes mannose receptor, greatly diminished dextran uptake but had no effect on cellular uptake of Lucifer yellow. Furthermore, exposure to the cytokine IL4 upregulated mannose receptor expression on the cell surface and increased uptake of dextran with little effect on Lucifer yellow uptake. Studies seeking to understand regulation of macropinocytosis in macrophages will be confounded by the use of dextran as a fluid-phase marker. MRC1 is a marker of alternatively activated/anti-inflammatory macrophages and is a potential target for delivery of therapeutics to macrophages. This work provides the basis for mechanistic underpinning of how MRC1 contributes to the receptor-mediated uptake of carbohydrates and glycoproteins from the tissue milieu and distinguishes genes regulating receptor-mediated endocytosis from those regulating the bona fide fluid-phase uptake of fluids and solutes by macropinocytosis.

Journal Article↗

PubMed2026

Gut Microbiota, Lipidome, and Metabolites Mediate Immune Dysregulation in Diabetic Microvascular Disease: A Two-sample Mendelian Randomization and Mediation Analysis.

INTRODUCTION: Diabetic microvascular disease (DMiVD) involves dysregulated immune cell function, but the precise pathogenic mechanisms remain unclear. MATERIALS AND METHODS: We conducted a two-sample Mendelian randomization (MR) study using comprehensive GWAS and FinnGen summary statistics, encompassing 731 immune cell phenotypes, 473 gut microbial taxa, 91 inflammatory proteins, 179 lipid types, 1,400 plasma metabolites, 20 micronutrients, and DMiVD cases. The analysis aimed to evaluate causal associations between these variables and DMiVD. We further explored potential mediating roles of gut microbiota, plasma lipidome, and metabolites using mediation analysis, with multiple sensitivity tests confirming the robustness of our findings. RESULTS: We identified 20 immune cell phenotypes, 33 gut microbial taxa, 31 lipid types, and 83 plasma metabolites with significant causal associations with DMiVD. Mediation analysis revealed that the risk effect of CD3+ resting Tregs on diabetic nephropathy was partly mediated by phosphatidylcholine (16:0_18:2) (10.7%). Additionally, the protective effect of CX3CR1 on monocytes against DMiVD was partly mediated by Unclassified Bacilli A (35%), Species CAG-177 sp003538135 (22.6%), and triacylglycerol (52:6) (25.5%). DISCUSSION: These findings advance understanding of DMiVD pathogenesis, highlighting that modulation of key metabolic pathways and immune regulatory nodes may represent promising therapeutic strategies. Further experimental studies are needed to validate these potential causal relationships. CONCLUSION: Using causal inference approaches, this study identifies immune cell-mediated mechanisms underlying DMiVD, involving gut microbiota, plasma lipids, and metabolites. The results suggest potential intervention targets for mechanistic studies and therapeutic development.

Mendelian Randomization Analysis↗

PubMed2026

Oncolytic HSV-1-Mediated JAG1 Blockade Induces Glioma Senescence-Associated Secretory Phenotype to Increase Macrophage Activation and Cetuximab-Mediated Senolysis.

UNLABELLED: Oncolytic HSV-1 (oHSV) treatment induces Notch signaling and myelosuppression in the tumor microenvironment (TME) of preclinical cancer models. Clinically, the Notch ligand JAG1 was upregulated in patients with recurrent high-grade glioma treated with the oHSV CAN-3110 and correlated with poor prognosis. To better understand endogenous JAG1-mediated signaling in glioma cells and tumor-associated macrophages (TAM), we engineered a JAG1-antagonizing oHSV (OD-0J1) and interrogated its impact on cancer and myeloid cells in the TME. OD-0J1 antagonized JAG1-mediated Notch signaling and suppressed tumor growth in athymic nude and humanized mice, an effect reliant on Notch signaling in tumor cells. Kinome profiling revealed that OD-0J1 treatment suppressed CDK1, resulting in activation of the G2-M cell cycle checkpoint. Cell cycle arrest led to senescence and correlated with increased reactive oxygen species, p62, and autophagosome accumulation and senescence-associated β-galactosidase activity. OD-0J1-induced senescence resulted in increased production of inflammatory chemokines and damage-associated molecular patterns (DAMP), such as IL1β, HMGB1, and extracellular ATP. Coculturing macrophages with OD-0J1-infected tumor cells led to stimulation of chemotactic and proinflammatory pathways, as well as increased Fc receptor activation. Single-cell RNA sequencing and flow cytometric analysis of F4/80+ cells isolated from tumors showed a shift from tumor-supporting TAMs to inflammatory macrophages upon OD-0J1 treatment. Heightened EGFR activation in senescent cells was a mechanism to escape cell death, which created a unique opportunity for cetuximab as a senolytic agent. Combination therapy reduced EGFR signaling and induced macrophage-mediated antibody-dependent cellular cytotoxicity, thereby increasing the antitumor therapeutic efficacy of OD-0J1. SIGNIFICANCE: Leveraging JAG1 antagonism in the context of oncolytic virotherapy rewires macrophage polarization within the tumor microenvironment, which has wide implications for sensitizing tumors to antibodies, senolytic agents, and BiTE therapies.

Humans↗

PubMed2025

EP300-mediated lactylation leads to ulcerative colitis via CD86-positive plasmacytoid dendritic cells: A Mendelian randomization and mediation analysis.

This study explores the potential mechanism between lactylation and ulcerative colitis (UC) using two-sample Mendelian randomization and multi-omics analysis. This study employed expression quantitative trait loci and protein quantitative trait loci as exposures, with UC from the Finnish database as the outcome, to conduct Mendelian randomization analysis on lactylation-related target genes, aiming to investigate the causal relationships between these exposures and the outcome. Sensitivity and pleiotropy tests, combined with colocalization analysis, are performed to identify the best target genes and ensure the robustness of the results. Finally, immune cells are included for mediation analysis between lactylation and UC to explore potential mechanisms of action. Through Mendelian randomization analysis combined with sensitivity and pleiotropy tests, 2 lactylation target genes were found to have a significant causal relationship with UC. Subsequent colocalization analysis confirmed EP300 as a potential gene target. After including immune cells in the mediation analysis, it was discovered that there is a potential mechanism involving EP300, CD86+ plasmacytoid dendritic cells (pDCs), and UC. There is a significant causal relationship between lactylation and UC. Furthermore, the lactylation-modified gene EP300 may lead to UC occurrence by regulating CD86+ pDCs.

Humans↗

PubMed2026

Phytoplasma-plant interactions: effector-mediated host reprogramming, hormonal crosstalk, metabolic alterations and plant-mediated vector manipulation.

Phytoplasmas are wall-less, phloem-restricted bacterial pathogens that infect over 1,000 plant species, causing substantial losses in agriculture, horticulture, and forestry worldwide. Despite their reduced genomes and limited metabolic autonomy, these obligate parasites colonize diverse hosts through secreted effector proteins that extensively reprogram plant development, metabolism, immune signalling, and vector interactions. Advances in genomics, transcriptomics, proteomics, metabolomics, and functional studies have substantially clarified the molecular basis of phytoplasma pathogenicity and symptom development. This review synthesizes current understanding of phytoplasma-plant interactions, covering phytoplasma biology, genome evolution, and the infection cycle across plant and insect vector hosts. We examine the molecular functions of key effectors, SAP11, SAP54/PHYL1, SAP05, TENGU, SWP1, and recently identified virulence factors, focusing on how they target host transcription factors, phytohormone networks, protein degradation pathways, and immune responses to promote colonization and disease progression. We further discuss how phytoplasma infection disrupts phytohormone signalling, primary and secondary metabolism, and developmental programs to produce characteristic disease symptoms, with particular attention to pathogen-induced changes in host volatiles and nutritional quality that alter vector behaviour and enhance transmission. Finally, we summarize insights from multi-omics studies and emerging management strategies, including CRISPR-based genome editing, RNAi, rapid molecular diagnostics, resistant cultivars, microbiome-based approaches, and sustainable vector control, and highlight key knowledge gaps and priorities for developing effective, environmentally sustainable phytoplasma disease management.

Phytoplasma↗

PubMed2024

Causal Mediation Analysis for Integrating Exposure, Genomic, and Phenotype Data.

Causal mediation analysis provides an attractive framework for integrating diverse types of exposure, genomic, and phenotype data. Recently, this field has seen a surge of interest, largely driven by the increasing need for causal mediation analyses in health and social sciences. This article aims to provide a review of recent developments in mediation analysis, encompassing mediation analysis of a single mediator and a large number of mediators, as well as mediation analysis with multiple exposures and mediators. Our review focuses on the recent advancements in statistical inference for causal mediation analysis, especially in the context of high-dimensional mediation analysis. We delve into the complexities of testing mediation effects, especially addressing the challenge of testing a large number of composite null hypotheses. Through extensive simulation studies, we compare the existing methods across a range of scenarios. We also include an analysis of data from the Normative Aging Study, which examines DNA methylation CpG sites as potential mediators of the effect of smoking status on lung function. We discuss the pros and cons of these methods and future research directions.

causal inference↗

PubMed2026

Genetically predicted associations between blood cell perturbation responses and bronchiectasis through immune mediation: A Mendelian Randomization study.

BACKGROUND: Bronchiectasis is a chronic airway disease characterized by persistent inflammation and structural damage, with substantial clinical and etiologic heterogeneity. Although previous studies have identified associations between blood cells and bronchiectasis, the causal relationships remain unclear. Moreover, the mechanisms underlying blood cell perturbation responses and their potential mediation by immune cells in disease progression are largely unexplored. METHODS: Two-sample Mendelian randomization (MR) analysis was used to explore genetically predicted associations among immune cell traits, blood cell perturbation response phenotypes, and bronchiectasis, based on genome-wide association study summary data. Mediation MR analysis was further applied to assess whether immune cells mediate these associations. Multiple sensitivity analyses, including tests for heterogeneity and horizontal pleiotropy, were performed to evaluate the validity and robustness. RESULTS: Five blood cell perturbation response phenotypes and twenty-nine immune cell traits showed significant genetically predicted associations with bronchiectasis. Mediation analysis showed that natural killer (NK) cell absolute count partially mediated the causal effect between the eosinophil perturbation response and bronchiectasis, with a mediation proportion of 9.626%. CD38 on transitional B cells mediated the causal effect between the monocyte perturbation response and bronchiectasis, with a mediation proportion of 10.580%. Additionally, CD45 on NK cells played a mediating role in the association between the white blood cell perturbation response and bronchiectasis, with a mediation proportion of 10.651%. CONCLUSION: This study systematically explores genetically predicted associations between blood cell perturbation responses and bronchiectasis and highlights potential immune-mediated pathways. These exploratory findings provide novel genetic insights into the pathogenesis of bronchiectasis and identify potential therapeutic targets for future strategies.

Humans↗

PubMed2026

Effectiveness of Caregiver-Mediated Spoken Language Interventions for Children Under Five at Risk of Developmental Language Disorder: A Systematic Review and Meta-Analysis.

BACKGROUND AND AIMS: Caregiver-mediated interventions are commonly used by Speech and Language Therapists to support early language development. Developmental Language Disorder (DLD) is associated with reduced quality of life throughout the lifespan. Understanding factors that predict intervention success is essential for developing appropriate, cost-effective therapy provision for the approximately 12% of preschool children who present with early markers for Developmental Language Disorder (DLD). This systematic review and meta-analysis examined the effectiveness of caregiver-mediated spoken language interventions for under-fives at risk of DLD, and factors influencing intervention effectiveness. METHODS: A systematic review following PRISMA guidelines was conducted. Five electronic databases were searched to identify experimental studies comparing caregiver-mediated spoken language interventions to control conditions in under-fives presenting with risk factors for DLD. Risk factors included prematurity, socioeconomic factors, caregiver language development concerns, and formal or informal language screening or assessment scores. Twenty-six experimental studies with 1407 child participants were included in qualitative synthesis. Meta-analysis was performed on nine Randomised Controlled Trials involving 947 children. RESULTS: Effectiveness was examined for outcomes including child language gains, child wellbeing, inclusion and attainment. Meta-analysis indicated a significant effect of caregiver-mediated spoken language interventions on language outcomes compared to treatment-as-usual, non-language intervention or waitlist control conditions. Non-language outcomes were evaluated via qualitative synthesis. Interventions significantly improved language development trajectories for under-fives presenting with risk factors or early markers for DLD. CONCLUSION AND IMPLICATIONS: This review contributes to the growing evidence base demonstrating that caregiver-mediated interventions can positively impact language development and wellbeing outcomes for children under five at risk of DLD. These findings support the implementation of caregiver-mediated environmental language interventions in clinical practice to maximise accessibility and cost-effectiveness while delivering optimal outcomes for vulnerable populations. WHAT THIS PAPER ADDS: What is already known on this subject Previous research on caregiver-mediated spoken language interventions has highlighted gaps in the evidence regarding the impact of risk factors, demographic characteristics, dosage and intervention components on child language outcomes. Developmental Language Disorder has relatively high population prevalence, estimated at 7%. Prevalence is associated with risk factors including low household socioeconomic status (SES), prematurity and late language emergence. In contrast to its prevalence, there is low public and professional awareness of DLD and a low diagnostic rate. Therefore, a strengthened evidence base and additional insights into the factors affecting success of family-based interventions is important in order to increase the effectiveness of service provision and care planning for this underserved population. Timely and effective intervention with young children presenting with early markers for DLD has the potential to offer lifelong improvement to their wellbeing, inclusion and attainment outcomes. Recent systematic reviews of the effectiveness of caregiver-mediated language interventions had differences in population age range and diagnostic inclusion criteria. What this paper adds to existing knowledge Our review examines the effectiveness of caregiver-mediated early spoken language interventions on child language, attainment and wellbeing, and on caregiver self-efficacy and adherence to language support strategies. Our population was children under five presenting with risk factors for Developmental Language Disorder, in the absence of other neurodevelopmental or genetic conditions such as intellectual disability or autism. This review adds depth and detail to the evidence base supporting the effectiveness of caregiver-mediated spoken language interventions in improving outcomes for this population of young children, and factors that influence their success. What are the potential or actual clinical implications of this work? The high prevalence of Developmental Language Disorder, estimated at around 7% of the population, and the strong association with risk factors including low SES, prematurity and late language emergence, coupled with the low awareness of DLD and low diagnostic rate, mean that a strengthened evidence base and additional insights into the factors affecting success of family-based interventions can increase the effectiveness of service provision and care planning for this population. Timely and effective intervention in this group of young children has the potential to improve wellbeing and attainment outcomes across the lifespan. This review contributes to our understanding of how to implement cost-effective, socially valid and maximally engaging partnership working with families of young children at risk for DLD.

Humans↗

PubMed2025

Brain Health Loss Mediates the Effect of Infarct Volume on Functional Outcome in Ischemic Stroke.

IMPORTANCE: Brain health may facilitate resilience to detrimental consequences from neurological diseases. Infarct volume is associated with poor functional outcome after acute ischemic stroke (AIS), but potential mediating effects through stroke-related brain health loss have not been investigated. OBJECTIVE: To determine whether stroke-related brain health loss, quantified by change in MRI derived effective Reserve (eR), mediates the effect of acute infarct volume on functional outcome after AIS. DESIGN: Observational multicenter cohort study. SETTING: We analyzed data from the GASROS (n=488) and MRI-GENIE (n=560) cohorts, collected 2003-2011. PARTICIPANTS: Adult patients consecutively diagnosed with AIS, with available admission MRI. EXPOSURE: At admission, white matter hyperintensity (WMH) and normal-appearing brain volumes were assessed on T2-FLAIR, and acute infarct volume on diffusion weighted imaging. WMH was normalized by brain volume, creating WMH load. We quantified brain health using eR, a latent variable incorporating age, WMH load, and normal-appearing brain volume. ΔeR reflected the change in eR when acute infarct volume was included, representing stroke-related brain health decline. Mediation analysis was used to determine if ΔeR mediates the effect of infarct volume on functional outcome (modified Rankin Scale [mRS] at 90 days). MAIN OUTCOME MEASURE: Proportion of mediating effect. RESULTS: We included 1,048 patients (median age 67y, 38% females). At baseline, median NIHSS score was 3 (IQR 1-7), median infarct volume 3.1mL (IQR 0.9-15.5). At 90 days, median mRS score was 1 (IQR 1-3) and 51 (5%) patients had died. In mediation analysis, ΔeR significantly mediated 36% (95% CI 16-56%) of the total effect of infarct volume on functional outcome (direct effect (ß=0.15 [95% CI 0.09-0.22], p<0.001; indirect effect mediated through ΔeR: ß=0.09 [95% CI 0.04 to 0.14], p=0.001). In subgroup-analyses, the mediative effect was apparent among female but not male, and among patients aged >67y but not ≤67y. CONCLUSIONS AND RELEVANCE: Stroke-related structural brain health loss mediates about one third of the effect of acute infarct volume on functional outcome after ischemic stroke, with important sex and age differences. Brain health significantly influences outcome and recovery potential, and may be considered a key biomarker when modeling outcome after AIS.

acute ischemic stroke↗

PubMed2026

Proteomic Mediators of Chronic Obstructive Pulmonary Disease Phenotypes and Coronary Artery Calcification Burden in Ever Smokers.

BACKGROUND: Chronic obstructive pulmonary disease (COPD) increases cardiovascular disease risk. Coronary artery calcification (CAC) predicts cardiovascular events and mortality in COPD. We hypothesized that plasma proteins linked to pulmonary phenotypes mediate CAC burden. METHODS: Pulmonary function, emphysema, airway wall thickening, Agatston CAC scores (inverse normal transformed), and relative abundance of 1305 plasma proteins (log-transformed) were assessed in 989 Phase 1 COPDGene (Genetic Epidemiology of COPD) participants. Proteins associated with both pulmonary phenotypes (FEV1[forced expiratory volume in 1 second]%predicted, FVC [forced vital capacity], FEV1/FVC, emphysema, airway wall thickness, wall area percentage) and CAC (false discovery rate P≤0.20) were evaluated using multivariable mediation. Model adjustments included sex, age, race, body mass index, smoking, comorbidities, and medications. Adjustment for pulmonary artery-to-aortic diameter ratio-a marker of pulmonary vascular pressure-was also explored. The95% bootstrap CIs that excluded zero were considered significant. RESULTS: FEV1%predicted (P=0.026) and FEV1/FVC (P=0.010) were associated with CAC. After adjusting for FEV1, visual emphysema, and visual airway wall thickening remained associated with CAC. Five proteins (TSP2 [thrombospondin-2], renin, MMP-7 [matrix metalloproteinase-7], ERBB1 [epidermal growth factor receptor], MIC-1 [macrophage inhibitory cytokine-1]) mediated the FEV1%predicted and CAC association. All except MIC-1 mediated FEV1/FVC and CAC. All except renin mediated quantitative airway wall thickness or wall area percentage and CAC. Additionally, α2-antiplasmin (alpha-2 antiplasmin) mediated airway wall thickness and CAC. ERBB1 mediated visual paraseptal emphysema and CAC. Pulmonary artery-to-aortic diameter ratio adjustment reduced or eliminated some mediation effects. ERBB1 remained an independent mediator across multiple phenotypes. CONCLUSIONS: Six plasma proteins mediated associations between COPD phenotypes and CAC burden. These effects were partially influenced by pulmonary artery-to-aortic diameter ratio A, suggesting shared molecular pathways linking lung dysfunction to cardiovascular risk in COPD.

Humans↗

PubMed2024

Role of myeloid cells in mediating the effects of lipids on ulcerative colitis.

OBJECTIVE: To evaluate the causal relationship between lipids and ulcerative colitis (UC) through Mendelian Randomization (MR), and to further investigate the involvement of immune cells in mediating this process. METHODS: Utilizing summary statistics from genome-wide association studies (GWAS) of individuals with European ancestry, we analyzed the causal link between 179 lipid types and UC (2,569 UC cases and 453,779 controls) through Two-sample Mendelian randomization (2SMR) and Bayesian-weighted MR (BWMR). Based on this, a mediation screening of 731 immune cell phenotypes was conducted to identify exposure and mediator factors. Lastly, the role and proportion of immune cells in mediating the causal effects of lipids on UC were assessed via reverse MR (RMR) and two-step MR. RESULTS: The results of MR showed that there was a causal relationship between the six genetically predicted lipid types and UC (P <0.05), and the four immune cell phenotypes were identified as mediators of the association between lipids and UC. Notably, Phosphatidylcholine (PC) (16:0_0:0) served as the exposure factor, and myeloid cells CD11b on CD33+ HLA DR+ CD14dim acted as the mediator. Mediation analysis showed that CD11b on CD33+ HLA DR+ CD14dim had a mediation effect of -0.0205 between PC (16:0_0:0) and UC, with the mediation effect ratio at 15.38%. CONCLUSION: Our findings elucidate the causal effect of lipids on UC and identify the significant mediating role of myeloid cells CD11b on CD33+ HLA DR+ CD14dim in regulating UC through PC (16:0_0:0), offering new pathways and strategies for UC clinical treatment.

Humans↗

PubMed2026

Differential DNA methylation in blood as potential mediator of the association between ambient PM2.5 and cerebrospinal fluid biomarkers of Alzheimer's disease among a cognitively normal population-based cohort.

Fine particulate matter (PM2.5) is a known risk factor for Alzheimer's disease (AD), with emerging evidence showing its effects detectable in the pre-clinical stage through cerebrospinal fluid (CSF) biomarkers of AD. While studies have linked PM2.5 exposure and AD to DNA methylation (DNAm) alterations, the role of DNAm as potential mediator in the association between PM2.5 and AD biomarkers in cognitively normal individuals remains largely unexplored, and formal mediation analyses addressing this question are scarce. Genome-wide DNAm profiles (Illumina EPIC BeadChips) in whole blood and CSF Aβ42 concentrations were assessed in 536 cognitively normal individuals from the Emory Healthy Brain Study (EHBS). Residential PM2.5 exposure for the year preceding participants' blood collection was estimated. A multi-stage analytical pipeline, incorporating single-mediator analysis, high-dimensional mediation analysis, and causal mediation analysis, was applied. Nine CpG sites were identified as noteworthy mediators of the relationship between PM2.5 and decreased CSF Aβ42 concentrations. Causal mediation analysis confirmed significant natural indirect effects (NIE) for eight CpGs, with effect estimates ranging from -0.015--0.029 per 1 ug/m3 increase in PM2.5 exposure. The proportion mediated ranging from 14-43%. Six CpGs are annotated to genes implicated in neuroinflammatory pathways. These findings suggest that differential DNAm, particularly in genes related to neuroinflammation, mediates the association between PM2.5 exposure and CSF Aβ42 concentrations, highlighting the utility of blood DNAm in detecting and studying biological pathways underlying PM2.5 toxicity in the pre-clinical stages of AD.

Humans↗

PubMed2025

Causal relationships between antibody-mediated immune responses and acute pancreatitis: Evidence from a genetic study.

Certain specific antibody-mediated immune responses may be associated with acute pancreatitis (AP), but their causal relationship remains uncertain. Therefore, we used bidirectional two-sample Mendelian randomization (MR) to investigate their causal link and potential mediation by inflammatory cytokines. Data for this study were sourced from a large-scale Genome Wide Association Study (GWAS) communal data pool. To explore the causality between antibody-mediated immune responses and AP, we performed two-sample bidirectional MR analyses using 5 approaches: inverse-variance weighted (IVW), MR-Egger, weighted mode, weighted median, and simple mode. We also studied the potential mediating effect of 91 circulating inflammatory cytokines using a two-step MR method. Additionally, sensitivity analyses were conducted using MR-Egger intercept test and Cochran Q test to ensure the robustness of the outcomes. The results of forward MR analysis showed that anti-Epstein-Barr virus (anti-EBV) IgG seropositivity [OR = 0.941; 95% CI, 0.893-0.992; P = .023] and human herpes virus (HHV) 6 IE1A antibody levels [OR = 0.894; 95% CI, 0.816-0.981; P = .017] significantly reduced the risk of AP. The results of the reverse MR analysis revealed a negative correlation between AP and anti-EBV IgG seropositivity [OR = 0.775; 95% CI, 0.605-0.992; P = .043]. Furthermore, none of the 91 circulating inflammatory cytokines could mediate the causal relationship between HHV-6 IE1A antibody levels and the risk of AP. The results of sensitivity analysis confirmed the robustness of these causalities. The current study suggests that HHV-6 IE1A antibody levels are a protective factor against AP, and there is a bidirectional causality between AP and anti-EBV IgG seropositivity. In addition, the mediation analysis results showed that the 91 circulating inflammatory cytokines could not serve as mediators between the 46 antibody-mediated immune responses and AP.

Humans↗

PubMed2025

Mediators of the Association Between a Parent's Experience of Trauma and Their Children's Well-Being: A Systematic Review.

At present, our understanding of trauma's complexity is underdeveloped, particularly with regard to intergenerational effects. In this paper, we review peer-reviewed literature on parental trauma and child well-being, focusing on mediating factors. We conducted a global systematic review of longitudinal, observational studies assessing mediators between a parent's traumatic exposure and their children's well-being. The primary outcome of the review was quantitative measures of child well-being (physical and psycho-social) assessed when the child was 18 years or under. We considered the following experiences as trauma exposures: intimate partner violence, rape, sexual assault, victimization during violent crime, childhood abuse, and exposure to direct, immediate threats to personal survival during war, political unrest, natural disasters, and sudden, critical injury/illness. Thirty-two studies met our inclusion criteria. The two most common mediator categories were caregiver mental health (n = 13) and parenting behavior (n = 10). Other studies measured aspects of the parent-child relationship (n = 9), maternal stress factors (n = 5), parental physical health (n = 2), and child-level factors (n = 6) as mediators. Almost all included studies (n = 28) detected a mediation effect. The majority of studies (n = 21) cited robust theoretical frameworks to support their mediator and outcome choices. Studies varied in quality, but most used appropriate, formal mediation analyses. Several study designs could be enhanced by methods to improve precision and reduce bias. Currently, there is little consistency in how similar constructs are measured between mediation studies. We did not locate any studies in low-income countries, and few studies examined aspects of family dynamics, physical health, environmental characteristics, or paternal factors.

Humans↗

PubMed2026

Proteomic pathways mediating low socioeconomic status and cardiovascular events in older adults in CHS and ARIC.

BACKGROUND AND AIMS: Many studies have linked socioeconomic status (SES) and cardiovascular outcomes, yet the biologic mechanisms mediating these associations are only partially understood. The objective of this study was to identify molecular mediators of the association of low SES with coronary heart disease (CHD) and stroke. METHODS: This research was conducted in 2942 Black and White adults in the Cardiovascular Health Study (mean age 76.2 years) and 10,689 Black and White adults in the Atherosclerosis Risk in Communities Study (mean age 60.0 years). We used factor analysis to create a composite measure of low educational attainment, low-income, and blue-collar occupation. Approximately 5000 proteins were measured with an aptamer-based method, and CHD and stroke events were adjudicated. Results were stratified by race, which was conceptualized as a social factor. RESULTS: Low SES was associated with 44 and 262 proteins, in Black and White adults, respectively. No protein met the Bonferroni adjusted threshold for statistically significantly mediation among Black participants. Among White participants, 23 proteins mediated the association between SES adversity and CHD and 5 mediated the association between SES adversity and stroke. The strongest mediating associations for CHD included PTPRS, SCG3, and MMP12. The strongest mediating associations for stroke included NCAN, FAM20B, and APLP1. SPARCL1 and CDCP1 remained the strongest mediators of the association between SES adversity and CHD, after adjusting for potential confounders and traditional cardiovascular risk factors. CONCLUSION: We identified several biomarkers that characterize the biologic risk of SES adversity on CHD and stroke.

Aged↗

PubMed2026

The Mediating Role of Immune Cells in the Genetically Predicted Relationship between Gut Microbiota and Puerperal Sepsis: A Mendelian Randomization Study.

INTRODUCTION: The causal relationship between gut microbiota and puerperal sepsis (PS) remains unclear, and there is a lack of in-depth research regarding the potential mediating role of immune cells in this context. OBJECTIVE: This study aims to investigate the causal relationship between gut microbiota and PS using Mendelian randomization (MR) analysis and to assess the mediating effects of immune cells on the risk of PS onset through mediation analysis. MATERIALS AND METHODS: We selected data from large-scale genome-wide association studies (GWAS) involving 473 gut microbiota species, 731 immune cell phenotypes, and PS datasets. Univariate MR (UVMR) analysis was employed to explore the causal relationship between gut microbiota and PS, with the primary statistical method being inverse variance weighting (IVW). Multiple statistical models were applied for sensitivity analysis to minimize the confounding effects of horizontal pleiotropy and heterogeneity. Subsequently, a two-step mediation MR analysis was conducted to evaluate whether immune cells mediate the relationship between gut microbiota and PS. RESULTS AND DISCUSSION: Analysis using various statistical models indicated that 11 gut microbiota species (e.g., Azorhizobium, Bacillus velezensis, CAG-245 sp000435175, Lentimicrobiaceae, and Providencia) exhibited a causal relationship with PS. Further reverse causal analysis between PS and gut microbiota ruled out the possibility of reverse causality. The two-step mediation MR analysis demonstrated that the percentage of IgD-CD27- B cells (10.26%) and CD62L- monocytes (17.29%) partially mediated the effect of CAG-245 sp000435175 on PS risk. CONCLUSION: This study provides evidence of a causal relationship between the abundance of certain gut microbiota species and PS, while also revealing a potential mediating role of immune cells. These findings offer valuable theoretical insights into personalized treatment strategies and the development of novel diagnostic biomarkers for PS.

Humans↗

PubMed2026

RAG-mediated structural variation and its impact on relapse risk in acute lymphoblastic leukemia.

Relapse during treatment of B-cell acute lymphoblastic leukemia (B-ALL) is a harbinger of poor outcomes. Identifying biomarkers for subsequent relapse risk which are detectable at B-ALL diagnosis remains a priority. Off-target recombination-activating gene (RAG)-mediated structural variants (SVs) generate genomic instability that drives leukemogenesis and may underlie treatment resistance. Leveraging sequencing data in 1,496 pediatric B-ALL patients enriched for relapse status (relapse n=532; non-relapse n=964), we characterized RAG-mediated SVs across B-ALL molecular subtypes and examined their association with patient characteristics and their impact on clinical outcomes. Off-target RAG-mediated SVs were overall frequent, particularly in ETV6::RUNX1, ETV6::RUNX1-like, and Ph-like B-ALL subtypes, while increasing age-at-diagnosis was positively associated with burden of off-target RAG-mediated SVs (P<.001). Off-target RAG-mediated SVs with a recombination signal sequence (RSS) at one breakpoint, a hallmark of off-target RAG activity, were significantly more frequent at diagnosis in patients who subsequently relapsed (P=.001). This association remained significant in multivariable regression analysis (per SV odds ratio [OR]:1.08, 95%CI:1.04-1.12), in minimal residual disease (MRD)-negative patients (OR:1.09, 95%CI:1.04-1.14) and across subtypes. Excluding deletions, MRD-negative ETV6::RUNX1 patients with ≥3 off-target RAG-mediated SVs had a >3-fold risk of relapse (hazard ratio:3.47, 95% CI:1.86-6.49). RAG-mediated SVs were also associated with relapse risk in T-cell ALL patients. Off-target RAG-mediated SV burden at diagnosis is a risk factor of relapse in pediatric ALL across molecular subtypes and independent of MRD status.

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