Brain, Behavior, and Immunity

Microglia, the tissue resident immune cells of the central nervous system, are critical regulators of postnatal neural circuit refinement. Innate immune receptors on microglia such as toll-like receptor 4 (TLR4) are best characterized in the context of inflammation, however, endogenous TLR4 ligands are generated during typical developmental processes. Here, we investigated whether TLR4 signaling in CX3CR1-expressing myeloid cells contributes to microglial morphology, synaptic engulfment, and behavioral development in mice under basal conditions. TLR4 conditional knockout altered maternal separation-induced ultrasonic vocalizations without impacting social preference or anxiety-like behaviors. Conditional TLR4 knockout in CX3CR1-expressing myeloid cells markedly increased microglial ramification and cell volume within the paraventricular nucleus (PVN) of the hypothalamus. TLR4 conditional knockout also reduced microglial engulfment of vGlut2-positive presynaptic material, while overall excitatory synapse numbers remained unchanged. Together, these findings demonstrate that TLR4 signaling in CX3CR1-expressing myeloid cells contributes to microglial morphology, presynaptic engulfment, and neonatal communicative behavior under basal conditions.

Gamma-aminobutyric acid (GABA), the principal inhibitory neurotransmitter in the mature human nervous system, plays a central role in neurodevelopment, emotion regulation, and sensory processing. Many psychiatric drugs act on the GABAergic system, highlighting its importance for healthy brain function. Individual differences in brain and circulating GABA levels have traditionally been attributed to genetic variation. However, several gut bacteria produce neuroactive compounds, including GABA, raising the possibility that microbial variation influences peripheral and central GABA levels and related measures in humans. This relationship remains largely unexplored. In a cross-sectional study of 251 healthy adults, we investigated associations between gut microbiota composition, central and peripheral GABA, and associated features. Brain GABA was quantified using magnetic resonance spectroscopy, blood GABA using enzyme-linked immunosorbent assays, and gut microbiota profiles using absolute and relative abundance measures derived from Flow Cytometry Fluorescent In Situ Hybridisation and 16S rRNA gene sequencing. Motor cortex GABA+ levels were positively associated with greater numbers of Bacteroides/Prevotella bacteria. A similar association was observed for blood GABA, which was additionally associated with greater numbers of lactic acid bacteria, Eubacterium rectale/Clostridium coccoides, and Clostridium histolyticum groups, and with predicted microbial gene pathways involved in GABA, propionate, and butyrate biosynthesis. No association was observed between brain and blood GABA concentrations. These findings provide new evidence for relationships between gut bacterial groups and central and peripheral GABA pools, supporting future longitudinal studies of causal links between gut microbiota and host GABA levels, as well as the potential for future intervention studies to influence GABAergic processing.

Background: Early-life adversity (ELA) is one of the strongest predictors of poor mental and physical health later in life, increasing an individual's risk for disorders ranging from depression to metabolic syndrome. However, whether and how ELA shapes immune memory through adulthood, subsequently affecting susceptibility to immune-associated diseases such as autoimmunity, remains elusive. Methods: To address this question, we employed a translationally and ethologically relevant mouse model of resource deprivation, the limited bedding and nesting model, to study the long-term effects of ELA on the immune system. ELA was induced by limited bedding and nesting material in the cage during postnatal days (P)2-9, which provokes fragmented and unpredictable maternal behavior in the dams, and results in chronic stress in the pups. Nucleic acid Linked ImmunoSandwich Assay (NULISA) was used to survey the proteome of adult (~P90) mice of both sexes that experienced ELA vs. control conditions. Results: Using a novel proteomic method, we detected significant upregulation in the levels of IL-17A in the adult blood, primarily in females. Within females, ELA also upregulated IL-13 and CCL3. Three proteins, HGF, PDGFA, and WNT16, were significantly downregulated in ELA mice of both sexes. Conclusions: Being a hallmark proinflammatory cytokine, IL-17A is found to increase in patients with systemic lupus erythematosus (SLE), as well as in animals with lupus-like diseases in virtually all reports. Importantly, autoimmune diseases like SLE have a higher prevalence in women than men, and our data support this sex bias. Together, our data suggest that ELA shapes long-term immune function in a way that may increase risk for autoimmune diseases, with promise for the development of more targeted and personalized therapies for autoimmunity.

Sickness is an organismal response to inflammation, yet its immune, metabolic, neural, and behavioral components are often studied separately and predominantly in male C57BL/6 mice. In this study, we characterized these responses to systemic lipopolysaccharide (LPS) in female BALB/c mice. Mice received intraperitoneal LPS at moderate concentrations and outcomes were assessed during the acute and resolving phases of endotoxemia. LPS caused rapid disappearance of resident peritoneal macrophages, followed by neutrophil accumulation and increased circulating TNF- and IL-6. In the liver, LPS induced inflammatory, acute-phase, and anti-inflammatory transcripts while suppressing genes involved in lipid, cholesterol, and xenobiotic metabolism. Hepatic glutathione was reduced, whereas total superoxide dismutase activity was unchanged. These peripheral responses were followed by transient hypothermia, reduced food intake, and body weight loss. Regional brain mapping showed increased c-Fos labeling in the area postrema, nucleus of the solitary tract, external lateral parabrachial nucleus, paraventricular nucleus of the hypothalamus, and arcuate nucleus. In parallel, LPS selectively promoted IBA1-positive area in the median eminence and arcuate nucleus, whereas several other regions showed no changes, indicating that neuronal and microglial responses are regionally distinct. Behaviorally, LPS reduced locomotion and exploration, increased freezing, and increased forced-swim immobility. Changes in spatial exploration were most pronounced during the acute phase, whereas locomotor suppression and passive stress-coping persisted longer and varied in magnitude with the timing of inflammatory challenge. Together, these findings show that systemic LPS produces a coordinated sickness state in female BALB/c mice that links peripheral inflammation and hepatic metabolic and redox changes with region-specific neuronal and microglial responses, altered thermoregulation and feeding, and behavioral suppression.

T helper cytokines such as IFN{gamma} and IL-17 are dysregulated in a subset of patients with depression and are associated with poor responses to treatment. Both IFN{gamma} and IL-17 have been shown to regulate neural circuits involved in behavioral changes implicated in depression. However, the cellular source and the regulatory mechanisms governing these cytokines in this context remain incompletely understood. We analyzed brain lymphocytes in response to unpredictable chronic mild stress (UCMS), a model of depression with strong face and construct validity. We confirmed that UCMS induced depressive-like behavior in both male and female mice. Interestingly, UCMS preferentially reduced regional synaptic density in female and neuron counts in male hippocampi. Using single cell RNAseq, we identified T helper cytokine signatures to be enriched in distinct lymphocyte lineages expressing tissue resident markers and are regulated by both sex and chronic stress. Female brain-resident {gamma}{delta}T cells are significantly enriched for type 2 and type 17 signatures and have higher expression of inflammasome genes such as Nlrp3 and Il1b whereas male {beta}T cells and NKT cells are enriched for type 1 signatures and have elevated Cxcr3 and Il27ra expression. Chronic stress amplified the sex differences and preferentially increased the type 1 response including IFN{gamma} production in males at both the transcriptome and protein level. Type 17 response (e.g. IL-17A and IL-17F production) is also increased in response to UCMS, however with sex-divergent polarization: IL-22 is decreased in female and increased in male brain lymphocytes. Mechanistically, we found that UCMS suppressed P4ha1 in male and Zfp36 in female brain tissue resident lymphocytes. P4HA1 was previously shown to restrict mitochondrial function and limit type 1 responses in CD8 T cells, whereas ZFP36 is a suppressor of inflammatory cytokine translation. Consistent with this finding, ex vivo CD3-dependent stimulation of brain immune cells showed stress-dependent increase in cytokine production with sex-specific effects. Our study provides the cellular and molecular framework for chronic stress-induced tissue resident lymphocyte dysregulation and its sex bias in the brain, with implications for depressive disorders marked by inflammation.

Psilocybin acutely alters neurotrophic, neurochemical, and immune markers, but the relationships between these responses and circulating microRNAs (miRNAs), i.e. non-coding RNAs that regulate post-transcriptional gene expression, remain unclear. In a randomized, double-blind, placebo-controlled study of 62 healthy adults who received psilocybin (0.17 mg/kg) or placebo, we previously demonstrated that let-7g-5p and miR-150-5p were transiently differentially expressed 360 minutes after psilocybin administration. Here, we examined whether changes in these miRNAs were associated with concurrent neurotrophic, inflammatory, pharmacokinetic, and glutamatergic measures. Expression changes from baseline to 360 min and 7 days were analysed using linear regression against changes in BDNF, TNF-, IL-6, C-reactive protein, cortisol, medial prefrontal cortex glutamate/total creatine, and psilocin concentrations. Psilocybin increased let-7g-5p and decreased miR-150-5p expression. Changes in let-7g-5p were positively associated with psilocin concentrations, suggesting sensitivity to inter-individual pharmacokinetic variability, whereas miR-150-5p showed no concentration-dependent association. In both groups, miRNA changes were negatively related to baseline expression: lower baseline let-7g-5p predicted larger increases, whereas higher baseline miR-150-5p predicted larger decreases. BDNF changes were associated with both miRNAs under placebo but not psilocybin, consistent with reduced between-subject variability and a flattened BDNF-miRNA relationship following treatment. Medial prefrontal glutamate was negatively associated with miR-150-5p change under psilocybin. No associations were found with immune biomarkers. Together, these findings support the predicted involvement of let-7g-5p and miR-150-5p in neuroplasticity and their potential as accessible blood-based biomarkers of individual neurobiological responsiveness to psilocybin and other psychedelics.

Abstract Background: Insomnia is highly prevalent in major depressive disorder (MDD), yet the clinical and biological significance of dysfunctional beliefs and attitudes about sleep (DBAS) in MDD remains poorly understood. We examined whether distinct DBAS dimensions are associated with insomnia severity, depressive phenotypes, and neuroimmune-metabolic-oxidative (NIMETOX) biomarkers. Methods: DBAS-30 dimensions, clinical phenotypes, and NIMETOX biomarkers were assessed in 87 hospitalized patients with MDD and 31 healthy controls. Principal component analysis (PCA) was used to ascertain DBAS cognitive dimensions, and associations were examined using multivariable analyses. Results: Compared with controls, MDD patients showed lower scores on "perceived consequences of insomnia," "sleep-related worry and helplessness," and "medication-related beliefs," but higher "causal attributions to aging or biochemical imbalance" scores. A composite DBAS score reflecting these 4 MDD-associated cognitive dimensions was constructed, labeled DBAS dimensional index (DBAS-DI). This score was lower in MDD and inversely associated with Insomnia Severity Index (ISI) scores, overall MDD severity, physiosomatic symptoms, current suicidal ideation, and recurrence of illness. DBAS-DI and the expectations domain jointly explained 35.4% of the variance in ISI scores, with inverse and positive associations, respectively. The DBAS-DI score was inversely associated with indices of the acute-phase inflammatory response, oxidative stress, fecal branched-chain short-chain fatty acids (SCFAs) and positively associated with serum antioxidant capacity and protective SCFAs, such as acetate, propionate, and butyrate. Conclusions: DBAS abnormalities in MDD extend beyond insomnia-related cognitions and are associated with illness severity, suicidality, recurrence, and NIMETOX alterations. These findings suggest that dysfunctional sleep-related cognitions are embedded within broader immune-oxidative and gut microbial-metabolic processes that may contribute to the insomnia-depression interface.

Brain development, especially developmental myelination, continues through young adulthood. Concordantly, children may be particularly vulnerable to neural-immune challenges. To investigate the consequences of major childhood immune challenges, juvenile mice were exposed to respiratory influenza (H1N1) infection. White matter-specific microglial reactivity accompanied by oligodendrocyte loss was evident until two months following infection. Mice exhibited hyperlocomotion and impaired attention, but not anxiety-like behavior, at one month following infection. Linking the oligodendroglial and behavioral deficits, genetic disruption of oligodendrocyte development at the same juvenile timepoint recapitulated this behavioral phenotype. Microglial reactivity and oligodendrocyte numbers normalized by young adulthood. However, myelin development was disrupted, with persistently decreased myelinated axon density and reduced myelin sheath thickness. Hyperlocomotion resolved, but anxiety-related behaviors emerged at two months after infection. At 6 months, anxiety resolved but cognitive deficits persisted. Elevated CSF chemokines and microglial chemokine expression prompted testing the role of the multi-chemokine receptor CCR3. CCR3 inhibition rescued these cellular and behavioral aberrations after juvenile H1N1 infection. Together, these findings underscore the potential for disruption of myelin development and lasting cognitive and neuropsychiatric sequelae following major immune challenges during the juvenile period and highlight chemokine signaling as an important therapeutic target.

Interleukin-17A (IL-17A) has been implicated in stress- and pain-related inflammation, yet evidence for acute IL-17A stress response in humans remains scarce. This study examined whether the Maastricht Acute Stress Test (MAST) induces changes in circulating IL-17A and how IL-17A dynamics relate to cortisol and subjective stress/pain. Forty-six healthy adults (mean age: 30.50, SD = 12.86 years; 54% female) completed the standardized MAST. Serum IL-17A and cortisol were assessed repeatedly across baseline and recovery. Stress- and pain-related ratings (VAS) and trait questionnaires (e.g., chronic stress, psychological distress, resilience) were completed. There was a significant increase over time in IL-17A and cortisol following the MAST, with an 36 % increase of IL-17A level measured at 105 min post-stressor and cortisol peaking at 10 min post-stressor. IL-17A indices (baseline and AUCi) showed no meaningful associations with cortisol, subjective stress/pain, or psychological traits, whereas cortisol response (AUCi) correlated positively with perceived acute stress and pain. Overall, the MAST produced clear IL-17A and cortisol responses that appeared dissociable in healthy individuals. Future studies should include broader inflammatory panels and clinical or high-stress samples to clarify conditions under which IL-17A covaries with HPA-axis activity and subjective experience.

The prevalence of neurodevelopmental disorders (NDDs) has increased dramatically, with growing evidence linking prenatal maternal stress exposure to NDDs. Across diverse maternal stressors, immune dysregulation emerges as a common feature, suggesting that fetal microglia may detect changes in the intrauterine environment and influence neurodevelopment. Accordingly, we utilized a mouse model of prenatal maternal cold stress to investigate the impact of maternal stress during pregnancy on fetal microglia morphology, cellular interactions, and phagocytic behaviors. Pregnant mice were exposed to cold stress from embryonic day 11.5 (E11.5) to E15.5 and fetal hypothalamic tissue was assessed from both male and female embryos. By adapting the morphology analysis toolset MicrogliaMorphology to assess fetal microglia, we demonstrate regional differences in microglial morphology in the fetal hypothalamus at baseline, with hypothalamic nuclei such as the paraventricular nucleus (PVN) containing fewer rod-like microglia compared to the broader hypothalamus. Interestingly, prenatal maternal cold stress induced a male-specific shift in microglial morphology from ameboid to ramified within the E15.5 PVN. Male embryos also displayed increased microglial-arginine vasopressin (AVP) neuronal interactions and microglial phagocytosis within the E15.5 PVN, but these changes were unique to microglia with a ramified morphology and were not observed when microglia with an ameboid or rod-like morphology were assessed. Using pHrodo bioparticles and flow cytometry, we further illustrate that prenatal maternal cold stress drives increased phagocytic activity in the E15.5 hypothalamus of male embryos, but not females. Together, these data demonstrate that prenatal maternal cold stress alters microglia morphology and drives morphology-dependent microglial interactions and phagocytic behaviors in male embryos which are unique to the hypothalamic PVN--a nuclei critical for social behaviors. Our findings also suggest that specific hypothalamic nuclei such as the PVN may be more sensitive to prenatal maternal stress, which has the potential to provide a cellular basis underlying the sex differences in microglia-dependent social deficits that were previously reported for this model.

Abstract Background: Glycosylated RNAs (GlycoRNAs) participate in immune recognition and intercellular communication, but their relationship with brain cell-type transcriptional signatures in major depressive disorder (MDD) remains unclear. We examined GlycoRNA-related transcriptional coupling with microglial and other cellular signatures in the dorsolateral prefrontal cortex (DLPFC). Method: Postmortem DLPFC transcriptomic data from 22 controls and 26 MDD patients (GSE102556) were analyzed. GlycoRNA-related pathway enrichment was quantified using gene set variation analysis (GSVA), whereas microglial, neuronal, astrocytic, and oligodendrocytic signatures were derived using single-sample gene set enrichment analysis (ssGSEA). Pearson correlations, linear regression, and generalized estimating equations (GEE) evaluated cell-type-specific associations and diagnostic interactions. Exploratory GEE results underwent false discovery rate (FDR) correction. Results: No differentially expressed genes survived FDR correction, and GlycoRNA-related and cell-type signatures did not differ significantly between groups. In controls, GlycoRNA enrichment was positively associated with the microglial signature (beta = 0.447, FDR-adjusted P = 0.006), with significantly weaker associations for neurons, astrocytes, and oligodendrocytes (all FDR-adjusted P < 0.05). The two-way GlycoRNA x is_microglia interaction was nominally significant (beta = 0.210, P = 0.048), confirming that GlycoRNA transcriptional coupling is substantially stronger for microglia than for the other three cell types combined. The microglial association was numerically attenuated in MDD (beta difference = -0.273, P = 0.167), but diagnostic interactions were nonsignificant. Conclusions: GlycoRNA pathway transcriptional enrichment exhibits preferential microglial association in control DLPFC. Its possible attenuation in MDD remains to be validated. keyword: Major depressive disorder; GlycoRNA; microglia; dorsolateral prefrontal cortex; generalized estimating equation; ssGSEA; bioinformatics

PurposeIt is well established that volatile anesthetics and surgery induce acute and subacute changes in the cellular and molecular landscape of the brain and peripheral circulation and can impair neurological function. However, the chronic neurological sequelae of isoflurane (Iso) anesthesia combined with surgical operation (OP), as well as the underlying mechanisms of postoperative neurological dysfunction, remain poorly understood. MethodsYoung adult male (M) and female (F) C57BL/6 mice underwent 4 h of 2% Iso plus laparotomy or sham treatment. At 12 weeks, olfactory and cognitive function were assessed by odor memory, buried food, Y-maze, and active avoidance tests. Olfactory bulbs (OB) and hippocampi (HI) were collected for RNAseq, while plasma extracellular vesicles (EVs) were isolated, characterized by NanoFCM, and profiled by Olink proteomics. Lastly, EVs were injected into the HI of naive male mice, and cytokine/chemokine responses were measured 24 h later. ResultsBoth sexes showed olfactory impairment after chronic Iso/OP, with greater deficits in females. Iso/OP mice, especially females, exhibited impaired odor recognition in the OM test and longer latencies to locate buried food. Female mice also showed greater hippocampal-dependent spatial working memory deficits in the Y-maze, with more arm returns and fewer alternations than Sham/F mice, whereas Iso/OP/M mice performed similarly to controls. Likewise, female, but not male, Iso/OP mice displayed impaired associative learning in the active avoidance test, evidenced by fewer avoided trials and more escape responses. These long-term behavioral abnormalities were accompanied by sex-divergent transcriptomic remodeling in the OB and HI, including altered synaptic, neurodevelopmental, extracellular matrix, stress-response, and chemotaxis-related pathways. Iso/OP reduced plasma EV particle numbers in both sexes and shifted EV size distributions, with prominent reductions in the 40-100 nm EV fraction. Proteomics revealed distinct sex-and condition-specific EV profiles, with several EV-associated proteins showing opposing sex-dependent expression patterns. Hippocampal injection of Iso/OP-derived EVs induced donor sex-dependent cytokine remodeling, confirming inflammatory bioactivity. ConclusionsFour-hour isoflurane (Iso) exposure combined with laparotomy in young adult mice induces chronic, sex-dependent neurological deficits with distinct transcriptomic remodeling across brain subregions. Persistent alterations in circulating EV abundance and inflammatory cargo may drive chronic neuroinflammation and long-term brain dysfunction.

The longstanding association between psychological trauma or stress and subsequent chronic inflammatory disorders is well-documented, but the mechanism by which psychopathology causes these immune changes has yet to be elucidated. We have previously reported that sympathetic innervation to lymphoid organs and beta adrenergic receptor signaling are essential for T-lymphocyte interleukin 17A (IL-17A) production and TH17 polarization, though the exact mechanistic contribution of this signaling to the development of TH17 cells remained unclear. Therefore, we hypothesized that norepinephrine (NE) is a novel and direct regulator of T-lymphocyte IL-17A expression. Herein, we indeed observed that NE regulates baseline IL-17A in vivo. We further identified a novel mechanism by which transforming growth factor beta (TGF{beta}) and NE together result in TH17 polarization and IL-17A production in CD4+ T-lymphocytes. Additionally, we found that cAMP, PKA, and CREB are induced by NE signaling, which ultimately increases CBP/p300 activity to initiate ROR{gamma}t transcription. Surprisingly, our data also demonstrate that STAT3, a transcription factor previously described as necessary for canonical TH17 polarization, is not involved in this novel pathway and may even be downregulated. Combined with bulk RNA sequencing data, our data highlight robust differences between the novel and canonical pathways to TH17 polarization. Altogether, our data reveal a novel, noncanonical mechanism that links sympathetic nervous system activity with IL-17A related inflammation, which may have significant relevance to sympathoexcitation-related disorders that stem from psychological trauma or stress.

Emotional lability (EL) is a prevalent cross-diagnostic symptom with unclear etiology. Given the potential role of the gut-brain axis in linking gut microbiota to EL, we adopted a multi-step Mendelian randomization (MR) framework to investigate the causal effects of gut microbiota on EL and the mediating role of blood metabolites. Bidirectional two-sample MR was first implemented to determine the causal relationship and direction between gut microbiota and EL, followed by multivariable MR (MVMR) to assess the direct contributions of individual microbial taxa. We then applied a multistep MR approach to identify gut microbiota specifically associated with EL-related psychopathology. Finally, the mediation effects of blood metabolites were quantified via the coefficient of variation method, and pathway analysis was conducted to verify the biological plausibility of the enriched metabolic pathways. Bidirectional MR detected 16 gut microbiota species associated with EL risk. MVMR identified three causally associated bacteria: RUG013 sp001486445 exerted the strongest positive effect (odds ratio [OR] = 1.500, 95\% confidence interval [CI]: 1.029-2.187, P = 0.034), followed by CAG-485 sp002362485 (OR = 1.398, 95\% CI: 1.118-1.749, P = 0.003). Each standard deviation (SD) increment in CAG-485 sp002362485 was linked to a 39.8\% higher risk of EL. This bacterium was specific to EL and correlated with glycine/serine/threonine metabolites. Reverse MR analyses ruled out reverse causality .

Background: Major depressive disorder (MDD) is a severe mental illness associated with severe clinical consequences and substantial societal burden. It's characterized by immune-inflammatory dysregulation and immune sensitization. Objective: To determine whether in vitro ketamine attenuates phytohemagglutinin (PHA)/lipopolysaccharide (LPS)-induced immune sensitization in patients with MDD and healthy controls (HCs). Methods: Whole blood from 18 patients with MDD and 18 HCs was stimulated with PHA/LPS and exposed to ketamine (0.3 M, 0.6 M, and 6 M) for 72 hours. Cytokines, chemokines, growth factors, and composite immune profiles, including M1/M2 macrophages, T helper (Th)1/2/17, the immune-inflammatory response system (IRS), and compensatory immunoregulatory system (CIRS), were synthesized and determined. Results: Under PHA and LPS stimulation in vitro, the MDD group exhibited markedly elevated immune profiles, including M1, M2, Th1, Th2, Th17, IRS, CIRS, chemokines, and growth factors, consistent with immune sensitization. Significant group-by-treatment interactions were observed for Th1-Th2, M2, growth factors, IL-12(p70), M1, and chemokines. Ketamine produced minimal changes in HCs but broader suppression in MDD, particularly at the highest concentration, without normalizing the sensitized immune phenotype. Among the immune markers with no notable group-by-treatment interactions, ketamine exerted diagnosis-independent effects, decreasing MIP-1{beta}, IL-1&{beta}, Th1, TNF-{beta} IRS, IFN-{gamma}, and IL-2 compared to the control condition. Conclusions: Ketamine exhibited two distinct immunoregulatory patterns: selective, disease-dependent attenuation of sensitized immune pathways and broader, diagnosis-independent suppression of the stimulated immune response, predominantly at higher concentrations. However, these effects were insufficient to normalize the immune-sensitized phenotype of MDD.

Preterm birth is strongly linked to systemic inflammation and encephalopathy of prematurity, which underlies subsequent cognitive impairment. T-cell immunity contributes to brain-immune crosstalk across the life course but its role in the pathogenesis of encephalopathy of prematurity is unknown. Protein epigenetic scores are DNA methylation (DNAm)-based proxies of circulating proteins. We tested the hypothesis that T-cell dysregulation has a specific role in child neurodevelopment following preterm birth. Multimodal data were collected from 144 preterm infants (median gestational age at birth 29+5 weeks [range 23+3 to 32+6]) recruited to a prospective cohort study: saliva DNAm for protein epigenetic score derivation and brain MRI, both at term-equivalent age, and the Mullen Scales of Early Learning Composite score at 5 years from a subset. We investigated associations of the epigenetic scores for cytotoxic and regulatory T cell-associated molecule (DNAm CRTAM) and C-reactive protein (DNAm CRP; a non-specific marker of inflammation) with MRI metrics of encephalopathy of prematurity: global and regional brain volumes, and general factors of diffusion tensor imaging and neurite orientation dispersion and density imaging metrics averaged across 42 white matter tracts. We tested whether DNAm CRTAM explains more variance than DNAm CRP in MRI metrics of the encephalopathy of prematurity and cognitive scores in childhood. Higher neonatal DNAm CRTAM was associated with lower general factor of fractional anisotropy ({beta} = -0.252, q = 0.011) and higher general factors of radial diffusivity ({beta} = 0.215, q = 0.039), mean diffusivity ({beta} = 0.198, q = 0.047) and orientation dispersion index ({beta} = 0.201, q = 0.048), independent of inflammatory morbidities and other biological covariates after false discovery rate correction. DNAm CRTAM explained more variance than DNAm CRP (maximum incremental R2 = 4.2% vs 1.5%) in diffusion MRI metrics. Higher neonatal DNAm CRTAM was associated with lower cognitive scores at 5 years, independent of DNAm CRP and other covariates ({beta} = -0.332, P = 0.008), and explained more variance in cognitive scores than DNAm CRP (incremental R2 = 9.4% vs 1.2%). An epigenetic proxy of CRTAM in preterm infants is associated with both encephalopathy of prematurity in the neonatal period and lower cognitive performance at 5 years, explaining greater incremental variance than a non-specific marker of inflammation. The data implicate T-cell dysregulation in the pathophysiology of atypical neurodevelopment following preterm birth.

Schizophrenia spectrum disorders (SSD) have been linked to immune dysregulation and altered intestinal barrier function, although findings across studies remain inconsistent. The present study investigated circulating markers of intestinal permeability and immune activation in individuals with early-stage SSD and healthy controls and examined their associations with clinical outcomes. Serum concentrations of intestinal fatty acid-binding protein (iFABP), zonulin, soluble CD14 (sCD14), bactericidal/permeability-increasing protein (BPI), and lipopolysaccharide-binding protein (LBP) were measured in 36 patients with SSD at baseline and one-year follow-up and in 36 matched healthy controls. Linear mixed-effects models adjusted for age, sex, and body mass index (BMI) were used to evaluate group differences and longitudinal changes. No biomarker differences between patients and controls, and no longitudinal changes within patients, remained statistically significant after correction for multiple testing. Similarly, biomarker concentrations were not associated with symptom severity, global functioning, or neutrophil-to-lymphocyte ratio (NLR). Exploratory analyses identified a robust positive association between BMI and zonulin concentrations and additional associations among iFABP, LBP, and sCD14. Exploratory mixed-effects models identified a negative non-significant association between iFABP and sCD14 after adjustment for age, sex, and BMI. Overall, the findings do not support a generalized alteration of gut permeability or immune activation markers in SSD. Instead, they suggest that variation in gut-related biomarkers may be more strongly influenced by metabolic and individual factors than by diagnosis or current symptom severity.

Introduction: Multidomain lifestyle interventions may slow down cognitive decline and dementia, but the brain mechanisms underlying these effects remain unclear. We investigated brain, inflammation, cardiometabolic, and gut health changes associated with a six-month multidomain lifestyle intervention in Dutch older adults at risk for cognitive decline and dementia. Method: Participants aged 60-75 years with [&ge;]2 lifestyle-modifiable cardiovascular risk factors (e.g., BMI [&ge;]25, physical inactivity) were recruited and randomised in a 1:1 ratio to a high-intensity intervention or active control group using stratified (2,4) block-randomisation. The multidomain lifestyle intervention included five lifestyle domains (diet, physical activity, stress management and mindfulness, cognitive training, and sleep). Primary outcomes were changes in cerebral perfusion levels, brain activity during working memory, working memory performance, inflammation profile, and microbiota diversity. Secondary outcomes included lifestyle factors and markers of neuroimaging, brain health, cardiovascular and gut health, and cognitive functioning. The effects of the lifestyle intervention were investigated using linear mixed-effect models. Results: A total of 102 participants were randomised into the intervention (n=53) or active control group (n=49), of which 86 participants completed the six-month multidomain lifestyle intervention. Baseline characteristics were similar between the groups. Within the intervention group, favourable reductions in lifestyle-modifiable cardiovascular risk factors, such as BMI and blood pressure, were observed, but these were not significantly different from changes in the active control group. The intervention resulted in improved diet and sleep scores in the intervention group compared to the active control group (Beta 1.67, 95% CI 0.61;2.73, PFDR=0.01, and Beta -1.80, 95% CI -2.79;-0.81, PFDR=0.005, respectively). The intervention did not result in significant changes over time between the intervention and control group in primary and secondary outcomes. Conclusion: The HELI multidomain lifestyle was able to reduce lifestyle-modifiable cardiovascular risk factors associated with dementia, although not significant compared to the active control group. We did not observe significant intervention effects on brain, cardiometabolic, inflammatory, and gut health outcomes. These results emphasize the complexity of exploring the role of lifestyle on neurobiological brain mechanisms associated with maintaining optimal cognitive functioning in aging and their underlying peripheral (to central) mechanisms.

Maternal depression and psychosocial adversity during pregnancy are associated with altered offspring neurodevelopment, yet the molecular processes linking maternal state to the developing fetus remain incompletely understood. The placenta is positioned to sense and respond to maternal physiological signals, but how placental molecular responses relate to those in the developing brain is unclear. Here, we used a mouse model of prolonged social isolation initiated before conception and maintained throughout pregnancy to investigate inflammatory and transcriptional alterations across matched placenta and fetal-brain samples at gestational day 18. Maternal social isolation altered cytokine profiles in both tissues and induced extensive transcriptional changes in the placenta, with a more restricted response in the fetal brain. Functional analyses identified alterations in placental immune, metabolic and transport-related programmes and fetal-brain immune, neuronal and proliferative processes. Although sex-stratified analyses revealed different transcriptional profiles in male and female tissues, formal maternal housing x fetal-sex interaction testing did not identify significant gene-level interaction effects. Cross-tissue co-expression analysis initially identified extensive covariation between social-isolation-responsive placental and fetal-brain modules; however, most associations were attenuated after accounting for their shared relationship with maternal housing. An exposure-independent network analysis nevertheless identified an inverse pregnancy-level association between a placental module enriched for immune and interferon-related signalling and a fetal-brain module enriched for cell-cycle and proliferative processes. Together, these findings show that prolonged maternal social adversity is associated with coordinated but tissue-distinct molecular alterations across the placenta-fetal brain axis and demonstrate the importance of distinguishing parallel responses to a common maternal environment from direct cross-tissue molecular coupling.

BackgroundPsilocybin, a classic psychedelic, produces acute alterations in brain function, and has shown sustained therapeutic effects in psychiatric disorders. However, most studies focus on acute brain imaging readouts (e.g., fMRI) and rarely assess longer-term molecular changes. MicroRNAs (miRNAs) are small non-coding RNAs that regulate gene expression, are enriched in the brain, and can be released into blood, potentially indexing brain-relevant molecular processes. We hypothesised that a single psilocybin dose would show acute changes in miRNAs with predicted relevance to neuroplasticity related signalling and immune/inflammatory regulation in healthy adults. MethodsIn a randomised, double-blind, placebo-controlled study (N=62; 31 psilocybin, 31 placebo), volunteers received psilocybin (0.17 mg/kg) or placebo. Blood was collected at baseline, 360 minutes, and 7 days after dosing. Plasma miRNAs were quantified by small RNA sequencing. Elastic net regression was used for feature selection, followed by differential expression analysis and validation with linear mixed models. Pathway enrichment used Reactome and Gene Ontology. ResultsTwo circulating miRNAs (let-7g-5p and miR-150-5p) met criteria for differentially expressed at 360 minutes following psilocybin administration, with no significant differences detected at 7 days or in the placebo condition under the statistical thresholds used. Over representation analysis suggested enrichment of molecular processes involved in neuroplasticity (e.g., TrkA, MAPK), inflammation (e.g., IL-6, TGF-{beta}), and transcriptional regulation (e.g., RNA polymerase II, SMAD2/3/4). ConclusionsA single oral dose of psilocybin was associated with transient alterations in circulating miRNA expression, consistent with an acute shift in circulating gene-regulatory miRNA signals, without sustained miRNA changes at 7 days. These findings provide initial evidence that circulating miRNA changes after psilocybin may reflect acute molecular process responses and support further investigation of circulating miRNAs as potential biomarkers of psychedelic-induced molecular responses.