BACKGROUND:Infants and their caregivers reciprocally influence each other through transactions within everyday activities, facilitating further child development. OBJECTIVES:This study assessed a transactional pathway between infant gaze capacities and maternal responsiveness across development and associations with child joint engagement at 24 months and social-emotional competence at 36 to 42 months of age. METHODOLOGY:Videos of mother-child play at 2, 6, 9, 12, 18, and 24 months were used to behaviorally code infant gaze, maternal responsiveness, and child joint engagement. Mothers completed a parent-report measure of social-emotional competence about their child at 36 to 42 months. Structural equation modeling tested the developed transactional model. RESULTS:The proposed transactional pathway between infant person-gaze capacities and maternal responsivity across 2 to 18 months mediated joint engagement, while joint engagement was associated with social-emotional competence. CONCLUSION:Transactions occurring within play occupations between infants and caregivers across early development are critical for development of social-emotional competencies.

Abstract Early life adversity (ELA) is a leading preventable contributor to morbidity and mortality, increasing risk for mental and physical illness later in life. However, mechanisms linking ELA to comorbid outcomes within both the brain and body remain poorly understood. We tested whether ELA disrupts functional and molecular development of vagal circuitry, a key pathway for brain-body communication, using the limited bedding and nesting (LBN) mouse model of unpredictable maternal care. We measured vagally mediated autonomic stress responses longitudinally using three noninvasive measures of heart rate variability (HRV). This is the first time the development of the vagally-mediated autonomic stress response has been measured in mice. We also performed single-nucleus RNA sequencing of the vagal medulla immediately after LBN and in adulthood, followed by spatial mapping of high-confidence differentially expressed genes. ELA altered trajectories of all HRV measures, with pronounced sex differences. ELA females showed precocious maturation followed by adult declines, whereas males initially exhibited blunted responses but recovered to control levels. Transcriptomic changes were also sex dependent, with female neurons exhibiting signatures of mitochondrial dysfunction, while males showed adaptive mitochondrial responses. Spatial mapping revealed rostro-caudal organization, localizing adaptive male responses to the rostral and intermediate vagal medulla and maladaptive female responses to the intermediate vagal medulla and loose nucleus ambiguus. These findings demonstrate enduring, sex-specific alterations in vagal circuit development centered on mitochondrial pathways.

Given clear connections between mental and physical health, the impact of dysfunctional brain-body communication on emotional behavior and psychopathology is garnering increased attention. Vagal circuits comprise a major neural substrate for communication between the brain and peripheral organs, and evidence suggests that these circuits are developmentally plastic and sensitive to stress and other environmental challenges. Here, we review historic and current literature regarding how early life experience shapes the development of vagal circuitry in rodents and in humans. We discuss the anatomical intricacies of the sensory and motor vagal systems in rodents and outline their pre- and postnatal windows of developmental plasticity. We then focus on how two core features of early life experience, i.e., nutrition and maternal care, alter vagal circuit development in rodents. We discuss human studies that use differing psychological frameworks for measuring, interpreting, and contextualizing vagal contributions to the development of emotional control and stress response systems. We focus on infant, child, and adolescent research that test relations between parental care and/or early life adversity and vagal function, and how these factors impact emotional regulation and development of psychopathology. By synthesizing literature across species, we draw attention to novel insights and testable hypotheses that can be explored using different model systems. We emphasize the importance of considering environmental context and developmental timing for study design and interpretation of results. We conclude that vagal circuitry is an environmentally sensitive system for encoding stressful experiences during early life in rodents and in humans, with lifespan health consequences.

The ability to rapidly detect and evaluate potential threats is essential for survival and requires the integration of sensory information with internal state and previous experience. The lateral septum (LS)-an inhibitory structure in the limbic forebrain-is thought to integrate these higher-order cognitive signals to regulate defensive responses1,2. However, the cellular, circuit and computational mechanisms fundamental to this process remain unknown. Here we focus on the population of LS neurons that express the type 2 CRH receptor (LSCrhr2), a neuronal subset shown to be critical for state-dependent behavioural changes and threat responsivity3-7 in mice. We use a combination of single-cell calcium imaging, molecular sequencing and circuit dissection to reveal the spatial and functional organization of the cell types involved, the computations they perform and the information relayed by their upstream activators. We determine that LSCrhr2 population activity is required for cue-driven defensive actions by rapidly and dynamically encoding threat representations that predict behavioural outcomes. We find that these threat representations are formed through the convergence of various signals differentially represented by distinct LSCrhr2 subclasses, which are defined by their molecular features, spatial locations and input architectures. Notably, these responses reflect specific afferents from the hippocampus and hypothalamus that preferentially impart cue- and action-related signals, respectively. These findings establish a multifeatured organizational principle that underlies how the LS mediates motivated behaviours in response to environmental challenges.

Experiencing early life adversity (ELA) and chronic stress activation early in childhood increases the risk for altered developmental trajectories that lead to lifelong impacts on physical and mental health. This results in a toxic stress response – the dysregulation of neuroendocrine, immune and metabolic functions that causes allostatic load and a higher risk for poor health. Current screening practices for identifying toxic stress is the typical use Adverse Childhood Experience (ACEs) questionnaires, for which higher scores have strong predictability of outcomes at a population level. However, when used as the sole ELA identification tool, the questionnaire has challenges predicting later health outcomes at the individual level. We have proposed that the adaptative processes to ELA converge on mitochondrial health and is measurable in several ways, including the gold standard marker of oxidative stress due to reactive oxygen species, F2α-Isoprostanes (F2α -IsoPs). The major initiation of F2α-IsoPs formation is reactive oxygen species (ROS) accumulation, a major source of which is mitochondria. This study aimed to evaluate the relation between maternal ACEs, child F2α-IsoPs measures, and child neurodevelopment, establishing how the relations change over early developmental periods. In our ongoing “Family First” longitudinal study, F2α-IsoPs were measured from child urine samples collected at 6-,12-, and 24 months. Maternal adversity was assessed using the ACEs questionnaire at 6- and scores were confirmed at 12-months. The Bayley Scales of Infant Development (Bayley-4) was administered to assess child neurodevelopment at all study time points. Elevated infant F2α-IsoPs at 6 months correlated significantly with lower language ( r=-0.15,p = 0.02) and motor scores (r=-0.16,p = 0.02) as assessed by the Bayley-4. Assessment of the relation between maternal ACEs on changes in infant F2α-IsoPs levels over the first year of life demonstrated there were significantly different F2α-IsoPs (15-F2t-IsoP, p = 0.003) and (5-F2t-IsoP, p = 0.001) trajectories for infants whose mothers endorsed either 0, 1–2, or 3 + on ACEs. Changes in child Bayley-4 scores in the second year of life varied by maternal ACEs with children whose mothers had no endorsements of adversity had decreasing language and motor scores and children whose mothers had any endorsements on ACEs had increasing language(p = 0.02) and motor scores (p = 0.02). The data indicate that there may be specific physiologic contributions of oxidative stress to a toxic stress response in young children. A broader approach to pediatric screening for toxic stress predictability may be the incorporation of F2α-IsoPs as one of the physiologic measures in the first two years postnatally.

Mouse models of human disease focus on determining the direct impact of genetic mutations on phenotypes related to clinical presentations. For example, loss of function mutations in the autism-associated CHD8 gene is highly penetrant for trait and behavioral abnormalities in children, but there is substantial clinical heterogeneity in the occurrence and extent of disruptions between individuals. Using a large genetic reference panel of mice, we recently showed that genetic background strongly regulates variability in trait disruptions caused by Chd8 haploinsufficiency. Here, we hypothesized that genetics could also impact the variability in response to early life experiences, thus contributing to differential susceptibility to neurodevelopmental disorders. To examine how genetic diversity impacts rearing experience, we systematically observed the behavior of genetically diverse offspring raised by genetically identical mothers. The results reveal strain differences in pup and maternal behaviors. Machine learning analysis reveals that early life litter experiences are strong predictors of sex-dependent postweaning social, anxiety-like, and cognitive trait disruptions due to Chd8 haploinsufficiency. The study suggests that offspring phenotypes in mutant models of disease are due to a combination of heritable and early experience factors, demonstrating the utility of incorporating genetic diversity in studies to model the mechanisms that underlie the heterogeneity of disrupted phenotypes in neurodevelopmental disorders.

Day length, or seasonal photoperiod, shapes mood and affective behaviors but the neural mechanisms underlying these effects are still being defined. Serotonin neurons of the dorsal raphe nucleus (DRN) are critical regulators of affective behaviors and photoperiod modulates their excitability and ongoing activity. Here, we investigated the influence of seasonal photoperiod on the function and expression of small conductance calcium-activated potassium (SK) channels which mediate the afterhyperpolarizing potential (AHP) in dorsal raphe serotonin neurons. Building on previous work demonstrating that photoperiod modulates serotonergic excitability and behavior, we hypothesized that day length influences SK channel activity, thereby contributing to differences in neuronal excitability observed between Long, Equinox, and Short photoperiod conditions. Using multi-electrode array recording of DRN slices we found a significant dose-dependent increase in spike rate to the application of the SK channel inhibitor apamin, indicating that SK channels indeed influence the spike rate of dorsal raphe serotonin neurons. In addition, DRN neurons in slices from Long photoperiod mice exhibited less pronounced responses to apamin relative to those from Short photoperiod mice, suggesting reduced function or expression of SK channels in Long photoperiod. Indeed, whole-cell recordings demonstrated that SK channel–mediated AHP currents were reduced in Long photoperiod mice. However, there were no significant differences in expression levels of the SK3 subunit (Kcnn3) in DRN serotonin neurons across photoperiod conditions as determined by single molecule fluorescence in situ hybridization. Overall, these findings indicate that photoperiod modulates SK channel function in DRN serotonin neurons likely at a post-transcriptional level. This study advances our understanding of how seasonal cues influence intrinsic neuronal properties and provides a mechanistic link between photoperiod, serotonergic excitability, and mood-related behaviors. The identification of SK channels as modulators of photoperiodic effects may offer novel therapeutic targets for mood disorders associated with dysregulated serotonin signaling. ### Competing Interest Statement The authors have declared no competing interest.

Significant genetic, behavioural and neuroanatomic heterogeneity is common in autism spectrum- and related- neurodevelopmental disorders (NDDs). This heterogeneity constrains the development of effective therapies for diverse patients in precision medicine paradigms. This has led to the search for subgroups of individuals having common etiologic factors/biology (e.g., genetic pathways), thus creating potential uniformity in prognosis and/or treatment response. Despite NDDs having a strong genetic component, only ~15-20% of individuals will present with a specific rare genetic variant considered clinically pathogenic, and therefore, subtyping efforts tend to focus on using clinical, cognitive, and/or brain imaging phenotypes to group individuals. Here we delineated mechanisms via mouse to human translational neuroscience. Using MRI derived structural neuroanatomy and a spatial transcriptomic comparison, we linked subgroups of 135 NDD relevant mouse models (3,515 individual mice) separately to two human databases, with 1,234 and 1,015 human individuals with NDDs, composed of autism, attention-deficit/hyperactivity disorder (ADHD), obsessive compulsive disorder (OCD), other related NDDs, and typically developing controls. Subgroups were significantly linked by consistent neuroanatomy across all three datasets, mouse and human, indicating that direct cross-species subgrouping and translation is consistent and reproducible. Ultimately, four specific neuroanatomical clusters were found and linked to precise molecular mechanisms: two showing a chromatin/transcription motif, with one of those showing specific links to G-protein coupled receptors (GPCR) and Notch signalling, and another two being mainly synaptic in origin, with one off those showing specific connections to axon guidance and Wnt signaling. Assigning molecular pathways, and thus genetic information, from the mouse to individual participants provides an insight into undetected and/or related genetic variants that could be working in combination or interacting with an environmental influence. Moreover, the subgroups found are transdiagnostic, including participants with autism, ADHD, and OCD, which indicates that NDDs as a whole can be subdivided into consistent neuroanatomical clusters with cohesive underlying biological mechanisms. This work allows us to bridge the gap between preclinical models and human disorders, linking previously idiopathic human patients to pertinent genetics, molecular mechanisms, and pathways.

The environment experienced by children, such as exposure to chronic early life adversity (ELA), increases lifespan brain disorder risk. The mechanisms that link ELA exposure to functional brain disruptions are not well understood. A limited-bedding and nesting paradigm, in which ELA is induced in mouse pups over the first postnatal week through disruption of maternal care, is characterized by limited resources, environment unpredictability, and disruption of reward and cognitive behaviors. Studies using this model demonstrated sex-selective alterations in hippocampal mitochondrial-associated proteins in response to ELA compared with care as usual (CAU). Further, oxidative phosphorylation (OXPHOS) capacity and complex I activity are increased in ELA juveniles, yet decreased in adults, with the impact of ELA moderated by sex in adults. Given that altered mitochondrial function is a key mediator in metabolic adaptations, the goal of the present study was to evaluate the possibility of reversing mitochondrial dysfunction and the anhedonia that accompanies ELA by addressing oxidative stress. Treatment with the antioxidant MitoQ began at weaning and extended to 3 months. Measures of complex I activity demonstrated full recovery in adults. Female-specific deficits in the sucrose preference task, which is a measure of rewarding behavior in rodents, also exhibited recovery, with preference for sucrose comparable with that of CAU mice. These data indicate that mitochondrial health is one component of responses to early life adversity that has lifespan implications, but with the capacity to recover normal functioning in adults.

INTRODUCTION:Single-cell transcriptomic analyses in adult mice show that cortical projection neuron subclasses exhibit heterogenous gene expression profiles that reflect their projection targets and laminar and areal positions. Further analyses revealed that projection neurons within the same subclass also exhibit transcriptomic heterogeneity. Recent evidence suggests that differences in maturation state reflect one source of this heterogeneity. The MET receptor tyrosine kinase, a regulator of synapse maturation, is expressed in a subpopulation within cortical projection neuron subclasses, providing an experimental model to address transcriptomic heterogeneity within developing projection neuron subclasses. METHODS:Single-cell RNA sequencing and smFISH were used to identify transcriptomic differences between Met+ and Met- projection neuron populations in the mouse visual and frontal cortices during the early phase of synapse formation and dendritic growth. RESULTS:Analyses confirmed enrichment of Met in select projection neuron subclasses and further identified astrocytes as the major source of its ligand, Hgf. No genes were expressed uniquely in Met+ or Met- projection neurons within a subclass; rather, there were graded differences in gene expression between the populations. While the identity of differentially expressed genes varied between subclass and cortical area, there was a consistent overrepresentation of genes associated with axon growth, as well as synapse structure, development, and function, with a subset associated with the MET interactome. Further, compared to Met- projection neurons, expression differences in genes associated with maturation indicate less mature excitatory synapses and spines in the Met+ population at this age. CONCLUSION:The current findings provide support for the hypothesis that Met+ projection neurons are in a less mature state than Met- projection neurons within the same subclass. Further, the data are consistent with converging lines of biochemical and electrophysiological evidence that MET contributes to asynchronous maturation of developing cortical circuits.

Date Presented 03/21/24 This study investigated associations between caregiver and infant behaviors from 2 to 18 months and child engagement at 24 months. Caregiver child-oriented behaviors should be considered during intervention to promote child engagement in co-occupation. Primary Author and Speaker: Cristin M. Holland Contributing Authors: John Sideris, Pat Levitt, Barbara L. Thompson, Grace Baranek

The mitochondrion is a multifunctional organelle that modulates multiple systems critical for homeostasis during pathophysiological stress. Variation in mitochondrial DNA (mtDNA) copy number (mtDNAcn), a key mitochondrial change associated with chronic stress, is an emerging biomarker for disease pathology and progression. mtDNAcn can be quantified from whole blood samples using qPCR to determine the ratio of mtDNA to nuclear DNA. However, the collection of blood samples in pediatric populations, particularly in infants and young children, can be technically challenging, yield much smaller volume samples, and can be distressing for the patients and their caregivers. Therefore, we have validated a mtDNAcn assay utilizing DNA from simple buccal swabs (Isohelix SK-2S) and report here it's performance in specimens from infants (age = <12 months). Utilizing qPCR to amplify ∼200 bp regions from two mitochondrial (ND1, ND6) and two nuclear (BECN1, NEB) genes, we demonstrated absolute (100%) concordance with results from low-pass whole genome sequencing (lpWGS). We believe that this method overcomes key obstacles to measuring mtDNAcn in pediatric populations and creates the possibility for development of clinical assays to measure mitochondrial change during pathophysiological stress.

In spite of the great progress that has been made towards automating brain extraction in human magnetic resonance imaging (MRI), challenges remain in the automation of this task for mouse models of brain disorders. Researchers often resort to editing brain segmentation results manually when automated methods fail to produce accurate delineations. However, manual corrections can be labor-intensive and introduce interrater variability. This motivated our development of a new deep-learning-based method for brain segmentation of mouse MRI, which we call Mouse Brain Extractor. We adapted the existing SwinUNETR architecture (Hatamizadeh et al., 2021) with the goal of making it more robust to scale variance. Our approach is to supply the network model with supplementary spatial information in the form of absolute positional encoding. We use a new scheme for positional encoding, which we call Global Positional Encoding (GPE). GPE is based on a shared coordinate frame that is relative to the entire input image. This differs from the positional encoding used in SwinUNETR, which solely employs relative pairwise image patch positions. GPE also differs from the conventional absolute positional encoding approach, which encodes position relative to a subimage rather than the entire image. We trained and tested our method on a heterogeneous dataset of N=223 mouse MRI, for which we generated a corresponding set of manually-edited brain masks. These data were acquired previously in other studies using several different scanners and imaging protocols and included in vivo and ex vivo images of mice with heterogeneous brain structure due to different genotypes, strains, diseases, ages, and sexes. We evaluated our method's results against those of seven existing rodent brain extraction methods and two state-of-the art deep-learning approaches, nnU-Net (Isensee et al., 2018) and SwinUNETR. Overall, our proposed method achieved average Dice scores on the order of 0.98 and average HD95 measures on the order of 100 μm when compared to the manually-labeled brain masks. In statistical analyses, our method significantly outperformed the conventional approaches and performed as well as or significantly better than the nnU-Net and SwinUNETR methods. These results suggest that Global Positional Encoding provides additional contextual information that enables our Mouse Brain Extractor to perform competitively on datasets containing multiple resolutions.

Mothers of infants have specific demands in fostering emotional bonds with their children, characterized by dynamics that are different from adult-adult interactions, notably requiring heightened maternal emotional regulation. In this study, we analyzed maternal emotional state by modeling maternal emotion regulation reflected in smiles. The dataset comprises N=94 videos of approximately 3 +/- 1-minutes, capturing free play interactions between 6 and 12-month-old infants and their mothers. Corresponding demographic details of self-reported maternal mental health provide variables for determining mothers' relations to emotions measured during free play. In this work, we employ diverse methodological approaches to explore the temporal evolution of maternal smiles. Our findings reveal a correlation between the temporal dynamics of mothers' smiles and their emotional state. Furthermore, we identify specific smile features that correlate with maternal emotional state, thereby enabling informed inferences with existing literature on general smile analysis. This study offers insights into emotional labor, defined as the management of one's own emotions for the benefit of others, and emotion regulation entailed in mother-infant interactions.

Mutations in CHD8 are one of the highest genetic risk factors for autism spectrum disorder. Studies in mice that investigate underlying mechanisms have shown Chd8 haploinsufficient mice display some trait disruptions that mimic clinical phenotypes, although inconsistencies have been reported in some traits across different models on the same strain background. One source of variation across studies may be the impact of Chd8 haploinsufficiency on maternal-offspring interactions. While differences in maternal care as a function of Chd8 genotype have not been studied directly, a previous study showed that pup survival was reduced when reared by Chd8 heterozygous dams compared with wild-type (WT) dams, suggesting altered maternal care as a function of Chd8 genotype. Through systematic observation of the C57BL/6 strain, we first determined the impact of Chd8 haploinsufficiency in the offspring on WT maternal care frequencies across preweaning development. We next determined the impact of maternal Chd8 haploinsufficiency on pup care. Compared with litters with all WT offspring, WT dams exhibited less frequent maternal behaviors toward litters consisting of offspring with mixed Chd8 genotypes, particularly during postnatal week 1. Dam Chd8 haploinsufficiency decreased litter survival and increased active maternal care also during postnatal week 1. Determining the impact of Chd8 haploinsufficiency on early life experiences provides an important foundation for interpreting offspring outcomes and determining mechanisms that underlie heterogeneous phenotypes.

Cognitive impairment is a common phenotype of neurodevelopmental disorders, but how these deficits arise remains elusive. Determining the onset of discrete cognitive capabilities facilitates studies in probing mechanisms underlying their emergence. The present study analyzed the emergence of contextual fear memory persistence (7-day memory retention) and remote memory (30-day memory retention). There was a rapid transition from postnatal day (P) 20 to P21, in which memory persistence emerged in C57Bl/6J male and female mice. Remote memory was present at P23, but expression was not robust compared to pubertal and adult mice. Previous studies reported that following deletion of the MET receptor tyrosine kinase (MET), there are fear memory deficits in adult mice and the timing of critical period plasticity is altered in the developing visual cortex, positioning MET as a regulator for onset of contextual fear memory. Sustaining Met past the normal window of peak cortical expression or deleting Met, however, did not alter the timing of emergence of persistence or remote memory capabilities during development. Fear memory in young adults, however, was disrupted. Remarkably, compared to homecage controls, the number of FOS-expressing infragranular neurons in medial prefrontal cortex (mPFC) did not increase from contextual memory formation recall of fear conditioning at P35 but exhibited enhanced activation at P90 in male and female mice. Additionally, MET-expressing neurons were preferentially recruited at P90 compared to P35 during fear memory expression. The studies demonstrate a developmental profile of contextual fear memory capabilities. Further, developmental disruption of Met leads to a delayed functional deficit that arises in young adulthood, correlated with an increase of mPFC neuron activation during fear memory recall.

The HEALthy Brain and Child Development (HBCD) Study, a multi-site prospective longitudinal cohort study, will examine human brain, cognitive, behavioral, social, and emotional development beginning prenatally and planned through early childhood. The longitudinal collection of biological samples from over 7,000 birthing parents and their children within the HBCD study enables research on pre- and postnatal exposures (e.g., substance use, toxicants, nutrition), and biological processes (e.g., genetics, epigenetic signatures, proteins, metabolites) on neurobehavioral developmental outcomes. The following biosamples are collected from the birthing parent: 1) blood (i.e., whole blood, serum, plasma, buffy coat, and dried blood spots) during pregnancy, 2) nail clippings during pregnancy and one month postpartum, 3) urine during pregnancy, and 4) saliva during pregnancy and at in-person postnatal assessments. The following samples are collected from the child at in-person study assessments: 1) saliva, 2) stool, and 3) urine. Additionally, placenta tissue, cord blood, and cord tissue are collected by a subset of HBCD sites. Here, we describe the rationale for the collection of these biospecimens, their current and potential future uses, the collection protocol, and collection success rates during piloting. This information will assist research teams in the planning of future studies utilizing this collection of biological samples.

Alterations in the expression of genes encoding proteins involved in synapse formation, maturation, and function are a hallmark of many neurodevelopmental and psychiatric disorders. For example, there is reduced neocortical expression of the MET receptor tyrosine kinase (MET) transcript and protein in Autism Spectrum Disorder (ASD) and Rett syndrome. Preclinical in vivo and in vitro models manipulating MET signaling reveal that the receptor modulates excitatory synapse development and maturation in select forebrain circuits. The molecular adaptations underlying the altered synaptic development remain unknown. We performed a comparative mass spectrometry analysis of synaptosomes generated from the neocortex of wild type and Met null mice during the peak of synaptogenesis (postnatal day 14; data are available from ProteomeXchange with identifier PXD033204). The analyses revealed broad disruption of the developing synaptic proteome in the absence of MET, consistent with the localization of MET protein in pre- and postsynaptic compartments, including proteins associated with the neocortical synaptic MET interactome and those encoded by syndromic and ASD risk genes. In addition to an overrepresentation of altered proteins associated with the SNARE complex, multiple proteins in the ubiquitin-proteasome system and associated with the synaptic vesicle, as well as proteins that regulate actin filament organization and synaptic vesicle exocytosis/endocytosis, were disrupted. Taken together, the proteomic changes are consistent with structural and functional changes observed following alterations in MET signaling. We hypothesize that the molecular adaptations following Met deletion may reflect a general mechanism that produces circuit-specific molecular changes due to loss or reduction of synaptic signaling proteins.

Background Although investigations have begun to differentiate biological and neurobiological responses to a variety of adversities, studies considering both endocrine and immune function in the same datasets are limited. Methods Associations between proximal (family functioning, caregiver depression, and anxiety) and distal (SES-D; socioeconomic disadvantage) early-life adversities with salivary inflammatory biomarkers (IL-1β, IL-6, IL-8, and TNF-α) and hair HPA markers (cortisol, cortisone, and dehydroepiandrosterone) were examined in two samples of young U.S. children ( N = 142; N = 145). Results Children exposed to higher SES-D had higher levels of TNF-α ( B = 0.13, p = 0.011), IL-1β ( B = 0.10, p = 0.033), and DHEA ( B = 0.16, p = 0.011). Higher family dysfunction was associated with higher cortisol ( B = 0.08, p = 0.033) and cortisone ( B = 0.05, p = 0.003). An interaction between SES-D and family dysfunction was observed for cortisol levels ( p = 0.020) whereby children exposed to lower/average levels of SES-D exhibited a positive association between family dysfunction and cortisol levels, whereas children exposed to high levels of SES-D did not. These findings were partially replicated in the second sample. Conclusions Our results indicate that these biological response systems may react differently to different forms of early-life adversity. Impact Different forms of early-life adversity have varied stress signatures, and investigations of early-life adversities with inflammation and HPA markers are lacking. Children with higher socioeconomic disadvantage had higher TNF-α, IL-1β, and DHEA. Higher family dysfunction was associated with higher hair cortisol and cortisone levels, and the association between family dysfunction and cortisol was moderated by socioeconomic disadvantage. Biological response systems (immune and endocrine) were differentially associated with distinct forms of early-life adversities.