Bragg, C. | Search bioRxiv

bioRxiv2026

Extracellular Vesicles From Metabolically Healthy Obesity Convey Distinct Molecular Signals That Initiate Endothelial Dysfunction: A Multi-Omics Study in Adults of African Ancestry

BackgroundMetabolically healthy obesity (MHO) is unstable, with up to 80% of individuals progressing to metabolically abnormal obesity (MAO), yet mechanisms underlying this transition remain unclear. African Americans bear a disproportionate burden of obesity-related cardiovascular disease. Circulating extracellular vesicles (EVs) mediate inter-organ communication and may drive MAO-related vascular dysfunction. MethodsAdults of African ancestry were classified as metabolically healthy lean (MHL, n=14), MHO (n=9), or MAO (n=16). Plasma-derived EVs were characterized and their microRNA cargo profiled. Human coronary artery endothelial cells were treated with EVs from each group to assess nitric oxide signaling, oxidative stress, inflammatory activation, and mitochondrial dynamics. ResultsMHO participants exhibited preserved insulin sensitivity and lower inflammation compared with MAO despite comparable adiposity. EVs from MHO carried a distinct microRNA signature enriched in miR-148a-5p, miR-181c-5p, and miR-1255a, linked to antioxidant and matrix regulatory pathways. MAO EVs were enriched in miR-3613-3p, miR-6842-3p, and miR-326, targeting inflammation and insulin resistance pathways. Compared with both MHL and MHO EVs, MAO EVs suppressed endothelial nitric oxide synthase phosphorylation and reduced nitric oxide bioavailability, with increased reactive oxygen species and ICAM-1 expression. MHO EVs induced an intermediate phenotype with disrupted mitochondrial morphology, supporting a graded continuum of endothelial stress. ConclusionsMHO represents a biologically active intermediate state. Circulating EVs from MHO individuals convey molecular signals that impair endothelial and mitochondrial function, predisposing to vascular injury and progression toward MAO. EV-associated microRNAs are mechanistic mediators and candidate biomarkers of metabolic and vascular deterioration in obesity. CLINICAL PERSPECTIVEO_ST_ABSWhat Is New?C_ST_ABSO_LIThis study systematically investigated extracellular vesicles derived from metabolically healthy obese individuals to define direct vesicle effects on endothelial function using integrated omics coupled to functional outputs. C_LIO_LIExtracellular vesicles from metabolically healthy obesity convey a distinct molecular and biological signature that distinguishes lean and metabolically abnormal obesity. C_LIO_LIMetabolic health status, rather than obesity alone, drives extracellular vesicle-mediated endothelial nitric oxide signaling, oxidative stress, inflammation, and mitochondrial dynamics. C_LI What Are the Clinical Implications?O_LIThese findings explain why some individuals with obesity exhibit preserved vascular function while others develop early endothelial dysfunction. C_LIO_LIStratifying obesity by metabolic health status improves cardiovascular risk assessment beyond body mass index alone. C_LIO_LITargeting extracellular vesicle signaling pathways represents a novel strategy to prevent metabolically healthy individuals from progressing to metabolically abnormal obesity. C_LI

molecular biology↗

bioRxiv2025

Non-vocal motor deficits in a transgenic mouse model linked to stuttering disorders

Stuttering is a neurodevelopmental disorder characterized by involuntary disruptions in speech. In addition, non-vocal motor impairments are reported in some individuals who stutter. Although its precise cause remains unknown, mutations in lysosomal trafficking proteins (such as GNPTAB) have been identified in a subgroup of people who stutter. To understand the functional significance of these mutations, transgenic Gnptab mice have been developed, and as expected, these mice exhibit vocal deficits throughout developmental stages. However, whether these mice also display non-vocal motor impairments is unknown. Our data reveal deficits in the breathing, locomotion, and grooming behaviors of the Gnptab mouse model, outlining a broader phenotype linked to GNPTAB mutations in stuttering. These findings suggest that lysosomal dysfunction may disrupt astrocyte-regulated motor circuits, affecting both vocal and non-vocal rhythmic behaviors that are central to stuttering neurophysiological symptoms.

genetics↗

bioRxiv2025

Iron dysregulation in mice engineered with a mutation associated with stuttering

Stuttering is a neurodevelopmental disorder characterized by involuntary disruptions in the normal fluency and timing of speech. Recently, stuttering has been related to specific point mutations in GNPTAB, a gene involved in lysosomal enzyme-targeting pathways, though it remains unclear how such a mutation might cause the stuttering phenotype. Herein, we studied mice engineered with the mutation in the Gnptab gene found in humans who stutter and found increased iron deposition in the basal ganglia of these mice. Further, we found these iron deposits localized predominantly with regional astrocytes when Perls stain was combined with an astrocyte-specific marker. Reducing iron deposition in the brain with iron chelation therapy improved vocalization symptoms in Gnptab-mutant mice. Our data suggest a relationship between the Gnptab mutation, iron homeostasis in astrocytes, and the stuttering phenotype, for which the underlying mechanisms remain to be elucidated.

cell biology↗

bioRxiv2024

Morphological deficits of glial cells in a transgenic mouse model for developmental stuttering

Vocal production involves intricate neural coordination across various brain regions. Stuttering, a common speech disorder, has genetic underpinnings, including mutations in lysosomal-targeting pathway genes. Using a Gnptab-mutant mouse model linked to stuttering, we examined neuron and glial cell morphology in vocal production circuits. Our findings revealed altered astrocyte and microglia processes in these circuits in Gnptab-mutant mice, while control regions remained unaffected. Our results shed light on the potential role of glial cells in stuttering pathophysiology and highlight their relevance in modulating vocal production behaviors.

cell biology↗