Exploratory Multiomics Profiling Reveals ACTN4‐Centric Cytoskeletal Failure and Environmental Arsenic Association in Morphologically Defined Oligoasthenoteratospermia Subtypes

Background Oligoasthenoteratospermia (OAT) represents a major cause of male infertility. The molecular mechanisms underlying sperm morphological defects, particularly their potential interplay with environmental exposure‐associated molecular alterations, remain poorly understood and warrant exploratory investigation. Methods Semen and plasma samples were collected from normal controls (NC, n = 6), mild morphological defect (MMD, n = 6), and severe morphological defect (SMD, n = 6) subjects in this exploratory pilot study designed to detect large‐effect signals. Integrated proteometabolomic profiling was performed using 4D proteomics and LC–MS. Bioinformatic analysis focused on screening differential expression, functional enrichment, exploring potential interactions between exposure‐associated metabolites and proteins, and identifying coherent patterns to potentially differentiate groups. Results Comparative analysis identified biphasic dysregulation patterns in key cytoskeletal proteins. The prominent hub ACTN4 exhibited depletion in MMD sperm while displaying pathological spatial dislocation with 83% showing midpiece signal loss and fragmented tail fluorescence, accompanied by extracellular vesicle release in SMD sperm. Quantitative immunofluorescence validation confirmed these divergent phenotypes, that is a 56% systemic reduction in MMD compared to controls ( p < 0.0001), with SMD sperm also showing 41% absolute depletion versus NC ( p < 0.0001) despite proteomic upregulation, which indicates functional loss through vesicular shedding. Plasma metabolomics revealed distinct profiles between severity groups, quantifying 357 differentially abundant metabolites (including prioritized selenometabolite‐bile acid interactions) between SMD and MMD. Exploratory correlation analysis prioritized inverse associations including arsenocholine (an established environmental arsenic exposure biomarker) and ACTN4 ( ρ = −0.867, p = 0.0025), glycodeoxycholic acid versus PPP1CC ( ρ = −0.917, p < 0.001), and Se‐adenosylselenomethionine‐PGK1 ( ρ = −0.867, p = 0.0025), reflecting ultrastructural damage patterns. Conclusion This severity‐stratified analysis demonstrates that sperm morphological defects in OAT associate with compartment‐specific ACTN4 depletion patterns, that is quantitative loss systemically impairing head‐tail coupling in MMD versus spatial dislocation with pathological vesiculation causing functional nullification in SMD. The exploratory findings suggest potential associations with multisystem exposure effects, particularly indicated by the arsenocholine‐ACTN4 correlation, though causal relationships cannot be established from this observational study. In addition, exposure‐protein associations involving PPP1CC and PGK1 also support the hypothesis of environmental perturbation affecting sperm integrity, though these observations require validation in independent cohorts.