Paternal immune activation-induced alteration of 28S rRNA-derived small RNAs in sperm reprograms offspring phenotypes.

Parental environmental exposures can induce transgenerational effects through epigenetic modifications in germ cells. Although paternal immune activation is implicated in transgenerational metabolic and neuropsychiatric disorders, the germline-encoded molecular vectors mediating this inheritance remain poorly understood. Here, we demonstrated that lipopolysaccharide-induced immune activation dynamically upregulated the abundance of 28S ribosomal RNA-derived small RNAs (28S-rsRNAs) in mouse sperm in a time-dependent manner. Furthermore, epididymal sperm maturation exhibited heightened susceptibility to acute immune perturbations compared with spermatogenic processes, and 28S-rsRNAs were selectively incorporated during their transit through the caput epididymis. Strikingly, zygotic microinjection of synthetic 28S-rsRNAs recapitulated paternal immune activation phenotypes, resulting in offspring exhibiting metabolic syndrome-like phenotypes, including obesity and impaired insulin sensitivity. Concurrently, these manipulated offspring displayed neurobehavioral abnormalities characterized by heightened anxiety-like and aggressive behaviors, accompanied by hippocampal transcriptomic alterations. Taken together, our findings demonstrate that sperm 28S-rsRNAs contribute to paternal immune activation-mediated programming of offspring behavioral and metabolic phenotypes and provide mechanistic insights into environment-germline interactions.