Neurodevelopmental disorders have been increasingly associated with maternal immune activation (MIA) during pregnancy, particularly in response to viral infections. However, the impact of human respir Show more
Neurodevelopmental disorders have been increasingly associated with maternal immune activation (MIA) during pregnancy, particularly in response to viral infections. However, the impact of human respiratory syncytial virus (hRSV) infection during gestation on offspring neurodevelopment remains poorly understood. This study aimed to characterize hRSV-induced MIA and evaluate its effects on fetal brain development and offspring behavior using a murine model. Pregnant mice were infected with hRSV at gestational day 14, and tissues were analyzed at day 19. Infection induced pulmonary inflammation, evidenced by increased neutrophil infiltration, and viral replication was detected in maternal lungs and placental tissue, but not in fetal organs. Placental infection was associated with increased decidual immune cells and a shift toward a pro-inflammatory cytokine profile, including elevated IL-6, TNF-α, IFN-γ, and IL-1β, along with decreased IL-10 and IFN-λ. Increased levels of IL-6, TNF-α, and IL-4 were also detected in maternal serum and fetal brains, suggesting vertical transfer of cytokines. Additionally, reduced brain-derived neurotrophic factor levels and altered expression of tight junction-related genes were observed in fetal brains. Behavioral analyses revealed that offspring of infected dams exhibited impaired short-term memory and altered anxiety-like and repetitive behaviors, which persisted or intensified with age. These findings demonstrate that maternal hRSV infection induces MIA, disrupts the fetal neuroimmune environment, and leads to long-term behavioral alterations in offspring, highlighting hRSV as a potential risk factor for neurodevelopmental disorders. Show less
Maternal immune activation (MIA) is a key environmental risk factor for neurodevelopmental disorders such as schizophrenia. MicroRNAs are critical regulators of brain development, yet their role in MI Show more
Maternal immune activation (MIA) is a key environmental risk factor for neurodevelopmental disorders such as schizophrenia. MicroRNAs are critical regulators of brain development, yet their role in MIA-induced pathology remains unclear. We found that miR-322-5p was significantly upregulated in the prefrontal cortex of MIA-exposed offspring and directly targeted the 3' untranslated region of brain-derived neurotrophic factor (BDNF), inhibiting its expression. This upregulation impaired BDNF/TrkB/AKT signaling and reduced the synaptic protein PSD95, leading to hypoactivity, cognitive deficits, social impairments, and disrupted sensorimotor gating. Inhibition of miR-322-5p or overexpression of BDNF in the prefrontal cortex restored signaling and reversed both behavioral and molecular abnormalities. These results identify miR-322-5p as a key mediator of MIA-induced neuropathology via repression of BDNF signaling and suggest its potential as a therapeutic target in neurodevelopmental disorders. Show less