Endoplasmic reticulum stress inhibitor 4-PBA alleviates immune damage in mice with enteroviral encephalitis by inhibiting ferroptosis

INTRODUCTION: Enterovirus A71 (EV71)-associated encephalitis lacks targeted neuroprotective therapy. Experimental data implicate endoplasmic reticulum (ER) stress and ferroptosis in neuronal injury. We tested whether the chemical chaperone 4-phenylbutyric acid (4-PBA) mitigates EV71 neuropathology by interrupting the ER-stress-ferroptosis axis. MATERIALS AND METHODS: Neonatal mice were infected with EV71 and treated with 4-PBA; survival, body weight, and neurological scores were recorded. Brain injury was assessed by histology (H&E, Nissl, TUNEL) and inflammatory cytokines. ER-stress markers (GRP78, CHOP), ferroptosis indices (GPX4, Fe²⁺, reactive oxygen species, malondialdehyde, superoxide dismutase, glutathione), and viral burden (VP1 mRNA) were quantified. Complementary experiments in EV71-infected HT22 neuronal cells evaluated 4-PBA with or without erastin to probe ferroptosis involvement. RESULTS: 4-PBA improved survival and clinical scores, attenuated neuronal loss, and reduced brain inflammation. Treatment suppressed ER-stress markers, restored GPX4 and antioxidant defences, and lowered Fe²⁺, reactive oxygen species, and malondialdehyde. VP1 mRNA decreased in brain tissue. In HT22 cells, 4-PBA reduced cytotoxicity and lipid-ROS accumulation; erastin abrogated these benefits, supporting a ferroptosis-dependent mechanism. CONCLUSIONS: These data identify an ER-stress-ferroptosis pathway as a driver of EV71 neurotoxicity and demonstrate that repurposed 4-PBA interrupts this cascade to confer functional neuroprotection in vivo and in neuronal cells. To our knowledge, this provides the first in vivo evidence that pharmacologic relief of ER stress can inhibit ferroptosis to ameliorate EV71 encephalitis, highlighting a translational strategy for neurotropic viral disease.