C/EBP β/AEP pathway mediates hippocampal mitochondrial damage in a mouse model of sepsis encephalopathy

Septic encephalopathy (SE), a neurocritical complication with alarmingly high mortality rates, represents a major diagnostic and therapeutic challenge in intensive care units (ICUs). Current diagnostic protocols rely predominantly on nonspecific clinical symptom assessment, while conventional laboratory biomarkers exhibit insufficient sensitivity for early detection. This diagnostic ambiguity contributes to delayed interventions and unfavorable patient prognoses. Mechanistically, prior studies in Alzheimer's disease (AD) have established that genetic ablation of C/EBP β or AEP (asparagine endopeptidase) mitigates neuroinflammation and disease progression. Intriguingly, our investigation reveals a pathophysiological paradox in SE: Conditional AEP knockout significantly attenuated sepsis-induced hippocampal damage, whereas C/EBP β knockdown unexpectedly exacerbated neuronal injury — findings directly opposing AD-related mechanisms. Notably, this study identifies mitochondrial dysfunction in hippocampal neurons as a previously unrecognized hallmark of SE, characterized by cristae fragmentation and mitochondrial membrane potential collapse. Multimodal analyses further demonstrate that AEP inhibition rescues synaptic plasticity through dual modulation of STat3 signaling and oxidative stress cascades. Importantly, our paradoxical findings regarding C/EBP β suggest context-dependent regulation of neuroinflammation, challenging the prevailing assumption of pathway conservation across neuropathologies. These translational insights not only elucidate the C/EBP β/AEP axis as a novel therapeutic target in SE but also warrant caution against extrapolating AD-derived mechanisms to sepsis-related encephalopathies.