Fu_2025_Cells_14_

Inflammation is essential for host defense but requires strict regulation to prevent immunopathology. This study reveals how pig liver esterase (PLE) in alveolar macrophages (PAMs) modulates PRRSV-induced inflammation through endocannabinoid metabolism. We identified PLE6 as the dominant hydrolytically active subtype in PAMs. Functional studies demonstrated that PLE promotes pro-inflammatory cytokine expression during PRRSV infection, while its substrate 2-arachidonoylglycerol (2-AG) exerts anti-inflammatory effects. Animal experiments confirmed that PLE inhibition reduces pulmonary inflammation and tissue damage in PRRSV-infected piglets. Transcriptomic and mechanistic analyses revealed that PLE hydrolyzes 2-AG to activate the PI3K-Akt-NF-kappaB pathway, particularly through enhanced phosphorylation of Akt and p65. These findings establish a novel pathological mechanism where PLE-mediated 2-AG degradation disrupts endocannabinoid homeostasis, amplifying PRRSV-induced inflammation. The study provides therapeutic insights for targeting endocannabinoid hydrolysis to control inflammatory diseases.