NAMO biosynthesis mediates low-dose aspirin protection against preeclampsia by inhibiting TLR4/NF-κB signaling

Description

Abstract

Preeclampsia (PE) is a life-threatening hypertensive disorder of pregnancy originating from placental dysfunction, yet therapeutic options remain limited. Low-dose aspirin (LDA) is the primary prophylactic agent for PE, but its protective mechanisms beyond cyclooxygenase inhibition are not fully elucidated. This study aimed to uncover novel pharmacological pathways for LDA's action directly within the placenta, the central organ of PE pathophysiology. Using a placental-focused metabolomics approach in an L-NAME-induced mouse model of PE, we discovered that LDA's therapeutic effects were not associated with the accumulation of its primary metabolite, salicylic acid. Instead, LDA significantly remodeled placental nicotinamide (NAM) metabolism, leading to a selective increase in the biosynthesis of Nicotinamide N-oxide (NAMO). This increase was attributed to a specific enhancement of CYP2E1 catalytic activity by LDA, not an alteration in its expression. Exogenous administration of NAMO recapitulated the protective effects of aspirin, ameliorating hypertension, proteinuria, and fetal growth restriction in PE mice. Mechanistically, RNA-sequencing and subsequent validation identified the TLR4/NF-κB signaling pathway as the primary target of NAMO. A comprehensive suite of biophysical and cellular assays, including molecular docking, SPR, CETSA, and DARTS, revealed that NAMO directly binds to TLR4, inhibiting its dimerization and subsequent activation of the NF-κB cascade. These findings unveil the 'Aspirin-NAMO-TLR4' axis as a novel, non-canonical mechanism for aspirin's therapeutic action, establishing NAMO as an endogenous anti-inflammatory regulator and a promising new therapeutic candidate for PE.