Tripterygium glycoside tablet induces male reproductive toxicity in CIA rats by inhibiting the NELL2-Lumicrine system.

AIMS

Tripterygium glycoside tablet (TGT), a first-line anti-inflammatory drug for rheumatoid arthritis (RA), is severely limited in clinical use by male reproductive toxicity with unclear mechanisms. This study aimed to confirm TGT's anti-RA efficacy, characterize its reproductive toxicity in collagen-induced arthritis (CIA) rats, and elucidate whether the NELL2-Lumicrine system mediates such damage.

MATERIALS AND METHODS

TGT's anti-inflammatory efficacy in CIA rats was evaluated via arthritis scoring, histopathology, and cytokine quantification. Male reproductive toxicity was assessed using sperm analysis, fertilization evaluation, histopathology, and hormone measurement. NELL2-Lumicrine system targets were identified by immunofluorescence and Western blot. Integrated metabolomic and transcriptomic analyses explored TGT's effects on testicular metabolism and gene expression. Molecular docking, dynamics simulation, and cell co-culture experiments verified inhibitory effects of TGT's bioactive components on the NELL2-Lumicrine system.

KEY FINDINGS

TGT alleviated joint swelling, reduced arthritis scores, and decreased serum TNF-α/IL-1β in CIA rats. However, TGT impaired sperm quality and fertilization capacity, increased sperm/embryo abnormalities, and induced testicular-epididymal damage, with hypothalamic-pituitary-gonadal axis hormone dysregulation. Mechanistically, TGT downregulated NELL2 and downstream targets (ROS1, OVCH2, ADAM28, ADAM3), disrupting sperm maturation. Multi-omics revealed TGT disrupted testicular steroid biosynthesis and Fgf signaling linked to the NELL2-Lumicrine system. Computational modeling and in vitro experiments confirmed triptolide and triptonide bind NELL2 strongly, suppressing its signaling pathway.

SIGNIFICANCE

Our data provide the first evidence that TGT induces male reproductive toxicity by inhibiting the NELL2-Lumicrine system, downregulating NELL2 and its downstream targets (ROS1, OVCH2, ADAM28, and ADAM3), which are essential for sperm maturation.