Toxic effects of Tripterygium glycoside tablets on the reproductive system of male rats by metabolomics, cytotoxicity, and molecular docking

Background: Tripterygium glycoside tablets (TGT) is the most common preparation from Tripterygium wilfordii Hook F, which is widely used in clinical for treating rheumatoid arthritis (RA) and other autoimmune diseases. However, its serious reproductive toxicity limits its application. Purpose: This study aimed to elucidate the toxic effects of TGT on the reproductive system of male RA rats and its potential toxic components and mechanism. Methods: Collagen-induced arthritis (CIA) rat model was established, and TGT suspension was given at low, medium, and high doses. Gonadal index, pathological changes, and the number of spermatogenic cells were used to evaluate the toxic effects of TGT on the reproductive system. Non-targeted metabolomics of testicular tissue was conducted by UHPLC-QTOF/MS. Combined with network toxicology, the key targets of TGT-induced reproductive toxicity were screened and RT-qPCR was used to validation. In vitro toxicity of 19 components of TGT was evaluated using TM3 and TM4 cell lines. Molecular docking was used to predict the interaction between toxic components and key targets. Results: TGT reduced testicular and epididymis weight. Pathology analysis showed a lot of deformed and atrophic spermatogenic tubules. The number of spermatogenic cells decreased significantly (P<0.0001). A total of 58 different metabolites including platelet-activating factor (PAF), lysophosphatidylcholine (Lyso PC), phosphatidylinositol (PI), glutathione (GSH), and adenosine monophosphate (AMP) were identified by testicular metabolomics. Glycerophospholipid metabolism, ether lipid metabolism, and glutathione metabolism were key pathways responsible for the reproductive toxicity of TGT. Ten key reproductive toxicity targets were screened by network toxicology. The cytotoxicity test showed that triptolide, triptonide, celastrol, and demethylzeylasteral could significantly reduce the viability of TM3 and TM4 cells. Alkaloids had no apparent toxic effects. Molecular docking showed that the four toxic components had a good affinity with 10 key targets. All binding energies were less than -7 kcal/mol. The RT-qPCR results showed the Cyp19a1 level was significantly up-regulated. Pik3ca and Pik3cg levels were significantly down-regulated. Conclusion: Through testicular metabolomics, we found that TGT may cause reproductive toxicity through CYP19A1, PIK3CA, and PIK3CG three target, which was preliminarily revealed. This study laid the foundation for elucidating the toxicity mechanism of TGT and evaluating its safety and quality.