Mechanism Of Leflunomide Inhibiting DAHPS Activity And Inducing Weight Loss

Leflunomide is an isoxazole immunosuppressant.Its mechanism of action is mainly through inhibiting the activity of tyrosine kinase and dihydroorotate dehydrogenase(DHODH),affecting the pyrimidine synthesis of activated lymphocytes,interfering with cell proliferation,thereby inhibiting lymphocyte-mediated cellular and humoral immune responses.Since its introduction,leflunomide has been widely used in the clinical treatment of rheumatoid arthritis by virtue of its unique immunosuppressive effect.It has also shown positive effects in the treatment of lupus nephritis,systemic vasculitis and transplantation immunity.Leflunomide has unique pharmacokinetic characteristics with a half-life of up to 15 days.The side effects that have been found in clinical trials are mainly diarrhea,nausea,rash,hair loss,elevated liver enzymes,and increased blood pressure.In recent years,clinical data has shown that some patients have experienced significant weight loss after taking leflunomide.This study intends to use metabolomic methods,using mice as animal models,through in vivo and in vitro experiments to explore the adverse effects of leflunomide on patients with weight loss.1.Experimental animals SPF Kunming mice aged 9-10 weeks were selected for experiment.Mice were randomly divided into 4 groups according to body weight,16 in each group,half male and female,4 mice per cage,and male and female were fed in cages.The four groups of mice were divided into a control group and a leflunomide administration group(3 mg / kg / day,10 mg / kg /day,30 mg / kg / day).The drug is administered intragastrically by mixing with 1%CMC to make a suspension.2.The in vitro experiment is to dissolve leflunomide in DMSO in the future,DMSO is used as a control group,and different concentrations of leflunomide(20 μM,50 μM,100 μM,200 μM)are used to treat human normal liver cells.Metabolomic test results showed that leflunomide mainly interfered with the biosynthesis of aromatic amino acids in mice,biotin metabolism(vitamin H),ammonium sulfate metabolism(vitamin B1),taurine and subtaurine metabolism,ascorbic acid Five metabolic pathways including vitamin C metabolism.The results showed that leflunomide inhibited the activity of DAHPS in the intestinal flora of mice(P <0.05).The results of in vitro experiments showed that leflunomide hadproliferative toxicity on human normal liver cells at 20 μM.Leflunomide causes hepatocyte endoplasmic reticulum stress(ERS)at 50 μM.Leflunomide inhibits the activity of DAHPS in the intestinal flora of mice,and induces ERS in human normal hepatocytes to cause liver damage.It may be one of the reasons for leflunomide-induced weight loss adverse reactions.Our results indicate that the influence of leflunomide on human intestinal flora is an important reason for indirectly affecting human body metabolism.