Tripterygium Wilfordii Plus Prednisone for Active IgG4-Related Disease

The goal of this clinical trial is to learn if tripterygium wilfordii added to prednisone can treat active IgG4-related disease (IgG4-RD) in adults 45 to 80 years of age. Women in the study must be postmenopausal. The main questions it aims to answer are: * Does adding tripterygium wilfordii to prednisone lower the chance that IgG4-RD comes back at 12 months compared with prednisone alone? * Does the combination improve remission, disease activity scores, blood tests, quality of life, and remain acceptably safe? Researchers will compare prednisone alone to prednisone plus tripterygium glycoside tablets to see if the combination reduces relapse. Participants will: * Be assigned by chance to prednisone alone or prednisone plus tripterygium glycoside tablets 20 mg three times a day * Start prednisone at 0.6 to 0.8 mg/kg per day and taper it off within 6 months * Attend clinic visits at the start of the study and at 1, 3, 6, 9, and 12 months for exams, blood tests, disease scores, and imaging when needed * Report symptoms and any side effects during the 12-month follow-up