Study to Evaluate the Safety and Preliminary Efficacy of CD19 CAR-T Cell Therapy (TranspoCART19) in Patients With Refractory Lupus Nephritis

The goal of this clinical trial is to evaluate the safety and preliminary efficacy of CD19 CAR-T cell therapy (TranspoCART19) in adults with refractory lupus nephritis. Lupus nephritis is a serious kidney complication of systemic lupus erythematosus that may not respond adequately to standard treatments. The main questions this study aims to answer are: * Is TranspoCART19 safe and tolerable in patients with refractory lupus nephritis? * Can TranspoCART19 induce complete or partial clinical and immunological remission? Participants will: * Undergo leukapheresis to collect immune cells for manufacturing TranspoCART19. * Receive lymphodepleting chemotherapy before treatment. * Receive a single fractionated infusion of TranspoCART19. * Attend regular follow-up visits for safety, disease activity, kidney function, immune response, and quality-of-life assessments for up to 24 months, with long-term safety follow-up after study completion.