The BCMA/CD19 Dual Targeted CAR-T Cell in Participants With Autoimmune Kidney Diseases

This study is a single-center, open-label, dose-escalation exploratory clinical trial, expected to enroll 6 to 12 participants. It will use a BOIN (Bayesian Optimal Interval) design for dose escalation, with four predetermined dose groups (0.3×10\^6 cells/kg, 1.0×10\^6 cells/kg, 3.0×10\^6 cells/kg, and an alternative dose of 0.1×10\^6 cells/kg). Each dose group plans to enroll 1-2 or 3-6 participants with relapsed or refractory autoimmune-mediated kidney diseases (such as lupus nephritis, ANCA-associated vasculitis, membranous nephropathy, and IgG4-related diseases).

Inclusion Criteria: 1. Participants must personally sign an informed consent form approved by the Ethics Committee before the start of the study. 2. Participants must be aged ≥18 and ≤65 years. 3. Disease-specific inclusion criteria: Active, relapsing, refractory Lupus Nephritis (LN): LN diagnosed by kidney biopsy within the last 2 years, with pathological types III, IV, or V, and a chronicity index (CI) score≤3 Meets one of the following criteria: Refractory LN, defined as no remission after at least one standard regimen (CTX and/or MMF) for 6 months. Relapsing LN, defined as a need to increase steroid dosage to control disease activity during maintenance treatment. Clinical criteria: eGFR \> 45 ml/min/1.73 m²; urinary protein quantification ≥ 1.5g/24h; SLE-DAI score ≥ 8. ANCA-associated vasculitis (AAV) patients: Diagnosed as AAV according to the 2012 Chapel Hill Consensus Conference criteria, meeting one of the following: Newly diagnosed AAV with renal involvement: Renal involvement must meet both: Kidney biopsy showing pauci-immune necrotizing glomerulonephritis. Urinary red blood cells \>30/high power field. Relapsing or refractory AAV: Relapse: Defined as an increase in BVAS V3.0 score of ≥1 after remission, requiring adjustment of immunosuppressive treatment to regain remission. Refractory: Defined as a) less than 50% reduction in BVAS V3.0 after 6 weeks of standard induction treatment; or b) persistent disease activity (BVAS V3.0 ≥3) after 12 weeks of treatment. Membranous nephropathy (MN) patients: Tissue biopsy diagnosed as aPLA2R-related membranous nephropathy. Clinical criteria for high-risk or relapsing/refractory membranous nephropathy: High-risk patients: Defined as meeting any of the following: eGFR normal, urinary protein \>3.5g/d, ACEI/ARB treatment for 6 months with \