An Exploratory Clinical Study of YTS109 Cell for R/R Autoimmune Diseases

Inclusion Criteria: * Subjects must meet both the following common inclusion criteria and disease-specific inclusion criteria simultaneously to be eligible for participation in this study: Common inclusion criteria: 1. Age ranges from 18 to 65 years old (including threshold), regardless of gender. 2. Essential Organ Function Criteria: <!-- --> 1. Bone marrow: Neutrophils ≥1×10\^9/L (within 2 weeks, excluding granulocyte colony-stimulating factor use); Hemoglobin ≥60 g/L. 2. Liver: ALT/AST ≤3×ULN (disease-related elevations permitted). TBIL≤1.5×ULN (disease-related elevations permitted). 3. Renal: CrCl≥30mL/min (Cockcroft-Gault formula, excluding acute declines). 4. Coagulation: INR/PT ≤1.5×ULN. 5. Cardiovascular: Hemodynamic stability. 3. Fertile females or males with partners of childbearing age must use medically approved contraception or abstain during and ≥12 months post- treatment. Negative serum HCG test (within 7 days pre-enrollment) for fertile females; non-lactating. 4\. Voluntary participation with signed informed consent and compliance. Specific inclusion criteria: Relapsing and refractory systemic lupus erythematosus: 1. Meeting the 2019 European League Against Rheumatism/American College of Rheumatology (EULAR/ACR) classification criteria for systemic lupus erythematosus (SLE); 2. Meeting the criteria for refractory lupus nephritis (LN) or SLE-associated immune thrombocytopenia (SLE-ITP), defined as follows: <!-- --> 1. Refractory Lupus Nephritis: 1. Failure to achieve remission following treatment regimens comprising glucocorticoids and at least two immunosuppressive agents (including cyclophosphamide \[CTX\], tacrolimus, mycophenolate mofetil \[MMF\], and cyclosporine) and/or biologic agents (including rituximab, belimumab, telitacicept, etc.). 2. Urine protein-to-creatinine ratio (UPCR) ≥1.0 g/g or 24-hour urine protein excretion \>1.0 g at screening. 3. Renal pathology must be performed within 6 months prior to the screening visit or during the screening period, demonstrating proliferative lupus nephritis (Class III or IV, with or without Class V) according to the 2003 International Society of Nephrology/Renal Pathology Society (ISN/RPS) criteria, with ≤50% glomerular sclerosis noted in the pathology report. 2. Refractory SLE-Associated Immune Thrombocytopenia: 1. Failure to achieve partial remission after at least one course of methylprednisolone pulse therapy (0.5-1 g × 3-5 days) or high-dose glucocorticoids (equivalent to 1 mg/kg/day of prednisone) combined with one or more immunosuppressive agents (including biologic agents) for at least 3 months, or inability to maintain therapeutic efficacy during glucocorticoid tapering. Platelet count \<50 × 10⁹/L on at least two consecutive complete blood count tests prior to enrollment. Exclusion of thrombocytopenia due to non-SLE causes, such as infection, bone marrow suppression, or hypersplenism. Relapsing and refractory Sjögren's syndrome: 1. Meeting the 2002 American-European Consensus Group (AECG) criteria or the 2016 American College of Rheumatology/European League Against Rheumatism (ACR/EULAR) classification criteria for primary Sjögren's syndrome; 2. Having a disease activity score of EULAR Sjögren's Syndrome Disease Activity Index (ESSDAI) ≥ 6; 3. Testing positive for anti-SSA/Ro antibodies; 4. Definition of relapsing and refractory condition: Persistence of disease activity or recurrence of disease activity after remission, despite undergoing conventional treatment for more than six months. Definition of conventional treatment: Administration of glucocorticoids in combination with any of the following immunosuppressive agents or biological agents: cyclophosphamide, azathioprine, mycophenolate mofetil, methotrexate, leflunomide, tacrolimus, cyclosporine, as well as biological agents including rituximab, belimumab, telitacicept, etc. Relapsing and refractory Sjogren's Syndrome: <!-- --> 1. Meeting the 2013 American College of Rheumatology (ACR) classification criteria for systemic sclerosis; 2. Testing positive for systemic sclerosis-related antibodies; 3. Presenting with diffuse cutaneous sclerosis or active interstitial lung disease (as indicated by ground-glass opacities on high-resolution computed tomography, HRCT); 4. Definition of relapsing and refractory condition: Persistence of disease activity or recurrence of disease activity after remission, despite undergoing conventional treatment for more than six months. Definition of conventional treatment: Administration of glucocorticoids and cyclophosphamide, in combination with any one or more of the following immunomodulatory agents: antimalarial drugs, azathioprine, mycophenolate mofetil, methotrexate, leflunomide, tacrolimus, cyclosporine, as well as biological agents including rituximab, belimumab, telitacicept, etc.; 5. Definition of progressive condition: Demonstrating rapid skin progression (an increase in modified Rodnan skin score, mRSS, of \>25%) or pulmonary disease progression (a 10% decrease in forced vital capacity, FVC, or a \>5% decrease in FVC accompanied by a 15% decrease in diffusion capacity for carbon monoxide, DLCO). Note: Meeting either criterion 4 or 5 is sufficient. Relapsing and refractory Inflammatory Myopathy: 1. Meeting the 2017 European League Against Rheumatism/American College of Rheumatology (EULAR/ACR) classification criteria for inflammatory myopathies (including dermatomyositis, DM; polymyositis, PM; antisynthetase syndrome, ASS; and necrotizing myopathy, NM); 2. Testing positive for myositis-specific antibodies; 3. For patients with muscle involvement, having a Manual Muscle Testing-8 (MMT-8) score below 142 and at least two abnormal findings among the following five core measures (Physician's Global Assessment, PhGA; Patient's Global Assessment, PtGA, or extra-muscular disease activity score ≥