GT719 Injection for Moderate to Severe Refractory Autoimmune Diseases

Inclusion Criteria 1. Voluntarily enrolled in the study, signed an informed consent form, willing and able to comply with the study protocol. 2. Aged 18 to 65 years (inclusive), regardless of gender. 3. The functions of important organs meet the following requirements，excluding those attributable to disease activity: 1. Bone marrow hematopoietic function needs to meet: Neutrophil count ≥1×10\^9/L; Hemoglobin ≥80g/L; Platelets ≥30×10\^9/L; 2. Liver function: ALT≤3×ULN; AST≤3×ULN; TBIL≤1.5×ULN; 3. Renal function: creatinine clearance (CrCl) ≥30 ml/minute; 4. Coagulation function: International standardized ratio (INR) ≤1.5×ULN, prothrombin time (PT) ≤1.5×ULN; 5. Heart function: good hemodynamic stability, with no evidence of moderate or greater pericardial effusion. 4. Women of childbearing age must: 1. During screening, the test result for serum β-human chorionic gonadotropin (β-hCG) was negative; 2. Agree to avoid breastfeeding during the study period until at least one year after the infusion of GT719 cell injection or until two consecutive flow cytometry tests show the absence of GT719 cells (whichever occurs later); 3. Male participants with sexual partners and female participants with potential fertility agree to use highly effective contraceptive methods from screening until at least one year after GT719 cell injection or until two consecutive flow cytometry tests show the absence of GT719 cells (whichever occurs later). Male participants must agree to use condoms during sexual contact with pregnant or fertile women for at least one year after infusion of GT719 cell injection, even after successful vasectomy. Specific inclusion criteria: Systemic lupus erythematosus 1. Complies with the classification standards of the 2019 European Union Against Rheumatology/American Society of Rheumatology (EULAR/ACR) SLE; 2. Disease activity score SELENA SLEDAI≥6 with at least one Injima Lupus Assessment Group Index (BILAG-2004) category A (severe presentation) or two Category B (moderate presentation) organ scores, or both; Or disease activity score SELENA SLEDAI score ≥8; 3. Definition of relapse refractory: conventional treatment remains ineffective for more than 6 months or disease activity occurs again after remission. Conventional treatment is defined as the use of glucocorticoids and cyclophosphamide, and any of the following immunomodulators: antimalarials, azathioprine, mortemycophanate, methotrexate, leflunomide, tacrolimus, cyclosporine, and biologics including rituximab, belimumab and telitacicept. Inflammatory myopathy 1. Inflammatory myopathy fulfilling the 2017 EULAR/ACR classification criteria (including Dermatomyositis (DM), Polymyositis (PM), Anti-Synthetase Syndrome (ASS), and Necrotizing Myopathy (NM)). 2. Positive myositis antibodies; 3. Muscle involvement with Manual Muscle Testing-8 (MMT-8) score less than 142 and at least two abnormalities found among the following five core measurements (Physician Global Assessment (PhGA), Patient Global Assessment (PtGA), or extramuscular disease activity score ≥ 2; Health Assessment Questionnaire (HAQ) total score ≥ 0.25; muscle enzyme levels ≥ 1.5×ULN; or MMT-8 ≥ 142, but with active interstitial lung disease (HRCT showing ground-glass opacities); 4. Definition of relapsed/refractory: Conventional treatment over 6 months remains ineffective, or disease recurrence after remission. Definition of conventional treatment: the use of glucocorticoids and cyclophosphamide, and any one or more of the following immunomodulatory drugs: antimalarials, azathioprine, mycophenolate mofetil, methotrexate, leflunomide, tacrolimus, cyclosporine, and biologics including belimumab, rituximab, and tocilizumab, etc. 5. Definition of progressive: Rapid progression of interstitial lung disease within a short period. Note: Meeting either criterion 4 or 5 is sufficient. Diffuse systemic sclerosis 1. Meet the 2013 ACR classification criteria for systemic sclerosis; 2. Positive antibodies related to systemic sclerosis; 3. Definition of relapse refractory: conventional treatment remains ineffective for more than 6 months or disease activity occurs again after remission. Conventional treatment is defined as the use of glucocorticoids and cyclophosphamide, and any of the following immunomodulators: antimalarials, azathioprine, mortemycophanate, methotrexate, leflunomide, tacrolimus, cyclosporine, and biologics including rituximab, belimumab and telitacicept 4. Definition of progression: rapid skin progression (mRSS increase \>25%); Or progression of lung disease (a 10% reduction in FVC, or a more than 5% reduction in FVC with a 15% reduction in DLCO). Note: Articles 4 and 5 satisfy one or the other. Exclusion Criteria: 1. SLE participants: 1. Drug induced SLE; 2. Patients with lupus crisis or concomitant diseases who require the use of contraindicated drugs according to the protocol are deemed unsuitable for inclusion by the investigator. 2. IIM participants 1. Documented inclusion body myositis (IBM), drug-induced PM or DM, tumor associated PM or DM, non-inflammatory myopathy (such as muscular dystrophy); 2. Uncontrolled extramuscular disease damage related to PM or DM: ILD: FVC\<55% or requiring oxygen therapy; Severe swallowing difficulties, as determined by investigator, increase the risk of patients participating in clinical trials; Severe cardiac manifestations (such as congestive heart failure, arrhythmia, conduction abnormalities requiring treatment, or myocardial infarction) have been determined by investigator to increase the risk of patients participating in clinical trials. 3. SSc participants 1. Moderate to severe pulmonary arterial hypertension (PAH) associated with SSc that cannot be controlled by drug therapy; 2. Rapid progressive SSc related low gastrointestinal (small and large intestine) involvement (requiring parenteral nutrition); Active dilation of gastric antral blood vessel