Effects of Telitacicept vs Cyclophosphamide on Lupus Related Interstitial Lung Disease

Inclusion Criteria: * Meet the 2019 EULAR/ACR classification criteria for systemic lupus erythematosus; * Male or non-pregnant female aged ≥ 18 years; * Diagnosis by high-resolution lung CT (HRCT) is clearly consistent with interstitial lung disease (ILD); * FEV1/FVC%≥60% and diffusion function DLCO (measured value/estimated value) ≥40%; * Patients voluntarily participate in this trial, have good compliance, and have the ability to understand and sign informed consent before the study. Exclusion Criteria: * Alanine aminotransferase and/or aspartate aminotransferase (ALT/AST) \> 5 times the upper limit of normal; * severe chronic kidney disease (stage IV) or need for dialysis (estimated glomerular filtration rate (eGFR) \< 30ml/min/1.73m2); * Hemoglobin \< 80 g/L; * WBC \< 2.0×10\^9; * Platelet \< 50×10\^9; * Is pregnant or breastfeeding; * Expected transfer to another hospital in a non-study site within 4 weeks (possibility of loss to follow-up); * Life expectancy does not exceed 24 weeks; * Have a history of severe allergies; * Patients with other serious lung diseases or other clinically significant serious abnormalities in the lungs; * Are using antitumor drugs, other immunosuppressants or immunomodulatory therapies; * Significant pulmonary hypertension; * Previous clinical or echocardiographic evidence of significant right heart failure; 1. Right heart catheterization showing cardiac index ≤ 2 L/min/m2; 2. Pulmonary hypertension requiring treatment with epoprostenol/traprostacyclin. * Patients with severe cardiovascular disease: 1. myocardial infarction within 6 months; 2. Unstable angina within 6 months. * Risk of bleeding, any of the criteria listed below: 1. known genetic predisposition to bleeding; 2. Patients who require the following treatments: i. Fibrinolytic therapy, full-dose therapeutic anticoagulation (e.g., vitamin K antagonists, direct thrombin inhibitors, heparin, hirudin); ii. High-dose antiplatelet therapy. \[Note: Prophylactic low-dose heparin or heparin flush solution (e.g., enoxaparin, 4000 I.U. S.C. per day) required for maintenance of indwelling intravenous access devices is not prohibited.) and prophylactic antiplatelet therapy (e.g., acetylsalicylic acid up to 325 mg/day, or clopidogrel at a dose of 75 mg/day, or other antiplatelet therapy at the same dose). * History of hemorrhagic central nervous system (CNS) events within 12 months; * Any of the following conditions within a period of 3 months: 1. hemoptysis or hematuria; 2. Active gastrointestinal bleeding or gastrointestinal ulcers; * Have previously undergone hematopoietic stem cell transplantation (HSCT), or plan to receive HSCT in the following year, or plan to undergo major surgery. * Women who are pregnant, breastfeeding or planning to become pregnant during the test; * 28 days before administration or 3 months after administration, women of childbearing age are unwilling or unable to use highly effective contraceptive methods; * According to the investigator's point of view, the patient has alcohol or drug abuse; * History of dysphagia or any gastrointestinal disease that affects drug * Patients with contraindications to the use of tatacept; * Subjects deemed unsuitable for participation in the study by the investigator.