This multicenter, open-label, prospective single-arm study will enroll adults (≥18 y) with primary IgA nephropathy confirmed by renal biopsy within 2 weeks, eGFR ≥20 ml/min/1.73 m² and 0.5-3.5 g/d proteinuria, to receive early (real-world) combination therapy with RASI (titrated irbesartan), SGLT2i (dapagliflozin 10 mg qd) and budesonide enteric-coated capsules (16 mg qd) for 9 months, followed by budesonide taper-off and continuation of RASI+SGLT2i for 3 more months (12 months total), with primary endpoint being change in proteinuria from baseline to month 12 and secondary endpoints changes in eGFR and microscopic hematuria.

Inclusion Criteria:

• (1) Age ≥ 18 years (2) Primary IgA nephropathy confirmed by renal-biopsy pathology within the past 2 weeks (3) eGFR ≥ 20 mL/min/1.73 m² (4) 24-hour urinary protein 0.5-3.5 g/day (5) Patient has been fully informed, agrees to receive supportive care plus budesonide enteric-coated capsules, and has signed the informed-consent form

Exclusion Criteria:

• (1) Secondary IgAN attributable to, but not limited to, Henoch-Schönlein purpura, systemic lupus erythematosus, liver cirrhosis, rheumatoid arthritis, or ankylosing spondylitis (2) Previous renal transplantation or current dialysis (3) Co-existing glomerular disease on biopsy (e.g., C3 glomerulopathy, diabetic nephropathy) or nephrotic syndrome (4) Acute, chronic, or latent infection, including hepatitis, tuberculosis, HIV, or chronic urinary-tract infection (5) Type 1 or type 2 diabetes with poor control (HbA1c > 9 %) (6) History of unstable angina, NYHA class III/IV congestive heart failure, or clinically significant arrhythmia (7) Uncontrolled hypertension (systolic ≥ 160 mmHg or diastolic ≥ 90 mmHg) (8) Malignancy diagnosed within the past 5 years (9) Known glaucoma, cataract, or history of cataract surgery (10) Gastro-intestinal disorders that may interfere with drug release or efficacy (peptic-ulcer disease, inflammatory bowel disease, chronic diarrhea) (11) Previous severe adverse reaction to corticosteroids, including psychotic symptoms (12) Concomitant use of potent cytochrome P450 3A4 (CYP3A4) inhibitors (13) Pregnancy, lactation, or unwillingness to use highly effective contraception during treatment and the 3-month follow-up (applies to women of child-bearing potential) (14) Patients whom the investigator deems unsuitable for budesonide enteric-coated-capsule therapy

Age ≥ 18 years，primary IgA nephropathy confirmed by renal-biopsy pathology within the past 2 weeks，eGFR ≥ 20 mL/min/1.73 m²，24-hour urinary protein 0.5-3.5 g/day，patient has been fully informed, agrees to receive supportive care plus budesonide enteric-coated capsules, and has signed the informed-consent form