Inclusion Criteria:  Biopsy-proven Class III or IV±V lupus nephritis (ISN/RPS 2003 lupus nephritis classification) with biopsy performed within 48 weeks before inclusion. Males or females aged 18 to 60 years old at the time of screening.  The mild proteinuric flare of lupus nephritis is defined as meeting all of the following criteria :  Persistently increased proteinuria after complete remission, and 24-hr proteinuria≥1.0g/day or doubling of proteinuria after partial remission, and 24-hr proteinuria≥2.0g/day No hypoalbuminemia: serum albumin ≥35g/L Stable renal function: serum creatinine<25% increase above the level at the time of renal disease remission Eligible to sign informed-consent independently  Exclusion Criteria:  Renal disease unrelated to SLE (e.g. diabetes mellitus, other glomerular or tubulointerstitial diseases, renovascular disease), or transplanted kidney Estimate glomerular filtration rate (eGFR by CKD-EPI)<45mL/min per 1.73m^2 at the time of screening Renal biopsy showing cellular of fibrocellular crescent in more than 25% of glomeruli Central nervous system (CNS) or other severe organ manifestations of lupus that necessitate aggressive immunosuppressive therapy on its own. Co-morbidities that require corticosteroid therapy (e.g. asthma, inflammatory bowel disease) Any increased dose of corticosteroids or other immunosuppressive medication including cyclophosphamide, mycophenolate, leflunomide, calcineurin inhibitors, azathioprine, methotrexate, or use of biological agents regardless of duration, with the past six months Hepatitis B virus (HBV) or Hepatitis C virus (HCV) infection history: seropositivity of HBV surface antigen (HBsAg) or HCV antibodies (HCV-Ab) Women who are pregnant or breastfeeding Women with childbearing potential or their male partners, who refuse to use an effective birth control method