Neutrophil Extracellular Traps and Lupus Nephritis

Inclusion criteria for LN group:

1. Adult patients (≥ 18 and > 60 years) of either sex.
2. Fulfill the 2019 EULAR/ACR Classification Criteria for Systemic Lupus Erythematosus (SLE) [11].
3. Diagnosis of active lupus nephritis requiring a renal biopsy as per standard clinical indications (e.g., proteinuria ≥ 0.5 g/24h, active urinary sediment, unexplained rise in serum creatinine).
4. Availability of an adequate renal biopsy specimen for histopathological evaluation according to the International Society of Nephrology/Renal Pathology Society (ISN/RPS) 2018 classification.
5. Patients planned to initiate standard induction therapy (e.g., mycophenolate mofetil or cyclophosphamide with corticosteroids).
6. Provision of written informed consent.

Inclusion Criteria for Control Groups:

1) SLE without nephritis: Patients meeting SLE criteria without any clinical or laboratory evidence of renal involvement (normal urinalysis, proteinuria < 0.3 g/24h, normal serum creatinine).

Exclusion Criteria:

• Participants will be excluded if ANY of the following criteria apply:

  1. Other Kidney Diseases:

     • Presence of, or suspicion of, any other primary or significant secondary kidney disease unrelated to SLE (e.g., diabetic nephropathy, hypertensive nephrosclerosis, IgA nephropathy, significant drug-induced nephrotoxicity, rheumatoid arthritis, positive HBs antigen or HCV antibody).

  2. Confounding Clinical Conditions:

     • Presence of an active or recent major infection (e.g., sepsis, pneumonia, UTI) at the time of enrollment, as infection can significantly alter immune markers.

     • Presence of advanced chronic kidney disease (CKD Stage 4 or 5) predating the diagnosis of SLE.

       3 · Pregnancy or lactation.

  4. Recent use (within the last 3 months) of biologic therapies that may affect neutrophil function or NET formation.

  5. Use of medications known to significantly alter neutrophil activity. 6. History of malignancy.