Anti-alpha-actinin Antibodies and Lupus Nephritis Activity

Prior treatment

• Confounding Medications:
  • Receipt of high-dose corticosteroids (\> 20 mg/day of prednisone or equivalent) or any potent immunosuppressive agent (e.g., cyclophosphamide, mycophenolate mofetil, rituximab) within 4 weeks prior to the renal biopsy and blood sampling).

Other illness

• 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).
• 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.
  • Pregnancy or lactation.

Other

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• Participants will be excluded if ANY of the following criteria apply:
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• Inclusion criteria for LN group:
  • Adult patients (≥ 18 and \> 60 years) of either sex.
  • Fulfill the 2019 EULAR/ACR Classification Criteria for Systemic Lupus Erythematosus (SLE).
  • 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).
  • Availability of an adequate renal biopsy specimen for histopathological evaluation according to the International Society of Nephrology/Renal Pathology Society (ISN/RPS) 2018 classification.
  • Renal biopsy performed within 3 months prior to enrollment, and patient has not received induction immunosuppressive therapy (cyclophosphamide, mycophenolate mofetil, or calcineurin inhibitors) in the period between biopsy and enrollment.
  • Provision of written informed consent.
  • b)Inclusion Criteria for Control Groups:
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  • 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).
  • Healthy controls: Age- and sex-matched healthy individuals with no history of autoimmune disease, normal urinalysis, and negative autoantibodies (ANA, anti-dsDNA).