Serum MPO-DNA Complexes as a Biomarker of Disease Activity in Systemic Lupus Erythematosus

Serum Myeloperoxidase-DNA Complexes as a Novel Biomarker of Neutrophil Extracellular Trap and Disease Activity in Systemic Lupus Erythematosus

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease characterized by immune system dysregulation and inflammation affecting multiple organs. A key mechanism in its development involves the excessive formation and impaired clearance of neutrophil extracellular traps (NETs), which release myeloperoxidase-DNA (MPO-DNA) complexes into the circulation. Although standard laboratory markers like complement proteins (C3, C4) and anti-dsDNA antibodies are routinely used, they often show inconsistent sensitivity in monitoring disease activity and flare-ups.

The primary purpose of this observational study is to evaluate serum MPO-DNA complexes as a circulating biomarker of NET formation in patients with systemic lupus erythematosus.

The study aims to:

• Measure serum MPO-DNA complex levels in active SLE patients compared to age- and sex-matched inactive SLE controls.
• Assess the correlation between MPO-DNA complex levels and clinical disease activity measured by the SLE Disease Activity Index 2000 (SLEDAI-2K) score.
• Evaluate the diagnostic accuracy of MPO-DNA complexes compared to conventional inflammatory and immunological markers (ESR, CRP, C3, C4, and anti-dsDNA).

Participants will undergo routine clinical assessments and standard blood sampling to measure routine laboratory parameters and circulating MPO-DNA complex levels via enzyme-linked immunosorbent assay (ELISA).

Inclusion Criteria:

• Diagnosis of systemic lupus erythematosus (SLE) according to the 2019 European Alliance of Associations for Rheumatology/American College of Rheumatology (EULAR/ACR) classification criteria.
• Age older than 16 years.
• Provision of written informed consent prior to study enrollment.

Exclusion Criteria:

• Age 16 years or younger.
• Overlapping autoimmune diseases (e.g., rheumatoid arthritis, systemic sclerosis, mixed connective tissue disease).
• Concurrent active severe infections.
• Malignancy.
• Pregnancy.