Molecular Biomarkers for Discriminating Lupus Nephritis in SLE

Lupus nephritis (LN) is a major cause of renal morbidity in systemic lupus erythematosus (SLE). Conventional clinical, renal, and serological parameters may not fully distinguish patients with renal involvement from those with SLE without LN. This cross-sectional observational study aims to evaluate a predefined panel of eight molecular biomarkers and determine their ability to discriminate between patients with established SLE with and without LN. The panel includes the non-coding RNA markers MALAT1, GAS5, miR-155, and miR-223; the inflammatory biomarkers interferon-beta (IFN-β), lipocalin-2 (LCN2), and interleukin-23 (IL-23); and the tissue-remodeling biomarker matrix metalloproteinase-9 (MMP-9). The study will also assess associations between these biomarkers and conventional clinical and laboratory parameters, disease activity, cumulative organ damage, and available renal histopathological findings. The discriminatory performance of conventional clinical assessment, the molecular biomarker panel, and their integrated combination will be evaluated.

Inclusion Criteria: * Adults aged 18 years or older. * Patients with an established diagnosis of systemic lupus erythematosus (SLE), according to the diagnostic/classification criteria adopted by the treating clinicians and documented in the medical records. * Patients classified into either of the following groups: SLE with established lupus nephritis (LN). SLE without evidence of lupus nephritis. * Availability of clinical and laboratory data sufficient for characterization of SLE disease status and renal involvement. * Availability of blood samples suitable for the planned molecular biomarker assessment. Exclusion Criteria: * Patients with an uncertain or undocumented diagnosis of SLE. * Patients with an unclear renal status that prevents reliable classification into the LN or non-LN group. * Patients with another active autoimmune or systemic inflammatory disease that could substantially interfere with interpretation of the investigated biomarkers. * Patients with an active infection at the time of sample collection. * Patients with a concurrent malignancy or another major condition likely to substantially affect the measured inflammatory or molecular biomarkers. * Patients with insufficient clinical information or inadequate biological samples for the planned analyses.