Background/Purpose: Approximately 30% of patients with adult-onset systemic lupus erythematosus (SLE) develop lupus nephritis (LN). Presence and/or severity of LN are currently assessed by renal biopsy, but biomarkers in serum or urine samples may provide an avenue for non-invasive routine testing.

Methods: 197 SLE patients and 48 healthy controls were recruited, and urine samples collected. 75 of the SLE patients had active LN and 104 had no or inactive renal disease. Concentrations of lipocalin-like prostaglandin D synthase (LPGDS), transferrin, alpha-1-acid glycoprotein (AGP-1), ceruloplasmin, monocyte chemoattractant protein 1 (MCP-1) and soluble vascular cell adhesion molecule-1 (sVCAM-1) were quantified by MILLIPLEX® Multiplex Assays using the MAGPIX Luminex xMAP platform. Binary logistic regression was conducted to examine whether proteins levels associate with active renal involvement and/or response to rituximab treatment.

Results: Urine levels of transferrin (p< 0.005), AGP-1 (p< 0.0001), MCP-1 (p< 0.001) and sVCAM-1 (p< 0.005) were significantly higher in SLE patients when compared to healthy controls. Furthermore, levels of transferrin, AGP-1, ceruloplasmin, MCP-1 and sVCAM-1 (all p< 0.0001) were significantly higher in SLE patients with active LN when compared to patients without active LN. A combination of five urine proteins, namely LPGDS, transferrin, ceruloplasmin, MCP-1 and sVCAM-1 was a good predictor of active LN (AUC 0.898). A combined model of LPGDS, transferrin, AGP-1, ceruloplasmin, MCP-1 and sVCAM-1 predicted response to rituximab treatment at 12 months (AUC 0.818).

Conclusion: Findings support the use of a urinary protein panel to identify active LN and potentially predict response to treatment with rituximab in adult SLE patients. Prospective studies are required to confirm findings.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/a-panel-of-urinary-proteins-predicts-active-lupus-nephritis-and-response-to-rituximab-treatment/