Background/Purpose: Lupus nephritis (LN) may severely affect SLE prognosis and an effective treatment of LN requires correct diagnosis, timely intervention and early treatment of any disease relapse. Biomarkers able to early identify disease relapse are still lacking. The aim of the study was to evaluate if some serum (cystatin C, β2-microglobulin) and urinary (α1-microglobulin and ACR- albumin/creatinine ratio) parameters can be more useful than the conventional parameters in monitoring lupus nephritis and in predicting exacerbations of renal involvement in SLE.

Methods: 73 consecutive SLE patients with renal involvement (active or inactive at baseline) were enrolled. Serum cystatin C and β2-microglobulin, and urinary α1-microglobulin and ACR values were evaluated at baseline (T0) and after 3 (T3) and 6 (T6) months of follow-up, along with routine clinical and laboratory examination. Renal relapse was defined as an arising of 24 hours proteinuria up to 500 mg and/or appearance of active urinary sediment and/or microematuria (>5 red blood cells/hpf).

Results:

Of the 73 LN patients (86.3% female, mean age 38.5±12.0 years, disease duration 13.0±8.8 years), 49 had inactive and 24 active renal disease at baseline. Patients with active nephritis had higher SLEDAI (p<0.01) and 24 hours proteinuria (p<0.01) values, as expected, as well as higher levels of cystatin (1.3±0.8 vs 1.0±0.6 mg/l, p=0.01), α1-microglobulin (22.3±82.2 vs 1.2±4.3 mg/l, p=0.005) and ACR (299.5±432.2 vs 76.7±241.2 mg/g, p<0.01) with respect to patients with inactive LN.

During the follow-up, 11 out of the 49 patients with inactive LN at T0 presented some renal relapse. The 11 patients relapsed during the six-month of follow-up showed at baseline higher values of cystatin C (1.6±0.9 vs 0.9±0.2 mg/l, p=0.001), serum β2-microglobulin (4.0±2.6 vs 2.0±0.8 mg/dl, p=0.001), urinary α1-microglobulin (5.2±8.2 vs 0.0±0.2 mg/l, p<0.01) and ACR (279.9±440.1 vs 6.9±12.0 mg/g, p<0.01), than patients with stable inactive nephritis, while no differences were found in traditional parameters (C3 levels, anti-DNA title and/or positivity, 24 hours proteinuria, SLEDAI, serum creatinine).

Conclusion: This study seems to show that these biomarkers can be integrated to the conventional parameters for predicting lupus nephritis exacerbations.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/biomarkers-in-lupus-nephritis-the-possible-role-of-serum-cystatin-c-serum-2-microglobulin-urinary-i%c2%b11-microglobulin-and-albumina%ef%bf%bdcreatinine-ratio/