Treatment of lupus nephritis

The potential use of serum interleukin-21 as biomarker for lupus nephritis activity compared to cytokines of the tumor necrosis factor (TNF) family

OBJECTIVE

Lupus nephritis (LN) is a significant consequence of systemic lupus erythematosus (SLE). To the best of our knowledge, this is the first work that focuses on evaluation of serum interleukin (IL-) 21 as a diagnostic biomarker of LN activity, compared to B lymphocyte stimulator (BlyS), tumor necrosis factor ligand superfamily member 13 (TNF-SF13), and traditional techniques of active LN attempting to compare their diagnostic usefulness.

METHODS

Serum levels of IL-21, BlyS, and TNF-SF13 during LN were investigated. Twenty-five biopsy-proven, active LN female patients and 15 SLE patients without active LN and 20 healthy controls (HCs) joined this work.

RESULTS

Serum IL-21 level was significantly higher in active LN group than in inactive LN group. Correlation analysis showed that serum IL-21 levels were significantly correlated with total SLEDAI (r = 0.41, p = 0.03), renal-SLEDAI (r = 0.48, p = 0.04), renal activity index (AI) (r = 0.93; p < 0.001), and 24-h proteinuria (r = 0.51; p > 0.008). Receiver operating characteristic curve (ROC) revealed the ability of serum IL-21 to discriminate between active and inactive LN with 70% sensitivity at >240 pg/ml cutoff point (AUC 0.809).

CONCLUSION

For Egyptian SLE patients, serum levels of IL-21 were superior to TNF-SF13 and BlyS and correlated significantly with the activity indexes of LN, indicating a promising role as a potential biomarker of active LN.

Expression of BAFF, APRIL, and cognate receptor genes in lupus nephritis and potential use as urinary biomarkers

BACKGROUND

B-cell activating factor (BAFF), a proliferation-inducing ligand (APRIL), and their receptors BAFF-R, BCMA, and TACI are crucial factors for the survival of B lymphocytes. Recent evidence has also demonstrated the importance of BAFF/APRIL signaling in lupus nephritis (LN). This study evaluated the relationships between LN clinical characteristics and the urinary expression levels of BAFF, APRIL, and cognate receptors to assess their potential value as disease biomarkers.

METHODS

Expression levels of these genes were assessed in urine samples collected from systemic lupus erythematosus (SLE) patients before renal biopsy using reverse transcription real-time PCR.

RESULTS

Thirty-five patients with LN were included. Most of the patients were female (82.86%) with median Systemic Lupus Erythematosus Disease Activity Index 2000 (SLEDAI-2K) of 15. BAFF mRNA was detectable in 28.57%, APRIL mRNA in 42.85%, BR3 mRNA in 48.57%, and TACI mRNA in 42.85% of urine samples. On the other hand, urinary (u)BCMA mRNA was not found in any sample. Urinary expression of most biomarkers was detected with greater frequency in class III and IV LN compared to class V LN. The expression level of uBR3 mRNA was correlated with SLEDAI-2K and histological activity index.

CONCLUSION

Urinary expression of BAFF/APRIL signaling factors, especially TACI, APRIL, and BR3 mRNAs, may be useful biomarkers for LN.