AUTHOR=Zhang Yuxian , Qu Xiaoxia , Wang Lishui , Song Lijun 

TITLE=Association of urine autoantibodies with disease activity in systemic lupus erythematosus

JOURNAL=Frontiers in Medicine

VOLUME=11

YEAR=2024

URL=https://www.frontiersin.org/journals/medicine/articles/10.3389/fmed.2024.1346609

DOI=10.3389/fmed.2024.1346609

ISSN=2296-858X

ABSTRACT=<sec id="sec1"><title>Objective</title><p>The presence of urinary autoantibodies in patients with systemic lupus erythematosus (SLE) has been confirmed by several studies; however, the significance of their presence in urine remains unclear. This study aims to further investigate the association between urine autoantibodies and disease activity as well as organ involvement in SLE.</p></sec><sec id="sec2"><title>Methods</title><p>This cross-sectional study included 89 SLE patients. Data collected included anti-nuclear antibody (ANA), anti-ENA antibodies, and anti-dsDNA antibody levels in both serum and urine, complement (C) 3, C4 levels in serum, SLE disease activity index-2000 (SLEDAI-2000), renal domains of SLEDAI (RSLEDAI) and non-renal SLEDAI (NRSLEDAI).</p></sec><sec id="sec3"><title>Results</title><p>The rate of positive urine ANA (uANA) was 33.3% (29/87) among the enrolled patients. Compared to the uANA negative group, the positive group exhibited significantly higher SLEDAI-2000 scores (7.85 ± 5.88 vs. 18.69 ± 6.93, <italic>p</italic> &lt; 0.001), RSLEDAI scores [0 (0, 4.0) vs. 12.0 (8.0, 16.0), <italic>p</italic> &lt; 0.001], and NRSLEDAI [4 (2.0, 8.0) vs. 6.0 (4.0, 9.5), <italic>p</italic> = 0.038]. Patients with positive urine anti-Sm antibody demonstrated significantly elevated SLEDAI-2000 scores compared to those who were negative (25.0 ± 8.80 vs. 10.09 ± 6.63, <italic>p</italic> &lt; 0.001). Similarly, they also had higher RSLEDAI [16.0 (12.0, 16.0) vs. 4.0 (0, 8.0), <italic>p</italic> &lt; 0.001] and NRSLEDAI [9.5 (6.0, 13.5) vs. 4.0 (3.0, 8.0), <italic>p</italic> = 0.012], as well as a greater prevalence of renal involvement compared to their negative counterparts (100% vs. 58.2, <italic>p</italic> = 0.022). There was a positive correlation between uANA titer and both SLEDAI-2000 (<italic>r<sub>s</sub></italic> = 0.663, <italic>p</italic> &lt; 0.001) and RSLEDAI (<italic>r<sub>s</sub></italic> = 0.662, <italic>p</italic> &lt; 0.001). The serum anti-dsDNA antibody level did not exhibit a significant correlation with RSLEDAI (<italic>r<sub>s</sub></italic> = 0.143, <italic>p</italic> = 0.182). Conversely, the urine anti-dsDNA antibody level demonstrated a significant positive correlation with RSLEDAI (<italic>r<sub>s</sub></italic> = 0.529, <italic>p</italic> &lt; 0.001).</p></sec><sec id="sec4"><title>Conclusion</title><p>Urine ANA is associated with both global SLEDAI and RSLEDAI scores. Urine anti-Sm antibody is associated with an increased incidence of renal involvement in SLE. The urine anti-dsDNA antibody level, rather than the serum anti-dsDNA antibody level, exhibits a significant association with RSLEDAI in SLE.</p></sec>