Evaluation of urinary CD163 level as a biomarker for the diagnosis of lupus nephritis

Aim of the work: to evaluate urinary CD163 as a possible biomarker indicating activity of lupus nephritis (LN). This retrospective, cross-sectional study evaluated 68 patients diagnosed with systemic lupus erythematosus (SLE) over a year, focusing on different states of lupus nephritis (LN). Participants included 38 with active LN, 15 with a history of LN in a non-active phase, and 15 without kidney involvement. The study utilized the SLEDAI index to classify disease activity, with active LN identified through specific urinary parameters. Renal biopsies were performed for those with active disease, following established classification criteria. Comprehensive assessments included blood tests, urinary protein levels, and measurement of urinary sCD163 using ELISA. Statistical analyses employed SPSS, utilizing various tests to compare groups and assess relationships between urinary sCD163 levels and clinical characteristics, establishing significance at p < 0.05. The findings contribute to the understanding of renal manifestations in SLE and the potential role of urinary biomarkers in monitoring disease progression and activity. Laboratory data from 68 participants were analyzed, focusing on correlations among active LN, inactive LN, and SLE without renal involvement. Significant correlations (p < 0.05) were observed in CD163, C3, C4, hemoglobin, platelets, serum creatinine, proteinuria, and BUN, while WBC count, serum albumin, and ESR showed no significant correlation. Notably, 98.5% of patients had positive anti-ds-DNA antibodies. Urinary sCD163 levels were highest in active LN patients. Linear regression showed that serum albumin and ESR significantly predicted urinary sCD163 levels. The optimal cut-off for urinary sCD163 to predict renal activity was > 4.2, with 60.5% sensitivity and 66.7% specificity. However, sCD163 levels did not correlate with renal histopathological classifications. Integration of urinary sCD163 as a biological marker for evaluating the activity of LN together with accurately distinguishing between histopathological classes mostly needs to be further evaluated. To this point of the study, sCD163 can be a good indicator of LN activity, sCD163 still can’t substitute for renal biopsy in differentiation of LN classes as it would not provide the comprehensive understanding necessary for effective management of LN.