Background/Purpose:  Some previous studies in Caucasian, Asian, and African-american patients have shown promising results for several urinary biomarkers in patients with lupus nephritis (LN). However, information regarding urinary biomarkers in Mestizo and Afro-Latin American patients is very limited. We investigated whether levels of urinary of monocyte chemoattractant protein 1 (MCP-1), neutrophil gelatinase-associated lipocalin (NGAL), ceruloplasmin (CP), transferrin (TP) and TWEAK are good biomarkers to differentiate patients with LN among Latin American SLE patients.

Methods:  SLE patients meeting the revised ACR classification criteria for SLE were recruited from a referral University Hospital. Urinary levels of MCP-1, NGAL, CP, TF and TWEAK were measured using a commercial ELISA kits, R&D system, Minneapolis, USA for MCP-1, NGAL and TWEAK and Assaypro, Missouri, USA for CP and TF. Serum Anti C1q antibodies were measured by ELISA (Inova, San Diego, USA). SLE activity was measured with SLEDAI. Pearson or Spearman’s rank correlations were used to examine associations between continuous variables. Additionally, ROC curves were done.

Results:  100 SLE patients were recruited (87% female) with median age of 33.4 ± 12.4 years and median disease duration of 7.6 ± 7.3 years. Mestizo (75%) and Afro-Latin American (22%) were majority. Mean SLEDAI score was 8.8 ± 9.0 and mean SLICC was 0.3 ± 0.6. Afro-Latin American had significantly higher prevalence of LN and serositis, and higher SLEDAI scores than Mestizo patients. All urinary biomarkers and anti C1q antibodies were significantly higher in patients with LN than in patients without LN. Additionally, NGAL, CP, TF and TWEAK were significantly higher in patients with active LN than in inactive LN (Table). NGAL levels were significantly higher in Afro-latin American patients (56 ± 56 vs 35 ± 46 pg/ml, p=0.04). No significant differences were found in urinary biomarkers levels among proliferative and non-proliferative forms of LN. We found significant positive correlation between all urinary markers and SLEDAI (r score ranging from 0.31-0.51, p<0.05 for all). A ROC curve for urinary biomarkers for LN in all SLE patients showed a good level of sensitivity and specificity for all, especially for CP (AUC 0.87), TF (AUC 0.84) and TWEAK (AUC 0.78).

Conclusion:  In our cohort, Afro-Latin American were more severely affected with higher disease activity and more LN. We found several urinary biomarkers with good discriminative power to differentiate LN in Latin American SLE patients. Those markers were moderate correlated with disease activitiy. NGAL, CP, TF and TWEAK were significantly higher in patients with active LN.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/a-panel-of-urinary-biomarkers-to-assess-renal-involvement-in-latin-american-patients-with-systemic-lupus-erythematosus/