Background Some previous studies in Caucasian, Asian, and African-american patients have shown that the anti-C1q antibodies and urine levels of MCP-1 (uMCP-1) were significantly greater in patients with LN. However, information in Mestizo and Afro-Latin American patients is very limited.
Objectives Our aim was to evaluate diagnostic value of Anti-C1q and uMCP-1 as a potential markers for the diagnosis of LN in Colombian SLE patients
Methods We examined serum levels of anti-C1q and uMCP-1 in 67 consecutive SLE patients (ACR criteria 1997) from Hospital San Vicente Fundaciόn, at Medellín, Colombia. A fresh urine sample from each patient was collected in a sterile container. Serum Anti-C1q antibodies and uMCP-1 were measured by ELISA techniques (Inova, San Diego, and R&D system, Minneapolis, EEUU, respectively). Several clinical and serological features were analyzed as well as disease activity (SLEDAI). Descriptive statistics were used to describe data. Mann-Whitney tests were used to compare data and Spearman'srho for correlations. Additionally, ROC curves relating the specificity and sensitivity profiles of the 2 biomarkers were done
Results 67 SLE patients were recruited (89% female) with median age of 33.5± 12.0 yrs and median disease duration of 6.76 ± 6.80 years. Mestizo (71%) and Afro-latin American (26%) were majority. Hematologic disease (89%), arthritis (86%), cutaneous involvement (80%), and renal disease (66%) were among most common manifestations. Sixty-three percent of patients were positive for anti-C1q and 56% had elevated levels of uMCP-1 (mean levels 1678 ±3722 pg/ml). Mean SLEDAI score was 10.0 ± 9.0. We found significant association between anti C1q antibodies and several clinical features including serositis, proteinuria, renal and hematological involvement and with several serological markers including anti-dsDNA, low complement and higher SLEDAI score. Patients with LN had higher levels of anti-C1q antibodies than patients without LN (mean levels of 91.3 ± 85.4 vs 31.7 ± 38.7, p value=0.002). uMCP-1 levels were significantly higher in patients with LN than in patients without LN (2399 ± 4566 vs 472 ± 596 pg/ml, p value=0.017) and in patients with proteinuria (2537 ± 4731 vs 553 ± 688, p value=0.025). There was no correlation between anti-C1q levels and uMCP-1. An ROC curve constructed for anti-C1q and uMCP-1 and renal in all SLE patients showed that uNGAL had a good level of sensitivity and specificity with an AUC of 0.74 for anti-C1q and 0.82for uMCP1 (see figure).
Conclusions Although further confirmatory testing is underway, LN patients had almost 3 times and 5 times higher levels of Anti-C1q and uMCP-1, respectively than patients without LN. Anti-C1q antibodies and uMCP-1 may be a good biomarkers for LN in Mestizo and Afro-Latin american SLE patients, and can be a useful marker to identify patients with higher risk of renal involvement
Acknowledgement JA Gόmez-Puerta was supported by Colciencias (conv. 656 de 2014). Anti-C1q antibodies were provided by Inova, Werfen, Colombia
Disclosure of Interest None declared