Potential biomarkers present in the urine of patients with systemic lupus erythematosus: An exploratory study in Colombian patients

Objective: To describe the urinary levels of molecules related to removing apoptotic cells and triggering inflammation, as well as cytokines involved in Colombian patients with systemic lupus erythematosus without and with lupus nephritis compared to healthy controls. Materials and methods: Urine samples were taken from three groups of patients: healthy controls (n = 7), patients with systemic lupus erythematosus without lupus nephritis (n = 7), and patients with lupus and lupus nephritis (n = 4). The urine sample was collected and concentrated by ultrafiltration. A western blot evaluated HMGB1, Histone H3, Calreticulin (CRT), Annexin A1 and CD46, CX3CL1 by ELISA and cytokines such as IL-8, IL-6, IL-12p70, TNF-α, and IL-1β by flow cytometry. Results: Histone H3 was detected in two patients, one with systemic lupus erythematosus without lupus nephritis and one with systemic lupus erythematosus and lupus nephritis. The detected band suggests a post-translational modification. There were no differences between the levels of HMGB1 and CX3CL1 in the study groups. CD46, Annexin A1, and CRT were not detected in our samples. When evaluating cytokines in urine, an increase in IL-8 was observed in the group of patients with systemic lupus erythematosus without nephritis compared to controls. For IL-6, an increase was found among patients without lupus nephritis when compared with patients with lupus nephritis. No differences were found between the urinary levels of the other cytokines evaluated (IL-12p70, TNF-α, IL-1β, and IL-10). Conclusion: Urinary histone H3 and IL-8 levels may be interesting molecules to be evaluated in more patients with systemic lupus erythematosus, while HMGB1 and CX3CL1 are not useful. Further evaluation of patients is required to confirm these findings.