High-Mobility Group Box 1 Protein (HMGBl): Role in Lupus Nephritis

Background: According to recent studies, in renal disease High Mobility Group Box 1 protien (HMGB1) levels in blood and urine, its expression in renal tissue, and its levels in the cytoplasm and extracellular medium are all elevated. Aim of Study: Was to assess serum and urinary levels of HMGB1 in correlation to renal histopathology, disease activity and organ damage in systemic lupus patients (SLE). Patients and Methods: Serum and urine levels of HMGB1 were measured in 25 SLE patients with active nephritis by ELISA at baseline (I) and after 6 months follow-up (II). Renal biopsies were performed at baseline. Results: There was high statistical significant difference between serum and urine HMGB 1 at baseline (I) and after follow-up (II) and between total BILAG score (I) and (II). There was statistically significant difference between SLE nephritis patients (responders and non responders) as regard total BILAG index, p 0.05. After follow-up, there was significant difference between patients with BILAG category A and C in serum (but not urinary) high mobility box protein 1 (II). There was significant positive correlation between total BILAG score after follow-up and serum level of High Mobility Box protein 1 (II) and SLICC score, p < 0.05. There was a significant positive correlation between renal BILAG score after follow-up and serum High Mobility Box protein 1 (II) after follow-up. There was a significant positive correlation between 24hrs urinary proteins and urinary level of High Mobility Box protein 1 (II) after follow-up p < 0.05. Conclusion: HMGB 1 levels (serum and/or urinary) are high in SLE patients with nephritis compared to reference range. There is an association/correlation not only between HMGB1 and general disease activity in SLE patients but also between it and renal disease activity, severity and class. It could be a useful marker of lupus nephritis activity and class that may influence therapeutic strategies replacing rebiopsy.