title: Urinary high-mobility group box-1 associates specifically with lupus nephritis class V.
abstract: BACKGROUND
  High-mobility group box 1 protein (HMGB-1) has been implicated in the pathogenesis of lupus nephritis (LN). There is increased HMGB-1 expression in the kidneys and increased levels are observed in serum and urine of patients with LN. This study was performed to determine whether the increased urinary HMGB-1 was specific for active lupus or secondary to renal damage.
  
  
  METHODS
  Urine from 61 lupus patients (32 had active LN and 29 had systemic lupus erythematosus (SLE) with no evidence of LN) and 14 control proteinuric patients (all with hypertension and eight also with diabetes) were included in this study. HMGB-1 was detected by Western blot. Urine protein was normalized to urine creatinine to account for volume of the specimen.
  
  
  RESULTS
  Median normalized urine HMGB-1 levels were significantly elevated in LN patients compared to lupus patients without kidney disease (53.81 vs 9.46, p < 0.001). A difference in median levels was seen between LN classes, with a significant difference between proliferative and membranous disease (33.4 vs 138.8, p = 0.003). Urine protein to urine creatinine ratio (P/C) correlated with urinary HMGB-1 (r = 0.52, p < 0.001), but across the classes this was true only for membranous disease (r = 0.71, p = 0.022, proliferative, p = 0.63; mixed, p = 0.34).
  
  
  CONCLUSIONS
  HMGB-1 is elevated in the urine of patients with active LN. Levels are associated with LN class, and higher levels of urinary HMGB-1 are seen in patients with class V when compared to both proliferative and mixed classes. Therefore, urinary HMGB-1 may be suggestive of membranous LN and warrants further evaluation in a large lupus cohort.
authors.affiliation: Rheumatology Section, Department of Medicine, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, USA.|Current affiliation: Arthritis and Clinical Immunology, Oklahoma Medical Research Foundation, Oklahoma City, OK, USA.
authors.forename: N R
authors.initials: NR
authors.lastname: Jog
authors.affiliation: Division of Rheumatology, Albert Einstein College of Medicine, Bronx, NY, USA.
authors.forename: I
authors.initials: I
authors.lastname: Blanco
authors.affiliation: Nephrology Section, Department of Medicine, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, USA.
authors.forename: I
authors.initials: I
authors.lastname: Lee
authors.affiliation: Division of Rheumatology, Albert Einstein College of Medicine, Bronx, NY, USA.
authors.forename: C
authors.initials: C
authors.lastname: Putterman
authors.affiliation: Rheumatology Section, Department of Medicine, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, USA roc@temple.edu.|Department of Microbiology and Immunology, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, USA.
authors.forename: R
authors.initials: R
authors.lastname: Caricchio
mesh_terms: D000328:Adult; D000368:Aged; D015415:Biomarkers / Q000652:urine; D003404:Creatinine / Q000652:urine; D005260:Female; D015433:Glomerulonephritis, Membranous / Q000652:urine*; D024243:HMGB1 Protein / Q000652:urine*; D006801:Humans; D007668:Kidney / Q000503:physiopathology; D007677:Kidney Function Tests; D008181:Lupus Nephritis / Q000145:classification / Q000652:urine*; D008297:Male; D008875:Middle Aged; D012720:Severity of Illness Index; D016482:Urinalysis
chemical_list: D015415:Biomarkers; D024243:HMGB1 Protein; D003404:Creatinine
keywords: HMGB-1; lupus nephritis; membranous nephritis