Urine neutrophil gelatinase-associated lipocalin as a biomarker of disease activity and pathological types in lupus nephritis

Abstract

Objective To investigate the relationship between urine neutrophil gelatinase-associated lipocalin (uNGAL) level and activity and pathological types of lupus nephritis (LN). Methods Thirty cases of biopsy proven LN patients as the initial onset were enrolled into the study. Ten healthy persons were selected as controls. The clinical and pathological data and blood, urine specimen were collected. The uNGAL was mea-sured by enzyme linked immunosorbent assay. The relationship between uNGAL and clinical and pathological features of LN was analyzed. One-way analysis of variance (ANOVA) and Pearson's correlation analysis were used for statistical analysis. Results Nineteen cases were in the LN active group and 11 cases were in the inactive group. The level of plasma NGAL had no significant difference between the active LN group [(64±6) ng/ml] and the inactive LN group [(58±20) ng/ml] and the healthy control group [(57±20) ng/ml] (P>0.05). The level of urine NGAL in the active LN group [(69±3) ng/ml] and inactive LN group [(66±5) ng/ml] was higher than that in the healthy control group [(64±5) ng/ml, P=0.009, 0.016, respectively]. Urine NGAL level in active LN group was higher than that in the inactive group (P=0.012). Urine NGAL level was positively correlated with SLEDAI, R-SLEDAI, GAI, TLAI, AI (r=0.472, 0.521, 0.502, 0.516, 0.597, respectively, P=0.042, 0.036, 0.042, 0.021, 0.007, respectively). The urine NGAL concentration after comparing to different pathological conditions were: urine NGAL's level [ (69.7±2.4) ng/ml] of type Ⅳ LN was higher than type ⅢN[(65.3±3.2) ng/ml] and type Ⅴ [(64.6±5.0) ng/ml] (P=0.031, 0.028, respectively). Receiver operating characteristic (ROC) indicated that uNGAL was more sensitive (86.7%) and specific (73.3%) for the diagnose of type Ⅳ LN than type Ⅲ or type Ⅴ LN. Conclusion uNGAL is closely related with disease activity and pathological activity in LN. uNGAL enables clinician to assess the activity of LN and could be a sensitive marker for the diagnosis of type Ⅳ adult LN. Key words: Lupus nephritis; Lupus erythematosus, systemic; Neutrophil gelatinase-associated lipocalin; Disease activity index