Aim of the work: To evaluate the impact of systemic lupus erythematosus (SLE) on
urinary levels of podocalyxin and nephrin and to determine their relationship to renal biopsy
and disease activity in lupus nephritis (LN) patients.
Patients and methods: The study included 50 LN patients with their renal biopsy classified
according to the international society of nephrology. Disease activity was determined using the
British Isles Lupus Assessment Group (BILAG). All patients underwent clinical and laboratory
evaluation. Urine samples were collected for the assessment of urinary podocalyxin (UPx) and
nephrin (UN) by ELISA and for the estimation of protein (UP) and creatinine (Cr) concentrations.
The UPx:Cr, UN:Cr and UP:Cr ratios were calculated.
Results: Urinary levels of podocalyxin (593.8± 282.2 ng/ml), nephrin (304.1 ±236.8 ng/ml)
and protein (2.36 ± 0.56 g/l) were significantly higher, while urinary creatinine levels (101.4
± 28.7 mg/l) lower in LN patients compared to control (38.1± 9 ng/ml, 19.2 ± 4.1 ng/ml, 0.34
± 0.13 g/l and 155.4 ± 26.7 mg/l; p= 0.0008, p= 0.0003, p=0.00002 and 0.0009, respectively).
Consequently, UNCr, UPxCr and UPCr ratios were significantly higher in patients compared to
control. There was a significant correlation of the estimated ratios with the LN class and with
the BILAG scores being most significant with UPx:Cr ratio. ROC curve and regression analyses
defined UPx:Cr ratio as the specific significant predictor of pathological LN grade.
Conclusion: SLE deleteriously affects fine glomerular structure as reflected by increased urinary
levels of podocyte-related proteins; podocalyxin and nephrin. Urinary podocalyxin/creatinine ratio significantly predicts the pathological impact of SLE on the kidney and could be used as a noninvasive
marker for such effect and its progression.
2015 The Authors. Publishing services provided by Elsevier B.V. on behalf of Egyptian Society of
Rheumatic Diseases. This is an open access article under the CC BY-NC-ND license (http://
creativecommons.org/licenses/by-nc-nd/4.0/). |
