Abstract: FR-PO671

Urine sCD163 Is a Biomarker of Active Nephrotic Syndrome

Session Information

Category: Glomerular

  • 1001 Glomerular: Basic/Experimental Immunology and Inflammation

Authors

  • Moran, Sarah Margaret, Trinity College, Dublin, Ireland
  • Dooley, Dearbhaile, Trinity College, Dublin, Ireland
  • Kretzler, Matthias, U.Michigan, Ann Arbor, Michigan, United States
  • Little, Mark Alan, Trinity College, Dublin, Ireland

Group or Team Name

  • Neptune Nephrotic Syndrome Study Network
Background

Prior work has demonstrated that urinary soluble CD163 (usCD163) displays excellent biomarker characteristics for detection of active renal vasculitis in patients with ANCA-associated vasculitis and Lupus. We sought to assess the levels of usCD163 in active and remission nephrotic syndrome.

Methods

Patients with biopsy proven nephrotic syndrome (Minimal change (MCD), focal and segmental glomerulosclerosis (FSGS) and membranous glomerulonephritis (MN) were included. Paired urine samples from time of remission (urine protein creatinine ratio (uPCR) <0.5mg/mmol) and of active nephrotic syndrome (uPCR >3.5mg/mmol) were selected from NEPTUNE a multicentre longitudinal cohort. Creatinine-normalised usCD163 levels were measured in urine by ELISA.

Results

53 patients were included (MN n=22, MCD n=20, FSGS n=11). Median age at onset of NS was 34.5 years (IQR 13.5-59.8 yrs), median eGFR was 77.3mls/min/1.73m2 (SD ±30.3mls/min/1.73m2). Median usCD163 levels were higher in active nephrotic syndrome (536.3ng/mmol (IQR 222.7-1061 ng/mmol))) compared to remission (0.9ng/mmol (IQR 0-19.6 ng/mmol), p<0.0001) with median values in active FSGS of 372.9ng/mmol (IQR 151.4-639mg/mmol), active MCD of 539.2ng/mmol (IQR 114.3-1511/mmol), and active MN of 604.2ng/mmol (IQR 305.8-1423/mmol), p=0.417. (figure 1A). uProtein:Creatinine Ratio and usCD163 levels were significantly correlated with a low correlation coefficient – in active NS r2=0.14, p=0.006 (figure 1B).

Conclusion

usCD163 levels are markedly elevated in active nephrotic syndrome. 14% of the observed variance in usCD163 was explained by total urine protein excretion. This suggests that, although some of the measurable usCD163 in urine of patients with nephrotic syndrome is due to leak across the GBM, most appears to be derived directly from the glomerular immune process.

Figure 1A: usCD163 levels in remission and active nephrotic syndrome. FSGS=focal and segmental glomerulosclerosis, MCD=minimal change disease, MN= membranous glomerulonephritis. Figure 1B: Correlation between urine protein creatinine ratio and usCD163 in active nephrotic syndrome.