Abstract: TH-PO836
Plasma Calprotectin Is a Marker of Stable Remission in ANCA Vasculitis
Session Information
- Glomerular Diseases: Immunology and Inflammation - I
October 25, 2018 | Location: Exhibit Hall, San Diego Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Glomerular Diseases
- 1202 Glomerular Diseases: Immunology and Inflammation
Authors
- McInnis, Elizabeth A., UNC Kidney Center, Chapel Hill, North Carolina, United States
- Hu, Yichun, UNC Kidney Center, Chapel Hill, North Carolina, United States
- Wu, Eve, The University of North Carolina, Chapel Hill, North Carolina, United States
- Free, Meghan E., UNC Kidney Center, Chapel Hill, North Carolina, United States
- Hogan, Susan L., UNC Kidney Center, Chapel Hill, North Carolina, United States
- Bunch, Donna O., UNC Kidney Center, Chapel Hill, North Carolina, United States
- Falk, Ronald J., UNC Kidney Center, Chapel Hill, North Carolina, United States
Background
In ANCA vasculitis, an increase in serum calprotectin (S100A8/9) was implicated as a marker of relapse and inflammation, but levels did not normalize during remission. Serum may not allow sensitive measurement of S100A8/9. We sought to determine if S100A8/9 is best measured in plasma or serum and if it is a marker of disease activity and remission in ANCA vasculitis.
Methods
S100A8/9 was measured by ELISA (BioLegend) in 16 paired serum and plasma samples. Plasma levels were also tested in 31 patients during active (BVAS>3, 15 MPO, 16 PR3) and remitting disease and in 14 age/gender matched healthy subjects. Additionally, 8 patients (4 MPO, 4 PR3) in long term remission off therapy (LTROT) for ≥5 years were evaluated and compared to healthy subjects.
Results
Serum measures of S100A8/9 averaged 2.90 μg/mL higher and had a higher standard deviation than plasma measures (4.29 vs 4.02 respectively). Thus, plasma measures were used for all analyses.
Conclusion
Plasma S100A8/9 levels were elevated during active disease. Levels decreased during remission, but remained higher than in healthy controls. Patients in LTROT, however, had plasma S100A8/9 levels similar to healthy subjects.
These findings suggest S100A8/9 is elevated during active disease and decreases, but remains slightly elevated, during remission, possibly due to subclinical inflammation. Levels may continue to decrease and normalize in long term remission off therapy. Prior studies may have observed artificially elevated levels of S100A8/9 due to measurements obtained in serum rather than plasma.
Measurement of plasma S100A8/9 (ug/mL) in ANCA vasculitis patients and healthy subjects
| Groups | Active Disease | Disease Remission | Healthy Subjects | P Value Paired Act vs Rem* | P Value Remission vs Healthy Subjects** | |
| All paired patients | N Median (IQR) | 31 2.56 (1.90, 5.31) | 31 1.60 (1.13, 2.00) | 14 0.86 (0.77, 1.26) | <0.0001 | 0.009 |
| MPO patients | N Median (IQR) | 15 2.99 (1.99, 5.26) | 15 1.60 (1.23,1.98) | 14 0.86 (0.77, 1.26) | 0.002 | 0.005 |
| PR3 patients | N Median (IQR) | 16 2.54 (1.82, 6.66) | 16 1.58 (0.86, 2.28) | 14 0.86 (0.77, 1.26) | 0.018 | 0.085 |
| LTROT patients | N Median (IQR) | 8 1.10 (0.77, 1.44) | 14 0.86 (0.77, 1.26) | 0.517 |
*P value was calculated by signed rank paired test. ** P value was calculated by Wilcoxon two sample test.
Funding
- NIDDK Support