Urinary Kringle Domain-Containing Protein HGFL: A Validated Biomarker of Early Sickle Cell Anemia-Associated Kidney Disease

Abstract

Introduction: Chronic kidney disease (CKD) is a prevalent complication of sickle cell anemia (SCA). Hyperfiltration that delayed detection of CKD is common in SCA patients. Identification of novel urinary biomarkers correlating with glomerular filtration rates may help to detect and predict progression of renal disease.

Methods: Reanalysis of mass spectra of urinary samples obtained from University of Illinois at Chicago identified kringle domain-containing protein HGFL.

Results: HGFL levels correlated with hyperfiltration, were significantly reduced at CKD stage 1 compared to stage 0, negatively correlated with progression of CKD and were suitable for differentiation of stage 1. Better prediction of CKD progression to stage 2 was observed for HGFL-based risk prediction compared to the estimated glomerular filtration rate (eGFR)-based prediction. Results from a Howard University patient cohort supported the utility of HGFL-based test for the differentiation of stage 1 of CKD.

Conclusion: Urinary HGFL may contribute additional information beyond eGFR and improve diagnosis of early-stage CKD in SCA patients.

Keywords: Chronic kidney disease; Glomerular filtration rate; HGFL; Hyperfiltration; Selected reaction monitoring; Sickle cell anemia.

Fig. 1

Urinary HGFL levels increase in the SCA subjects with hyperfiltration, correlate with eGFR, allow of differentiation of CKD stage 1, and better predict progression of albuminuria and CKD. (A) HGFL/Cr levels in subjects with normal filtration and hyperfiltration quantified by single reaction monitoring (SRM) mass-spectrometry, performed in 19 samples collected from Chicago cohort patients without kidney disease. Hyperfiltration was defined as eGFR>130 ml/min/1.73m² for women and >140 ml/min/1.73m² for men. Results on the graph are shown for each subject and as mean for group. (B) Pearson correlation of HGFL/Cr levels quantified by SRM with eGFR calculated based on CKD-EPI equation. (C). Pearson correlation between HGFL/Cr levels quantified by ELISA and stages of CKD. The 54 samples were collected from the Chicago cohort patients with stages 0-4 CKD. (D) HGFL/Cr levels at stage 1 of CKD and in subjects without kidney disaese quantified by ELISA in the Chicago cohort samples (N=22). Results on the graph are shown for each subject and as mean for group. (E) Receiver operating characteristic curve analysis for differentiation of stage 1 of CKD from no kidney disease for the Chicago cohort samples. AUC is an area under curve. (F) HGFL/Cr levels at stage 1 of CKD and in subjects without kidney disease quantified by ELISA in the Howard cohort samples (25 sarnies with stage 0 and 7 samples with stage 1). Results on the graph are shown for each subject and as mean for group. (G-H) Fifty-four patients from the Chicago cohort were followed up for a median length of 26 months (range 6-68 months) and risk of disease progression was calculated using 4 variables kidney failure risk equation. (G) C-statistic, calculated using eGFR-based equation. (H) C-statistic, calculated using HGFL-based equation. Area under curve (AUC) and 95% confident intervals (95% Cl) are shown. ALB- risk of progression from microalbuminurria (30mg/g<ALB/Cr<300 mg/g) to macroalbuminuria (ALB/Cr>300 mg/g), Stage 1 - risk of progression from stage 1 to stage 2 CKD, Stage 2-3 – risk of progression from stage 2 and 3 to the next stage of renal disease. Cr – creatinin.