Plasma immunoglobulin binding protein 1 as a predictor of development of lupus nephritis

• Published in: Lupus Vol. 29; no. 6; pp. 547 - 553
• Main Authors: Kwon, Oh Chan, Lee, Eun-Ju, Oh, Ji Seon, Hong, Seokchan, Lee, Chang-Keun, Yoo, Bin, Park, Min-Chan, Kim, Yong-Gil
• Format: Journal Article
• Language: English
• Published: London, England SAGE Publications 01.05.2020; Sage Publications Ltd
• Subjects: Adaptor Proteins, Signal Transducing - blood; Adult; Anti-DNA antibodies; Biomarkers - blood; Biopsy; Disease Progression; Enzyme-Linked Immunosorbent Assay; Female; Humans; Immunoglobulins; Longitudinal Studies; Lupus; Lupus nephritis; Lupus Nephritis - blood; Lupus Nephritis - diagnosis; Male; Middle Aged; Molecular Chaperones - blood; Nephritis; Plasma; Proportional Hazards Models; Regression analysis; Sensitivity and Specificity; Systemic lupus erythematosus; immunoglobulin binding protein 1; lupus nephritis; Systemic lupus erythematosus
• DOI: 10.1177/0961203320912336
• ISSN: 0961-2033

Objective Urine levels of immunoglobulin binding protein 1 (IGBP1) are increased in patients with lupus nephritis (LN) compared with systemic lupus erythematosus (SLE) patients without nephritis. However, the clinical significance of IGBP1 level in plasma is unclear. We aimed to evaluate whether the plasma level of IGBP1 can predict future development of LN in SLE patients without nephritis. Methods Forty-three SLE patients without nephritis were followed for 5 years. Plasma IGBP1 levels were measured using ELISA, and clinical and laboratory data were obtained at study entry. Development of LN was confirmed by renal biopsy. Cox regression analysis was performed to identify factors associated with development of LN, and receiver operating characteristic curve analysis was used to determine the predictive value of each factor. Results Of the total 43 patients, eight (18.6%) developed LN during the follow-up period. Compared with patients who did not develop LN, those who developed LN had higher levels of plasma IGBP1 (6.3 ng/ml (range 4.3–9.6 ng/mL) vs. 13.3 ng/ml (range 7.2–31.3 ng/ml); p = 0.023). In the Cox regression analysis, higher CRP (hazard ratio (HR) = 1.325, 95% confidence interval (CI) 1.073–1.637, p = 0.009), anti-dsDNA antibody (Ab; HR = 1.066, 95% CI 1.012–1.124, p = 0.017) and plasma IGBP1 (HR = 1.091, 95% CI 1.034–1.152, p = 0.002) were associated with future development of LN. Among these factors, anti-dsDNA Ab (area under the curve (AUC)=0.893) had the highest predictive value followed by plasma IGBP1 (AUC = 0.761) and CRP (AUC = 0.634). A combination of anti-dsDNA Ab and plasma IGBP1 as a composite predictor was highly specific (97%) for predicting the development of LN. Conclusions Plasma IGBP1 can be used complementarily with anti-dsDNA Ab for detecting SLE patients at a higher risk of developing LN.