Diagnostic value of progranulin in patients with lupus nephritis and its correlation with disease activity

The aim of this study was to explore whether progranulin (PGRN) can be a useful marker not only for accurate diagnosis of patients with active lupus nephritis (LN), but also for prediction of the disease activity in this population. A total of 154 LN patients were enrolled in this study, 76 of which were diagnosed as having active LN and 78 as having stable LN. Additionally, 71 age-matched non-LN patients were enrolled as controls. The serum and urine PGRN levels of each study population were measured using the enzyme-linked immunosorbent assay method. The diagnostic performance of both indicators and their correlation with the disease activity of LN were systematically investigated using receiver operating characteristic (ROC) analysis and correlation analysis. The active LN population had significantly higher serum and urine PGRN levels than the other two populations. ROC analysis further demonstrated that these two indicators, particularly in combination, appear to have a strong performance in discriminating active LN patients from the rest of the LN population. In the active LN population, serum and urine PGRN levels were not only significantly correlated with SLEDAI score, rSLEDAI score, and activity index, but also had a considerable association with several key markers reflecting the disease activity of LN, including serum levels of complement component 3 and ds-DNA. Nevertheless, neither of the two indicators were correlated with the pathological classification of LN, chronicity index, serum creatinine level, and 24-h urine protein levels. Our findings demonstrate that PGRN may have great potential as a diagnostic factor for active LN and as a predictor for its disease activity.