Urinary mannose-binding lectin is a biomarker for predicting the progression of immunoglobulin (Ig)A nephropathy

Abstract

SummaryComplement system activation is associated with immunoglobulin A nephropathy (IgAN) activity and progression. The aim of the present study was to investigate the importance of urinary mannose-binding lectin (MBL), at the time of renal biopsy, for evaluating disease severity and predicting the progression of IgAN. A total of 162 patients with biopsy-proven IgAN were enrolled and 50 healthy individuals were selected as normal controls. Urinary MBL was measured by sandwich enzyme-linked immunosorbent assay (ELISA) and normalized for urinary creatinine concentration. Urinary MBL was significantly higher in IgAN patients than that in normal controls, and elevated as histopathological phenotypes upgraded. Urinary MBL was correlated significantly with the well-known clinical predictors for the prognosis of IgAN; that is, renal function (represented by serum creatinine and estimated glomerular filtration rate), proteinuria and arterial hypertension. Urinary MBL was demonstrated to be correlated with the histopathological parameters which have independent value in predicting renal outcome of IgAN according to the Oxford classification; that is, mesangial hypercellularity, segmental glomerulosclerosis, endocapillary hypercellularity and tubular atrophy/interstitial fibrosis. More importantly, non-remission patients at the end of follow-up had significantly higher levels of urinary MBL compared with patients in remission. In conclusion, urinary MBL can be a reliable non-invasive biomarker for evaluating disease severity and predicting the prognosis of IgAN. This is the first report on this issue. However, our conclusions should be verified further in large-scale studies with long-term follow-up.

Complement and kidney disease

“…Consistent with a role for the lectin pathway is the presence of C4d in glomeruli and increased C4d staining is associated with increased risk of progression [44]. Liu et al [45] have studied urinary mannose-binding lectin (MBL) in 162 patients with IgAN. They found that urinary MBL was significantly higher in IgAN patients than that in normal controls.…”

Diagnosis and monitoring of IgA nephropathy: the role of biomarkers as an alternative to renal biopsy

“…Liu et al [66] sTfR Urine Urinary levels of sTfR were markedly higher in patients with active IgAN or HSPN in comparison with patients with other morphological types of glomerulopathy and healthy subjects. A cut-off level of 5 μg/L was proposed to distinguish active disease from partial or complete remission.…”

“…properdin, factor I and factor H were significantly higher in IgAN patients than in healthy controls, but only serum C4 binding protein was able to predict disease prognosis [68]. Furthermore, urinary MBL has been suggested as a reliable noninvasive biomarker for evaluation of disease severity and prediction of the prognosis of IgAN [66].…”

“…In IgAN, the deposits of IgA and the glomerular damage are associated with complement activation [33,[64][65][66][67]. properdin, factor I and factor H were significantly higher in IgAN patients than in healthy controls, but only serum C4 binding protein was able to predict disease prognosis [68].…”

Biomarkers in IGA Nephropathy

“…Mannose binding lectin (MBL) is one of the proteins that are involved in complement component system activation and has been associated with IgAN pathogenesis [17,18]. Urinary levels of MBL were found to be increased in IgAN patients when compared with healthy controls.…”