Urinary levels of calgranulin B, MCP-1, and IGFBP-5 have been identified as significant predictors of specific renal lesions in lupus nephritis, according to a recent study. 

In the study, published in Arthritis & Rheumatology, researchers examined urinary biomarkers to predict histological severity in lupus nephritis (LN). The objective was to identify urinary proteins associated with pathogenic signal pathways reflective of histological findings in LN. The researchers analyzed urine samples from patients with biopsy-proven active LN using an aptamer-based proteomic assay to screen for 1,305 proteins.

The study comprised urine samples from 24 patients diagnosed with lupus nephritis and 3 with diabetic nephropathy in the discovery cohort, while the validation cohort consisted of 24 patients with lupus nephritis. In the discovery cohort of patients with lupus nephritis, 14 of them were classified as having class III/IV, 6 as class III/IV+V, and 4 as class V nephritis.

The analysis identified five distinct histological subgroups correlated with specific urinary protein profiles. Levels of calgranulin B (S100A9), MCP-1, and IGFBP-5 were found to be significant predictors of glomerular lesions, interstitial inflammation, and interstitial fibrosis, respectively. Immunohistochemical staining further validated the localization of these proteins within renal tissues.

Urinary calgranulin B levels were associated with histological scores for cellular/fibrocellular crescents (r = 0.65, P < .001) and endocapillary hypercellularity (r = 0.72, P < .001). Additionally, urinary MCP-1 levels showed a correlation with interstitial inflammation scores (r = 0.65, P < .001), while urinary IGFBP-5 levels were linked to interstitial fibrosis scores (r = 0.41, P = .048).

In the receiver operating characteristic analysis, calgranulin B demonstrated an area under the curve (AUC) of 0.78 for predicting cellular/fibrocellular crescents and 0.87 for endocapillary hypercellularity. MCP-1 showed an AUC of 0.84 for assessing interstitial inflammation, while IGFBP-5 had an AUC of 0.71 for interstitial fibrosis.

The study was funded by Mitsubishi Tanabe Pharma Corporation, and the authors declare no competing interests related to this research.