Researchers have identified low-abundance urinary biomarkers that are potentially useful for diagnosing lupus nephritis (LN), according to a new study published in Arthritis & Rheumatology.
The researchers identified these biomarkers using a new technique, an electrode-coupled immunoassay with an electrochemiluminescence (ECL) signal, that is more sensitive than traditional ELISA or antibody-based arrays.
Using a preexisting 40-plex ECL panel, Chandra Mohan, MD, PhD, from the Department of Biomedical Engineering at the University of Houston, Texas, and colleagues analyzed 48 human urine samples from 2 independent cohorts each consisting of 8 patients with active LN and 8 with inactive LN and 8 healthy control patients.
They found 17 urinary proteins that were elevated in the active LN samples compared with samples from patients with inactive LN and healthy control patients in 1 cohort, and 9 that were similarly elevated in the other cohort. From these, the investigators chose the cytokines interleukin (IL)-7, Il-12p40, and IL-15 and the chemokines IP-10 and TARC for further validation. These 5 biomarkers were undetectable by ELISA.
The investigators developed a custom 5-plex ECL panel, which they used to validate the results from the initial 40-plex screening panel.
The 5 biomarkers again were significantly elevated in active LN compared with inactive LN and healthy control patients.
In addition, all 5 proteins were more frequently elevated in LN compared with other chronic kidney disease controls.
“In conclusion,” the authors wrote, “custom [ECL]-based multiplex immunoassay panels are a promising technology for the identification and validation of potential urinary biomarkers of [LN].”
Stanley S, Mok CC, Vanarsa K, et al. Identification of low-abundance urinary biomarkers in lupus nephritis using electrochemiluminescence immunoassays [published online January 7, 2019]. Arthritis Rheumatol. doi: 10.1002/art.40813