Abstract

Methods. In a prospectively enrolled cohort with pathologist-adjudicated histological diagnoses, termed the discovery cohort, we tested the association of 180 immune proteins measured by a proximity extension assay with AIN and validated the top protein, CXCL9, using sandwich immunoassay.

Results. In a proximity extension assay, urinary CXCL9 was 7.6-fold higher in patients with AIN than in individuals in the control group (P = 1.23 × 10^–5).

Conclusion. We identified CXCL9 as a diagnostic biomarker for AIN using proximity extension urine proteomics, confirmed this association using sandwich immunoassays in discovery and external validation cohorts, and observed higher expression of this protein in kidney biopsies from patients with AIN.

Figure 1

Volcano plot demonstrating associations of proximity extension measurement of urine proteins with acute interstitial nephritis diagnosis.

The authors regret the errors.

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