Objective: In search of potential urinary biomarkers of obstructive nephropathy, this study examined whether a potential change in the concentration of urinary cytokines [interferon-γ(IFN-γ), interleukin-1β (IL-1β), IL-2, IL-6, IL-10 and tumour necrosis factor-α (TNF-α)] reliably reflects changes in renal parenchymal levels of the same cytokines following the release of acute and chronic unilateral ureteral obstruction, respectively.
Material and methods: Acute obstruction was performed in 12 adult rats. After 48 h, six rats were used for selective urine collection and six rats had their kidneys removed and dissected into inner medulla and cortex. Chronic obstruction was performed in newborn rats. After 10 weeks, a similar set-up to that of the acute study was implemented. Sham-operated rats were prepared in parallel. Urine and tissue cytokines were measured with a bead-based multiplex sandwich immunoassay and analysed on a Luminex 100 IS instrument.
Results: In the acute study, there were significantly increased concentrations of IL-1β and IL-6 in inner medulla and in urine from the obstructed kidney, significantly increased concentrations of TNF-α in urine from the obstructed kidney and, importantly, significantly increased levels of IL-10 in cortex and in urine from the non-obstructed kidney. In the chronic study, there were similar changes in IL-1β and IL-6 (not significant) but no changes in TNF-α and IL-10.
Conclusions: This study showed that inflammatory cytokines can be detected both in renal parenchyma and in urine from rats with experimental unilateral ureteral obstruction. Further studies are needed to confirm the diagnostic accuracy of IL-1β, IL-6, IL-10 and TNF-α in urine.