Urinary Soluble CD163 in Active Renal Vasculitis.

Area of Science:

• Nephrology
• Immunology
• Biomarker Discovery

Background:

• A specific biomarker for active renal vasculitis is needed, often requiring invasive kidney biopsies.
• Soluble CD163 (sCD163), released by macrophages, is a potential marker for macrophage activation.

Purpose of the Study:

• To investigate if urinary sCD163 correlates with active glomerular inflammation in renal vasculitis.
• To evaluate sCD163 as a noninvasive diagnostic marker for active renal vasculitis.

Main Methods:

• Detected sCD163 in rat urine during experimental vasculitis.
• Quantified CD163 mRNA and protein expression in human kidney biopsies (SVV vs. controls).
• Measured serum and urinary sCD163 levels in patients with SVV, disease controls, and healthy individuals across validation cohorts.

Main Results:

• Glomeruli from small vessel vasculitis (SVV) patients showed higher CD163 mRNA than controls.
• CD163 protein was highly expressed in glomeruli and interstitium of SVV patients.
• Urinary sCD163 levels were significantly higher in active renal vasculitis patients compared to remission, controls, and healthy individuals.
• Serum sCD163 levels did not differ between groups.
• Urinary sCD163 achieved 83% sensitivity and 96% specificity for active renal vasculitis detection.

Conclusions:

• Urinary sCD163 is a sensitive and specific noninvasive biomarker for active renal vasculitis.
• Assessing urinary sCD163 may provide a new method for diagnosing renal flares in known SVV patients.