Urine macrophages reflect kidney macrophage content during acute tubular interstitial and glomerular injury.

Macrophage polarization is a major contributing factor in acute kidney injury (AKI). We aim to determine its biomarker value in differentiating etiologic causes of various intrinsic renal AKI. A total of 205 patients with renal intrinsic AKI were enrolled. Urinary sCD163 was quantified and macrophage subtypes in urine and in renal biopsy were determined. Compared to healthy controls and AKI due to interstitial or tubular injuries (0 pg/µmol), urinary sCD163 was markedly higher in glomerulopathy, especially in diffuse proliferative glomerulonephritis (275.5 pg/µmol) and significantly correlated with cellular crescent formation. Urine sediment analysis of M1/M2 ratio could differentiate acute tubulointerstitial nephritis (M1/M2 > 2.35) from crescentic glomerulonephritis (M1/M2 < 0.27). Urinary sCD163 levels and M2 subtype positively correlated with infiltrated M2 in the glomeruli, whereas urine M1 positively correlated with infiltrated M1 in the interstitium. Of note, urinary sCD163 showed better diagnositic performance in differentiating disease etiologies compared to tradiational urinary biomarkers of AKI (NGAL and KIM-1) and markers of myeloid cells (CD11b) and pan macrophages (CD68). Thus markers of macrophage polarization could be viewed as the noninvasive "liquid biopsy" in the presence of various intrinsic kidney diseases.

The Detection of Urinary Podocytes from Drug-Induced Glomerular Thrombotic Microangiopathy in Advanced Cancer Patients.

BACKGROUND: Focusing on glomerular thrombotic microangiopathy (TMA), we detected urinary podocytes to evaluate podocyte damage following glomerular endothelial cell injury. METHODS: We analyzed the relationship between urinary podocytes as biomarkers for podocyte injuries and clinical manifestations in five patients of anti-cancer-drug-induced glomerular TMA. RESULTS: Cancer in all five patients was advanced, including 4 cases of renal cell carcinoma treated with tyrosine kinase inhibitor, and one with intrahepatic bile duct carcinoma treated with gemcitabine. Urinary podocytes were detected in 2 cases that rapidly developed acute kidney injury (AKI) and nephrotic syndrome, while they were not detected in 3 cases of slowly progressive chronic renal failure. One case with AKI, presenting sequential manifestations of urinary podocytes, showed the decrease and disappearance of urinary podocytes in accordance with the cessation of the anti-cancer drug, followed by improvement in renal function and in clinical symptoms such as hypertension. CONCLUSIONS: These findings indicate that severe endothelial cell dysfunction during the acute phase of glomerular TMA leads to podocyte loss.