Kidney Injury Molecule-1 Expression In Adult Henoch-Sch(?)nlein Purpura Nephritis And Its Clinical Significance

Background and AimsKidney injury molecule-1(KIM-1)was identified the most highly upregulated protein in chronic kidney diseases and prolonged KIM-1 expression may be maladaptive.The present study was aimed to investigate urinary,renal and serum KIM-1 levels and to analyze association between KIM-1 levels with clinical and pathological indexes in adult Henoch-Schonlein purpura nephritis(HSPN)patients.Methods20 healthy individuals,20 HSP patients without nephritis and 35 HSP patients with nephritis were recruited.Urinary and serum KIM-1 levels were determined by enzyme linked immunosorbent assay and Luminex,respectively.Urine KIM-1 level was normalized to urinary creatinine for each sample.The normalized data was indicated as urinary KIM-1 concentration/creatinine concentration(ng/mg).Renal KIM-1 expression was evaluated by immunohistochemistry.The KIM-1 expression level in renal specimens and pathological indexes were semi-quantitated by an image analysis system.ResultsHSP patients with nephritis were characterized as elevated levels of urinary,renal and serum KIM-1.Those with more severe tubular injury of renal biopsy tissues presented significantly higher urinary and renal KIM-1 levels in HSPN patients.Urinary and renal levels of KIM-1 were positively correlated with blood urea nitrogen and urinary ACR,while they were negatively correlated with eGFR at both baseline and after 2-3 years follow-up.Urinary and renal levels of KIM-1 did not correlate with eGFR decline rate after 2-3 years follow-up.Moreover,serum KIM-1 levels were associated with blood urea nitrogen,cystatin-C and urinary ACR as well.Further univariate correlation analysis indicated urinary and renal KIM-1 levels was positively correlated with interstitial inflammation index and tubulointerstitial chronicity index.Only urinary KIM-1 levels were associated with extracapillary glomerular activity index,interstitial inflammation index and tubulointerstitial chronicity index,after logistic regression analysis.Urinary KIM-1/Cr predicting tubulointerstitial chronicity of T2 by the area under the curve was 0.910,which was obviously better than eGFR,urinary ACR,serum creatinine,blood urea nitrogen and serum cystatin-C.ConclusionsThis finding suggests that KIM-1 is increased in adult Henoch Schonlein purpura nephritis patient’s urine,renal tubular epithelial cells and serum.Compared with serum KIM-1,urinary KIM-1 level may be more helpful to evaluate the expression of KIM-1 in renal tissue and to evaluate severity of renal pathological damage in adult HSP patients with nephritis.