The Relationship Between The Calcium Sensing Receptor Expression And Renal Interstitial Injury In Children With Idiopathic Nephrotic Syndrome

Objective To examine calcium/phosphorus metabolism, the expression of calcium sensing receptor on tubular cells and the transforming growth factor-βexpression of renal interstitial and the microvessel changes in children with idiopathic nephrotic syndrome and explore the relationship the influence of calcium sensing receptor expression to the etiology of renal interstitial injury.Methods Forty children in the Second Xiangya Hospital from 2010/01 to 2010/09 with idiopathic nephrotic syndrome(INS) diagnosized according to standards by the nephrology group of pediatric branch of Chinese Medical Association were enrolled and divided into two groups, INS(those who have not taken prednisone therapy 10 cases) and INS/PRED (those who have taken prednisone therapy eight weeks haven't completely remission 20 cases). Kidney tissue from 5 cases accepting nephrectomy for renal trauma in Urology department was considered as control and 10 healthy children were enrolled for calcium and phosphorus concentration examination by automatic biochemical analyzer. Immunohistochemistry assay was used to detect the expression of CD34, CaSR, and TGF-β.Results (1) Compared with control group, serum Ca decreased INS children and INS/PRED significantly, with P<0.05. The difference of calcium concentration in INS and INS/PRED children did not show significant differences, with P>0.05. Compared with that in control, serum phosphorus levels in INS children increased, with P>0.05, while increased significantly in INS/PRED, with P<0.05. (2) Compared with that in control, renal interstitial microvessel density decreased INS children with P>0.05 and INS/PRED with P<0.05. Renal interstitial microvessel density decreased in INS/PRED children when compared with that in INS children, with P>0.05. (3) Compared with that in control, CaSR expression in renal interstitial increased INS children with P<0.05 and INS/PRED with P<0.01. CaSR expression increased in INS/PRED children when compared with that in INS children, with P<0.05. (4) Compared with that in control, TGF-(3 expression in renal interstitial increased INS children with P<0.05 and INS/PRED with P<0.01. TGF-βexpression increased in INS/PRED children when compared with that in INS children, with P<0.05. (5) The tubular damage including vacuolar degeneration, occasional necrosis and obvious interstitial edema and mild to moderate inflammatory cells infiltration could be found in kidney samples from children with INS. Compared with that in control, with P<0.05.Severer damages, such as light to severe vacuolar degeneration of tubular epithelial cells and more necrosis, interstitial edema, could be found in INS/PRED children with higher frequency. Furthermore, interstitial fibrosis could be seen in INS/PRED children when compared with that in INS children, with P<0.05. (6) A negative correlation between CaSR expression and interstitial microvessel density could be obtained from correlation analysis,with the correlation coefficient-0.5, P<0.05. A positive correlation between CaSR expression and TGF-βexpression in renal interstitial, could be obtained from correlation analysis, with the correlation coefficient 0.803, P<0.05. A positive correlation between CaSR expression and renal interstitial interstitial pathological score could be obtained from correlation analysis, with the correlation coefficient 0.945, P<0.01.Conclusion There exist abnormal calcium and phosphorus metabolisms in children with idiopathic nephrotic syndrome. Glucocorticoid resistance in children could aggravate the abnormal calcium/phosphorus metabolism. There may be a positive relation between the enhanced expression of CaSR and the INS etiology and could take part in the microvessel damage in renal interstitial and renal tubular cells injury.