Comparison of apoptosis and growth factors in fetal kidney and cystic kidney diseases

ABSTRACT COMPRASION OF APOPTOSIS AND GROWTH FACTORS IN FETAL KIDNEY AND CYSTIC KIDNEY DISEASES In this study, a total of 48 kidneys were examined for anti-TGF-a, anti-VEGF, and apoptosis using strept-avidin-biotin peroxidase method and TUNEL method. Fifteen of the cases were normal fetal kidney samples whereas 28 were diagnosed as cystic kidney disease in fetal autopsies. Five adult normal kidney tissues are also included in the.study. We observed that reactivity of TGF-a was decreasing during the pregnangy period in proximal tubules, it was intense staining in distal tubules at all stage of pregnancy and it was disappeared in collecting tubules at the last stage of the pregnancy in fetal kidneys. In adult kidneys distal and collecting tubules showed a dense immunostaining pattern when compared with proximal tubules. Glomeruli were negative in both fetal and adult kidneys. This findings supported the mitogenic effect of TGFa in the growth of fetal kidneys and the, role of distal tubules in this primary process. In adult kidneys TGFa can play a role in the maintenance of the mitogenic effect of the labile nephron epithelium. Negative immunoreaction in the interstitium of cortex and medulla supported that TGFa has no mitogenic effects on mesenchyma. VEGF distribution was found to be parallel to TGFa distribution in fetal kidney tissues. VEGF staining was stronger in the epithelium than endothelium during the development of kidney. If also induces mitogenic activity as much as angiogenesis and/or is related from the kidney epithelium. Apoptosis was found at low levels in the epithelium till the end of the pregnancy. It was seen densely in the medulla at the last stage and in the nephrogenic zone mesencyhma at the early stage of the pregnancy in fetal kidneys. Our findings showed that apoptosis, in fetal kidneys, is essential in the loss of uninduced mesenchyma as much as the control of cell proliferation in nephron morphogenesis associated with growth factors. In the cystic renal disease, like distal tubuler epithelium, the intense immunostaining of TGFa and VEGF in small cysts when compared with the larger ones and increased apoptosis in larger cysts supports the important role of the small cyst epithelium in the cyst development. In cystic renal disease, the finding of decreased interstitiel apoptosis when compared with fetal tissues was observed in most cases however can be shown in high levels in some cases may depend on the stage of the disease and the existence of undifferentiated mesencyhma between the cysts. Our findings correlated well with the literature. Key words: Apoptosis, Growth factor, Fetal kidney, Cystic kidney disease VII