[The modulation of renal tubular epithelial cells treated with hypoxia on renal interstitial fibroblasts in coculture].

To clarify cell-cell interaction in the pathogenesis of renal tubulointerstitial nephritis (TIN), the effect of renal tubular epithelial cells (TEC) on renal interstitial peritubular fibroblasts (PTF) was examined in cell coculture system without direct contact. TEC and PTF were prepared from the kidney of BALB/C mice. Firstly, TEC were plated into intercup chambers of 24-well plates and incubated at 37 degrees C in a humidified 5% CO2 atmosphere for 72 hours. Then the cells were cultured in an incubator which was full of 95% N2 for 24 hours. Secondly, those intercups with hypoxia-treated TEC were floated on the wells of 24-well plates containing PTF which had been incubated for 24 hours. The TEC and the PTF were cocultured for another 48 hours. PTF were also cocultured with normal TEC as controls. The parameters of the cocultured PTF were measured as follows. (1) Cell proliferation examined by MTT incorporation method and the cell numbers were detected with total acid phosphatase activity. (2) Fibronectin (FN), laminin (LN) and collagen IV in the supernatants of coculture system were measured by ELISA method. (3) The distribution of ICAM-1 on the cell membrane of PTF was determined by laser confocal scanning microscopy.

RESULTS

(1) The number of PTF cocultured with hypoxiatreated TEC was greater than that of controls (P < 0.01). (2) The level of FN and LN in the supernatants of the PTF cocultured with hypoxia-treated TEC was higher than that of the controls (P < 0.05). (3) The expression of ICAM-1 on PTF cocultured with hypoxia-treated TEC was higher than that of controls (P < 0.01). In conclusion the interaction of PTF and TEC may play a role in the pathogenesis of TIN.