RESUMEN

BACKGROUND: It has been demonstrated that Fasmediated apoptosis participates in the physiopathology of lupus nephritis, although it is not clear whether it contributes to the development of the tissue damage.Since YY-1 down regulates Fas in cancer cell lines, it is reasonable to consider that this transcription factor may control Fas expression in lupus nephritis. The objective was to determine the correlation between YY-1 and Fas expression in renal biopsies from children with type IV lupus nephritis, and their association with the clinical condition of the patients. MATERIAL AND METHODS: Eighteen biopsies from children with type IV lupus nephritis and 5 controls were studied. Fas and YY-1 expression were determined by immunochemistry and quantified by densytometric analysis. The clinical conditions at the moment the biopsy were obtained from the clinical records and the results were analyzed through a one-way ANOVA with p<0.005. RESULTS: The results of the densytometric analysis showed an inverse relationship between YY-1 and Fas expression. YY-1 was grouped according to the intensity of expression in low, moderate and high and compared with the expression of Fas. The lupus nephritis biopsies, which revealed high expression of YY-1, corresponded to patients with less number of clinical complications,better outcome and fewer alterations on renal function.In contrast, low expression of YY-1 correlated with high Fas expression and worst clinical conditions. CONCLUSIONS: The present study suggests that YY-1regulates Fas expression in lupus nephritis and that it is associated with the clinical outcome of the patients,although further studies are necessary to determine weather it factor may serve as a prognosis factor. This is the first evidence of YY-1 participation in the physiopathology of lupus nephritis.