FRI0226 LOW EXPRESSION OF ESTROGEN RECEPTOR BETA IN RENAL TUBULAR EPITHELIAL CELL MAY CONTRIBUTE TO HYPERURICEMIA IN PREMENOPAUNITED STATES OF AMERICAL FEMALE SYSTEMIC LUPUS ERYTHEMATOSUS PATIENTS

Abstract

Background We have reported that the incidence of hyperuricemia of young female systemic lupus erythematosus (SLE) patients was higher than that of healthy young women[1].Whether the estrogen receptor (ER) expressed in renal tubular tissue contributes to it? There are few reports yet. Objectives To investigate the expression of ERs in the renal tubular cells and their relationship with serum uric acid (UA) levels in premenopausal female SLE patients. Methods Eighteen kidney biopsy specimens of premenopausal female SLE patients served as the lupus nephritis group (LN group), and 12 specimens of premenopausal female IgA nephropaty patients served as the IgA group. Serum UA levels and kidney index were collected, and the expression of ERs in the renal tubular epithelial cell of the two groups were determined by immunohistochemistry. According to the percentage of the positive stained cells, the semiquantitative analysis was made. The expressions of ERs, including ERα and ERβ, of the two groups were compared, and the relationship between the expression of ERs and serum UA levels were analyzed with linear regression analysis. Results 1. The mean ages of the LN group and the IgA group were 27.39±8.09 years and 33.08±5.45 years, respectively, with significantly different (t=2.128, p=0.042). There was no renal failure subject in both groups (CRE level above 120μmol/l), and all the SLE patients were at stage of onset. 2. Mean UA level of the LN group was significantly higher than that of the IgA group (t=-3.149, P=0.004), and the CRE level of the two groups were similar (t=-0.109, P=0.914) (table1). 3. In each group, ERβ was well expressed in the tubular epithelial cells, and no in kidney glomeruli. In contrast, ERα was not expresssed in the renal tissues of both groups (figure1). 4. The median score of ERβ expression in the LN group was remarkable lower than that of the IgA group (z=-2.080, P=0.038, table 1). 5.Linear regression analysis indicated that ERβ expression scores of the total 30 patients had significantly negative correlation with serum UA levels (t=-2.141, P= 0.041, table2). Conclusion 1. Low expression of ERβ in renal tubular epithelial cell may contribute to hyperuricemia in premenopausal female SLE patients. 2. ERα showed no expression in LN and IgA nephropaty kidney tissues.