DIFFERENTIAL EXPRESSION AND REGULATION OF CYTOKINE GENES IN THE MOUSEUTERUS

The present investigation examined the differential expression of cyto kine genes in vivo and in vitro in the mouse uterus and their regulati on by ovarian steroid hormones. The expression of interleukin-1 beta ( IL-1 beta), IL-1 alpha, IL-6, and tumor necrosis factor-alpha (TNF alp ha) genes was examined in the mouse uterus as well as in freshly isola ted or cultured epithelial cells by Northern blot and in situ hybridiz ation. In the day 1 pregnant (D1 = vaginal plug) uterus, the levels of IL-1 alpha and IL-1 beta messenger RNAs (mRNAs) were abundant, wherea s those of TNF alpha and IL-6 were at the limits of detection. Freshly isolated D1 uterine epithelial cell preparations contained higher lev els of IL-1 alpha and IL-1 beta mRNAs than those observed in the D1 wh ole uterus, whereas TNF alpha and IL-6 mRNA levels were consistently l ow. In contrast, D1 epithelial cells showed decreased levels of IL-1 b eta mRNA after 1 day of culture, whereas the levels of IL-1 alpha and IL-6 mRNAs increased under similar conditions. The levels of IL-1, IL- 6, and TNF alpha mRNAs were at the limits of detection in the D4 whole uterus or freshly isolated diestrous epithelial cells. However, IL-1 alpha and IL-6; mRNA levels in diestrous epithelial cells, like those in D1 epithelial cells, increased in culture. In contrast, IL-1 beta a nd TNF alpha mRNA levels remained low in cultured epithelial cells. In situ hybridization was used to examine the cell type-specific express ion of IL-1 alpha or IL-6 mRNA in uterine sections and cultured cells. Although hybridization signals for IL-1 alpha mRNA were detected in u terine epithelial cells on D1 of pregnancy, IL-6 mRNA could not be det ected. IL-1 alpha and IL-6 mRNAs could not be detected in freshly isol ated diestrous epithelial cells, although a majority of the epithelial cells showed hybridization signals for these mRNAs after 2 or 4 days of culture. The effects of steroid hormones on uterine cytokine gene e xpression were examined by Northern blot and in situ hybridization. In adult ovariectomized mice, an injection of 17 beta-estradiol (E(2)), progesterone (P-4), or a combination of E(2) and P-4 had little or no apparent effect on these cytokine mRNA levels. The results establish t hat uterine epithelial cells on D1 of pregnancy exhibit heightened exp ression of IL-1 alpha in culture. In contrast, these cells express lit tle or no IL-6 mRNA in vivo, but show heightened expression in culture . These results suggest that an apparent loss of repression of these u terine genes occurs in culture. Furthermore, E(2) and/or P-4 treatment s appear to have little or no effect on uterine cytokine mRNA levels i n adult ovariectomized mice.