The human uterine cervix is a fibrous organ with a high connective tissue content. An extensive remodeling of the connective tissue prior to parturition, i.e., cervical ripening, requires the presence of proteolytic enzymes. The exact mechanism of cervical ripening has not been clarified. We evaluated in vivo distribution and expression of matrix metalloproteinases 2 and 9 (MMP-2 and MMP-9) in the human cervix at term pregnancy and immediately after parturition compared with the nonpregnant state. Cervical biopsies were obtained from term pregnant, postpartum, and nonpregnant women. MMP-2 and MMP-9 proteins were localized by immunohistochemistry. Messenger RNA levels of MMP-2 and MMP-9 were evaluated by relative quantitative reverse transcription-polymerase chain reaction (RT-PCR) using an invariable internal standard. The mRNA levels of MMP-2 and MMP-9 were increased in the cervix at term pregnancy and postpartum compared with the nonpregnant state. Cervical stromal fibroblasts and smooth muscle cells were identified as main sources of MMP-2, whereas the MMP-9 protein was observed exclusively in invading leukocytes. These data indicate the involvement of MMP-2 and MMP-9 in the cervical ripening process.

Major reproductive events such as menstruation, ovulation, implantation, and cervical ripening are characterized by an increased number of invading leukocytes in the tissues. Sex steroid hormones, particularly estrogens, play an important role in these dynamic changes in the female reproductive tract. Estrogens have also been implicated in the pathogenesis of many common pathological conditions associated with leukocyte infiltration and immunological dysfunction, such as autoimmune diseases and atherosclerosis. Although the two estrogen receptor (ER) subtypes, ERa and ERb, have been found in different leukocyte populations in tissues and in peripheral blood, there is still very little known about functional activity and importance of ERs in blood cells. To elucidate the different roles for ERa and ERb in peripheral blood leukocytes, we used microarray gene expression profiling of rat peripheral blood leukocytes subjected to in vivo treatment with estradiol (E 2 ), the selective ERa agonist 4,4 0 ,4 00 -(4-propyl-[1H]-pyrazole-1,3,5-triyl)trisphenol (PPT), and the selective ERb agonist 2,3-bis(4-hydroxyphenyl)-propionitrile (DPN). We report the identification of genes that were commonly regulated by E 2 , PPT, and DPN, and genes that were regulated either by the ERa or ERb agonist. Further confirmatory analyses of the selected regulated genes 12-lipoxygenase, fibulin-1, furin, and calgranulin B are also presented. These results were then compared with those from the uterine tissue of the same animals. Our study demonstrates that peripheral blood leukocytes are responsive to estrogens. E 2 and selective ERa and ERb agonists regulate a number of genes that may contribute to inflammation and remodeling of the extracellular matrix.

Our study demonstrates the presence of ERalpha and ERbeta in PBMC and PMN cells from female and male donors. The ERalpha and ERbeta genes have complex transcriptional profiles, with many receptor variant isoforms being expressed. Considering the diversity of ER isoforms in leucocyte subtypes, we conclude that the expected effect of oestrogen would be highly cell type-specific. Further studies are needed to test the functional activity of ER isoforms and their relation to disease.

Cervical ripening during parturition is associated with rapid production of catabolic enzymes by invading leukocytes and increased collagen metabolism. The recruitment of leukocytes is regulated by various factors including inflammatory mediators, prostaglandins and matrix metalloproteinases. Sex steroids may be indirectly or directly involved in this process. This study aimed to evaluate the expression of oestrogen receptor beta (ER beta) in blood cells infiltrating the cervix during pregnancy and parturition. Cervical biopsies were obtained from term pregnant, post-partal and non-pregnant women. The ER beta protein and leukocyte markers CD45 and CD68 were evaluated by single and double labelling immunohistochemistry. Quantitative values were assessed using a microscope and a high-resolution camera connected to a computer with image analysis program. The number of CD45(+) and CD68(+) cells in the cervix increased in term pregnancy and post-partum compared with the non-pregnant state. The ER beta antigen was co-localized with CD45 leukocyte common antigen and CD68 macrophage specific antigen in blood leukocytes infiltrating the cervical tissue. The presence of ER beta in the cervical leukocytes suggests that oestrogen may directly regulate leukocyte functions in the cervix.

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The concept of a blockade of progesterone during human pregnancy and withdrawal of this blockade at parturition remains controversial There is no sharp fall in serum progesterone before parturition, but treatment with an antiprogestin is successful for labor induction at term pregnancy. The human progesterone receptor (PR) exists in two isoforms (PR-A and PR-B), mediating different biological responses. Here, the hypothesis of a progesterone withdrawal at parturition in terms of a change in PR isoforms was tested. Cervical biopsies were obtained at term before the onset of labor, immediately after parturition and from non-pregnant women. Solution hybridization showed a tendency for the PR mRNA level to be decreased at parturition. Immunohistochemistry displayed decreased PR(A + B) and PR-B levels (p < 0.05) immediately after parturition. The relative importance of PR-A seemed higher immediately after parturition as compared to its importance in non-pregnant and term pregnant women. Our results are consistent with the concept of a functional progesterone blockade at the receptor level at term pregnancy, and withdrawal of this blockade at parturition. These observations may have important clinical and therapeutic implications.

Background: Cervical ripening is an inflammatory reaction. The glucocorticoid receptor (GR) mediates glucocorticoid antiinflammatory reactions, whereas nuclear factor (NF)kappaB is a key pro-inflammatory transcription factor. Prostaglandins as well as platelet activating factor (PAF) are inflammatory mediators. Inducible nitric oxide synthase (iNOS) regulates the level of nitric oxide (NO) in response to various inflammatory stimuli. We hypothesize that a changed biological response to glucocorticoids could be a mechanism regulating the inflammatory events resulting in cervical ripening.

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