Regulation of the human oxytocin receptor in the uterus: a molecular approach.
(17/3697)
The oxytocin-oxytocin receptor (OTR) system plays important roles in the human uterus, and the effectiveness of oxytocin is greatly influenced by the pattern of receptor expression in vivo. To investigate OTR expression at the molecular level, we have established a bioassay system for the specific transcripts using Xenopus laevis oocytes, cloned the OTR cDNA, raised anti-OTR antibodies, and characterized OTR genomic clones and systems to study the transcriptional regulation of the gene. Using these molecular tools, we have examined OTR expression in the endometrium and myometrium of non-pregnant and pregnant women. OTR expression appears mainly to be regulated at the transcription level. Analysis of the 5' flanking region of this gene indicates constitutionally active promoter activity when transfected into cultured HeLa and SKN cells. We are currently developing these techniques to analyse OTR regulation in the uterus. (+info)
Uterine peristalsis during the follicular phase of the menstrual cycle: effects of oestrogen, antioestrogen and oxytocin.
(18/3697)
Uterine peristalsis, directing sustained and rapid sperm transport from the external cervical os or the cervical crypts to the isthmic part of the tube ipsilateral to the dominant follicle, changes in direction and frequency during the menstrual cycle, with lowest activity during menstruation and highest activity at mid cycle. It was therefore suggested that uterine peristalsis is under the control of the dominant follicle with the additional involvement of oxytocin. To test this hypothesis, vaginal sonography of uterine peristalsis was performed in the early, mid and late proliferative phases, respectively, of cycles of women treated with oestradiol valerate and with human menopausal gonadotrophin following pituitary downregulation, with clomiphene citrate and with intravenous oxytocin, respectively. Administration of oestradiol valerate resulted in oestradiol serum concentrations comparable with the normal cycle with a simulation of the normal frequency of peristaltic contractions. Elevated oestradiol concentrations and bolus injections of oxytocin resulted in a significant increase in the frequency of peristaltic contractions in the early and mid follicular phases, respectively. Chlomiphene tended, though insignificantly so, to suppress the frequency of peristaltic waves in the presence of elevated oestradiol concentrations. In the late follicular phase of the cycle extremely elevated oestradiol concentrations as well as the injection of oxytocin resulted only in an insignificant further increase of peristaltic frequency. In the normal cycles, as well as during extremely elevated oestradiol concentrations and following oxytocin administration, the peristaltic contractions were always confined to the subendometrial layer of the muscular wall. The results and the review of literature indicate that uterine peristalsis during the follicular phase of the menstrual cycle is controlled by oestradiol released from the dominant follicle with the probable involvement of oxytocin, which is presumably stimulated together with its receptor within the endometrial-subendometrial unit and therefore acting in an autocrine/paracrine fashion. Since unphysiological stimulation with oestradiol and oxytocin did not significantly increase the frequency of uterine peristalsis in the late follicular phase of the cycle it is assumed that normal preovulatory frequency of uterine peristalsis is at a level which cannot be significantly surpassed due to phenomena of refractoriness of the system. (+info)
Decreased apoptosis and sensitivity to macrophage mediated cytolysis of endometrial cells in endometriosis.
(19/3697)
Ectopic dissemination of endometrial cells and their subsequent implantation are the mechanisms involved in the development of endometriosis. While the process of dissemination appears to be a phenomenon common to all women, it is unknown what facilitates or prevents ectopic implantation of misplaced endometrial cells. Prior studies by our group and others suggest that cell-mediated immunity in patients with endometriosis is decreased. The present studies evaluated (i) peripheral blood monocyte (PBM) and peritoneal macrophage (PM) mediated cytolysis of autologous eutopic and ectopic endometrial cells and (ii) programmed cell death (apoptosis) in the eutopic and ectopic endometrium. PBM-mediated cytolysis was (mean+/-SD) 23.1+/-13% for the eutopic and 7.8+/-% for the ectopic endometrium (P < 0.004), while the corresponding percentages for PM-mediated cytolysis were 5.4+/-7 and 0.3+/-1 respectively (P < 0.04). This indicates that PBM are much more effective than PM in inducing cytolysis of both eutopic and ectopic endometrium and that ectopic endometrial cells are significantly more resistant to both PBM- and PM-mediated cytolysis. The apoptosis was significantly decreased in the eutopic endometrium of women with endometriosis as compared to fertile controls (0.375+/-0.17 versus 1.57+/-0.3, P < 0.0001). Furthermore, in matched samples apoptosis was significantly lower in the ectopic (0.149+/-0.075) than eutopic (0.375+/-0.17) endometrium (P < 0.001). We conclude from these studies that the decrease in the capacity of monocytes to mediate cytolysis of the misplaced endometrial cells in the peritoneal locations and an increased resistance of these cells to apoptosis are fundamental to the aetiology and/or pathophysiology of endometriosis. (+info)
Phenotypic and functional studies of leukocytes in human endometrium and endometriosis.
(20/3697)
The aetiology of endometriosis, a common and disabling disorder, is presently unknown, although immune dysfunction could allow ectopic endometrial fragments to survive outside the uterine cavity. These studies investigate the relationship between leukocyte populations, steroid hormone receptor expression, proliferative activity, bcl-2 expression and apoptosis in eutopic and ectopic endometrium from women with endometriosis or adenomyosis at different phases of the menstrual cycle. Significantly increased oestrogen receptor expression, bcl-2 expression and numbers of CD8+ leukocytes were found in ectopic compared with eutopic endometrium in endometriosis, and CD56+ endometrial granulated lymphocytes (eGLs) were significantly reduced in ectopic endometrium. Apoptotic cells were rarely found in control and subject endometria. In contrast with endometriosis, adenomyotic lesions showed identical steroid hormone receptor expression, proliferative activity, bcl-2 expression and leukocyte subpopulations to eutopic endometrium, indicating different aetiologies for these disorders. The unusual CD56+ CD16- eGLs present in large numbers in late secretory phase eutopic endometrium were highly purified (>98%) by immunomagnetic separation. Except for a negligible cytotoxic activity of eGLs from early proliferative samples, cytotoxic activity of eGLs from non-pregnant endometrium during the menstrual cycle was comparable with those in peripheral blood, predominantly CD56+ CD16+ natural killer cells. eGLs from non-pregnant endometrium and early pregnancy showed a variable proliferative response to 5 and 100 U/ml interleukin-2 over 48-h and 120-h time courses. eGLs are evidently functionally important in the eutopic endometrium. Their absence in endometriotic lesions together with increased CD+8 T-cell numbers and increased oestrogen receptor and bcl-2 expression may have significant effects on the development and progression of endometriosis. (+info)
Expression pattern of integrin adhesion molecules in endometriosis and human endometrium.
(21/3697)
Integrins are cell adhesion molecules that undergo cell-specific dynamic changes during the normal menstrual cycle in the human endometrium. Here, using immunohistochemistry, we have investigated the expression pattern of the integrins alphav, alpha2beta1, alpha3beta1, alpha3, alpha6, beta1, beta2 and beta3 in the human ectopic endometrium of 30 patients and in nine cases in the corresponding eutopic endometrium. The biopsies were obtained during the early or late follicular phase (25 cases), during the corpus luteum phase (four cases) and in one case after 6 months' treatment with a gonadotrophin releasing hormone (GnRH) agonist. The integrin expression was independent of the ovarian steroid situation at the time of biopsy. The integrin alpha6 was expressed in all endometriotic and endometrium samples. The integrin alpha3 was absent in all endometrium tissues of patients with endometriosis. However, the corresponding endometriotic lesions re-expressed this adhesion molecule in 15 cases. No change in integrin beta3 expression pattern could be demonstrated in either endometriotic lesions or endometrium samples, regardless of the menstrual cycle phase. A correlation between serum oestradiol and progesterone concentrations and the expression of the investigated integrins was not observed, thus indicating that these two hormones play a minor role in the regulation of the cell adhesion molecules examined. Our investigation suggests that endometriosis is a dedifferentiated disease as it expressed different integrins in comparison with the eutopic endometrium, and independently of the hormonal situation. The ability of endometriotic tissues to express integrins may explain the high recurrence rates in patients with endometriosis, as these samples retain their adhesion potency after retrograde menstruation and are thus able to establish cell-cell and cell-matrix interactions with the surrounding peritoneum. (+info)
Tracing cellular and molecular mechanisms involved in endometriosis.
(22/3697)
The aetiology and pathogenesis of endometriosis, defined as the presence of endometrium-like tissue outside the uterine cavity, is largely unknown. In this paper we present and discuss possibilities to study the putative pathogenic properties of endometriotic cells in vitro. The current focus of our investigations is on the invasive phenotype of the disease, assuming that this might contribute to the pathogenesis of endometriosis. So far, we have shown that: (i) cytokeratin-positive and E-cadherin-negative endometriotic cells have an invasive phenotype in a collagen invasion assay in vitro similar to metastatic carcinoma cells; (ii) the invasiveness of endometriotic but not of eutopic endometrial cells can be stimulated by a heat-stable protein present in peritoneal fluid; and (iii) the endometriotic cell line EEC145T, which we established, may be a useful tool for the identification of gene products which are, positively or negatively, invasion-related. Finally, our studies suggest that the invasive phenotype in endometriosis shares aspects with tumour metastasis, but might also have unique mechanisms. (+info)
Extracellular matrix remodelling in the endometrium and its possible relevance to the pathogenesis of endometriosis.
(23/3697)
Essential features of endometrial physiology involve the extracellular matrix (ECM). In the pathogenesis of endometriosis, interactions of endometriosis cells with ECM can be postulated. Two systems of secreted proteases in the endometrium, the plasmin(ogen) activator/inhibitor and the matrix metalloproteinases and their inhibitors were examined in cell cultures of uterine endometrial cells from women with and without endometriosis. Soluble urokinase receptor secretion is increased, and mRNA transcription of tissue inhibitor of metalloproteinases-2 (TIMP-2) is upregulated by progestin in endometriosis. These findings are compatible with an altered ECM turnover in the endometrium of these patients that may explain a higher invasive potential of retrogradely menstruated endometrial fragments. (+info)
Angiogenesis: a new theory for endometriosis.
(24/3697)
Excessive endometrial angiogenesis is proposed as an important mechanism in the pathogenesis of endometriosis. Evidence is reviewed for the hypothesis that the endometrium of women with endometriosis has an increased capacity to proliferate, implant and grow in the peritoneal cavity. Data is summarized indicating that the endometrium of patients with endometriosis shows enhanced endothelial cell proliferation. Results are also reviewed indicating that the cell adhesion molecule integrin alphavbeta3 is expressed in more blood vessels in the endometrium of women with endometriosis when compared with normal women. Taken together, these results provide evidence for increased endometrial angiogenesis in women with endometriosis when compared with normal subjects. Endometriosis is one of the family of angiogenic diseases. Other angiogenic diseases include solid tumours, rheumatoid arthritis, psoriasis and diabetic retanopathy. Excessive endometrial angiogenesis suggests novel new medical treatments for endometriosis aimed at the inhibition of angiogenesis. (+info)