Levent M. Senturk

Leukemia inhibitory factor in human reproduction.

PROBLEM: Leukemia inhibitory factor (LIF) is a pleiotropic cytokine of the interleukin‐6 family and has different biological actions in various tissue systems. Although named for its ability to inhibit proliferation of a myeloid leukemic cell line by inducing differentiation, it also regulates the growth and differentiation of embryonic stem cells, primordial germ cells, peripheral neurons, osteoblasts, adipocytes, and endothelial cells. LIF is crucial for successful implantation of the embryo in mice. Currently, there is an accumulation of data about the role of LIF in human reproduction.

Thin endometrium in assisted reproductive technology.

Purpose of review To review the etiology, diagnosis and clinical importance of thin endometrium during assisted reproductive technology cycles and to find out better ways to deal with it. Recent findings Precise and specific endometrial maturational development is crucial in allowing implantation following assisted reproduction. As endometrial biopsy is invasive and hormonal milieu assessment inaccurate, the need to evaluate endometrial development encouraged the use of high-resolution ultrasonography as an alternative non-invasive method of assessment for uterine receptivity. Ultrasonographic endometrial thickness measurement, endometrial pattern investigation, endometrial volume computation, uterine and subendometrial blood flow analysis by Doppler sonography are just some of the methods that we can utilize to have an idea of uterine receptivity and consequently to better predict pregnancy outcome following assisted reproductive technology cycles. There is a lot of debate on the administration of low-dose aspirin, estrogen, vaginal sildenafil citrate, pentoxifylline, vitamin E, and gonadotropin-releasing hormone agonist for the management of thin endometrium with an aim to increase the pregnancy and implantation rates in assisted reproductive technology cycles. Summary Various recent modalities proposed for the treatment of thin endometrium seem to be useless and inefficient from an evidence-based medicine point of view. At the moment, evaluation of endometrium using different ultrasonographic markers seems to be superior to all those therapies.

The impact of body mass index on assisted reproduction

Purpose of review Obesity is a worldwide problem. The effect of obesity on the outcome of assisted reproductive techniques is quite controversial. Recent findings Although there is not an absolute consensus based on evidence, obesity may lengthen the duration of ovulation induction, increase the gonadotrophin dose, decrease the peak estradiol levels, number of mature follicles and number of oocytes retrieved, and increase the cycle cancellation rate. Moreover, obesity may have a negative impact on oocyte and embryo quality. Thus, fertilization, embryo transfer, implantation and pregnancy rates have been usually found to be low in many studies. In addition, oocyte retrieval and embryo transfer procedures can be difficult due to obesity itself. Finally, miscarriage rate is found to be high. None of the studies related with obesity and assisted reproduction has been designed as a randomized controlled trial, yet. Definition of obesity, cause of infertility, protocols used for ovulation induction, starting dose for gonadotrophins, oocyte and embryo-grading systems are not standardized among the studies. Some confounding factors, such as polycystic ovary syndrome status and age, are not taken into consideration. Summary Obesity has a negative impact on the outcomes of assisted reproductive techniques.

Immunology of endometriosis

Endometriosis is classically described as the presence of both endometrial glandular and stromal cells outside the uterine cavity, mainly in the pelvis. The pathogenesis of this enigmatic disorder still remains controversial despite extensive research. Although multiple theories have been put forth to explain the pathophysiology and pathogenesis of endometriosis, the retrograde menstruation theory of Sampson is the most widely accepted. However, since retrograde menstruation occurs in most of the reproductive age women, it is clear that there must be other factors which may contribute to the implantation of endometrial cells and their subsequent development into endometriotic disease. There is substantial evidence to support that the alterations in both cell-mediated and humoral immunity contribute to the pathogenesis of endometriosis. Increased number and activation of peritoneal macrophages, decreased T cell and natural killer (NK) cell cytotoxicities are the alterations in cellular immunity and result in inadequate removal of ectopic endometrial cells from the peritoneal cavity. Moreover, increased levels of several cytokines and growth factors which are secreted by either immune and endometrial cells seem to promote implantation and growth of ectopic endometrium by inducing proliferation and angiogenesis. In addition to the impaired capacity of the immune cells to mediate endometrial cell removal, inherent resistance of the ectopic endometrial cells against immune cells is another interesting concept in the pathogenesis of endometriosis. Endometriosis has also been considered to be an autoimmune disease, since it is often associated with the presence of autoantibodies, other autoimmune diseases, and possibly with recurrent immune-mediated abortion.

Basic fibroblast growth factor: peritoneal and follicular fluid levels and its effect on early embryonic development.

OBJECTIVE To investigate the effect of basic fibroblast growth factor (FGF) on preimplantation embryos and to evaluate the levels of basic FGF in follicular and peritoneal fluid. DESIGN Prospective study. SETTING University-based laboratory. PATIENT(S) Follicular fluids (FFs) were obtained from women undergoing ovulation induction (n = 62) and peritoneal fluids were obtained from women with (n = 49) or without (n = 12) endometriosis. INTERVENTION(S) The effect of basic FGF on mouse embryos was assessed. Basic FGF concentrations were measured in pre-hCG and post-hCG FFs and in peritoneal fluids. MAIN OUTCOME MEASURE(S) Two-cell murine embryos were treated with basic FGF and followed for the rate of blastocyst formation and embryo hatching. Follicular and peritoneal fluid basic FGF levels were measured by ELISA. RESULT(S) Basic FGF (10 ng/mL) decreased the rate of blastocyst formation and embryo hatching. The level of basic FGF did not change in the FF around ovulation, and there was no correlation between FF basic FGF levels and reproductive parameters, with the exception of age. The levels of basic FGF in the peritoneal fluid of women with or without endometriosis were not different. CONCLUSION(S) Basic FGF is present in follicular and peritoneal fluids, but its concentration in these fluids does not change during the menstrual cycle or in the presence of endometriosis. Basic FGF inhibits murine preimplantation embryonic development at concentrations 10-100 times higher than the levels detected in follicular and peritoneal fluids.

Chemokine Receptor Expression in Human Endometrium

Abstract Chemokines play a role in endometrial physiology and pathology and may affect endometrial receptivity and menstrual shedding. Chemokines exert their effect by binding to their relevant receptors, the expression levels of which may modulate their action. In the present study, we examined the expression of chemokine receptors CXCR1 and CXCR2 (receptors for interleukin-8) and CCR5 (receptor for RANTES [regulated-on-activation, normal-T-cell-expressed and -secreted], macrophage inflammatory protein [MIP]-1α, and MIP-1β) in human endometrium. Human endometria (n = 35) were grouped according to the menstrual cycle phase and examined by immunohistochemistry for CXCR1, CXCR2, and CCR5. In both epithelial and stromal cells, CXCR1 and CXCR2 immunoreactivity was detected. Staining was most prominent at the apical and basal aspects of epithelial cells. Intense CCR5 immunostaining was observed in epithelial and stromal compartments throughout the menstrual cycle. Epithelial and stromal staining for CXCR1 reached a peak at the midsecretory phase, during which it was significantly higher than the level of staining during the proliferative phase (P < 0.05). Immunostaining for CXCR2 and CCR5 showed no significant variation across the menstrual cycle. Expression of interleukin-8 and RANTES in endometrium, together with the presence of their receptors, suggests that autocrine and paracrine interactions involving these chemokines may participate in endometrial physiology.

Expression of aminopeptidase N in human endometrium and regulation of its activity by estrogen

OBJECTIVES To determine whether aminopeptidase N (APN) regulates the cycle-dependent bioavailability of interleukin-8 (IL-8) in the endometrium. DESIGN Prospective study. SETTING University medical center. PATIENT(S) Women without endometrial pathology from the proliferative (n = 25) or secretory (n = 18) phase of the menstrual cycle. INTERVENTION(S) We first immunolocalized APN in the endometrium using an anti-APN antibody. We then determined the regulation of APN kinetic activity by sex steroids in endometrial stromal cell cultures. MAIN OUTCOME MEASURE(S) Expression of APN in human endometrium throughout the menstrual cycle. Regulation of APN activity by estradiol and progesterone in cultured endometrial stromal cells. RESULT(S) Immunohistochemistry of endometrial sections revealed staining of endometrial stroma throughout the menstrual cycle. There was no detectable staining in glandular cells. The expression of APN as detected by immunohistochemistry was significantly lower in the early proliferative phase. In cultured cells, estradiol inhibited APN activity in a concentration-dependent manner. Progesterone did not have a significant effect. CONCLUSION(S) Stromal localization of APN in endometrium may explain the epithelial rather than stromal presence of IL-8 in vivo. Decreased expression of APN may increase IL-8 bioavailability thus contributing to angiogenesis and polymorphonuclear leukocyte chemotaxis in early proliferative phase.

The effect of monocyte chemotactic protein 1 in intraperitoneal adhesion formation in a mouse model

OBJECTIVE Intraperitoneal adhesions are a significant cause of morbidity among women of reproductive age. Monocyte chemotactic protein 1 plays a role in the chemotaxis of mononuclear cells and fibroblasts into the peritoneal injury site. To evaluate its role in intraperitoneal adhesion formation, we used an established postsurgical adhesion model in mice. STUDY DESIGN Surgical adhesions in mice were induced by scraping and crushing peritoneal sites. We analyzed the injury sites for the temporal expression of monocyte chemotactic protein 1 messenger ribonucleic acid and cellular infiltration at 12 to 24 hours across 10 days and evaluated the effects of monocyte chemotactic protein 1 and anti-monocyte chemotactic protein 1 neutralizing antibody on adhesion formation. On induction of adhesions animals were randomly assigned to 1 of 4 groups: (1) control, (2) nonspecific immunoglobulin G, (3) monocyte chemotactic protein 1, (4) anti-monocyte chemotactic protein 1 antibody. Animals received daily intraperitoneal injections for 6 days. Adhesions were scored on day 14 and immunostained for fibroblasts and macrophages. RESULTS Adhesions developed consistently by the fifth postoperative day. We detected an increase in monocyte chemotactic protein 1 messenger ribonucleic acid expression at 48 hours; this remained until the fourth postoperative day. By the second day macrophages were present at the injury site. Animals treated with anti-monocyte chemotactic protein 1 antibody had significantly fewer adhesions develop than did the other three groups. CONCLUSION This study demonstrates that monocyte chemotactic protein 1 may play a role in adhesion formation. Inhibiting the action of this chemokine may help to prevent adhesions.

The Peritoneal Fluid Levels of Interleukin‐12 in Women with Endometriosis

PROBLEM: Interleukin‐12 (IL‐12) is produced mainly by monocytes/macrophages, and it induces proliferation and cytotoxicity of T‐cells and natural killer cells. In women with endometriosis, natural killer cell activity in the peritoneal fluid is significantly decreased. We aimed to measure the peritoneal fluid level of IL‐12 in endometriosis.

Expression of Proliferative and Preapoptotic Molecules in Human Myometrium and Leiomyoma Throughout the Menstrual Cycle

The pathogenesis of leiomyoma may be related to an imbalance in the interaction of sex steroids with paracrine growth factors that may control the modulation of mitogenesis and local immunity. The authors investigate the temporal and spatial expression of proliferative and preapoptotic molecules that may participate in the modulation of myometrial function and leiomyoma pathogenesis. Immunohistochemistry and Western blot analysis are used to investigate Fas ligand (FasL), phosphatase and tensin homolog deletion on chromosome 10 (PTEN), and proliferating cell nuclear antigen (PCNA) expression in myometrium and leiomyoma. Western blot results show that in the secretory phase, FasL expression is 1.8-fold and 2.3-fold higher compared with the proliferative phase in the myometrium and leiomyoma, respectively (P = .022 and .047, respectively). A paired comparison between myometrium and leiomyoma reveals higher FasL expression in the leiomyoma (P = .003). On the contrary, when compared with the secretory phase, PCNA expression during the proliferative phase is 4.6-fold and 3.7-fold higher in the myometrium and leiomyoma, respectively (P = .041 and .034, respectively). A paired comparison between myometrium and leiomyoma reveals higher PCNA expression in the leiomyoma. Furthermore, lower PTEN expression is detected in the leiomyoma compared with the myometrium (P < .032). Immunohistochemistry results reveal that FasL, PTEN, and PCNA are expressed in the myometrium and leiomyoma, consistent with the results from the Western blot analysis. The results suggest that FasL, PTEN, and PCNA may be involved in the pathophysiology of leiomyoma. A higher FasL level in the leiomyoma is likely to correspond to suppression of local immunity by inducing apoptosis of immune cells, while a higher level of PCNA and a lower level of PTEN may be related to increased mitogenesis and decreased apoptosis in leiomyoma.