Implantation: The correlation of placental protein 14 concentrations in uterine flushing and endometrial morphology in the peri-implantation period

The relationship between the concentrations of placental protein14 (PP14) in uterine flushing and the endometrial morphologyin the mid-luteal phase was assessed in a prospectively designedstudy involving the precise timing of all samples by the luteinizinghormone (LH) surge. A total of 29 regularly cycling women withunexplained infertility or recurrent miscarriage were studied.To flush the uterine cavity, 10 ml of physiological saline solutionwas used immediately prior to sampling of an endometrial specimenfor morphological study, in the mid-luteal phase. PP14 concentrationswere measured by radioimmunoassay in uterine flushings and plasmasamples; the endometrium was assessed by the use of histologicaldating criteria and morphometric techniques. PP14 levels inuterine flushings were correlated with endometrial dating andvolume fraction measurement of the glands. They were consistentlybelow the sensitivity of the assay with histological datingof < day LH +5, or when the glandular lumen occupied <20%of the gland. In contrast, PP14 concentrations in plasma werenot related to histological dating or morphometric analyses,and did not differ in patients with normal endometrial development(20.8 ng/ml) and in those with retarded endometrial development(22.5 ng/ml). The presence of detectable concentrations of PP14in uterine flushing was significantly associated with normalhistological dating. Uterine flushing may therefore providea reliable, non-invasive alternative to endometrial biopsy inthe evaluation of endometrial function in the peri-implantationperiod.     

Psoriasin, a calcium-binding protein with chemotactic properties is present in the third trimester amniotic fluid

Psoriasin is a small calcium-binding protein first found in psoriatic lesions and also up-regulated in other inflammatory skin diseases and cancer tissues. Psoriasin is also present in the fetal epithelial cells. Its biological function is unclear, but there is both in vitro and in vivo evidence for its chemokine-like activity. The aim of the present study was to find whether psoriasin could be found in the amniotic fluid and thus could have long-range immunobiological effects. Two recombinant psoriasins were prepared, one in Escherichia coli, the other one in Pichia pastoris. The former was used to produce a rabbit antiserum against psoriasin. Fractionation of full-term amniotic fluids with polyacrylamide gel electrophoresis (PAGE) and gel filtration associated with immunodetection with the antiserum were used to identify a protein compatible with the size of psoriasin. The identity of psoriasin was further verified by mass spectrometric analysis. Expression of psoriasin in cells of the amniotic membranes was detected with nested RT-PCR. Because of its chemokine-like activity, psoriasin present in the amniotic fluid might have consequential immunobiological effects during the fetal development.     

Suppression of prolactin secretion during ovarian hyperstimulation is followed by elevated serum levels of endometrial protein PP14 in the late luteal phase

A double-blind placebo-controlled study on bromocriptine administrationduring days 2-12 of ovarian hyperstimulation for in-vitrofertilization(IVF) showed that, in bromocriptine cycles, levels of the endometrialprotein PP14 were higher in the late luteal phase. This wasverified both by calculating forward from the day of human chorionicgonadotrophin (HCG) administration and backward from the onsetof the next period. Bromocriptine had no effect on IVF performance.During bromocriptine treatment the serum prolactin levels declinedand serum oestradiol levels were higher on day 9 of the cycle.There was a positive correlation (r =0.55; P = 0.012) betweenthe serum oestradiol levels on day 9 and the PP14 levels ondays 22-23 of the cycle. No difference was found in the lutealphase progesterone levels between bromocriptine-and placebo-treatedcycles. These results suggest that low prolactin and/or highoestradiol levels during the follicular phase have an influenceon the subsequent secretory capacity of the endometrium as reflectedby secretion of a specific endometrial protein     

Molecular aspects of implantation: Variation in the expression of cellular retinoid binding proteins in human endometrium throughout the menstrual cycle

Human endometrium is a glandular epithelial tissue with a substantialunderlying stroma. Under the influence of ovarian steroids,endometrium undergoes a cyclical pattern of proliferation followedby secretory differentiation. Since retinoids promote the differentiationof many epithelia to secretory phenotypes they may be involvedin controlling the secretory differentiation of human endometrialepithelium. Cytosolic binding proteins for retinol (cellularretinol binding protein) and retinoic acid (cellular retinoicacid binding protein) may play an important part in regulatingthe availability of retinoic acid to its nuclear receptors andwe have therefore asked whether expression of mRNA for theseproteins varies in relation to endometrial differentiation.In a series of 54 endometrial biopsies, both endometrial epithelialand stromal cells expressed mRNA for cellular retinol bindingprotein type I at a constant level throughout the menstrualcycle. Cellular retinoic acid binding protein type II was alsoexpressed but the level of expression varied dramatically, beingelevated in the proliferative phase and depressed during thesecretory phase of the menstrual cycle in both epithelial andstromal cells. These data suggest that cytosolic binding proteinsmodulate the supply of retinoic acid to the nuclei of endometrialcells during the menstrual cycle and that retinoic acid is involvedin the cyclical control of endometrial differentiation.     

Endometrial TIMP-4 mRNA is expressed in the stroma, while TIMP-4 protein accumulates in the epithelium and is released to the uterine fluid

We have previously reported that endometrial mRNA expression of both tissue inhibitors of metalloproteinase-4 (TIMP-4) and matrix metalloproteinase-26 (MMP-26) peaks in the early secretory phase, which implies a role in implantation. The objective of this study was to compare the distribution of TIMP-4 and MMP-26 in endometrial tissue and uterine fluid over the menstrual cycle. Endometrial tissue was analysed with in situ hybridization and immunohistochemistry to localize mRNA and protein for TIMP-4 and MMP-26 in the same set of samples. TIMP-4 mRNA was quantified in separated stromal and epithelial cells using real-time PCR. Uterine fluid was analysed with western blotting. TIMP-4 mRNA was exclusively localized to the stroma, whereas MMP-26 mRNA was expressed by epithelial cells. TIMP-4 protein was only occasionally found in the stroma but was consistently present in granules of the apical part of luminal and glandular epithelial cells. TIMP-4, but not MMP-26, was demonstrated in uterine fluid. Thus, TIMP-4 is produced in the stroma only, secreted by stromal cells, taken up by epithelial cells, accumulated in apical granules and finally secreted to the uterine fluid. Maximal expression of MMP-26, and its strongest inhibitor TIMP-4, in the early and mid-secretory phase suggests a role during implantation. MMP-26 is stored in epithelial cells in its active form, is not released spontaneously and is controlled by TIMP-4 in both stroma and uterine fluid.     

Steroid Production by the cumulus: relationship to fertilization in vitro

Insemination media were Collected from 92 follicles of 14 patientsstimulated to progesterone and oestradiol in the inseminationdrops were assayed, corrected for carry–over from follicularfluid and volume and expressed as production per µg ofprotein in the cumulus. significantly higher progesteron productionper unit protein was associated with oocytes which fertilizedin vitro (P << 0.02). Oocytes fertilizing with subsequentfragmentation or degeneration showed progesterone levels significantlyhigher than oocytes fertilizing normaly (P << 0.05). Polyspermicoocytes ( n = 3 ) were associated with very high levels of progesteroneproduction but were not significantiy different due to the lownumbers. Oestradial production per unit protein was significantlygreater in oocytes which degenerated (P << 0.05). TheProtein content of cumuli whose oocytes fertilized appearedto be significantly lower than those which did not (P <<0.05). these results probably reflect the maturity of the folliclealthough direct actions of cumulus products upon gametes cannotbe ruled out.     

Circulating concentrations of the antiprogestins CDB-2914 and mifepristone in the female rhesus monkey following various routes of administration

The overall aim of these studies was to investigate the oral and i.m. bioavailability of CDB-2914 in intact female rhesus monkeys, and to compare the serum concentrations of CDB-2914 with that of mifepristone following oral administration. In the first study, a 50 mg bolus of CDB-2914 per monkey was administered intravenously, orally or intramuscularly. The area under the serum concentration-time curve for 72 h (AUC(0-72)) following i.v. injection was 18 320 +/- 2718 ng/ml*h, and that for oral administration was 10 464 +/- 3248 ng/ml*h. Thus, the oral bioavailability of CDB-2914 equivalents was 56%. The AUC(0-168 h) following i.m. injection was 11 226 +/- 1130 ng/ml*h. Therefore, the i.m. bioavailability of CDB-2914 equivalents was 62%. In the second study, the serum concentrations of CDB-2914 and mifepristone equivalents were compared following an oral bolus dose in two different formulations. When administered at 5 mg/kg in aqueous suspending vehicle (ASV), the mean peak serum concentration (C(max)) of CDB-2914 equivalents (192 +/- 64 ng/ml) occurred at 5 +/- 1 h, whereas the C(max) of mifepristone equivalents (82 +/- 25 ng/ml) occurred at 3 +/- 1 h. Following administration in gelatin capsules (35 mg/monkey), the C(max) of CDB-2914 equivalents (129 +/- 24 ng/ml) occurred at 5 +/- 1 h, while the C(max) of mifepristone equivalents (31 +/- 8 ng/ml) occurred at 3 +/- 1 h. The serum concentration (AUC(0-120 h)) of CDB-2914 equivalents was 4.7- or 5. 3-fold greater than that of mifepristone equivalents when administered orally in ASV or gelatin capsules respectively. The serum protein binding characteristics of CDB-2914 were also studied. CDB-2914 bound to human alpha(1)-acid glycoprotein (AAG), but not with as high an affinity as mifepristone. In contrast, neither CDB-2914 nor mifepristone bound with high affinity to AAG, corticosteroid binding globulin or sex hormone binding globulin in monkey serum. Collectively, these results indicated that CDB-2914 was more efficiently absorbed than mifepristone following oral administration to female rhesus monkeys.     

Stress proteins in the human endometrium and decidua

Protein synthesis in response to heat shock was induced in theproliferative and secretory human endometrium as well as inhuman decidua during a 2-h incubation period at 41°C. Amajor 70 K stress protein and two minor stress proteins of 88and 94 K were detected after [³⁵S]methionlne incorporation followedby SDS polyacrylamide gel electrophoretic separation and autoradiographyof dried gels. Two dimensional isoelectric focusing followedby horography showed the major 70 K stress protein to consistof at least six polypeptides of pH 4.6 to 5.5, the 88 K to consistof at least four polypeptides, of pH 5.5 to 6.0, and the 94K to consist of at least three polypeptides of pH 4.6 to 5.2.Stress proteins in the human endometrium and decidua may proveto be of physiological significance in repductive events.     

Presence of a 16 kd protein in human seminal plasma counteracts the effects of the anti-fertility agent, gossypol

Gossypol inhibited lactate dehydrogenase (LDH) noncompetitively in human spermatozoa. The inhibitory effect of gossypol on LDH was cancelled by the addition of human serum albumin, human gamma-globulin, bovine serum albumin or human seminal plasma. Seminal plasma was at least 10 times more effective than the other three proteins, when expressed on a per mg protein basis. Attempts were made to purify the active fraction from human seminal plasma. The purification steps included gel filtration, ammonium sulphate precipitation, centrifugal microconcentration and fast-performance liquid chromatography. A single active protein of Mr = 16,000 was purified to a final yield of 0.18%. The 16 kd protein was not observed in male blood plasma. The protein was found to be heat-stable and leucine-rich (16% of the molecule), and has been designated 'gossact'. The inhibitory effect of gossypol on the LDH reaction was completely blocked by the addition of gossact (5 micrograms/ml); human blood plasma (25 micrograms/ml) and human serum albumin (200 micrograms/ml) were far less potent in this assay. In addition, gossact bound 1.4 mol of gossypol/mol of protein with the dissociation constant (Kd) = 3.06 x 10(-5) M. The role of gossact in the protection of LDH from gossypol is discussed.     

The effect of Danazol on the circulating levels of 34K insulin-like growth factor-binding protein (PP12) and endometrial secretory protein PP14

Twenty-four women, 11 with endometriosis and 13 with fibrocysticmastopathy, were treated with a medium dose (300–400 mgdaily) of Danazol for 6 months. The circulating level of progesterone,the 34K insulin-like growth factor-binding protein (IGF-bp)and endometrial protein PP14 (placental protein 14) were measuredby specific radioimmunoassays before and during treatment. Theserum progesterone concentration decreased significantly duringDanazol treatment, as did the serum levels of 34K IGF-bp andPP14. By the third month of therapy amenorrhoea was observedin 22 out of 24 women and this was accompanied by a furtherdecline in the IGF-bp and PP14 levels. In light of the previousobservations on the IGF-bp and PP14 synthesis by secretory endometriumand the fact that Danazol causes endometrial atrophy, theseresults suggest that Danazol treatment has an effect on endometrialprotein secretion.     

Can the mouse embryo provide a good model for the study of abnormal cellular development seen in human embryos?

Mouse 2-cell embryos arrested in development, either due to the effect of in vitro culture conditions ('2-cell block') or after exposure to the protein synthesis inhibitor anisomycin, were examined to determine the effect of the level of protein synthesis on development. The rate of protein synthesis was found directly to reflect the developmental potential of the embryos. Embryos cultured in the highest dose of the drug failed to divide and had the lowest rate of protein synthesis over the period of investigation, whereas untreated viable 2-cell embryos in the control group had the highest rate of protein synthesis and developed normally. Measurement of the nuclear DNA showed that both arrested and non-arrested embryonic cells completed DNA replication. Furthermore, drug-arrested embryos, like embryos which 'block' in culture, remained morphologically intact when left in culture. Disruption of the nuclear integrity and formation of micronuclei, as is frequently observed in arrested human embryos, was not seen in mouse embryos. These results indicate that developmentally arrested mouse embryos may not be a good model for studying cellular dysfunction in early human development. Experimentation using human material is required to address directly the problem of abnormal human development.     

Absence of mutations in the PCI gene in subfertile men

The molecular aetiology of male subfertility is still unknown in the majority of cases and it is thought that multiple genes are involved. One of the genes that might play a role in male reproductive function is the protein C inhibitor (PCI) gene. In mice the presence of PCI is an absolute requirement for reproduction. In this study we performed a mutation screen of the PCI gene in subfertile men with severe teratozoospermia or idiopathic azoospermia. Male partners of subfertile couples with idiopathic azoospermia (n = 27) or teratozoospermia (n = 34) and men with normozoospermia (n = 34) were screened for mutations in the PCI gene by direct sequencing. Nine nucleotide variants found in the patients were not present in the initial control group and were therefore screened in an additional control group of 80 men with normozoospermia by restriction fragment length polymorphism analysis. In addition, PCI antigen levels were measured in the seminal plasma of the patients in which a potential mutation was found. In total, three new variants were exclusively present in men with idiopathic azoospermia, but are not likely to have caused the patients' phenotypes. In addition, the PCI antigen levels in seminal plasma of these three patients were not decreased. The fact that we were not able to detect causal mutations in the PCI gene does not necessarily lead to the conclusion that the PCI protein is not involved in human male fertility, but the results of our study indicate that mutations in the human PCI gene are not a common cause of reduced semen parameters in men.     

Physiology: Morphological characteristics of preimplantation stage endometrium in the rhesus monkey

The morphological characteristics of endometrium on day 6 afterovulation of conception (group 1) and non-fecund, menstrual(group 2) cycles have been studied in the rhesus monkey (n =30). A conception cycle was distinguished by the presence ofa developmentally normal, age—stage-synchronized embryo.Thus, 78% of the mated cycles (n = 18) yielding synchronousembryos (12 zona-encased and two zona-free blastocysts) wereused for this study. On day 6 after ovulation, no significantchanges in the serum concentrations of oestrogen and progesteronewere seen in conception cycles (n = 14) compared with the non-mated,normal ovulatory cycles (n = 12). Morphometric analyses revealedthat on day 6 of gestation (n = 8), endometrium differed fromthe corresponding non-mated luteal phase (n = 7) with significantincreases in epithelial mitosis (P < 0.01), height of glandularepithelium (P < 0.05), volume ratio of gland cell to gland(P < 0.03), degree of pseudostratification (P < 0.02),and higher frequency of supranuclear, adluminal accumulationof vacuoles in gland cells (P < 0.05). The degree of stromaloedema was higher (P < 0.02) in fecund cycles but there wasno change in venular diameter. In a separate set of experiments,estimates of tissue vascular response revealed a higher (P <0.02) endometrial extravascular albumin space on the same dayof gestation; there were no differences, however, in endometrialblood volume, or in the number of von Willebrand antigen-positivecapillaries and small vessels between the two groups (group1, n = 6; group 2, n = 5). The overall results of the presentstudy together with our earlier reports support the hypothesisthat differential changes occur in luteal phase endometriumfunctionalis in the presence of preimplantation stage blastocystin the rhesus monkey.     

A biochemical test for the direct assessment of endometrial function: measurement of the major secretory endometrial protein PP14 in serum during menstruation in relation to ovulation and luteal function

Circulating PP14 was measured by radioimmunoassay in ovulating (n = 12) and anovulatory (n = 3) women throughout the menstrual cycle, the highest levels of serum PP14 being seen during menstruation and in the late luteal phase in ovulating women. Mean serum PP14 levels on days 1-7 and 24-28 of the menstrual cycle were significantly higher than those observed from days 8 to 23 (P less than 0.0005 and P = 0.005 respectively). There was no difference in mean PP14 levels observed in the menstrual and luteal phase. By contrast, serum PP14 was rarely detected in anovulatory cycles. During the luteal phase, mean serum PP14 levels were apparently not related to serum progesterone levels. However, mean PP14 levels during the menstrual phase were significantly higher in the group of women with the highest progesterone production (Pmax greater than 39 nmol/l) (P less than 0.002) in comparison with levels seen in ovulating women with lower progesterone production (Pmax less than 32 nmol/l). These findings suggest that the synthesis and secretion of PP14 is influenced by ovulation and luteal function. Serum PP14 measurements may provide useful information about the endometrium in relation to fertility, and that these measurements during the menstrual cycle may distinguish between ovulatory and anovulatory cycles.     

Circulating placental protein 14: in the first trimester of spontaneous and IVF pregnancies

Circulating placental protein 14 (PP14) levels were measuredduring the first trimester in three groups of pregnant women:(i) natural conception (n = 15); (ii) pituitary desensitizationwith buserelin and ovarian stimulation with human menopausalgonadotrophin (HMG) followed by in-vitro fertilization and embryotransfer (IVF—ET) (n = 15); and (iii) ovarian stimulationwith clomiphene citrate and HMG, followed by IVF—ET (n= 16). A 7- to 8-fold increase in serum PP14 levels was observedin normal pregnancies between weeks 4 and 10. This increasewas earlier and less marked in group (ii) and absent in group(iii). These findings support the concept that endometrial functionis altered in pregnancies achieved following ovarian stimulation.Alternatively, if the ovary is an important source of PP14,then these data suggest that in contrast to ovarian synthesisof steroids and the peptide relaxin, ovarian stimulation resultsin an impairment of PP14 synthesis, and that this is most markedwhen clomiphene citrate has been used.     

In-vitro synthesis of total protein and placental protein PP14 by the Fallopian tube mucosa: variation in relation to anatomical site, the ovarian cycle and the menopause

De-novo synthesis and secretion of protein by short term explantsof mucosa from each anatomical section of the Fallopian tubeand endometrium of pre-menopausal (n = 25) and tubal mucosaof post-menopausal (n = 5) women were studied by demonstrationof incorporation of radiolabelled L-[³⁵S]methionine and one-dimensionalSDS — polyacrylamide gel electrophoresis. A consistentfinding in 25 pre-menopausal women was the presence of a 25kDa protein band synthesized by tissue obtained throughout theovarian cycle. Western blotting demonstrated that this proteinband contained placental protein 14 (PP14)-like immunoreactivityin the proliferative (n = 2) and luteal phase (n = 2) of theovarian cycle. To determine if there is quantitative variationin total protein and PP14 synthesis and secretion during theovarian cycle, the total quantities of protein and PP14 synthesizedwere determined by Coomassie Brilliant Blue staining and radioimmunoassayrespectively. Analysis of the results of total protein assayrevealed statistically significant differences in relation tothe anatomical origin of the study tissue (P < 0.01), thestage of the ovarian cycle (P < 0.04) and the manner in whicheach anatomical site varied during the ovarian cycle (P <0.01), the endometrium being significantly different from theFallopian tube. When the data for PP14 synthesized by the Fallopiantube mucosa were analysed, these effects were not seen. PP14was not detected in the culture media of Fallopian tube mucosaobtained from post-menopausal women.     

Human seminal plasma displays significant phospholipid transfer activity due to the presence of active phospholipid transfer protein

The lipid composition of germ cell membranes is considerably modified during spermatogenesis, sperm maturation and capacitation. Some of these modifications are caused by exchanges between soluble lipid donors or acceptors and cell membranes. The aim of this study was to assess whether significant lipid transfers between lipoprotein structures are detectable in human seminal plasma. Phospholipid and cholesteryl ester (CE) transfer activities were measured by specific fluorescence and isotopic assays. Seminal plasma samples did not display significant CE transfer. Substantial levels of phospholipid transfer activity were detected in all samples studied, levels were approximately 25% of the phospholipid transfer activity measured in human blood plasma. Concordantly, CE transfer protein was not detected in seminal plasma, while the presence of the phospholipid transfer protein (PLTP) was confirmed by Western blot analysis. Enzyme-linked immunosorbent assay indicated that seminal PLTP concentrations represented 25% of the concentration measured in blood plasma. Blockade of phosphatidylcholine and phosphatidyl-ethanolamine transfer by a 60 min, 56 degrees C heating step or with anti-PLTP antibody revealed that PLTP accounts for almost 80% of the phospholipid transfer activity present in seminal plasma. As shown by gel-permeation chromatography and Western blot analysis, seminal PLTP activity was partially associated with prostasomes. Significantly higher PLTP activity levels were measured in seminal plasma samples with low seminal vesicle secretions. The latter observation may reflect the sustained secretion of active PLTP that is diluted in a variable volume of PLTP-free seminal vesicle secretion. In conclusion, human seminal plasma displays significant phospholipid transfer activity due to the presence of active PLTP.     

Symposium: reproduction in baboons. Secretory proteins of the baboon (Papio anubis) endometrium: regulation during the menstrual cycle and early pregnancy

The biological function of uterine endometrial secretory proteinsin the primate remain to be elucidated. In general, during theluteal phase and under progesterone dominance, the glandularepithelial cells synthesize and secrete a number of proteins.Of these, placental protein 14 (PP₁₄; now referred to as glycodelin)and insulin-like growth factor binding protein-1 (IGFBP-1) arethe best characterized. Although induced by progesterone, theirsynthesis increases exponentially during pregnancy. In the baboon,glycodelin is immunolocalized to the mid functionalis and basalglands between days 10 and 12 post-ovulation. In response toeither exogenous or blastocyst-secreted chorionic gonadotrophin,glandular synthesis increases markedly and remains elevatedup to days 18-25 of pregnancy. The decrease in glycodelin inthe endometrium is associated with glandular regression duringthe first third of pregnancy. In contrast, IGFBP-1 is only observedin the deep basal glands during the luteal phase. Followingthe establishment of pregnancy, IGFBP-1 synthesis switches fromglandular to stromal and is correlated with the process of decidualization.IGFBP-1 synthesis continues to increase throughout gestation.We propose that glycodelin may have immunosuppressive propertiesand that IGFBP-1 may regulate trophoblast migration within theuterine endometrium.     

Changes induced in serum protein profiles by ovarian stimulation during in-vitro fertilization--embryo transfer treatment: a comparison between conception and non-conception cycles.

The profiles of plasma protein concentrations during the follicular phase in unstimulated women and in women undergoing ovarian stimulation for in-vitro fertilization--embryo transfer (IVF-ET) treatment are described. Plasma protein concentrations are correlated with those of total oestradiol (protein-bound and free) and total progesterone. In addition, 10 conception cycles and 18 non-conception cycles are compared in an attempt to identify predictors of successful treatment. Ovarian stimulation caused a significant increase in follicular phase in serum concentrations of sex hormone binding globulin (SHBG), cortisol binding protein (CBP) and insulin-like growth factor binding protein 1 (IGFBP1). In contrast no increase was observed in unstimulated cycles. Serum levels of endometrial protein PP14 decreased significantly during the follicular phase in both stimulated and unstimulated cycles. Levels of pregnancy zone protein (PZP) were more than doubled at the time of oocyte aspiration compared to the unstimulated cycles. Albumin concentrations were unchanged by the stimulation. Throughout the follicular phase, levels of SHBG were significantly higher, and total oestradiol significantly lower in women who became pregnant, than in those who did not. Therefore, a low concentration of free, biologically active oestradiol seemed to favour pregnancy, as the concentration of albumin is similar in the two groups. The endometrial protein PP14 was significantly lower during the follicular phase in conception than in non-conceptional cycles. On day 2 of the treatment cycle, the PP14 concentration showed a 75% correct prediction of conception and non-conception cycles. These results suggest that levels of PP14 may predict successful IVF cycles even before hormonal treatment is commenced.     

Heat shock proteins in human endometrium throughout the menstrual cycle

Human endometrium is a steroid-sensitive tissue and there isevidence that supports the viewpoint that heat shock proteins(HSP) are implicated in the regulation of steroid function.Therefore, in this study we examined the expression of variousmembers of the heat shock family of proteins in the steroid-responsivehuman endometrium. Western blot analysis revealed that the expressionof HSP90 showed minimal changes throughout the menstrual cycle.When normalized to the amount of HSP90, the expression of HSP27,HSP60 and the constitutive form of heat shock protein 70 (HSC70)increased progressively during the late proliferative and earlysecretory phases, and diminished in the mid- to late secretoryand menstrual phases. In contrast, the inducible form of heatshock protein 70 (HSP70) did not undergo these changes. Thecellular and subcellular localizations of these proteins wereexamined in human endometria by immunohistochemical staining.With the exception of HSP70, which was found primarily in theepithelial cells, the immunoreactivity for other heat shockproteins was found in both the stroraa and the epithelium. Immunoreactivityfor HSP27 was found in the lymphoid aggregates within endometrialstroma, and both HSP27 and HSP90 were found in endothelial cells.The immunoreactive heat shock proteins were found in the nucleiand/or cytoplasm of cells. However, no consistent nuclear versuscytoplasmic staining emerged, and such localization was irrespectiveof the site, the cell type or the phase of the menstrual cycle.Our findings show that endometrium has a full complement ofheat shock proteins. The menstrual cycle-dependent changes inthe amounts of heat shock protein suggest regulation by steroidhormones.