The functional and molecular studies on involvement of hydrogen sulphide in myometrial activity of non-pregnant buffaloes (Bubalus bubalis)

Background

Hydrogen sulphide (H₂S), a member of the gasotransmitters family, is known to play patho-physiological role in different body systems including during pregnancy. But its involvement in myometrial spontaneity and associated signalling pathways in uterus in non-pregnant animals is yet to be studied. Present study describes the effect of L-cysteine, an endogenous H₂S donor, on isolated myometrial strips of non-pregnant buffaloes and the underlying signaling mechanism(s).

Results

L-cysteine (10 nM-30 mM) produced concentration-dependent contractile effect on buffalo myometrium which was extracellular Ca²⁺ and L-type calcium channels-dependent. Significant rightward shift of dose-response curve of L-cysteine was observed with significant decrease in maxima in the presence of amino-oxyacetic acid (AOAA; 100 μM) and d, l-propargylglycine (PAG; 100 μM), the specific blockers of cystathionine β-synthase (CBS) and cystathionine γ-lyase (CSE), respectively. Existence of CBS enzyme of 63 kDa and CSE of 45 kDa molecular weights was confirmed by western blot using specific antibodies and also by immunohistochemistry.

Conclusions

Endogenous H₂S along with its biosynthetic enzymes (CBS and CSE) is evidently present in uteri of non-pregnant buffaloes and it regulates spontaneity in uteri of non-pregnant buffaloes and this effect is dependent on extracellular Ca²⁺ influx through nifedipine-sensitive L-type calcium channels. Thus H₂S-signalling pathway may be a potential target to alter the uterine activities in physiology and patho-physiolgical states.

Titanium Dioxide Modulation of the Contractibility of Visceral Smooth Muscles In Vivo

Electronic scanning microscopy was used in the work to obtain the image and to identify the sizes of titanium dioxide (TiO2) nanoparticles 21 ± 5 nm. The qualitative and quantitative elemental analysis of the preparations of the caecum, antrum, myometrium, kidneys, and lungs of the rats, burdened with titanium dioxide, was also performed. It was established using the tenzometric method in the isometric mode that the accumulation of titanium dioxide in smooth muscles of the caecum resulted in the considerable, compared to the control, increase in the frequency of their spontaneous contractions, the decrease in the duration of the contraction-relaxation cycle, and the decrease in the indices of muscle functioning efficiency (the index of contractions in Montevideo units (MU) and the index of contractions in Alexandria units (AU)). In the same experimental conditions, there was not the increase, but the decrease in the frequency of spontaneous contractions, the duration of the contraction-relaxation cycle, and the increase in MU and AU indices in the smooth muscles of myometrium (in the group of rats, burdened with TiO2 for 30 days). It was also determined that TiO2 modulates both the mechanisms of the input of extracellular Ca2+ ions and the mechanisms of decreasing the concentration of these cations in smooth muscle cells of the caecum during the generation of the high potassium contraction. In these conditions, there is a considerable increase in the normalized maximal velocity of the contraction phase and the relaxation phase. It was demonstrated in the work that titanium dioxide also changes the cholinergic excitation in these muscles. The impact of titanium dioxide in the group of rats, burdened with TiO2, was accompanied with a considerable impairment of the kinetics of forming the tonic component of the oxytocin-induced contraction of the smooth muscles of myometrium.

Toxicological effects and ultrastructural changes induced by lanthanum and cerium in ovary and uterus of Wistar rats

Rare earths have been widely used in a huge number of areas in industry and medicine. Therefore, they exist in the environment and possibly accumulated within the human body. However their effects in the living organism particularly in the female reproductive system are still unclear. In this work, the subcellular behavior of lanthanum and cerium was investigated through the Transmission Electron Microscopy (TEM), in different territories of the reproductive system of Wistar rats exposed intraperitoneally to soluble solution of these elements during 2 weeks. Ultrastructural investigations of ultrathin sections from uterus and ovary of treated rats revealed the existence of inclusions with high electron density and heterogeneous aspects in the lysosomes of uterus and ovary cells. Many disruptions of architecture were observed, accompanied with several changes like vacuolations, significant expansion of the endoplasmic reticulum, mitochondrial alterations and necrotic cells, demonstrating the toxicity of these elements with doses used. Phagolysosomes as well as eosinophils were also seen. Our experimental investigations revealed no intralysosomal inclusions in ultrathin sections of the uterus and ovary of pregnant control females. The original mechanism implicated in this insolubilization-concentration phenomenon of these elements, as non-soluble phosphate form, in the lysosomes is a biochemical one involving intralysosomal hydrolytic enzymes, the acid phosphatase.

Alterations in antioxidant system, mitochondrial biogenesis and autophagy in preeclamptic myometrium

Preeclampsia is a pregnancy complication which causes significant maternal and fetal morbidity and mortality worldwide. Although intensive research has been performed in the last 40 years, the pathology of preeclampsia is still poorly understood. The present work is a comparative study of the myometrium of women with normal pregnancy, and those with late- and early-onset preeclampsia (n = 10 for each group). We observed significant changes in the levels of antioxidant enzymes, markers of mitochondrial biogenesis and autophagy proteins in preeclamptic myometrium. Levels of superoxide dismutase 1 and catalase were lower in both preeclamptic groups than the control group. In late-onset preeclampsia, expression levels of essential mitochondria-related proteins VDAC1, TFAM, hexokinase 1, PGC-1α and PGC-1β, and autophagy marker LC3A, were significantly elevated. In the myometrium of the early-onset preeclampsia group OPA1 and Bcl-2 were up-regulated compared to those of the control (p < 0.05). These findings suggest that crucial molecular changes in the maternal myometrium occur with the development of preeclampsia.

ATP-sensitive and maxi potassium channels regulate BRL 37344-induced tocolysis in buffaloes-an in vitro study

Cellular coupling of beta₃-adrenoceptors (β₃-ADR) to potassium channels in myometrium is largely unknown. In vitro study was undertaken to unravel the presence of β₃-adrenergic receptors (ADR) and the role of K⁺-channels in mediating β₃-ADR-induced relaxation in isolated myometrial strips from cyclic non-pregnant water buffaloes. Isometric tension was recorded in isolated myometrial strips using data acquisition system based physiograph. Compared to SR 59230A, BRL 37344 was found to be more potent in inducing β₃-dependent myometrial relaxation which was significantly (p < 0.05) inhibited in the presence of β₃ antagonist, SAR 150640. The immunoreactive protein to β₃-ADR was also detected in membrane fraction of myometrial protein. Further, incubation with BRL 37344 (10 μM) significantly (p < 0.05) increased c-AMP accumulation (37.58 ± 9.52 pmol/mg protein; n = 4) in the myometrial strips compared to basal c-AMP level (16.85 ± 3.87 pmol/mg protein; n = 4). The concentration response curves (CRC) of BRL 37344 were significantly (p < 0.05) shifted towards right in the presence of K_ATP channels specific blocker, glibenclamide (10 μM) and maxi K⁺-channels (BK_Ca) specific blocker, iberiotoxin (100 nM), with decrease in both efficacy and potency as compared to control. However, 4-aminopyridine (4-AP), a specific blocker of the voltage gated K⁺-channels (Kv), failed to alter the CRC of BRL 37344. Existence of immunoreactive protein to Kir6.1, α-subunit of BK_Ca and Kv1.1 channels were also detected in the membrane fraction of myometrial protein. Based on the above findings, it can be concluded that BRL 37344 is a potent stimulator of β₃-adrenoceptors in buffalo myometrium and besides mediating their effect through rise in c-AMP, they are coupled to K_ATP and BK_Ca channels in inducing tocolytic effects.

Recently discovered interstitial cells "telocytes" as players in the pathogenesis of uterine leiomyomas

Uterine telocytes are interstitial cells characterized by a very long cytoplasmic prolongations, which form a 3D network, functionally integrating a wide variety of different cells. Leiomyomas (uterine fibroids) are benign tumors, which pose a huge threat concerning various health problems in women affected by this condition. The exact cause of leiomyomas development is, however, still largely unknown. Therefore, in an attempt to clarify their etiology, we performed an immunohistochemical characterization of telocytes in leiomyomas as well as in normal myometrium. Tissue samples of intramural leiomyomas from 26 women (age 46.26 ± 11.07) were immunohistochemically stained for the expression of c-kit (CD117) antigen, one of the markers of telocytes. C-kit (CD117) antigen is useful for a routine immunohistochemical identification of uterine telocytes in histological sections of myometrium. In normal, healthy myometrium the c-kit positive telocytes occupy approximately 2.2% of the area of a tissue slide, contrasting with no detectable c-kit positive cells within leiomyomas. As telocytes are thought to be key players in the regulation of tissue homoeostasis, our data suggest that uterine telocyte loss may have important implications in the pathogenesis of leiomyomas. In addition, we supposed to summarize three hypotheses on the association of the cells telocytes loss within the myometrium and formation of leiomyomas. These hypotheses include the loss of telocytes' functions as "sex hormone sensors" and regulators of smooth muscle cells cycle; the role of telocytes as progenitor cells for the development of leiomyomas; and the hypothesis of decreased angiogenesis after telocytes' loss with subsequent hypoxia (as a key factor for leiomyomas development).

The IL-1β signalling pathway and its role in regulating pro-inflammatory and pro-labour mediators in human primary myometrial cells

Interleukin (IL)-1β plays a central role in the processes of human labour and delivery. The adaptor proteins involved in the IL-1β signalling pathway in human myometrium are not known. This study sought to determine the role of the adaptor proteins myeloid differentiation primary response 88 (MyD88), tumour necrosis factor receptor-associated factor 6 (TRAF6), IL-1 receptor-associated kinase 4 (IRAK4) and transforming growth factor beta-activated kinase 1 (TAK1) in IL-1β-induced formation of pro-inflammatory and pro-labour mediators in human myometrium. Human primary myometrial cells were transfected with siRNA against MyD88 (siMYD88), TRAF6 (siTRAF6), IRAK4 (siIRAK4) or TAK1 (siTAK1), treated with IL-1β, and assayed for the mRNA expression and or secretion of pro-inflammatory and pro-labour mediators. Transfection of primary myometrial cells with siMYD88, siTRAF6, siIRAK4 and siTAK1 significantly decreased IL-1β-induced IL-1α, IL-6, growth-regulated alpha protein (GRO-α), IL-8, monocyte chemoattractant protein (MCP)-1, intercellular adhesion molecule (ICAM)-1 and cyclooxygenase (COX)-2 mRNA expression and release of IL-6, GRO-α, IL-8, MCP-1, ICAM-1 and prostaglandin PGF_2α. The expression and secretion of the extracellular matrix remodelling enzyme matrix metalloproteinase (MMP)-9 was significantly lower with siMYD88 and siTRAF6. Finally, IL-1β-induced nuclear factor κB (NF-κB) transcriptional activity was significantly attenuated by transfection with siMyD88, siTRAF6 and siIRAK4; there was no effect of siTAK1 transfection on NF-κB transcriptional activity. Collectively, these findings suggest that MyD88, TRAF6, IRAK4 and TAK1 are involved in IL-1β signalling in human myometrium. Further studies are required to determine if inhibition of these proteins can prevent preterm birth.

TLR2, TLR3 and TLR5 regulation of pro-inflammatory and pro-labour mediators in human primary myometrial cells

Preterm birth continues to be a significant global health care issue, due to our lack of understanding of the mechanisms that drive human labour and delivery. Toll-like receptors (TLRs) are essential in triggering an inflammatory response in human gestational tissues, leading to the production of pro-inflammatory and pro-labour mediators, and thus preterm birth. The aims of this study were to determine whether the adaptor molecules associated with TLR2, TLR3 and TLR5 signalling are involved in human myometrium. Primary human myometrial cells were transfected with siRNA against TIRAP, IRAK1, IRAK4, TAK1and stimulated with bacterial product fsl-1 (TLR2); TRIF, TRADD, TRAF6, RIP1, TAK1 and stimulated with dsRNA viral analogue poly(I:C) (TLR3); IRAK1, IRAK4, TAK1 and stimulated with bacterial product flagellin (TLR5), and assayed for production of pro-inflammatory and pro-labour mediators. Cells transfected with TIRAP, IRAK1, IRAK4 or TAK1 all showed a decrease in fsl-1-induced expression of cytokines (IL-1α, IL-1β, IL-6), chemokines (GRO-α, IL-8, MCP-1), adhesion molecule ICAM-1, cyclooxygenase (COX)-2 mRNA and release of PGF_2α and MMP-9 expression. Cells transfected with TRIF, TRAF6, RIP1 or TAK1 all decreased production of poly(I:C)-induced IL-1α, IL-1β, IL-6, GRO-α, IL-8, MCP-1, ICAM-1 and MMP-9 expression. Cells transfected with IRAK1, IRAK4 or TAK1 all showed decreased expression of flagellin-induced cytokine and chemokine expression, ICAM-1 and MMP-9 expression. Lastly, transfection with these siRNAs decreased fsl-1, poly(I:C) and flagellin-induced NF-κB transcriptional activity. Our study signifies that these adaptor molecules are necessary for the proper production of cytokines, chemokines and pro-labour mediators after TLR ligation.

[New features in the 2014 WHO classification of uterine neoplasms]

The 2014 World Health Organization (WHO) classification of uterine tumors revealed simplification of the classification by fusion of several entities and the introduction of novel entities. Among the multitude of alterations, the following are named: a simplified classification for precursor lesions of endometrial carcinoma now distinguishes between hyperplasia without atypia and atypical hyperplasia, the latter also known as endometrioid intraepithelial neoplasia (EIN). For endometrial carcinoma a differentiation is made between type 1 (endometrioid carcinoma with variants and mucinous carcinoma) and type 2 (serous and clear cell carcinoma). Besides a papillary architecture serous carcinomas may show solid and glandular features and TP53 immunohistochemistry with an "all or null pattern" assists in the diagnosis of serous carcinoma with ambiguous features. Neuroendocrine neoplasms are categorized in a similar way to the gastrointestinal tract into well differentiated neuroendocrine tumors and poorly differentiated neuroendocrine carcinomas (small cell and large cell types). Leiomyosarcomas of the uterus are typically high grade and characterized by marked nuclear atypia and lively mitotic activity. Low grade stromal neoplasms frequently show gene fusions, such as JAZF1/SUZ12. High grade endometrial stromal sarcoma is newly defined by cyclin D1 overexpression and the presence of the fusion gene YWHAE/FAM22 and must be distinguished from undifferentiated uterine sarcoma. Carcinosarcomas (malignant mixed Mullerian tumors MMMT) show biological and molecular similarities to high-grade carcinomas.

Reciprocal regulation of β2-adrenoceptor-activated cAMP response-element binding protein signalling by arrestin2 and arrestin3

Activation of Gs coupled receptors (e.g. β₂-adrenoreceptor (β₂AR)) expressed within the uterine muscle layer (myometrium), promotes intracellular cAMP generation, inducing muscle relaxation through short-term inhibition of contractile proteins, and longer-term modulation of cellular phenotype to promote quiescence. In the myometrium cAMP-driven modulation of cell phenotype is facilitated by CREB activity, however despite the importance of CREB signalling in the promotion of myometrial quiescence during pregnancy, little is currently known regarding the molecular mechanisms involved. Thus, we have characterised β-adrenoceptor-stimulated CREB signalling in the immortalised ULTR human myometrial cell line. The non-selective β-adrenoceptor agonist isoprenaline induced time- and concentration-dependent CREB phosphorylation, which was abolished by the β₂AR selective antagonist ICI118,551. β₂AR-stimulated CREB phosphorylation was mediated through a short-term PKA-dependent phase, and longer-term Src/p38 MAPK-dependent/PKA-independent phase. Since in model cells, arrestin2 can facilitate β₂AR-mediated Src/p38 recruitment, we examined whether CREB signalling was activated through a similar process in myometrial cells. Depletion of arrestin2 attenuated p38 phosphorylation, whilst arrestin3 depletion enhanced and prolonged isoprenaline-stimulated p38 signals, which was reversed following inhibition of Src. Knockdown of arrestin2 led to enhanced short-term (up to 10min), and attenuated longer-term (>10min) isoprenaline-stimulated CREB phosphorylation. Contrastingly, removal of arrestin3 enhanced and prolonged isoprenaline-stimulated CREB phosphorylation, whilst depletion of both arrestins abolished CREB signals at time points >5min. In summary, we have delineated the molecular mechanisms coupling β₂AR activity to CREB signalling in ULTR myometrial cells, revealing a biphasic activation process encompassing short-term PKA-dependent, and prolonged Src/arrestin2/p38-dependent components. Indeed, our data highlight a novel arrestin-mediated modulation of CREB signalling, suggesting a reciprocal relationship between arrestin2 and arrestin3, wherein recruitment of arrestin3 restricts the ability of β₂AR to activate prolonged CREB phosphorylation by precluding recruitment of an arrestin2/Src/p38 complex.

The role of T1 perfusion-based classification in magnetic resonance-guided high-intensity focused ultrasound ablation of uterine fibroids

OBJECTIVE

To comparatively evaluate the role of magnetic resonance (MR) T1 perfusion-based time-signal intensity (SI) curves of fibroid tissue and the myometrium in classification of fibroids for predicting treatment outcomes of high-intensity focused ultrasound (HIFU) treatment.

METHODS

The fibroids of 74 women who underwent MR-HIFU treatment were classified into group A (time-SI curve of fibroid lower than that of the myometrium) and group B (time-SI curve of fibroid equal to or higher than that of the myometrium). Non-perfused volume (NPV) ratios immediately after treatment and fibroid volume reduction ratios and symptom severity scores (SSS) at the 6-month follow-up were retrospectively assessed.

RESULTS

The immediate NPV ratios in groups A and B were 95.3 ± 6.3% (n = 62) and 63.8 ± 11% (n = 12), respectively. At the 6-month follow-up, the fibroid volume reduction ratios in groups A and B were 0.52 ± 0.14 (n = 50) and 0.07 ± 0.14 (n = 11), with the corresponding improvement in mean transformed SSS being 0.86 ± 0.14 and 0.19 ± 0.3, respectively. No serious adverse effects were reported.

CONCLUSIONS

Our novel classification method could play an important role in classifying fibroids for predicting the immediate outcomes of HIFU treatment.

KEY POINTS

• MRI is an important modality for outcome prediction in HIFU treatment • Patient selection is a significant factor for achieving high NPV ratio • NPV ratio is very strongly correlated with T1 perfusion-based classification • T1 perfusion-based classification is a strong predictor of treatment outcome.

C-kit receptor immunopositive interstitial cells (Cajal-type) in the porcine reproductive tract

Background

Interstitial Cajal cells have been suspected as being the pacemaker cells of smooth muscle motor activity and discharging slow triggering waves in the gut as well as in other organs containing smooth muscles where they are known as interstitial Cajal-like cells (ICLC). The present study describes ICLC localization and density in the porcine oviduct and uterus. Differences in ICLC density were examined using histological, immunohistochemical and immunofluorescent methods and c-kit expression was determined.

Results

interstitial Cajal-like cells with characteristic morphological and immunological phenotypes were found. Star-like or spindle-shaped cells with very long, moniliform processes were localized in the muscle layers of the oviduct and uterine walls at variable densities that decreased progressively from high in the oviduct to low in the uterus.

Conclusions

The detailed description of ICLC in the porcine reproductive tract may lead to a better understanding of reproductive tract motility. Our approach is inexpensive and effective for ICLC evaluation and may in the future be applied to clinical diagnosis.

11β-hydroxysteroid dehydrogenase type 1 and pregnancy: Role in the timing of labour onset and in myometrial contraction

Glucocorticoids play a primary role in the maturation of fetal organs and may contribute to the onset of labour. Glucocorticoid activity depends on the 11β-hydroxysteroid dehydrogenase family (11β-HSDs), catalysing the interconversion between "active" cortisol into inactive cortisone. No definitive study exists on 11β-HSD expression profile in human decidua and myometrium during pregnancy. We investigated the implications of 11β-HSD1 in the regulation of uterine activity in pregnancy, examining its role on contraction of a myocyte cell line and murine 11β-hsd1 levels in utero. Murine 11β-hsd1 mRNA and protein levels in utero progressively increased until the last day of gestation and significantly decreased at the onset of labour (P < 0.0001) (n = 3 to 5 in the various gestational days analysed). Experiments on human myometrial samples confirm the significant fall in 11β-hsd1 mRNA levels at labour, compared to end pregnancy samples (n = 5 to 8). In vitro experiments showed that human myometrial contraction is inhibited by using a non-selective inhibitor of 11β-HSD1. The present study shows the temporal localisation of 11β-HSD1 in uterus, highlighting its importance in the timing of gestation and suggesting its contribution in the myometrium contraction.

Progesterone Receptor Signaling in Uterine Myometrial Physiology and Preterm Birth

Myometrium holds the structural integrity for the uterus and generates force for parturition with its primary component, the smooth muscle cells. The progesterone receptor mediates progesterone-dependent signaling and connects to a network of pathways for regulation of contractility and inflammatory responses in myometrium. Dysfunctional progesterone signaling has been linked to pregnancy complications including preterm birth. In the present review, we summarize recent findings on modifiers and effectors of the progesterone receptor signaling. Discussions include novel conceptual discoveries and new development in legacy pathways such as the signal transducers NF-κB, ZEB, microRNA, and the unfolded protein response pathways. We also discuss the impact of progesterone receptor isoform composition and ligand accessibility in modification of the progesterone receptor genomic actions.

Very small embryonic-like stem cells (VSELs) in adult mouse uterine perimetrium and myometrium

We have earlier reported the presence of very small embryonic-like stem cells (VSELs) in adult mouse uterus along with slightly bigger progenitors termed endometrial stem cells (EnSCs) and their regulation by ovarian hormones thus demonstrating a crucial role played by them during proliferation, differentiation and remodeling of the endometrium. Present study is a brief communication wherein we have examined the effect of higher dose of estrogen (E, 2 μg/day), progesterone (P, 1 mg/day) and follicle stimulating hormone (FSH, 5 IU/day for 5 days) specifically on the myometrium and perimetrium surrounding the endometrium in bilaterally ovariectomized mice. Similar treatment with E & P was recently used in a study published in the journal Nature to study the effect of steroid hormones on hematopoietic stem cells and this treatment regimen helps achieve hormone levels observed during pregnancy. Quiescent spherical stem cells (lacking PCNA expression) with high nucleo-cytoplasmic ratio and nuclear OCT-4A were detected in the perimetrium of atrophied (bilaterally ovariectomized) uterus. PCNA expression was observed after treatment and cells with cytoplasmic OCT-4B were invariably observed in the myometrium. VSELs were clearly visualized after treatment and the effect of P and FSH was more prominent compared to E on the development of myometrium. It is speculated that stem cells with nuclear OCT-4A located in the perimetrium differentiate to give rise to endothelial and myometrial cells with cytoplasmic OCT-4B. Based on the results of present study and published reports showing the presence of pluripotent markers (OCT-4, NANOG and SOX2) in human myometrial side population and expression of particularly OCT-4A in human leiomyomas, we speculate that these nuclear OCT-4 positive stem cells located in the perimetrium are the possible tumor initiating cells leading to the development of leiomyomas rather than the mesenchymal cells which express cytoplasmic OCT-4B.

The Potential Functions of Small Heat Shock Proteins in the Uterine Musculature during Pregnancy

The small heat shock protein B (HSPB) family is comprised of eleven members with many being induced by physiological stressors. In addition to being molecular chaperones, it is clear these proteins also play important roles in cell death regulation, cytoskeletal rearrangements, and immune system activation. These processes are important for the uterine smooth muscle or myometrium during pregnancy as it changes from a quiescent tissue, during the majority of pregnancy, to a powerful and contractile tissue at labor. The initiation and progression of labor within the myometrium also appears to require an inflammatory response as it is infiltrated by immune cells and it produces pro-inflammatory mediators. This chapter summarizes current knowledge on the expression of HSPB family members in the myometrium during pregnancy and speculates on the possible roles of these proteins during myometrial programming and transformation of the myometrium into a possible immune regulatory tissue.

Ryanodine receptor type 3 does not contribute to contractions in the mouse myometrium regardless of pregnancy

Ryanodine receptor type 3 (RyR3) is expressed in myometrial smooth muscle cells (MSMCs). The short isoform of RyR3 is a dominant negative variant (DN-RyR3) and negatively regulates the functions of RyR2 and full-length (FL)-RyR3. DN-RyR3 has been suggested to function as a major RyR3 isoform in non-pregnant (NP) mouse MSMCs, and FL-RyR3 may also be upregulated during pregnancy (P). This increase in the FL-RyR3/DN-RyR3 ratio may contribute to the strong contractions by MSMCs for parturition. In the present study, spontaneous contractions by the myometrium in NP and P mice were highly susceptible to nifedipine but were not affected by ryanodine. Ca²⁺ image analyses under a voltage clamp revealed that the influx of Ca²⁺ through voltage-dependent Ca²⁺ channels did not cause the release of Ca²⁺ from the sarcoplasmic reticulum (SR). Cytosolic Ca²⁺ concentrations ([Ca²⁺]_cyt) in MSMCs were not affected by caffeine. Despite the abundant expression of large conductance Ca²⁺-activated K⁺ channels in MSMCs, spontaneous transient outward currents were not observed in the resting state because of the substantive lack of Ca²⁺ sparks. Quantitative PCR and Western blot analyses indicated that DN-RyR3 was strongly expressed in the NP myometrium, while the expression of FL-RyR3 and DN-RyR3 was markedly reduced in the P myometrium. The messenger RNA (mRNA) expression of RyR2 and RyR1 was negligible in the NP and P myometria. Moreover, RyR3 knockout mice may become pregnant and deliver normally. Thus, we concluded that none of the RyR subtypes, including RyR3, play a significant role in the regulation of [Ca²⁺]_cyt in or contractions by mouse MSMCs regardless of pregnancy.

3D Cell Culturing and Possibilities for Myometrial Tissue Engineering

Research insights into uterine function and the mechanisms of labour have been hindered by the lack of suitable animal and cellular models. The use of traditional culturing methods limits the exploration of complex uterine functions, such as cell interactions, connectivity and contractile behaviour, as it fails to mimic the three-dimensional (3D) nature of uterine cell interactions in vivo. Animal models are an option, however, use of these models is constrained by ethical considerations as well as translational limitations to humans. Evidence indicates that these limitations can be overcome by using 3D culture systems, or 3D Bioprinters, to model the in vivo cytological architecture of the tissue in an in vitro environment. 3D cultured or 3D printed cells can be used to form an artificial tissue. This artificial tissue can not only be used as an appropriate model in which to study cellular function and organisation, but could also be used for regenerative medicine purposes including organ or tissue transplantation, organ donation and obstetric care. The current review describes recent developments in cell culture that can facilitate the development of myometrial 3D structures and tissue engineering applications.

Misoprostol modulates the gene expression prostaglandin E2 and oxidative stress markers in myometrial cells

Misoprostol, prostaglandin E1 analogue, used for labour induction. However, one-third of patients who have labour induced with prostaglandins do not reach vaginal delivery. The differential expression of prostaglandin receptors in myometrial cells could account for this differential response. Since delivery physiology also involves modulation of oxidative metabolism that can be potentially affected by pharmacological drugs, in the present investigation the role of misoprostol on expression of prostaglandin receptors, and oxidative markers of myometrial cells was evaluated. Samples of myometrial tissues procured from women with spontaneous (SL) and nonspontaneous (NSL) labours were cultured in vitro and exposed to different concentrations of misoprostol. Gene expression was evaluated by qRT-PCR and oxidative biomarkers were evaluated by spectrophotometric and fluorometric analysis. Cells from SL women presented greater responsiveness to misoprostol, since an upregulation of genes related to increased muscle contraction was observed. Otherwise, cells from NSL women had low responsiveness to misoprostol exposure or even a suppressive effect on the expression of these genes. Oxidative biomarkers that previously have been related to labour physiology were affected by misoprostol treatment: lipoperoxidation and protein carbonylation (PC). However, a decrease in lipoperoxidation was observed only in SL cells treated with low concentrations of misoprostol, whereas a decrease of PC occurred in all samples treated with different misoprostol concentrations. The results suggest a pharmacogenetic effect of misoprostol in labour induction involving differential regulation of EP receptor genes, as well as some minor differential modulation of oxidative metabolism in myometrial cells.

Myometrial relaxation of mice via expression of two pore domain acid sensitive K(+) (TASK-2) channels

Myometrial relaxation of mouse via expression of two-pore domain acid sensitive (TASK) channels was studied. In our previous report, we suggested that two-pore domain acid-sensing K⁺ channels (TASK-2) might be one of the candidates for the regulation of uterine circular smooth muscles in mice. In this study, we tried to show the mechanisms of relaxation via TASK-2 channels in marine myometrium. Isometric contraction measurements and patch clamp technique were used to verify TASK conductance in murine myometrium. Western blot and immunehistochemical study under confocal microscopy were used to investigate molecular identity of TASK channel. In this study, we showed that TEA and 4-AP insensitive non-inactivating outward K⁺ current (NIOK) may be responsible for the quiescence of murine pregnant longitudinal myometrium. The characteristics of NIOK coincided with two-pore domain acid-sensing K⁺ channels (TASK-2). NIOK in the presence of K⁺ channel blockers was inhibited further by TASK inhibitors such as quinidine, bupivacaine, lidocaine, and extracellular acidosis. Furthermore, oxytocin and estrogen inhibited NIOK in pregnant myometrium. When compared to non-pregnant myometrium, pregnant myometrium showed stronger inhibition of NIOK by quinidine and increased immunohistochemical expression of TASK-2. Finally, TASK-2 inhibitors induced strong myometrial contraction even in the presence of L-methionine, a known inhibitor of stretch-activated channels in the longitudinal myometrium of mouse. Activation of TASK-2 channels seems to play an essential role for relaxing uterus during pregnancy and it might be one of the alternatives for preventing preterm delivery.

A dynamical systems model of progesterone receptor interactions with inflammation in human parturition

BACKGROUND

Progesterone promotes uterine relaxation and is essential for the maintenance of pregnancy. Withdrawal of progesterone activity and increased inflammation within the uterine tissues are key triggers for parturition. Progesterone actions in myometrial cells are mediated by two progesterone receptor (PR) isoforms, PR-A and PR-B, that function as ligand-activated transcription factors. PR-B mediates relaxatory actions of progesterone, in part, by decreasing myometrial cell responsiveness to pro-inflammatory stimuli. These same pro-inflammatory stimuli promote the expression of PR-A which inhibits the anti-inflammatory activity of PR-B. Competitive interaction between the progesterone receptors then augments myometrial responsiveness to pro-inflammatory stimuli. The interaction between PR-B transcriptional activity and inflammation in the pregnancy myometrium is examined using a dynamical systems model in which quiescence and labor are represented as phase-space equilibrium points. Our model shows that PR-B transcriptional activity and the inflammatory load determine the stability of the quiescent and laboring phenotypes. The model is tested using published transcriptome datasets describing the mRNA abundances in the myometrium before and after the onset of labor at term. Surrogate transcripts were selected to reflect PR-B transcriptional activity and inflammation status.

RESULTS

The model coupling PR-B activity and inflammation predicts contractile status (i.e., laboring or quiescent) with high precision and recall and outperforms uncoupled single and two-gene classifiers. Linear stability analysis shows that phase space bifurcations exist in our model that may reflect the phenotypic states of the pregnancy uterus. The model describes a possible tipping point for the transition of the quiescent to the contractile laboring phenotype.

CONCLUSIONS

Our model describes the functional interaction between the PR-A:PR-B hypothesis and tissue level inflammation in the pregnancy uterus and is a first step in more sophisticated dynamical systems modeling of human partition. The model explains observed biochemical dynamics and as such will be useful for the development of a range of systems-based models using emerging data to predict preterm birth and identify strategies for its prevention.

MicroRNA-15b regulates reversion-inducing cysteine-rich protein with Kazal motifs (RECK) expression in human uterine leiomyoma

BACKGROUND

Human uterine leiomyoma (fibroids; LYO) are the most common benign neoplasms in reproductive-aged women. Dysregulated extracellular matrix and irregular LYO reversion-inducing cysteine-rich protein with Kazal motifs (RECK) expression are thought to be mediated by aberrant microRNA (miR) expression. The relationship of miR-15b and RECK expression in LYO has not been studied.

METHODS

The expression levels of miR-15b and RECK were determined by quantitative RT-PCR, Western blot, and immunohistochemistry in cultures derived from commercial primary leiomyoma (cpLYO) and myometrial (cpMYO) cell lines and leiomyoma (pLYO) and myometrium (pMYO) tissue from surgical samples respectively. The relationship between miR-15b and RECK expression in cpLYO and pLYO (compared to their respective myometrial controls) was evaluated following transfection of cell cultures with either miR-15b mimic or inhibitor.

RESULTS

Elevated levels of miR-15b were observed in cpLYO (2.82-fold; p = 0.04) and pLYO cell (1.30-fold; p = 0.0001) cultures respectively compared to corresponding MYO cell controls. Following transfection with miR-15b mimic, cpLYO cells (0.62-fold; p < 0.0001) and pLYO cells (0.68-fold; p < 0.0001) demonstrated reduced RECK protein expression. Following transfection with miR-15b inhibitor, cpLYO cells (1.20-fold; p < 0.0001) and pLYO cells (1.31-fold; p = 0.0007) demonstrated elevated RECK protein expression. RECK protein expression was reduced in pLYO tissues (0.73-fold; p < 0.0001) and pLYO (0.47-fold; p = 0.047) cells when compared to the corresponding MYO tissue controls.

CONCLUSION

Our findings suggest that miR-15b negatively regulates RECK expression in LYO, and increased miR-15b and decreased RECK expression may contribute to the pathobiology of LYO. The functional significance of miR-15b and RECK expression warrants further investigation as potential therapeutic targets for the treatment of human LYO.

Identification and potential role of telocytes in human uterine leiomyoma

Background

Telocytes are specialized interstitial tissue cell type. Our aim is to characterize telocytes in human uterine leiomyoma (ULM) and its adjacent myometrium (Myo-F) as well as normal myometrium (Myo-N).

Methods

ULMs and Myo-F tissues were taken from hysterectomy specimens done to treat symptomatic uterine fibroids (N = 20). Myo-N is isolated from hysterectomies done on ULM- free uteri for other benign indications (N = 15).

Telocytes were detected using immunohistochemistry to detect c-Kit (CD-117), as a surface marker expressed on telocytes, and electron microscopic examination to identify telocytes characteristic ultrastructure. Cellular count and electron microscopic features of telocytes in each of the studied tissues were compared.

Results

Telocytes could be detected in ULMs, Myo-F and Myo-N using c-KIT immunostaining. Electron microscopy confirmed the presence of telocytes in the three types of tissues identifying their characteristic features including small triangular or fusiform cell bodies with extensive cellular prolongations. ULM telocytes showed ultrastructural features suggestive of high cellular activities. Cell counts of ULM telocytes (3.35 ± 0.39) were significantly higher (P value = 0.00039) than that of Myo-F (1.39 ± 0.13). Myo-N (2.6 ± 0.36) contained higher telocyte numbers than Myo-F (1.39 ± 0.13), but the difference did not reach statistical significance (P value = 0.19).

Conclusions

Telocytes are detected in higher numbers and activity in ULMs than Myo-F or Myo-N. In ULMs, telocytes can work as a hormonal sensors for stem cells, provide scaffold for newly formed myocytes, or control important downstream signaling pathways.

The effects of progesterone on the alpha2-adrenergic receptor subtypes in late-pregnant uterine contractions in vitro

BACKGROUND

The adrenergic system and progesterone play major roles in the control of the uterine function. Our aims were to clarify the changes in function and expression of the α2-adrenergic receptor (AR) subtypes after progesterone pretreatment in late pregnancy.

METHODS

Sprague Dawley rats from pregnancy day 15 were treated with progesterone for 7 days. The myometrial expressions of the α2-AR subtypes were determined by RT-PCR and Western blot analysis. In vitro contractions were stimulated with (-)-noradrenaline, and its effect was modified with the selective antagonists BRL 44408 (α2A), ARC 239 (α2B/C) and spiroxatrine (α2A). The accumulation of myometrial cAMP was also measured. The activated G-protein level was investigated via GTPγS binding assays.

RESULTS

Progesterone pretreatment decreased the contractile effect of (-)-noradrenaline through the α2-ARs. The most significant reduction was found through the α2B-ARs. The mRNA of all of the α2-AR subtypes was increased. Progesterone pretreatment increased the myometrial cAMP level in the presence of BRL 44408 (p < 0.001), spiroxatrine (p < 0.001) or the spiroxatrine + BRL 44408 combination (p < 0.05). Progesterone pretreatment increased the G-protein-activating effect of (-)-noradrenaline in the presence of the spiroxatrine + BRL 44408 combination.

CONCLUSIONS

The expression of the α2-AR subtypes is progesterone-sensitive. It decreases the contractile response of (-)-noradrenaline through the α2B-AR subtype, blocks the function of α2A-AR subtype and alters the G protein coupling of these receptors, promoting a Gs-dependent pathway. A combination of α2C-AR agonists and α2B-AR antagonists with progesterone could be considered for the treatment or prevention of preterm birth.

Modeling hormonal and inflammatory contributions to preterm and term labor using uterine temporal transcriptomics

BACKGROUND

Preterm birth is now recognized as the primary cause of infant mortality worldwide. Interplay between hormonal and inflammatory signaling in the uterus modulates the onset of contractions; however, the relative contribution of each remains unclear. In this study we aimed to characterize temporal transcriptome changes in the uterus preceding term labor and preterm labor (PTL) induced by progesterone withdrawal or inflammation in the mouse and compare these findings with human data.

METHODS

Myometrium was collected at multiple time points during gestation and labor from three murine models of parturition: (1) term gestation; (2) PTL induced by RU486; and (3) PTL induced by lipopolysaccharide (LPS). RNA was extracted and cDNA libraries were prepared and sequenced using the Illumina HiSeq 2000 system. Resulting RNA-Seq data were analyzed using multivariate modeling approaches as well as pathway and causal network analyses and compared against human myometrial transcriptome data.

RESULTS

We identified a core set of temporal myometrial gene changes associated with term labor and PTL in the mouse induced by either inflammation or progesterone withdrawal. Progesterone withdrawal initiated labor without inflammatory gene activation, yet LPS activation of uterine inflammation was sufficient to override the repressive effects of progesterone and induce a laboring phenotype. Comparison of human and mouse uterine transcriptomic datasets revealed that human labor more closely resembles inflammation-induced PTL in the mouse.

CONCLUSIONS

Labor in the mouse can be achieved through inflammatory gene activation yet these changes are not a requisite for labor itself. Human labor more closely resembles LPS-induced PTL in the mouse, supporting an essential role for inflammatory mediators in human "functional progesterone withdrawal." This improved understanding of inflammatory and progesterone influence on the uterine transcriptome has important implications for the development of PTL prevention strategies.