Collagen and matrix metalloproteinase-2 and -9 in the ewe cervix during the estrous cycle

An Exploratory Data Analysis from Ovine and Bovine RNA-Seq Identifies Pathways and Key Genes Related to Cervical Dilatation

The present study developed a review and exploration of data in public and already validated repositories. The main objective was to identify the pathways involved in ruminants' cervical dilatation, which are conserved between cattle and sheep in the follicular and luteal phases of the reproductive cycle. In cattle, 1961 genes were more differentially expressed in the follicular phase and 1560 in the luteal phase. An amount of 24 genes were considered exclusively expressed from these. A total of 18 genes were in the follicular phase and 6 genes were in the luteal phase. In sheep, 2126 genes were more differentially expressed in the follicular phase and 2469 genes were more differentially expressed in the luteal phase. Hoxb genes were identified in both species and are correlated with the PI3K/Akt pathway. PI3K/Akt was also found in both cattle and sheep, appearing prominently in the follicular and luteal phases of both species. Our analyses have pointed out that the PI3K/Akt pathway and the Hoxb genes appear in prominence in modulating mechanisms that involve estrus alterations in the cervix. PI3K/Akt appears to be an important pathway in the cervical relaxation process.

Integrated multiple transcriptomes in oviductal tissue across the porcine oestrous cycle reveal functional roles in oocyte maturation and transport

Understanding the changes in the swine female reproductive system is important for solving issues related to reproductive failure and litter size. Elucidating the regulatory mechanisms of the natural oestrous cycle in the oviduct under non-fertilisation conditions can improve our understanding of its role in the reproductive system. Herein, whole transcriptome RNA sequencing of oviduct tissue samples was performed. The differentially expressed genes (DEGs) were identified for each time point relative to Day 0 and classified into three clusters based on their expression patterns. Clusters 1 and 2 included genes involved in the physiological changes through the oestrous cycle. Cluster 1 genes were mainly involved in PI3K-Akt signalling and steroid hormone biosynthesis pathways. Cluster 2 genes were involved in extracellular matrix-receptor interactions and protein digestion pathways. In Cluster 3, the DEGs were downregulated in the luteal phase; they were strongly associated with cell cycle, calcium signalling, and oocyte meiosis. The gene expression in the oviduct during the oestrous cycle influenced oocyte transport and fertilisation. Our findings provide a basis for successfully breeding pigs and elucidating the mechanisms underlying the changes in the pig oviduct during the oestrous cycle.

HPV post-infection microenvironment and cervical cancer

Human papillomavirus (HPV) is the most common sexually transmitted virus worldwide. More than 99% of cervical cancer cases are associated with certain types of HPVs, termed high-risk types. In addition to the well-known transformative properties, HPVs-infected cells actively instruct the local milieu and create a supportive post-infection microenvironment (PIM), which is becoming recognized as a key factor for the viral persistence, propagation, and malignant progression. The PIM is initiated and established via a complex interplay among virus-infected cells, immune cells, and host stroma, as well as their derived components including chemokines, cytokines, extracellular vesicles, and metabolites. In this review, we summarize the current understanding of these key components, characteristics, and effects of the PIM, and highlights the prospect of targeting the PIM as a potential strategy to improve therapeutic outcomes for cervical cancer.

Expression and localisation of epidermal growth factor receptors and their ligands in the lower genital tract of cycling cows

The epidermal growth factor receptor (ErbB) family and its ligands are essential for the regulation of multiple cellular processes required for mammalian reproduction. The objectives of this study were to investigate the expression and localisation of ErbB subtypes (ErbB1-4) and selected ligands, namely epidermal growth factor (EGF), amphiregulin (AREG) and neuregulin (NRG), in the cervix and vagina of cycling cows and to determine possible steroid hormone-dependence of their expression using immunohistochemistry. All four ErbBs and EGF, AREG and NRG proteins were found to be localised in the nucleus and cytoplasm of different cells in the cervix and vagina, and their expression differed during the oestrous cycle. During the follicular phase, in both the cervix and vagina, ErbB1, ErbB2, ErbB3, ErbB4 and EGF expression was higher in the luminal epithelium (LE) than in stromal and smooth muscle (SM) cells (P<0.05). During the luteal phase, the expression of ErbB1, ErbB3 and EGF in the LE was significantly different from that in stromal and SM cells in the cervix, whereas the expression of EGF and AREG differed in the vagina compared to the cervix (P<0.05). Throughout the oestrous cycle, in both the cervix and vagina, although ErbB2/human epidermal growth factor receptor 2 expression in the LE and SM cells was significantly higher than in the stromal cells (P<0.05), NRG expression was similar in the LE, stromal and SM cells (P>0.05). Overall, these results suggest that all four ErbBs and the EGF, AREG and NRG proteins may collectively contribute to several cellular processes in the bovine cervix and vagina during the oestrous cycle.

Cyclical cervical function in the mare involves remodelling of collagen content, which is correlated with modification of oestrogen receptor 1 abundance

This study was conducted to elucidate mare cervical dilation mechanisms by testing two hypotheses: (i) the proportion of collagen staining in histological samples of mare cervices and (ii) the abundance of hormone receptors in the equine cervix differ with stage of the oestrous cycle and site within the cervix. Tissues and jugular vein blood samples were collected from 15 mares. Collagen content was assessed using Masson's Trichome staining. Receptor abundance was assessed using RT-PCR, qRT-PCR and immunohistochemistry. In sub-epithelial stroma, there was less collagen during the follicular than luteal phase, in the caudal- (P =  0.029), mid- (P =  0.0000) and cranial (P =  0.001) cervical tissue. In the deep stroma, there was less collagen staining during the follicular stage in the mid- (P =  0.004) and cranial- (P =  0.041) cervical regions. There were PTGER2, PTGER3, PGR and ESR1 mRNA transcripts in the cervix. A greater proportion of cells were positive for ESR1 protein during the follicular phase in sub-epithelial (P =  0.019) and deep (P =  0.013) stroma. The abundance of ESR1 in the epithelium was negatively correlated with collagen staining in sub-epithelial (P =  0.007) and deep (P =  0.005) stroma. The results of the study provide new information about the cervical biology of mares by increasing the knowledge about collagen content and the relationship between collagen content and ESR1 protein abundance during the oestrous cycle which indicates the ESR1 receptor is a candidate for involvement in control of cervical dilation.

Collagen, glycosaminoglycans and matrix metalloproteinase-2 and metalloproteinase-9 in the cervix of the ewe during prepubertal development

The tortuous nature of the ovine cervix restricts the transcervical passage of the cannula, and many studies have aimed to understand the endocrine mechanism of the remodelling of cervical tissue in adult ewe. However, little is known about the remodelling of the cervical tissue during the prepubertal development of the lambs. To obtain histochemical and biochemical evidence about the nature of the prepubertal development of the cervix of the ewe, cervices of Corriedale lambs obtained at 0, 1, 2, 4, 6 and 8 months of age (n = 5 to 6 in each) were processed. Neutral and acidic glycosaminoglycans (by PAS-Alcian stain) were weakly in the cervical stroma and not shown change during the development, whereas the percentage volume of fibrillar collagen (by van Gieson stain) increases throughout the experimental period in the superficial fold stroma and deep wall stroma (p < 0.05). The relative cervical weight (g/kg of body weight) and the collagen concentration (by spectrophotometry, mg/mg wet tissue) showed an early decreasing phase from months 0 to 4 and a later increasing phase from months 4 to 8 (p < 0.05). The latent form of matrix metalloproteinase-2 (MMP-2) detected by gelatin zymography (ng/mg protein) decreased from months 0 to 2 and increased from months 4 to 8, whereas the activated form decreased from months 0 to 2, remained low until month 6 and then recovered on month 8 (p < 0.0001). Data suggest that the relative cervical weight biphasic pattern during the development is related to MMP-2-dependent changes in the collagen content.

Evaluating residual strain throughout the murine female reproductive system

Mounting evidence suggests that cells within soft tissues seek to maintain a preferred biomechanical state. Residual stress is defined as the stress that remains in a tissue when all external loads are removed and contributes to tissue mechanohomeostasis by decreasing the transmural gradient of wall stress. Current computational models of pelvic floor mechanics, however, often do not consider residual stress. Residual strain, a result of residual stress can be quantitatively measured through opening angle experiments. Therefore, the objective of this study is to quantify the regional variations in opening angles along the murine female reproductive system at estrus and diestrus, to quantify residual strain in the maintenance state of sexually mature females. Further, evidence suggests that hydrophilic glycosaminoglycan/proteoglycans are integral to cervical remodeling. Thus, variations in opening angles following hypo-osmotic loading are evaluated. Opening angle experiments were performed along the murine reproductive system in estrus (n = 8) and diestrus (n = 8) and placed in hypo-osmotic solution. Measurements of thickness and volume were also obtained for each group. Differences (p < 0.05) in opening angle were observed with respect to region and loading, however, differences with respect to estrous stage were not significant. Thickness values were significant (p < 0.05) with respect to region only. The effects of both estrous cycle and region resulted in significant differences (p < 0.05) in observed volume. The observed regional differences indicate variation in the stress-free state among the reproductive system which may have implications for future computational models to advance women's reproductive health.

Priming anoestrous Corriedale ewes with progesterone and gonadotrophin-releasing hormone causes cervical tissue remodelling due to metalloproteinase-2 (MMP-2) activity

The aim was to obtain experimental evidence of cervical collagen degradation in anoestrous Corriedale adult ewes induced to ovulate with progesterone (P) and gonadotrophin-releasing hormone (GnRH), at the expected time of induced ovulation and early luteal phase. In Experiment 1, anoestrous ewes were treated with P for 10 days (P, n = 4), with nine micro-doses of GnRH followed by a GnRH bolus injection (GnRH, n = 4) or with P plus GnRH treatments (P+GnRH, n = 3), and cervices were obtained either without treatment (A, n = 4), when P was removed, or 24 h after the GnRH bolus injection. In Experiment 2, cervices were obtained 1 (group P+GnRH, n = 5) or 5 (P+GnRH 5, n = 6) days after the GnRH bolus injection with P pretreatment. MMP-2 activity was detected in all samples; however, MMP-9 activity was only detected in 15% of the samples. The activity of the latent (L) form of MMP-2 in the cranial zone of group A was higher than in the cranial zone of groups P, GnRH and P+GnRH, and was also higher than that in the caudal zone of the same group (P < 0.05). The collagen concentration was lower in group P+GnRH 1 than in group P+GnRH 5 (P < 0.04). The activity of the activated (A) form of MMP-2 and the A/L MMP-2 ratio were higher in group P+GnRH 1 than in group P+GnRH 5 (P < 0.05). Data suggest that the L form of MMP-2 was expressed mainly in a constitutive form in the cervix of anoestrous ewes and that an oestrogen-dependent activation mechanisms due to the GnRH treatment may be responsible for the lowest collagen content at the moment of the induced ovulation. This work provides evidence about cervical collagen remodelling in anoestrous ewes treated with P + GnRH.